Effect of Alloy Elements on Corrosion Behavior of Rebar under Chloride Salt Environment

Taking low alloy high strength corrosion resistant rebars and ordinary rebars as test objects, alternate environments of marine splash zone was simulated, wet and dry cycle immersion corrosion tests were performed in chloride salt environment. The surface morphology of the inner rust layer was observed with scanning electron microscopy (SEM), influence of alloy elements on the mechanism of corrosion behavior of the tested rebar was studied with electrochemical impedance spectroscopy and polarization curves, the structure of rust layer was analyzed with method of AC diffraction (XRD). Results show that the addition of Cr can reduce the self-corrosion potential of tested rebar, promote anode passivation and formation of inner rust layer in the initial corrosion stage, and decrease the average corrosion rate of the tested rebar. With the content of Cr increasing, the average corrosion rate of tested rebar becomes lower at the initial corrosion stage. The synergistic effect of Mn-Cu can enlarge the passivation range of steel bars and decrease average corrosion rate of steel bars, and the impedance of tested rebar increases rapidly in the middle and later corrosion stage, which can accelerate development of rust layer to the stabilization of rust layer of α-FeOOH and Fe₃O₄, shorten the formation time of the stability of stable rust layer, and reduce the corrosion rate in the middle and later stage.