Modelling the austenite to ferrite phase transformation in low carbon steels in terms of the interface mobility

The kinetics of the phase transformation between the high temperature FCC-p hase austenite and the low temperature BCC-phase ferrite as it occurs durin g controlled cooling of hot roiled low carbon steels is described using a p hysical model that considers austenite grain size, nucleus density, composi tion effects, and the austenite/ferrite interface mobility. The model is ve rified against experimental dilatometry data for three lean carbon-manganes e steel grades. The model yields adequate reproductions of the transformati on kinetics. Ferrite grain coarsening during the transformation appears to have a significant effect on the final microstructure.