Vibroplasma hardening of the working bodies of agricultural machines

Abstract

The article describes the technology of hardening the working bodies of agricultural machines based on the use of the electric spark energy and vibration arc discharges or the energy of vibroplasma. (Research purpose). The research purpose is studying of the influence of vibroplasma treatment on the physical and mechanical properties of 65G steel, which is the main material of many working bodies of agricultural machinery. (Materials and methods). The studies were carried out on samples from a coulter disk of 30x30 mm with a thickness of 2 mm. The processing was carried out at VDGU-2 technological installations of electric spark alloying in accordance with the patent of the Russian Federation No. 2655420 and vibration arc hardening. Tungsten-cobalt and copper-graphite rods with diameters of 4 and 8 mm were used as electrodes. (Results and discussion). In contrast to the initial sample, the spectrum of the relatively large area of the 65G steel sample hardened by electrospark treatment showed that cobalt (4.92 percents) and tungsten (16.83 percents) are present in the treated layer in appreciable amounts. Measurements of the elemental composition of the local processing zone showed that the main components of this region are tungsten (64.20 percents) and cobalt (7.55 percent). Carbon, nitrogen, oxygen, iron, manganese, calcium, silicon, aluminum, and a number of other elements are present in the surface layer of the sample with a vibratory arc treatment, but at lower concentrations in comparison with the listed elements for the sample with electric spark treatment. It has been found that the main phases are carbide and iron oxide, as well as metallic iron. After treatment with vibroplasma, there is a so-called zone of thermal influence near the treated zone. (Conclusions). The surface layer formed by processing parts by vibroplasma represents a new composite structure consisting of three layers. The hardening of the base material in the depth of the part during electrospark machining occurs at 0.5-1.0 millimeter, with vibroplasma machining it is up to 3-4 millimeter. The microhardness of the surface layer of products increased by more than three times.