Cast Functionally Graded Materials Based on Chromium White Irons for Fabricating Grinding Bodies

The possibility of the use of directed crystallization for obtaining a graded structure in grinding balls from chromium white irons is assessed. The chemical composition of the iron is determined. The structure and the microhardness of the balls are studied after a heat treatment. Tests of the grinding balls are performed. Directed crystallization in metallic molds is used to provide a graded structure from the surface to the center of the balls. Preliminary modification with manganese also affects the formation of the structure. The structure of the surface layer in the radial direction is represented by austenitic dendrites and a quasi-eutectic based on (Cr, Fe)7C3 carbides and meets the principle of composite hardening making the balls highly abrasion-resistant. The core of the grinding balls consists of a dispersed spherulitic eutectic and base leading carbides of type M7C3, which raises the resistance of the balls to impact loads during service.