Study on the corrosion behavior of 316H stainless steel in molten NaCl–KCl–MgCl2salts with and without purification

The corrosion behavior of 316H stainless steel (SS) in the impure and purified NaCl–KCl–MgCl2salt was investigated at 700 °C. Results indicate that the main deleterious impurity induced corrosion in the impure salt was the absorbed moisture, present in the form of MgCl2·6H2O. 316H SS occurred severe intergranular corrosion with a corrosion depth of 130 μm for 1000 h in the impure NaCl–KCl–MgCl2salt. In contrast, the purification treatment of molten chloride salt by the dissolved Mg metal can remove the absorbed moisture, and the corresponding reactions were also discussed. As a result, the corrosiveness of NaCl–KCl–MgCl2salt is reduced significantly. 316H SS occurred slight uniform corrosion with a depth of less than 5 μm for 3000 h in the purified NaCl–KCl–MgCl2salt.