Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Modelling of anisotropic elastic properties in alloy 718 built by electron beam melting
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0002-4087-6467
Linköping University, Division of Engineering Materials, Department of Management and Engineering, Linköping, Sweden.
Linköping University, Division of Engineering Materials, Department of Management and Engineering, Linköping, Sweden.
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0001-7787-5444
2018 (English)In: Materials Science and Technology, ISSN 0267-0836, E-ISSN 1743-2847, Vol. 34, no 5, p. 529-537Article in journal (Refereed) Published
Abstract [en]

Owing to the inherent nature of the process, typically material produced via electron beam melting (EBM) has a columnar microstructure. As a result of that, the material will have anisotropic mechanical properties. In this work, anisotropic elastic properties of EBM built Alloy 718 samples at room temperature were investigated by using experiments and modelling work. Electron backscatter diffraction data from the sample microstructure was used to predict the Young’s modulus. The results showed that the model developed in the finite element software OOF2 was able to capture the anisotropy in the Young’s modulus. The samples showed transversely isotropic elastic properties having lowest Young’s modulus along build direction. In addition to that, complete transversely isotropic stiffness tensor of the sample was also calculated. © 2018 Institute of Materials, Minerals and Mining.

Place, publisher, year, edition, pages
2018. Vol. 34, no 5, p. 529-537
Keywords [en]
Elastic constants; Elasticity; Electron beam melting; Electron beams; Finite element method; Melting; Microstructure; Models, Alloy 718; Anisotropic elastic properties; Anisotropic mechanical properties; Columnar microstructures; EBSD; Electron back scatter diffraction; Finite element software; Transversely isotropic, Anisotropy
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
URN: urn:nbn:se:hv:diva-12134DOI: 10.1080/02670836.2018.1426258ISI: 000428303200005Scopus ID: 2-s2.0-85041234684OAI: oai:DiVA.org:hv-12134DiVA, id: diva2:1184229
Funder
Knowledge Foundation, SUMAN-Next
Note

Published online: 28 Jan 2018

Funders:  European Regional Development Fund, 3Dprint

Available from: 2018-02-20 Created: 2018-02-20 Last updated: 2020-12-15Bibliographically approved
In thesis
1. Microstructure Modelling of Additive Manufacturing of Alloy 718
Open this publication in new window or tab >>Microstructure Modelling of Additive Manufacturing of Alloy 718
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [sv]

In recent years, additive manufacturing (AM) of Alloy 718 has received increasing interest in the field of manufacturing engineering because of its attractive features compared with those of conventional manufacturing methods. Nevertheless, owing to the inherent nature of the process, the build material is exposed to complex thermal conditions that affect the microstructure. In addition, the post heattreatments applied to the built component further cause microstructural changes. Thus, obtaining the desired microstructure that gives the desired properties is still a challenging task. Therefore, understanding the microstructure formation during the build and subsequent post-heat treatment is important and is the objective of this thesis work.

To this end, a computational modelling approach was used that combines multiphase-field modelling with transformation kinetics modelling. Two different AM processes, laser metal powder directed energy deposition (LM-PDED) and electron beam powder bed fusion (EB-PBF), were considered in this study.Based on the modelling work, it was observed that solidification conditions (thermal gradients and cooling rates) that occur during the AM process have an impact on the as-solidified microstructure in Alloy 718 and the resultant Laves phase formation. With an increase in cooling rate, the Laves phase volume fraction becomes lower and the morphology tends to become discrete particles,which is important for resisting the formation of liquation cracks in Alloy 718. It was also found that the precipitates formed during the solidification process did not undergo any significant change during subsequent thermal cycles associated with the deposition of subsequent layers, given that the deposition of the subsequent layer does not increase the global temperature of the build to> 600 °C. If the global temperature increases above 600 °C, then phase changes are expected, depending on the temperature value. In the case of the EB-PBF process, the high build temperature maintained in the build chamber resulted in an ‘‘in situ’’ heat treatment, which had a homogenisation effect on the as-solidified microstructure because of the smaller dendrite spacing and relatively low Lavesphase size. In the case of the LM-PDED, the microsegregation of composition observed in the as-built microstructure was shown to change the equilibrium conditions and precipitation kinetics of Alloy 718. As a result, excess precipitationof γ'/γ″ and δ was observed in the interdendritic region compared with the dendrite core, depending on the type of heat treatment used.

In addition, modelling was performed to evaluate the elastic properties of EB-PBF Alloy 718. To this end, crystallographic orientation data gathered from EBSD data and single-crystal elastic constants were used. The prediction showed good agreement with published literature data. The hatch (bulk) region of the EB-PBF samples showed significant anisotropic elastic properties because of the strong crystallographic texture observed in the microstructure. The lowest Young’s modulus was observed along the build direction. Normal to the build direction, the elastic properties were shown to be isotropic. Overall, the elastic behaviour of the hatch region was similar to that of a transversely isotropic case

Place, publisher, year, edition, pages
Trollhättan: University West, 2020. p. 89
Series
PhD Thesis: University West ; 43
Keywords
Phase-Field Modelling; Additive Manufacturing; Phase Transformation; Solidification; Heat Treatment; Superalloy
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-16118 (URN)978-91-88847-83-6 (ISBN)978-91-88847-82-9 (ISBN)
Public defence
2020-12-16, 10:00 (English)
Opponent
Supervisors
Available from: 2020-12-15 Created: 2020-12-15

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textScopus

Authority records

Kumara, ChamaraNylén, Per

Search in DiVA

By author/editor
Kumara, ChamaraNylén, Per
By organisation
Division of Subtractive and Additive Manufacturing
In the same journal
Materials Science and Technology
Manufacturing, Surface and Joining Technology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 277 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf