Statistical Analysis of Grain-Scale Effects of Twinning Deformation for Magnesium Alloys under Cyclic Strain Loading

To reveal the relationship between grain size and twinning deformation of magnesium alloys under cyclic strain, this study carried out a group of strain-controlled low-cycle fatigue experiments and statistical analysis of microstructures. Experimental results show that the shape of the hysteresis loop exhibits significant asymmetry at different strain amplitudes, and the accumulation of residual twins plays an important role in subsequent cyclic deformation. For the different strain amplitudes, the statistical distribution of the grain size of magnesium alloy approximately follows the Weibull probability function distribution, while the statistical distribution of twin thickness is closer to that of Gaussian probability function. The twin nucleation number (TNN) increases with the increase of grain size, but there is no obvious function relationship between twin thickness and grain size. Twin volume fraction (TVF) increases with the increase of grain size, which is mainly due to the increase of TNN. This work can provide experimental evidence for a more accurate description of the twinning deformation mechanism.