Effect of joint gap on Nd: YAG laser welded Ti-6Al-4V

Abstract

The effect of joint gap on the butt joint quality of Ti-6Al-4V alloy welded using 4 kW Nd:YAG laser was evaluated in terms of welding defects, microstructure, hardness and tensile properties. Fully penetrated welds were obtained up to a joint gap of 0.5 mm. No cracks were detected. The main defects observed in the welds are porosity and underfill. The porosity area increases with increasing joint gap but remains less than 1% of the fusion zone area. Large underfill defects appear at the welds in the absence of a joint gap but the use of filler wire can reduce this defect in the presence of a joint gap. The weld hardness is slightly decreased with increasing joint gap but the tensile properties seem to be optimized at an intermediary joint gap, probably due to the compromise between the low underfill (after the use of filler wire) and a limited amount of porosity.The effect of joint gap on the butt joint quality of Ti-6Al-4V alloy welded using 4 kW Nd:YAG laser was evaluated in terms of welding defects, microstructure, hardness and tensile properties. Fully penetrated welds were obtained up to a joint gap of 0.5 mm. No cracks were detected. The main defects observed in the welds are porosity and underfill. The porosity area increases with increasing joint gap but remains less than 1% of the fusion zone area. Large underfill defects appear at the welds in the absence of a joint gap but the use of filler wire can reduce this defect in the presence of a joint gap. The weld hardness is slightly decreased with increasing joint gap but the tensile properties seem to be optimized at an intermediary joint gap, probably due to the compromise between the low underfill (after the use of filler wire) and a limited amount of porosity.