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Thickness dependency of surface properties for thin-walled titanium parts manufactured by Electron Beam Melting (EBM®)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.ORCID iD: 0000-0002-5292-2504
Dept of Materials Science & Engineering, School of Biomedical Engineering, McMaster University, Cananda.
Center for Additive Manufacturing and Logistics, North Carolina State University.
Center for Additive Manufacturing and Logistics, North Carolina State University.
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(English)In: Additive Manufacturing Journal, ISSN 2214-8604Article in journal (Refereed) Submitted
Abstract [en]

The surface morphology of components produced by powder bed metal additive manufacturing is of interest for multiple industry sectors including biomedical and aerospace.  For some applications, improvements in surface finish can reduce or eliminate the requirement for secondary finishing processes. In this study, titanium alloy (Ti6Al4V) samples were manufactured using the Electron Beam Melting (EBM) process. The effect of variations in sample thickness, powder size distribution and layer thickness were measured with three different techniques, both for direct measurement and comparison of the techniques.  Ra-values in the range of 15 µm – 37 µm were obtained and varied depending on measurement technique. However, independent of technique, Ra values were found to be dependent on powder size distribution, build layer thickness, and wall thickness. Analytical transmission electron microscopy of cross sections prepared by focused ion beam milling revealed that the outermost surfaces consisted of an oxide layer of 5 nm -6 nm thickness.

Keyword [en]
Additive Manufacturing, Electron Beam Melting, Ti-6Al-4V, Surface roughness, Surface properties, Transmission Electron Microscopy
National Category
Metallurgy and Metallic Materials Medical Materials Production Engineering, Human Work Science and Ergonomics
Research subject
Engineering Science with specialization in Materials Science
Identifiers
URN: urn:nbn:se:uu:diva-236638OAI: oai:DiVA.org:uu-236638DiVA: diva2:764846
Available from: 2014-11-20 Created: 2014-11-20 Last updated: 2015-02-03
In thesis
1. Optimization of Electron Beam Melting for Production of Small Components in Biocompatible Titanium Grades
Open this publication in new window or tab >>Optimization of Electron Beam Melting for Production of Small Components in Biocompatible Titanium Grades
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Additive manufacturing (AM), also called 3D-printing, are technologies where parts are formed from the bottom up by adding material layer-by-layer on top of each other. Electron Beam Melting (EBM) is an AM technique capable of manufacturing fully solid metallic parts, using a high-intensity electron beam to melt powder particles in layers to form finished components. Compared to conventional machining, EBM offers enhanced efficiency for production of customized and patient specific parts such as e.g. dental prosthetics. However, dental prosthetics are challenging to produce by EBM, as their small sizes mean that mechanical and surface properties may be altered as part sizes decreases.

The aim of this thesis is to gain new insights that could lead to optimization for production of small sized components in the EBM. The work is focused to understand the process-property relationships for small size components production.

To improve the surface resolution and part detailing, a smaller sized powder was used for production and compared to parts made with standard sized powder. The surface-, chemical and mechanical properties were evaluated for parts produced with both types of powders. The results indicate that the surface roughness may be influenced by powder and build layer thickness size, whereas the mechanical properties showed no influence of the layer-wise production. However, the mechanical properties are dependent on part size. The outermost surface of the parts consists of a surface oxide dominated by TiO2, formed as a result of reaction between the surface and residual gases in the EBM build chamber. The surface oxide thickness is comparable to that of a conventionally machined surface, but is dependent on build height.

This work concludes that the surface resolution and component detailing can be improved by various measures. Provided that proper process themes are used, the EBM manufactured material is homogenous with properties comparable to conventional produced titanium. It has also been shown that the material properties will be altered for small components. The results point towards different ways of optimizing manufacturing of dental prosthetics by EBM, which will make dental prosthetics available for an increased number of patients.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 80 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1206
Keyword
Additive Manufacturing, 3D-printing, Electron Beam Melting, Titanium alloys, Chemical properties, Mechanical properties, Surface properties, Additiv tillverkning, 3D-skrivare, Electron Beam Melting, Titan, Kemiska egenskaper, Mekaniska egenskaper, Ytegenskaper
National Category
Production Engineering, Human Work Science and Ergonomics Metallurgy and Metallic Materials Medical Materials
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-236709 (URN)978-91-554-9110-9 (ISBN)
Public defence
2015-01-23, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2014-12-17 Created: 2014-11-21 Last updated: 2015-02-03

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Karlsson, Joakim

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