Electrochemical Corrosion Behavior of NMZ1 Wear-resistant Cast Steel in Simulated Seawater

The corrosion resistance of NMZ1 wear-resistant cast steel was compared with that of the mooring chain steel (22MnCrNiMo) by observing the corrosion morphology and measuring the Tafel linear sweep and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution to reveal the electrochemical corrosion mechanism. The results showed that the corrosion resistance of the NMZ1 steel was worse than the mooring chain steel at the initial stage of soaking, the corrosion current density and the charge transfer resistance of the NMZ1 steel were 0.674 mA/cm2 and 265 Ω/cm2, respectively. The higher corrosion rate of the NMZ1 steel was due to the selective corrosion caused by the retained austenite and lower bainites existing in the microstructure. The corrosion current density and the charge transfer resistance of the NMZ1 steel were close to those of the mooring chain steel at the corrosion steady stage because of the protection of the compact corrosion product scale on the surface. It is hopeful to be widely used in marine engineering fields owing to the good comprehensive properties of the NMZ1 steel.