Hydrogen Embrittlement of Ni-Based Superalloy Inconel 625 Fabricated by Wire Arc Additive Manufacturing: The Role of Laves Phase

The influence of hydrogen on the mechanical response of Ni-based superalloy Inconel 625 fabricated by wire arc additive manufacturing (WAAM) was investigated via slow strain rate tensile tests at room temperature. The results indicate that the WAAM superalloy just suffered from a slight necking deformation but still reached a high strain value in the presence of hydrogen. H promotes the fracture of the WAAM superalloy from ductile microvoid coalescence change to brittle quasi-cleavage. The gamma-matrix/Laves phase interfaces served as the preferred cracking sites in the alloy. However, the initiation of voids at the interface was not hydrogen-induced, which may be attributed to the strong hydrogen capture ability of the Laves phase, resulting in less hydrogen segregated to the interface. In the formation of voids in the interface at high stress, hydrogen accumulates at the interface through dislocation transport and stress-induced, weakening the interface binding force by hydrogen enrichment. Hydrogen enrichment at the crack tip diminished the stress field and thus reduced the energy required for crack cracking during cracking propagation.