Study of Initial Corrosion Behavior of Typical Wheel Steel in Neutral Salt Spray Environment

In order to solve the problem of atmospheric corrosion of wheel steels during their service，the initial corrosion behaviors of two kinds of automotive wheel steels 590CL and 780CL at 590 MPa and 780 MPa levels in neutral salt spray environment of 5% NaCl solution were studied by neutral salt spray test.The morphology， structure， corrosion rate and electrochemical behavior of corrosion products after salt spray test were characterized by glow spectrometer， metallographic microscope， scanning electron microscope (SEM)， X-ray diffractometer (XRD)and electrochemical measurement.Results showed that after 48 h in the neutral salt spray test， red rust appeared on the surface of the two wheel steels， and the corrosion rates of the two were 590CL＞780CL.The polarization curves and electrochemical impedance spectroscopy results measured in 3.5%NaCl solution were in good agreement with the above results.Besides， the corrosion products of 590CL and 780CL steels were mainly γ-FeO(OH)， and also contained some α-FeO(OH) and Fe3O4.However， the corrosion products basically had no protective effect on the substrate.