Stainless steel suitable for high-pressure hydrogen environment

Abstract

The stainless steel material suitable for the high-pressure hydrogen environment comprises the following components in percentage by weight: 16 to 22 weight percent of chromium (Cr), 7 to 9 weight percent of nickel (Ni), 10 to 13 weight percent of manganese (Mn), 0.1 to 0.3 weight percent of niobium (Nb), 0.1 to 0.3 weight percent of vanadium (V), 0.4 to 0.5 weight percent of nitrogen (N) and the balance of necessary trace elements and inevitable impurities, and the nickel equivalent (Nieq) of the components of the stainless steel material is between 35 and 42. By greatly increasing the manganese content of the composition of the stainless steel material, the nitrogen content is synchronously increased to achieve solution strengthening and stabilize the austenite phase of the stainless steel material, in addition, the stainless steel material can generate an MX precipitated phase in the stretching process by adding niobium and vanadium at the same time, the hydrogen embrittlement resistance of the stainless steel material can be improved, and the stainless steel material can have high tensile strength.

Description

Technical Field

[0001] The present invention relates to a stainless steel material, in particular to a stainless steel material suitable for a high-pressure hydrogen environment. Background Art

[0002] Due to the demand for environmental protection and alternative energy, the research on using hydrogen as driving energy to replace petrochemical raw materials is being actively developed. For example, fuel cells using hydrogen as fuel. In the related development of hydrogen as kinetic energy, hydrogen filling stations for supplying hydrogen for fuel cells are also being actively developed.

[0003] The aforementioned hydrogen gas used to supply fuel cells is stored in stainless steel bottles at high pressure, so the stainless steel bottles used to store hydrogen are in a high-pressure hydrogen environment for a long time. However, when stainless steel is in a high-pressure hydrogen environment, it is easy for the mechanical properties of the stainless steel bottle to deteriorate and brittle fracture to occur due to hydrogen absorption or hydrogen permeation. Therefore, stainless steel used in a high-pressure hydrogen environment has higher requirements for hydrogen embrittlement resistance and strength, and related industries are constantly developing various stainless steel materials suitable for high-pressure hydrogen environments.

[0004] For example, Chinese Patent Publication No. CN113924378A (International Patent Application No. PCT / JP2020 / 021422) discloses an austenitic stainless steel with excellent hydrogen embrittlement resistance and high strength. It mainly utilizes the combination of stainless steel composition and processing conditions to match stainless steel materials with specific components with hot working conditions to control the final stainless steel to have an austenite grain size number based on ASTM E112 of 5.0 or more and less than 8.0, and in a cross section perpendicular to the length direction of the austenitic stainless steel, the dislocation cell organization rate is 50% or more and less than 80%, and the number density of precipitates with a long axis of 1.0 μm or more is 5.0 / 0.2 mm 2 The following is done to achieve the purpose of excellent hydrogen embrittlement resistance and high strength. Summary of the invention

[0005] The object of the present invention is to provide a stainless steel material suitable for high-pressure hydrogen environment.

[0006] The stainless steel material suitable for high-pressure hydrogen environment of the present invention comprises, by weight percentage, chromium (Cr): 16-22wt%, nickel (Ni): 7-9wt%, manganese (Mn): 10-13wt%, niobium (Nb): 0.1-0.3wt%, vanadium (V): 0.1-0.3wt%, nitrogen (N): 0.4-0.5wt%, and the remainder are necessary trace elements and unavoidable impurities, and the nickel equivalent (Nieq) of the components of the stainless steel material is between 35 and 42.

[0007] The stainless steel material suitable for high-pressure hydrogen environment of the present invention has a manganese (Mn) content of 12-13wt%.

[0008] The stainless steel material suitable for high-pressure hydrogen environment of the present invention has a chromium (Cr) content of 18-22 wt %.

[0009] The stainless steel material suitable for high-pressure hydrogen environment of the present invention further comprises carbon (C) in a content of 0.03-0.06 wt %.

[0010] The stainless steel material suitable for high-pressure hydrogen environment of the present invention further comprises silicon (Si) in a content of 0-1wt%.

[0011] The stainless steel material suitable for high-pressure hydrogen environment of the present invention contains no molybdenum (Mo).

[0012] The stainless steel material suitable for high-pressure hydrogen environment of the present invention has a tensile strength (TS) of not less than 650 MPa and an elongation (E1%) of not less than 40% in an atmospheric environment.

[0013] The stainless steel material suitable for high-pressure hydrogen environment of the present invention has a relative tensile strength (RTS) greater than 0.9, where RTS=(tensile strength in high-pressure hydrogen environment) / (tensile strength in atmospheric environment).

[0014] The stainless steel material suitable for high-pressure hydrogen environment of the present invention has a yield strength (YS) of not less than 340 MPa in the high-pressure hydrogen environment.

[0015] The beneficial effect of the present invention is that by significantly increasing the manganese content of the stainless steel material, the nitrogen content is simultaneously increased to achieve solid solution strengthening and stabilize the austenite phase of the stainless steel material. In addition, by simultaneously adding niobium and vanadium, the stainless steel material can produce MX precipitation phase during the stretching process, thereby improving the hydrogen embrittlement resistance of the stainless steel material and having a higher tensile strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings, in which:

[0017] Figure 1 is a stress-strain diagram illustrating the stress-strain measurement results of the specific example 3 of the present invention in an atmospheric environment and a high-pressure hydrogen environment;

[0018] Figure 2 is a stress-strain diagram illustrating the stress-strain measurements of 316L (cast) in atmospheric and high pressure hydrogen environments; and

[0019] Figure 3 is a stress-strain diagram illustrating the stress-strain measurement results of Comparative Example 2 in an atmospheric environment and a high-pressure hydrogen environment. DETAILED DESCRIPTION

[0020] Before the present invention is described in detail, it should be noted that similar components are represented by the same numbers in the following description. The relevant technical content, features and effects of the present invention will be clearly presented in the following detailed description of the embodiments with reference to the accompanying drawings.

[0021] An embodiment of the present invention provides a stainless steel material suitable for a high-pressure hydrogen environment.

[0022] The stainless steel is an austenite phase, and the components of the stainless steel are expressed in weight percentages as follows: chromium (Cr): 16-22wt%, nickel (Ni): 7-9wt%, manganese (Mn): 10-13wt%, niobium (Nb): 0.1-0.3wt%, vanadium (V): 0.1-0.3wt%, nitrogen (N): 0.4-0.5wt%, molybdenum (Mo): 0-3wt%, and the remainder are necessary trace elements and unavoidable impurities, and the nickel equivalent (Ni) of the components of the stainless steel is 16-22wt%. eq ) is between 35 and 42. In the embodiment of the present invention, the remaining necessary trace elements refer to carbon (C): ≤ 0.06 wt % and silicon (Si): 0 to 1 wt %.

[0023] Wherein, the calculation formula of the nickel equivalent (Nieq) is as follows:

[0024] [Ni+0.72Cr+0.88Mo+1.11Mn-0.27Si+0.53Cu+12.93C+7.55N]

[0025] In some embodiments, the nickel equivalent (Ni eq ) is between 40 and 42.

[0026] Preferably, the carbon (C) content of the stainless steel component is between 0.03 and 0.06 wt %.

[0027] Manganese (Mn), nitrogen (N) and nickel (Ni) are all elements that can stabilize the austenite phase and improve hydrogen embrittlement resistance. However, in general existing technologies, too much nickel (Ni) will increase costs and increase the recrystallization temperature; too much manganese content (for example, greater than 13wt%) will promote the formation of ε phase with high sensitivity to hydrogen embrittlement, and too high nitrogen content (for example, greater than 0.5wt%) will easily produce internal defects such as pores during smelting, affecting manufacturability; if excessive manganese and nitrogen are added at the same time, stacking fault energy of the material will be generated, and local dislocation multiplication will easily occur under deformation in a high-pressure hydrogen environment, reducing the ductility of the material and causing hydrogen embrittlement. Therefore, the present invention controls the content of manganese (Mn) and nitrogen (N) added simultaneously, so that the content of manganese is not higher than 13wt% and the content of nitrogen is not higher than 0.5wt%, thereby avoiding the aforementioned problems, and stabilizing the austenite phase at a lower cost, using manganese (Mn) to improve the solubility of nitrogen (N), reducing the addition of high-valent nickel, and maintaining a higher nickel equivalent; furthermore, since nitrogen (N) atoms will be plugged in the gaps of the face-centered cubic structure, the alloy solid solution strengthening effect can be greatly improved, thereby improving the strength of the alloy. Preferably, the manganese (Mn) content of the components of the stainless steel material is between 12 and 13wt%, and the nitrogen (N) content is between 0.4 and 0.5wt%.

[0028] Preferably, the stainless steel material has a chromium (Cr) content of 18-22wt%, a silicon (Si) content of 0.7-0.8wt%, a niobium (Nb) content of 0.2-0.3wt%, and a vanadium (V) content of 0.1-0.2wt%.

[0029] The present invention increases the nitrogen (N) content in the composition by increasing the manganese (Mn) content of the stainless steel composition, thereby simultaneously increasing the solid solubility rate of nitrogen (N), and simultaneously adding precipitation strengthening elements such as niobium and vanadium, so that the stainless steel can produce MX precipitation phase during the stretching process, and at the same time control the stainless steel composition to have a higher nickel equivalent (Ni eq ) (between 35 and 42), which can stabilize the austenite phase of the stainless steel and improve the hydrogen embrittlement resistance and casting mechanical strength.

[0030] In addition, the composition of the stainless steel material of the present invention utilizes increased manganese (Mn) and nitrogen (N) contents, thereby reducing the contents of relatively expensive metals (nickel, molybdenum) in the composition, thereby also reducing costs.

[0031] In some embodiments, the stainless steel material of the present invention does not contain molybdenum (Mo), and can also achieve the characteristics of hydrogen embrittlement resistance and high strength with lower cost.

[0032] Furthermore, the stainless steel material of the present invention is suitable for castings and has excellent casting mechanical properties.

[0033] In some embodiments, the stainless steel material has a casting mechanical property of a yield strength (YS) of not less than 340 MPa.

[0034] Preferably, the tensile strength (TS) of the stainless steel material of the present invention in the atmospheric environment is not less than 650MPa, the yield strength (YS) is not less than 340MPa, and the elongation (El%) is not less than 40%. The tensile strength (TS) of the stainless steel material in the high-pressure hydrogen environment is not less than 620MPa, the yield strength (YS) is not less than 340MPa, and the elongation (El%) is not less than 35%, indicating that the stainless steel material of the present invention can resist hydrogen embrittlement in the high-pressure hydrogen environment and maintain good mechanical properties at the same time.

[0035] In some embodiments, the relative tensile strength (RTS) of the stainless steel is greater than 0.9, which can show excellent hydrogen embrittlement resistance. RTS = (tensile strength in high-pressure hydrogen environment) / (tensile strength in atmospheric environment), and high-pressure hydrogen environment refers to a hydrogen atmosphere and a pressure of 700 bar.

[0036] Next, the manufacturing method of the embodiment of the present invention is described as follows.

[0037] First, an iron-based alloy is placed in a melting crucible under an atmospheric environment for melting, and when molten iron appears, other materials required for preparing the stainless steel material (such as the components described in the above-mentioned embodiment) are added in sequence. The order of adding is to add the material with a high melting point first, and then the material with a low melting point, so that all the materials are completely melted to obtain a stainless steel melt with a specific ratio.

[0038] Next, the stainless steel melt is poured into a mold within a melting temperature range (1580-1680 degrees Celsius), and the stainless steel casting is obtained after cooling.

[0039] Next, the stainless steel casting test pieces of Specific Examples 1 to 3 and Comparative Examples 1 to 2 were prepared by the aforementioned preparation method, and the stainless steel casting test pieces prepared in the specific examples and comparative examples and a commercially available stainless steel material (316L (casting)) were subjected to mechanical properties (yield strength (TS), tensile strength (YS), and elongation (EL%)) and hydrogen embrittlement resistance measurements in an atmospheric environment and a high-pressure hydrogen environment to illustrate the relevant properties of the stainless steel material of the present invention.

[0040] The high-pressure hydrogen environment is a hydrogen atmosphere with a pressure of 700 bar.

[0041] Yield strength (TS), tensile strength (YS), and elongation (EL%) were measured using an Instron tensile tester by subjecting the casting specimens to a high pressure hydrogen environment and an atmospheric environment at room temperature (25°C) at a tensile rate of 8.33x10 -6 / second, and the specifications of the casting specimens are made according to ASTM E8 / E8M specifications. The overall testing process is carried out in accordance with ASTM G129.

[0042] The compositions and related test results of the specific examples 1 to 3, comparative examples 1 to 2, and commercially available stainless steel materials are summarized in Table 1 and Table 2, respectively.

[0043] Table 1

[0044]

[0045] Table 2

[0046]

[0047] *RTS: (Tensile strength in high-pressure hydrogen environment) / (Tensile strength in atmospheric environment). High-pressure hydrogen environment means that the tensile test is performed immediately after the high-pressure hydrogen environment reaches 700 bar.

[0048] As can be seen from Tables 1 and 2, the RTS values ​​of the specific examples 1 to 3 are all >0.9, indicating that the tensile strength of the stainless steel material in the high-pressure hydrogen environment and the atmospheric environment can be almost maintained unchanged, showing excellent hydrogen embrittlement resistance. In particular, when the manganese (Mn) content is increased to 12wt%, the nitrogen (N) content is increased to more than 0.4wt%, and precipitation strengthening elements (niobium (Nb), vanadium (V)) are added, and the nickel equivalent (Nieq) of the composition is controlled to be not less than 40, the tensile strength of the stainless steel (atmospheric environment) can be further increased to more than 620MPa, and the RTS value is increased to 0.95.

[0049] In addition, please refer to Figure 1 , 2 , Figure 1 , 2The yield strength (YS) test results of Specific Example 3 and 316L (cast) in atmospheric environment and high-pressure hydrogen environment are shown respectively. It can be seen from the results that the yield strength (YS) of Specific Example 3 and 316L (cast) in high-pressure hydrogen environment are 342MPa and 170MPa respectively, indicating that Specific Example 3 can also have excellent stability in high-pressure hydrogen environment. And from Table 2, the results of tensile strength (TS) under different environmental conditions show that the casting mechanical strength of the stainless steel material of Specific Example 3 described in this case is significantly better than 316L (cast) and 316L (forged) in both atmospheric environment and high-pressure hydrogen environment, indicating that the stainless steel material in this case can indeed have good hydrogen embrittlement resistance and mechanical properties. In addition, Figure 3 It can be seen that the manganese content (6.72wt%) and nitrogen content (0.27wt%) of the comparative example 2 are lower than those of the specific example, resulting in the yield strength (YS) of the comparative example 2 in the atmospheric environment and the high-pressure hydrogen environment being 248MPa and 247MPa respectively, which are lower than those of the specific example. However, the yield strength (YS) of the comparative example 2 in the atmospheric environment and the high-pressure hydrogen environment is higher than that of 316L (cast), which also shows that increasing the manganese content of the stainless steel composition and then simultaneously increasing the nitrogen content can achieve solid solution strengthening and stabilize the austenite phase of the stainless steel, and the addition of niobium and vanadium at the same time can cause the stainless steel to produce MX precipitation phase during the stretching process to improve its hydrogen embrittlement resistance.

[0050] Refer to Table 2 again. HRX19 (forged) in Table 2 is the stainless steel used for high-pressure hydrogen. Although HRX19 (forged) has excellent strength and hydrogen embrittlement resistance, HRX19 is obtained by forging, and the process is more complicated. However, due to the high content of expensive metals (nickel and molybdenum) in the composition of HRX19 (forged), the cost is higher. In this case, the composition design reduces the amount of expensive metals such as nickel and molybdenum. In addition to effectively reducing costs, the stainless steel obtained by casting has excellent hydrogen embrittlement resistance and casting mechanical properties, which can further simplify the process method.

[0051] In summary, the stainless steel material suitable for high-pressure hydrogen environment of the present invention achieves solid solution strengthening and stabilizes the austenite phase of the stainless steel material by significantly increasing the manganese content of the stainless steel material, and then simultaneously increasing the nitrogen content, and simultaneously adding niobium and vanadium so that the stainless steel material can produce MX precipitation phase during the stretching process, thereby improving the hydrogen embrittlement resistance of the stainless steel material and having a higher tensile strength, so the purpose of the present invention can be achieved.

[0052] However, what is described above is only an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the claims and the contents of the patent specification of the present invention are still within the scope of the patent of the present invention.

Claims

1. A stainless steel material suitable for high-pressure hydrogen environment, characterized in that: The components of the stainless steel material include, by weight percentage, chromium (Cr): 16-22wt%, nickel (Ni): 7-9wt%, manganese (Mn): 10-13wt%, niobium (Nb): 0.1-0.3wt%, vanadium (V): 0.1-0.3wt%, nitrogen (N): 0.4-0.5wt%, and the remainder are necessary trace elements and unavoidable impurities, and the nickel equivalent (Ni) of the components of the stainless steel material is 1.1-1.3wt%. eq ) is between 35 and 42.

2. The stainless steel material suitable for high-pressure hydrogen environment according to claim 1, characterized in that: The manganese (Mn) content of the stainless steel component is between 12 and 13 wt%.

3. The stainless steel material suitable for high-pressure hydrogen environment according to claim 1, characterized in that: The chromium (Cr) content of the stainless steel material is between 18 and 22 wt %.

4. The stainless steel material suitable for high-pressure hydrogen environment according to claim 1, characterized in that: The stainless steel material further comprises carbon (C) in an amount ranging from 0.03 to 0.06 wt %.

5. The stainless steel material suitable for high-pressure hydrogen environment according to claim 1, characterized in that: The stainless steel material further comprises silicon (Si) in an amount ranging from 0 to 1 wt %.

6. The stainless steel material suitable for high-pressure hydrogen environment according to claim 1, characterized in that: The stainless steel material does not contain molybdenum (Mo).

7. The stainless steel material suitable for high-pressure hydrogen environment according to claim 1, characterized in that: The tensile strength (TS) of the stainless steel material in an atmospheric environment is not less than 650 MPa, and the elongation (El%) is not less than 40%.

8. The stainless steel material suitable for high-pressure hydrogen environment according to claim 7, characterized in that: The relative tensile strength (RTS) of the stainless steel material is greater than 0.9, RTS=(tensile strength in a high-pressure hydrogen environment) / (tensile strength in an atmospheric environment).

9. The stainless steel material suitable for high-pressure hydrogen environment according to claim 1, characterized in that: The yield strength (YS) of the stainless steel material in a high-pressure hydrogen environment is not less than 340 MPa.

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