Effect of high-speed laser cladding on microstructure and corrosion resistance of CoCrFeNiMo0.2 high-entropy alloy

In order to study the corrosion resistance of high-speed laser cladding (HLC) coating while improving production efficiency, a CoCrFeNiMo 0.2 high-entropy alloy (HEA) coating was prepared by HLC. The optimized parameters of HLC are laser power of 880 W, scanning speed of 18 m/min, overlapping ratio of 60%, and powder feed speed of 3 r/min. Then, the surface roughness, microstructure, phase composition, element distribution, and electrochemical properties in 3.5 wt% NaCl solution of the coatings were analyzed, respectively. The local surface roughness of the CoCrFeNiMo 0.2 HEA coating was found to be 15.53 µm. A distinct metallurgical bond could be observed between the coating and the substrate. Compared to the conventional laser cladding (CLC), the results of electrochemical tests showed that CoCrFeNiMo 0.2 HEA coating exhibited a significant passivation. The corrosion current density of 5.4411×10 −6 A·cm −2 and the corrosion potential of −0.7445 V for the HLC coating were calculated by the Tafel extrapolation method. The CLC coating’s corrosion current density and corrosion potential are 2.7083×10 −5 A·cm −2 and −0.9685 V, respectively. The HLC coating shows a superior corrosion resistance, crucially due to the uniform and fine grains. Under various complex and harsh working conditions, this method can be widely used in the field of repairing and remanufacturing of corrosion-proof workpieces.