High-temperature corrosion behavior of Inconel 617 with Ni-claddings in molten FLiNaK salt

In this study, the Ni-cladding layer was deposited on Inconel 617 substrate as a corrosion-resistant layer by gas tungsten arc welding. The corrosion behavior of Inconel 617 alloys with and without Ni-cladding layer, and individual Ni-claddings was studied at 850 degrees C in molten FLiNaK salts with a high Ni2+ concentration. After corrosion, FeNi3 layers cover the surface of all alloy specimens. Inconel 617 suffers from severe Cr depletion, whereas Ni-claddings with low Cr content demonstrate significantly improved corrosion resistance. For Ni-clad Inconel 617, if Ni-claddings are broken, the coupling of Ni-claddings and Inconel 617 can accelerate the corrosion of Inconel 617 by galvanic corrosion, inducing a mass transfer of Co from Inconel 617 to Ni-claddings through the molten salts.

Automated summary

This study investigates the corrosion behavior of Inconel 617 alloys with a Ni-cladding layer deposited by gas tungsten arc welding. The presence of the Ni-cladding layer significantly improves the corrosion resistance of Inconel 617, especially in alloys with a low chromium content. However, if the Ni-cladding layer is broken, it can accelerate the corrosion of Inconel 617 and induce a mass transfer of cobalt from Inconel 617 to the Ni-cladding layer in the presence of molten salts.