Friction Stir Welding Development

The research of this summer was a continuation of work started during the previous summer faculty fellowship period. The Friction Stir Welding process (FSW) patented by The Welding Institute (TWI), in Great Britain, has become a popular topic at the Marshall Space Flight Center over the past year. Last year it was considered a novel approach to welding but few people took it very seriously as a near term solution. However, due to continued problems with cracks in the new aluminum-lithium space shuttle external tank (ET), the friction stir process is being mobilized at full speed in an effort to mature this process for the potential manufacture of flight hardware. It is now the goal of NASA and Lockheed-Martin Corporation (LMC) to demonstrate a full-scale friction stir welding system capable of welding ET size barrel sections. The objectives this summer were: (1) Implementation and validation of the rotating dynamometer on the MSFC FSW system; (2) Collection of data for FSW process modeling efforts; (3) Specification development for FSW implementation on the vertical weld tool; (4) Controls and user interface development for the adjustable pin tool; and (5) Development of an instrumentation system for the planishing process. The projects started this summer will lead to a full scale friction stir welding system that is expected to produce a friction stir welded shuttle external tank type barrel section. The success of this could lead to the implementation of the friction stir process for manufacturing future shuttle external tanks.