Investigation on hydrogen induced cracking behaviors of Ni-base alloy

Hydrogen embrittlement of a Ni-base alloy at room temperature was investigated by slow strain rate tensile test (SSRT) under precharging or dynamic charging conditions. It was found that hydrogen embrittlement susceptibility of this alloy increased with increasing charging current density in both charging conditions. In-situ observation of hydrogen induced cracking revealed that surface crack initiation at both grain boundaries and slip bands, which should be attributed to decomposition of hydride phase during aging at room temperature. SSRT result exhibited that hydrogen diffusion in the alloy could be facilitated by deformation and as a result induced transgranular fracture of the sample. Both hydrogen induced cracking and the interaction between hydrogen and deformation played combined roles on hydrogen embrittlement of this alloy.