电极感应熔炼气雾化制备Ti-6Al-4V合金粉末的性能及其表征

Properties and Characterization of Ti-6Al-4V Alloy Fine Powders Prepared by Electrode Induction Melting Gas Atomization(EIGA) Technique

采用自行研制的无坩埚电极感应熔炼气体雾化设备制备Ti-6Al-4V合金粉末。使用环孔型和环缝型两种气雾化喷嘴,改变雾化压力和熔炼功率,设计4组工艺参数,研究雾化工艺对粉末性能的影响规律。根据激光选区熔化(SLM)对粉末的要求,将筛分得到的粒径小于53μm的粉末进行表征,采用MASTERSIZE 2000激光粒度分析仪分析不同雾化工艺制备粉末的粒度分布,采用欧奇奥500NanoXY+HR型粒度粒形分析仪对粉末的粒形进行量化表征分析。结果表明,采用环缝型喷嘴、5 MPa的雾化压力和25 kW的熔炼功率的工艺参数组合制备的粉末效果最佳,得到的粉末粒径较小且分布集中,粉末粒度呈近似正态分布,D10、D50和D90分别为19.4、31.9和51.5μm;粉末的球形度较高,粉末圆度的平均值为90.6%,欧奇奥钝度的平均值为92.7%,超过80%粉末的赘生物指数为0,卫星粉较少。通过XRD、SEM、EDS能谱和氧氮仪等手段对粉末进一步分析,发现粉末内部组织为不同取向的针状α’马氏体,空心粉含量较少,粉末成分无损耗且氧含量较低。对该粉末进行SLM成形,成形件致密度达到99.02%,表面粗糙度为4.98μm,显微硬度HV0.5为3525 MPa。

Ti-6 Al-4 V 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 500 NanoXY+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-6 Al-4 V 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.