Molten salt corrosion (FLiNaK) of a Ni–Mo–Cr alloy and its welds for application in energy-generation and energy-storage systems

Abstract

The molten salt corrosion performance of a Ni–Mo–Cr (GH3535) alloy weldment, produced using matching filler metal, was assessed. Corrosion testing was performed in FLiNaK molten salt at 750 °C for 500 h. Present results reveal that, despite a similar chemical composition, the weld metal has somewhat superior corrosion resistance to the parent metal. The difference is primarily attributed to the significantly lower density of high-angle grain boundaries (HAGBs) in the weld metal. Results further suggest that large M6C carbides present in the parent metal may contribute to corrosion attack of the alloy matrix via galvanic corrosion.