Corrosion and cracking behavior of high strength steel covered with high- velocity oxygen- fuel spraying WC coating in marine environment

In order to explore the adaptability and failure mechanism of landing gear materials for amphibious aircraft in the marine environment. By preparing a high-speed flame sprayed WC coating on the surface of hot-rolled 300M high-strength steel, the corrosion behavior of the coating in an artificial seawater environment was studied using electrochemical testing,salt spray testing,tensile testing,fatigue testing, and characterization by SEM,EDS,XRD,and CLSM. The research results indicate that the WC coating undergoes significant passivation and exhibits good corrosion resistance in an artificial seawater environment with pH value 8. 2,which is related to the passivation of Co in the coating under alkaline conditions. The long-term electrochemical impedance results indicate that the corrosion resistance of the coating increases after soaking for 28 days,which is related to the oxide formed by the surface binder. Compared with the 300 M substrate,the tensile strength of the sprayed material slightly increases,which is related to the residual stress releasing inside the coating. Its cracking in artificial seawater is mainly controlled by the anodic dissolution process. As the pre corrosion time increases,the fatigue life of the material significantly decreases. The corrosive medium from the environment enters the interior of the coating during the pre corrosion process,which increases the number of defects,causes premature failure of the coating,and leads to an increase in material fracture sensitivity. WC coatings have good corrosion resistance,and the release of residual stress during the tensile process slightly increases the tensile strength of the material. The coating fails prematurely after pre corrosion,which results in a reduced fatigue life of the material.