Actual Problems in Machine Building. Vol. 9. N 1-2. 2022 Innovative Technologies in Mechanical Engineering ____________________________________________________________________ 30 SURFACE HARDENING OF STEEL GRADES Cr-W-Mn AND 40Cr BY THE METHOD OF ELECTROLYTE-PLASMA NITRIDING Smirnov V.M., Ph.D. (Physics and Mathematics), Associate Professor, e-mail: vms53@inbox.ru Lobanov D.V., D.Sc. (Engineering), Professor, e-mail: lobanodv@list.ru Busov A.I., Master’s Degree student, e-mail: sanches.05@mail.ru I.N. Ulianov Chuvash State University, 15 Moskovsky Prospekt, Cheboksary, 428015, Russian Federation Abstract The research results of the surface hardening of steel grades Cr-W-Mn and 40Cr by the method of electrolytic-plasma nitriding on the anode in an electrolyte from an aqueous solution containing 11% ammonium chloride and 11% ammonium nitrate are presented in this paper. The paper describes the scheme of the used laboratory installation for electrolytic-plasma heating and shows the dimensions and shape of the steel samples, on which the studies were carried out. The modes of electrolytic-plasma nitriding of samples made of the investigated steel grades are given. The simulation of the influence of Cr-W-Mn tool steel electrolyte-plasma nitriding modes is carried out by the method of a full factorial experiment. A regression equation is obtained that describes the dependence of the maximum microhardness of the surface layer of Cr-W-Mn steel on the electrodes voltage and the time of electrolytic-plasma heating. It is shown that the most advantageous factor that provides an increase in the microhardness of the surface layer of Cr-W-Mn steels due to nitriding is the electrodes voltage. The experimental dependences of microhardness on distance in the surface layers of Cr-W-Mn and 40Cr steels are analyzed. Keywords Electrolyte-plasma nitriding, surface hardening of steel, microhardness, aqueous electrolyte, full factorial experiment, regression equation.
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