Study on the corrosion behavior of static liquid Pb-16.7Li on the structural material CLF-1 steel

In liquid Pb-Li tritium breeding blanket, the compatibility between liquid Pb-Li and Reduced-activation-ferritic-martensitic (RAFM) steel structure material is crucial for the successful application of the RAFM steel. Corrosion experiments on CLF-1 steel in static Pb-Li at 550 ℃ were conducted for up to 1200 h to figure out the corrosion behavior and mechanism. After exposure, a subset of specimens was cleaned by mixed acid dissolution, while the remaining samples were cold-mounted in resin for cross-sectional observation. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Electron Backscatter Diffraction (EBSD) measurements were employed to characterize the corrosion behavior and reveal the corrosion mechanism. With increasing exposure time, corrosion initiates at grain boundaries and spreads laterally, producing boundary ditches, hollows, protrusions, and ultimately pebble‑like grains. It is proposed that corrosion occurs through the dissolution of Fe and Cr, facilitated by the diffusion of Li into the grain boundaries and grains, as well as the penetration and adsorption of Pb.