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摘要
Ti-6Al-4V alloy powders were prepared by a self-developed electrode induction melting gas atomization (EIGA) equipment. Two kinds of gas atomizing nozzles, ring-hole type and ring-slit type, were used in the experiment. Different atomization pressures and power inputs were used. Four sets of processing parameters were designed and their effect on the powder properties was studied. The powder were sieved by 270 standard mesh (powder particle size ≤53 μm) and the size distribution was analyzed by MASTERSIZE 2000 Laser Particle Size Analyzer. The powder particle shape was quantified with Occhio 500NanoXY+HR Particle Size and Shape Analyzer. Results show that optimal results are achieved with good sphericity by the combination of ring-slit nozzle with atomization pressure of 5 MPa and smelting power of 25 kW. A normal distribution of powder size is attained and the D10, D50 and D90 are 19.4, 31.9 and 51.5 μm, respectively. The mean Circularity and Occhio bluntness are 90.6% and 92.7%, respectively. It is found that more than 80% of powders have Occhio outgrow of 0. The powder was further analyzed by XRD, SEM, EDS and oxygen and nitrogen analyzer. The microstructure of the powder is acicular α' martensite with random orientations. The amount of hollow powder is extremely small. The powder composition is practically same as that of the ingot and a low oxygen content is found, which satisfies the requirements of the SLM process. The Ti-6Al-4V powder achieved by optimal process was used for Selective Laser Melting and the relative density, surface roughness and HV0.5 microhardness are 99.02% and 4.98 μm, and 3525 MPa, respectively. ? 2019, Science Press. All right reserved.
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