Effect of Salt Composition and Microstructure on Stress Corrosion Cracking of 316L Austenitic Stainless Steel for Dry Storage Canisters

摘要

The atmospheric SCC/pitting susceptibility of deposited MgCl2, synthetic sea-salt and site-specific sea-salt (containing ammonium and nitrate ions) on weld, HAZ and base 316L canister material was investigated. Higher SCC/pitting densities were observed for the HAZ region exposed to MgCl2, due to higher tensile residual stresses and plastic strains. Pitting in the weld region exposed to MgCl2 show preferential corrosion of delta-ferrite. Salt composition appears to have had a significant impact on SCC, pitting density and surface corrosion behaviour. Maximum surface crack propagation rates in the HAZ of 4 x 10(-11) ms(-1) were obtained for both synthetic sea-salt and MgCl2. (C) 2020 Published by Elsevier B.V.