Post-processing technologies for microstructure and properties optimization of additive manufacturing-fabricated high-strength aluminum alloys: A review

Additive manufacturing (AM) offers a promising route for the lightweight and integrated fabrication of complex high-strength aluminum alloy (HSAA) components. However, the as-built state of these alloys is characterized by an under-precipitated condition, metallurgical defects (e.g., hot cracking, porosity), non-equilibrium microstructure (e.g., coarse columnar grains), and a poor strength-toughness balance, thereby severely restricting their engineering applications. Post-processing is a critical means to eliminate defects, reshape microstructure, and optimize performance. This paper systematically reviews the research progress in post-processing technologies for AM-fabricated HSAAs, covering heat treatments (e.g., solution and aging, direct aging, retrogression and re-aging), and thermo-mechanical coupled treatments (e.g., hot isostatic pressing, friction stir processing, rolling, laser shock peening, and interlayer hammering). We provide an in-depth analysis of the mechanisms by which these post-processing technologies control microstructural evolution and their effects on mechanical properties, fatigue performance, and corrosion resistance. This review indicates that through well-designed post-processing, it is possible to achieve defect elimination, grain refinement, and precipitate optimization, enabling the performance of AM-fabricated HSAAs to approach that of conventional wrought counterparts with the same composition. Finally, we address the current challenges in this field and provide an outlook on future research directions, including intelligent process optimization, integrated short-flow, and multiphysics coupled modeling.