Forming behavior of magnesium sheet

The mechanical behavior of O-temper AZ31B Mg sheet was measured in large-strain tension/compression. Metallography, acoustic emission (AE), and texture measurements revealed twinning and untwinning, producing asymmetric yield and hardening evolution. A novel analysis was used to estimate the relative sizes of hardening effects related to twinning: obstacle strength of twins to slip is approximately 1/3 the magnitude of textural softening caused by twin formation. The difference in activation stress of twinning versus untwinning is of the same magnitude as textural softening.