Corrosion initiation of Hastelloy C-2000 in an HCl-polluted atmosphere

In this study, welded and non-welded Hastelloy C-2000 samples are tested at room temperature in HCl environments, with two experiments: one in hydrochloric acid solutions and one in HCl vapor/condensate phases. In the hydrochloric acid solutions, there is no corrosion after more than 900 hr of exposure. In the humid air polluted by HCl, corrosion occurs in the form of an intergranular attack at the metal grain boundaries. In the weld bead zone, areas rich in molybdenum and depleted of nickel seem to be less susceptible to corrosion than the zones depleted of molybdenum and rich in nickel. This study highlights that Hastelloy C-2000, exposed to HCl vapor/condensate phases, is more penalizing than when immersed in an HCl solution, which is due to the presence of oxygen.