Investigation of Corrosion Behavior of Wrought and Wire + Arc Additive Manufactured Inconel 625 in Air and Molten Salts at High-Temperature Environments

A cutting-edge method for efficiently producing large-scale, almost net-shaped products using a layer-by-layer technique is wire + arc additive manufacturing (WAAM). An Inconel 625 thin-walled component was manufactured utilizing WAAM employing the Cold Metal Transfer (CMT) process with Inconel 625 filler wire. The research investigated the elevated temperature corrosion behavior of wrought and WAAM Inconel 625 in molten salt (MS) NaCl + V₂O₅, NaCl + K₂SO₄ and air at 700 °C. Corrosion-related compounds were analyzed for surface appearances, cross-sectional analysis and elemental makeup using scanning electron microscopy and energy-dispersive x-ray spectroscopy. The thermogravimetric analysis (weight change method) determined the corrosion kinetics in the Inconel 625 samples. X-ray diffraction (XRD) was used to determine the composition of the corrosion-related substances. The test findings showed that the corroded samples exposed to salt conditions underwent significant corrosion due to sulfidation and chlorination compared to those under air environments. An oxidized WAAM surface exhibited uneven, rough morphology; oxides were found, but no major failure occurred is commonly anticipated due to passivation and oxidation. However, the wrought Inconel 625 exhibited oxide scales and spallation occurred in MS environments, as was evident from the field emission scanning electron microscopy (FESEM) surface morphology and cross-sectional analysis. WAAM offered minimal oxidation and corrosion responses when compared with wrought Inconel 625, suggesting that the synergic effect of wire + arc additive manufacturing (WAAM) is beneficial for the manufacturing of Ni-based superalloy.