Study On Test And Performance Of Magnetic Pulse Welding Joints For Aluminum Alloy And Galvanized Steel Plates

In order to reduce the weight of automobiles and achieve energy conservation and emission reduction,aluminum,magnesium and other light metals are widely used in automobile industry to replace some conventional automotive steels.The galvanized steel and the aluminum alloy are simultaneously applied to the automobile,resulting in a difficult problem of joint between the two metals.Magnetic pulse welding,as a solid high-speed collision welding technique,can effectively solve the above-mentioned connection problem.This paper made use of magnetic pulse welding technology to weld aluminum alloy plates and galvanized steel plates,and probed into their mechanical properties,macroscopic fracture,micro-interface,microstructure composition and corrosiveness.Firstly,the aluminum alloy plates and the zinc-coated steel plates were carried out by the magnetic pulse welding with different welding parameters.These joints were subjected to quasi-static tensile test and their mechanical properties were analyzed.The mechanical properties of the joints increase with the increase of discharge energies.As the overlap gap increases,the mechanical properties first rise and then decrease.In addition,a group of welding parameter was selected for magnetic pulse welding of aluminum plates and non-galvanized steel plates.Comparing the two kinds of joints performed with the same welding parameter,it is found that the existence of zinc layer has a great negative influence on the aluminum-steel joints by magnetic pulse welding.Secondly,the two aluminum-steel joints were analyzed by means of microscopic analysis methods such as optical microscope(OM),scanning electron microscope(SEM),energy dispersive spectrometer(EDS),transmission electron microscope(TEM)and nanoindentation.The energy and gap can influence the length of the zinc-free zone and the size of the interface wave in the micro-interface of the joint,resulting in a large difference in the mechanical properties.The presence of the zinc layer can result in the production of hard and brittle phases in the welding interface,affecting the strength of the aluminum-galvanized steel joints.Finally,aluminum plates and galvanized steel non-galvanized steel plates were separately carried out by magnetic pulse welding technology with the same welding condition.The two kinds of formed joints were both performed with neutral salt spray test and electrochemical corrosion test.In the neutral salt spray corrosion test,the mechanical properties of the two joints decrease with the increase of corrosion time,but the decrease tendency of mechanical properties is different.The two joints have different corrosion mechanisms by analyzing the corrosion morphology and corrosion products of the joints.In the electrochemical corrosion test,the electrochemical corrosion resistance of aluminum and galvanized steel joints is stronger than that of aluminum and non-galvanized steel joints.