Analyses of Anodically Formed Passive Film and Corrosion Behavior of Wire-arc Additive Manufactured ATI 718Plus® Superalloy

The corrosion behavior and surface passive film properties of ATI 718Plus® prepared by wire-arc additive manufacturing (WAAM) and subjected to solution heat treatment and aging (STA) are analyzed in this study. An orientation-dependent micorstructural variation is observed on the vertical section (VS, parallel to the build direction) and horizontal section (HS, vertical to the build direction) of STA-WAAM 718Plus. However, potentiodynamic polarization measurements show that there is no significantly anistropic corrosion resistance in the VS and HS of the STA-WAAM 718Plus under both acidic and Cl- environments at room temperature. A comparative analysis of their passive film properties is performed using potentiostatic polarization, X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and the Mottt-Schottky method. The results indicate that this similar corrosion behavior in the STA-WAAM 718Plus is due to comparable characteristics of passive film, in terms of composition, structure, steady-state current density, impedance, as well as the same n-type semiconductors with similar donor density and flat band potential.