On the opposition of dynamic recrystallization and solute dragging in steels

The influence of chemical composition on the hot deformation behavior and dynamic recrystallization was studied by conducting hot compression tests on two low alloy steels, AISI 4135 and VCN200, over a temperatures range of 1000-1150 °C and at strain rates of 0.001 s−1 to 1 s−1. The activation energy of dynamic recrystallization in 4135 and VCN200 was determined as 374 kJ/mol and 435.3 kJ/mol, respectively. The different apparent activation energies (about 17%) were attributed to about 30% difference between the carbon equivalents of the steels. The results confirmed that the higher the alloying elements, the higher the peak stress and strain of DRX flow curves. The results were associated with the dragging force of solute atoms on the grain boundaries. A new formula was proposed as a chemical factor to quantify the influence of solute dragging on the dynamic recrystallization behavior. Simple power equations described how the peak stress and strain depends on the Zener-Hollomon parameter. The material constants of the developed equations were related to the proposed composition factor. Unlike to dynamic recrystallization, dynamic recovery did not delayed by solute dragging.