Abstract

This study comprehensively analyzes the effect of high-pressure hydrogen gas on the elastic-plastic fracture toughness, fatigue crack growth rate (FCGR) properties, and the corresponding fracture behavior of Cr–Mo steel in hydrogen stationary vessels. The fracture toughness value under 99 MPa hydrogen pressure significantly reduced by approximately one-third of the value tested in ambient air while FCGRs tested under hydrogen environments at a specified ΔK exhibited an approximate two-order magnitude increase compared to those observed in ambient air. The hydrogen-assisted fracture mechanism, encompassing crack initiation, propagation, and crack arrested, was meticulously examined. The distinct variations in fracture modes with changes in the ΔK range can be attributed to the synergistic interaction of HELP and HEDE mechanisms. Leak before break (LBB) behavior was not satisfied for the hydrogen vessel due to a significant reduction in the fracture toughness of materials when exposed to 99 MPa H2.

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