Tungsten Inert Gas Welding-Brazing of AZ31B Magnesium Alloy to TC4 Titanium Alloy

Tungsten inert gas (TIG) welding-brazing technology using Mg-based filler was developed to join AZ31B Mg alloy to TC4 Ti alloy in a lap configuration. The results indicate that robust joints can be obtained with welding current in the range of 60-70 A. The joint interface was found to be likely composed of Mg-Ti diffusion reaction layer accompanied with Mg17Al12 precipitate phase, indicating that metallurgical joining was achieved. The optimized joint with average tensile-shear strength of 190 N/mm2 was obtained and fracture occurred at the Ti/fusion zone interfacial layer during tensile test. Moreover, the fracture surface was characterized by equiaxed dimple patterns accompanied with a few lamellar tearing. Finally, finite element modeling (FEM) numerical simulation was developed to analyze the distribution characteristics of the temperature field of joints.