Analysis of the Development of Abnormal Grains Structures During Beta Annealing of Ti-64 Wrought Products

Abstract

The ß-annealing of Titanium-6Al-4V (Ti64) wrought aerospace components can lead to the development of abnormal grain structures (AGS) that jeopardise material performance. Therefore, an in-depth understanding into the origins of AGS will help in the design of processing routes that can avoid the conditions that lead to their development. This research demonstrates the application of novel concurrent in-situ heating and electron back scatter diffraction (EBSD) techniques to help elucidate possible mechanisms for the development of AGS. It was found that primary-a (ap) may play a key role, acting as a second phase particle, in pinning the ß-phase grain boundaries during recrystallisation. The strengthening of a large area cube component texture macrozone, consisting of predominantly low angle grain boundaries, is also a prerequisite for the development of AGS.