LOCALIZED CORROSION OF 316 STAINLESS STEEL IN SUPERCRITICAL WATER CONTAINING NaCl

摘要

Effects of temperature, pressure and concentration of NaCl on the corrosion behavior of 316 stainless steel in supercritical water were examined. 316 stainless steel showed mass loss at sub- and supercritical temperature in 10 mass% NaCl. The mass loss of 316 stainless steel increased with increasing temperature. The mass loss increased with increasing pressure in 10 mass% NaCl. The mass of 316 stainless steel decreased remarkably in 4 to 10 mass% NaCl. Oxide layers, formed on 316 stainless steel exposed at 300-400 ℃, were very thin and homogeneous. However, oxide layers formed at 450-550 ℃ were inhomogeneous and some localized corrosions were observed. Oxides such as γ-Fe_2O_3, Fe_3O_4 and FeCr_2O_4 were identified on the surface of 316 stainless steel exposed at 400-550 ℃ in 10 mass% NaCl.