Effects of Filler Wires on A7204 Aluminum Alloy Joint by Fiber Laser-VPTIG Hybrid Welding

By using the hybrid welding technology of fiber-laser and VPTIG (variable-polarity tungsten inert gas arc welding), the A7204 aluminum alloys are welded with different filler wires. The microstructures and mechanical properties of these joints by this hybrid welding are analyzed, and the softening behavior and mechanism of these joints are also investigated. The results show that the upper part of the weld with ER5087 filler wires presents the finest microstructure with narrow dendrite arms. After the natural aging of 90 days, the mechanical properties of joints welded with three kinds of filler wires are similar, and the tensile specimens fracture basically in the heat-affected zone which is close to the base metal. The microhardness of these joints welded with three kinds of filler wires in the heat-affected zone, 1.6-2 mm away from the fusion line, is the highest, in contrast, the softening zone obviously occurs in the heat-affected zone, 3-7 mm away from the weld center. In the heat-affected zone, there exist the obvious aging hardening zone and recrystallizat on softening zone, and the natural aging has an obvious effect on the softening of heat-affected zone.