Exploring the correlation between the austenite yield strength and the bainite lath thickness

Abstract

The shape deformation associated with the formation of a bainite lath requires plastic accommodation in the neighboring austenite, and therefore it is assumed that the austenite yield strength will have a strong effect on the dimensions of the formed lath. Experimental data of the bainite lath thickness and the austenite yield strength have been examined to investigate this assumed dependency. First an equation is proposed to describe the austenite yield strength as a function of composition, grain size and temperature. This model has been validated with data of TWIP steels and medium carbon steels while also maintaining consistency with Irvine's original equation for austenitic stainless steels. Subsequently it is demonstrated that experimental data of the bainite lath thickness reported for various high-Si steels have an approximate inverse dependence with the austenite yield strength. On the basis of this correlation a concise model is proposed that can predict the bainite lath thickness as a function of composition, austenite grain size and temperature. Such a tool can be useful for alloy design in the development of new steels.