CN111254358B - Production method of steel for track link of ultrahigh-purity crawler belt - Google Patents

Production method of steel for track link of ultrahigh-purity crawler belt Download PDF

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CN111254358B
CN111254358B CN202010208413.4A CN202010208413A CN111254358B CN 111254358 B CN111254358 B CN 111254358B CN 202010208413 A CN202010208413 A CN 202010208413A CN 111254358 B CN111254358 B CN 111254358B
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steel
refining
molten steel
slag
equal
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CN111254358A (en
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印传磊
翟万里
郑力宁
张洪才
林鹏
杨勰
田春阳
许正周
蒋栋初
张益民
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Jiangsu Lihuai Steel Co ltd
Jiangsu Shagang Group Huaigang Special Steel Co Ltd
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Jiangsu Lihuai Steel Co ltd
Jiangsu Shagang Group Huaigang Special Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/114—Treating the molten metal by using agitating or vibrating means
    • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/35—Blowing from above and through the bath
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/36—Processes yielding slags of special composition
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron

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  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention discloses a production method of steel for an ultra-high purity crawler track link, which comprises the following production steps: the top-bottom blowing combined blowing converter uses the molten iron and high-quality scrap steel after KR desulfurization for blowing, and the molten steel end pointw([C])=0.10%~0.20%、w([S])≤0.012%、T>Deoxidizing, alloying and slagging the molten steel in the tapping process at 1620 ℃; the refining process is fast heated, the components are finely adjusted, the slag surface is deoxidized/desulfurized, the refining time is less than or equal to 60min, and the ladle bottom blowing stirring argon is controlledThe air flow is less than or equal to 300 NL/min; carrying out RH vacuum treatment on the molten steel, and keeping the molten steel for 25-31 min under the condition that the vacuum is less than or equal to 100 pa; standing the molten steel for soft blowing; and (4) protecting casting by using an arc continuous casting machine. According to the method, the steel for the track link of the ultra-high purity crawler belt can be obtained by controlling the blowing end point C, S of the converter, rapidly smelting the molten steel in the refining process, controlling the deoxidation of a refining slag system and a slag surface, stirring by weak bottom blowing, circulating RH molten steel and casting for protection.

Description

Production method of steel for track link of ultrahigh-purity crawler belt
Technical Field
The invention belongs to the technical field of alloy steel, relates to the field of production of steel for track links of engineering machinery, and particularly relates to a production method of steel for track links of an ultra-high-purity track.
Background
In recent years, with the development of economy, the steel equipment manufacturing industry for engineering machinery is upgraded and developed rapidly, and the demand for steel for track links of crawler tracks of engineering machinery is greatly increased. The field operation environment of the engineering machinery is severe, the continuity and the frequency are strong, in order to meet the requirement of product upgrading, higher and higher requirements are put forward on the quality of steel materials for track links of the engineering machinery, most of steel products for track links of the engineering machinery produced in China still stay on the level only meeting the national standard requirements at present, the yield is high, the quality control level is low, and particularly the purity control aspect of the steel cannot meet the requirement of product upgrading of downstream customers
Therefore, how to produce the steel for the track link joint of the engineering machinery crawler with ultrahigh purity with low cost, low energy consumption and high efficiency has profound significance for improving the mechanical service performance and promoting the rapid development of the steel for the track link joint of the high-quality engineering machinery crawler in China.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a production method of steel for an ultra-high purity crawler track link, the invention carries out bottom blowing combined blowing converter smelting by using a low-sulfur raw material, the molten steel is strongly deoxidized, and deep desulfurization is carried out to reach ultra-low sulfur content; controlling the ladle bottom blowing stirring flow, making a low-alkalinity slag system, reducing steel slag reaction, and improving/changing the morphological characteristics and components of oxide inclusions. The inclusion removal efficiency is obviously improved through RH long-time high-vacuum molten steel circulation and long-time effective soft blowing standing. And the continuous casting adopts protective casting to avoid secondary oxidation of molten steel. The purity of the molten steel can be controlled at the following level: the T.O content in the steel is 5-8 ppm; according to JIS G0555 point method, 60 visual fields are observed under 400 times optical microscope for testing, dA (sulfides) <0.10, dB (long strip oxide) =0, dC (particle oxide) ≦ 0.05, particle sizes are all <10 μm (wherein the proportion of the particle size is 2 μm-5 μm is more than 90%), and more than 90% of oxide inclusions are magnesium aluminate spinel. The invention improves the steel cleanliness and the service performance of the existing steel for engineering machinery.
The invention is realized by the following technical scheme:
a production method of steel for track links of ultra-high-purity crawler tracks comprises the following steps:
1) use ofw([S]) Less than or equal to 0.003 percent of desulfurized molten iron and low-sulfur carbon steel scrap are used as raw materials, the ratio of the steel scrap is less than or equal to 10 percent, a top-bottom combined blown converter is adopted for smelting, and the end point of the molten steel isw([C])=0.10%~0.20%、w([S])≤0.012%、T>Deoxidizing, alloying and slagging the molten steel in the tapping process at 1620 ℃, and stopping slag by adopting a sliding plate;
2) the temperature of molten steel reaching an LF station is higher than 1540 ℃, rapid temperature rise and alloying in the refining process are ensured, bottom blowing stirring is controlled, and a low-alkalinity slag system is manufactured by adopting slag surface composite deoxidation and deep desulfurization;
3) and (3) carrying out RH vacuum treatment on the molten steel, and keeping the molten steel for 25-31 min under the condition that the vacuum is less than or equal to 100 pa. Carrying out micro-calcium treatment after RH treatment, and carrying out soft blowing after calcium treatment, wherein the soft blowing time is 25-35 min;
4) and after the soft blowing is finished, the molten steel is hoisted to be continuously cast into a blank.
The steel for the track link of the ultrahigh-purity crawler belt comprises the following main chemical components in percentage by mass: 0.34-0.38% of C, 0.15-0.25% of Si, 0.90-1.10% of Mn, 0.15-0.30% of Cr, 0.030-0.045% of Al, 0.025-0.050% of Ti, 0.0020-0.0030% of B, less than or equal to 0.015% of P, less than or equal to 0.005% of S, less than or equal to 0.010% of Ni, less than or equal to 0.008% of Cu, less than or equal to 0.010% of V, and the balance of Fe.
The invention further improves the scheme as follows:
in the step 1), the deoxidation is as follows: before the steel tapping amount is 20 t-30 t and before the steel tapping amount is 20 t-30 t, adding 1.1-2.0 kg/t of aluminum cakes for deep deoxidation, and ensuring that refining is finished to a stationw([Al])= 0.015%～0.045%。
Further, in the step 1), the alloying is finished by deoxidation, and manganese metal (A), (B), (C) and (C) are usedw((Mn))>97 percent of low-titanium low-aluminum ferrosilicon: (w((Si))>75%、w((Ca))<0.5 percent) medium carbon ferrochrome (w((Cr))>55%) of molten steel is subjected to primary alloying.
Further, in the step 1), after the deoxidation and the alloying are finished and before the tapping of the molten steel is finished, the slag is formed by using lime and premelted refining slag according to the ratio of 2: 1.5.
Further, the premelted refining slag comprises the following components in percentage by mass: CaO =45% -55%, SiO2≤10%、MgO=4%～10%、Al2O3=25%～40%、S≤0.1%。
Further, in the step 1), a sliding plate is adopted for blocking slag, so that molten steel at the end point of the converter is ensuredw([P]) And refining the molten steel to a stationw([P]) Difference between the two<0.002%。
Further, in the step 2), the refining time is controlled to be less than or equal to 60min, fine adjustment of C, Si, Mn and Cr components is carried out in the early stage of refining, and ferrotitanium and ferroboron alloy are added under the condition of white slag of refining slag in the middle and later stages. The bottom-blowing stirring argon flow is 100-300 NL/min during temperature rising and alloying, and the bottom-blowing stirring argon flow is 30-100 NL/min in the middle and later refining stages.
Further, in the step 2), the aluminum particles and the high-purity silicon carbide are subjected to slag surface diffusion deoxidation and aluminum particle precipitation deoxidation, and a refining process is usedw([Al]) = 0.030% -0.055%, refining end pointw([S])<0.003%。
Furthermore, the high-purity silicon carbide,w(SiC)>95 percent, and the dosage is controlled to be 1.4 to 2.0 kg/t.
Further, in the step 2), the low-alkalinity slag system is prepared by adding 0-150 kg of lime and 0-100 kg of premelted refining slag at the early stage of refining, so that the final refining slagw(CaO)/ w(SiO2)=3～5，w(MgO)=6%～10%、w(Al2O3) = 25-35%, and ensures molten steel in refining processw([Ca])<0.0015%。
Further, in the step 3), calcium treatment is carried out on the molten steel by micro-calcium treatment, the dosage of a silicon-calcium line is 0-50 m/furnace, and the grade of the silicon-calcium line is as follows:w((Ca))>28%、 w((Si))>60%。
further, in the step 4), Ar sealing protection casting is carried out on the ladle long nozzle, and the Ar flow is 10-60L/min. And a crystallizer and a tail end are used for electromagnetic stirring, the Ar seal protects casting, and the nitrogen content of the continuous casting tundish molten steel minus the nitrogen content of the RH ladle molten steel is ensured to be less than 0.0003%. The crystallizer and the tail end electromagnetic stirring are used, the segregation of sulfur elements in steel is reduced, and the appearance and distribution of sulfides in steel are improved.
The invention has the beneficial effects that:
according to the production method of the steel for the track link section of the ultrahigh-purity crawler belt, the low-sulfur molten iron and the scrap steel are used for smelting in the converter, so that the initial S content of the molten steel is reduced, the consumption of slag materials such as lime and the like supplemented due to desulfurization in the refining process is reduced, the temperature drop of the molten steel caused by the addition of a large amount of slag materials is reduced, the rapid temperature rise in the refining process is realized, the smelting time is shortened, and the electricity and electrode consumption are reduced. Meanwhile, the refining process does not need large stirring for desulfurization, and the mass transfer reaction of the steel slag is favorably weakened.
Secondly, according to the production method of the steel for the track link of the ultrahigh-purity crawler, the converter adopts a low scrap ratio, the temperature of the molten steel is increased, the temperature of the molten steel at the initial stage of LF refining is ensured to be high, the rapid smelting in the refining process is realized, the refining time is shortened, the control of the type of impurities is facilitated, and the process cost is reduced. The molten steel adopts aluminum to perform strong deoxidation, silicon carbide on the slag surface is subjected to diffusion deoxidation, a low-alkalinity slag system is manufactured, bottom blowing stirring is controlled, mass transfer of calcium among steel slag is inhibited, the calcium content in the molten steel is ensured to be less than 0.0015%, oxide inclusions in the molten steel are converted to dispersed fine magnesium aluminum spinel, and large-particle calcium aluminate inclusions are avoided.
Thirdly, the method for producing the steel for the track link of the track with the ultrahigh purity ensures that impurities are removed in the refining process by deoxidation and the accurate control of the components of molten steel, and avoids the fine adjustment of the components after RH breaking, which brings about the non-uniformity of the components of the molten steel and secondary pollution. And the molten steel is circulated in the vacuum chamber for a long time through RH and is subjected to soft blowing and standing, so that the inclusion in the steel is further reduced.
Fourthly, according to the method for producing the steel for the track link of the ultra-high purity crawler belt, the continuous casting process adopts the long nozzle argon sealing protection casting to avoid the secondary oxidation of molten steel, and adopts the electromagnetic stirring to improve the sulfur segregation, so that sulfides in the steel are in a short and dispersed state.
Fifth, according to the method for producing the steel for the track link of the ultra-high purity crawler of the invention, the purity of molten steel can be controlled at the following level: the T.O content in the steel is 5-8 ppm; according to JIS G0555 point method, 60 visual fields are observed under 400 times optical microscope for testing, dA (sulfides) <0.10, dB (long strip oxide) =0, dC (particle oxide) ≦ 0.05, particle sizes are all <10 μm (wherein the proportion of the particle size is 2 μm-5 μm is more than 90%), and more than 90% of oxide inclusions are magnesium aluminate spinel.
Detailed Description
Example 1
The steel for the track link of the ultrahigh-purity crawler belt comprises the following main chemical components in percentage by mass: 0.34 percent of C, 0.15 percent of Si, 0.90 percent of Mn, 0.15 percent of Cr, 0.030 percent of Al, 0.025 percent of Ti, 0.0020 percent of B, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.010 percent of Ni, less than or equal to 0.008 percent of Cu, less than or equal to 0.010 percent of V, and the balance of Fe.
The production steps are as follows:
1) use ofw([S]) Using desulfurized molten iron and low-sulfur carbon steel scrap of which the ratio of steel scrap is 8% as raw materials, smelting by adopting a top-bottom combined blown converter and finishing the molten steelw([C])=0.10%、w([S]) =0.011%, T =1650 ℃, the tapping amount is 25T, 1.8kg/T aluminum cake is added for deep deoxidation, and refining is carried out to the stationw([Al]) = 0.030%; adding metal manganese, low-titanium low-aluminum ferrosilicon and medium-carbon ferrochromium for alloying, and adding 5.9kg/t lime and 4.3kg/t refining slag when tapping is finished.
2) And after tapping, a sliding plate is used for blocking slag, and the phosphorus return amount of the molten steel is 0.001%.
3) The temperature of molten steel reaching an LF station is 1559 ℃, the total time of LF refining of the molten steel is 60min, fine adjustment of C, Si, Mn and Cr components is carried out at the early stage of refining, and ferrotitanium and ferroboron alloy are added under the condition of white slag of refining slag at the middle and later stages. The flow of bottom-blowing stirring argon gas in the early stage of refining is 200-350 NL/min, the flow of bottom-blowing stirring argon gas in the middle stage of refining is 80-100 NL/min, and the flow of bottom-blowing stirring argon gas in the later stage of refining is 30-50 NL/min. During the refining process, aluminum particles and high-purity silicon carbide are used for diffusion deoxidation of slag surface and precipitation deoxidation of the aluminum particles, the dosage of the high-purity silicon carbide is controlled to be 1.6kg/t, and during the refining processw([Al]) = 0.030% -0.050% molten steel in refining processw([Ca]) = 0.0013-0.0009%, refining end pointw([S])=0.0014%。
4) The refining final slag comprises the following components:w(CaO)=47.9%、 w(SiO2)=12.6%，w(MgO)=8.0%、w(Al2O3)=30.5%。
5) the molten steel is subjected to RH vacuum treatment, and the molten steel is kept for 28min under the condition that the vacuum is less than or equal to 100 pa. Feeding 25m of calcium silicate wire after finishing the RH treatment, and then carrying out soft blowing for 30 min;
6) and after the soft blowing is finished, hoisting the molten steel to continuous casting for continuous casting to form a blank, carrying out Ar sealing protection casting on a ladle long nozzle, wherein the Ar flow is 40L/min, and electromagnetically stirring by using a crystallizer and the tail end. The nitrogen content of the molten steel of the continuous casting tundish minus the nitrogen content of the molten steel of the RH ladle is 0.00025 percent.
In the steels obtained by steps 1) to 6), t.o was 5.7ppm, inclusion rating: dA (sulfides) =0.05, dB (long-strip oxides) =0, dC (particle oxides) =0.07, the grain size is 90% of 2-5 μm, 92% of oxide inclusions are magnesium-aluminum spinel, and the balance are aluminum oxide inclusions and calcium-aluminum-magnesium composite inclusions.
Example 2
The steel for the track link of the ultrahigh-purity crawler belt comprises the following main chemical components in percentage by mass: 0.36 percent of C, 0.20 percent of Si, 1.00 percent of Mn, 0.22 percent of Cr, 0.038 percent of Al, 0.040 percent of Ti, 0.0025 percent of B, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.010 percent of Ni, less than or equal to 0.008 percent of Cu, less than or equal to 0.010 percent of V, and the balance of Fe.
The production steps are as follows:
1) use ofw([S]) Using desulfurized molten iron and low-sulfur carbon steel scrap of which the ratio of steel scrap is 10% as raw materials, smelting by adopting a top-bottom combined blown converter and finishing the molten steelw([C])=0.15%、w([S]) =0.012%, T =1631 ℃, the tapping amount is 25T, 1.5kg/T aluminum cake is added for deep deoxidation, and refining is carried out to the stationw([Al]) = 0.038%; adding metal manganese, low-titanium low-aluminum ferrosilicon and medium-carbon ferrochromium for alloying, and adding 5.9kg/t lime and 4.3kg/t refining slag when tapping is finished.
2) And after tapping, a sliding plate is used for pushing off slag, and the phosphorus return amount of the molten steel is 0.0015%.
3) The temperature of molten steel reaching an LF station is 1542 ℃, the total time of LF refining of the molten steel is 57min, fine adjustment of C, Si, Mn and Cr components is carried out at the early stage of refining, and ferrotitanium and ferroboron alloy are added under the condition of white slag of refining slag at the middle and later stages. 50kg of lime and 25kg of premelted refining slag are added in the early stage of refining. The flow of bottom-blowing stirring argon in the early stage of refining is 150-200 NL/min, the flow of bottom-blowing stirring argon in the middle stage of refining is 80-90 NL/min, and the flow of bottom-blowing stirring argon in the later stage of refining is 30-40 NL/min. During the refining process, aluminum particles and high-purity silicon carbide are used for diffusion deoxidation of slag surface and precipitation deoxidation of the aluminum particles, the dosage of the high-purity silicon carbide is controlled to be 1.7kg/t, and during the refining processw([Al]) = 0.040% -0.055%, molten steel in refining processw([Ca]) = 0.0015-0.0011%, refining end pointw([S])=0.0018%。
4) The refining final slag comprises the following components:w(CaO)=49.5%、 w(SiO2)=11.1%，w(MgO)=7.4%、w(Al2O3)=31.0%。
5) the molten steel is subjected to RH vacuum treatment, and the molten steel is kept for 28min under the condition that the vacuum is less than or equal to 100 pa. Directly performing soft blowing after RH treatment, wherein the soft blowing time is 26 min;
6) and after the soft blowing is finished, hoisting the molten steel to continuous casting for continuous casting to form a blank, carrying out Ar sealing protection casting on a ladle long nozzle, wherein the Ar flow is 40L/min, and electromagnetically stirring by using a crystallizer and the tail end. The nitrogen content of the molten steel of the continuous casting tundish minus the nitrogen content of the molten steel of the RH ladle is 0.00023%.
In the steels obtained by steps 1) to 6), t.o was 5.9ppm, inclusion rating: dA (sulfides) =0.07, dB (long-strip oxides) =0, dC (particle oxides) =0.05, the grain diameter is 92% of the proportion of 2-5 μm, 94% of oxide inclusions are magnesium-aluminum spinel, and the balance are aluminum oxide inclusions and calcium-aluminum-magnesium composite inclusions.
Example 3
The steel for the track link of the ultrahigh-purity crawler belt comprises the following main chemical components in percentage by mass: 0.38 percent of C, 0.25 percent of Si, 1.10 percent of Mn, 0.30 percent of Cr, 0.045 percent of Al, 0.050 percent of Ti, 0.0030 percent of B, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.010 percent of Ni, less than or equal to 0.008 percent of Cu, less than or equal to 0.010 percent of V, and the balance of Fe.
The production steps are as follows:
1) use ofw([S]) Using desulfurized molten iron and low-sulfur carbon steel scrap of which the ratio of steel scrap is 10% as raw materials, smelting by adopting a top-bottom combined blown converter and finishing the molten steelw([C])=0.13%、w([S]) =0.010%, T =1644 ℃, the tapping amount is 25T, 1.7kg/T aluminum cake is added for deep deoxidation, and refining is carried out to stationw([Al]) = 0.035%; adding metal manganese, low-titanium low-aluminum ferrosilicon and medium-carbon ferrochromium for alloying, and adding 5.9kg/t lime and 4.3kg/t refining slag when tapping is finished.
2) And after tapping, a sliding plate is used for pushing off slag, and the phosphorus return amount of the molten steel is 0.0011%.
3) The temperature of molten steel reaching an LF station is 1551 ℃, the total time of LF refining of the molten steel is 55min, fine adjustment of C, Si, Mn and Cr components is carried out at the early stage of refining, and ferrotitanium and ferroboron alloy are added under the condition of white slag of refining slag at the middle and later stages. Extract of Chinese medicinal materialsThe flow of bottom-blowing stirring argon in the early refining stage is 180-220 NL/min, the flow of bottom-blowing stirring argon in the middle refining stage is 80-90 NL/min, and the flow of bottom-blowing stirring argon in the later refining stage is 25-40 NL/min. During the refining process, aluminum particles and high-purity silicon carbide are used for diffusion deoxidation of slag surface and precipitation deoxidation of the aluminum particles, the dosage of the high-purity silicon carbide is controlled to be 1.9kg/t, and during the refining processw([Al]) = 0.035% -0.050%, molten steel in refining processw([Ca]) = 0.0011-0.0007%, refining end pointw([S])=0.0014%。
4) The refining final slag comprises the following components:w(CaO)=47.1%、 w(SiO2)=14.8%，w(MgO)=8.4%、w(Al2O3)=28.7%。
5) the molten steel is subjected to RH vacuum treatment, and the molten steel is kept for 28min under the condition that the vacuum is less than or equal to 100 pa. Directly performing soft blowing after the RH treatment is finished, wherein the soft blowing time is 25 min;
6) and after the soft blowing is finished, hoisting the molten steel to continuous casting for continuous casting to form a blank, carrying out Ar sealing protection casting on a ladle long nozzle, wherein the Ar flow is 40L/min, and electromagnetically stirring by using a crystallizer and the tail end. The nitrogen content of the molten steel of the continuous casting tundish minus the nitrogen content of the molten steel of the RH ladle is 0.00016 percent.
In the steels obtained by steps 1) to 6), t.o was 5.3ppm, inclusion rating: dA (sulfides) =0.06, dB (long-strip oxides) =0, dC (particle oxides) =0.03, the grain size is 94% of 2-5 μm, 96% of oxide inclusions are magnesia-alumina spinel, and the balance is alumina inclusions and calcium-aluminum-magnesium composite inclusions.

Claims (7)

1. A production method of steel for track links of ultra-high-purity crawler tracks is characterized by comprising the following steps:
1) use ofw([S]) Less than or equal to 0.003 percent of desulfurized molten iron and low-sulfur carbon steel scrap are used as raw materials, the ratio of the steel scrap is less than or equal to 10 percent, a top-bottom combined blown converter is adopted for smelting, and the end point of the molten steel isw([C])=0.10%~0.20%、w([S])≤0.012%、T>Deoxidizing, alloying and slagging the molten steel in the tapping process at 1620 ℃, and stopping slag by adopting a sliding plate;
2) the temperature of molten steel reaching the LF station is more than 1540 ℃, and the rapid temperature rise and alloy production in the refining process are ensuredMelting, controlling bottom blowing stirring, and performing deep desulfurization by adopting slag surface composite deoxidation to manufacture a low-alkalinity slag system; wherein, the refining time is controlled to be less than or equal to 60min, the fine adjustment of C, Si, Mn and Cr components is carried out at the early stage of refining, and ferrotitanium and ferroboron alloy are added under the condition of white slag of refining slag at the middle and later stages; the flow of bottom-blowing stirring argon gas is 100-300 NL/min in the early stage of refining, temperature rise and alloying, and the flow of bottom-blowing stirring argon gas is 30-100 NL/min in the middle and later stages of refining; the slag surface composite deoxidation and deep desulfurization is to carry out slag surface diffusion deoxidation on aluminum particles and high-purity silicon carbide, precipitate deoxidation on the aluminum particles, and control the refining processw([Al]) = 0.030% -0.055%, refining end pointw([S])<0.003% of the high-purity silicon carbidew(SiC)>95 percent, and the dosage is controlled to be 1.4 to 2.0 kg/t; the process of producing the low-alkalinity slag system comprises the step of adding 0-150 kg of lime and 0-100 kg of premelted refining slag in the early stage of refining so as to obtain the final refining slagw(CaO)/w(SiO2)=3～5，w(MgO)=6%～10%、w(Al2O3) = 25-35%, and ensures molten steel in refining processw([Ca])<0.0015%；
3) Carrying out RH vacuum treatment on the molten steel, and keeping the molten steel for 25-31 min under the condition that the vacuum is less than or equal to 100 pa;
carrying out micro-calcium treatment after RH treatment, and carrying out soft blowing after calcium treatment, wherein the soft blowing time is 25-35 min;
4) after the soft blowing is finished, the molten steel is hoisted to be continuously cast into a blank;
the steel for the track link of the ultrahigh-purity crawler belt comprises the following main chemical components in percentage by mass: 0.34-0.38% of C, 0.15-0.25% of Si, 0.90-1.10% of Mn, 0.15-0.30% of Cr, 0.030-0.045% of Al, 0.025-0.050% of Ti, 0.0020-0.0030% of B, less than or equal to 0.015% of P, less than or equal to 0.005% of S, less than or equal to 0.010% of Ni, less than or equal to 0.008% of Cu, less than or equal to 0.010% of V, and the balance of Fe.
2. The method for producing the steel for the track link of the ultra-high purity crawler according to claim 1, wherein the steel comprises the following steps: in the step 1), the deoxidation is as follows: before the steel tapping amount is 20 t-30 t, adding 1.1-2.0 kg/t of aluminum cakes for deep deoxidation, and ensuring that refining is finished to a stationw([Al])= 0.015%～0.045%。
3. The method for producing the steel for the track link of the ultra-high purity crawler according to claim 1, wherein the steel comprises the following steps: in the step 1), alloying is as follows: after the deoxidation, the metal manganese is usedw(Mn)>97% low titanium low aluminium silicon ironw(Si)>75%、w(Ca)<0.5% medium carbon ferrochromew(Cr)>55 percent of the alloy is used for preliminary alloying of the molten steel.
4. The method for producing the steel for the track link of the ultra-high purity crawler according to claim 1, wherein the steel comprises the following steps: in the step 1), after deoxidation and alloying are finished and before molten steel tapping is finished, slagging is carried out by using lime and premelted refining slag according to the ratio of 2: 1.5.
5. The method for producing the steel for the track link of the ultra-high purity crawler according to claim 4, wherein the steel comprises the following steps: the premelted refining slag comprises the following components in percentage by mass: CaO =45% -55%, SiO2≤10%、MgO=4%～10%、Al2O3=25%～40%、S≤0.1%。
6. The method for producing the steel for the track link of the ultra-high purity crawler according to claim 1, wherein the steel comprises the following steps: in the step 3), calcium treatment is carried out on the molten steel by micro-calcium treatment, the using amount of a silicon-calcium line is 0-50 m/furnace, and the grade of the silicon-calcium line is as follows:w(Ca)>28%、w(Si)>60%。
7. the method for producing the steel for the track link of the ultra-high purity crawler according to claim 1, wherein the steel comprises the following steps: in the step 4), Ar sealing protection casting is carried out on the ladle long nozzle, Ar flow is 10-60L/min,
crystallizer and terminal electromagnetic stirring are used.
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