Research Of Early Failure Mechanism Of Clad Metal Mould Chrome Grinding Ball

Along with development of heavy industry, millions of tons wearing products used in metallurgy and mining department to break and mill, such as grinding balls and lining boards, is consumed annually, and the consumption is increased year after year. While among numerous wear resistant materials, chrome-based white cast iron is accepted by most consumers for its excellent performance and the use ratio is enhanced continuously. But in practical production, there exists one serious problem in the use of grinding balls made of chrome-based white cast iron—early failure, which affects the grinding capability and economic performance badly. So the research of early failure mechanism has far-reaching theoretical and practical value.In this paper, the solidifying process of grinding balls produced by clad metal mould group casting and the prediction of shrinkage porosity and void are studied based on the casting numerical simulation software of Flow-3D. Also the distribution of residual stress of grinding balls in cast condition is simulated based on the software . The stress distribution after heat treating is determined by X-ray diffraction instrument. It is indicated that grinding balls in the metal mould solidified first and then in the sand mould, and the interior structures of grinding balls are sound and free of fault. There is a mass of residual stress in cast condition. Although a definite residual stress can be eliminated, an amount of stress still exists.Low-chrome grinding balls of clad metal mould were poured by in laboratory. The metallurgical structures in each part of grinding balls are researched through cut samples and the relation between the structure difference and the early failure of grinding balls is discussed. Simultaneously, the pyriform failure mechanism of grinding balls is investigated through falling sphere tests. It is shown that the existence of a great deal of internal residual stress is the main reason for the early failure of grinding balls and the structure difference is another important one.