High-nickel stainless steel cold-rolled sheet and process for producing the same

Abstract

The present application 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. The process comprises the following steps: step 1: heating 316L stainless steel plate to 1500-1550 DEG C under nitrogen environment to form molten steel, adding TiN nanoparticles as a modifier, and continuing smelting for 20-30 min; casting, hot rolling and solid solution to obtain a base sheet; step 2: pickling, asynchronous cold rolling and annealing the base sheet to obtain a cold-rolled base sheet A; step 3: low-temperature nitriding the cold-rolled base sheet A to form a nitriding layer; and then cold flattening and cutting to obtain the high nickel stainless steel cold-rolled sheet.

Description

Technical Field

[0001] This invention relates to the field of high-nickel stainless steel technology, specifically to a high-nickel stainless steel cold-rolled sheet and its preparation process. Background Technology

[0002] High-nickel stainless steel cold-rolled sheets are widely used in chemical, aerospace, and other fields due to their excellent high-temperature resistance. However, the following problems still exist in the actual manufacturing process, directly affecting their mechanical properties and corrosion resistance:

[0003] Firstly, in traditional manufacturing processes, hot rolling and solution treatment easily precipitate σ phase and δ ferrite, which not only directly reduces the plasticity and toughness of the material, but also exacerbates compositional segregation and induces cracks. At the same time, since no modifier is added in the process, it is impossible to control the heterogeneous nucleation of δ ferrite, resulting in coarse δ ferrite grains. These coarse δ ferrite grains are enriched with Cr and Mo elements, which will preferentially transform into σ phase during aging, 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.

[0004] Secondly, traditional hot rolling and solution treatment processes leave a hard oxide layer on the material surface, which cannot be uniformly and completely removed by mechanical treatments such as sandblasting and grinding. Therefore, direct strong acid pickling is often used to remove the surface oxide layer. However, this process generates additional hydrogen gas, causing some hydrogen atoms to penetrate into the material, further leading to hydrogen embrittlement and a decrease in mechanical properties and corrosion resistance. Moreover, the single corrosion inhibitors typically used are easily decomposed in strong oxidizing acids, failing to form an effective protective film and resulting in excessive surface corrosion.

[0005] Third, in traditional manufacturing processes, synchronous rolling is mostly used. On the one hand, the material deformation resistance increases sharply during rolling, which leads to high rolling force and dislocation pile-up. Hydrogen diffusion channels are formed at stress concentration, causing hydrogen embrittlement and edge cracking. On the other hand, synchronous rolling can lead to uneven deformation between the surface and the interior, resulting in a large difference in grain size, which affects mechanical properties and corrosion resistance.

[0006] In conclusion, solving the above problems and preparing a high-nickel stainless steel cold-rolled sheet is of great significance. Summary of the Invention

[0007] The purpose of this invention is to provide a high-nickel stainless steel cold-rolled sheet and its preparation process to solve the problems mentioned in the background art.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] A process for preparing high-nickel stainless steel cold-rolled sheet includes the following steps:

[0010] Step 1: Heat 316L stainless steel plate to 1500~1550℃ in a nitrogen atmosphere to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 20~30 minutes; cast, hot roll, and solution treat to obtain the basic thin plate;

[0011] Step 2: Pickling, asynchronous cold rolling, and annealing of the base sheet to obtain cold-rolled base sheet A;

[0012] Step 3: The cold-rolled base sheet A is subjected to low-temperature nitriding to form a nitrided layer; subsequently, it is cold-flattened, cut, and rolled to obtain a high-nickel stainless steel cold-rolled sheet.

[0013] In a more optimized manner, the chemical composition of the 316L stainless steel plate, by mass percentage, includes: 0.5%~1.0% silicon, 1.5%~2% manganese, 13.8%~14.6% nickel, 16.5%~18.5% chromium, 2.2%~2.4% molybdenum, nitrogen ≤0.08%, carbon ≤0.015%, with the remainder being iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.5wt%~1wt% of the mass of the 316L stainless steel plate.

[0014] In a more optimized manner, the asynchronous cold rolling adopts a staged cold rolling process; specifically: after cold rolling for two passes with a rolling reduction rate of 25-35%, it is annealed at 1050-1100℃ for 15-30 minutes, and then cold rolled for one pass with a rolling reduction rate of 20-25%.

[0015] In a more optimized manner, the asynchronous cold rolling adopts the TRR path; the process parameters are: rolling force of 1800~2500KN; asynchronous ratio of upper roll to lower roll of 1.2~1.4:1; and rolling temperature of 50~60℃.

[0016] In a more optimized manner, step 2 involves the following pickling process: The base plate is immersed in a sulfuric acid solution at 75-85°C for 1-2 minutes; then transferred to a mixed acid solution at 65-75°C with a current density of 4-8 A / dm³. 2 Electropolishing for 2-3 minutes, followed by rinsing with water and drying with nitrogen.

[0017] The annealing process is as follows: under a mixed atmosphere of nitrogen and hydrogen in a volume ratio of 8 to 10:1, the base sheet that has undergone asynchronous cold rolling is annealed at 1050 to 1100°C for 0.8 to 1.5 hours.

[0018] More preferably, 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;

[0019] The sulfuric acid solution has a concentration of 15wt% to 20wt%.

[0020] In a more optimized manner, the low-temperature nitriding process is as follows: cold-rolled base sheet A is placed in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 2 to 4:1; the pressure is set at 180 to 220 Pa and the temperature at 440 to 460 °C to perform low-temperature nitriding to form a nitrided layer.

[0021] Ideally, the thickness of the nitrided layer is 30~40 μm.

[0022] In a more optimized manner, in step 1, the working atmosphere for casting 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 treatment temperature is 1000~1050℃, and the solution treatment time is 0.8~1.5h.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] First, the proposed solution introduces TiN nanoparticles as a modifier, combined with a low-temperature nitriding process, to synergistically improve ductility and toughness, and address issues such as component segregation and hot cracking. Specifically, TiN nanoparticles, acting as a modifier, refine δ-ferrite through heterogeneous nucleation, reducing the segregation of Cr and Mo elements in the δ-phase. Simultaneously, TiN nanoparticles, by refining the δ-phase size and increasing the phase interface, inhibit the transformation of δ-ferrite into the σ-phase during aging, thus improving ductility and toughness. The low-temperature nitriding process, by forming a dissolved nitrogen surface layer, expands the austenite phase region, inhibiting the transformation of deformed martensite into the δ-phase, improving ductility and toughness, and reducing crack initiation; further enhancing mechanical properties and corrosion resistance.

[0025] However, oxides still form on the material surface after hot rolling and solution treatment, making it prone to hydrogen embrittlement when electropolished with strong oxidizing acids. Therefore, this solution employs a combined pickling method with a compound corrosion inhibitor. The Mannich base, sodium molybdate, and BTA form a synergistic corrosion inhibitor to reduce hydrogen embrittlement. Specifically, BTA preferentially adsorbs at active sites such as twin boundaries and dislocations, chelating with the base metal to form a dense film that blocks hydrogen permeation channels, further suppressing hydrogen embrittlement. Sodium molybdate effectively blocks hydrogen ions during electropolishing. The Mannich base enhances hydrophobicity through its long-chain amino groups, physically blocking and improving corrosion resistance.

[0026] However, the work hardening characteristics of high-nickel stainless steel cause a sharp increase in rolling force when using traditional synchronous cold rolling, which leads to stress concentration and the formation of hydrogen diffusion channels, resulting in hydrogen embrittlement and edge cracking. Therefore, in order to solve the above problems, the solution adopts asynchronous cold rolling, which increases the slip band density and dislocation entanglement through staged rolling, refines the grains, reduces rolling force, avoids martensitic phase transformation, stabilizes plasticity, and further improves mechanical properties. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that the following parts are by weight. There are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: sodium molybdate with CAS number 7631-95-0; hydrofluoric acid with CAS number 7664-39-3; nitric acid with CAS number 7697-37-2; Mannich base with CAS number 81080-09-3; BTA with CAS number 95-14-7; and TiN nanoparticles with a specification of 20nm, catalog number AM-TiN-N-01, purchased from Zhejiang Yamei Nanotechnology Co., Ltd.

[0029] In the following embodiments, it is specifically noted that:

[0030] (1) The mixed acid consists of the following components: 125 mg / L Mannich base, 110 mg / L sodium molybdate, 50 mg / L LBTA, 100 g / L nitric acid, and 15 g / L hydrofluoric acid;

[0031] (2) The concentration of the sulfuric acid solution is 18wt% sulfuric acid solution.

[0032] Example 1: A process for preparing high-nickel stainless steel cold-rolled sheet, comprising the following steps:

[0033] Step 1: Heat 316L stainless steel plate to 1525℃ in a nitrogen atmosphere to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 25 minutes; cast at 1425℃ for 1.5 hours in a nitrogen atmosphere; hot roll at 1125℃ and hold for 2.5 hours; solution treat at 1025℃ for 1.2 hours to obtain the basic thin plate;

[0034] Step 2: (1) Pickling the base plate; the process is as follows: place the base plate 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 Electropolishing for 2.5 minutes, followed by rinsing with water and drying with nitrogen.

[0035] (2) It is subjected to asynchronous cold rolling; the process is as follows: using the TRR path, the rolling force is set to 2100KN, the asynchronous ratio of the upper roll to the lower roll is 1.3:1, and it is cold rolled for 2 passes at a rolling temperature of 55℃ with a rolling reduction rate of 30%, then annealed at 1075℃ for 22min, and then cold rolled for 1 pass with a rolling reduction rate of 22%.

[0036] (3) Anneal it to obtain cold-rolled base sheet A; the process is as follows: under a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1, the base sheet that has been asynchronously cold rolled is annealed at 1025℃ for 1.2h to obtain cold-rolled base sheet A.

[0037] 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 gas pressure to 200 Pa and the temperature to 450 ℃ for low-temperature nitriding to form a nitrided layer with a thickness of 35 μm; then cold flatten, cut and roll to obtain a high-nickel stainless steel cold-rolled sheet.

[0038] In the above embodiments, the chemical composition of the 316L stainless steel plate, 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, with the remainder being iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.8 wt% of the mass of the 316L stainless steel plate.

[0039] Example 2: A process for preparing high-nickel stainless steel cold-rolled sheet, comprising the following steps:

[0040] Step 1: Heat 316L stainless steel plate to 1525℃ in a nitrogen atmosphere to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 25 minutes; cast at 1425℃ for 1.5 hours in a nitrogen atmosphere; hot roll at 1125℃ and hold for 2.5 hours; solution treat at 1025℃ for 1.2 hours to obtain the basic thin plate;

[0041] Step 2: (1) Pickling the base plate; the process is as follows: place the base plate 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 Electropolishing for 2.5 minutes, followed by rinsing with water and drying with nitrogen.

[0042] (2) It is subjected to asynchronous cold rolling; the process is as follows: using the TRR path, the rolling force is set to 2100KN, the asynchronous ratio of the upper roll to the lower roll is 1.3:1, and it is cold rolled for 2 passes at a rolling temperature of 55℃ with a rolling reduction rate of 30%, then annealed at 1075℃ for 22min, and then cold rolled for 1 pass with a rolling reduction rate of 22%.

[0043] (3) Anneal it to obtain cold-rolled base sheet A; the process is as follows: under a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1, the base sheet that has been asynchronously cold rolled is annealed at 1025℃ for 1.2h to obtain cold-rolled base sheet A.

[0044] 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 gas pressure to 200 Pa and the temperature to 450 ℃ for low-temperature nitriding to form a nitrided layer with a thickness of 30 μm; then cold flatten, cut and roll to obtain a high-nickel stainless steel cold-rolled sheet.

[0045] In the above embodiments, the chemical composition of the 316L stainless steel plate, 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, with the remainder being iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.5 wt% of the mass of the 316L stainless steel plate.

[0046] Example 3: A process for preparing high-nickel stainless steel cold-rolled sheet, comprising the following steps:

[0047] Step 1: Heat 316L stainless steel plate to 1525℃ in a nitrogen atmosphere to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 25 minutes; cast at 1425℃ for 1.5 hours in a nitrogen atmosphere; hot roll at 1125℃ and hold for 2.5 hours; solution treat at 1025℃ for 1.2 hours to obtain the basic thin plate;

[0048] Step 2: (1) Pickling the base plate; the process is as follows: place the base plate 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 Electropolishing for 2.5 minutes, followed by rinsing with water and drying with nitrogen.

[0049] (2) It is subjected to asynchronous cold rolling; the process is as follows: using the TRR path, the rolling force is set to 2100KN, the asynchronous ratio of the upper roll to the lower roll is 1.3:1, and it is cold rolled for 2 passes at a rolling temperature of 55℃ with a rolling reduction rate of 30%, then annealed at 1075℃ for 22min, and then cold rolled for 1 pass with a rolling reduction rate of 22%.

[0050] (3) Anneal it to obtain cold-rolled base sheet A; the process is as follows: under a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1, the base sheet that has been asynchronously cold rolled is annealed at 1025℃ for 1.2h to obtain cold-rolled base sheet A.

[0051] 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 gas pressure to 200 Pa and the temperature to 450 ℃ for low-temperature nitriding to form a nitrided layer with a thickness of 40 μm; then cold flatten, cut and roll to obtain a high-nickel stainless steel cold-rolled sheet.

[0052] In the above embodiments, the chemical composition of the 316L stainless steel plate, by mass percentage, includes: 1.0% silicon, 2% manganese, 14.6% nickel, 18.5% chromium, 2.4% molybdenum, 0.05% nitrogen, 0.01% carbon, with the remainder being iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 1 wt% of the mass of the 316L stainless steel plate.

[0053] Comparative Example 1: Based on Example 1, the low-temperature nitriding process was not used, but the other processes remained unchanged, specifically:

[0054] Step 1: Heat 316L stainless steel plate to 1525℃ in a nitrogen atmosphere to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 25 minutes; cast at 1425℃ for 1.5 hours in a nitrogen atmosphere; hot roll at 1125℃ and hold for 2.5 hours; solution treat at 1025℃ for 1.2 hours to obtain the basic thin plate;

[0055] Step 2: (1) Pickling the base plate; the process is as follows: place the base plate 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 Electropolishing for 2.5 minutes, followed by rinsing with water and drying with nitrogen.

[0056] (2) It is subjected to asynchronous cold rolling; the process is as follows: using the TRR path, the rolling force is set to 2100KN, the asynchronous ratio of the upper roll to the lower roll is 1.3:1, and it is cold rolled for 2 passes at a rolling temperature of 55℃ with a rolling reduction rate of 30%, then annealed at 1075℃ for 22min, and then cold rolled for 1 pass with a rolling reduction rate of 22%.

[0057] (3) Anneal it to obtain cold-rolled base sheet A; then cold flatten, cut and roll it to obtain high-nickel stainless steel cold-rolled sheet; the process is as follows: under a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1, the base sheet that has been asynchronously cold rolled is annealed at 1025℃ for 1.2h to obtain cold-rolled base sheet A; then cold flatten, cut and roll it to obtain high-nickel stainless steel cold-rolled sheet.

[0058] In the above embodiments, the chemical composition of the 316L stainless steel plate, 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, with the remainder being iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.8 wt% of the mass of the 316L stainless steel plate.

[0059] Comparative Example 2: Based on Example 1, asynchronous cold rolling was changed to synchronous cold rolling, while the other processes remained unchanged. Specifically:

[0060] Step 1: Heat 316L stainless steel plate to 1525℃ in a nitrogen atmosphere to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 25 minutes; cast at 1425℃ for 1.5 hours in a nitrogen atmosphere; hot roll at 1125℃ and hold for 2.5 hours; solution treat at 1025℃ for 1.2 hours to obtain the basic thin plate;

[0061] Step 2: (1) Pickling the base plate; the process is as follows: place the base plate 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 Electropolishing for 2.5 minutes, followed by rinsing with water and drying with nitrogen.

[0062] (2) It is subjected to synchronous cold rolling; the process is as follows: the speed ratio is set to 1:1, and 25% of the single pass is subjected to synchronous cold rolling at 3000KN at room temperature;

[0063] (3) Anneal it to obtain cold-rolled base sheet A; the process is as follows: under a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1, the base sheet that has been synchronously cold rolled is annealed at 1025℃ for 1.2h to obtain cold-rolled base sheet A.

[0064] 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 gas pressure to 200 Pa and the temperature to 450 ℃ for low-temperature nitriding to form a nitrided layer with a thickness of 35 μm; then cold flatten, cut and roll to obtain a high-nickel stainless steel cold-rolled sheet.

[0065] In the above embodiments, the chemical composition of the 316L stainless steel plate, 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, with the remainder being iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.8 wt% of the mass of the 316L stainless steel plate.

[0066] Comparative Example 3: Based on Example 1, the compound corrosion inhibitor in pickling was changed to a single corrosion inhibitor, while the rest of the process remained unchanged. Specifically:

[0067] Step 1: Heat 316L stainless steel plate to 1525℃ in a nitrogen atmosphere to form molten steel, add TiN nanoparticles as a modifier, and continue smelting for 25 minutes; cast at 1425℃ for 1.5 hours in a nitrogen atmosphere; hot roll at 1125℃ and hold for 2.5 hours; solution treat at 1025℃ for 1.2 hours to obtain the basic thin plate;

[0068] Step 2: (1) Pickling the base plate; the process is as follows: place the base plate 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 Electropolishing for 2.5 minutes, followed by rinsing with water and drying with nitrogen.

[0069] (2) It is subjected to asynchronous cold rolling; the process is as follows: using the TRR path, the rolling force is set to 2100KN, the asynchronous ratio of the upper roll to the lower roll is 1.3:1, and it is cold rolled for 2 passes at a rolling temperature of 55℃ with a rolling reduction rate of 30%, then annealed at 1075℃ for 22min, and then cold rolled for 1 pass with a rolling reduction rate of 22%.

[0070] (3) Anneal it to obtain cold-rolled base sheet A; the process is as follows: under a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1, the base sheet that has been asynchronously cold rolled is annealed at 1025℃ for 1.2h to obtain cold-rolled base sheet A.

[0071] 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 gas pressure to 200 Pa and the temperature to 450 ℃ for low-temperature nitriding to form a nitrided layer with a thickness of 35 μm; then cold flatten, cut and roll to obtain a high-nickel stainless steel cold-rolled sheet.

[0072] In the above embodiments, the chemical composition of the 316L stainless steel plate, 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, with the remainder being iron and unavoidable impurities; the amount of TiN nanoparticles introduced accounts for 0.8 wt% of the mass of the 316L stainless steel plate.

[0073] The mixed acid consists of the following components: 80 mg / L LBTA, 100 g / L nitric acid, and 15 g / L hydrofluoric acid.

[0074] Comparative Example 4: Based on Example 1, without adding TiN nanoparticles, but with the other processes unchanged, specifically:

[0075] Step 1: Heat the 316L stainless steel plate to 1525℃ in a nitrogen atmosphere to form molten steel, and smelt for 25 minutes; cast at 1425℃ for 1.5 hours in a nitrogen atmosphere; hot roll at 1125℃ and hold for 2.5 hours; solution treat at 1025℃ for 1.2 hours to obtain the basic thin plate.

[0076] Step 2: (1) Pickling the base plate; the process is as follows: place the base plate 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. 2Electropolishing for 2.5 minutes, followed by rinsing with water and drying with nitrogen.

[0077] (2) It is subjected to asynchronous cold rolling; the process is as follows: using the TRR path, the rolling force is set to 2100KN, the asynchronous ratio of the upper roll to the lower roll is 1.3:1, and it is cold rolled for 2 passes at a rolling temperature of 55℃ with a rolling reduction rate of 30%, then annealed at 1075℃ for 22min, and then cold rolled for 1 pass with a rolling reduction rate of 22%.

[0078] (3) Anneal it to obtain cold-rolled base sheet A; the process is as follows: under a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 9:1, the base sheet that has been asynchronously cold rolled is annealed at 1025℃ for 1.2h to obtain cold-rolled base sheet A.

[0079] 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 gas pressure to 200 Pa and the temperature to 450 ℃ for low-temperature nitriding to form a nitrided layer with a thickness of 35 μm; then cold flatten, cut and roll to obtain a high-nickel stainless steel cold-rolled sheet.

[0080] In the above embodiments, the chemical composition of the 316L stainless steel plate, 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, with the remainder being iron and unavoidable impurities.

[0081] Test experiment: The high-nickel stainless steel cold-rolled sheet prepared in Examples 1-3 and Comparative Examples 1-4 was tested for its performance: (1) Mechanical property test: The yield strength of the high-nickel stainless steel cold-rolled sheet prepared in Examples 1-3 and Comparative Examples 1-4 was tested according to GB / T 228.1-2021; the test results are shown in Table 1; (2) Corrosion resistance test: The corrosion rate was tested by pitting 6% FeCl3 aqueous solution at 35℃ for 24h according to GB4334.7-84; the results are shown in Table 1.

[0082] Table 1

[0083]

[0084] Results Analysis: Analysis of the data in Table 1 shows that the high-nickel stainless steel cold-rolled sheet prepared using this method exhibits excellent mechanical properties and corrosion resistance. Comparative Example 1 data shows that without low-temperature nitriding and the introduction of a dissolved nitrogen surface layer, the austenite phase region cannot be expanded, and the transformation of deformed martensite to the δ phase cannot be suppressed, resulting in a significant decrease in mechanical properties and corrosion resistance. Comparative Example 2 data shows that changing asynchronous cold rolling to synchronous cold rolling easily leads to stress concentration, forming hydrogen diffusion channels, causing hydrogen embrittlement and edge cracking, thus reducing mechanical properties and corrosion resistance. Comparative Example 3 data shows that changing the compound corrosion inhibitor in pickling to a single corrosion inhibitor reduces the hydrogen embrittlement blocking effect, resulting in a decrease in mechanical properties and corrosion resistance. Comparative Example 4 data shows that without the addition of TiN nanoparticles, coarse δ-ferrite σ-phase precipitation occurs, leading to grain boundary embrittlement, hindered dislocation slip, and a significant decrease in mechanical properties; in terms of corrosion resistance, σ-phase precipitation causes grain boundary chromium depletion and δ-phase galvanic corrosion, significantly reducing corrosion resistance.

[0085] 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 implemented 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 exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A process for the production of high nickel stainless steel cold rolled sheet characterized in that: The preparation process comprises the following steps: Step 1: heating 316L stainless steel plate to 1500-1550℃ under nitrogen atmosphere to form molten steel, adding TiN nanoparticles as a modifier, and continuing smelting for 20-30 min; casting, hot rolling, and solid solution to obtain a base sheet; Step 2: pickling, asynchronous cold rolling, and annealing the base sheet to obtain a cold-rolled base sheet A; Step 3: low-temperature nitriding the cold-rolled base sheet A to form a nitriding layer; subsequent cold flattening and cutting to obtain a high-nickel stainless steel cold-rolled sheet; The pickling process is as follows: the base sheet is placed in a sulfuric acid solution, immersed and treated at 75-85°C for 1-2 min; transferred to a mixed acid, set at 65-75°C, and an electric current density of 4-8 A / dm 2 electropolished for 2-3 min, washed with water, and dried with nitrogen. The annealing process is as follows: annealing the base sheet after asynchronous cold rolling at 1050-1100℃ for 0.8-1.5 h under a mixed atmosphere with a nitrogen-hydrogen volume ratio of 8-10:1; The mixed acid comprises 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.

2. The process for producing a high nickel stainless steel cold rolled sheet as claimed in claim 1, wherein: The 316L stainless steel plate comprises, by mass percentage, 0.5%-1.0% silicon, 1.5%-2% manganese, 13.8%-14.6% nickel, 16.5%-18.5% chromium, 2.2%-2.4% molybdenum, ≤0.08% nitrogen, ≤0.015% carbon, and the balance of iron and unavoidable impurities; and the TiN nanoparticles are introduced in an amount of 0.5wt%-1wt% of the mass of the 316L stainless steel plate.

3. The process for producing high nickel stainless steel cold rolled sheet as claimed in claim 1 wherein the process is characterized by: The asynchronous cold rolling is performed in stages; specifically, cold rolling for 2 passes at a rolling reduction rate of 25-35%, intermediate annealing at 1050-1100℃ for 15-30 min, and cold rolling for 1 pass at a rolling reduction rate of 20-25%.

4. The process for producing a high nickel stainless steel cold rolled sheet as claimed in claim 3, wherein the process further comprises the steps of: The asynchronous cold rolling adopts a TRR path; the process parameters are as follows: rolling force is 1800-2500 KN; the asynchronous ratio of the upper roller to the lower roller is 1.2-1.4:1; and the rolling temperature is 50-60℃.

5. The process for producing high nickel stainless steel cold rolled sheet as claimed in claim 1 wherein the process is characterized by: The low-temperature nitriding process is as follows: low-temperature nitriding the cold-rolled base sheet A in a mixed atmosphere with a nitrogen-hydrogen volume ratio of 2-4:1; setting the gas pressure to 180-220 Pa and the temperature to 440-460℃ to form a nitriding layer.

6. The process for producing a high nickel stainless steel cold rolled sheet as claimed in claim 5, wherein the process further comprises the steps of: The thickness of the nitriding layer is 30-40 μm.

7. The process for producing high nickel stainless steel cold rolled sheet as claimed in claim 1 wherein the process is characterized by: In step 1, the working atmosphere for casting is a nitrogen atmosphere, the casting temperature is 1400-1450℃, and the casting time is 1-2 h; the hot rolling temperature is 1100-1150℃, and the holding time is 2-3 h; and the solid solution temperature is 1000-1050℃, and the solid solution time is 0.8-1.5 h.

8. A high-nickel stainless steel cold-rolled sheet prepared by the preparation process of any one of claims 1-7.

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