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A new class of alumina-forming superalloy for 3D printing

A new class of alumina-forming superalloy for 3D printing
A new class of alumina-forming superalloy for 3D printing

A new class of crack-resistant nickel-based superalloy containing high γ fraction is studied for the laser-powder bed fusion (L-PBF) process. The effects of the (Nb+Ta)/Al ratio is emphasized, a strategy that is shown to confer excellent low-temperature strength whilst maintaining oxidation resistance at high temperatures via stable alumina scale formation. The processability of the new alloys is characterized with respect to defect assessment by micro-focus X-ray computed tomography; use is made of a prototype turbine blade geometry and the heritage alloy CM247LC as a benchmark. In all cases, some processing-related porosity is present in thin wall sections such as the trailing edge, but this can be avoided by judicious processing. The cracking seen in CM247LC – in solid-state, liquation and solidification forms – is avoided. A novel sub-solvus heat treatment strategy is proposed which takes advantage of AM not requiring solutioning; super-solvus heat treatment is inappropriate since it embrittles the material by deterioration of the texture and coarsening of grain boundary carbides. The tensile strength of the new superalloy is greatest when the Nb+Ta content is highest and exceeds that of CM247LC up to ∼900°C. The oxidation resistance is best when Al content is highest, and oxidation-assisted cracking resistance maximized when the (Nb+Ta)/Al ratio is balanced. In all cases these are equivalent or superior to that of CM247LC. Nevertheless, the creep resistance of the new alloys is somewhat inferior to that of CM247LC for which the γ , C, and B contents are higher; this implies a processing/property trade-off which requires further clarification.

Additive manufacturing, Alloy design, Creep, Micro-CT, Ni-based superalloys, Oxidation
2214-8604
Ghoussoub, Joseph N.
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Klups, Przemyslaw
101e33f8-ae1b-46a9-ba29-3966e7edca4c
Dick-Cleland, William J. B.
bb4dd49f-7eb4-4d99-ba53-9a072046215b
Rankin, Kathryn E.
d9516566-0ad8-473d-b99b-4683c663a2b7
Utada, Satoshi
ec303ebe-cd4d-4baa-b977-ee36144c707a
Bagot, Paul A. J.
8a06c019-e7c4-4baf-a17f-fa4cf7f6ed1c
McCartney, D. Graham
bd0675ab-8142-449f-8a75-f475e9895e65
Tang, Yuanbo
e97b0a96-87fb-4f92-9acd-415800573958
Reed, Roger C.
a46a2082-23d6-4b81-8ef1-0e2cc6115cfc
Ghoussoub, Joseph N.
f0ef7113-de7a-4ec6-a477-11bc9f712442
Klups, Przemyslaw
101e33f8-ae1b-46a9-ba29-3966e7edca4c
Dick-Cleland, William J. B.
bb4dd49f-7eb4-4d99-ba53-9a072046215b
Rankin, Kathryn E.
d9516566-0ad8-473d-b99b-4683c663a2b7
Utada, Satoshi
ec303ebe-cd4d-4baa-b977-ee36144c707a
Bagot, Paul A. J.
8a06c019-e7c4-4baf-a17f-fa4cf7f6ed1c
McCartney, D. Graham
bd0675ab-8142-449f-8a75-f475e9895e65
Tang, Yuanbo
e97b0a96-87fb-4f92-9acd-415800573958
Reed, Roger C.
a46a2082-23d6-4b81-8ef1-0e2cc6115cfc

Ghoussoub, Joseph N., Klups, Przemyslaw, Dick-Cleland, William J. B., Rankin, Kathryn E., Utada, Satoshi, Bagot, Paul A. J., McCartney, D. Graham, Tang, Yuanbo and Reed, Roger C. (2022) A new class of alumina-forming superalloy for 3D printing. Additive Manufacturing, 52, [102608]. (doi:10.1016/j.addma.2022.102608).

Record type: Article

Abstract

A new class of crack-resistant nickel-based superalloy containing high γ fraction is studied for the laser-powder bed fusion (L-PBF) process. The effects of the (Nb+Ta)/Al ratio is emphasized, a strategy that is shown to confer excellent low-temperature strength whilst maintaining oxidation resistance at high temperatures via stable alumina scale formation. The processability of the new alloys is characterized with respect to defect assessment by micro-focus X-ray computed tomography; use is made of a prototype turbine blade geometry and the heritage alloy CM247LC as a benchmark. In all cases, some processing-related porosity is present in thin wall sections such as the trailing edge, but this can be avoided by judicious processing. The cracking seen in CM247LC – in solid-state, liquation and solidification forms – is avoided. A novel sub-solvus heat treatment strategy is proposed which takes advantage of AM not requiring solutioning; super-solvus heat treatment is inappropriate since it embrittles the material by deterioration of the texture and coarsening of grain boundary carbides. The tensile strength of the new superalloy is greatest when the Nb+Ta content is highest and exceeds that of CM247LC up to ∼900°C. The oxidation resistance is best when Al content is highest, and oxidation-assisted cracking resistance maximized when the (Nb+Ta)/Al ratio is balanced. In all cases these are equivalent or superior to that of CM247LC. Nevertheless, the creep resistance of the new alloys is somewhat inferior to that of CM247LC for which the γ , C, and B contents are higher; this implies a processing/property trade-off which requires further clarification.

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Published date: April 2022
Additional Information: Funding Information: The financial support of this work by Alloyed Ltd. as well as The Natural Sciences and Engineering Research Council of Canada (NSERC) in the Chemical, Biomedical and Materials Science Engineering division award number 532410 . The authors acknowledge funding from Innovate UK , under project number 104047, specifically the Materials and Manufacturing Division, as well as funding for the National X-ray Computed Tomography (NXCT) grant code EP/T02593X/1 from the Engineering and Physical Sciences Research Council (EPSRC), United Kingdom . The authors acknowledge Prof. Ian Sinclair, Dr. David Crudden, Dr. André Németh and Dr. Matthew Fawkes for their support and advisory roles regarding this body of work. Publisher Copyright: © 2022 The Author(s)
Keywords: Additive manufacturing, Alloy design, Creep, Micro-CT, Ni-based superalloys, Oxidation

Identifiers

Local EPrints ID: 454927
URI: http://eprints.soton.ac.uk/id/eprint/454927
ISSN: 2214-8604
PURE UUID: b935f4c3-fd3f-415f-8581-e64811d048d5
ORCID for Kathryn E. Rankin: ORCID iD orcid.org/0000-0002-8458-1038

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Date deposited: 01 Mar 2022 17:51
Last modified: 17 Mar 2024 03:28

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Contributors

Author: Joseph N. Ghoussoub
Author: Przemyslaw Klups
Author: William J. B. Dick-Cleland
Author: Kathryn E. Rankin ORCID iD
Author: Satoshi Utada
Author: Paul A. J. Bagot
Author: D. Graham McCartney
Author: Yuanbo Tang
Author: Roger C. Reed

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