Kinetics of the Austenite-to-Ferrite Phase Transformation – Simulations and Experiments

Sharp as well as thick interface models have been developed to describe austenite-to-ferrite transformation kinetics. By comparing the results of these models it turns out that the diffusion processes in the interface can be described by an effective mobility, which is several orders of magnitude smaller than the intrinsic one. For a sufficiently low amount of substitutional solutes the interface velocity is not influenced by bulk diffusion of substitutional components. This work confirms that diffusion processes in the interface (solute drag) and diffusion of interstitial components like carbon control the kinetics of the austenite-to-ferrite transformation in low-alloyed steels. As an example the austenite-to-ferrite transformation kinetics for a dual phase steel grade is simulated. The models are compared with and verified by the results of experimental investigations.