When the second phase is precipitated from the iron surface, the iron surface and the second phase precipitate constitute the galvanic cell. The occurrence of REDOX reaction is accompanied by the process of surface electrochemical corrosion, resulting in the continuous dissolution of the anode material. Above all, the existence of Al/Si atoms can reduce the open circuit voltage between anode and cathode materials to improve the corrosion resistance of the steel. Display omitted The electrochemical corrosion on the face-centred cubic Fe (111) surface is studied on the basis of first-principles calculations when the lead–bismuth eutectic and the second phase precipitates coexist. The precipitates on the iron surface have a great effect on the surface properties, which can form the micro galvanic cell to cause electrochemical corrosion of the anode under corrosive conditions. The electrochemical corrosion was assessed by calculating the electrode potential of the half electrode (Fe surface). In addition, the effect of various alloy combinations on corrosion resistance was studied and a theoretical scheme for experimental design was proposed. Finally, in order to determine the electrochemical corrosion mechanism, the energetic, microstructural and electronic properties were analysed. The results show that the influence of Bi atoms on the surface electrode potential is greater than that of Pb atoms, and the existence of Al and Si atoms slows down the electrochemical corrosion of the anode to a great extent.