OBRABOTKAMETALLOV Vol. 24 No. 4 2022 technology compressive region up to −100...−130 MPa. The depth of occurrence of the TRS at the same time is more than 0.55 mm. Since the CTT processes take place in the entire volume of the material and form a flat SSS of a homogeneous type, i.e. any direction in the processing plane is the main one, the components of the TRS should be the same in all directions. Similar diffusion layers obtained on the surface of 5CrNiMo and 3Cr2W8V steels by boroaluminizing can be classified as composite layers with heterogeneous dispersed morphology of the boride crystals arrangement [35, 36]. These layers are characterized by a complex distribution of microhardness in depth, explained by the gradient distribution of B, Al and alloying elements from the base steel [15]. It was shown in [15] that as a result of CTT on 5CrNiMo and 3Cr2W8V steels at a temperature of 1,050 °C and on 5CrNiMo steel at a temperature of 950 °C, diffusion layers are formed on the surface of the steel, in which solid structural components (borides and carbides) are arranged in a matrix of plastic phases (aluminides, solid solutions of aluminum and carbon in α-Fe). The obtained properties have a positive effect on the wear resistance of the working surface, however, the nature of the TRS distribution in the diffusion layers and its dependence on the SSS obtained as a result of the strengthening CTT remains understudied. As is known, tensile properties are unfavorable and can lead to cracks and destruction of the product, increase intercrystalline corrosion, contribute to fatigue failure, especially for parts operating under shock and alternating loads. In this case, it is necessary to provide a set of measures to reduce the tensile TRS after CTT or to form favorable compression TRS. As such measures can be proposed: subsequent heat treatment (tempering), quenching with subsequent tempering, plasma or laser treatment, elaboration of modes and technologies of CTT, etc. which will be a continuation of further research. Conclusions The main methods for determining the TRS in the surface layer after strengthening by the CTT methods of tool die steels 5CrNiMo and 3Cr2W8V are considered. Problems are identified in determining the TRS by mechanical method on the UDINON-2 installation in samples after diffusion boroaluminizing, and its solution are proposed. The expediency of using the anodic dissolution method for continuous removal of stressed layers from treated samples in the study of TRS by mechanical method on the UDION-2 installation is shown. The optimal electrolyte composition for the anodic dissolution process is selected, consisting of: NaNO3 – 60 g/l; NaNO2 – 5 g/l; Na2CO3 – 5 g/l; C3H8O3 – 15 g/l; H2O – the rest. The distributions of TRS normal components in the diffusion layer of samples from die steels after boroaluminizing are revealed. It is established that the formation of predominantly tensile TRS occurs in the surface layer of the CTT of these steels. Further research will be aimed at developing technological methods to reduce the tensile forces during diffusion boroaluminizing of die steels. References 1. Voroshnin L.G., Mendeleeva O.L., Smetkin V.A. Teoriya i tekhnologiya khimiko-termicheskoi obrabotki [Theory and technology of chemical and heat treatment]. Moscow, Novoe znanie Publ., 2010. 304 p. ISBN 978-594735-149-1. 2. Gagandeep S., Gurbhinder B. Modification of EN9 steel surface by salt bath nitrocarburising process. Journal of Materials Science and Surface Engineering, 2017, vol. 5, no. 4, pp. 577–580. 3. Zuno-Silva J., Ortiz-Domínguez M., KeddamM., Elias-Espinosa M., Damián-Mejía O., Cardoso-Legorreta E., Abreu-Quijano M. Boriding kinetics of Fe2B layers formed on AISI 1045 steel. Journal of Mining and Metallurgy. Section B: Metallurgy, 2014, vol. 50 (2), pp. 101–107. 4. Balanovskii A., Huy V.V. (2017). Plazmennaya poverkhnostnaya tsementatsiya s ispol’zovaniem grafitovogo pokrytiya [Plasma surface carburizing with graphite paste]. Pis’ma o materialakh = Letters on Materials, 2017, vol. 7, no. 2, pp. 175–179. DOI: 10.22226/2410-3535-2017-2-175-179. 5. KolosovA.D., Gozbenko V.E., Shtayger M.G., Kargapoltsev S.K., BalanovskiyA.E., KarlinaA.I., SivtsovA.V., Nebogin S.A. Comparative evaluation of austenite grain in high-strength rail steel during welding, thermal processing
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