On the statistical correlation between twin deformation and grain size of magnesium alloy under combined tension-torsion cyclic deformation

Abstract

To study the relationship between the twinning deformation and grain size of a magnesium alloy under combined tension-torsion cyclic (CTTC) loading, CTTC loading experiments with different paths and statistical analysis of the microstructure (grains and twins) were carried out. The test results show that the axial and tangential stress-strain cyclic curves present different symmetrical or asymmetrical characteristics due to the activation of the twinning-detwinning deformation mechanism. The statistical analysis of the microstructure shows that the grain size distribution of the magnesium alloy and the twin thickness distribution in all the grains conform to the Gaussian probability distribution. Furthermore it is found that the statistical correlation between twinning thickness and grain size is not obvious, but the number of twin nuclei is stable and positively correlated with the grain area, and with an increase in the amplitude, additional twin nuclei are produced in the same area of the grain. The research results can provide experimental data for effectively describing the twin deformation mechanism.