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

doi:10.3390/ma15062238

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

Metallurgy and Materials

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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 language	English
Article number	2238
Number of pages	12
Journal	Materials
Volume	15
Issue number	6
DOIs	https://doi.org/10.3390/ma15062238
Publication status	Published - 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. The North West Centre for Advanced Manufacturing (NW CAM) project is supported by the European Union's INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB). The views and opinions in this document do not necessarily reflect those of the European Commission or the Special EU Programmes Body (SEUPB). If you would like further information about NW CAM please contact the lead partner, Catalyst, for details.

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

Keywords

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

ASJC Scopus subject areas

Materials Science(all)
Condensed Matter Physics

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HarkinR2022PowderFinal published version, 2.94 MBLicence: Creative Commons: Attribution (CC BY)

Cite this

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title = "Powder reuse in laser-based powder bed fusion of Ti6Al4V—changes in mechanical properties during a powder top-up regime",

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). ",

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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. The North West Centre for Advanced Manufacturing (NW CAM) project is supported by the European Union's INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB). The views and opinions in this document do not necessarily reflect those of the European Commission or the Special EU Programmes Body (SEUPB). If you would like further information about NW CAM please contact the lead partner, Catalyst, for details. Publisher Copyright: {\textcopyright} 2022 by the authors. Licensee MDPI, Basel, Switzerland.",

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AU - Lupoi, Rocco

AU - McKay, Wilson

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AU - Quinn, Justin

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N2 - 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).

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Powder reuse in laser-based powder bed fusion of Ti6Al4V—changes in mechanical properties during a powder top-up regime

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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