Application of a Forming Limit Concept to the Design of Powder Preforms for Forging

The soundness of the metallurgical structure and the associated strength of a forged powder preform material increase with increasing lateral flow during the forging process. Unconstrained lateral flow, however, enhances the possibility of fracture during deformation. In this paper, a preform design technique is presented that provides the preform shape and dimensions for forging a part to full density with a sound metallurgical structure but without fracture. The basis of the approach is a forming limit concept developed previously for cold forming processes. Application of the technique is demonstrated through design of the preform for forging a pulley blank consisting of a flange, rim and hub.