Plastic Deformation Behavior and Processing Maps of 35CrMo Steel

Abstract

Hot deformation behavior of 35CrMo steel was investigated by compression tests in the temperature range of 850 to 1150 °C and strain rate range of 0.01 to 20 s−1 on a Gleeble-3810 thermal simulator. According to processing maps constructed based on the experimental data and using the principle of dynamic materials modeling (DMM), when the strain is 0.8, three safe regions with comparatively high efficiency of power dissipation were identified: (850 to 920) °C/(0.01 to 0.02) s−1, (850 to 900) °C/(10 to 20) s−1, and (1050 to 1150) °C/(0.01 to 1) s−1. And the domain of (920 to 1150) °C/(2.7 to 20) s−1 is within the instability range, whose efficiency of power dissipation is around 0.05. The deformed optical microstructure indicated that the combination of low deformation temperature (850 °C) and a relatively high strain rate (20 s−1) resulted in the smallest dynamic recrystallized grains, but coarser grains were obtained when a much higher strain rate was employed (50 s−1). A lower strain rate or a higher temperature will accelerate the growth of grains, and both high temperature and high strain rate can cause microcracks in the deformed steel. Integration of the processing map into the optical microstructure identified the region of (850 to 900) °C/(10 to 20) s−1 as the ideal condition for the hot deformation of 35CrMo steel.