Controlling the recrystallization behavior of a Mg-3Al-1Zn alloy containing extension twins

In the present study, a pre-treatment is employed to tailor the recrystallization behavior of a Mg-3Al-1Zn (AZ31) plate that contains {101¯2} twins. When the {101¯2} twins are generated by a transverse direction (TD) compression directly from a hot rolled plate, those twins have a quite high thermal stability and can be totally removed only after an annealing at 350 °C for 2 h. A severe grain coarsening takes place, too. In contrast, if a 5.5% pre-compression along the normal direction (ND) prior to the formation of {101¯2} twins is conducted, the stored energy increases and recrystallization behavior changes. Our results show that the 5.5% ND pre-compression does not change the main deformation mode during the subsequent TD compression and hardly reduces the compressive plasticity along the TD. The stored energy generated by the ND pre-compression results in extensive nucleation at grain boundaries and increases the thermal mobility of {101¯2} twin boundaries. A fully recrystallized structure with the refined grains is achieved after an annealing at 250° for 1 h and orientations of the {101¯2} twins are well kept after recrystallization.