Microstructure and property of IN718/WCP composite coating fabricated by electromagnetic compound field-assisted laser cladding
SUN Wei1, HUO Kun2, DAI Fengze2*
1. National mould quality inspection and Testing Center, Suzhou, Jiangsu215316, China; 2. School of Mechanical Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
Abstract：The IN718/WCP composite coatings were prepared by electromagnetic compound field-assisted laser cladding. The macrostructure, microstructure, microhardness and wear resistance of the coatings were systematically studied. The results show that the electromagnetic compound field creates a downward Ampere force that enhances Marangoni convection in the molten pool. Enhanced Marangoni convection enables uniform distribution of WC particles in the composite coating. However, excessive Marangoni convection can cause WC particles, especially small WC particles, to escape from the molten pool. The combination of 20 mT steady magnetic field and 100 A direct current works well. The WC particles decompose in the molten pool to form submicron eutectic carbides, feathery eutectic carbides and equiaxed eutectic carbides. The degree of decomposition is related to the spatial location of the WC particles and the distance between particles. The higher the spatial position of the particles(relative to the molten pool), the greater the distance between particles and the more severe the decomposition. In addition, the direct current enhanced the nucleation rate of eutectic carbides and the enhanced Marangoni convection interrupted the long columnar eutectic carbides, which together refined the microstructure of the coatings. Under the action of the compound field(20 mT, 100 A), the diffraction intensity of reinforcing phases is the highest, and the microhardness(530 HV0.2)is greater than that of the coating prepared by unassisted laser cladding(400 HV0.2), which alleviates the adhesive wear during the friction and wear tests.
