Study On Welding Of AZ31and Al Dissimilar Metal

Magnesium and aluminium as a wide distribution in the crust, in today’s s growingdemand for industrial raw materials, magnesium and aluminium has been identified as themost promising two metals. Magnesium alloy with light weight, specific strength and highspecific rigidity, stiffness, damping, low price and so on, is widely used in industries suchas cars, planes, mechanical and electrical products. Aluminium and aluminium alloy withgood corrosion resistance, good conductivity and thermal conductivity, high specificstrength，high specific rigidity and so on, have great potential in the field of high and newtechnology such as aerospace, aviation, automobile, etc. So magnesium and aluminumwelding technology research has become a hotspot and difficulty in the welding field.AZ31magnesium alloy and aluminum are connected in different temperatures byusing electronic universal testing machine, and TIG welding was carried out to weldaluminum and magnesium by using wires in this paper, the Mg/Al dissimilar welded jointinterface bonding, interface microstructure, element diffusion and the composition of thefracture are analyzed. The relationship between joint organization structure andperformance and the regular between element diffusion with the formation of interfacialtransition zone is explored.The result shows that the Mg/Al joint interface combined well in440℃，With theincrease of holding time, Mg、Al element diffusion more fully, joint combined with well.Calculation shows that the diffusion coefficient of Al in Mg is bigger than that of Mg in Al,and aluminum atomic diffuses into the magnesium matrix easily. TIG welding betweenaluminum and magnesium is carried out by adding Ag, Zn, Niand brass, Zn-5Al,respectively. when cladding AZ31wire on the aluminum, The interdiffusion betweenmagnesium and aluminum results in the presence of fragile Mg2Al3intermetallics. theexistence of Ag or Zn prevents the interdiffusion between magnesium and aluminum，while Ni and brass can not validly prevents the interdiffusion between magnesium andaluminum or the formation of intermetallic compound. TIG welding was carried out to weld aluminum and magnesium by using AZ31、Al wires，Mg17Al12and Mg2Al3intermetallics were formed in the transition zone, which makes the interface of the weldedjoint easy to fracture. The existence of zinc prevents the inter diffusion betweenmagnesium and aluminum and decreases the thickness of the transition region effectively,which restrains the formation of intermetallics.