Abstract
The ferrite nucleation model based on a classical nucleation theory for a rectangular TiN was derived to clarify its nucleation potency. The calculation revealed that a ferrite nucleates most easily on the facets of TiN rather than on its edges, corners, and austenite grain boundary and also indicated that the minimum size of TiN exists being influenced by the chemical driving force. These theoretical findings were confirmed experimentally for the TiN precipitate in low C-steel. The minimum size of TiN which has the potency of a ferrite nucleation was experimentally determined for various chemical driving force conditions by measuring the maximum size distribution of TiN which existed in the not transformed austenite at transformation temperature. These values showed a good agreement with the calculated ones.
