Influence of pore structure on mechanical properties of 3D printing porous tungsten

The porous tungsten with the cube and triangular pyramid shape was designed by ANSYS finite element analysis in this paper. In the results, when the point, line, and plane loads are applied, respectively, the stress on the cube and triangular pyramid skeleton units is uneven. When the skeleton unit is subjected to the plane and line loads, respectively, the stress at the supported struts is relatively small, while the stress at the unsupported struts is relatively large, causing a large amount of deformation. When the skeleton unit is subjected to the point load, the stress and deformation are both the maximum at the loading point. The porous tungsten in the shape of cube and triangular pyramid with high porosity was fabricated by selective laser melting (SLM) technique, and the effects of pore shape and size on the mechanical properties were investigated. The results show that the macrostructure of these skeleton structure is not significantly different from the designed structure, but the porosity is lower than that of the designed value, because of the hanging and sticky powders on the skeleton struts. The tensile strength of cube skeleton with 50% and 80% porosity is 127.4 MPa and 55.8 MPa, the compressive strength is 667.1 MPa and 213.0 MPa, the impact toughness is 6.764 and 4.492 J·cm−2. The compressive strength of the triangular pyramid skeleton with 50% and 80% porosity is 231.1 MPa and 65.3 MPa, the impact toughness is 2.030 J·cm−2, and the hardness is similar as that of the cube skeleton. The tensile and compressive fracture morphology of the cube and triangular porous tungsten show the typical quasi-cleavage brittle fracture.