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The corrosion behavior of a high manganese steel in simulated marine splash zone environment was studied by dry-wet cyclic corrosion experiment and electrochemical experiment. Corrosion kinetics, composition, surface morphology, cross-section morphology, element distribution, valence state, polarization curve and electrochemical impedance spectroscopy were analyzed with the aim of characterizing the characteristics of corrosion product films. The results show that in chloride-containing environment, in the initial corrosion products, Mn oxides with porous structure lead to higher corrosion rate. As corrosion extends, the formation of alloy element oxides in corrosion products changes the corrosion properties of rust layers at different stages. Mo oxides form a stable passivation film, which reduces the influence of chloride ion on corrosion. Ni oxides in the inner rust layer facilitate the transformation of goethite, and Cr oxides in the outer rust layer increase the densification of the rust layer. The stability and compactness of Fe3O4, α-FeOOH and FeCr2O4 in the later corrosion products inhibit the corrosion action of manganese iron oxides and slow down the corrosion rate. With the corrosion durations, the corrosion current density of the sample with the corrosion product film first increases and then decreases, and the corrosion potential first moves negative and then shifts in a positive direction subsequently, indicating that the protective effect of the corrosion product film is gradually significant.

Ni-Cu-P coating by chemical plating has excellent corrosion resistance,wear resistance, thermal stability and electrical conductivity. In this paper, Ni-Cu-P was prepared by chemical deposition methods, the optimum process of chemical plating Ni-Cu-P. By using scanning electron microscopy(SEM), spectrum analyzer, Autolab workstation on the corrosion resistance of the coating. The results showed that: (1)after the specimen surface chemical plating nickelcopper phosphorus treatment, in the same corrosion potential, the corrosion current density was lower than that of Ni-P coating and substrate materials; (2)had a significant effect on corrosion resistance of quantity of citric acid sodium on nickel copper phosphorus alloy plating, coating corrosion resistance with increasing citric acid sodium content first increased and then decreased, and inaddition level of sodium citrate is 40g/L, the corrosion current density reaches a minimum, 14.51×10–6A/cm2; (3)under the same conditions, the Ni-Cu-P alloy coating pH impact is the biggest,the maximum impedance 1268.05Ω; (4)in the 3.5%NaCl solution, with the change of copper content, the main trend of the corrosion current is decreased first and then increased, and the content of copper in Energy spectrum analysis within 5.18Wt% corrosion current density of a minimum of 14.51×10–6A/cm2, the corrosion resistance. With the increase of Cu content in the coatings, the P content first increased and then decreased in the coating, the content of Ni decreased first and then increased; (5)the best technology:NiSO46H2O, CuSO4 25g/L, 5H2O 0.15g/L, C6H5Na3O7•2H2O 40g/L, NaH2PO2H2O 25g/L, CH3COONa 15g/L, KIO3 0.03g/L, C12H25NaO4SO3 0.01g/L, pH4.75 ± 0.01,temperature 80 ± 1 °C, deposition time of 2h.