Aspects of the nucleation of Widmanstätten ferrite

Abstract

Published experimental data on the variation of the highest temperature at which Widmanstätten ferrite can be seen to form at a detectable rate, as a function of steel composition, are analysed theoretically. It is found that the data can be predicted to a fair accuracy if it is assumed that the nucleation of Widmanstätten ferrite occurs by a mechanism which is similar to that of martensite, but with the diffusion of carbon during nucleation, and if it is additionally assumed that the growth of Widmanstätten ferrite can only be sustained when the chemical driving force exceeds a specific stored energy term.