Electron beam surface treatment of tool steels

In this work we present a combined method for surface modification on tool steel (0,31%C; 0,30%Si; 0,35%Mn; 2,9%Cr; 2,8%Mo; 0,5%V), consisting of electron beam treatment, plasma nitriding and subsequent electron beam treatment. The electron beam treatment has been performed on a Leybold Heraus (ESW300 - 15/60) installation, and the plasma nitriding - on an installation of the type ION 500. The structure of the processed samples has been investigated by X-ray diffraction analysis and scanning electron microscopy. The microhardness measuring is carried out by means of device MicroDuromat 4000 of firm Reichert-Jung. The results obtained in this study show the formation of Fe3N and FeN0.076 phases after EBT+PN and EBT+PN+EBT respectively. The transformation from Fe3N to FeN0.076 is due redistribution of the nitrogen atoms. The metallographic analysis demonstrates a formation of gradient layers with superior mechanical properties. The measured hardness reaches a value of 718 kg/mm2 for the case of EBT+PN and 679 kg/mm2 after EBT+PN+EBT treatment respectively.