Identification of Parameters in the History Dependent Constitutive Model for Steels

Abstract

The problem of an influence of history of deformation on material behaviour during hot forming of steels is discussed in the paper. The method of description of the yield stress, which accounts for a strain path, is presented. This approach is based on an internal variable method and it uses dislocation density for a description of the state of the material. Identification of the material parameters in this model is the main difficulty, which prevents its practical application. Therefore, an inverse analysis combined with the experimental data is used in this work for an identification of these unknown parameters. The experiment composed axisymmetric hot compression performed at various temperatures and at various strain rates on the Gleeble 3800 simulator. After identification the flow stress model was implemented into the finite element program and simulations of various hot forming processes were performed.