Effect of laser pretreatment and laser cladding on the interface bond strength and surface properties of vermicular graphite

The surface properties of laser-cladded vermicular cast iron are close to application requirements, particularly for automobile engines, and laser-deposited wear-resistant coatings have a low interface strength. To address these limitations, this paper proposes a laser-pretreated (laser fusing and secondary laser heat treatment), laser-deposited, wear-resistant coating method to better improve the surface properties and interface bonding strength of vermicular graphite. The interface bonding strength was improved by laser pretreatment, and the material’s surface properties were improved by laser-deposited, wear-resistant coating. The macroscopic and microscopic structures of weld joints were characterized using optical microscopy, scanning electron microscopy, and X-ray diffractometry. The cladding layer’s bonding strength was tested using a universal tensile test machine. The microhardness of workpieces was measured using a microhardness tester. The experimental results indicated that the wear volume of a Ni45 + 5% WC coating applied using laser cladding was significantly lower. The Ni45 + 5% WC coating also exhibited better wear resistance, with a value that was 1.6 times higher than that of a laser-fused layer. Based on a coating bonding strength test, the average bonding strength of the laser-cladded coating on the fused layer was approximately 1.56 times that of laser-cladded vermicular graphite cast iron.