TIG Welding of Dissimilar High-Strength Aluminum Alloys 6061 and 7075 with Nano-Treated Filler Wires

Arc welding of dissimilar high-strength aluminum alloys is a major challenge in the automotive and aerospace industries due to differences in intrinsic material parameters and compositions. However, successful joining can lead to desirable combinations of material properties. To solve this problem, nanoparticles were loaded into AA6061 and AA7075 filler wires to fabricate nano-treated fillers, which were used to successfully weld AA6061 and AA7075. Neither weldment exhibited defects such as hot tearing or crater cracking, and both weld metals were observed to contain equiaxial grains smaller than 30 mu m. The principal mechanisms behind the observed microstructures originate from nanoparticle interactions during the welding process, as they affect the solidification behavior of the weld metal and modify eutectic secondary phases that traditionally lead to dendritic grain morphologies. The promising results of these dissimilar high-strength aluminum alloy welds show nano-treated fillers have much potential in welding systems that are traditionally difficult to weld.