OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 4 2022 a b c Fig. 4. Distribution of graphite in: a – SCh35; b – ChMN-35M; c – SChKM-45 (number 1 denotes graphite) alloyed with molybdenum according to the energy dispersive analysis. Vanadium is also recorded in the ferrite of SChKM-45 cast iron along with molybdenum. Nickel is evenly distributed over the volume of the studied materials. The result of alloying with molybdenum and nickel is an increase in the dispersion of lamellar pearlite. The reasons for this effect are reflected in [31–33]. The interlamellar distance is 2.2 µm and corresponds to PD1.6 in SCh35 cast iron.Alloying cast iron with molybdenum and nickel leads to a decrease of interlamellar distance to ~ 1.4–1.5 µm (PD1.4). Perlite observed in SChKM-45 cast iron alloyed with molybdenum, nickel and vanadium is characterized by an even higher level of perlite dispersion (PD1.0) [30, 34–36]. The results of measuring the microhardness of the volumes of structurally free ferrite and lamellar pearlite in the analyzed cast irons are presented in Table 4. A comparative analysis of obtained data allows to conclude that with an increase in the degree of alloying the microhardness of single structural components of the metal matrix increases [37, 38]. Structural analysis established that small amounts of primary cementite are present in SChKM-45 cast iron, the particle size of which is in the range from ~ 8 to ~ 35 μm (see Fig. 4, e). Works [31, 32] describe similar effect. The values of the friction coefficient and the weight wear of the friction pair elements were chosen as criteria characterizing the tribological properties of the analyzed materials. The test results of the samples are presented in Table 5. The obtained data testify the high tribological properties of SChKM-45 cast iron. The wear amount of samples from this alloy is approximately 1.3–1.8 times lower compared to SCh35 cast iron and 1.1–1.2 times lower compared to ChMN-35M cast iron. The efficiency of complex alloyed SChKM-45 cast iron used in friction pairs with steels 30CrMnSiA, 20MnL and 09Mn2Si was confirmed [39, 40–42]. The fractographic research data shown in Figs. 6 allow to conclude that the fracture of all specimens is brittle. The brittleness of the investigated alloys conditioned by the presence of graphite inclusions sharply
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