ステンレス鋼および高強度鋼の高圧水素ガス中の疲労特性と劣化機構

概要

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In order to ensure the safety of pipe and vessel used in high pressure gaseous hydrogen for fuel cell vehicles and hydrogen stations, material properties should be clarified and the mechanical structure needs to be designed. In this study, a cyclic pressurization fatigue test was conducted using tubular specimens in the high pressure gaseous hydrogen environment. Stable austenitic stainless steel SUS316L showed no degradation of fatigue life in high pressure gaseous hydrogen environment. In contrast, metastable austenitic stainless steel SUS304, precipitation hardening steel A-286 and low alloy steel SCM435 (high and low strength) showed degradation of fatigue life in high pressure gaseous hydrogen environment. Higher strengthened SCM435 showed degradation more significantly. It was clarified that the fatigue cracks grew along the interface between martensite phase and austenite phase in SUS304 with the use of Electron Back Scattering Diffraction Pattern (EBSD). Sub-cracks and intergranular fractures were observed in the fracture surface of A-286 which was tested in hydrogen environment. Intergranular fractures were observed in the fracture surface of high strengthened SCM435 and transgranular fractures were observed in the fracture surface of low strengthened SCM435 which was tested in hydrogen environment.