In this study, the 3D-FEM (finite element method) code “DEFORM 3D” was applied to the simulation of RR forging. RR stands for the initials of Mr. Roederer (President of Cresot-Loire Ltd.) and Mr. Ruget (the inventor). To estimate the deformation and load accurately, analytical conditions such as the strain rate and temperature dependency of flow stress, the temperature distribution of the material and volume decrement caused by the oxidation scale were taken into consideration. As a result, it was found that numerical results such as the shape of arms and the positions of flash and underfill showed a good agreement with those measured. Moreover, using this method, we built and verified an empirical equation for predicting the maximum forging load by estimating the effect of the restraint depending on each die's mode. Using this equation, the optimum forging shape was designed and used in the actual forging process. By this new designed process, successful yields have been obtained.
