Research on Microstructure and Properties of TiC/CoCrNi Coating by Laser Cladding on 45 Steel Surface
Yi-Wen Lei, Xiao-Long Li and Wei Niu
In order to improve the surface properties of 45 steel, laser cladding technology was used to prepare CoCrNi composite coatings with different TiC content on the surface of 45 steel using TiC powder and CoCrNi alloy powder as cladding materials. The phase composition and microstructure of the coating were studied by X-ray diffractometer (XRD), scanning electron microscope (SEM) and metallographic microscope (OM). The microhardness, friction and wear properties and corrosion resistance of the coating were measured. The results show that the phase of the coating was mainly composed of FCC solid solution phase when the content of TiC was 0%~5%. The phase of the coating was composed of TiC phase and FCC solid solution phase when the content of TiC was 15%~25%. TiC particles in the shape of irregular polygons, spheres and cross petals were uniformly dispersed in the coating. Due to the second phase strengthening effects of TiC, the average microhardness of the coating reaches the maximum value 401.5 HV0.3, which is about twice the hardness of the substrate 45 steel, and the minimum weight loss is 2.6 mg when the content of TiC was 25%. The wear form of the coating is mainly abrasive wear. With the increase of TiC content, the corrosion resistance of the coating decreases and then increases. The corrosion resistance of the coating is obviously better than 45 steel. When the content of TiC is 25%, the corrosion resistance of the coating is the best, the self-corrosion potential is -479.08 mV, the self-corrosion current density is 1.16×10-4 mA·cm-2. TiC/CoCrNi composite coatings possess excellent corrosion resistance and wear resistance, which can effectively improve the surface properties of 45 steel.
Keywords: 45 steel, laser cladding, CoCrNi, microstructure