THE INITIAL STAGE OF ATMOSPHERIC CORROSION OF CARBON AND WEATHERING STEEL IN BEIJING CITY ATMOSPHERE

This paper focuses on the initial corrosion behavior of carbon and weathering steel.The surface morphology of corrosion layer,corrosion products,structure and alloy elements of rust layer in natural city atmosphere were studied by metallographic observation,SEM and XRD.The results show that the rust layer of weathering steel was a little denser than that of carbon steel at the initial corrosion period.Two layers partly formed in both carbon and weathering steel after 25 days,there was no essential difference of corrosion products in both of them.The difference in rust layer was mainly due to the function of alloy elements.Cu,Cr elements were found in rust layer of weathering steel.They were concentrated in the cracks and voids,which prevented water,oxygen and pollutants penetrating to the steel substrate.