Abstract: Welding-brazing joining of Dissimilar metals between AZ31B Mg alloy and industrial pure titanium TA2 is studied by cold metal transfer (CMT) welding technology. The microstructure、element distribution of the welding joints were analyzed to show joining mechanism. The results show that, cold metal transfer welding technology is a feasible method for dissimilar metals Mg and Ti joining. The gagnesium and titanium sheets can be joined by forming new phases in the transition joining zones. The weld metal zone is constituted by -Mg solid solution ,skeleton shaped Mg17Al12 intermetallic compound, and granular distributed Mg17Al(Zn)12. The joining of magnesium and titanium mainly depends on the Ti3Al, and Mg17Al12 intermetallic compounds. At the same time, diffusions of Ti atoms and Al atoms also affect the formation of the joints during welding process. Therefore, enough quantity of heat input must be ensured to make the local titanium parent metal to melt and titanium atomic diffuse, so as to improve the joining strength during the welding process.

Key words: cold metal transfer technology;AZ31B;TA2;microstructure;mechanical properties