Ti-6Al-4V: Deformation map and modelisation of tensile behaviour

Tensile tests have been performed on a superplastic titanium alloy. Different strain rates from 5 × 10^-4 s^-1 to 5 × 10^-2 s^-1 and various temperatures up to 1050 °C were explored. The results of these tests, supplemented with microstructural investigations allow, as a function of temperature and strain rate, the determination of mechanical properties such as flow stress, strain hardening and fracture strain as well as the identification of mechanisms such as grain boundary sliding, dynamic recrystallization and dynamic grain growth. A modified Norton-Hoff law is proposed to characterize the tensile behaviour of this alloy. All temperature-strain rate combinations have been grouped into a number of domains, each corresponding to a particular deformation mechanism. For each domain the Norton-Hoff parameters have been determined. Close agreement between the predicted and experimental stress-strain relationships has been achieved.