Reasearch On Performance Of Laser Cladding Mixed Powder With Co-based Alloy And WC

As a new surface modification technology, laser cladding has been widely used in thearea of parts manufacturing and repair because it can produce cladding layer with goodperformance. The metal-ceramic composite coating produced by laser cladding can providewell adjacent to the substrate and can service in extremely severe working conditions.In this paper, cobalt-base alloys with WC powder as cladding materials cladded on thesubstrate of304stainless steel by CO2laser and lateral powder feeding device wasprepared into laser cladding composite coating. The influence of laser technical parameterand WC content on the morphology、microstrcture、properties of cladding layer werediscussed. The microstructure、component distribution and phase composition of claddinglayer were analysed in detail through optical microsocopy（OM）, scanning electronmicroscopy（SEM）, energy dispersive spectroscopy（EDS）and X-ray diffraction （XRD）. Thehardness and its distribution of cladding layer was tested by Vickers hardness tester.Thewear resistance of cladding layer with different content WC were tested by abrasion testingmachine.The experiment results showed that with increasing the laser power, the dilution rateof cladding layer increased, the hardness first increased and then decreased. Withincreasing the scanning speed, the structure of cladding layer became finer, the hardnessfirst increased and then decreased. When the laser power was too high or the scanningspeed was too slow, the cladding layer would be overheated, conversely, the surface ofcladding layer was coarse, the internal combination was poor. When WC content increasedgradually, the solidification characteristic of cladding layer changed from hypoeutectic tohypereutectic finally, and the dilution rate of the cladding layer gradually increased. Thephase composition of cladding layer with0%WC was γ-Co、M₇C₃、CoC_xand W₂C, with20%WC was γ-Co、M₂₃C₆、CoC_x、M₇C₃、Co₃W₃C₆、W₂C and WC, with50%WC wasγ-Co、M₂₃C₆、CoC_x、M₇C₃、Co₃W₃C、Co₆W₆C、Fe₆W₆C、WC and W₂C. The hardnessof cladding layer increased with increasing of WC content, when WC content was60%,the hardness of upper cladding layer could reach above1200Hv. Wear resistance ofcladding layer increased with increasing of WC content. When the WC content was up to50%, cladding layer had the best wear resistance. However, When WC content increased to 60%, the wear resistance of cladding layer decreased slightly. The study showed that theroot cause of cracking in cladding layer was stress, cracks in cladding layer was belong tocold cracks. With increasing of WC content, the crack sensitivity of cladding layerincreased. The crack sensitivity of cladding layer could be reduced effectively bypreheating the substrate.