Ultrafine-grained metals processed by severe plastic deformation usually possess very high strength but low ductility, i.e., uniform elongation less than 5%. In the present work, ultrafine-grained (UFG) Al–Mg–Si–(Cu) aluminum alloys have been fabricated by equal channel angular pressing at different temperatures. Combinations of high ductility and high strength were obtained. The highest ultimate tensile strength and yield strength among the alloys were ~460 MPa and ~430 MPa, respectively. The precipitation sequence and kinetics, dislocation density, grain size, precipitate volume, and solute atom distributions were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and atom probe tomography (APT). Special emphasis was laid on the interactions between precipitates, dislocations, grain boundaries and solutes, as well as the effects of precipitation on the accumulation of dislocations, work hardening, strength and ductility.