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The mechanism of natural age-strengthening of grey cast iron : PEC-ageing

Bello Bermejo, Juan Manuel LU orcid ; Carrero Robles, Jesús LU ; Chen, Huaiyu LU ; Hill Landberg, Megan O. ; Wallentin, Jesper LU ; Hektor, Johan LU ; Magnusson Åberg, Lena ; Borgström, Henrik and Lenrick, Filip LU orcid (2026) In Materials and Design 263.
Abstract

In this work we introduce the concept of natural ageing via precipitation arising from eutectic cell structure (PEC-ageing). Natural age-strengthening in grey cast iron at room temperature is long recognised yet still poorly understood, despite its beneficial effect on tensile strength and machinability. We investigate its underlying mechanisms by comparing fresh and naturally aged industrial grey cast iron using high-resolution synchrotron Wide-Angle X-ray Scattering (WAXS), complemented by scanning electron microscopy and X-ray energy-dispersive spectroscopy. A strict sample-preparation process was designed to minimize artificial ageing and X-ray attenuation artefacts. We present direct experimental evidence of an X-ray diffraction... (More)

In this work we introduce the concept of natural ageing via precipitation arising from eutectic cell structure (PEC-ageing). Natural age-strengthening in grey cast iron at room temperature is long recognised yet still poorly understood, despite its beneficial effect on tensile strength and machinability. We investigate its underlying mechanisms by comparing fresh and naturally aged industrial grey cast iron using high-resolution synchrotron Wide-Angle X-ray Scattering (WAXS), complemented by scanning electron microscopy and X-ray energy-dispersive spectroscopy. A strict sample-preparation process was designed to minimize artificial ageing and X-ray attenuation artefacts. We present direct experimental evidence of an X-ray diffraction peak that forms upon natural ageing in grey cast iron. Based on its position in reciprocal space, a plausible candidate for this peak is the iron nitride phase FeX4N. Spatially resolved analysis further shows that this phase is strongly localised along eutectic cell boundaries, supporting a nitride-related, boundary-mediated precipitation mechanism (PEC-ageing) as the main driver of the ageing phenomenon. These results provide a spatially resolved description of natural ageing in grey cast iron, establish WAXS as a powerful tool to track ageing-related changes in the bulk, and highlight that logistics and sample preparation remain the main practical challenges for future in-situ studies.

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Age-strengthening, Grey cast iron, Natural ageing, Wide-angle X-Ray scattering (WAXS), X-Ray diffraction (XRD)
in
Materials and Design
volume
263
article number
115536
publisher
Elsevier
external identifiers
  • scopus:105036159348
ISSN
0264-1275
DOI
10.1016/j.matdes.2026.115536
language
English
LU publication?
yes
id
430c2a46-94ae-4f62-a879-7c560bda4fd9
date added to LUP
2026-04-28 09:04:26
date last changed
2026-06-09 11:46:14
@article{430c2a46-94ae-4f62-a879-7c560bda4fd9,
  abstract     = {{<p>In this work we introduce the concept of natural ageing via precipitation arising from eutectic cell structure (PEC-ageing). Natural age-strengthening in grey cast iron at room temperature is long recognised yet still poorly understood, despite its beneficial effect on tensile strength and machinability. We investigate its underlying mechanisms by comparing fresh and naturally aged industrial grey cast iron using high-resolution synchrotron Wide-Angle X-ray Scattering (WAXS), complemented by scanning electron microscopy and X-ray energy-dispersive spectroscopy. A strict sample-preparation process was designed to minimize artificial ageing and X-ray attenuation artefacts. We present direct experimental evidence of an X-ray diffraction peak that forms upon natural ageing in grey cast iron. Based on its position in reciprocal space, a plausible candidate for this peak is the iron nitride phase FeX<sub>4</sub>N. Spatially resolved analysis further shows that this phase is strongly localised along eutectic cell boundaries, supporting a nitride-related, boundary-mediated precipitation mechanism (PEC-ageing) as the main driver of the ageing phenomenon. These results provide a spatially resolved description of natural ageing in grey cast iron, establish WAXS as a powerful tool to track ageing-related changes in the bulk, and highlight that logistics and sample preparation remain the main practical challenges for future in-situ studies.</p>}},
  author       = {{Bello Bermejo, Juan Manuel and Carrero Robles, Jesús and Chen, Huaiyu and Hill Landberg, Megan O. and Wallentin, Jesper and Hektor, Johan and Magnusson Åberg, Lena and Borgström, Henrik and Lenrick, Filip}},
  issn         = {{0264-1275}},
  keywords     = {{Age-strengthening; Grey cast iron; Natural ageing; Wide-angle X-Ray scattering (WAXS); X-Ray diffraction (XRD)}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Materials and Design}},
  title        = {{The mechanism of natural age-strengthening of grey cast iron : PEC-ageing}},
  url          = {{http://dx.doi.org/10.1016/j.matdes.2026.115536}},
  doi          = {{10.1016/j.matdes.2026.115536}},
  volume       = {{263}},
  year         = {{2026}},
}