OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 а b Fig. 8. Microstructure of VT23 alloy after LENS (P = 1,000 W; track distance 0.7L): a – laser scanning plane; b – cross section of the specimen Fig. 9. X-ray diffraction pattern of a bulk specimen at P = 700 W and 0.5L The study of the microstructure of the obtained bulk specimens allows us to conclude that there are no macro-defects. After LENS at a laser power of 1,000 W, the α-phase is observed in the form of areas of the so-called “basket weave” and areas of a mesh around primary β-grains (Fig. 8). Such structures are characteristic of this alloy both in the quenched state and after LENS [20–23]. Large (~ 100 μm) equiaxed regions of primary β-phase crystals are observed in the scanning plane. Similar structures were observed at other LENS modes as well. When analyzing the dependence of the microhardness of bulk specimens on the deposition mode, it was found that the hardness level at all modes is approximately the same, measuring 457 ± 23 HV (Fig. 7). Figure 9 presents the results of X-ray phase analysis. All specimens obtained by LENS modes exhibit (α + β) phase composition, where α and β are phases with BCC and FCC crystal lattices, respectively. Since the diffraction peaks of α’-martensite coincide with the peaks of the α-phase, it is not possible to definitively determine its presence in the structure based on the diffraction pattern. It is found that the amount of β-phase constitutes approximately 30 %.
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