Constitutive modelling of coupled creep deformation and age hardening behavior of aluminum alloys under various thermal and mechanical loadings

A new theoretical-based constitutive model has been proposed in this study to concurrently predict the ageing and coupled creep-ageing behavior in both micro and macro ways of aluminum alloys under complex thermal and mechanical loading histories. The nucleation, growth and coarsening theories for age strengthening of aluminum alloys have been modified with the integration of dislocation-based theories raised by plastic or creep deformation to form the new theoretical-based creep-ageing modelling framework. Both the key microstructures (precipitates, solid solutes and dislocations) and macro properties (creep/stress-relaxation, yield strength and strengthening components) under various thermal and loading histories (e.g., single-step/multi-step isothermal and non-isothermal, pre-strain loaded) of a typical Al–Zn–Mg alloy have been effectively predicted and validated by the same set model. Furthermore, the capability of the developed model to reveal the detailed deformation and strengthening mechanisms with complex thermal and loading histories, and to assist the design of complex non-isothermal creep-ageing processes with optimization objectives of accurate shape and high strength in the formed alloys has been discussed and demonstrated.