Kinetics of Structure Formation in the Heating of Cold-Rolled Automotive Steel Sheet

The softening kinetics associated with recovery and recrystallization is investigated, along with the kinetics of phase transformation (austenitization) on heating cold-rolled autompotive steel sheet. The kinetics of softening in isothermal holding is studied using the Gleeble 3800 system for 12 steels, and the phase transformation in continuous heating at constantrate is studied for 6 steels of different strength class, with different chemical composition. Considerable slowing of the steel’s recovery and recrystallization is observed with increase in the Mn and Ti content in the ferrite solid solution. The grain size of the recrystallized ferrite hardly depends on the annealing temperature. The results may be used in developing a quantitative integral model to describe the complex microstructural evolution of cold-rolled steel sheet on annealing in industrial production.