The effects of texture and twinning on the yield asymmetry and differential work-hardening behaviour of an as-extruded AZ31 alloy under uniaxial compression and tension are investigated using a viscoplastic self-consistent model. The results show that the yield asymmetry and differential work-hardening behaviour can be attributed to the combined effects of strong fibre texture and the polar nature of twinning. The variation in the relative activity of each deformation mode under compressive deformation is much more complex than that under tension. Under tensile deformation, the major deformation modes are prismatic and pyramidal slips, while twinning and basal slip are the major deformation modes under compressive deformation. The presence of extension twins and contraction twins is confirmed by microstructural observations.
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and pyramidal 
slips, while twinning and basal slip are the major deformation modes under compressive deformation. The presence of extension twins and contraction twins is confirmed by microstructural observations.