Effect of irradiation on corrosion behavior of 316L steel in lead-bismuth eutectic with different oxygen concentrations

Okubo, Nariaki; Fujimura, Yuki; Tomobe, Masakatsu*

Quantum Beam Science (Internet), 5(3), p.27_1 - 27_9, 2021/09

https://doi.org/10.3390/qubs5030027

In an accelerator driven system (ADS), the beam window material of the spallation neutron target is heavily irradiated under severe conditions. Displacement damage and corrosion occur simultaneously because of high-energy neutron and/or proton irradiation in the lead-bismuth flow. The materials used in ADSs need to be compatible with the liquid metal, which is lead-bismuth eutectic (LBE), to prevent issues such as liquid metal embrittlement (LME) and liquid metal corrosion (LMC). In this study, the LMC behavior after ion irradiation of 316L austenitic steel is considered for self-ion irradiations followed by the corrosion tests. The 316L specimens were irradiated by 10.5 MeV-Fe ions at temperature of 450C up to 50 displacement per atom (dpa). After the corrosion test at 450C in LBE with low oxygen concentration, the surface of the non-irradiated area was not oxidized but corrosive morphology with pits, whereas the irradiated area was covered by an iron/chromium oxide layer. The surface of the irradiated area was covered by the duplex layers of iron and iron/chromium oxides in the case of higher oxygen concentration in LBE. It is suggested that irradiation can advance oxide layer formation because of enhanced Fe diffusion caused by the residual vacancies in 316L steel.