Microstructural characteristics and mechanical properties of Ti6Al4V alloy fiber laser welds

In this paper an experimental analysis on laser beam welding process of Ti6Al4V titanium alloy was performed. Butt joints with a thickness of 2 mm were produced and assessed. A high brightness fiber laser was adopted to carry out the analysis. No filler wire and shaped grooves were used. An experimental plan was implemented keeping constant the laser power and varying the welding speed. A proper device was adopted to prevent oxidation phenomena that involve Ti at high temperatures reached during the thermal process. The geometric characteristics of the welding beads were studied through metallographic inspection of the cross sections. Vickers micro-hardness tests were conducted at the mid thickness of the cross sections of the joints and its variation in function of the distance from the welding line was achieved. Two tensile strength tests for each welding condition were performed in order to evaluate the mechanical properties of the welds. Results revealed a contained extent of the FZ and HAZ in the cross sections. The reduction of mechanical properties of the welds in comparison with those typical of the parent metal was about 20%, which is a good result in comparison with other previous research works.