FATIGUE AND FRACTURE BEHAVIOUR OF FRICTION STIR WELDED ALUMINIUM ALLOY AA6056-T6

摘要

Butt joints of thin sheets (3.2 mm) of the airframe quality AA6056 were produced by friction stir welding in the peak-aged T6 temper and tensile, fatigue, fatigue crack propagation (FCP) and fracture behaviour of welds were investigated. All data were obtained on skimmed specimens. Local property changes were inferred from hardness profiles and micro-tensile specimens. After welding, the alloy exhibited softening and loss of strength in the weld zone. Nonetheless, the fatigue performance in the high cycle regime was reasonably good. Also, the resistance to FCP was comparable or slightly better than that of the base material at high ΔK (≥ 10 MPa m~(1/2)). Compared to the nugget, the thermomechanically affected zones (TMAZ) exhibited inferior FCP, and deformation and fracture behaviour under static loading. While comparing with the literature, these results are assessed.