Corrosion performance of 316 stainless steel and nodular cast iron 600-3 in molten Ca(NO3)2-NaNO3-KNO3 salt

摘要

? 2022The corrosion effect of Ca(NO3)2-NaNO3-KNO3 on 316 stainless steel (316SS) and nodular cast iron 600-3 (QT-600-3) at 520 °C was studied by static corrosion method in argon. After corrosion for 100 h, it was found that there were oxides on the corroded surfaces of the two alloys in XRD spectra. The oxide on the surface of 316SS alloy after corrosion was very thin, and the thickness of Cr depleted layer on the surface of corroded 316SS was only 0.4 μm. On the other hand, a loose oxide layer with a thickness of about 42 μm was formed on the surface of QT-600-3 after corrosion, and its main components were Fe2O3 and Fe3O4. The corrosion of Ca(NO3)2-NaNO3-KNO3 salt on QT-600-3 is much greater than that on 316SS. The fundamental reason for the different corrosion performance of the two materials was the different oxide structures formed on the surface of the two alloy materials. The results may be helpful to the selection of structural materials when Ca(NO3)2-NaNO3-KNO3 salt is used as the heat storage medium.