CN108676952B - Preparation method for producing bearing steel by converter process - Google Patents

Preparation method for producing bearing steel by converter process Download PDF

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CN108676952B
CN108676952B CN201810251679.XA CN201810251679A CN108676952B CN 108676952 B CN108676952 B CN 108676952B CN 201810251679 A CN201810251679 A CN 201810251679A CN 108676952 B CN108676952 B CN 108676952B
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steel
converter
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CN108676952A (en
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张觉灵
白华东
闫宗根
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Jingye Steel Co Ltd
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    • 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
    • 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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/072—Treatment with gases
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/40—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
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: 1 to 1.05C, 0.6 to 0.65 Si, 1.30 to 1.35 Mn, 0.02 to 0.05 Mo, 0.02 to 0.04 Ni, 1.75 to 1.8 Cr, 0.005 to 0.008V, AlS0.01～0.03，Hf 0.02～0.03、Sb 0.001～0.004、Cu 0.15～0.2，S≤0.025，P≤0.025，[O]≤10×10‑6，[H]≤2×10‑6The balance being Fe and unavoidable impurities. By controlling smelting raw materials, refining process, refining slag, crystallizer casting powder and continuous casting process, the obtained bearing steel has low content of non-metal impurities and low content of Ti, a water gap nodulation phenomenon cannot occur in the square billet in the continuous casting process, the billet is smoothly drawn, the solidification speed of a billet shell is high, the continuous casting safety is ensured, and the final product has uniform components, stable performance and good strength.

Description

Preparation method for producing bearing steel by converter process
Technical Field
The invention relates to a method for producing bearing steel, in particular to a method for producing high-carbon chromium bearing steel by adopting a converter and a continuous casting machine.
Background
The high-carbon chromium bearing steel is mainly used for steel balls, rollers and ferrules on bearings of automobiles, motorcycles, household appliances, tractors, railway vehicles, metallurgical mining machinery and high-speed rotating and high-load machinery. Before the invention, the domestic traditional bearing steel production process comprises the following steps: electric furnace smelting → LF furnace refining → vacuum refining → die casting or continuous casting → rolling → slow cooling (air cooling) of slow cooling hood. The process of producing the high-carbon chromium bearing steel by adopting the electric furnace and vacuum treatment has the advantages of multiple processes, long period, high difficulty in smelting structure and high production cost.
The research shows that the T [ O ] (oxygen content) of high-carbon chromium bearing steel is the most key index of bearing fatigue life, and the lower the T [ O ], the longer the fatigue life, so that the quality of high-carbon chromium bearing steel is improved.
Patent CN102418041A discloses a production method of bearing steel, the section of a continuous casting billet of the steel is a round billet with the diameter of 180mm, and a rolled finished steel product is a round steel with the diameter not more than 60mm through a material forming process; the chemical components and the weight percentage content are as follows: 0.95-1.05% of carbon, 0.15-0.35% of silicon, 0.25-0.45% of manganese, less than or equal to 0.025% of phosphorus, less than or equal to 0.025% of sulfur, 1.40-1.65% of chromium, and the balance of Fe and undetectable trace impurity elements; the production process comprises the following steps: converter, LF refining furnace, VD refining furnace, continuous casting, heating furnace heating and rolling. However, the bearing steel prepared by the method still has the problem of non-uniform distribution of non-metallic inclusions, and the performance of the steel cannot meet the strict standard requirements easily.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method of bearing steel. By controlling smelting raw materials, refining process, refining slag, crystallizer casting powder and continuous casting process, the obtained bearing steel has low content of non-metal impurities and low content of Ti, a water gap nodulation phenomenon cannot occur in the square billet in the continuous casting process, the billet is smoothly drawn, the solidification speed of a billet shell is high, the continuous casting safety is ensured, and the final product has uniform components, stable performance and good strength.
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: 1 to 1.05C, 0.6 to 0.65 Si, 1.30 to 1.35 Mn, 0.02 to 0.05 Mo, 0.02 to 0.04 Ni, 1.75 to 1.8 Cr, 0.005 to 0.008V, AlS0.01～0.03，Hf 0.02～0.03、Sb 0.001～0.004、Cu 0.15～0.2，S≤0.025，P≤0.025，[O]≤10×10-6，[H]≤2×10-6The balance of Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, adjusting slag in time during the refining process, and making white slag to control slag system components to be 55-57% of CaO, 211-12% of SiO, 315-20% of Al2O, 6-10% of MgO, less than or equal to 2.0% of FeO + MnO, 4.6-5.2% of CaO/SiO2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
carrying out RH vacuum treatment on the molten steel, controlling the vacuum degree to be less than 200Pa, treating for 25-35 min, pure degassing for 15-25 min, and lifting gas amount to be 1450-1500 NL/min, wherein after RH vacuum treatment, the calcium content in the molten steel is less than 10 multiplied by 10-4 wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The casting speed is controlled to be 0.55-0.60 m/min when a square billet with the cross section of 300mm × 300mm, the superheat degree of molten steel is controlled to be 15-30 ℃, the water flow of a continuous casting billet crystallizer is controlled to be 200-210 m3/h, the solidification of the molten steel in the crystallizer is accelerated, the leakage is avoided, the secondary cooling specific water amount is 0.35-0.40L/kg, the casting powder is used in the continuous casting process, and the components of the casting powder comprise (CaO + BaO) 40-45% and SiO 240 DEG according to mass percentage45％，(CaO+BaO)/SiO20.9-1.0 percent of (Fe2O3+ MnO) 1-3 percent of (B2O3+ Na2O) 5-15 percent of C1-2 percent of (C2O) and the balance of 0-5 percent of inevitable impurities; the addition amount of the covering slag is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
Further, the preparation method for producing the bearing steel by the converter process is characterized by comprising the following steps: 1 to 1.02C, 0.6 to 0.62 Si, 1.30 to 1.32 Mn, 0.02 to 0.04 Mo, 0.02 to 0.03 Ni, 1.75 to 1.78 Cr, 0.005 to 0.006V, AlS0.01～0.02，Hf 0.02～0.025、Sb 0.001～0.003、Cu 0.15～0.18，S≤0.025，P≤0.025，[O]≤10×10-6，[H]≤2×10-6The balance being Fe and unavoidable impurities.
Further, the preparation method for producing the bearing steel by the converter process is characterized by comprising the following steps: c1, Si 0.6, Mn1.30, Mo 0.02, Ni 0.02, Cr 1.75, V0.005, AlS0.01，Hf 0.02、Sb 0.001、Cu 0.15，S≤0.025，P≤0.025，[O]≤8×10-6，[H]≤2×10-6The balance being Fe and unavoidable impurities.
Further, the preparation method for producing the bearing steel by the converter process is characterized by comprising the following steps: c1.02, Si 0.62, Mn1.32, Mo 0.04, Ni0.03, Cr 1.78, V0.006, AlS0.02，Hf 0.025、Sb 0.003、Cu 0.18，S≤0.025，P≤0.025，[O]≤9×10-6，[H]≤2×10-6The balance being Fe and unavoidable impurities.
Further, the preparation method for producing the bearing steel by the converter process is characterized by comprising the following steps: c1.05, Si 0.65, Mn1.35, Mo 0.05, Ni 0.04, Cr 1.8, V0.008, AlS0.03，Hf 0.03、Sb 0.004、Cu 0.2，S≤0.025，P≤0.025，[O]≤8×10-6，[H]≤2×10-6The balance being Fe and unavoidable impurities.
Further, the preparation method for producing the bearing steel by the converter process is characterized by comprising the following steps: smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the converter during smelting is 1600-1620 ℃, lime is added into the converter according to the amount of 65-68 kg lime added into each ton of steel during blowing, solid slag materials with high MgO content are added within the last 2 minutes of the converter blowing so as to improve the MgO content in the converter slag to 10-11 percent, and Fe-Al alloy with 30-32 percent of Al content is added into each ton of steel along with steel flow during tapping to perform pre-deoxidation.
Further, the preparation method for producing the bearing steel by the converter process is characterized by comprising the following steps: and (3) refining in an LF furnace, adjusting slag in time in the refining process, and making white slag to control slag system components to be CaO 55%, SiO 211%, Al2O 316%, MgO 8%, FeO + MnO less than or equal to 1.0%, CaO/SiO2 to be 5, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm.
Further, the preparation method for producing the bearing steel by the converter process is characterized by comprising the following steps: the soaking temperature of the steel billet in a heating furnace is 1200-1220 ℃, the heating and high-temperature diffusion time is 10-11 h, the initial rolling temperature is 1100-1120 ℃, and the final rolling temperature is 850-900 ℃; the cooling speed of the rolled steel is 1.5-1.8 ℃/min.
Further, the preparation method for producing the bearing steel by the converter process is characterized by comprising the following steps: the casting powder is used in the continuous casting process, and comprises the following components in percentage by mass: 45% of (CaO + BaO), 245% of SiO, and (CaO + BaO)/SiO21.0 percent, (Fe2O3+ MnO)3 percent, (B2O3+ Na2O)5 percent, C1 percent and the balance of 1 percent of inevitable impurities; the amount of the mold flux added was 0.45kg/t steel, and the thickness of the liquid slag layer was 12.5 mm.
Hf prevents deterioration of fatigue strength, particularly rolling fatigue, and in the present invention, when the content exceeds 0.03 mass%, the content is set to 0.03 mass% or less because it does not contribute to further improvement of strength even if the content increases. In order to exhibit the effect of improving the fatigue strength, it is preferably set to 0.02 mass% or more.
Sb can prevent the fatigue strength, particularly the rolling fatigue, from deteriorating, and in the present invention, when the content thereof is increased to more than 0.004 mass%, the content thereof is set to 0.004 mass% or less, and preferably 0.001 mass% or more in order to exhibit the effect of improving the fatigue strength.
The bearing steel refining slag mainly has three tasks: firstly, the number of inclusions, particularly the number of oxide inclusions, is reduced; secondly, the property and the shape of the inclusion are improved, the proportion of the plastic inclusion is increased, and the CaO type spherical inclusion is reduced or eliminated; thirdly, the content of sulfur in the steel is reduced. According to the components of the refining slag system, the bearing steel refining slag is divided into acid slag and alkaline slag. Under the condition of the current stage, when the bearing steel is smelted by LF, the high-alkalinity refining slag is generally most beneficial to reducing dissolved oxygen in the steel, and has the strongest desulfurization capability, but the punctiform inclusions of the high-alkalinity refining slag reach 0.9 level; the lowest forming possibility of punctiform inclusions is achieved when low-alkalinity slag of about 2.0 is adopted, the invention takes the reduction of oxide inclusions in steel as an important purpose, and the research and analysis of the refining slag of bearing steel show that the use of high-alkalinity refining slag (CaO/SiO2 is 4.6-5.2) is most beneficial to the reduction of dissolved oxygen in steel, has the strongest desulfurization capability and reduces the harm of punctiform inclusions to the service life of a bearing.
The casting powder of the invention can not be reduced or Al2O3 can not be reduced when contacting molten steel because the casting powder can be combined with CaO, BaO and the like into stable compounds even if Al2O3 exists in the casting powder, and the reduction of Al2O3 can not occur when oxides with high activity such as Fe2O3, MnO and SiO2 exist, so that the lubricating requirement is met, the casting blank surface casting powder layer is uniform, no slag ring exists in a crystallizer, the casting blank has no slag inclusion, no drawing leakage and no aluminum increase phenomenon in steel, and the casting powder of the invention can not increase aluminum in molten steel.
The invention has the beneficial effects that:
1. the production process of high-quality bearing steel features that the raw materials and production process are strictly controlled to make the large-size inclusion (more than 10 microns in diameter) be fully polymerized by collision and discharged from molten steel, so promoting the inclusion in steel to float upward fully, increasing molten steel cleanliness, controlling the large-size inclusion and increasing steel fatigue performance, and because of the better titanium-removing condition in converter, the titanium content in molten steel is only 6 × 10-6This is a low titanium bearing steelThe production of (2) provides good molten steel conditions;
2. the castability of molten steel is good, the content of aluminum is properly controlled, and the total oxygen is further reduced. The nozzle nodulation caused by alumina and Ti-containing compounds is avoided, and the castability of molten steel is greatly improved, so that the aluminum is easily controlled to be 0.01-0.03%, the total oxygen in the steel is further reduced, and the inclusions in the steel are correspondingly reduced;
3. the invention further optimizes the components of the bearing steel and combines the distribution of low-content nonmetallic inclusion, so that the overall mechanical property, particularly the fatigue resistance, is greatly improved;
4. the casting powder has the casting powder performance more suitable for the continuous casting requirement of the aluminum-free or ultra-low aluminum steel, namely, the casting powder has lower melting point, higher melting speed, higher spreadability and proper viscosity, and the functions of lubricating, preventing oxidation, absorbing impurities and the like of the casting powder are ensured;
5. the smelting process is utilized to control the inclusion in the bearing steel, and finally the steel is obtained, wherein the content of the A-type coarse impurities is less than or equal to 0.5%, the content of the A-type fine impurities is less than or equal to 0.5%, the content of the B-type coarse impurities is less than or equal to 0.5%, the content of the D-type coarse impurities is less than or equal to 0.5%, the content of the C-type coarse impurities is zero, and the content of the C-type fine impurities is zero, so that the content of various inclusions is greatly reduced, the forging performance of the bearing steel is improved, and the service life of the bearing steel is prolonged.
Detailed Description
The technical solution of the present invention will be described in detail with reference to exemplary embodiments. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.
Example 1
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: c1, Si 0.6, Mn1.30，Mo 0.02，Ni 0.02、Cr 1.75，V 0.005、AlS0.01，Hf 0.02、Sb 0.001、Cu 0.15，S≤0.025，P≤0.025，[O]≤8×10-6，[H]≤2×10-6The balance of Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, adjusting slag in time during the refining process, and making white slag to control slag system components to be 55-57% of CaO, 211-12% of SiO, 315-20% of Al2O, 6-10% of MgO, less than or equal to 2.0% of FeO + MnO, 4.6-5.2% of CaO/SiO2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 25-35 min, the pure degassing time is 15-25 min, the lift gas amount is 1450-1500 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The casting speed is controlled to be 0.55-0.60 m/min at the cross section of a square billet with the thickness of 300mm × 300mm, the superheat degree of molten steel is controlled to be 15-30 ℃, and the water flow of a continuous casting crystallizer is controlled to be 200-210 m3/h to accelerate the molten steel in the crystallizerThe inner blank shell is solidified to avoid drawing leakage, and the secondary cooling specific water amount is 0.35-0.40L/kg; the casting powder is used in the continuous casting process, and comprises the following components in percentage by mass: 40-45% of (CaO + BaO), 240-45% of SiO, and (CaO + BaO)/SiO20.9-1.0 percent of (Fe2O3+ MnO) 1-3 percent of (B2O3+ Na2O) 5-15 percent of C1-2 percent of (C2O) and the balance of 0-5 percent of inevitable impurities; the addition amount of the covering slag is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
Example 2
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: c1.02, Si 0.62, Mn1.32, Mo 0.04, Ni0.03, Cr 1.78, V0.006, AlS0.02，Hf 0.025、Sb 0.003、Cu 0.18，S≤0.025，P≤0.025，[O]≤9×10-6，[H]≤2×10-6The balance of Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, adjusting slag in time during the refining process, and making white slag to control slag system components to be 55-57% of CaO, 211-12% of SiO, 315-20% of Al2O, 6-10% of MgO, less than or equal to 2.0% of FeO + MnO, 4.6-5.2% of CaO/SiO2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 25-35 min, the pure degassing time is 15-25 min, the lift gas amount is 1450-1500 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The casting speed is controlled to be 0.55-0.60 m/min when a square billet with the cross section of 300mm × 300mm is taken, the superheat degree of molten steel is controlled to be 15-30 ℃, the water flow of a continuous casting billet crystallizer is controlled to be 200-210 m3/h, the solidification of the molten steel in the crystallizer is accelerated, the casting leakage is avoided, the secondary cooling specific water amount is 0.35-0.40L/kg, protective slag is used in the continuous casting process, and the components of the protective slag comprise (CaO + BaO) 40-45%, SiO 240-45%, and (CaO + BaO)/SiO by mass percent20.9-1.0 percent of (Fe2O3+ MnO) 1-3 percent of (B2O3+ Na2O) 5-15 percent of C1-2 percent of (C2O) and the balance of 0-5 percent of inevitable impurities; the addition amount of the covering slag is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
Example 3
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: c1.05, Si 0.65, Mn1.35, Mo 0.05, Ni 0.04, Cr 1.8, V0.008, AlS0.03，Hf 0.03、Sb 0.004、Cu 0.2，S≤0.025，P≤0.025，[O]≤8×10-6，[H]≤2×10-6The balance of Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, adjusting slag in time during the refining process, and making white slag to control slag system components to be 55-57% of CaO, 211-12% of SiO, 315-20% of Al2O, 6-10% of MgO, less than or equal to 2.0% of FeO + MnO, 4.6-5.2% of CaO/SiO2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 25-35 min, the pure degassing time is 15-25 min, the lift gas amount is 1450-1500 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The drawing speed is controlled to be 0.55-0.60 m/min when the cross section of a square billet with the size of 300mm multiplied by 300mm is adopted, the superheat degree of molten steel is controlled to be 15-30 ℃, the water flow of a continuous casting crystallizer is controlled to be 200-210 m3/h, the solidification of a billet shell of the molten steel in the crystallizer is accelerated, the drawing leakage is avoided, and the secondary cooling specific water flow is 0.35-0.40L/kg; the casting powder is used in the continuous casting process, and comprises the following components in percentage by mass: 40-45% of (CaO + BaO), 240-45% of SiO, 0.9-1.0% of (CaO + BaO)/SiO2, (1-3% of Fe2O3+ MnO), (5-15% of (B2O3+ Na2O), 1-2% of C, and 0-5% of unavoidable impurities in balance; the addition amount of the covering slag is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
Comparative example 1
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: c1.3, Si 0.6, Mn1.30, Mo 0.02, Ni 0.02, Cr 1.25, V0.005 and AlS0.01，Hf 0.02，S≤0.025，P≤0.025，[O]≤8×10-6，[H]≤2×10-6The balance of Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, adjusting slag in time during the refining process, and making white slag to control slag system components to be 55-57% of CaO, 211-12% of SiO, 315-20% of Al2O, 6-10% of MgO, less than or equal to 2.0% of FeO + MnO, 4.6-5.2% of CaO/SiO2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 25-35 min, the pure degassing time is 15-25 min, the lift gas amount is 1450-1500 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The drawing speed is controlled to be 0.55-0.60 m/min when the cross section of a square billet with the size of 300mm multiplied by 300mm is adopted, the superheat degree of molten steel is controlled to be 15-30 ℃, the water flow of a continuous casting crystallizer is controlled to be 200-210 m3/h, the solidification of a billet shell of the molten steel in the crystallizer is accelerated, the drawing leakage is avoided, and the secondary cooling specific water flow is 0.35-0.40L/kg; the casting powder is used in the continuous casting process, and comprises the following components in percentage by mass: 40-45% of (CaO + BaO), 240-45% of SiO, 0.9-1.0% of (CaO + BaO)/SiO2, (1-3% of Fe2O3+ MnO), (5-15% of (B2O3+ Na2O), 1-2% of C, and 0-5% of unavoidable impurities in balance; the addition amount of the covering slag is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
Comparative example 2
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: c1.02, Si 0.62, Mn1.32, Mo 0.04, Ni0.03, Cr 1.78, V0.006, AlS0.02，Hf 0.025、Sb 0.003、Cu 0.18，S≤0.025，P≤0.025，[O]≤9×10-6，[H]≤2×10-6The balance being Fe and unavoidableThe impurities of (a); the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, 40-45 kg of lime is added into the converter in the blowing process according to the amount of lime added into each ton of steel, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process so as to improve the MgO content in the converter slag to 5-8 percent, and 3-3.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with the steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, adjusting slag in time during the refining process, and making white slag to control slag system components to be 55-57% of CaO, 211-12% of SiO, 315-20% of Al2O, 6-10% of MgO, less than or equal to 2.0% of FeO + MnO, 4.6-5.2% of CaO/SiO2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 25-35 min, the pure degassing time is 15-25 min, the lift gas amount is 1450-1500 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The drawing speed is controlled to be 0.55-0.60 m/min when the cross section of a square billet with the size of 300mm multiplied by 300mm is adopted, the superheat degree of molten steel is controlled to be 15-30 ℃, the water flow of a continuous casting crystallizer is controlled to be 200-210 m3/h, the solidification of a billet shell of the molten steel in the crystallizer is accelerated, the drawing leakage is avoided, and the secondary cooling specific water flow is 0.35-0.40L/kg; the casting powder is used in the continuous casting process, and comprises the following components in percentage by mass: 40-45% of (CaO + BaO), 240-45% of SiO, 0.9-1.0% of (CaO + BaO)/SiO2, (1-3% of Fe2O3+ MnO), (5-15% of (B2O3+ Na2O), 1-2% of C, and 0-5% of unavoidable impurities in balance; the addition amount of the covering slag is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
Comparative example 3
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: c1.05, Si 0.65, Mn1.35, Mo 0.05, Ni 0.04, Cr 1.8, V0.008, AlS0.03，Hf 0.03、Sb 0.004、Cu 0.2，S≤0.025，P≤0.025，[O]≤8×10-6，[H]≤2×10-6The balance of Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, timely adjusting slag in the refining process, and making white slag to control slag system components to be CaO 45-48%, SiO 215-18%, Al2O 320-30%, MgO 15-20%, FeO + MnO less than or equal to 2.0%, CaO/SiO2 to be 2.5-3.2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 15-20 min, the pure degassing time is 10-12 min, the gas lifting amount is 1200-1300 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The drawing speed is controlled to be 0.55-0.60 m/min when the cross section of a square billet with the size of 300mm multiplied by 300mm is adopted, the superheat degree of molten steel is controlled to be 15-30 ℃, the water flow of a continuous casting crystallizer is controlled to be 200-210 m3/h, the solidification of a billet shell of the molten steel in the crystallizer is accelerated, the drawing leakage is avoided, and the secondary cooling specific water flow is 0.35-0.40L/kg; the casting powder is used in the continuous casting process, and comprises the following components in percentage by mass: 40-45% of (CaO + BaO), 240-45% of SiO, 0.9-1.0% of (CaO + BaO)/SiO2, (1-3% of Fe2O3+ MnO), (5-15% of (B2O3+ Na2O), 1-2% of C, and 0-5% of unavoidable impurities in balance; the addition amount of the covering slag is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
Comparative example 4
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: c1.05, Si 0.65, Mn1.35, Mo 0.05, Ni 0.04, Cr 1.8, V0.008, AlS0.03，Hf 0.03、Sb 0.004、Cu 0.2，S≤0.025，P≤0.025，[O]≤8×10-6，[H]≤2×10-6The balance of Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, adjusting slag in time during the refining process, and making white slag to control slag system components to be 55-57% of CaO, 211-12% of SiO, 315-20% of Al2O, 6-10% of MgO, less than or equal to 2.0% of FeO + MnO, 4.6-5.2% of CaO/SiO2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 25-35 min, the pure degassing time is 15-25 min, the lift gas amount is 1450-1500 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The drawing speed is controlled to be 0.55-0.60 m/min when the cross section of a square billet with the size of 300mm multiplied by 300mm is adopted, the superheat degree of molten steel is controlled to be 15-30 ℃, the water flow of a continuous casting crystallizer is controlled to be 200-210 m3/h, the solidification of a billet shell of the molten steel in the crystallizer is accelerated, the drawing leakage is avoided, and the secondary cooling specific water flow is 0.35-0.40L/kg; the casting powder is used in the continuous casting process, and comprises the following components in percentage by mass: 40-45% of (CaO + BaO), 240-45% of SiO, 0.9-1.0% of (CaO + BaO)/SiO2, (1-3% of Fe2O3+ MnO), (5-15% of (B2O3+ Na2O), 1-2% of C, and 0-5% of unavoidable impurities in balance; the addition amount of the covering slag is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1250-1260 ℃, the heating and high-temperature diffusion time is 20-25 h, the initial rolling temperature is 1170-1180 ℃, and the final rolling temperature is 700-800 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
Comparative example 5
A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: c1.05, Si 0.65, Mn1.35, Mo 0.05, Ni 0.04, Cr 1.8, V0.008, AlS0.03，Hf 0.03、Sb 0.004、Cu 0.2，S≤0.025，P≤0.025，[O]≤8×10-6，[H]≤2×10-6The balance of Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, adjusting slag in time during the refining process, and making white slag to control slag system components to be 55-57% of CaO, 211-12% of SiO, 315-20% of Al2O, 6-10% of MgO, less than or equal to 2.0% of FeO + MnO, 4.6-5.2% of CaO/SiO2, wherein the refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is between 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 25-35 min, the pure degassing time is 15-25 min, the lift gas amount is 1450-1500 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, soft argon blowing is carried out on the molten steel, the soft blowing time is 10-25 min, and the soft argon blowing amount is controlled to be 20-50 NL/min;
(4) continuous casting
The drawing speed is controlled to be 0.55-0.60 m/min when the cross section of a square billet with the size of 300mm multiplied by 300mm is adopted, the superheat degree of molten steel is controlled to be 15-30 ℃, the water flow of a continuous casting crystallizer is controlled to be 200-210 m3/h, the solidification of a billet shell of the molten steel in the crystallizer is accelerated, the drawing leakage is avoided, and the secondary cooling specific water flow is 0.35-0.40L/kg; the casting powder is used in the continuous casting process, the alkalinity of the casting powder is 1.5-2.0, the adding amount of the casting powder is 0.3-0.5 kg/t steel, and the thickness of the liquid slag layer is 10-15 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
The bearing steel products of examples 1 to 3 and comparative examples 1 to 5 of the present invention were subjected to inclusion inspection, and the inspection results are shown in table 1.
TABLE 1
Figure BSA0000161262190000131
The terminology used herein is for the purpose of description and illustration, rather than of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.

Claims (5)

1. A preparation method for producing bearing steel by a converter process comprises the steps of raw material preparation, converter smelting and alloying, LF + RH refining, continuous casting, rolling and slow cooling; controlling the chemical components of the bearing steel in percentage by mass as follows: 1 to 1.02C, 0.6 to 0.62 Si, 1.30 to 1.32 Mn, 0.02 to 0.04 Mo, 0.02 to 0.03 Ni, 1.75 to 1.78 Cr, 0.005 to 0.006V, 0.01 to 0.02 AlS, 0.02 to 0.025 Hf, 0.001 to 0.003 Sb, 0.15 to 0.18 Cu, less than or equal to 0.025S, less than or equal to 0.025P and [ O ] O]≤10×10-6，[H]≤2×10-6The balance being Fe and inevitable impurities; the specific production steps are as follows:
(1) raw material preparation
Preparing raw materials by taking a converter with the capacity of 250t as a standard, wherein molten iron with the content of P being less than or equal to 0.07 percent and S being less than or equal to 0.02 percent accounts for 84-86 percent, scrap steel with the content of P being less than or equal to 0.07 percent, S being less than or equal to 0.02 percent and Ti being less than or equal to 0.05 percent accounts for 6-8 percent, and the rest are iron blocks with the content of P being less than or equal to 0.07 percent and S being less than or equal;
(2) smelting in a converter
Smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the smelted converter is 1600-1650 ℃, the lime is added into the converter according to the amount of 65-68 kg of lime added into each ton of steel in the blowing process, solid slag materials with high MgO content are added into the converter within the last 2 minutes of the converter blowing process, the MgO content in the converter slag is 10-12 percent, and 5-5.5 kg of Fe-Al alloy with 30-35 percent of Al content is added into each ton of steel along with steel flow during tapping process for pre-deoxidation;
(3) refining
Refining in an LF furnace, timely adjusting slag in the refining process, and making white slag to control slag system components to be CaO 55-57% and SiO211～12％、Al2O315～20％、MgO 6～10％、FeO+MnO≤2.0％、CaO/SiO2The refining tapping temperature of the LF furnace is 1560-1580 ℃, aluminum is 0.03-0.04% during tapping, and dissolved oxygen is less than or equal to 4 ppm;
RH vacuum treatment is carried out on the molten steel, the vacuum degree is controlled to be less than 200Pa, the treatment time is 25-35 min, the pure degassing time is 15-25 min, the lift gas amount is 1450-1500 NL/min, and after the RH vacuum treatment, the calcium content in the molten steel is less than 10 × 10- 4wt%; after the RH vacuum treatment is finished, the molten steel is softenedBlowing argon for 10-25 min, and controlling the soft blowing amount to be 20-50 NL/min;
(4) continuous casting
The casting speed is controlled to be 0.55-0.60 m/min at the cross section of a square billet of 300mm × 300mm, the superheat degree of molten steel is controlled to be 15-30 ℃, and the water flow of a continuous casting billet crystallizer is controlled to be 200-210 m3The solidification of the molten steel in the crystallizer blank shell is accelerated, the pulling leakage is avoided, and the secondary cooling specific water amount is 0.35-0.40L/kg; the casting powder is used in the continuous casting process, and comprises the following components in percentage by mass: (CaO + BaO) 45%, SiO245％，(CaO+BaO)/SiO2Is 1.0, (Fe)2O3+MnO) 3％，(B2O3+Na2O) 5%, C1% and the balance of inevitable impurities 1%; the addition amount of the covering slag is 0.45kg/t steel, and the thickness of a liquid slag layer is 12.5 mm;
(5) rolling and slow cooling
The soaking temperature of the steel billet in a heating furnace is 1200-1230 ℃, the heating and high-temperature diffusion time is 10-12 h, the initial rolling temperature is 1100-1150 ℃, and the final rolling temperature is 850-950 ℃; the cooling speed of the rolled steel is 1.5-2.0 ℃/min.
2. The method for producing bearing steel by the converter process according to claim 1, wherein: c1, Si 0.6, Mn1.30, Mo 0.02, Ni 0.02, Cr 1.75, V0.005, AlS 0.01, Hf 0.02, Sb 0.001, Cu 0.15, S less than or equal to 0.025, P less than or equal to 0.025, [ O ] O]≤8×10-6，[H]≤2×10-6The balance being Fe and unavoidable impurities.
3. The method for producing bearing steel by the converter process according to claim 1, wherein: smelting in a converter, wherein the end point phosphorus is less than or equal to 0.01 percent, the end point carbon is more than or equal to 0.35 percent, the tapping temperature of the converter during smelting is 1600-1620 ℃, lime is added into the converter according to the amount of 65-68 kg lime added into each ton of steel during blowing, solid slag materials with high MgO content are added within the last 2 minutes of the converter blowing so as to improve the MgO content in the converter slag to 10-11 percent, and Fe-Al alloy with 30-32 percent of Al content is added into each ton of steel along with steel flow during tapping to perform pre-deoxidation.
4. The method for producing bearing steel by the converter process according to claim 1, wherein: refining in an LF furnace, timely slag adjustment in the refining process and white slag making are carried out, so that slag system components are controlled to be CaO 55% and SiO211％、Al2O316％、MgO 8％、FeO+MnO≤1.0％、CaO/SiO2And (5), the refining tapping temperature of the LF furnace is 1560-1580 ℃, the aluminum content is 0.03-0.04% during tapping, and the dissolved oxygen content is less than or equal to 4 ppm.
5. The method for producing bearing steel by the converter process according to claim 1, wherein: the soaking temperature of the steel billet in a heating furnace is 1200-1220 ℃, the heating and high-temperature diffusion time is 10-11 h, the initial rolling temperature is 1100-1120 ℃, and the final rolling temperature is 850-900 ℃; the cooling speed of the rolled steel is 1.5-1.8 ℃/min.
CN201810251679.XA 2018-03-26 2018-03-26 Preparation method for producing bearing steel by converter process Expired - Fee Related CN108676952B (en)

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