Constitutive modeling for flow behavior of GCr15 steel under hot compression experiments

The thermal compressive deformation behavior of GCr15 (AISI-52100), one of the most commonly used bearing steels, was studied on the Gleeble-3500 thermo-simulation system at temperature range of 950-1150 degrees C and strain rate range of 0.1-10 s(-1). According to the experimental results, the stress level decreases with increasing deformation temperature and decreasing strain rate. The peak stresses on the true stress-strain curves suggest that the dynamic softening of GCr15 steel occurs during hot compression tests. To formulate the thermoplastic constitutive equation of GCr15 steel, Arrhenius equation and the Zener-Hollomon parameter in an exponent-type equation were utilized in this paper. In addition, a modified Zener-Hollomon parameter considering the compensation of strain rate during hot compression was employed to improve the prediction accuracy of the developed constitutive equation. Analysis results indicate that the flow stress values predicted by the proposed constitutive model agree well with the experimental values, which confirms the accuracy and reliability of the developed constitutive equation of GCr15 steel. (C) 2012 Elsevier Ltd. All rights reserved.