Laser welding 6A02 aluminum alloy with filler wire under high welding speed

The experimental of fiber laser welding 6A02 aluminum alloy with filler wire was carried out, and high welding speed with 6m/min was used. The effects of different wire feeding speeds on cross-section shapes of welds, joints' microstructure and tensile properties were analyzed. The laser energy melting the base metal to achieve the keyhole effect is defined as relative heat input. It is affected by the wire feeding speed, which leads to the changes of the penetration state of laser welding and the coarsening degree of the microstructure of the joint. The microstructure of the joints presents the columnar grains near the fusion zone and the mixed grains (columnar grains + equiaxed grains) in the weld center zone. For the joints with full weld formation, the microstructure of joint with as-welded state by using wire feeding speed of 4m/min is finer than that with wire feeding speed of 2m/min slightly. And the tensile strength of joints of the former is a little higher than that of the latter. The average ultimate strength of the joints in the as-welded state could reach 245MPa, while that in the heat-treated state could reach 373MPa. All o f the tensile fractures occur near the fusion zone. However, the angles between the fracture surfaces and the base metal surfaces are different significantly by observing the tensile fracture positions of as-welded and heat-treated joints.