High-nickel stainless steel cold-rolled sheet and preparation process thereof

Abstract

The invention relates to the technical field of high-nickel stainless steel, in particular to a high-nickel stainless steel cold-rolled sheet and a preparation process thereof. Comprising the following steps that 1, a 316L stainless steel plate is heated to 1500-1550 DEG C in a nitrogen environment, molten steel is formed, TiN nanoparticles are added to serve as a modifier, and smelting continues to be conducted for 20-30 min; casting, hot rolling and solid solution are performed to obtain a basic thin plate; 2, the basic thin plate is subjected to acid pickling, asynchronous cold rolling and annealing, and a cold-rolled basic thin plate A is obtained; 3, the cold-rolled base sheet A is subjected to low-temperature nitriding, and a nitriding layer is formed; follow-up cold flattening, cutting and coil dividing are carried out; therefore, the high-nickel stainless steel cold-rolled sheet is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of high-nickel stainless steel, in particular to a high-nickel stainless steel cold-rolled sheet and a preparation process thereof. Background Art

[0002] High nickel stainless steel cold rolled sheets are widely used in chemical industry, aerospace and other fields due to their excellent high temperature resistance. However, in the actual preparation process, the following problems still exist, which directly affect their mechanical properties and corrosion resistance: First, in the traditional preparation process, σ phase and δ ferrite are easily precipitated during hot rolling and solution treatment, which not only directly reduces the plasticity and toughness of the material, but also aggravates composition segregation and induces cracks. At the same time, since no modifier is added in the process, the heterogeneous nucleation of δ ferrite cannot be controlled, resulting in coarse δ ferrite grains. This coarse δ ferrite is enriched with Cr and Mo elements, which will preferentially transform into σ phase during the aging process, further aggravating the generation of hot cracks, leading to a continuous decrease in plasticity and toughness, and a decline in mechanical properties and corrosion resistance.

[0003] Secondly, traditional hot rolling and solutionizing processes form a hard oxide scale on the material surface, which cannot be removed evenly and completely by mechanical treatments such as sandblasting and grinding. Therefore, direct strong acid pickling is often used to remove the surface oxide layer. However, this removal process generates excess hydrogen, causing some hydrogen atoms to penetrate into the material, further causing hydrogen embrittlement and degrading mechanical properties and corrosion resistance. Furthermore, the single corrosion inhibitor typically used decomposes easily in strong oxidizing acids, failing to form an effective protective film and leading to excessive surface corrosion.

[0004] Third, in traditional preparation processes, synchronous rolling is mostly used. On the one hand, the material deformation resistance increases sharply during the rolling process, causing high rolling force to lead to dislocation pileup, forming hydrogen diffusion channels under stress concentration, causing hydrogen embrittlement and edge cracking; on the other hand, synchronous rolling will lead to uneven deformation of the surface and the interior, and a large difference in grain size, which will affect the mechanical properties and corrosion resistance.

[0005] In summary, it is of great significance to solve the above problems and prepare a high-nickel stainless steel cold-rolled sheet. Summary of the Invention

[0006] The object of the present invention is to provide a high nickel stainless steel cold rolled sheet and a preparation process thereof, so as to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: A process for preparing a high-nickel stainless steel cold-rolled sheet comprises the following steps: Step 1: Heat the 316L stainless steel plate to 1500-1550°C in a nitrogen environment to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 20-30 minutes; then cast, hot roll, and solid solution to obtain a base thin plate; Step 2: pickling, asynchronous cold rolling, and annealing the base sheet to obtain a cold-rolled base sheet A; Step 3: Low-temperature nitriding is performed on the cold-rolled base sheet A to form a nitrided layer; and then cold flattening, cutting and coiling are performed to obtain a high-nickel stainless steel cold-rolled sheet.

[0008] More optimally, the chemical composition of the 316L stainless steel plate, calculated by mass percentage, includes: 0.5% to 1.0% silicon, 1.5% to 2% manganese, 13.8% to 14.6% nickel, 16.5% to 18.5% chromium, 2.2% to 2.4% molybdenum, nitrogen ≤0.08%, carbon ≤0.015%, and the rest is iron and unavoidable impurities; the amount of the TiN nanoparticles introduced accounts for 0.5wt% to 1wt% of the mass of the 316L stainless steel plate.

[0009] More optimally, the asynchronous cold rolling adopts staged cold rolling; specifically, after cold rolling for 2 passes at a rolling reduction rate of 25-35%, intermediate annealing at 1050-1100°C for 15-30 minutes, and then cold rolling for 1 pass at a rolling reduction rate of 20-25%.

[0010] More optimally, the asynchronous cold rolling adopts the TRR path; the process parameters are: rolling force of 1800~2500KN; upper roll and lower roll asynchronous ratio of 1.2~1.4:1; rolling temperature of 50~60℃.

[0011] More optimally, in step 2, the pickling process is as follows: placing the base sheet in a sulfuric acid solution, immersing it at 75-85°C for 1-2 minutes; transferring it to a mixed acid solution, at 65-75°C, setting the current density to 4-8A / dm 2 Electropolishing for 2-3 minutes, washing with water, and drying with nitrogen; The annealing process is as follows: annealing the asynchronously cold-rolled base sheet at 1050-1100° C. for 0.8-1.5 h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 8-10:1.

[0012] More optimally, the mixed acid is composed of the following components: 100-150 mg / L Mannich base, 80-130 mg / L sodium molybdate, 45-55 mg / L LBTA (benzotriazole), 95-105 g / L nitric acid, and 10-20 g / L hydrofluoric acid; The concentration of the sulfuric acid solution is 15wt%~20wt% sulfuric acid solution.

[0013] More optimally, the low-temperature nitriding process is: placing the cold-rolled base sheet A in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 2~4:1; setting the gas pressure to 180~220Pa and the temperature to 440~460℃ for low-temperature nitriding to form a nitriding layer.

[0014] More optimally, the thickness of the nitriding layer is 30-40 μm.

[0015] More optimally, in step 1, the casting working atmosphere is a nitrogen atmosphere, the casting temperature is 1400~1450℃, and the casting time is 1~2h; the hot rolling temperature is 1100~1150℃, and the holding time is 2~3h; the solution temperature is 1000~1050℃, and the solution time is 0.8~1.5h.

[0016] Compared with the prior art, the present invention has the following beneficial effects: First, the scheme introduces TiN nanoparticles as a modifier, combined with a low-temperature nitriding process, to synergistically improve plasticity and toughness, addressing issues such as composition segregation and thermal cracking. The TiN nanoparticles, as a modifier, refine the δ-ferrite through heterogeneous nucleation, reducing the segregation of Cr and Mo elements within the δ phase. Furthermore, by refining the δ phase size and increasing the phase interface, the TiN nanoparticles inhibit the transformation of δ-ferrite into the σ phase during aging, improving plasticity and toughness. The low-temperature nitriding process forms a solid-solution nitrogen surface layer, expanding the austenite phase and inhibiting the transformation of deformed martensite into the δ phase, thereby improving plasticity and toughness and reducing cracking, further enhancing mechanical properties and corrosion resistance.

[0017] However, after hot rolling and solutionizing, oxides still form on the material surface, making electropolishing with strong oxidizing acids prone to hydrogen embrittlement. Therefore, the proposed solution utilizes a combined pickling method with a compound corrosion inhibitor, using Mannich base, sodium molybdate, and BTA to form a compound corrosion inhibitor to synergistically reduce hydrogen embrittlement. BTA preferentially adsorbs on active sites such as twin boundaries and dislocations, chelating with the base metal to form a dense film that blocks hydrogen permeation channels and further suppresses hydrogen embrittlement. Sodium molybdate effectively blocks hydrogen ions during the electropolishing process. Mannich base enhances hydrophobicity through long-chain amino groups, providing physical barriers that improve corrosion resistance.

[0018] However, the work hardening characteristics of high-nickel stainless steel itself cause a sharp increase in rolling force when using traditional synchronous cold rolling, which triggers stress concentration and forms hydrogen diffusion channels, resulting in hydrogen embrittlement and edge cracking. Therefore, in order to solve the above problems, asynchronous cold rolling is adopted in the scheme. Through staged rolling, the slip band density and dislocation entanglement are increased, the grains are refined, and the rolling force is reduced while avoiding martensitic phase transformation, stabilizing plasticity and further improving mechanical properties. DETAILED DESCRIPTION

[0019] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0020] It should be noted that the following parts are by mass, and all raw materials involved in the present invention are purchased from manufacturers without any special restrictions. Examples include: in the following examples, the CAS number of sodium molybdate is 7631-95-0; the CAS number of hydrofluoric acid is 7664-39-3; the CAS number of nitric acid is 7697-37-2; the CAS number of Mannich base is 81080-09-3; the CAS number of BTA is 95-14-7; the specification of TiN nanoparticles is 20 nm, the product number is AM-TiN-N-01, and they are purchased from Zhejiang Yamei Nano Technology Co., Ltd.

[0021] In the following embodiments, it is particularly noted that: (1) The mixed acid consists of the following components: 125 mg / L Mannich base, 110 mg / L sodium molybdate, 50 mg / L BTA, 100 g / L nitric acid, and 15 g / L hydrofluoric acid; (2) The concentration of the sulfuric acid solution is 18 wt% sulfuric acid solution.

[0022] Example 1: A process for preparing a high-nickel stainless steel cold-rolled sheet, comprising the following steps: Step 1: 316L stainless steel plate was heated to 1525°C in a nitrogen environment to form molten steel, TiN nanoparticles were added as a modifier, and smelting was continued for 25 minutes; casting was carried out at 1425°C for 1.5 hours under a nitrogen atmosphere; hot rolling was carried out at 1125°C and heat preservation was carried out for 2.5 hours; solution treatment was carried out at 1025°C for 1.2 hours to obtain a base sheet; Step 2: (1) Pickling the base sheet; the process is as follows: place the base sheet in a sulfuric acid solution and immerse it at 80°C for 1.5 minutes; transfer it to a mixed acid solution and set the current density to 6A / dm at 70°C. 2 Electropolish for 2.5 minutes, rinse with water, and blow dry with nitrogen; (2) Asynchronous cold rolling was performed on the steel sheet; the process was as follows: using the TRR path, setting the rolling force to 2100 kN, the upper and lower roll asynchronous ratio to 1.3:1, cold rolling at a rolling temperature of 55 °C with a rolling reduction rate of 30% for two passes, followed by intermediate annealing at 1075 °C for 22 min, and then cold rolling at a rolling reduction rate of 22% for one pass; (3) Annealing the sheet to obtain a cold-rolled base sheet A; the process is as follows: annealing the asynchronously cold-rolled base sheet at 1025°C for 1.2 h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1 to obtain a cold-rolled base sheet A; Step 3: Place the cold-rolled base sheet A in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 3:1; set the pressure to 200 Pa and the temperature to 450°C for low-temperature nitriding to form a nitriding layer with a thickness of 35 μm; subsequently, cold flatten and cut into coils to obtain high-nickel stainless steel cold-rolled sheets.

[0023] In the above embodiment, the chemical composition of the 316L stainless steel plate, calculated by mass percentage, includes: 0.8% silicon, 1.8% manganese, 14.2% nickel, 17.5% chromium, 2.3% molybdenum, 0.08% nitrogen, 0.015% carbon, and the remainder is iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.8 wt% of the mass of the 316L stainless steel plate.

[0024] Example 2: A process for preparing a high-nickel stainless steel cold-rolled sheet, comprising the following steps: Step 1: 316L stainless steel plate was heated to 1525°C in a nitrogen environment to form molten steel, TiN nanoparticles were added as a modifier, and smelting was continued for 25 minutes; casting was carried out at 1425°C for 1.5 hours under a nitrogen atmosphere; hot rolling was carried out at 1125°C and heat preservation was carried out for 2.5 hours; solution treatment was carried out at 1025°C for 1.2 hours to obtain a base sheet; Step 2: (1) Pickling the base sheet; the process is as follows: place the base sheet in a sulfuric acid solution and immerse it at 80°C for 1.5 minutes; transfer it to a mixed acid solution and set the current density to 6A / dm at 70°C. 2 Electropolish for 2.5 minutes, rinse with water, and blow dry with nitrogen; (2) Asynchronous cold rolling was performed on the steel sheet; the process was as follows: using the TRR path, setting the rolling force to 2100 kN, the upper and lower roll asynchronous ratio to 1.3:1, cold rolling at a rolling temperature of 55 °C with a rolling reduction rate of 30% for two passes, followed by intermediate annealing at 1075 °C for 22 min, and then cold rolling at a rolling reduction rate of 22% for one pass; (3) Annealing the sheet to obtain a cold-rolled base sheet A; the process is as follows: annealing the asynchronously cold-rolled base sheet at 1025°C for 1.2 h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1 to obtain a cold-rolled base sheet A; Step 3: Place the cold-rolled base sheet A in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 3:1; set the pressure to 200 Pa and the temperature to 450°C for low-temperature nitriding to form a nitriding layer with a thickness of 30 μm; subsequently, cold flatten and cut into coils to obtain high-nickel stainless steel cold-rolled sheets.

[0025] In the above embodiment, the chemical composition of the 316L stainless steel plate, calculated by mass percentage, includes: 0.5% silicon, 1.5% manganese, 13.8% nickel, 16.5% chromium, 2.2% molybdenum, 0.08% nitrogen, 0.015% carbon, and the remainder is iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.5 wt% of the mass of the 316L stainless steel plate.

[0026] Example 3: A process for preparing a high-nickel stainless steel cold-rolled sheet, comprising the following steps: Step 1: 316L stainless steel plate was heated to 1525°C in a nitrogen environment to form molten steel, TiN nanoparticles were added as a modifier, and smelting was continued for 25 minutes; casting was carried out at 1425°C for 1.5 hours under a nitrogen atmosphere; hot rolling was carried out at 1125°C and heat preservation was carried out for 2.5 hours; solution treatment was carried out at 1025°C for 1.2 hours to obtain a base sheet; Step 2: (1) Pickling the base sheet; the process is as follows: place the base sheet in a sulfuric acid solution and immerse it at 80°C for 1.5 minutes; transfer it to a mixed acid solution and set the current density to 6A / dm at 70°C. 2 Electropolish for 2.5 minutes, rinse with water, and blow dry with nitrogen; (2) Asynchronous cold rolling was performed on the steel sheet; the process was as follows: using the TRR path, setting the rolling force to 2100 kN, the upper and lower roll asynchronous ratio to 1.3:1, cold rolling at a rolling temperature of 55 °C with a rolling reduction rate of 30% for two passes, followed by intermediate annealing at 1075 °C for 22 min, and then cold rolling at a rolling reduction rate of 22% for one pass; (3) Annealing the sheet to obtain a cold-rolled base sheet A; the process is as follows: annealing the asynchronously cold-rolled base sheet at 1025°C for 1.2 h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1 to obtain a cold-rolled base sheet A; Step 3: Place the cold-rolled base sheet A in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 3:1; set the pressure to 200 Pa and the temperature to 450°C for low-temperature nitriding to form a nitriding layer with a thickness of 40 μm; subsequently cold flatten and cut into coils to obtain high-nickel stainless steel cold-rolled sheet.

[0027] In the above embodiment, the chemical composition of the 316L stainless steel plate, calculated by mass percentage, includes: 1.0% silicon, 2% manganese, 14.6% nickel, 18.5% chromium, 2.4% molybdenum, 0.05% nitrogen, 0.01% carbon, and the remainder is iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 1 wt% of the mass of the 316L stainless steel plate.

[0028] Comparative Example 1: Based on Example 1, the low-temperature nitriding process is not used, and the other processes remain unchanged, specifically: Step 1: 316L stainless steel plate was heated to 1525°C in a nitrogen environment to form molten steel, TiN nanoparticles were added as a modifier, and smelting was continued for 25 minutes; casting was carried out at 1425°C for 1.5 hours under a nitrogen atmosphere; hot rolling was carried out at 1125°C and heat preservation was carried out for 2.5 hours; solution treatment was carried out at 1025°C for 1.2 hours to obtain a base sheet; Step 2: (1) Pickling the base sheet; the process is as follows: place the base sheet in a sulfuric acid solution and immerse it at 80°C for 1.5 minutes; transfer it to a mixed acid solution and set the current density to 6A / dm at 70°C. 2 Electropolish for 2.5 minutes, rinse with water, and blow dry with nitrogen; (2) Asynchronous cold rolling was performed on the steel sheet; the process was as follows: using the TRR path, setting the rolling force to 2100 kN, the upper and lower roll asynchronous ratio to 1.3:1, cold rolling at a rolling temperature of 55 °C with a rolling reduction rate of 30% for two passes, followed by intermediate annealing at 1075 °C for 22 min, and then cold rolling at a rolling reduction rate of 22% for one pass; (3) Annealing the sheet to obtain a cold-rolled base sheet A; subsequently, cold-flattening, cutting, and coiling are performed to obtain a high-nickel stainless steel cold-rolled sheet; the process is as follows: annealing the asynchronously cold-rolled base sheet at 1025°C for 1.2h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1 to obtain a cold-rolled base sheet A; subsequently, cold-flattening, cutting, and coiling are performed to obtain a high-nickel stainless steel cold-rolled sheet.

[0029] In the above embodiment, the chemical composition of the 316L stainless steel plate, calculated by mass percentage, includes: 0.8% silicon, 1.8% manganese, 14.2% nickel, 17.5% chromium, 2.3% molybdenum, 0.08% nitrogen, 0.015% carbon, and the remainder is iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.8 wt% of the mass of the 316L stainless steel plate.

[0030] Comparative Example 2: Based on Example 1, the asynchronous cold rolling was adjusted to synchronous cold rolling, and the other processes remained unchanged, specifically: Step 1: 316L stainless steel plate was heated to 1525°C in a nitrogen environment to form molten steel, TiN nanoparticles were added as a modifier, and smelting was continued for 25 minutes; casting was carried out at 1425°C for 1.5 hours under a nitrogen atmosphere; hot rolling was carried out at 1125°C and heat preservation was carried out for 2.5 hours; solution treatment was carried out at 1025°C for 1.2 hours to obtain a base sheet; Step 2: (1) Pickling the base sheet; the process is as follows: place the base sheet in a sulfuric acid solution and immerse it at 80°C for 1.5 minutes; transfer it to a mixed acid solution and set the current density to 6A / dm at 70°C. 2 Electropolish for 2.5 minutes, rinse with water, and blow dry with nitrogen; (2) synchronous cold rolling; the process is: setting the speed ratio to 1:1, single pass 25% synchronous cold rolling at room temperature at 3000KN; (3) Annealing the sheet to obtain a cold-rolled base sheet A; the process is as follows: annealing the synchronously cold-rolled base sheet at 1025°C for 1.2 h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1 to obtain a cold-rolled base sheet A; Step 3: Place the cold-rolled base sheet A in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 3:1; set the pressure to 200 Pa and the temperature to 450°C for low-temperature nitriding to form a nitriding layer with a thickness of 35 μm; subsequently, cold flatten and cut into coils to obtain high-nickel stainless steel cold-rolled sheets.

[0031] In the above embodiment, the chemical composition of the 316L stainless steel plate, calculated by mass percentage, includes: 0.8% silicon, 1.8% manganese, 14.2% nickel, 17.5% chromium, 2.3% molybdenum, 0.08% nitrogen, 0.015% carbon, and the remainder is iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.8 wt% of the mass of the 316L stainless steel plate.

[0032] Comparative Example 3: Based on Example 1, the compound corrosion inhibitor in the pickling process was adjusted to a single corrosion inhibitor, and the other processes remained unchanged, specifically: Step 1: 316L stainless steel plate was heated to 1525°C in a nitrogen environment to form molten steel, TiN nanoparticles were added as a modifier, and smelting was continued for 25 minutes; casting was carried out at 1425°C for 1.5 hours under a nitrogen atmosphere; hot rolling was carried out at 1125°C and heat preservation was carried out for 2.5 hours; solution treatment was carried out at 1025°C for 1.2 hours to obtain a base sheet; Step 2: (1) Pickling the base sheet; the process is as follows: place the base sheet in a sulfuric acid solution and immerse it at 80°C for 1.5 minutes; transfer it to a mixed acid solution and set the current density to 6A / dm at 70°C. 2 Electropolish for 2.5 minutes, rinse with water, and blow dry with nitrogen; (2) Asynchronous cold rolling was performed on the steel sheet; the process was as follows: using the TRR path, setting the rolling force to 2100 kN, the upper and lower roll asynchronous ratio to 1.3:1, cold rolling at a rolling temperature of 55 °C with a rolling reduction rate of 30% for two passes, followed by intermediate annealing at 1075 °C for 22 min, and then cold rolling at a rolling reduction rate of 22% for one pass; (3) Annealing the sheet to obtain a cold-rolled base sheet A; the process is as follows: annealing the asynchronously cold-rolled base sheet at 1025°C for 1.2 h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1 to obtain a cold-rolled base sheet A; Step 3: Place the cold-rolled base sheet A in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 3:1; set the pressure to 200 Pa and the temperature to 450°C for low-temperature nitriding to form a nitriding layer with a thickness of 35 μm; subsequently, cold flatten and cut into coils to obtain high-nickel stainless steel cold-rolled sheets.

[0033] In the above embodiment, the chemical composition of the 316L stainless steel plate, calculated by mass percentage, includes: 0.8% silicon, 1.8% manganese, 14.2% nickel, 17.5% chromium, 2.3% molybdenum, 0.08% nitrogen, 0.015% carbon, and the remainder is iron and unavoidable impurities; the amount of the introduced TiN nanoparticles accounts for 0.8wt% of the mass of the 316L stainless steel plate; The mixed acid consists of the following components: 80 mg / L BTA, 100 g / L nitric acid, and 15 g / L hydrofluoric acid.

[0034] Comparative Example 4: Based on Example 1, TiN nanoparticles were not added, and the other processes remained unchanged, specifically: Step 1: Heat the 316L stainless steel plate to 1525°C in a nitrogen environment to form molten steel, and smelt it for 25 minutes; cast it at 1425°C for 1.5 hours in a nitrogen atmosphere; hot roll it at 1125°C and keep it for 2.5 hours; and solutionize it at 1025°C for 1.2 hours to obtain a base sheet; Step 2: (1) Pickling the base sheet; the process is as follows: place the base sheet in a sulfuric acid solution and immerse it at 80°C for 1.5 minutes; transfer it to a mixed acid solution and set the current density to 6A / dm at 70°C. 2 Electropolish for 2.5 minutes, rinse with water, and blow dry with nitrogen; (2) Asynchronous cold rolling was performed on the steel sheet; the process was as follows: using the TRR path, setting the rolling force to 2100 kN, the upper and lower roll asynchronous ratio to 1.3:1, cold rolling at a rolling temperature of 55 °C with a rolling reduction rate of 30% for two passes, followed by intermediate annealing at 1075 °C for 22 min, and then cold rolling at a rolling reduction rate of 22% for one pass; (3) Annealing the sheet to obtain a cold-rolled base sheet A; the process is as follows: annealing the asynchronously cold-rolled base sheet at 1025°C for 1.2 h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1 to obtain a cold-rolled base sheet A; Step 3: Place the cold-rolled base sheet A in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 3:1; set the pressure to 200 Pa and the temperature to 450°C for low-temperature nitriding to form a nitriding layer with a thickness of 35 μm; subsequently, cold flatten and cut into coils to obtain high-nickel stainless steel cold-rolled sheets.

[0035] In the above embodiment, the chemical composition of the 316L stainless steel plate includes, by mass percentage, 0.8% silicon, 1.8% manganese, 14.2% nickel, 17.5% chromium, 2.3% molybdenum, 0.08% nitrogen, 0.015% carbon, and the remainder is iron and unavoidable impurities.

[0036] Testing experiment: The performance of a high-nickel stainless steel cold-rolled sheet prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested: (1) Mechanical property test: With reference to GB / T 228.1-2021, the yield strength of a high-nickel stainless steel cold-rolled sheet prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested; the test results are shown in Table 1; (2) Corrosion resistance test: With reference to GB4334.7-84, a 6% FeCl3 aqueous solution was used for pitting at 35°C for 24 hours to test the corrosion rate. The results are shown in Table 1; Table 1

[0037] Result analysis: According to the data analysis in Table 1, it can be seen that the high nickel stainless steel cold rolled sheet prepared by this scheme has excellent mechanical properties and corrosion resistance. From the data of comparative example 1, it can be seen that without adopting the low temperature nitriding process and introducing the solid solution nitrogen surface layer, the austenite phase region cannot be expanded and the transformation of the deformed martensite to the δ phase cannot be suppressed, and the mechanical properties and corrosion resistance are significantly reduced; from the data of comparative example 2, it can be seen that adjusting the asynchronous cold rolling to synchronous cold rolling can easily induce stress concentration to form a hydrogen diffusion channel, hydrogen embrittlement and edge cracking, and the mechanical properties and corrosion resistance are reduced; from the data of comparative example 3, it can be seen that the compound corrosion inhibitor in the pickling is adjusted to a single corrosion inhibitor, the hydrogen embrittlement blocking effect is reduced, and the mechanical properties and corrosion resistance are reduced; from the data of comparative example 4, it can be seen that without adding TiN nanoparticles, coarse σ phase of δ ferrite will be precipitated, resulting in grain boundary embrittlement, dislocation slip obstruction, and a significant reduction in mechanical properties; in terms of corrosion resistance, σ phase precipitation will cause grain boundary chromium depletion and δ phase galvanic corrosion, and the corrosion resistance will be significantly reduced.

[0038] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A process for preparing a high nickel stainless steel cold rolled sheet, characterized in that: The following steps are involved: Step 1: Heat the 316L stainless steel plate to 1500-1550°C in a nitrogen environment to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 20-30 minutes; then cast, hot roll, and solid solution to obtain a base thin plate; Step 2: pickling, asynchronous cold rolling, and annealing the base sheet to obtain a cold-rolled base sheet A; Step 3: Low-temperature nitriding is performed on the cold-rolled base sheet A to form a nitrided layer; and then cold flattening, cutting and coiling are performed to obtain a high-nickel stainless steel cold-rolled sheet.

2. The process for preparing a high nickel stainless steel cold rolled sheet according to claim 1, wherein: The chemical composition of the 316L stainless steel plate includes, by mass percentage, 0.5% to 1.0% silicon, 1.5% to 2% manganese, 13.8% to 14.6% nickel, 16.5% to 18.5% chromium, 2.2% to 2.4% molybdenum, nitrogen ≤ 0.08%, carbon ≤ 0.015%, and the remainder is iron and unavoidable impurities; the amount of the TiN nanoparticles introduced accounts for 0.5wt% to 1wt% of the mass of the 316L stainless steel plate.

3. The process for preparing a high nickel stainless steel cold rolled sheet according to claim 1, wherein: The asynchronous cold rolling adopts staged cold rolling; specifically, after cold rolling for 2 passes at a rolling reduction rate of 25-35%, intermediate annealing at 1050-1100° C. for 15-30 minutes, and then cold rolling for 1 pass at a rolling reduction rate of 20-25%.

4. The process for preparing a high nickel stainless steel cold rolled sheet according to claim 3, wherein: The asynchronous cold rolling adopts the TRR path; the process parameters are: rolling force of 1800~2500KN; upper roll and lower roll asynchronous ratio of 1.2~1.4:1; rolling temperature of 50~60℃.

5. The process for preparing a high nickel stainless steel cold rolled sheet according to claim 1, wherein: In step 2, the pickling process is as follows: the base sheet is placed in a sulfuric acid solution and immersed at 75-85°C for 1-2 minutes; then transferred to a mixed acid solution at 65-75°C with a current density of 4-8A / dm 2 Electropolishing for 2-3 minutes, washing with water, and drying with nitrogen; The annealing process is as follows: annealing the asynchronously cold-rolled base sheet at 1050-1100° C. for 0.8-1.5 h in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 8-10:

1.

6. The process for preparing a high nickel stainless steel cold rolled sheet according to claim 5, characterized in that: The mixed acid is composed of the following components: 100-150 mg / L Mannich base, 80-130 mg / L sodium molybdate, 45-55 mg / L BTA, 95-105 g / L nitric acid, and 10-20 g / L hydrofluoric acid; The concentration of the sulfuric acid solution is 15wt%~20wt% sulfuric acid solution.

7. The process for preparing a high nickel stainless steel cold rolled sheet according to claim 1, characterized in that: The low-temperature nitriding process is as follows: placing the cold-rolled base sheet A in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 2-4:1; setting the pressure to 180-220 Pa and the temperature to 440-460° C. for low-temperature nitriding to form a nitrided layer.

8. The process for preparing a high nickel stainless steel cold rolled sheet according to claim 7, characterized in that: The thickness of the nitriding layer is 30-40 μm.

9. The process for preparing a high nickel stainless steel cold rolled sheet according to claim 1, characterized in that: In step 1, the casting working atmosphere is a nitrogen atmosphere, the casting temperature is 1400~1450℃, and the casting time is 1~2h; the hot rolling temperature is 1100~1150℃, and the holding time is 2~3h; the solution temperature is 1000~1050℃, and the solution time is 0.8~1.5h.

10. A high nickel stainless steel cold rolled sheet obtained according to the preparation process of a high nickel stainless steel cold rolled sheet according to any one of claims 1 to 9.

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