Mechanism of corrosion protection in reinforced Ti-6Al-4 V alloy by wire arc additive manufacturing using magnetic arc oscillation

Large titanium component fabricated using Wire Arc Additive Manufacturing (WAAM) remains a challenge as it is difficult to obtain uniform material properties, such as corrosion resistance, for industrial applications. In this study, corrosion performance of Ti-6Al-4 V alloy that have been fabricated using WAAM with magnetic arc oscillations were fully explored by means of material characterization and electrochemical corrosion testing. Compared to stable arc, oscillated arc specimens impart superior corrosion resistance owing to refined α grains that bring substantial grain boundaries to produce copious ion position or reactive site, allowing for rapid formation of passive film which is insusceptible to chloride-induced localized attack. For typical α + β structure, lamellar α size plays a critical role in passive film generation, growth and dissolution in corrosive media. The research outcomes provide a better understanding of corrosion behavior for Ti-6Al-4 V alloy fabricated by WAAM, which will benefit further process design and improvement.