Abstract
High cost of metal powders has increased the demand for recycling of unmelted powder in electron beam powder bed fusion additive manufacturing process. However, powder characteristics are likely to change during manufacturing, recovery and reuse. It is important to track the evolution of powder characteristics at different stages of recycling to produce components with consistent properties. The present work evaluates the changes in Ti6Al4V powder properties during manufacturing by characterising powder particles at different locations in the powder bed; recovery and reuse, through evaluating the effects of the powder recovery system and sieving for 10 build cycles. Heterogeneous powder degradation occurred during manufacturing with the particles closer to the melt zone showing higher oxygen content and thicker α laths with β phase boundaries. Most of them had a hard- sintered and agglomerated powder morphology in contrast to particles at the edges of the powder bed. Recovery and reuse resulted in a refined particle size distribution, but only marginal change in powder morphology. The increased oxygen caused a slight increase in the yield and tensile strengths of the build. The effect of powder reuse on material elongation, hardness and Charpy impact energy was negligible. The high cycle fatigue per- formance deteriorated with reuse due to the increased lack-of-fusion defects. This might be attributed to the voids formed in the powder bed due to decrease in the number of fine particles coupled with an increase in the number of high-aspect ratio particles
| Original language | English |
|---|---|
| Article number | 102101 |
| Number of pages | 14 |
| Journal | Additive Manufacturing |
| Volume | 46 |
| Early online date | 5 Jun 2021 |
| DOIs | |
| Publication status | Published - Oct 2021 |
Bibliographical note
NOTICE: this is the author’s version of a work that was accepted for publication in Additive Manufacturing. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Additive Manufacturing, 46, (2021) DOI: 10.1016/j.addma.2021.102101© 2021, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Funder
This research was made possible by the sponsorship and support of the Lloyd's Register Foundation. The financial support from the EPSRC Fellowship EP/R043973/1 awarded to Bo Chen is acknowledged to facilitate this research collaboration. The authors acknowledge the XCT facility and analysis at the Research Complex at Harwell (RCaH), funded through the UK-EPSRC MAPP: Future Manufacturing Hub in Manufacture using Advanced Powder Processes (EP/P006566/1) and a Royal Academy of Engineering Chair in Emerging Technology (CiET1819/10). EH-N would like to acknowledge the Henry Royce Institute for Advanced Materials, funded through EPSRC grants EP/R00661X/1, EP/S019367/1, EP/P02470X/1 and EP/P025285/1 for access to the ARCAM Q10+ system at The University of Sheffield. C.L.A.L. is grateful for the EPSRC grant (EP/R511638/1) to work on this project.Keywords
- Additive manufacturing
- Build properties
- Electron beam powder bed fusion
- Powder characteristics
- Powder reuse
ASJC Scopus subject areas
- Biomedical Engineering
- Materials Science(all)
- Engineering (miscellaneous)
- Industrial and Manufacturing Engineering