1992 Volume 78 Issue 5 Pages 790-797
The isothermal precipitation behavior of Nb(C, N) in austenite has been investigated using steels of different carbon contents. The observed progress of the precipitation in extra low carbon steel ismuch faster and size of the precipitates is apparently larger than those in steels with higher carbon content even though their supersaturations are the same. To explain this phenomenon, the local equilibrium at the austenite/Nb( C, N) interface has been introduced into the classical nucleation theory and the spherical growth theory, and a generalized precipitation model has been proposed which can predict the precipitation behavior of extra low carbon steels as well as that of HSLA steels. As a conclusion, this study clealy shows that the kinetics of MC-type precipitation is influenced not only by the precipitate-forming atomic product, M·C, but also by its ratio, M/C.
