Corrosion of a 316L stainless steel in a gaseous environment polluted with HCl: Mechanism.

The corrosion of a 316L stainless steel (SS) exposed to a humid gas flow polluted with HCl has been studied. The mixture is carried out in a reactor connected to two gas feedthroughs: one with wet air and one with HCl(g). The corrosion mechanism comprehension is based on several steps. The presence of humid air polluted by HCl involves the creation of a precursor film that can evolve to droplet formation. In contact with this acid and chloride concentrated electrolyte, the 316L SS corrodes producing soluble ferrous chloride. This corrosion product can evolve to the oxide formation, depending of the HCl concentration. For high concentrations, 316L SS corrodes uniformly. However, this phenomenon is accompanied by pits when the HCl concentration is not sufficient or the HCl flow is not continuous. The particularity of the corrosion mechanisms is shown as well as the problems using materials in an HCl‐polluted gaseous environment. [ABSTRACT FROM AUTHOR]