Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding

S. Mohammad H. Hojjatzadeh; Niranjan D. Parab; Qilin Guo; Minglei Qu; Lianghua Xiong; Cang Zhao; Luis I. Escano; Kamel Fezzaa; Wes Everhart; Tao Sun; Lianyi Chen

doi:10.1016/j.ijmachtools.2020.103555

Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding

S. Mohammad H. Hojjatzadeh, Niranjan D. Parab, Qilin Guo, Minglei Qu, Lianghua Xiong, Cang Zhao, Luis I. Escano, Kamel Fezzaa, Wes Everhart, Tao Sun, Lianyi Chen

Research output: Contribution to journal › Article › peer-review

198 Scopus citations

Abstract

Laser powder bed fusion (LPBF) is a 3D printing technology that can print parts with complex geometries that are unachievable by conventional manufacturing technologies. However, pores formed during the printing process impair the mechanical performance of the printed parts, severely hindering their widespread application. Here, we report six pore formation mechanisms that were observed during the LPBF process. Our results reconfirm three pore formation mechanisms - keyhole induced pores, pore formation from feedstock powder and pore formation along the melting boundary during laser melting from vaporization of a volatile substance or an expansion of a tiny trapped gas. We also observe three new pore formation mechanisms: (1) pore trapped by surface fluctuation, (2) pore formation due to depression zone fluctuation when the depression zone is shallow and (3) pore formation from a crack. The results presented here provide direct evidence and insight into pore formation mechanisms during the LPBF process, which may guide the development of pore elimination/mitigation approaches. Since certain laser processing conditions studied here are similar to the situations in high energy density laser welding, the results presented here also have implications for laser welding.

Original language	English
Article number	103555
Journal	International Journal of Machine Tools and Manufacture
Volume	153
DOIs	https://doi.org/10.1016/j.ijmachtools.2020.103555
State	Published - Jun 2020
Externally published	Yes

Funding

The authors would like to thank Alex Deriy at the APS for his help on the beamline experiments. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This work is funded by the Department of Energy's Kansas City National Security Campus Managed by Honeywell Federal Manufacturing & Technologies (FM&T) and National Science Foundation. All data prepared, analyzed and presented have been developed in a specific context of work and was prepared for internal evaluation and use pursuant to that work authorized under the referenced contract. Reference herein to any specific commercial product, process or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof or Honeywell Federal Manufacturing & Technologies, LLC. This publication has been authored by Honeywell Federal Manufacturing & Technologies under Contract No. DE-NA0002839 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes. The authors would like to thank Alex Deriy at the APS for his help on the beamline experiments. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This work is funded by the Department of Energy's Kansas City National Security Campus Managed by Honeywell Federal Manufacturing & Technologies (FM&T) and National Science Foundation . All data prepared, analyzed and presented have been developed in a specific context of work and was prepared for internal evaluation and use pursuant to that work authorized under the referenced contract. Reference herein to any specific commercial product, process or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof or Honeywell Federal Manufacturing & Technologies, LLC. This publication has been authored by Honeywell Federal Manufacturing & Technologies under Contract No. DE-NA0002839 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes.

Funders	Funder number
Alex Deriy
Department of Energy's Kansas City National Security
United States Government
National Science Foundation	DE-NA0002839
U.S. Department of Energy
Office of Science
Argonne National Laboratory	DE-AC02-06CH11357

Keywords

Additive manufacturing
Laser powder bed fusion
Laser welding
Pore formation
X-ray imaging

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.ijmachtools.2020.103555

Cite this

Hojjatzadeh, S. M. H., Parab, N. D., Guo, Q., Qu, M., Xiong, L., Zhao, C., Escano, L. I., Fezzaa, K., Everhart, W., Sun, T., & Chen, L. (2020). Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding. International Journal of Machine Tools and Manufacture, 153, Article 103555. https://doi.org/10.1016/j.ijmachtools.2020.103555

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abstract = "Laser powder bed fusion (LPBF) is a 3D printing technology that can print parts with complex geometries that are unachievable by conventional manufacturing technologies. However, pores formed during the printing process impair the mechanical performance of the printed parts, severely hindering their widespread application. Here, we report six pore formation mechanisms that were observed during the LPBF process. Our results reconfirm three pore formation mechanisms - keyhole induced pores, pore formation from feedstock powder and pore formation along the melting boundary during laser melting from vaporization of a volatile substance or an expansion of a tiny trapped gas. We also observe three new pore formation mechanisms: (1) pore trapped by surface fluctuation, (2) pore formation due to depression zone fluctuation when the depression zone is shallow and (3) pore formation from a crack. The results presented here provide direct evidence and insight into pore formation mechanisms during the LPBF process, which may guide the development of pore elimination/mitigation approaches. Since certain laser processing conditions studied here are similar to the situations in high energy density laser welding, the results presented here also have implications for laser welding.",

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Hojjatzadeh, SMH, Parab, ND, Guo, Q, Qu, M, Xiong, L, Zhao, C, Escano, LI, Fezzaa, K, Everhart, W, Sun, T & Chen, L 2020, 'Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding', International Journal of Machine Tools and Manufacture, vol. 153, 103555. https://doi.org/10.1016/j.ijmachtools.2020.103555

TY - JOUR

T1 - Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding

AU - Hojjatzadeh, S. Mohammad H.

AU - Parab, Niranjan D.

AU - Guo, Qilin

AU - Qu, Minglei

AU - Xiong, Lianghua

AU - Zhao, Cang

AU - Escano, Luis I.

AU - Fezzaa, Kamel

AU - Everhart, Wes

AU - Sun, Tao

AU - Chen, Lianyi

PY - 2020/6

Y1 - 2020/6

N2 - Laser powder bed fusion (LPBF) is a 3D printing technology that can print parts with complex geometries that are unachievable by conventional manufacturing technologies. However, pores formed during the printing process impair the mechanical performance of the printed parts, severely hindering their widespread application. Here, we report six pore formation mechanisms that were observed during the LPBF process. Our results reconfirm three pore formation mechanisms - keyhole induced pores, pore formation from feedstock powder and pore formation along the melting boundary during laser melting from vaporization of a volatile substance or an expansion of a tiny trapped gas. We also observe three new pore formation mechanisms: (1) pore trapped by surface fluctuation, (2) pore formation due to depression zone fluctuation when the depression zone is shallow and (3) pore formation from a crack. The results presented here provide direct evidence and insight into pore formation mechanisms during the LPBF process, which may guide the development of pore elimination/mitigation approaches. Since certain laser processing conditions studied here are similar to the situations in high energy density laser welding, the results presented here also have implications for laser welding.

AB - Laser powder bed fusion (LPBF) is a 3D printing technology that can print parts with complex geometries that are unachievable by conventional manufacturing technologies. However, pores formed during the printing process impair the mechanical performance of the printed parts, severely hindering their widespread application. Here, we report six pore formation mechanisms that were observed during the LPBF process. Our results reconfirm three pore formation mechanisms - keyhole induced pores, pore formation from feedstock powder and pore formation along the melting boundary during laser melting from vaporization of a volatile substance or an expansion of a tiny trapped gas. We also observe three new pore formation mechanisms: (1) pore trapped by surface fluctuation, (2) pore formation due to depression zone fluctuation when the depression zone is shallow and (3) pore formation from a crack. The results presented here provide direct evidence and insight into pore formation mechanisms during the LPBF process, which may guide the development of pore elimination/mitigation approaches. Since certain laser processing conditions studied here are similar to the situations in high energy density laser welding, the results presented here also have implications for laser welding.

KW - Additive manufacturing

KW - Laser powder bed fusion

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KW - X-ray imaging

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Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding

Abstract

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Keywords

UN SDGs

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