Constitutive relationship of hot deformation of X80 pipeline steel

In order to realize numerical simulation of hot rolling and establish the hot deformation process parameters for X80 pipeline steel, the flow stress behavior of X80 pipeline steel during hot deformation was investigated in the temperature range of 900-1100°C and strain rate of 0.01-1s^-1 on Gleeble-3500 thermo-simulation machine. The results show that dynamic recover and dynamic recrystallization occur during hot deformation. As the deformation temperature increase and strain rate decrease, dynamic recrystallization critical strain and peak stress decrease, and softening caused by dynamic recrystallization is obvious. According to analyzing and calculating the data of thermo-simulation, the dynamic recrystallization activation energy and flow stress equation were set up. Finally, the error analysis of flow stress equation proved that the equation had good accuracy.