Real-time tomography of stress corrosion cracking on stainless steel by an in-situ corrosion tensile test

Spent AGR (Advanced gas-cooled reactor) fuel cladding 20/25/Nb stainless steel may suffer from stress corrosion cracking (SCC) in cooling ponds and compromise storage safety, thus a better understanding of the SCC evolution is required. In this research, in-situ corrosion tensile experiments were performed on heat-treated 20/25/Nb and 304 stainless steels to capture the real-time development of SCC by X-ray tomography at a synchrotron beamline. Post-exposure materials were further characterised to analyse by FIB (focused ion beam) milling. SCC was only observed in 304 stainless steel, and 20/25/Nb stainless was more susceptible to intergranular corrosion (IGC) and pitting corrosion.