Investigations on the Use of Damage Indicating Criteria in FE Simulations of Cold and Semi-Hot Bulk Forging Operations

Abstract

Bulk forging operations play an important role in metal forming. A wide range of applications is possible from some ounces to several tons of steel in a high diversity of shapes. However economical constraints demand for further optimisation and cost-effective production. One severe problem arising not only in bulk forging is the susceptibility of steels to ductile damage during the production process. In case it reaches macroscopic proportions the workpiece might be destroyed. Otherwise it inhibits a potential threat to safety and lifetime of the product. Recent research concentrated on cold forging processes as their share in the market clearly outweighs semi-hot or hot forging. Nevertheless semi-hot forging processes are prone to ductile damage as well. It is the intention of this paper to propose the damage indicating Model of Effective Stresses by Lemaitre for an application in the design of bulk forging operations. The model is identified from several different approaches and verified by combined experiments and finite element simulations. Last an application to exemplary cold and semi-hot forging operations will show the suitability of this approach.