Abstract:The samples of Ti-46Al-6(Cr,Nb,Si,B) (at%), G4 alloy for short, were hot compressed in the temperature range of 1050-1250 oC at constant strain rate from 0.001~1 s-1 for high temperature flow behavior and microstructural evolution study. The results show that G4 alloy displays a flow characteristic of hardening followed by softening during hot compression. The microstructure of G4 alloy evolves from as-cast big size γ+γ/α2 to small size near-equiaxed γ+α2. Dynamic recrystallization (DRX) is the main reason that results in flow softening and macro- and micro-structure evolution of G4 alloy. Temperature and strain rate are the two main factors that influence flow softening behavior and microstructure evolution of the G4 alloy during high temperature deformation. The main transformation mechanism of the G4 alloy at elevated temperature is kinking, curving, globalizing and DRX of γ/α2 lamellae, and elongating, breaking and DRX of γ grain, with twining as an auxiliary deformation mode. The optimum temperature for hot forming of cast near lamella G4 alloy is 1150 oC, and the strain rate should not exceed 0.1 s-1