PSI - Issue 81

Anatolii Babinets et al. / Procedia Structural Integrity 81 (2026) 353–359

358

such microdefects is 5 –20 µm. In specimen No. 5 (particle size 50–100 µm), the structure is more homogeneous, microdefects are isolated, and do not exceed 1 µ m (Fig. 6b), which leads to an increase in the microhardness of the metal. This can be explained by the fact that melting fine-dispersed core particles of the MPW (50 –100 µm) requires less heat than in the case of a wide granulometric composition and the presence of large particles (200 –300 µm). As a result, the melting process occurs more uniformly, arc stability and heat transfer intensity to the molten pool increase, promoting better dissolution of components and the formation of defect-free deposited metal.

a

b

Fig. 6. Areas of the microstructure of the deposited metal with characteristic microdefects: (a) specimen No. 1 (reference); (b) specimen No. 5 with optimized B ₄ C additive content and granulometric composition. Magnification ×300. Considering the above, when evaluating the influence of B ₄ C modifying additives and the granulometric composition of the MPW core on the performance properties of deposited metal of the 50Cr2Ni2MoVSi type, the maximum boron content in the specimens was limited to 0.01% to avoid crack formation. The investigation of performance properties (heat resistance and wear resistance under high-temperature friction according to the “metal– metal ” scheme) was conducted for three groups of specimens deposited with the following MPWs: No. 1 – reference, without addition of modified particles, granulometry 50 –300 µm; No. 2 – with 0.01% B ₄ C additives, granulometry 50 –300 µm; No. 5 – the same, granulometry 50 –100 µm. It was experimentally established that the introduction of 0.01% B ₄ C additives positively affects the heat resistance of deposited metal of the 50Cr2Ni2MoVSi type. In specimen No. 5, deposited using an MPW with an optimized core granulometric composition, thermal fatigue cracks initiate at later stages and are characterized by smaller length and number compared to specimen No. 2 of the same chemical composition, deposited with MPW of standard granulometry (Fig. 7a).

a

b

Fig. 7. Heat resistance (a) and wear resistance under high- temperature friction according to the “metal–metal” scheme (b) of specimens deposited with MPWs with cores: 1 – without modifying particles, granulometry 50 –300 µm; 2 – 0.01% B, granulometry 50 –300 µm; 5 – 0.01% B, granulometry 50 –100 µm. A positive effect of introducing 0.01% B ₄ C additives on the wear resistance of deposited metal of the 50Cr2Ni2MoVSi type under high- temperature friction according to the “metal–metal” scheme has been noted. Due to the increase d hardness of the deposited metal, the absence of defects, and the greater homogeneity of the structure, the wear rate of the specimen decreases, and wear occurs more uniformly. This is confirmed by a 1.2-fold reduction in specimen mass loss (Fig. 7b) and a 2.0-fold reduction in the mass loss of the ring (counterbody) in the friction pair with the specimen. Thus, introducing an optimal amount of B ₄ C modifying additives into the MPW core and optimizing its granulometric composition ensure an improvement in the performance properties of deposited metal of the 50Cr2Ni2MoVSi type, in particular heat resistance and wear resistance under high- temperature friction according to the “metal–metal” scheme, by 15– 20% compared to the reference material. This indicates that surfacing with modified MPWs is an effective method for enhancing wear resistance, compared to other known surface treatment methods (Bhadauria et al. (2020), Nykyforchyn et al. (2021), Kyryliv et al. (2023), Maksymiv et al. (2023)).