Tensile Behavior and Microstructure of the 6082 Alloy Sheet with High-Temperature Aging Treatments

Abstract

The present study investigates the tensile behavior and microstructure evolution of the 6082 aluminum alloy aged with high temperature. A universal testing machine was applied to explore the tensile behavior, while features of the fracture surface were characterized via scanning electron microscopy (SEM). The microstructural evolution was assessed through optical microscopy (OM) and transmission electron microscopy (TEM). The findings illustrate that the 6082 alloy sheet achieves peak strength following treatment at 180 °C for 8 h for the 0° orientation specimen, with the yield strength and tensile strength reaching 345 MPa and 373 MPa, respectively. An increase in aging temperature results in a decline in strength, accompanied by an improvement in elongation. After the treatment at 330 °C for 0.5 h, the corresponding yield strength falls below 150 MPa, with elongation exceeding 12%. The alloy sheet consistently exhibits ductile fracture characteristics with various aging treatments. The aging processes have no obvious influence on grain morphology. The fibrous grain structure is responsible for the anisotropic mechanical properties. The alloy aged at 180 °C for 8 h demonstrates the greatest precipitate density with the smallest precipitate size. As the aging temperature increases, the precipitate distribution becomes less uniform, and the precipitates grow coarser, leading to a decline in the precipitate density and corresponding strength of the alloy. Furthermore, it is noted that smaller precipitates are more effective in suppressing the mechanical anisotropy of the alloy.