Ultrasonic treatment of the melt welding pool and heat affected zone (HAZ) is a hot research topic; however, it is hard to introduce ultrasound into working area. In this paper, the resonant method of introduction of ultrasonic oscillations with formation of a standing ultrasonic wave (frequency 18 kHz) was realized. Number of investigated technological parameters was minimized: welding current (180-240 А); the preheating temperature of the base metal (20-200 °С); length of the plate corresponds to the value of the acoustic wavelength (λ) in the low-carbon steel. Using different waveguides allows you to change the intensity of the ultrasonic treatment by varying the amplitude (ξ = 4.8; 9; and 18 microns). The effect of ultrasonic treatment on the melt metal of system Ni-Cr-C-B-Si and heat affected zone is studied. Formation of structure and properties for the hardfacing coating in an standing ultrasonic wave was considered. The microstructure of the treated area is significantly refined (the fragmentation of dendrites and inclusions was found). The effective technological parameters of ultrasonic field and plasma-arc hardfacing were established.

plasma-arc hardfacing, ultrasonic waves, microstructure, inclusion morphology, inhomogeneity of the structure, grain refining, heat affected zone, crack resistance.