Fluid and particle dynamics in laser powder bed fusion
Fluid and particle dynamics in laser powder bed fusion
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DOI：
10.1016/j.actamat.2017.09.051
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发表时间：
2018-01-01
期刊：
影响因子：
9.4
通讯作者：
Moore, A. J.
中科院分区：
文献类型：
--
作者：
Bidare, P.;Bitharas, I.;Moore, A. J.
在这项工作中，我们采用了高速成像和纹影成像，以及多物理场建模相结合，阐明激光束和粉末床之间的相互作用的影响。第一次对在单线和岛扫描期间去除粉末的裸露区域的形成进行了成像。通过改变功率和扫描速度，激光羽流的倾斜度从向前移动到向后，从而导致不同的剥蚀制度，影响过程中的热量、质量和动量传递。随着建造的进展，剥蚀变得不那么严重，比一个单一的粉末层，但发生烧结和熔融粉末团聚体，这是受羽流，增加。纹影成像使Ar气流的可视化成为可能，Ar气流由于羽流而发生在床上方的大气中，此外还与受影响的颗粒相互作用。数值模拟被用来理解和量化所观察到的流动行为，通过流体动力学处理的激光羽流作为一个多组分的Ar-Fe等离子体。这些结果促进了激光粉末床熔合（LPBF）过程中流体动力学现象的表征，这是防止增材制造零件缺陷的关键因素。(C)2017 Acta Materialia Inc.出版社：Elsevier Ltd
In this work, we employ a combination of high-speed imaging and schlieren imaging, as well as multiphysics modelling, to elucidate the effects of the interaction between the laser beam and the powder bed. The formation of denuded areas where the powder was removed during single line and island scans over several layers were imaged for the first time. The inclination of the laser plume was shifted from forwards to backwards by changing power and scan speed, resulting in different denudation regimes with implications to the heat, mass and momentum transfer of the process. As the build progressed, denudation became less severe than for a single powder layer, but the occurrence of sintered and fused powder agglomerates, which were affected by the plume, increased. Schlieren imaging enabled the visualisation of the Ar gas flow, which takes place in the atmosphere above the bed due to the plume, in addition to its interaction with affected particles. Numerical modelling was used to understand and quantify the observed flow behaviour, through the hydrodynamic treatment of the laser plume as a multi-component Ar-Fe plasma. These results promote the characterisation of fluid dynamic phenomena during the laser powder-bed fusion (LPBF) process, which constitutes a key factor in the prevention of defects in additively manufactured parts. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd.