1 New Developments in FEM Based Process Simulation to Predict and Eliminate Material Failure in Cold Extrusion

The use of ductile materials in metal forming is limited by the occurrence of material failure due to cracking (internal or external). To characterize the behavior of the material and predict material failure, it is necessary to determine its flow stress and critical damage value (CDV).This paper deals with the prediction and elimination of defects such as chevron cracks (or central burst defects) during the cold forward extrusion process using Finite Element (FE) based process simulation techniques. Two major approaches are proposed in predicting ductile fracture: a) macroscopic modeling approach and b) constitutive modeling approach. In this paper, brief insights into the integral damage model and the Model of Effective Stress (MES) model are made and some case studies have been discussed.