Welding of dissimilar aluminium alloys

The results of GTA-welding of dissimilar aluminium alloys of the series 5xxx and 6xxx for plate thickness of 1.5, 3 and 5 mm are presented in this paper. Specific attention was given to the asymmetry of the weld and melting behaviour of the different weld grooves. Practical solutions are given for realising optimal weld penetration for materials with a large difference in thermal properties. Due to welding, the strength of the material in the HAZ is reduced. This reduction in strength is smaller for solution hardened and strain hardened alloys, than for precipitation hardened alloys. For the precipitation hardened alloys the reduction in strength due to welding is smaller for the naturally aged condition than for the artificially aged situation. The reduction in strength for the strain hardened alloys is independent of material thickness for the specified range of material thickness.