Molten salt stress corrosion of metal alloys - An updated review

Molten salt is commonly used as high-temperature heat transfer and thermal energy storage (TES) medium. The stress corrosion is a crucial influence factor for safety operation of molten salt TES system. This work summary the methods and evaluation parameters of molten salt stress corrosion. The stress corrosion behavior of different metal alloys in various kinds of molten salts is compared and analyzed, the anode dissolution mechanism and hydrogen-induced cracking mechanism of stress corrosion are summarized, and the slip dissolution mechanism and oxide film cracking mechanism of stress corrosion cracking in molten salt are expounded and explored. Furthermore, the influence of metal alloy microstructure on molten salt stress corrosion is summarized, the relationship between the addition of material components such as Ni, Mo, and N and the susceptibility of molten salt stress corrosion is analyzed, and the effects of molten salt impurities, stress and temperature changes on molten salt stress corrosion are discussed. The corrosion depth is positively correlated with corrosion time, molten salt temperature, and stress on the metal alloy. Additionally, the strategies to inhibit and alleviate stress corrosion in metal alloys are presented, such as coating, optimizing the alloy composition of materials, etc. Finally, the further research direction of stress corrosion in molten salt is proposed, which is of great significance for selecting suitable metal alloy materials for molten salt TES system.