Research on Pitting Strength uuder Rolling Contact of Gray Cast Iron

A study on the pitting resistance of gray cast iron containing about 3.5~3.7% C, which was cast or heat-treatment, was carried out by performing experiments using a Nishihara-type wear testing machine under sliding condition with light oil as a lubricant. The result obtained are summarized as follow. 1) The pitting strength decreases in proportion to the amount of graphite. Flaky graphites remarably lower the pitting strength, especially at high matrix handness. 2) The pitting crack of the flaky cast iron was deeper than the spheroidal cast iron. 3) It was shown that the position of the pitting crack of gray cast iron closely related to the depth of the maximum stress value calculated from the maximum shearing theory. 4) Pitting strength of gray cast iron is mainly determined by the maximum shearing stress.