Intergranular corrosion of stainless steel 316L in molten LiCl-NaCl-KCl salt at 700 °C

Molten chloride salt is an ideal heat transfer and storage medium for solar power generation systems. However, the strong corrosion of high-temperature molten salts on metal materials is the main problem limiting its applications in solar thermal power systems. In this work, corrosion behavior of stainless steel 316L in molten chloride salt at 700°C was examined and characterized. Results show that the stability of surface oxide of stainless steel 316L was dramatically jeopardized in high-temperature chloride molten salt. When the oxide film was dissolved, stainless steel 316L corrodes primarily through the selective dissolution of Cr with intergranular corrosion features. Moreover, O impurity in the chloride molten salt enter the alloy matrix through grain boundary and form intergranular oxide of (Fe,Cr,Ni) 3 O 4 spinel, accelerating the intergranular corrosion crack in molten chloride salts.