Crashworthiness design of AlSi10Mg lattice structures through heat treatments

This study investigates the process-structure-property relationship of LPBF AlSi10Mg octet-truss lattices for crash-absorption applications. The main novelty is the use of low-temperature post-process heat treatments as explicit design variables to tune crash performance without changing the lattice geometry. Lattice specimens were tested in the as-built condition and after two heat treatments, at 200°C (HT-200) and at 300°C (HT-300), under quasi-static compression and low-velocity impact loading (4 and 8 m/s). The results show that heat treatment strongly affects deformation mode and energy-absorption capability. HT-300 promotes a smoother and more stable collapse, significantly increases specific energy absorption, and reduces force peaks, whereas HT-200 provides limited benefits compared with the as-built condition. Microstructural analyses indicate that the improved response is associated with thermally induced changes that increase ductility and enable more homogeneous plastic deformation. A finite element model, calibrated and validated against the experiments across strain rates, was then used to design a lattice-based crash box for automotive applications. The proposed solution meets the crash-energy target of a segment C vehicle while achieving more than 40% mass reduction compared with a conventional crash tube. At the component level, this corresponds to an increase in specific energy absorption of 67%, passing from 11.5 kJ/kg for the reference crash tube to 20.16 kJ/kg for the proposed lattice absorber. Overall, the study demonstrates that heat treatment can be used as a geometry-free design lever to tailor the crashworthiness of additively manufactured lattice structures.