Study On Joining Magnesium To Aluminum By Conventional Mig Welding Process With Metal Interlayers

The key problem in joining magnesium and aluminum is how to control the verybrittle metallic compounds. So, in order to control the produce of intermetalliccompounds to realize good joining of this dissimilar metals joint, this paper putsforward using MIG welding for joining magnesium to aluminum with differentinterlayers.This paper is about the study of the joint between Mg（AZ31B） and Al（1060） whichformed by MIG welding. The result shows this novel welding process can obtain goodMg/Al dissimilar metals joint. The best welding parameter was: welding current100A,welding Voltage18V, welding wire feed rate38.m/min, Zn as interlayerï¼›The tensilestrength of joint can reached43.2MPa.The thickness of the compound layer in the interface area of Mg related to thewelding heat input. The thickness of the compound layer will be too thick when thewelding heat input was high or too low. The organization of joint was changed when thetrace elements of weld wire was altered. When the element Al of weld wire increased,the grain of fusion zone was smaller and increased the amount of strengthening phase.Using Al-Si weld wire, the strengthening phase Mg₂Si was produced during weldingprocess because of element Si, Mg₂Si can improve the quality of Mg/Al joint. But onthe other hand, element Si also can raise the possibility of porosity produce. TheMg₁₇Al₁₂intermetallic compounds will be increased when the element Mg of weld wireincreased, and this will reduce the quality of Mg/Al joint.The fracture mode is brittle fracture through the interface layer of Mg, and themain phase is Mg₁₇Al₁₂; the hardness of welding center zone was similar because of thesimilar organization and phase. Near the fusion zone of magnesium the hardness wasincreased because of the Mg/Al metallic compounds, furthermore, as the quantity ofMg/Al metallic compounds in different areas is not the same, the hardness was changedin different areas of the Mg/Al joint.