Method for improving center segregation of super austenitic stainless steel plate blank

Abstract

The invention discloses a method for improving center segregation of a superaustenitic stainless steel slab, which specifically comprises the following steps of: proportioning raw materials for steelmaking according to a component proportion to obtain a mixture, and then sequentially carrying out EAF (Ethylene Aerated Filter) rough smelting, liquid discharging and slagging-off, pre-desulfurization treatment, AOD (Argon Oxygen Decarburization) refining, LT secondary refining and continuous casting on the mixture to obtain a slab; and the plate blank is subjected to first-time pre-deformation hot rolling, second-time pre-deformation hot rolling, rough rolling, finish rolling, annealing and acid pickling, and then the super austenite steel coil is obtained. By the adoption of the method, the segregation problem of the super austenite solidification structure can be effectively solved, and the problems of surface cracking and center layering of the plate blank in the hot rolling process are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, and particularly relates to a method for improving center segregation of super austenitic stainless steel slab. BACKGROUND

[0002] Super austenitic stainless steel is a special stainless steel containing high chromium, nickel, molybdenum and ultra-low carbon. Compared with traditional austenitic stainless steel, super austenitic stainless steel not only has extremely high corrosion resistance and crevice corrosion resistance, but also has good mechanical properties, processing properties and welding properties, and is widely used in extremely harsh environments such as paper bleaching, seawater desalination, flue gas desulfurization and chemical waste treatment.

[0003] However, due to the extremely high alloy content in super austenitic stainless steel, the solubility and diffusion speed of alloy elements in solid and liquid phases are different, and the alloy elements are easily redistributed between solid and liquid phases, so the alloy elements are easily segregated in front of the solidification interface. Ultimately, the element segregation in the center position of the continuous casting slab during the solidification process is very serious (especially Mo segregation), and a large amount of hard and brittle intermetallic phases such as sigma phase are precipitated in the Mo-rich interdendritic region. Severe segregation and precipitation can significantly reduce the microstructure uniformity and composition uniformity of super austenitic stainless steel, sharply deteriorate the hot working properties, and cause the super austenitic stainless steel to crack easily during hot rolling, especially the delamination phenomenon occurs in the center position of the slab during the initial rolling stage, as shown in FIG. 1. Figure 1 Therefore, it is very important to explore a method for improving the solidification structure, reducing element segregation and precipitation in order to ensure the high quality and stable production of super austenitic stainless steel.

[0004] Some methods for improving the center segregation of super austenitic stainless steel slab currently appearing in China, such as solidification stage electromagnetic stirring, steel strip insertion into the crystallizer, molten steel gas atomization and powder metallurgy, cannot stably, reliably and low-costly solve the segregation problem. Therefore, it is urgent to develop a method for stably and reliably inhibiting the formation of precipitated phases in super austenitic stainless steel and low-costly improving the center segregation of super austenitic stainless steel slab. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a method for stably, reliably and low-costly improving the center segregation of super austenitic stainless steel slab, which can effectively improve the segregation problem of super austenitic solidification structure and eliminate the surface cracking and center delamination problems of the slab during hot rolling.

[0006] Super austenitic stainless steel contains extremely high levels of chromium, nickel, and molybdenum alloying elements. During the solidification process of continuously cast slabs, the alloying elements segregate severely in the center of the slab, and a large amount of hard and brittle intergranular phases such as the σ phase precipitate in the Mo-rich interdendritic regions, seriously deteriorating hot workability and making the slab extremely prone to cracking during hot rolling. Especially in the early stages of rolling, delamination can occur in the center of the slab. Figure 1 As shown.

[0007] To solve the above problems, the technical solution adopted by the present invention is: a method for improving center segregation of super austenitic stainless steel slabs, the steps of which are: EAF→AOD→LT→CCP→HSM→HAP. Specifically, the raw materials for steelmaking are first batched according to the component ratio to obtain a mixture. Then, the mixture is subjected to EAF roughing, slag removal, pre-desulfurization treatment, AOD refining, LT secondary refining, and continuous casting to obtain a slab. The slab is then subjected to a first pre-deformation hot rolling, a second pre-deformation hot rolling, rough rolling, finish rolling, annealing, and pickling to obtain a super austenitic steel coil.

[0008] Furthermore, in the aforementioned method for improving center segregation of super austenitic stainless steel slabs, after EAF roughing and slag removal, the content of carbon, silicon, chromium, nickel, and phosphorus in the molten steel from the electric furnace needs to be controlled within the following ranges: carbon > 2.0%, silicon ≤ 1.0%, chromium 20%–25%, nickel 18%–23%, phosphorus < 0.025%, with the remainder mainly consisting of iron.

[0009] Furthermore, in the aforementioned method for improving center segregation in super austenitic stainless steel slabs, the pre-desulfurization treatment step is as follows: First, lime, reducing agent, and fluorite are added to the molten steel after slag removal. The amount of lime added is 10-15 kg / ton of steel, the amount of reducing agent is ferrosilicon reducing agent or silicon carbide reducing agent, and the amount of reducing agent added is 3-5 kg / ton of steel, and the amount of fluorite added is 3-5 kg / ton of steel; then, pre-desulfurization treatment is carried out by bottom-blowing argon stirring for 15-30 minutes at an argon flow rate of 5 m³ / ton. 3 / min; After the pre-desulfurization treatment, the newly generated slag is removed. After the pre-desulfurization treatment, the sulfur content in the molten steel is ≤0.05%, which can effectively reduce the desulfurization load of subsequent AOD refining and also ensure the purity of the molten steel.

[0010] Furthermore, in the aforementioned method for improving center segregation in super austenitic stainless steel slabs, the basicity of the AOD refining slag is controlled at 1.8–2.0; the tapping temperature is controlled at 1560–1620℃; and the composition of the qualified molten steel obtained from AOD refining includes: carbon <0.02%, silicon 0.4%–0.7%, manganese 0.2%–0.6%, phosphorus <0.03%, sulfur <0.01%, chromium 20%–21%, nickel 18.0%–18.5%, molybdenum 6.0%–6.5%, copper 0.6%–0.8%, and nitrogen 0.20%–0.24%.

[0011] Furthermore, in the aforementioned method for improving center segregation of super austenitic stainless steel slabs, the qualified molten steel obtained from AOD refining is tapped to a casting ladle, and the casting ladle is sent to the LT slag removal station for secondary refining; after the LT secondary refining, the harmful trace elements sulfur, oxygen, lead, and tin in the molten steel are controlled within the following ranges: sulfur ≤ 10 ppm, oxygen ≤ 20 ppm, lead ≤ 20 ppm, and tin ≤ 50 ppm.

[0012] This solution effectively controls the content of harmful elements S, O, Pb, and Sn by controlling the components of the EAF crude refining liquor, the AOD refined liquor, and the LT secondary refining liquor, thereby effectively preventing the formation of brittle compounds.

[0013] Furthermore, in the aforementioned method for improving center segregation of super austenitic stainless steel slabs, the continuous casting process is as follows: molten steel is poured into the continuous casting tundish, and then distributed to the crystallizer from the tundish nozzle. After solidification in the crystallizer, the slab is continuously pulled out from the outlet below the crystallizer, and obtained after spray cooling, cutting, and rapid water cooling.

[0014] Key management aspects of continuous casting include: EMS electromagnetic stirring, tundish temperature, casting speed, crystallizer cooling water temperature and flow rate, hot billet spray cooling water temperature and specific water flow rate, continuous casting roll gap size, and rapid water cooling of the hot billet. Specific parameters are as follows: The casting speed of the continuous casting is ≥1.10m / min. A higher casting speed can increase the length of the liquid core of the slab in continuous casting, which is beneficial for controlling the thickness of the slab under pressure.

[0015] The temperature inside the continuous casting tundish is 1430–1445℃; the cooling water temperature in the crystallizer is 33–36℃; the water flow rate on the wide side of the crystallizer is 3300–3500 L / min; the water flow rate on the narrow side of the crystallizer is 450–550 L / min; the vibration frequency of the crystallizer is 150 times / min; and the amplitude of the crystallizer is 4.0 mm.

[0016] The crystallizer employs an EMS electromagnetic stirrer, which is installed below the crystallizer. The current of the EMS electromagnetic stirrer is 1000–1200 A. Electromagnetic stirring creates a magnetic field in the molten steel during casting, forcibly stirring the molten steel stream using electromagnetic force, improving the solidification process and resulting in a high-quality casting structure. The casting stream, situated in a changing magnetic field, forms eddies in the fixed molten steel. The interaction between the eddies and the magnetic field generates force, forcing the molten steel to flow. This forced flow of molten steel, passing through the solidification interface, creates a scouring effect, cutting off dendrites growing between the contact surfaces. These cut-off dendrite tips re-enter the molten steel and interact with it, melting and decomposing. Furthermore, this reduces temperature differences and promotes the formation of equiaxed crystals.

[0017] The thickness of the slab obtained after continuous casting is 200mm. The continuous casting roll gap control mechanism eliminates the dynamic light pressure control method and replaces it with a fixed roll gap method. The fixed roll gap control roll gap distance is 202mm, and the continuous drawing speed from the outlet below the crystallizer is ≥1.1m / min. EMS electromagnetic stirring breaks up the dendrites generated by segregation. Combined with the high casting speed and the fixed roll gap forced pressure on the slab, it can effectively promote the center healing of the continuously cast slab and suppress the center segregation of the continuously cast slab.

[0018] The temperature of the spray cooling water used for continuously pulling out the billet shell from the outlet below the crystallizer is 34-37℃, and the specific water flow rate is 0.40-0.45L / (ton·min). The rapid water cooling involves immersing the cut billet shell in a water cooling pool for cooling for ≥30min to ensure that the hot billet quickly passes the σ phase precipitation temperature (500-900℃). The water in the water cooling pool is natural water with a temperature ≤40℃.

[0019] Key aspects of the hot rolling process: the slab undergoes two pre-deformation processes followed by hot rolling, rough rolling, and finish rolling. Specifically: The steps of the first pre-deformation hot rolling are as follows: the slab is heated for the first time in a heating furnace at a temperature of 1250-1270℃ for 200-240 minutes; then the heated slab is rolled for the first time in two passes, with a reduction of 15±1mm in each pass; the thickness of the slab after rolling is 200mm→170mm.

[0020] The steps of the second pre-deformation hot rolling are as follows: the slab is heated for the second time in a heating furnace at a temperature of 1250-1270℃ for 200-240 minutes; then the heated slab is rolled for the second time in two passes, with a reduction of 15±1mm in each pass; the thickness of the slab after rolling is 170mm→140mm.

[0021] The rough rolling process involves 5 to 7 rolling passes, with the same reduction amount in each pass, ultimately reducing the slab thickness to 23 to 28 mm.

[0022] The finishing rolling process involves 5 to 7 rolling passes, with the same reduction amount in each pass, ultimately rolling the slab to the target thickness. A reversible hot roll mill can be used for this finishing process.

[0023] The black coil obtained after precision rolling is annealed and pickled to obtain a super austenitic white coil product.

[0024] The beneficial effects of this invention are: ① By controlling the composition of the EAF roughing broth, the AOD refining broth, and the LT secondary refining broth, the content of harmful elements S, O, Pb, and Sn is effectively controlled, thereby effectively avoiding the formation of brittle compounds; ② The continuous casting process is optimized by using EMS electromagnetic stirring + high casting speed + fixed roll gap + rapid cooling of hot billets to maximize the elimination of brittle σ phase precipitation and slab center segregation; ③ The secondary pre-rolling process of hot-rolled reheated materials, by reheating and pre-deforming the continuously cast slab by 200mm→170mm→140mm, effectively promotes the remelting of precipitated phases, improves the high-temperature plasticity of hot rolling, and improves slab center segregation; ④ The improved processes of this invention do not require new equipment investment, have high feasibility, and increase production costs by little. The improvement effect on the center segregation and stratification problem of super austenitic slabs is significant and stable. Attached Figure Description

[0025] Figure 1 This is a picture of a super austenitic steel coil obtained using traditional steelmaking methods.

[0026] Figure 2 This is a photograph of a super austenitic steel coil obtained using the method described in this invention for improving center segregation in super austenitic stainless steel slabs. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0028] The method for improving center segregation of super austenitic stainless steel slabs described in this embodiment includes the following steps: First, steelmaking raw materials are batched according to the component ratio to obtain a mixture. Then, the mixture is subjected to EAF roughing, slag removal, pre-desulfurization treatment, AOD refining, LT secondary refining, and continuous casting to obtain a slab. The slab is then subjected to a first pre-deformation hot rolling, a second pre-deformation hot rolling, rough rolling, finish rolling, annealing, and pickling to obtain a super austenitic steel coil.

[0029] The EAF crude refining process is the same as the traditional EAF crude refining process, except for the control of the following parameters: In this embodiment, during the EAF crude refining process, after the EAF crude refining is completed and the broth is skimmed off, it is necessary to ensure that the C, Si, Cr, Ni, and P contents in the broth from the electric furnace are controlled within the following ranges: C > 2.0%, Si ≤ 1.0%, Cr 20% to 25%, Ni 18% to 23%, P < 0.025%, and the remaining balance is mainly Fe.

[0030] In traditional methods, after EAF roughing and slag removal, the steel is directly fed into an AOD furnace for refining. However, this method has a drawback: the sulfur content in the molten steel after EAF slag removal is generally above 1000 ppm. Directly refining in an AOD furnace would place too much stress on desulfurization, requiring a large amount of lime. However, excessive lime input would negatively impact the purity of the molten steel. This embodiment adds a pre-desulfurization step after slag removal. The pre-desulfurization step is as follows: First, lime, reducing agent, and fluorite are added to the molten steel after slag removal. The lime input is 10-15 kg / ton of steel, the reducing agent is either ferrosilicon or silicon carbide reducing agent, and the input is 3-5 kg / ton of steel. The fluorite input is also 3-5 kg / ton of steel. Then, pre-desulfurization is performed by bottom-blowing argon agitation for 15-30 minutes at a flow rate of 5 m³ / ton. 3 / min; After the pre-desulfurization treatment, the newly generated slag is removed. After the pre-desulfurization treatment, the sulfur content in the molten steel is ≤0.05%, which can effectively reduce the desulfurization load of subsequent AOD refining and also ensure the purity of the molten steel.

[0031] The AOD refining process is consistent with the traditional AOD refining process, with the difference being the control of the following parameters: In this embodiment, the basicity of the AOD refining slag is controlled at 1.8–2.0; the tapping temperature is controlled at 1560–1620℃; the composition of the qualified molten steel obtained from AOD refining includes: C < 0.02%, Si 0.4%–0.7%, Mn 0.2%–0.6%, P < 0.03%, S < 0.01%, Cr 20%–21%, Ni 18.0%–18.5%, Mo 6.0%–6.5%, Cu 0.6%–0.8%, and N 0.20%–0.24%. The remaining balance is mainly Fe, with trace elements such as Pn and Sn also present.

[0032] The qualified molten steel obtained from AOD refining is tapped to a casting ladle, which is then sent to the LT slag removal station for secondary refining. The LT secondary refining process is the same as the traditional LT secondary refining process, except for the control of the following parameters: After LT secondary refining, the harmful trace elements S, O, Pb, and Sn in the molten steel are controlled within the following ranges: S≤10ppm, O≤20ppm, Pb≤20ppm, Sn≤50ppm.

[0033] By controlling the composition of the EAF crude refining liquor, the AOD refined liquor, and the LT secondary refining liquor, the content of harmful elements S, O, Pb, and Sn can be effectively controlled, thereby effectively preventing the formation of brittle compounds.

[0034] The continuous casting process described in this embodiment is as follows: molten steel is poured into the continuous casting tundish, and then distributed to the crystallizer from the tundish nozzle. After solidification in the crystallizer, the slab is continuously pulled out from the outlet below the crystallizer, and after spray cooling, cutting, and rapid water cooling, a slab is obtained.

[0035] Key management aspects of continuous casting include: EMS electromagnetic stirring, tundish temperature, casting speed, crystallizer cooling water temperature and flow rate, hot billet spray cooling water temperature and specific water flow rate, continuous casting roll gap size, and rapid water cooling of the hot billet. This embodiment optimizes the continuous casting process by using EMS electromagnetic stirring + high casting speed + fixed roll gap + rapid cooling of the hot billet, combined with the control of various parameters, to maximize the elimination of brittle σ-phase precipitation and slab center segregation. Specific parameters are as follows: The casting speed of the continuous casting is ≥1.10m / min. A higher casting speed can increase the length of the liquid core of the slab in continuous casting, which is beneficial for controlling the thickness of the slab under pressure.

[0036] The temperature inside the continuous casting tundish is 1430–1445℃; the cooling water temperature in the crystallizer is 33–36℃; the water flow rate on the wide side of the crystallizer is 3300–3500 L / min; the water flow rate on the narrow side of the crystallizer is 450–550 L / min; the vibration frequency of the crystallizer is 150 times / min; and the amplitude of the crystallizer is 4.0 mm.

[0037] The crystallizer employs an EMS electromagnetic stirrer, which is installed below the crystallizer. The current of the EMS electromagnetic stirrer is 1000-1200A. The electromagnetic stirrer creates a magnetic field in the molten steel during casting, forcibly stirring the molten steel stream using electromagnetic force, thus improving the solidification process and resulting in a high-quality casting structure. The casting stream, situated in a changing magnetic field, forms eddies in the fixed molten steel. The interaction between the eddies and the magnetic field generates force, forcing the molten steel to flow. This forced flow of molten steel, passing through the solidification interface, creates a scouring effect, cutting off dendrites growing between the contact surfaces. These cut-off dendrite tips re-enter the molten steel and interact with it, melting and decomposing. Furthermore, this reduces temperature differences and promotes the formation of equiaxed crystals.

[0038] The thickness of the slab obtained after continuous casting is 200mm. The continuous casting roll gap control mechanism eliminates the dynamic light pressure control method and adopts a fixed roll gap method. The fixed roll gap control roll gap distance is 202mm, and the continuous drawing speed from the outlet below the crystallizer is ≥1.1m / min. EMS electromagnetic stirring breaks up the dendrites generated by segregation. Combined with the high casting speed and the fixed roll gap forced pressure on the slab, it can effectively promote the center healing of the continuously cast slab and suppress the center segregation of the continuously cast slab.

[0039] The temperature of the spray cooling water used for continuously pulling out the billet shell from the outlet below the crystallizer is 34-37℃, and the specific water flow rate is 0.40-0.45L / (ton·min). The rapid water cooling involves immersing the cut billet shell in a water cooling pool for cooling for ≥30min to ensure that the hot billet quickly passes the σ phase precipitation temperature (500-900℃). The water in the water cooling pool is natural water with a temperature ≤40℃.

[0040] Key aspects of the hot rolling process: slab pre-deformation twice followed by hot rolling, rough rolling, and finish rolling. Specifically, the first pre-deformation hot rolling step is as follows: the slab is first heated in a furnace at a temperature of 1250–1270℃ for 200–240 minutes; then, the heated slab is rolled for the first time in two passes, with a reduction of 15±1mm per pass; the slab thickness after rolling is 200mm→170mm.

[0041] The steps of the second pre-deformation hot rolling are as follows: the slab is heated for the second time in a heating furnace at a temperature of 1250-1270℃ for 200-240 minutes; then the heated slab is rolled for the second time in two passes, with a reduction of 15±1mm in each pass; the thickness of the slab after rolling is 170mm→140mm.

[0042] The rough rolling process involves 5 to 7 rolling passes, with the same reduction amount in each pass, ultimately reducing the slab thickness to 23 to 28 mm.

[0043] The finishing rolling process involves 5 to 7 rolling passes, with the same reduction amount in each pass, ultimately rolling the slab to the target thickness, typically 3 to 5 mm. The finishing rolling of the slab can be performed using a reversible hot roll mill.

[0044] The secondary pre-rolling process for hot-rolled reheated materials effectively promotes the remelting of precipitated phases, improves the high-temperature plasticity of hot-rolled materials, and reduces center segregation of slabs by reheating and pre-deforming the continuously cast slab by 200mm→170mm→140mm.

[0045] The black coil obtained after precision rolling is annealed and pickled to obtain a super austenitic white coil product, such as...Figure 2 As shown, compared with the original method, the improved method does not require additional new equipment, thus the equipment investment cost is zero. The overall feasibility of the solution is high, the additional production cost is small, and the improvement effect on the segregation and delamination problem in the center of the super austenitic slab is significant and stable.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A method for improving center segregation in super austenitic stainless steel slabs, characterized in that: The raw materials for steelmaking are batched according to the composition ratio to obtain a mixture. The mixture is then subjected to EAF roughing, slag removal, pre-desulfurization treatment, AOD refining, LT secondary refining, and continuous casting to obtain a slab. The slab is then subjected to a first pre-deformation hot rolling, a second pre-deformation hot rolling, rough rolling, finish rolling, annealing and pickling to obtain a super austenitic steel coil.

2. The method for improving center segregation in super austenitic stainless steel slabs according to claim 1, characterized in that: After EAF crude refining, the carbon, silicon, chromium, nickel, and phosphorus content in the broth from the electric furnace is controlled within the following ranges: carbon > 2.0%, silicon ≤ 1.0%, chromium 20%–25%, nickel 18%–23%, and phosphorus < 0.025%.

3. A method for improving center segregation in super austenitic stainless steel slabs according to claim 1 or 2, characterized in that: The pre-desulfurization treatment steps are as follows: First, lime, reducing agent, and fluorite are added to the molten steel after slag removal. The amount of lime added is 10-15 kg / ton of steel. The reducing agent is either ferrosilicon reducing agent or silicon carbide reducing agent, and the amount of reducing agent added is 3-5 kg / ton of steel. The amount of fluorite added is also 3-5 kg / ton of steel. Then, pre-desulfurization treatment is carried out by bottom-blowing argon gas stirring for 15-30 minutes at a flow rate of 5 m³ / ton. 3 / min; After the pre-desulfurization treatment is completed, the newly generated slag is removed.

4. The method for improving center segregation in super austenitic stainless steel slabs according to claim 3, characterized in that: The basicity of AOD refining slag is controlled at 1.8–2.0; the tapping temperature is controlled at 1560–1620℃; the composition of qualified molten steel obtained by AOD refining includes: carbon <0.02%, silicon 0.4%–0.7%, manganese 0.2%–0.6%, phosphorus <0.03%, sulfur <0.01%, chromium 20%–21%, nickel 18.0%–18.5%, molybdenum 6.0%–6.5%, copper 0.6%–0.8%, and nitrogen 0.20%–0.24%.

5. The method for improving center segregation in super austenitic stainless steel slabs according to claim 4, characterized in that: The qualified molten steel obtained from AOD refining is tapped into the casting ladle, and the casting ladle is sent to the LT slag removal station for secondary refining. After secondary refining, the harmful trace elements sulfur, oxygen, lead, and tin in the molten steel are controlled within the following ranges: sulfur ≤ 10 ppm, oxygen ≤ 20 ppm, lead ≤ 20 ppm, and tin ≤ 50 ppm.

6. The method for improving center segregation in super austenitic stainless steel slabs according to claim 1, characterized in that: The continuous casting process is as follows: molten steel is poured into the continuous casting tundish, and then distributed to the crystallizer through the tundish nozzle. After solidification in the crystallizer, the slab is continuously pulled out from the outlet below the crystallizer, and after spray cooling, cutting, and rapid water cooling, a slab is obtained.

7. The method for improving center segregation in super austenitic stainless steel slabs according to claim 6, characterized in that: The casting speed of the continuous casting is ≥1.10m / min; the temperature inside the continuous casting tundish is 1430~1445℃; The cooling water temperature in the crystallizer is 33-36℃, the water flow rate on the wide side of the crystallizer is 3300-3500 L / min, the water flow rate on the narrow side of the crystallizer is 450-550 L / min, the vibration frequency of the crystallizer is 150 times / min, and the amplitude of the crystallizer is 4.0 mm. The crystallizer uses EMS electromagnetic stirring, and the current of the EMS electromagnetic stirring is 1000-1200A. The continuous casting roll gap at the outlet below the crystallizer adopts a fixed roll gap method; the continuous drawing speed from the outlet below the crystallizer is ≥1.1m / min; The temperature of the spray cooling water used to continuously cool the billet shells pulled out from the outlet below the crystallizer is 34-37℃, and the specific water flow rate is 0.40-0.45L / (ton·min). The rapid water cooling involves immersing the cut billet in a water cooling tank for cooling, with a cooling time of ≥30 minutes. The water in the water cooling tank is natural water with a temperature of ≤40℃.

8. The method for improving center segregation in super austenitic stainless steel slabs according to claim 7, characterized in that: When using the fixed roll gap method, the roll gap distance is 202mm, and the thickness of the slab obtained after continuous casting is 200mm.

9. The method for improving center segregation in super austenitic stainless steel slabs according to claim 1, characterized in that: The steps of the first pre-deformation hot rolling are as follows: the slab is heated for the first time in a heating furnace at a temperature of 1250-1270℃ for 200-240 minutes; then the heated slab is rolled for the first time in two passes, with a reduction of 15±1mm in each pass. The steps of the second pre-deformation hot rolling are as follows: the slab is heated for the second time in a heating furnace at a temperature of 1250-1270℃ for 200-240 minutes; then the heated slab is rolled for the second time in two passes, with a reduction of 15±1mm in each pass. The rough rolling process involves 5 to 7 rolling passes, with the same reduction amount in each pass, ultimately reducing the thickness of the slab to 23 to 28 mm. The finishing rolling process involves 5 to 7 rolling passes, with the same reduction amount in each pass, ultimately rolling the slab to the target thickness.

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