Texture and microtexture variations in a near-α titanium forged disk of bimodal microstructure

Quasi-alpha titanium billets often contain macrozones, i.e. large regions of sharp microtexture that differ from one region to the next and are detrimental for dwell fatigue properties. We analyzed the effect of additional alpha/beta forging on the occurrence of macrozones in aerospace components. Thus the microstructures and local textures of an IMI834 disk were characterized by scanning electron microscopy and electron backscattering diffraction (EBSD) techniques. Advanced EBSD data processing was performed to distinguish alphap and alphas orientations and to calculate the prior β orientations. Pronounced variations in alphap/alphas microtextures were observed over the disk. Macrozones with characteristics similar to those observed in the billet were still present in the dead regions. However, the macrozones were progressively reduced and even suppressed when moving to regions highly deformed by compression. Finally, the mechanisms responsible for these changes in the microtexture are discussed.