The corrosion behavior of 316 stainless steel has been examined in distilled water and 1–5 % NaCl containing 0.01–1 % H2O2 as an oxidizing agent at temperatures of 350–500 °C and at a constant
pressure of 40 MPa. In the mixture of distilled water + 1 % H2O2, the materials showed slightly mass gains at all temperatures and almost within the range of detection limit. The addition of H2O2 to NaCl
solutions accelerated the corrosion, resulting remarkable mass losses at all temperatures. The rate of the mass loss increased with increasing temperature, except for the specimen exposed at 450 °C. In oxidizing NaCl solutions, the samples significantly showed mass losses with increasing H2O2 content, probably due to shifting of the potential into the transpassive region of the specimens. It was also observed that mass loss was increasing with NaCl content, indicating the important role of NaCl in corrosion of the materials in oxidizing NaCl solutions. The oxide scale formed on the specimens was highly enriched with Cr and Mo, and depleted in Ni and Fe.
Keywords: sub- and supercritical water oxidation, sodium chloride solution, hydrogen peroxide, pitting corrosion, transpassive dissolution, 316 stainless steel.