Abstract:Aluminum alloy was directly lap joined to uncoated carbon steel by gas tungsten arc welding process with Zn-based flux-cored filler wire. The Fe-rich layer detaches from the interface during welding, and then Al-Zn phases flow into the zone between the detached layer and the interfacial layer, accelerating further detachment of the Fe-rich layer. The detached layer diffuses and migrates gradually into the weld upon solidification. The intermetallic layer is about 15 μm thick, and the tensile strength of the as-welded joint reaches 111 MPa. After heat treatment, the tensile strength is improved to 150 MPa.

Key words: aluminum alloy; steel; dissimilar metal joining; interface; detachment