OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 4 2024 step of 5 % and the minimum deformation degree of 30 %, the maximum degree of deformation of 80%. When deformed by less than 30 %, there were no signifi cant changes in the structure and appearance of the workpieces. When deformed by 80 %, the maximum possible degree of plastic deformation is observed for the specimens “modifi ed layer – base metal”. Based on the scientifi c literature, the temperature for plastic deformation was chosen as 950 °C as the minimum temperature to ensure the plasticity of the substrate (0.12 C-18 Cr-9 Ni-Ti) and the relative plasticity of the modifi ed layer. In addition, deformation at 950 °C avoids overheating of the material and grain coarsening in the base metal. Metallographic studies were performed using the Axio Observer Z1m Carl Zeiss microscope. The determination of the phase composition and structure was studied at the station “Rigid Fluoroscopy” of the Siberian Center for Synchrotron and Terahertz Radiation at the G.I. Budker Institute of the INP SB RAS. Diff raction analysis was performed at room temperature in a translucent mode. The radiation energy was 56.35 keV, the beam size was 500×500 μm, and the distance to the studied material was 353 mm. The Mar345 detector was used to register diff racted radiation. After the study, two-dimensional diff raction patterns were integrated using the open source pyFAI software [21]. The profi le analysis of diff raction maxima was carried out using the pseudo-Voight function, with subsequent calculation of the crystal lattice parameter using the matrix method. To identify the features of the boride particles location in the structure of the modifi ed layer, a Carl Zeiss EVO50 XVP scanning microscope was used. The studies were carried out in the backscattered electron diff ractionmode, the chemical composition was determined using the EDX X-Act energy dispersion analyzer. The microhardness of the modifi ed layers obtained was measured using the Vickers method in accordance with GOST 9450-76 at a load of 0.98 N on a Wolpert Group 402MVD micro-hardness tester. At least 5 tracks with 10 indentations were made on each specimen. Results and discussion The most eff ective temperature range for deformation of chromium-nickel steel is 950–1,100 °C; it is in this temperature range that the processes of dynamic recovery and recrystallization have time to occur, and there are no local melting areas with defects that lead to destruction. Figure 1 shows the structure of transverse sections of modifi ed layers obtained after surfacing a powder mixture of composition 10Cr-30B, which is a composite material with a dense arrangement of boride particles. A matrix composite material is understood to be a sample of a “modifi ed layer – base metal” (Figure 1, a). Borides act as a strengthening phase in the modifi ed layer. The density of the boride particles was assessed visually (Figure 1, b). The modifi ed surface layer with a thickness of up to 2.5 mm is connected to the main material by a transition zone with a thickness of 100-150 microns. The structure of the modifi ed layer contains borides that do not have the correct geometric shape, which can be explained by the collision of crystals during their growth. The transition layer is a eutectic, the components of which are austenite and boride crystals. Ta b l e 2 Modes of non-vacuum electron beam surfacing Parameter Meaning The energy of the electron beam, E 1.4 MeV Specifi c energy, Ese 6.44 kJ/cm2 Powder weight per unit area, m 0.33 g/cm2 The scanning frequency of the electron beam, ν 50 Hz The distance from the outlet to the workpiece, h 90 mm The speed of movement of the table with the specimen, V 10 mm/s
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