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On the thermomechanical aging of LPBF alloy 718

On the thermomechanical aging of LPBF alloy 718 Thumbnail



G. Gaspard

Professor of Mechanics of Solids

G. A. Ravi

Professor of Manufacturing Engineering


Heat treatment of products post additive manufacture are considered hugely important since the metallurgical condition post process is suboptimal. In the case of nickel-based superalloys, grain size, precipitate distribution and precipitate size are distinct from wrought equivalents. Appropriate heat treatment is required to ensure material performance. In this study, LPBF alloy 718, post-processed using a standard heat treatment, is explored under thermal and thermomechanical exposure conditions (with and without applied stress) to illustrate textural and microstructural evolution. The results show the instability of the LPBF microstructure in terms of grain size, precipitate density, and crystallographic orientation, illustrating the need for an appropriate heat treatment in relation to future service conditions. During thermal exposure only, the instability of the LPBF alloy microstructure was evident as the texture increased with time before decreasing and almost disappearing at the time of fracture. This contrasts with wrought alloy whose texture increases throughout creep testing and reaches a maximum at the time of fracture. An ideal microstructure for improved creep performance was identified and includes large equiaxed grains, elimination of texture, dissolution of Laves and δ phase and the precipitation of small carbides and γ’’ precipitates. Recommendations on how to heat treat LPBF alloy 718 to reach this microstructure are given. Overall, this work showed that LPBF components may become more performant than wrought and conventional equivalents.


Sanchez, S., Gaspard, G., Hyde, C. J., Ashcroft, I. A., Ravi, G. A., & Clare, A. T. (2022). On the thermomechanical aging of LPBF alloy 718. Materials Science and Engineering: A, 841, Article 142998.

Journal Article Type Article
Acceptance Date Mar 14, 2022
Online Publication Date Mar 29, 2022
Publication Date Apr 28, 2022
Deposit Date Apr 7, 2022
Publicly Available Date Apr 8, 2022
Journal Materials Science and Engineering A
Print ISSN 0921-5093
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 841
Article Number 142998
Keywords Mechanical Engineering; Mechanics of Materials; Condensed Matter Physics; General Materials Science
Public URL
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