On the origin of isotropic steady state structural superplastic deformation

Abstract

Many models are available to explain isotropic steady state structural superplastic deformation. One such proposal suggests that grain boundary sliding (GBS) that develops to a mesoscopic scale is the rate controlling process in the above mentioned range in different classes of materials with different crystal structures. The equations derived accurately describe the experimental results pertaining to many superplastic materials of different classes, crystal structures and grain sizes tested at different temperatures and strain rates. In this paper using existing experimental data available in the open literature the isotropic steady state structural superplastic deformation is predicted accurately by first evaluating the model constants using some of the existing experimental data. Using these model constants, the isotropic steady state structural superplastic deformation of some other superplastic material conditions not used for the analysis is predicted once again to high accuracy. As required by a sound theory, it is pointed out that some predictions of the physical description have already been verified experimentally by earlier findings.