Crevice Corrosion Damage Analysis on Ni-Cr-Mo Alloys Proposed for the Nuclear Waste Containers

Abstract

The crevice corrosion of Alloy-22 has been studied under constant applied current conditions in 5 mol/L NaCl at 120°C. Stable propagation could be achieved for applied currents of ≥ 10 μA, but not for applied currents ≤ 5 μA, despite a large number of initiation attempts. Initiation appears to require that the potential achieve a sufficiently positive value (200 mV vs. sat'd Ag/AgCl). Propagation occurs preferentially at the edge of the creviced area and spreads across, rather than penetrating into, the alloy surface. This may be due to the presence of a protective molybdenum gel layer on the exposed alloy surface.