Low-Temperature Corrosion Performance of Laser-Cladded Co-WB Coatings in Simulated Seawater

In this study, using laser cladding technology, three different coatings with varying contents of spherical tungsten boride (WB) were completed on the EH40 steel substrate. These coatings included the Co coating, Co+15%WB coating, and Co+45%WB coating. The electrochemical corrosion performance of these three coatings was investigated in a low-temperature environment. The findings indicated that the phases present in the WB-reinforced Co-based coatings are mostly Cr₂₃C₆ and Cr₇C₃, WB, and WO₃, as well as γ-Co. The study showed that as the amount of tungsten boride in the coatings rose, their corrosion resistance increased and gradually dropped. Among them, the Co+15%WB coating exhibited the best corrosion resistance in a neutral solution. In the low-temperature (–20°C) immersion test, the main corrosion products for the Co+45%WB coating in simulated seawater solution were Co(OH)₂ and Co₃O₄, along with the presence of WO₂ and WO₃ oxides. Overall, the spherical tungsten boride coatings significantly enhanced the corrosion resistance of the EH40 steel substrate, providing an effective approach to improving the steel’s performance in low-temperature environments.