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.