Hot work processing, microstrructure and mechanical properties of two-phase γ titanium aluminides

Hot-die forging has been undertaken on two-phase γ titanium aluminides. It has been shown that sound forgings can be achieved through using high billet temperatures (1250-1350 °C) and high die temperature (1000 °C). The inhomogenous as-cast microstructures causes the initially circular cross-section of the upset forgings to become elliptical. Hot-die forging leads to non-uniform macrostructure (formation of dead zones) and non-uniform microstructure (a network of lamellae and fine recrystallized γ grains). These non-uniformities are reduced with increasing temperatures of billet and die. The improvement in mechanical properties using high die and billet temperature is discussed in terms of surface quality of forging and microstructure effects.