Effects of the manufacturing process on the flexural properties of EBMed lattice structures

Lattice structures are very interesting since they present good mechanical properties coupled with lightness. Today, the maturity reached by additive manufacturing technologies allows the production of such structures. However, the mechanical properties of the constituting material can be affected by the process itself, because of the particular geometry. In fact, in a previous work, the mechanical characteristics of the bulk-printed material were used for modelling the bending behavior of lattice-cored specimens made of Ti6Al4V and produced through electron beam melting (EBM) process, but a certain discrepancy with experimental results was found. Therefore, in this work, a procedure was proposed to determine the mechanical properties of the material the lattice specimen is made of, in order to reduce the gap between the numerical and the experimental results. By considering the redetermined yield strength, such mismatch was reduced. Moreover, the metallographic analysis of the material found that the α laths of the α + β microstructure, typical of the studied alloy, were thinner than those of bulk specimens, and the presence of α′ martensite was discovered too. The fracture surface analysis determined a ductile failure mode for the lattice core while a fragile mode for the skins.