Impact damage behaviors of Ti-6Al-4V alloy targets with different microstructures

The damage behaviors of Ti-6Al-4V alloy targets with two different states (aged state and annealed state) and three different thickness (thin, medium, and semi-infinite) impacted by 4 mm diameter GCr15 steel ball at a speed of 2.0 km/s were studied. The results show that the strength of the targets with aged state is higher than those with annealed state at two different strain rates. In the semi-infinite thickness targets, the depth and diameter of the crater in the targets with annealed state are similar to those with the aged state, but the volume of the crater in the annealed targets is about 1.5 times higher than those with the aged state. In the medium thickness targets, after being impacted, a plug was clearly formed in the rear of the targets with aged state, and a bulge was formed on the back face of the targets with annealed state. Abundant adiabatic shear bands were observed near the craters. Abundant adiabatic shear bands intercept each other and formed a net structure. The density and distribution range of abundant adiabatic shear bands in the targets with aged state are larger than those with annealed state. Two straight abundant adiabatic shear bands extending along tangential direction were observed and connected with the plug. Micro-voids nucleate, grow and coarsen in the abundant adiabatic shear bands, which leads to a premature failure.