OBRABOTKAMETALLOV technology Vol. 27 No. 2 2025 Ultrasonic treatment methods result in significant profile changes, both in the shape of the profilogram and in the numerical values of the roughness parameters. After CET+CT, the surface profile is leveled and consists of similarly sized protrusions and depressions. This is due to the absence of spherical defects on the surface. The Ra parameter decreases to 19.3 µm. The profile after CAT+CT is characterized by fewer depressions and a larger number of protrusions deformed by the abrasive. Ra = 16.2 µm, representing a decrease of 43.5%. Additionally, the profilogram after this treatment method exhibits the lowest maximum profile height of 89 µm. The surface relief after ultrasonic SPD, due to the presence of large, flat areas, has the lowest value of Ra = 13.6 µm. However, the difference in the height of the protrusions and the depth of the depressions reaches 98 µm, which is greater than with CAT+CT. This indicates that combined cavitation and abrasive action is a more effective method for reducing surface protrusion height. Assessment of changes in the submicrostructure Three-dimensional images of the surface topography, measuring 308×308 nm (Fig. 11), were obtained by atomic force microscopy (AFM) using the Constant Height method. This method maintains a constant distance between the cantilever and the surface under study during scanning. These images allow assessment of the formation mechanisms of the studied surfaces. Fig. 11. AFM images of surfaces (308×308 nm) As a result of the flattening of spherical irregularities, the surface profile is leveled and consists of large, rectilinear sections alternating with depressions. In this case, the surface layer acquires several defects (hereafter, the defect number corresponds to the designation in Fig. 12): – discontinuity of metal at the points of contact of deformed spheres, appearing as vertical cracks; – discoloration of spheres under the influence of vibrations and shock loading; – partially deformed spheres with poor adhesion to the surface; – untreated deep depressions that increase roughness and may contain adhering powder particles. The deformed layer after ultrasonic SPD is approximately 90 to 100 µm thick. Without treatment, the sample has a lamellar microstructure typical of Ti-6Al-4V alloy, which is the same in the surface layer (Fig. 13, a) and the base metal (Fig. 13, b). After treatment, the microstructure of the material shows clearly marked traces of deformation (Fig. 13, c, d). Furthermore, the area of the surface without spheres (Fig. 13, c) is deformed to a greater extent than the area with spheres (Fig. 13, g), where the spheres themselves are deformed much more intensively than the underlying metal layer.
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