Influence of Non-Equilibrium Grain Boundary Segregation of Phosphorus on Corrosion Resistance of Marine Steel A690M in Seawater

The grain boundary segregation behavior of phosphorus in marine steel A690M during tempering treatment at 600℃ was analyzed by Auger electron spectroscopy. The influence of grain boundary segregation of phosphorus on corrosion resistance of A690M steel in seawater was studied by microscopic observation of corrosion rust layer and polarization curve. The results show that the phosphorus segregation at grain boundary is consistent with non-equilibrium segregation behavior caused by vacancy-solute complex diffusion. The higher the concentration of phosphorus at grain boundary, the easier the formation of lamellar corrosion pit in the rust layer, which decreases the corrosion resistance of marine steel.