Fatigue and residual stress relaxation of deep rolled differently aged aluminium alloy AA6110

The precipitation-hardened aluminium wrought alloy AA6110 (Al–Mg–Si–Cu) was heat treated to the ageing conditions under-, peak- and over-aged. Deep rolling was applied at room temperature for all ageing conditions. Residual stresses and work hardening states near the surface of the deep rolled condition were characterized by X-ray diffraction methods. Depth profiles of residual stresses, full width at half maximum (FWHM) values of the X-ray diffraction peaks and microhardness near the surface of the deep rolled non-, under-, peak- and over-aged conditions are presented. Results of quasistatic tension tests of non-surface treated specimens are given to characterize the heat treatment state. The cyclic deformation behavior, s/n-curves and residual stress relaxation during fatigue tests have been investigated by stress-controlled fatigue tests at room temperature. Several polished and deep rolled non-aged (as-quenched) specimens were fatigued as a reference. The effect of deep rolling on fatigue lifetime as compared to polished specimens is discussed.