Study of mechanical, microstructural and thermal stability properties of friction stir processed aluminum 2024-T3 alloy

Friction Stir Processing (FSP) was applied on AA2024-T3 plates. The hardness and tensile properties of the stir zone were tested, and a microstructure study was conducted. During the FSP the coarse elongated grains of the parent material changed into fine equiaxed ones, refinement of the coarse precipitates detected at the parent material occurred at the same time. The material subjected to FSP was found to be thermally unstable, as revealed by aging experiments at 300◦C and precipitate chemical analysis. TEM study showed that the rolled parent material contained low-angle sub-grains with dislocation network boundaries. During FSP these were replaced by fine equiaxed grains with clear boundaries and no dislocation tangles. This led to the conclusion that the material underwent Dynamic Recovery (DRV) during the rolling process, as opposed to Dynamic Recrystallization (DRX) during FSP. Thus, FSP appears to have the technological potential for improving the microstructure and mechanical properties of AA2024.