Improvement of corrosion protective film on stainless steels by UV light irradiation

Stainless steels have been widely used for many apparatuses of light water reactors for their excellent corrosion resistance. However, local corrosion sometimes occurs in solution including harmful ions such as dissolved oxygen and chloride ions. Then, it is necessary to make further improvement of the corrosion protective film on stainless steels. In this study, UV light irradiation was examined to modify the non-conductive film with semiconductor properties. It was observed that the resistance to the pitting corrosion of the film of 304 stainless steels was improved by UV light irradiations due to chromium enrichment. However, the effect of UV light irradiation on sensitivity for stress corrosion cracking of 60% cold-worked 316L stainless steels was not cleared. (A.H.)