Effect of Cold Reduction Rate on Ferrite Recrystallization Behavior during Annealing in Low-Carbon Steel with Different Initial Microstructures

Abstract

We investigate the effect of the cold reduction rate on ferrite recrystallization behavior during the annealing of low-carbon steel with different initial microstructures. Three types of hot-rolled sheet specimens are prepared: specimens P, B, and M, which consist of ferrite and pearlite, bainite, and martensite, respectively. To evaluate the effect of the cold reduction rate on ferrite recrystallization behavior, hot-rolled sheet specimens are cold-rolled at cold reduction rates of 40% and 67%. The cold-rolled sheet specimens are heated to the target temperature, and then water-quenched to room temperature. Irrespective of the initial microstructures, the ferrite recrystallization is accelerated by increasing the cold reduction rate. In addition, the dislocation densities of specimens P and B increase at the larger cold reduction rate, which accelerates ferrite recrystallization in these specimens. In the case of specimen M, the dislocation arrangement parameter remarkably decreases at the larger cold reduction rate, whereas the dislocation density hardly changes. Thus, we conclude that the accelerated ferrite recrystallization at the larger cold reduction rate for specimen M can be mainly attributed to an increase in the amount of interactions between dislocations in the specimen.