Influence of Anvil Shape of Surface Crack Generation in Large Hot Forging Process

In hot free forging process of large products, surface cracks occur occasionally. When these cracks occur, they must be removed by hot scarfing process after stopping forging process temporarily. Final products have no cracks on those surfaces after applying the hot scarfing process. Hot scarfing process, however, cuts into productivity due to additional time consuming. Since surface cracks are regarded as significant defects, suppression of the surface crack generation is important issue. A lot of research has been studied about mechanism and criteria of forging crack generation [1]∼[8]. In hot forging process, however, there are a few researches [9]∼[14]. Then the mechanism and criteria of crack generation during the hot forging process are not clear at this moment. There are various factors for crack generation, such as reduction ratio, forging temperature, anvil shape, ingot surface integrity and so on. The goal of this research is to clarify the mechanism of crack generation in actual forging processes. The derived mechanism is applied to design anvil shapes by using numerical forging simulation.