High temperature deformation behaviour of As-cast Ti-46Al-8.5Nb-0.2W alloy

The high temperature deformation behaviour during hot compression of as-cast Ti-46Al-8.5Nb-0.2W alloy was studied. The compression was performed at the temperatures ranging from 900 to 1100 °C with the strain rates ranging from 10^-2 to 2 × 10^-5 s^-1. The true stress-true strain curves during high temperature deformation exhibit a peak stress, which is followed by a gradual decrease into a steady state with increasing strain. The flow softening after the peak stress is attributed to the dynamic recrystallization during deformation. The activation energy Q was measured as 353 kJ/mol and the stress exponent was measured as 3.3. The dynamically recrystallized grain size decreases with decreasing temperature and increasing strain rate, i.e. with increasing the Z parameter (grain size D ∝ Z^-0.414).