A Review of Grain Evolution Effect on Accommodation Mechanism, Modeling, and Processing of Superplastic Titanium Alloys

Abstract

The objective of this overview is to elucidate the grain evolution mechanism during the superplastic deformation and manufacturing process. Particular emphasis is placed on the accommodation mechanisms of grain boundary sliding; however, the mechanism of grain rotation has been significantly underestimated. Furthermore, the differing grain refinement mechanisms in superplastic (region II) and near-superplastic (regions II/III to III) conditions may lead to variations in grain size evolution and fracture mechanisms. On the other hand, the grain growth during low-temperature superplastic forming is also influenced by the thermal stability of fine grains, continuous severe plastic deformation processes, and non-uniform grain distribution. This work will guide future research on superplastic deformation mechanisms and grain evolution control in the field of low-temperature superplasticity.