Incremental deformation and the forgeability of titanium aluminide

Hot die forging has been undertaken on cube shaped workpieces of cast two-phase gamma titanium aluminide. The inhomogeneous as-cast microstructure causes non-uniform deformation and low ductility. Incremental deformation using hot dies aims to break down large alpha (2)+gamma lamellae in the structure by using an accumulation of small amounts of deformation with interspersed with periods for material recovery. The effect of various forms of incremental deformation, with or without subsequent isothermal forging, on microstructure is discussed. It is shown that the use of hot-die forging to refine microstructure is limited by chilling of the workpiece and loss in ductility. (C) 2001 Published by Elsevier Science Ltd.