Microstructure and Mechanical Properties of Dissimilar Friction Stir Welded AA2024-T4/AA7075-T6 T-Butt Joints

Aircraft skin and stringer elements are typically fabricated from 2xxx 7xxx series high strength aluminum alloys. A single friction stir welding (FSW) pass using a specially designed tool with shoulder/pin diameter ratio (D/d) of 3.20 is used to produce dissimilar T-butt welds between AA2024-T4 AA7075-T6 alloys at constant travel speed 50 mm/min different rotational speeds 400, 600 800 rpm. The the stringer. Sound joints produced without macro defects in both weld top surfaces joint corners all (400, 600, rpm). hardness value nugget zone increases by increasing 150 ± 4 Hv 400 rpm 167 3 rpm, while decreases reach as-received (132 Hv) Joint efficiency along exhibits higher values than that Four morphologies precipitates were detected (SZ); irregular, almost-spherical, spherical rod-like. Investigations electron back scattered diffraction (EBSD) technique showed significant grain refinement sir T-welds compared due dynamic recrystallization. size reduction percentages 85 90 % for AA2024 AA7075 regions mixed zone, respectively. Fracture indicate failed through modes fracture.