Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions: Part 1—Mill-Annealed Condition

Abstract

Alloy 22 (UNS N06022) is a Ni-Cr-Mo-W alloy developed for corrosion resistance in a variety of aggressive environments. Because of its excellent corrosion resistance, Alloy 22 was selected as a candidate container material for the disposal of high-level nuclear waste at the proposed repository at Yucca Mountain, Nevada. The localized corrosion susceptibility of mill-annealed Alloy 22 was assessed in chloride-containing solutions at temperatures ranging from 60°C to 150°C by comparing the crevice corrosion repassivation potentials with corrosion potentials measured in separate tests. Crevice corrosion repassivation potentials were found to be strongly dependent on temperature, chloride concentration, and nitrate-to-chloride molar concentration ratio. Corrosion potentials were dependent on solution pH but independent of chloride concentration.