CN1311086C

CN1311086C - Highly clean steel and production method

Info

Publication number: CN1311086C
Application number: CNB2005100785775A
Authority: CN
Inventors: 佐藤一郎; 石堂嘉一郎; 森知巳; 入江敏弘; 儿玉和哉; 川上洁; 北野修平
Original assignee: Sanyo Special Steel Co Ltd
Current assignee: Sanyo Special Steel Co Ltd
Priority date: 2000-06-05
Filing date: 2001-06-05
Publication date: 2007-04-18
Anticipated expiration: 2021-06-05
Also published as: CN1966732A; CN1966731A; CN1690229A; CN100523251C; CN1966751A; JP2001342512A

Abstract

A process for producing a high-cleanliness steel, comprising the steps of: transferring a molten steel produced in an arc melting furnace or a converter to a ladle furnace to refine the molten steel; degassing the molten steel; and then casting the molten steel into an ingot, said process further comprising the step of tapping deoxidation wherein, in transferring the molten steel to the ladle furnace, a deoxidizer including manganese, aluminum, and silicon is added to the molten steel by previously placing the deoxidizer in the ladle, and/or by adding the deoxidizer to the molten steel in the course of tapping into the ladle, whereby the molten steel is pre-deoxidized before the refining in the ladle furnace.

Description

Cleanness steel and production method thereof

The application is dividing an application of Chinese patent application 01810730.3 (applying date being June 5 calendar year 2001, and exercise question is " cleanness steel and a production method thereof ", and international application no is PCT/JP01/04742, and priority date is on June 5th, 2000).

Technical field

The present invention relates to a kind of cleanness steel, it is suitable for the machine steel of making to require to have fatigue strength, fatigue lifetime and calm degree (quietness), particularly suitable is done as rolling bearing with steel, constant speed tieing with steel, gear steel, annular continuous change transmission to the invention still further relates to the production method of cleanness steel with steel, the steel for mechanical structure that is used for cold forging, tool steel and spring steel.

The machine steel that requirement has fatigue strength and fatigue lifetime should be high-cleanness, high (the nonmetal inclusion body burden in the steel is a low) steel.The conventional production methods of these cleanness steels comprises: (A) oxidation refining molten steel in electrometal furnace or converter; (B) reduction refining in ladle (ladle) stove (LF); (C) in circulating vacuum degasser (RH), carry out the circulating vacuum degassing (RH processing); (D) with continuous casting or traditional ingot casting method teeming; (E), then product made from steel is heat-treated by press forging method processing steel ingot.In step (A),, perhaps molten steel is added and carrying out then molten steel being transferred in the ladle furnace in the converter of oxidation refining by the electric-arc heating melting waste steel.Temperature when shifting molten steel generally is the high temperature than high about 30-100 ℃ of the fusing point of steel.In step (B), alloy deoxidizers such as aluminium, manganese, silicon join in the ladle furnace that moves into molten steel, utilize deoxygenation to carry out reduction refining here, and carry out desulphurization reaction to regulate the alloy formation with sweetening agent.Generally everybody thinks that treatment effect increases with the prolongation of the time of processing.Adopt to surpass 60 minutes very long treatment time in this step, treatment temp is generally high 50 ℃ than the fusing point of steel.In the RH of step (C) handles, in the circulating vacuum degassing vessel, carry out vacuum outgas, pass through circulating vacuum degassing vessel circulation molten steel simultaneously with deoxidation and dehydrogenation.In this case, the internal circulating load of molten steel be about the molten steel total amount 5-6 doubly.In step (D), the molten steel after RH handles is transferred in the tundish, continuous casting of molten steel is become Steel Bloom, blank, slab etc. here.Also the molten steel in the ladle furnace directly can be injected ingot mold and be cast into steel ingot.In step (E), rolling or forge as Steel Bloom, blank, slab or steel ingot, heat-treat then and make the product made from steel that can subsequently it be transported.

When needs have the steel of specific high-cleanness, high, in aforesaid method, with the casting steel ingot as raw material, carry out vacuum remelting or esr then to prepare these steel.

In recent years, mechanical component use under more and more harsher condition.This just has more and more harsher requirement to the performance of product made from steel, and this area need have the more product made from steel of high-cleanness, high.But above-mentioned conventional production methods (A)-(E) is difficult to satisfy such requirement.In order to satisfy such requirement, people produce these product made from steel by vacuum remelting or esr.But the problem that these methods exist is that production cost significantly improves.

Produced the present invention under these conditions, the objective of the invention is under the situation that does not rely on remelting processing, to provide product made from steel with high-cleanness, high.

Disclosure of the Invention

In order to achieve the above object, the present inventor has carried out extensive and deep research to the production method of cleanness steel.They find can significantly improve with following method the cleanliness factor of steel as a result.

First invention

The method that the present invention solves existing the problems referred to above in the prior art is described below.In the traditional method of using refining furnace such as electrometal furnace or converter, fusing and oxidation refining are mainly carried out in as electrometal furnace or converter, and reduction process (deoxygenation) is carried out in ladle refining furnace.On the other hand, first invention relates to the production method of cleanness steel, and it comprises the steps: the molten steel that generates in electrometal furnace or the converter is transferred to refined molten steel in the ladle furnace; With liquid steel degassing, preferably carry out circulating vacuum outgas; Then molten steel casting is become steel ingot, wherein add the reductor (alloy form of manganese, aluminium, silicon etc. is unimportant) that comprises manganese, aluminium and silicon, the add-on of pure basic reductor is not less than 1kg in the molten steel per ton, the adding mode is in advance reductor to be placed ladle furnace, and/or in the process of the molten steel in electrometal furnace or the converter being transferred in the ladle furnace, reductor is joined in the molten steel, and add slag former such as CaO in some cases simultaneously and carry out tapping deoxidization, wherein, molten steel carries out carrying out pre-deoxidation before the reduction refining in ladle furnace.

According to first preferred embodiment of the present invention, it is that the tapping temperature of molten steel is higher at least 100 ℃ than the fusing point of steel that molten steel is transferred to condition in the ladle furnace, preferably high at least 120 ℃, and more preferably high at least 150 ℃.

Carrying out the purified time in ladle refining furnace is not more than 60 minutes, preferably is not more than 45 minutes, and more preferably 25-45 minute, the carrying out time of the degassing was not less than 25 minutes.Specifically, as you know: in circulating vacuum degasser, when the internal circulating load of molten steel is not less than 5 times of molten steel total amount, can access gratifying result.On the other hand, in the present invention, in circulating vacuum degasser, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount in the degasification process, and preferably big at least 10 times, more preferably big at least 15 times.

The present invention relates to cleanness steel with aforementioned production method production.

According to the present invention, the oxygen level in the steel preferably is not more than 10ppm.Preferably, when the carbon content in the steel was lower than 0.6% (quality), the oxygen level in the steel was not more than 8ppm.More preferably be that under the situation of C 〉=0.6% (quality), oxygen level is not more than 6ppm.

Preferably, in steel of the present invention, be not less than the oxide inclusion body of 20 μ m, for example Al by product made from steel being dissolved in the granularity that detects in the acid ₂O ₃The quantity that content is not less than 50% oxide inclusion body is not more than 40 in every 100g product made from steel, preferably be not more than 30, more preferably no more than 20.

In steel of the present invention, for example, when at 100mm ²Lip-deep 30 places of product made from steel when measuring maximum and being mingled with the body diameter, the 30000mm that obtains according to the statistical calculations of these extreme values ²The predictor that middle maximum is mingled with the body diameter is not more than 60 μ m, preferably is not more than 40 μ m, more preferably no more than 25 μ m.

Second invention

Second invention is described below.In the traditional method of using refining furnace such as electrometal furnace or converter, fusing and oxidation refining are mainly carried out in as electrometal furnace or converter, and reduction process (deoxygenation) is carried out in ladle refining furnace.On the other hand, the present invention relates to the production method of cleanness steel, it comprises the steps: the molten steel that generates in electrometal furnace or the converter transferred in the ladle and outgases, and preferably carries out circulating vacuum outgas; Molten steel after the degassing is transferred to refined molten steel in the ladle furnace; Outgas again, preferably in circulating vacuum degasser, carry out circulating vacuum outgas.

According to a preferred embodiment of the invention, it is that the tapping temperature of molten steel is higher at least 100 ℃ than the fusing point of steel that molten steel is transferred to condition in the ladle, preferably high at least 120 ℃, and more preferably high at least 150 ℃.

Carrying out the purified time in ladle furnace is not more than 60 minutes, preferably is not more than 45 minutes, and more preferably 25-45 minute, the carrying out time of the degassing was not less than 25 minutes.Specifically, as you know: in circulating vacuum degasser, when the internal circulating load of molten steel is not less than 5 times of molten steel total amount, can access gratifying result.On the other hand, in the present invention, in circulating vacuum degasser, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount in the degasification process, and preferably big at least 10 times, more preferably big at least 15 times.

The 3rd invention

The 3rd invention is described below.In the traditional method of using refining furnace such as electrometal furnace or converter, fusing and oxidation refining are mainly carried out in as electrometal furnace or converter, and reduction process (deoxygenation) is carried out in ladle refining furnace.On the other hand, the present invention relates to the production method of cleanness steel, it comprises the steps: oxidation refining molten steel in electrometal furnace or converter; Add the reductor (alloy form of manganese, silicon, aluminium etc. is unimportant) that comprises manganese, silicon and aluminium before the molten steel tapping, make deoxidation of molten steel in same stove in molten steel, the add-on of reductor is not less than 2kg in the molten steel per ton; Molten steel after the deoxidation transferred to carry out ladle refining in the ladle furnace; Then by circulating vacuum degasser circulation molten steel after refining, with liquid steel degassing.

According to a preferred embodiment of the invention, it is that the tapping temperature of molten steel is higher at least 100 ℃ than the fusing point of steel that molten steel is transferred to condition in the ladle furnace, preferably high at least 120 ℃, and more preferably high at least 150 ℃.

According to the present invention, in ladle furnace, carry out the purified time preferably to be not more than 60 minutes, preferably be not more than 45 minutes, more preferably 25-45 minute.Carry out in circulating vacuum degasser as the degassing step 1 after this step, the internal circulating load of molten steel is not less than 5 times of molten steel total amount.On the other hand, in the present invention, in circulating vacuum degasser, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount in the degasification process, and preferably big at least 10 times, more preferably big at least 15 times, the degassing time is 25 minutes at least.

The 4th invention

The 4th invention is described below.In the traditional method of using refining furnace such as electrometal furnace or converter, fusing and oxidation refining are mainly carried out in as electrometal furnace or converter, and reduction process (deoxygenation) is carried out in ladle refining furnace.On the other hand, the present invention relates to the production method of cleanness steel, it comprises the steps: the molten steel that generates in electrometal furnace or the converter is transferred to refined molten steel in the ladle furnace; Molten steel after refining is carried out circulating vacuum outgas; Molten steel casting after will outgasing then becomes steel ingot, wherein, carrying out the purified time in ladle furnace is not more than 60 minutes, preferably be not more than 45 minutes, more preferably 45-25 minute, internal circulating load at molten steel is not less than in the circulating vacuum degasser of 5 times of molten steel total amounts, and the time of carrying out of the degassing after the refinement step generally is lower than 25 minutes.But in the present invention, in circulating vacuum degasser, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount in the degasification process, and preferably big at least 10 times, more preferably big at least 15 times, the degassing time is 25 minutes at least.

The 5th invention

The 5th invention is described below.In the traditional method of using refining furnace such as electrometal furnace or converter, fusing and oxidation refining are mainly carried out in as electrometal furnace or converter, and reduction process (deoxygenation) is carried out in ladle refining furnace.On the other hand, the present invention relates to the production method of cleanness steel, it comprises the steps: the molten steel that generates in electrometal furnace or the converter transferred in the ladle as the refining furnace of coming out of the stove (out-furnace refining furnace) and carries out refining; Molten steel is carried out the circulating ladle degassing; Molten steel casting after will outgasing then becomes steel ingot, wherein, carrying out the purified condition in ladle is: except using from the gas of ladle bottom introducing stirs, also stir by electromagnetic induction, the time that ladle refining carries out is 50-80 minute, preferred 70-80 minute.

According to the present invention, preferably in inert atmosphere, in ladle, carry out ladle refining by gas stirring and induction stirring.

The accompanying drawing summary

Figure 1A is the graph of a relation that carries out or do not carry out oxygen level in SUJ 2 steel of tapping deoxidization and the product, wherein, and A ₁The data that only adopt the tapping deoxidization of claim 1 definition according to the present invention are shown, A ₂The data of the tapping deoxidization+high temperature tapping of employing claim 2 definition according to the present invention are shown, A ₃The data that the tapping deoxidization+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, A ₄The data that the tapping deoxidization+high temperature tapping+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, traditional data of the prior art also is shown among Figure 1A;

Figure 1B is the graph of a relation that carries out or do not carry out oxygen level in SCM 435 steel of tapping deoxidization and the product, wherein, and B ₁The data that only adopt the tapping deoxidization of claim 1 definition according to the present invention are shown, B ₂The data of the tapping deoxidization+high temperature tapping of employing claim 2 definition according to the present invention are shown, B ₃The data that the tapping deoxidization+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, B ₄The data that the tapping deoxidization+high temperature tapping+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, traditional data of the prior art also is shown among Figure 1B;

Fig. 1 C carries out or does not carry out SUJ 2 steel of tapping deoxidization and the graph of a relation that maximum predicted is mingled with the body diameter, wherein, and A ₁The data that only adopt the tapping deoxidization of claim 1 definition according to the present invention are shown, A ₂The data of the tapping deoxidization+high temperature tapping of employing claim 2 definition according to the present invention are shown, A ₃The data that the tapping deoxidization+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, A ₄The data that the tapping deoxidization+high temperature tapping+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, traditional data of the prior art also is shown among Fig. 1 C;

Fig. 1 D carries out or does not carry out SCM 435 steel of tapping deoxidization and the graph of a relation that maximum predicted is mingled with the body diameter, wherein, and B ₁The data that only adopt the tapping deoxidization of claim 1 definition according to the present invention are shown, B ₂The data of the tapping deoxidization+high temperature tapping of employing claim 2 definition according to the present invention are shown, B ₃The data that the tapping deoxidization+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, B ₄The data that the tapping deoxidization+high temperature tapping+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, traditional data of the prior art also is shown among Fig. 1 D;

Fig. 1 E is SUJ 2 steel and the L that carries out or do not carry out tapping deoxidization ₁₀Life relation figure, wherein, A ₁The data that only adopt the tapping deoxidization of claim 1 definition according to the present invention are shown, A ₂The data of the tapping deoxidization+high temperature tapping of employing claim 2 definition according to the present invention are shown, A ₃The data that the tapping deoxidization+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, A ₄The data that the tapping deoxidization+high temperature tapping+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, traditional data of the prior art also is shown among Fig. 1 E;

Fig. 1 F is SCM 435 steel and the L that carries out or do not carry out tapping deoxidization ₁₀Life relation figure, wherein, B ₁The data that only adopt the tapping deoxidization of claim 1 definition according to the present invention are shown, B ₂The data of the tapping deoxidization+high temperature tapping of employing claim 2 definition according to the present invention are shown, B ₃The data that the tapping deoxidization+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, B ₄The data that the tapping deoxidization+high temperature tapping+short period of time LF of employing claim 3 definition according to the present invention, long-time RH handle are shown, traditional data of the prior art also is shown among Fig. 1 F;

Fig. 2 A is the graph of a relation that carries out or do not carry out oxygen level in SUJ 2 steel that W-RH handles and the product, wherein, and A ₁The data that only adopt W-RH of the present invention to handle are shown, A ₂The data that adopt W-RH processing+high temperature tapping of the present invention are shown, A ₃The data that adopt W-RH processing+short period of time LF of the present invention, long-time RH to handle are shown, A ₄The data that adopt W-RH processing+high temperature tapping+short period of time LF of the present invention, long-time RH to handle are shown, traditional data of the prior art also is shown among Fig. 2 A;

Fig. 2 B is the graph of a relation that carries out or do not carry out oxygen level in SCM 435 steel that W-RH handles and the product, wherein, and B ₁The data that only adopt W-RH of the present invention to handle are shown, B ₂The data that adopt W-RH processing+high temperature tapping of the present invention are shown, B ₃The data that adopt W-RH processing+short period of time LF of the present invention, long-time RH to handle are shown, B ₄The data that adopt W-RH processing+high temperature tapping+short period of time LF of the present invention, long-time RH to handle are shown, traditional data of the prior art also is shown among Fig. 2 B;

Fig. 2 C is the graph of a relation that W-RH treatment S UJ 2 steel that carry out or do not carry out and maximum predicted are mingled with the body diameter, wherein, and A ₁The data that only adopt W-RH of the present invention to handle are shown, A ₂The data that adopt W-RH processing+high temperature tapping of the present invention are shown, A ₃The data that adopt W-RH processing+short period of time LF of the present invention, long-time RH to handle are shown, A ₄The data that adopt W-RH processing+high temperature tapping+short period of time LF of the present invention, long-time RH to handle are shown, traditional data of the prior art also is shown among Fig. 2 C;

Fig. 2 D carries out or does not carry out SCM 435 steel of W-RH processing and the graph of a relation that maximum predicted is mingled with the body diameter, wherein, and B ₁The data that only adopt W-RH of the present invention to handle are shown, B ₂The data that adopt W-RH processing+high temperature tapping of the present invention are shown, B ₃The data that adopt W-RH processing+short period of time LF of the present invention, long-time RH to handle are shown, B ₄The data that adopt W-RH processing+high temperature tapping+short period of time LF of the present invention, long-time RH to handle are shown, traditional data of the prior art also is shown among Fig. 2 D;

Fig. 2 E carries out or does not carry out SUJ 2 steel and the L that W-RH handles ₁₀Life relation figure, wherein, A ₁The data that only adopt W-RH of the present invention to handle are shown, A ₂The data that adopt W-RH processing+high temperature tapping of the present invention are shown, A ₃The data that adopt W-RH processing+short period of time LF of the present invention, long-time RH to handle are shown, A ₄The data that adopt W-RH processing+high temperature tapping+short period of time LF of the present invention, long-time RH to handle are shown, traditional data of the prior art also is shown among Fig. 2 E;

Fig. 2 F is SCM 435 steel and the L that carries out or do not carry out tapping deoxidization ₁₀Life relation figure, wherein, B ₁The data that only adopt W-RH of the present invention to handle are shown, B ₂The data that adopt W-RH processing+high temperature tapping of the present invention are shown, B ₃The data that adopt W-RH processing+short period of time LF of the present invention, long-time RH to handle are shown, B ₄The data that adopt W-RH processing+high temperature tapping+short period of time LF of the present invention, long-time RH to handle are shown, traditional data of the prior art also is shown among Fig. 2 F;

Fig. 3 A illustrates the method according to this invention is carried out oxygen level in 10 stove SUJ, 2 product made from steel of deoxidation in the stove in handling the molten steel process broken line graph, and Fig. 3 A also illustrates according to traditional method and do not carry out oxygen level in 10 stove SUJ, 2 product made from steel of deoxidation in the stove;

Fig. 3 B illustrates the method according to this invention is carried out oxygen level in 10 stove SCM, 435 product made from steel of deoxidation in the stove in handling the molten steel process broken line graph, and Fig. 3 B also illustrates according to traditional method and do not carry out oxygen level in 10 stove SCM, 435 product made from steel of deoxidation in the stove;

Fig. 3 C illustrates the broken line graph that the method according to this invention carries out obtaining according to these statisticss of extremes in 10 stove SUJ, 2 product made from steel of deoxidation in the stove in handling the molten steel process maximum predicted is mingled with the body diameter, and Fig. 3 C also illustrates the maximum predicted of not carrying out in 10 stove SUJ, 2 product made from steel of deoxidation in the stove according to traditional method and is mingled with the body diameter;

Fig. 3 D illustrates the broken line graph that the method according to this invention carries out obtaining according to these statisticss of extremes in 10 stove SCM, 435 product made from steel of deoxidation in the stove in handling the molten steel process maximum predicted is mingled with the body diameter, and Fig. 3 C also illustrates the maximum predicted of not carrying out in 10 stove SCM, 435 product made from steel of deoxidation in the stove according to traditional method and is mingled with the body diameter;

Fig. 3 E illustrates the method according to this invention is carried out 10 stove SUJ, 2 product made from steel of deoxidation in the stove in handling the molten steel process the L according to tappet roller measuring in work-ing life ₁₀The broken line graph in life-span, Fig. 3 E also illustrate the L that does not carry out 10 stove SUJ, 2 product made from steel of deoxidation in the stove according to traditional method ₁₀Life-span;

Fig. 3 F illustrates the method according to this invention is carried out 10 stove SCM, 435 product made from steel of deoxidation in the stove in handling the molten steel process the L according to tappet roller work-ing life (thrust rolling service life) measuring ₁₀The broken line graph in life-span, Fig. 3 E also illustrate the L that does not carry out 10 stove SCM, 435 product made from steel of deoxidation in the stove according to traditional method ₁₀Life-span;

Fig. 4 A illustrates the method according to this invention is carried out oxygen level in short period of time LF handles and long-time RH handles 10 stove SUJ, 2 product made from steel in handling the molten steel process broken line graph, Fig. 4 A also illustrate according to traditional method carry out that long-time LF handles and 10 stove SUJ, 2 product made from steel of short period of time RH processing in oxygen level;

Fig. 4 B illustrates the method according to this invention is carried out oxygen level in short period of time LF handles and long-time RH handles 10 stove SCM, 435 product made from steel in handling the molten steel process broken line graph, Fig. 4 A also illustrate according to traditional method carry out that long-time LF handles and 10 stove SCM, 435 product made from steel of short period of time RH processing in oxygen level;

Fig. 4 C illustrates the broken line graph that the method according to this invention carries out obtaining according to these statisticss of extremes in short period of time LF handles and long-time RH handles 10 stove SUJ, 2 product made from steel in handling the molten steel process maximum predicted is mingled with the body diameter, Fig. 4 C also illustrate according to traditional method carry out that long-time LF handles and 10 stove SUJ, 2 product made from steel of short period of time RH processing in maximum predicted be mingled with the body diameter;

Fig. 4 D illustrates the broken line graph that the method according to this invention carries out obtaining according to these statisticss of extremes in short period of time LF handles and long-time RH handles 10 stove SCM, 435 product made from steel in handling the molten steel process maximum predicted is mingled with the body diameter, Fig. 4 C also illustrate according to traditional method carry out that long-time LF handles and 10 stove SCM, 435 product made from steel of short period of time RH processing in maximum predicted be mingled with the body diameter;

Fig. 4 E illustrates the method according to this invention to carry out the L according to tappet roller measuring in work-ing life that short period of time LF handles 10 stove SUJ, 2 product made from steel of handling with long-time RH in handling the molten steel process ₁₀The broken line graph in life-span, Fig. 3 E also illustrate the L that carries out 10 stove SUJ, 2 product made from steel of long-time LF processing and short period of time RH processing according to traditional method ₁₀Life-span;

Fig. 4 F illustrates the method according to this invention to carry out the L according to tappet roller measuring in work-ing life that short period of time LF handles 10 stove SCM, 435 product made from steel of handling with long-time RH in handling the molten steel process ₁₀The broken line graph in life-span, Fig. 3 E also illustrate the L that carries out 10 stove SCM, 435 product made from steel of long-time LF processing and short period of time RH processing according to traditional method ₁₀Life-span.

Optimum implementation of the present invention

First invention

According to first invention, the preferred production process of cleanness steel comprises the steps (1)-(5):

(1) in traditional steel production method of using refining furnace such as electrometal furnace or converter, fusing and oxidation refining are mainly carried out in electrometal furnace or converter, and reduction process (deoxygenation) is carried out in ladle refining furnace.On the other hand, according to the present invention, oxidation refining molten steel in electrometal furnace or converter.Make molten steel have predetermined chemical constitution and preset temperature then, in process that molten steel is come out of the stove from smelting furnace, add the reductor (alloy form of manganese, aluminium, silicon etc. is unimportant) that comprises manganese, aluminium and silicon, the add-on of pure basic reductor is not less than 1kg in the molten steel per ton, the adding mode is in advance reductor to be placed ladle, and/or in the process of molten steel being transferred in the ladle furnace, reductor is joined in the molten steel, and add slag former such as CaO simultaneously in some cases.Adding reductor is most crucial steps in the present invention.Before ladle refining, add reductor (thought in the past and there is no need) to reduce the production that oxygen level can finally realize having the steel of low oxygen content before the reduction refining in ladle furnace to a certain extent.Its reason is as follows: the dissolved oxygen amount in molten steel is that the deoxygenation that carries out in the system of the gratifying 100ppm of being not less than can form more deoxidation product, and these deoxidation products are easy to flotation and separate.Therefore, the total content of steel water oxygen can significantly reduce, and drops to and is not more than 50ppm.

(2) the pre-deoxidation molten steel is transferred in the ladle furnace, in ladle furnace, carried out reduction refining, and regulate the chemical constitution of steel.

(3) will carry out the liquid steel degassing that reduction refining and chemical constitution are regulated, and particularly carry out circulating degasification, and finally regulate the chemical constitution of steel by circulating vacuum degasser.

(4) will carry out the degassing and become steel ingot with the molten steel casting that final chemical constitution is regulated.

(5) the steel ingot press forging is become shape of product, can randomly heat-treat then, produce product made from steel.

In preferred production process according to cleanness steel of the present invention, in step (1)-(5), the mode of molten steel being transferred to the step (2) in the ladle furnace is: though the tapping temperature of molten steel is generally than high about 50 ℃ of the fusing point of steel, but in the present invention, the tapping temperature of molten steel is higher at least 100 ℃ than the fusing point of steel, preferably high at least 120 ℃, more preferably high at least 150 ℃.The reductor that adds in when tapping and formerly handle in the dissolving or separates therefore and fully of the metal that adds and slag, so can prevent because separation and splash into metal in the molten steel or oxygen level rising that slag causes under the preliminary refining state in the ladle refining process.In refining furnace, can improve simultaneously initial slagging performance and reactivity.Specifically, formerly handle and current the processing between during in oxidation sedimentary reducing metal in formerly handling, in current reduction period was operated, when metal began to dissolve, particularly when the reduction period EO, equilibrium state was broken.The result is that the molten steel part is contaminated.Therefore, in the molten steel that sedimentary dissolving metal is come out of the stove before reduction, this dissolved metal and the molten steel of coming out of the stove are together by deoxidation.

In above-mentioned steps, though think all that generally the refining time that surpasses 60 minutes can produce effect preferably, but in preferred production process according to cleanness steel of the present invention, carrying out the purified time in ladle refining furnace is not more than 60 minutes, preferably be not more than 45 minutes, more preferably 25-45 minute, though generally think that all the degassing time that is less than 25 minutes is enough to produce gratifying result, but in preferred production methods of the present invention, the carrying out time of the degassing was not less than 25 minutes.Specifically, as you know: when the internal circulating load of molten steel is about 5 times of molten steel total amount, can access gratifying result.But on the other hand, in the present invention, in circulating vacuum degasser, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount in the degasification process, preferably big at least 10 times, and more preferably big at least 15 times.Utilize such being provided with carry out when can make heating the purified ladle refining time be minimum in case of necessity between, the flotation separation time that in not relating to the degassing step of heating, can guarantee the oxide inclusion body.This can prevent from can prevent that granularity is not less than the formation that is mingled with body greatly of about 20 μ m simultaneously owing to the rising that is subjected to the oxygen level that refractory materials on the ladle furnace inwall or scoriaceous pollution cause.In circulating vacuum outgas, particularly because nozzle is immersed in the molten steel and the molten steel that only circulates, so the slag on the molten steel upper surface is in gratifying stationary state.Therefore, enter oxide inclusion body number the molten steel from slag and be less than oxide inclusion body number in the reduction process of in ladle refining furnace, carrying out.Therefore, in the pre-deoxidation molten steel, adopt the gratifying long degassing time can significantly reduce even less deoxidation product.

According to the present invention, cleanness steel preferably particularly has the cleanness steel of outstanding rolling fatigue life, it is characterized in that: the oxygen level in the steel is not more than 10ppm; Preferably, when the carbon content in the steel was lower than 0.6% (quality), the oxygen level in the steel was not more than 8ppm; More preferably be that under the situation of C 〉=0.6% (quality), oxygen level is not more than 6ppm.Reduce oxygen level as you know and help to improve rolling fatigue life.In the steel of producing with method of the present invention, oxygen level is not more than 10ppm, preferably, when the C in the steel＜0.6% (quality), oxygen level is not more than 8ppm, more preferably be that under the situation of C 〉=0.6% (quality), the cleanness steel that oxygen level is not more than 6ppm stably demonstrates outstanding rolling fatigue life.

In above-mentioned cleanness steel, the invention still further relates to the cleanness steel of have outstanding rolling fatigue life (rollingfatigue life) and fatigue strength, it is characterized in that: be not less than the oxide inclusion body of 20 μ m, for example Al by product made from steel being dissolved in the granularity that detects in the acid ₂O ₃The quantity that content is not less than 50% oxide inclusion body is not more than 40 in every 100g product made from steel, preferably be not more than 30, more preferably no more than 20.This measuring method of product made from steel has reflected that oxygen level and the maximum in the pre-determined volume is mingled with the body diameter.As for fatigue strength, fatigue lifetime and calm degree, in the same steel of oxygen level, the oxide inclusion body of volume particle size is deleterious, and specifically, the oxide inclusion body that granularity is not less than 20 μ m is deleterious.Therefore, in the steel of producing with method of the present invention, product made from steel is dissolved in the quantity that the granularity that detects in the acid is not less than the oxide inclusion body of 20 μ m in every 100g product made from steel, is not more than 40, preferably be not more than 30, the steel more preferably no more than 20 is the cleanness steel with outstanding rolling fatigue life and outstanding fatigue strength and outstanding calm degree.

Cleanness steel of the present invention also comprises the cleanness steel of particularly have outstanding rotoflector fatigue strength (rotating bending fatigue strength) and cyclic stress fatigue strength (cyclestress fatigue strength), it is characterized in that: when at 100mm ²The product made from steel cross section on 30 places when measuring maximum and being mingled with the body diameter, the 30000mm that obtains according to the statistical calculations of these extreme values ²The predictor that middle maximum is mingled with the body diameter is not more than 60 μ m, preferably is not more than 40 μ m, more preferably no more than 25 μ m.As you know: cyclic stress fatigue strength and safe range of stress depend on that to a great extent the maximum in the pre-determined volume is mingled with the body diameter.This is disclosed in Japan's special permission publication 194121/1999, and the applicant of this patent is identical with applicant of the present invention.For example, generally work as at 100mm ²The product made from steel cross section on 30 places when measuring maximum and being mingled with the body diameter, the 30000mm that obtains according to the statistical calculations of these extreme values ²In the maximum predictor that is mingled with the body diameter be not more than 60 μ m, preferably be not more than 40 μ m, stably demonstrate outstanding fatigue strength more preferably no more than the cleanness steel of 25 μ m.In this case, oxygen level in the cleanness steel is not more than 10ppm, preferably, under the situation of the C in steel＜0.6% (quality), oxygen level is not more than 8ppm, more preferably be, under the situation of C 〉=0.6% (quality), oxygen level is not more than 6ppm, and the predictor that maximum is mingled with the body diameter is not more than 60 μ m, preferably be not more than 40 μ m, more preferably no more than 25 μ m.The steel of producing with method of the present invention is the cleanness steel with outstanding rolling fatigue life and outstanding fatigue strength.Though acid dissolving is work very time-consuming and trouble, advantageously, the aforesaid method that does not carry out product made from steel dissolving processing can be examined under a microscope certain area and come statistical ground to predict that maximum is mingled with the body diameter, and this method is very simple.In addition, specifically, the fatigue that is caused as for the cyclic stress (cycle stress) of Compression and Expansion, as you know: being easy to the maximum diameter that is mingled with body that fracture place exists is the factor of very large decision intensity.This can statistical the method for this maximum diameter of ground prediction be useful.

Second invention

According to second invention, the preferred production process of cleanness steel comprises the steps (1)-(6):

(1) oxidation refining molten steel in electrometal furnace or converter, preparation have the molten steel of predetermined chemical composition and preset temperature.

(2) then molten steel is outgased in advance.Specifically, for example, the degas method of molten steel is that molten steel is circulated by circulating vacuum degasser.This degassing step is most important in the present invention.Generally be directly with the molten steel reduction refining of producing in the step (1) in ladle furnace.And the present invention is opposite, and molten steel is to outgas in advance before reduction refining.This pre-degassing can significantly improve the cleanliness factor of the steel that finally obtains.

(3) molten steel that reduction refining outgases in step (2) in ladle furnace and regulate its chemical constitution.

(4) will carry out the molten steel that reduction refining and chemical constitution regulate in step (3) and further outgas, method is by circulating vacuum degasser circulation molten steel, and the chemical constitution of finally regulating steel.

(5) will carry out the degassing and become steel ingot with the molten steel casting that final chemical constitution is regulated.

(6) the steel ingot press forging is become shape of product, can randomly heat-treat then, produce product made from steel.

In preferred production process according to cleanness steel of the present invention, in step (1)-(6), molten steel after the step (2) is being transferred to when carrying out step (3) in the ladle furnace, though the tapping temperature of molten steel is generally than high about 50 ℃ of the fusing point of steel, but in the present invention, the tapping temperature of molten steel is higher at least 100 ℃ than the fusing point of steel, and preferably high at least 120 ℃, more preferably high at least 150 ℃.In specification sheets of the present invention, coming out of the stove under the high temperature refers to the high temperature tapping.The reductor that adds in when tapping and formerly handle in the dissolving or separates therefore and fully of the metal that adds and slag, so can prevent because separation and splash into metal in the molten steel or oxygen level rising that slag causes under the preliminary refining state in the ladle refining process.In refining furnace, can improve simultaneously initial slagging performance and reactivity.Specifically, formerly handle and current the processing between during in oxidation sedimentary reducing metal in formerly handling, in current reduction period was operated, when metal began to dissolve, particularly when the reduction period EO, equilibrium state was broken.The result is that molten steel is partly polluted.Therefore, in the molten steel that sedimentary dissolving metal is come out of the stove before reduction, this dissolved metal and the molten steel of coming out of the stove are together by deoxidation.

In the ladle refining of step (3), though think all that generally the refining time that surpasses 60 minutes can produce effect preferably, but in the present invention, carrying out the purified time in the ladle furnace of step (3) is not more than 60 minutes, preferably be not more than 45 minutes, more preferably 25-45 minute, as for the degassing behind the ladle refining, though generally think that all the degassing time that is less than 25 minutes is enough to produce gratifying result, but in preferred production methods of the present invention, the carrying out time of the degassing was not less than 25 minutes.Specifically, as you know: when the internal circulating load of molten steel is about 5 times of molten steel total amount, can access gratifying result.But on the other hand, in preferred production process of the present invention, in circulating vacuum degasser, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount in the degasification process, preferably big at least 10 times, and more preferably big at least 15 times.Utilize such being provided with carry out when can make heating the purified ladle refining time be minimum in case of necessity between, the flotation separation time that in not relating to the degassing step of heating, can guarantee the oxide inclusion body.This can prevent from can prevent that granularity is not less than the formation that is mingled with body greatly of about 20 μ m simultaneously owing to the rising that is subjected to the oxygen level that refractory materials on the ladle furnace inwall or scoriaceous pollution cause.In circulating vacuum outgas, particularly because nozzle is immersed in the molten steel and the molten steel that only circulates, so the slag on the molten steel upper surface is in gratifying stationary state.Therefore, enter oxide inclusion body number the molten steel from slag and be less than oxide inclusion body number in the reduction process of in ladle refining furnace, carrying out.Therefore, in the pre-deoxidation molten steel, adopt the gratifying long degassing time can significantly reduce even less deoxidation product.In specification sheets of the present invention, this method is called short period of time LF, long-time RH processing or short LF, long RH and handles.

According to a preferred embodiment, draw together cleanness steel with the ladle that method of the present invention is produced with outstanding rolling fatigue life and fatigue strength, it is characterized in that: be not less than the oxide inclusion body of 20 μ m, for example Al by product made from steel being dissolved in the granularity that detects in the acid ₂O ₃The quantity that content is not less than 50% oxide inclusion body is not more than 40 in every 100g product made from steel, preferably be not more than 30, more preferably no more than 20.This measuring method of product made from steel has reflected that oxygen level and the maximum in the pre-determined volume is mingled with the body diameter.As for fatigue strength, fatigue lifetime and calm degree, in the same steel of oxygen level, the oxide inclusion body of volume particle size is deleterious, and specifically, the oxide inclusion body that granularity is not less than 20 μ m is deleterious.Therefore, in the steel of producing with method of the present invention, product made from steel is dissolved in the quantity that the granularity that detects in the acid is not less than the oxide inclusion body of 20 μ m in every 100g product made from steel, is not more than 40, preferably be not more than 30, the steel more preferably no more than 20 is the cleanness steel with outstanding rolling fatigue life and outstanding fatigue strength and outstanding calm degree.

According to a preferred embodiment, cleanness steel of the present invention also comprises the cleanness steel that particularly has outstanding rotoflector fatigue strength and cyclic stress fatigue strength, it is characterized in that: when at 100mm ²The product made from steel cross section on 30 places when measuring maximum and being mingled with the body diameter, the 30000mm that obtains according to the statistical calculations of these extreme values ²The predictor that middle maximum is mingled with the body diameter is not more than 60 μ m, preferably is not more than 40 μ m, more preferably no more than 25 μ m.As you know: cyclic stress fatigue strength and safe range of stress depend on that to a great extent the maximum in the pre-determined volume is mingled with the body diameter.This is disclosed in Japan's special permission publication 194121/1999, and the applicant of this patent is identical with applicant of the present invention.For example, generally work as at 100mm ²The product made from steel cross section on 30 places when measuring maximum and being mingled with the body diameter, the 30000mm that obtains according to the statistical calculations of these extreme values ²In the maximum predictor that is mingled with the body diameter be not more than 60 μ m, preferably be not more than 40 μ m, stably demonstrate outstanding fatigue strength more preferably no more than the cleanness steel of 25 μ m.In this case, oxygen level in the cleanness steel is not more than 10ppm, preferably, under the situation of the C in steel＜0.6% (quality), oxygen level is not more than 8ppm, more preferably be, under the situation of C 〉=0.6% (quality), oxygen level is not more than 6ppm, and the predictor that maximum is mingled with the body diameter is not more than 60 μ m, preferably be not more than 40 μ m, more preferably no more than 25 μ m.The steel of producing with method of the present invention is the cleanness steel with outstanding rolling fatigue life and outstanding fatigue strength.Though acid dissolving is work very time-consuming and trouble, advantageously, the aforesaid method that does not carry out product made from steel dissolving processing can be examined under a microscope certain area and come statistical ground to predict that maximum is mingled with the body diameter, and this method is very simple.In addition, specifically, as for the fatigue that cyclic stress caused of Compression and Expansion, as you know: at the maximum diameter that is mingled with body that is easy to fracture place existence is the factor of very large decision intensity.This can statistical the method for this maximum diameter of ground prediction be useful.

The 3rd invention

According to the 3rd invention, the preferred production process of cleanness steel comprises the steps (1)-(5):

(1) oxidation refining molten steel in electrometal furnace or converter.Add the reductor (alloy form of manganese, aluminium, silicon etc. is unimportant) that comprises manganese, silicon and aluminium then in same stove, the add-on of reductor is not less than 2kg in the molten steel per ton, and adds slag former such as CaO in some cases simultaneously with deoxidation of molten steel.Then the molten steel after the deoxidation is transferred in the ladle.Carrying out deoxidation in steel melting furnace such as electrometal furnace or converter is most crucial steps in the present invention.Deoxidation before ladle refining (thought in the past and there is no need) is to reduce the production that oxygen level can finally realize having the steel of low oxygen content to a certain extent before ladle refining.

(2) in ladle refining furnace, the molten steel of transferring in the ladle is carried out reduction refining, and regulate its chemical constitution.

(3) will carry out the liquid steel degassing that reduction refining and chemical constitution are regulated in step (2), method is by circulating vacuum degasser circulation molten steel, in addition, finally regulates the chemical constitution of steel.

(4) will in step (3), carry out the degassing and become steel ingot with the molten steel casting that final chemical constitution is regulated.

In preferred production process according to cleanness steel of the present invention, in step (1)-(5), as for the step of molten steel being transferred in the ladle furnace (1), though the tapping temperature of molten steel is generally than high about 50 ℃ of the fusing point of steel, but in the present invention, the tansition temperature of molten steel is higher at least 100 ℃ than the fusing point of steel, and preferably high at least 120 ℃, more preferably high at least 150 ℃.Utilize such being provided with to make that sedimentary metal is dissolved in the molten steel fully around the ladle, slag is flotation fully also, so can prevent owing to separate or splash into the oxygen level that metal in the molten steel or slag cause raise in the ladle refining process under the preliminary refining state.

According to a preferred embodiment, in the ladle refining of above-mentioned steps, though think all that generally the refining time that surpasses 60 minutes can produce effect preferably, but in the present invention, carrying out the purified time in ladle furnace is not more than 60 minutes, preferably be not more than 45 minutes, more preferably 25-45 minute, as for the degassing in the step (3), though generally think that all the degassing time that is less than 25 minutes is enough to produce gratifying result, promptly, generally all think: when being about 5 times of molten steel total amount, the internal circulating load of molten steel can access gratifying result, but in the present invention, in circulating vacuum degasser, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount, preferably big at least 10 times, more preferably big at least 15 times, to outgas for a long time, that is, be not less than 25 minutes the degassing.Utilize such being provided with carry out when can make heating the purified ladle refining time be minimum in case of necessity between, the flotation separation time that in not relating to the degassing step of heating, can guarantee the oxide inclusion body satisfactorily.This can prevent from can prevent that granularity is not less than the formation that is mingled with body greatly of about 20 μ m simultaneously owing to the rising that is subjected to the oxygen level that refractory materials on the ladle furnace inwall or scoriaceous pollution cause.In circulating vacuum outgas, particularly because nozzle is immersed in the molten steel and the molten steel that only circulates, so the slag on the molten steel upper surface is in gratifying stationary state.Therefore, enter oxide inclusion body number the molten steel from slag and be less than oxide inclusion body number in the reduction process of in ladle refining furnace, carrying out.Therefore, in the pre-deoxidation molten steel, adopt the gratifying long degassing time can significantly reduce even less deoxidation product.In specification sheets of the present invention, this method is called short period of time LF, long-time RH processing or short LF, long RH and handles.

According to a preferred embodiment, cleanness steel of the present invention is the cleanness steel that particularly has outstanding rolling fatigue life, it is characterized in that: the oxygen level in the steel is not more than 10ppm; Preferably, when the carbon content in the steel was lower than 0.6% (quality), the oxygen level in the steel was not more than 8ppm; More preferably be that under the situation of C 〉=0.6% (quality), oxygen level is not more than 6ppm.Reduce oxygen level as you know and help to improve rolling fatigue life.In the steel of producing with method of the present invention, oxygen level is not more than 10ppm, preferably, when the C in the steel＜0.6% (quality), oxygen level is not more than 8ppm, more preferably be that under the situation of C 〉=0.6% (quality), the cleanness steel that oxygen level is not more than 6ppm stably demonstrates outstanding rolling fatigue life.

According to a preferred embodiment, the steel of producing with method of the present invention also comprises the cleanness steel with outstanding rolling fatigue life and fatigue strength, it is characterized in that: be not less than the oxide inclusion body of 20 μ m, for example Al by product made from steel being dissolved in the granularity that detects in the acid ₂O ₃The quantity that content is not less than 50% oxide inclusion body is not more than 40 in every 100g product made from steel, preferably be not more than 30, more preferably no more than 20.This measuring method of product made from steel has reflected that oxygen level and the maximum in the pre-determined volume is mingled with the body diameter.As for fatigue strength, fatigue lifetime and calm degree, in the same steel of oxygen level, the oxide inclusion body of volume particle size is deleterious, and specifically, the oxide inclusion body that granularity is not less than 20 μ m is deleterious.Therefore, in the steel of producing with method of the present invention, product made from steel is dissolved in the quantity that the granularity that detects in the acid is not less than the oxide inclusion body of 20 μ m in every 100g product made from steel, is not more than 40, preferably be not more than 30, the steel more preferably no more than 20 is the cleanness steel with outstanding rolling fatigue life and outstanding fatigue strength and outstanding calm degree.

The 4th invention

According to the 4th invention, the preferred production process of cleanness steel comprises the steps (1)-(5):

(1) oxidation refining molten steel in electrometal furnace or converter, preparation have the molten steel of predetermined chemical composition and preset temperature, then molten steel are transferred in the ladle furnace.

(2) in ladle furnace, the molten steel of transferring in the ladle furnace is carried out reduction refining, and regulate the chemical constitution of molten steel.At this time in ladle furnace, as you know: force to stir molten steel by the microgas that ladle bottom is blown into the speed of 1.5-5.0N.l/min/t, in this case, the churning time that surpasses 60 minutes can produce effect preferably.On the other hand, in the present invention, the refining time in the ladle refining furnace is not more than 60 minutes, preferably is not more than 45 minutes, more preferably 25-45 minute.

(3) will carry out the liquid steel degassing that reduction refining and chemical constitution are regulated in step (2), method is by circulating vacuum degasser circulation molten steel, and the chemical constitution of finally regulating steel.The degassing time in circulating vacuum degasser of generally all thinking in this case is less than 25 minutes, can access gratifying result when the internal circulating load of molten steel is about 5 times of molten steel total amount.On the other hand, in the present invention, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount, preferably big at least 10 times, more preferably big at least 15 times, to outgas for a long time, that is, is not less than 25 minutes the degassing.Step (2) and (3) are most important in the present invention.In step (2), carry out the purified ladle refining time in the heating and be minimum in case of necessity between, in step (3), do not relate to the degassing of heating, the mode that particularly circulating vacuum outgas is carried out is to make nozzle be immersed in the molten steel and only circulate molten steel.So the slag on the molten steel upper surface is in gratifying stationary state, therefore, enters oxide inclusion body number the molten steel from slag and be less than oxide inclusion body number in the reduction process of in ladle refining furnace, carrying out.In this system, when the flotation separation time of oxide inclusion body can guarantee, just can prevent to prevent that granularity is not less than the formation that is mingled with body greatly of about 30 μ m simultaneously owing to the rising that is subjected to the oxygen level that refractory materials on the ladle furnace inwall or scoriaceous pollution cause.So just can produce cleanness steel.

(4) will in step (3), carry out the molten steel casting that final chemical constitution regulates and become steel ingot.

In preferred production process according to cleanness steel of the present invention, in step (1)-(5), molten steel after the step (1) is being transferred in the process of ladle refining furnace, though the tapping temperature of molten steel is generally than high about 50 ℃ of the fusing point of steel, but in the present invention, the tapping temperature of molten steel is higher at least 100 ℃ than the fusing point of steel, and preferably high at least 120 ℃, more preferably high at least 150 ℃.Utilize such being provided with to make that sedimentary metal is dissolved in the molten steel fully around the ladle, slag is flotation fully also, so can prevent owing to separate or splash into the oxygen level that metal in the molten steel or slag cause raise in the ladle refining process under the preliminary refining state.

According to a preferred embodiment, the steel of producing with method of the present invention also comprises the cleanness steel with outstanding rolling fatigue life and fatigue strength, it is characterized in that: be not less than the oxide inclusion body of 20 μ m, for example Al by product made from steel being dissolved in the granularity that detects in the acid ₂O ₃The quantity that content is not less than 50% oxide inclusion body is not more than 40 in every 100g product made from steel, preferably be not more than 30, more preferably no more than 20.This measuring method of product made from steel has reflected that oxygen level and the maximum in the pre-determined volume is mingled with the body diameter.As for fatigue strength, fatigue lifetime and calm degree, in the same steel of oxygen level, the oxide inclusion body of volume particle size is deleterious, and specifically, the oxide inclusion body that granularity is not less than 20 μ m is deleterious.Therefore, in the steel of producing with method of the present invention, product made from steel is dissolved in oxide inclusion body (for example, the Al that the granularity that detects in the acid is not less than 20 μ m ₂O ₃Content is not less than 50% oxide inclusion body) quantity in every 100g product made from steel, be not more than 40, preferably be not more than 30, the steel more preferably no more than 20 is the cleanness steel with outstanding rolling fatigue life and outstanding fatigue strength and outstanding calm degree.

The 5th invention

According to the 5th invention, the preferred production process of cleanness steel comprises the steps (1)-(5):

(2) in ladle furnace, the molten steel of transferring in the ladle furnace is carried out reduction refining, and regulate the chemical constitution of molten steel.At this time in ladle furnace, be blown into microgas by ladle bottom with the speed of 1.5-5.0N.1/min/t and force to stir molten steel, also carry out induction stirring in addition.Therefore, the ladle refining time is 50-80 minute, preferred 70-80 minute.

(3) will carry out the liquid steel degassing that reduction refining and chemical constitution are regulated in step (2), method is by circulating vacuum degasser circulation molten steel, and the chemical constitution of finally regulating steel.The degassing time in circulating vacuum degasser of generally all thinking in this case is less than 25 minutes, can access gratifying result when the internal circulating load of molten steel is about 5 times of molten steel total amount.On the other hand, in the present invention, the internal circulating load of molten steel is bigger at least 8 times than molten steel total amount, preferably big at least 10 times, more preferably big at least 15 times, to outgas for a long time, that is, is not less than 25 minutes.Step (2) and (3) are most important in the 5th invention.In step (2), carry out in the purified ladle refining time in gas stirring and the induction stirring, even when refining is not the short period of time refining, promptly, even during long-time refining, that is, and 50-80 minute, during preferred refining in 70-80 minute, also can improve the cleanliness factor of steel satisfactorily.The stirring of induction stirring can be molten steel 200-700w per ton.As mentioned above, induction stirring is not stirred slag itself.Therefore can prevent the destruction of the slag equilibrium system that causes because the refractory materials of stove and melting loss that slag is mingled with body are become homeless.In addition, because the degassing, the mode that particularly circulating vacuum outgas is carried out is to make nozzle be immersed in the molten steel and only circulate molten steel.So the slag on the molten steel upper surface is in gratifying stationary state, enters oxide inclusion body number the molten steel from slag and be less than oxide inclusion body number in the reduction process of in ladle, carrying out.In this system, when the flotation separation time of oxide inclusion body can guarantee, just can prevent to prevent that granularity is not less than the formation that is mingled with body greatly of about 30 μ m simultaneously owing to the rising that is subjected to the oxygen level that refractory materials on the ladle inner wall or scoriaceous pollution cause.So just can produce cleanness steel.

(4) will carry out the molten steel casting that final chemical constitution regulates and become steel ingot.

In preferred production process according to cleanness steel of the present invention, in the ladle refining of the step (2) in step (1)-(5), specifically, ladle is in the inert atmosphere, therefore isolated with air, under this condition, carry out ladle refining (step 6).In preferred this embodiment of the present invention, step (6) is most important in the present invention.

In production practice, carry out ladle refining in the inert atmosphere at air-isolation in step (6) and in step (2), carry out the purified ladle refining under in conjunction with the induction stirring condition and combine in gas stirring, like this, even when refining is not the short period of time refining, that is, even during long-time refining, promptly, 50-80 minute, during preferred refining in 70-80 minute, also can improve the cleanliness factor of steel satisfactorily.Be exactly that ladle is covered specifically.For with molten steel in the ladle and air insulated, in the space that limits by cover plate, be full of rare gas element, as argon gas, nitrogen or the mixed gas that constitutes by argon gas and nitrogen.Therefore can keep scoriaceous system balancing.Inert gas pressure preferably drops to and is not more than 10 holders in the cover plate.This can further improve its effect.Therefore utilize such being provided with to make the complete flotation of slag, can prevent owing in the ladle refining process, under the preliminary refining state, separate or splash into the oxygen level that metal in the molten steel or slag cause and raise.Sealed gas is that flow velocity is not less than 50Nm ³The gas of/H is if refining under the decompression situation then also can use flow velocity to be lower than the gas of this scope.

According to a preferred embodiment, cleanness steel of the present invention also comprises the cleanness steel that particularly has outstanding rotoflector fatigue strength and cyclic stress fatigue strength, it is characterized in that: when at 100mm ²The product made from steel cross section on 30 places when measuring maximum and being mingled with the body diameter, the 30000mm that obtains according to the statistical calculations of these extreme values ²The predictor that middle maximum is mingled with the body diameter is not more than 60 μ m, preferably is not more than 40 μ m, more preferably no more than 25 μ m.As you know: cyclic stress fatigue strength and safe range of stress depend on that to a great extent the maximum in the pre-determined volume is mingled with the body diameter.This is disclosed in Japan's special permission publication 194121/1999, and the applicant of this patent is identical with applicant of the present invention.For example, generally work as at 100mm ²The product made from steel cross section on 30 places when measuring maximum and being mingled with the body diameter, the 30000mm that obtains according to the statistical calculations of these extreme values ²In the maximum predictor that is mingled with the body diameter be not more than 60 μ m, preferably be not more than 40 μ m, stably demonstrate outstanding fatigue strength more preferably no more than the cleanness steel of 25 μ m.In this case, oxygen level in the cleanness steel is not more than 10ppm, preferably, under the situation of the C in steel＜0.6% (quality), oxygen level is not more than 8ppm, more preferably be, under the situation of C 〉=0.6% (quality), oxygen level is not more than 6ppm, and the predictor that maximum is mingled with the body diameter is not more than 60 μ m, preferably be not more than 40 μ m, more preferably no more than 25 μ m.The steel of producing with method of the present invention is the cleanness steel with outstanding rolling fatigue life and outstanding fatigue strength.Though acid dissolving is work very time-consuming and trouble, advantageously, the aforesaid method that does not carry out product made from steel dissolving processing can be examined under a microscope certain area and come statistical ground to predict that maximum is mingled with the body diameter, and this method is very simple favourable.In addition, specifically, as for the fatigue that cyclic stress caused of Compression and Expansion, as you know: at the maximum diameter that is mingled with body that is easy to fracture place existence is the factor of very important decision intensity.This can statistical the method for this maximum diameter of ground prediction be useful.

Embodiment A

In electrometal furnace, carry out in the process that the molten steel after the oxidation refining pours out reductor such as manganese, aluminium and silicon being added ladle in advance from smelting furnace, perhaps in the process of coming out of the stove, be added in the molten steel.The add-on of pure basic reductor is not less than 1kg in the molten steel per ton, adds reductor and carries out tapping deoxidization,, carries out pre-deoxidation that is.Reduction refining molten steel in ladle refining technology then, molten steel after refining outgases in circulating vacuum degasser, carries out the steel ingot production technique with teeming practice then.10 stove JIS SUJ 2 and SCM 435 product made from steel that obtain are like this detected, and the maximum that measure oxygen level in the product, obtains according to the statistical calculations of extreme value is mingled with the predictor of body diameter and the L that measures according to tappet roller experiment in work-ing life (thrust-type rolling service life test) ₁₀Work-ing life.When the mensuration maximum is mingled with the predictor of body diameter, forge materials from φ 65 and get next experiment slice, 30 experiment slices are carried out 100mm ²Observation, according to the Principle of Statistics of these extreme values prediction 30000mm ²In maximum be mingled with the body diameter.In tappet roller experiment in work-ing life, the experiment slice that at first will be of a size of φ 60 * φ 20 * 8.3T carries out carburizing, quench hardening and tempering, experimentizes under the maximum hertz stress Pmax of 4900Mpa then, determines L by calculating then ₁₀Work-ing life.

Table A 1 illustrates an example of 10 stove SUJ, 2 steel being operated according to the present invention.

Table A 1

Operation	Tapping deoxidization (A ₁)
Operation	Tapping deoxidization (A ₁)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	62	56	52	57	65	60	75	65	57	73
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	1.9	3	2.2	2.8	1.3	1.9	2.9	2	2.8	1	Tapping temperature: fusing point+℃	62	56	52	57	65	60	75	65	57	73
	1.9	3	2.2	2.8	1.3	1.9	2.9	2	2.8	1	LF: the time, minute	55	51	56	56	60	57	59	57	60	55
LF: warm eventually, ℃	1525	1526	1521	1520	1526	1524	1525	1522	1526	1523	LF: the time, minute	55	51	56	56	60	57	59	57	60	55
LF: warm eventually, ℃	1525	1526	1521	1520	1526	1524	1525	1522	1526	1523	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	5.7	6.5	7.1	5.5	6.7	6.4	5.6	6.8	5.7	7	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	5.7	6.5	7.1	5.5	6.7	6.4	5.6	6.8	5.7	7	RH: warm eventually, ℃	1499	1493	1492	1498	1502	1502	1492	1497	1500	1499
Pouring temperature, ℃	1475	1476	1476	1475	1478	1478	1475	1477	1476	1475	RH: warm eventually, ℃	1499	1493	1492	1498	1502	1502	1492	1497	1500	1499
Pouring temperature, ℃	1475	1476	1476	1475	1478	1478	1475	1477	1476	1475	Oxygen level in the product, ppm	4.9	5.6	4.8	5.2	5.3	5.3	4.9	4.9	5.8	5.1
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	38	33	30	26	27	35	32	34	31	36	Oxygen level in the product, ppm	4.9	5.6	4.8	5.2	5.3	5.3	4.9	4.9	5.8	5.1
	38	33	30	26	27	35	32	34	31	36	The maximum predicted diameter that is mingled with body, μ m	49	44.8	38.4	52	47.7	42.4	49	49	52.2	40.8
L ₁₀(×10 ⁷)	2.2	1.9	3.1	3.0	2.5	2.4	2.7	3.5	2.9	2.8		49	44.8	38.4	52	47.7	42.4	49	49	52.2	40.8
L ₁₀(×10 ⁷)	2.2	1.9	3.1	3.0	2.5	2.4	2.7	3.5	2.9	2.8	Evaluation result	△	△	△	△	△	△	△	△	△	△

Table A 2 illustrates an example of 10 stove SCM, 435 steel being operated according to the present invention.

Table A 2

Operation	Tapping deoxidization (B ₁)
Operation	Tapping deoxidization (B ₁)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	68	54	69	61	74	68	62	67	55	65
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	2.5	1.8	2.5	1.9	1.5	1.6	1.7	1.5	1.5	2.6	Tapping temperature: fusing point+℃	68	54	69	61	74	68	62	67	55	65
	2.5	1.8	2.5	1.9	1.5	1.6	1.7	1.5	1.5	2.6	LF: the time, minute	55	51	57	56	59	53	60	53	54	51
LF: warm eventually, ℃	1565	1574	1567	1571	1570	1569	1572	1575	1565	1573	LF: the time, minute	55	51	57	56	59	53	60	53	54	51
LF: warm eventually, ℃	1565	1574	1567	1571	1570	1569	1572	1575	1565	1573	RH: the time, minute	22	22	21	20	23	20	24	23	20	21
RH: internal circulating load, multiple	6.8	6.0	6.6	5.7	5.9	5.5	7.0	6.5	7.0	6.3	RH: the time, minute	22	22	21	20	23	20	24	23	20	21
RH: internal circulating load, multiple	6.8	6.0	6.6	5.7	5.9	5.5	7.0	6.5	7.0	6.3	RH: warm eventually, ℃	1531	1533	1537	1534	1531	1532	1539	1541	1539	1536
Pouring temperature, ℃	1514	1518	1518	1520	1520	1516	1520	1520	1512	1516	RH: warm eventually, ℃	1531	1533	1537	1534	1531	1532	1539	1541	1539	1536
Pouring temperature, ℃	1514	1518	1518	1520	1520	1516	1520	1520	1512	1516	Oxygen level in the product, ppm	7.9	6.7	8.0	7.4	7.9	6.5	8.3	7.9	7.9	6.9
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	40	33	35	39	35	25	25	30	37	36	Oxygen level in the product, ppm	7.9	6.7	8.0	7.4	7.9	6.5	8.3	7.9	7.9	6.9
	40	33	35	39	35	25	25	30	37	36	The maximum predicted diameter that is mingled with body, μ m	47.4	46.9	48.0	51.8	55.3	45.5	49.8	55.3	55.3	45.4
L ₁₀(×10 ⁷)	1.2	1.9	1.8	2.1	1.5	2.8	2.7	1.2	2.4	2.1		47.4	46.9	48.0	51.8	55.3	45.5	49.8	55.3	55.3	45.4
L ₁₀(×10 ⁷)	1.2	1.9	1.8	2.1	1.5	2.8	2.7	1.2	2.4	2.1	Evaluation result	△	△	△	△	△	△	△	△	△	△

△: medium

Table A 3 illustrates an example of 10 stove SUJ, 2 steel being operated according to the present invention.

Table A 3

Operation	Tapping deoxidization+high temperature tapping (A ₂)
Operation	Tapping deoxidization+high temperature tapping (A ₂)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	147	148	116	145	155	152	139	113	152	126
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	2.7	1.5	2.3	1.7	1.7	2.7	1.9	2.3	1.1	2.7	Tapping temperature: fusing point+℃	147	148	116	145	155	152	139	113	152	126
	2.7	1.5	2.3	1.7	1.7	2.7	1.9	2.3	1.1	2.7	LF: the time, minute	56	60	59	51	53	53	52	52	58	53
LF: warm eventually, ℃	1524	1520	1521	1523	1523	1520	1523	1525	1525	1522	LF: the time, minute	56	60	59	51	53	53	52	52	58	53
LF: warm eventually, ℃	1524	1520	1521	1523	1523	1520	1523	1525	1525	1522	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	6	6.5	5.5	6.3	5.9	6.7	6.4	6.1	6.7	6.3	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	6	6.5	5.5	6.3	5.9	6.7	6.4	6.1	6.7	6.3	RH: warm eventually, ℃	1498	1501	1502	1500	1503	1498	1502	1497	1494	1501
Pouring temperature, ℃	1478	1476	1476	1476	1477	1476	1478	1475	1478	1476	RH: warm eventually, ℃	1498	1501	1502	1500	1503	1498	1502	1497	1494	1501
Pouring temperature, ℃	1478	1476	1476	1476	1477	1476	1478	1475	1478	1476	Oxygen level in the product, ppm	5.2	5.1	5	4.6	4.9	5.1	4.5	5.2	4.9	4.7
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	30	28	28	26	25	22	23	16	25	30	Oxygen level in the product, ppm	5.2	5.1	5	4.6	4.9	5.1	4.5	5.2	4.9	4.7
	30	28	28	26	25	22	23	16	25	30	The maximum predicted diameter that is mingled with body, μ m	20.8	20.4	20	23	24.5	25.5	22.5	26	24.5	23.5
L ₁₀(×10 ⁷)	3.4	3.7	4.7	4.0	4.1	2.6	3.3	4.9	3.9	5.2		20.8	20.4	20	23	24.5	25.5	22.5	26	24.5	23.5
L ₁₀(×10 ⁷)	3.4	3.7	4.7	4.0	4.1	2.6	3.3	4.9	3.9	5.2	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table A 4 illustrates an example of 10 stove SCM, 435 steel being operated according to the present invention.

Table A 4

Operation	Tapping deoxidization+high temperature tapping (B ₂)
Operation	Tapping deoxidization+high temperature tapping (B ₂)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	104	119	138	116	119	147	114	141	110	113
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	2	2.8	1.9	2.2	2.9	2.5	1.7	1.6	1.5	2.9	Tapping temperature: fusing point+℃	104	119	138	116	119	147	114	141	110	113
	2	2.8	1.9	2.2	2.9	2.5	1.7	1.6	1.5	2.9	LF: the time, minute	49	51	52	51	52	47	53	51	51	47
LF: warm eventually, ℃	1565	1572	1572	1572	1573	1572	1575	1566	1572	1567	LF: the time, minute	49	51	52	51	52	47	53	51	51	47
LF: warm eventually, ℃	1565	1572	1572	1572	1573	1572	1575	1566	1572	1567	RH: the time, minute	24	20	22	21	23	20	24	22	23	22
RH: internal circulating load, multiple	6.5	6.1	5.5	7.2	6.6	6.5	7.1	5.8	7.3	7.0	RH: the time, minute	24	20	22	21	23	20	24	22	23	22
RH: internal circulating load, multiple	6.5	6.1	5.5	7.2	6.6	6.5	7.1	5.8	7.3	7.0	RH: warm eventually, ℃	1533	1538	1532	1534	1540	1538	1538	1536	1538	1538
Pouring temperature, ℃	1519	1517	1517	1511	1516	1515	1513	1516	1511	1513	RH: warm eventually, ℃	1533	1538	1532	1534	1540	1538	1538	1536	1538	1538
Pouring temperature, ℃	1519	1517	1517	1511	1516	1515	1513	1516	1511	1513	Oxygen level in the product, ppm	7.1	7.3	7.1	7.4	6.5	6.8	7.1	7.1	6.9	6.4
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	28	29	20	25	30	28	29	26	22	20	Oxygen level in the product, ppm	7.1	7.3	7.1	7.4	6.5	6.8	7.1	7.1	6.9	6.4
	28	29	20	25	30	28	29	26	22	20	The maximum predicted diameter that is mingled with body, μ m	37.6	38.5	38.3	39.3	34.5	35.6	37.8	36.2	34.5	32.6
L ₁₀(×10 ⁷)	2.9	2.8	2.4	3.0	3.6	3.3	3.4	3.1	2.8	3.3		37.6	38.5	38.3	39.3	34.5	35.6	37.8	36.2	34.5	32.6
L ₁₀(×10 ⁷)	2.9	2.8	2.4	3.0	3.6	3.3	3.4	3.1	2.8	3.3	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table A 5 illustrates an example that 10 stove SUJ, 2 steel is carried out tapping deoxidization+weak point LF, long RH operation according to the present invention.

Table A 5

Operation	Tapping deoxidization+weak point LF, long RH (A ₃)
Operation	Tapping deoxidization+weak point LF, long RH (A ₃)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	66	80	61	79	55	66	68	65	67	60
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	1.8	1.7	3	1.6	2.6	2.7	2.8	2.2	3	2	Tapping temperature: fusing point+℃	66	80	61	79	55	66	68	65	67	60
	1.8	1.7	3	1.6	2.6	2.7	2.8	2.2	3	2	LF: the time, minute	41	34	33	31	38	30	40	32	39	44
LF: warm eventually, ℃	1546	1547	1548	1549	1550	1551	1552	1553	1554	1555	LF: the time, minute	41	34	33	31	38	30	40	32	39	44
LF: warm eventually, ℃	1546	1547	1548	1549	1550	1551	1552	1553	1554	1555	RH: the time, minute	56	57	59	54	55	55	54	57	60	58
RH: internal circulating load, multiple	18.7	19.0	19.7	18.0	18.3	18.3	18.0	19.0	20.0	19.3	RH: the time, minute	56	57	59	54	55	55	54	57	60	58
RH: internal circulating load, multiple	18.7	19.0	19.7	18.0	18.3	18.3	18.0	19.0	20.0	19.3	RH: warm eventually, ℃	1502	1510	1506	1502	1505	1508	1503	1508	1506	1508
Pouring temperature, ℃	1478	1477	1477	1478	1477	1478	1478	1475	1477	1476	RH: warm eventually, ℃	1502	1510	1506	1502	1505	1508	1503	1508	1506	1508
Pouring temperature, ℃	1478	1477	1477	1478	1477	1478	1478	1475	1477	1476	Oxygen level in the product, ppm	4.8	4	4.1	4.6	5.2	4.8	4.5	4.2	4.2	4.4
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	26	30	22	28	21	20	30	30	26	23	Oxygen level in the product, ppm	4.8	4	4.1	4.6	5.2	4.8	4.5	4.2	4.2	4.4
	26	30	22	28	21	20	30	30	26	23	The maximum predicted diameter that is mingled with body, μ m	21.8	19.4	18.9	21	21.6	18.4	22.7	21.3	20.8	20.2
L ₁₀(×10 ⁷)	4.8	4.0	5.1	4.0	3.4	3.9	4.4	3.6	3.7	3.1		21.8	19.4	18.9	21	21.6	18.4	22.7	21.3	20.8	20.2
L ₁₀(×10 ⁷)	4.8	4.0	5.1	4.0	3.4	3.9	4.4	3.6	3.7	3.1	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table A 6 illustrates an example that 10 stove SCM, 435 steel is carried out tapping deoxidization+weak point LF, long RH operation according to the present invention.

Table A 6

Operation	Tapping deoxidization+weak point LF, long RH (B ₃)
Operation	Tapping deoxidization+weak point LF, long RH (B ₃)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	62	72	56	55	71	59	63	78	67	63
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	3	1.6	2.8	1.8	2.9	2.4	2.3	2.6	2.1	1.9	Tapping temperature: fusing point+℃	62	72	56	55	71	59	63	78	67	63
	3	1.6	2.8	1.8	2.9	2.4	2.3	2.6	2.1	1.9	LF: the time, minute	42	42	40	41	42	45	41	37	42	36
LF: warm eventually, ℃	1580	1582	1585	1580	1579	1578	1578	1585	1584	1581	LF: the time, minute	42	42	40	41	42	45	41	37	42	36
LF: warm eventually, ℃	1580	1582	1585	1580	1579	1578	1578	1585	1584	1581	RH: the time, minute	36	45	39	35	43	39	45	36	43	38
RH: internal circulating load, multiple	12.0	15.0	13.0	11.7	14.3	13.0	15.0	12.0	14.3	12.7	RH: the time, minute	36	45	39	35	43	39	45	36	43	38
RH: internal circulating load, multiple	12.0	15.0	13.0	11.7	14.3	13.0	15.0	12.0	14.3	12.7	RH: warm eventually, ℃	1537	1533	1533	1535	1539	1539	1534	1539	1534	1539
Pouring temperature, ℃	1514	1513	1515	1515	1515	1516	1516	1515	1516	1515	RH: warm eventually, ℃	1537	1533	1533	1535	1539	1539	1534	1539	1534	1539
Pouring temperature, ℃	1514	1513	1515	1515	1515	1516	1516	1515	1516	1515	Oxygen level in the product, ppm	7	7.3	7.2	7.1	6.7	7.3	6.8	7.1	6.5	7.1
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	28	29	25	25	22	30	23	28	26	23	Oxygen level in the product, ppm	7	7.3	7.2	7.1	6.7	7.3	6.8	7.1	6.5	7.1
	28	29	25	25	22	30	23	28	26	23	The maximum predicted diameter that is mingled with body, μ m	25.0	25.0	24.9	24.7	25.0	24.8	24.9	24.6	24.7	24.9
L ₁₀(×10 ⁷)	3.0	2.6	3.8	3.7	3.1	3.3	2.9	2.3	3.6	2.7		25.0	25.0	24.9	24.7	25.0	24.8	24.9	24.6	24.7	24.9
L ₁₀(×10 ⁷)	3.0	2.6	3.8	3.7	3.1	3.3	2.9	2.3	3.6	2.7	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table A 7 illustrates an example that 10 stove SUJ, 2 steel is carried out tapping deoxidization+high temperature tapping+weak point LF, long RH operation according to the present invention.

Table A 7

Operation	Tapping deoxidization+high temperature tapping+weak point LF, long RH ((A ₄)
Operation											Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	132	143	131	150	153	134	151	138	111	157
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	2.8	1	2.9	1.9	2.7	2.6	2.5	2.4	1.7	2.2	Tapping temperature: fusing point+℃	132	143	131	150	153	134	151	138	111	157
	2.8	1	2.9	1.9	2.7	2.6	2.5	2.4	1.7	2.2	LF: the time, minute	43	34	35	38	31	39	38	41	35	44
LF: warm eventually, ℃	1541	1541	1546	1546	1541	1540	1543	1544	1544	1546	LF: the time, minute	43	34	35	38	31	39	38	41	35	44
LF: warm eventually, ℃	1541	1541	1546	1546	1541	1540	1543	1544	1544	1546	RH: the time, minute	54	50	58	48	52	47	51	60	53	48
RH: internal circulating load, multiple	18.8	16.1	18.6	16.0	16.8	15.7	17.6	20.7	18.2	16.5	RH: the time, minute	54	50	58	48	52	47	51	60	53	48
RH: internal circulating load, multiple	18.8	16.1	18.6	16.0	16.8	15.7	17.6	20.7	18.2	16.5	RH: warm eventually, ℃	1498	1502	1502	1502	1500	1501	1498	1502	1497	1498
Pouring temperature, ℃	1478	1476	1477	1475	1478	1475	1475	1476	1476	1475	RH: warm eventually, ℃	1498	1502	1502	1502	1500	1501	1498	1502	1497	1498
Pouring temperature, ℃	1478	1476	1477	1475	1478	1475	1475	1476	1476	1475	Oxygen level in the product, ppm	4.1	4.7	4.1	4.2	4.1	4.9	4.3	3.8	4.3	4.7
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	14	11	5	6	8	8	13	10	6	7	Oxygen level in the product, ppm	4.1	4.7	4.1	4.2	4.1	4.9	4.3	3.8	4.3	4.7
	14	11	5	6	8	8	13	10	6	7	The maximum predicted diameter that is mingled with body, μ m	12.3	14.1	12.3	14.4	14.1	14.7	12.9	11.4	12.9	13.8
L ₁₀(×10 ⁷)	7.1	7.9	9.9	9.1	11.3	10.6	10.9	11.9	10.0	8.4		12.3	14.1	12.3	14.4	14.1	14.7	12.9	11.4	12.9	13.8
L ₁₀(×10 ⁷)	7.1	7.9	9.9	9.1	11.3	10.6	10.9	11.9	10.0	8.4	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

Table A 8 illustrates an example that 10 stove SCM, 435 steel is carried out tapping deoxidization+high temperature tapping+weak point LF, long RH operation according to the present invention.

Table A 8

Operation	Tapping deoxidization+high temperature tapping+weak point LF, long RH (B ₄)
Operation											Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	143	115	104	148	130	106	109	124	122	105
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	2	2.1	2.4	1.7	1.7	2.9	2.1	2	2.4	2.5	Tapping temperature: fusing point+℃	143	115	104	148	130	106	109	124	122	105
	2	2.1	2.4	1.7	1.7	2.9	2.1	2	2.4	2.5	LF: the time, minute	35	34	33	42	33	43	38	45	41	37
LF: warm eventually, ℃	1577	1579	1585	1578	1584	1578	1582	1581	1577	1576	LF: the time, minute	35	34	33	42	33	43	38	45	41	37
LF: warm eventually, ℃	1577	1579	1585	1578	1584	1578	1582	1581	1577	1576	RH: the time, minute	36	45	44	40	38	37	46	39	40	43
RH: internal circulating load, multiple	12.4	14.5	14.2	13.3	13.1	11.9	15.3	13.0	12.9	14.3	RH: the time, minute	36	45	44	40	38	37	46	39	40	43
RH: internal circulating load, multiple	12.4	14.5	14.2	13.3	13.1	11.9	15.3	13.0	12.9	14.3	RH: warm eventually, ℃	1532	1541	1535	1537	1531	1531	1532	1540	1538	1536
Pouring temperature, ℃	1513	1520	1517	1521	1516	1511	1518	1511	1511	1519	RH: warm eventually, ℃	1532	1541	1535	1537	1531	1531	1532	1540	1538	1536
Pouring temperature, ℃	1513	1520	1517	1521	1516	1511	1518	1511	1511	1519	Oxygen level in the product, ppm	6.5	5.4	5.5	5.9	6.0	6.1	5.3	6.0	5.8	5.7
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	8	10	6	9	8	14	8	14	11	8	Oxygen level in the product, ppm	6.5	5.4	5.5	5.9	6.0	6.1	5.3	6.0	5.8	5.7
	8	10	6	9	8	14	8	14	11	8	The maximum predicted diameter that is mingled with body, μ m	24.6	23.5	23.8	24.4	24.6	24.0	22.5	24.0	26.7	26.8
L ₁₀(×0 ⁷)	7.9	8.6	10.4	9.3	98	96	8.8	8.7	10.0	9.3		24.6	23.5	23.8	24.4	24.6	24.0	22.5	24.0	26.7	26.8
L ₁₀(×0 ⁷)	7.9	8.6	10.4	9.3	98	96	8.8	8.7	10.0	9.3	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

In order to contrast with the present invention, Table A 9 illustrates an example of SUJ 2 steel being operated according to prior art, and Table A 10 illustrates an example of the SCM435 steel being operated according to prior art

Table A 9

Operation	Traditional operation (prior art)
Operation	Traditional operation (prior art)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	57	72	58	60	74	75	51	65	62	68
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	-	-	-	-	-	-	-	-	-	-	Tapping temperature: fusing point+℃	57	72	58	60	74	75	51	65	62	68
	-	-	-	-	-	-	-	-	-	-	LF: the time, minute	61	61	63	61	62	62	61	63	61	63
LF: warm eventually, ℃	1525	1524	1526	1525	1523	1524	1523	1520	1525	1520	LF: the time, minute	61	61	63	61	62	62	61	63	61	63
LF: warm eventually, ℃	1525	1524	1526	1525	1523	1524	1523	1520	1525	1520	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	5.7	6.7	7.1	6.5	6.2	5.7	7	5.5	6.8	6.2	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	5.7	6.7	7.1	6.5	6.2	5.7	7	5.5	6.8	6.2	RH: warm eventually, ℃	1493	1502	1501	1497	1501	1501	1502	1503	1496	1499
Pouring temperature, ℃	1477	1475	1475	1475	1475	1475	1476	1478	1478	1476	RH: warm eventually, ℃	1493	1502	1501	1497	1501	1501	1502	1503	1496	1499
Pouring temperature, ℃	1477	1475	1475	1475	1475	1475	1476	1478	1478	1476	Oxygen level in the product, ppm	5.4	5.1	5.1	6.1	5.8	5.9	5.8	5.9	5.2	6.2
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	59	56	54	65	48	41	50	47	45	49	Oxygen level in the product, ppm	5.4	5.1	5.1	6.1	5.8	5.9	5.8	5.9	5.2	6.2
	59	56	54	65	48	41	50	47	45	49	The maximum predicted diameter that is mingled with body, μ m	86.4	61.2	66.3	97.6	81.2	76.7	92.8	76.7	72.8	74.4
L ₁₀(×10 ⁷)	1.9	2.4	2.4	1.8	1.9	3.4	1.9	2.2	2.0	2.2		86.4	61.2	66.3	97.6	81.2	76.7	92.8	76.7	72.8	74.4
L ₁₀(×10 ⁷)	1.9	2.4	2.4	1.8	1.9	3.4	1.9	2.2	2.0	2.2	Evaluation result	×	×	×	×	×	×	×	×	×	×

*: poor

Table A 10

Operation	Traditional operation (prior art)
Operation	Traditional operation (prior art)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	61	54	69	50	74	58	58	69	64	54
Deoxidation dosage in deoxidation dosage that adds when coming out of the stove or the adding ladle, kg/t	-	-	-	-	-	-	-	-	-	-	Tapping temperature: fusing point+℃	61	54	69	50	74	58	58	69	64	54
	-	-	-	-	-	-	-	-	-	-	LF: the time, minute	62	63	61	61	61	63	63	63	61	61
LF: warm eventually, ℃	1570	1574	1566	1572	1567	1569	1567	1569	1569	1570	LF: the time, minute	62	63	61	61	61	63	63	63	61	61
LF: warm eventually, ℃	1570	1574	1566	1572	1567	1569	1567	1569	1569	1570	RH: the time, minute	23	23	23	20	21	23	21	23	23	24
RH: internal circulating load, multiple	6.8	7.5	7.0	8.3	6.2	6.0	7.4	8.0	7.3	6.7	RH: the time, minute	23	23	23	20	21	23	21	23	23	24
RH: internal circulating load, multiple	6.8	7.5	7.0	8.3	6.2	6.0	7.4	8.0	7.3	6.7	RH: warm eventually, ℃	1533	1538	1541	1540	1541	1533	1535	1534	1531	1531
Pouring temperature, ℃	1517	1519	1520	1518	1517	1511	1516	1512	1512	1521	RH: warm eventually, ℃	1533	1538	1541	1540	1541	1533	1535	1534	1531	1531
Pouring temperature, ℃	1517	1519	1520	1518	1517	1511	1516	1512	1512	1521	Oxygen level in the product, ppm	7.6	9.2	9.2	8.8	6.9	8.3	6.9	8.3	9.4	9.1
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	49	54	59	52	42	57	56	53	53	42	Oxygen level in the product, ppm	7.6	9.2	9.2	8.8	6.9	8.3	6.9	8.3	9.4	9.1
	49	54	59	52	42	57	56	53	53	42	The maximum predicted diameter that is mingled with body, μ m	68.4	82.8	73.6	70.4	55.2	83.0	55.2	83.0	84.6	91.0
L ₁₀(×10 ⁷)	1.0	1.3	1.1	1.9	2.3	1.5	2.0	1.2	1.2	1.9		68.4	82.8	73.6	70.4	55.2	83.0	55.2	83.0	84.6	91.0
L ₁₀(×10 ⁷)	1.0	1.3	1.1	1.9	2.3	1.5	2.0	1.2	1.2	1.9	Evaluation result (*: poor)	×	×	×	×	×	×	×	×	×	×

1-A8 can clearly be seen that from Table A: for carrying out tapping deoxidization (promptly according to the present invention, pre-deoxidation) product made from steel of Sheng Chaning, when tapping temperature is higher than the traditional operation temperature (promptly, fusing point+at least 100 ℃) time, and when outgasing satisfactorily by the operating time in the shortening ladle refining furnace, and the amount of increase circulation RH (promptly in the circulating degasification process, circulation molten steel amount/molten steel total amount) time, no matter be SUJ 2 steel or SCM 435 steel, the oxygen level of product is all very little, in addition, the granularity body number that is mingled with that is not less than 20 μ m also declines to a great extent.From Table A 1-A8 as can be seen: as for cleanliness factor, for example of the present invention, all product made from steel all are be evaluated as generally (△), good (zero) and outstanding (◎), that is, all be outstanding cleanness steel.On the contrary, from Table A 9 and A10 as can be seen: for all traditional examples, its cleanliness factor is be evaluated as poor (*), and the not talkative one-tenth of traditional product made from steel is Clean Steel.Should be noted that in this: general (△) compares with good (zero) and outstanding (◎), if do not compare with do not carry out the steel that tapping deoxidization is be evaluated as poor (*) according to art methods, these are be evaluated as generally that the steel of (△) then has higher cleanliness factor.

For each the stove product made from steel that has carried out pre-deoxidation (that is, tapping deoxidization), oxygen level and maximum are mingled with the predictor of body diameter all because of T _SH[(temperature when molten steel is transferred to ladle furnace)-(fusing point of molten steel)=T _SH] increase and reduce, thereby improved the cleanliness factor of steel.For each the stove product made from steel that has carried out pre-deoxidation, relation between refining time in the ladle furnace and oxygen level and the maximum predictor that is mingled with the body diameter is: when refining time was not less than about 25 minutes, the predictor that oxygen level and maximum are mingled with the body diameter can both reduce satisfactorily.But the maximum predictor that is mingled with the body diameter but increases along with the increase of refining time.Can think that its reason is as follows: along with the prolongation of time, the melting loss vector of refractory materials increases in the ladle furnace, the balance of slag system is broken, and for example, this is the minimum value that the oxidizing reaction that produces because contact with air and dissolved oxygen amount have surpassed dissolved oxygen.In addition, relation in circulating vacuum degasser between circulation molten steel amount/molten steel total amount and oxygen level and the maximum predictor that is mingled with the body diameter is: the raising effect of cleanliness factor increases with the increase of circulation molten steel amount, when circulation molten steel amount/when the molten steel total amount is not less than 15 times, this effect state that reaches capacity basically.

Verified: as to reduce oxygen level and can improve L with the maximum predictor that is mingled with the body diameter ₁₀Life-span.This means that the steel that the oxygen level of producing with method of the present invention and the maximum predictor that is mingled with the body diameter have all reduced has outstanding fatigue strength performance such as outstanding rolling fatigue life.

Figure A1 is the broken line graph that is illustrated in the oxygen level of the 10 stove product made from steel that carry out tapping deoxidization in the production method of the present invention in the process that SUJ 2 molten steel is transferred to ladle furnace, and figure A1 also is illustrated in the oxygen level of not carrying out 10 stove product made from steel of tapping deoxidization in the traditional method.In figure A1, A3 and A5, A ₁Data when the tapping deoxidization that claim 1 defines according to the present invention is shown, A ₂Data when the tapping deoxidization of according to the present invention claim 2 definition+high temperature tapping is shown, A ₃Tapping deoxidization+short period of time LF, the data when long-time RH handles of claim 3 definition according to the present invention are shown, A ₄Tapping deoxidization+high temperature tapping+short period of time LF, the data when long-time RH handles of claim 3 definition according to the present invention are shown, among the figure A1 traditional data of the prior art are shown also.

Figure A2 is the broken line graph that is illustrated in the oxygen level of the 10 stove product made from steel that carry out tapping deoxidization in the production method of the present invention in the process that SCM 435 molten steel is transferred to ladle, and figure A2 also is illustrated in the oxygen level of not carrying out 10 stove product made from steel of tapping deoxidization in the traditional method.In figure A2, A4 and A6, B ₁Data when the tapping deoxidization that claim 1 defines according to the present invention is shown, B ₂Data when the tapping deoxidization of according to the present invention claim 2 definition+high temperature tapping is shown, B ₃Tapping deoxidization+short period of time LF, the data when long-time RH handles of claim 3 definition according to the present invention are shown, B ₄Tapping deoxidization+high temperature tapping+short period of time LF, the data when long-time RH handles of claim 3 definition according to the present invention are shown, among the figure A2 traditional data of the prior art are shown also.

Figure A3 is illustrated in the broken line graph that the maximum predicted that obtains according to these statisticss of extremes in the 10 stove product made from steel that carry out deoxidation in the production method of the present invention in the process that SUJ 2 molten steel is transferred to ladle furnace is mingled with the body diameter, and figure A3 also illustrates the maximum predicted of not carrying out in 10 stove SUJ, 2 product made from steel of deoxidation according to traditional method and is mingled with the body diameter.

Figure A4 is illustrated in the broken line graph that the maximum predicted that obtains according to these statisticss of extremes in the 10 stove product made from steel that carry out deoxidation in the production method of the present invention in the process that SCM 435 molten steel is transferred to ladle furnace is mingled with the body diameter, and figure A4 also illustrates the maximum predicted of not carrying out in 10 stove SCM, 435 product made from steel of deoxidation according to traditional method and is mingled with the body diameter.

Figure A5 is illustrated in the L according to tappet roller measuring in work-ing life that carries out 10 stove product made from steel of deoxidation in the production method of the present invention in the process that SUJ 2 molten steel is transferred to ladle furnace ₁₀The broken line graph in life-span, figure A5 also illustrates the L that does not carry out 10 stove SUJ, 2 product made from steel of deoxidation according to traditional method ₁₀Life-span.

Figure A6 is illustrated in the L according to tappet roller measuring in work-ing life that carries out 10 stove product made from steel of deoxidation in the production method of the present invention in the process that SCM 435 molten steel is transferred to ladle furnace ₁₀The broken line graph in life-span, figure A6 also illustrates the L that does not carry out 10 stove SCM, 435 product made from steel of deoxidation according to traditional method ₁₀Life-span.

Can fully prove by these experimental results: in accordance with the present production process, before ladle refining, carry out pre-deoxidation (promptly, tapping deoxidization) no matter still can reduce the oxygen level of product and the predictor that maximum is mingled with the body diameter to SCM 435 steel capital to SUJ 2 steel, its cleanliness factor can be significantly improved, L can be significantly improved according to tappet roller measuring in work-ing life ₁₀Life-span.In the production method of steel, add these treatment steps, that is, only add the definition of according to the present invention claim 1 the tapping deoxidization step, add tapping deoxidization+high temperature tapping step of claim 2 definition, the tapping deoxidization+short period of time LF that adds claim 3 definition, long-time RH treatment step, add tapping deoxidization+high temperature tapping+short period of time LF according to the present invention according to the present invention, predictor that the RH treatment step can significantly improve all steel for a long time oxygen level, maximum are mingled with the body diameter and according to the L of tappet roller measuring in work-ing life ₁₀Life-span.Add that particularly short period of time LF, long-time RH treatment step can produce very large effect.

Can clearly be seen that from above-mentioned explanation: when tapping deoxidization, when transferring to the molten steel of refining furnace such as electric arc furnace generation in the ladle, reductor such as manganese, aluminium and silicon are added ladle in advance, perhaps in the process of in accordance with the present production process molten steel being transferred in the ladle, reductor is joined in the molten steel, make molten steel pre-deoxidation before ladle refining, like this can the very high product made from steel of mass production cleanliness factor, and needn't the very high remelting processing of use cost.In addition, employing tapping deoxidization+high temperature is tapped and is added that tapping deoxidization+high temperature tapping+short period of time LF, long-time RH treatment step can make product made from steel have higher cleanliness factor.So just can provide cleanness steel, it is suitable for the machine steel of making to require to have fatigue strength, fatigue lifetime and calm degree, particularly suitable is done as rolling bearing with steel, constant speed tieing with steel, gear steel, annular continuous change transmission with steel, the steel for mechanical structure that is used for cold forging, tool steel and spring steel, the production method of cleanness steel can also be provided, that is, the present invention has unexpected unprecedented advantage.

Embodiment B

The molten steel that generates by melting process in electrometal furnace carries out circulating degasification by circulating vacuum degasser, and the molten steel after will outgasing is then transferred in the ladle furnace, in ladle furnace molten steel is carried out ladle refining.Make molten steel after refining carry out circulating degasification then, carry out the steel ingot production technique with teeming practice then by circulating vacuum degasser.10 stove JIS SUJ 2 and SCM 435 product made from steel that obtain are like this detected, and the maximum that measure oxygen level in the product, obtains according to the statistical calculations of extreme value is mingled with the predictor of body diameter and according to the L of tappet roller measuring in work-ing life ₁₀Work-ing life.When the mensuration maximum is mingled with the predictor of body diameter, forge materials from φ 65 and get next experiment slice, 30 experiment slices are carried out 100mm ²Observation, according to the Principle of Statistics of these extreme values prediction 30000mm ²In maximum be mingled with the body diameter.In tappet roller experiment in work-ing life, the experiment slice that at first will be of a size of φ 60 * φ 20 * 8.3T carries out carburizing, quench hardening and tempering, experimentizes under the maximum hertz stress Pmax of 4900Mpa then, determines L by calculating then ₁₀Work-ing life.

Table B1 illustrates the example that 10 stove SUJ, 2 steel are operated under the situation that the W-RH that only carries out claim 1 definition of the present invention handles.

Table B1

Operation	W-RH(A ₁)
Operation	W-RH(A ₁)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	75	64	63	60	71	61	73	59	64	68
First RH: the time, minute	15	9	15	8	10	8	11	12	15	11	Tapping temperature: fusing point+℃	75	64	63	60	71	61	73	59	64	68
First RH: the time, minute	15	9	15	8	10	8	11	12	15	11	First RH: internal circulating load, multiple	5.0	3.0	5.0	2.7	3.3	2.7	3.7	4.0	5.0	3.7
First RH: reductor add-on, kg/t	2.6	1.6	2.6	1.7	2.8	2	2.9	1.1	1.3	2.6	First RH: internal circulating load, multiple	5.0	3.0	5.0	2.7	3.3	2.7	3.7	4.0	5.0	3.7
First RH: reductor add-on, kg/t	2.6	1.6	2.6	1.7	2.8	2	2.9	1.1	1.3	2.6	LF: the time, minute	48	60	49	52	59	57	58	49	48	57
LF: warm eventually, ℃	1532	1534	1533	1532	1528	1531	1533	1534	1535	1533	LF: the time, minute	48	60	49	52	59	57	58	49	48	57
LF: warm eventually, ℃	1532	1534	1533	1532	1528	1531	1533	1534	1535	1533	Second RH: the time, minute	22	21	22	25	24	24	25	23	24	25
Second RH: internal circulating load, multiple	7.3	7.0	7.3	8.3	8.0	8.0	8.3	7.7	8.0	8.3	Second RH: the time, minute	22	21	22	25	24	24	25	23	24	25
Second RH: internal circulating load, multiple	7.3	7.0	7.3	8.3	8.0	8.0	8.3	7.7	8.0	8.3	The 2nd RH: warm eventually, ℃	1509	1508	1503	1510	1510	1509	1504	1505	1503	1506
Pouring temperature, ℃	1476	1478	1476	1476	1478	1476	1477	1476	1475	1476	The 2nd RH: warm eventually, ℃	1509	1508	1503	1510	1510	1509	1504	1505	1503	1506
Pouring temperature, ℃	1476	1478	1476	1476	1478	1476	1477	1476	1475	1476	Oxygen level in the product, ppm	4.8	5.1	4.6	47	4.9	5.1	4.9	4.8	4.8	5
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	23	21	19	26	27	30	21	20	20	29	Oxygen level in the product, ppm	4.8	5.1	4.6	47	4.9	5.1	4.9	4.8	4.8	5
	23	21	19	26	27	30	21	20	20	29	The maximum predicted diameter that is mingled with body, μ m	22.8	20.5	19.7	21.8	20	19.8	19.8	21.2	18.6	20.2
L ₁₀(×10 ⁷)	3.8	3.3	5.0	4.8	4.7	4.1	5.3	3.2	5.5	4.9		22.8	20.5	19.7	21.8	20	19.8	19.8	21.2	18.6	20.2
L ₁₀(×10 ⁷)	3.8	3.3	5.0	4.8	4.7	4.1	5.3	3.2	5.5	4.9	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table B2 illustrates the example that 10 stove SCM, 435 steel are operated under the situation of only carrying out W-RH processing of the present invention.

Table B2

Operation	W-RH(B ₁)
Operation	W-RH(B ₁)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	68	74	69	74	65	77	63	60	58	70
First RH: the time, minute	12	12	11	12	10	10	13	8	15	15	Tapping temperature: fusing point+℃	68	74	69	74	65	77	63	60	58	70
First RH: the time, minute	12	12	11	12	10	10	13	8	15	15	First RH: internal circulating load, multiple	4.0	4.0	3.7	4.0	3.3	3.3	4.3	2.7	5.0	5.0
First RH: reductor add-on, kg/t	2.9	2.2	2	1.5	1.5	1.8	2.3	2.5	2.7	2.2	First RH: internal circulating load, multiple	4.0	4.0	3.7	4.0	3.3	3.3	4.3	2.7	5.0	5.0
First RH: reductor add-on, kg/t	2.9	2.2	2	1.5	1.5	1.8	2.3	2.5	2.7	2.2	LF: the time, minute	60	47	55	47	56	57	51	45	60	56
LF: warm eventually, ℃	1579	1585	1578	1583	1580	1578	1580	1579	1582	1583	LF: the time, minute	60	47	55	47	56	57	51	45	60	56
LF: warm eventually, ℃	1579	1585	1578	1583	1580	1578	1580	1579	1582	1583	Second RH: the time, minute	22	22	25	24	22	25	20	22	25	24
Second RH: internal circulating load, multiple	7.3	7.3	8.3	8.0	7.3	8.3	6.7	7.3	8.3	8.0	Second RH: the time, minute	22	22	25	24	22	25	20	22	25	24
Second RH: internal circulating load, multiple	7.3	7.3	8.3	8.0	7.3	8.3	6.7	7.3	8.3	8.0	The 2nd RH: warm eventually, ℃	1523	1522	1523	1524	1525	1521	1524	1520	1524	1522
Pouring temperature, ℃	1515	1516	1515	1513	1514	1515	1515	1514	1516	1515	The 2nd RH: warm eventually, ℃	1523	1522	1523	1524	1525	1521	1524	1520	1524	1522
Pouring temperature, ℃	1515	1516	1515	1513	1514	1515	1515	1514	1516	1515	Oxygen level in the product, ppm	6.7	6.7	7	72	7.1	6.9	6.6	6.8	6.4	7
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	30	27	25	22	24	28	23	26	26	26	Oxygen level in the product, ppm	6.7	6.7	7	72	7.1	6.9	6.6	6.8	6.4	7
	30	27	25	22	24	28	23	26	26	26	The maximum predicted diameter that is mingled with body, μ m	20.1	21.7	22.8	20.2	24	21.9	22.2	22.5	20.7	22
L ₁₀(×10 ⁷)	2.7	3.3	3.4	2.6	2.5	3.4	4.0	4.0	3.8	3.7		20.1	21.7	22.8	20.2	24	21.9	22.2	22.5	20.7	22
L ₁₀(×10 ⁷)	2.7	3.3	3.4	2.6	2.5	3.4	4.0	4.0	3.8	3.7	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table B3 illustrates an example that 10 stove SUJ, 2 steel is carried out W-RH processing+high temperature tapping steel according to the present invention.

Table B3

Operation	W-RH+ high temperature tapping (A ₂)
Operation	W-RH+ high temperature tapping (A ₂)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	136	152	128	169	163	145	120	125	160	154
First RH: the time, minute	15	9	15	8	10	8	11	12	15	11	Tapping temperature: fusing point+℃	136	152	128	169	163	145	120	125	160	154
First RH: the time, minute	15	9	15	8	10	8	11	12	15	11	First RH: internal circulating load, multiple	5.0	3.0	5.0	2.7	3.3	2.7	3.7	4.0	5.0	3.7
First RH: reductor add-on, kg/t	2.6	1.6	2.6	1.7	2.8	2	2.9	1.1	1.3	2.6	First RH: internal circulating load, multiple	5.0	3.0	5.0	2.7	3.3	2.7	3.7	4.0	5.0	3.7
First RH: reductor add-on, kg/t	2.6	1.6	2.6	1.7	2.8	2	2.9	1.1	1.3	2.6	LF: the time, minute	72	64	63	72	72	62	66	60	65	71
LF: warm eventually, ℃	1532	1534	1533	1532	1528	1531	1533	1534	1535	1533	LF: the time, minute	72	64	63	72	72	62	66	60	65	71
LF: warm eventually, ℃	1532	1534	1533	1532	1528	1531	1533	1534	1535	1533	Second RH: the time, minute	22	21	22	24	24	24	23	23	24	24
Second RH: internal circulating load, multiple	7.3	7.0	7.3	8.3	8.0	8.0	8.3	7.7	8.0	8.3	Second RH: the time, minute	22	21	22	24	24	24	23	23	24	24
Second RH: internal circulating load, multiple	7.3	7.0	7.3	8.3	8.0	8.0	8.3	7.7	8.0	8.3	The 2nd RH: warm eventually, ℃	1509	1508	1503	1510	1510	1509	1504	1505	1503	1506
Pouring temperature, ℃	1476	1478	1476	1476	1478	1476	1477	1476	1475	1476	The 2nd RH: warm eventually, ℃	1509	1508	1503	1510	1510	1509	1504	1505	1503	1506
Pouring temperature, ℃	1476	1478	1476	1476	1478	1476	1477	1476	1475	1476	Oxygen level in the product, ppm	4.8	5.1	4.5	4.6	4.9	5.2	5.0	4.6	4.8	5.1
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	21	23	14	16	20	23	22	17	19	26	Oxygen level in the product, ppm	4.8	5.1	4.5	4.6	4.9	5.2	5.0	4.6	4.8	5.1
	21	23	14	16	20	23	22	17	19	26	The maximum predicted diameter that is mingled with body, μ m	15.7	16.2	141	14.3	15.6	16.6	16.0	14.9	14.8	17.2
L ₁₀(×10 ⁷)	7.0	6.0	8.8	7.7	6.5	5.2	6.6	8.4	7.2	5.3		15.7	16.2	141	14.3	15.6	16.6	16.0	14.9	14.8	17.2
L ₁₀(×10 ⁷)	7.0	6.0	8.8	7.7	6.5	5.2	6.6	8.4	7.2	5.3	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table B4 illustrates an example that 10 stove SCM, 435 steel is carried out W-RH processing+high temperature tapping steel according to the present invention.

Table B4

Operation	W-RH+ high temperature tapping (B ₂)
Operation	W-RH+ high temperature tapping (B ₂)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	135	140	130	123	102	122	118	109	157	115
First RH: the time, minute	12	12	11	12	10	10	13	8	15	15	Tapping temperature: fusing point+℃	135	140	130	123	102	122	118	109	157	115
First RH: the time, minute	12	12	11	12	10	10	13	8	15	15	First RH: internal circulating load, multiple	4.0	4.0	3.7	4.0	3.3	3.3	4.3	2.7	5.0	5.0
First RH: reductor add-on, kg/t	2.9	2.2	2	1.5	15	1.8	2.3	2.5	2.7	2.2	First RH: internal circulating load, multiple	4.0	4.0	3.7	4.0	3.3	3.3	4.3	2.7	5.0	5.0
First RH: reductor add-on, kg/t	2.9	2.2	2	1.5	15	1.8	2.3	2.5	2.7	2.2	LF: the time, minute	72	68	62	71	61	67	64	73	62	68
LF: warm eventually, ℃	1579	1585	1578	1583	1580	1578	1580	1579	1582	1583	LF: the time, minute	72	68	62	71	61	67	64	73	62	68
LF: warm eventually, ℃	1579	1585	1578	1583	1580	1578	1580	1579	1582	1583	Second RH: the time, minute	22	22	23	24	22	23	20	22	24	24
Second RH: internal circulating load, multiple	7.3	7.3	8.3	8.0	7.3	8.3	6.7	7.3	8.3	8.0	Second RH: the time, minute	22	22	23	24	22	23	20	22	24	24
Second RH: internal circulating load, multiple	7.3	7.3	8.3	8.0	7.3	8.3	6.7	7.3	8.3	8.0	The 2nd RH: warm eventually, ℃	1523	1522	1523	1524	1525	1521	1524	1520	1524	1522
Pouring temperature, ℃	1515	1516	1515	1513	1514	1515	1515	1514	1516	1515	The 2nd RH: warm eventually, ℃	1523	1522	1523	1524	1525	1521	1524	1520	1524	1522
Pouring temperature, ℃	1515	1516	1515	1513	1514	1515	1515	1514	1516	1515	Oxygen level in the product, ppm	6.2	6.7	6.6	6.1	6.3	6.4	6.2	6.5	6.4	6.5
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	14	18	15	13	16	16	13	17	15	18	Oxygen level in the product, ppm	6.2	6.7	6.6	6.1	6.3	6.4	6.2	6.5	6.4	6.5
	14	18	15	13	16	16	13	17	15	18	The maximum predicted diameter that is mingled with body, μ m	20.2	21.6	20.3	19.7	20.4	20.8	19.5	21.3	20.6	21.0
L ₁₀(×10 ⁷)	6.2	5.0	6.4	7.8	5.2	6.9	7.0	4.8	5.9	4.1		20.2	21.6	20.3	19.7	20.4	20.8	19.5	21.3	20.6	21.0
L ₁₀(×10 ⁷)	6.2	5.0	6.4	7.8	5.2	6.9	7.0	4.8	5.9	4.1	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table B5 illustrates an example that 10 stove SUJ, 2 steel is carried out W-RH processing+weak point LF, long RH operation according to the present invention.

Table B5

Operation	W-RH+ short LF, long RH (A ₃)
Operation	W-RH+ short LF, long RH (A ₃)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	59	68	74	61	69	78	74	59	73	67
First RH: the time, minute	14	12	12	9	10	9	12	9	15	11	Tapping temperature: fusing point+℃	59	68	74	61	69	78	74	59	73	67
First RH: the time, minute	14	12	12	9	10	9	12	9	15	11	First RH: internal circulating load, multiple	4.7	4.0	4.0	3.0	3.3	3.0	4.0	3.0	5.0	3.7
First RH: reductor add-on, kg/t	2.6	1.3	1.5	2.2	1	2.2	1.5	2.1	2.2	1.3	First RH: internal circulating load, multiple	4.7	4.0	4.0	3.0	3.3	3.0	4.0	3.0	5.0	3.7
First RH: reductor add-on, kg/t	2.6	1.3	1.5	2.2	1	2.2	1.5	2.1	2.2	1.3	LF: the time, minute	44	38	35	44	45	42	41	36	36	44
LF: warm eventually, ℃	1541	1545	1544	1543	1542	1541	1541	1543	1541	1544	LF: the time, minute	44	38	35	44	45	42	41	36	36	44
LF: warm eventually, ℃	1541	1545	1544	1543	1542	1541	1541	1543	1541	1544	Second RH: the time, minute	49	38	37	46	54	54	53	59	45	41
Second RH: internal circulating load, multiple	16.3	12.7	12.3	15.3	18.0	18.0	17.7	19.7	15.0	13.7	Second RH: the time, minute	49	38	37	46	54	54	53	59	45	41
Second RH: internal circulating load, multiple	16.3	12.7	12.3	15.3	18.0	18.0	17.7	19.7	15.0	13.7	The 2nd RH: warm eventually, ℃	1507	1505	1507	1507	1506	1503	1504	1505	1508	1508
Pouring temperature, ℃	1476	1478	1478	1476	1475	1475	1477	1477	1476	1476	The 2nd RH: warm eventually, ℃	1507	1505	1507	1507	1506	1503	1504	1505	1508	1508
Pouring temperature, ℃	1476	1478	1478	1476	1475	1475	1477	1477	1476	1476	Oxygen level in the product, ppm	4.8	4.3	4.4	4.5	5.1	5.1	4.1	4.4	4.9	4.6
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	15	14	21	17	25	19	16	12	20	19	Oxygen level in the product, ppm	4.8	4.3	4.4	4.5	5.1	5.1	4.1	4.4	4.9	4.6
	15	14	21	17	25	19	16	12	20	19	The maximum predicted diameter that is mingled with body, μ m	14.1	13.7	14.1	13.2	12.5	14.3	13.8	12.5	12.8	14.7
L ₁₀(×10 ⁷)	8.6	10.6	10.7	10.0	7.0	9.3	9.9	9.4	8.9	9.4		14.1	13.7	14.1	13.2	12.5	14.3	13.8	12.5	12.8	14.7
L ₁₀(×10 ⁷)	8.6	10.6	10.7	10.0	7.0	9.3	9.9	9.4	8.9	9.4	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

Table B6 illustrates an example that 10 stove SCM435 steel is carried out W-RH processing+weak point LF, long RH operation according to the present invention.

Table B6

Operation	W-RH+ short LF, long RH (B ₃)
Operation	W-RH+ short LF, long RH (B ₃)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	56	70	78	67	76	63	74	63	64	72
First RH: the time, minute	9	14	12	12	15	13	8	14	15	10	Tapping temperature: fusing point+℃	56	70	78	67	76	63	74	63	64	72
First RH: the time, minute	9	14	12	12	15	13	8	14	15	10	First RH: internal circulating load, multiple	3.0	4.7	4.0	4.0	5.0	4.3	2.7	4.7	5.0	3.3
First RH: reductor add-on, kg/t	2.4	2.8	1.6	2.7	2.2	3	2.5	3	2.9	1.9	First RH: internal circulating load, multiple	3.0	4.7	4.0	4.0	5.0	4.3	2.7	4.7	5.0	3.3
First RH: reductor add-on, kg/t	2.4	2.8	1.6	2.7	2.2	3	2.5	3	2.9	1.9	LF: the time, minute	40	38	42	41	37	42	36	43	38	35
LF: warm eventually, ℃	1585	1578	1581	1579	1582	1579	1585	1583	1577	1577	LF: the time, minute	40	38	42	41	37	42	36	43	38	35
LF: warm eventually, ℃	1585	1578	1581	1579	1582	1579	1585	1583	1577	1577	Second RH: the time, minute	31	55	34	32	31	54	37	53	52	46
Second RH: internal circulating load, multiple	10.3	18.3	11.3	10.7	10.3	18.0	12.3	17.7	17.3	15.3	Second RH: the time, minute	31	55	34	32	31	54	37	53	52	46
Second RH: internal circulating load, multiple	10.3	18.3	11.3	10.7	10.3	18.0	12.3	17.7	17.3	15.3	The 2nd RH: warm eventually, ℃	1524	1520	1523	1524	1524	1522	1525	1525	1524	1523
Pouring temperature, ℃	1516	1513	1514	1515	1515	1515	1515	1516	1516	1514	The 2nd RH: warm eventually, ℃	1524	1520	1523	1524	1524	1522	1525	1525	1524	1523
Pouring temperature, ℃	1516	1513	1514	1515	1515	1515	1515	1516	1516	1514	Oxygen level in the product, ppm	6.3	6.4	6.1	6.4	6	6.5	6.5	6.4	6.4	6.4
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	14	12	11	15	14	15	10	14	11	15	Oxygen level in the product, ppm	6.3	6.4	6.1	6.4	6	6.5	6.5	6.4	6.4	6.4
	14	12	11	15	14	15	10	14	11	15	The maximum predicted diameter that is mingled with body, μ m	24	22.7	22.2	22.2	23	23.7	23.7	22.5	23.4	22.1
L ₁₀(×10 ⁷)	7.9	8.8	10.1	9.7	7.7	6.9	8.3	9.4	9.5	8.0		24	22.7	22.2	22.2	23	23.7	23.7	22.5	23.4	22.1
L ₁₀(×10 ⁷)	7.9	8.8	10.1	9.7	7.7	6.9	8.3	9.4	9.5	8.0	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

Table B7 illustrates an example that 10 stove SUJ, 2 steel is carried out W-RH processing+high temperature tapping+weak point LF, long RH operation according to the present invention.

Table B7

Operation	W-RH+ high temperature tapping+weak point LF, long RH (A ₄)
Operation	W-RH+ high temperature tapping+weak point LF, long RH (A ₄)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	140	182	170	149	189	166	163	182	142	157
First RH: the time, minute	13	14	8	13	8	17	15	18	14	11	Tapping temperature: fusing point+℃	140	182	170	149	189	166	163	182	142	157
First RH: the time, minute	13	14	8	13	8	17	15	18	14	11	First RH: internal circulating load, multiple	4.3	4.7	2.7	4.3	2.7	5.7	5.0	6.0	4.7	3.7
First RH: reductor add-on, kg/t	1.2	2.2	0.5	2.1	2.1	1.6	2.5	2.4	0.9	1.1	First RH: internal circulating load, multiple	4.3	4.7	2.7	4.3	2.7	5.7	5.0	6.0	4.7	3.7
First RH: reductor add-on, kg/t	1.2	2.2	0.5	2.1	2.1	1.6	2.5	2.4	0.9	1.1	LF: the time, minute	37	40	40	43	37	37	44	38	33	39
LF: warm eventually, ℃	1541	1546	1546	1543	1540	1545	1542	1544	1540	1542	LF: the time, minute	37	40	40	43	37	37	44	38	33	39
LF: warm eventually, ℃	1541	1546	1546	1543	1540	1545	1542	1544	1540	1542	Second RH: the time, minute	49	56	53	59	53	55	46	49	58	56
Second RH: internal circulating load, multiple	15.8	19.2	17.1	19.7	17.6	18.3	15.7	15.9	20.0	19.4	Second RH: the time, minute	49	56	53	59	53	55	46	49	58	56
Second RH: internal circulating load, multiple	15.8	19.2	17.1	19.7	17.6	18.3	15.7	15.9	20.0	19.4	The 2nd RH: warm eventually, ℃	1501	1502	1496	1493	1502	1499	1492	1495	1501	1501
Pouring temperature, ℃	1477	1478	1475	1477	1478	1477	1478	1475	1476	1476	The 2nd RH: warm eventually, ℃	1501	1502	1496	1493	1502	1499	1492	1495	1501	1501
Pouring temperature, ℃	1477	1478	1475	1477	1478	1477	1478	1475	1476	1476	Oxygen in the product contains, ppm	4.6	4.1	4.5	4	4.3	4.2	3.7	4.5	3.8	3.9
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	2	5	6	7	8	8	8	5	2	4	Oxygen in the product contains, ppm	4.6	4.1	4.5	4	4.3	4.2	3.7	4.5	3.8	3.9
	2	5	6	7	8	8	8	5	2	4	The maximum predicted diameter that is mingled with body, μ m	11.7	11	11.8	10.9	10.5	10.3	11.2	12.1	10.9	10.4
L ₁₀(×10 ⁷)	9.7	12.2	11.0	12.6	11.3	10.9	11.5	10.2	10.8	11.1		11.7	11	11.8	10.9	10.5	10.3	11.2	12.1	10.9	10.4
L ₁₀(×10 ⁷)	9.7	12.2	11.0	12.6	11.3	10.9	11.5	10.2	10.8	11.1	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

Table B8 illustrates an example that 10 stove SCM, 435 steel is carried out W-RH processing+high temperature tapping+weak point LF, long RH operation according to the present invention.

Table B8

Operation	W-RH+ high temperature tapping+weak point LF, long RH (B ₄)
Operation	W-RH+ high temperature tapping+weak point LF, long RH (B ₄)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	136	131	137	106	107	102	136	138	105	134
First RH: the time, minute	18	8	9	16	11	8	17	8	15	14	Tapping temperature: fusing point+℃	136	131	137	106	107	102	136	138	105	134
First RH: the time, minute	18	8	9	16	11	8	17	8	15	14	First RH: internal circulating load, multiple	6	2.67	3.00	5.33	3.67	2.67	5.67	2.67	5.00	4.67
First RH: reductor add-on, kg/t	2.4	2.1	1	2.5	1.3	1.6	0.8	1.4	0.8	2.3	First RH: internal circulating load, multiple	6	2.67	3.00	5.33	3.67	2.67	5.67	2.67	5.00	4.67
First RH: reductor add-on, kg/t	2.4	2.1	1	2.5	1.3	1.6	0.8	1.4	0.8	2.3	LF: the time, minute	33	37	44	42	40	35	39	40	34	34
LF: warm eventually, ℃	1577	1581	1577	1576	1579	1586	1582	1585	1579	1584	LF: the time, minute	33	37	44	42	40	35	39	40	34	34
LF: warm eventually, ℃	1577	1581	1577	1576	1579	1586	1582	1585	1579	1584	Second RH: the time, minute	39	39	42	42	40	44	37	39	38	41
Second RH: internal circulating load, multiple	13.0	13.5	14.0	13.5	12.4	14.3	12.7	13.3	12.2	12.9	Second RH: the time, minute	39	39	42	42	40	44	37	39	38	41
Second RH: internal circulating load, multiple	13.0	13.5	14.0	13.5	12.4	14.3	12.7	13.3	12.2	12.9	The 2nd RH: warm eventually, ℃	1541	1538	1532	1539	1541	1537	1540	1537	1532	1539
Pouring temperature, ℃	1515	1518	1521	1513	1518	1520	1521	1519	1511	1520	The 2nd RH: warm eventually, ℃	1541	1538	1532	1539	1541	1537	1540	1537	1532	1539
Pouring temperature, ℃	1515	1518	1521	1513	1518	1520	1521	1519	1511	1520	Oxygen level in the product, ppm	6.0	5.8	5.3	5.2	5.6	4.7	5.5	5.5	5.8	5.6
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	5	3	6	8	8	6	2	5	4	3	Oxygen level in the product, ppm	6.0	5.8	5.3	5.2	5.6	4.7	5.5	5.5	5.8	5.6
	5	3	6	8	8	6	2	5	4	3	The maximum predicted diameter that is mingled with body, μ m	22.0	21.3	20.3	20.5	23.4	20.0	22.9	22.1	23.2	21.8
L ₁₀(×10 ⁷)	10.4	10.6	9.8	9.6	10.0	11.0	9.2	9.1	10.2	9.9		22.0	21.3	20.3	20.5	23.4	20.0	22.9	22.1	23.2	21.8
L ₁₀(×10 ⁷)	10.4	10.6	9.8	9.6	10.0	11.0	9.2	9.1	10.2	9.9	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

In order to contrast with the present invention, table B9 illustrates an example of SUJ 2 steel being operated according to prior art, and table B10 illustrates an example of the SCM435 steel being operated according to prior art

Table B9

Operation	Traditional operation (prior art)
Operation	Traditional operation (prior art)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	57	72	58	60	74	75	51	65	62	68
First RH: the time, minute	-	-	-	-	-	-	-	-	-	-	Tapping temperature: fusing point+℃	57	72	58	60	74	75	51	65	62	68
First RH: the time, minute	-	-	-	-	-	-	-	-	-	-	First RH: internal circulating load, multiple	-	-	-	-	-	-	-	-	-	-
First RH: reductor add-on, kg/t	-	-	-	-	-	-	-	-	-	-	First RH: internal circulating load, multiple	-	-	-	-	-	-	-	-	-	-
First RH: reductor add-on, kg/t	-	-	-	-	-	-	-	-	-	-	LF: the time, minute	61	61	63	61	62	62	61	63	61	63
LF: warm eventually, ℃	1525	1524	1526	1525	1523	1524	1523	1520	1525	1520	LF: the time, minute	61	61	63	61	62	62	61	63	61	63
LF: warm eventually, ℃	1525	1524	1526	1525	1523	1524	1523	1520	1525	1520	Second RH: the time, minute	23	23	23	23	23	23	23	23	23	23
Second RH: internal circulating load, multiple	5.7	6.7	7.1	6.5	6.2	5.7	7	5.5	6.8	6.2	Second RH: the time, minute	23	23	23	23	23	23	23	23	23	23
Second RH: internal circulating load, multiple	5.7	6.7	7.1	6.5	6.2	5.7	7	5.5	6.8	6.2	The 2nd RH: warm eventually, ℃	1493	1502	1501	1497	1501	1501	1502	1503	1496	1499
Pouring temperature, ℃	1477	1475	1475	1475	1475	1475	1476	1478	1478	1476	The 2nd RH: warm eventually, ℃	1493	1502	1501	1497	1501	1501	1502	1503	1496	1499
Pouring temperature, ℃	1477	1475	1475	1475	1475	1475	1476	1478	1478	1476	Oxygen level in the product, ppm	5.4	5.1	5.1	6.1	5.8	5.9	5.8	5.9	5.2	6.2
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	59	56	54	65	48	41	50	47	45	49	Oxygen level in the product, ppm	5.4	5.1	5.1	6.1	5.8	5.9	5.8	5.9	5.2	6.2
	59	56	54	65	48	41	50	47	45	49	The maximum predicted diameter that is mingled with body, μ m	86.4	61.2	66.3	97.6	81.2	76.7	92.8	76.7	72.8	74.4
L ₁₀(×10 ⁷)	1.9	2.4	2.4	1.8	1.9	3.4	1.9	2.2	2.0	2.2		86.4	61.2	66.3	97.6	81.2	76.7	92.8	76.7	72.8	74.4
L ₁₀(×10 ⁷)	1.9	2.4	2.4	1.8	1.9	3.4	1.9	2.2	2.0	2.2	Evaluation result	×	×	×	×	×	×	×	×	×	×

*: poor

Table B10

Operation	Traditional operation (prior art)
Operation	Traditional operation (prior art)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	61	54	69	50	74	58	58	69	64	54
First RH: the time, minute	-	-	-	-	-	-	-	-	-	-	Tapping temperature: fusing point+℃	61	54	69	50	74	58	58	69	64	54
First RH: the time, minute	-	-	-	-	-	-	-	-	-	-	First RH: internal circulating load, multiple	-	-	-	-	-	-	-	-	-	-
First RH: reductor add-on, kg/t	-	-	-	-	-	-	-	-	-	-	First RH: internal circulating load, multiple	-	-	-	-	-	-	-	-	-	-
First RH: reductor add-on, kg/t	-	-	-	-	-	-	-	-	-	-	LF: the time, minute	62	63	61	61	61	63	63	63	61	61
LF: warm eventually, ℃	1570	1574	1566	1572	1567	1569	1567	1569	1569	1570	LF: the time, minute	62	63	61	61	61	63	63	63	61	61
LF: warm eventually, ℃	1570	1574	1566	1572	1567	1569	1567	1569	1569	1570	Second RH: the time, minute	23	23	23	20	21	23	21	23	23	24
Second RH: internal circulating load, multiple	6.8	7.5	7.0	8.3	6.2	6.0	7.4	8.0	7.3	6.7	Second RH: the time, minute	23	23	23	20	21	23	21	23	23	24
Second RH: internal circulating load, multiple	6.8	7.5	7.0	8.3	6.2	6.0	7.4	8.0	7.3	6.7	The 2nd RH: warm eventually, ℃	1533	1538	1541	1540	1541	1533	1535	1534	1531	1531
Pouring temperature, ℃	1517	1519	1520	1518	1517	1511	1516	1512	1512	1521	The 2nd RH: warm eventually, ℃	1533	1538	1541	1540	1541	1533	1535	1534	1531	1531
Pouring temperature, ℃	1517	1519	1520	1518	1517	1511	1516	1512	1512	1521	Oxygen level in the product, ppm	7.6	9.2	9.2	8.8	6.9	8.3	6.9	8.3	9.4	9.1
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	49	54	59	52	42	57	56	53	53	42	Oxygen level in the product, ppm	7.6	9.2	9.2	8.8	6.9	8.3	6.9	8.3	9.4	9.1
	49	54	59	52	42	57	56	53	53	42	The maximum predicted diameter that is mingled with body, μ m	68.4	82.8	73.6	70.4	55.2	83.0	55.2	83.0	84.6	91.0
L ₁₀(×10 ⁷)	1.0	1.3	1.1	1.9	2.3	1.5	2.0	1.2	1.2	1.9		68.4	82.8	73.6	70.4	55.2	83.0	55.2	83.0	84.6	91.0
L ₁₀(×10 ⁷)	1.0	1.3	1.1	1.9	2.3	1.5	2.0	1.2	1.2	1.9	Evaluation result	×	×	×	×	×	×	×	×	×	×

*: poor

B1-B8 can clearly be seen that from table: for the product made from steel that carries out the W-RH process for producing according to the present invention, wherein, the molten steel that generates in electrometal furnace or the converter is outgased in advance, transfer to then and carry out refining in the ladle furnace, then molten steel is passed through circulating vacuum degasser circulating degasification, be higher than the traditional operation temperature (promptly, when fusing point+at least 100 ℃) adopting W-RH processings+high temperature to tap combination operation down, adopt the W-RH processing+weak point LF that shortens the operating time in the ladle furnace, during combination operation that long RH handles, and the amount of increase circulation RH (promptly in the circulating degasification process, circulation molten steel amount/molten steel total amount) when outgasing for a long time satisfactorily, and the combination of all above-mentioned treatment steps of employing, promptly, W-RH processing+high temperature tapping+weak point LF, when long RH handles, no matter be SUJ 2 steel or SCM 435 steel, can both reduce the oxygen level of product, that can also reduce significantly that granularity is not less than 20 μ m is mingled with the body number.B1-B8 it can also be seen that from table: as for cleanliness factor, for example of the present invention, all product made from steel all are be evaluated as well (zero) and outstanding (◎), that is, all be outstanding cleanness steel.On the contrary, from showing B9 and B10 as can be seen: for all traditional examples, its cleanliness factor is be evaluated as poor (*), and the not talkative one-tenth of traditional product made from steel is Clean Steel.

For having carried out each stove product made from steel that W-RH handles, oxygen level and maximum are mingled with the predictor of body diameter all because of T _SH[(temperature when molten steel is transferred to ladle furnace)-(fusing point of molten steel)=T _SH] increase and reduce, thereby improved the cleanliness factor of steel.For having carried out the product made from steel that W-RH handles, relation between refining time in the ladle furnace and oxygen level and the maximum predictor that is mingled with the body diameter is: when refining time was not less than about 25 minutes, the predictor that oxygen level and maximum are mingled with the body diameter can both reduce satisfactorily.But the maximum predictor that is mingled with the body diameter but increases along with the increase of refining time.Can think that its reason is as follows: along with the prolongation of time, the melting loss vector of refractory materials increases in the ladle refining furnace, the balance of slag system is broken, and for example, this is the minimum value that the oxidizing reaction that produces because contact with air and dissolved oxygen amount have surpassed dissolved oxygen.In addition, relation in circulating vacuum degasser between circulation molten steel amount/molten steel total amount and oxygen level and the maximum predictor that is mingled with the body diameter is: the raising effect of cleanliness factor increases with the increase of circulation molten steel amount, when circulation molten steel amount/when the molten steel total amount is not less than 15, this effect state that reaches capacity basically.

Figure B1 is the broken line graph that is illustrated in the oxygen level of the 10 stove product made from steel that carry out the W-RH processing in the production method of the present invention, in the process that SUJ 2 molten steel are handled, the degassing in advance before ladle refining, behind ladle refining molten steel is outgased again, figure B1 also is illustrated in the oxygen level of 10 stove SUJ, 2 product made from steel that do not carry out pre-deoxidation in the traditional method.In figure B1, B3 and B5, A ₁Data when the W-RH processing of only adopting claim 8 definition according to the present invention is shown, A ₂Data when the W-RH processing+high temperature tapping that claim 9 defines according to the present invention is shown, A ₃W-RH processing+short period of time LF, the data when long-time RH handles of claim 10 definition according to the present invention are shown, A ₄W-RH processing+high temperature tapping+short period of time LF, the data when long-time RH handles of claim 10 definition according to the present invention are shown, the traditional data that does not outgas in advance in the prior art also is shown among these figure.

Figure B2 is the broken line graph that is illustrated in the oxygen level of the 10 stove product made from steel that carry out the W-RH processing in the production method of the present invention, in the process that SCM 435 molten steel are handled, the degassing in advance before ladle refining, behind ladle refining molten steel is outgased again, figure B2 also is illustrated in the oxygen level of 10 stove SCM, 435 product made from steel that do not carry out pre-deoxidation in the traditional method.In figure B2, B4 and B6, B ₁Data when the W-RH processing of only adopting claim 8 definition according to the present invention is shown, B ₂Data when the W-RH processing+high temperature tapping that claim 9 defines according to the present invention is shown, B ₃W-RH processing+short period of time LF, the data when long-time RH handles of claim 10 definition according to the present invention are shown, B ₄W-RH processing+high temperature tapping+short period of time LF, the data when long-time RH handles of claim 10 definition according to the present invention are shown, the traditional data that does not outgas in advance in the prior art also is shown among these figure.

Figure B3 is illustrated in the broken line graph that the maximum predicted that obtains according to these statisticss of extremes in the 10 stove product made from steel that carry out the W-RH processing in the production method of the present invention is mingled with the body diameter, in the process that SUJ 2 molten steel are handled, the degassing in advance before ladle refining, behind ladle refining molten steel is outgased again, figure B3 also illustrates the maximum predicted of not carrying out in 10 stove SUJ, 2 product made from steel of deoxidation according to traditional method and is mingled with the body diameter.

Figure B4 is illustrated in the broken line graph that the maximum predicted that obtains according to these statisticss of extremes in the 10 stove product made from steel that carry out the W-RH processing in the production method of the present invention is mingled with the body diameter, in the process that SCM 435 molten steel are handled, the degassing in advance before ladle refining, behind ladle refining molten steel is outgased again, figure B4 also illustrates the maximum predicted of not carrying out in 10 stove SCM, 435 product made from steel of deoxidation according to traditional method and is mingled with the body diameter.

Figure B5 is the L according to tappet roller measuring in work-ing life that is illustrated in the 10 stove product made from steel that carry out the W-RH processing in the production method of the present invention ₁₀The broken line graph in life-span, in the process that SUJ 2 molten steel are handled, the degassing in advance outgases molten steel behind ladle refining again before ladle refining, and figure B5 also illustrates the L that does not carry out 10 stove SUJ, 2 product made from steel of deoxidation according to traditional method ₁₀Life-span.

Figure B6 is the L according to tappet roller measuring in work-ing life that is illustrated in the 10 stove product made from steel that carry out the W-RH processing in the production method of the present invention ₁₀The broken line graph in life-span, in the process that SCM 435 molten steel are handled, the degassing in advance outgases molten steel behind ladle refining again before ladle refining, and figure B6 also illustrates the L that does not carry out 10 stove SCM, 435 product made from steel of deoxidation according to traditional method ₁₀Life-span.

Can fully prove by these experimental results: in accordance with the present production process, W-RH handles, wherein before ladle refining, outgas in advance and behind ladle refining, molten steel outgased again and no matter still can significantly reduce the oxygen level and the maximum predictor that is mingled with the body diameter of product SCM 435 steel capital to SUJ 2 steel, its cleanliness factor can be significantly improved, L can be significantly improved according to tappet roller measuring in work-ing life ₁₀Life-span.In the production method of steel, add these treatment steps, that is, only add the definition of according to the present invention claim 8 the W-RH treatment step, add claim 9 definition according to the present invention W-RH processings+high temperature tapping step, add the W-RH processings+short period of time LF of claim 10 definition according to the present invention, for a long time the RH treatment step or add W-RH processing+high temperature tapping+short period of time LF, RH treatment step oxygen level, the maximum that can significantly improve all products is mingled with the predictor of body diameter and according to the L of tappet roller measuring in work-ing life for a long time ₁₀Life-span.

Can clearly be seen that from above-mentioned explanation: can the very high product made from steel of mass production cleanliness factor according to the present invention, and needn't the very high remelting processing of use cost.So just can provide cleanness steel, it is suitable for the machine steel of doing to require to have fatigue strength, fatigue lifetime, particularly suitable is done as rolling bearing with steel, constant speed tieing with steel, gear steel, annular continuous change transmission with steel, the steel for mechanical structure that is used for cold forging, tool steel and spring steel, the production method of cleanness steel can also be provided, that is, the present invention has unexpected advantage.

Embodiment C

Oxidation refining molten steel in electrometal furnace.In same stove, in molten steel after refining, add reductor such as aluminium and silicon then, make deoxidation of molten steel.The molten steel of pre-deoxidation transferred to carry out ladle refining in the ladle furnace.Molten steel after refining outgases in circulating vacuum degasser, carries out the steel ingot production technique with teeming practice then.10 stove JIS SUJ 2 and SCM 435 product made from steel that obtain are like this detected, and the maximum that measure oxygen level in the product, obtains according to the statistical calculations of extreme value is mingled with the predictor of body diameter and according to the L of tappet roller measuring in work-ing life ₁₀Work-ing life.When the mensuration maximum is mingled with the predictor of body diameter, forge materials from φ 65 and get next experiment slice, 30 experiment slices are carried out 100mm ²Observation, according to the Principle of Statistics of these extreme values prediction 30000mm ²In maximum be mingled with the body diameter.In tappet roller experiment in work-ing life, the experiment slice that at first will be of a size of φ 60 * φ 20 * 8.3T carries out carburizing, quench hardening and tempering, experimentizes under the maximum hertz stress Pmax of 4900MPa then, determines L by calculating then ₁₀Work-ing life.

Table C1 illustrates according to the present invention 10 stove SUJ, 2 steel oxidation refining in electrometal furnace or converter carrying out in same stove then deoxidation operation (below be referred to as " deoxidation stove in "),, only carries out an example of the interior deoxidation of stove that is.

Table C1

Operation	Deoxidation (A in the stove ₁)
Operation	Deoxidation (A in the stove ₁)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	3.7	2	4.6	4.3	3.6	5	5.9	4.9	4.4	4.9
Tapping temperature: fusing point+℃	59	67	70	52	55	71	69	69	58	69		3.7	2	4.6	4.3	3.6	5	5.9	4.9	4.4	4.9
Tapping temperature: fusing point+℃	59	67	70	52	55	71	69	69	58	69	LF: the time, minute	59	57	53	54	57	57	54	58	53	53
LF: warm eventually, ℃	1524	1520	1520	1526	1520	1520	1524	1521	1525	1521	LF: the time, minute	59	57	53	54	57	57	54	58	53	53
LF: warm eventually, ℃	1524	1520	1520	1526	1520	1520	1524	1521	1525	1521	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	7.1	6.3	7	6.1	7.1	6.8	6.7	5.9	6.7	7.2	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	7.1	6.3	7	6.1	7.1	6.8	6.7	5.9	6.7	7.2	RH: warm eventually, ℃	1497	1499	1500	1494	1500	1494	1496	1498	1496	1499
Pouring temperature, ℃	1478	1475	1477	1477	1475	1475	1476	1475	1475	1475	RH: warm eventually, ℃	1497	1499	1500	1494	1500	1494	1496	1498	1496	1499
Pouring temperature, ℃	1478	1475	1477	1477	1475	1475	1476	1475	1475	1475	Oxygen level in the product, ppm	4.8	5.2	5.	5.6	4.6	4.8	4.6	5.7	5	5
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	29	40	32	25	30	26	37	27	27	34	Oxygen level in the product, ppm	4.8	5.2	5.	5.6	4.6	4.8	4.6	5.7	5	5
	29	40	32	25	30	26	37	27	27	34	The maximum predicted diameter that is mingled with body, μ m	48	41.6	50	56	36.8	43.2	41.4	51.3	50	50
L ₁₀(×10 ⁷)	2.5	1.9	2.4	2.6	2.1	2.7	2.2	1.8	2.2	1.8		48	41.6	50	56	36.8	43.2	41.4	51.3	50	50
L ₁₀(×10 ⁷)	2.5	1.9	2.4	2.6	2.1	2.7	2.2	1.8	2.2	1.8	Evaluation result	△	△	△	△	△	△	△	△	△	△

△: general

Table C2 illustrates an example that 10 stove SCM, 435 steel is only carried out deoxidation operation in the stove according to the present invention.

Table C2

Operation	Deoxidation (B in the stove ₁)
Operation	Deoxidation (B in the stove ₁)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	5.4	5.7	2.3	2.7	47	2.5	5.1	5.3	5.4	5.1
Tapping temperature: fusing point+℃	60	65	66	54	63	64	57	61	60	51		5.4	5.7	2.3	2.7	47	2.5	5.1	5.3	5.4	5.1
Tapping temperature: fusing point+℃	60	65	66	54	63	64	57	61	60	51	LF: the time, minute	60	54	54	52	58	52	54	56	57	56
LF: warm eventually, ℃	1575	1572	1570	1570	1565	1572	1568	1566	1567	1572	LF: the time, minute	60	54	54	52	58	52	54	56	57	56
LF: warm eventually, ℃	1575	1572	1570	1570	1565	1572	1568	1566	1567	1572	RH: the time, minute	20	20	20	24	21	23	21	20	21	23
RH: internal circulating load, multiple	6.7	6.2	6.5	6.6	6.3	7.3	7.1	6.9	5.7	5.8	RH: the time, minute	20	20	20	24	21	23	21	20	21	23
RH: internal circulating load, multiple	6.7	6.2	6.5	6.6	6.3	7.3	7.1	6.9	5.7	5.8	RH: warm eventually, ℃	1540	1540	1535	1534	1541	1539	1541	1536	1536	1533
Pouring temperature, ℃	1520	1517	1521	1518	1515	1519	1520	1520	1514	1520	RH: warm eventually, ℃	1540	1540	1535	1534	1541	1539	1541	1536	1536	1533
Pouring temperature, ℃	1520	1517	1521	1518	1515	1519	1520	1520	1514	1520	Oxygen level in the product, ppm	8.5	8.3	8.1	7.1	7.0	7.3	8.0	8.1	6.7	6.9
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	35	28	25	32	29	27	37	32	38	33	Oxygen level in the product, ppm	8.5	8.3	8.1	7.1	7.0	7.3	8.0	8.1	6.7	6.9
	35	28	25	32	29	27	37	32	38	33	The maximum predicted diameter that is mingled with body, μ m	51.0	58.1	48.6	49.7	42.0	51.1	56.0	48.6	40.2	48.3
L ₁₀(×10 ⁷)	1.5	1.8	2.1	1.8	2.3	1.7	1.6	2.5	2.2	2.3		51.0	58.1	48.6	49.7	42.0	51.1	56.0	48.6	40.2	48.3
L ₁₀(×10 ⁷)	1.5	1.8	2.1	1.8	2.3	1.7	1.6	2.5	2.2	2.3	Evaluation result	△	△	△	△	△	△	△	△	△	△

△: general

Table C3 illustrates an example that 10 stove SUJ, 2 steel is carried out deoxidation in the stove+high temperature tapping steel according to the present invention.

Table C3

Operation	Deoxidation in the stove+high temperature tapping (A ₂)
Operation	Deoxidation in the stove+high temperature tapping (A ₂)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	3.1	2	3.2	4.6	2	4.8	2.1	3	3.3	4.1
Tapping temperature: fusing point+℃	187	178	124	143	178	142	175	163	180	142		3.1	2	3.2	4.6	2	4.8	2.1	3	3.3	4.1
Tapping temperature: fusing point+℃	187	178	124	143	178	142	175	163	180	142	LF: the time, minute	54	59	57	59	60	60	57	59	56	54
LF: warm eventually, ℃	1523	1525	1522	1526	1525	1520	1524	1525	1522	1520	LF: the time, minute	54	59	57	59	60	60	57	59	56	54
LF: warm eventually, ℃	1523	1525	1522	1526	1525	1520	1524	1525	1522	1520	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	7.2	6.1	6.3	7	6.7	5.5	6.4	5.9	5.8	6	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	7.2	6.1	6.3	7	6.7	5.5	6.4	5.9	5.8	6	RH: warm eventually, ℃	1501	1503	1500	1499	1496	1496	1498	1493	1492	1499
Pouring temperature, ℃	1477	1476	1478	1475	1475	1475	1475	1478	1476	1478	RH: warm eventually, ℃	1501	1503	1500	1499	1496	1496	1498	1493	1492	1499
Pouring temperature, ℃	1477	1476	1478	1475	1475	1475	1475	1478	1476	1478	Oxygen level in the product, ppm	4.8	4.5	4.6	4.6	4.7	5.1	4.6	4.9	4.9	4.7
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	19	19	19	18	26	30	24	22	30	24	Oxygen level in the product, ppm	4.8	4.5	4.6	4.6	4.7	5.1	4.6	4.9	4.9	4.7
	19	19	19	18	26	30	24	22	30	24	The maximum predicted diameter that is mingled with body, μ m	19.2	22.5	18.4	23	23.5	25.5	18.4	19.6	24.5	18.8
L ₁₀(×10 ⁷)	4.0	3.8	44	3.9	4.3	4.3	3.9	4.1	3.7	3.7		19.2	22.5	18.4	23	23.5	25.5	18.4	19.6	24.5	18.8
L ₁₀(×10 ⁷)	4.0	3.8	44	3.9	4.3	4.3	3.9	4.1	3.7	3.7	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table C4 illustrates an example that 10 stove SCM, 435 steel is carried out deoxidation in the stove+high temperature tapping steel according to the present invention.

Table C4

Operation	Deoxidation in the stove+high temperature tapping (B ₂)
Operation	Deoxidation in the stove+high temperature tapping (B ₂)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	5.2	5	6	6	1.9	5.8	4.8	4.8	3.4	2.7
Tapping temperature: fusing point+℃	124	140	123	109	112	117	123	116	104	143		5.2	5	6	6	1.9	5.8	4.8	4.8	3.4	2.7
Tapping temperature: fusing point+℃	124	140	123	109	112	117	123	116	104	143	LF: the time, minute	54	45	55	49	48	52	48	45	45	54
LF: warm eventually, ℃	1567	1566	1573	1575	1575	1572	1566	1565	1567	1567	LF: the time, minute	54	45	55	49	48	52	48	45	45	54
LF: warm eventually, ℃	1567	1566	1573	1575	1575	1572	1566	1565	1567	1567	RH: the time, minute	22	24	22	24	20	21	24	21	23	24
RH: internal circulating load, multiple	7.2	6.5	5.6	6.8	6.7	5.9	6.4	7.2	6.3	6.5	RH: the time, minute	22	24	22	24	20	21	24	21	23	24
RH: internal circulating load, multiple	7.2	6.5	5.6	6.8	6.7	5.9	6.4	7.2	6.3	6.5	RH: warm eventually, ℃	1535	1539	1532	1538	1538	1536	1538	1533	1541	1541
Pouring temperature, ℃	1513	1513	1520	1514	1518	1521	1521	1521	1518	1518	RH: warm eventually, ℃	1535	1539	1532	1538	1538	1536	1538	1533	1541	1541
Pouring temperature, ℃	1513	1513	1520	1514	1518	1521	1521	1521	1518	1518	Oxygen level in the product, ppm	7.2	6.8	7.0	7.0	6.4	6.8	7.5	7.3	6.5	6.1
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	30	16	19	23	29	30	30	21	25	26	Oxygen level in the product, ppm	7.2	6.8	7.0	7.0	6.4	6.8	7.5	7.3	6.5	6.1
	30	16	19	23	29	30	30	21	25	26	The maximum predicted diameter that is mingled with body, μ m	39.0	38.1	37.1	38.5	37.8	39.8	39.0	39.4	33.8	32.9
L ₁₀(×10 ⁷)	2.8	3.3	2.9	3.5	3.1	3.5	3.3	3.0	3.7	3.6		39.0	38.1	37.1	38.5	37.8	39.8	39.0	39.4	33.8	32.9
L ₁₀(×10 ⁷)	2.8	3.3	2.9	3.5	3.1	3.5	3.3	3.0	3.7	3.6	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table C5 illustrates an example that 10 stove SUJ, 2 steel is carried out deoxidation in the stove+weak point LF, long RH operation according to the present invention.

Table C5

Operation	Deoxidation in the stove+weak point LF, long RH (A ₃)
Operation	Deoxidation in the stove+weak point LF, long RH (A ₃)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ2	SUJ 2	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ2	SUJ 2	SUJ2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	47	5	4.4	2.3	2.6	2	4.5	2.3	3.6	4.5
Tapping temperature: fusing point+℃	67	79	59	78	64	72	75	75	69	72		47	5	4.4	2.3	2.6	2	4.5	2.3	3.6	4.5
Tapping temperature: fusing point+℃	67	79	59	78	64	72	75	75	69	72	LF: the time, minute	43	31	45	40	37	35	41	30	37	45
LF: warm eventually, ℃	1546	1543	1545	1544	1545	1541	1544	1545	1546	1545	LF: the time, minute	43	31	45	40	37	35	41	30	37	45
LF: warm eventually, ℃	1546	1543	1545	1544	1545	1541	1544	1545	1546	1545	RH: the time, minute	53	56	56	59	59	59	60	56	56	58
RH: internal circulating load, multiple	17.7	18.7	18.7	19.7	19.7	19.7	20.0	18.7	18.7	19.3	RH: the time, minute	53	56	56	59	59	59	60	56	56	58
RH: internal circulating load, multiple	17.7	18.7	18.7	19.7	19.7	19.7	20.0	18.7	18.7	19.3	RH: warm eventually, ℃	1508	1502	1508	1510	1505	1508	1509	1508	1506	1506
Pouring temperature, ℃	1476	1477	1477	1478	1478	1478	1475	1477	1478	1475	RH: warm eventually, ℃	1508	1502	1508	1510	1505	1508	1509	1508	1506	1506
Pouring temperature, ℃	1476	1477	1477	1478	1478	1478	1475	1477	1478	1475	Oxygen level in the product, ppm	49	4.4	4.6	4.5	4.1	5.1	5	4.3	5	5.1
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	29	27	27	25	26	29	29	22	20	24	Oxygen level in the product, ppm	49	4.4	4.6	4.5	4.1	5.1	5	4.3	5	5.1
	29	27	27	25	26	29	29	22	20	24	The maximum predicted diameter that is mingled with body, μ m	18	18	22.8	21.1	20.8	20.5	18.2	20.6	22.6	18.7
L ₁₀(×10 ⁷)	5.7	5.9	5.1	5.4	5.7	5.5	5.8	5.6	5.2	6.0		18	18	22.8	21.1	20.8	20.5	18.2	20.6	22.6	18.7
L ₁₀(×10 ⁷)	5.7	5.9	5.1	5.4	5.7	5.5	5.8	5.6	5.2	6.0	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table C6 illustrates an example that 10 stove SCM, 435 steel is carried out deoxidation in the stove+weak point LF, long RH operation according to the present invention.

Table C6

Operation	Deoxidation in the stove+weak point LF, long RH (B ₃)
Operation	Deoxidation in the stove+weak point LF, long RH (B ₃)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	3.9	4.4	2.7	4.5	3.6	3	2.6	2.5	2.2	5.8
Tapping temperature: fusing point+℃	66	62	56	71	58	70	80	75	62	62		3.9	4.4	2.7	4.5	3.6	3	2.6	2.5	2.2	5.8
Tapping temperature: fusing point+℃	66	62	56	71	58	70	80	75	62	62	LF: the time, minute	41	44	44	44	42	39	44	39	43	38
LF: warm eventually, ℃	1581	1577	1584	1582	1577	1578	1579	1583	1583	1578	LF: the time, minute	41	44	44	44	42	39	44	39	43	38
LF: warm eventually, ℃	1581	1577	1584	1582	1577	1578	1579	1583	1583	1578	RH: the time, minute	39	41	37	43	43	44	38	37	38	45
RH: internal circulating load, multiple	13.0	13.7	12.3	14.3	14.3	14.7	12.7	12.3	12.7	15.0	RH: the time, minute	39	41	37	43	43	44	38	37	38	45
RH: internal circulating load, multiple	13.0	13.7	12.3	14.3	14.3	14.7	12.7	12.3	12.7	15.0	RH: warm eventually, ℃	1540	1534	1536	1534	1539	1532	1537	1533	1540	1533
Pouring temperature, ℃	1513	1513	1516	1514	1514	1515	1514	1514	1515	1514	RH: warm eventually, ℃	1540	1534	1536	1534	1539	1532	1537	1533	1540	1533
Pouring temperature, ℃	1513	1513	1516	1514	1514	1515	1514	1514	1515	1514	Oxygen level in the product, ppm	7	7.1	7.3	7.4	7.3	6.5	7	6.9	6.9	6.7
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	25	28	25	25	24	23	24	25	26	23	Oxygen level in the product, ppm	7	7.1	7.3	7.4	7.3	6.5	7	6.9	6.9	6.7
	25	28	25	25	24	23	24	25	26	23	The maximum predicted diameter that is mingled with body, μ m	23.7	20.7	24.6	22.7	22.9	23.7	22.8	21.7	24.8	24.6
L ₁₀(×10 ⁷)	4.5	5.1	4.4	4.8	4.9	5.1	4.8	4.8	4.3	5.7		23.7	20.7	24.6	22.7	22.9	23.7	22.8	21.7	24.8	24.6
L ₁₀(×10 ⁷)	4.5	5.1	4.4	4.8	4.9	5.1	4.8	4.8	4.3	5.7	Evaluation result	○	○	○	○	○	○	○	○	○	○

Zero: good

Table C7 illustrates an example that 10 stove SUJ, 2 steel is carried out deoxidation in the stove+high temperature tapping+weak point LF, long RH operation according to the present invention.

Table C7

Operation	Deoxidation in the stove+high temperature tapping+weak point LF, long RH (A ₄)
Operation											Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ2	SUJ 2	SUJ 2	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	2.8	2.4	3.6	5.6	3.1	1.5	2.1	5.9	3.1	1.6
Tapping temperature: fusing point+℃	133	149	162	164	119	138	122	163	137	143		2.8	2.4	3.6	5.6	3.1	1.5	2.1	5.9	3.1	1.6
Tapping temperature: fusing point+℃	133	149	162	164	119	138	122	163	137	143	LF: the time, minute	39	36	36	42	43	37	38	30	42	37
LF: warm eventually, ℃	1546	1543	1545	1544	1545	1541	1544	1545	1546	1545	LF: the time, minute	39	36	36	42	43	37	38	30	42	37
LF: warm eventually, ℃	1546	1543	1545	1544	1545	1541	1544	1545	1546	1545	RH: the time, minute	53	53	53	53	56	52	57	53	52	56
RH: internal circulating load, multiple	17.7	18.3	17.8	17.1	18.7	17.9	18.4	17.5	16.7	19.3	RH: the time, minute	53	53	53	53	56	52	57	53	52	56
RH: internal circulating load, multiple	17.7	18.3	17.8	17.1	18.7	17.9	18.4	17.5	16.7	19.3	RH: warm eventually, ℃	1495	1497	1503	1502	1501	1503	1497	1503	1500	1503
Pouring temperature, ℃	1475	1476	1476	1477	1475	1478	1476	1477	1478	1477	RH: warm eventually, ℃	1495	1497	1503	1502	1501	1503	1497	1503	1500	1503
Pouring temperature, ℃	1475	1476	1476	1477	1475	1478	1476	1477	1478	1477	Oxygen level in the product, ppm	4.8	4.2	4.7	4.7	4.4	4.1	4.4	4.8	4.5	4.2
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	14	6	8	9	6	14	13	8	15	14	Oxygen level in the product, ppm	4.8	4.2	4.7	4.7	4.4	4.1	4.4	4.8	4.5	4.2
	14	6	8	9	6	14	13	8	15	14	The maximum predicted diameter that is mingled with body, μ m	14.3	13.6	14.1	14.8	13.2	13.7	13.2	14.4	14.8	12.6
L ₁₀(×10 ⁷)	7.8	9.0	8.7	8.7	10.6	9.7	10.8	9.4	9.8	10.0		14.3	13.6	14.1	14.8	13.2	13.7	13.2	14.4	14.8	12.6
L ₁₀(×10 ⁷)	7.8	9.0	8.7	8.7	10.6	9.7	10.8	9.4	9.8	10.0	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

Table C8 illustrates an example that 10 stove SCM, 435 steel is carried out deoxidation in the stove+high temperature tapping+weak point LF, long RH operation according to the present invention.

Table C8

Operation	Deoxidation in the stove+high temperature tapping+weak point LF, long RH (B ₄)
Operation											Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	4.3	4	1.7	2.2	4.1	2.3	4.5	4.6	1.5	2.1
Tapping temperature: fusing point+℃	134	132	117	107	132	137	128	109	116	102		4.3	4	1.7	2.2	4.1	2.3	4.5	4.6	1.5	2.1
Tapping temperature: fusing point+℃	134	132	117	107	132	137	128	109	116	102	LF: the time, minute	39	33	30	41	30	36	32	35	35	44
LF: warm eventually, ℃	1577	1581	1577	1585	1584	1582	1582	1576	1582	1584	LF: the time, minute	39	33	30	41	30	36	32	35	35	44
LF: warm eventually, ℃	1577	1581	1577	1585	1584	1582	1582	1576	1582	1584	RH: the time, minute	39	39	36	42	38	42	38	40	39	41
RH: internal circulating load, multiple	11.9	12.7	12.1	13.1	11.0	14.0	11.7	12.2	12.3	12.7	RH: the time, minute	39	39	36	42	38	42	38	40	39	41
RH: internal circulating load, multiple	11.9	12.7	12.1	13.1	11.0	14.0	11.7	12.2	12.3	12.7	RH: warm eventually, ℃	1534	1540	1534	1540	1541	1532	1539	1531	1538	1532
Pouring temperature, ℃	1512	1513	1516	1513	1513	1515	1512	1516	1514	1518	RH: warm eventually, ℃	1534	1540	1534	1540	1541	1532	1539	1531	1538	1532
Pouring temperature, ℃	1512	1513	1516	1513	1513	1515	1512	1516	1514	1518	Oxygen level in the product, ppm	6.3	5.5	5.5	5.4	6.0	6.0	5.6	6.5	5.7	5.6
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	13	6	11	9	5	8	11	14	10	14	Oxygen level in the product, ppm	6.3	5.5	5.5	5.4	6.0	6.0	5.6	6.5	5.7	5.6
	13	6	11	9	5	8	11	14	10	14	The maximum predicted diameter that is mingled with body, μ m	24.0	23.5	23.3	22.5	23.9	23.7	23.8	24.6	23.7	23.6
L ₁₀(×10 ⁷)	9.2	8.8	10.1	9.7	10.3	8.7	9.8	9.9	10.7	9.9		24.0	23.5	23.3	22.5	23.9	23.7	23.8	24.6	23.7	23.6
L ₁₀(×10 ⁷)	9.2	8.8	10.1	9.7	10.3	8.7	9.8	9.9	10.7	9.9	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

In order to contrast with the present invention, table C9 illustrates an example of SUJ 2 steel being operated according to prior art, and table C10 illustrates an example of the SCM435 steel being operated according to prior art

Table C9

Operation	Traditional operation (prior art)
Operation	Traditional operation (prior art)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	57	72	58	60	74	75	51	65	62	68
Tapping temperature: fusing point+℃	-	-	-	-	-	-	-	-	-	-		57	72	58	60	74	75	51	65	62	68
Tapping temperature: fusing point+℃	-	-	-	-	-	-	-	-	-	-	LF: the time, minute	61	61	63	61	62	62	61	63	61	63
LF: warm eventually, ℃	1525	1524	1526	1525	1523	1524	1523	1520	1525	1520	LF: the time, minute	61	61	63	61	62	62	61	63	61	63
LF: warm eventually, ℃	1525	1524	1526	1525	1523	1524	1523	1520	1525	1520	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	5.7	6.7	7.1	6.5	6.2	5.7	7	5.5	6.8	6.2	RH: the time, minute	23	23	23	23	23	23	23	23	23	23
RH: internal circulating load, multiple	5.7	6.7	7.1	6.5	6.2	5.7	7	5.5	6.8	6.2	RH: warm eventually, ℃	1493	1502	1501	1497	1501	1501	1502	1503	1496	1499
Pouring temperature, ℃	1477	1475	1475	1475	1475	1475	1476	1478	1478	1476	RH: warm eventually, ℃	1493	1502	1501	1497	1501	1501	1502	1503	1496	1499
Pouring temperature, ℃	1477	1475	1475	1475	1475	1475	1476	1478	1478	1476	Oxygen level in the product, ppm	5.4	5.1	5.1	6.1	5.8	5.9	5.8	5.9	5.2	6.2
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	59	56	54	65	48	41	50	47	45	49	Oxygen level in the product, ppm	5.4	5.1	5.1	6.1	5.8	5.9	5.8	5.9	5.2	6.2
	59	56	54	65	48	41	50	47	45	49	The maximum predicted diameter that is mingled with body, μ m	86.4	61.2	66.3	97.6	81.2	76.7	92.8	76.7	72.8	74.4
L ₁₀(×10 ⁷)	1.9	2.4	2.4	1.8	1.9	3.4	1.9	2.2	2.0	2.2		86.4	61.2	66.3	97.6	81.2	76.7	92.8	76.7	72.8	74.4
L ₁₀(×10 ⁷)	1.9	2.4	2.4	1.8	1.9	3.4	1.9	2.2	2.0	2.2	Evaluation result	×	×	×	×	×	×	×	×	×	×

*: poor

Table C10

Operation	Traditional operation (prior art)
Operation	Traditional operation (prior art)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	The add-on of reductor (Si, Mn, Al etc.) during deoxidation in the stove, kg/t	61	54	69	50	74	58	58	69	64	54
Tapping temperature: fusing point+℃	-	-	-	-	-	-	-	-	-	-		61	54	69	50	74	58	58	69	64	54
Tapping temperature: fusing point+℃	-	-	-	-	-	-	-	-	-	-	LF: the time, minute	62	63	61	61	61	63	63	63	61	61
LF: warm eventually, ℃	1570	1574	1566	1572	1567	1569	1567	1569	1569	1570	LF: the time, minute	62	63	61	61	61	63	63	63	61	61
LF: warm eventually, ℃	1570	1574	1566	1572	1567	1569	1567	1569	1569	1570	RH: the time, minute	23	23	23	20	21	23	21	23	23	24
RH: internal circulating load, multiple	6.8	7.5	7.0	8.3	6.2	6.0	74	8.0	7.3	6.7	RH: the time, minute	23	23	23	20	21	23	21	23	23	24
RH: internal circulating load, multiple	6.8	7.5	7.0	8.3	6.2	6.0	74	8.0	7.3	6.7	RH: warm eventually, ℃	1533	1538	1541	1540	1541	1533	1535	1534	1531	1531
Pouring temperature, ℃	1517	1519	1520	1518	1517	1511	1516	1512	1512	1521	RH: warm eventually, ℃	1533	1538	1541	1540	1541	1533	1535	1534	1531	1531
Pouring temperature, ℃	1517	1519	1520	1518	1517	1511	1516	1512	1512	1521	Oxygen level in the product, ppm	7.6	9.2	9.2	8.8	6.9	8.3	6.9	8.3	9.4	9.1
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	49	54	59	52	42	57	56	53	53	42	Oxygen level in the product, ppm	7.6	9.2	9.2	8.8	6.9	8.3	6.9	8.3	9.4	9.1
	49	54	59	52	42	57	56	53	53	42	The maximum predicted diameter that is mingled with body, μ m	68.4	82.8	73.6	70.4	55.2	83.0	55.2	83.0	84.6	91.0
L ₁₀(×10 ⁷)	1.0	1.3	1.1	1.9	2.3	1.5	2.0	1.2	1.2	1.9		68.4	82.8	73.6	70.4	55.2	83.0	55.2	83.0	84.6	91.0
L ₁₀(×10 ⁷)	1.0	1.3	1.1	1.9	2.3	1.5	2.0	1.2	1.2	1.9	Evaluation result	×	×	×	×	×	×	×	×	×	×

*: poor

C1-C8 can clearly be seen that from table: for product made from steel produced according to the invention, wherein, the molten steel that generates in electrometal furnace or converter carries out deoxidation in the stove in same stove, transfer to then and carry out refining in the ladle furnace, circulate so that liquid steel degassing by circulating vacuum degasser then, be higher than the traditional operation temperature (promptly, during fusing point+at least 100 ℃) deoxidation in the employing stove down+high temperature tapping combination operation, adopt deoxidation in the stove that shortens the operating time in the ladle furnace+weak point LF, during combination operation that long RH handles, and the amount of increase circulation RH (promptly in the circulating degasification process, circulation molten steel amount/molten steel total amount) when outgasing for a long time satisfactorily, and the combination of all above-mentioned treatment steps of employing, promptly, deoxidation in the stove+high temperature tapping+weak point LF, when long RH handles, no matter be SUJ 2 steel or SCM 435 steel, can both reduce the oxygen level of product, that can also reduce significantly that granularity is not less than 20 μ m is mingled with the body number.C1-C8 it can also be seen that from table: as for cleanliness factor, for example of the present invention, all product made from steel all are be evaluated as generally (△), good (zero) or outstanding (◎), that is, all be outstanding cleanness steel.On the contrary, from showing C9 and C10 as can be seen: for all traditional examples, its cleanliness factor is be evaluated as poor (*), and the not talkative one-tenth of traditional product made from steel is Clean Steel.Should be noted that in this: general (△) compares with good (zero) and outstanding (◎), if do not compare with do not carry out the steel that tapping deoxidization is be evaluated as poor (*) according to art methods, these are be evaluated as generally that the steel of (△) then has higher cleanliness factor.

For having carried out the product made from steel of deoxidation in the stove, oxygen level and maximum are mingled with the predictor of body diameter all because of T _SH[(temperature when molten steel is transferred to ladle furnace)-(fusing point of molten steel)=T _SH] increase and reduce, thereby improved the cleanliness factor of steel.For having carried out the product made from steel of deoxidation in the stove, relation between refining time in the ladle furnace and oxygen level and the maximum predictor that is mingled with the body diameter is: when refining time was not less than about 25 minutes, the predictor that oxygen level and maximum are mingled with the body diameter can both reduce satisfactorily.But the maximum predictor that is mingled with the body diameter but increases along with the increase of refining time.Can think that its reason is as follows: along with the prolongation of time, the melting loss vector of refractory materials increases in the ladle refining furnace, the balance of slag system is broken, and for example, this is the minimum value that the oxidizing reaction that produces because contact with air and dissolved oxygen amount have surpassed dissolved oxygen.In addition, relation in circulating vacuum degasser between circulation molten steel amount/molten steel total amount and oxygen level and the maximum predictor that is mingled with the body diameter is: the raising effect of cleanliness factor increases with the increase of circulation molten steel amount, when circulation molten steel amount/when the molten steel total amount is not less than 15, this effect state that reaches capacity basically.

Figure C1 is the broken line graph that the oxygen level of the 10 stove product made from steel of producing in accordance with the present production process is shown, in the process that SUJ 2 molten steel are handled, oxidation refining molten steel in electrometal furnace or converter, before tapping, in same stove, add reductor then, make deoxidation of molten steel, the molten steel of pre-deoxidation transferred to carry out ladle refining in the ladle furnace, circulate with liquid steel degassing by circulating vacuum degasser then, scheme C1 and also be illustrated in the oxygen level of not carrying out 10 stove SUJ, 2 product made from steel of deoxidation in the stove in the traditional method.In figure C1, C3 and C5, A ₁Data when deoxidation in the stove that adopts claim 15 definition according to the present invention only is shown, A ₂Data when deoxidation in the stove of according to the present invention claim 16 definition+high temperature tapping is shown, A ₃Deoxidation+short period of time LF in the stove that claim 17 defines according to the present invention, the data when long-time RH handles are shown, A ₄Deoxidation+high temperature tapping+short period of time LF in the stove that claim 17 defines according to the present invention, the data when long-time RH handles are shown, traditional data of the prior art also is shown among these figure.

Figure C2 is the broken line graph that the oxygen level of the 10 stove product made from steel of producing in accordance with the present production process is shown, in the process that SCM 435 molten steel are handled, oxidation refining molten steel in electrometal furnace or converter, before tapping, in same stove, add reductor then, make deoxidation of molten steel, the molten steel of pre-deoxidation transferred to carry out ladle refining in the ladle furnace, then in circulating vacuum degasser with liquid steel degassing, figure C2 also is illustrated in the oxygen level of not carrying out 10 stove SCM, 435 product made from steel of deoxidation in the stove in the traditional method.In Figure 16,18 and 20, B ₁Data when deoxidation in the stove that adopts claim 15 definition according to the present invention only is shown, B ₂Data when deoxidation in the stove of according to the present invention claim 16 definition+high temperature tapping is shown, B ₃Deoxidation+short period of time LF in the stove that claim 17 defines according to the present invention, the data when long-time RH handles are shown, B ₄Deoxidation+high temperature tapping+short period of time LF in the stove that claim 17 defines according to the present invention, the data when long-time RH handles are shown, the traditional data of not carrying out deoxidation in the stove in the prior art also is shown among these figure.

Figure C3 is illustrated in the production method of the present invention the broken line graph that the maximum predicted of SUJ 2 molten steel being carried out obtain according to these statisticss of extremes in the 10 stove product made from steel of deoxidation treatment in the stove according to claim 15-17 is mingled with the body diameter, and figure C3 also illustrates the maximum predicted of not carrying out in 10 stove SUJ, 2 product made from steel of deoxidation in the stove according to traditional method and is mingled with the body diameter.

Figure C4 is illustrated in the production method of the present invention the broken line graph that the maximum predicted of SCM 435 molten steel being carried out obtain according to these statisticss of extremes in the 10 stove product made from steel of deoxidation treatment in the stove according to claim 15-17 is mingled with the body diameter, and figure C4 also illustrates the maximum predicted of not carrying out in 10 stove SCM, 435 product made from steel of deoxidation in the stove according to traditional method and is mingled with the body diameter.

Figure C5 is illustrated in the L according to tappet roller measuring in work-ing life that according to claim 15-17 SUJ 2 molten steel is carried out 10 stove product made from steel of deoxidation treatment in the stove in the production method of the present invention ₁₀The broken line graph in life-span, figure C5 also illustrates the L that does not carry out 10 stove SUJ, 2 product made from steel of deoxidation in the stove according to traditional method ₁₀Life-span.

Figure C6 is illustrated in the L according to tappet roller measuring in work-ing life that according to claim 15-17 SCM 435 molten steel is carried out 10 stove product made from steel of deoxidation treatment in the stove in the production method of the present invention ₁₀The broken line graph in life-span, figure C6 also illustrates the L that does not carry out 10 stove SCM435 product made from steel of deoxidation in the stove according to traditional method ₁₀Life-span.

Can fully prove by these experimental results: in accordance with the present production process, oxidation refining molten steel in electrometal furnace or converter, before tapping, in same stove, add reductor then, make deoxidation of molten steel, the molten steel of pre-deoxidation transferred to carry out ladle refining in the ladle furnace, then in circulating vacuum degasser with liquid steel degassing, no matter still can significantly reduce the oxygen level of product and the predictor that maximum is mingled with the body diameter to SCM 435 steel capital to SUJ 2 steel, its cleanliness factor can be significantly improved, L can be significantly improved according to tappet roller measuring in work-ing life ₁₀Life-span.In the production method of steel, add these treatment steps, that is, only add deoxygenation step in the stove that claim 15 defines according to the present invention, add deoxidation in the stove that claim 16 defines according to the present invention+high temperature tapping step, add deoxidation+short period of time LF in the stove that claim 17 defines according to the present invention, long-time RH treatment step, or add deoxidation+high temperature tapping+short period of time LF in the stove of according to the present invention claim 17 definition, long-time RH treatment step can significantly improve the oxygen level of all steel, maximum is mingled with the predictor of body diameter and according to the L of tappet roller measuring in work-ing life ₁₀Life-span.

Can clearly be seen that from above-mentioned explanation: can the very high product made from steel of mass production cleanliness factor according to the present invention, and needn't the very high remelting processing of use cost.So just can provide cleanness steel, it is suitable for the machine steel of doing to require to have fatigue strength and fatigue lifetime, particularly suitable is done as rolling bearing steel, constant speed tieing steel, gear steel, annular continuous change transmission steel, that is, the present invention has unexpected unprecedented advantage.

Embodiment D

Generate and the oxidizing semlting molten steel by method of fusion in electrometal furnace, molten steel is transferred to carried out ladle refining in the ladle furnace then, the ladle refining time is very short, is no more than 60 minutes.Be no less than 25 minutes the degassing then, specifically, the condition that outgases in circulating vacuum degasser is 8 times that circulation molten steel amount is not less than the molten steel total amount, carries out the steel ingot production technique with teeming practice then.10 stove JIS SUJ 2 and SCM 435 product made from steel that obtain are like this detected, and the maximum that measure oxygen level in the product, obtains according to the statistical calculations of extreme value is mingled with the predictor of body diameter and according to the L of tappet roller measuring in work-ing life ₁₀Work-ing life.When the mensuration maximum is mingled with the predictor of body diameter, forge materials from φ 65 and get next experiment slice, 30 experiment slices are carried out 100mm ²Observation, according to the Principle of Statistics of these extreme values prediction 30000mm ²In maximum be mingled with the body diameter.In tappet roller experiment in work-ing life, the experiment slice that at first will be of a size of φ 60 * φ 20 * 8.3T carries out carburizing, quench hardening and tempering, experimentizes under the maximum hertz stress Pmax of 4900MPa then, determines L by calculating then ₁₀Work-ing life.

Table D1 illustrates an example that 10 stove SUJ, 2 steel is carried out following operation, oxidation refining molten steel in electrometal furnace or converter, then molten steel is transferred to and be no more than 60 minutes ladle refining in the ladle furnace, (being called " short period of time LF, long-time RH or short LF or long RH " in this application) handled in the degassing that is no less than 25 minutes then in circulating vacuum degasser, that is, carry out short period of time LF, long-time RH processing.

Table D1

Operation	Short LF, long RH (A ₁)
Operation	Short LF, long RH (A ₁)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	67	79	59	78	64	72	75	61	57	59
LF: the time, minute	43	31	45	40	37	35	41	30	37	45	Tapping temperature: fusing point+℃	67	79	59	78	64	72	75	61	57	59
LF: the time, minute	43	31	45	40	37	35	41	30	37	45	LF: warm eventually, ℃	1546	1543	1545	1544	1526	1541	1544	1534	1530	1524
RH: the time, minute	53	56	56	59	29	59	60	44	38	27	LF: warm eventually, ℃	1546	1543	1545	1544	1526	1541	1544	1534	1530	1524
RH: the time, minute	53	56	56	59	29	59	60	44	38	27	RH: internal circulating load, multiple	17.7	18.7	18.7	19.7	9.0	19.7	20.0	13.7	11.9	8.5
RH: warm eventually, ℃	1508	1502	1508	1510	1505	1508	1509	1508	1506	1506	RH: internal circulating load, multiple	17.7	18.7	18.7	19.7	9.0	19.7	20.0	13.7	11.9	8.5
RH: warm eventually, ℃	1508	1502	1508	1510	1505	1508	1509	1508	1506	1506	Pouring temperature, ℃	1476	1477	1477	1478	1478	1478	1475	1477	1478	1475
Oxygen level in the product, ppm	4.9	4.4	4.6	4.5	5.3	5.1	5	4.8	5.2	5	Pouring temperature, ℃	1476	1477	1477	1478	1478	1478	1475	1477	1478	1475
Oxygen level in the product, ppm	4.9	4.4	4.6	4.5	5.3	5.1	5	4.8	5.2	5	What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	29	27	27	25	30	29	29	26	27	28
The maximum predicted diameter that is mingled with body, μ m	18	18	22.8	21.1	22.9	20.5	18.2	20.6	20.1	21.7		29	27	27	25	30	29	29	26	27	28
	18	18	22.8	21.1	22.9	20.5	18.2	20.6	20.1	21.7	L ₁₀(×10 ⁷)	5.7	5.1	4.1	4.9	4.6	4.1	5.3	4.2	4.7	4.7
Evaluation result	○	○	○	○	○	○	○	○	○	○	L ₁₀(×10 ⁷)	5.7	5.1	4.1	4.9	4.6	4.1	5.3	4.2	4.7	4.7

Zero: good

Table D2 illustrates an example that 10 stove SCM, 435 steel is carried out following operation, oxidation refining molten steel in electrometal furnace or converter, then molten steel is transferred to and be no more than 60 minutes ladle refining in the ladle furnace, the degassing that is no less than 25 minutes then in circulating vacuum degasser is handled, that is, carry out short period of time LF, long-time RH processing.

Table D2

Operation	Short LF, long RH (B ₁)
Operation	Short LF, long RH (B ₁)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	66	62	56	71	58	70	80	75	62	62
LF: the time, minute	41	44	44	44	42	39	44	39	43	38	Tapping temperature: fusing point+℃	66	62	56	71	58	70	80	75	62	62
LF: the time, minute	41	44	44	44	42	39	44	39	43	38	LF: warm eventually, ℃	1581	1568	1584	1571	1577	1578	1579	1583	1572	1578
RH: the time, minute	39	26	37	30	43	44	38	37	29	45	LF: warm eventually, ℃	1581	1568	1584	1571	1577	1578	1579	1583	1572	1578
RH: the time, minute	39	26	37	30	43	44	38	37	29	45	RH: internal circulating load, multiple	13.0	8.2	12.3	9.5	14.3	14.7	12.7	12.3	8.8	15.0
RH: warm eventually, ℃	1540	1534	1536	1534	1539	1532	1537	1533	1540	1533	RH: internal circulating load, multiple	13.0	8.2	12.3	9.5	14.3	14.7	12.7	12.3	8.8	15.0
RH: warm eventually, ℃	1540	1534	1536	1534	1539	1532	1537	1533	1540	1533	Pouring temperature, ℃	1513	1513	1516	1514	1514	1515	1514	1514	1515	1514
Oxygen level in the product, ppm	7	7.7	7.3	7.5	7.3	6.5	7	6.9	7.4	6.7	Pouring temperature, ℃	1513	1513	1516	1514	1514	1515	1514	1514	1515	1514
Oxygen level in the product, ppm	7	7.7	7.3	7.5	7.3	6.5	7	6.9	7.4	6.7	What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	25	29	25	27	24	23	24	25	28	23
The maximum predicted diameter that is mingled with body, μ m	23.7	24.8	24.6	24.1	22.9	23.7	22.8	21.7	24.2	24.6		25	29	25	27	24	23	24	25	28	23
	23.7	24.8	24.6	24.1	22.9	23.7	22.8	21.7	24.2	24.6	L ₁₀(×10 ⁷)	2.9	2.3	3.9	3.4	3.4	3.5	3.8	4.0	3.0	3.9
Evaluation result	○	○	○	○	○	○	○	○	○	○	L ₁₀(×10 ⁷)	2.9	2.3	3.9	3.4	3.4	3.5	3.8	4.0	3.0	3.9

Zero: good

Table D3 illustrates an example that 10 stove SUJ, 2 steel is carried out following operation, oxidation refining molten steel in electrometal furnace or converter, then in the tapping (being called " high temperature tapping " in the specification sheets in the application) under the high 100 ℃ high temperature than molten steel fusing point at least, molten steel transferred to be no more than 60 minutes ladle refining in the ladle furnace, the degassing that is no less than 25 minutes then in circulating vacuum degasser is handled, that is, carry out short period of time LF, long-time RH processing+high temperature tapping.

Table D3

Operation	High temperature tapping+weak point LF, long RH handle (A ₂)
Operation											Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	133	149	162	164	119	138	122	163	137	143
LF: the time, minute	39	36	36	42	43	37	38	30	42	37	Tapping temperature: fusing point+℃	133	149	162	164	119	138	122	163	137	143
LF: the time, minute	39	36	36	42	43	37	38	30	42	37	LF: warm eventually, ℃	1531	1543	1545	1537	1545	1541	1544	1533	1524	1531
RH: the time, minute	41	53	53	48	56	52	57	38	29	35	LF: warm eventually, ℃	1531	1543	1545	1537	1545	1541	1544	1533	1524	1531
RH: the time, minute	41	53	53	48	56	52	57	38	29	35	RH: internal circulating load, multiple	12.6	18.3	17.8	15.7	18.7	17.9	18.4	11.5	9.0	10.5
RH: warm eventually, ℃	1495	1497	1503	1502	1501	1503	1497	1503	1500	1503	RH: internal circulating load, multiple	12.6	18.3	17.8	15.7	18.7	17.9	18.4	11.5	9.0	10.5
RH: warm eventually, ℃	1495	1497	1503	1502	1501	1503	1497	1503	1500	1503	Pouring temperature, ℃	1475	1476	1476	1477	1475	1478	1476	1477	1478	1477
Oxygen level in the product, ppm	4.8	4.2	4.7	4.7	4.4	4.1	4.4	4.8	4.5	4.2	Pouring temperature, ℃	1475	1476	1476	1477	1475	1478	1476	1477	1478	1477
Oxygen level in the product, ppm	4.8	4.2	4.7	4.7	4.4	4.1	4.4	4.8	4.5	4.2	What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	14	6	8	9	6	14	13	8	15	14
The maximum predicted diameter that is mingled with body, μ m	14.3	13.6	14.1	14.8	13.2	13.7	13.2	14.4	14.8	12.6		14	6	8	9	6	14	13	8	15	14
	14.3	13.6	14.1	14.8	13.2	13.7	13.2	14.4	14.8	12.6	L ₁₀(×10 ⁷)	8.0	10.6	9.6	8.8	9.0	9.4	9.7	7.3	7.7	10.9
Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎	L ₁₀(×10 ⁷)	8.0	10.6	9.6	8.8	9.0	9.4	9.7	7.3	7.7	10.9

◎: outstanding

Table D4 illustrates an example that 10 stove SCM, 435 steel is carried out following operation, oxidation refining molten steel in electrometal furnace or converter, at least tapping under the high 100 ℃ high temperature than molten steel fusing point then, molten steel transferred to be no more than 60 minutes ladle refining in the ladle furnace, the degassing that is no less than 25 minutes then in circulating vacuum degasser is handled, that is, carry out short period of time LF, long-time RH processing+high temperature tapping.

Table D4

Operation	High temperature tapping+weak point LF, long RH handle (B2)
Operation	High temperature tapping+weak point LF, long RH handle (B2)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	134	132	117	107	132	137	128	109	116	102
LF: the time, minute	39	33	30	41	30	36	32	35	35	44	Tapping temperature: fusing point+℃	134	132	117	107	132	137	128	109	116	102
LF: the time, minute	39	33	30	41	30	36	32	35	35	44	LF: warm eventually, ℃	1577	1581	1577	1585	1584	1582	1582	1576	1570	1569
RH: the time, minute	39	39	36	42	38	42	38	33	28	29	LF: warm eventually, ℃	1577	1581	1577	1585	1584	1582	1582	1576	1570	1569
RH: the time, minute	39	39	36	42	38	42	38	33	28	29	RH: internal circulating load, multiple	11.9	12.7	12.1	13.1	11.0	14.0	11.7	11.0	8.9	9.6
RH: warm eventually, ℃	1534	1540	1534	1540	1541	1532	1539	1531	1538	1532	RH: internal circulating load, multiple	11.9	12.7	12.1	13.1	11.0	14.0	11.7	11.0	8.9	9.6
RH: warm eventually, ℃	1534	1540	1534	1540	1541	1532	1539	1531	1538	1532	Pouring temperature, ℃	1512	1513	1516	1513	1513	1515	1512	1516	1514	1518
Oxygen level in the product, ppm	6.3	5.5	5.5	5.4	6.0	6.0	5.6	6.5	6.8	6.3	Pouring temperature, ℃	1512	1513	1516	1513	1513	1515	1512	1516	1514	1518
Oxygen level in the product, ppm	6.3	5.5	5.5	5.4	6.0	6.0	5.6	6.5	6.8	6.3	What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	13	6	11	9	5	8	11	14	14	14
The maximum predicted diameter that is mingled with body, μ m	24.0	23.5	23.3	22.5	23.9	23.7	23.8	24.6	23.7	23.6		13	6	11	9	5	8	11	14	14	14
	24.0	23.5	23.3	22.5	23.9	23.7	23.8	24.6	23.7	23.6	L ₁₀(×10 ⁷)	7.2	9.9	10.0	8.7	7.4	8.1	8.6	9.7	9.3	9.3
Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎	L ₁₀(×10 ⁷)	7.2	9.9	10.0	8.7	7.4	8.1	8.6	9.7	9.3	9.3

◎: outstanding

In order to contrast with the present invention, table D5 illustrates an example of SUJ 2 steel being operated according to prior art, and table D6 illustrates an example of the SCM435 steel being operated according to prior art.

Table D5

Operation	Traditional operation (prior art)
Operation	Traditional operation (prior art)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	SUJ 2	Tapping temperature: fusing point+℃	70	70	79	58	77	76	73	55	58	60
LF: the time, minute	74	74	68	75	64	71	66	70	65	74	Tapping temperature: fusing point+℃	70	70	79	58	77	76	73	55	58	60
LF: the time, minute	74	74	68	75	64	71	66	70	65	74	LF: warm eventually, ℃	1523	1524	1524	1524	1523	1520	1522	1520	1523	1524
RH: the time, minute	20	21	21	21	20	18	20	19	23	22	LF: warm eventually, ℃	1523	1524	1524	1524	1523	1520	1522	1520	1523	1524
RH: the time, minute	20	21	21	21	20	18	20	19	23	22	RH: internal circulating load, multiple	6.7	7.0	7.0	7.0	6.7	6.0	6.7	6.3	7.7	7.3
RH: warm eventually, ℃	1494	1497	1492	1493	1498	1498	1492	1499	1497	1499	RH: internal circulating load, multiple	6.7	7.0	7.0	7.0	6.7	6.0	6.7	6.3	7.7	7.3
RH: warm eventually, ℃	1494	1497	1492	1493	1498	1498	1492	1499	1497	1499	Pouring temperature, ℃	1476	1477	1478	1476	1475	1478	1478	1478	1475	1476
Oxygen level in the product, ppm	5.7	5.7	5.8	5.2	6	5.1	5.3	5.2	5.6	6.3	Pouring temperature, ℃	1476	1477	1478	1476	1475	1478	1478	1478	1475	1476
Oxygen level in the product, ppm	5.7	5.7	5.8	5.2	6	5.1	5.3	5.2	5.6	6.3	What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	47	44	42	54	46	53	44	45	44	43
The maximum predicted diameter that is mingled with body, μ m	76.3	77.2	68.2	68.5	82.3	63.9	76.5	91.3	70.3	68.5		47	44	42	54	46	53	44	45	44	43
	76.3	77.2	68.2	68.5	82.3	63.9	76.5	91.3	70.3	68.5	L ₁₀(×10 ⁷)	3.5	2.4	1.8	2.7	2.9	3.8	4.1	3.1	2.4	1.8
Evaluation result	×	×	×	×	×	×	×	×	×	×	L ₁₀(×10 ⁷)	3.5	2.4	1.8	2.7	2.9	3.8	4.1	3.1	2.4	1.8

*: poor

Table D6

Operation	Traditional operation (prior art)
Operation	Traditional operation (prior art)										Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Tapping temperature: fusing point+℃	61	62	60	61	56	57	63	62	62	63
LF: the time, minute	63	64	66	64	68	67	71	62	75	69	Tapping temperature: fusing point+℃	61	62	60	61	56	57	63	62	62	63
LF: the time, minute	63	64	66	64	68	67	71	62	75	69	LF: warm eventually, ℃	1565	1567	1569	1572	1565	1569	1566	1566	1565	1571
RH: the time, minute	19	19	18	21	18	23	19	20	18	20	LF: warm eventually, ℃	1565	1567	1569	1572	1565	1569	1566	1566	1565	1571
RH: the time, minute	19	19	18	21	18	23	19	20	18	20	RH: internal circulating load, multiple	6.3	6.3	6.0	7.0	6.0	7.7	6.3	6.7	6.0	6.7
RH: warm eventually, ℃	1535	1534	1536	1532	1541	1540	1535	1541	1539	1535	RH: internal circulating load, multiple	6.3	6.3	6.0	7.0	6.0	7.7	6.3	6.7	6.0	6.7
RH: warm eventually, ℃	1535	1534	1536	1532	1541	1540	1535	1541	1539	1535	Pouring temperature, ℃	1516	1519	1511	1518	1515	1516	1515	1517	1515	1512
Oxygen level in the product, ppm	9.5	6.5	5.3	5.5	6	6.3	6.3	6.3	5.7	5.2	Pouring temperature, ℃	1516	1519	1511	1518	1515	1516	1515	1517	1515	1512
Oxygen level in the product, ppm	9.5	6.5	5.3	5.5	6	6.3	6.3	6.3	5.7	5.2	What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	51	49	48	58	60	43	56	47	43	54
The maximum predicted diameter that is mingled with body, μ m	58.3	60.4	65.8	72.6	69.7	75.3	78.7	61	78.6	83.9		51	49	48	58	60	43	56	47	43	54
	58.3	60.4	65.8	72.6	69.7	75.3	78.7	61	78.6	83.9	L ₁₀(×10 ⁷)	0.9	1.8	2.3	1.1	1.7	1.4	1.4	2.4	2.3	1.7
Evaluation result	×	×	×	×	×	×	×	×	×	×	L ₁₀(×10 ⁷)	0.9	1.8	2.3	1.1	1.7	1.4	1.4	2.4	2.3	1.7

*: poor

D1-D4 can clearly be seen that from table: for use short LF according to the present invention, the product made from steel of long RH process for producing, wherein, the molten steel that generates in electrometal furnace or converter is transferred in the ladle furnace and is carried out the short period of time (promptly, be no more than 60 minutes) ladle refining, then by circulating vacuum degasser circulation molten steel, increase the RH internal circulating load (promptly, circulation molten steel amount/molten steel total amount) and carry out long-time (promptly, be no less than 25 minutes) degassing, be higher than the traditional operation temperature (promptly, fusing point+at least 100 ℃) adopt short LF down, the steel that long RH processing+high temperature tapping combination operation is produced, no matter be SUJ 2 steel or SCM435 steel, its oxygen level is all very low, and that can also reduce significantly like this that granularity is not less than 20 μ m is mingled with the body number.D1-D4 it can also be seen that from table: for example of the present invention, all product made from steel all are be evaluated as well (zero) or outstanding (◎), that is, all be outstanding cleanness steel.On the contrary, from showing D5 and D6 as can be seen: for all traditional examples, its cleanliness factor is be evaluated as poor (*), and the not talkative one-tenth of traditional product made from steel is Clean Steel.

For the steel of oxidizing semlting molten steel in electrometal furnace or converter, oxygen level and maximum are mingled with the predictor of body diameter all because of T _SH[(temperature when molten steel is transferred to ladle furnace)-(fusing point of molten steel)=T _SH] increase and reduce, thereby improved the cleanliness factor of steel.For these product made from steel, the relation that refining time in the ladle furnace and oxygen level and maximum are mingled with between the predictor of body diameter is: when refining time is not more than 60 minutes, as when being less than or equal to about 25 minutes, oxygen level and the maximum predictor that is mingled with the body diameter can both reduce satisfactorily.But the maximum predictor that is mingled with the body diameter but increases along with the increase of refining time.Can think that its reason is as follows: along with the prolongation of time, the melting loss vector of refractory materials increases in the ladle refining furnace, the balance of slag system is broken, and for example, this is the minimum value that the oxidizing reaction that produces because contact with air and dissolved oxygen amount have surpassed dissolved oxygen.In addition, relation in circulating vacuum degasser between circulation molten steel amount/molten steel total amount and oxygen level and the maximum predictor that is mingled with the body diameter is: the raising effect of cleanliness factor increases with the increase of circulation molten steel amount, when circulation molten steel amount/when the molten steel total amount is not less than 15, this effect state that reaches capacity basically.

Figure D1 is the broken line graph that the oxygen level of the 10 stove product made from steel of producing in accordance with the present production process is shown, in the process that SUJ 2 molten steel are handled, in electrometal furnace or converter, generate and the oxidation refining molten steel by method of fusion, then molten steel is transferred to the ladle refining that carries out the short period of time in the ladle furnace, carry out long circulating vacuum outgas then, figure D1 also is illustrated in the oxygen level of 10 stove SUJ, 2 product made from steel of producing in the traditional method, in traditional method, in electrometal furnace or converter, generate and the oxidation refining molten steel by method of fusion, then molten steel is transferred to and carried out long ladle refining in the ladle furnace, carry out the circulating vacuum outgas of short period of time then.In figure D1, D3 and D5, A ₁Short period of time LF, the data when long-time RH handles of employing claim 22 definition according to the present invention are shown, A ₂Data when the high temperature tapping+short period of time LF of claim 23 definition according to the present invention, long-time RH treatment combination are shown also illustrate the traditional data according to traditional method among these figure.

Figure D2 is the broken line graph that the oxygen level of the 10 stove product made from steel of producing in accordance with the present production process is shown, in the process that SCM 435 molten steel are handled, in electrometal furnace or converter, generate and the oxidation refining molten steel by method of fusion, then molten steel is transferred to the ladle refining that carries out the short period of time in the ladle furnace, carry out long circulating vacuum outgas then, figure D2 also is illustrated in the oxygen level of 10 stove SCM, 435 product made from steel of producing in the traditional method, in traditional method, in electrometal furnace or converter, generate and the oxidation refining molten steel by method of fusion, then molten steel is transferred to and carried out long ladle refining in the ladle furnace, carry out the circulating vacuum outgas of short period of time then.In figure D1, D3 and D5, A ₁Short period of time LF, the data when long-time RH handles of employing claim 22 definition according to the present invention are shown, A ₂Data when the high temperature tapping+short period of time LF of claim 23 definition according to the present invention, long-time RH treatment combination are shown also illustrate the traditional data according to traditional method among these figure.

Figure D3 is illustrated in the production method of the present invention the broken line graph that the maximum predicted that obtains according to statistics of extremes in the 10 stove product made from steel of SUJ 2 molten steel being handled according to the method for claim 22 or 23 is mingled with the body diameter, figure D3 also illustrates the maximum predicted that obtains according to these statisticss of extremes in 10 stove SUJ, 2 product made from steel according to produced in conventional processes and is mingled with the body diameter, in the method for conventional process SUJ 2 molten steel, carry out long-time LF, short period of time RH and handle.

Figure D4 is illustrated in the production method of the present invention the broken line graph that the maximum predicted that obtains according to statistics of extremes in the 10 stove product made from steel of SCM 435 molten steel being handled according to the method for claim 22 or 23 is mingled with the body diameter, figure D4 also illustrates the maximum predicted that obtains according to these statisticss of extremes in 10 stove SCM, 435 product made from steel according to produced in conventional processes and is mingled with the body diameter, in the method for conventional process SCM 435 molten steel, carry out long-time LF, short period of time RH and handle.

Figure D5 is the L according to tappet roller measuring in work-ing life that is illustrated in the production method of the present invention the 10 stove product made from steel of handling according to claim 22 or 23 pairs of SUJ 2 molten steel ₁₀The broken line graph in life-span, figure D5 also illustrates the L according to tappet roller measuring in work-ing life according to 10 stove SUJ, 2 product made from steel of produced in conventional processes ₁₀In the life-span, in the method for conventional process SUJ 2 molten steel, carry out long-time LF, short period of time RH and handle.

Figure D6 is the L according to tappet roller measuring in work-ing life that is illustrated in the production method of the present invention the 10 stove product made from steel of handling according to claim 22 or 23 pairs of SCM 435 molten steel ₁₀The data in life-span, figure D6 also illustrates the L according to tappet roller measuring in work-ing life according to 10 stove SCM, 435 product made from steel of produced in conventional processes ₁₀In the life-span, in the method for conventional process SCM 435 molten steel, carry out long-time LF, short period of time RH and handle.

Can fully prove by these experimental results: in accordance with the present production process, in electrometal furnace or converter, generate and the oxidation refining molten steel by method of fusion, then molten steel is transferred to the ladle refining that carries out the short period of time in the ladle furnace, outgas for a long time by circulating vacuum degasser circulation molten steel then, no matter still can significantly reduce the oxygen level of product and the predictor that maximum is mingled with the body diameter to SCM 435 steel capital to SUJ 2 steel, its cleanliness factor can be significantly improved, L can be significantly improved according to tappet roller measuring in work-ing life ₁₀Life-span.In the production method of steel, add these treatment steps, promptly, add the short period of time LF of according to the present invention claim 22 definition, long-time RH treatment step, or add the high temperature tapping+short period of time LF of claim 23 definition according to the present invention, RH treatment step oxygen level, the maximum that can significantly improve all steel is mingled with the predictor of body diameter and according to the L of tappet roller measuring in work-ing life for a long time ₁₀Life-span.

Can clearly be seen that from above-mentioned explanation: can the very high product made from steel of mass production cleanliness factor according to the present invention, and needn't the very high remelting processing of use cost.So just can provide cleanness steel, it is suitable for the machine steel of making to require to have fatigue strength, fatigue lifetime and calm degree, particularly suitable is done as rolling bearing with steel, constant speed tieing with steel, gear steel, annular continuous change transmission with steel, the steel for mechanical structure that is used for cold forging, tool steel and spring steel, the production method of cleanness steel can also be provided, that is, the present invention has unexpected unprecedented advantage.

Embodiment E

In electric arc furnace, generate and oxidation refining JIS SCM 435 molten steel by method of fusion, molten steel is transferred in the ladle furnace that induction stirrer is installed then, carry out 50-80 minute ladle refining (the short period of time gas stirring+induction stirring under inert atmosphere) altogether, then with liquid steel degassing 20-30 minute.Specifically, the condition that outgases in circulating vacuum degasser is 12 times that circulation molten steel amount is not less than the molten steel total amount, produces 10 stove SCM, 435 product made from steel by the steel ingot production technique of using teeming practice then.In order to contrast, in electric arc furnace, generate and oxidation refining JIS SCM 435 molten steel with method of fusion according to above-mentioned identical mode by traditional operation, then molten steel is transferred in the ladle furnace, with gas stirring molten steel 35-50 minute to carry out ladle refining, the circulating degassing that molten steel is no more than 25 minutes is then produced 10 stove SCM435 product made from steel by the steel ingot production technique of using teeming practice then.These product made from steel that obtain are like this detected, and the maximum that measure oxygen level in the product, obtains according to the statistical calculations of extreme value is mingled with the predictor of body diameter and according to the L of tappet roller measuring in work-ing life ₁₀Work-ing life.When the mensuration maximum is mingled with the predictor of body diameter, forge materials from φ 65 and get next experiment slice, 30 experiment slices are carried out 100mm ²Observation, according to the Principle of Statistics of these extreme values prediction 30000mm ²In maximum be mingled with the body diameter.In tappet roller experiment in work-ing life, the experiment slice that at first will be of a size of φ 60 * φ 20 * 8.3T carries out carburizing, quench hardening and tempering, experimentizes under the maximum hertz stress Pmax of 4900MPa then, determines L by calculating then ₁₀Work-ing life.

Table E1 illustrates the example and the experimental result thereof of carrying out the present invention operation, and table E2 illustrates the Comparative Examples and the experimental result thereof of carrying out traditional operation.

Table E1

Operation	Outer (ladle) refining of the stove that is undertaken by short period of time gas stirring+induction stirring
Operation											Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	The external refining stove: the time, minute	55	76	70	78	59	65	68	53	69	77
The external refining stove: warm eventually, ℃	1577	1581	1577	1585	1584	1582	1582	1576	1582	1584	The external refining stove: the time, minute	55	76	70	78	59	65	68	53	69	77
The external refining stove: warm eventually, ℃	1577	1581	1577	1585	1584	1582	1582	1576	1582	1584	RH: the time, minute	28	21	24	22	21	28	26	25	25	28
RH: internal circulating load, multiple	9.3	7.0	8.0	7.3	7.0	9.3	8.7	8.3	8.3	9.3	RH: the time, minute	28	21	24	22	21	28	26	25	25	28
RH: internal circulating load, multiple	9.3	7.0	8.0	7.3	7.0	9.3	8.7	8.3	8.3	9.3	RH: warm eventually, ℃	1534	1540	1534	1540	1541	1532	1539	1531	1538	1532
Pouring temperature, ℃	1512	1513	1516	1513	1513	1515	1512	1516	1514	1518	RH: warm eventually, ℃	1534	1540	1534	1540	1541	1532	1539	1531	1538	1532
Pouring temperature, ℃	1512	1513	1516	1513	1513	1515	1512	1516	1514	1518	Oxygen level in the product, ppm	6.3	5.5	5.5	5.4	6.0	6.0	6.6	6.5	5.7	5.6
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	13	6	11	9	5	8	11	14	10	14	Oxygen level in the product, ppm	6.3	5.5	5.5	5.4	6.0	6.0	6.6	6.5	5.7	5.6
	13	6	11	9	5	8	11	14	10	14	The maximum predicted diameter that is mingled with body, μ m	30.2	25.3	26.4	24.3	28.8	27.0	26.9	30.6	26.2	25.8
L ₁₀(×10 ⁷)	9.2	10.0	8.4	8.9	11.3	10.7	10.8	9.4	9.8	9.3		30.2	25.3	26.4	24.3	28.8	27.0	26.9	30.6	26.2	25.8
L ₁₀(×10 ⁷)	9.2	10.0	8.4	8.9	11.3	10.7	10.8	9.4	9.8	9.3	Evaluation result	◎	◎	◎	◎	◎	◎	◎	◎	◎	◎

◎: outstanding

Table E2

Operation	Outer (ladle) refining of the stove that is undertaken by the short period of time gas stirring
Operation											Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	Numbering	1	2	3	4	5	6	7	8	9	10
Grade of steel	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	SCM 435	The external refining stove: the time, minute	35	45	48	38	42	47	42	39	48	44
The external refining stove: warm eventually, ℃	1570	1574	1566	1572	1567	1569	1567	1569	1569	1570	The external refining stove: the time, minute	35	45	48	38	42	47	42	39	48	44
The external refining stove: warm eventually, ℃	1570	1574	1566	1572	1567	1569	1567	1569	1569	1570	RH: the time, minute	24	23	21	23	23	23	23	23	21	23
RH: internal circulating load, multiple	6.7	7.5	6.2	7.3	7.0	6.8	6.0	8.0	7.4	8.3	RH: the time, minute	24	23	21	23	23	23	23	23	21	23
RH: internal circulating load, multiple	6.7	7.5	6.2	7.3	7.0	6.8	6.0	8.0	7.4	8.3	RH: warm eventually, ℃	1531	1538	1541	1531	1541	1533	1533	1534	1535	1540
Pouring temperature, ℃	1521	1519	1517	1512	1520	1517	1511	1512	1516	1518	RH: warm eventually, ℃	1531	1538	1541	1531	1541	1533	1533	1534	1535	1540
Pouring temperature, ℃	1521	1519	1517	1512	1520	1517	1511	1512	1516	1518	Oxygen level in the product, ppm	9.1	9.2	6.9	9.4	9.2	7.6	8.3	8.3	6.9	8.8
What be not less than 20 μ m in the 100g product made from steel is mingled with the body number	42	54	42	53	59	49	57	53	56	52	Oxygen level in the product, ppm	9.1	9.2	6.9	9.4	9.2	7.6	8.3	8.3	6.9	8.8
	42	54	42	53	59	49	57	53	56	52	The maximum predicted diameter that is mingled with body, μ m	91.0	82.8	55.2	84.6	73.6	68.4	83.0	83.0	55.2	70.4
L ₁₀(×10 ⁷)	2.0	1.7	2.6	2.1	1.0	1.1	1.8	1.4	2.2	1.7		91.0	82.8	55.2	84.6	73.6	68.4	83.0	83.0	55.2	70.4
L ₁₀(×10 ⁷)	2.0	1.7	2.6	2.1	1.0	1.1	1.8	1.4	2.2	1.7	Evaluation result	×	×	×	×	×	×	×	×	×	×

*: poor

E1 can clearly be seen that from table: for the 10 stove SCM435 product made from steel of producing in accordance with the present production process, promptly, in electric arc furnace, generate and oxidation refining JIS SCM 435 molten steel by method of fusion, molten steel is transferred in the ladle furnace that induction stirrer is installed then, carry out 50-80 minute ladle refining (the short period of time gas stirring+induction stirring under inert atmosphere) altogether, then with liquid steel degassing 20-30 minute.Specifically, the condition that outgases in circulating vacuum degasser is 12 times that circulation molten steel amount is not less than the molten steel total amount, then 10 kinds of product made from steel that are numbered 1-10 producing by the steel ingot production technique of using teeming practice.Its oxygen level is 5.4-6.6ppm, and to be not less than the body number that is mingled with of 20 μ m be 5-14 to granularity in the 100g product made from steel, and it is 30.6 μ m that maximum predicted is mingled with the body diameter.That is, these products are very clean steel.For example, the L of these products ₁₀There is very large raising in life-span.Aspect total appraisal, these products all are be evaluated as outstanding (◎).

On the contrary, from table E2 as can be seen: for 10 stove SCM, 435 product made from steel of producing with conventional production methods according to contrast, promptly, in electric arc furnace, generate and oxidation refining JIS SCM 435 molten steel by method of fusion, then molten steel is transferred in the ladle furnace, to carry out ladle refining, the circulating degassing that molten steel is no more than 25 minutes was then produced 10 stove SCM, 435 product made from steel by the steel ingot production technique of using teeming practice then with gas stirring molten steel 35-50 minute.Although the oxygen level of these products is lower, still a little more than product made from steel of the present invention.In addition, to be not less than the body number that is mingled with of 20 μ m be 42-59 to granularity in the 100g product made from steel, and it is also big than of the present invention that maximum predicted is mingled with the body diameter, is 55.2-91.0 μ m.In addition, the L of these products ₁₀Life-span is also low than of the present invention, is the 1/10-1/5 of product made from steel of the present invention.All these compared steel products all are be evaluated as poor (*).

The foregoing description explanation: production method of the present invention can reduce oxygen level and the maximum predictor that is mingled with the body diameter, can improve L ₁₀Life-span.This means that in accordance with the present production process the steel that the oxygen level of producing and the maximum predictor that is mingled with the body diameter have all reduced has outstanding fatigue strength performance such as outstanding rolling fatigue life.

Can clearly be seen that from above-mentioned explanation: can the very high product made from steel of mass production cleanliness factor according to the present invention, and needn't the very high remelting processing of use cost.So just can provide cleanness steel, it is suitable for the machine steel of making to require to have fatigue strength, fatigue lifetime and calm degree, particularly suitable is done as rolling bearing with steel, constant speed tieing with steel, gear steel, annular continuous change transmission with steel, the steel for mechanical structure that is used for cold forging, tool steel and spring steel, the present invention can also provide the production method of cleanness steel, that is, the present invention has unexpected unprecedented advantage.

Claims

1, a kind of production method of cleanness steel, it comprises the steps: the molten steel that generates in electrometal furnace or the converter is transferred in the ladle furnace with refined molten steel, wherein, to transfer to the mode in the ladle furnace be that the tapping temperature of molten steel is higher 100 ℃ than the fusing point of steel at least to molten steel; With liquid steel degassing; Then molten steel casting is become steel ingot, described method also comprises the step of tapping deoxidization, wherein when molten steel is shifted in ladle furnace, in molten steel, add the reductor that comprises manganese, aluminium and silicon, the adding mode is in advance reductor to be placed ladle, and/or in the process of ladle of tapping, reductor is joined in the molten steel, thereby make molten steel in ladle furnace, carry out carrying out pre-deoxidation before the refining.

2, according to the process of claim 1 wherein that the refining time in ladle furnace is no more than 60 minutes, the time that outgases is no less than 25 minutes.

3, a kind of cleanness steel, it is to produce with each method among the claim 1-2, wherein, is not more than 40 by product made from steel being dissolved in the quantity that the granularity that detects in the acid is not less than the oxide inclusion body of 20 μ m in every 100g product made from steel.

4, according to the cleanness steel of claim 3, wherein, the oxygen level of steel is not more than 10ppm.

5, according to the cleanness steel of claim 3, wherein, the 30000mm that obtains according to the statistical calculations of extreme value ²The predictor that middle maximum is mingled with the body diameter is not more than 60 μ m.