Research on dynamic compression properties and deformation mechanism of Ti6321 titanium alloy

This research reports detailed investigations on the dynamic compression properties and the deformation mechanism in Ti6321 titanium alloy subjected to high strain rate loading by using the split Hopkinson pressure bar (SHPB). Microstructures of deformed samples were analyzed by scanning electron microscopy (SEM) with an electron backscatter diffraction (EBSD) detector and transmission electron microscopy (TEM). The experimental results demonstrate that with the increase of strain rate, the strength of Ti6321 titanium alloy increases significantly, which indicates the phenomenon of strain rate hardening. Due to twinning, the initial plastic deformation mechanism is by twin shear, the twins' interface is straight, continuous, and symmetrically distributed. The majority of twins are found at low strain stage (the strain range of 0.03 ∼ 0.06), which justifies the early initiation and contribution of twins in plastic deformation of the material. It also indicates that during plastic deformation twinning dominates the dynamic deformation mechanism. As the strain (e) increases further (when the strain is greater than 0.06), the number of twins also increases up to ε = 0.20. After that, the dynamic deformation mechanism started shifting from twinning deformation to dislocation slip.