300 series stainless steel sheet for hydrogen storage equipment and method for manufacturing the same

Abstract

The application provides a 300 series stainless steel plate for hydrogen storage equipment and a manufacturing method thereof. The steel plate comprises the following components in percentage by weight: C: 0.02%-0.034%, Si: 0.64%-0.98%, Mn: 2.11%-2.64%, P: ≤0.015%, S: ≤0.01%, Cr: 20.4%-22.8%, Ni: 5.2%-9.8%, Mo: 0.12%-0.14%, Ti: 0.014%-0.027%, Cb: 0.0015%-0.0042%, Alt: 0.020%-0.045%, Ti / Cb=5-15, and the balance of Fe and inevitable inclusions. The production method of the steel plate comprises smelting, slab continuous casting, heating, rolling, hot straightening and heat treatment. The steel plate has the following properties under room temperature conditions: 260MPa≤Rel≤350MPa, 540MPa≤Rm≤696Mpa and A%≥40; under-196 ℃ conditions: 360MPa≤Rel≤510MPa, 1050MPa≤Rm≤1120Mpa and KV2≥150J, and the steel plate has excellent intergranular corrosion resistance and pitting corrosion resistance. The microstructure of the steel plate is fine austenite structure, the grain size is 4-6, and the thickness of the steel plate is 20-100 mm.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials, and in particular relates to a 300 series stainless steel plate for hydrogen storage equipment and a method for manufacturing it. Background Technology

[0002] Currently, 300 series stainless steel, mainly referring to Cr-Ni series stainless steel, is the most widely used type of stainless steel. Among them, 304 series and 316 series are commonly used in pressure equipment applications. 300 series stainless steel plates possess high corrosion resistance, heat resistance, oxidation resistance, and toughness; however, due to the presence of Cr in its composition, and the high affinity of Cr for oxygen, Cr-rich Cr deposits easily precipitate at grain boundaries. 23 C6 leads to chromium-depleted zones in the surrounding matrix, creating corrosion cells and causing intergranular corrosion. Furthermore, due to the environmental requirements of pressure vessel steel plates used in hydrogen storage, the performance and manufacturing methods of traditional stainless steel for pressure equipment are no longer sufficient to meet the strength and toughness requirements of steel plates under ultra-low temperature operating conditions. Therefore, there is an urgent need to develop a production method for 300 series stainless steel plates used in hydrogen storage to solve this problem.

[0003] Hydrogen energy is a crucial means to support the clean energy transformation of fossil fuels and the large-scale development of renewable energy. Looking at the development trend of hydrogen energy, hydrogen technology has become a disruptive energy technology leading a new generation of industrial transformation, and it is of great significance for building a clean, low-carbon, safe, and efficient energy system. Therefore, the development of stainless steel plates for hydrogen energy storage and utilization has become a recent research focus and has attracted increasing attention.

[0004] The invention patent "A High-Strength Twisted Induced Plastic Austenitic Stainless Steel Resistant to Intergranular Corrosion" (CN112458367A) describes a steel plate composed of the following weight percentages: C ≤ 0.02%, Si: 1.00%–3.00%, Mn: 22.00%–28.00%, P ≤ 0.015%, S ≤ 0.010%, Ni: 2.00%–4.00%, Cr: 16.00%–20.00%, N: 0.4%–0.8%, with the balance being Fe and unavoidable impurities. With the above composition, after solution treatment at 1050℃–1150℃, a significant TWIP effect can be generated under cold deformation of not less than 5%, resulting in a high-strength and highly corrosion-resistant stainless steel. The study only discussed the room temperature strength and corrosion resistance of the example steel plates, and did not study the low temperature performance or even the cryogenic and ultra-low temperature performance below -196℃, which does not meet the design requirements for steel plates used in hydrogen storage equipment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to prepare a 300 series stainless steel plate for hydrogen storage devices. This invention utilizes a novel chemical composition design, a highly efficient homogeneous heat treatment process, and a two-stage rolling process to achieve a room-temperature Ro of the steel plate. m ≥540Mpa, A≥40%; under -196℃ condition, R m Steel plates with a thickness of (20-100) mm and a transverse impact energy of ≥1050 MPa and KV2≥150 J, meaning excellent strength, low-temperature toughness, formability, and shape, meet the manufacturing and application requirements of high-performance hydrogen storage equipment.

[0006] The objective of this invention is achieved as follows:

[0007] A 300 series stainless steel plate for a hydrogen storage device has the following chemical composition: C: 0.02%–0.034%, Si: 0.64%–0.98%, Mn: 2.11%–2.64%, P: ≤0.015%, S: ≤0.01%, Cr: 20.4%–22.8%, Ni: 5.2%–9.8%, Mo: 0.12%–0.14%, Ti: 0.014%–0.027%, Cb: 0.0015%–0.0042%, Alt: 0.020%–0.045%, with the balance being Fe and unavoidable inclusions.

[0008] Furthermore, the Ti / Cb ratio is 5 to 15.

[0009] Furthermore, the steel plate has the following properties at room temperature: 0~25℃: 260MPa≤Rel≤350MPa, 540MPa≤Rm≤696MPa, A%≥40; and at -196℃: 360MPa≤Rel≤510MPa, 1050MPa≤Rm≤1120MPa, KV2≥150J.

[0010] Furthermore, the microstructure of the steel plate is a refined austenitic structure with a grain size of 4 to 6.

[0011] Furthermore, the thickness of the steel plate is 20–100 mm.

[0012] The rationale for the design of the components in this invention is as follows:

[0013] The reasons for limiting the amounts of each chemical element (C, Si, Mn, P, S, Cr, Ni, Mo, Ti, Cb, and Al) in steel plates are detailed below:

[0014] C: 0.02%~0.034%

[0015] Carbon (C) is the most important element for increasing the strength of steel. Its combination with strong carbide alloying elements in steel plays a role in precipitation strengthening. However, excessively high carbon content can affect the machinability of steel, and supersaturated carbides can also affect the low-temperature toughness of steel plates. Therefore, this invention sets the C content range to 0.02% to 0.034%.

[0016] Si: 0.64%~0.98%

[0017] In steelmaking, silicon (Si) acts as a reducing agent and deoxidizer. Si is also an inexpensive alloying element; adding an appropriate amount of Si to steel, which dissolves in austenite, can improve the steel's hardness and strength. However, when the silicon content is too high, because silicon has a stronger affinity for oxygen than iron, it easily forms low-melting-point silicates during welding. This increases the fluidity of the slag and molten metal, causing spattering and affecting weld quality. Therefore, this invention sets the Si content range to 0.64%–0.98%.

[0018] Mn: 2.11%~2.64%

[0019] Mn is infinitely soluble in Fe and is a strong austenite stabilizer, playing a role in fixing austenite in steel and replacing some of the role of nickel. While increasing the strength of steel, Mn has a relatively small impact on plasticity and can lower the lower critical point of steel, increasing the undercooling during austenite cooling, thereby refining the microstructure and improving the mechanical properties of the steel plate. Furthermore, it is relatively inexpensive. However, excessively high Mn content increases the tendency for grain coarsening in steel; therefore, this invention sets the Mn content range to 2.11%–2.64%.

[0020] P: ≤0.015%, S: ≤0.01%

[0021] S and P are harmful elements in steel. To ensure the purity and toughness of steel, they must be strictly controlled. Therefore, this invention limits P to ≤ 0.015% and S to ≤ 0.010%.

[0022] Cr: 20.4%–22.8%

[0023] As a major alloying element in 300 series stainless steel, Cr increases the hardenability of the steel and has a secondary hardening effect, improving the hardness and wear resistance of carbon steel without making it brittle. Increasing the Cr content within a certain range gives the steel good high-temperature oxidation resistance and resistance to oxidative corrosion, while also increasing its hot strength. However, because it readily forms M23C6 carbides with C, it negatively impacts the intergranular corrosion resistance of the steel plate. Large amounts of Cr, when added in excess, generate large-sized carbides that reduce the low-temperature toughness of the steel plate. Therefore, this invention limits the Cr content to 20.4%–22.8%.

[0024] Ni: 5.2%–9.8%

[0025] Ni is an alloying element that strengthens the austenite region, refining ferrite and reinforcing pearlite. It also lowers the quenching temperature, increases the hardenability of the steel plate, and ensures a comprehensive improvement in the steel's strength, plasticity, and toughness, especially its low-temperature toughness. Furthermore, the addition of nickel not only improves the steel plate's acid resistance but also simultaneously enhances its alkali resistance and resistance to atmospheric and salt corrosion. However, considering overall cost, this invention sets the Ni content range to 5.2%–9.8%.

[0026] Mo: 0.12%–0.14%

[0027] Mo is a weak solid solution strengthening element. Its main role in steel is to increase the supercooling capacity of austenite, thereby refining the microstructure and having a positive impact on impact toughness and brittle transition temperature. Furthermore, the addition of molybdenum reduces the tendency of steel plates to pit corrosion caused by chloride ions, increasing the corrosion resistance of the steel plates. However, excessive Mo has an adverse effect on the weldability of the steel plates. Therefore, this invention sets the Mo content range to 0.12%–0.14%.

[0028] Ti: 0.014%~0.027%

[0029] Ti: Titanium has a strong affinity for nitrogen, oxygen, and carbon, and its affinity for sulfur is stronger than that for iron. It is an excellent deoxidizer and degassing agent, as well as an effective element for fixing nitrogen and carbon. Although titanium is a strong carbide-forming element, it does not combine with other elements to form complex compounds. Appropriate addition of Ti increases the Al and A3 temperatures, which helps form fine, dispersed titanium carbides in the steel plate and inhibits grain growth, improving plasticity and toughness. Because the affinity between titanium and carbon is much greater than that between chromium and carbon, Cr and Ti are added together to stainless steel to eliminate chromium depletion at grain boundaries, thereby eliminating or mitigating intergranular corrosion. In this invention, the Ti content is set in the range of 0.014% to 0.027%.

[0030] Cb: 0.0015%~0.0042%

[0031] Cb primarily functions in three ways: partly it dissolves into the solid solution, acting as a solid solution strengthening agent; partly it dissolves into austenite, significantly improving the hardenability of the steel; and when the addition amount is controlled within a certain range, Cb exists in the form of carbide and oxide particles, refining the internal grains of the steel plate and improving its strength, impact toughness, and lowering its brittle transition temperature without affecting its plasticity or toughness. Cb has a greater affinity for carbon than chromium (Cr), thus reducing Cr depletion at grain boundaries and positively impacting intergranular corrosion. However, considering cost and operability, the Cb content is controlled between 0.0015% and 0.0042%. Simultaneous addition of Ti and Cb to steel further refines the grains and mitigates the reduction in toughness caused by precipitation strengthening, achieving high strength while maintaining low-temperature toughness. To comprehensively improve the strength-toughness balance and resistance to intergranular corrosion, and to reduce costs, the Ti / Cb ratio is controlled within the range of 5 to 15.

[0032] Alt: 0.020%~0.045%

[0033] Alt is a commonly used deoxidizer in steel. Adding a small amount of aluminum can refine the grains and improve the strength and impact toughness of the steel. However, excessive amounts can affect the hot working properties, weldability, and machinability of the steel. This invention limits the Alt content to the range of 0.020% to 0.045%.

[0034] The second technical solution of the present invention is to provide a method for manufacturing 300 series stainless steel plates for hydrogen storage equipment, including smelting, slab continuous casting (forging), heating, rolling, hot straightening, and heat treatment.

[0035] A combination of solution treatment and homogenization heat treatment with two-stage controlled rolling (TMCP) is used to produce stainless steel plates for hydrogen storage with a thickness of 20–100 mm. The produced steel plates have a uniform microstructure, good strength and toughness, and excellent low-temperature and corrosion resistance.

[0036] 1. Smelting process:

[0037] Because the design composition contains high-melting-point elements such as Cr, steelmaking is carried out in an electric furnace, using high-quality scrap steel and low-P molten iron as raw materials. The molten iron content is controlled at 69-78% to ensure steel purity and reduce the difficulty of subsequent processes. During smelting, a mixture of O2, Ar, or N2 gas is blown in, and decarburization and chromium preservation are achieved by strictly controlling the oxygen-argon ratio parameter, maintaining an oxygen-argon ratio of 2.25-2.55 and a decarburization time of 15-25 minutes. To effectively reduce the content of harmful element P, oxygen blowing for dephosphorization is controlled at 10-15 minutes, reducing the phosphorus mass fraction in the molten steel to below 0.035%. Further deep desulfurization is carried out in an LF refining furnace, controlling the sulfur content below 0.002%. Degassing is completed in a VD furnace, with a net circulation time of 15-24 minutes and a pre-casting settling time of 6-11 minutes.

[0038] 2. Casting process:

[0039] After vacuum breaking, slab continuous casting is used for casting, with key control over the casting temperature. The tundish steel casting temperature is 1550–1562℃, and the superheat is set at 12–22℃. The billet pulling speed during casting is 1.2–1.8 m / min. Low-temperature casting is preferred to refine the original as-cast microstructure. To control center segregation and porosity of the continuously cast billet, electromagnetic stirring or a light reduction process is used, with the light reduction rate controlled at 5–7%. The billet is then stacked for slow cooling after being removed from the casting line, with a stacking and slow cooling time of 24–32 hours.

[0040] 3. Forging process:

[0041] For the production of finished steel plates with a thickness range of ≥60~100mm: hot forging is adopted, and the deformation amount of each forging pass is controlled to be 2.5-3.5% of the final steel billet thickness. During forging, the length direction-width direction-thickness direction are carried out in sequence. After completing the forging in one direction, the sample is rotated 90° and then the pressing deformation in the next direction is carried out. The deformation in the three directions is carried out in a total of 33 to 39 passes until the forging process is completed. The slab produced by hot forging has a uniform and dense internal structure and a good match between strength and toughness.

[0042] 4. Heating process:

[0043] The slab is sent to the heating furnace for heating using a two-stage heating process. The first stage controls the heating temperature range between 994 and 1048℃, while the second stage, the soaking zone, controls the temperature between 1241 and 1255℃. The total time the slab spends in the furnace is controlled between 2.2 and 3.4 hours. This two-stage heating method ensures complete phase transformation within the steel plate's internal structure, complete solid solution of alloying elements and large inclusions, and reduces internal stress. The first stage heating temperature is controlled within the range of 994–1048℃. In the second stage soaking zone, if the heating temperature is below 1241℃, large precipitates in the continuously cast slab cannot dissolve, resulting in incomplete austenitization and making it impossible to guarantee the final rolling temperature in the first stage. Conversely, if the heating temperature is above 1255℃, fine precipitates in the continuously cast slab are prone to re-dissolving, leading to excessive grain growth.

[0044] 5. Rolling process:

[0045] The rolling process employs a two-stage controlled rolling method using TMCP. The initial rolling temperature in the first stage is 1215–1230℃, and the final rolling temperature in the recrystallization zone is 1185–1220℃, fully refining the original austenite structure. Large deformation rapid rolling is used, with a rolling speed of 5.3–5.7 m / s and a reduction controlled at 9–11%. In the non-recrystallization zone, the final rolling temperature is 835–852℃, with a reduction controlled at 5–7%. Small deformation multi-pass rapid rolling is used, with a rolling speed of 5.0–5.2 m / s. At this stage, the austenite grains are further flattened and elongated, and the grains are further refined as the grain boundary area increases. Post-rolling, an ultra-rapid cooling process is employed, with the initial rapid cooling temperature controlled between 751–785℃ and the cooling rate controlled at 42–50℃ / s, followed by final cooling to room temperature, further improving the strength of the steel plate.

[0046] 6. Heat Treatment Process: Due to the addition of elements such as C, Si, Mn, P, S, Cr, Ni, Mo, Ti, and Cb to the steel, the steel plate obtains an austenitic structure with excellent strength and toughness after rolling. The online ultra-fast cooling control technology employed during the rolling stage further improves the strength of the steel plate. However, some grain sizes remain unevenly distributed, and there is concentration of structural and thermal stress, making it prone to delayed cracking during flame cutting. Therefore, timely heat treatment is necessary to homogenize the microstructure, soften the structure, and relieve stress. To further control the internal microstructure of the steel plate while ensuring high production efficiency, this invention employs solution treatment combined with homogenization heat treatment to ensure that the strength of the hydrogen storage steel plate is not compromised, while also giving the steel plate suitable plasticity and toughness, low-temperature performance, and good processing properties. Therefore, the first stage of heat treatment for steel involves a solution treatment temperature controlled at 1045–1066℃, a heating rate of 1.0–1.5 min / mm, and a net holding time of 0.8–1.6 min / mm. The second stage involves homogenization treatment, with the temperature controlled at 1186–1204℃, a heating rate of 1.0–1.3 min / mm, and a net holding time of 3.6–4.2 h. After removal from the furnace, the steel is air-cooled to room temperature. To reduce internal defects and control the flatness of the steel plate, the cooling rate is controlled at 16–22℃.

[0047] The beneficial effects of this invention are as follows:

[0048] (1) Based on the strengthening elements C, Si and Mn, by adding appropriate amounts of alloying elements Cr, Ni, Mo, Ti and Cb, while strictly controlling the content of harmful elements P and S, and combining with the optimization of production process, a uniformly distributed and refined austenitic structure is obtained with a grain size of 4 to 6. The fine and uniformly dispersed second phase carbide particles ensure the strong plasticity and low-temperature toughness of the steel plate, and at the same time have good resistance to intergranular corrosion.

[0049] (2) This invention provides high-performance stainless steel plates for hydrogen storage equipment with a thickness of (20-100) mm and excellent plate shape, obtained through a unique production process. Its mechanical properties are as follows: Room temperature: 0-25℃: 260MPa≤Rel≤350MPa, 540MPa≤Rm≤696MPa, A%≥40; -196℃: 360MPa≤Rel≤510MPa, 1050MPa≤Rm≤1120MPa, KV2≥150J.

[0050] (3) Intergranular corrosion test was conducted according to Method E in GB / T 4334-2008 "Corrosion of metals and alloys - Test method for intergranular corrosion of stainless steel", with sensitization process: 650℃×120min; pitting corrosion test was conducted according to Method A in GB / T 17897-2016 "Corrosion of metals and alloys - Test method for pitting corrosion of stainless steel with ferric chloride" (sensitization process: 650℃×120min). The results showed that the steel plate had excellent resistance to intergranular corrosion and pitting corrosion. Detailed Implementation

[0051] The present invention will be further illustrated below through examples.

[0052] According to the component ratio of the technical solution, the embodiments of the present invention carry out smelting, slab continuous casting, heating, rolling, hot straightening and heat treatment.

[0053] Forging process:

[0054] For finished steel plates with a thickness range of ≥60~100mm, hot forging is adopted, and the deformation amount of each forging pass is controlled to be 2.5-3.5% of the final steel billet thickness. During forging, the length direction-width direction-thickness direction are carried out in sequence. After completing the forging in one direction, the sample is rotated 90° and then the pressing deformation in the next direction is carried out. The deformation in the three directions is carried out in a total of 33 to 39 passes until the forging process is completed.

[0055] Heating process:

[0056] The slab is sent to the heating furnace for heating. A two-stage heating process is adopted. The first stage controls the heating temperature range of 994 to 1048℃, and the second stage controls the temperature of the soaking zone at 1241 to 1255℃. The total time of the slab in the furnace is controlled at 2.2 to 3.4 hours.

[0057] Rolling process:

[0058] The rolling process employs a two-stage controlled rolling method with TMCP. The final rolling temperature in the recrystallization zone is 1185–1220℃, using large deformation rapid rolling with a reduction controlled at 9–11%. The final rolling temperature in the non-recrystallization zone is 835–852℃, with a reduction controlled at 5–7%, using small deformation multi-pass rapid rolling. The rolling process is combined with ultra-rapid cooling, with the initial rapid cooling temperature controlled between 751–785℃ and the cooling rate controlled at 42–50℃ / s, followed by final cooling to room temperature.

[0059] Heat treatment process:

[0060] The heat treatment process employs a solution treatment followed by homogenization. In the first stage, the solution treatment temperature is controlled at 1045–1066℃, with a heating rate of 1.0–1.5 min / mm and a net holding time of 0.8–1.6 min / mm. In the second stage, the homogenization temperature is controlled at 1186–1204℃, with a heating rate of 1.0–1.3 min / mm and a net holding time of 3.6–4.2 h. After removal from the furnace, the furnace is air-cooled to room temperature, with the cooling rate controlled at 16–22℃.

[0061] Furthermore, during the smelting process, a mixture of O2, Ar, or N2 gas is blown in, controlling the oxygen-argon ratio at 2.25–2.55, the decarburization time at 15–25 min, the dephosphorization oxygen blowing time at 10–15 min, and the phosphorus mass fraction in the molten steel is controlled to be reduced to below 0.035%. Further, a deep desulfurization treatment is performed using an LF refining furnace, controlling the sulfur content to below 0.002%. Degassing is completed in a VD furnace, with a net circulation time of 15–24 min, and a pre-casting settling time of 6–11 min.

[0062] Furthermore, during the continuous casting process, the molten steel pouring temperature in the ladle is 1550–1562℃, the superheat is set to 12–22℃, and the billet pulling speed during pouring is 1.2–1.8 m / min; electromagnetic stirring or continuous casting billet light reduction process is adopted, wherein the light reduction rate is controlled at 5–7%, and the billet is stacked for slow cooling after leaving the line, with a stacking and slow cooling time of 24–32 hours.

[0063] Table 1 shows the chemical composition of the embodiments of the present invention, Table 2 shows the smelting and continuous casting process parameters of the steel in the embodiments, Table 3 shows the forging process parameters of the steel in the embodiments, Table 4 shows the rolling parameters of the steel in the embodiments, Table 5 shows the heat treatment parameters of the steel in the embodiments, Table 6 shows the final mechanical properties of the embodiments, and Table 7 shows the results of intergranular corrosion test and pitting test of the embodiments.

[0064] Table 1 Chemical composition (wt, %) of the examples

[0065]

[0066] Table 2 Smelting and Continuous Casting Process Parameters for Examples

[0067] Example 1 2 3 4 5 6 7 8 9 10 Iron content / % 70 73 75 72 74 71 69 73 69 71 Oxygen-argon ratio 2.34 2.28 2.29 2.42 2.38 2.52 2.50 2.41 2.35 2.51 Dephosphorization oxygen blowing time / min 11 12 13 10 13 11 10 14 11 15 Net cycle time / min 18 22 19 23 16 18 19 22 19 20 Sedation time / min 7 9 8 9 7 9 10 9 11 10 Casting temperature / ℃ 1556 1560 1558 1577 1561 1562 1552 1555 1554 1553 Superheat / °C 15 16 13 20 16 17 16 20 21 17 Casting speed (m / min) 1.3 1.6 1.7 1.4 1.8 1.6 1.2 1.4 1.3 1.5 Light compression rate / % 7 5 6 6 7 5 6 7 6 6 Stacking time / h 26 28 24 32 32 28 24 26 28 32

[0068] Table 3. Steel forging process parameters for the embodiments.

[0069] Example Thickness / mm Intermediate billet thickness / mm Deformation amount per pass / % 7 62 220 3.4 8 74 225 2.6 9 82 236 3.1 10 98 242 2.5

[0070] Table 4 Slab Heating Process Parameters

[0071] Example First stage heating temperature / ℃ Second-stage heat spreader temperature / ℃ Furnace time / h 1 998 1243 2.3 2 997 1250 2.2 3 1026 1248 2.4 4 1041 1249 2.3 5 1010 1253 2.6 6 1026 1251 2.7 7 1024 1249 2.9 8 1032 1254 3.1 9 1037 1252 2.9 10 1036 1251 3.3

[0072] Table 5 shows the steel rolling parameters for the examples.

[0073]

[0074] Table 6 Heat treatment process parameters for the steel in the examples

[0075]

[0076] Table 7 Final Mechanical Properties of Examples

[0077]

[0078] Table 8 Results of intergranular corrosion test in the examples

[0079]

[0080] As can be seen from the above, the 300 series stainless steel plate with excellent shape and thickness specifications for producing high-performance hydrogen storage equipment provided by this invention exhibits the following mechanical properties at room temperature: 5540MPa ≤ R. m ≤696MPa, 260MPa≤R el ≤380MPa, -196℃: 360MPa≤R m ≤510MPa, 1050MPa≤R el It has a strength of ≤1120 MPa and KV2≥150 J, exhibiting excellent resistance to intergranular corrosion and pitting corrosion.

[0081] To illustrate the present invention, the present invention has been appropriately and sufficiently described above through embodiments. The above embodiments are only for illustrating the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Any modifications, equivalent substitutions, improvements, etc., should be included within the protection scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A 300 series stainless steel plate for a hydrogen storage device, characterized in that, The steel plate, by weight percentage, comprises the following components: C: 0.02%–0.034%, Si: 0.64%–0.98%, Mn: 2.11%–2.64%, P: ≤0.015%, S: ≤0.01%, Cr: 20.4%–22.8%, Ni: 5.2%–9.8%, Mo: 0.12%–0.14%, Ti: 0.014%–0.027%, Nb: 0.0015%–0.0042%, Alt: 0.020%–0.045%, with the balance being Fe and unavoidable inclusions; the steel plate, under room temperature conditions, has a pressure of 260 MPa ≤ R. el ≤350MPa, 540MPa≤R m ≤696Mpa, A≥40%; under -196℃ condition: 360MPa≤R el ≤510MPa, 1050MPa≤R m ≤1120Mpa, KV2≥150J.

2. The 300 series stainless steel plate for hydrogen storage equipment according to claim 1, characterized in that, The Ti / Nb ratio is 5 to 15.

3. The 300 series stainless steel plate for hydrogen storage equipment according to claim 1, characterized in that, The microstructure of the steel plate is a refined austenitic structure with a grain size of 4 to 6.

4. The 300 series stainless steel plate for hydrogen storage equipment according to claim 1, characterized in that, The thickness of the steel plate is 20-100 mm.

5. A method for manufacturing a 300 series stainless steel plate for a hydrogen storage device according to any one of claims 1 to 4, comprising smelting, slab continuous casting, heating, rolling, hot straightening, and heat treatment, characterized in that, Forging process: For finished steel plates with a thickness range of 60-100mm, hot forging is used, and the deformation amount of each forging pass is controlled to be 2.5-3.5% of the final steel billet thickness. Forging is carried out in the order of length direction-width direction-thickness direction. After completing the forging in one direction, the sample is rotated 90° and then the pressing deformation in the next direction is carried out. The deformation in the three directions is carried out in a total of 33-39 passes until the forging process is completed. Heating process: The steel billet is sent to the heating furnace for heating. A two-stage heating process is adopted. The first stage controls the heating temperature range of 994 to 1048℃, and the second stage controls the temperature of the soaking zone at 1241 to 1255℃. The total time of the steel billet in the furnace is controlled at 2.2 to 3.4 hours. Rolling process: The rolling process employs a two-stage controlled rolling method using TMCP. The initial rolling temperature in the first stage is 1215–1230℃, and the final rolling temperature in the recrystallization zone is 1185–1220℃. Large deformation rapid rolling is used, with a rolling speed of 2.3–2.7 m / s and a reduction controlled at 9–11%. The final rolling temperature in the non-recrystallization zone is 835–852℃, with a reduction controlled at 5–7%. Small deformation multi-pass rapid rolling is used, with a rolling speed of 2.0–3.2 m / s. Post-rolling is combined with an ultra-rapid cooling process, with the initial rapid cooling temperature controlled between 751–785℃ and the cooling rate controlled at 42–50℃ / s, followed by final cooling to room temperature. Heat treatment process: The heat treatment process employs a solution treatment followed by homogenization. In the first stage, the solution treatment temperature is controlled at 1045–1066℃, with a heating rate of 1.0–1.5 min / mm and a net holding time of 0.8–1.6 min / mm. In the second stage, the homogenization temperature is controlled at 1186–1204℃, with a heating rate of 1.0–1.3 min / mm and a net holding time of 3.6–4.2 h. After removal from the furnace, the furnace is air-cooled to room temperature, with a cooling rate controlled at 16–22℃ / s.

6. The method for manufacturing a 300 series stainless steel plate for a hydrogen storage device according to claim 5, characterized in that, During the smelting process, a mixture of O2 and Ar2 gas is blown in, and the oxygen-argon ratio is controlled at 2.25-2.

55. The oxygen blowing time for dephosphorization is controlled at 10-15 minutes. Further desulfurization is carried out in an LF refining furnace. Degassing is completed in a VD furnace with a net circulation time of 15-24 minutes and a settling time of 6-11 minutes before casting.

7. The method for manufacturing a 300 series stainless steel plate for a hydrogen storage device according to claim 5, characterized in that, During the continuous casting process, the molten steel pouring temperature in the ladle is 1550–1562℃, the superheat is set to 12–22℃, and the billet pulling speed during pouring is 1.2–1.8 m / min. Electromagnetic stirring or continuous casting billet light reduction process is adopted, wherein the light reduction rate is controlled at 5–7%, and the billet is put into a stack for slow cooling after leaving the line, with a stacking and slow cooling time of 24–32 hours.

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