A microstructure-based model for describing the material properties of Al–Zn alloys during high pressure torsion

•The softening process of Al–30wt%Zn alloy during high pressure torsion (HPT).•Development of a new microstructure-based model (MBWG).•Effect of the solid solution decomposition, Orowan looping and dislocation density.•Observation of the strong grain refinement during HPT.•Simulation of the softening and saturation processes of Al–Zn alloy during HPT.