The microstructure and property of the Al-Li alloy 8090 weldments were investigated under the as-welded and post-welded heat treatment conditions. TIG and EB welding methods were used in this study. Two filler metals used were 2319 and 8090 for TIG welding. The test results show that as-welded 8090 weld is strengthed by solid solution of the alloying elements and precipitation of the fine δ' phase, but the coarse T_2 phase at the grain boundary decreases its strength and ductility. As-welded 2319 weld is also strengthened mainly by solid solution, but it contains more alloying elements, so its strength is higher than that of 8090 weld. For EB weld, the grain is finer, the segregation lower, and the brittle phase at the grain boundary less, so its strength is high-welded than that of 8090 weld. For the weldments under the post-welded solution and aged condition, δ' phase in 8090 weld coarsens so that the strength increases. The fractographs for tensile specimens reveal ductile intergranular fracture feature due to forming of δ'-precipitate-free zone near grain boundary. 2319 weld is strengthened by precipitation of the θ' and T phases. The alloying elements transfer from weld to the non compounded zone, so the fracture mode is variated, and the strength is increased.
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