Abstract:

Aluminum alloy plates were joined to galvanized steel sheets with lap joint by laser-MIG arc hybrid brazing-fusion welding with AlSi5, AlSi12, AlMg5 filler wires, respectively. The influences of Si and Mg on the microstructure and mechanical properties of the brazed-fusion welded joint were studied. The increase of Si element in the fusion weld can make the grain refined, and increase the microhardness of the fusion weld. Therefore, the microhardness in fusion weld made from AlSi12 and AlSi5 filler wires can be up to 98.4 HV0.01 and 96.8 HV0.01, which is higher than that from AlMg5 filler wire of 70.4 HV0.01. The highest tensile strength can reach 178.9 MPa made with AlMg5 filler wire. The tensile strength is 172.43 MPa made with AlSi5 filler wire. However, the lowest tensile strength is 144 MPa made with AlSi12 filler wire. The average thicknesses of the intermetallic compounds (IMCs) layer with AlSi5,AlSi12, AlMg5 filler wires are 1.49-2.64 μm. The IMCs layer made from AlSi5, AlSi12 filler wires are identified as FeAl₂, Fe₂Al₅, Fe⁴Al₁₃ and Al_0.5Fe₃Si_0.5, that from AlMg5 filler wire are identified as FeAl₂, Fe₂Al₅ and Fe₄Al₁₃.

Key words: Hybrid welding, Welding of dissimilar metals, Aluminum alloy, Galvanized steel, Mechanical properties, Intermetallic compounds