气雾化制备18Ni250钢粉体的数值模拟与试验验证  

Numerical simulation and experimental validation on preparation of 18Ni250 steel powder by VIGA process

作　　者：李嘉 刘雨[2] 王长军[2] 于晓华[1] 刘振宝[2] 王睿 毕中南 梁剑雄[2] LI Jia;LIU Yu;WANG Changjun;YU Xiaohua;LIU Zhenbao;WANG Rui;BI Zhongnan;LIANG Jianxiong(Faculty of Materials Science and Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China;Research Institute of Special Steels,Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China;Beijing GAONA Materials and Technology Co.,Ltd.,Beijing 100081,China)

机构地区：[1]昆明理工大学材料科学与工程学院,云南昆明650093 [2]钢铁研究总院有限公司特殊钢研究院,北京100081 [3]北京钢研高纳科技股份有限公司,北京100081

出　　处：《钢铁》2024年第6期112-121,共10页Iron and Steel

基　　金：科技部重点研发资助项目(2021YFB3702501)。

摘　　要：真空感应熔炼气雾化(VIGA)工艺具备细粉收得率高、高效率以及低成本等优点,是目前增材制造用粉体制备最为通用的工业技术。由于超声速流场冲击液滴形成粉体的雾化过程机理复杂,粉体质量与细粉收得率难以兼顾是关键技术问题之一。数值模拟通过可视化展示氩气流场和金属熔体破碎的过程,有助于分析VIGA工艺中超声速流场冲击液滴形成粉体的复杂机理。首先通过数值模拟对VIGA工艺的氩气流场、金属熔体破碎过程进行可视化分析,结合试验研究气雾化参数对细粉收得率以及粉末形貌的影响。主要的气雾化参数为气体压强(4、5 MPa)、气体温度(300、373、423 K)、熔体漏眼直径(5 mm)、熔体温度(1873 K)。研究结果表明,气体压强升高、气体加热可以明显提升超声速氩气流速度,模拟结果给出的最优参数为雾化气体压强5 MPa、气体温度423 K。机理分析发现,上升气流是金属熔体在一次雾化时的主要作用气流,作用为液膜拓展至初始液滴形成;初始液滴在超声速气流交叉冲击区进行二次雾化,液滴破碎后冷却形成粉末。采用最优工艺参数进行试验,实际细粉收得率可达到约66.59%,制备的粉末球形度良好。此外,雾化气体加热对粉体表面熔覆氧无明显影响。为开发18Ni马氏体时效钢材料及相应的气雾化制粉工艺提供技术支持,有望提高雾化效率和粉末性能。The vacuum induction gas atomization(VIGA)process has the advantages of high fine powder yield,high efficiency,and low cost,and it is currently the most common industrial technology for powder preparation for additive manufacturing.Due to the complexity of the atomization process of the supersonic flow field impacting droplets to form powders,it is challenging to balance the powder quality and fine powder yield,which is one of the critical technical problems.Numerical simulation helps to analyze the complex mechanism of powder formation by supersonic flow field impacting droplets in the VIGA process by visualizing the argon flow field and the process of metal melt crushing.It is visualized the argon flow field and metal melt crushing process of the VIGA process through numerical simulation and studied the effect of atomization parameters on the fine powder yield and powder morphology in combination with experiments.The main atomization parameters are gas pressure(4,5 MPa),gas temperature(300,373,423 K),melt nozzle diameter(5 mm),and melt temperature(1873 K).The results show that the gas pressure increasing,gas heating can significantly enhance the supersonic argon gas flow velocity,simulation results give the optimal parameters for atomization gas pressure 5 MPa,gas temperature 423 K.Mechanism analysis found that the rising gas flow is the central role of the metal melt in the primary atomization of the gas flow,and the role of the liquid film to expands to the formation of the initial droplets.The initial droplets are secondly atomized in the cross-impact area of the supersonic flow,and the droplets are crushed and cooled to form powder.Using the optimal process parameters for the experiment,the actual fine powder yield can reach about 66.59%,and the prepared powder has a good sphericity.In addition,the atomizing gas heating has no significant effect on the fusion-coated oxygen on the powder surface.It provides technical support for developing 18Ni martensitic aging steel materials and the corresponding gas atom

关 键 词：真空感应气雾化 数值模拟 18Ni250钢 一次雾化 二次雾化 粉体质量 

分 类 号：TF123.112[冶金工程—粉末冶金]