Shear behavior of TC4 alloy under dynamic loading

Two types (single-edged and double-edged) of TC4 (Ti-6Al-4V) alloy samples are tested by using the split-Hopkinson bar system under the strain rate of 10⁴ s^-1. By using ultra-high speed photography, the initialization and propagation of adiabatic shear band (ASB) are obtained with sufficient resolution. The relationship of the mechanical properties is built. The width of the shear band is observed to be 5-12 μm by using metallurgical microscope and scanning electron microscopy (SEM). Shear dimples and smooth regions are observed in the fracture surfaces as well. However, no obvious phase-transfer are detected. The double-edged samples have shown a better performance because of the relatively negligible bending during experimenting. The critical shear strain at which ASB appears is between 78%-88% and the propagation speed is estimated to be in the range of 460-1250 m/s. It is also found that when strain rate rises, the shear bands propagate faster. Moreover, the propagation speed increases as the loading process proceeds and the speed is linearly proportional with the nominal strain rate.