Effects of Ultrasonic-Aided Quenching on the Corrosion Resistance of GB 35CrMoV Steel in Seawater Environment

The effects of ultrasonic-aided quenching (USQ) on the microstructure and corrosion properties of 35CrMoV steel in a simulated seawater environment (wt % (NaCl) = 3.5) were studied. The corrosion properties of the steel were studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. The scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to characterize the microstructure and corrosion products. Combined with the EIS equivalent circuit, the corrosion mechanism was investigated. The results show that the microstructure of the USQ specimen is small martensite and that there was no residual ferrite compared with an un-ultrasonic-aided quenching (UUSQ) sample. It was also found that the corrosion products of USQ sample are less than the UUSQ sample, and the corrosion cracks are lighter and thinner than that of the UUSQ sample, which indicates that the corrosion resistance of 35CrMoV in a seawater environment has been obviously improved.