Research On Mechanical Properties Of Ti6Al4V Minimal Surface Lattice Materials Printed By Selective Electron Beam Melting

Lattice materials are potential candidates for energy absorption,heat dissipation,and tissue engineering due to the lightweight,strong performance and efficient form of the structure.Metallic additive manufacturing techniques,in particular the selective electron beam melting(SEBM)process,are capable of fabricating strong,lightweight and complex metallic lattice materials,which promotes the development of lattices.However,lattices currently used are usually strut-based cellular structures which contain nodes,struts,and right-angled edges leading to high stress concentration and lower material utilization,restricting the performance and application of lattice materials.Therefore,the pursuit of stronger yet lighter materials has still been one of the primary objectives of engineering materials development.To achieve this goal,researchers have investigated the properties of sheet-based materials with lower stress concentration and high material utilization.Which is different from the strut-based structures,sheet-based TPMS structures are smooth infinite surfaces,and are periodic in three independent directions with lower stress concentration and stable structure.In this paper,the mechanical properties of Octet-truss,Tetrakaidecahedral and Diamond(D),Gyroid(G),I-WP(I),Primitive(P)TPMS lattices are investigated both experimentally and computationally.Strutbased structures and sheet-based TPMS lattices of Ti6A14V having an interconnected high porosity were manufactured by selective electron beam melting.The manufacturability,microstructure and mechanical properties of the Ti6A14V lattices were investigated with the help of numerical analysis.The results reveal that:Finite element analysis(FEA)results show that sheet-based TPMS lattices display relatively more uniform stress distributions and high utilization.It is also found that the yield strength of TPMS lattices linearly with their relative densities indicating a stretching-dominated deformation behavior leading to good performance than strut-based lattices.Diamond lattices exhibit the highest mechanical properties among all the structures studied in this paper,their yield strength reaches 212.25 MPa,when the ralative density is 0.40;The SEBM manufactured lattice materials retain the specific design form of lattice structure,and the dimensional error is less than or equal to 0.17mm,which have a good geometric agreement with the original CAD models;The SEBM manufactured Ti6A14V lattives exhibit the microstructure of columnar grains filled with very fine and orthogonally oriented martensitic laths and ?+?;Experimental results are in good agreement with FEA results.The resultes both show that sheet-based TPMS lattices significantly outperform strut-based lattices in Yield strength and compressive strength.Diamond lattices exhibit the highest mechanical properties among all the structures studied in this paper,their yield strength reaches 194.78 MPa and their compressive strength reaches 234.27 MPa when the ralative density is 0.36;After heat treatment at 1100? for 2 h,columnar grains was turned out to equiaxed grains,martensite was converted to a mixture of ? and ?,Annealing at 1100? for 2h improved the compressive ductility of the lattice materials.The sheet-based TPMS structure plays a role of stress transferring and reducing stress concentration,improves the mechanical properties of lattice materials,and promotes the development of 3D printing titanium alloy,thus providing more choices for multi-functional applications.