Pore elimination mechanisms during 3D printing of metals

• Published in: Nature communications Vol. 10; no. 1; pp. 3088 - 8
• Main Authors: Hojjatzadeh, S. Mohammad H., Parab, Niranjan D., Yan, Wentao, Guo, Qilin, Xiong, Lianghua, Zhao, Cang, Qu, Minglei, Escano, Luis I., Xiao, Xianghui, Fezzaa, Kamel, Everhart, Wes, Sun, Tao, Chen, Lianyi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12-07-2019; Nature Publishing Group; Nature Portfolio
• Subjects: 3-D printers; 639/301/1023/1026; 639/301/930/1032; Coordination compounds; High temperature; Humanities and Social Sciences; Image resolution; MATERIALS SCIENCE; Melting; Metals; multidisciplinary; Pores; Powder; Powder beds; Printing; Science; Science (multidisciplinary); Synchrotron radiation; Temperature gradients; Thermocapillary force; Three dimensional printing; X ray imagery
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-10973-9

Laser powder bed fusion (LPBF) is a 3D printing technology that can print metal parts with complex geometries without the design constraints of traditional manufacturing routes. However, the parts printed by LPBF normally contain many more pores than those made by conventional methods, which severely deteriorates their properties. Here, by combining in-situ high-speed high-resolution synchrotron x-ray imaging experiments and multi-physics modeling, we unveil the dynamics and mechanisms of pore motion and elimination in the LPBF process. We find that the high thermocapillary force, induced by the high temperature gradient in the laser interaction region, can rapidly eliminate pores from the melt pool during the LPBF process. The thermocapillary force driven pore elimination mechanism revealed here may guide the development of 3D printing approaches to achieve pore-free 3D printing of metals.
3D printing pore-free complex metal parts remains a challenge. Here, the authors combine in-situ imaging and simulations to show thermocapillary force can eliminate pores from the melt pool during a laser powder bed fusion process.