Unveiling the synergistic effect of thermal aging and irradiation corrosion on the passivation performance and stress corrosion cracking of 308 L stainless steel under high-temperature water environment

This study investigated coupling of thermal aging with irradiation corrosion, and carried out the microstructure and electrochemical characterization of 308 L stainless steel (SS). The passivation performance of 308 L SS was studied under the simulated pressurized water reactor (PWR) environmental condition and its stress corrosion cracking (SCC) performance was tested under thermal aging-irradiation conditions. The experimental results indicate that thermal aging results in spinodal decomposition of delta-ferrite, giving rise to G-phase precipitate and carbide precipitate formation at delta/gamma-phase interface, whereas irradiation causes Cr depletion and Ni enrichment at the interface. Both thermal aging and irradiation lead to the decreased corrosion resistance of 308 L SS. Under coupling conditions of the two, severe Cr loss occurs at the phase boundary, which leads to severe corrosion on delta/gamma phase boundary and also reduces SCC resistance of 308 L SS.