ESCAPE OF CARBON FROM FERRITE PLATES IN AUSTENITE

A newly developed computer program for the simulation of diffusional transformations has been applied to study the escape of carbon from a plate of ferrite assuming that the plate initially formed by a partitionless reaction from an Fe-C austenite. Thereafter the ferrite austenite interface was assumed to be immobile and local equilibrium was assumed for carbon but not for iron. The process first follows a parabolic rate law and is there controlled by the rate of diffusion in ferrite. Later stages are not parabolic and are controlled by the diffusivity in austenite. Its concentration dependence was taken into account. It was found that the rate could be estimated analytically using the maximum value rather than the average value.