Even though friction stir welding (FSW) has been shown to produce high
performing butt-joints, stress concentration at the weld edges in
overlap FSW significantly reduces the performance of these joints. By
combining FSW and adhesive bonding into a friction stir (FS)
weld-bonding, joint mechanical performance is greatly improved.
Quasi-static and fatigue strength of the proposed FS weld-bonding joints
was assessed and benchmarked against overlap FSW and adhesive bonding.
The characterization of the structural adhesive is also presented,
including differential scanning calorimetry (DSC) and thermogravimetric
analysis (TGA), as well as mechanical characterization with curing
temperature. A small process parameter study was made to select proper
FSW parameters for AA6082-T6 overlap FSW and FS weld-bonded joints. The
adhesive degradation temperature (357ºC) was found to be higher than
reported temperatures in the adhesive during welding of FS weld-bonding
joints. Higher curing temperatures were found to lead to increased
strength while decreasing ductility of the adhesive. The addition of
adhesive bonding to the overlap FSW to produce FS weld-bonding resulted
in a significant increase in quasi-static and fatigue strength,
achieving 79.9% of the fatigue strength of adhesive bonded joints at
106 cycles, while FSW had 41.6%.