Surface Modification Of M2 High-Speed Steel By High Energy Density Beam

In order to improve hardness,wear and corrosion resistance, the surface of M2 high-Speed steel (W6Mo5Cr4V2)was treated by high intense pulsed ion beam (HIPIB) and high current pulsed electron beam (HCPEB). The microstructure and Properties (including micro-hardness, wear and corrosion) of surface layer on M2 high-Speed steel treated by HIPIB and HCPEB have been studied systematically. The effect of technical Parameter on the morphology and microstructure of the treated layer on M2 high-Speed steel has been analyzed,and the relationship between microstructure and properties has also been discussed. Before and after HIPIB and HCPEB irradiation the structure and morphology, the micro-hardness, the corrosion resistance, friction and wear properties were detected by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultra low load micro-hardness tester, salt spray corrosion and friction and wear testing machine. The experimental results show that:1. After HIPIB and HCPEB irradiation,the carbides in the surface layer dissolved,the carbon content in martensite increased,the martensite grain were refined or lattice distortion occurred , the residual austenite was obtained, and surface residual compressing stress was formed because of the intense surface quenching effect. With the increase of the pulses number,the surface of the targets became smoothing.2. After HIPIB and HCPEB irradiation,the micro-hardness was increased with depth of 200～250μm on the surface of M2 high-Speed steel due to the compress stress wave induced by the bombardment,so as to the slip friction coefficient of the irradiated surfaces was reduced and the wear resistance of them was increased significantly.At the same time, because of residual austenite increasing, corrosion resistance has also been improved significantly.3. The remelting layer on the surface of M2 high-Speed steel is affected by the process parameters of Irradiation. According to cross-section SEM image, there is a remelting layer with depth of 1～3μm on the surface of the irradiated samples, and the grains of the remelting layer are refined and the grain boundaries are blurry. The thickness of the treated layer increases with the increase of the numbers of pulses and the beam density.