A Microstructurally Based Model for Recrystallization in Dual-Phase Steels

Adjusting and predicting the ferrite recrystallization kinetics of cold-rolled Advanced High-Strength Steels during annealing is necessary to control their final microstructure and thus their mechanical properties. This study proposes a microstructurally based model for predicting the recrystallization kinetics of Dual-Phase steels that takes into account the effect of several physical parameters (chemical composition, temperature, cold rolling reduction ratio, and precipitation state). First, ternary Fe-C-Mn grades were used to validate the parameters of the model relative to the Mn content and to the reduction ratio. Second, the effect of other alloying elements (Si, Cr, Mo) was analyzed using recrystallization kinetics from the literature, before testing the model on two industrial Dual-Phase grades: a DP600 steel and a micro-alloyed DP1000 steel. The effect of the micro-alloyed elements (Nb,Ti) either in solid solution or as precipitates was detailed. Lastly, the model was used to build interaction maps between recrystallization and austenite formation during continuous heating with different heating rates.