Abstract
Vanadium carbide layers formed on grey or ductile cast irons when immersed in molten borax baths containing vanadium are as dense as those formed on steels. Since the growth rate of VC layers on graphites in the cast irons is smaller than that on the matrix, pits are formed on the graphites in the beginning of the growth when VC layers are thin. But these pits disappear gradually with the growth of VC layers. The growth rate of VC layers on spheroidal graphites in ductile cast iron is smaller than that on artificially made bulk graphites. Initially growth rate of VC on spheroidal graphite is slower at the center of graphite than at the edge. Intermediate iron carbide layers containing small amount of V and Cr form between the matrix and VC layers and between the matrix and graphites which are in contact with the VC layers.
