Differential analysis of the influence mechanism of ultrasonic vibrations on laser cladding

Although the laser cladding technology is widely used in various fields, the laser cladding layer is prone to pores, inclusions and microcracks, severely limiting the popularization and application of this technology. High-frequency mechanical vibration can effectively reduce the micro defects in the cladding layer and strengthen the solidification structure of the cladding layer. In this paper, a laser cladding system for a disc laser assisted by ultrasonic vibration is built, and the dynamic response of ultrasonic vibration of the cladding experiment platform is tested. A finite element model of the dynamic response of the cladding experiment platform under ultrasonic vibration was established, and the difference of the vibration of the experimental platform substrate at different positions under the ultrasonic vibration was calculated. The internal amplitude of the substrate is differentiated in a hemispherical shape with the vibration source as the center and is distributed under the influence of ultrasonic vibration. On this basis, the phase field method was used to establish the ultrasonic-assisted disc laser cladding solidification model to obtain the dendrite growth state during the solidification process. The calculation reveals the change law of single crystal and polycrystalline solidification growth under the influence of ultrasonic amplitude at different substrate positions. Calculations show that ultrasonic vibration can effectively increase the growth rate of dendrites and promote the formation of secondary dendrite arms. The polycrystalline solidification growth model is closer to reality. The competitive growth of dendrites suppresses the growth of primary dendrites to a certain extent and affects the selective growth of dendrites. The results show that the larger the ultrasonic amplitude, the more rapid the formation of secondary dendrite arms. (c) 2022 CIRP.