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Thermomechanical fatigue in 9-12Cr steels: Life prediction models and the effect of tensile dwell periods

Barrett, Richard A.; Hyde, Christopher J.; O'Donoghue, Padraic E.; Leen, Sean B.


Richard A. Barrett

Padraic E. O'Donoghue

Sean B. Leen


This paper is concerned with the assessment of life prediction models for thermomechanical fatigue (TMF), with specific application to P91 steel. A program of TMF tests, including dwell periods, are performed to determine the role of thermomechanical loading on fatigue life. As expected, fatigue life under conventional TMF testing (no dwells) is governed by maximum applied stress and inelastic strain-range. However, with the introduction of dwell periods, at maximum tensile stress during TMF loading, in-phase loading becomes the life-limiting case. This is attributed here to increased microstructural degradation and oxidation, associated with the dwell at peak temperature. Analysis of commonly used TMF life prediction models shows that the effect of dwell periods currently cannot be predicted for in-phase loading. Thus, it is concluded that physically-motivated approaches are required to successfully predict fatigue life under more complex (service) thermomechanical loading histories.


Barrett, R. A., Hyde, C. J., O'Donoghue, P. E., & Leen, S. B. (2019). Thermomechanical fatigue in 9-12Cr steels: Life prediction models and the effect of tensile dwell periods. International Journal of Fatigue, 126, 335-345.

Journal Article Type Article
Acceptance Date May 8, 2019
Online Publication Date May 9, 2019
Publication Date 2019-09
Deposit Date May 22, 2019
Publicly Available Date May 10, 2020
Journal International Journal of Fatigue
Print ISSN 0142-1123
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 126
Pages 335-345
Keywords Mechanical Engineering; Modelling and Simulation; Industrial and Manufacturing Engineering; General Materials Science; Mechanics of Materials
Public URL
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