Strain-rate effect on work-hardening behavior in β-type Ti-10Mo-1Fe alloy with TWIP effect

The strain rate effect (2.8 × 10−5-2.8 × 10−1 s−1) on the tensile properties and microstructure evolution of a β-type Ti-10Mo-1Fe (wt%) alloy has been investigated. With increasing strain rate, the yield strength increased, while the ultimate tensile strength, total elongation and uniform elongation decreased. It was found that deformation at a lower strain rate led to an enhanced work hardening rate (θ). This is reflected in the decreasing strain rate sensitivity of flow stress, m, with increasing strain. Strain rate sensitivity was positive at a smaller strain level (< 0.13), and decreased to a negative at a larger strain. The strain rate dependence of work-hardening behavior has been investigated and discussed in terms of the microstructure evolution, such as {332}<113> twins and dislocations. Electron Backscattered Diffraction (EBSD) and X-ray diffraction (XRD) analyses revealed lower increasing rates of {332}<113> twins and dislocation density at higher strain rates, which may be caused by adiabatic heating. This may lead to the reduced work-hardening rate on deformation at the higher strain rates.