The main corrosion process was the dissolution of Cr and controlled by Cr diffusing from metal matrix into the melt.

The corrosion performance was exactly the same between the base and weld zone of weld joint after long term exposure.

Depth of Cr depletion increased rapidly in early stage and then slowed down to approach a plateau for long term exposure.

Impurities in the FLiNaK molten salt promoted the corrosion at early stage.

Impurities of metal ions such as Ni and Fe in the melt substituted Cr in metal and deposited on the surface.