Hydrogen embrittlement resistant austenitic stainless steel and method of making and using same

Abstract

The application provides a hydrogen embrittlement resistant austenitic stainless steel and a preparation method and application thereof. The hydrogen embrittlement resistant austenitic stainless steel comprises the following components in percentage by mass: C: 0.02-0.08%, Cr: 24.0-26.5%, Ni: 17.5-18.2%, Cu: 1.8-2.5%, Mn: 0.5-2.0%, Si: 0.3-1.0%, N: 0.05-0.25%, Al: 0.01-0.10%, S: <0.01%, P: <0.01%, and the balance of Fe and inevitable impurities. The hydrogen embrittlement resistant austenitic stainless steel provided by the application takes the functional design of copper elements as a core innovation point, introduces 1.8-2.5wt% of copper to replace part of nickel on the basis of controlling nickel at 17.5-18.2wt%, reduces the alloy cost, and improves the hydrogen embrittlement resistance by regulating the microstructure and surface state of the material.

Description

Technical Field

[0001] This application relates to the field of metallic materials technology, and more specifically, to a hydrogen-resistant austenitic stainless steel, its preparation method, and its application. Background Technology

[0002] With the rapid development of the hydrogen energy industry, the production, storage, transportation, and utilization of high-pressure gaseous and liquid hydrogen have placed higher performance and cost requirements on structural materials. The dissolution, diffusion, and accumulation of hydrogen in metals can induce delayed fracture or brittle fracture, seriously threatening the service reliability of high-pressure hydrogen storage and transportation equipment. Currently, face-centered cubic austenitic stainless steel is considered a material system with excellent resistance to hydrogen embrittlement due to its high austenitic stability and relatively low hydrogen diffusion coefficient. Typical grades such as 310S and 316L exhibit better stability than martensitic or bainitic steels in various hydrogen environments. However, to ensure corrosion resistance and high-temperature performance, traditional austenitic stainless steels typically contain a high proportion of nickel. Nickel is a key element for stabilizing austenitic microstructure, but its market price fluctuates significantly, accounting for a large proportion of the total material cost. With the large-scale development of hydrogen energy equipment, material cost issues are becoming increasingly prominent. Therefore, reducing nickel content while ensuring microstructure stability and hydrogen resistance has become an important direction in current material design.

[0003] Therefore, developing an austenitic stainless steel material that combines low cost, structural stability, and resistance to hydrogen embrittlement remains of practical significance. Summary of the Invention

[0004] The main objective of this application is to provide a hydrogen-resistant austenitic stainless steel, its preparation method, and its application, in order to solve the problem that traditional austenitic stainless steel contains a high proportion of nickel, which leads to increasingly prominent material cost issues.

[0005] To achieve the above objectives, according to one aspect of this application, a hydrogen embrittlement-resistant austenitic stainless steel is provided, comprising, by weight percentage: C: 0.02–0.08%, Cr: 24.0–26.5%, Ni: 17.5–18.2%, Cu: 1.8–2.5%, Mn: 0.5–2.0%, Si: 0.3–1.0%, N: 0.05–0.25%, Al: 0.01–0.10%, S < 0.01%, P < 0.01%, with the balance being Fe and unavoidable impurities.

[0006] Furthermore, in the hydrogen embrittlement resistant austenitic stainless steel, the mass content of S is ≤0.006% and the mass content of P is ≤0.006%.

[0007] Furthermore, by mass percentage, the Cu content in hydrogen embrittlement resistant austenitic stainless steel is 1.9~2.3%.

[0008] Furthermore, in the hydrogen embrittlement resistant austenitic stainless steel, the mass content of Ni is 17.6~18.1%.

[0009] Furthermore, the nickel equivalent index is greater than or equal to 30 and less than or equal to 45.

[0010] Furthermore, in hydrogen-resistant austenitic stainless steel, the γ phase accounts for ≥99.5%.

[0011] To achieve the above objectives, according to one aspect of this application, a method for preparing hydrogen-embrittlement-resistant austenitic stainless steel is provided. The method includes: step S1, weighing raw materials according to the content of each component in the hydrogen-embrittlement-resistant austenitic stainless steel, mixing the raw materials and smelting them to obtain alloy steel liquid; step S2, casting the alloy steel liquid into slabs or ingots and subjecting them to homogenization heat treatment to obtain a billet to be rolled; step S3, hot-rolling the billet to be rolled to obtain a hot-rolled plate; step S4, solution treating the hot-rolled plate to obtain a solution-treated plate; and step S5, aging the solution-treated plate to obtain the hydrogen-embrittlement-resistant austenitic stainless steel.

[0012] Furthermore, in step S1, the smelting temperature is 1500~1540℃.

[0013] Furthermore, in step S2, the casting temperature is 1490~1525℃.

[0014] Furthermore, in step S2, the temperature of the heat treatment is 1100~1200℃, and the holding time of the heat treatment is 1~2h.

[0015] Further, in step S3, hot rolling includes preheating, primary rolling and final rolling in sequence; wherein, the preheating temperature is 1100~1200℃, the preheating holding time is 2~3h, the primary rolling temperature is 1100~1180℃, and the final rolling temperature is 920~980℃.

[0016] Furthermore, the hot rolling passes are 6 to 10, and the total rolling reduction rate is 70% to 88%.

[0017] Furthermore, a first cooling treatment is performed during the hot rolling process. The first cooling treatment is carried out by segmented laminar flow or spraying, and the first cooling rate is 5~30℃ / s.

[0018] Furthermore, in step S4, when the thickness of the hot-rolled plate is ≤12mm, the solution treatment temperature is 1040~1060℃ and the solution treatment holding time is 60~120min. When the thickness of the hot-rolled plate is greater than 12mm and ≤25mm, the solution treatment temperature is 1100~1130℃ and the holding time is 90~150min.

[0019] Furthermore, step S4 also includes a rapid cooling process following the solution treatment to obtain a solution-treated plate. The rapid cooling process includes water quenching, preferably by immediately immersing the solution-treated plate in water to rapidly cool it to room temperature.

[0020] Further, in step S5, the temperature for low-temperature aging treatment is 450~650℃, and the holding time for low-temperature aging treatment is 0.5~4h.

[0021] Furthermore, step S5 also includes a second cooling process performed after the low-temperature aging treatment, preferably air cooling.

[0022] According to a third aspect of this application, the application of the hydrogen-resistant austenitic stainless steel provided in the first aspect above, or the hydrogen-resistant austenitic stainless steel prepared according to the preparation method provided in the second aspect above, is provided in hydrogen storage equipment, hydrogen transportation equipment, high-pressure hydrogen containers, internal parts of hydrogen reactors, structural parts for high-pressure hydrogen environments, and lining materials for high-pressure hydrogen environments.

[0023] Applying the technical solution of this application, the hydrogen embrittlement-resistant austenitic stainless steel provided in this application takes the functional design of copper as its core innovation. While controlling the nickel content to 17.5–18.2% by mass, copper with a mass content of 1.8–2.5% is introduced to partially replace the nickel. This reduces alloy costs while improving hydrogen embrittlement resistance through the regulation of the material's microstructure and surface state by copper. Simultaneously, the hydrogen embrittlement-resistant austenitic stainless steel provided in this application introduces manganese with a mass content of 0.5–2.0% and nitrogen with a mass content of 0.05–0.25%. Utilizing the synergistic effect of copper with manganese and nitrogen, austenite stability is enhanced and deformation-induced martensitic transformation is suppressed. This maintains a stable austenitic structure while reducing nickel content, thus reducing the material's embrittlement sensitivity in hydrogen-containing environments. The result is a hydrogen embrittlement-resistant stainless steel design dominated by copper element regulation, balancing microstructure stability and economy. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0025] Figure 1 The XRD pattern of the hydrogen-resistant austenitic stainless steel provided in Example 1 of this application;

[0026] Figure 2 The EBSD (electron backscattering diffraction) phase diagram of the hydrogen-resistant austenitic stainless steel provided in Example 1 after hydrogen charging;

[0027] Figure 3 Stress-strain curves of stainless steel before and after hydrogen charging, provided for Example 1 and Comparative Example 1. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.

[0029] As analyzed in the background section of this application, traditional austenitic stainless steels such as 310S and 316L exhibit excellent stability in various hydrogen environments. However, traditional austenitic stainless steels typically contain a high proportion of nickel, and the market price of nickel fluctuates significantly, accounting for a large share of the total material cost, leading to increasingly prominent material cost issues. To reduce the nickel content while ensuring the structural stability and hydrogen resistance of austenitic stainless steel, this application provides a hydrogen-embrittlement-resistant austenitic stainless steel, its preparation method, and its applications.

[0030] In a first typical embodiment of this application, this application provides a hydrogen embrittlement-resistant austenitic stainless steel, which, by mass percentage, comprises the following components: C: 0.02-0.08%, Cr: 24.0-26.5%, Ni: 17.5-18.2%, Cu: 1.8-2.5%, Mn: 0.5-2.0%, Si: 0.3-1.0%, N: 0.05-0.25%, Al: 0.01-0.10%, S < 0.01%, P < 0.01%, with the balance being Fe and unavoidable impurities.

[0031] In this application, the total content of unavoidable impurities is ≤0.5%, and the content of a single impurity element is <0.01%.

[0032] The hydrogen embrittlement-resistant austenitic stainless steel provided in this application takes the functional design of copper as its core innovation. While controlling the nickel content to 17.5–18.2% by mass, copper with a mass content of 1.8–2.5% is introduced to partially replace the nickel. This reduces alloy costs while improving hydrogen embrittlement resistance through the regulation of the material's microstructure and surface state by copper. Simultaneously, the hydrogen embrittlement-resistant austenitic stainless steel provided in this application introduces manganese with a mass content of 0.5–2.0% and nitrogen with a mass content of 0.05–0.25%. Utilizing the synergistic effect of copper with manganese and nitrogen, austenite stability is enhanced and deformation-induced martensitic transformation is suppressed. This maintains a stable austenitic structure while reducing nickel content, thus reducing the material's embrittlement sensitivity in hydrogen-containing environments. The result is a hydrogen embrittlement-resistant austenitic stainless steel that is primarily controlled by copper, balancing microstructure stability and economy.

[0033] Compared with the widely used 310S austenitic stainless steel, the hydrogen embrittlement resistant austenitic stainless steel provided in this application has the following advantages:

[0034] (1) In the hydrogen embrittlement resistant austenitic stainless steel provided in this application, the mass content of nickel is controlled at 17.5~18.2%, and copper with a mass content of 1.8~2.5% is introduced for alloying design. While reducing the dependence on nickel, the material performance and cost control requirements are taken into account, and it has broad application prospects.

[0035] (2) The hydrogen-resistant austenitic stainless steel provided in this application has a volume ratio of up to 99.9% of the austenitic phase after hydrogen charging, and no obvious martensite phase is observed to form, which shows excellent resistance to hydrogen-induced phase transformation.

[0036] (3) The hydrogen embrittlement resistant austenitic stainless steel provided in this application still maintains excellent mechanical properties and plasticity retention in a hydrogen-containing environment. Its elongation at break remains stable, and its hydrogen embrittlement sensitivity index is much lower than that of 310S austenitic stainless steel. It has hydrogen embrittlement resistance that is significantly better than that of 310S stainless steel.

[0037] In the hydrogen embrittlement-resistant austenitic stainless steel provided in this application, the mass content of C, by mass percentage, is 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, or any range of two such values; the mass content of Cr is 24.0%, 24.2%, 24.5%, 24.8%, 25.0%, 25.2%, 25.5%, 25.8%, 26.0%, 26.2%, 26.5%, or any two such values. The range of values; Ni mass content is 17.5%, 17.6%, 17.7%, 17.8%, 17.9%, 18.0%, 18.1%, 18.2% or any two values; Cu mass content is 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.4%, 2.5% or any two values; Mn mass content is 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1 The mass content of Si is 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or any two values; the mass content of N is 0.05%, 0.08%, 0.10%, 0.12%, 0.15%, 0.18%, 0.20%, 0.22%, 0.25%, or any two values; the mass content of Al is 0. The mass content of S is 0.001%, 0.002%, 0.05%, 0.08%, 0.10%, or any two of these values; the mass content of S is 0.001%, 0.002%, 0.003%, 0.005%, 0.008%, 0.009%, or any two of these values; the mass content of P is 0.001%, 0.002%, 0.003%, 0.005%, 0.008%, 0.009%, or any two of these values.

[0038] In some embodiments of this application, in order to further improve the cleanliness of the hydrogen embrittlement resistant austenitic stainless steel and reduce the adverse effects of impurities, inclusions and impurity elements on the material's plasticity and hydrogen resistance, it is preferred that the content of S in the hydrogen embrittlement resistant austenitic stainless steel is ≤0.006% and the content of P is ≤0.006%, so as to further improve the material's structural stability and hydrogen embrittlement resistance.

[0039] In some embodiments of this application, when the mass content of Cu in the hydrogen-embrittled austenitic stainless steel is 1.9~2.3%, it can further improve the material's structural stability and mechanical property retention in a hydrogen-containing environment.

[0040] In some embodiments of this application, when the mass content of Ni in the hydrogen embrittlement resistant austenitic stainless steel is 17.6~18.1%, it is possible to maintain a stable austenitic structure while reducing material costs and reducing the catalytic sensitivity of the material in a hydrogen-containing environment.

[0041] In some embodiments of this application, the equivalent index of nickel in the hydrogen embrittlement-resistant austenitic stainless steel is greater than or equal to 30 and less than or equal to 45, in order to increase the volume content of the austenitic phase in the material microstructure, thereby further improving the stability of the material and reducing the hydrogen diffusion coefficient. Specifically, in the hydrogen embrittlement-resistant austenitic stainless steel, the equivalent index of nickel is 30, 32, 35, 38, 40, 42, 45 or any range of two values.

[0042] In this application, the nickel equivalent index is an indicator that reflects the degree of austenite formation in the stainless steel structure. Its value is calculated based on the austenitic elements (such as nickel, carbon, manganese, etc.) contained in the structure, according to the intensity of their austenitic effect, into the equivalent of a certain number of nickel units.

[0043] In some embodiments of this application, the volume content of the austenitic phase in the hydrogen embrittlement resistant austenitic stainless steel is ≥99.5%, or the proportion of the γ phase is ≥95%, so as to further improve the microstructure stability and hydrogen embrittlement resistance of the hydrogen embrittlement resistant austenitic stainless steel.

[0044] In a second typical embodiment of this application, a method for preparing the above-mentioned hydrogen embrittlement-resistant austenitic stainless steel is also provided. The method includes: step S1, weighing raw materials according to the content of each component in the hydrogen embrittlement-resistant austenitic stainless steel, mixing the raw materials and smelting them to obtain alloy steel liquid; step S2, casting the alloy steel liquid into slabs or ingots and subjecting them to homogenization heat treatment to obtain billets to be rolled; step S3, hot rolling the billets to be rolled sequentially to obtain hot-rolled plates; step S4, solution treating the hot-rolled plates to obtain solution-treated plates; and step S5, aging the solution-treated plates to obtain hydrogen embrittlement-resistant austenitic stainless steel.

[0045] The method for preparing hydrogen-embrittled austenitic stainless steel provided in this application is simple, easy to control, and applicable to industrial production, further reducing preparation costs.

[0046] In some embodiments of this application, in step S1, the smelting temperature is 1500~1540℃ to further improve smelting efficiency and promote the uniform distribution of each component in the material. Specifically, the smelting temperature is 1500℃, 1510℃, 1520℃, 1530℃, 1540℃ or any range of two values.

[0047] In some specific embodiments of this application, step S1 includes: weighing raw materials according to the content of each component in the hydrogen embrittlement resistant austenitic stainless steel, smelting the raw materials sequentially, using vacuum induction smelting or electric arc furnace smelting, followed by heating, desulfurization, composition fine-tuning, slag refining and vacuum degassing, deep decarburization, uniform composition temperature, and high-purity refining to control impurities such as O, S and P under vacuum degassing for 12 minutes to reduce the oxygen content to below 20 ppm, thereby obtaining alloy steel liquid; wherein, desulfurization, composition fine-tuning, slag refining and vacuum degassing, deep decarburization, uniform composition temperature, and high-purity vacuum degassing are all conventional operations in the art.

[0048] In some embodiments of this application, in step S2, the casting temperature is 1490~1525℃ to further improve casting efficiency. Specifically, the casting temperature for casting molten alloy steel into slabs or ingots is 1490℃, 1495℃, 1500℃, 1505℃, 1510℃, 1515℃, 1520℃, 1525℃, or any range of two such values.

[0049] In some embodiments of this application, in step S2, the temperature of the heat soaking treatment is 1100~1200℃, and the holding time of the heat soaking treatment is 1~2h, so as to further improve the efficiency of the heat soaking treatment. Specifically, the temperature of the heat soaking treatment is 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, 1190℃, 1200℃ or any two of these values, and the holding time of the heat soaking treatment is 1h, 1.2h, 1.5h, 1.8h, 2h or any two of these values.

[0050] In some embodiments of this application, hot rolling includes sequential preheating, primary rolling, and final rolling. The preheating temperature is 1100-1200℃, the preheating holding time is 2-3 hours, the primary rolling temperature is 1100-1180℃, and the final rolling temperature is 920-980℃, to further improve the efficiency of hot rolling and the production efficiency of hot-rolled sheets. Specifically, the preheating temperature is 1100℃, 1110℃, 1120℃, 1150℃, 1180℃, 1200℃, or any two of these values; the preheating holding time is 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, 3 hours, or any two of these values; the primary rolling temperature is 1100℃, 1120℃, 1150℃, 1180℃, or any two of these values; and the final rolling temperature is 920℃, 930℃, 950℃, 980℃, or any two of these values.

[0051] In some embodiments of this application, the number of hot rolling passes is 6 to 10, and the total rolling reduction rate is 70% to 88% to further improve the efficiency of hot rolling. Specifically, the number of hot rolling passes is 6, 7, 8, 9, 10, or any combination of two values; the total rolling reduction rate is 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, or any combination of two values.

[0052] In some embodiments of this application, a first cooling treatment is performed during the hot rolling process. The first cooling treatment is carried out by segmented laminar flow or spraying to achieve preliminary refinement of the grain and dislocation structure in the hot-rolled sheet. Preferably, the rate of the first cooling treatment is 5~30℃ / s to further promote the further refinement of the grain and dislocation structure in the hot-rolled sheet. Specifically, the first cooling rate is 5℃ / s, 8℃ / s, 10℃ / s, 15℃ / s, 20℃ / s, 25℃ / s, 30℃ / s, or any range of two values.

[0053] In some embodiments of this application, the solution treatment temperature and holding time vary depending on the thickness of the hot-rolled sheet. When the thickness of the hot-rolled sheet is ≤12mm, the solution treatment temperature is 1040~1060℃, and the holding time is 60~120min, which can form a uniform austenitic structure and dissolve harmful precipitates in the hot-rolled sheet. Specifically, when the thickness of the hot-rolled sheet is ≤12mm, the solution treatment temperature is 1040℃, 1045℃, 1050℃, 1055℃, 1060℃, or any two of these values; the holding time is 60min, 70min, 80min, 90min, 100min, 110min, 120min, or any two of these values.

[0054] In some embodiments of this application, when the thickness of the hot-rolled sheet is >12mm and ≤25mm, a solution treatment temperature of 1100~1130℃ and a solution treatment holding time of 90~150min are more conducive to forming a uniform austenitic structure and dissolving harmful precipitates in thicker hot-rolled sheets. Specifically, the solution treatment temperature is 1100℃, 1110℃, 1120℃, 1130℃ or any two of these values; the solution treatment holding time is 90min, 100min, 110min, 120min, 130min, 140min, 150min or any two of these values.

[0055] In some embodiments of this application, to further promote the formation of the austenite phase in the solution-treated sheet, a rapid quenching treatment is preferably performed after the solution treatment to obtain the solution-treated sheet. The rapid quenching method includes, but is not limited to, water quenching, and the preferred rapid quenching rate is 55~100℃ / s to further reduce harmful precipitated phases in the solution-treated sheet. Specifically, the rapid quenching rate is 65℃ / s, 75℃ / s, 85℃ / s, 95℃ / s, or any range of two values.

[0056] In step S5 above, the solution-treated plate is subjected to low-temperature aging treatment to promote the excellent distribution of copper elements in hydrogen-resistant austenitic stainless steel, thereby improving the material's structural stability and mechanical properties in a hydrogen-containing environment.

[0057] In some embodiments of this application, the low-temperature treatment temperature is 450~650℃, and the low-temperature aging treatment holding time is 0.5~4h, to further promote the enrichment of Cu element in the material and improve the material's resistance to hydrogen embrittlement and mechanical properties. Specifically, the low-temperature treatment temperature is 450℃, 480℃, 500℃, 520℃, 550℃, 580℃, 600℃, 620℃, 650℃, or any two of these values; the low-temperature aging treatment holding time is 0.5h, 0.8h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, or any two of these values.

[0058] In some embodiments of this application, step S5 further includes a second cooling treatment following the low-temperature aging treatment to obtain hydrogen-resistant austenitic stainless steel. The second cooling treatment may include, but is not limited to, air cooling. Air cooling is particularly beneficial for energy conservation.

[0059] In the third typical embodiment of this application, the application of the hydrogen-resistant austenitic stainless steel provided in the first typical embodiment or the hydrogen-resistant austenitic stainless steel obtained by the preparation method provided in the second typical embodiment is also provided in hydrogen storage equipment, hydrogen transportation equipment, high-pressure hydrogen containers, internal parts of hydrogen reactors, high-pressure pressure-partitioning structural parts or high-pressure pressure-partitioning lining materials is also provided.

[0060] The hydrogen embrittlement-resistant austenitic stainless steel provided in this application has a core innovation in the functional design of copper. While controlling the nickel content to 17.5–18.2% by mass, it introduces 1.8–2.5% copper by mass to partially replace the nickel. This reduces alloy costs while enhancing hydrogen embrittlement resistance through the regulation of the material's microstructure and surface state by copper. Simultaneously, the hydrogen embrittlement-resistant austenitic stainless steel provided in this application incorporates 0.5–2.0% manganese and 0.05–0.25% nitrogen by mass. Utilizing the synergistic effect of copper with manganese and nitrogen, it enhances austenite stability and inhibits deformation-induced martensitic transformation. This maintains a stable austenitic structure while reducing nickel content, thus reducing the material's embrittlement sensitivity in hydrogen-containing environments. This enables its application in hydrogen equipment, hydrogen transportation equipment, high-pressure hydrogen containers, hydrogen reactor internals, high-pressure hydrogen environment structural components, and high-pressure hydrogen environment lining materials.

[0061] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.

[0062] Example 1

[0063] This embodiment provides a hydrogen-embrittlement-resistant austenitic stainless steel, comprising the following elements by mass percentage: C 0.04%; Cr 25.1%; Ni 17.8%; Cu 2.1%; Mn 1.1%; Si 0.85%; N 0.13%; Al 0.05%; S 0.004%; P 0.005%; with the balance being Fe and unavoidable impurities.

[0064] The preparation method of the above-mentioned hydrogen embrittlement resistant austenitic stainless steel includes the following steps:

[0065] (1) Raw material and batching preparation: First, accurately weigh the raw materials according to the designed chemical composition. All raw materials should meet the metallurgical grade quality requirements and be pretreated to reduce inclusions. Strictly control the content of impurities such as sulfur and phosphorus. Through raw material selection and pretreatment, the sulfur content and phosphorus content are controlled within the specified range. Add the prepared raw materials to a vacuum induction furnace or electric arc furnace for melting. The furnace temperature is raised to 1520℃ and held for 15 minutes to ensure that all elements are completely melted. Then, refining and degassing are carried out to reduce the oxygen content to below 20ppm. The final tapping temperature is controlled at 1530℃ to obtain alloy steel liquid.

[0066] (2) Continuous casting and soaking treatment: Molten alloy steel is poured into a slab continuous casting machine under a protective atmosphere (nitrogen atmosphere). The pouring temperature is controlled at 1505℃ to ensure uniform composition and suppress segregation during solidification. Continuous casting yields a slab with a thickness of approximately 180 mm. After the slab cools naturally to room temperature, surface cleaning is performed to remove inclusions and oxide scale. The surface-cleaned slab is placed in a heating furnace and heated to 1180℃ and held for 2.5 hours to eliminate temperature gradients and achieve preliminary homogenization of chemical composition, resulting in the billet to be rolled.

[0067] (3) Hot rolling: The billet to be rolled enters the hot rolling process. Seven passes of hot rolling are used to make the cumulative reduction rate of the plate reach 82%. The temperature during the initial rolling is 1160℃ and the temperature during the final rolling is 950℃. After hot rolling, laminar flow cooling or spray cooling is used immediately to accelerate the cooling, so that the average cooling rate is about 18℃ / s. After cooling to below 200℃, air cooling is used to cool to room temperature to obtain a hot-rolled plate with a thickness of 12 mm. At the same time, the grains are refined and the dislocation structure is optimized through thermomechanical control.

[0068] (4) Solution treatment: The 12 mm thick hot-rolled plate is placed in a solution furnace and heated to 1050°C and held for 2 hours to dissolve the carbides and nitrides in the matrix and restore a uniform austenitic matrix structure. After the holding period, it is immediately cooled to room temperature by water quenching, so as to dissolve the alloying elements in the matrix and fix the required solid solution state, reducing the risk of harmful phase precipitation during subsequent processing or service, and obtaining a solution-treated plate.

[0069] (5) Low-temperature aging: The solution-treated plate was subjected to low-temperature aging treatment. The solution-treated plate was placed in a box furnace at 550℃ and held for 1 hour to promote the favorable distribution of Cu element in the matrix, thereby improving the material’s structural stability and mechanical property retention in a hydrogen-containing environment. After aging, it was naturally air-cooled to room temperature to obtain hydrogen-resistant austenitic stainless steel.

[0070] Example 2

[0071] The difference between this embodiment and Embodiment 1 is that the hydrogen-embrittlement-resistant austenitic stainless steel provided in this embodiment, by mass percentage, includes the following elements: C 0.02%; Cr 26.5%; Ni 17.5%; Cu 2.5%; Mn 0.5%; Si 1.0%; N 0.05%; Al 0.10%; S 0.006%; P 0.006%; with the balance being Fe and unavoidable impurities.

[0072] Example 3

[0073] The difference between this embodiment and Embodiment 1 is that the hydrogen-embrittlement-resistant austenitic stainless steel provided in this embodiment includes the following elements by mass percentage: C 0.08%; Cr 24.0%; Ni 18.2%; Cu 1.8%; Mn 2.0%; Si 0.3%; N 0.25%; Al 0.01%; S 0.006%; P 0.006%; with the balance being Fe and unavoidable impurities.

[0074] Comparative Example 1

[0075] This comparative example provides a commercially available 310S stainless steel.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that the mass content of Cu is 1.5%.

[0078] Comparative Example 3

[0079] The difference between this comparative example and Example 1 is that the mass content of Cu is 3.0%.

[0080] Experimental Example 1

[0081] The hydrogen-resistant austenitic stainless steel provided in Example 1 was subjected to X-ray diffraction testing, and the results are as follows: Figure 1 As shown, from Figure 1 As can be seen, in the XRD pattern of the hydrogen-embrittlement-resistant austenitic stainless steel provided in Example 1, obvious diffraction peaks appear near 43°, 50°, 74°, 90°, and 95°, corresponding to the characteristic peaks of the (111), (200), (220), (311), and (222) crystal planes of face-centered cubic austenite (γ phase), respectively. No obvious martensite or other harmful phase characteristic peaks were detected. This indicates that a stable austenitic phase has formed in the hydrogen-embrittlement-resistant austenitic stainless steel provided in Example 1.

[0082] Experimental Example 2

[0083] The stainless steels provided in the above embodiments and comparative examples were tested for yield strength, tensile strength and elongation at break before and after hydrogen charging, respectively. The hydrogen embrittlement sensitivity index was calculated based on the elongation at break, and the results are shown in Table 1 below.

[0084] Among them, (1) the specific operation steps of hydrogen charging are as follows: the sample is charged with hydrogen using a high-temperature gas phase hydrogen charging experimental platform. The experimental platform includes a resistance furnace, a closed reaction chamber set in the resistance furnace, a gas introduction unit, a vacuum measurement unit and a vacuum pumping unit; the vacuum measurement unit includes a thin film gauge and an ion gauge, the vacuum pumping unit includes a mechanical pump and a molecular pump, and the gas introduction unit is connected to the hydrogen source through an angle valve and a needle valve. The sample after surface pretreatment is placed evenly in the closed reaction chamber to ensure that the samples do not overlap. After the reaction chamber is closed, the mechanical pump and the molecular pump are started to evacuate the system; then high-purity H2 is introduced for circulation replacement for several minutes. After the atmosphere is stable, the reaction chamber is heated to 673 K and kept at the set time (4h). After the heat preservation is completed, the heating is stopped and the sample is cooled to room temperature in the hydrogen atmosphere. The sample is taken out immediately after cooling and subjected to room temperature tensile test and related performance characterization. The hydrogen charging medium was high-purity hydrogen (purity ≥99.9%), the charging temperature was 673K, and the charging time was 4h. After the hydrogen charging was completed, the test sample was cooled to room temperature in the furnace under nitrogen protection.

[0085] (2) The test methods for yield strength, tensile strength and elongation at break are as follows: After cutting and polishing, the specimen is subjected to a room temperature uniaxial tensile test according to the slow strain rate tensile test method. The test can be carried out with reference to ISO 7539-7, and the tensile strain rate is set to 5×10. -4 s -1 The testing equipment used was an electronic universal testing machine. During the test, the load-displacement data of the specimen was recorded and converted into an engineering stress-strain curve. The yield strength was determined using the 0.2% specified plastic extension method, the tensile strength was taken as the maximum engineering stress, and the elongation at break was calculated based on the change in gauge length after fracture. Unless otherwise specified, each working condition was tested at least three times to ensure the reliability of the test results.

[0086] (3) The method for calculating the hydrogen embrittlement sensitivity index is as follows:

[0087] The hydrogen embrittlement sensitivity index is characterized by the decrease in elongation after fracture, where, The hydrogen embrittlement sensitivity index. The elongation at break is the value of the uncharged hydrogen sample. This represents the elongation at break of the hydrogen-charged sample. When the value is positive, it indicates that the elongation after fracture decreases after hydrogen charging, and the material exhibits a loss of plasticity; The higher the value, the higher the hydrogen embrittlement sensitivity of the material.

[0088] Table 1

[0089]

[0090] Figure 2 The EBSD (electron backscattering diffraction) phase diagram of the hydrogen-resistant austenitic stainless steel provided in Example 1 after hydrogen charging is shown below. Figure 2 It can be seen that the hydrogen embrittlement resistant austenitic stainless steel provided in Example 1 still has an austenitic phase ratio of 99.9% (volume ratio) after hydrogen charging, and no obvious martensite phase is observed to form. This indicates that the hydrogen embrittlement resistant stainless steel provided in the example still has excellent austenitic structure stability under hydrogen-containing conditions.

[0091] Figure 3 The stress-strain curves of the stainless steel provided in Example 1 and Comparative Example 1 before and after hydrogen charging are shown below. 310S-RT represents the stress-strain curve of the 310S stainless steel provided in Comparative Example 1 before hydrogen charging; 310S-H represents the stress-strain curve of the 310S stainless steel provided in Comparative Example 1 after hydrogen charging; LHAS-RT represents the stress-strain curve of the hydrogen-resistant austenitic stainless steel provided in Example 1 before hydrogen charging; and LHAS-H represents the stress-strain curve of the hydrogen-resistant austenitic stainless steel provided in Example 1 after hydrogen charging. Figure 3 It can be seen that the hydrogen embrittlement-resistant austenitic stainless steel provided in Example 1 of this application still maintains high load-bearing capacity and relatively stable plastic deformation capacity after hydrogen charging, and does not exhibit obvious early cracking or sudden instability characteristics. This shows that the hydrogen embrittlement-resistant austenitic stainless steel provided in Example 1, after reducing the Ni content and introducing Cu element, can still maintain good strength-plasticity matching and excellent hydrogen embrittlement resistance under hydrogen-containing conditions.

[0092] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0093] The hydrogen embrittlement-resistant austenitic stainless steel provided in this application takes the functional design of copper as its core innovation. While controlling the nickel content to 17.5–18.2% by mass, copper with a mass content of 1.8–2.5% is introduced to partially replace the nickel. This reduces alloy costs while improving hydrogen embrittlement resistance through the regulation of the material's microstructure and surface state by copper. Simultaneously, the hydrogen embrittlement-resistant austenitic stainless steel provided in this application introduces manganese with a mass content of 0.5–2.0% and nitrogen with a mass content of 0.05–0.25%. Utilizing the synergistic effect of copper with manganese and nitrogen, austenite stability is enhanced and deformation-induced martensitic transformation is suppressed. This maintains a stable austenitic structure while reducing nickel content, thus reducing the material's embrittlement sensitivity in hydrogen-containing environments. The result is a hydrogen embrittlement-resistant austenitic stainless steel that is primarily controlled by copper, balancing microstructure stability and economy.

[0094] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A hydrogen-embrittlement-resistant austenitic stainless steel, characterized in that, The hydrogen embrittlement resistant austenitic stainless steel comprises the following components by weight percentage: C: 0.02-0.08%, Cr: 24.0-26.5%, Ni: 17.5-18.2%, Cu: 1.8-2.5%, Mn: 0.5-2.0%, Si: 0.3-1.0%, N: 0.05-0.25%, Al: 0.01-0.10%, S < 0.01%, P < 0.01%, with the balance being Fe and unavoidable impurities.

2. The hydrogen-embrittlement-resistant austenitic stainless steel according to claim 1, characterized in that, In the hydrogen embrittlement resistant austenitic stainless steel, the mass content of S is ≤0.006% and the mass content of P is ≤0.006%.

3. The hydrogen-embrittlement-resistant austenitic stainless steel according to claim 1, characterized in that, The Cu content in the hydrogen embrittlement resistant austenitic stainless steel is 1.9-2.3% by mass percentage. And / or, in the hydrogen embrittlement resistant austenitic stainless steel, the mass content of Ni is 17.6~18.1%.

4. The hydrogen-embrittlement-resistant austenitic stainless steel according to any one of claims 1 to 3, characterized in that, The nickel equivalent index is greater than or equal to 30 and less than or equal to 45; And / or, in the hydrogen-resistant austenitic stainless steel, the γ phase accounts for ≥99.5%.

5. A method for preparing a hydrogen-embrittlement-resistant austenitic stainless steel according to any one of claims 1 to 4, characterized in that, The preparation method includes: Step S1: Weigh the raw materials according to the content of each component in the hydrogen embrittlement resistant austenitic stainless steel, mix the raw materials and smelt them to obtain alloy steel liquid; Step S2: Cast the molten alloy steel into slabs or ingots and perform homogenization heat treatment to obtain the billet to be rolled. Step S3: The billet to be rolled is hot rolled to obtain a hot-rolled sheet. Step S4: The hot-rolled sheet is subjected to solution treatment to obtain a solution-treated sheet; Step S5: The solution-treated plate is subjected to aging treatment to obtain the hydrogen-resistant austenitic stainless steel.

6. The preparation method according to claim 5, characterized in that, In step S1, the smelting temperature is 1500~1540℃; And / or, in step S2, the casting temperature is 1490~1525℃; And / or, in step S2, the temperature of the heat treatment is 1100~1200℃, and the heat treatment holding time is 1~2h.

7. The preparation method according to claim 5, characterized in that, Step S3, the hot rolling includes preheating, primary rolling and final rolling in sequence; wherein, the preheating temperature is 1100~1200℃, the preheating holding time is 2~3h, the primary rolling temperature is 1100~1180℃, and the final rolling temperature is 920~980℃; Preferably, the hot rolling process involves 6 to 10 passes, and the total rolling reduction rate is 70% to 88%. Preferably, a first cooling treatment is performed during the hot rolling process. The first cooling treatment is performed by segmented laminar flow or spraying, and preferably the first cooling rate is 5~30℃ / s.

8. The preparation method according to any one of claims 5 to 7, characterized in that, In step S4, when the thickness of the hot-rolled sheet is less than or equal to 12 mm, the solution treatment temperature is 1040~1060℃ and the solution treatment holding time is 60~120 min; when the thickness of the hot-rolled sheet is greater than 12 mm and less than or equal to 25 mm, the solution treatment temperature is 1100~1130℃ and the solution treatment holding time is 90~150 min. Preferably, step S4 further includes a rapid cooling process performed after the solution treatment to obtain the solution-treated plate, wherein the rapid cooling process includes water quenching.

9. The preparation method according to any one of claims 5 to 7, characterized in that, In step S5, the temperature of the low-temperature aging treatment is 450~650℃, and the holding time of the low-temperature aging treatment is 0.5~4h. Preferably, step S5 further includes a second cooling process performed after the low-temperature aging treatment, wherein the second cooling process includes air cooling.

10. The application of a hydrogen-resistant austenitic stainless steel according to any one of claims 1 to 4, or a hydrogen-resistant austenitic stainless steel prepared according to any one of claims 5 to 9, in hydrogen storage equipment, hydrogen transportation equipment, high-pressure hydrogen containers, internal parts of hydrogen reactors, structural parts for high-pressure hydrogen environments, and lining materials for high-pressure hydrogen environments.

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