Microstructure and Wear Resistance of Metal Matrix Composite Layer Fabricated by Simultaneous Powder-delivery Laser Melt Injection

Abstract:

Casting WC particles (WCp) were used as reinforced particle, 4Cr5MoSiV1 steel particles were used as metal matrixs, and Laser Melt Injection (LMI) was employed to produce WCp/4Cr5MoSiV1 metal matrix composite on Q235 steel. Microstructure of MMC layer was analyzed by X-ray diffraction (XRD), Optical microscopy (OM) and scanning electron microscopy (SEM), microhardness was tested along the depth direction of the coatings, pin-on-disk wear test was conducted at room temperature, and morphologies of worn surfaces was analyzed by SEM. Results show that the compound layer mainly comprises γ-Fe, WC, M2C, M6C, M23C7, (Fe,W)3C (M=(Fe, Cr, W, Mo), carbides exhibit different forms in the composite layer. The hardness of the compound layer is 723.74HV0.2, which is 4.6 times of the substrate and 50% higher than traditional hardened 4Cr5MoSiV1 steel. The average friction coefficient of MMC layer is 0.283, which is only 87.1% of the cemented carbide and 61.1% of the 4Cr5MoSiV1 steel. The relative wear rate is 43.45, which is 1.7 times of the cemented carbide and 43 times of the 4Cr5MoSiV1 steel.