A dislocation based material model for warm forming simulation

Abstract

Based on experimental results, a dislocation material model describing the influence of dynamic strain aging on the deformation behavior at elevated temperatures is presented. One and two stage loading tests at different temperatures were performed in order to describe the hardening behavior during the deformation at elevated temperatures as well as the hardening behavior after the dynamic strain aging process. Bergström's theory of work hardening was used as a basis for the model development. In the proposed model a relationship between material coefficients of the classical Bergström model and temperature was investigated. The aim of the new material model was to introduce the least possible amount of new parameters as well as to facilitate the mathematical determination of parameters during the fitting of the model with the experimental data. The developed model was implemented in an in-house FE-Code in order to simulate the material behavior due to the dynamic strain aging. Representative simulation results were compared with the experimental data in order to validate the efficiency and the application range of the model. Simulation of the forming process provided data for optimizing strength properties and enabled process control.