Work at Abington on friction stir welding has been so successful that TWI plans further group sponsored R&D to extend the capability of the process into joining of thick sections. Aerospace is one of the industries where friction stir welding shows great promise
In just under three years of systematic development, friction stir welding (FSW) has proved to be a remarkable technique for making butt and lap joints in aluminium alloys. Invented and patented by TWI, the process is already being used in production for welding extrusions several metres in length.
The development of FSW has been accelerated by a Group Sponsored Project backed by aluminium producers, aluminium users and stir welding machine builders. Project Leader Chris Dawes explains: 'Work to date has concentrated on welding material from 1.6 to 12.7mm thick. Major engineering alloys in the 2xxx, 5xxx, 6xxx and 7xxx series have been investigated, although we have also welded some aluminium-lithium alloys.
'Mechanical and metallurgical properties, including fatigue, are outstanding. And welds which are difficult to make by fusion processes such as arc, laser and electron beam are easy using friction stir. For example, we have welded2xxx to 7xxx without problems.'
Chris Dawes said it is clear that FSW has great potential for single pass welding of aluminium alloys much thicker than 12.7mm. He now plans to extend the existing Group Sponsored Project (GSP 5651), or start a new GSP. This will study thicker sections used by industries such as aerospace, construction, ship building and heavy road and rail vehicle.
TWI would like to hear from Member Companies interested in the proposed project. It would also like to know which aluminium alloys and what thickness range different industries would like to study. Please contact Chris Dawes or Dave Nicholas at TWI.
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