Revealing transient powder-gas interaction in laser powder bed fusion process through multi-physics modeling and high-speed synchrotron x-ray imaging
Revealing transient powder-gas interaction in laser powder bed fusion process through multi-physics modeling and high-speed synchrotron x-ray imaging
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DOI：
10.1016/j.addma.2020.101362
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发表时间：
2020-10-01
影响因子：
11
通讯作者：
Tan, Wenda
中科院分区：
文献类型：
--
作者：
Li, Xuxiao;Zhao, Cang;Tan, Wenda
激光粉床熔化是一种新兴的金属添加剂制造工艺。激光粉床熔化过程中气体驱动的粉末运动对成形质量有重要影响。然而，由于定量实验测量方面的挑战，对暂态粉气相互作用的了解还不是很清楚。本文研究了单脉冲激光照射粉床时的粉气相互作用。我们建立了一个多物理模型来模拟复杂的液/气流动以及气体驱动的粉末运动，并通过高速同步辐射X射线成像进行了验证。我们识别和量化了LPBF中气-气相互作用的四种特征模式。粉末的运动受一种或多种相互作用模式的共同控制。通过模拟和实验证实，粉末可以从熔池边缘融入熔池，以不同的散角喷射(粉末飞溅)，或跳入熔池引起显著的熔池波动。我们的结果为控制动态粉末行为的驱动力提供了见解，为减少构建过程中的结构缺陷铺平了道路。
Laser powder bed fusion (LPBF) is an emerging metal additive manufacturing process. The gas-driven powder motions in laser powder bed fusion have significant influence on the build quality. However, the transient powder-gas interaction has not been well understood due to the challenges in quantitative experiment measurements. In this work, the powder-gas interaction for a single pulse laser illuminating on the powder bed is studied. We establish a multi-physics model to simulate the complex liquid/gas flow as well as the gas-driven powder motions, which is substantiated by high-speed synchrotron x-ray imaging. We identify and quantify four characteristic modes of powder-gas interaction in LPBF. The motion of a powder is controlled by one or multiple interaction modes collectively. As revealed by simulations and confirmed by experiments, powders can merge into the molten pool from its rim, be ejected at different divergence angles (powder spattering), or dive into the molten pool to cause significant molten pool fluctuation. Our results provide insights toward the driving forces controlling the dynamic powder behavior, which pave the way for reducing structure defects during the build process.