INVESTIGATION OF CHLORIDE-INDUCED STRESS CORROSION CRACKING FOR AISI 304/304L STAINLESS STEEL USING NOTCHED BAR SPECIMENS

摘要

Spent nuclear fuels are stored in dry storage canisters made of austenitic stainless steels. Canisters have a sensitivity to chloride-induced stress corrosion cracking since some storage facilities are located in coastal regions, and this environment could have a higher risk for pits and cracks to form on the surface of canisters. Hence, this paper suggests an experimental method of evaluating crack initiation for austenitic stainless steels. Notched bar specimens fabricated using AISI 304 and 304L stainless steels are designed to simulate loads corresponding to welding residual stresses on the surface of canisters. For testing to be conducted in chloride environments, the developed tester for evaluating CISCC is designed such that the notched bar specimens are immersed into the brine of 5% salinity and are loaded by tightening a spring to provide a constant load condition at 50 °C temperature. Also, initial load applied to each notched specimen is verified using finite element analysis as in the same experimental condition. As a result, the areas by pitting corrosion on notches are 'measured using the Image Analyzer program and the stress parameters obtained from the finite element analysis are used to correlate the effect of the pit formation.