Martensite stabilization effect after high strain rate loading

The behavior of shape memory alloys depends on the deformation technique and strain rate. This paper aims to demonstrate the martensite stabilization effect in equiatomic NiTi shape memory alloy after high strain rate loading. The high strain rate deformation at different rates and temperatures was performed using the Kolsky method modified for tension. Quasistatic deformation tests were conducted on a universal testing machine at identical temperatures up to the same residual strains. After tests, the samples were heated through reverse martensitic transformation temperature range in a thermomechanical analyzer with a temperature measurement accuracy of 0.3 °C. It is shown that the martensite stabilization effect depends on the loading rate in martensitic, premartensitic, and mixed phase states. An increase in the loading rate in the martensitic state results in a greater stabilization effect. High strain rate loading in the premartensitic and mixed-phase states does not lead to martensite stabilization, unlike in the quasi-static case. The results are consistent with the those of other authors and can be explained by hypotheses referenced in the paper.