Study On Metal Transfer Behavior Of AZ31 Magnesium Alloy MIG Welding

AZ31 magnesium alloy with good comprehensive properties,has been widely used in all walks of life,has become a research hotspot in the field of a structural magnesium alloy materials.Magnesium alloy structural parts is in the use of the process,it is essential to the magnesium alloy welding or connection,so the study of magnesium alloy welding is of great significance.At present,the welding of magnesium alloy is not yet mature,magnesium alloy welding is still facing many problems,magnesium alloy welding to be further studied.In this paper,the effect of welding technology on the welding process of AZ31 magnesium alloy was studied based on MIG welding method.By changing the process parameters(welding current,dry elongation and protective gas flow),different active agents(KCl、Zn Cl2、Ca Cl2、Cd Cl2、Mg Cl2)were used to collect the arc and metal transfer during the welding process,the weld joints after welding were obtained.The experimental results were measured,calculated and analyzed.In this paper,we can draw the following conclusions:(1)There is a great influence on the arc and droplets of welding current,the collection shows the current from small to large process,the droplets in turn experienced drop-like transfer,projected transfer and spray transfer,where adjustable parameters range of the drop-like transition is wide,the critical current value is about 220 A,this time the arc is stable,droplet size is close to the wire diameter.During the process of increasing the current from125 A,the arc shape changes obviously,the arc height increases from high to short,the arc width increases gradually,and the droplet size changes,and the droplet size changes from big to small,and the transition frequency is accelerated.The current is through the impact of arc and droplet transition to effect the weld forming,the melt width increases,penetration is deeper,welding seam increases.(2)The experimental results show that the dry elongation will affect the critical current in the droplet transfer,the dry elongation increases and the critical current becomes larger.Under certain condition,with the increase in dry elongation,the resistance of the wire increases,the voltage increases,the droplet size becomes larger and the arc length becomes longer.The study of the weld found that dry elongation is too small,will cause the weld is too high,poor forming.Dry elongation is too large,arc is instability,metal splash is serious,weld formation is not good.(3)In a certain range,with the argon flow increases,the arc will shrink,the arc is more stable,the droplet size has been reduced.Gas flow is too small,will be involved in air,with arc disorder,resulting in splashing,and the protection effect is not good,resulting in weld oxidation;when gas flow is too large,arc blowing will increase,and be prone to splash.(4)The addition of different activating flux will have different effects on arc and droplet transfer.Ca Cl2 activator increases the arc width,increases the droplet size,increases the droplet transition cycle,hinders the transition of droplets,The penetration depth decreases,the remaining height is slightly reduced.Cd Cl2 activating flux and Zn Cl2 activating flux shrink the arc,so that the droplet size becomes smaller,the weld height and the width of the greatly reduced.After adding KCl activating flux,the arc is expanded greatly,becomes umbrella,the width of the arc is widened,the droplet size becomes smaller,the transition is in the vertical axial direction,the transition period decreases,the transition is smooth,the droplet transition is changed to the spray transition,KCl activating flux can promote the droplet transfer,welding seam and weld width increased,the increase in the width is of a great range.Mg Cl2 activating flux has little effect on the droplet transfer,the arc shrinks slightly,and the weld penetration increases slightly.