Phase transformations in two C-Mn-Si-Cr dual phase steels

Abstract

The continuous cooling transformation behaviour of dual phase steels were studied with emphasis on the effects of addition of chromium, cooling rate and intercritical annealing temperature on the volume fractions of different transformed products of austenite. The results show that addition of 0.21 % chromium promotes the formation of acicular products in the final microstructure and does not have much effect on the volume fractions of the co-existing phases at intercritical annealing temperatures. A mathematical model based on Avrami's equation and Scheil's additivity principle was developed to predict the volume fractions of polygonal ferrite as a function of cooling rate for one of the continuous cooled steels. The predicted results from the model show good agreement with experimental observations. © 2006 ISIJ.