Microstructure and performance analysis of laser-MIG hybrid welding joints of aluminum alloy with multi-stranded wire

The butt welding experiment of 5A06 aluminum alloy laser multi-strand MIG hybrid welding was carried out by 1 × 3 structure ER5356 aluminum alloy multi-strand wire. The mechanical properties and microstructures of 20 mm thick welded joints were studied by scanning electron microscopy, EBSD analysis, tensile and hardness tests. The results showed that the laser multi-strand MIG hybrid welding presented good process performance. The weld was mainly composed of α (Al) matrix and dispersedly distributed Al₃Mg₂ second phases. The center zone of the weld was mainly equiaxed grains, with the average grain size of 34.83 μm. The grain in the heat affected zone was fine, with the average grain size of 10.21 μm, and there existed recovery and recrystallization. The hardness of the welded joint was between 75 and 90 HV, and that of the fusion zone was the lowest, which was 84.6% of the base metal. The average tensile strength of the welded joint was 291 MPa, which was 84.2% of that of the base metal. The fracture position of the tensile specimen was near the fusion zone, and the fracture showed ductile fracture characteristic.