Modelling simultaneous alloy carbide sequence in power plant steels

Abstract

A method has recently been developed to estimate the speed with which precipitation reactions occur in power plant steels. It is based on Avrami theory but with an adaptation that allows the treatment of simultaneous reactions. In the present work, a number of approximations and inconsistencies in the theory have been eliminated and this kinetic theory for simultaneous reactions has been modified with the treatments of both diffusion-controlled growth and capillarity effect in multicomponent systems. The modified model can predict not only volume fraction changes of each carbide but also particle sizes. New experimental results on alloy carbide in 3Cr1.5Mo and 2 1/4Cr1Mo steels are reported and shown to be comparable to the modified theory.