Finite Element Simulation of Ausforming of Austempered Ductile Iron Components

The mechanical properties of ductile iron can be improved by ausforming, that is, applying work during austempering. The resulting yield strength and ductility are comparable to those of SAE 4140 steel, while the density is approximately 10 percent less. The viability of manufacturing components by casting a preform, austenitizing it, quenching it to the austempering temperature, forging it, austempering it, and finally, quenching it to the net shape is investigated by simulating the forging operation with finite element analysis. The preform geometry and die set geometry are determined such that the forging operation imparts a reasonably uniform equivalent plastic strain of 20 percent to the workpiece and the prescribed final component geometry is obtained. Forging of two components of varying geometric complexity is simulated using a commercial software package. The results indicate that the geometry of the final part is reasonably close to the goal and that the equivalent plastic strain distribution is reasonably uniform—over 80 percent of the material was plastically deformed 15–25 percent. The design of the preform and die sets appears to be an excellent application for an optimization algorithm.