Laser Surface Cladding of Plastic-Molded Steel 718H by CoCrMo Alloy

With the purpose of enhancing the surface properties of plastic-molded steel 718H, in this study, a wear-resistant CoMoCr alloy cladding layer was obtained using laser surface cladding technology. Laser surface cladding was carried out by melting the CoMoCr alloy powder (particle size 15-45 μm) supplied through a pneumatically driven powder delivery system with a 5-kW continuous wave (CW) CO2 laser with the wavelength 10.6 μm. The microstructure, chemical composition, and wear resistance of the cladding coating were revealed by optical microscope (OM), scanning electron microscope(SEM), energy-dispersive x-ray analysis (EDX) and sliding wear machine. The microstructure of the cladding layer was found to consist of three zones: a top cladding zone mainly comprising CoMoCr; an internal zone comprising a cellular microstructure; and the interface zone which was a mixture of CoMoCr and 718H substrate. Compared to the 718H steel substrate with a microhardness of 345 Hv, the microhardness of the cladding coating showed a significant improvement, with its value increasing to 794 Hv. The wear results confirmed that the wear resistance was enhanced after laser cladding CoMoCr alloy powder.