Hot compression deformation behavior of biomedical Ni–Ti alloy

Biomedical Ti-55.78 (wt%) Ni alloy samples were prepared by vacuum induction melting, and their hot compression deformation behavior was studied in the deformation temperature range of 750–950 °C, the strain rate range of 0.001–1.000 s⁻¹ and the true strain range of 0.1–0.7. The constitutive equation of the as-cast biomedical Ni–Ti alloy was established based on the Arrhenius constitutive model, and error analysis of the constitutive equation was carried out. The processing zone and unstable thermal deformation zone of the as-cast biomedical Ni–Ti alloy were obtained by establishing hot processing maps based on a dynamic material model. The results showed that deformation temperature and strain rate were the main factors affecting the flow stress. The results of error verification of the constitutive equation show that the predicted flow stress curves agree well with the measured ones. Therefore, the constitutive equation based on Arrhenius can accurately predict the high temperature flow stress of as-cast biomedical Ni–Ti alloy. The optimum parameters for forging process of biomedical Ni–Ti alloy are the strain rate less than 0.003 s⁻¹ and the hot deformation temperature range of 930–950 °C.