Initial Corrosion Behavior of Spheroidal Graphite Cast Iron in Atmospheric Environment

Abstract

This study focused on the differences in initial corrosion behavior of spheroidal graphite cast iron, carbon steel and weathering steel in atmospheric corrosive environment, the atmospheric exposure test and dry/wet cyclic test were conducted to examine the effect of graphite and Cu of spheroidal graphite cast iron on its initial corrosion behavior. After exposure to the atmosphere for two years, the mean corrosion depth of spheroidal graphite cast iron is smaller than that of carbon steel and similar to that of weathering steel, whereas the initial corrosion of spheroidal graphite cast iron progresses earlier than carbon steel and weathering steel, regardless of the temperature, humidity, and the amount of sea salt. From the initial corrosion test results in the wet-dry cyclic test, that Cu precipitation was observed at the corrosion origin of the spheroidal graphite cast iron, which is same as that in weathering steel. Based on the findings obtained in this study, a schematic diagram of the initial corrosion mechanism of spheroidal graphite cast iron was speculated.