Ultrasonic Induced Cavitation Modification Mechanism And Experimental Research Of AZ31B Magnesium Alloy

Ultrasonic cavitation modification is the use of ultrasonic as an energy source to cause the shock wave or micro-jet released by the cavitation bubble generated in the liquid medium to continuously impact the surface of the metal material,causing strong plastic deformation on the surface of the material in order to achieve the modification of the surface of the material.Different from the common electroplating and melting modification methods,ultrasonic cavitation modification is a new modification method which is only obtained by mechanical means on the basis of the material itself without introducing new external substances.In order to carry out a comprehensive and in-depth study on the mechanism of ultrasonic cavitation modification,the impact models of micro-jet and shock waves on materials were established and the residual stress field formed was numerically simulated.Finally,the process parameters of ultrasonic cavitation modification were studied.The influence law of the material properties of the material was tested experimentally.Based on the theoretical knowledge of ultrasonic cavitation,this paper introduces the cavitation mechanism and cavitation dynamics.The mechanism of plastic deformation and residual stress caused by ultrasonic cavitation bubble collapse impact on the material and the surface grain size of the material are discussed.The impact of change.The three-dimensional finite element model of AZ31B magnesium alloy microjet and shock wave was established by ANSYS/LS-DYNA and ABAQUS software.The impact pressure and residual stress field of the material were simulated and the microjets with different liquid environments and different impact velocities were studied.The impact wave with different peak pressures on the impact pressure and residual stress of the material obtained the variation law of the residual stress of the surface under different parameters and the movement of the surface grain was analyzed.In this paper,the ultrasonic cavitation modification test of AZ31B magnesium alloy was carried out,and the effects of ultrasonic time,workpiece distance,ultrasonic amplitude and other process parameters on the surface hardness,roughness and surface grain size of the test piece were obtained.The variation law and the optimal process parameter combination measure the depth of the pit surface of the test piece after ultrasonic cavitation test,revealing the influence mechanism of ultrasonic cavitation modification on the surface roughness of the material.In order to explore the liquid environment modified by ultrasonic cavitation of AZ31B magnesium alloy,the effects of ultrasonic cavitation modification on the surface hardness,roughness and surface grain size of the test piece under different media were discussed by comparative experiments in kerosene.