Dissimilar Alloy Aluminum Tailor Welded Blanks

The advantages of using tailor-welded blank (TWB) technology to optimize the use of sheet metal in assemblies by selectively varying material thickness, alloy, temper and surface coatings demonstrate the ability to simultaneously reduce cost and weight in built-up structures.  While several welding methods are currently available for the production of aluminum TWBs, each with their own advantages and challenges, high speed friction stir welding allows for both linear and curvilinear joint configurations in similar and dissimilar thicknesses.  As such, an evaluation of high speed friction stir welding was performed using dissimilar alloy combinations with dissimilar thickness sections.  Variations of combinations of precipitation strengthened and work hardenable alloys were welded together to evaluate the feasibility of joining alloys with different high temperature yield strengths, strengthening mechanisms, and tempers.  The effect of welding speed on the precipitation strengthened alloys is especially of interest, as high welding speeds demonstrated shifts in softening mechanisms.  Evaluation of combinations AA7075, AA6022, and AA5182 in similar and dissimilar thickness combinations are presented.