Dynamic tensile and compressive properties of vacuum and ordinary die-casting AT72 magnesium alloy at high strain rates

To investigate dynamic tensile and compressive properties of AT72 magnesium alloys under high strain rates, the Split Hopkinson tensile Bar (SHTB) and the Split Hopkinson Pressure Bar apparatus was used at ambient temperature. The specimens after dynamic tension and dynamic compression were analyzed by scanning electron microscope (SEM) and metallographic microscope. Dynamic mechanical properties and fracture mechanism were discussed in this paper. The results show that at approximate tensile strain rate, the dynamic tensile strength of ordinary die-casting AT72 and vacuum die-casting AT72 is very similar, but the dynamic failure strain is of great difference. AT72 magnesium alloys under dynamic compressive yield continuously, and have the slight positive strain rate effect. The dynamic compressive behaviors of ordinary die-casting AT72 and vacuum die-casting AT72 are nearly the same. The dynamic tensile fracture mechanism of both vacuum die-casting AT72 and ordinary die-casting AT72 is inter-granular fracture. The dynamic compressive fracture mechanism of both vacuum die-casting AT72 and ordinary die-casting AT72 is quasi-cleavage intra-crystalline failure. The pores have an important effect on dynamic properties of die casting magnesium alloys.