Effect of Pre-strain on High-Temperature Oxidation Behavior of Inconel 617 Superalloy Fabricated by Wire Arc Additive Manufacturing at 900 °C

The influence of pre-strains on the high-temperature oxidation behavior of Inconel 617 superalloy fabricated by wire arc additive manufacturing (WAAM) at 900 degrees C was investigated. The results reveal that the increasing pre-strain reduces the mass gain of the WAAM Inconel 617 superalloy significantly. A bilayer oxide film composed of an outer layer of Cr oxides with some (Ti, Ni)-oxides and spinel compounds and an inner layer of Al2O3 is generated on the surface of WAAM Inconel 617 superalloy. With pre-strain increasing, the oxide film becomes more dense, which could be attributed to the fast diffusion rate of the elements Cr and Al resulting from higher dislocation density. Furthermore, pre-strain promotes the precipitation of the Mo-rich phase in the interdendritic region and inhibits the formation of the Mo-oxide on the surface of the WAAM superalloy at high temperature. The phenomenon may be attributed to the decreasing outward diffusion rate of element Mo by the dense oxide film.