Development of forging process design to close internal voids

In this study, the closing behavior of internal voids was examined by a deformation analysis involving the 2-D finite element method (FEM), which simulates voids in steel ingots in the compression process (upset process). In the compression process, a model experiment that uses internal voids was carried out to confirm the accuracy of the deformation analysis. By comparing the model experiment with the analytical results, it was confirmed to simulate the internal void behavior by this analysis. The relationship between the reduction ratio and the void shape/void position was investigated by the analysis. In the forging process, the closing evaluation value of internal voids (Q value) was calculated by a model experiment and 3-D FEM. Using the analysis results, a limit value of the closing behavior of voids was quantified, and it is now understood that the voids close at more than Q = 0.21. In addition, the forging process of filling the above-mentioned value was designed by the Taguchi method. The predicted Q value in the case of using the Taguchi method almost corresponds to the value calculated by the deformation analysis. It was clarified that the process is capable of being designed simply.