Physically-based constitutive modelling of hot deformation behavior in a LDX 2101 duplex stainless steel

A detailed understanding of the hot deformation and work hardening behavior of LDX 2101 dual phase steel has been obtained through a wide range of hot compression tests with strain rates from 0.01 to 50 s(-1) and temperatures from 900 to 1250 degrees C. In most of the cases, the material showed typical dynamic recrystallization (DRX) behavior i.e., a peak followed by a gradual decrease to a steady state stress. The work hardening rate showed a two stage behavior i.e., a transient sharp drop at low stress values followed by a gradual decrease at higher stresses. Using the work hardening rate behavior at the latter stage, the saturation stress was calculated for different hot working conditions. Regression methods were used to develop a hyperbolic-sine equation linking the saturated stress to the deformation conditions. A physically-based Estrin-Mecking (EM) constitutive equation was then employed to model the flow behavior in the work hardening (WH)-dynamic recovery (DRV) regime. Finally, the Avrami equation to describe the evolution of the softening fraction was coupled to the EM model to extend the model to the dynamic recrystallization region. The results show that the model which is based on the stress-strain and work hardening behavior accurately predicts the flow behavior of this microstructurally complex steel. (C) 2016 Elsevier Ltd. All rights reserved.