The hydrogen embrittlement of pure Ni fabricated by additive manufacturing

This work investigated the hydrogen embrittlement mechanism of Ni fabricated by laser-based powder bed fusion (L-PBF). In the presence of hydrogen, the L-PBFed Ni failed with a brittle mode, while its fracture surface had a “transgranular-like” appearance. This unusual fracture morphology is rooted in the special grain shape induced by the laser-based manufacturing process, and the failure process is actually predominated by the intergranular decohesion. An annealing process of the as-printed sample enhanced its elongation and mitigated the hydrogen embrittlement. The special dislocation cellular pattern formed in additive manufacturing is considered to be detrimental to hydrogen embrittlement resistance.