Low-titanium low-oxygen smelting control method for high-grade and special-grade bearing steel

Abstract

The invention relates to the technical field of high-carbon chromium bearing steel smelting, and discloses a high-grade and special-grade bearing steel low-titanium low-oxygen smelting control method which comprises the steps of S1, raw material pretreatment, S2, KR deep S removal treatment, S3, converter smelting, S4, LF refining, S5, VD / RH vacuum treatment, S6, continuous casting process and S7, process inspection and control. Low-Ti molten iron is strictly screened through raw material pretreatment, low-Ti auxiliary materials are selected, LF refining slag skimming and salvaging are matched to remove Ti-rich slag, VD / RH vacuum intensified deoxidation is carried out, the Ti element is effectively prevented from being brought in and returned, the Ti content is stably controlled to be 0.0010%-0.0015%, the O content is precisely locked to be 0.0005%-0.00065% and far exceeds the industry special-grade product standard, the Ti / O hit rate is increased to 100% and 80% or above, and the requirement of the special-grade product is met. And the pain point of large Ti / O content fluctuation in the traditional process is solved.

Description

Technical Field

[0001] This invention relates to the field of high-carbon chromium bearing steel smelting technology, specifically a method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen. Background Technology

[0002] GCr15 steel, as the core grade of high-carbon chromium bearing steel, is widely used in high-end equipment fields such as automotive bearings and precision machinery bearings. Its premium grade has stringent requirements for the control precision of Ti and O content, steel purity, internal structure uniformity and surface quality. Currently, the production of premium GCr15 steel in the industry generally faces multiple technical bottlenecks: First, Ti elements are easily introduced through molten iron raw materials, alloy auxiliary materials, and residues in smelting equipment, and are prone to reversion during refining, making it difficult to stably control the Ti content below 0.0015%; Second, the total oxygen content is greatly affected by deoxidation processes, vacuum treatment effects, and secondary oxidation, with most steel mills controlling the O content in the range of 5-9 ppm, making it difficult to consistently meet the requirement of ≤6.5 ppm for premium grade products; Third, the removal of inclusions during smelting is incomplete, with a high proportion of large-size inclusions (≥10μm), which easily leads to quality issues such as black spots and cracks in bearing rings; Fourth, carbon segregation is a prominent problem during continuous casting, with segregation indices mostly above 1.10, affecting the uniformity of the steel's mechanical properties; Fifth, surface defects (such as folds, cracks, and scabs) occur frequently, leading to customer complaints such as peeling of the outer skin of the tube and spontaneous breakage of the wire rod, which restricts its application in the high-end bearing field. Meanwhile, although mainstream competitors have achieved low-level control of Ti and O content, there is still room for improvement in the precise control of inclusions, optimization of carbon segregation, and quality stability. The industry urgently needs a smelting process that can achieve precise control of Ti / O content and take into account both purity and microstructure uniformity. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen content. This method has the advantages of precise and controllable Ti / O content, meeting the core requirements of high-grade products, and solving the problem that Ti elements are easily introduced through molten iron raw materials, alloy auxiliary materials, and smelting equipment residues, and that the reversion phenomenon easily occurs during the refining process.

[0004] (II) Technical Solution To achieve precise and controllable Ti / O content and meet the core requirements of premium grade products, this invention provides the following technical solution: a method for controlling the smelting of premium grade bearing steel with low titanium and low oxygen, including S1 raw material pretreatment, S2 KR deep desulfurization treatment, S3 converter smelting, S4 LF refining, S5 VD / RH vacuum treatment, S6 continuous casting process and S7 process inspection and control, wherein the S1 raw material pretreatment includes S101 control of molten iron entering the furnace and S102 selection of auxiliary materials; Among them, S4 LF refining includes S401 slag removal, S402 argon blowing deoxidation, S403 composition fine-tuning and S404 final deoxidation treatment. Among them, the S5 VD / RH vacuum treatment includes S501 argon blowing control, S502 vacuum treatment, S503 temperature control and S504 gas control; The S6 continuous casting process includes S601 protective casting, S602 crystallizer parameters, S603 reduction control and S604 billet treatment. Among them, S7 process inspection and control includes S701 composition detection, S702 billet quality inspection and S703 inclusion control.

[0005] Preferably, the molten iron fed into the furnace in S101 is controlled as follows: [S]≤0.045%-0.055%, [P]≤0.140%-0.160%, Ti≤0.05%-0.07%, and low-Ti molten iron raw materials are strictly selected to avoid introducing excessive Ti elements.

[0006] Preferably, the auxiliary material S102 is selected from: low-Ti alloy (low-carbon ferrochrome, low-aluminum low-titanium ferrosilicon, metallic manganese), low-titanium low-boron pre-melted slag and diversion sand with excellent diversion effect; steel tanks that have been smelted with Ti-containing steel grades are prohibited from use, and the slag on the edge of the tank should be thoroughly cleaned before use. Turnover tanks or special steel tanks are preferred.

[0007] Preferably, the S2 KR deep desulfurization treatment: Desulfurization target: Control the [S] content of molten steel to ≤0.002%-0.003%, reduce the desulfurization load of subsequent LF refining, shorten the refining time, and reduce the risk of Ti element return during the refining process; Processing parameters: The stirring power should be adapted to the tonnage of molten steel, and the stirring time should be 30-45 minutes to ensure that the desulfurizing agent and molten steel are in full contact and react.

[0008] Preferably, the S3 converter smelting: End-point control of tapping: End-point [C] 0.08%-0.12%, to avoid over-oxidation of molten steel, which would increase the difficulty of subsequent deoxidation; Slag blocking during steel tapping: Mechanical slag blocking combined with slag-blocking agent is used to assist in slag blocking. Slag feeding is strictly prohibited to prevent harmful impurities from being introduced into the furnace. Alloy addition: When 1 / 4 of the steel is tapped, a pre-set low-Ti alloy and slag are added along the steel flow. The target composition of the steel entering the station is: [C] 0.82%-0.98%, [Mn] 0.22%-0.38%, [Cr] 1.32%-1.48%.

[0009] Preferably, the S401 slag removal / removal operation is performed first after the steel enters the station to remove Ti-rich slag from the surface of the molten steel and reduce the Ti content of the molten steel. S402 Argon blowing deoxidation: Total argon blowing time is 40-60 min. Al particles are used for diffusion deoxidation, combined with low Ti synthesis slag for rapid slag formation, deoxidation, and desulfurization. The slag formation time is controlled at 20-30 min. S403 composition fine-tuning: The composition is precisely adjusted according to the target value, with key control of [Cr] 1.40%-1.65%, [C] at the station 0.94%-1.00%, and carbon difference between the upper and lower furnaces ≤0.04%; Al content is adjusted ≤1 time to avoid excessive Al leading to increased inclusions; S404 final deoxidation treatment: When molten steel leaves the station, sprinkle 5-15 kg of aluminum powder onto the slag surface to enhance deoxidation. It is strictly forbidden to add Ca or Ca alloy for deoxidation or to modify inclusions.

[0010] Preferably, the S501 argon blowing control is as follows: total argon blowing time for VD furnace is 50-70 min, and total argon blowing time for RH furnace is 40-60 min; S502 vacuum treatment: vacuum degree ≤67Pa, vacuum holding time 15-25min; after breaking the vacuum, soft argon blowing in VD furnace for 15-35min, soft argon blowing in RH furnace for 15-30min, and settling time 10-25min to promote the floating of inclusions; S503 Temperature Control: The superheat of molten steel leaving the station is 18-38℃ for the initial casting furnace and 12-32℃ for the continuous casting furnace (liquid phase reference temperature 1450-1460℃). S504 Gas Control: At least one furnace sample is taken for testing [H] after each casting, and [H] is controlled to be ≤1.2-1.5ppm; an appropriate amount of heat-insulating agent is added to the ladle when it leaves the station.

[0011] Preferably, the S601 protective casting process uses carbonized rice husks and high-carbon steel special protective slag throughout to prevent secondary oxidation of the molten steel. S602 crystallizer parameters: crystallizer water flow rate 3200-4000L / min, pulling speed 0.48-0.56m / min, specific water volume 0.16-0.20L / kg; crystallizer electromagnetic stirring current 220-280A, frequency 2.0-3.0Hz, end electromagnetic stirring current 320-380A, frequency 7.0-9.0Hz; S603 reduction control: The designed reduction is 22-28mm, which improves the center segregation of the billet through heavy reduction; S604 billet processing: Slow cooling time for billets ≥ 48-72h, hot billet insulation is preferred for the bottom and top layers; billets with liquid level fluctuations in the crystallizer exceeding ±4-6mm are rejected.

[0012] Preferably, the S701 composition detection involves sampling and testing at the LF outlet, VD / RH outlet, and billet casting stage for each heat, controlling Ti ≤ 0.0010%-0.0015% and O ≤ 0.0005%-0.00065%. S702 billet quality inspection: For each casting, samples covering all flows are taken for low magnification and segregation inspection. The segregation index is required to be ≤1.05-1.08, with no obvious central porosity or shrinkage defects.

[0013] Preferably, the S703 inclusion control: by automatically analyzing and detecting the quantity and size of inclusions, it ensures that the proportion of inclusions with a size ≥10μm is ≤3%-5%, thus avoiding large-particle inclusions from affecting the steel quality.

[0014] (III) Beneficial Effects Compared with the prior art, the present invention provides a method for controlling the smelting of high-quality bearing steel with low titanium and low oxygen content, which has the following beneficial effects: 1. This process achieves precise control of Ti / O content, meeting the core requirements of premium grade products: Through strict screening of low-Ti molten iron and selection of low-Ti auxiliary materials in raw material pretreatment, combined with LF refining to remove Ti-rich slag and VD / RH vacuum enhanced deoxidation, the process effectively avoids the introduction and return of Ti elements, stabilizing the Ti content at 0.0010%-0.0015% and precisely locking the O content at 0.0005%-0.00065%, far exceeding the industry standard for premium grade products. The Ti / O hit rate is increased to over 100% and 80% respectively, solving the pain point of large fluctuations in Ti / O content in traditional processes.

[0015] 2. This process significantly improves steel purity and effectively controls inclusions: KR deep desulphurization shortens refining time and reduces inclusion formation; LF refining rapidly forms slag, and the synergistic effect of argon stirring, combined with VD / RH vacuum settling, promotes inclusion flotation, resulting in a significant reduction in the number of inclusions. The proportion of inclusions with a size ≥10μm is controlled within 3%-5%, significantly reducing magnesium aluminum spinel and calcium aluminate composite inclusions, and lowering the incidence of black spots and cracks in bearing rings.

[0016] 3. This process optimizes the internal structure uniformity and effectively improves carbon segregation: The continuous casting process adopts precise speed control (0.48-0.56m / min), electromagnetic stirring and 22-28mm heavy pressure, and the billet segregation index is controlled within 1.05-1.08, and the carbon range is reduced to 0.01-0.06%, avoiding the problems of loose center and excessive carbide banding in traditional processes, and ensuring uniform mechanical properties of steel.

[0017] 4. This process significantly reduces surface defects and improves quality stability: By controlling slag removal during steel tapping in the converter, strictly controlling liquid level fluctuations in the continuous casting crystallizer (±4-6mm for rejection), and slow cooling treatment of the billet, surface defects such as folds, cracks, and scabs are effectively reduced. The pass rate of magnetic flux leakage testing is increased to over 98%, reducing the risk of customer complaints about external peeling of pipes and spontaneous breakage of wire rods. The product quality stability is significantly better than that of traditional processes.

[0018] 5. This process adapts to the demands of the high-end market and enhances competitiveness: The premium GCr15 steel produced by this process fully matches the high-end application scenarios of automotive wheel bearings and precision mechanical bearings in terms of purity, microstructure uniformity and surface quality. It can meet the technical requirements of high-end customers such as SKF and Schaeffler, break through the technical barriers of mainstream competitors, and increase the market share of the product in the high-end bearing steel market. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] This solution provides a technical approach, specifically a method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen, comprising the following processes: S1 Raw material pretreatment: S101 molten iron feed control: [S]≤0.045%-0.055%, [P]≤0.140%-0.160%, Ti≤0.05%-0.07%, strictly screen low-Ti molten iron raw materials to avoid introducing excessive Ti elements; S102 auxiliary materials selection: use low-Ti alloy (low-carbon ferrochrome, low-aluminum low-titanium ferrosilicon, metallic manganese), low-titanium low-boron pre-melted slag and diversion sand with excellent diversion effect; steel tanks that have been smelted with Ti-containing steel grades are prohibited from use. Thoroughly clean the slag on the tank rim before use. Use turnover tanks or special steel tanks as a priority. S2 KR Deep S-removal Treatment: Desulfurization target: Control the [S] content of molten steel to ≤0.002%-0.003%, reduce the desulfurization load of subsequent LF refining, shorten the refining time, and reduce the risk of Ti element return during the refining process; Processing parameters: The stirring power should be adapted to the tonnage of molten steel, and the stirring time should be 30-45 minutes to ensure that the desulfurizing agent and molten steel are in full contact and react. S3 converter smelting: End-point control of tapping: End-point [C] 0.08%-0.12%, to avoid over-oxidation of molten steel, which would increase the difficulty of subsequent deoxidation; Slag blocking during steel tapping: Mechanical slag blocking combined with slag-blocking agent is used to assist in slag blocking. Slag feeding is strictly prohibited to prevent harmful impurities from being introduced into the furnace. Alloy addition: When 1 / 4 of the steel is tapped, a pre-set low-Ti alloy and slag are added along the steel flow. The target composition of the steel entering the station is: [C] 0.82%-0.98%, [Mn] 0.22%-0.38%, [Cr] 1.32%-1.48%. S4 LF Refined: S401 Slag Removal: Slag removal / removal is prioritized after the molten steel enters the station to remove Ti-rich slag from the surface of the molten steel and reduce the Ti content of the molten steel; S402 Argon blowing deoxidation: Total argon blowing time is 40-60 min. Al particles are used for diffusion deoxidation, combined with low Ti synthesis slag for rapid slag formation, deoxidation, and desulfurization. The slag formation time is controlled at 20-30 min. S403 composition fine-tuning: The composition is precisely adjusted according to the target value, with key control of [Cr] 1.40%-1.65%, [C] at the station 0.94%-1.00%, and carbon difference between the upper and lower furnaces ≤0.04%; Al content is adjusted ≤1 time to avoid excessive Al leading to increased inclusions; S404 final deoxidation treatment: When the molten steel leaves the station, sprinkle 5-15kg of aluminum powder onto the slag surface to enhance deoxidation. It is strictly forbidden to add Ca or Ca alloy for deoxidation or to modify inclusions. S5 VD / RH Vacuum Treatment: S501 Argon blowing control: Total argon blowing time for VD furnace is 50-70 min, and for RH furnace it is 40-60 min; S502 vacuum treatment: vacuum degree ≤67Pa, vacuum holding time 15-25min; after breaking the vacuum, soft argon blowing in VD furnace for 15-35min, soft argon blowing in RH furnace for 15-30min, and settling time 10-25min to promote the floating of inclusions; S503 Temperature Control: The superheat of molten steel leaving the station is 18-38℃ for the initial casting furnace and 12-32℃ for the continuous casting furnace (liquid phase reference temperature 1450-1460℃). S504 Gas Control: At least one furnace sample is taken after each casting to test [H], and [H] is controlled to be ≤1.2-1.5ppm; an appropriate amount of heat-insulating agent is added to the ladle when it leaves the station; S6 continuous casting process: S601 Protective Casting: The entire casting process uses carbonized rice husks + special protective slag for high carbon steel to protect the molten steel from secondary oxidation. S602 crystallizer parameters: crystallizer water flow rate 3200-4000L / min, pulling speed 0.48-0.56m / min, specific water volume 0.16-0.20L / kg; crystallizer electromagnetic stirring current 220-280A, frequency 2.0-3.0Hz, end electromagnetic stirring current 320-380A, frequency 7.0-9.0Hz; S603 reduction control: The designed reduction is 22-28mm, which improves the center segregation of the billet through heavy reduction; S604 billet processing: Slow cooling time for billets ≥ 48-72h, hot billet insulation is preferred for the bottom and top layers; billets with liquid level fluctuations in the crystallizer exceeding ±4-6mm are rejected. S7 Process Inspection and Control: S701 Composition Analysis: Samples were taken and tested at the LF outlet, VD / RH outlet, and billet stage for each heat, controlling Ti ≤ 0.0010%-0.0015% and O ≤ 0.0005%-0.00065%. S702 billet quality inspection: For each casting, samples covering all flows are taken for low magnification and segregation inspection. The segregation index is required to be ≤1.05-1.08, with no obvious central porosity or shrinkage defects. S703 Inclusion Control: Automatically analyzes and detects the quantity and size of inclusions to ensure that the proportion of inclusions with a size ≥10μm is ≤3%-5%, thus avoiding large particle inclusions from affecting the steel quality; Furthermore, this process achieves precise control over Ti / O content, meeting the core requirements of premium grade products: through strict screening of low-Ti molten iron and selection of low-Ti auxiliary materials in raw material pretreatment, combined with LF refining to remove Ti-rich slag and VD / RH vacuum-enhanced deoxidation, the introduction and return of Ti elements are effectively avoided, and the Ti content is stably controlled at 0.0010%-0.0015%, and the O content is precisely locked at 0.0005%-0.00065%, far exceeding the industry standard for premium grade products. The Ti / O hit rate is increased to over 100% and 80% respectively, solving the pain point of large fluctuations in Ti / O content in traditional processes. Furthermore, this process significantly improves steel purity and effectively controls inclusions: KR deep desulphurization shortens refining time and reduces inclusion formation; LF refining rapidly forms slag, and the synergistic effect of argon stirring, combined with VD / RH vacuum settling, promotes inclusion flotation, resulting in a significant reduction in the number of inclusions, with the proportion of inclusions ≥10μm controlled within 3%-5%, significantly reducing magnesium aluminum spinel and calcium aluminate composite inclusions, and lowering the incidence of black spots and cracking in bearing rings. Furthermore, this process optimizes the internal structure uniformity and effectively improves carbon segregation: the continuous casting process adopts precise speed control (0.48-0.56m / min), electromagnetic stirring and 22-28mm heavy pressure, the billet segregation index is controlled within 1.05-1.08, and the carbon range is reduced to 0.01-0.06%, avoiding the problems of central porosity and excessive carbide banding in traditional processes, and ensuring uniform mechanical properties of steel; Furthermore, this process significantly reduces surface defects and improves quality stability: by controlling slag removal during steel tapping in the converter, strictly controlling liquid level fluctuations in the continuous casting crystallizer (±4-6mm for rejection), and slow cooling treatment of the billet, surface defects such as folds, cracks, and scabs are effectively reduced, the pass rate of magnetic flux leakage testing is increased to over 98%, and the risk of customer complaints regarding external peeling of pipes and spontaneous breakage of wire rods is reduced. The product quality stability is significantly better than that of traditional processes. Furthermore, this process has enabled it to adapt to the demands of the high-end market and enhance its competitiveness: the premium GCr15 steel produced by this process fully matches the high-end application scenarios of automotive wheel bearings and precision mechanical bearings in terms of purity, microstructure uniformity and surface quality. It can meet the technical requirements of high-end customers such as SKF and Schaeffler, break through the technical barriers of mainstream competitors, and increase the product's market share in the high-end bearing steel market.

[0021] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen, comprising: S1 raw material pretreatment, S2 KR deep desulfurization treatment, S3 converter smelting, S4 LF refining, S5 VD / RH vacuum treatment, S6 continuous casting process, and S7 process inspection and control, characterized in that: The S1 raw material pretreatment includes S101 control of molten iron entering the furnace and S102 selection of auxiliary materials; Among them, S4 LF refining includes S401 slag removal, S402 argon blowing deoxidation, S403 composition fine-tuning and S404 final deoxidation treatment. Among them, the S5 VD / RH vacuum treatment includes S501 argon blowing control, S502 vacuum treatment, S503 temperature control and S504 gas control; The S6 continuous casting process includes S601 protective casting, S602 crystallizer parameters, S603 reduction control and S604 billet treatment. Among them, S7 process inspection and control includes S701 composition detection, S702 billet quality inspection and S703 inclusion control.

2. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S101 molten iron feed temperature is controlled as follows: [S]≤0.045%-0.055%, [P]≤0.140%-0.160%, Ti≤0.05%-0.07%. Low-Ti molten iron raw materials are strictly selected to avoid introducing excessive Ti elements.

3. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S102 auxiliary materials are selected as follows: low-Ti alloy (low-carbon ferrochrome, low-aluminum low-titanium ferrosilicon, metallic manganese), low-titanium low-boron pre-melted slag, and diversion sand with excellent diversion effect; steel tanks that have been smelted with Ti-containing steel grades are prohibited from use. Before use, the slag on the edge of the tank should be thoroughly cleaned. Reusable tanks or special steel tanks should be given priority.

4. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S2 KR deep desulfurization treatment: Desulfurization target: Control the [S] content of molten steel to ≤0.002%-0.003%, reduce the desulfurization load of subsequent LF refining, shorten the refining time, and reduce the risk of Ti element return during the refining process; Processing parameters: The stirring power should be adapted to the tonnage of molten steel, and the stirring time should be 30-45 minutes to ensure that the desulfurizing agent and molten steel are in full contact and react.

5. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S3 converter smelting: End-point control of tapping: End-point [C] 0.08%-0.12%, to avoid over-oxidation of molten steel, which would increase the difficulty of subsequent deoxidation; Slag blocking during steel tapping: Mechanical slag blocking combined with slag-blocking agent is used to assist in slag blocking. Slag feeding is strictly prohibited to prevent harmful impurities from being introduced into the furnace. Alloy addition: When 1 / 4 of the steel is tapped, a pre-set low-Ti alloy and slag are added along the steel flow. The target composition of the steel entering the station is: [C] 0.82%-0.98%, [Mn] 0.22%-0.38%, [Cr] 1.32%-1.48%.

6. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S401 slag removal and slag retrieval: After entering the station, slag removal / slag retrieval operations are performed first to remove Ti-rich slag from the surface of the molten steel and reduce the Ti content of the molten steel; S402 Argon blowing deoxidation: Total argon blowing time is 40-60 min. Al particles are used for diffusion deoxidation, combined with low Ti synthesis slag for rapid slag formation, deoxidation, and desulfurization. The slag formation time is controlled at 20-30 min. S403 composition fine-tuning: The composition is precisely adjusted according to the target value, with key control of [Cr] 1.40%-1.65%, [C] at the station 0.94%-1.00%, and carbon difference between the upper and lower furnaces ≤0.04%; Al content is adjusted ≤1 time to avoid excessive Al leading to increased inclusions; S404 final deoxidation treatment: When molten steel leaves the station, sprinkle 5-15 kg of aluminum powder onto the slag surface to enhance deoxidation. It is strictly forbidden to add Ca or Ca alloy for deoxidation or to modify inclusions.

7. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S501 argon blowing control is as follows: total argon blowing time for VD furnace is 50-70 min, and total argon blowing time for RH furnace is 40-60 min; S502 vacuum treatment: vacuum degree ≤67Pa, vacuum holding time 15-25min; after breaking the vacuum, soft argon blowing in VD furnace for 15-35min, soft argon blowing in RH furnace for 15-30min, and settling time 10-25min to promote the floating of inclusions; S503 Temperature Control: The superheat of molten steel leaving the station is 18-38℃ for the initial casting furnace and 12-32℃ for the continuous casting furnace (liquid phase reference temperature 1450-1460℃). S504 Gas Control: At least one furnace sample is taken for testing [H] after each casting, and [H] is controlled to be ≤1.2-1.5ppm; an appropriate amount of heat-insulating agent is added to the ladle when it leaves the station.

8. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S601 protective casting process uses carbonized rice husks and high-carbon steel special protective slag throughout to prevent secondary oxidation of the molten steel. S602 crystallizer parameters: crystallizer water flow rate 3200-4000L / min, pulling speed 0.48-0.56m / min, specific water volume 0.16-0.20L / kg; crystallizer electromagnetic stirring current 220-280A, frequency 2.0-3.0Hz, end electromagnetic stirring current 320-380A, frequency 7.0-9.0Hz; S603 reduction control: The designed reduction amount is 22-28mm, which improves the center segregation of the billet through heavy reduction; S604 billet processing: Slow cooling time for billets ≥ 48-72h, hot billet insulation is preferred for the bottom and top layers; billets with liquid level fluctuations in the crystallizer exceeding ±4-6mm are rejected.

9. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S701 composition test: Samples were taken and tested at the LF outlet, VD / RH outlet, and billet stage for each heat, and Ti was controlled to be ≤0.0010%-0.0015%, and O was controlled to be ≤0.0005%-0.00065%. S702 billet quality inspection: For each casting, samples covering all flows are taken for low magnification and segregation inspection. The segregation index is required to be ≤1.05-1.08, with no obvious central porosity or shrinkage defects.

10. The method for controlling the smelting of high-grade bearing steel with low titanium and low oxygen according to claim 1, characterized in that: The S703 inclusion control: By automatically analyzing and detecting the quantity and size of inclusions, it ensures that the proportion of inclusions with a size ≥10μm is ≤3%-5%, thus avoiding large-particle inclusions from affecting the steel quality.