Ion-selectivity of iron sulfides and their effect on H_2S corrosion

摘要

H2S corrosion behaviors of P110, Fe-Mn-Al, and Fe-Mn-Cr-Ni high-Mn steels were analyzed according to ion-selectivity of corrosion products. At 60 degrees C and 80 degrees C, cation-selective troilite restrain diffusion of corrosive ions to the substrate. The corrosion rates were low, and uniform corrosion occurred. At 100 degrees C and 205 degrees C, anion-selective pyrrhotite caused accumulation of Cl- between corrosion scale and substrate. Corrosion rates were high and localized corrosion happened. Crystal atom stacking models of iron sulfides were built, and the adsorption energy of ions on the exposed surface was calculated to discuss the ion-selectivity mechanism. The effect of alloy elements on corrosion behavior was analyzed.