The Microstructure And Mechanical Properties Of Wc Coating Welded By TIG Welding

With the development of modern science and technology,single engineering materials such as metal,ceramics and polymer can hardly meet the material performance requirements of key components.In order to overcome the limitation on the performance of single material and give full play to the properties of various materials to make up for their deficiencies,composite materials emerge at the right moment.In this paper,the wear and impact resistance particle reinforced metal composite was prepared by tungsten inert gas welding.The microstructure of the surfacing layer was analyzed by optical microscope,scanning electron microscope and X-ray diffraction.The hardness,wear resistance and toughness of the surfacing layer were measured by Vickers hardness tester,wear test and impact test.After mixing tungsten carbide particles with a small amount of nickel powder to make a flux cored wire with a diameter of 1.6 mm,and then adjusting the TIG welding parameters,a uniform distribution of tungsten carbide layer can be prepared.Tungsten carbide particles in the layer are divided into three forms:undissolved,partially dissolved and completely dissolved.Corresponding micro-hardness is respectively 2474.7 HV_0.1,1456 HV_0.1 and 735 HV_0.1.The average hardness of the substrate of the layer is 616.6 HV_0.1.Element diffusion occurs between the undissolved and partially dissolved tungsten carbide particles and the matrix,resulting in metallurgical bonding between the tungsten carbide particles and the matrix.The matrix plays a good supporting role for the tungsten carbide particles,while tungsten carbide protects the matrix from the role of friction pair,thus improving the wear resistance of the cladding layer.The fully dissolved tungsten carbide can improve the wear resistance of the matrix by forming a cast structure with higher hardness when solidifying with the matrix.In the case of grinding with GCr15 steel wheel,the wear volume of the overlaying layer is only 1/50 of the base metal.In addition to abrasion resistance,the composite material itself also has good toughness.Through the impact test,the overall impact energy of the composite material was measured to be about 96 J,the cladding layer was brittle fracture,and both the heat affected zone and the base metal were ductile fracture.