Residual Stresses in Alloy IN718 Produced Through Modulated Laser Powder Bed Fusion

K. Georgilas, Hua Guo, Bilal Ahmad, R. H. U. Khan, Michael Fitzpatrick, M. E. Kartal

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Abstract

Background: Laser powder bed fusion (L-PBF) additive manufacturing (AM) is used for building metallic parts layer-by-layer and often generates non-uniform thermal gradients between layers during fabrication, resulting in the development of residual stresses when parts are cooled down.
Objective: The impact of modulated laser used during the L-PBF process on residual stresses in Inconel 718 (IN718) material was investigated. The impact of build directions on residual stress is also determined.
Methods: The contour method is employed to measure the full-field residual stress component on the cross-section of samples. A complementary residual stress measurement method, incremental hole drilling, was employed for obtaining in-plane residual stress components.
Results: The results show that the residual stress distribution is sensitive to the build direction, with a higher magnitude of residual stress in the direction of build than that in the transverse direction. Multiple measurements with the same manufacturing parameters show good repeatability.
Conclusion: Residual stresses in the as-built parts are significant and hence a further consideration regarding relieving residual stresses is required when post-thermal treatments are developed.
Original languageEnglish
Pages (from-to)181-195
Number of pages15
JournalExperimental Mechanics
Volume64
Issue number2
Early online date6 Dec 2023
DOIs
Publication statusPublished - Feb 2024

Bibliographical note

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Funder

The work was financially supported by the Lloyd’s Register Foundation, United Kingdom, a charitable foundation helping to protect life and property by supporting engineering‐related education, public engagement and the application of research. The authors would also like to thank the National Structural Integrity Research Centre (NSIRC) United Kingdom, a postgraduate engineering facility for industry-led research into structural integrity established and managed by TWI through a network of both national and international Universities.

Keywords

  • Residual stresses
  • The contour method
  • Alloy IN718
  • Laser methods
  • Powder methods

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Aerospace Engineering

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