Localized Corrosion of Stainless Steel in a Nuclear Waste Cooling Water System—Part 6: Testing for Stress Corrosion Cracking Susceptibility

To investigate possible inhibition options for large corrosion pits in 18Cr-13Ni-1Nb stainless steel, various designs of artificial pits were developed previously and shown to be capable of sustaining corrosion for long periods. Nitrate added to the bulk water in large concentrations was found previously to be capable of affecting inhibition, but there were indications of deleterious effects in the form of increased corrosion, and it also was speculated that stress corrosion cracking might result in some circumstances. To provide the means of investigating any tendency for a transition from pitting to stress corrosion cracking, work is reported here to incorporate tensile stress into the artificial pit specimen, consequently rendering it capable of detecting stress corrosion cracking if the environmental conditions are conducive. Tensile stress was incorporated by including a notch ahead of the pit cavity, which was compressively loaded. The developed specimen, termed the stressed all-metal pit, is shown ...