Abstract: The uniformity of microstructure distribution across the transverse section of a Ti-6AI-4 V bar afler stepwise radial forging process is a relevant index to the quality of the foaled bar. In this work, hot deformation chamcteristics of Ti-6Al-4 V bar in the stepwise radial forging process were investigated in the or+p and g range 6etween 940℃ and 1000℃. Various flow curves and microstructures were obtained by using Gleeble simulation. The deformation process of a bar from initial diameter to a desired reduction in cross section was simulated by using a FEM code ABAQUS combined with the constitutive models obtained from physical simulation. Heat onduction model was coupled to the computation. The principal stresses and final strain istribution of the bar after forging were predicted by the contours obtained from FEM analysis. Together with the results obtained from Gleeble simulation, a map of microstructure distribu- tion on the cross section of the forged bar was constructed. According to the map,recrystallized zone in the center region of the bar was predicted to be approximately 50 to 65% of the total cross section area.

Key words: Ti-6Al-4V alloy, hot deformation, Gleeble simulation, finite element method