High‐Strain‐Rate Response and Microstructural Evolution of Additively Manufactured A286 Steel Lattice Structures: A Multiscale Experimental Investigation

This study investigates the high‐strain‐rate response and microstructural evolution of additively manufactured A286 steel lattice structures with body‐centered cubic (BCC), honeycomb, and gyroid architectures. The lattices, produced via powder bed fusion–laser melting, are characterized through quasistatic compression, split Hopkinson pressure bar (SHPB) testing, and advanced material analyses including thermogravimetric‐differential thermal analysis, Fourier transform infrared, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and residual stress evaluation. Under quasistatic compression, the honeycomb lattice exhibits the highest peak stress (≈3200 MPa), exceeding the BCC (≈2100 MPa) and gyroid (≈1500 MPa) configurations. SHPB tests reveal that the honeycomb maintains lower strain rates (≈1200 s ⁻¹ at 6 bar) and minimal deformation, confirming superior dynamic stability. Despite its lower energy absorption (≈4.95 J), it demonstrates enhanced impact resistance due to retained compressive residual stress (−628 MPa) and improved stress redistribution. Finite element simulations corroborate experimental results, validating stress evolution and deformation trends. SEM and XRD analyses confirm that the honeycomb lattice resists fracture and maintains phase stability under high‐strain‐rate loading. These findings identify the honeycomb lattice as an optimal design for underbody blast protection in armored fighting vehicles, combining stiffness, resilience, and superior structural integrity.