Laser-pulsed MIG hybrid welding technology of A6N01S aluminum alloy

Welding research of A6N01S-T5aluminum alloy profile for high-speed train was done by using laser-MIG hybrid welding and MIG welding individually.And the weld appearance,welding distortion,mechanical properties of the joints and microstructures were analyzed.The test results demonstrated that high-efficient welding for the profile can be achieved by using laser-MIG hybrid welding,the speed of which can be over3.0 m/min.The processing had a good gap bridging ability，even if the gap of the butt joint was up to2.0 mm,a good weld appearance can also be got.While the hybrid welding speed was greater than2.5 m/min,the welding distortion of the laser-tandem MIG hybrid joints was just about33%of that of the MIG joints,but the welding efficiency was over3times of MIG welding.And tensile strength of the hybrid joints was85%of that of A6N01S-T5base metal, 9%higher than that of the MIG joints.Fatigue properties was tested individually with pulsed tensile fatigue method in the condition of1×107 lifetime.The test results demonstrated that the fatigue strength of the joints was a little lower than that of base material,which could be up to115 MPa.But the fatigue strength of hybrid welding joints was107.5 MPa,which was23%higher than87 MPaof MIG welding joints.