Effect of welding speed on butt joint quality of Ti\u20136Al\u20134V alloy welded using a high-power Nd:YAG laser

Annealed Ti\u20136Al\u20134V alloy sheets with 1 and 2 mm thickness are welded using a 4 kW Nd:YAG laser system. The effects of welding speed on surface morphology and shape, welding defects, microstructure, hardness and tensile properties are investigated. Weld joints without or with minor cracks, porosity and shape defects were obtained indicating that high-power Nd:YAG laser welding is a suitable method for Ti\u20136Al\u20134V alloy. The fusion zone consists mainly of acicular \u3b1\u2032 martensite leading to an increase of approximately 20% in hardness compared with that in the base metal. The heat-affected zone consists of a mixture of \u3b1\u2032 martensite and primary \u3b1 phases. Significant gradients of microstructures and hardness are obtained over the narrow heat-affected zone. The laser welded joints have similar or slightly higher joint strength but there is a significant decrease in ductility. The loss of ductility is related to the presence of micropores and aluminum oxide inclusions.Peer reviewed: YesNRC publication: Ye