Modelling of transformation kinetics in HSLA 100 steel during continuous cooling

Abstract

Generalised Johnson and Mehl and Avrami type kinetic reaction rate equations were applied to analyse the transformation behavior of HSLA-100 steel during continuous cooling. Analysis of the dilatometric data for various cooling rates yielded the time exponent constant n and the activation energy Q. Using these 2 contents, it was possible to determine the amount and the transformation temperature of austenite to acicular ferrite and bainite and fraction transformed. Detailed analysis of cooling curves yielded a correlation between the transformation mode and the constants in the Avarami equation. Using these 2 constants only, it was shown that the entire CCT diagram for HSLA steels could be predicted. The results are in good agreement with the experimental value.