Influences of Friction Stir Welding and Post-Weld Heat Treatment on Al-Cu-Li Alloy

In this paper, the influences of friction stir welding (FSW) and post-weld heat treatment (PWHT) on the microstructures and tensile properties of Al-Cu-Li alloy are investigated. After FSW, strengthen loss occurred in the welding area. Remarkable softening occurs in the thermo-mechanically affected zone (TMAZ) resulting from dissolution of Al3Li () phases. Recrystallization and precipitation of ultra-fine phases take place in the nugget zone (NZ) that lightens the softening degree of this zone. A noteworthy enhancement in the hardness and tensile strength of the joint is achieved after T8 reaging treatment (3% - pre-deformation, 30h at 152 degrees C). However, re-solution treatment coupled with re-aging treatment leads to ductility deterioration in the joint because coplanar slip of coarse Al3Li phases induces severe stress concentration during plastic deformation.