OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 4 2024 According to experimental data, with an increase in the degree of plastic deformation of compositions, cracks and delamination are formed in relatively large boride particles, which can contribute to its spalling and the formation of defects in the form of discontinuities, although no defects in the structure were observed before deformation (Figure 2). With an increase in the degree of plastic deformation, the boride particles are crushed with its alignment in the rolling direction (Figure 2, a, c, e). The chaotic distribution of boride particles after non-vacuum electron beam surfacing (Figure 2, a) and the rolling texture with boride orientation (Figure 2, b, e) confi rm the assumption above. Under the infl uence of high temperatures (950 °C) and large deformations (80 %), crushed borides that do not come into contact with the matrix material become sources of structural defects in the form of a grid of cracks and spalling during the preparation of thin sections (Figure 2, b, d, f). In addition, after hot plastic deformation, with an increase in the degree of deformation, borides with an irregular geometric shape (Figure 2, b) become smoother due to high temperatures and partial diff usion of elements (Figure 2, e, f). In accordance with scanning electron microscopy (Figure 3, a, b), the surface of the specimen after maximum plastic deformation is characterized by clearly marked traces of plastic fl ow and destruction of high-strength boride particles (Figure 3, c). Longitudinal broadening of the specimens is also observed (Figure 3, g) and the texture of the base metal 0.12 C-18 Cr-9 Ni-Ti (Figure 3, a), which is the result of high ductility of steel and is further confi rmed by X-ray phase analysis. Image analysis at maximum plastic deformation shows the presence of small cracks between the modifi ed layer and the base metal in the transition zone (Figure 2, b). Amore detailed examination of the transition zone (Figure 3, b) reveals a deformation texture, multiple grooves and etching pits. In the modifi ed layer, partial cracking of high-strength particles is observed simultaneously with its grinding (Figure 3, c). It can be assumed that such a structure is formed as a result of critical stresses and accompanying deformations. The thickness of the modifi ed layer decreases from 2.5 mm (Figure 1, a) to 0.5 mm (Figure 3, a). During deformation, the composition acquires a complex layered morphology and decreases in thickness by 7–8 times (Figure 3, a). The analysis of the results of the study showed that the plastic deformation of the composition begins with the base material, and then continues in the modifi ed layer. Also, with an increase in the degree of compression, borides are crushed by a brittle mechanism, and the base metal and matrix of the modifi ed layer are mainly viscous. The mechanism of destruction of high-strength boride particles and the matrix is the same at all degrees of deformation. Starting from 30 % deformation, the degree of crushing of boride particles and its partial destruction continues with an increase in subsequent rolling. a b Fig. 1. Structure of the specimens before plastic deformation: a – transverse section; b – frontal section
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