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A novel ultra-high strength maraging steel with balanced ductility and creep resistance achieved by nanoscale β-NiAl and Laves phase precipitates
L. Sun,
T.H. Simm,
T.L. Martin,
S. McAdam,
D.R. Galvin,
K.M. Perkins,
P.A.J. Bagot,
M.P. Moody,
S.W. Ooi,
P. Hill,
M.J. Rawson,
H.K.D.H. Bhadeshia,
Karen Perkins 
,
Thomas Simm
,
Thomas Simm
Acta Materialia, Volume: 149, Pages: 285 - 301
Swansea University Authors:
Karen Perkins , Thomas Simm
-
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DOI (Published version): 10.1016/j.actamat.2018.02.044
Abstract
A novel ultra-high strength precipitation hardened martensitic steel with balanced ductility and creep resistance has been developed. It utilises a unique combination of nanometre scale intermetallic precipitates of Laves phases and β-NiAl to achieve such properties. The mechanical properties of thi...
| Published in: | Acta Materialia |
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| ISSN: | 1359-6454 |
| Published: |
2018
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa39001 |
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| Abstract: |
A novel ultra-high strength precipitation hardened martensitic steel with balanced ductility and creep resistance has been developed. It utilises a unique combination of nanometre scale intermetallic precipitates of Laves phases and β-NiAl to achieve such properties. The mechanical properties of this steel were assessed by tensile and creep testing. With different heat treatments, this steel showed a remarkable combination of mechanical properties: yield strength of >1800 MPa, ultimate tensile strength of ∼2000 MPa, tensile ductility up to ∼8% at room temperature and creep rupture life >2000 h under 700 MPa stress at 500 °C. The microstructures at different length scales were characterised using scanning/transmission electron microscopy and atom probe tomography. The austenisation and ageing temperatures were found be the key factors determining the microstructural development and resulting mechanical properties. Large primary Laves phase precipitates formed at lower austenisation temperatures resulted in reduced creep strength; whilst the small difference (20 °C) in ageing temperatures had significant impact on the spatial distribution characteristics of β-NiAl precipitates. Lower ageing temperature produced much smaller but more uniformly distributed β-NiAl precipitates which contributed to the higher observed yield strength. It is clear from this study that whilst this novel alloy system showed great potentials, careful design of heat treatment is still required to achieve balanced mechanical properties to meet the service requirements in aerospace propulsion systems. |
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| Keywords: |
Steel; Precipitation; Nanostructure; Transmission electron microscopy (TEM); Atom probe tomography (APT) |
| College: |
Faculty of Science and Engineering |
| Start Page: |
285 |
| End Page: |
301 |