Study on modified Johnson-Cook constitutive material model to predict the dynamic behavior Mg-1Al-4Y alloy

Abstract

An accurate prediction of high speed impact behavior of metals by considering the combined effects of strain, strain rate and temperature is essential for understanding dynamic impact deformation of metals. To understand the effect of strain, strain rate and temperature on the high-speed impact behavior of Mg-1Al-4Y alloy, the dynamic impact compression experiments for Mg-1Al-4Y alloy were carried out by split Hopkinson pressure bar (SHPB). The mechanical properties of Mg-1Al-4Y alloy specimens were studied at different strain rate and temperature. The number of {10–12} extension twins decreases with the strain rate increasing from the electron backscatter diffraction (EBSD) technology, because of the formation of extension twins is suppressed with the strain rate increases, and dislocations become the main mode of dominant deformation. It is also found that the increase of strain rate has a positive effect on the strength of the material. But, the temperatures have a negative impact on the strength of the material. A modified Johnson-cook model has been presented, which shows good predictions with experimental results at different strain rates and temperatures. Especially, the predictions of the Johnson-cook equation are completely consistent with experimental results in small deformation stage.