Enhancing the energy absorption capacity of Ti–6Al–4V lattice structure manufactured by additive manufacturing through β-annealing

The geometric configuration and microstructure are crucial for the mechanical properties of the lattice structure formed by laser powder bed fusion (LPBF). In this study, a type of Ti–6Al–4V lattice structure with hexagonal-body-centered (HBC) structure was fabricated by LPBF and post β-annealing treatment. The microstructure, mechanical properties, energy absorption properties and deformation behavior of the Ti–6Al–4V HBC lattice structure was investigated by electron backscatter diffraction (EBSD), quasi-static compression tests and digital image correlation (DIC) techniques. The results showed that the β-annealing sample completely transformed from the αʹ martensitic microstructure to a completely stable α + β lamellar microstructure, which slightly reduced the ultimate compressive strength of the HBC lattice structure and increased the strain at the end of yielding. The β-annealed sample showed better plasticity and work-hardening rate during the loading process, which increased its absorption capacity by 74.7% compared to the un-annealed sample. Finally, the quantitative analysis of fracture morphology indicated that the HBC lattice structure subjected to β-annealing undergoes ductile-brittle fracture, significantly improving its deformation stability.