Changes in Roughness and Microhardness of ShKh15 Steel after Pulsed Plasma Flow Treatment

Modern industry requires that the surface layers of bearing components made of ShKh15 steel be modified to increase their service life. This effect is obtained by enhancing the microhardness. Currently, the pulsed plasma flow treatment method is being intensively studied. The applicability of this method to bearing steel is limited by high requirements for the surface roughness of manufactured products. In this work, the effect of pulsed plasma flow treatment modes on the roughness and microhardness of ShKh15 steel at different thermal loads and numbers of pulses is studied. The goal was to determine the optimum treatment parameters for obtaining a combination of the maximum hardening with the minimum roughness change. According to the results obtained, after pulsed plasma flow treatment at certain parameters, a fourfold increase in microhardness can be achieved. In addition, when the melting threshold is reached, the roughness of the samples sharply grows. In addition, a series of experiments has been carried out to determine the impact of a number of pulses on the investigated characteristics. It has been found that, under irradiation of ShKh15 steel by several pulses, an increase in the number of impacts on the material provokes a decrease in the microhardness due to a change in the quantitative ratio between the phases. The roughness index varies within 10‒40%, while the values fluctuate chaotically.