Using OIM to investigate the microstructural evolution of Ti-6Ai-4V

Orientation imaging microscopy provides both microstructural and crystallographic-texture information that allows a coupled analysis of changes in texture and microstructure. This capability has been used to determine how microstructure develops by transformation from beta to alpha in Ti-6Al-4V and by subsequent hot working to develop a fine-grain microstructure that is technologically desirable for secondary processes such as rolling and superplastic forming. With this technique, the mechanisms that account for the retention of large clusters of grains with similar grain orientation, heterogeneous deforination phenomena such as shear banding, and cavity nucleation and growth, can be elucidated. From such examinations, the development of physically based constitutive models and new forming strategies to improve the homogeneity of the microstructure are possible.