Correlation between microstructure and properties of 2219/5A06 dissimilar aluminum alloy welded joint

Two different aluminum alloys of 2219-T87 and 5A06-H112 with thickness of 5.5 mm were jointed using plused VP-TIG butt welding. The microstructure and mechanical properties of the joint was investigated. The results show that the microstructure in heat-affected zone on the 5A06 side is equiaxed crystal, the strip structure in the heat-affected zone on the 2219 side is getting coarser, and the welding seam is composed of equiaxed crystal. The fine equiaxed crystal band and porosity defects near the fusion line on the 2219 side, and the low angle grain boundary near the fusion line on the 2219 side is less than that near the fusion line on the 5A06 side, which lead to the failure of the fusion line on the 2219 side during the tensile texts. During the tensile texts, the fracture of the specimen occurred along the maximum strain near the fusion line of 2219 side. The tensile strength of the joint reached 63.6% and 75.3% of the base material of 2219 and 5A06, and the elongation reached 30.5% and 29.8% of the base material of 2219 and 5A06, respectively.