Study On The Properties Of Ti6Al4V Porous Structures Fabricated By Selective Laser Melting

Ti6A14V alloy has many excellent characteristics such as high specific strength,corrosion resistance,and biocompatibility.It has been widely used in aerospace and medical implants due to these properties.At the same time,it has also become the most widely used material in the field of metal additive manufacturing.In order to give full play to the advantages of additive manufacturing,the fabrication of complex porous structures with high precision and high performance by selective Laser Melting and the related properties have become the current research hotspot.First of all,Ti6A14V alloy powder is used as the feedstock material to optimize the process parameters for SLM of Ti6A14V.The influence of different process parameters on the density,tensile,impact,and other properties of Ti6A14V alloy samples was studied.The tensile and impact fracture mechanism and the difference of the microstructure under different laser power and scanning speed were analyzed.The optimum process parameters obtained by the control variable method were laser power of 80 W,scanning speed of 500 mm/s,and hatch spacing of 80μm.With the optimized parameters,the density of the Ti6A14V alloy was 99.45%.The tensile strength and elongation were 1188 MPa and 9.5%,respectively.The impact toughness was 24.13 J/Cm2.Subsequently,the effects of annealing and solution aging heat treatment on the microstructure,phase composition,and mechanical properties of Ti6A14V alloy fabricated by SLM were studied.The experimental results show that the elongation,impact toughness,and fatigue life of Ti6A14V alloy fabricated by SLM have been improved after heat treatment.After 2 hours of furnace cooling at 850℃,the elongation of Ti6A14V alloy increased from 9.5%to 12.5%.The impact toughness increased from 24.13 J/cm2 to 47.51 J/cm2.After 2 hours of furnace cooling at 1050℃,the impact toughness increased to 49.22 J/cm2.The fatigue life under a constant stress amplitude of 350MPa increased from 4.8× 104 cycles to 8.6×104 cycles.Finally,the compression mechanical and energy absorption properties of the periodic porous structure of the rod system and the thin sheet were also studied.It was concluded that the compression fracture of the porous structure of Ti6A14V alloy is a mainly elastic brittle fracture.In this paper,by fitting the compression results,a revised Gibson-Ashby prediction equation for the structure of the Ti6A14V alloy triply periodic minimal surface(TPMS)thin sheet structures were established.By changing the relative density of the porous structure,the elastic modulus and strength of the porous structure can be adjusted,and the required mechanical properties can be obtained.The experimental results show that compared with the porous structure of the rod system,the porous structure of the TPMS thin sheet shows a better deformation mode.Therefore,a better energy absorption effect was obtained.In addition,the porous structure of the TPMS-Diamond thin sheet shows the best energy absorption capacity.