Evolution of microstructure and texture of a near α titanium alloy during forging bar into disk

Abstract

Abstract Ti6242S alloy bar with equiaxed microstructure and random textures was selected to investigate evolution of microstructure and texture during the process of forging bar into disk by isothermal constant speed hot compression test. Experimental investigation shows that αp grains experienced bend, rotation under prismatic slip system action and further separated into refined grains by dynamic recovery or dynamic recrystallization with the increase of strain. Sharp macrozones existed in Ti6242S alloy were completely eliminated when strain arrived at 50%. Two main texture components of 2 ¯ 0> and 2 ¯ 3>//compression direction were developed in all deformation strain. The former was mainly caused by the activated prismatic slip system motion of α phase during deformation and the precipitated αs phase neighboring αp phase after β→α transformation which hold the same orientation with αp phase. The latter was the results of αp phase dynamic recrystallization and polycrystalline coordinated deformation of αp/αp or αp/β phases, likewise, the same orientation αs laths with neighboring αp phase preferentially precipitated after β→α. It is also demonstrated that if the strain surpassed 50%, especially for multi-step deformation to 70% dynamic recrystallization lightly softened the texture density.