Abstract
Cast iron specimens containing different contents of component elements were prepared for bead-on-pleat test. The results show that the amount of pinholes increases with increasing C, Si, Mn, Ni and Cu contents, while the amount of pinholes decreases with increasing P, S, Cr, Mo and Mg contents. The following conclusions were obtained. (1) Graphitizing elements, such as C, Si, Ni, and Cu and oxide forming elements such as Mn, Si at the interface between graphite and matrix, tend to promote the generation of pinholes easily. (2) Elements with give oxidation resistance or graphite growth resistance to cast irons, elements which tend to form oxide film on the cast iron surface, elements which segregate near the eutectic cell boundary, and elements which form more stable oxides than carbon monoxide all tend to reduce pinholes.
