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Understanding keyhole induced-porosities in laser powder bed fusion of aluminum and elimination strategy

Guo, Liping; Wang, Hongze; Liu, Hanjie; Huang, Yuze; Wei, Qianglong; Alex Leung, Chu Lun; Wu, Yi; (2023) Understanding keyhole induced-porosities in laser powder bed fusion of aluminum and elimination strategy. International Journal of Machine Tools and Manufacture , 184 , Article 103977. 10.1016/j.ijmachtools.2022.103977. Green open access

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Abstract

Laser powder bed fusion (LPBF) technology has the potential to revolutionize the fabrication of complex metal components in the aerospace, medical, and automotive industries. However, keyhole pores may be induced during the rapid laser-metal interaction (∼10−5 s) of the LPBF. These inner porosities can potentially affect the mechanical properties of the fabricated parts. Here, based on the experimentally observed keyhole-penetration pore (KP-pore) led by the keyhole splitting of the molten pool in LPBF, a multi-physics finite volume model was established to reveal this mechanism, where keyhole pores were formed under the direct contact of keyhole and solid metal substrate, which is different from the previously reported gas–liquid interaction. The formation mechanisms of the KP-pore, rear-front pore (RF-pore), and rear pore (R-pore) could be attributed to different keyhole fluctuation modes. The effects of the powder on the characteristics of the keyhole, molten pool, and pore formation were explored. The increased pore counts and decreased size were owing to the powder-promoting keyhole and molten pool oscillation. In addition, a relationship map between the input energy density and pore number was built via a high-throughput simulation, providing a strategy to reduce or remove the pores in laser powder bed fusion.

Type: Article
Title: Understanding keyhole induced-porosities in laser powder bed fusion of aluminum and elimination strategy
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.ijmachtools.2022.103977
Publisher version: https://doi.org/10.1016/j.ijmachtools.2022.103977
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Laser powder fusion, Simulation, Keyhole pore, Mechanism
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10159796
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