Microstructure and corrosion behaviours of composite coatings on S355 offshore steel prepared by laser cladding combined with micro-arc oxidation

The composite coatings were prepared on S355 offshore steel by laser cladding combined with micro-arc oxidation technology. The microstructure and corrosion behaviours such as immersion corrosion, corrosive wear of the as-prepared composite coatings were investigated, and the corrosion properties of the coatings were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The composite coating was well bonded with the substrate layer and showed good mechanical properties. The interaction between corrosion and wear was mainly corrosion accelerating abrasion in the substrate, while it was wear accelerating corrosion in the coating. The immersion corrosion mechanism of the cladding coating was pitting corrosion. When the current density was 5A·dm−2, the composite coating could significantly improve the corrosion resistance of the substrate.