Static recrystallization of warm-rolled pure Ti influenced by microstructural inhomogeneity

The recrystallization characteristics of commercially pure titanium (CP-Ti) rolled at various temperatures between 25 and 600 degrees C was investigated. Increasing the rolling temperature up to 450 degrees C enhanced the progress of recrystallization and refined the grain structure in the as-recrystallized state, although it reduced the overall stored energy in the as-rolled state. This peculiar phenomenon was attributed to characteristic features of the microstructure that developed during warm rolling, such as deformation-induced high-angle grain boundaries and steep in-grain orientation gradients. These microstructural inhomogencities, which originate from diverse slip systems - pyramidal < c + a > in addition to the main prism < a > - activated at the working temperature, are expected to promote the subsequent nucleation of recrystallization. It is proposed, therefore, that the rate of static recrystallization will accelerate when the factor of the microstructural inhomogeneity outbalances that of the stored energy that is reduced by dynamic recovery. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.