Abstract: Stellite-6, St6 in short, St6+5%WC, St6+5%WC+1%RE cobalt base self-fluxing powders were employed to enhance the H13 steel surface in CO₂ laser cladding process. The microstructure, elements distribution, phase composition etc. of the coatings were investigated using Optical Microscope (OM), Scanning Electron Microscope(SEM) and X-ray Diffraction (XRD).The micro-hardness and were-resisting property of the coatings were studied using micro-hardness tester and friction wear testing machine. The analysis shows that a metallurgical combination is formed between the laser cladding layer and the surface. All cladding coatings are composed of γ-Co and γ-Ni solid solutions as the matrix phase, Cr-Ni-Fe-C,(Mn, Cr)7C₃ and Cr₂₃C₆ as the wild phase. Furthermore, the phase compositions of St6+5%WC, St6+5%WC+1%RE also contain WC W₂C and SiC phases. The micro-hardness of the cladding is in the range 560~710 HV_0.2. Under the same testing conditions, the wear-resisting performance of the four materials is in the order: St6+5%WC+1%RE > St6+5%WC>St6>H13 steel.

Key words: metallic material, laser cladding, H13 steel, Co-based fluxed powder