Effect of Quenching Method on Mechanical Properties of Thin‐Walled Al–Mg–Si–Cu Alloys

The quenching method significantly affects the mechanical properties of Al–Mg–Si–Cu alloy energy‐absorbing boxes. This study examines the inherent mechanism of the quenching process's action while methodically examining how it affects mechanical properties of the alloy's energy‐absorbing boxes. The results demonstrate that, in comparison to samples treated with air cooling (AC), the mechanical properties of those treated with online water cooling (WC) are substantially improved. Specifically, the WC samples achieve optimal levels of tensile strength, elongation, and fracture toughness and perform well overall. Comparing it to the AC samples, its tensile strength (383.1 MPa), bending angle (148.6°), and peak crush load (410.4 kN) are all enhanced by 21.3%, 38.3%, and 31.3%, respectively. In this study, it is found that rapid cooling significantly inhibits the diffusion of solute atoms into the crystal, and more vacancies and solute atoms are obtained. This helps create the narrow grain boundary, precipitate‐free zone, and aging‐strengthening precipitation of dense and fine β″ phases. In addition, the WC quenching process inhibits crack propagation, which ultimately results in WC samples exhibiting high strength along with high toughness. This guarantees that the energy‐absorbing box profiles has outstanding plastic deformability and energy‐absorbing qualities under bending and crushing loads.