Lesyk D. Technological ensuring of the quality surface layer of parts by combined laser-ultrasonic treatment

In the thesis a method of the combined laser-ultrasonic hardening and finishing treatment of metals and techniques for maintaining a constant temperature in laser beam processing zone are suggested. It is possible to obtain a uniform depth of hardening and avoid undesirable overheating and melting of complex shapes and edges of the treated surface. Moreover, the consumed power source capacity was reduced by means of automated irradiated spot temperature control system. Technology of ultrasonic strain hardening using multi-pins heads that allows to improve the quality of the surface layer and increase the productivity of the thermo-deformation process hardening and finishing of large parts was suggested as well. The effect of the processing regimes of the combined laser and subsequent ultrasonic hardening and finishing treatment on the basic laws of microrelief formation, structure, hardness, the magnitude and distribution of residual stresses as well as wear resistance and corrosion resistance of steel parts was established. Based on the simulation results and experimental research, the algorithm for definition of the processing regimes for the combined laser-ultrasonic treatment of steel parts is developed.