Research on the Oxidation Mechanism of Vermicular Graphite Cast Iron.

The oxidation mechanism of vermicular graphite cast iron was studied. The oxidation reaction starts from graphites and diffused slowly. Graphites in vermicular graphite are interconnected, coral-like clusters, providing the main oxidation core and channel. The worm-like graphites on the surface are mostly oxidized and form oxide affected zones. The oxide films are composed of a loose oxide layer with the phases of FeO, FeO, and FeO, and a dense passivation layer with FeO and FeSiO. After oxidation, pearlites in the vermicular graphite cast iron are decomposed into ferrite and cementite at high temperatures.