Surface Modification Of M2 High Speed Steel By High Current Pulsed Electron Beam

High speed steel has high hardness,good wear resistance,excellent cutting performance and red hardness.As a tool material,it is widely used in modern machinery industry.With the rapid development of modern industry,there are more stringent requirements for the service life and performance of high-speed steel tools.Improving the surface performance of high-speed steel through surface modification technology is of great significance to improve the service efficiency of high-speed steel tools.High current pulsed electron beam(HCPEB)is a new type of energy carrying beam.It has developed rapidly because of its fast heating and cooling speed,high energy utilization,simple process control and suitable for local modification.HCPEB surface modification can produce 109 K / s temperature change on the material surface,750k/ μ M temperature gradient,a large amount of heat can be deposited in a very short time.At the same time,non-equilibrium phase transformation occurs on the material surface,which makes the surface composition tend to be uniform,weakens or even eliminates the surface segregation,produces ultra-fine grains and metastable structures,and optimizes the surface properties.In this paper,M2 high speed steel(W6Mo5Cr4V2 high speed steel)is used as the experimental material.After heat treatment,sample grinding and polishing,it is irradiated by hope-1 HCPEB equipment.The pulse times are 1,3,8,15 and 22 times,and the acceleration voltage is 24.5 k V.XRD was used for phase test and residual stress test,metallographic microscope was used to observe the surface macro morphology,laser confocal microscope and 3D surface profiler were used to test the surface crater morphology and surface roughness,SEM was used to observe the surface micro morphology and EBSD test,and then the surface friction and wear performance,electrochemical corrosion resistance,surface microhardness and red hardness were tested.The experimental results show that after 15 times of HCPEB pulse irradiation,the surface macro morphology of the sample is the most flat and smooth,and the roughness is the lowest;Combined with the results of XRD and surface micro morphology test,with the increase of HCPEB pulse times,the carbides on the surface of the sample are transformed,the content of residual austenite increases,the tempered martensite decreases,and the density of crater and molten hole decreases;The residual stress on the sample surface decreases with the increase of HCPEB pulse times;The section micro morphology test shows that the remelting layer depth of 15 pulse samples is the lowest and the most stable;EBSD test shows that the grain orientation uniformity of 15 pulse samples is the best;With the increase of HCPEB pulse times,the hardness,red hardness,friction and wear properties and electrochemical corrosion resistance of the samples were improved in varying degrees,and the best performance was obtained at 15 pulses.Based on the analysis of the experimental results,the surface modification effect of M2 high speed steel by HCPEB irradiation is the best when the number of pulses is 15.