Effect of high-temperature deformation on the texture of a two-phase titanium alloy

Abstract

Changes in the texture of both the α- and β-phases of the two-phase alloy Ti-6AI-4V have been determined in order to clarify the mechanisms of high-temperature deformation. A strain of ∼ 1.5 was applied to the alloy at 928 °C, at strain rates representative of superplastic and nonsuperplastic conditions. The α-phase texture changed very little with strain rate whereas that for the β-phase was much more sensitive. The β-phase texture was weakened at superplastic strain rates but developed a fibre texture at non-superplastic rates. It is postulated that under superplastic conditions the alloy deforms predominantly by grain boundary sliding of the soft β-phase grains, with the hard primary α-phase grains remaining in their original orientations and the measured loss in texture intensity being attributed to the loss in texture of the secondary α-phase only. Under non-superplastic conditions there is a greater contribution from plastic deformation in the β-phase which, in turn, can enhance the secondary α-phase texture.