Effect of Pb on the polarization behavior of alloy 600 in a caustic solution

As one of the most suspect impurities causing the outer diameter stress corrosion cracking (ODSCC) in steam generator tubes, the effect of lead (Pb) on the SCC has been extensively investigated. In spite of numerous studies on the subject, the effects of lead on the polarization behavior and surface oxide formation of Ni base alloys are still debatable. The purpose of this study is to provide basic information about the lead effect. In the measurements of the polarization curves, a cathodic treatment (CT) at a potential below the open circuit potential (OCP) is often performed to remove a surface oxide. To examine the effects of lead and the cathodic treatment on the polarization behavior of Alloy 600, polarization measurements on Alloy 600 samples were performed in 40% NaOH solutions with and without Pb