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Failure modes in dual layer thickness Laser Powder Bed Fusion components using a novel post-mortem reconstruction technique

Gullane, Alex; Murray, James W.; Hyde, Christopher J.; Sankare, Simon; Evirgen, Alper; Clare, Adam T.

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Authors

Alex Gullane

James W. Murray

Simon Sankare

Alper Evirgen

ADAM CLARE adam.clare@nottingham.ac.uk
Professor of Manufacturing Engineering



Abstract

To exploit the design freedoms of Powder Bed Fusion, parameters can be varied within sub-volumes of components to achieve the optimal part for both service conditions and manufacturing productivity. This involves prioritising mechanical strength in areas of structural significance and high volumetric build rates in areas of low structural significance. In theory, a component with similar mechanical behaviour to that seen in standard Laser Powder Bed Fusion parts can be built in significantly less time and at a reduced cost. In practice however, the boundary between such regions is yet to be understood and discretising components into sub-volumes can induce interfacial defects. In this study, an in-depth analysis of interfaces between disparate layer thickness volumes in single components has been explored, to gain information vital to solving interface quality issues so that LPBF design freedoms can be fully exploited. A novel 3D reconstruction technique has been demonstrated to characterise transient plastic behaviour of interfacial pores post-fracture. This technique enables post-mortem evaluation of additively manufactured parts and tracking of pore deformation during subsequent mechanical testing. X-ray Computed Tomography (XCT) identified interfacial pores up to 170 µm Feret diameter, with a voxel resolution of 6 µm. Micro tensile testing with in-situ microscopy exhibited a real-time mechanical response, observing evidence that these interfacial defects lead to fracture at interface locations. The 3D reconstruction technique found that pores constricted 10.0 – 14.1% in the x direction and 10.3 – 14.6% in the y direction after fracture – normal to the loading direction. These findings contribute towards improving Additively Manufactured biomedical implants and airframe components with reduced time and cost.

Citation

Gullane, A., Murray, J. W., Hyde, C. J., Sankare, S., Evirgen, A., & Clare, A. T. (2022). Failure modes in dual layer thickness Laser Powder Bed Fusion components using a novel post-mortem reconstruction technique. Additive Manufacturing, 59(Part B), Article 103186. https://doi.org/10.1016/j.addma.2022.103186

Journal Article Type Article
Acceptance Date Sep 28, 2022
Online Publication Date Sep 30, 2022
Publication Date 2022-11
Deposit Date Jan 13, 2023
Publicly Available Date Jan 16, 2023
Journal Additive Manufacturing
Print ISSN 2214-8604
Electronic ISSN 2214-8604
Peer Reviewed Peer Reviewed
Volume 59
Issue Part B
Article Number 103186
DOI https://doi.org/10.1016/j.addma.2022.103186
Keywords Additive manufacturing; Laser Powder Bed Fusion; Layer thickness; Productivity; Porosity; X-ray computed tomography
Public URL https://nottingham-repository.worktribe.com/output/12624907
Publisher URL https://www.sciencedirect.com/science/article/pii/S2214860422005759?via%3Dihub

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