Abstract: The corrosion behavior of cast irons in caustic soda is investigated by means of the corrosion tests. The results show that the metallographic structure influences the corrosion resistance obviously. The cast iron with pearlite matrix is the best. The hard phase (phosphide eutectic) in the matrix can improve the general corrosion resistance but decrease the stress corrosion resistance. And the influences of graphic morphology on the general corrosion resistance are not obvious. While the coarse flaky graphit accelerates stress corrosion due to its being crack source, the uniform fine flaky and vermicular graphits are useful in improving the stress corrosion resistance. According to the value of maintain passivity current the general corrosion resistance of cast irons can be predicted. It has been proved that the slow strain rate technology (SSRT) is an effective method for studying the stress corrosion of cast irons.

Key words: Electrochemical corrosion, General corrosion, Slow strain rate technology, Stress corrosion