Microstructure and mechanical behavior of friction stir welded titanium alloys

Friction stir welding (FSW) has evolved extremely rapidly into a viable and affordable technology to join metallic alloys to manufacture structures for use in transportation systems. Automotive, aircraft, space and ship building industries have been actively pursuing this technology for the last eight to ten. years to join aluminum alloys, steels and recently titanium alloys. Research work is progressing at a vigorous pace on all fronts, including novel tool design, optimization of process parameters to produce mechanical properties equal to or better than fastened structures, and process models to understand and guide the FSW process Friction stir welding of aluminum alloys is nearing maturation and a number of applications have been identified for complex aerospace components in defense and commercial industry. However, a number of issues still remain to be investigated to provide a confident solution for long term usage of friction stir welded aluminum structures. This paper primarily presents a general overview of the friction stir welding of Ti alloys.