In order to overcome the shortcomings in the traditional production of ADI grinding balls, it is necessary to find cheap alloy combinations from materials to replace Mo, Cu and other precious alloy elements. Through years of practice, research and improvement, the production of nodular cast iron grinding balls with proper chemical composition combination has solved the above problems by replacing precious alloy elements such as Cu and Mo with Si-Mn.
Mn is one of the cheaper alloy elements, which can expand the austenite zone like Cu and Mo, shift the C curve to the right, thus increasing the hardenability, and is conducive to the formation of bainite and martensite. However, Mn is also an anti graphitized element, which is prone to positive segregation, promoting the formation of carbides at the boundary of eutectic cluster, resulting in higher hardness and lower toughness. Si is also a cheap alloy element, which strongly promotes graphitization. Adding an appropriate amount of silicon can effectively inhibit carbide precipitation and toughness reduction caused by adding Mn. In the process of production and manufacturing, the quality of inoculation and spheroidization must be strictly controlled. In this way, the new type Si Mn alloyed ductile iron becomes a new kind of grinding ball material, replacing expensive alloy with cheap metal elements. The material composition is shown in the table.
| C | Si | Mn | P | S | Re, Mg (residual) | B |
| 3.1-3.8 | 2.0-3.2 | 1.4-2.5 | ≤0.04 | ≤0.03 | ≥0.04 | Appropriate Amount |