WO2022017545A1 - V-n microalloyed steel and method for producing v-n microalloyed and surface-crack-free continuous casting blank - Google Patents

Abstract

Disclosed are a V-N microalloyed steel and a method for producing a V-N microalloyed and surface-crack-free continuous casting blank. The V-N microalloyed steel is composed of the following chemical components by mass percentage: 0.09%-0.13% of C, 0.1%-0.4% of Si, 1.0%-3.0% of Mn, less than or equal to 0.05% of P, less than or equal to 0.05% of S, 0.1%-0.4% of V, 0.011%-0.2% of N and the balance of Fe and unavoidable impurity elements. A continuous casting blank is subjected to component control according to the chemical components of the V-N microalloyed steel; and the production method therefor comprises converter smelting, LF refining and continuous casting steps in sequence. According to the present invention, by means of reasonable component design and smelting and continuous casting processes, the thermoplasticity of the continuous casting blank is improved, so that a high-temperature brittle region is prevented in a casting blank straightening region of the continuous casting blank or the thermoplasticity is good enough such that no surface crack appears, the casting blank is good in terms of surface quality and does not need to be cleaned, and the production efficiency is improved.

Description

Production method of V-N microalloyed steel and V-N microalloyed continuous casting billet without surface cracks technical field

The invention belongs to the field of continuous casting technology, in particular to a method for producing a V-N microalloyed continuous casting billet without surface cracks.

Background technique

Microalloyed steel is a steel for engineering structures that has developed rapidly in the past half century. By adding various alloying elements (Nb, V, Ti, etc.) It is widely used in various fields such as bridges, buildings, ships, automobiles, high-pressure vessels, etc. It has good application prospects and is the main product in the modern steel industry. China has abundant reserves of microalloying elements and has significant advantages in the development of microalloyed steels. Typical Q550 and Q460 grades of low alloy high strength steel have good market applications.

In the process of industrial production, micro-alloying is widely used due to the strengthening effect of micro-alloying elements, but in the process of continuous casting, due to the precipitation of carbonitrides of micro-alloying elements, the plasticity of steel is reduced, and the surface cracks of continuous casting billets are reduced. The occurrence rate is significantly higher than that of ordinary carbon steel billets, and problems such as transverse cracks, longitudinal cracks, and shape cracks occur, which affect the quality of continuous casting billets and are not conducive to large-scale production. This is a typical problem of microalloyed billets. Niobium, vanadium, and titanium are the three elements that are relatively widely used in microalloyed steels. Among them, niobium has the greatest effect on the plasticity of steel and the most obvious effect on the reduction of thermoplasticity of steel. Studies have shown that the addition of Ti element can reduce the brittleness of niobium and vanadium microalloyed steels, but it is difficult to control the cost.

Therefore, considering the cost and the problem of micro-alloyed steel billet cracks comprehensively, a low-cost billet production process without billet cracks is developed, which not only ensures the performance of micro-alloyed steel, ensures the normal progress of the continuous casting process, but also improves the The surface quality of the billet is a typical technological difficulty.

SUMMARY OF THE INVENTION

Aiming at the problem that the microalloyed steel in the prior art is prone to cracks on the surface of the billet during continuous casting, the present invention provides a VN microalloyed steel without surface cracks in the continuous casting billet. The exit section is (150～350)mm*(1250～2400)mm without surface cracks, which improves the surface quality of the continuous casting.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A VN microalloyed steel, which is composed of the following chemical components in percentage by mass: C: 0.09-0.13%, Si: 0.1-0.4%, Mn: 1.0-3.0%, P: ≤ 0.05%, S: ≤ 0.05%, V: 0.1 to 0.4%, N: 0.011 to 0.2%, and the balance is Fe and inevitable impurity elements.

In the present invention, the chemical composition of the microalloyed steel is rationally designed by utilizing the low thermoplastic trough point of the vanadium-containing steel, so as to reduce the occurrence of surface cracks on the slab surface of the microalloyed steel during continuous casting.

In the present invention, the V element has a strong affinity with the N element, and the combination of the TMCP method in the later stage can increase the strength and toughness of the tissue through the two typical strengthening mechanisms of fine-grain strengthening and precipitation strengthening.

At the same time, some areas of my country are rich in vanadium reserves, such as Chengde, Panzhihua and other places, which have a good cost advantage, and the price of N is relatively low. Therefore, the use of V-N microalloying is beneficial to reduce the production cost of continuous casting slabs.

The invention also provides a method for producing a VN microalloyed continuous casting billet without surface cracks. The continuous casting billet is produced according to the chemical composition of the VN microalloyed steel; the method sequentially includes: converter smelting, LF refining and continuous casting. casting process.

In the above production method, as a preferred mode, the section specification of the continuous casting slab is (150-350) mm*(1250-2400) mm.

In the above production method, as a preferred way, in the converter smelting process, the molten iron ratio is controlled at 88.0% to 91.0% (for example, 88.0%, 89.0%, 90.0%, 91.0%), and the top-bottom double blowing mode is adopted throughout the whole process. , and blow nitrogen first and then argon during the blowing process to stir the molten steel to promote the chemical reaction in the furnace. Wherein, the argon blowing time is not less than 3min (for example, 3min, 5min, 10min, 15min).

In the above production method, as a preferred way, in the converter smelting process, the blowing process adopts the form of one shot to the end, and there is no supplementary blowing process, so as to avoid superoxidation of molten steel in the supplementary blowing process and increase the number of inclusions. .

In the above production method, as a preferred way, in the converter smelting process, the C content at the smelting end point is controlled at 0.09-0.13% (for example, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%), the tapping temperature is 1625-1645°C (for example, 1625°C, 1630°C, 1635°C, 1640°C, 1645°C). Can be poured smoothly.

In the above production method, as a preferred method, LF refining is performed after tapping, without vacuum degassing refining; the purpose of not performing vacuum degassing is to ensure the N content in the molten steel.

In the above production method, as a preferred mode, in the continuous casting process, the continuous casting process adopts a weak water cooling method to effectively reduce the occurrence of cracks in the slab.

In the above production method, as a preferred way, in the continuous casting process, the continuous casting process adopts protective pouring, the large ladle alarms and immediately closes the nozzle at the end of the pouring stage, and it is strictly forbidden to open it again after the nozzle is closed, and the tundish is carried out with an alkaline covering agent. Cover to ensure that the liquid level is well covered, and the mold is made of low-carbon steel mold slag.

In the above production method, as a preferred mode, in the continuous casting process, the specific water amount in the continuous casting process is 0.7-1.25L/kg (for example, 0.7L/kg, 0.8L/kg, 1.0L/kg, 1.2 L/kg, 1.25L/kg).

In the above production method, as a preferred mode, in the continuous casting process, the degree of superheat of the continuous casting furnace is strictly controlled, and the degree of superheat of molten steel is 10 to 25°C (for example, 10°C, 15°C, 20°C, 25°C).

In the above production method, as a preferred way, in the continuous casting process, the pulling speed is 1.0-1.3m/min (for example, 1.0m/min, 1.1m/min, 1.2m/min, 1.3 m/min).

In the present invention, the low superheat degree is controlled, which is beneficial to increase the drawing speed, shorten the pouring time, and reduce the energy consumption; the tundish adopts an alkaline covering agent to keep the ladle warm and remove the inclusions in the ladle.

In the above production method, as a preferred manner, in the continuous casting process, the mold slag is divided into a powder slag layer, a sintered layer and a liquid slag layer during the dissolving process.

In the above production method, as a preferred mode, in the converter smelting process, deoxidation alloying is performed during the tapping process, and slag washing is performed simultaneously.

In the above production method, as a preferred way, in the converter smelting process, in the tapping process, the specific operation method of the deoxidation alloying is: in the tapping process, a silicon-containing material is selected for deoxidation, and the addition amount is: 3.5～4.0kg/ton steel (for example, 3.5kg/ton steel, 3.6kg/ton steel, 3.8kg/ton steel, 4.0kg/ton steel); use silicon manganese and vanadium-nitrogen alloy for alloying, among which vanadium-nitrogen alloy (V content is not less than 75%) the addition amount is 1～2kg/ton steel (for example, 1kg/ton steel, 1.2kg/ton steel, 1.4kg/ton steel, 1.6kg/ton steel, 1.8kg/ton steel, 2kg/ton steel). The present invention does not use aluminum for deoxidation.

In the above production method, as a preferred mode, in the converter smelting process, in the tapping process, the slag washing is carried out with a CaO-containing material (the CaO content is not less than 90%), and the addition amount is 3.5～ 4.0kg/ton of steel (for example, 3.5kg/ton of steel, 3.6kg/ton of steel, 3.8kg/ton of steel, 4.0kg/ton of steel), the CaO-containing substance needs to be added before the molten steel reaches 3/4 .

In the above production method, as a preferred mode, in the LF refining, in the early stage of LF refining, the argon blowing amount for argon blowing and stirring is 400 to 1000L/min (for example, 500L/min, 600L/min, 700L/min, 800L/min, 900L/min), the stirring time of blowing argon is 3~4min (for example, 3min, 3.2min, 3.5min, 3.8min, 4min), while stirring, be careful not to expose molten steel, and then use silicon-containing material to deoxidize, The composition was fine-tuned under stirring with argon.

In the above production method, as a preferred mode, in the LF refining, weak argon gas is used for stirring in the middle and final stages of LF refining, and the flow rate of argon blowing is the same.

In the above-mentioned production method, as a kind of preferred mode, in the described LF refining, in the last stage of the described LF refining, the amount of argon blowing for argon blowing and stirring is 100-200L/min (for example, 120L/min, 140L/min, 160L/min). /min, 180L/min), the time of argon blowing and stirring is ≥5min; the total refining time is controlled at 40-50min (for example, 40min, 42min, 45min, 48min, 50min), and the N content obtained is 100-2000ppm (for example, 100ppm) , 500ppm, 1000ppm, 1500ppm, 2000ppm), and the content of other components meets the molten steel component content required in the smelting process.

In the present invention, in the continuous casting process, during the continuous casting process, different water distributions are selected according to the specifications of the slab and the composition of the steel grade.

In the above production method, as a preferred way, in the continuous casting process, the specific distribution of water in the continuous casting process is as follows: , 8.5%, 9.0%, 9.5%, 10.0%), the water volume of the narrow surface foot roll accounts for 3.4 to 4.5% of the total water volume (for example, 3.4%, 3.8%, 4.0%, 4.2%, 4.5%), the vertical bending section The inner and outer arc water in the second zone accounts for 11.0-15.9% of the total water (for example, 11.0%, 12.0%, 13.0%, 14.0%, 15.0%, 15.5%, 15.9%), and the inner and outer arc water in the third zone accounts for 13.0-15.9% of the total water. % (for example, 13.0%, 14.0%, 15.0%, 15.5%, 15.9%), the internal and external arc water in the four zones accounts for 12.0 to 13.0% of the total water (for example, 12.0%, 12.2%, 12.5%, 12.6%, 12.8% , 13.0%), the inner and outer arc water in the five zones of arc 1 section accounts for 8.5 to 9.5% of the total water (for example, 8.0%, 8.5%, 9.0%, 9.5%), and the inner and outer arc water in the six zones corresponding to arc 2 and 3 sections The arc water volume accounts for 12.0-14.0% of the total water volume (for example, 12.0%, 12.5%, 13.0%, 13.5%, 13.8%, 13.0%), and the inner and outer arc water volume of the seven zones in the 4th to 5th stage accounts for 8.0-11.5% of the total water volume (For example, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, 11.0%, 11.5%, 10.0%), the internal and external arc water in the eight zones of straightening 6, 7 and 8 accounts for 8.0~8 of the total water. 11.5% (eg, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, 11.0%, 11.5%, 10.0%), and the rest of the water is distributed to the horizontal section.

In the present invention, the above technical features can be freely combined to form new technical solutions without conflicting with each other.

The steps and processes not described in detail in the production method provided by the present invention are conventional processes in the art.

Compared with the prior art, the beneficial effects of the present invention are:

The method for producing a VN microalloyed continuous casting billet without surface cracks provided by the present invention improves the thermoplasticity of the continuous casting billet through reasonable component design of the VN microalloying and combined with a suitable smelting and continuous casting process, so that the billet can be straightened in the casting billet. The interval avoids the high temperature brittle zone or the thermoplasticity is good enough so that no surface cracks occur, the surface quality of the billet is good, and the billet cleaning is not required, which improves the production efficiency.

detailed description

The technical solutions of the present invention will be described in detail below with reference to the embodiments. The various examples are provided by way of explanation of the invention and do not limit the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For example, features illustrated or described as part of one embodiment can be used on another embodiment to yield yet another embodiment. Therefore, it is intended that the present invention embrace such modifications and variations as come within the scope of the appended claims and their equivalents.

According to an embodiment of the present invention, there is provided a VN microalloyed steel with no surface crack continuous casting billet. The VN microalloyed steel is composed of the following chemical components by mass percentage: C: 0.09-0.13%, Si: 0.1-0.4 %, Mn: 1.0-3.0%, P: ≤ 0.05%, S: ≤ 0.05%, V: 0.1-0.4%, N: 0.011-0.2%, the balance is Fe and a small amount of unavoidable impurity elements.

The invention also provides a production method for preparing the micro-alloyed steel with the above chemical composition without surface crack continuous casting billet, which sequentially includes the following steps: converter smelting, LF refining and continuous casting.

The alkaline covering agent and the low carbon steel mold flux used in the production process of the continuous casting slab of the present invention are commercially available products commonly used in the production of microalloyed steel.

Due to the precipitation of carbonitrides in the continuous casting process, the plasticity of the steel is reduced, the occurrence rate of surface cracks of the continuous casting billet is significantly higher than that of the ordinary carbon steel billet, and problems such as transverse cracks, longitudinal cracks, and shape cracks appear. In the process, the control of C content, the reduction of S, the use of deoxidizers, the change of the shape of inclusions, and the improvement of the purity of the steel are adopted. With LF refining and reasonable continuous casting process, micro-alloyed steel with fine grains and good plasticity is obtained. , so as to reduce the generation of surface cracks in the microalloyed steel continuous casting billet and improve the surface quality of the continuous casting billet.

Example 1

The present embodiment provides a V-N microalloyed continuous casting billet and a production method thereof. The chemical composition of the continuous casting billet by mass percentage is shown in Table 1.

Table 1 Chemical composition of V-N microalloyed steel continuous casting billet in Example 1

The production method includes the following steps in sequence: converter smelting, LF refining and continuous casting.

(1) Converter smelting:

The converter smelting process uses a 120t converter for smelting. The smelting raw materials are molten iron and scrap steel, and the ratio of molten iron is controlled at 90%. Nitrogen is used for blowing in the early stage, and argon is used in the later stage. The argon blowing time is 4min, and the blowing process uses one shot. In the final form of blowing, the supplementary blowing process is resolutely eliminated, thereby preventing the overoxidation of molten steel and improving the cleanliness of molten steel.

The C content at the end of smelting is controlled at 0.10wt%, and the tapping temperature is 1632°C; deoxidation alloying and slag washing are carried out during the tapping process, and the deoxidizer is selected from silicon-containing substances, and the addition amount is about 3.6kg/ton steel; the alloying raw material is vanadium Nitrogen alloy (V content is 77wt%), the addition is about 1.6kg/ton steel; CaO-containing material (CaO content is 90wt%) is selected for slag washing, and the addition amount is 3.8kg/ton steel.

(2) LF refining:

After tapping, the ladle is directly transferred to the LF refining station for argon blowing refining. The amount of argon blowing in the early stage of refining is 400 L/min for argon blowing and stirring for 3 minutes. After that, silicon-containing substances are added for deoxidation, and a small amount of silicon manganese is added to adjust the Mn content; at the end of refining, argon blowing is performed. The amount was adjusted to 150L/min and stirred for 6min; the total refining time was controlled at 45min, the N content obtained was 120ppm, and the content of other components met the molten steel component content required in the component control process.

(3) Continuous casting:

In the protection and casting process, the large package is protected by a long nozzle, and a conical asbestos pad is added to ensure the tightness of the connection.

After the casting starts, first use the gas flame to test the tightness of the ladle shroud and the bowl of the long shroud. If the flame is inhaled, it means that the tightness of the place is not good, and the long shroud should be re-covered. If the airtightness meets the requirements, during the pouring process, argon gas is introduced into the connection of the bowl of the long nozzle to form an argon-sealed state, which further prevents the connection between the bowl of the long nozzle and the ladle outlet from being loose and caused by air inhalation. Addition of oxygen and nitrogen to molten steel.

The big bag alarms at the end of pouring and closes the nozzle immediately. After the nozzle is closed, it is strictly forbidden to open it again. The tundish is covered with alkaline covering agent, and the mold is protected with mild steel mold slag (P0050 for Shinagawa 250).

This example is the third heat of pouring, that is, the third heat of steel poured after continuous casting starts, the superheat degree is 20°C, and the actual pulling speed is 1.1m/min.

In the process of continuous casting, the specific distribution of water with a specific water volume of 1.2L/kg is as follows: the water volume of the inner and outer arcs of the wide-faced foot rolls accounts for about 8.6% of the total water volume, the narrow-faced foot rolls accounted for 3.5% of the total water volume, and the vertical bending section The inner and outer arc water volume of the second zone accounts for 15.8% of the total water volume, the third zone inner and outer arc water volume accounts for 15.6% of the total water volume, the fourth zone inner and outer arc water volume accounts for 12.9% of the total water volume, and the fifth zone inner and outer arc water volume of the first arc section accounts for the total water volume. 9.3% of the total water volume in the six zones corresponding to the 2nd and 3rd sections of the arc, 12.4% of the total water volume, and 8.1% of the total water volume in the seven zones of the 4th to 5th sections. The inner and outer arc water in the eight zones of the section accounts for 8.9% of the total water, and the rest is allocated to the horizontal section.

Implementation effect: the present invention adopts the continuous casting billet obtained from the multi-furnace steel poured by the above method, the cross section is 200mm*2000mm, the surface quality is good, there is no crack in the low magnification inspection, and the surface of the billet is observed in the hot state without cracks, and no billet cleaning is required.

Example 2

In this example, a V-N microalloyed continuous casting billet without surface cracks is produced, and its chemical composition is shown in Table 2 by mass percentage.

Table 2 Chemical composition of V-N microalloyed steel continuous casting billet in Example 2

The production method includes the following steps in sequence: converter smelting, LF refining and continuous casting.

(1) Converter smelting:

The smelting process uses a 120t converter for smelting. The raw materials for smelting are molten iron and scrap steel. The ratio of molten iron to molten iron is controlled at 89%. Nitrogen is used for blowing in the early stage, and argon is used in the later stage. The argon blowing time is 3 minutes. Form blowing, resolutely put an end to the supplementary blowing process.

The C content at the smelting end is controlled at 0.09wt%, and the tapping temperature is 1630°C.

Deoxidation alloying and slag washing are carried out during the tapping process. The deoxidizer is selected from silicon-containing substances (ie silicon carbide), and the addition amount is about 3.8kg/ton steel; It is 1.3kg/ton steel; CaO-containing material (CaO content is 90wt%) is selected for slag washing, and the addition amount is 3.6kg/ton steel.

(2) LF refining:

After tapping, the ladle is directly transferred to the LF refining station for argon blowing refining. The amount of argon blowing in the early stage of refining is 400L/min for argon blowing and stirring for 4 minutes, and then silicon-containing substances are added for deoxidation; the amount of argon blowing in the final stage of refining is adjusted to 150L/min. ; The total refining time is controlled at 48min, the N content obtained is 100ppm, and the content of other components meets the content of molten steel required in the component control process.

(3) Continuous casting:

In the protection and casting process, the large package is protected by a long nozzle, and a conical asbestos pad is added to ensure the tightness of the connection. After the casting starts, first use the gas flame to test the tightness of the ladle shroud and the bowl of the long shroud. If the flame is inhaled, it means that the tightness of the place is not good, and the long shroud should be re-covered. If the airtightness meets the requirements, during the pouring process, argon gas is introduced into the connection of the bowl of the long nozzle to form an argon-sealed state, which further prevents the connection between the bowl of the long nozzle and the ladle outlet from being loose and caused by air inhalation. Addition of oxygen and nitrogen to molten steel. The big bag alarms at the end of pouring and closes the nozzle immediately. After the nozzle is closed, it is strictly forbidden to open it again. The tundish is covered with an alkaline covering agent, and the mold is protected with a mild steel mold slag (P0027-3 for Shinagawa 250).

This example is the fourth heat of steel poured by continuous casting after open casting, the superheat degree is 15°C, and the actual pulling speed is 1.2m/min.

In the process of continuous casting, the specific distribution of water with a specific water volume of 1.0L/kg is as follows: the water volume of the inner and outer arcs of the wide-faced foot rolls accounts for about 8.1% of the total water, and the narrow-faced foot rolls account for 4.3% of the total water. The inner and outer arc water volume in the second zone accounts for 11.4% of the total water volume, the third zone inner and outer arc water volume accounts for 13.1% of the total water volume, the fourth zone inner and outer arc water volume accounts for 12% of the total water volume, and the fifth zone inner and outer arc water volume in the arc 1 section accounts for the total water volume. The inner and outer arc water in the six zones corresponding to the arc 2 and 3 sections accounts for 13.6% of the total water volume, and the inner and outer arc water in the seven zones in the 4-5 sections accounts for 11.2% of the total water volume. Straightening sections 6, 7 and 8 The inner and outer arc water in the eight zones of the section accounts for 11.3% of the total water, and the rest is allocated to the horizontal section.

Implementation effect: The continuous casting billet obtained from the multi-furnace steel poured by the above method has a specification of 250mm*1800mm, the surface quality is good, there is no obvious crack in the low-power inspection, and the surface of the billet is observed in the hot state. There is no obvious crack, and no billet cleaning is required. .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A VN microalloyed steel, characterized in that the VN microalloyed steel is composed of the following chemical components by mass percentage: C: 0.09-0.13%, Si: 0.1-0.4%, Mn: 1.0-3.0%, P: ≤ 0.05%, S: ≤ 0.05%, V: 0.1-0.4%, N: 0.011-0.2%, the balance is Fe and inevitable impurity elements.
2. A method for producing a VN microalloyed continuous casting billet without surface cracks, characterized in that the chemical composition composition of the VN microalloyed steel according to claim 1 produces a continuous casting billet; the method sequentially comprises: converter smelting, LF refining and continuous casting process.
3. The production method according to claim 2, wherein the section specification of the continuous casting slab is (150-350) mm*(1250-2400) mm.
4. The production method according to claim 2 or 3, characterized in that, in the converter smelting process, the molten iron ratio is controlled at 88.0wt% to 91.0wt%, a top-bottom re-blowing mode is adopted in the whole process, and the blowing process is carried out first. Blow nitrogen after blowing argon; wherein, the time of blowing argon is not less than 3min;

   Preferably, the blowing process adopts the one-shot-to-bottom form blowing without supplementary blowing process;

   Preferably, the C content at the smelting end point is controlled at 0.09-0.13 wt%, and the tapping temperature is 1625-1645°C.
5. The production method according to claim 4, characterized in that LF refining is carried out after tapping without a vacuum degassing refining process.
6. The production method according to claim 5, characterized in that, in the continuous casting process, the continuous casting process adopts a weak water cooling method; the continuous casting process adopts protection pouring, and the large ladle alarms and immediately closes the nozzle at the end of the pouring stage, and it is strictly prohibited after the nozzle is closed. Open it again, the tundish is covered with an alkaline covering agent, and the mold is made of low-carbon steel mold slag;

   Preferably, the specific water volume in the continuous casting process is 0.7-1.25L/kg;

   Preferably, the superheat degree of molten steel is 10～25℃;

   Still preferably, during the continuous casting process, the drawing speed is 1.0-1.3 m/min.
7. The production method according to claim 4, characterized in that, in the converter smelting process, deoxidation alloying is performed during the tapping process, and slag washing is performed simultaneously;

   Preferably, the specific operation method of deoxidation and alloying is as follows: in the tapping process, a material containing silicon is used for deoxidation, and the addition amount is 3.5-4.0 kg/ton steel; The amount of alloy added is 1～2kg/ton of steel;

   Preferably, the slag washing is carried out with CaO-containing substances, and the addition amount is 3.5-4.0 kg/ton of steel, and the CaO-containing substances need to be added before the molten steel reaches 3/4.
8. The production method according to claim 5, wherein, in the LF refining process, in the early stage of LF refining, the amount of argon blowing for argon blowing and stirring is 400 to 1000 L/min, and the time for argon blowing and stirring is 3 to 4 min. The composition is fine-tuned by deoxidizing silicon-containing substances and stirring with argon blowing.
9. The production method according to claim 8, wherein, in the LF refining process, in the final stage of the LF refining, the amount of argon blowing for argon blowing and stirring is 100-200L/min, and the time for argon blowing and stirring is ≥5min ; The total refining time is controlled at 40-50min, and the N content obtained is 100-2000ppm.
10. The production method according to claim 6, characterized in that, in the continuous casting process, the specific distribution of water in the continuous casting process is as follows: The water volume of the face and foot roller accounts for 3.4-4.5% of the total water volume, the inner and outer arc water volume of the second zone of the vertical bending section accounts for 11.0-15.9% of the total water volume, the inner and outer arc water volume of the third zone accounts for 13.0-15.9% of the total water volume, and the inner and outer arc water volume of the fourth zone It accounts for 12.0-13.0% of the total water volume, the inner and outer arc water volume in the five zones of arc 1 section accounts for 8.5-9.5% of the total water volume, and the inner and outer arc water volume in the six zones corresponding to arc 2 and 3 sections accounts for 12.0-14.0% of the total water volume. The internal and external arc water in the seven zones of the 4th to 5th sections accounts for 8.0 to 11.5% of the total water volume, and the eight zones of straightening sections 6, 7 and 8 account for 8.0 to 11.5% of the total water volume, and the rest of the water is distributed to the horizontal section .