Friction Stir Welded Ti-6Al-4V Structural Joints

Friction Stir Welding of titanium has been shown to be suitable for producing flat, linear butt joints in thicknesses ranging from 2 to 12 mm.  In order to use this process for producing aerospace structures, welding techniques for more complex joints, such as corner and T-joints, are needed along with curved path and out of plane welding capabilities.  This paper covers recent developments in 6 mm thick Ti-6Al-4V corner and T-joints in addition to curved path and out of plane 5-axis corner joint welding.  The performance of these structural welds in bending fatigue was also evaluated and compared to similar geometries machined from wrought material.  It was found that contoured structural joints can be produced in Ti-6Al-4V using Friction Stir Welding and the fatigue properties of these welds are comparable to the fully machined part.