D. G. Sanders, The Boeing Company, Seattle, WA; M. Ramulu, University of Washington, Seattle, WA; A. Reynolds, University of South Carolina, Columbia, SC; G. J. Grant, Battelle Pacific Northwest National Laboratory, Richland, WA

Summary:

This paper explores recent research aimed at combining Friction Stir Welding (FSW) butt joints of titanium alloy 6Al-4V sheet metal with Superplastic Forming (SPF) to enable the fabrication of very large airframe components. SPF of titanium has been used within the aerospace industry for over 30 years to fabricate monolithic assemblies for military and commercial aircraft. The development of Friction Stir Welding (FSW) of aluminum alloys is very well documented and much progress has been made in recent years in the deployment of the technology for the production of liquid fuel rocket tanks and passenger aircraft components. The current size limitation for titanium SPF is due to the maximum available size of sheets, which is 1.2 meters x 3.6 meters. The true benefit of SPF fabrication is in the reduction of part count and the elimination of fasteners, which means that larger sized SPF assemblies would be desirable if the current limitation on titanium sheet size could be overcome. The successful combination of titanium FSW and SPF technologies will enable very large integrally stiffened titanium parts to be produced in custom shapes for Boeing’s new 787 Dreamliner airplane. Preliminary material properties have been developed for FSW joints and FSW joined sheets that have been subsequently Superplastic Formed.