Mechanical properties and deformation behavior of additively manufactured lattice structures of stainless steel

Abstract

In this work, we used the powder bed fusion selective laser melting (SLM) technique to build two different lattice structures, i.e. of type f2cc,z and hollow spherical, to investigate their plastic deformation behavior during tension, compression and cyclic testing. The stainless steel AISI 316L/1.4404 was used as model alloy for lattice structures that exhibited a relative density of 33% compared to bulk samples and a part density of 2.623 g/cm3. Using optical microscopy, SEM, EDS, DIC analyses as well as tension, compression and fatigue testing, microstructures and mechanical properties of the two types of lattice structures were compared with annealed counterparts, SLM-produced bulk and reference specimens of the same chemical composition. It was found that the f2cc,z lattice structures deformed by stretch, whereas the hollow spherical lattice structures presented a bending dominated deformation mode. Consequently, f2cc,z lattice specimens revealed higher energy absorption capacity and were capable of bearing higher loads. In addition, the f2cc,z samples showed comparable specific energy absorption with respect to bulk reference samples. The plastic deformation behavior of the different lattice structures has been assessed by considering geometrical and microstructural aspects. Implications on usability and potential improvements were also discussed.