Production and application of Austenitic high chromium cast ball （1）
Zhang Baojie, Qiao Xiaoai, Liu Wenhui
(Shanxi Linfen Machinery Casting Co., Ltd., Linfen, Shanxi 041000)
Abstract: The production process and key points of austenitic high chromium cast iron grinding ball are introduced. Because of its as-cast austenite structure, it has high impact toughness. In addition, in the condition of impact friction, the microstructure will change to martensite, which will produce a work-hardening phenomenon. The material has high toughness and high impact wear resistance. Production should show that this grinding ball has excellent wear resistance and economy.
Keywords: High chromium cast iron, austenite, work hardening, wear resistance
As one of the most anti-wear metal materials, high chromium cast iron has been widely used in recent years, especially in cast iron grinding ball production and application.
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 proven that the wear resistance of high chromium cast iron, depends not only on the hardness of the material determined by the type and quantity of carbide but also on the impact toughness of the material determined by the metal matrix structure and its working hardening ability in use.
The austenitic matrix high chromium cast iron grinding ball is derived from the above principles, through adding austenite, austenitizing the table gold, and reducing the carbon content in order to reduce, reduce the total microstructure, the amount of crystalline carbide, at the same time using the method of permanent mold casting, after rapid cooling, as-cast austenite and austenite are formed, and the impact toughness of the material is improved. Under the condition of impact wear, martensite transformation is induced by friction and impact, and the comprehensive properties of strength, toughness, high wear resistance, and wear resistance are achieved.
Austenitic, base strength and toughness high chromium cast iron grinding ball material grade are ZQC2.4CR15MN2, the main elements are carbon (C), chromium (Cr), manganese (Mn).
Carbon on the hardness of the material, the greatest impact, hardness, with the content of C, increase and increase. When the content of C is high, the structure, the amount of middle carbide increases, the primary carbide is coarser, the hardness further increases, but to the matrix, the degree of fracture increases, the material, the toughness, the strength decreases, the use, the middle crack, the flaking phenomenon intensifies. Therefore, 2.0%-2.7% of C content is suitable.
Cr is the main alloying element in high chromium cast iron, which is used to form (FECR7) C-3 carbide with high microhardness and enhance the strength of the matrix by dissolving in the matrix structure in the other. In this way, the hard carbide is embedded in the tough matrix and the body structure. The high chromium cast iron has the properties of both hard and tough. The content of CR was 13% ~ 17% , w (CR)/W (C) was 5.6 ~ 7.
Mn has the function of stabilizing austenite and carbide, for example, adding Mn:
- 5% ~ 3.0% in high chromium cast ball, the as-cast sub-stable austenite structure can be obtained by using metal mold casting process, which can improve the structure of as-cast sub-stable austenite.
- The toughness of the high chromium cast iron material is obtained.
- The material has the conditions of working hardening and using in the impact wear environment.