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

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


V.L. Ratia

D. Zhang

M.J. Carrington

D.G. McCartney

D.A. Stewart


Cobalt-based Stellite alloys are widely used in the primary circuit of pressurized water reactors (PWR) to protect valve surfaces against wear and galling in a corrosive environment. In this study, self-mated sliding wear of HIP-consolidated (Hot Isostatically Pressed) Stellite 6 (Co − 27.1 Cr − 1.5 Si − 5.0 W − 0.96 C, in wt %) was investigated. A pin-on-disc apparatus was enclosed in an autoclave and wear was measured in water from room temperature up to 250 °C (a representative PWR environment). Samples were characterized before and after wear testing using mass measurements, profilometry, X-ray diffraction and scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD). The bulk HIPed alloy is predominantly two phase and comprises a cobalt-rich fcc matrix and an M7C3 carbide phase. However, surface grinding prior to wear testing causes a surface layer of the matrix to partially transform to hcp Co-rich phase. The wear (mass loss) is very low below 150 °C but increases by approximately an order of magnitude when the temperature is increased from 150 to 250 °C. SEM/EBSD reveals sub-surface damage and partial fcc to hcp transformation of the Co-rich matrix phase to a depth of ~ 15 μm in the disc. However, there is little change in transformation behavior and depth with temperature and this is not regarded as significant cause of the increased wear. The order of magnitude increase in wear is instead ascribed to a tribocorrosion mechanism associated with significantly higher corrosion rates at 250 °C than at 150 °C. As the material removal and factors affecting it are found to be so dependent on temperature, this work demonstrates the necessity of conducting assessments of materials for use in PWR environments under representative conditions.


Ratia, V., Zhang, D., Carrington, M., Daure, J., McCartney, D., Shipway, P., & Stewart, D. (2019). The effect of temperature on sliding wear of self-mated HIPed Stellite 6 in a simulated PWR water environment. Wear, 420-421, 215-225.

Journal Article Type Article
Acceptance Date Sep 29, 2018
Online Publication Date Oct 19, 2018
Publication Date Feb 15, 2019
Deposit Date Oct 26, 2018
Publicly Available Date Nov 26, 2018
Journal Wear
Print ISSN 0043-1648
Electronic ISSN 1873-2577
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 420-421
Pages 215-225
Keywords Sliding wear; Stellite 6; Cobalt based alloys; Electron backscatter diffraction
Public URL
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