Corrosion resistance of 310S and 316L austenitic stainless steel in a quaternary molten salt for concentrating solar power

摘要

This paper evaluates the corrosion of 310S and 316L austenitic stainless steel in a quaternary molten salt KNO3-NaNO2-NaNO3-KCl (wt%, 50.35:38:6.65:5) at 500°C The corrosion rates were determined using gravimetric analysis, which measures the weight loss over 1848h in order to identify the corrosion products with field-emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). The results showed that the corrosion rate of these two austenitic stainless steels has the highest value at the initial stage, and then decrease followed by a constant value, which is due to the formation of protective oxide film on the interface to prevent further corrosion. Compared to 316L, 310S has better corrosion-resistance in the salt, since it contains more Cr and Ni element. The corrosion layer thickness of the 310S and 316L is 1.613um and 2.903μm based on the cross-section micrographs, which is equal to 0.499μm/year and 1.460μm/year, respectively.