Laser powder bed fusion of a β titanium alloy: Microstructural development, post-processing, and mechanical behaviour

Peter Ibrahim, Rebecca Garrard, Moataz m. Attallah*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

β-Titanium alloys demonstrate unique properties, especially their low elastic modulus, good balance of strength and ductility, and strong heat treatment response. In this study, pre-alloyed powder of a β-Ti-alloy Ti–34Nb–13Ta–5Zr-0.3O (TNTZO) was processed using Laser Powder Bed Fusion (LPBF). Dense builds that demonstrate a full β microstructure with limited texture were achieved following process optimisation, with an elastic modulus of 56.5 GPa, tensile strength of 756 MPa, elongation-to-failure of 20 %, and recoverable strain of 1.3 %. Due to the high oxygen content, the β→α′′ deformation induced transformation was supressed, which resulted in a typical elastic-plastic stress-strain behaviour unlike the double-yielding behaviour typically experienced in superelastic Ti-alloys. The alloy was particularly sensitive to ageing heat treatments that resulted in needle α-precipitation, with tensile strengths exceeding 950 MPa, elastic modulus of ∼80 GPa, and recoverable strain of 1.5 %, yet at the expense of a reduced elongation-to-failure of 9 %. Transmission electron microscopy and electron backscattered diffraction investigations revealed the deformation mechanism was slip-dominated with no trace of twinning or stress induced phase transformation.
Original languageEnglish
Article number146617
JournalMaterials Science and Engineering: A
Volume905
Early online date6 May 2024
DOIs
Publication statusPublished - 1 Jul 2024

Bibliographical note

Acknowledgement
The authors acknowledge The Egyptian Ministry of Higher Education & Scientific Research and The British Council (Newton-Mosharafa Fund) represented by The Egyptian Bureau for Cultural & Educational Affairs in London.

Keywords

  • Additive manufacturing
  • Titanium alloys
  • Microstructure
  • Mechanical properties

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