Atmospheric-Induced Stress Corrosion Cracking of austenitic stainless steels under limited chloride supply

The occurrence of Atmospheric-Induced chloride Stress Corrosion Cracking in types 304L and 316L stainless steels contacted with sea-salt and magnesium chloride deposits has been studied under controlled conditions of relative humidity (ca. 30%) and temperature (80°C). The time to cracking and extent of cracking are shown, at least semi-quantitatively, for specimens contacted with sea-salt deposits to be related to the deposit size prior to environmental exposure with each of these quantities appearing to decrease with decreasing deposit size. For specimens contacted with MgCl ₂ the quantities correlate with the nominal deposition density decreasing with decreasing deposition density. Specimens of the stainless steels, U-bends and pieces taken from an Intermediate Level Waste container, were also exposed to a marine environment under sheltered and open conditions. Pitting and oxide build up was observed on these specimens after ca. 5 months with pitting occurring to a greater extent on those exposed under the shelter. No cracking was observed after 11 months in the atmospheric exposures.