Powder Reuse in Laser-Based Powder Bed Fusion of Ti6Al4V—Changes in Mechanical Properties during a Powder Top-Up Regime

Ryan Harkin, Hao Wu, Sagar Nikam, Shuo Yin, Rocco Lupoi, Wilson McKay, Patrick Walls, Justin Quinn, Shaun McFadden

Research output: Contribution to journalArticlepeer-review

Abstract

The properties of Extra Low Interstitials (ELI) Ti6Al4V components fabricated via the laser-based powder bed fusion (L-PBF) process are prone to variation, particularly throughout a powder reuse regime. Interstitial pick-up of interstitial elements within the build chamber during processing can occur, most notably, oxygen, nitrogen, and hydrogen, which can impair the mechanical properties of the built component. This study analyses ELI Ti6Al4V components manufactured by the L-PBF process when subjected to a nine-stage powder reuse sequence. Mechanical properties are reported via hardness measurement and tensile testing. Results showed that from 0.099 wt.% to 0.126 wt.% oxygen content, the mean hardness and tensile strength increased from 367.8 HV to 381.9 HV and from 947.6 Mpa to 1030.7 Mpa, respectively, whereas the ductility (area reduction) reduced from around 10% to 3%. Statistical analysis based on the empirical model from Tabor was performed to determine the strength–hardness relationship. Results revealed a significant direct relationship between tensile strength and Vickers hardness with a proportionality constant of 2.61 (R-square of 0.996 and p-value of 6.57 × 10−6 ).

Original languageEnglish
Article number2238
Number of pages12
JournalMaterials
Volume15
Issue number6
Early online date17 Mar 2022
DOIs
Publication statusE-pub ahead of print - 17 Mar 2022

Bibliographical note

Funding Information:
This research was funded by INTERREG VA Programme (IVA5055), managed by the Special EU Programmes Body (SEUPB), as part of the NW CAM project. The APC was funded through the NW CAM project.

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • ELI (Grade 23) Ti6Al4V
  • laser-based powder bed fusion
  • mechanical properties
  • powder recycling
  • Tabor’s relationship

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