The Ti6Al4V alloy is generally welded using gas tungsten arc welding (GTAW) technique, due to its easy availability and cheap equipment cost. The laser beam welding (LBW) technique is used in places where high quality and precision welds are preferred. Even though the GTAW technique is commercially cheaper, it has its inherent drawbacks like broad heat affected zone (HAZ) and associated metallurgical changes due to long duration of exposure to the welding arc. The laser beam welding produces a narrow heat affected zone (HAZ) and minimum welding defects, but its application is limited due to its high equipment cost.

In this investigation square butt joints were fabricated from 1.6 mm and 3 mm thick plates of Ti6Al4V alloy using laser beam welding process. The tensile strength, impact toughness, micro hardness, microstructure and the fractography of the weldments were studied to determine the effect of plate thickness on these mechanical properties and the mode of failure in laser beam welded joints. Even though the 3 mm thick plate exhibited high tensile strength, the notch strength ratio was less than unity, whereas the 1.6 mm thick plate showed lower tensile strength and higher notch strength ratio. This indicates that the 1.6 mm thick plate could be used in low strength applications and the 3 mm thick plates could be used in high strength static loads and low cycle load applications.