Evolution of microstructure, macrotexture and microtexture during hot rolling of Ti-6Al-4V

The evolution of microstructure. macrotexture and microtexture during subtransus hot working of Ti-6Al-4V with two different types of transformed beta starting microstructures (lamellar colony, acicular/martensitic alpha) was investigated. Globularization of the transformed microstructures required heavy rolling reductions or moderate reductions coupled with near transus post-rolling heat treatment. Despite the sluggish dynamic globularization kinetics, noticeable macrotexture changes were noted after low reductions. an effect ascribed to the rotations associated with kinking and bending of the lamellar/acicular plates. Noticeable microtextures, noted in samples with an initial lamellar colony microstructure, persisted through hot rolling suggesting that dynamic globularization does not involve recrystallization. In contrast, hot rolled material with a starting acicular alpha microstructure exhibited weak microtextures and strong macrotextures. The absence of microtexture in these latter cases was explained on the basis of multiple transformation variants within each colony/prior beta grain following the beta-annealing-and-water-quenching process used to obtain the microstructure. (C) 1998 Elsevier Science S.A. All rights reserved.