Mechancial Properties of Repaired 7075-T73 Friction Stir Weld Butt Welds

Abstract

For production parts joined by friction stir welding, there is a need to identify the effects of rework in a shop environment, or later repair of damage in service, on mechanical properties. Effects on strength or microhardness have been previously characterized; however, often design loads may not be purely driven by static strength allowables, but instead by fatigue limits, which may be less sensitive to rework than ultimate or yield tensile strengths. To investigate those effects, defective butt welds were created in 0.25 in thick 7075-T73 Aluminum alloy plates. Welds were then repaired using similar parameters directly over the original weld. The mechanical properties of up to four passes after the initial weld were also investigated with a focus on fatigue life. An analysis of the results and a discussion of the implications for repair and rework of friction stir welded structures and assemblies are included.