AbstractThe kinetics of the equiaxed ferrite massive transformation in Fe and Fe alloys has been examined theoretically. The basis of the analysis is that the plateau temperature in a plot of transformation temperature versus cooling rate corresponds to the maximum rate of transformation. An approximate approach for the geometry of grain corner and grain edge nuclei having one or more coherent interfaces has been used. Neither Russell's treatment of incubation periods nor Cahn's analysis of overall reaction involving nucleation and growth predict the observed transformation plateaux temperatures. Instead, calculations assuming that growth kinetics is the rate controlling factor give good agreement for the plateaux temperatures in Fe, Fe–Ni, and Fe–Cr alloys. The theoretical calculations also show the existence of a plateau within±10 K over a range of cooling rates. The marked hardenability of Fe–Ni alloys is also discussed.MST/1393