Dual increases in plasticity and strength of AZ31B/5052 clad plates subjected to one-pass hot rolling based on microstructural evolution

Abstract

AZ31 B/5052 clad plates fully preheated at 400 °C are subjected to one-pass hot rolling with reduction ratios of 40%, 50%, 58% and 66%. The interfacial bonding strength, ultimate tensile strength (UTS) and elongation (EL) of the clad plates increase significantly with increasing rolling reduction ratio. With increasing rolling pressure, the main deformation mechanism of the Mg layer gradually changes from twinning (reduction ratio of 40%) to full dynamic recrystallization (DRX, reduction ratio of 66%), realizing significant fine-grain strengthening. The Al layer shows significant work hardening strengthening with increasing reduction. This soft-hard combination of Mg/Al clad plates makes the strengthening effect induced by heterogeneous deformation during the tensile process, which makes its UTS higher than the calculated value of the rule of mixtures (ROM). The dual increases in plasticity and strength are analyzed from the effects of geometrically necessary dislocations (GNDs), twins, DRX, texture, and bonding strength. The choice of a 66% reduction ratio is a guideline for industrial production.