Effect of Microalloying Element Composite Adjustment on the Corrosion Resistance of Q345qE Bridge Steel

In order to investigate the effect of microalloying element composite adjustment on the corrosion resistance of Q345qE bridge steel, the influences of alloy element Cr, Ni, and Cu composite adjustment on the corrosion resistance of Q345qE bridge steel were studied by confocal laser scanning microscopy (CLSM), electrochemical workstation, field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). Results showed that the compactness and protectiveness of the rust layer were improved after the composite adjustment of Cr, Ni and Cu microalloying elements. The Cr element in the rust layer on the Q345qE bridge steel surface could be enriched in the inner rust layer, which effectively blocked the penetration and transmission of corrosive ions such as Cl- and enhanced the protective ability of the rust layer on the substrate. After alloying element adjustment, the proportion of α-FeOOH that was more stable than γ-FeOOH in the rust layer of Q345qENH steel increased. Generally, Q345qE bridge steel with composite adjustment by microalloying elements possessed better corrosion resistance compared to ordinary Q345qE in 3.5% NaCl solution.