Comparison of Two Physical Simulation Tests to Determine the No-Recrystallization Temperature in Hot Rolled Steel Plates
Abstract
Two rolling simulations were conducted using a Gleeble 3500 to determine the no-recrystallization temperature, TNR on six microalloyed plate steels. Double hit deformation tests and multistep torsion tests were performed on steels containing varying amounts of Nb, V, and Ti. TNR for the double hit deformation tests were determined by finding fractional softening using the 5 % true-strain method and the intersection of the sigmoidal fractional softening curve with 20 % fractional softening. TNR for the multistep hot torsion test were determined using a mean flow stress method and finding the intersection of the two linear regions. TNR values following multistep hot torsion testing were lower than values measured after double hit deformation testing. The decrease in measured TNR values for the torsion tests occurs from the inherent multiple deformations, resulting in refined grains and an increase in nucleation sites for recrystallization during the subsequent deformation steps; thus recrystallization can continue to occur at lower temperatures.