Localized corrosion of candidate container materials in ferric chloride solutions

Localized corrosion behavior of candidate inner- and outer-container materials of current nuclear waste package design was evaluated in aqueous solutions of various concentrations of ferric chloride (FeCl3) at 30 C, 60 C and 90 C using the electrochemical cyclic potentiodynamic polarization (CPP) technique. Materials tested include A 516 carbon steel (UNS K01800), and high-performance UNS N08825, UNS N06985, UNS N06030, UNS N06455, UNS N06625, UNS N06022, and UNS R53400. A 516 steel suffered from severe general and localized attack including pitting and crevice corrosion. High-nickel UNS N08825 and N06985 also became susceptible to severe pitting and crevice corrosion. The extent of localized attack was less pronounced in UNS N06030 and N06455. UNS N06625 experienced severe surface degradation including general corrosion crevice corrosion and intergranular attack. In contrast, only slight crevice corrosion tendency was observed with nickel-base UNS N06022 in solutions containing higher concentrations of FeCl3 at 60 C and 90 C. UNS R53400 was immune to localized attack in all tested environments. The test solutions showed a significant amount of precipitated particles, especially at higher temperatures