The effect of heat treatment on the microstructure and mechanical properties of 6082 aluminum alloy manufactured by friction stir additive

The Friction Stir Additive Manufacturing (FSAM) technique was employed to successfully fabricate multi-layered components of 6082-T6 aluminum alloy in this study. This study investigated the influence of heat treatment on the microstructure and mechanical properties of the additively manufactured 6082-T6 aluminum alloy parts. The results indicate that due to continuous dynamic recrystallization (CDRX), AZ exhibits a fine equiaxed grain structure . Compared to BM, the proportion of low angle boundaries (LABs) and the density of geometrically necessary dislocations (GND) decrease in the AZ samples. Subsequent to heat treatment, the HTAZ grains undergo static recrystallization (SRX) and exhibit abnormal growth, leading to a further reduction in LABs proportion and GND density . Following FSAM , the disappearance of the β” phase in AZ samples results in microhardness and tensile strength reaching 62.82 % and 64.46 % of BM, respectively. Variations in thermal cycling across different locations in AZ lead to heterogeneous mechanical properties. Post-heat treatment, the re-precipitation of high-density β” phases led to a 56.21 % strength recovery in HTAZ samples. Most importantly, the significant improvement and resolution of the mechanical property non-uniformity issue in the additive region were achieved. • Multilayer 6082-T6 aluminum alloy components were successfully fabricated by friction stir additive manufacturing. • The study investigated the microstructure evolution mechanism and mechanical properties of the additive material. • The problems of decreasing and non-uniform physical properties of additive were solved successfully by heat treatment.