  The softening and strengthening contributions in pre-deformed and aged
Al-Mg-Cu alloys containing 3wt.%Mg and 0.5wt.%Cu are evaluated by a combination
of microscopy, mechanical testing and modelling. A refined phenomenological
model for the work hardening response, accounting for the separate effects of
recovery and precipitation, is shown to be suitable for an unambiguous
determination of the precipitation hardening contribution in these alloys.
Significantly, it is found that the mechanical response of these alloys is not
strongly impacted by Cu content (in the low Cu content regime), pre-deformation
level or aging temperature meaning that the alloys are robust with respect to
variations in composition. This is interesting from the perspective of alloy
design concepts based on `recycling friendly' compositions in applications that
include paint-baking.
