Corrosion Behavior of a Selective Laser Melted Inconel 718 Alloy in a 3.5 wt.% NaCl Solution

The corrosion behavior of an Inconel 718 alloy fabricated using the selective laser melting (SLM) technique in a 3.5 wt.% NaCl solution is determined. The corrosive effect of the NaCl solution on the Inconel 718 alloy is investigated using potentiodynamic polarization curve measurements, Mott-Schottky plots, electrochemical impedance spectroscopy, atomic force microscopy, and x-ray photoelectron spectroscopy (XPS) and is compared with that on a commercially rolled Inconel 718 alloy (R 718). Electrochemical results suggest that the application of SLM to the Inconel 718 alloy lowers its corrosion resistance. The passive films formed on both alloys show p-type and n-type semiconductor behaviors. However, the concentrations of the defects in the passive films formed on the surface of the SLM Inconel 718 alloy are higher than those on the surface of the commercially rolled R 718. XPS shows that the passive film formed on the SLM Inconel 718 alloy has a higher NiO content, leading to the deterioration of its protective properties.