Effect of high strain rates on the mechanical behavior and structure formation of the titanium alloy Ti–6Al–4V

The mechanical behavior and structure formation of sheet specimens of the titanium alloy Ti–6Al–4V is studied. Low strain rate (quasi-static) deformation at ἐ = 0.001, 0.01, 0.1 and 1 s^–1 is compared with fast (dynamic) deformation performed using the Hopkinson method with ἐ = 1290, 2066, 3567, and 3828 s^–1. The features of the structure formation mechanism of the titanium alloy Ti–6Al–4V under high-strain-rate (≈3800 s^–1) deformation have been determined, namely that along with the dislocation glide, the twinning develops, the characteristics of texture present in the original sheet material undergo changes, plastic deformation occurs throughout the entire volume of the α-phase and β-phase grains (while in the quasi-static mode, mainly plastic deformation of the α-phase grains takes place), dislocation pile-ups and cells inside the grains are formed, which points to intensive interaction of dislocations. The established mechanisms lead to a substantial increase in technological plasticity of the titanium alloy during impact hydroforming as compared to quasi-static deformation.

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