Effect of post-deposition aluminizing on the corrosion and mechanical behavior of WAAM-fabricated stainless steel and Ni-based superalloy

The demand for corrosion-resistant and mechanically reliable metallic components in marine, chemical processing, and energy conversion industries has encouraged the integration of additive manufacturing into industrial production. Wire Arc Additive Manufacturing enables the fabrication of medium- to large-scale complex metallic structures at low cost; however, the high thermal input and layer-by-layer deposition commonly lead to elemental segregation, porosity, and nonuniform microstructures that degrade corrosion performance. This study investigates the influence of a post-deposition aluminizing treatment on the surface characteristics and corrosion behavior of stainless steel ER307 and nickel-based superalloy Inconel 625 produced by Wire Arc Directed Energy Deposition. Microstructural evolution, phase transformation, hardness distribution, and corrosion behavior in a 3.5% sodium chloride environment were examined through microscopy, X-ray diffraction, hardness testing, and electrochemical analysis. The aluminizing process generated localized surface porosity and limited non-uniformity aluminide coatings of approximately 40-50 mu m thickness, reduced surface roughness, and markedly improved surface hardness. Electrochemical assessments demonstrated substantial enhancements in corrosion resistance, including a 2.3-fold improvement for stainless steel and a 13.9-fold improvement for Inconel 625. These findings reveal that post-deposition aluminizing effectively mitigates intrinsic surface defects and microchemical heterogeneity, enabling significantly improved durability in chloride-containing environments. This work provides a straightforward and scalable strategy for enhancing the corrosion resistance of wire-arc-manufactured metallic structures and promotes their application in aggressive service conditions.