Classifications

• • 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
  • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
• • 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
  • C21D7/00—Modifying the physical properties of iron or steel by deformation
  • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
  • C21D7/10—Modifying the physical properties of iron or steel by deformation by cold working of the whole cross-section, e.g. of concrete reinforcing bars
• • 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
  • C21D9/14—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes wear-resistant or pressure-resistant 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
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • 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
  • C22C38/12—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
• • 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
  • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium 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
  • C22C38/26—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
  • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with 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
  • C22C38/18—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
  • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
  • C22C38/40—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
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
  • C23C2/06—Zinc or cadmium or alloys based thereon
• • 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
  • C21D2211/004—Dispersions; Precipitations
• • 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
• • 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
  • C21D2211/009—Pearlite
• • 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

Definitions

• the invention relates to a hydrogen-carrying pipe component according to the features of claim 1.
• Hydrogen as an energy carrier for fuel cell vehicles is emission-free, but has a low volumetric mass density at room temperature. Compressing hydrogen increases this low volumetric energy density, which significantly simplifies the storage, transport, and use of hydrogen.
• Suitable high-pressure piping systems are required to transport compressed hydrogen from a tank to a fuel cell stack or to an internal combustion engine. In trucks and cars, these systems are typically operated at a hydrogen pressure of 35 MPa or 70 MPa, respectively.
• the requirements for high-pressure piping systems in hydrogen-powered vehicles, as well as in peripheral systems, are...
• the requirements for comparable applications are high. They must withstand the high hydrogen pressure safely and reliably. Furthermore, they must be protected against corrosion from hydrogen and against corrosion from other media.
• Stainless steels are preferably used for hydrogen-conducting components. Stainless steels have a minimum chromium content of 16% and nickel content of 10%. Due to the high chromium and nickel content, they are relatively expensive. Furthermore, the material has low strength, so components designed for higher pressure resistance require greater wall thicknesses. This, in turn, increases the weight and thus, in mobile applications, the energy consumption. The increased material usage also leads to higher costs.
• the invention is based on the objective of optimizing the alloy composition of low-alloy carbon steels specifically with regard to their use in hydrogen-carrying pipe components and with regard to material costs.
• a hydrogen-carrying, cold-drawn pipe component according to the features of claim 1 solves this problem.
• the dependent claims relate to advantageous embodiments of the invention.
• the invention relates to a hydrogen-carrying, cold-drawn pipe component made of a steel alloy.
• Hydrogen-carrying pipe components are, in particular, high-pressure lines or hydrogen tanks for storing hydrogen in stationary or mobile applications.
• the pipe component according to the invention is, in particular, a piping application of a hydrogen pressure tank system of a motor vehicle.
• the cold-drawn pipe component used for this purpose consists of a steel alloy which, in addition to iron and melting-related impurities, contains the following elements in mass percent as residue: C: 0.07 - 0.22 Yes: 0.10 - 0.55 Mn: 0.30 - 1.60 P: ⁇ 0.025 S: ⁇ 0.015 Ti: 0.010 - 0.030 V: 0.003 - 0.30 N: 0.008 - 0.025 Al: 0.010 - 0.025 Approx ⁇ 0.10.
• the alloy contains the following elements in mass %: Note: ⁇ 0.10 Mon: ⁇ 0.50 Cr: ⁇ 0.50 Ni: ⁇ 1.0 Cu: ⁇ 0.20
• Carbide-forming elements such as vanadium are added in a targeted manner.
• the addition of these elements improves hydrogen embrittlement (HE) resistance. Due to precipitation hardening, the addition of these elements leads to increased material strength.
• Nanoscale vanadium carbonitrides (V(C,N)) play a crucial role in this process. They act as hydrogen traps, effectively trapping hydrogen and thus reducing the hydrogen diffusion rate. They also refine the existing austenite grain size, significantly improving HE resistance.
• Coarse vanadium carbonitrides lose their ability to act as strong hydrogen traps and instead act as crack initiation sites, thus reducing their HE resistance. Therefore, only vanadium carbonitride nanoprecipitates with sizes below 60 nm represent effective hydrogen traps.
• Thermokinetic calculations have shown that for the alloy composition according to the invention, the number of vanadium carbonitride precipitates
• the average size of the vanadium carbonitride precipitates is 10 nm in diameter. The equivalent diameter is determined.
• the number of nanoscale vanadium carbonitride precipitates increases.
• the hydrogen diffusion coefficient decreases by an order of magnitude.
• the maximum value of 0.3 wt% vanadium should not be exceeded, as otherwise the HE resistance decreases again with increasing vanadium concentrations.
• Titanium and titanium nitrides have a grain-refining effect by inhibiting recrystallization and austenite grain growth. Furthermore, TiN precipitates serve as nucleation sites for vanadium carbonitrides, thereby increasing their number and thus the number of hydrogen traps.
• Vanadium leads to the formation of vanadium carbonate ditrides V(C,N), which have a grain-refining effect. This grain-refining effect increases the strength and toughness of the material.
• the pipe component is manufactured, in particular, without weld seams, preferably from a hot-rolled and once- or twice-normalized microstructure.
• the pipe component is heated above the Ac3 temperature, held at the target temperature, and slowly cooled to produce a fine-grained microstructure. This achieves a homogeneous distribution of mechanical properties, which improves formability during cold drawing.
• the pipe component according to the invention consists of a ferrite-pearlite steel with high HE resistance due to the addition of vanadium.
• the pipe component according to the invention is particularly easy to weld and has a carbon equivalent value (CEV) of less than or equal to 0.42%.
• CEV carbon equivalent value
• the carbon equivalent is a measure for assessing the weldability of unalloyed and low-alloy steels.
• the carbon equivalent combines the carbon content and the weighted proportions of elements that influence the weldability of the steel in a similar way to what would be expected from carbon alone into a single numerical value. Values below A martensite content of 0.45% indicates good weldability. Higher values require preheating. Above 0.65%, the workpiece is only weldable with increased effort due to martensite formation, which can lead to cold cracking or hardening cracks.
• Copper, nickel, chromium and molybdenum are optional alloying components.
• the microstructure consists of more than 95% ferrite and pearlite.
• the remaining components of the microstructure are martensite, bainite, and retained austenite.
• the microstructure is exceptionally fine-grained, corresponding to a grain size of size class 9 or finer according to ASTM 112-13 (2021).
• the grain size class is at least 10.
• the steel alloy is formed into a cold-drawn tube component, the tube component having a tensile strength of at least 340 MPa.
• the tensile strength is between 400 MPa and 850 MPa.
• the yield strength Rp0.2 is preferably at least 220 MPa.
• the elongation at break A is at least 25%.
• the steel alloy preferably contains the following elements in mass percent, in addition to iron and impurities resulting from the melting process: C: 0.09 - 0.22 Yes: 0.10 - 0.55 Mn: 0.70 - 0.70 P: 0.005 - 0.025 S: 0.002 - 0.015 Ti: 0.010 - 0.030 V: 0.030 - 0.30 N: 0.008 - 0.025 Al: 0.010 - 0.025 Ca: 0.0005 - 0.050 and optional Note: ⁇ 0.050 Mon: ⁇ 0.30 Cr: ⁇ 0.350
• the steel alloy preferably contains, in addition to iron and smelting-related impurities, the following elements in mass percent: C: 0.09 - 0.22 Yes: 0.10 - 0.55 Mn: 0.70 - 1.60 P: 0.005 - 0.025 S: 0.002 - 0.015 Ti: 0.010 - 0.030 V: 0.050 - 0.30 N: 0.008 - 0.025 Al: 0.015 - 0.025 Ca: 0.0005 - 0.050 and optional Note: ⁇ 0.050 Mon: ⁇ 0.30 Cr: ⁇ 0.50 Ni: ⁇ 0.50 Cu: ⁇ 0.20.
• the steel alloy consists, in addition to iron and impurities resulting from the melting process, of the following elements in mass percent: C: 0.09 - 0.19 Yes: 0.20 - 0.55 Mn: 0.90 - 1.50 P: 0.005 - 0.025 S: 0.003 - 0.015 Ti: 0.010 - 0.030 V: 0.110 - 0.30 N: 0.008 - 0.025 Al: 0.015 - 0.025 Ca: 0.0010 - 0.010 and optional Note: ⁇ 0.050 Mon: ⁇ 0.30 Cr: ⁇ 0.50 Ni: ⁇ 0.50 Cu: ⁇ 0.180, and in particular from the following composition: C: 0.07 - 0.17 Yes: 0.10 - 0.55 Mn: 0.70 - 1.60 P: 0.005 - 0.025 S: 0.002 - 0.015 Ti: 0.010 - 0.030 V: 0.003 - 0.30 N: 0.008 - 0.025 Al: 0.010 -
• the hydrogen-carrying pipe component can be coated on one outer surface, preferably only on one side.
• This coating can be a zinc or zinc alloy coating applied by immersion.
• an organic coating such as a powder coating.
• Suitable coatings can be applied galvanically or by electrophoretic deposition processes, in particular by cathodic dip coating.
• the coating is, in particular, multi-layered and serves to protect the exterior of the hydrogen-carrying, cold-drawn pipe component from corrosion, especially in its function as a pipeline in a hydrogen pressure tank system, namely as a line within a system or as the tank itself.
• the burst pressure test according to ISO 11114-4:2017 is a test procedure for assessing the susceptibility of metals to hydrogen embrittlement.
• a small, flat disc of the material to be tested is placed between two stainless steel flanges. Pressure is increased from one side of the disc at varying rates of pressure increase until fracture occurs. The burst pressures are then determined.
• the test is performed using both helium and hydrogen gas. The resulting burst pressures are compared. The ratio between these burst pressures is an indicator of hydrogen compatibility. The lower the ratio of the helium burst pressure to the hydrogen burst pressure, the less susceptible the steel is to hydrogen embrittlement.
• the helium burst pressure should be equal to or only slightly higher than the hydrogen burst pressure.
• the helium burst pressure/hydrogen burst pressure factor should be a maximum of 2, preferably a maximum of 1.75, particularly preferably a maximum of 1.50, and especially a maximum of 1.25.
• Steels with a coefficient of performance (COP) of less than or equal to 2.0 are considered hydrogen-compatible. Values close to 1.0 are desirable for high-pressure hydrogen pipeline systems.
• the steel alloy according to the invention achieves COPs of up to 1.2, and in particular values of up to 1.16. It is therefore a steel alloy suitable for the production of cold-drawn, hydrogen-carrying pipe components, and especially for use in high-pressure hydrogen pipeline systems.
• the hydrogen-carrying, cold-drawn pipe component according to the invention also meets high requirements for cyclic pressure loading.
• a cyclic pressure test with hydrogen gas is performed for up to 50,000 pressure cycles at a defined test temperature.
• the cyclic pressure test is particularly suitable for assessing the effects of cyclic aging under the influence of pressurized hydrogen. Maximum hydrogen-induced damage occurs at a temperature of -60 °C.
• One pressure cycle lasts 20 to 30 seconds, during which the pressure is increased from 0 to 87.5 MPa and then reduced back to 0 MPa.
• a burst pressure test is performed, stipulating that an unstressed pipe component, i.e., a pipe component without cyclic pressure testing, is used as a reference pipe and compared to a pipe sample after the cyclic pressure test.
• the ratio between the determined burst pressures is an indicator of hydrogen compatibility after dynamic loading, wherein the determined burst pressure of the pipe sample is at most 40%, preferably at most 30%, particularly preferably at most 20%, and especially at most 10% lower compared to the reference pipe.
• the pipe component according to the invention is characterized in that the determined burst pressure of the pipe sample is lower compared to the reference pipe.
• Hydrogen is stored at a pressure level of 70 MPa. At a working pressure of 70 MPa and a safety factor of 1.25, this results in 87.5 MPa, corresponding to the test pressure in the cyclic pressure test.
• the tests have thus confirmed that a burst pressure of at least 80 MPa was determined.
• the cyclic pressure test was performed on a pipe according to the features of claim 1 with dimensions of 6.35 mm diameter and The test was carried out with a wall thickness of 1.675 mm. The test was performed using hydrogen gas with a purity of at least 99.999%. Regarding the test conditions for the cyclic pressure test, it should be added that, under the same test conditions, the burst pressure of the stainless steel pipe decreased by 1.9% compared to the original pipe.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Crystallography & Structural Chemistry (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Manufacturing & Machinery (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatment Of Articles (AREA)

Priority Applications (4)

Applications Claiming Priority (1)

Publications (1)

Family

ID=91376610

Family Applications (1)

Country Status (4)

Citations (3)

• 2024
  • 2024-06-04 EP EP24179799.2A patent/EP4660328A1/fr active Pending
• 2025
  • 2025-06-03 CA CA3275723A patent/CA3275723A1/en active Pending
  • 2025-06-03 US US19/227,104 patent/US20250369081A1/en active Pending
  • 2025-06-04 CN CN202510733133.8A patent/CN121065574A/zh active Pending

Patent Citations (3)

Also Published As

Similar Documents

Legal Events