Wear resistant cast iron rocker arm and method of making same

摘要

A wear-resistant cast iron rocker arm or similar machine element is formed by differential pressure, countergravity casting an iron melt of low superheat into a ceramic investment shell mold maintained initially at room temperature and rapidly solidifying the melt therein to provide a wear-resistant, as-cast microstructure throughout the body of the element. The as-cast microstructure comprises a dendritic constituent of austenite or transformed austenite (e.g., pearlite) depending on alloy composition and an interdendritic carbide constituent. Interdendritic ledeburite will also be present if the austenite remains untransformed. The as-cast microstructure of the rocker arm is devoid of graphite.