Characterization of dynamic recrystallization behavior of low carbon steel under flexible rolling process

Abstract

The uplifting process of the flexible rolling causes different deformations at different positions of the rolled strip, which will affect the microstructure and dynamic recrystallization behavior of the material under the coupling effect of contact heat transfer and plastic deformation. The equivalent substitution method and the Gleeble-3800 thermal simulation experimental machine were used to study the effect of dynamic recrystallization behavior of a low carbon steel in the flexible rolling process at a temperature of 900–1100 °C, a strain rate of 0.01–10 s−1, and strains in the range 0.2–1.2. Firstly, the critical condition of dynamic recrystallization was determined by analyzing the flow stress curve at high temperature, and the Zener-Hollomon equation under the coupling interaction of stress, strain rate, and temperature was established. Secondly, the method of solving the dynamic recovery coefficient r is optimized, and the dynamic recrystallization volume fraction model is established based on the optimized model, and the experimental value is compared with the predicted value. Finally, the microstructure of the experimental steel was analyzed. Through the equivalent substitution method, it can be concluded that as the roll uplifting reduces the reduction of the strip during the flexible rolling process, the number of dynamically recrystallized grains decreases with the decrease of deformation degree.