20th International Forgemasters Meeting - IFM 2017

A　forging pass schedule affects a closing behavior of internal void in ingots. To evaluate a void consolidation behavior, the parameter Q-value, which is calculated from the hydrostatic stress and the equivalent strain, is reasonable. The recent progress of forging simulation technology makes Q-value calculation easier. A forging pass schedule has been decided by forging ratio. It only depends on the first/last cross-sectional area of the forging product, so a void consolidation behavior changes depending on other forging conditions (e.g. shape of forging tools, reduction ratio, deformation resistance of material) even though the forging ratio is same. These conditions were decided empirically. In some cases, low productivity conditions were decided to prevent internal void defect. To deal with productivity and internal quality at the same time, an optimum forging pass schedule was designed with calculating Q-value under the capacity of press machine. Moreover, trial manufacturing with designed forging pass schedule was conducted. Detected maximum UT defect size was φ2mm (MDDS：φ1.8mm）and it was showed that this pass schedule provide enough void consolidation effect. Also, the productivity was improved 7%. It is confirmed that a useful forging pass schedule could be determined for actual forging. For the future, to use Q-value more readily (without calculating in each case), the formulation between Q-value and forging conditions is carried forward.