Hot deformation modelling for a medium carbon vanadium micro alloyed steels

Although the grain refinement promoted by microalloying addition together with the controlled rolling is well known and established in industrial scale in low alloy steels, the same is not so well determined in medium carbon steels. In this work, the mechanical behaviour at elevated temperature of a medium carbon microalloyed vanadium steel was studied. Continuous stress-strain curves were determined by hot torsion tests carried out at the temperature range from 850 deg C to 1150 deg C and strain rate from 0.5 to 5 s-1. The work hardening stage was analyzed plotting the derived of the stress-strain curves versus the applied stress and the softening region fitting experimental data to Avrami equation. Also, it was observed that the activation energy for tis kind of steel is 340 kJ/mol. From multiple passes with continuous cooling it was determined the no-recrystallization temperature, 830 deg C, that separates the work range in two distinct regions. Above occurs total recrystallization between passes and below only partial one. (author)