A method of forming a bi-metallic casting. The method includes providing a metal preform of a desired base shape defining a substrate surface and removing a natural oxide layer and surface contamination from the substrate surface to yield a cleaned metal preform. The method further includes galvanizing the cleaned metal preform, yielding a galvanized metal preform followed by electroplating a thin nickel film on at least a portion of the substrate surface of the galvanized metal preform. Additionally, the method includes metallurgically bonding the portion of the metal preform having the nickel film with an overcast metal to form a bi-metallic casting. The nickel film promotes a metallurgical bond between the metal preform and the overcast metal.