Enhanced corrosion performance in Ti-6Al-4V alloy produced via wire-arc directed energy deposition with magnetic arc oscillation

In this study, the corrosion properties of Ti-6Al-4 V alloys using wire-arc Directed Energy Deposition (DED) with and without different Magnetic Arc Oscillation (MAO) patterns are comparatively evaluated. The relationship between corrosion resistance and microstructural features including grain size, geometrically necessary dislocation (GND), and grain orientation spread (GOS) of as-fabricated specimens are fully explored. The results show that magnetic arc oscillation, including liner arc oscillation and arc rotation, can enhance corrosion stability of as-fabricated Ti-6Al-4 V alloys. This enhanced corrosion stability is due to refined α grains, increased grain boundaries and enhanced dislocation density that provides more active reaction sites which, when coupled with adequate ion diffusion, expedites passive film growth on the Ti-6Al-4 V metal surface. Moreover, a transpassive film was directly observed on the Ti-6Al-4 V corrosive surface, and was confirmed to contain non-stoichiometric oxides. This study provides an insight into the corrosion mechanism of DED-produced Ti-6Al-4 V, and offers guidance for future process optimization and practical applications.