Effects of heat treatment on microstructure and mechanical properties of selective laser melted Ti-6Al-4V lattice materials

Titanium alloy lattice materials fabricated by selective laser melting (SLM) have shown great potential in many engineering applications related to energy absorption. The mechanical behavior of the titanium alloy is dependent on its microstructure that can be improved by heat treatment. However, little attention has been paid to the effects of heat treatment on the lattice materials, and the relationship between the mechanical properties of the base material and the lattice structure is unclear. In this study, based on the body-centered cubic (BCC) and face-centered cubic (FCC) titanium lattice material fabricated by SLM, different heat treatments (750-1050°C, including hot isostatic pressing) were conducted to study the relationship between the microstructure and mechanical properties of the base material and the mechanical properties of the lattice materials. The results show that bending-dominated structure BCC is more sensitive to the heat treatment conditions than stretching-dominated structure FCC. The better heat treatment temperature for BCC and FCC are 920°C and 750°C respectively. Moreover, a numerical simulation model was established to show the relationship between the mechanical properties of the base material and the lattice material. These results are significant for the design and application of titanium lattice materials.