The centrifugal casting of railroad car wheels was one of the first applica
The centrifugal casting of railroad car wheels was one of the first applica‐tions involving controlled variations in chemical composition from the outside periphery of the car wheel as compared to the balance of the casting. As the casting was poured, a quantity of ferromanganese was introduced with the first metal to enter the mold. 
This formed a high manganese wear‐resistant tread and car wheel flange, as compared to the softer second por‐tion of the molten metal which became the center portion and the hub of the wheel. Although this practice is no longer used, similar applications do exist since, in principle, true solutions will not be separated in the centrifu‐gal casting process.