Increasing the fatigue resistance of implants is an important scientific and technical problem. One of the solutions to this problem is the high-strength state formation due to the ultrafine-grained (UFG) structure. However, high-strength alloys are characterized by greater sensitivity to stress concentrators and the surface roughness parameter. In turn, implant designs, as a rule, imply the presence of concentrators in the form of various grooves, threaded elements, etc., and the manufacturing technology supposes mechanical processing with an ambiguous effect on a finished product surface. The application of additional surface finishing, for example, abrasive-free ultrasonic finishing (AFUF), is a solution to this problem. This work aims to study the effect of different AFUF modes on the microhardness and roughness of a cylindrical blank made of Grade 4 commercially pure titanium in the UFG state. During the study, the authors assessed the effect of the rotation frequency of a workpiece and the static force of pressing the tool against the processed workpiece on the surface parameters; carried out microstructural studies of the obtained samples. The results showed that processing titanium in the UFG state by the AFUF method leads to a significant increase in the surface microhardness and a decrease in its roughness. For example, depending on the mode, the increase in microhardness can reach from 2 to 3.5 times. The authors investigated the effect of a power level of ultrasonic treatment on roughness and microhardness and considered various variants of surface pretreatment. The study identified that an increase in the speed of rotation of a workpiece reduces the roughness of a machined workpiece, while the microhardness increases.

Recently, innovative medical techniques for restoring lost functions of patients have been actively developed, in which the use of bio-soluble (bioresorbable) materials is of particular importance. Such materials include alloys based on Mg, Fe, and Zn, and can significantly reduce the cost of surgical operations and shorten the duration of treatment. However, these metals have such disadvantages as insufficient strength and increased fragility to be used in medical implants. Therefore, increasing the mechanical characteristics of bioresorbable alloys is an urgent problem. In this work, the authors solve this problem using an advanced method of plastic treatment – severe plastic deformation (SPD), which, due to active initial structure refinement to nano- and ultrafine state, allows effective improvement of the mechanical strength of metal materials. The authors used the most effective and well-spread SPD method –equal-channel angular pressing (ECAP). The paper presents the results of computer ECAP research of Zn–4Ag–Cu zinc alloy at different deformation rates (0.4 and 7.8 mm/sec) and temperature conditions (150, 200 °C) chosen based on equipment performance potential and conditions to ensure thermal stability of the structure. The patterns of distribution of accumulated deformation degree, deformation rate, average stress values, and temperature-force conditions are obtained. According to the results of computer modeling, the authors recommended carrying out ECAP processing at the temperature of 150, 200 °C and a speed of 0.4 mm/s, which ensures a uniform thermal field at the deformation zone. During the experimental work according to the selected modes, the authors obtained samples after four ECAP cycles, which had advanced mechanical properties improving performance characteristics. The increased strength will allow minimizing the implants’ sizes ensuring less trauma during their installation and faster dissolution in the physiological environment of the body when retaining functionality.