Corrosion Inhibition Study of Waam-CMT Fabricated 316l Stainless Steel in 0.5 M Sulfuric Acid by an Aminophenol-Derived Schiff Base: Electrochemical and Surface Analysis

Wire arc addition (WAAM-CMT) technology enables faster and more cost-effective product design compared to other currently available additive manufacturing methods. This technology uses wire as the raw material and an electric arc as the heat source to build the metal components layer by layer. Known for its high deposition rates and cost-effectiveness, this technology is particularly well-suited for large-scale, complex structures. The final product exhibits a highly specialized, heterogeneous microstructure due to its thermal history. Currently, very few studies exist on the corrosion resistance of 316L steel when fabricated using the WAAM-CMT technique. Therefore, this study focuses specifically on the corrosion resistance of 316L steel fabricated using the WAAM-CMT technique in an acidic medium, specifically 0.5 M sulfuric acid (H₂SO₄), in the absence and presence of various concentrations from 5.10-6 to 10⁻³ M of an aminophenol-derived Schiff base (SB) inhibitor, at constant immersion temperatures, using electrochemical methods, specifically electrodynamic polarization and spectroscopic impedance measurement. The samples were analyzed using scanning electron microscopy, which confirmed the adsorption of the inhibitor onto the contact surface between the steel and the solution. Therefore, this organic compound acts as a catalyst in the aggressive medium of 0.5 M sulfuric acid. The corrosion potential did not exhibit a consistent pattern with varying (SB) concentrations. The changing slope of the cathodic and anode Tafel curves highlights the mixed nature of the inhibitor. The addition of (SB) leads to a decrease in current density. The corrosion rate (icorr) decreases with increasing ligand concentration, indicating that the inhibition process is due to the adsorption of (SB) onto the steel surface. The inhibition efficiency (EI%) shows an upward trend with increasing (SB) concentration. The optimal concentration of 10⁻³ M achieved an inhibition efficiency of 90.4%.