Effect of orientation and extrusion welds on the fatigue life of an Al–Mg–Si–Mn alloy

The effect of specimen orientation and extrusion weld (seam and charge) on the fatigue life of specimens from a hollow AA6082 alloy extrusion profile have been characterized in the form of S–N curves. Specimen orientation with respect to the extrusion direction has a large effect on fatigue life. Transverse specimens exhibit only a fraction of the high cycle fatigue life exhibited by longitudinal specimens. The presence of seam and/or charge welds oriented both longitudinally and transverse to the loading direction, also reduces the fatigue life. The effects of these welds, however, are not as significant as the effects of orientation alone. The variations in fatigue life are explained by surface roughness and variations in microstructure.