Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L9/00—Rigid pipes
  • F16L9/02—Rigid pipes of metal
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/10—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/002—Bainite
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/005—Ferrite

Definitions

• the present invention relates to a steel pipe for high-pressure hydrogen piping and a high-pressure hydrogen pipe using the same, and particularly relates to a steel pipe for high-pressure hydrogen piping suitable as a pipe for high-pressure hydrogen gas used in a fuel cell vehicle and a high-pressure hydrogen pipe using the same.
• FCV fuel cell vehicle
• PEFC solid polymer fuel cell
• Electric vehicles can be mentioned as transportation equipment that plays a similar role, but since the requirements for cruising range and vehicle size cannot be fully satisfied, it is expected that the technology equipped with fuel cells will be applied to commercial vehicles in particular. ..
• materials such as pipes, joints, and valves used for hydrogen stations are under high pressure hydrogen gas environment according to the general high pressure gas safety regulation related example standards (High Pressure Gas Safety Association) in consideration of the influence of hydrogen on the materials.
• SUS316 / SUS316L JIS G 3459 stainless steel for piping
• the drawing value in a tensile test or a mill sheet is 75% or more
• the Ni equivalent is -45 ° C or more at a normal temperature. If it is less than -10 ° C, it is 28.5 or more, if the normal temperature is -10 ° C or more and less than 20 ° C, it is 27.4 or more, and the normal temperature is 20 ° C or more.
• the wall thickness should be kept to a minimum for economic reasons, and it is expected that high-strength materials that can be used in a high-pressure hydrogen gas environment will be applied in the future.
• a high pressure fuel injection pipe for a diesel engine that injects high pressure fuel, and Patent Document 1 and Patent Document 2 shown below are disclosed.
• Patent Document 1 discloses a method for manufacturing a steel pipe used for fuel injection of a diesel engine in which the inner surface of a hot-rolled seamless steel pipe material is ground and polished by shot blasting and then cold drawn. There is. According to this manufacturing method, the depth of scratches (unevenness, dents, fine cracks, etc.) on the inner surface of the steel pipe can be reduced to 0.10 mm or less, so that the strength of the steel pipe used for fuel injection can be increased. Further, Patent Document 2 discloses a steel pipe for a fuel injection pipe having a maximum diameter of 20 ⁇ m or less and a tensile strength of 500 MPa or more, which is present at a depth of at least 20 ⁇ m from the inner surface of the steel pipe. ..
• the steel pipe for high-pressure hydrogen piping according to the present invention has a chemical composition of mass%.
• C 0.17 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.30 to 2.00%, P: 0.035% or less, S: 0.035% or less, Cu: 0 to 0.50%, Mo: 0-1.0%, V: 0 to 0.15%, Remaining: Fe and impurities
• the metal structure at the center of the wall thickness of the steel pipe is a mixed structure of bainite and ferrite, the tensile strength in a hydrogen atmosphere is 500 to 900 MPa, the hardness at the center of the wall thickness is 160 to 280 HV1, and the inner diameter d is 3 mm or more.
• the outer diameter D is 12 mm or less, the wall thickness is 1 mm or more, the ratio of the outer diameter to the inner diameter satisfies the following formula (1), and the maximum value of the defect depth existing on the inner surface of the steel pipe is 200 ⁇ m or less. It is characterized by.
• the chemical composition of the steel pipe is mass%.
• the high-pressure hydrogen pipe according to the present invention is characterized in that a steel pipe for high-pressure hydrogen pipe having any of the above chemical compositions is used as a material.
• the steel pipe for high-pressure hydrogen piping of the present invention has excellent fatigue characteristics, and it is possible to obtain a steel pipe for high-pressure hydrogen piping that has both safety and economy. Therefore, the steel pipe for high-pressure hydrogen piping according to the present invention can be suitably used as a high-pressure hydrogen pipe particularly used in a fuel cell vehicle.
• C 0.17 to 0.27%
• C is an element effective for increasing the strength of steel. In order to secure the desired tensile strength, it is necessary to set the C content to 0.17% or more. However, if the C content exceeds 0.27%, the processability deteriorates, so the C content is preferably 0.17 to 0.27%.
• Si 0.05 to 0.40% Si is preferably contained for deoxidation of steel, and it is necessary to have 0.05% or more in order to improve the strength, but when the Si content exceeds 0.40%, toughness is required. May lead to a decrease in.
• Mn 0.30 to 2.0%
• Mn is an element that not only has a deoxidizing effect, but is also effective in enhancing the hardenability of steel and improving its strength and toughness. However, if the content is less than 0.30%, sufficient strength cannot be obtained, while if it exceeds 2.0%, MnS is coarsened and stretched during hot rolling, and the toughness is rather lowered. .. Therefore, the Mn content is set to 0.30 to 2.0%.
• P 0.035% or less
• P is an element that is inevitably present in steel as an impurity. If the content exceeds 0.035%, not only the hot workability is lowered, but also the toughness is significantly lowered due to the segregation of grain boundaries. Therefore, the P content is 0.035% or less.
• S 0.035% or less S is an element that is inevitably present in steel as an impurity like P. If the content exceeds 0.035%, segregation occurs at the grain boundaries and sulfide-based inclusions are generated, which tends to cause a decrease in fatigue strength. Therefore, the S content is 0.035% or less.
• Cu 0 to 0.50%
• Cu is an element having the effect of improving strength and toughness by enhancing the hardenability of steel.
• the Cu content is set to 0.50% or less.
• Mo 0-1.0% Mo is an element that contributes to ensuring high strength because it improves hardenability and enhances tempering and softening resistance. However, even if the Mo content exceeds 1.0%, the effect is saturated and the alloy cost is increased. Therefore, the Mo content when contained is 1.0% or less.
• V 0 to 0.15%
• V is an element that precipitates as fine carbides (VC) during tempering, increases tempering softening resistance, enables high-temperature tempering, and contributes to high strength and toughness of steel.
• the V content exceeds 0.15%, the toughness is rather lowered, so the V content when contained is set to 0.15% or less.
• Ti 0.005 to 0.015%
• Ti is an element that contributes to the prevention of coarsening of crystal grains by finely precipitating it in the form of TiN or the like, but in order to obtain its effect, the Ti content must be 0.005% or more. be.
• the Ti content exceeds 0.015%, the grain refinement effect of the crystal grains tends to be saturated, and in some cases, large Ti—Al composite inclusions may be generated. Therefore, the Ti content is set to 0.005 to 0.015%.
• Nb 0.015 to 0.045%
• Nb is an essential element for obtaining a desired fine-grained structure because it is finely dispersed in steel as a carbide or carbonitride and has the effect of strongly pinning the crystal grain boundary, and is also a carbide of Nb.
• the fine dispersion of carbides improves the strength and toughness of the steel.
• the Nb content is preferably 0.015 to 0.045%.
• Cr 0-1.0% Cr is an element that has the effect of improving the hardenability and wear resistance of steel, but if the content exceeds 1.0%, the toughness and cold workability deteriorate, so the Cr content when contained. Is 1.0% or less.
• Ni 0 to 0.50% Like Cu, Ni is an element that has the effect of improving strength and toughness by increasing the hardenability of steel. However, even if the Ni content exceeds 0.50%, the effect is saturated and the alloy cost is increased. Therefore, the Ni content when contained is set to 0.50% or less.
• Al 0.005 to 0.060%
• Al is an element that is effective in deoxidizing steel and has an effect of enhancing the toughness and workability of steel. In order to obtain these effects, it is necessary to contain 0.005% or more of Al, but on the other hand, if the Al content exceeds 0.060%, large Ti-Al composite inclusions may be formed. The Al content is 0.005 to 0.060%.
• O 0.0040% or less O forms a coarse oxide, which tends to cause a decrease in the internal pressure limit. From this point of view, the O content should be 0.0040% or less.
• Ca 0.0010% or less
• Ca has an action of aggregating silicate-based inclusions, and when the Ca content exceeds 0.0010%, the critical internal pressure decreases due to the formation of coarse C-based inclusions. Therefore, the Ca content is 0.0010% or less.
• N 0.0020-0.0080%
• N is an element that is inevitably present in steel as an impurity.
• it is necessary to leave 0.0020% or more of N for the purpose of preventing crystal grain coarsening due to the pinning effect of TiN.
• the N content is set to 0.0020 to 0.0080%.
• the metal structure of the steel pipe for high-pressure hydrogen piping according to the present invention preferably has a mixed structure of bainite and ferrite. If martensite is present in the structure, a tensile strength higher than 1000 MPa can be secured, but the hydrogen environment compatibility may not be sufficient. Further, as an example of the improvement method, the tempering treatment at a high temperature is indispensable, but the heat treatment leads to an increase in cost.
• the steel pipe for high-pressure hydrogen piping which does not require the above-mentioned treatment, satisfies the desired mechanical properties in a non-tamed metal structure form, and achieves both safety and economy, and high-pressure hydrogen using the same. We found that we could realize plumbing.
• the tensile strength of the steel pipe for high-pressure hydrogen piping according to the present invention in a hydrogen atmosphere is preferably 500 to 900 MPa.
• the hardness at the central portion of the wall thickness is 160 to 280 HV1. If the hardness is less than 160 HV1, sufficient strength cannot be obtained in a hydrogen atmosphere. On the other hand, when the hardness exceeds 280 HV1, the influence of hydrogen on the material properties tends to be more remarkable.
• “HV1” means a "hardness symbol” when a Vickers hardness test is carried out with a test force of 9.8 N (1 kgf) (see JIS Z 2244: 2009). When the hardness at the central portion of the wall thickness is 160 HV1 or more, a tensile strength of 500 MPa or more can be obtained.
• the maximum value of the defect depth existing on the inner surface of the steel pipe is 200 ⁇ m or less.
• the dimensions of the steel pipe for high-pressure hydrogen piping and the ratio of outer diameter to inner diameter, etc. according to the present invention shall be appropriately set according to the technology to be applied, the purpose of use, and the like.
• a steel pipe for high-pressure hydrogen piping for example, it is desirable that the inner diameter d is 3 mm or more, the outer diameter D is 12 mm or less, the wall thickness is 1 mm or more, and the ratio of the outer diameter to the inner diameter satisfies the above equation (1).
• D is the outer diameter (mm) of the steel pipe for high-pressure hydrogen piping
• d is the inner diameter (mm).
• the upper limit of D / d is not particularly set, but if the value is excessive, bending becomes difficult, so that it is preferably 3.0 or less, and more preferably 2.8 or less.
• a steel material (billet) having the chemical components shown in Table 2 was cut to a predetermined length and processed into a test piece to prepare a test material for a fatigue life test.
• a minute defect with a depth of 100 ⁇ m 125 ⁇ m was introduced into the test material evaluation unit as a defect assumed to exist in the piping material.
• the metal structure at this time was a mixed structure of bainite and ferrite, and the tensile strength was 703 MPa in the atmosphere, 698 MPa in hydrogen, and the hardness at the center of the billet wall thickness was 223 HV1 (Table 3). From the above results, the tensile strength in the atmosphere can be regarded as equivalent to that in hydrogen.
• the frequency in the atmosphere is 10 Hz
• the frequency in hydrogen gas is 10 Hz. It was set to 1 Hz.
• the fatigue life test in hydrogen gas was carried out in a state where 95 MPa of hydrogen gas was sealed in the pressure vessel of the testing machine.
• the fatigue limit is relative to the atmosphere. It has been confirmed that it does not decrease. From these facts, it was found that the design can be performed in hydrogen as well as in the atmosphere, and a high-pressure hydrogen pipe using the steel type can be obtained.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
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• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Rigid Pipes And Flexible Pipes (AREA)
• Heat Treatment Of Articles (AREA)

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• 2021
  • 2021-11-01 EP EP21886433.8A patent/EP4239096A4/en active Pending
  • 2021-11-01 US US18/250,982 patent/US20250075831A1/en active Pending
  • 2021-11-01 CN CN202180072979.1A patent/CN116438323B/zh active Active
  • 2021-11-01 JP JP2022559452A patent/JP7712950B2/ja active Active
  • 2021-11-01 WO PCT/JP2021/040268 patent/WO2022092316A1/ja not_active Ceased
  • 2021-11-01 KR KR1020237015727A patent/KR20230084555A/ko not_active Ceased

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