Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones
Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones
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DOI：
10.1016/j.actamat.2016.02.014
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发表时间：
2016-04-15
期刊：
影响因子：
9.4
通讯作者：
King, Wayne E.
中科院分区：
文献类型：
--
作者：
Khairallah, Saad A.;Anderson, Andrew T.;King, Wayne E.
本文研究了后坐压力和Marangoni对流在316L不锈钢激光粉床熔化过程中的重要作用。三维高保真粉末尺度模型揭示了强烈的动态熔体流动如何产生气孔缺陷、材料飞溅(火花)和剥蚀区。熔体轨迹分为三个部分：拓扑凹陷、过渡和尾部区域，每个区域都是特定物理效应的位置。在粉末尺度模型中加入了激光跟踪能量沉积，改进了传统的体积能量沉积。它可以使部分颗粒熔化，从而影响剥蚀区的气孔缺陷。在扫描轨迹的边缘、熔池底部(在熔池凹陷崩溃期间)和在熔体轨迹末端(在激光功率下降期间)观察到不同的气孔形成机制。对这些不良毛孔的补救措施进行了讨论。与实验结果进行了验证，并讨论了其对激光吸收率的敏感性。(C)2016 Acta Materialia Inc.由爱思唯尔有限公司出版。版权所有。
This study demonstrates the significant effect of the recoil pressure and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel. A three-dimensional high fidelity powder-scale model reveals how the strong dynamical melt flow generates pore defects, material spattering (sparking), and denudation zones. The melt track is divided into three sections: a topological depression, a transition and a tail region, each being the location of specific physical effects. The inclusion of laser ray-tracing energy deposition in the powder-scale model improves over traditional volumetric energy deposition. It enables partial particle melting, which impacts pore defects in the denudation zone. Different pore formation mechanisms are observed at the edge of a scan track, at the melt pool bottom (during collapse of the pool depression), and at the end of the melt track (during laser power ramp down). Remedies to these undesirable pores are discussed. The results are validated against the experiments and the sensitivity to laser absorptivity is discussed. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.