Applied Physics and Mathematics Annotation << Back EVOLUTION OF THE GRADIENT MICROSTRUCTURE OF 35KHGS STEEL DURING MECHANICAL AND THERMAL TREATMENT A.S. GLINKA, D.A. ROMANOV, E.S. VASHCHUK In this paper, the results of the study of the grain structure, intragrain defects, the state of the carbide phase, the states of the solid solution of the α-phase are presented; detailed information was obtained on the phase transformation of a single carbide in steel – cementite – during the mechanothermal treatment of steel 35HGS according to the specified modes. The surface of the product contains a volume fraction of cementite particles located at the boundaries of fragments and whose size is ~ 10 nm, equal to 0.6 %, and the volume fraction of cementite particles located randomly in the volume of the material and whose size is an order of magnitude higher (~0.1 microns), 0.2 %. Regardless of the mode of mechanical processing, the morphological components are perlite and ferrite. The basis of the material after any of the processing modes is perlite, the volume fraction of perlite is 70 % in roughing modes and, depending on the combination of operating parameters, decreases to 55–43 %. Keywords: 35KHGS steel, structural-phase state, mechanical-thermal treatment. DOI: 10.25791/pfi m.05.2024.1309 Pp. 25-38.