A microstructure model for recrystallisation and phase transformation during the dual-phase steel annealing cycle

A three-dimensional cellular automata model is developed for the description of the relevant metallurgical mechanisms occurring in the annealing stage of dual-phase steels: ferrite recrystallisation, pearlite-to-austenite and ferrite-to-austenite transformation on heating and austenite-to-ferrite transformation on cooling. Based on the local grain-boundary and interface velocity, the latter controlled by both interface mobility and carbon diffusivity, the model is able to simulate the microstructure development throughout the annealing stage. The model also provides information on the carbon gradient in austenite at the end of the cycle, which is relevant for the prediction of martensite formation during the subsequent quenching. The simulated structure thus provides a realistic representation of many microstructural aspects.