Characterizations of microstructure and crystallographic orientation in a near-α titanium alloy billet

Abstract

Previous studies have found that the α+β and near-α titanium alloys often contain large regions, referred as macrozones, with sharp local texture that differs from one region to the next. In this work the characterizations of microstructure and crystallographic orientation heterogeneities were studied by optical microscopy and electron backscattered diffraction techniques in a billet of a near-α titanium alloy Ti60. It was found that a heterogeneous microstructure, both in orientation distribution and morphology, comprising remnants of α lamellae along the axis direction and equiaxed α grain was found in the longitudinal section of the billet. In the billet, a weak <11–20>//AD fiber texture component was found, and this texture component was related to the special deformation mode for the billet and recrystallization texture in hexagonal close-packed metals. The deformation was mainly supported by prismatic <a> slip in the α phase during forging according to in-grain misorientation axis analysis, while many subgrains/grains with low-angle boundaries were found within an apparent α grain under EBSD observation.