A critical test of twin-induced softening in a magnesium alloy extruded to a strain of 0.7 at room temperature

Ambient extrusion was used to impart different uniaxial strains to a magnesium alloy. The aim was to test the idea that texture change at high strains can lead to work softening. Tensile tests, optical microscopy, X-ray diffraction and transmission electron microscopy were used to investigate the flow stress, microstructure and texture evolution up to a uniaxial strain of ∼0.7. The microstructure after extrusion is dominated by contraction twinning, which served to weaken the basal texture. However, no softening was observed; global work hardening persisted.