PURPOSE: To prevent seizure of a bearing metal by forming a crankshaft and the bearing members with a cast iron which is composed of a mixed structure of bainite and retained austenite.
CONSTITUTION: A crankshaft is manufacture with globular graphite cast iron which is austempertreated so that a retained austenite amount in its base can be 25W50 vol.%, and the bearing members are manufactured with the globular graphite cast iron which is austempertreated so that the retained austenite amount in its base can be 25W50 vol.%, similarly to the above, a flake graphite case iron, or a vermicular graphite cast iron. Therefore, the bearing members with the same thermal expansion ratio as that of the crankshaft can be obtained, then seizure of the bearing metal caused by the friction between the crankshaft and the bearing can be prevented.
OKAZAKI TAKESHI
HANAKAWA KATSUNORI
