No abstract

The stability of retained austenite refers to its resistance to transform into martensite. While most models describe the thermal and mechanical influence on retained austenite stability and transformation kinetics separately, few have considered explaining both aspects in a unified model. Here, we review the factors governing austenite stability and transformation kinetics, together with models which predict these properties. By assessing the predictive capabilities of models using experimental data, several parameters have been identified as crucial in describing transformation behaviour. We anticipate that this review will stimulate further research in developing physics-based models that could improve the understanding of austenite stability and transformation.

The transformation behaviour of retained austenite in steels is known to differ according to chemical composition and other microstructural attributes. Earlier research indicated that austenite in high-carbon steels transforms into martensite only when the applied stress exceeds a critical value, contrary to low-carbon steels where transformation occurs in the early stages of deformation. Although transformation models have been proposed, most are optimised for low-carbon steels. Here, we propose physics-based models applied to high-carbon steels to overcome previous limitations. The models have fewer free parameters (4) compared to previous approaches (6), exhibiting improvements in the numerical and physical interpretation of the austenite transformation process. We envision the use of these models as tools for alloy design, also highlighting their scientific and technological value.