Effect of Freezing–Corrosion Treatment on Wear Resistance of Laser-Cladded Cobalt-Based Coatings on EH32 Steel

Laser cladding on polar icebreaking ship steels that can work under low-temperature conditions has rarely been investigated. Herein, three types of the cobalt (Co)-based coatings with different chemical compositions and structures were fabricated on EH32 steel substrate by laser cladding. The influence of corrosion treatment at room temperature and freezing–corrosion treatment at a low temperature of −80 °C on the wear resistance of the EH32 substrate and the Co-based coatings was investigated. Results showed that the as-cladded Co-based coatings were composed of Co-based solid solutions and hard carbides such as Cr7C3, Cr23C6, Mo2C, WC, and/or W2C. Columnar dendrites with a 3D honeycomb-like structure and equiaxed dendrites occurred in the coatings containing WC and/or W2C. The Co-based coatings could significantly improve the hardness and wear resistance of the EH32 substrate, and the coating with the highest hardness possessed the best wear resistance. Both the corrosion and freezing–corrosion treatments could enhance the wear resistance of the Co-based coatings but weakened the wear resistance of the EH32 substrate. The Co-based coatings after corrosion treatment had superior wear resistance compared to the untreated coatings and the coatings after freezing–corrosion treatment.