Prediction Model for the Austenite Grain Size in the Coarse Grained Heat Affected Zone of Fe-C-Mn Steels: Considering the Effect of Initial Grain Size on Isothermal Growth Behavior

Abstract

The austenite grain size in the coarse-grained heat affected zone (CGHAZ) was predicted by analyzing isothermal grain growth behavior of Fe-C-Mn steels which were designed to investigate the effect of alloying elements. A procedure was proposed to prevent inappropriate neglect of initial grain size (D₀) and misreading both time exponent and activation energy for isothermal grain growth. It was found that the time exponent was almost constant, irrespectively of temperature and alloying elements, and activation energy increased with the addition of alloying elements. From quantification of the effect of alloying elements on the activation energy, an isothermal grain growth model was presented. Combining with the additivity rule, the austenite grain size in the CGHAZ was predicted.