Development Of Electromagnetic Pulse Plate Welding Equipment And Technology Research On Magnesium-Aluminum Plate Welding

Magnesium(Mg)alloys and aluminum(Al)alloys are widely applied in the field of vehicle lightweight production due to the light material properties.However,traditional welding methods fail to achieve a reliable combination of the Mg and Al alloys because of the extremely diverse physical and chemical properties of these two metals.This situation restricts the widespread utilization of Mg alloys and Al alloys in automotive production.Electromagnetic pulse welding performs the metallurgical bonding of metal materials by means of the electromagnetic force,which is expected to bridge the gap of the bonding of Mg alloys and Al alloys.However,due to the poor plasticity of Mg,higher parameters for electromagnetic pulse welding equipment are required.Besides,the development of domestic electromagnetic pulse welding technology is relatively late.Consequently,there is no technically sophisticated and high-power domestic welding equipment,resulting in less research on the electromagnetic pulse welding of Mg alloys and Al alloys and hindering the application of electromagnetic pulse welding technology in the welding of Mg alloys and Al alloys.To this end,this article developed a set of electromagnetic pulse welding equipment for metal plate welding and carried out experimental research on electromagnetic pulse welding of Mg alloys and Al alloys.The research results have certain practical significance for promoting the further promotion and application of magnesium alloys and aluminum alloys in automobile production.First,this article selected the 27 kV / 200 kA multi-rod trigger vacuum switch(MTVS)as the discharge switch in the electromagnetic pulse welding equipment and developed a trigger power supply which successfully triggered the switch.Based on this system,a test platform was constructed.Theoretical and experimental analysis about the conduction characteristics of the electromagnetic pulse welding circuit was carried out to obtain the influencing factors and rules of the switching trigger characteristics and the main circuit discharge characteristics.Furthermore,based on the principle of electromagnetic pulse welding,the current required for Al alloy and Mg alloy welding was calculated.Combined with the design method of double discharge switch synchronous conduction,a set of electromagnetic pulse welding equipment for metal plate welding was developed.The equipment has a maximum charging voltage of 20 k V and a maximum conduction current of 400 k A.The welding of Mg alloy and Al alloy plates can successfully perform by this equipment.Subsequently,the high-speed camera was used to capture the forming process of the Al alloy plates.The effects of welding voltage,loop capacitance,spacer pitch,and thickness of the spacer on the forming process of the Al alloy plates were analyzed.This experiment verified the influence of various factors on the impact parameters of metal plates during electromagnetic pulse welding.In the electromagnetic pulse welding process,increasing the welding voltage,appropriately increasing the thickness and spacing of the shim can heighten the impact speed of the plate.Also,the proper thickness of the shim can control the deformation degree of the plate to ensure that the plate has a suitable impact angle.Finally,experimental research on electromagnetic pulse welding of Mg alloys and Al alloys was employed.Welding experiments of Mg alloy plates and Al alloy plates with different welding voltages and different plates spacing were operated.The anisotropy of magnesium alloy plates' mechanical properties on electromagnetic pulse welding was studied for the first time.The reliable welding conditions for magnesium alloy and Al alloy plates were obtained through the tensile test of the welded joint.Furthermore,it revealed that the tensile strength of the magnesium alloy plate in the rolling direction is the smallest and it is easier to achieve welding than other direction.Then,through the analysis of transient phenomena during welding,the existence of metal jets was verified and the phenomenon of micro-gap discharge during welding was found.