Corrosion behavior and mechanism of 316 stainless steel in NaCl–KCl–FeCl₃ molten salt and vapor at 300°C

Abstract

The corrosion behavior of 316 stainless steel (316 SS) in NaCl–KCl–FeCl3 molten salt and vapor was studied at 300°C for 150, 300, and 500 h in Ar. The weight change, the micromorphology, element distribution, and crystal structure of the 316 SS alloy were analyzed by scanning electron microscopy, energy‐dispersive spectroscopy, and X‐ray diffraction. 316 SS alloys suffered from weight loss, significant visible corrosion shedding, and corrosion holes. The corrosion holes and corrosion shedding block of the 316 SS alloys become more and more serious with the increase in corrosion time. The corrosion depth of the corroded 316 SS alloys in NaCl–KCl–FeCl3 molten salt and vapor for 500 h can even reach up to 20.0 and 14.0 μm, respectively. 316 SS alloys in NaCl–KCl–FeCl3 molten salts underwent a more serious corrosion attack than that in the NaCl–KCl–FeCl3 vapor at 300°C due to the strong oxidizing compound FeCl3 in the molten salt. It not only offers a new insight into the corrosion behavior of 316 SS alloys in the chloride salts and corresponding vapor but also enriches the corrosion databases of the chloride salts.