Friction Stir Welding of Thick Section Aluminum for Military Vehicle Applications

Abstract : This report will highlight the work conducted in developing production-level, single-pass friction stir welding (FSW) parameters for thicknesses ranging from 0.5 to 1.6 inches in aluminum alloys 5083, 5059, and 2139. This includes developing welding procedures to meet ballistic shock requirements, extending tool life greater than 500 in without loss in weld properties, and maximizing travel speeds. Phased array ultrasonic testing (PAUT) was selected as the primary inspection method due to its flexibility, portability, and accuracy in detecting common FSW defects. The high automation of the FSW process led to an inherently stable process, ensuring that the incidences of welding defects were limited. As such, the PAUT development effort focused on refining techniques for inspecting defects most likely to occur in a production environment over the range of expected FSW joints. This collaborative effort between the U.S. Army Research Laboratory, EWI, and General Dynamics Land Systems (GDLS) culminated in the construction and inspection of a military vehicle demonstrator hull at GDLS facilities in Lima, OH. The successful fabrication of this demonstration article represents a significant step forward in accepting FSW technology as a viable joining method for aluminum hulled military vehicles.