Effect of scanning speed on the organization and properties of CoCrFeNi fusion cladding layer

The effects of the scanning speed on the organization, hardness, and corrosion properties of laser-melted CoCrFeNi-fused cladding layers were investigated. In this paper, a CoCrFeNi high-entropy alloy cladding layer was prepared on the surface of the CX stainless steel substrate using laser cladding technology. The physical phase, microstructure, hardness, and corrosion resistance of the cladding layer were analyzed by an x-ray diffractometer, a scanning electron microscope, an energy dispersive spectrometer (EDS), a microhardness tester, and an electrochemical workstation. The effects of scanning speed on the organization and corrosion resistance of the cladding were further investigated. The results showed that good metallurgical bonding between the coating and the substrate was achieved at different laser scanning speeds, and no obvious defects were observed in the fused cladding layer, which was organized by columnar crystals and equiaxial crystals. The phase composition of the molten cladding layer did not change with the increase in scanning speed, and all of them were face-centered-cubic. With the increase in the scanning speed, the hardness of the fused cladding layer shows a trend of increasing and then decreasing; when the scanning speed is 6 mm/s, the hardness of the fused cladding layer is the largest, 203.1 HV 0.2, and at this time, the corrosion resistance of the fused cladding layer reaches the optimum, and the self-corrosion current density is the smallest, 3.6 × 10−8 A/cm2. When the laser power is set to 1400 W and the scanning speed is 6 mm/s, the corrosion performance of the fused cladding layer is better than that of the stainless steel substrate.