Study On The Microstructure And Properties Of Biomedical Ti-6Al-4V Produced By Selective Laser Melting

Selective laser melting is a new type of additive manufacturing technology. As a result of the superposition processing method for layer by layer, this technique eliminates the traditional processing methods limit geometry, has significant advantages in the preparation of a complex structure with a bore and personalized production. Provide an effective solution to reduce the elastic modulus of TC4 titanium medical implants, reducing stress shielding, adapted to individual needs of different patients. In this paper, a high-quality selection of TC4 titanium alloy powder was tested for its physical and chemical properties, and use SLM technology to prepare alloy block, through detection and analysis of their microstructure, mechanical properties and biological properties found this molded parts to meet the requirements of biomedical implant materials.This paper has made the following conclusions:① The high degree of spheroidization TC4 alloy powder used herein, the particle surface is smooth, the particle size in the range of between 3-52μm, an average particle size of 30.65μm, specific surface area of 0.0652m2/g, the bulk density of the powder 2.67 g / cm3, no liquidity, angle of repose 38 °.② SLM molding process parameters: laser power 170 W, spot diameter 0.1mm, scan spacing 0.1mm, dusting thickness 0.04 mm, scanning speed 1.2m/s; moldings density reached 99.5%; the surface roughness of the top surface(dusting direction) 22.47μm, the side surface(overlay direction) 60.13μm.③ TC4 powder microstructure of fine needle α’ martensite. SLM molding TC4 microstructure of fine needle α’ martensite, the organization has been roughened after annealing. As build side of the microstructure is composed of β through multiple cladding was composed of columnar grains epitaxial growth, positive organizational features a grid-like, and the angle of rotation between the layers of the laser scanning approach basically.④ The main mechanical properties of TC4 alloy produced by SLM: tensile strength 1202 MPa, yield strength1029 MPa, elongation of 8.3%, the top surface hardness HV402, the side surface hardness HV418. SLM molded parts strength and hardness than conventional casting and forging TC4 alloy, but the plastic is no obvious advantage compared with forging TC4 alloy; microstructure tensile fracture is toughness + quasi-cleavage characteristics.⑤ SLM forming TC4 alloy compared to the TC4 alloy produced by the traditional process has a better corrosion resistance in the SBF Ringer ’s biomimetic solution and physiological salt solution; After annealing, the SLM forming TC4 alloy corrosion resistance decreased compared to before annealing.⑥ The hemolysis rate of SLM forming TC4 alloy and after annealing were 1.434%, 1.389%, less than 5%, does not cause acute hemolysis, showed a more excellent blood compatibility; two state alloy cytotoxicity was grade 0, no toxicity to osteoblasts, showing a good cell compatibility.