OBRABOTKAMETALLOV technology Vol. 27 No. 1 2025 The specimens were machined on a single precision lathe 16E20 (Alma Ata Machine Tool Plant, Alma Ata, Kazakhstan). A surface layer of 0.75 mm thickness was removed from the specimens, followed by contour turning with the following parameters: feed rate SX = 0.34 mm/rpm, spindle rotation speed n = 560 rpm, and cutting depth t = 0.25 mm. The contour turning, using a tool with a tip radius of 0.4 mm, resulted in a regular microrelief of the surface with the surface roughness parameters: Ra = 6.63 μm, Rz = 30.1 μm, Rmax = 33.7 μm, Sm = 0.260 mm, S = 0.055 mm, t30 = 11.6%. These values are consistent with rough machining. The selection of specimen processing mode was based on an analysis of previous studies, for example, [37]. Grooves with a depth of 3–4 mm were made on the specimens every 50 mm, to divide the specimen surface into sections. Similar specimens, made according to the above procedure, were used to study the effect of the tilt angle of the oscillating system on the change in the properties of steel 45 under the influence of ultrasonic SPD. After machining, the specimens were normolized at T = 860 °C. The microhardness on the surface of the specimens was 165 HV 20, and the core material, it was 125 HV 20. Experimental procedure and equipment Ultrasonic SPD was performed according to the scheme shown in Fig. 4. An ultrasonic oscillating system with a waveguide concentrator was mounted in the tool holder of the lathe. A rod-type, three-halfwavelength magnetostrictive oscillating system PMS-2.0/22 (Afalina LLC, Moscow, Russia) was used. It consists of a magnetostrictive transducer made of 49K2F alloy, located in a water-cooling casing, and a waveguide concentrator made of titanium alloy soldered to its end. To ensure the indenter is pressed against the workpiece surface with the necessary force, the oscillating system is equipped with a spring that provides a defined clamping force. A stepped titanium emitter with a transmitting surface diameter of ∅16 mm, which has a vibration amplitude amplification factor of ky = 2, was connected to the waveguide of the oscillating system via a threaded connection. A WC8 hard Fig. 4. Design of an experiment
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