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

Liping Guo, Hongze Wang, Hanjie Liu, Yuze Huang, Qianglong Wei, Chu Lun Alex Leung, Yi Wu, Haowei Wang

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

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.

Original languageEnglish
Article number103977
JournalInternational Journal of Machine Tools and Manufacture
Volume184
Early online date14 Nov 2022
DOIs
Publication statusPublished - Jan 2023

Bibliographical note

Funding Information:
This work is sponsored by National Natural Science Foundation of China ( 52004160 and 52075327 ), Shanghai Sailing Program ( 20YF1419200 ), Natural Science Foundation of Shanghai ( 20ZR1427500 ) and Major Science and Technology Project of Huaibei ( Z2020001 ). CLAL acknowledges financial support from the EPSRC MAPP Future Manufacturing Hub ( EP/P006566/1 , www.mapp.ac.uk ), Manufacturing by Design ( EP/W003333/1 ) and Made Smarter Innovation – Materials Made Smarter Research Centre ( EP/V061798/1 ); Data-driven, Reliable, and Effective Additive Manufacturing using multi-BEAM technologies ( EP/W037483/1 ); Performance-driven design of aluminium alloys for additive manufacturing (PAAM) ( EP/W006774/1 ). YH acknowledges financial support from the Innovate UK for the Advanced Propulsion Centre (APC12) H1perChain project (grant number 113244 ).

Publisher Copyright:
© 2022 Elsevier Ltd

Keywords

  • Keyhole pore
  • Laser powder fusion
  • Mechanism
  • Simulation

ASJC Scopus subject areas

  • Mechanical Engineering
  • Industrial and Manufacturing Engineering

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