THE FUSION WELDING OF Al-Li-Cu-Mg (8090) ALLOY

Abstract
Successful TIG welds have been made in the Al-Li-Cu-Mg alloy 8090-T6. Weld zone porosity associated with the adsorption of water vapour by oxide formed during solution treatment or hot rolling can be largely eliminated by machining prior to welding. Susceptibility to weld cracking as measured by bead-on-plate tests is similar to that of 2014-T6, indicating the likelihood of successful welding except where there is severe restraint. Using an 8090 filler produces specific weld strengths comparable to those of the strongest commercial weldable aluminium alloys. Ductility is lower and fractures are intergranular. Transgranular fractures occur when Al-5Mg filler is used, but the strength achieved is lower. Post-weld (-T6) heat treatment increases the strength of the welds but the grain boundary structure and composition, with which the brittleness of the welds is associated, restricts the improvement of mechanical properties.