On the Wearing Phenomena of Nodular Graphite Cast Iron (1st Report)

A systematic investigation on the wear of nodular cast iron has hardly ever been heard of. This work was carried out for inspecting the wearing mechanism by means of lubrication or slide-weating of various kinds of nodular cast iron and then for comparing the result with that of ordinary pearlite cast iron. According to the work, the wear of the nodular cast irons becomes considerably different according to their structures; the less the magnitude of ferrite around graphite, the greater becomes the resistance to wear, and the specimen of which the matrix in structure is wholly pearlite with no ferrite shows the least wear. Compared to the ordinary cast iron, in this respect the specimen of which the structure consists entirely in pearlite in the matrix shows a slightly better resistance against wear, but when the structure consists in bull’s eyes it is worse. That cast iron having higher hardness and less elongation is superior in resistance to wear is contrary to the request of mechanical properties generally demanded. Deducing from observations of the worn surface, the thermal resistance of nodular cast iron would be high. Again, alloying iron with phosphor improves the resistance to wear but in a different tendency. Inspecting the breakage mechanism of the worn surface of high phosphor cast iron, the mechanism was found to differ from that of ordinary cast iron. After the specimen run for a long period provided that only oxidation wear carried out, that the wear phenomena appears as in mixed of bright surface wear and fusion wear is recognized.