Electrochemical study of the dissolution of oxide films grown on type 316L stainless steel in molten fluoride salt

The corrosion behavior of oxide films grown on Type 316L stainless steel (SS) in molten FLiNaK (LiF-NaF-KF: 46.5-11.5-42 mol.%) salt was investigated. The results show that the oxide film formed on Type 316L SS is unstable and can only temporarily protect materials from corrosion in molten FLiNaK salt. Based on the electrochemical impedance spectroscopy, the oxide dissolution rate is calculated to be 0.85 nm/h at 700 degrees C in molten FLiNaK salt. After the oxide film dissolved, Cr and Fe are selective dealloyed from the steel, leading to intergranular corrosion of Type 316L SS in molten fluoride salt.

Automated summary

The study found that the oxide film formed on Type 316L stainless steel in molten FLiNaK salt is unstable and can only provide temporary corrosion protection. After the dissolution of the oxide film, selective dealloying of Cr and Fe from the steel leads to intergranular corrosion of Type 316L SS in molten fluoride salt.