PURPOSE: To obtain cast iron for a rocker arm having superior wear resistance by preparing cast iron contg. specified percentages of C, Si and Mn and forming a graphite-free structure consisting of specified percentages of retained austenite and bainite by austempering.
CONSTITUTION: Cast iron consisting of, by weight, 0.5W4.5% C, 0.5W3.0% Si, 0.1W1.0% Mn and the balance essentially Fe and forming a graphite-free structure consisting of 10W60vol% retained austenite as the matrix and the balance bainite, bainite-martensite mixture or bainite-pearlite mixture by austempering is prepd. When the cast iron is used as the material of a rocker arm, it has superior resistance to wear and scuffing and damages hardly a material along which the arm slides.
MASUDA RIYUUICHI
SEKIGUCHI TSUTOMU
