Hydrogen-assisted failure of laser melting additive manufactured IN718 superalloy

Abstract A nickel-based superalloy IN718 was fabricated by laser melting additive manufacturing process and hydrogen embrittlement (HE) behavior of this alloy was assessed via slow strain rate tensile tests. The results reveal that hydrogen-charged as-deposited samples along vertical plane exhibit the lowest susceptibility to HE, followed by as-deposited samples along horizontal plane and then heat-treated samples. Additionally, hydrogen-assisted cracking of as-deposited samples initiates from γ-matrix/Laves phase interfaces, whereas γ-matrix/δ phase interfaces along grain boundaries act as preferable damage sites for hydrogen charged heat-treated samples. These hydrogen-assisted cracking can be explained by synergistic effect of HELP mechanism and HEDE mechanism.