Hot deformation characteristics and microstructure evolution of Ti-5Al-3Mo-1.5V alloy

A detailed investigation was conducted to study the concurrent effect of temperature and strain rate on the microstructure evolution in Ti-5Al-3Mo-1.5V dual-phase Titanium alloy. By applying varying strain rates from 10-3 to 10 s-1between 1098 and 1298 K at an interval of 50 K, isothermal compression characteristics and microstructural changes were recorded. The sizes of globules, concentrated predominantly at the lamellar kinks, were found to be inversely proportional to the strain rate. Further, a dynamic material model was employed to assess and plot the processing map displaying the safe hot working regime. The apparent hot-working activation energy in the alpha+ beta and beta phase field was 636 kJ/mol and 379 kJ/mol, respectively. A higher activation energy than the self-diffusion threshold of the alpha+beta and beta field was attributed to lamellae breakup and dynamic recrystallization in the respective phase fields. The microstructure analysis and identified softening mechanisms further helped in concluding the safe hot working regime to be 1248 K and 10(-3) s(-1).