Ultrasonic assisted burnishing process is a newly developed alternative of conventional burnishing process that enhances the surface properties of engineering materials. The process needs careful selection of design parameters to improve the quality of surface layer of workpieces made of high-strength steel that are difficult to deform. The analytical models to predict the surface roughness after the ultrasonic assisted burnishing process for surfaces are developed. Feed, ultrasonic influence power and static static force could be considered as main factors influencing to surface roughness at that feed has the greatest impact among other parameters. The models are verified by experimental studies with various ultrasonic burnishing parameters. Technological parameters of the ultrasonic burnishing are found, which decrease surface roughness from 1-2 μm to 0.05-0.55 μm. It is experimentally proved that feed increase results in surface roughness increase. To low the surface roughness of high-strength steel workpieces it is necessary to increase ultrasonic influence power with simultaneous static force lowering. The analytical models obtained in the present work may be employed in determining the best conditions for ultrasonic assisted burnishing in industrial field.

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Fatigue, corroding and tribological properties of machine parts are mostly determined by surface quality formed during finishing operations. One of the most effective ways to form the required surface is by ultrasonic smoothing. The article presents experimental results of ultrasonic surface smoothing for workpieces of two types of steels 17Х18N9Т and 20Х1М1F1ТR. The experiments were conducted on the turning lathe with the experimental ultrasonic technological complex. The variables were workpiece rotational speed, feeding speed, clamping force and ultrasonic power treatment. D-optimal plan of Hartley-Kono was used during the experiment. Dispersion-regressive analysis of the experimental data revealed the relation between the surface roughness and processing regime modes. Feeding lowering decreases the surface roughness for both steels. To decrease the surface roughness of 20Х1М1F1ТR steel it is necessary to increase power of ultrasonic treatment simultaneously with clamping force decrease. For steel 17Х18N9Т clamping force results in surface roughness lowering that is why ultrasonic power is not significant. Partial correlation coefficient analysis revealed that micro profile height for steel 20Х1М1F1ТR is determined by feeding speed. For austenitic steel 17Х18N9Т feeding speed and clamping force are equally important factors. During the experiments the surface roughness decreased from 1.5 mkm to 0,1-0,2 mkm with ultrasonic treatment, that is more than 10 times.

The influence of the parameters of plastic deformation by ultrasonic burnishing during finishing treatment on the surface roughness of workpieces made of Р6М5 and 9ХС steels with an initial surface hardness of 57¸60 HRC is investigated. The D-optimal Hartley—Kono plan was used in the experiments for four factors (workpiece rotation frequency, feed, loading force, ultrasound power). Keywords: ultrasonic finishing, indenter, ultrasound power, surface roughness, plastic deformation zone. v.slutskov@narfu.ru