Mechanical Behavior of Ti6Al4V Laser Welded Single Lap Joints

Laser welding technique has recently spread quickly thanks to its numerous advantages compared to traditional welding techniques, namely high precision, reduced welding beads size, high speed and possibility to be implemented in mechanical automatization systems. Owing to its superior characteristics and high reliability, laser welding is the preferred choice especially for joints made with titanium alloys, which are widely used for aircraft and aerospace structures. Therefore, the mechanical behavior of Ti6Al4V laser welded joints was investigated in this work. In particular, six specimens, cut from six different single lap joints made with different welding parameters, were equipped with two strain-gauges and subjected to tensile tests. The specimens were manufactured with six different terns of welding parameters: laser power of 3 kW for all joints, welding speed equal to 30 mm/s, 35 mm/s or 40 mm/s and laser beam focus equal to 0 mm or - 3 mm (i.e. half thickness of the joint). Results showed that the tensile properties of the single lap joints were significantly affected by the welding laser focus and that the lower the welding speed, the higher the tensile strength. The analysis of the load- strain curves led to the conclusion that the most resistant welded joints were those obtained with a welding speed of 30 mm/s and a surface (i.e., 0 mm) focus of the laser beam