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Stir welding emerges as major new process for aluminium

Connect, no.86, May 1997

The first major research programme to study friction stir welding of aluminium alloys has successfully concluded at TWI.


Friction stir welded (FSW) 6mm thick aluminium alloy panel measuring 3in x 2m.
Butt weld with minimal distortion produced on TWI's specially developed
FSW equipment for prototype manufacture

Friction stir welding (FSW) has been heralded as the most exciting new joining technique to emerge this decade. Invented by TWI in 1991, it is now patented in Europe, America, Scandinavia and Asia. And twenty-three organisations have already been licensed by TWI to use FSW.

FSW uses a non-consumable rotating probe moving along the joint line to create a high quality butt or lap weld. No filler or shielding gas is required for aluminium alloys and, because it is a solid-state process, FSW can be used to make high quality welds in all aluminium alloys, including those which cannot be welded by conventional fusion processes.

Twenty-five companies from around the world sponsored the four-year, 0.7m R&D programme at TWI to develop FSW for aluminium alloys in the range 1.2 to 13mm thick.

The companies were a mixture of end-users, equipment manufacturers and materials suppliers. Aerospace, automotive, shipbuilding and defence industries were all represented and many of the companies are now using FSW.

Building on the success of this programme, TWI has begun a study on titanium alloys. Seven companies have already agreed to support the work, but additional sponsors are welcome to apply to join the project.

Other forthcoming projects in this area include the application of FSW to marine and thick-section aluminium structures; evaluation of the mechanical properties of FSW joints and the use of FSW for lightweight automotive structures.

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