Recent Developments in Stationary Shoulder Friction Stir Welding

This presentation will highlight recent development work at TWI in the area of Stationary Shoulder Friction Stir Welding (SSFSW). SSFSW is a variant of FSW where separate tool probe and shoulder components are used and only the tool probe component rotates. The result is a more linear heat input into the workpiece material and a keyhole type welding process. Process heat input is reduced, as are the key process forces (and hence machine requirements). Weld surface quality is typically much improved, and less thermal damage is caused to the workpiece (particularly in age-hardening Al alloys).

SSFSW has the potential to replace conventional FSW in a number of current applications, and allows FSW technology to be extended to new materials and new workpiece geometries. This talk will present the results of recent trials in a high strength 7xxx series Al alloy where the heat input and weld quality achievable by SSFSW has been directly compared with that of conventional FSW. The presentation will also highlight recent trials on welding of challenging joint geometries including 90 degree corner joints and T section parts, including the in-situ generation of corner fillet radii (and other features) by adding filler wire during welding.

SSFSW has been the subject of considerable development work at TWI over the last decade and is now starting to find industrial applications in a number of sectors, including aerospace.