Role of microstructure heterogeneity on hydrogen-assisted fracture toughness degradation of X80 weld metal in H₂S-saturated solution

The hydrogen-assisted fracture toughness degradation of X80 weld metal with different microstructure heterogeneity was investigated through a crack tip opening displacement (CTOD) test in air and an H2S-saturated solution combined with a microstructure-based simulation. Differences in microstructure heterogeneity do not lead to variations in corrosion resistance; thus, the degradation of fracture toughness associated with microstructure heterogeneity is mainly controlled by hydrogen embrittlement (HE). The combined effects of increased microstructure heterogeneity and hydrogen promote damage associated with enhanced plastic strain localization. Hydrogen-dislocation interactions make it easier for dislocations to follow the {110} slip plane, resulting in void formation and crack initiation.