Corrosion Resistance Mechanism

From the perspective of the impact of corrosion products on the corrosion process, atmospheric corrosion of steel is a process in which 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. The alloying elements in steel mainly work through the influence of the inner rust layer. In the corrosion products of weathering steel, it can be observed that Cu, P, and Cr are enriched in the dense inner rust layer. The higher corrosion resistance of weathering steel is related to the high resistance of the inner rust layer and the dense and crystalline inner rust layer. The finer particle size is related to the enrichment of Cu and P. The existence of this dense inner rust layer is reflected in the electrochemical behavior of the steel, which is that the anodic process is blocked. This process of gradually improving its density during the corrosion process just shows that the longer the time, the stronger the corrosion resistance.