OBRABOTKAMETALLOV Vol. 24 No. 4 2022 technology a b c Fig. 6. The surface of specimens as a result of electrochemical etching of specimens made of 3Cr2W8V steel after CTT: a – composition No. 1; b – composition No. 2; c – composition No. 3 Investigation of TRS after diffusion boroaluminizing Control samples after annealing (Fig. 7) are characterized by the presence of compression TRS on its surface: for 5CrNiMo steel sample (Fig. 7, a) the compression TRS values lie in the range of −325…−570 MPa with a sharp rise and specifying near-zero values from a depth of 0.05–0.075 mm; for 3Cr2W8V steel sample (Fig. 7, b) these values are in the range of −155…−235 MPa. Moreover, the TRS plot after annealing of the 5CrNiMo steel plate is self-balanced (Fig. 7, a). After the CTT of 5CrNiMo steel at a temperature of 950 °C (Fig. 8, a), a diffusion layer with a thickness of 400–450 µm is formed [15], in which the TRS components are tensile. On the surface of the sample, it takes values of 210 MPa, at a depth of 0.08 mm it reaches a maximum of 620–687 MPa and gradually decrease, taking zero values at a depth of 0.9 mm. The depth of the TRS in this case is estimated to be within 0.5 mm. a b Fig. 7. Diagrams of residual stresses in a plate: a – of steel 5CrNiMo after annealing at 790 °C; b – of steel 3Cr2W8V after annealing at 880 °C
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