Microstructure and joining mechanism of Ti/Al dissimilar joint by pulsed gas metal arc welding

Butt joining of titanium alloy Ti–2Al–Mn to aluminum 1060 using AlSi5 filler wire was conducted using pulsed gas metal arc welding. Joining mechanism of Ti–2Al–Mn/Al 1060 dissimilar joint with different welding heat input was investigated. Formations of precipitation and Ti/Al interface were discussed in detail. Fusion zone near aluminum is composed of α-Al dendrites and Al–Si hypoeutectic structures. A few TiAl3 precipitations appear in the weld metal owing to metallurgical reactions of Al with dissolved Ti. When the welding heat input was in the range of 1.87–2.10 kJ/cm, titanium alloy Ti–2Al–Mn and Al 1060 were joined together by the formation of a complex Ti/Al interface. With a low welding heat input, a serrate TiAl3 interfacial reaction layer was formed near Ti/Al interface. With the increasing of the welding heat input, α-Ti, Ti7Al5Si12, and TiAl3 layers were formed orderly from Ti–2Al–Mn to weld metal.