Effect of Strain on Hot Deformation Behavior and 3-D Processing Maps of a Vanadium and Titanium Microalloyed Steel

The hot deformation behavior of a V-Ti microalloyed steel was studied via hot compression testing at the deformation temperature of 900-1050 °C, strain rate of 0.005-10 s-1 and strain of 0.4, 0.6 and 0.8. The constitutive equations under different strain were established to characterize the effects of strain on the hot deformation behavior, hot processing maps and microstructure evolution. When the strain increased from 0.4 to 0.8, the activation energy of the V-Ti microalloyed steel decreased from 515.61 to 347.48 kJ/mol, which was different from the theoretical strain. Considering the influence of strain, an accurate flow stress model was established. The 3-D power consumption maps based on theoretical values and actual values have the same trend, but there is a large difference in the η-value; the 3-D instability maps have the same change trend under different strains. The optimum deformation parameters for the V-Ti microalloyed steel were determined using the 3-D processing maps and microstructure evolution.