Study On Wear-Resistance Performance Of Mining Pick Spray-Welding Coating By Plasma-Transferred Arc Weld-Surfacing

Mining pick is used as the cutting tool installed into shearers when cutting coals and drilling rocks.In the process of work,the picks endured the cyclical impact of coal seam,the severe friction and extrusion and alloy internal alternating thermal stress and so on,so its failure is serious.In some extent,the worn picks must be repaired or replaced.The failure forms of mining pick mainly include: wear,collapse,broken,fracture and so on.Among them the wear failure is the main form of the pick failure.Therefore,it is of great significance to improve the wear resistance performance and prolong its service life.Alloy powder including Ni60?WC?Cr₃C₂ and TiC with different mass ratio was deposited on medium carbon low alloy steel by plasma transferred arc welding?PTAW?.Through the experiments,the optimal alloy powder reinforcing cutter tool surface properties was discovered in the paper.It was analyzed on microstructures and hardness through the optical microscope?OM?,scanningelectron microscope?SEM?with Energy Disperse Spectroscopy?EDS?,X-ray diffraction?XRD?and microhardness tester.The wear-resistance properties were investigated on the impact abrasive wear tester.Besides,the scanning electron microscope?SEM?was employed to observe wear surfacemorphology,which was used to analyse the wear mechanism.Results showed that in terms of microstructure,there existed the shape of herringbone,spider mesh,broken flower structures in coatings.In addition,fusion area of four specimens surfacing welding layer appeared a large number of acicular martensite with a small amount of austenite,the middle layer of NO.3 specimen surfacing welding layer existed more austenite.Through X-ray diffraction?XRD?,the coating mainly consisted of Ni-Cr-Fe austenitic phase and the other precipitates,such as,boride hard phase?CrB,Ni4B?,carbide hard phase?WC,W3 C,Cr7C3,TiC?.TiC density was smaller,its content was less in alloy powder,in the process of surfacing welding,TiC was melted fully,which was mainly distributed in surface layer and middle layer of hardfacing layer.That is,the content of TiC gradually reduced from surface layer of hardfacing layer to the fusion area.Compared to TiC,the density of tungsten carbide and chromium carbide was larger,there existed tungsten carbide and chromium carbide particles,which were not completely melt near the fusion area.The microhardness presented gradient change from the fusion area to the surface layer of hardfacing layer,and the hardness of the middle layer was slightly lower than that of the fusion area,and the hardness increased near the surface layer.In terms of wear resistance,the four specimens were tested for abrasion resistance in the same operating conditions,The results showed that in the process of wear,the wear volume increased.In the early and late periods mass loss was smaller than that of the middle period,severe wear points were in the middle period.The mass loss of No.1specimen was the biggest among them.No.2 specimen was similar to No.3 specimen,their mass loss was smaller and wear resistance was higher.The mass loss of No.4 specimen was the smallest and its wear resistance was the highest.The wear mechanism of the specimens was dominated by abrasive wear,fatigue wear and adhesive wear by scanning electron microscopy.In addition,during the wear process,the specimens surface existed spalled pits,micro-cracks,furrows and other wear defects.