Effect of chloride ions on the structure of the oxide layer on the surface of 316L stainless steel in high-temperature water: Experiments and Calculations

The structure and composition of the oxide layer on the surface of 316L SS after exposure to high-temperature and high-pressure water with different concentrations of chloride ions (0, 50, and 200 μg/kg) for 500 h were characterized using various analysis methods and DFT calculations. The oxide layer had a double-layer structure. With the increase in chloride ion concentration, the thickness of the inner oxide layer became thinner, and the growth rates became similar. DFT results show that the Cl and O adsorption on the matrix and oxide surface differ. On the surface of the substrate, Cl adsorbs more readily than O. On the oxide surface, O adsorption is prior to Cl adsorption. After the formation of stable oxides, the effect of Cl is weakened, which corresponds to the approaching corrosion rate in different solutions after 500 h.