New phenomenological and differential model for hot working of metallic polycrystalline materials

This paper presents a new phenomenological and differential model (that use differential equations) to predict the flow stress of a metallic polycrystalline material under hot working. The model, called MCC, depends on six parameters and uses two internal variables to consider the strain hardening, dynamic recovery and dynamic recrystallization processes that occur under hot working. The experimental validation of the MCC model has been carried out by means of stress-strain curves from torsion tests at high temperature (900 degree centigrade a 1200 degree centigrade) and moderate high strain rate (0.005 s-1 to 5 s-1) in a high nitrogen steel. The results reveal the very good agreement between experimental and predicted stresses. Furthermore, the Garofalo a-parameter and the strain to reach 50 % of recrystallized volume fraction have been employed as a control check being a first step to the physical interpretation of variables and parameters of the MCC model. (Author) 26 refs.