## 1 Introduction  
Tool steels have improved performance characteristics and, nevertheless, they are subjected to additional strengthening treatment to solve technological problems. CrWMn steel is one of the common grades of tool steel. Products made from this grade of steel and its analogs are subjected to cryogenic treatment [1, 2], laser treatment [3, 4], electron-beam treatment [5], and ion implantation [6]. One of the promising methods for modifying the surfaces of metals and alloys is plasma electrolytic treatment (PET). This method has found application for obtaining protective ceramic-like coatings on the surfaces of valve metals [7, 8, 9, 10], reducing roughness by polishing [11, 12, 13], as well as changing the structural and phase composition of the surface layers of steels and titanium alloys. In the latter case, a type of chemical-thermal treatment is considered, when the saturating and heating area is electrolysis plasma. Depending on the type of diffusion saturation, nitriding, carburizing, boriding, or a combination of these methods are carried out. This technology has found application for increasing the hardness, strength, wear resistance, and corrosion resistance of products made from carbon [14, 15, 16, 17, 18, 19, 20, 21] and alloy [22, 23, 24, 25] steels and titanium alloys [26, 27]. Regarding the case under consideration with alloy steels, it was shown that during plasma electrolytic carburizing of steel H13, Fe\({}_{3}\)C, FeC, and Fe\({}_{1.88}\)C\({}_{0.12}\) carbides are formed [28], and during carburizing of steel 30 CrMnSiA, Fe\({}_{5}\)C\({}_{2}\) carbide is formed [29]. The use of aqueous electrolytes leads to the formation of oxides on the surface. Thus, after the carburizing of T8 steel, the FeO, Fe\({}_{3}\)O\({}_{4}\), Fe\({}_{2}\)O\({}_{3}\), and Fe\({}_{3}\)C phases were discovered [30]. As a result of plasma electrolytic nitriding of 316L steel, iron FeN\({}_{0.076}\) nitride and Fe\({}_{3}\)O\({}_{4}\) oxide were discovered [31]. After plasma electrolytic nitrocbarurizing of this steel, nitrogenous austenite is revealed as the main phase [32]. Additionally, NiFe\({}_{2}\)O\({}_{4}\), FeCr\({}_{2}\)O\({}_{4}\)[33], Fe\({}_{2}\)O\({}_{3}\), Fe\({}_{3}\)O\({}_{4}\), Cr\({}_{2}\)O\({}_{4}\)[34], Fe(Fe,Cr)\({}_{2}\)O\({}_{4}\)[35; 36] oxides, Fe\({}_{3}\)N [34], CrN Cr\({}_{2}\)N [36] nitrides, Cr\({}_{3}\)C\({}_{2}\), Cr\({}_{7}\)C\({}_{3}\)[36] carbides and silicon dioxide [34] are detected. As a result of structural and phase changes, performance properties improve. For example, after plasma electrolytic nitrocbarurizing of 30 CrMnSiA steel, hardness and wear resistance increase due to the formation of finely dispersed FeN, (Fe,Cr)\({}_{3}\)C and Me\({}_{23}\)(C,N)\({}_{6}\) secondary phases [37]. Plasma electrolytic nitriding reduces the intensity of adhesive wear of 34 CrNiMo steel [38] and 38 CrMoAl steel [39]. This paper examines the possibility of increasing the wear resistance of the surface of CrWMn tool steel by plasma electrolytic treatment due to the formation of a modified layer that will compensate for the contact effect of the counter body on the treated surface. Plasma electrolytic nitriding (PEN) is considered a method of diffusion saturation. As an original aspect of the study, it is proposed to combine PEN with plasma electrolytic polishing (PEP) by changing the electrophysiological processing parameters. The use of PEP after diffusion saturation has previously been shown to be effective in improving the wear and corrosion resistance of low- and medium-carbon steels by removing irregularities and loose areas of the surface oxide layer, as well as reducing surface roughness [20]. High-carbon steels, in particular CrWMn, do not require diffusion hardening of the surface to increase wear resistance, as in the case of low- and medium-carbon steels. When a hard surface layer is formed on a more plastic substrate, it compensates for the impact of the counter body and prevents the occurrence of deformations and destruction of the material.