Avrami theory for transformations from non-uniform austenite grain structures

Abstract

Classical overall transformation kinetics theory for grain boundary nucleated transformations relies on the assumption that the parent phase grain size is uniform. In the present work the theory is adapted to deal with the case where there is a distribution in the size of the parent grains, as is often found in practice. It is demonstrated that the overall transformation rate is fastest when the starting grain structure is uniform. The method has been applied to the formation of allotriomorphic ferrite in austenite and the results have been compared against published experimental data.