Mixed-mode model for ferrite-to-austenite phase transformation in dual-phase steel

A mixed-mode model is proposed to predict the austenite formation during intercritical annealing of a low-carbon steel with ferrite-cementite microstructure. The transformation kinetics is decribed by carbon diffusion in combination with an interface mobility, representative of complex phenomena slowing down the transformation rate (solute drag, slow diffusivity of other alloying elements, cementite dissolution). The model approach is formulated to be relevant for complex chemistries typical of industrial steels. Model predictions have been successfully benchmarked with experimental data including heating and holding stages at various heating rates and holding temperatures.