Influence of Welding Parameters on Weld Formation and Microstructure of Dual-Laser Beams Welded T-Joint of Aluminum Alloy

This paper focused on the welding 1.8 mm thick 6061 aluminum alloy plates in T-joint form using dual lasers that introduced by a Nd: YAG laser and a CO2 laser with 4043 aluminum filler wire. The effects of welding parameters on the T-joint weld appearance, microstructure and the joint mechanical properties were studied systematically, The influence of welding parameters included the distance between two laser beams, welding speed, laser power and the laser beam offset toward the stringer. The weld appearance, microstructure, hardness of the joint were evaluated by optical microscope and micro-hardness test. A monotonic quasi-static tensile test was conducted by a self-made clamping device to obtain the tensile property of welded joints. At the optimized parameters, the welded T-joint showed good weld appearance without macro defects; the micro hardness of welds ranged from 75 to 85 HV0.3, and the tensile strength was about 254 MPa with the fracture at the heat affected zone on the stringer side