Based on the classic diffusion controlled nucleation and growth theory, the
sympathetic nucleation-ledgewise growth mechanism of bainite was studied t
heoretically for low carbon F-e-C alloys. The rationality of the occurrence
of sympathetic nucleation on the terraces of ledges competing with lateral
ledge growth and other sites nucleation was demonstrated by the present wo
rk quantitatively. The calculations indicated that low reaction temperature
s and high carbon concentrations may favor the sympathetic nucleation, thus
accounting for the formation of multilayer structures of bainite.