| Abstract: | The hot deformation behavior of an ultralow-carbon microalloyed steel was investigated using an MMS-200 thermal simulation test machine in a temperature range of 1 073-1 373 K and strain rate range of 0.01-10 s~(-1).The results show that the flow stress decreases with increasing deformation temperature or decreasing strain rate.The strain-compensated constitutive model based on the Arrhenius equation for this steel was established using the true stress-strain data obtained from a hot compression test.Furthermore,a new constitutive model based on the Z-parameter was proposed for this steel.The predictive ability of two constitutive models was compared with statistical measures.The results indicate the new constitutive model based on the Z-parameter can more accurately predict the flow stress of an ultralow-carbon microalloyed steel during hot deformation.The dynamic recrystallization (DRX) nucleation mechanism at different deformation temperatures was observed and analyzed by transmission electron microscopy (TEM),and strain-induced grain boundary migration was observed at 1 373 K/0.01 s~(-1). |
