What is the difference between Inconel 625 and 316 SS?
316 stainless steel and nickel-based Inconel 625 are potential candidates for next-generation CSP systems using chloride molten salts as the thermal fluid and TES because of their good mechanical properties at high temperatures. It is known that 316 stainless steel and Inconel 625 alloy exhibit good corrosion resistance in nitrite molten salts. However, as mentioned above, chloride molten salt is much more corrosive than subnitrate molten salt. To the best of our knowledge, the corrosion mechanism of the alloy in chloride molten salt is still unclear, and the corrosion data of these two alloys in chloride molten salt, especially in the molten salt of the NaCl-KCl-ZnCl2 system, are scattered. In this work, in order to understand the corrosion mechanism and evaluate the corrosion resistance of 316 stainless steel and Inconel 625 alloy in chloride molten salts, these two alloys were studied in molten NaCl-KCl-ZnCl2 at 700°C and 900°C. The corrosion behavior was studied by immersion tests and electrochemical methods. Scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) was used to study the microstructural morphology and phase composition of the corrosion products.
Composition of 316 stainless steel (wt%)
| C | Si | Mn | P | S | Ni | Cr | Mo |
|---|---|---|---|---|---|---|---|
| 0.03 | 1.0 | 2.0 | 0.045 | 0.03 | 12 | 17 | 2.5 |
Main chemical composition of Inconel 625 alloy (wt%)
| Elements | Ni | Cr | Mo | Nb + Ta | Fe |
|---|---|---|---|---|---|
| Content | 61.2 | 22.25 | 9.65 | 3.75 | 3.15 |
