Influence of heat treatment on the microstructure and properties of laser welds in 8090

An investigation into the weldability of the Al-Li-Cu-Mg-Zr alloy 8090 using a CO, laser indicates that the grain structure and microstructure of the weld zone are sensitive to the post-weld heat treatment. If a slow heating rate of 1Krnin-I to the solution treatment temperature is used the formation of P' (AIJr) dispersoids is promoted which leads to a uniformly small grain size within the fusion zone. If, however, faster heating rates are employed massive grains can form in 'the fusion zone. This is shown to be associated with a virtual absence of p' precipitates.