Ultrasonic Welding Technology Of Light Alloy

Ultrasonic welding technology is a solid state welding process,which has many advantages and has a good application prospects in the light alloy welding.This paper will study the solder joints which are obtained through a series of experiments on aluminum alloy,magnesium alloy and titanium alloy for homogeneous or heterogeneous ultrasonic welding.The solder joints are studied to explore the effect of welding parameters and material properties of the welding and the formation mechanism.In this paper,ultrasonic welding technology is used to weld the light alloy plates.In order to obtain good solder joint specimens,we change the welding parameters(welding pressure,welding power,welding time and weld amplitude)and material properties(hardness).The tensile shear test was carried out to explore the relationship between the lap shear strength of the solder joint and the welding parameters and material properties.The microstructures of the specimens are observed by metallographic microscope,EPMA(electron microprobe analysis)and EBSD(electron backscatter diffraction),and the tensile fracture section of the welded joint was analyzed by XRD(X-ray diffraction).In addition,this subject also presents a stamping pre-deformation treatment of ultrasonic welding structure.The results show that there is a parabola relationship between the lap shear strength of welds of ultrasonic welding of aluminum alloy and welding pressure,welding power,welding time and weld amplitude.The formation process of different solder joints can be divided into three stages according to the welding energy: the micro-bonding stage,the wave displacement stage and the scroll displacement stage.The material flow ability gets better as reducing the hardness of the plate,which on the one hand will promote the formation of good weld,on the other hand will make the plate deformation and strength decrease.A stamping pre-deformation treatment to the plate will eliminate the invalid friction area,making the welding force more uniform and the welding strength increased.When the energy consumption is high,the side of magnesium of the magnesium / titanium welding interface generate a semi-melting zone and grain refinement zone.The precipitated aluminum elements of magnesium alloy in the liquid phase plays a bridge role and promote the magnesium / titanium heterogeneous metal high-strength connection.In the magnesium / copper interface,an interfacial diffusion layer form on the side of magnesium alloy,which is mainly composed of Mg and Mg2 Cu and promotes a stable and reliable welding joints.This topic systematically studied the ultrasonic welding of light alloy,and explored the formation mechanism of homogeneous and heterogeneous welded joints.And some improved method of ultrasonic welding process were put forward to provide a meaning reference of the ultrasonic welding process for the future research.