Friction Stir Welding Characterization of 2050 and 2219 plate

It is well known in the aerospace community that aluminum-lithium alloys possess some of best specific strength and specific stiffness properties among metals.  Early generations of aluminum-lithium alloys were restricted to plate sections less than 2” thick and possessed highly anisotropic microstructure.  AIRWARE 2050 is a 3^rd generation aluminum-lithium alloy that is produced in significantly thicker sections and has a mature mechanical properties database.  The database includes mechanical properties for the short transverse (i.e. through the thickness) grain orientation which was poorly understood in early-generation aluminum-lithium alloys. The data available on 2050 weldments using friction stir welding (FSW) are very limited, especially in grain directions that follow the short transverse.  Lockheed Martin sponsored research by students from the University of New Orleans and Louisiana State University in conjunction with the National Center for Advanced Manufacturing (NCAM) to conduct a series of FSW trials on 2050-to-2219 using self-reacting FSW pin tools. The 2219 material, representing the cone section of the Orion Command Module, was welded along the longitudinal grain direction.  The 2050 material, representing the forward bulkhead of the Orion Command Module, was welded in the longitudinal gain direction as well as the Longitudinal-45 degree-Short Transverse (L-45-ST) grain orientation. This orientation is of particular interest to the Orion program because the 2050 material would be welded in this grain orientation if it were implemented on the vehicle. Implementing 2050 on the Orion Command Module is of great interest since it could lead to significant mass savings over the current 2219 alloy. This presentation will report the results of FSW trials on 0.320” thick 2050-to-2219 plates with the 2050 configured in two different grain orientations.  The differences in FSW mechanical properties between the two 2050 grain orientations will be highlighted.