3D PRINTING OF IRON-BASED LATTICE STRUCTURES PRODUCED BY SELECTIVE LASER MELTING

Abstract

The mechanical properties of lattice structures with 78–79% pore volume produced from iron powder by selective laser melting were studied. Given that the mechanical properties of lattice structures can be predicted from the topology and dimensions of the unit cell, the influence of spatial orientation of the unit cells on the mechanism whereby the samples are deformed should be also established. Three types of lattice structures with different spatial orientations of unit cells represented by simple cubic volumes of porous material with the same size of forming lattices and unit cells were considered. The response of the lattice structure to different types of loads was analyzed. Measurements of the elastic modulus in four-point bending tests showed that porous 3D lattices with different unit cells had an elastic modulus of the same order, from 17.2 to 23.9 GPa. Compression tests of the 3D lattice structures showed that the lattices located at an angle of 45° to the z axis deformed according to similar schemes and had almost the same yield stress (14.0–15.4 MPa). The highest yield stress (40.5 ± 3.3 MPa) was observed in the lattices whose unit cells were parallel to the x, y, and z axes, which is due to the layered deformation of the cells. The greatest impact toughness (22.1–23.2 J/cm²), as well as the compressive yield stress and elastic modulus, was also shown by these lattices. Analysis of the fracture structure of the samples after impact toughness tests indicated that the iron lattice structures of all three types had a pit microrelief characteristic of viscous fracture. The results indicated the prospects of applying additive manufacturing techniques for the creation of iron-based powder materials by selective laser melting to form a lattice structure with high reproducibility of mechanical characteristics.