Coordinated deformation and high formability mechanisms of Al–Zn–Mg–Si–Fe–Mn–Cu alloys with heterogeneous cellular structure

Abstract

The formation of a heterogeneous microstructure and its effect on the deformation behavior and formability of Al–Zn–Mg–Si–Fe–Mn–Cu alloys prepared by novel thermomechanical processing were systematically investigated. The results reveal that heterogeneous microstructures, i.e., the coexistence of hard and soft microdomains and recrystallized grains with a cellular structure, were obtained in alloy sheets by the synergy of thermomechanical processing. Furthermore, mechanical property tests show that the alloy with a reasonable heterogeneous microstructure possesses a significantly enhanced formability (r = 0.7705) and a low anisotropy (Δ r = −0.047), which can make this alloy very promising in automotive outer body panel applications. In addition, based on the microstructure evolution during the whole thermomechanical processing, the formation and high formability mechanisms of heterogeneous microstructure in Al–Zn–Mg–Si–Fe–Mn–Cu alloys is proposed in this paper.