OBRABOTKAMETALLOV technology Vol. 27 No. 2 2025 These advantages make additive technologies one of the fastest-growing industries, as demonstrated by the annual increase in the proportion of additively manufactured parts used relative to those produced using traditional technologies [4, 5]. For mechanical engineering, the technologies that enable the production of metal products from powder are of the greatest interest, including selective laser sintering (SLS) and selective laser melting (SLM). Production using these methods has a number of significant disadvantages [6–8]: – low productivity; – high requirements for the granulometric composition of metal powders; – the need to print supporting structures, which then have to be removed; – the need to remove non-melting powder, which prevents manufacturing hollow parts with a closed circuit; – formation of pores inside the part; – differences in the mechanical properties of the part in parallel and perpendicular directions relative to the layers of the part; – high roughness of the resulting surfaces, which, if non-compliant with the specified requirements, requires additional treatment that may not be available for areas with complex geometry. Since the quality of the surface layer largely determines the operational properties of the product as a whole, high roughness is the main factor preventing the wider use of additive technologies [9]. Regardless of the chemical composition of the metal being fused during selective laser melting, surface roughness is formed as a result of the following factors [10–15]: – metal splashing from the melt pool; – spheroidization of liquid metal under the action of surface tension forces when the laser beam is removed from the melting zone; – incompletely melted powder particles with different adhesion to the surface; – non-molten powder particles stuck to the surface; – boundaries between individual layers caused by varying degrees of melting of powder particles located along the boundaries of each layer. Another significant problem with additive manufacturing is the high probability of pores appearing inside the product, which significantly reduces the strength properties of the product, especially if the pores are close to the surface. The treatment issues of such products are relevant and are reflected in many scientific papers that propose methods such as laser surface infusion [16], isostatic pressing, which is primarily used to densify the material [17, 18], various types of chemical action [19, 20], coating [21] and surface plastic deformation (SPD) [22]. The disadvantage of these methods is that they do not provide for the treatment of complex surfaces. For this purpose, one of the most effective methods is ultrasonic liquid treatment [23–24]. In this case, the working bodies are cavitation bubbles that can penetrate into any surface areas and modify them [25-26]. In modern research on this topic, two types of ultrasonic liquid treatment are considered [27-37]: cavitation-erosion (CET) and cavitation-abrasive (CAT). The results in all studies showed a decrease in various roughness parameters and a change in the morphology of the treated surface, manifested as a decrease in the number of defects on the surface. At the same time, the results vary greatly and are achieved with different treatment parameters: time from several minutes [27, 28, 31] to several hours [30, 37], and the amplitudes of ultrasonic vibrations from 5 µm [29] to 80 µm [33–34]. The best results are achieved with CAT at a distance of 1–2 mm between the end of the radiator and the treated surface, which is, in fact, dimensional processing and cannot be used for treatment of complex parts, or with CAT and CET combined with electrochemical polishing at high oscillation amplitudes of 60–80 µm [33–34], which leads to significant heating of the electrolyte, which, in turn, accelerates chemical reactions and makes it difficult to assess the contribution of ultrasound to the resulting effect.
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