Hydrogen embrittlement behavior of selective laser-melted Inconel 718 alloy

In this study, slow strain rate tensile tests under in situ hydrogen electrochemical charge are performed to investigate the hydrogen embrittlement (HE) behavior of selective laser-melted (SLM) and post-heat-treated Inconel 718 alloys in tandem with microstructure evolution and cracking feature characterization. The results indicate that the high density of dislocations and local strain along the cellular structure walls in the as-SLM sample increase local hydrogen concentration, leading to a crack along the cell walls of the cellular structure. The tensile strength and the HE susceptibility are significantly enhanced by the precipitation of the γ′, γ″, and δ phases generated by solution aging. Solution-aged samples suffer from the severe HE susceptibility caused by the δ phase formation along the grain boundaries and the cell walls, which lead to the δ/γ interface cracking.