Freeman, F. orcid.org/0000-0002-7402-1790, Chechik, L. orcid.org/0000-0002-7626-2694, Thomas, B. et al. (1 more author) (2023) Calibrated closed-loop control to reduce the effect of geometry on mechanical behaviour in directed energy deposition. Journal of Materials Processing Technology, 311. 117823. ISSN 0924-0136
Abstract
Directed energy deposition (DED) is an emerging technology with significant industrial potential in the repair of critical aerospace components, however its adoption has been limited by concerns about geometry-driven microstructural and mechanical property variation. These could be resolved by controlling the local temperature field, which would result in a consistent and predictable cooling profile. Closed-loop control approaches have been investigated previously, but with limited assessment of mechanical properties and only on small builds. In this work, we confirm that using fixed build parameters results in a statistically significant, geometry-driven variation in the bulk mechanical properties of DED-built 316 L steel. To address this issue, we have developed an industrially-suitable control algorithm using a low-cost coaxial camera, applying statistical process control techniques to identify representative melt pool images from the livestream. This has been tested on long builds, maintaining a control adjustment frequency of 1 Hz on build durations of > 1 h. Performance has been quantified through bulk mechanical testing, which confirmed that the control algorithm successfully eliminated the component-scale trends in melt pool size, and achieved a geometry-agnostic process with improved mechanical homogeneity.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022 The Authors. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Directed energy deposition; Closed loop control; Melt pool monitoring; Mechanical properties; Additive manufacturing |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Funding Information: | Funder Grant number EUROPEAN COMMISSION - HORIZON 2020 820776 Engineering and Physical Sciences Research Council EP/P02470X/1 Engineering and Physical Sciences Research Council EP/P025285/1 Engineering and Physical Sciences Research Council EP/P006566/1 Engineering and Physical Sciences Research Council EP/S019367/1 Engineering and Physical Sciences Research Council EP/R00661X/1 ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/X038661/1 ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL UNSPECIFIED |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 02 Dec 2022 13:52 |
Last Modified: | 02 Dec 2022 13:52 |
Status: | Published |
Publisher: | Elsevier BV |
Refereed: | Yes |
Identification Number: | 10.1016/j.jmatprotec.2022.117823 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:194006 |