Mathematical modelling of mean flow stress during the hot strip rolling of multiply-alloyed medium carbon steels

The kinetics of static, dynamic and metadynamic recrystallization applicable to a Cr-Mo-V-Ni-Nb steel were determined by means of torsion testing. A mathematical model for the flow stress was then drawn up based on the Misaka equation, but which incorporates the effects of dynamic, metadynamic, and static recrystallization. In this way, it takes both the accumulated strain as well as microstructural evolution into account. In addition, mill log data obtained from the Wakayama Steel Works of Sumitomo Metal industries were converted into mean flow stresses (MFS's) using the Sims approach. The operating data obtained in this way are compared with the predictions of the model, and excellent agreement is obtained between the measured and predicted MFS values over the whole range of rolling temperatures and conditions. The predictions indicate that dynamic, followed by metadynamic, recrystallization lakes place during finish rolling of this grade.