Researchon Microstructureand Propertiesof Fe Based Wear Resistantcoating By Laser Deposition

At present in manufacturing,in order to improve the properties of the surface where on the medium carbon steel materials which as the key components,the high frequency induction quenching process is often adopted to strengthen the surface.But the overloaded parts increase sharply and the working conditions getting worse resulting in significant wear as developed machinery equipment on which the aspects of small volume and high power oriented,thus,the high frequency hardening technology has been unable to fully satisfied the requirements when we used.However,in terms of enhancing the fatigue life of the components,the technology of the laser cladding not only could deposit the high quality wear resisting alloy layer on the surface of the key components but also can adding hard particle phases to improve the wear resistance property.Moreover,these technologies can achieve the precise controlling in terms of the thickness and location to various coatings.Thus,this is an effective means to improve the performance of the key components.This thesis describes testing of 42 CrMo coupons in laser cladding processing using the high power CO2 laser and coaxial powder feeding devices under the same processing parameters in the various iron-based powders which include five kinds are that Fe106,Fe106+Ni/WC,Fe106+rare-earth,Fe106+MoS2 and Fe106+(W+C).The laser cladding processing tests were performed using a metallographic microscope,scanning electron microscopy,x-ray diffraction,friction and wear testing machine,electrochemical workstation and others equipment.And then the data generated to compare the residual stresses,microstructure,phase composition,wear resistance and corrosion resistance encountered for each.The object of the tests is that the properties of the coating of the iron-based powders can be defined under the situations of the various compositions.Under the conditions of which are the P=2.5kW,v=0.3m/min and different composition ratio in the iron-based powders,where P and v are the laser power and laser scanning speed,the conclusions are summed up through the data: On the one hand,comparing with the initial coatings which is Fe106,the wear resistance property of the various coatings is enhanced in various degree because of adding the hard particle phase and the function of the grain refining except that the wear resistance property significant decrease with the speed of sulphuration increasing on the MoS2 coating.On the other hand,comparing with the high frequency induction quenching process,the wear resistance property of the various coatings are enhanced in various degrees because of adding the hard particle phase and the function of the grain refining except that the wear resistance property isn't enhanced with the coarse grain,and less hard particles on the Fe106,and Fe106+(W+graphene/carbon nanotubes)coatings,respectively.