Austenitic stainless steel plate for hydrogen storage container and manufacturing method thereof

Abstract

The present invention discloses an austenitic stainless steel plate for a hydrogen storage container and a manufacturing method thereof, and belongs to the field of metal materials. The chemical composition weight percentages of the steel plate are as follows: C: 0.04-0.10%, Si: 0.10-0.40%, Mn: 2.00-3.00%, P: ≤0.020%, S: ≤0.005%, Cr: 10.00-15.00%, Ni: 9.50-10.50%, Mo: 1.50-2.50%, N: 0.20-0.50%, Nb: 1.50-2.00%, Zr: 0.50-1.00%, V: 0.10-0.50%, and the remainder is Fe and unavoidable impurities. The manufacturing method comprises: smelting and continuous casting-electroslag remelting-forging and homogenization-heating and rolling-heat treatment. The present invention improves the corrosion resistance and low-temperature toughness of the steel plate.

Description

Technical Field

[0001] The invention relates to the field of metal materials, and in particular to an austenitic stainless steel plate for a hydrogen storage container and a manufacturing method thereof. Background Art

[0002] At present, with the continuous development of the field of energy steel, the research on materials related to hydrogen energy storage and transportation has received more and more attention and concern. Because austenitic stainless steel has good corrosion resistance and excellent strength and toughness matching at room temperature and low temperature, it is generally considered to be a type of material suitable for pressure vessel steel plates used in hydrogen energy storage. Pressure vessel steel plates for hydrogen storage containers are used in complex conditions such as low temperature, high pressure and hydrogen. Moreover, with the continuous development of the industry, the development direction of equipment tends to be large-scale, high-performance, weight-reduced, and long-term service. This puts higher requirements on the raw materials for the manufacture of hydrogen storage equipment. The strength and toughness of traditional low-carbon alloy container steel plates can no longer meet the manufacturing requirements of high-end hydrogen storage pressure vessel equipment. In addition, the high content of residual ferrite in the material, the large grain size, and the corrosive environment in the application scenario will have an extremely adverse effect on the comprehensive performance of the material.

[0003] At present, there are few related patents in China, and the main ones related to this invention include the following:

[0004] (1) Publication No. CN116590630A "A low-cost austenitic stainless steel for high-pressure hydrogen storage and its preparation method" belongs to the field of material technology. In terms of weight percentage, the chemical composition of the austenitic stainless steel is: Cr: 18.0-25.0%, Mn: 6.0-12.0%, Ni: 4.0-10.0%, N: 0.15-0.45%, Se: 0.0001-0.01%, Si <1.0%, C <0.01%, Al <0.005%, Ca <0.005%, P <0.004%, S <0.002%, O <0.005%, and the balance is iron. The steel plate is heat treated for 10-20 hours. This method of heat treatment occupies a lot of resources and is not suitable for large-scale production applications. At the same time, the patent does not mention the low-temperature performance of the steel plate. In addition, the patent does not mention the intergranular corrosion problem that may exist in hydrogen storage application scenarios.

[0005] (2) Publication No. CN116479335A "A hot-rolled austenitic stainless steel for hydrogen storage valves and its manufacturing method": C: 0.03-0.06%, Si: 0.50-0.70%, Mn: 1.50-2.00%, Cr: 16.5-18.5%, Mo: 2.0-3.0%, Ni: 12-14%, Co: 0.20-0.40%, N: 0.030-0.060%, P: ≤0.015%, S: ≤0.002%, [O] ≤0.002%, [H] ≤0.0015%, B ≤0.0008%, and the rest are Fe and unavoidable impurities. The method is aimed at the manufacturing method of steel plates with a thickness of 30-40 mm, and no statement is made for steel plates with a thickness greater than 40 mm and less than 30 mm. At the same time, the patent does not mention the impact of residual ferrite in hydrogen storage austenitic stainless steel on the low-temperature performance of the material, and cannot guarantee the ultra-low temperature toughness of the material at -253°C. In addition, the patent also does not mention the intergranular corrosion problem that may exist in hydrogen storage application scenarios.

[0006] Therefore, it is urgent to develop an austenitic stainless steel plate for hydrogen storage containers having excellent low temperature performance and resistance to intergranular corrosion and a method for manufacturing the same. Summary of the invention

[0007] The purpose of the present invention is to provide an austenitic stainless steel plate for hydrogen storage containers and a method for manufacturing the same. The present invention aims to solve the key problems of mixed crystals, residual ferrite content and intergranular corrosion of austenitic stainless steel, and can regulate the structure and performance of the steel plate through appropriate composition, forging and homogenization process, rolling process and efficient heat treatment method.

[0008] In order to achieve the above object, the present invention provides an austenitic stainless steel plate for a hydrogen storage container, and the chemical composition weight percentage of the steel used is as follows:

[0009] C: 0.04-0.10%, Si: 0.10-0.40%, Mn: 2.00-3.00%, P: ≤0.020%, S: ≤0.005%, Cr: 10.00-15.00%, Ni: 9.50-10.50%, Mo: 1.50-2.50%, N: 0.20-0.50%, Nb: 1.50-2.00%, Zr: 0.50-1.00%, V: 0.10-0.50%, the balance is Fe and unavoidable impurities.

[0010] The effects of the above chemical elements are analyzed as follows:

[0011] C is an important element of austenitic stainless steel. It can expand the austenite zone and inhibit the formation of ferrite in the steel. In addition, the presence of C in the form of solid solution or carbide precipitation in the steel can effectively improve the room temperature and low temperature strength of the steel plate. However, too high C content not only increases the hardness of the heat affected zone of welding and cracking after reheating after welding, but also is not conducive to the intergranular corrosion resistance of the steel plate. Therefore, the C content is limited to 0.04-0.10%.

[0012] Si is the main deoxidizing element of austenitic stainless steel, which can effectively reduce the oxygen content in steel and improve the purity of steel. However, too high Si content will promote the formation of brittle σ phase or the precipitation of silicon-rich G phase at the grain boundary. Therefore, the Si content is limited to 0.10-0.40%.

[0013] Mn is an important element of austenitic stainless steel. It can expand the austenite zone and improve the strength of steel, but too high Mn content will affect the welding performance of the steel plate. Therefore, the Mn content is limited to 2.00-3.00%.

[0014] Ni is an important element of austenitic stainless steel. Ni can expand the austenite zone and inhibit the formation of ferrite in the steel. In addition, it is also beneficial to the low-temperature toughness of the steel plate. At the same time, it is used in combination with Cr to ensure that the steel plate has good oxidation and corrosion resistance. Due to its high price, the Ni content is limited to 9.50-10.50%.

[0015] Cr is an important element for oxidation resistance and corrosion resistance in austenitic stainless steel. In order to ensure that the steel plate of the present invention has excellent corrosion resistance, the grain boundary is prevented from 23 The precipitation of C6 carbides causes chromium-poor areas to appear near the grain boundaries, and excessive addition of C6 carbides will lead to carbide coarsening, which in turn reduces the strength and toughness of the steel plate. Therefore, the Cr content is limited to 10.00-15.00%.

[0016] Mo is an important element for improving high temperature strength and corrosion resistance in austenitic stainless steel. In addition, it has a strong affinity for P. It reduces the amount of P segregated at the grain boundary, which is beneficial to reduce the sensitivity of welding reheating cracking. Therefore, the Mo content is limited to 1.50-2.50%.

[0017] N is an important element in austenitic stainless steel. It stabilizes the austenite structure, improves strength and corrosion resistance (especially local corrosion resistance) without significantly damaging the toughness and plasticity of the steel. Therefore, the N content is limited to N: 0.20-0.50%.

[0018] Zr is the main element in steel that improves the strength and low-temperature toughness of steel plates. It precipitates in the form of carbides at the grain boundaries, strengthening the grain boundaries and thus improving the strength and toughness of the steel plates. At the same time, due to the large amount of precipitation of Zr carbides, the precipitation of Cr at the grain boundaries is inhibited, preventing the appearance of "chromium-poor areas" near the grain boundaries, and increasing the intergranular corrosion resistance of the steel plates. However, too high a Zr content will cause a decrease in the mechanical properties of the steel plates. Therefore, the Zr content is limited to 0.50-1.00%.

[0019] Nb precipitates in the form of carbides at the grain boundaries, thereby inhibiting the precipitation of Cr at the grain boundaries, preventing the appearance of "chromium-poor zones" near the grain boundaries, and increasing the intergranular corrosion resistance of the steel plate. In addition, it can also increase the recrystallization temperature of the steel, refine the grains of the steel, and increase the tensile strength and yield strength of the steel. However, too high a Nb content will cause embrittlement of the welded joint during welding, reducing the plasticity and toughness of the material. Therefore, the Nb content is limited to 1.50-2.00%.

[0020] The main function of V in steel is to improve the strength and toughness of the steel plate by refining the grains. Therefore, the V content is limited to 0.10-0.50%.

[0021] P and S are harmful elements of austenitic stainless steel. Theoretically, the lower their content, the better. However, excessive reduction will lead to a significant increase in manufacturing costs. Therefore, the P content is limited to ≤0.020% and the S content is limited to ≤0.005%.

[0022] Furthermore, the width of the austenitic stainless steel plate used for the hydrogen storage container is 2000-5000 mm and the thickness is 8-50 mm.

[0023] The present invention also provides a method for manufacturing the austenitic stainless steel plate for the hydrogen storage container. The process flow includes: smelting and continuous casting - electroslag remelting - forging and homogenization - heating and rolling - heat treatment. The specific steps are as follows:

[0024] (1) Smelting and continuous casting: Stainless steel is smelted by electric furnace smelting + AOD + VOD steelmaking method, and then slab continuous casting is carried out.

[0025] Furthermore, the casting temperature of the molten steel in the tundish is 1380-1410°C; the continuous casting billet pulling speed is 0.65-1.00m / min, the secondary cooling water is 5500-6200L / min, the superheat is 20-35°C, and the straightening temperature is 950~1000°C; the electromagnetic stirring is alternating forward and reverse stirring, the forward time is 10-20s, the reverse time is 4-6s, the current is 1200-1700A, and the frequency is 10-15Hz; the continuous casting billet light reduction rate is controlled at 6-8%.

[0026] (2) Electroslag remelting: The electroslag billet is produced using the continuous casting billet as the electrode, and argon gas protection is used throughout the production process.

[0027] Furthermore, the thickness of the electroslag billet is 200-550mm; the argon flow rate is 25-45m 3 / h; the current during the electroslag remelting process is 8000-30000A and the voltage is 80-110V.

[0028] (3) Forging and homogenization: The electroslag billet is first forged and then homogenized. During the forging stage, the billet is heated to 1200-1230℃ and kept warm for 10-15h. The billet is forged along the XYZ axis in sequence. The total deformation of the X axis is 10-15% of the original thickness of the billet, the total deformation of the Y axis is 10-15% of the original thickness of the billet, and the total deformation of the Z axis is 20-30% of the original thickness of the billet. The forged billet is kept at 600-645℃ for 2-3h and then water-cooled to room temperature. The main purpose of this process is to precipitate M 23 C6 cuts the large strip ferrite at the grain boundary into several small pieces of ferrite; in the homogenization stage, the billet is heated to 1265-1280℃ and kept warm for 110-140h. After the end of the warming, it is forged along the Z axis. The total deformation is 10-15% of the original thickness of the billet (before forging in the previous stage), ensuring that the billet has a fine original austenite structure before rolling.

[0029] Furthermore, during the forging process, the deformation amount is controlled within 15-20 mm each time.

[0030] (4) Heating and rolling: Billet heating is divided into preheating section, heating section and soaking section. The temperature range of the heating section is 1170-1200℃, the temperature range of the soaking section is 1150-1180℃, and the total time in the furnace is 120-180min. During the preheating section, when the billet is heated to 600℃, the heating rate is adjusted to ensure that the temperature rises to above 700℃ within 20-30min to prevent the precipitation of M at the grain boundary by staying in this temperature range for too long. 23 C6 has an adverse effect on the material's resistance to intergranular corrosion; a two-stage rolling method is used, the first stage (rough rolling stage) has a rolling temperature of ≥1140℃, a single-pass reduction rate of 15-20%, and a roller speed of 35-45r / min. After rolling, a laminar cooling system is used to cool the surface of the intermediate billet at a cooling rate of 15-23℃ / s, shortening the intermediate billet waiting time to prevent excessive growth of surface grains; the second stage (finishing rolling stage) has a rolling temperature of ≥900℃, a single-pass reduction rate of 5-8%, and a roller speed of 15-25r / min. After rolling, the steel plate is cooled with a cooling temperature of 700-740℃, a final cooling temperature of 550-600℃, and a cooling rate of 15-23℃ / s.

[0031] Furthermore, the thickness of the intermediate billet is 2-3 times that of the finished steel plate.

[0032] (5) Heat treatment: The steel plate is first subjected to solution treatment and then to stabilization treatment. The first stage (solid solution) treatment temperature is 1030-1050°C, the net holding time is 30-60 min, and the steel plate is water-cooled to room temperature after being taken out of the furnace. The second stage (stabilization) treatment temperature is 850-900°C, the net holding time is 20-50 min, and the steel plate is air-cooled to room temperature after being taken out of the furnace.

[0033] Beneficial effects of the present invention:

[0034] The present invention improves the room temperature and low temperature strength of the steel plate by adding a large amount of C and N elements, while reducing the content of precious metal element Ni in the steel, thereby greatly reducing the manufacturing cost of the steel plate; by adding Nb and Zr elements, the appearance of "chromium-poor zones" near the grain boundaries is avoided, further improving the corrosion resistance and low temperature toughness of the steel plate.

[0035] The present invention effectively controls the residual ferrite in the steel through forging and homogenization processes; ensures that no mixed crystals occur in the entire thickness interface of the steel plate through a special rolling process to ensure the room temperature and low temperature performance of the material; and improves the intergranular corrosion resistance of the steel plate through a heat treatment process.

[0036] The invention manufactures austenitic stainless steel plates for hydrogen storage containers with a steel plate width of 2000-5000 mm and a thickness of 8-50 mm. el ≥400MPa, R m ≥750MPa, A≥50%; R at -196℃ el ≥650MPa, KV2≥150J, LE≥0.75mm; R at -253℃ ultra-low temperature el ≥850MPa, KV2≥100J; ferrite content ≤1%, grain size 65-125μm; after sensitization treatment at 650℃×2h, it meets the requirements of GB / T4334-2018 "Corrosion of Metals and Alloys - Test Method for Intergranular Corrosion of Stainless Steel" E method, and at the same time, it meets the requirements of ASTMA262 "Standard Method for Detecting Intergranular Corrosion Susceptibility of Austenitic Stainless Steel" C method, and the average corrosion rate within five corrosion cycles is ≤3.0μm / 48h. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the crystal phase structure of the austenitic stainless steel plate for hydrogen storage container prepared in Example 3. DETAILED DESCRIPTION

[0038] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0039] Example

[0040] An austenitic stainless steel plate for a hydrogen storage container comprises the following components and their weight percentages: C: 0.04-0.10, Si: 0.10-0.40%, Mn: 2.00-3.00%, P: ≤0.020%, S: ≤0.005%, Cr: 10.00-15.00%, Ni: 9.50-10.50%, Mo: 1.50-2.50%, N: 0.20-0.50%, Nb: 1.50-2.00%, Zr: 0.50-1.00%, V: 0.10-0.50%, and the balance is Fe and unavoidable impurities. The specific chemical compositions of Examples 1-15 are shown in Table 1.

[0041] The manufacturing method of the austenitic stainless steel plate for the hydrogen storage container includes the following process flow: smelting and continuous casting - electroslag remelting - forging and homogenization - heating and rolling - heat treatment; the specific steps are as follows:

[0042] (1) Smelting and continuous casting: Stainless steel was smelted by electric furnace smelting + AOD + VOD steelmaking method, and then slab continuous casting was performed. The tundish molten steel casting temperature was 1380-1410°C; the continuous casting billet pulling speed was 0.65-1.00 m / min, the secondary cooling water was 5500~6200 L / min, the superheat was 20-35°C, and the straightening temperature was 950-1000°C; the electromagnetic stirring was alternating forward and reverse stirring, the forward time was 10-20s, the reverse time was 4-6s, the current was 1200-1700A, and the frequency was 10-15Hz; the continuous casting billet soft reduction rate was controlled at 6-8%. The specific smelting and continuous casting parameters in Examples 1-15 are shown in Table 2.

[0043] (2) Electroslag remelting: The continuous casting billet is used as the electrode to produce electroslag billets with a thickness of 200-550 mm. Argon protection is used throughout the production process, with an argon gas flow rate of 25-45m 3 / h. The current during the electroslag remelting process is 8000-30000A, and the voltage is 80-110V. The specific electroslag remelting parameters in Examples 1-15 are shown in Table 3.

[0044] (3) Forging and homogenization: During the forging stage, the billet is heated to 1200-1230°C and kept warm for 10-15 hours. The billet is forged in the XYZ axis direction in sequence, and the deformation amount is controlled at 15-20 mm each time. The total deformation of the X axis is 10-15% of the original thickness of the billet, the total deformation of the Y axis is 10% of the original thickness of the billet, and the total deformation of the Z axis is 20% of the original thickness of the billet. The forged billet is kept warm at 600-645°C for 2-3 hours and then water-cooled to room temperature. During the homogenization stage, the billet is heated to 1265-1280°C and kept warm for 110-120 hours. After the end of the insulation, the billet is forged along the Z axis, and the total deformation is 10% of the original thickness of the billet (before forging in the previous stage). The specific forging and homogenization parameters in Examples 1-15 are shown in Table 3.

[0045] (4) Heating and rolling: The billet heating is divided into preheating section, heating section and soaking section. The temperature range of the heating section is 1170-1200℃, the temperature range of the soaking section is 1150-1180℃, and the total time in the furnace is 120-180min. During the preheating section, when the billet is heated to 600℃, the heating rate is adjusted to ensure that it is heated to 710℃ within 20-30min. A two-stage rolling method is adopted. In the first stage, the starting rolling temperature is ≥1140℃, the single-pass reduction rate is 15-20%, and the roller speed is controlled at 35-45r / min. After rolling, the laminar cooling system is used to cool the surface of the intermediate billet at a cooling rate of 15-23℃ / s. In the second stage, the starting rolling temperature is ≥900℃, the single-pass reduction rate is 5-8%, and the roller speed is controlled at 15-25r / min. After rolling, the steel plate is subjected to controlled cooling, with the initial cooling temperature being 700-740°C, the final cooling temperature being 550-600°C, and the cooling rate being 15-23°C / s. Specific heating and rolling parameters in Examples 1-6 are shown in Table 4.

[0046] (5) Heat treatment: The steel plate adopts a solution + stabilization treatment process. The first stage heat treatment temperature is 1030-1050°C, the net holding time is 30-60 minutes, and the steel is water-cooled to room temperature after being taken out of the furnace; the second stage temperature is 850-900°C, the net holding time is 20-50 minutes, and the steel is air-cooled to room temperature after being taken out of the furnace. The specific heat treatment parameters in Examples 1-15 are shown in Table 5.

[0047] Table 1 Chemical composition of the examples (wt%)

[0048]

[0049] Table 2 Smelting and continuous casting parameters of the embodiment

[0050]

[0051] Table 3 Electroslag remelting, forging and homogenization parameters of the embodiment

[0052]

[0053] Table 4 Rolling parameters of the embodiment

[0054]

[0055] Table 5 Heat treatment parameters of the examples

[0056]

[0057] Table 6 Mechanical properties of examples

[0058]

[0059] Table 7 Microstructure and corrosion performance of the examples

[0060]

[0061] like Figure 1 As shown, the austenitic stainless steel plate for hydrogen storage container prepared in Example 3 has uniform grains and no mixed crystals.

Claims

1. A method for manufacturing an austenitic stainless steel plate for a hydrogen storage container, characterized in that: The chemical composition weight percentage of the steel plate is as follows: C: 0.04-0.10%, Si: 0.10-0.40%, Mn: 2.00-3.00%, P: ≤0.020%, S: ≤0.005%, Cr: 10.00-15.00%, Ni: 9.50-10.50%, Mo: 1.50-2.50%, N: 0.20-0.50%, Nb: 1.50-2.00%, Zr: 0.50-1.00%, V: 0.10-0.50%, the balance is Fe and unavoidable impurities; The method for manufacturing the austenitic stainless steel plate for the hydrogen storage container comprises the following steps: (1) Smelting and continuous casting: Stainless steel is smelted by electric furnace smelting + AOD + VOD steelmaking method, and then slab continuous casting is carried out; (2) Electroslag remelting: The electroslag billet is produced using the continuous casting billet as the electrode, and argon gas protection is used throughout the production process; (3) Forging and homogenization: The electroslag billet is first forged and then homogenized; Forging stage: the billet is heated to 1200-1230℃ and kept warm for 10-15h. The billet is forged along the XYZ axis. The total deformation of the X axis is 10-15% of the original thickness of the billet, the total deformation of the Y axis is 10-15% of the original thickness of the billet, and the total deformation of the Z axis is 20-30% of the original thickness of the billet. The forged billet is kept warm at 600-645℃ for 2-3h and then water-cooled to room temperature. Homogenization stage: the billet is heated to 1265-1280℃ and kept warm for 110-140h. After the end of the warming period, forging is carried out along the Z axis. The total deformation is 10-15% of the original thickness of the billet before forging in the previous stage. (4) Heating and rolling: The heating of the billet is divided into preheating section, heating section and soaking section. The temperature range of the heating section is 1170-1200℃, the temperature range of the soaking section is 1150-1180℃, and the total time in the furnace is 120-180min. During the preheating section, when the billet is heated to 600℃, the heating rate is adjusted to ensure that the temperature rises to above 700℃ within 20-30min. A two-stage rolling method is adopted. The starting rolling temperature of the rough rolling stage is ≥1140℃, the single-pass reduction rate is 15-20%, and the roller speed is controlled at 35-45r / min to obtain the intermediate billet. The starting rolling temperature of the finishing rolling stage is ≥900℃, the single-pass reduction rate is 5-8%, and the roller speed is controlled at 15-25r / min. After rolling, the steel plate is controlled to cool, with the starting cooling temperature of 700-740℃ and the final cooling temperature of 550-600℃. (5) Heat treatment: The steel plate is first subjected to solution treatment and then to stabilization treatment; the temperature of the solution treatment is 1030-1050°C, the net holding time is 30-60 minutes, and the steel plate is water-cooled to room temperature after being taken out of the furnace; the temperature of the stabilization treatment is 850-900°C, the net holding time is 20-50 minutes, and the steel plate is air-cooled to room temperature after being taken out of the furnace; The hydrogen storage container is made of austenitic stainless steel plate, R el ≥400MPa, R m ≥750MPa, A≥50%; -196℃ low temperature R el ≥650MPa, KV2≥150J, LE≥0.75mm; R at -253℃ ultra-low temperature el ≥850MPa, KV2≥100J; ferrite content ≤1%, grain size 65-125μm; after sensitization treatment at 650℃×2h, it meets the requirements of GB / T4334-2018 "Corrosion of Metals and Alloys - Test Method for Intergranular Corrosion of Stainless Steel" E method, and at the same time, it meets the requirements of ASTMA262 "Standard Method for Detecting Intergranular Corrosion Susceptibility of Austenitic Stainless Steel" C method, and the average corrosion rate within five corrosion cycles is ≤3.0μm / 48h.

2. The manufacturing method according to claim 1, characterized in that: The austenitic stainless steel plate for the hydrogen storage container has a width of 2000-5000 mm and a thickness of 8-50 mm.

3. The manufacturing method according to claim 1, characterized in that: In step (2), the thickness of the electroslag billet is 200-550 mm; the argon gas flow rate is 25-45 m 3 / h; the current during the electroslag remelting process is 8000-30000A and the voltage is 80-110V.

4. The manufacturing method according to claim 1, characterized in that: In step (3), during the forging process, the deformation amount in the X-axis is controlled within 15-20 mm, the deformation amount in the Y-axis is controlled within 15-20 mm, and the deformation amount in the Z-axis is controlled within 15-20 mm.

5. The manufacturing method according to claim 1, characterized in that: In step (4), laminar cooling is performed between rough rolling and finish rolling, with a cooling rate of 15-23°C / s.

6. The manufacturing method according to claim 1, characterized in that: In step (4), the thickness of the intermediate billet is 2-3 times that of the finished steel plate.

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