Production and Application of the Austenitic High Chrome Cast Iron Grinding Ball-1
Zhang Bao-jie , QIAO Xiao2ai , Liu Wen-hui
( Shanxi Linfen Mechanical Casting Factory , Linfen 041000 , China)
Abstract :This article mainly introduces production and applction of the high chrome cast iron austenitic grinding ball. For obtaining austenite in casting state , the balls have stronger impact toughness. In addition, martensite transformation happens under impact wear conditions , mean while work hardening will also happens ,thus the material has higher toughness and still improves its impact resistance of composite. In the industrial application it can give play to its fine wearing capacity and economy.
Key Words :high chrome cast iron ; austenite ; work hardening ; wear resistance
As one of the most anti-wear metal materials, high chrome cast iron has been widely used in recent years, especially in the field of cast iron grinding ball.
Because the strength and toughness of common high chromium cast iron grinding ball are not high, the fracture and spalling are serious in use. It has been proved that the wear resistance of high chromium cast iron depends not only on the hardness determined by the type and quantity of carbide but also on the impact toughness, working hardening ability of the material determined by the Metal Matrix structure.
The high chromium cast iron grinding ball with austenite matrix strength and toughness is derived from the above principles. By adding austenitizing alloy elements and reducing carbon content, the amount of eutectic carbide in the structure can be reduced to Form as-cast austenite and improve the material’s impact toughness. Under the condition of impact wear, the martensite transformation is induced by friction impact, and the comprehensive properties of strength, toughness, and high wear resistance are achieved.
The material grade of high chrome cast iron austenitic grinding ball is ZQ C2. 4Cr15Mn2, the main elements are carbon (C) , chromium (Cr) , manganese (Mn) .
C has the greatest influence on the hardness of the material, and the hardness increases with the increase of C content. When the C’s content is high, the amount of carbide increases, the primary carbide is coarser, and the further hardness increases, but for the Matrix, the degree of fracture increases, the toughness and strength of the material decrease, and the crack and spalling phenomenon increase. Therefore, C content of 2. 0% ~ 2. 7% would be better.
CR is the main alloy element in high chrome cast iron, which is used to form FeCr 7C3 carbides with high microhardness in one part and to enhance the strength of the Matrix by dissolving in the Matrix. In this way, the hard carbide is embedded in the tough matrix, and the high chromium cast iron has both hard and tough properties. The content of CR was 13% ~ 17% , w (CR)/W (C) was 5. 6 ~ 7.
Mn has the function of stabilizing austenite and carbide, such as adding MN: 1. 5% ~ 3. 0%; the as-cast sub-stable austenite Matrix can be obtained by permanent mold casting, which not only improves the toughness of high chrome cast iron but also provides the working hardening and application conditions in impact wear environment.