Optimizing the microstructure and mechanical properties of a cold-rolled Al–Mg–Li alloy via electropulsing assisted recrystallization annealing and ageing

Abstract

The combined processing of electropulsing assisted recrystallization annealing (EARA) and electropulsing assisted ageing (EAA) was designed as an efficient environmental-friendly route to optimize the microstructure and mechanical properties of a cold rolled Al–Mg–Li alloy. The EARA treatment could rapidly complete the recrystallization and texture weakening of the cold rolled alloy within tens of seconds, which was mainly due to the promotion effect induced by electropulsing. The electropulsing promoted the climb of dislocations by accelerating the diffusion of vacancies, further resulting in the rapid continuous microstructure evolution from cold deformed structure to substructure and recrystallized grains. After the subsequent EAA treatment, the mechanical properties of the alloy were improved remarkably due to the combination of the precipitation strengthening of δ′ phase, grain refinement and texture modification. The 66.7% cold rolled alloy treated by EARA + EAA exhibited the most excellent mechanical properties with the yield strength of 355.3 MPa, ultimate tensile strength of 527.2 MPa and elongation of 10.9%. Besides, the anisotropy of mechanical properties was weakened substantially due to the grain refinement and texture weakening. The mechanism of electropulsing induced rapid recrystallization and the effect mechanism of microstructure on mechanical properties were discussed in detail.