In-situ characterization of pore formation dynamics in pulsed wave laser powder bed fusion

Seyed Mohammad H. Hojjatzadeh, Qilin Guo, Niranjan D. Parab, Minglei Qu, Luis I. Escano, Kamel Fezzaa, Wes Everhart, Tao Sun*, Lianyi Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Laser powder bed fusion (LPBF) is an additive manufacturing technology with the capability of printing complex metal parts directly from digital models. Between two available emission modes employed in LPBF printing systems, pulsed wave (PW) emission provides more control over the heat input compared to continuous wave (CW) emission, which is highly beneficial for printing parts with intricate features. However, parts printed with pulsed wave LPBF (PW-LPBF) commonly contain pores, which degrade their mechanical properties. In this study, we reveal pore formation mechanisms during PW-LPBF in real time by using an in-situ high-speed synchrotron x-ray imaging technique. We found that vapor depression collapse proceeds when the laser irradiation stops within one pulse, resulting in occasional pore formation during PW-LPBF. We also revealed that the melt ejection and rapid melt pool solidification during pulsed-wave laser melting resulted in cavity formation and subsequent formation of a pore pattern in the melted track. The pore formation dynamics revealed here may provide guidance on developing pore elimination approaches.

Original languageEnglish (US)
Article number2936
Issue number11
StatePublished - Jun 1 2021


  • Additive manufacturing
  • Laser powder bed fusion
  • Pore
  • Pulsed emission
  • X-ray imaging

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics


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