The role of pore structures on the fatigue properties of additively manufactured porous tantalum scaffolds produced by electron beam powder bed fusion

Abstract

In this work, porous tantalum scaffolds with structures of cubic, G7 and rhombic dodecahedron with different strut angles were fabricated by electron beam powder bed fusion (EB-PBF). Uniaxial compressive testing and compression–compression fatigue testing were conducted on the EB-PBF built tantalum scaffolds. The role of pore structures on the deformation behavior and fatigue properties of the tantalum scaffolds were analyzed. The effect of buckling component in the rhombic dodecahedron structure on fatigue performance of the porous tantalum scaffolds was investigated. It was demonstrated that the G7 and cubic porous tantalum scaffolds were dominated by buckling deformation under the axial force. Due to the presence of vertical struts, the G7 scaffold showed higher fatigue strength and fatigue ratio than the dodecahedron which deformed mainly via bending, the cubic scaffold showed the highest fatigue ratio. As the strut angel increased from 35.3° to 43°, the fatigue strength and fatigue ratio of the rhombic dodecahedron tantalum scaffolds improved by 59% and 20% at 2 × 106 cycles, respectively. The ratcheting strain and fatigue damage strain during the fatigue test were both decreased with the increase of buckling component, leading to the boosting of compressive fatigue properties of tantalum scaffolds accordingly.