From the perspective of the influence of corrosion products on the corrosion process, the atmospheric corrosion of steel is a process in which the oxygen in the air undergoes an electrochemical reaction through the rust layer in the presence of a water film. The rust layer is composed of a loose outer rust layer and a dense inner rust layer, and the alloying elements in the steel mainly work through the influence of the inner rust layer. In the corrosion products of weathering steel, the enrichment of dense inner rust layer of Cu, P and Cr can be observed, and the high corrosion resistance of weathering steel is not only related to the high impedance of the inner rust layer, but also related to the dense inner rust layer, fine grain size and the enrichment of Cu and P. The presence of this dense inner rust layer is reflected in the electrochemical behavior of the steel, which is the retardation of the anode process. This process of gradually perfecting its compactness during the corrosion process just shows that the longer the time, the stronger the corrosion resistance.
