Processing map for a cast and homogenized near alpha titanium alloy

The high temperature deformation behaviour of cast and homogenised near alpha titanium alloy Titan 29A (M/s MIDHANI, India), equivalent to IMI 834 (M/s TIMET, UK) was studied towards developing a processing map. The processing map is interpreted in terms of the microstructural changes occurring during deformation, based on the values of a dimensionless parameter eta which represents the energy dissipation through microstructural evolution processes. An instability criterion (xi < 0) is applied to demarcate the flow instability regions in the processing map. Both the parameters (eta and xi) were computed from the experimental data generated by hot isothermal compression tests conducted at various temperature (T) and strain rate (epsilon) combinations T = 850-1100 degrees C and epsilon= 3 x 10(-4) to 10 (0)/s. The deterministic domains observed in the investigated temperature and strain rate regime are attributed to continuous dynamic recrystallization of alpha lamella and dynamic recrystallization of beta grains.