Investigation of properties of the regular structures obtained by additive technologies in combination with the powder metallurgy methods

Abstract

Despite significant amount of research and applied works in the additive technologies, problems of the topological optimization of structures obtained by combining 3D printing and the powder metallurgy methods remain insufficiently studied both theoretically and experimentally. Results of simulating regular structures made of plastics and studying their destruction processes could be effectively used as a starting approach in developing technology for production of the composite materials based on the titanium alloys with the increased level of strength properties. Based on numerical experiments and full-scale tests, the most preferred types of structures were determined. They include honeycomb structures based on PLA with the following strength properties: elastic modulus — 342.3 MPa; ultimate compressive strength — 20.4 MPa; specific strength — 81 MPa cm3/g. 3D models realized on plastics were used in manufacture of the metal composites using technology combining selective laser melting and powder metallurgy. In addition to increasing density and eliminating porosity of structures made from the titanium alloy powders, the strength properties level also increases after infiltration with the lower-melting alloys, since redistribution of stresses arising in the titanium frame under load is ensured. Bending strength alters in the range of 1140...1560 MPa and elastic modulus - in the range of 49 500...54 000 MPa depending on the composite composition and selective laser melting modes. Rockwell hardness increases from 35 to 45 HRC, and Brinell hardness — from 340 to 410 HB, which is by 20...25 % higher than hardness of the rolled products from the VT6 alloy. The increased strength values could be explained by the material composite structure formed by combination of the two mutually penetrating frames. Results of testing samples for strength are another argument in favor of the proposed infiltration method implying combined additive and powder metallurgy methods.