Comparative Studies of Ti–6Al–4V Titanium Alloy Fractograms under Dynamic and Quasi-Static Plastic Deformation

Abstract—Comparative studies of fractograms of Ti–6Al–4V titanium alloy under dynamic and quasi-static plastic deformation have been conducted. The specimens were fractures of cap-type parts obtained by the Eriksen cupping test under different deformation rates, namely quasi-stationary (low $$\dot {\varepsilon }$$ = 1 s–1) and at impact hydroforming (high $$\dot {\varepsilon }$$ = 3828 s–1). Significant differences in the nature of the fractures have been revealed. It is shown that slow deformation results in predominantly ductile transcrystalline fracture in the presence of individual domains of brittle intercrystalline fracture corresponding to the breakouts of groups consisting of several grains. During dynamic deformation, a predominantly ductile transcrystalline fracture is observed, which indicates an increase in plasticity. In this case, the edges of the dimples are smoother than in the case of quasi-static deformation, which indicates the occurrence of additional local plastic deformation at the last stage of fracture. The revealed features of titanium alloy fracture are one of the reasons that ensure a more uniform deformation under dynamic loading and an overall increase in technological plasticity.