High-strength austenitic stainless steel for cryogenic high-pressure hydrogen storage container lining and preparation method of high-strength austenitic stainless steel

Abstract

According to the high-strength austenitic stainless steel for the cryogenic high-pressure hydrogen storage container lining and the preparation method of the high-strength austenitic stainless steel, tempered martensite is formed in a uniform equiaxed austenite structure, and martensite phase transformation is induced in austenite under the ultralow temperature condition; a part of martensite structure is obtained in an austenite matrix, and then nano precipitated phases which are uniformly distributed are formed in the austenite structure through medium and low temperature tempering heat preservation and heating and cooling processes, so that the austenitic stainless steel with high strength and internal hydrogen embrittlement resistance is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steel smelting, in particular to a high-strength austenitic stainless steel for lining of a deep cryogenic high-pressure hydrogen storage container and a preparation method thereof. BACKGROUND

[0002] Hydrogen has three common phase states: gaseous, liquid, and solid. Deep cryogenic high-pressure supercritical state is when the temperature range is between 33K (-240℃) and 77K (-196℃), and the pressure is greater than 35MPa, hydrogen enters a supercritical state.

[0003] Currently, the conventional storage methods of hydrogen mainly include gaseous storage, liquid storage, and solid storage. Supercritical hydrogen storage CcH2 is a new type of storage and transportation form that has appeared in recent years, and it is currently the physical hydrogen storage method with the largest energy density. Its safety is higher than that of high-pressure gaseous hydrogen, and its leakage rate is lower than that of liquid hydrogen. The LLNL laboratory in the United States first carried out research on supercritical hydrogen storage technology, and cooperated with BMW to develop a low-temperature high-pressure container, which completed field testing in 2010 and can meet the service environment of 35MPa and 77K. The low-temperature high-pressure container adopts a double-layer structure, the inner layer material is 316 stainless steel + carbon fiber reinforcement, the outer layer material is 304 stainless steel, and the interlayer is vacuum insulation material. It is found that when the pressure increases to 70MPa, the supercritical hydrogen density can reach 85g / L, which is the largest among the current hydrogen storage methods. Deep cryogenic high-pressure supercritical hydrogen storage has two extreme working conditions of deep cryogenic and high pressure, so the inner layer material should have high strength, high toughness, and hydrogen embrittlement resistance under the combined action of deep cryogenic and high pressure hydrogen environment.

[0004] Currently, the strength of 316 stainless steel is relatively low, and the standard stipulates that the yield strength thereof is generally not less than 205MPa. Therefore, it is particularly important to improve the strength of traditional austenitic stainless steel without losing the hydrogen embrittlement resistance of the material.

[0005] Therefore, it is particularly important to propose an austenitic stainless steel with high strength and good hydrogen embrittlement resistance. SUMMARY

[0006] The present application aims to provide a high-strength austenitic stainless steel for lining of a deep cryogenic high-pressure hydrogen storage container and a preparation method thereof. This method forms tempered martensite in the equiaxed austenitic structure, and the obtained stainless steel not only retains good hydrogen embrittlement resistance, but also improves the mechanical strength.

[0007] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] The application discloses a preparation method of high-strength austenitic stainless steel for a cryogenic high-pressure hydrogen storage container liner.

[0009] Further, the austenitic stainless steel material blank is subjected to rolling treatment to obtain an equiaxed austenitic structure; and the equiaxed austenitic structure is subjected to ultralow-temperature rolling treatment and then low-temperature tempering to obtain the high-strength austenitic stainless steel for the cryogenic high-pressure hydrogen storage container liner.

[0010] Further, the rolling treatment of the austenitic stainless steel material blank comprises the following steps:

[0011] The austenitic stainless steel material blank is prepared, and the austenitic stainless steel material blank is processed into a primary product;

[0012] The primary product is subjected to solid solution treatment, and is subjected to rolling deformation treatment to obtain a product, and the product is an equiaxed austenitic structure.

[0013] Further, the preparation method of the austenitic stainless steel material blank comprises the following steps: austenitic stainless steel raw materials are mixed and smelted, a cast ingot is obtained through casting, and the cast ingot is processed into a material blank.

[0014] Further, the strain rate of the rolling deformation treatment is 0.05-0.1 s -1 , and the deformation amount of rolling is 50-60%.

[0015] Further, the ultralow-temperature rolling treatment comprises the following steps: the ultralow-temperature condition is 77K-173K.

[0016] Further, the rolling treatment adopts multi-step rolling, the total rolling amount is 40-60%, and the rolling speed is 200-400mm / s.

[0017] Further, after the equiaxed austenitic structure is subjected to the ultralow-temperature rolling treatment, the equiaxed austenitic structure is subjected to low-temperature holding treatment, is then heated, is immediately cooled, and is subjected to water quenching to obtain a tempered martensite reinforced type internal hydrogen embrittlement resistant austenitic stainless steel.

[0018] Further, the low-temperature holding treatment comprises the following steps: after being placed at room temperature, the equiaxed austenitic structure is heated, the heating temperature is 260-310 DEG C, and the holding time is 240-420min; the tempering treatment comprises the following steps: the equiaxed austenitic structure is heated to 600-685 DEG C, is immediately cooled, and the cooling speed is 1-2 DEG C / s.

[0019] The application further provides a preparation method of high-strength austenitic stainless steel for a cryogenic high-pressure hydrogen storage container liner,

[0020] The method comprises the following steps:

[0021] S1, preparing an austenitic stainless steel material blank, and processing the austenitic stainless steel material blank into a preliminary product;

[0022] S2, subjecting the preliminary product to high-temperature solid solution treatment, and performing rolling deformation treatment to obtain a product, wherein the product is an equiaxed austenitic structure;

[0023] S3, subjecting the product to rolling treatment under super-low temperature conditions;

[0024] S4, subjecting the product after the super-low temperature rolling to medium-low temperature holding treatment, and then to low-temperature tempering;

[0025] Low-temperature tempering: subjecting the product after the holding treatment to temperature rising, and then to temperature falling, and then to water quenching to obtain the high-strength austenitic stainless steel for the inner liner of the cryogenic high-pressure hydrogen storage container.

[0026] In S1, the preparation method of the austenitic stainless steel material blank is as follows: austenitic stainless steel raw materials are mixed and smelted to obtain an ingot, and the ingot is processed into a material blank.

[0027] The austenitic stainless steel raw materials include the following components in percentage by mass: 8-10% of Ni, 18-19% of Cr, 2.0-3.0% of Mo, 2.0-3.0% of Cu, 0.03-0.08% of C, 0.2-0.5% of Si, 5.0-7.0% of Mn, 0.15-0.5% of Nb, 0.15-0.5% of V, 0.15-0.30% of Ti, ≤0.03% of P, and ≤0.01% of S, and the balance is Fe.

[0028] In S2, the strain rate of the rolling deformation treatment is 0.05-0.1 s -1 , and the deformation amount is 60%; and the temperature of the high-temperature solid solution treatment is 1100-1200°C.

[0029] In S3, the rolling treatment adopts a multi-step rolling process, and the total rolling amount is 40-60%, and the rolling rate is 200-400 mm / s.

[0030] In S4, after the sample obtained in S3 is placed at room temperature, the sample is subjected to temperature rising, the temperature rising is 260-310°C, and the holding time is 240-420 min; the product after the holding treatment is subjected to temperature rising, and when the temperature rises to a target temperature, the temperature falling is immediately performed at a rate of 1-2°C / s, and the target temperature is 600-685°C.

[0031] The application also protects the high-strength austenitic stainless steel for the inner liner of the cryogenic high-pressure hydrogen storage container prepared by the above method.

[0032] The application also protects the application of the high-strength austenitic stainless steel for lining of the cryogenic high-pressure hydrogen storage container in the hydrogen storage pressure container.

[0033] The application provides a preparation method of a tempered martensite reinforced type internal hydrogen embrittlement resistant austenitic stainless steel.

[0034] Beneficial effects:

[0035] The preparation method provided by the application realizes the obtaining of partial martensite structure in the austenitic matrix by inducing martensite phase transition in the austenitic matrix under the ultra-low temperature condition, and then forms the uniformly distributed nano precipitates in the austenitic structure through the medium-low temperature tempering and temperature rising and falling processes, so that the austenitic stainless steel with high strength and internal hydrogen embrittlement resistance is obtained.

[0036] The application also provides a high-strength austenitic stainless steel for lining of a cryogenic high-pressure hydrogen storage container, which is prepared by the preparation method. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0038] Figure 1 is an austenitic grain diagram obtained by example 1 in the specific embodiment of the application;

[0039] Figure 2 is a martensite / austenite structure diagram of the stainless steel obtained by example 1 in the specific embodiment of the application;

[0040] Figure 3: This is the nano-precipitated phase diagram in Example 1 of the specific embodiments of the present invention. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0042] Example 1:

[0043] Preliminary part preparation: The alloy material is smelted to obtain molten steel with the target alloy content, which is then continuously cast into a continuous casting billet, and then hot rough rolling is used to make the preliminary part.

[0044] The alloy material is a tempered martensitic-reinforced austenitic stainless steel resistant to internal hydrogen embrittlement, with the following mass percentages: Ni 8.5%, Cr 19.5%, Mo 2.5%, Cu 3.0%, Mn 5.5%, C 0.03%, Si 0.2%, Nb 0.30%, V 0.20%, Ti 0.15%, P 0.03%, S 0.01%, and the remainder being Fe.

[0045] Part preparation: The initial part thickness is 60 mm, heated to 1150 °C at a rate of 30 °C / s; held at this temperature for 5 min, and then subjected to a strain rate of 0.08 s. -1 The material is then rolled and deformed by 60% to obtain the finished part, i.e., equiaxed austenitic stainless steel. Figure 1 It can be seen that the obtained stainless steel is equiaxed austenitic stainless steel.

[0046] Martensitic transformation: The workpiece was immersed in low-temperature alcohol at 173K for 20 minutes and then rolled at a rolling deformation rate of 200 mm / s. The deformation amount of the rolling deformation was 50%, and the martensite in the obtained steel body accounted for about 20%.

[0047] Martensitic tempering: The temperature is increased at a rate of 5℃ / s, and when the temperature reaches 260℃, it is held for 420 minutes. After holding, the temperature is increased to 650℃ at a rate of 10℃ / s. When the temperature reaches 650℃, it is held for 2 minutes, and then cooled at a rate of 2℃ / s. When the temperature reaches 500℃, it is water-quenched to obtain stainless steel.

[0048] Depend on Figure 2 It is evident that martensite is formed in austenitic stainless steel, while... Figure 3 It is evident that the tempering process precipitated nanophases.

[0049] Example 2

[0050] Preparation of the initial piece: the alloy material is smelted to obtain a molten steel with a target alloy content, and then a continuous casting billet is generated, and then a hot rough rolling process is used to prepare the initial piece;

[0051] The alloy material is a hydrogen embrittlement resistant precipitation strengthened iron-nickel-based alloy material, and the mass percentages are as follows: Ni 9%; Cr 19.5%; Mo 2.0%; Cu 3.0%; C 0.06%; Si 0.3%; Mn 5.5%; Nb 0.50%; V 0.50%; Ti 0.10%; P 0.03%; S 0.01%; and the remainder is Fe.

[0052] Preparation of the piece: the thickness of the initial piece is 50 mm, and the temperature is raised to 1100℃ at a rate of 30℃ / s; the temperature is maintained for 5 min, and rolling deformation is performed at a strain rate of 0.05 s -1 , and the deformation amount is 60%, to obtain the piece.

[0053] Martensitic phase transformation: in low-temperature alcohol, the temperature is controlled at 173K, the piece is soaked for 30 min, and then rolling treatment is performed at a rolling deformation rate of 300 mm / s; the deformation amount of the rolling deformation is 60%, and the obtained steel body contains about 30% of martensite.

[0054] Martensite tempering: the temperature is raised at a rate of 5℃ / s, and when the temperature reaches 310℃, the temperature is maintained for 240 min; after the temperature maintaining is completed, temperature rising treatment is performed, the temperature rising rate is 5℃ / s, and when the temperature rises to 675℃, it is kept for 1.5 min, and then the temperature is lowered at a cooling rate of 1℃ / s, and when the temperature reaches 530℃, water quenching is performed, to obtain the stainless steel.

[0055] Example 3

[0056] Preparation of the initial piece: the alloy material is smelted to obtain a molten steel with a target alloy content, and then a continuous casting billet is generated, and then a hot rough rolling process is used to prepare the initial piece;

[0057] The alloy material is a tempering martensite reinforced type internal hydrogen embrittlement resistant austenitic alloy material, and the mass percentages are as follows: Ni 9.5%; Cr 18.5%; Mo 2.5%; Cu 2.0%; Mn 6.5%; C 0.03%; Si 0.5%; Nb 0.15-0.5%; V 0.15-0.5%; Ti 0.10-0.3%; P 0.03%; S 0.01%; and the remainder is Fe.

[0058] Preparation of the piece: the thickness of the initial piece is 60 mm, and the temperature is raised to 1200℃ at a rate of 30℃ / s; the temperature is maintained for 5 min, and rolling deformation is performed at a strain rate of 0.07 s -1, the rolling deformation is performed at a deformation rate of 400 mm / s, and a deformation amount of the rolling deformation is 60%, to obtain the product.

[0059] Martensite phase transformation: the product is soaked in liquid nitrogen at a temperature of 77 K for 40 min, and then rolling treatment is performed at a rolling deformation rate of 400 mm / s; a deformation amount of the rolling deformation is 60%, and about 30% of the obtained martensite accounts for the steel body.

[0060] Martensite tempering: the temperature is increased at a rate of 3 °C / s, and when the temperature reaches 310 °C, the temperature is kept for 360 min; after the temperature keeping is completed, temperature increasing treatment is performed at a temperature of 685 °C and a temperature increasing rate of 10 °C / s; when the temperature reaches 685 °C, the temperature is kept for 2 min, and then the temperature is decreased at a cooling rate of 1.5 °C / s, and when the temperature reaches 500 °C, water quenching is performed, to obtain the stainless steel.

[0061] Example 4

[0062] Preparation of the product: the alloy material is smelted to obtain molten steel with a target alloy content, and then a continuous casting blank is generated through continuous casting, and then the initial product is prepared through a hot rough rolling process;

[0063] The alloy material is a tempered martensite reinforced anti-internal hydrogen embrittlement austenitic alloy material, and the mass percentage is Ni 10%; Cr 18%; Mo 3.0%; Cu 2.0%; Mn 5%; C 0.08%; Si 0.5%; Nb 0.3%; V 0.25%; Ti 0.10%; P 0.03%; S 0.01%; and the rest is Fe.

[0064] Preparation of the product: the thickness of the initial product is 40 mm, the temperature is increased to 1100 °C at a rate of 30 °C / s, and the temperature is kept for 5 min; the rolling deformation is performed at a strain rate of 0.08 s -1 , and a deformation amount of the rolling deformation is 50%, to obtain the product.

[0065] Martensite phase transformation: the product is soaked in liquid nitrogen at a temperature of 77 K for 30 min, and then rolling treatment is performed at a rolling deformation rate of 350 mm / s; a deformation amount of the rolling deformation is 50%, and about 25% of the obtained martensite accounts for the steel body.

[0066] Martensite tempering: the temperature is increased at a rate of 5 °C / s, and when the temperature reaches 375 °C, the temperature is kept for 420 min; after the temperature keeping is completed, temperature increasing treatment is performed at a temperature of 620 °C and a temperature increasing rate of 5 °C / s; when the temperature reaches 620 °C, the temperature is kept for 2 min, and then the temperature is decreased at a cooling rate of 2 °C / s, and when the temperature reaches 420 °C, water quenching is performed, to obtain the stainless steel.

[0067] Comparative Example 1

[0068] A commercial 304 stainless steel hot-rolled plate is milled to the upper and lower surface finish, the milled material is vacuum sealed and then heat treated at 1100°C in an air furnace for 1 hour, after which it is rapidly water quenched, and then the quenched 304 stainless steel plate is soaked for 30 minutes. Then direct ultra-low temperature cold rolling deformation is carried out to obtain a rolled plate with a deformation of 80%, and finally the plate is heat treated and annealed at a temperature of 850°C for 5 minutes to obtain the stainless steel.

[0069] Comparative Example 2

[0070] Preparation of the initial piece: The alloy material is smelted to obtain a molten steel with a target alloy content, and then a continuous casting billet is formed, and then a hot rough rolling process is used to form the initial piece;

[0071] The alloy material is a tempered martensite reinforced anti-internal hydrogen embrittlement austenitic stainless steel material, with a mass percentage of Ni 8.5%, Cr 19.5%, Mo 2.5%, Cu 3.0%, Mn 5.5%, C 0.03%, Si 0.2%, Nb 0.30%, V 0.20%, Ti 0.15%, P 0.03%, S 0.01%, and the remainder being Fe.

[0072] Preparation of the piece: the initial piece has a thickness of 60mm, and is heated to 1150°C at a rate of 30°C / s; it is held for 5min, and then rolled at a strain rate of 0.08s -1 , with a deformation of 60% to obtain the piece, i.e. an equiaxed austenitic stainless steel.

[0073] Martensite phase transformation: the piece is soaked in low-temperature alcohol at a temperature of 173K for 20min, and then rolled at a rolling deformation rate of 200mm / s; the deformation of the rolling deformation is 50%, and the obtained steel body has about 20% martensite.

[0074] Martensite tempering: heat treatment annealing is carried out at a temperature of 850°C for 5min.

[0075] For the performance comparison test of the above-mentioned high-strength austenitic stainless steel and 304L and 316L, longitudinal round bar slow tensile specimens of the austenitic stainless steel prepared in the embodiment, 304L and 316L are taken, the diameter of the parallel section of the specimen is 5mm, the length of the parallel section is 25mm, the strain rate is 5x10 -6 s -1 , the test temperature is -40°C, and the slow tensile test is carried out under vacuum and high temperature and high pressure (35MPa, 80°C) hydrogen charging conditions respectively, and the test results are shown in Table 1 below:

[0076] Table 1

[0077]

[0078] As shown in Table 1, the stainless steel obtained in Examples 1-4 has a yield strength of 521-555 MPa at room temperature, a reduction of area of 78%-83% at 77 K, a reduction of area of 55%-63% in an environment containing internal hydrogen at 77 K, and a relative reduction of area of 70.1%-78.8%. The stainless steel has very good strength and toughness, and very good resistance to internal hydrogen embrittlement, and is suitable for a deep cold high-pressure hydrogen service environment, i.e., is suitable for use in a hydrogen storage pressure vessel.

[0079] Comparative Example 1 uses 304 stainless steel, which is subjected to ultra-low temperature cold rolling deformation and then heat treatment annealing. The mechanical strength and hydrogen embrittlement resistance of the obtained stainless steel are obviously insufficient compared to Examples 1-4. As shown in Comparative Example 2 and Example 1, direct use of conventional heat treatment annealing results in a stainless steel having mechanical strength and hydrogen embrittlement resistance that are much lower than those of Example 1.

[0080] Compared to existing 304L and 316L stainless steels, the strength and hydrogen embrittlement sensitivity of the tempered martensite reinforced internal hydrogen embrittlement resistant austenitic stainless steel prepared in the examples of the present application are all superior to those of 304L and 316L and Comparative Examples 1-2, i.e., the present application forms tempered martensite in the austenite, which ensures the mechanical strength of the stainless steel while also improving the resistance to internal hydrogen embrittlement.

Claims

1. A method for producing a high-strength austenitic stainless steel for a liner of a cryogenic high-pressure hydrogen storage container, characterized by, The austenitic stainless steel material blank is subjected to rolling treatment to obtain an equiaxed austenitic structure; the equiaxed austenitic structure is subjected to super-low temperature rolling treatment and then low-temperature tempering to obtain high-strength austenitic stainless steel for inner lining of a deep cold high-pressure hydrogen storage container.

2. The production method according to claim 1, characterized by, The austenitic stainless steel material blank is subjected to rolling treatment, including: Preparing an austenitic stainless steel material blank, and processing the austenitic stainless steel material blank into a preliminary product; Subjecting the preliminary product to solid solution treatment and rolling deformation treatment to obtain a product, wherein the product is an equiaxed austenitic structure.

3. The production method according to claim 2, characterized by, The preparation method of the austenitic stainless steel material blank is as follows: mixing austenitic stainless steel raw materials, melting and casting to obtain an ingot, and processing the ingot into a material blank.

4. The preparation method according to claim 2, characterized in that, The strain rate of the rolling deformation treatment is 0.05-0.1 s -1 , and the deformation amount of rolling is 50-60%.

5. The preparation method according to claim 1, characterized in that, The super-low temperature rolling treatment includes: Subjecting the equiaxed austenitic structure to stay under super-low temperature conditions and rolling treatment, wherein the super-low temperature conditions are 77K-173K.

6. The production method according to claim 5, characterized by, The rolling treatment adopts multi-step rolling, and the total rolling amount is 40-60%, and the rolling speed is 200-400mm / s.

7. The preparation method according to claim 1, characterized in that, After the equiaxed austenitic structure is subjected to super-low temperature rolling treatment, low-temperature holding treatment is first performed, then the temperature is raised, and then the temperature is lowered to perform water quenching, thereby obtaining a tempered martensite reinforced anti-internal hydrogen embrittlement austenitic stainless steel.

8. The preparation method according to claim 7, characterized in that, The low-temperature holding treatment: after being placed at room temperature, the temperature is raised, the temperature for the temperature raising is 260-310℃, and the holding time is 240-420min; the tempering treatment: after being raised to 600-685℃, the temperature is immediately lowered, and the lowering speed is 1-2℃ / s.

9. High-strength austenitic stainless steel for inner lining of a deep cold high-pressure hydrogen storage container prepared by the method of any one of claims 1-8.

10. Application of the high-strength austenitic stainless steel for inner lining of a deep cold high-pressure hydrogen storage container of claim 9 in a hydrogen storage pressure container.

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