A holistic approach for evaluation of Gaussian versus ring beam processing on structure and properties in laser powder bed fusion

Jaivindra Singh, J. P. Oliveira, Hunter Taylor, Jorge Mireles, Ryan Wicker

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, a holistic evaluation strategy employing a complex test artifact, coupled with single line scan tracks, was employed to examine the influence of different laser beam energy profiles on various features of laser-based powder bed fusion of metals (PBF-LB/M). Using IN718, results revealed a significant influence of the laser beam on bead geometry. Specifically, the conventional Gaussian beam produced deeper, concave-shaped melt pools, while the ring beam resulted in wider and shallower beads. In terms of productivity, the artifacts (two each) fabricated using the Gaussian beam required 6 h and 6 min of build time, while those built using ring beam required only 3 h and 49 min (37% build time reduction) but a defocused Gaussian beam (not included in this study) can match the productivity of the ring beam. However, the holistic approach using the complex test artifact highlighted drawbacks associated with the ring beam, including increased lack of fusion porosity, compromised resolution for features below 0.5 mm, and less than 10% elongation to break in both as built and heat-treated conditions. While acknowledging the potential for improvement through further process optimization, the study concludes that the shallower melt pools produced by the ring beam may cause limitations as layer thicknesses increase. Microstructural analysis revealed distinct grain characteristics, with the Gaussian beam producing more equiaxed grains and the ring beam favouring columnar grains positioned along the build direction. The work primarily highlights the need for and benefits from a holistic analysis in PBF-LB/M technology, ensuring data driven outcomes.
Original languageEnglish
Article number118293
Number of pages14
JournalJournal Of Materials Processing Technology
Volume325
DOIs
Publication statusPublished - Apr 2024

Keywords

  • Beam Shaping
  • Laser powder bed fusion
  • Mechanical properties
  • Microstructure
  • Single line scan
  • Test artifact

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