Investigation of void closure in open-die forging considering changing load directions

Abstract

Ingots from casting processes usually contain defects such as voids from solidification. These voids can lead to failure during application, e.g., crack formation. Accordingly, it is important to close these voids in the forging process. Predicting the closure and healing of voids during forging has been the subject of numerous studies, most of which assume a constant loading direction. As multiple-pass open-die forging processes usually include workpiece rotations, in this study, an existing criterion found in the literature for the prediction of void closure is extended to consider changing loading directions. For model validation, an AISI 4140 ingot with artificial voids is forged, and the void volume is investigated by radiographic analysis. The results confirm the improvement in the model prediction provided by the proposed extension.