Microscopic mechanism exploration and constitutive equation construction for compression characteristics of AZ31-TD magnesium alloy at high strain rate

Uniaxial compression tests were conducted with strain rates in the range of 0.001–2000 s−1 at room temperature for transverse direction (TD) of AZ31 magnesium hot-rolled sheet alloy. The true stress-true strain curves were characterized by inflection points between convexity and concavity. The deformation mechanism of AZ31-TD was systematically discussed by combining Schmid Factor (SF), critical resolved shear stress (CRSS), electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). The results showed that the dominant mechanism of plastic deformation before inflection point of true stress-true strain curve was {101‾2} tension twinning, while the dominant mechanism of plastic deformation after inflection point was non-base slip. Based on the deformation mechanism of AZ31-TD analysis, a modified JC model was proposed to predict the true stress-true plastic strain curves of AZ31-TD magnesium hot-rolled sheet alloy, which agreed well with the measured curves. This solved the difficult problem of predicting the change of curve shape caused by tension twinning in the initial stage of plastic deformation.