Surface Modification Of Cemented Carbide Cutting Toolstreated By High Current Pulsed Electron Beam

High current pulsed electron beam(HCPEB) plays an obvious role in material surface modification because of high power density and short pulsed time. The electron beam generates thermal stress and shock wavesand causes strong plastic deformation on the surface of target materials. Some special modification effects may be obtained during the modification by HCPEB. Therefore, we determine to investigate in detail the microstructures and properties of cemented carbide tools induced by HCPEB.Surface modification of YW2 and H13 A cemented carbide cutting tools were carried out through HCPEB with different pulsed times and energy density, and the microstructural, mechanical properties and cutting performance before and after HCPEBwas also investigated in this work. The evolution of phase composition and morphology of tool was tested by means of XRD and SEM, and the micro-hardness was measured. The effects of accelerate voltage, current, pulse number on the micro-hardness and roughness of carbide tools were optimized with response surface methodology.XRD results show thatbesides the strong peak of WC, Co and Ti C, there is weak of Co3W3 C on original insert. After the HCPEB treatments, the Co3W3 C and Ti C peak became higher than the original one, and he peaks of WC have a little shift to high angle, which implies there being higher residual compressive stress is introduced within theirradiated surface layer. The value of residual compressive stress of YW2 cemented carbide tool is 10.724 GPa,which is irradiated by HCPEB with 4.5J/cm2. The micro-hardness of modified layer induced by HCPEB is increased where is near to 100μm from the surface, and the maximum hardness is 2012 HV where is near to 20μmfrom the surface. In addition, the full width at half maximum(FWHM) of main WC phase’s peaks in irradiated samples widen to the original one, and the broadening of diffraction peaks can be caused by finer grains. SEM results show that in the melt layer, fine grain microstructure can be found and the WC phase cannot be clearly seen, and the melt layer depth is about 1μm. The roughness of surface treated by HCPEB is lower because of fine grain microstructure.The optimal parameters of YW2 tool are following: accelerate voltage of 10 k V, current of 180 A and pulse number of 45 times, and the optimal parameters of H13 A toolare following: accelerate voltage of 11.5k V, current of 120 A and pulse number of 50 times. Compared with the untreated tool, the irradiated YW2 and H13 A tool under optimal condition has higher micro-harness and lower roughness. The cutting property of the irradiated YW2 and H13 A tool under optimal condition has improved through the cutting tests of titanium alloy.