Low-alloy high-strength hydrogen-resistant steel and preparation method thereof

Abstract

The invention relates to low-alloy high-strength hydrogen-resistant steel and a preparation method thereof, and belongs to the technical field of steel and iron materials. The low-alloy high-strength hydrogen-resistant steel comprises the following components in percentage by mass: 0.10%-0.25% of carbon, 0.10%-0.50% of silicon, 0.001%-0.09% of manganese, 0.03%-0.09% of aluminum, 1.0%-2.0% of nickel, 0.20%-0.60% of chromium, 0.20%-1.0% of molybdenum, 0.01%-0.05% of vanadium, 0.01%-0.04% of titanium, 0.001%-0.006% of boron and the balance of iron and impurity elements, in the impurity elements, sulfur is not more than 0.005%, phosphorus is not more than 0.01%, and nitrogen is not more than 0.004%. The low-alloy high-strength hydrogen-resistant steel is prepared through forging stock preparation, rolling treatment, quenching treatment and tempering treatment. The low-alloy high-strength hydrogen-resistant steel disclosed by the invention has the characteristics of high strength, good toughness matching performance and relatively low hydrogen embrittlement sensitivity, and is particularly suitable for being used as a material of a hydrogen storage and transportation container.

Description

Technical Field

[0001] The invention relates to a low-alloy high-strength hydrogen-resistant steel and a preparation method thereof, belonging to the technical field of steel materials. Background Art

[0002] Hydrogen energy has become the focus of energy transformation around the world due to its many advantages such as cleanliness, high energy conversion efficiency, storability and sustainability. The hydrogen energy industry chain covers a wide range and is long-term, and its main links include the preparation, storage, transportation, refueling and terminal utilization of hydrogen energy. As two important links in the hydrogen energy industry chain, the storage and transportation of hydrogen energy are the core guarantee for the large-scale development and utilization of hydrogen energy.

[0003] At present, the main methods of hydrogen energy storage include high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage, liquid organic hydrogen storage, metal hydride hydrogen storage, and adsorption hydrogen storage. One of the core foundations for the large-scale development of the hydrogen energy industry is the large-scale storage and transportation of hydrogen energy. Among the existing hydrogen energy storage technologies, liquid organic hydrogen storage and solid hydrogen storage are still in the development stage, while low-temperature liquid hydrogen storage technology has achieved certain applications in aerospace and other fields. Compared with the various existing hydrogen storage technologies, high-pressure gaseous hydrogen storage has the potential to become a large-scale hydrogen storage and transportation implementation technology due to its simple equipment structure, low energy consumption for compressed hydrogen preparation, fast charging and discharging speed, and wide temperature adaptability.

[0004] However, high-pressure gaseous hydrogen storage technology has high technical requirements for high-pressure hydrogen storage and transportation containers. This is because under the dual effects of high pressure and hydrogen environment, hydrogen atoms will diffuse into the interior of the hydrogen storage container, causing plastic loss of the container material and accelerating the crack growth rate, that is, "hydrogen embrittlement". "Hydrogen embrittlement" is a key factor leading to the failure of high-pressure hydrogen storage and transportation containers, and has a significant negative effect on the safety of large-scale hydrogen energy storage.

[0005] The tank body of the high-pressure hydrogen storage container in the prior art is usually made of steel materials, mostly 316L austenitic stainless steel and Cr-Mo alloy steel. 316L austenitic stainless steel has excellent corrosion resistance, good formability and easy welding; however, 316L austenitic stainless steel has low mechanical strength and contains a high Ni content (generally 10% to 14%), resulting in high production costs and is not suitable for large-scale applications. Cr-Mo alloy steel has the characteristics of low production cost, high strength and good quenching performance; however, the Mn content in Cr-Mo alloy steel is usually above 0.5%, which limits its hydrogen resistance.

[0006] Therefore, designing and developing materials suitable for high-pressure hydrogen storage and transportation containers has significant practical significance and engineering value. Since materials for high-pressure hydrogen storage and transportation containers need to have high strength and good strength-toughness matching while ensuring low hydrogen embrittlement sensitivity, it is still difficult for technicians in this field to achieve technical difficulties. Summary of the invention

[0007] In order to improve the problems of low strength and toughness and poor hydrogen embrittlement resistance of existing hydrogen storage and transportation container materials, one of the purposes of the present invention is to provide a low-alloy high-strength hydrogen-resistant steel; the low-alloy high-strength hydrogen-resistant steel has the characteristics of high strength, good strength-toughness matching performance and low hydrogen embrittlement sensitivity.

[0008] A second object of the present invention is to provide a method for preparing low-alloy high-strength hydrogen-resistant steel.

[0009] To achieve the purpose of the present invention, the following technical solutions are provided.

[0010] A low-alloy high-strength hydrogen-resistant steel, wherein the mass of the low-alloy high-strength hydrogen-resistant steel is 100%, wherein the components and their mass fractions are as follows:

[0011]

[0012] The balance is iron (Fe) and unavoidable impurity elements;

[0013] Among the impurity elements, sulfur (S) ≤ 0.005%, phosphorus (P) ≤ 0.01%, and nitrogen (N) ≤ 0.004%; the aluminum is acid-soluble aluminum (Als).

[0014] Furthermore, taking the mass of the low-alloy high-strength hydrogen-resistant steel as 100%, the preferred components and their mass fractions are as follows:

[0015]

[0016]

[0017] A method for preparing the low-alloy high-strength hydrogen-resistant steel according to the present invention, the preparation method comprises the following steps:

[0018] (1) Preparing forging blanks: According to the components and mass fractions of the low-alloy high-strength hydrogen-resistant steel, batching, vacuum melting, casting and forging are performed to obtain forging blanks;

[0019] (2) rolling treatment: heating the forging billet obtained in step (1) to 1150° C. to 1250° C., keeping the temperature constant for 1 h to 2 h, rolling it, and air cooling it to room temperature to prepare a billet after rolling treatment;

[0020] (3) quenching treatment: heating the rolled blank obtained in step (2) to 870° C. to 890° C., keeping the temperature constant for 0.8 h to 1.2 h, and then water cooling the blank to obtain a quenched steel material;

[0021] (4) Tempering treatment: The steel material obtained after quenching treatment in step (3) is heated to 670° C. to 690° C., kept at a constant temperature for 1.3 h to 1.7 h, and then air-cooled to prepare the low-alloy high-strength hydrogen-resistant steel described in the present invention.

[0022] Preferably, in step (2): the forging blank obtained in step (1) is heated to 1170°C to 1220°C.

[0023] Preferably, in step (3), the rolled blank obtained in step (2) is heated to 870° C. to 880° C. and kept at the constant temperature for 0.9 h to 1.1 h.

[0024] Preferably, in step (4), the quenched steel obtained in step (3) is heated to 670° C. to 680° C. and kept at a constant temperature for 1.4 h to 1.6 h.

[0025] Beneficial Effects

[0026] (1) The present invention provides a low-alloy high-strength hydrogen-resistant steel. Compared with the prior art, the low-alloy high-strength hydrogen-resistant steel has lower hydrogen embrittlement sensitivity in an in-situ electrochemical hydrogen charging environment, and the ratio of the elongation after slow strain rate tensile fracture under in-situ electrochemical hydrogen charging and air conditions is not less than 85%; at the same time, the yield strength of the low-alloy high-strength hydrogen-resistant steel is ≥750MPa, the tensile strength is ≥800MPa, and the impact absorption energy at -40°C is ≥250J, taking into account excellent strength and low-temperature impact toughness, and is particularly suitable for use as a material for hydrogen storage and transportation containers.

[0027] (2) The present invention provides a low-alloy high-strength hydrogen-resistant steel, which obtains high strength, excellent strength-toughness matching characteristics, and at the same time takes into account good hydrogen embrittlement resistance by designing the types and contents of alloying elements of the main components; wherein the mass fraction of the Mn element is greatly reduced relative to the Mn content in the prior art (usually above 0.50%); the inventors have found through creative labor that when the Mn addition exceeds 0.001%, it has a certain deoxidation and desulfurization effect in the steel, and can be dissolved in austenite and ferrite to increase the strength and hardness of the steel; therefore, the mass fraction of the Mn element in the present invention shall not be less than 0.001%. At the same time, when the Mn addition exceeds 0.09%, the hydrogen embrittlement sensitivity of the steel will be significantly increased, and the impact toughness of the steel will be reduced. Therefore, the mass fraction of Mn shall not exceed 0.09%. In summary, the mass fraction of the Mn element in the present invention is 0.001% to 0.09%.

[0028] (3) The present invention provides a low-alloy high-strength hydrogen-resistant steel, which obtains high strength and excellent strength-toughness matching characteristics by designing other components and cooperating with each other, while taking into account good hydrogen embrittlement resistance, wherein:

[0029] The C element can improve the strength, hardness, and wear resistance of steel, and enhance the hardenability of steel; however, too high a C content will increase the brittleness of the steel, reduce its toughness and corrosion resistance, and deteriorate its weldability; therefore, the mass fraction of C in the present invention is controlled at 0.10% to 0.25%;

[0030] The Si element can increase the strength and hardness of steel and improve the wear resistance of steel; however, too high Si content is often not conducive to the plasticity and toughness of steel and deteriorates the welding performance of steel. Therefore, the mass fraction of Si in the present invention is controlled to be 0.10% to 0.50%;

[0031] The Al element is a deoxidizing and nitrogenating agent for molten steel, which can improve the martensitic transformation temperature, oxidation resistance and corrosion resistance of steel; however, excessive Al element will deteriorate the welding performance and cutting performance of steel; therefore, the mass fraction of Al in the present invention is controlled to be 0.03% to 0.09%;

[0032] Ni is an important alloying element for stabilizing austenite, and also has a certain positive effect on the hardenability and tempering stability of steel; considering the scarcity and price of Ni, the mass fraction of Ni in the present invention is controlled at 1.0% to 2.0%;

[0033] The Cr element can form a variety of carbides with the C element in steel, thereby improving the strength, hardness and wear resistance of the steel, and improving the oxidation resistance and corrosion resistance of the steel; however, excessive Cr addition will cause the impact toughness of the steel to decrease rapidly and increase the temper brittleness of the steel; therefore, the mass fraction of Cr in the present invention is controlled to be 0.20% to 0.60%;

[0034] The Mo element has a solid solution strengthening effect, which can increase the strength of steel and improve the hardenability of steel; however, excessive Mo elements will deteriorate the oxidation resistance of steel and increase the difficulty of steel processing; therefore, the mass fraction of Mo in the present invention is controlled to be 0.20% to 1.0%;

[0035] The V element can form compounds with the C and N elements in the steel, thereby increasing the strength and toughness of the steel and improving the steel's resistance to hydrogen embrittlement. However, excessive V addition is detrimental to the strength and toughness of the steel. Therefore, the mass fraction of V in the present invention is controlled at 0.01% to 0.05%.

[0036] The Ti element can refine the grains and improve the strength, toughness and hydrogen corrosion resistance of the steel; however, too high a Ti addition is not conducive to the strength and toughness of the steel; therefore, the mass fraction of Ti in the present invention is controlled at 0.01% to 0.04%;

[0037] The B element can improve the hardenability of steel and increase the strength of steel after quenching and low-temperature tempering; however, excessive B will cause hot brittleness of steel, which is not conducive to the hot working performance of steel; therefore, the mass fraction of B in the present invention is controlled to be 0.001% to 0.006%;

[0038] As unavoidable impurities, S and P elements will lead to a significant decrease in the impact toughness of steel. In order to obtain the low-alloy high-strength hydrogen-resistant steel of the present invention, it is necessary to control the mass fraction of S element to not exceed 0.005%, and the mass fraction of P element to not exceed 0.01%;

[0039] As an unavoidable impurity, N element will cause quenching aging and strain aging of steel, which will increase the strength and hardness of the steel, while reducing the plasticity and toughness; in addition, excessive N element is difficult to completely dissolve into the steel, which will cause casting defects such as looseness or pores in the steel; therefore, the mass fraction of N element in the present invention shall not exceed 0.004%.

[0040] (4) The present invention provides a method for preparing low-alloy high-strength hydrogen-resistant steel. In step (2) of the method, the forging blank is heated to 1150°C to 1250°C and kept at a constant temperature for 1h to 2h, so that a relatively uniform austenite structure can be obtained; when the heating temperature is too high or the holding time is too long, the forging blank is prone to oxidation and decarburization, thereby reducing the quality of the slab after rolling; when the heating temperature is too low or the holding time is too short, it is not conducive to the complete austenitization of the forging blank, and it is difficult to ensure a scientific final rolling temperature.

[0041] (5) The present invention provides a method for preparing low-alloy high-strength hydrogen-resistant steel. In step (3) of the method, the blank is heated to 870°C to 890°C and kept at a constant temperature for 0.8h to 1.2h, so that a relatively uniform and fine austenite structure can be obtained, which is beneficial to improving the performance of the product. When the heating temperature is too high or the heating time is too long, austenite coarsening is likely to occur, which is not conducive to the mechanical strength and impact toughness of the product. When the heating temperature is too low or the heating time is too short, it is difficult to ensure complete austenitization.

[0042] (6) The present invention provides a method for preparing low-alloy high-strength hydrogen-resistant steel. In step (4) of the method, the steel after quenching treatment is heated to 670°C to 690°C and kept at a constant temperature for 1.3h to 1.7h, thereby achieving a good match between strength and toughness. If the heating temperature is too high or too low, or the heating time is too short or too long, it is difficult to obtain a good strength-toughness matching characteristic. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the microscopic morphology of the radial area of ​​the impact fracture of the steel prepared in Example 1.

[0044] Figure 2 This is the microscopic morphology of the radial area of ​​the impact fracture of the steel prepared in Comparative Example 1.

[0045] Figure 3 This is the overall morphology of the slow strain rate tensile fracture of the steel prepared in Example 1 in an air environment.

[0046] Figure 4 This is the overall morphology of the slow strain rate tensile fracture of the steel prepared in Comparative Example 1 in an air environment.

[0047] Figure 5 The overall morphology of the slow strain rate tensile fracture of the steel prepared in Example 1 under an in-situ electrochemical hydrogen charging environment.

[0048] Figure 6 This is the overall morphology of the slow strain rate tensile fracture of the steel prepared in Comparative Example 1 under an in-situ electrochemical hydrogen charging environment. DETAILED DESCRIPTION

[0049] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0050] Example 1

[0051] A low-alloy high-strength hydrogen-resistant steel, wherein the mass of the low-alloy high-strength hydrogen-resistant steel is 100%, wherein the components and their mass fractions are as follows:

[0052] C 0.17%, Si 0.23%, Mn 0.042%, Al 0.045%, Ni 1.52%, Cr 0.39%, Mo0.52%, V 0.031%, Ti 0.019%, B 0.004%, the balance is Fe and unavoidable impurity elements, among which S 0.0031%, P<0.005%, N 0.001%; ​​the aluminum is acid-soluble aluminum (Als).

[0053] The steps of the preparation method of the low alloy high strength hydrogen resistant steel described in this embodiment are as follows:

[0054] (1) preparing a forging blank: preparing ingredients, vacuum melting, casting and forging according to the components and mass fractions of the low-alloy high-strength hydrogen-resistant steel to obtain a forging blank;

[0055] (2) Rolling treatment: the forging billet obtained in step (1) is placed in a heat treatment furnace and heated to 1170° C., kept at a constant temperature for 2 h, and then rolled for 6 times, and air-cooled to room temperature to obtain a billet after rolling treatment, which is a steel plate billet with a thickness of 16 mm;

[0056] (3) Quenching treatment: the rolled blank obtained in step (2) is heated to 880° C., kept at a constant temperature for 0.9 h, and then water-cooled to obtain a quenched steel plate;

[0057] (4) Tempering treatment: The steel plate obtained after quenching treatment in step (3) is heated to 680° C., kept at a constant temperature for 1.4 h, and then air-cooled to prepare a low-alloy high-strength hydrogen-resistant steel.

[0058] Example 2

[0059] A low-alloy high-strength hydrogen-resistant steel, wherein the mass of the low-alloy high-strength hydrogen-resistant steel is 100%, wherein the components and their mass fractions are as follows:

[0060] C 0.12%, Si 0.43%, Mn 0.079%, Al 0.039%, Ni 1.18%, Cr 0.56%, Mo0.28%, V 0.039%, Ti 0.019%, B 0.002%, the balance is Fe and unavoidable impurity elements, among which S 0.0023%, P<0.005%, N 0.0007%; the aluminum is acid-soluble aluminum (Als).

[0061] The steps of the preparation method of the low alloy high strength hydrogen resistant steel described in this embodiment are as follows:

[0062] (1) preparing a forging blank: preparing ingredients, vacuum melting, casting and forging according to the components and mass fractions of the low-alloy high-strength hydrogen-resistant steel to obtain a forging blank;

[0063] (2) Rolling treatment: the forging billet obtained in step (1) is placed in a heat treatment furnace and heated to 1220° C., kept at a constant temperature for 1 hour, and then rolled for 6 times, and air-cooled to room temperature to obtain a billet after rolling treatment, which is a steel plate billet with a thickness of 16 mm;

[0064] (3) Quenching treatment: the rolled blank obtained in step (2) is heated to 870° C., kept at a constant temperature for 1.1 h, and then water-cooled to obtain a quenched steel plate;

[0065] (4) Tempering treatment: The steel plate obtained after quenching treatment in step (3) is heated to 670° C., kept at a constant temperature for 1.6 hours, and then air-cooled to prepare a low-alloy high-strength hydrogen-resistant steel.

[0066] Example 3

[0067] A low-alloy high-strength hydrogen-resistant steel, wherein the mass of the low-alloy high-strength hydrogen-resistant steel is 100%, wherein the components and their mass fractions are as follows:

[0068] C 0.22%, Si 0.14%, Mn 0.0017%, Al 0.081%, Ni 1.87%, Cr 0.27%, Mo0.92%, V 0.02%, Ti 0.038%, B 0.0053%, the balance is Fe and unavoidable impurity elements, among which S 0.0032%, P<0.005%, N 0.0013%; the aluminum is acid-soluble aluminum (Als).

[0069] The steps of the preparation method of the low alloy high strength hydrogen resistant steel of this embodiment are as follows:

[0070] (1) Preparing a forging blank: According to the components and contents of the low-alloy high-strength hydrogen-resistant steel, batching, vacuum melting, casting and forging are performed to obtain a forging blank;

[0071] (2) Rolling treatment: the forging billet obtained in step (1) is placed in a heat treatment furnace and heated to 1200° C., kept at a constant temperature for 1.5 h, and then rolled for 6 times, and air-cooled to room temperature to obtain a billet after rolling treatment, which is a steel plate billet with a thickness of 16 mm;

[0072] (3) Quenching treatment: the rolled blank obtained in step (2) is heated to 880° C., kept at a constant temperature for 1 hour, and then water-cooled to obtain a quenched steel plate;

[0073] (4) Tempering treatment: The steel plate obtained after quenching treatment in step (3) is heated to 680° C., kept at a constant temperature for 1.5 hours, and then air-cooled to prepare a low-alloy high-strength hydrogen-resistant steel.

[0074] Comparative Example 1

[0075] A steel material, wherein the mass of the steel material is 100%, wherein the components and their mass fractions are as follows:

[0076] C 0.13%, Si 0.25%, Mn 1.17%, Al 0.056%, Ni 1.53%, Cr 0.56%, Mo0.52%, V 0.039%, Ti 0.018%, B 0.0015%, the balance is Fe and unavoidable impurity elements, among which S 0.0034%, P<0.005%, N 0.0012%; the aluminum is acid-soluble aluminum (Als).

[0077] The steps of the preparation method of the steel material of this comparative example are as follows:

[0078] (1) Preparing a forging blank: performing batching, vacuum melting, casting and forging according to the components and mass fractions of the steel material to obtain a forging blank;

[0079] (2) Rolling treatment: The forging billet obtained in step (1) is placed in a heat treatment furnace and heated to 1200° C., kept at a constant temperature for 1 hour, and then rolled for 6 times, and air-cooled to room temperature to obtain a billet after rolling treatment, which is a steel plate billet with a thickness of 16 mm;

[0080] (3) Quenching treatment: the rolled blank obtained in step (2) is heated to 840° C., kept at a constant temperature for 1 hour, and then water-cooled to obtain a quenched steel plate;

[0081] (4) Tempering treatment: The quenched steel plate obtained in step (3) is heated to 670° C., kept at a constant temperature for 1.5 hours, and then air-cooled to prepare a steel material.

[0082] Performance Testing

[0083] The following tests and observations were performed on the steels prepared in Example 1, Example 2, Example 3 and Comparative Example 1:

[0084] (1) Conventional mechanical properties test

[0085] According to GB / T 228.1 and GB / T 229, conventional mechanical property tests were carried out on the steels prepared in Example 1, Example 2, Example 3 and Comparative Example 1.

[0086] The test results are shown in Table 1. It can be seen from the data in Table 1 that the mechanical properties of the steels prepared in Example 1, Example 2 and Example 3 all meet the requirements of yield strength ≥ 750 MPa, tensile strength ≥ 800 MPa, and impact absorption energy KV2 at -40°C ≥ 250 J. In contrast, the yield strength of the steel prepared in Comparative Example 1 is lower than 750 MPa, and the impact absorption energy KV2 at -40°C is much lower than 250 J, which does not meet the performance index requirements.

[0087] Table 1 Mechanical properties of steel prepared in Example 1, Example 2, Example 3 and Comparative Example 1

[0088]

[0089]

[0090] (2) Fracture morphology observation

[0091] The microscopic morphologies of the radial zones of the impact fractures of the steels prepared in Example 1 and Comparative Example 1 are as follows: Figure 1 and 2 It can be found that the fracture surface corresponding to Example 1 has a large number of circular or elliptical dimples of different sizes, which is a ductile fracture form; the fracture surface corresponding to Comparative Example 1 has more tearing edges, a small cleavage surface, and an unobvious river pattern, which belongs to a quasi-dissociation fracture.

[0092] The above-mentioned fracture morphology analysis was also carried out on the steels prepared in Example 2 and Example 3, and their morphological states were generally consistent with that of Example 1.

[0093] (3) Slow strain rate tensile test

[0094] Based on GB / T 228.1, the steels prepared in Example 1, Example 2, Example 3 and Comparative Example 1 were processed into smooth round bar tensile specimens, and slow strain rate tensile tests were carried out in an in-situ electrochemical hydrogen charging environment and an air environment. The strain rate was 10 -5 s -1 , the electrolyte is 1mol / L NaOH+1g / L thiourea, the current is 30mA / cm 2 The test results of the elongation ratio after breaking are shown in Table 2. The mathematical expression of the elongation ratio after breaking is as follows:

[0095] Elongation ratio after break R el =(Elongation of the sample after fracture under hydrogen filling condition el H ) / (elongation of the specimen after fracture under reference test conditions el Air )×100%.

[0096] Table 2 Plasticity index of steels prepared in Example 1, Example 2, Example 3 and Comparative Example 1 under slow strain rate tension

[0097]

[0098] From the slow strain rate tensile test results in Table 2, it can be seen that the steel prepared in Example 1 has an elongation ratio of 90.96% under in-situ electrochemical hydrogenation conditions and air conditions; the steel prepared in Example 2 has an elongation ratio of 85.33% under in-situ electrochemical hydrogenation conditions and air conditions; the steel prepared in Example 3 has an elongation ratio of up to 92.47% under in-situ electrochemical hydrogenation conditions and air conditions, all of which show good hydrogen embrittlement resistance. In contrast, the steel prepared in Comparative Example 1 not only does not meet the performance index requirements in terms of yield strength and -40°C impact absorption energy, but also has a lower elongation ratio under in-situ electrochemical hydrogenation environment and reference environment than the steel prepared in Examples 1, 2 and 3, showing more significant hydrogen embrittlement sensitivity.

[0099] (4) Fracture morphology observation

[0100] Figure 3 and 4 The overall morphology of the slow strain rate tensile fracture of the steel prepared in Example 1 and Comparative Example 1 under air environment is shown respectively. It can be found that the tensile fractures under the reference environment corresponding to Example 1 and Comparative Example 1 are both "cup-cone-shaped", with the fiber area and shear lip accounting for a large proportion, while the radial area accounts for a small proportion, which is a ductile fracture. In addition, the overall morphology of the slow strain rate tensile fracture of the steel prepared in Example 1 and Comparative Example 1 under the in-situ electrochemical hydrogen charging environment is as follows: Figure 5 and 6 Compared with the reference environment, the tensile fractures in the hydrogen environment corresponding to Example 1 and Comparative Example 1 are relatively flat, the proportion of the fiber area and the shear lip is significantly reduced, and the proportion of the radial area is significantly increased, which belongs to brittle fracture.

[0101] The above-mentioned fracture morphology analysis was also carried out on the steels prepared in Example 2 and Example 3, and their morphological states were generally consistent with that of Example 1.

Claims

1. A low alloy high strength hydrogen resistant steel, characterized by: Taking the mass of the low-alloy high-strength hydrogen-resistant steel as 100%, the various components and their mass fractions are as follows: The balance is iron and impurity elements; among the impurity elements, sulfur ≤0.005%, phosphorus ≤0.01%, and nitrogen ≤0.004%.

2. The low alloy high strength hydrogen resistant steel according to claim 1, characterized in that: Taking the mass of the low-alloy high-strength hydrogen-resistant steel as 100%, the various components and their mass fractions are as follows:

3. A low alloy high strength hydrogen resistant steel according to claim 1 or 2, characterized in that: The aluminum is acid-soluble aluminum.

4. A method for preparing a low alloy high strength hydrogen resistant steel as claimed in any one of claims 1 to 3, characterized in that: (1) According to the various components and their mass fractions in the low-alloy high-strength hydrogen-resistant steel, batching, vacuum melting, casting and forging are carried out to obtain a forging billet; (2) heating the forging billet to 1150° C. to 1250° C., keeping the temperature constant for 1 h to 2 h, rolling it, and air cooling it to room temperature to obtain a billet after rolling treatment; (3) heating the rolled blank to 870° C. to 890° C., keeping the temperature constant for 0.8 h to 1.2 h, and then water cooling the blank to obtain a quenched steel; (4) The quenched steel is heated to 670°C to 690°C, kept at a constant temperature for 1.3h to 1.7h, and then air-cooled to obtain a low-alloy high-strength hydrogen-resistant steel.

5. The method for preparing a low alloy high strength hydrogen resistant steel according to claim 4, characterized in that: In step (2), the forging blank is heated to 1170°C to 1220°C.

6. The method for preparing a low alloy high strength hydrogen resistant steel according to claim 4, characterized in that: In step (3), the rolled blank is heated to 870°C to 880°C and kept at a constant temperature for 0.9h to 1.1h.

7. The method for preparing a low alloy high strength hydrogen resistant steel according to claim 4, characterized in that: In step (4), the quenched steel is heated to 670° C. to 680° C. and kept at a constant temperature for 1.4 h to 1.6 h.

8. The method for preparing a low alloy high strength hydrogen resistant steel according to claim 4, characterized in that: In step (2), the forging blank is heated to 1170° C. to 1220° C.; In step (3), the rolled blank is heated to 870° C. to 880° C. and kept at a constant temperature for 0.9 h to 1.1 h; In step (4), the quenched steel is heated to 670° C. to 680° C. and kept at a constant temperature for 1.4 h to 1.6 h.

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