Correlation between film rupture ductility and PbSCC of Alloy 800

The fracture ductility of anodic films was measured for Alloy 800 at 300 °C in a neutral crevice solution with and without lead contamination. The film fracture ductility decreased, generally, with rising potential and increasing lead impurity concentration. The lead contamination altered the compositions of anodic films significantly and the effects of lead depended heavily on the passivation potentials. Anodic films containing more MOH and MOH2 bonds displayed lower film rupture ductility. The film rupture ductility correlated well with the stress corrosion cracking (SCC) resistance. It was found that the sensitivity of SCC resistance to lead contamination increased with an increase in the impact of lead contamination on the film rupture ductility. It is concluded that the SCC of Alloy 800 is likely related to film rupture at the crack tip and that the high SCC susceptibility in lead-contaminated environments may be related to the reduced rupture ductility of anodic films.