Enhanced energy absorption and low anisotropy of additively manufactured porous Ti-6Al-4V alloy with disordered trapezo-rhombic dodecahedron structures

Abstract

Additive manufacturing (AM) enables the fabrication of porous metals possessing outstanding characteristics for lightweight structural applications and energy absorption. The mechanical properties of porous metals are influenced by factors such as porosity, cell shape, cell size, and loading direction. This study explores porous Ti-6Al-4V samples with both ordered and disordered cellular structures, manufactured via the laser powder bed fusion (L-PBF) process. We systematically investigate their anisotropic compression behavior under varying degrees of regularity. Results indicate that samples with ordered cellular structures demonstrate higher compressive strength under z-axis compression but are susceptible to shear band formation under x- and y-axis compression, significantly reducing strength. As regularity decreases, shear bands diminish, leading to more uniform plastic deformation across all directions. Notably, at a regularity coefficient R = 0.8, the samples exhibit optimal mechanical performance, including the highest plastic collapse strength and energy absorption capacity. Decreasing regularity also reduces the anisotropy of the porous structures, with the lowest anisotropy observed at R = 0.4; however, the optimal overall mechanical performance is achieved at R = 0.8. Adjusting the porous structure regularity is key to achieving isotropy and optimizing mechanical properties, offering significant advantages for practical applications in lightweight structures and energy absorption.