Influence of electropulsing treatment on microstructure and mechanical properties of cold-rolled Mg–9Al–1Zn alloy strip

Influences of electropulsing treatment (EPT) on microstructure and mechanical properties of cold-rolled Mg–9Al–1Zn alloy strip were studied. EPT was found to accelerate the recrystallization of cold-rolled Mg–9Al–1Zn alloy strip at a relatively low temperature, and obtain fine microstructure of quasi-single-phase-recrystallized grains. The EPT-induced microstructural changes weakened the intensity of the basal fiber texture, and increased elongation to failure remarkably with a decrease in tensile strength. Fracture surface analysis showed that transition from intergranular brittle facture to transgranular dimple fracture took place with an increase in frequency of EPT. The rapid recrystallization behaviour of the Mg–9Al–1Zn alloy strip under EPT was attributed to the enhancement of nucleation rate and atomic diffusion resulting from the coupling of the thermal and athermal effects. It is supposed that EPT can provide a highly efficient method for the intermediate-softening annealing of magnesium alloys sheet/strips.

► EPT tremendously accelerated recrystallization of cold-rolled AZ91 alloy.
► The extent of EPT induced recrystallization increased gradually with frequency.
► EPT changed the tensile fracture behaviours of the AZ91 strip.
► A mechanism for rapid recrystallization of the AZ91 alloy under EPT was proposed.