Experiment And Analysis Of Ultrasonic Assisted Laser Cladding Ceramic Composite Layer On Die Surface

H13 die steel in the long-term service process,the surface often appears pit,wear.When these defects are serious,the whole die will be scrapped and its life will be affected.In recent years,more and more researchers have studied the laser cladding WC nickel based coating,and found that it can greatly strengthen the surface of the material.However,due to the difference of thermal expansion coefficient between cladding powder and substrate,it is easy to produce large cracks and pores in the process of cladding.Therefore,these defects become urgent problems and research hotspots.In this project,ceramic cladding layer was prepared on H13 steel by preset coating method,and the influence of different WC ceramic powder particle size on the morphology,crack sensitivity and hardness of cladding layer was further explored.The ultrasonic vibration platform was designed and fabricated.The influence mechanism of ultras onic field on the cladding coating was explored by applying ultrasonic vibration to it:(1)Through the experiments of different laser power and scanning speed,the surface morphology and microhardness of the cladding layer were studied.The appropriate process parameters were determined as follows:laser current 120a,scanning speed 90 mm/min,defocus 6 mm,powder thickness 0.2 mm.(2)T The effects of powder size on the morphology,phase,microstructure and microhardness of laser cladding layer were studied.Research shows that when using 100 When the size of WC ceramic particles is 30?m,the volume of WC Ceramic Particles in the cladding layer is relatively large,and the fluidity is poor,which will cause serious composition segregation and internal stress in the cladding layer,resulting in the initiation of cracks,and the quality of the coating is seriously reduced.When the ceramic powder with smaller particle size of 30?m is used for the preparation of laser cladding coating,the dispersion of ceramic particles is better The surface forming is also good.The results show that the phases in the two kinds of cladding layers are basically the same,which are composed of?(Ni,Fe),WC,W₂C,Fe₅C₂,Mo₂C,Fe₇C₃,Ni₂Si,etc.It is found that the hardness of the cladding layer prepared by 100?m ceramic particles fluctuates greatly,and"short plate effect"is easy to appear in the application.(3)The influence of ultrasonic field on the macro morphology,crack sensitivity,corrosion resistance and hardness of the cladding layer was investigated by comparing and analyzing whether the ultrasonic field was applied or not.The results show that the application of ultrasonic field makes the reaction between WC Ceramic Particles and liquid metal more severe,the complex intermetallic compounds generated between the interface improve the wettability of WC Ceramic Particles and molten pool,and reduce the initiation of cracks;the application of ultrasonic field makes the self corrosion current density of the cladding layer change from 0.26 A?m² to 0.17 A?m²,the corrosion resistance is improved,and the hardness increases from 633.9 HV to 746.6 HV,the average hardness increased by 15%.