Microstructural characterisation of subsurface deformation and the degradation of Stellite 6 induced by self-mated sliding contact in a simulated PWR environment

M. J. Carrington; J. L. Daure; V. L. Ratia-Hanby; Deen Zhang; P. H. Shipway; D. A. Stewart; D. G. McCartney

doi:10.1016/j.triboint.2021.106899

Microstructural characterisation of subsurface deformation and the degradation of Stellite 6 induced by self-mated sliding contact in a simulated PWR environment

M. J. Carrington^*, J. L. Daure, V. L. Ratia-Hanby, Deen Zhang, P. H. Shipway, D. A. Stewart, D. G. McCartney

^*Corresponding author for this work

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Abstract

Stellite 6 (Co-29.5%Cr-5%W-1.2%C in wt%) is traditionally used as a hardfacing material in the primary circuit of pressurised water reactors (PWRs) due to its good corrosion and wear resistance in water at up to 300 °C. In this study, pin-on-disc type sliding contact tribocorrosion testing was conducted on HIPed Stellite 6 at 20 °C and 250 °C using a bespoke tribometer to simulate a primary circuit environment. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to characterize, for the first time, the material affected by tribocorrosion. Whilst the material loss increases by 16–39 times when the test temperature is increased from 20 °C to 250 °C, the mechanisms of degradation and deformation remain largely unchanged. Furthest from the sliding contact, strain is principally accommodated by the deformation-induced transformation of the γ Co-based matrix to ε-martensite. Closer to the sliding contact, the ε-martensite phase accommodates further strain via twinning and dislocation slip. At the sliding contact the intense deformation generates a nanocrystalline structure. The tribologically affected material is resistant to plastic strain localisation; this confines wear to the nanoscale where the synergistic effects of chemical degradation and mechanical deformation permit the removal of nanoscale particulates (corrosion enhanced nanowear (tribocorrosion)). The increased wear rate at 250 °C is attributed to a temperature dependent increase in corrosion enhanced nanowear. The degradation mechanisms revealed are important for the design of future hardfacings.

Original language	English
Article number	106899
Journal	Tribology International
Volume	158
DOIs	https://doi.org/10.1016/j.triboint.2021.106899
Publication status	Published - Jun 2021
MoE publication type	A1 Journal article-refereed

Funding

The authors gratefully acknowledge funding from Rolls-Royce plc. M.J. Carrington also acknowledges funding from the Faculty of Engineering, University of Nottingham in support of a PhD studentship. The authors thank the Nanoscale and Microscale Research Centre (nmRC) for providing access to instrumentation. Access to the JEOL 7100F FEG-SEM was supported by the Engineering and Physical Sciences Research Council (EPSRC) [under grant EP/L022494/1 ] and the University of Nottingham . The authors also wish to thank Dr. Geoff West of the Warwick Manufacturing Group (WMG) at the University of Warwick for his technical assistance concerning TEM and TEM sample preparation.

Keywords

Hardfacing
Sliding contact
Transmission electron microscopy
Tribocorrosion

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10.1016/j.triboint.2021.106899

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Carrington, M. J., Daure, J. L., Ratia-Hanby, V. L., Zhang, D., Shipway, P. H., Stewart, D. A., & McCartney, D. G. (2021). Microstructural characterisation of subsurface deformation and the degradation of Stellite 6 induced by self-mated sliding contact in a simulated PWR environment. Tribology International, 158, Article 106899. https://doi.org/10.1016/j.triboint.2021.106899

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title = "Microstructural characterisation of subsurface deformation and the degradation of Stellite 6 induced by self-mated sliding contact in a simulated PWR environment",

abstract = "Stellite 6 (Co-29.5%Cr-5%W-1.2%C in wt%) is traditionally used as a hardfacing material in the primary circuit of pressurised water reactors (PWRs) due to its good corrosion and wear resistance in water at up to 300 °C. In this study, pin-on-disc type sliding contact tribocorrosion testing was conducted on HIPed Stellite 6 at 20 °C and 250 °C using a bespoke tribometer to simulate a primary circuit environment. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to characterize, for the first time, the material affected by tribocorrosion. Whilst the material loss increases by 16–39 times when the test temperature is increased from 20 °C to 250 °C, the mechanisms of degradation and deformation remain largely unchanged. Furthest from the sliding contact, strain is principally accommodated by the deformation-induced transformation of the γ Co-based matrix to ε-martensite. Closer to the sliding contact, the ε-martensite phase accommodates further strain via twinning and dislocation slip. At the sliding contact the intense deformation generates a nanocrystalline structure. The tribologically affected material is resistant to plastic strain localisation; this confines wear to the nanoscale where the synergistic effects of chemical degradation and mechanical deformation permit the removal of nanoscale particulates (corrosion enhanced nanowear (tribocorrosion)). The increased wear rate at 250 °C is attributed to a temperature dependent increase in corrosion enhanced nanowear. The degradation mechanisms revealed are important for the design of future hardfacings.",

keywords = "Hardfacing, Sliding contact, Transmission electron microscopy, Tribocorrosion",

author = "Carrington, {M. J.} and Daure, {J. L.} and Ratia-Hanby, {V. L.} and Deen Zhang and Shipway, {P. H.} and Stewart, {D. A.} and McCartney, {D. G.}",

note = "Funding Information: The authors gratefully acknowledge funding from Rolls-Royce plc. M.J. Carrington also acknowledges funding from the Faculty of Engineering, University of Nottingham in support of a PhD studentship. The authors thank the Nanoscale and Microscale Research Centre (nmRC) for providing access to instrumentation. Access to the JEOL 7100F FEG-SEM was supported by the Engineering and Physical Sciences Research Council (EPSRC) [under grant EP/L022494/1 ] and the University of Nottingham . The authors also wish to thank Dr. Geoff West of the Warwick Manufacturing Group (WMG) at the University of Warwick for his technical assistance concerning TEM and TEM sample preparation. ",

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doi = "10.1016/j.triboint.2021.106899",

language = "English",

volume = "158",

journal = "Tribology International",

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AU - Carrington, M. J.

AU - Daure, J. L.

AU - Ratia-Hanby, V. L.

AU - Zhang, Deen

AU - Shipway, P. H.

AU - Stewart, D. A.

AU - McCartney, D. G.

N1 - Funding Information: The authors gratefully acknowledge funding from Rolls-Royce plc. M.J. Carrington also acknowledges funding from the Faculty of Engineering, University of Nottingham in support of a PhD studentship. The authors thank the Nanoscale and Microscale Research Centre (nmRC) for providing access to instrumentation. Access to the JEOL 7100F FEG-SEM was supported by the Engineering and Physical Sciences Research Council (EPSRC) [under grant EP/L022494/1 ] and the University of Nottingham . The authors also wish to thank Dr. Geoff West of the Warwick Manufacturing Group (WMG) at the University of Warwick for his technical assistance concerning TEM and TEM sample preparation.

PY - 2021/6

Y1 - 2021/6

N2 - Stellite 6 (Co-29.5%Cr-5%W-1.2%C in wt%) is traditionally used as a hardfacing material in the primary circuit of pressurised water reactors (PWRs) due to its good corrosion and wear resistance in water at up to 300 °C. In this study, pin-on-disc type sliding contact tribocorrosion testing was conducted on HIPed Stellite 6 at 20 °C and 250 °C using a bespoke tribometer to simulate a primary circuit environment. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to characterize, for the first time, the material affected by tribocorrosion. Whilst the material loss increases by 16–39 times when the test temperature is increased from 20 °C to 250 °C, the mechanisms of degradation and deformation remain largely unchanged. Furthest from the sliding contact, strain is principally accommodated by the deformation-induced transformation of the γ Co-based matrix to ε-martensite. Closer to the sliding contact, the ε-martensite phase accommodates further strain via twinning and dislocation slip. At the sliding contact the intense deformation generates a nanocrystalline structure. The tribologically affected material is resistant to plastic strain localisation; this confines wear to the nanoscale where the synergistic effects of chemical degradation and mechanical deformation permit the removal of nanoscale particulates (corrosion enhanced nanowear (tribocorrosion)). The increased wear rate at 250 °C is attributed to a temperature dependent increase in corrosion enhanced nanowear. The degradation mechanisms revealed are important for the design of future hardfacings.

AB - Stellite 6 (Co-29.5%Cr-5%W-1.2%C in wt%) is traditionally used as a hardfacing material in the primary circuit of pressurised water reactors (PWRs) due to its good corrosion and wear resistance in water at up to 300 °C. In this study, pin-on-disc type sliding contact tribocorrosion testing was conducted on HIPed Stellite 6 at 20 °C and 250 °C using a bespoke tribometer to simulate a primary circuit environment. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to characterize, for the first time, the material affected by tribocorrosion. Whilst the material loss increases by 16–39 times when the test temperature is increased from 20 °C to 250 °C, the mechanisms of degradation and deformation remain largely unchanged. Furthest from the sliding contact, strain is principally accommodated by the deformation-induced transformation of the γ Co-based matrix to ε-martensite. Closer to the sliding contact, the ε-martensite phase accommodates further strain via twinning and dislocation slip. At the sliding contact the intense deformation generates a nanocrystalline structure. The tribologically affected material is resistant to plastic strain localisation; this confines wear to the nanoscale where the synergistic effects of chemical degradation and mechanical deformation permit the removal of nanoscale particulates (corrosion enhanced nanowear (tribocorrosion)). The increased wear rate at 250 °C is attributed to a temperature dependent increase in corrosion enhanced nanowear. The degradation mechanisms revealed are important for the design of future hardfacings.

KW - Hardfacing

KW - Sliding contact

KW - Transmission electron microscopy

KW - Tribocorrosion

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DO - 10.1016/j.triboint.2021.106899

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SN - 0301-679X

VL - 158

JO - Tribology International

JF - Tribology International

M1 - 106899

ER -

Microstructural characterisation of subsurface deformation and the degradation of Stellite 6 induced by self-mated sliding contact in a simulated PWR environment

Abstract

Funding

Keywords

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Comparison of the sliding wear behaviour of self-mated HIPed Stellite 3 and Stellite 6 in a simulated PWR water environment

The effect of temperature on sliding wear of self-mated HIPed Stellite 6 in a simulated PWR water environment

Tribocorrosion Phenomena in Co- and Fe-Based Hardfacing Alloys Evaluated Using Pin-on-Disc Wear Tests in a Simulated PWR Environment

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