2007 Volume 47 Issue 8 Pages 1188-1194
The kinetics of ferrite nucleation inside an austenite grain under strong super cooling conditions are proposed by considering dislocation lines as nucleation sites based on cluster dynamics. The elastic energies within spherical space, cylindrical space and ellipsoidal space on a dislocation line have been studied, and are recognized to be approximately proportional to the cluster radius. By applying the conventional nucleation and grain growth theory on the dislocation line, the free energy change induced by a new ferrite nuclear generation on the dislocation line has been evaluated, and the ferrite nucleation rate has been formulated by considering the deformation elastic energy. According to the proposed inner-grain nucleation theory, the ferrite nucleation phenomenon inside austenite grain can be evaluated mathematically with strong super cooling conditions.
