Cold metal transfer welding of Ti-6Al-4V sheets for aerospace and biomedical applications

Cold metal transfer (CMT) welding of Ti-6Al-4V sheets was carried out at different welding conditions, e.g. welding current, welding voltage and welding speed. It was observed that the weld pool size increased as a function of heat input during welding. The base metal (BM) had near equiaxed grains of α with insignificant amount (∼ 2%) of β at the boundaries of α grains. However, the fusion zone (FZ) and heat-affected zone (HAZ) consisted of predominantly α and α′ grains. The FZ exhibited the highest micro-hardness and residual stress values as compared to the HAZ and BM regions. The residual stress values of the welds were found to be compressive in nature and they decreased as a function of heat inputs of the welding. The welded samples had higher tensile strengths as well as ductility as compared to the sample before welding. Further, the strength and ductility of the welded samples were found to decrease with increasing the heat input of the welding. Similarly, the welded sample exhibited a lower corrosion rate and superior biocompatibility as compared to the base metal.