Investigation on hot deformation behavior of 12Cr2Mo1V steel using a combination of Hansel-Spittel constitutive model and finite element simulation

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Isothermal hot compression experiments were conducted on 12Cr2Mo1V steel to investigate the hot deformation behavior at the temperature range of 900–1200 °C and the strain rate range of 0.01–5 s −1 by using a Gleeble-1500D thermo-mechanical simulator. Microstructural evolution was characterized using optical microscope, electron backscatter diffraction, and transmission electron microscope analysis. Results demonstrate that increasing temperature and decreasing strain rate generally promote dynamic recrystallization (DRX) while reducing geometrically necessary dislocation (GND) densities. However, at 1200 °C with a constant strain rate of 0.1 s −1 , as well as at 1150 °C with strain rates of 0.1−0.01 s −1 , GND densities exhibited an anomalous increase due to the formation of subgrains evolved from dislocation cells. According to the measured true stress-strain data, the hot processing maps were constructed, identifying the optimal workability window at 1170−1200 °C and 0.01−0.1 s −1 . The constitutive model was constructed based on Hansel-Spittel model and incorporated into FORGE® software to perform the finite element simulations on the hot deformation process of 12Cr2Mo1V steel. The predicted force-displacement curve results agree well with the measured curves, verifying the dependability of the Hansel-Spittel constitutive model for describing the rheological behavior of 12Cr2Mo1V steel during hot compression. With the increase of temperature, the variation of equivalent strain within the sample reduced, which is beneficial to obtain homogenous microstructure.