Constitutive modeling and hot deformation processing map of a new biomaterial Ti-14Cr alloy

A new biomaterial Ti-14Cr alloy was designed for biomedical applications. The manufacturing process of Ti alloys through hot deformation is crucial for controlling the grain structure and the mechanical performance of the alloy. In the present study, several compression tests at elevated temperatures (1123-1273 K) and strain rate ranges of 0.01-10 s-1 were conducted using a Gleeble-3800 thermomechanical simulator. A processing map of the studied alloy was constructed using the principles of the dynamic material model to evaluate the hot workability and deformation mechanisms at different ranges of temperature and strain rate. The resulting grain structure was correlated with the processing map. The processing map showed that adiabatic shear bands are expected to form at low temperatures (1123-1223 K) and moderate to high strain rates (1-10 s-1), whereas the nucleation of wedge cracks is likely to develop at the grain boundary at high temperatures and low strain rates (1248-1273/0.01 s-1). Consequently, a deterministic domain in the temperature and strain rate ranges of 1148-1273 K and 0.01-0.1 s-1, respectively, was identified as the domain of dynamic recrystallization with a peak efficiency of the order of ∼70% at 1173 K/0.01 s-1, and these were considered to be the optimum parameters for hot deformation. The constitutive flow behavior was modeled based on the hyperbolic-sinusoidal Arrhenius-type equations, and a mathematical relation was used to elucidate the influence of true strain on material constants.