| Abstract Scope |
Despite the growing interest in additive manufacturing, there remains a significant gap in research concerning corrosion behavior of wire-based methods. Most of the existing studies have predominantly focused on powder-based methods, leaving wire-based techniques relatively underexplored. This disparity in research attention highlights the need for additional corrosion research involving wire-based methods to fully understand their potential benefits and applications. In this study, the corrosion behavior of alloy 625 produced by laser-wire directed energy deposition (LW-DED) and wire arc additive manufacturing (WAAM) was investigated using electrochemical techniques. Samples were subjected to open circuit potential, Tafel analysis, potentiodynamic, and potentiostatic testing (+1V vs. OCP) in a 3.7% HCl electrolyte, employing a silver/silver chloride reference and platinum counter electrode. Post-test characterization included optical and scanning electron microscopy with energy dispersive spectroscopy. Both methods yielded dendritic microstructures with segregation of niobium, molybdenum, and titanium into interdendritic regions, which displayed heightened susceptibility to corrosion. Corrosion products primarily consisted of niobium and molybdenum oxides, with titanium enrichment observed. LW-DED samples demonstrated higher average corrosion potentials and lower corrosion rates compared to WAAM samples, attributed to their finer, multi-pass microstructures and alternating print direction per layer. In contrast, WAAM samples, built in single passes per layer, exhibited coarser microstructures and increased corrosion susceptibility. This study highlights the influence of wire-based additive manufacturing techniques and resulting microstructures on the localized corrosion resistance of alloy 625, with LW-DED offering enhanced corrosion performance relative to WAAM. |