Good combination of strength and mechanical isotropy in AA6082 alloy processed by high temperature intermediate annealing

Abstract

The microstructure, textures and mechanical property anisotropy of AA6082 alloy sheets after intermediate annealing were investigated. The result shows that the anisotropy of final cold-rolled and T6 alloy sheets decrease and the strengths increase as the intermediate annealing temperatures rise from 400 °C to 550 °C. Higher intermediate annealing temperature promotes the coarsening of soluble Mg2Si particles, which influences subsequent recrystallization and precipitation. The final cold-rolled sheet intermediately annealed at 550 °C presents weak rolling textures, thereby decreasing in-plane anisotropy (IPA) of yield strength from 4.4% to 2.5%. The T6 sheet intermediately annealed at 550 °C exhibits high yield strength (326 MPa), which is ascribed to the synergistic effects of precipitation strengthening, texture strengthening and grain refinement. Meanwhile, it presents high volume fractions of CubeND and random textures. This causes that r̅ value increases by 9.2% and ∆r value decreases by 80%.