SURFACE HARDENING OF POWDERED IRON-CARBON ALLOYS

Abstract

There are many ways to improve the quality of iron-carbon alloys used as structural materials, one of which is surface heat treatment with highly concentrated energy streams. The effect of electron-beam heating on the structure and properties of powder-metal ceramic materials was studied in this work. In order to solve this problem, the following tasks were solved: the study of the influence of the technological parameters of electron-beam processing on the structure and phase composition of the sintered materials on the basis of iron powder with graphite additions, determination of the influence of the thickness of the surface layer on the temperature gradient under the electron beam treatment of the material surface and formation structure, investigation of the influence of the chemical composition and the thickness of the surface layer on the hardness and microhardness of materials after electron beam processing. The advantages of electron-beam processing are shown in comparison with other methods of hardening the surface of parts. The influence of electron-beam processing regimes on the structure and phase composition of layered iron-based powder materials is studied. In the work the process of surface heat treatment of powdered laminated iron-carbon alloys is investigated. It was established that doping of a surface layer with carbide chromium allows to increase the surface strength of materials after treatment with an electron beam twice. Distribution of structural components of iron-carbon alloy under surface heat treatment depending on the thickness of the surface layer is investigated. Research results can be used to create economically alloyed structural iron-carbon alloys, which must have high surface hardness and high bulk strength. It is shown that in the middle of the samples the microhardness is practically the same for all materials and is about 3-4 GPa. On the surface, with a thickness of the upper layer of 0.5-1.0 mm, the average values of microhardness are about 5.0-5.5 GPa. With an increase in the thickness of the layer to 1.5-2.0 mm, the average microhardness reaches about 7.5-9.0 GPa. Surface hardness of materials also increases to 68 HRC with hardness in the middle of about 35-40 HRC. Research results can be used to create economically alloyed structural iron-carbon alloys, which must have high surface hardness and high bulk strength .