AbstractThe fine grained, equiaxed duplexα/βphase microstructure of Ti–6AI–4V alloy enables large uniform plastic strains to be obtained under superplastic conditions. In this paper the role of microstructure and texture in superplastic deformation is considered. A banded, two phase microstructure gives rise to anisotropic superplastic flow stresses and strains, and can affect post-formed mechanical properties. The effect of microstructure is discussed with reference to the behaviour of Ti–6AI–4V alloy in various product forms: thick and thin sheet, extruded section and tube, and rolled bar. Manufacturing costs may dictate the use of fusion welding or diffusion bonding before superplastic forming, and the effect of such joints on deformation is described. The above data are related to other published work on Ti alloys, and the implications for the manufacture of components by superplastic forming are considered.MST/1328