Corrosion behaviour of ductile cast iron

Abstract

In this investigation the corrosion behavior of ductile cast iron as function of the microstructure and electrolyte solution has been conducted. The change in microstructure of the ductile cast iron is obtained by austenetising at different temperatures of 850°C, 900°C,950°C and 1000°C for 90 minutes followed by water quench. Corrosion tests included both immersion tests and electrochemical test. Corrosion rates measured from the immersion test using the weight loss method revealed that the cast iron investigated suffer less corrosion when exposed to sodium hydroxide compared to sodium chloride and that the corrosion rates are not significantly affected by the microstructure of the material. Observation of the corrosion attack also showed that the type of corrosion is that of uniform instead of localized. The low corrosion rates of the ductile iron are probably the results of the high Si content in the ductile iron, which provide a thin and protective hydrate layer. This observation is reconciled with previous research which investigated high Si containing ductile cast irons.