A physically based constitutive model of As-forged 34CrNiMo6 steel and processing maps for hot working

In this paper, isothermal compression tests of as-forged 34CrNiMo6 steel were carried out using a Gleeble-1500D testing machine for the deformation temperatures ranging from 1173 K to 1473 K and strain rates ranging from 0.005 s−1 to 1 s−1. Flow stress curves were obtained under the given conditions. Using regression analysis, the hyperbolic sine law Zener-Hollomon equation was established, and the hot deformation activation energy was obtained as 376.5 kJ mol−1. To predict the flow stress for hot working, a constitutive model including work hardening-dynamic recovery modeling and the corresponding Avrami-type dynamic recrystallization equation was established. The work hardening-dynamic recovery model was derived based on the evolution equation of the dislocation density and the work hardening rate. All parameters in this model can be expressed in terms of the Zener-Hollomon parameter. Our results indicated that the proposed constitutive model had high prediction accurately for hot working of as-forged 34CrNiMo6 steel. Furthermore, the optimized processing parameters for the as-forged 34CrNiMo6 alloy steel were determined based on the processing maps and microstructure.