INFLUENCE OF Cu AND Mn ON CORROSION BEHAVIOR OF LOW ALLOY STEEL IN A SIMULATED COASTAL ENVIRONMENT

Corrosion rates of 16Mn steel and Cu-Mn weathering steel in a simulated coastal environment are measured by wet/dry cyclic test.The rust layer was observed and analyzed by SEM,XRD and XPS.The experimental results show that the corrosion rate of Cu-Mn weathering steel was lower than that of 16Mn steel,due to the formation of a denser rust layer.The rusts on the two steels were consisded of Fe3O4,α-FeOOH,β-FeOOH,γ-FeOOH and amorphous.The amount of α-FeOOH and β-FeOOH in the rust of 16Mn was larger than in that of Cu-Mn steel.The addition of Cu increased the amount of Fe3O4,while the addition of Mn decreased the amount of γ-FeOOH in the rusts.XPS results show that,Cu existed in the form of CuFeO2;Mn existed as MnO in the initial stage,and then transferred to Mn3O4 after the rust layer stabilized.The synergetic effect of Cu and Mn improved the corrosion resistance of Cu-Mn steel.