Evolution Law of Corrosion Product Films of Q345qDNH Bridge Weathering Steel in Simulated Industrial Atmospheric Environment

The corrosion behavior and evolution of corrosion product film of Q345qDNH bridge weathering steel in simulated industrial atmospheric corrosion environment wered studied by wetting-drying cycle immersion corrosion test, and compared with Q345B steel. The results show that in the simulated process atmospheric environment, the corrosion mass loss of Q345qDNH steel decreased gradually with the extension of the wetting period, and tended to be gentle after 72 hours of corrosion. During the whole test period, the corrosion mass loss of Q345B steel was always greater than that of Q345qDNH steel. In the later stage of corrosion (120 h), serious pitting corrosion occurred on Q345B steel, while the rust layer on the surface of Q345qDNH steel was relatively complete, the film was dense, the protection effect on the metal matrix was more obvious, and the corrosion resistance was higher. The main components of corrosion products on the surface of Q345B steel and Q345qDNH steel were α-FeOOH, γ-FeOOH and Fe₃O₄, but the content of each component and the thickness of the film were different. With the increase of test time, the thickness of the inner layer of corrosion products on the surface of Q345qDNH steel increased significantly, and the oxidation products of Ni, Cr and Cu were enriched in the inner layer, which enhanced the compactness and stability of the oxidation film layer, thereby improving the corrosion resistance of the material.