Effect of auxiliary TIG arc on formation and microstructures of aluminum alloy/stainless steel joints made by MIG welding-brazing process
(Shandong Provincial Key Laboratory of Special Welding Technology, School of Materials Science and Engineering,
Harbin Institute of Technology at Weihai, Weihai 264209, China)
Harbin Institute of Technology at Weihai, Weihai 264209, China)
Abstract: A new hybrid welding process was successfully used to join aluminum alloy and stainless steel. In the MIG welding-brazing process, the lower thermal conductivity of steel can cause dramatic change of temperature gradient on steel surface, while the auxiliary TIG arc can change this phenomenon by heating the steel side. The auxiliary TIG improved the wettability of molten metal, resulting in the molten metal spreading fully on upper surfaces, front and back surface of steel, forming a sound brazing joint; the content of Cr and Ni elements in IMCs layer was increased, which can enhance the quality of the layer; and the microstructure of IMCs layer also was improved, increasing the bonding strength with the weld seam. The average tensile strength of the joint obtained with auxiliary TIG arc (146.7 MPa) was higher than that without auxiliary TIG arc (96.7 MPa).
Key words: welding-brazing; auxiliary TIG arc; wettability; intermetallics layer; mechanical property