Investigation on the Corrosion Behavior of Solution-Treated Inconel 718 Alloy Fabricated by Selective Laser Melting

Abstract

This study investigates the corrosion behavior of solution-treated selective laser melted (SLM) Inconel 718 alloy in marine environments and various corrosive media. Electrochemical tests demonstrate that solution treatment effectively reduces the corrosion current density and enhances polarization resistance, significantly improving the corrosion resistance of the material. EBSD analysis reveals an increase in average grain size from 12.78 mu m to 17.28 mu m and a decrease in Kernel Average Misorientation (KAM) values, indicating the release of lattice strain which contributes to mitigating localized corrosion. XPS results show that with increasing polarization potential, the surface oxygen content rises from 9.33 at pct to 20.78 at pct, while Fe content markedly decreases. A dense and stable passive film, primarily composed of Cr2O3 and MoO2, forms on the surface, providing the main protective effect. Although NiO and Fe oxides exhibit self-healing capabilities, their protective performance is comparatively inferior. The formation of Nb2O5 may adversely affect the stability of the passive film. Overall, both solution treatment and the composition of the passive film play critical roles in enhancing the corrosion resistance of SLM Inconel 718 alloy.