Pearlite growth in cast irons: a review of literature data

Abstract

Following previous authors, it is considered that the decomposition of austenite to pearlite proceeds in the matrix of cast irons as it does in steels. The main features related to the nucleation and growth of pearlite in steels are thus first summarized. As most cast irons are Fe-C-Si alloys, the available studies on pearlite growth in Fe-C-Si steels are of first concern and are then reviewed in further detail. Emphasis is placed on the fact that growth of pearlite in Fe-C-Si alloys is controlled by silicon partitioning between ferrite and cementite in the temperature range of interest for cast irons. A semi-empirical relationship is suggested which describes approximately the scarce data on pearlite growth rates in Fe-C-Si steels. Finally, it is proposed that the growth rate of pearlite in cast iron with low levels of alloying elements (with the possible exception of Mo and Cr), should also be controlled by silicon partitioning and could thus be estimated with the same growth law. This hypothesis is supported by analysis of literature data on the effect of alloying on pearlite growth in cast irons with various additions of substitutional solutes.

Keywords:

• pearlite reaction
• Fe-C-X alloys
• cast irons