The effects of interstitial inert gas on the spreading of Inconel 718 in powder bed fusion
The effects of interstitial inert gas on the spreading of Inconel 718 in powder bed fusion
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DOI：
10.1016/j.addma.2023.103737
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发表时间：
2023-08
影响因子：
11
通讯作者：
S. Khajepor;O. Ejtehadi;S. Haeri
中科院分区：
文献类型：
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作者：
S. Khajepor;O. Ejtehadi;S. Haeri
采用离散元-格子-玻尔兹曼（DEM-LB）方法模拟研究了间隙气体对粉末床熔融增材制造（PBF-AM）条件下Inconel 718粉末铺展性的影响。在这里，一个精细的计算网格完全解决了每个颗粒周围的惰性气体流动。此外，Inconel 718粉末被充分表征，DEM接触模型通过专为增材制造中的金属粉末设计的严格程序进行校准。该过程涉及休止角和载玻片测试、纳米CT成像和剪切细胞实验。然后模拟了Inconel 718在真空和气体环境中的扩散行为。研究结果表明，惰性气体的存在下，增加沉积粉末的量和床层厚度。随着叶片速度的增加，气体和真空环境之间的粉末沉积的差异变得更加明显。此外，考虑到床附近的气体速度可以超过模拟中大多数颗粒尺寸类别的终端速度，观察到新沉积的颗粒被叶片的尾流破坏。
The effects of interstitial gas on the spreadability of Inconel 718 powder under conditions relevant to powder-bed fusion additive manufacturing (PBF-AM) are investigated through high-fidelity discrete element method-lattice-Boltzmann (DEM-LB) simulations. Here, a fine computational grid fully resolves the flow of inert gases around each grain. Furthermore, Inconel 718 powder is fully characterised, and the DEM contact models are calibrated via a rigorous procedure devised specifically for metallic powders in additive manufacturing. This procedure involves angle of repose and slide tests, nano-CT imaging, and shear cell experiments. The spreading behavior of Inconel 718 by a blade is then simulated in both vacuum and gaseous environments. The findings reveal that the presence of inert gases increase the amount of deposited powder and the bed thickness. As the blade speed increases, the disparity in powder deposition between gaseous and vacuum surroundings becomes more pronounced. Moreover, it is observed that the newly deposited particles are disrupted by the wake of the blade, given that the gas velocity near the bed can exceed the terminal velocities of most particle size classes in the simulation.