Microstructure and mechanical properties of tungsten inert gas welded–brazed Al/Ti joints

Abstract

The tungsten inert gas welding–brazing process using Al-based filler metal has been developed for joining 5052 Al alloy to Ti–6Al–4V alloy in a butt configuration. The results indicated that heat input influenced the morphology and thickness of the interfacial reaction layer of Al/Ti joints, which played an important role in the mechanical properties of weldment. With the optimised tungsten electrode offset D of 1.0 mm from Al/Ti initial interface to Al side and welding current of 70 A, the thin cellular-shaped and club-shaped TiAl₃ reaction layers formed in the brazing zone, which contributed to suppressing crack initiation and propagation during tensile test. Eventually, the maximum tensile strength of 183 MPa was obtained and the optimised Al/Ti joint fractured at Al alloy base plate. Moreover, the power density characterisation and joining mechanism of Al/Ti joints were discussed.

Keywords:

• TIG welding–brazing
• Aluminium alloy
• Titanium alloy
• Microstructure
• Mechanical property

Acknowledgements

The authors gratefully acknowledge the financial support provided by the Major project of science and technology of Hunan province (Project No. 2015NK3031).