The anisotropic corrosion behaviour of wire arc additive manufactured Ti-6Al-4V alloy in 3.5% NaCl solution

This study investigates the relationships between corrosion resistances, microstructure and phase composition of Ti-6Al-4V components that have been fabricated with the gas tungsten wire arc additive manufacturing (GT-WAAM) process, through the use of electrochemical corrosion testing, optical microscopy, X-ray diffraction and hardness testing. The corrosion behaviour is anisotropic due to corresponding anisotropy in microstructure, phase structure, grain size and orientation within the WAAM-processed Ti-6Al-4V alloy. Compared to ASTM standard wrought Ti-6Al-4V, the WAAM-processed alloy has a slightly inferior corrosion resistance owing to the formation of asymmetrical structures with lamellar α and acicular α’ phases, that display preferred orientation.