The Research On Weld Experiment Of Magnetic Pulse Assisted Brazing In Al-tube With Cu-tube

For the need of energy saving and environmental protection and light weight,using a mixture of copper and aluminum pipe is an inevitable trend,the effective connectivity of the pipes is a key problem to be solved in manufacturing.In the brazing process of aluminum and copper pipe,the solder is difficult to have a good contact with both base metal.In order to solve such problems,according to the research status of dissimilar metal pipes,in this paper,taking the advantages of magnetic pulse welding and brazing,a kind of composite welding process is studied.In this new process,the copper 、solder foil and aluminum is formed by magnetic pulse forming first,after that the brazing process is being done.The method has the following advantages: ○1 The solder can be conveniently arranged between two pipes.It is beneficial to wetting and diffusion of filler metal in the process of brazing.○2 The magnetic pulse assisted process can break the surface oxide film of the base metal and solder.○3 The solder is sealed between the two welded pipes,which is similar to the vacuum environment.○4 The magnetic pulse forming can improve the forming limit of metal material and is suitable for the connection of dissimilar metal pipe with large diameter.In order to study the practical effectiveness of the composite process,this paper takes the outer copper tube and 6063 aluminum alloy inner tube as the objects.The electromagnetic field of the coil and the magnetic force of the tube are analyzed by ANSYS.Based on the theory of magnetic pulse welding,the process parameters of Magnetic Pulse assisted part is determined.After that,using Zn3 Al solder foil as the solder to do the test and verify.Do research on the voltage,fitting clearance value,brazing temperature,brazing time and solder foil thickness and other factors on the effects of the whole process.The microstructure characteristics and microstructure distribution of the joints obtained by magnetic pulse assisted brazing were studied and analyzed.The results of numerical simulation and experimental study show that: It is feasible to apply the magnetic pulse assisted brazing technology in the practical application,which can form the welded joints with good microstructure and meet the theoretical expectations.In this experimental condition,an excellent welded joint organization can be found at a voltage of 8kv when the solder foil thickness is 300μm and the temperature is 410 ℃ for 8s.The welded joint is formed with the eutectic structure of α-Al and Zn-Al eutectic,and the formation and growth mechanism of the welded joint are in accord with the typical brazing mechanism of the Zn Al alloy brazing filler metal.