Steel plate for hydrogen storage pressure vessel and preparation method thereof

Abstract

The invention relates to a steel plate for a hydrogen storage pressure vessel and a preparation method of the steel plate, belongs to the field of manufacturing of steel for pressure vessels, and solves the problems of deteriorated surface toughness and higher hydrogen embrittlement sensitivity of a thick plate in the prior art. The steel plate for the hydrogen storage pressure vessel is prepared from the following components in percentage by mass: 0.1 to 0.15 percent of C, 0.2 to 0.29 percent of Si, 1.0 to 1.5 percent of Mn, 0.4 to 0.5 percent of Cr, 1.3 to 1.4 percent of Ni, 0.3 to 0.55 percent of Mo, 0.02 to 0.05 percent of V, 0.01 to 0.02 percent of Ti, 0.008 to 0.009 percent of Nb, 0.02 to 0.06 percent of Cu, 0.02 to 0.03 percent of Al and the balance of Fe and inevitable impurities. The prepared steel plate for the hydrogen storage pressure vessel has high strength and high toughness.

Description

Technical Field

[0001] This invention relates to the field of steel for containers, and more particularly to a steel plate for hydrogen storage pressure vessels and its preparation method. Background Technology

[0002] With the continued exploitation of traditional energy sources, numerous environmental problems have gradually emerged; at the same time, the scarcity of irreversible resources has led technicians to turn their attention to various new clean energy sources. Hydrogen energy systems, due to their high calorific value (142 MJ / kg) and lack of pollution, are gradually becoming a promising new energy source.

[0003] High-pressure hydrogen storage pressure vessel steel is expected to be used in industrial facilities such as large high-pressure hydrogen storage tanks, high-pressure hydrogen transport vehicles, and pipelines, providing a highly reliable and independent development guarantee for the large-scale hydrogen energy industry. Compared to traditional spherical tank steel, 800MPa-grade ultra-high strength and toughness hydrogen storage steel can reduce wall thickness, significantly saving costs and energy consumption; however, under high-pressure hydrogen environments, the material may suffer from hydrogen embrittlement failure, therefore requiring the material to maintain sufficient toughness under high pressure.

[0004] Existing steel plates for hydrogen storage pressure vessels have drawbacks such as a narrow range of thickness specifications, poor surface quality, low impact toughness, and a tendency for toughness deterioration to occur on the surface, core, and 1 / 4 of the vessel. These shortcomings make them unsuitable for the current requirements of large, high-parameter hydrogen-resistant pressure vessels.

[0005] Therefore, it is of great significance to develop a steel plate for hydrogen storage pressure vessels that combines high strength, high and low temperature toughness, and low hydrogen embrittlement sensitivity, as well as its preparation method. Summary of the Invention

[0006] Based on the above analysis, the embodiments of the present invention aim to provide a steel plate for hydrogen storage pressure vessels and a method for preparing the same, to solve one of the following problems of existing steel plates for hydrogen storage pressure vessels: 1. The thickness specification range of existing steel plates for hydrogen storage pressure vessels is narrow; 2. The strength and toughness of existing steel plates for hydrogen storage pressure vessels are not matched at different locations; 3. The surface low-temperature impact toughness of existing steel plates for hydrogen storage pressure vessels is poor; 4. Existing steel plates for hydrogen storage pressure vessels have high hydrogen embrittlement sensitivity.

[0007] The objective of this invention is mainly achieved through the following technical solutions:

[0008] This invention provides a steel plate for a hydrogen storage pressure vessel. The composition of the steel plate, by mass percentage, is as follows: C 0.1-0.15%, Si 0.2-0.29%, Mn 1.0-1.5%, Cr 0.4-0.5%, Ni 1.3-1.4%, Mo 0.3-0.55%, V 0.02-0.05%, Ti 0.01-0.02%, Nb 0.008-0.009%, Cu 0.02-0.06%, Al 0.02-0.03%, with the balance being Fe and unavoidable impurities.

[0009] Furthermore, the sum of the C content and Mn content satisfies the following condition: the C+Mn content is 1.1% to 1.6%;

[0010] The sum of the Cr, Mo, and Al contents satisfies the following condition: the Cr + Mo + Al content is 0.75% to 1.0%.

[0011] The sum of the Ti and V contents satisfies the condition that the Ti+V content is 0.04% to 0.07%.

[0012] Furthermore, the microstructure of the steel plate used in the hydrogen storage pressure vessel is tempered sorbite + cementite + nanoscale carbide precipitates, wherein the cementite has a size of 5.2 × 10⁻⁶. -2 ~5.6×10 -2 μm, nanoscale carbide precipitates with a size <5nm.

[0013] This invention also provides a method for preparing steel plates for hydrogen storage pressure vessels, which uses the composition design of the above-mentioned nickel-based wrought superalloy and includes the following steps:

[0014] S1: Continuously cast billets are obtained by smelting in a converter or electric furnace and then continuously casting.

[0015] S2: After homogenization treatment of the continuously cast billet, it is hot rolled, and after rolling, it is laminar cooled to obtain a hot-rolled plate.

[0016] S3: Hot-rolled plates are subjected to cyclic quenching and high-temperature tempering to obtain steel plates for hydrogen storage pressure vessels.

[0017] 5. The preparation method according to claim 4, wherein in step S2, the homogenization treatment temperature is 1150-1250℃ and the homogenization treatment time is 1.5-2h.

[0018] Furthermore, in step S2, the hot rolling process involves 12 to 16 rolling passes, with a reduction of 20 to 30% per pass, an initial rolling temperature of 910 to 950°C, and a final rolling temperature of 800 to 860°C.

[0019] Furthermore, in step S2, the cooling water volume for laminar flow cooling is 0.9-1.3 × 10⁻⁶. 4 m 3 / h, cooling water pressure is 1-1.4Kpa.

[0020] Furthermore, in step S3, the number of cyclic quenchings is ≥2, wherein the austenitizing temperature of the first quenching is 860~920℃, and after the first quenching, a water cooling step is also included, with an average cooling rate of 20~50℃ / s and a final cooling temperature ≤100℃.

[0021] The austenitizing temperature for secondary quenching and subsequent multiple quenching is 880~920℃. After quenching, circulating water cooling is used, with a final cooling temperature ≤100℃ and an average cooling rate ≥20℃ / s.

[0022] Furthermore, in step S3, the heating rate of the cyclic quenching is 20-100℃ / min, and the holding time t and the steel plate thickness d satisfy: t = (0.1-2 min / mm)d, where d is in mm and t is in min.

[0023] Furthermore, in step S3, the tempering temperature is 600-700℃, and the holding time t and the steel plate thickness d satisfy: t = (0.4-1.4 min / mm)d; the unit of d is mm, and the unit of t is min.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] 1. This invention ensures the strength and toughness of the matrix by precisely controlling elements such as C, Mn, and Ni. At the same time, it uses the combination of Cr and Mo to improve hardenability and resistance to hydrogen embrittlement, and uses microalloying elements such as Ti and V to achieve fine grain strengthening and precipitation strengthening. Through the synergistic effect of each element, the prepared steel plate for hydrogen storage pressure vessels has both high strength and good low-temperature toughness and resistance to hydrogen embrittlement.

[0026] 2. In the preparation process of the steel plate for hydrogen storage pressure vessel of the present invention, the austenitizing temperature and time are precisely controlled to ensure a small original austenite grain size. Combined with the cyclic quenching process, the strength and toughness of the steel plate for hydrogen storage pressure vessel are well matched at each position, ensuring that it has high strength while also having high low-temperature toughness.

[0027] 3. The steel plate for hydrogen storage pressure vessels of the present invention overcomes the deterioration of surface toughness caused by traditional quenching and tempering treatment, and obtains tempered sorbite + cementite + nanoscale carbide precipitates. Among them, tempered sorbite, as the matrix structure of the steel plate for hydrogen storage pressure vessels, ensures that the steel plate has a good balance of strength and toughness.

[0028] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1 This is a microstructure diagram of the steel plate for the hydrogen storage pressure vessel of Embodiment 1 of the present invention after heat treatment;

[0031] Figure 2 This is a microstructure diagram of the steel plate for the hydrogen storage pressure vessel of Embodiment 2 of the present invention after heat treatment;

[0032] Figure 3 This is a microstructure diagram of the steel plate used for the hydrogen storage pressure vessel in Comparative Example 1 of the present invention after heat treatment. Detailed Implementation

[0033] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0034] This invention provides a steel plate for a hydrogen storage pressure vessel. The composition of the steel plate, by mass percentage, is as follows: C 0.1-0.15%, Si 0.2-0.29%, Mn 1.0-1.5%, Cr 0.4-0.5%, Ni 1.3-1.4%, Mo 0.3-0.55%, V 0.02-0.05%, Ti 0.01-0.02%, Nb 0.008-0.009%, Cu 0.02-0.06%, Al 0.02-0.03%, with the balance being Fe and unavoidable impurities.

[0035] Preferably, the C+Mn content in the steel plate for the hydrogen storage pressure vessel is 1.1% to 1.6%.

[0036] Preferably, the Cr+Mo+Al content in the steel plate for the hydrogen storage pressure vessel is 0.75% to 1.0%.

[0037] Preferably, the Ti+V content in the steel plate for the hydrogen storage pressure vessel is 0.04% to 0.07%.

[0038] The following details the role and dosage selection of the components in the steel plate for hydrogen storage pressure vessels and its preparation method described in this invention:

[0039] C: Carbon is a key factor determining the weldability of steel. As the carbon content increases, the weldability of steel decreases significantly. Carbon can effectively improve the hardenability of thick steel plates, ensure a more uniform distribution of cross-sectional properties, and enhance the material's ability to resist hardness reduction during tempering. When the carbon content is below 0.25%, the steel usually exhibits good plasticity and toughness, but its strength and hardness are relatively low, thus possessing good rolling and welding properties. Taking all factors into consideration, the C content in this invention ranges from 0.1% to 0.15%.

[0040] Si: As a deoxidizer, Si has a strong affinity for oxygen. After being added, it can quickly react with oxygen to generate silicon dioxide (SiO2) and float to the slag, thereby effectively reducing the oxygen content in the steel and improving the purity of the molten steel. Si can form a substitution solid solution with ferrite, which can significantly improve the strength and hardness of the steel. However, too much Si usually deteriorates the toughness of the steel and cannot meet the requirements of low temperature and high toughness for steel plates used in hydrogen storage pressure vessels. The Si content in this invention ranges from 0.2% to 0.29%.

[0041] Mn: Mn can improve the toughness of steel, especially its low-temperature toughness; at the same time, Mn is a strong austenite forming element, which is beneficial to increasing the hardenability of the material and is a significant strengthening element. The C+Mn content needs to be maintained between 1.1% and 1.6%; in this invention, the Mn content is controlled to be between 1.0% and 1.5%.

[0042] Cr: Cr is a strong carbide-forming element. After dissolving into austenite, it can significantly improve the stability of supercooled austenite. When the total content of Cr, Mo, and Al in steel is controlled above 0.75%, they can synergistically improve the hardenability and corrosion resistance of the steel. In addition, this synergistic effect of elements can also effectively enhance the oxidation resistance of steel under high-temperature environments. In this invention, the Cr content is controlled at 0.4% to 0.5%.

[0043] Ni: The most significant role of Ni in steel is its ability to effectively improve the toughness of steel, especially its low-temperature toughness; at the same time, Ni is one of the strongest austenite-forming elements, which can expand the γ phase region; even at low temperatures, Ni can help stabilize the phase structure with good toughness; therefore, the Ni content in this invention is controlled at 1.3 to 1.4%.

[0044] Mo: Mo can effectively improve the strength and toughness of steel, ensuring that the steel has good comprehensive mechanical properties; at the same time, it can significantly improve the steel's resistance to hydrogen embrittlement and hydrogen-induced cracking, reduce the sensitive sites of hydrogen traps, and form stable carbides. In this invention, the Mo content is 0.3-0.55%.

[0045] Ti and V: Since both Ti and V are strong carbide-forming elements, they can precipitate nanoscale (Ti,V)C during tempering, which produces precipitation strengthening effect by forming carbides, effectively improving the strength of steel. In addition, undissolved carbides pin the austenite grain boundaries during heating, preventing grain coarsening at high temperatures and inhibiting austenite grain growth. In this invention, the Ti content is controlled at 0.01-0.02%, the V content at 0.02-0.05%, and the Ti+V content is kept between 0.04% and 0.07%.

[0046] Nitrogen (Nb): Nitrogen primarily enhances the overall properties of steel, including strength, toughness, and weldability, through the formation of carbonitrides. This enhancement can be summarized as grain refinement and precipitation strengthening. In this invention, the Nb content is controlled between 0.008% and 0.009%.

[0047] Cu: After solution treatment, supersaturated copper precipitates out as a very fine copper-rich phase, effectively hindering dislocation movement, thereby improving strength and hardness, and producing precipitation strengthening. In this invention, the Cu content is controlled at 0.02-0.06%.

[0048] Al: Aluminum acts as a deoxidizer in steel, purifying the molten steel during smelting and improving its purity; it also refines the grains and improves the toughness of the steel. However, excessive Al will reduce the weldability of the steel. In this invention, the Al content is controlled at 0.02-0.03%.

[0049] Preferably, the present invention provides a steel plate for a hydrogen storage pressure vessel, wherein the composition of the steel plate for the hydrogen storage pressure vessel, by mass percentage, is: C 0.11-0.14%, Si 0.22-0.26%, Mn 1.0-1.28%, Cr 0.43-0.48%, Ni 1.32-1.34%, Mo 0.48-0.5%, V 0.037-0.038%, Ti 0.013-0.015%, Nb 0.008-0.0088%, Cu 0.038-0.04%, Al 0.02-0.03%, with the balance being Fe and unavoidable impurities.

[0050] Preferably, the C+Mn content in the steel plate for the hydrogen storage pressure vessel is 1.11% to 1.42%.

[0051] Preferably, the Cr+Mo+Al content in the steel plate for the hydrogen storage pressure vessel is 0.95% to 0.99%.

[0052] Preferably, the Ti+V content in the steel plate for the hydrogen storage pressure vessel is 0.051% to 0.053%.

[0053] The present invention also provides a method for preparing the steel plate for the above-mentioned hydrogen storage pressure vessel, comprising the following steps:

[0054] S1: Continuously cast billets are obtained by smelting in a converter or electric furnace and then continuously casting.

[0055] S2: After homogenization treatment of the continuously cast billet, it is hot rolled, and after rolling, it is laminar cooled to obtain a hot-rolled plate.

[0056] S3: Hot-rolled plates are subjected to cyclic quenching and high-temperature tempering to obtain steel plates for hydrogen storage pressure vessels.

[0057] Specifically, in step S1, a converter or electric furnace is used for smelting, and a continuously cast billet is obtained through continuous casting.

[0058] Specifically, step S2 aims to improve the overall mechanical properties of the steel plate by controlling the rolling and cooling processes to obtain a bainite-dominant microstructure and refine the original austenite grains. The specific operation is as follows: First, the continuously cast billet is homogenized at 1150–1250℃ for 1.5–2 hours to ensure sufficient dissolution and homogenization of alloying elements. Then, hot rolling is performed. Since excessive reduction per pass can cause edge and center waviness defects and exacerbate roll wear, while insufficient reduction leads to inadequate deformation and insufficient grain refinement, potentially even causing abnormal grain growth, the reduction per pass must be controlled at 20–30%, with a total of 12–16 rolling passes to ensure sufficient deformation penetration and a uniformly refined microstructure. The initial hot rolling temperature is controlled at 910–950℃ to precisely control the finished product dimensions and shape and obtain excellent surface quality. The final rolling temperature is controlled at 800–860℃.

[0059] The process parameters of laminar flow cooling directly affect the microstructure and properties of steel plates. The cooling water volume used for hot-rolled plates is 0.9–1.3 × 10⁻⁶. 4 m 3 Sufficient cooling water is crucial for maintaining the steel's microstructure and shape quality. The water pressure is generally maintained at 1 to 1.4 kPa, which can effectively break through the vapor film formed on the surface of the hot-rolled plate at high temperatures and improve cooling efficiency.

[0060] Specifically, in step S3, the hot-rolled plate undergoes cyclic quenching followed by high-temperature tempering. The cyclic quenching involves two or more quenching processes. The austenitizing temperature of the first quench is 860–920℃. After the first quench, a water cooling step is performed with an average cooling rate of 20–50℃ / s and a final cooling temperature ≤100℃. During the first quenching process, uniform austenite grains are obtained during heating and holding. The resulting microstructure is uniform and fine martensite, while retaining a small amount of ferrite and retained austenite.

[0061] The austenitizing temperature for the second quenching and subsequent multiple quenchings is 880–920℃; after quenching, circulating water cooling is used, with a final cooling temperature ≤100℃ and an average cooling rate ≥20℃ / s. The second quenching and subsequent multiple quenchings austenitize the martensite lath grain boundaries of the previous quenching, resulting in more uniform and finer austenite grains.

[0062] It should be noted that the heating rate for each quenching is 20-100℃ / min, and the holding time t and the steel plate thickness d are related as follows: t = (0.1-2 min / mm)d, where d is in mm and t is in min.

[0063] The tempering temperature in the tempering heat treatment step is 600-700℃; within this temperature range, a uniform tempered sorbite structure is obtained; the heating rate is 20-50℃ / min, and the holding time t is related to the steel plate thickness d as follows: t = (0.4-1.4min / mm)d; where d is in mm and t is in min. After holding, the plate is air-cooled to room temperature; a tempered sorbite + cementite + nanoscale precipitates are obtained, ensuring that the prepared steel plate has both high toughness and excellent strength.

[0064] This invention ensures that the steel plate has a good range of thickness specifications and comprehensive mechanical properties by reasonably controlling the mass percentage of alloying elements and the cyclic quenching process.

[0065] This invention achieves comprehensive performance in steel plates that meet the requirements of large-scale high-pressure hydrogen storage containers by precisely controlling the mass percentage and synergistic ratio of alloying elements. By controlling the C content to 0.10%–0.15% and combining it with Mn, the total C+Mn content is maintained at 1.1%–1.6%. This ensures basic strength through solid solution strengthening while also providing excellent weldability and toughness. Furthermore, the Cr+Mo+Al content is controlled at 0.75%–1.0%. The synergistic effect of Cr and Mo significantly improves hardenability to ensure uniform cross-sectional properties, while Mo's crucial role imparts excellent resistance to hydrogen embrittlement. Further, the strong carbide-forming elements Ti and V are controlled, with the total Ti+V content between 0.04% and 0.07%. The precipitated nanoscale (Ti,V)C particles pin grain boundaries and refine the original austenite grains during heat treatment, and produce significant precipitation strengthening during tempering, thereby effectively improving strength while refining the grain size. Furthermore, the addition of 1.3%–1.4% Ni directly contributes to stabilizing the austenitic structure, significantly improving the low-temperature toughness of the steel plate. Ultimately, through the specific composition range and synergistic ratio mentioned above, the various elements collectively achieve an optimal combination of high strength, high and low temperature toughness, and low hydrogen embrittlement sensitivity in the steel plate.

[0066] In the cyclic quenching process of this invention, the martensite structure formed in the first quenching will transform back into new austenite during the second quenching. The original martensite lath interfaces will become new nucleation sites, thereby increasing the nucleation rate and refining the grain size, resulting in a finer lath martensite structure after the second quenching. Similarly, during subsequent quenching, the martensite structure formed in the previous quenching will transform back into new austenite, and the original martensite lath interfaces will become new nucleation sites, thereby increasing the nucleation rate and refining the grain size, resulting in a finer lath martensite structure after subsequent quenching. During high-temperature tempering, the martensite laths decompose, the residual austenite and carbides transform, and the fine-grained cementite rapidly aggregates and coarsens; the tempered sorbite structure obtained by high-temperature tempering has a good strength-toughness balance. After cyclic quenching and high-temperature tempering, the microstructure consists of tempered sorbite + cementite + nano-sized carbide precipitates, with the cementite having a size of 5.2 × 10⁻⁶. ～2 ~5.6×10 ～2 The carbide precipitates are <5nm in size, and the grain size is refined, with an effective grain size ≤8μm, thus achieving high strength. At the same time, the refinement of the original austenite grains effectively reduces lath and block boundaries, increases the length of large-angle grain boundaries, effectively suppresses stress concentration and crack propagation, increases crack inflection paths, and improves low-temperature toughness.

[0067] The steel plate for hydrogen storage pressure vessels prepared in this embodiment has a yield strength ≥840MPa (e.g., 846~880MPa), tensile strength ≥880MPa (e.g., 882~950.5MPa), surface impact energy at ~40℃ ≥180J (e.g., 188~197J), reduction of area loss ≤29% (e.g., 26.3~28.4%) under 10MPa hydrogen environment, and fracture toughness ≥100MPa·m under 10MPa hydrogen environment. 1 / 2 (e.g., 105–122 MPa·m) 1 / 2 ).

[0068] Example 1

[0069] This embodiment provides a steel plate for a hydrogen storage pressure vessel. The composition of the steel plate for the hydrogen storage pressure vessel, by mass percentage, is: C 0.11%, Si 0.22%, Mn 1.0%, Cr 0.43%, Ni 1.32%, Mo 0.49%, V 0.037%, Ti 0.014%, Nb 0.0081%, Cu 0.04%, Al 0.03%, with the balance being Fe and unavoidable impurities.

[0070] The C+Mn content is 1.11%, the Cr+Mo+Al content is 0.95%, and the Ti+V content is 0.051%.

[0071] Prepared by the following steps:

[0072] S1: Continuously cast billets are obtained by smelting in a converter or electric furnace and then continuously casting.

[0073] S2: After homogenization treatment of the continuously cast billet, it is hot rolled, and after rolling, it is laminar cooled to obtain a hot-rolled plate.

[0074] First, the continuously cast billet is homogenized and held at 1200℃ for 1.8 hours, followed by 14 passes of hot rolling, with a reduction of about 20% per pass. The initial rolling temperature is 920℃ and the final rolling temperature is 830℃.

[0075] The cooling water volume for laminar flow cooling is approximately 1.1 × 10⁻⁶. 4 m 3 / h, water pressure is 1.2KPa;

[0076] The thickness of the hot-rolled plate is 90mm;

[0077] S3: The hot-rolled plate is subjected to two cycles of quenching and high-temperature tempering to obtain steel plate for hydrogen storage pressure vessels.

[0078] The austenitizing temperature of the first quenching is 910℃. After the first quenching, a water cooling step is also included, with an average cooling rate of 20℃ / s and a final cooling temperature of 25℃.

[0079] The austenitizing temperature of the second quenching is 910℃; after quenching, circulating water cooling is used, with a final cooling temperature of 25℃ and an average cooling rate of 20℃ / s.

[0080] The quenching heating rate is 50℃ / min each time, and the holding time is t=(0.1~2min / mm)d=0.44×90mm≈40min, where d is in mm and t is in min;

[0081] The tempering temperature is 650℃, the heating rate is 20℃ / min, and the holding time t and the steel plate thickness d are related as follows: t=(0.4~1.4min / mm)d=1.3×90=117min; the unit of d is mm, and the unit of t is min.

[0082] Example 2

[0083] This embodiment provides a steel plate for a hydrogen storage pressure vessel. The composition of the steel plate for the hydrogen storage pressure vessel, by mass percentage, is: C 0.12%, Si 0.23%, Mn 1.01%, Cr 0.43%, Ni 1.34%, Mo 0.5%, V 0.038%, Ti 0.015%, Nb 0.008%, Cu 0.04%, Al 0.03%, with the balance being Fe and unavoidable impurities.

[0084] The C+Mn content is 1.13%, the Cr+Mo+Al content is 0.96%, and the Ti+V content is 0.053%.

[0085] The preparation method is similar to that in Example 1, except that:

[0086] In step S3, the cyclic quenching is performed 3 times, and the process parameters are the same as those in Example 1.

[0087] Example 3

[0088] This embodiment provides a steel plate for a hydrogen storage pressure vessel. The composition of the steel plate for the hydrogen storage pressure vessel, by mass percentage, is: C 0.14%, Si 0.26%, Mn 1.28%, Cr 0.48%, Ni 1.34%, Mo 0.48%, V 0.038%, Ti 0.013%, Nb 0.0088%, Cu 0.038%, Al 0.03%, with the balance being Fe and unavoidable impurities.

[0089] The C+Mn content is 1.42%, the Cr+Mo+Al content is 0.99%, and the Ti+V content is 0.051%.

[0090] The preparation method and process parameters are the same as in Example 1.

[0091] Example 4

[0092] This embodiment provides a steel plate for a hydrogen storage pressure vessel, the composition of which is the same as that in Embodiment 1.

[0093] The preparation method is similar to that in Example 1, except that:

[0094] In step S2, the continuously cast billet is heated at 1250℃ for 1.5 hours, and then hot rolled in 12 passes, with a reduction of about 30% per pass. The initial rolling temperature is 940℃ and the final rolling temperature is 850℃.

[0095] In step S3, two cycles of quenching are performed. The austenitizing temperature of the first quenching is 920℃. After the first quenching, a water cooling step is also included. The average cooling rate is 25℃ / s, and the final cooling temperature is 30℃.

[0096] The austenitizing temperature of the secondary quenching is 920℃; after quenching, circulating water cooling is used, with a final cooling temperature of 30℃ and an average cooling rate of 25℃ / s.

[0097] Comparative Example 1

[0098] This comparative example provides a steel plate for a hydrogen storage pressure vessel, the composition of which is the same as that of Example 1.

[0099] The preparation method is similar to that in Example 1, except that:

[0100] In this comparative example, the hot-rolled plate was subjected to only one quenching at 910℃ and then a high-temperature tempering treatment at 650℃ to obtain a steel plate for hydrogen storage pressure vessels.

[0101] Comparative Example 2

[0102] This comparative example provides a steel plate for a hydrogen storage pressure vessel, with a composition different from Example 1. The difference lies in that the C+Mn content is 1.74%, of which the C content is 0.14% and the Mn content is 1.6%, while the contents of the remaining elements are the same as in Example 1. The Mn content and C+Mn content do not meet the requirements of this invention.

[0103] The preparation method and parameters are the same as in Example 1.

[0104] Comparative Example 3

[0105] This comparative example provides a steel plate for a hydrogen storage pressure vessel, which has similar composition and preparation method to Example 1, except that:

[0106] The chemical composition of this comparative example differs from that of Example 1. The Cr+Mo+Al content is 0.64%, of which the Cr content is 0.38%, the Mo content is 0.25%, and the Al content is 0.01%. The content of the remaining elements is the same as that of Example 1.

[0107] The difference between the preparation method of this comparative example and that of Example 1 is that...

[0108] In this comparative example, the hot-rolled plate was subjected to two quenching treatments at 910℃ followed by high-temperature tempering at 650℃. The quenching holding time was t=(0.1~2min / mm)d=1.1×90=99min, resulting in a steel plate for hydrogen storage pressure vessels.

[0109] Comparative Example 4

[0110] This comparative example provides a steel plate for a hydrogen storage pressure vessel, with the same composition as Example 1. The preparation method is similar to Example 1, except that:

[0111] In step S2, the laminar cooling water flow rate is 0.6 × 10⁻⁶. 4 m 3 / h;

[0112] In step S3, the cooling rate after the first quenching and the second quenching is 15℃ / s.

[0113] The chemical composition of the steels in the examples and comparative examples is shown in Table 1, the preparation process parameters are shown in Table 2, and the properties are shown in Table 3.

[0114] Table 1. Chemical composition of the examples and comparative examples, wt%.

[0115]

[0116]

[0117] Table 2 Preparation process parameters

[0118]

[0119] Table 3. Properties of the steels in the examples and comparative examples.

[0120]

[0121] Table 4. Microstructure of the steels in the examples and comparative examples.

[0122]

[0123] The steel plate compositions, preparation methods, and parameters of Examples 1-4 all meet the requirements of this invention. The prepared steel plates for hydrogen storage pressure vessels achieve a good strength-toughness balance and ensure good resistance to hydrogen embrittlement, while effectively overcoming the deterioration of surface toughness of the experimental steel plates. Comparative Example 1, although having the same composition as Example 1 and meeting the requirements of this invention, only underwent one quenching process. The strength, surface impact energy at -40°C, and fracture toughness under 10MPa hydrogen conditions of the prepared steel plate for hydrogen storage pressure vessels are significantly lower than those of Example 1, and the reduction of area loss rate under 10MPa hydrogen conditions is increased. Comparative Example 2, although prepared using the same method as Example 1 and meeting the requirements of this invention, does not meet the requirements of this invention in terms of Mn and C+Mn content. Although its strength is somewhat enhanced compared to Example 1, its surface impact energy at -40°C and fracture toughness under 10MPa hydrogen conditions are both lower, failing to simultaneously possess high strength and high toughness, resulting in a poor strength-toughness balance. Although the preparation method and parameters of Comparative Example 3 meet the requirements of this invention, the content of Cr, Mo, and Al in its steel plate composition does not meet the requirements of this invention, resulting in poor strength and toughness. Although the composition of Comparative Example 4 is the same as that of Example 1, the amount of laminar cooling water during its preparation process is less, and the cooling rate after the first and second quenching is lower, leading to coarsening of its microstructure. Ultimately, its toughness (impact energy at ~40℃) and resistance to hydrogen embrittlement (reduction of area loss rate, fracture toughness) are significantly lower than those of Example 1.

[0124] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A steel plate for a hydrogen storage pressure vessel, characterized in that, The composition of the steel plate used for the hydrogen storage pressure vessel, by mass percentage, is as follows: C 0.1-0.15%, Si 0.2-0.29%, Mn 1.0-1.5%, Cr 0.4-0.5%, Ni 1.3-1.4%, Mo 0.3-0.55%, V 0.02-0.05%, Ti 0.01-0.02%, Nb 0.008-0.009%, Cu 0.02-0.06%, Al 0.02-0.03%, with the balance being Fe and unavoidable impurities.

2. The steel plate for a hydrogen storage pressure vessel according to claim 1, characterized in that, The sum of the C content and Mn content satisfies the following condition: the C+Mn content is 1.1% to 1.6%; The sum of the Cr, Mo, and Al contents satisfies the following condition: the Cr + Mo + Al content is 0.75% to 1.0%. The sum of the Ti and V contents satisfies the condition that the Ti+V content is 0.04% to 0.07%.

3. The steel plate for a hydrogen storage pressure vessel according to claim 1, characterized in that, The microstructure of the steel plate used in the hydrogen storage pressure vessel consists of tempered sorbite + cementite + nanoscale carbide precipitates, wherein the cementite has a size of 5.2 × 10⁻⁶. -2 ~5.6×10 -2 μm, nanoscale carbide precipitates with a size <5nm.

4. A method for preparing a steel plate for a hydrogen storage pressure vessel, comprising the composition design of the nickel-based wrought superalloy as described in claim 1 or 2, characterized in that, Includes the following steps: S1: Continuously cast billets are obtained by smelting in a converter or electric furnace and then continuously casting. S2: After homogenization treatment of the continuously cast billet, it is hot rolled, and after rolling, it is laminar cooled to obtain a hot-rolled plate. S3: Hot-rolled plates are subjected to cyclic quenching and high-temperature tempering to obtain steel plates for hydrogen storage pressure vessels.

5. The preparation method according to claim 4, characterized in that, In step S2, the homogenization temperature is 1150-1250℃ and the homogenization time is 1.5-2h.

6. The preparation method according to claim 5, characterized in that, In step S2, the hot rolling process involves 12 to 16 rolling passes, with a reduction of 20 to 30% per pass, an initial rolling temperature of 910 to 950°C, and a final rolling temperature of 800 to 860°C.

7. The preparation method according to claim 6, characterized in that, In step S2, the cooling water volume for laminar flow cooling is 0.9-1.3 × 10⁻⁶. 4 m 3 / h, cooling water pressure is 1-1.4Kpa.

8. The preparation method according to claim 7, characterized in that, In step S3, the number of cyclic quenching is ≥2, wherein the austenitizing temperature of the first quenching is 860~920℃, and after the first quenching, a water cooling step is also included, with an average cooling rate of 20~50℃ / s and a final cooling temperature ≤100℃. The austenitizing temperature for secondary quenching and subsequent multiple quenching is 880~920℃. After quenching, circulating water cooling is used, with a final cooling temperature ≤100℃ and an average cooling rate ≥20℃ / s.

9. The preparation method according to claim 8, characterized in that, In step S3, the heating rate of the cyclic quenching is 20-100℃ / min, and the holding time t and the steel plate thickness d satisfy: t = (0.1-2 min / mm)d, where d is in mm and t is in min.

10. The preparation method according to claim 9, characterized in that, In step S3, the tempering temperature is 600-700℃, and the holding time t and the steel plate thickness d satisfy: t = (0.4-1.4 min / mm)d; the unit of d is mm, and the unit of t is min.

Images