Pulsed TIG Welding–Brazing of Aluminum–Stainless Steel with an Al-Cu Twin Hot Wire

A TIG welding–brazing process with a twin aluminum hot wire technique was utilized to control the heat input, improve the joint formation, suppress the interfacial intermetallic compounds (IMCs) and increase the joint strength, thereby creating reliable joints between an aluminum alloy and stainless steel with an ER2319 filler. Twin wires with reasonable diameters and filling modes led to a satisfactory weld of parent metals with varying thicknesses. By the hot wire technique, the reasonable range of the welding current was extended and the thickness of the interfacial IMC at the seam bottom was reduced. In addition, both the tensile strength and stability of the joints increased compared with a cold wire. The IMC consisted of θ-(Fe,Cu)₄Al₁₃ and minor Cr_0.7Fe_0.3Al₆, and the precipitated phases in the weld were Al₂Cu and Al₂CuMg. With an increasing welding current, the IMC thickness significantly increased, while the joint strength decreased. The fracture positions of the joints varied with the corresponding welding currents.