Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

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• 作者：Saad A. Khairallah ; ^{khairallah1@llnl.gov" class="auth_mail" title="E-mail the corresponding author} ; Andrew T. Anderson ^{anderson1@lln.gov" class="auth_mail" title="E-mail the corresponding author} ; Alexander Rubenchik ^{rubenchik1@llnl.gov" class="auth_mail" title="E-mail the corresponding author} ; Wayne E. King ^{king17@llnl.gov" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Selective laser melting ; Laser powder bed fusion ; Additive manufacturing ; 3D printing ; Metal ; Defect ; Computer simulations ; Heat flow ; Solidification
• 刊名：Acta Materialia
• 出版年：2016
• 出版时间：15 April 2016
• 年：2016
• 卷：108
• 期：Complete
• 页码：36-45
• 全文大小：5023 K

文摘

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.