Role of tension twins on warm deformation behavior of AZ31 Mg alloy

Abstract

Twinning has been known to play an important role on plastic deformation of wrought magnesium alloys. Role of tension twins on warm deformation has thus been investigated in this study under two different loading conditions, viz. tensile and compressive loading at 250 °C using hot-rolled AZ31 magnesium alloy. Tension twins were observed to form under a compressive loading perpendicular to the c-axis and also under a tensile loading along the c-axis at 250 °C. Various morphologies and volume fractions of tension twins were generated under different loading conditions, but they exhibit different flow curves and work hardening behavior during the warm deformation. The ‘Hall-Petch type hardening effect’ appeared to contribute significantly in an early stage of deformation below the strain of ∼0.1, while texture hardening effect became dominant above the ∼10% strain in RD-C specimen. ND-T specimen was, on the other hand, found to generate tension twins continuously up to fracture, but dislocation slip became dominant with increasing strain above ∼10%. Twins were also found to affect dynamic re-crystallization behavior during warm deformation.