Low-cycle fatigue behavior of P91 Steel
Authors:
- Halina Egner,
- Władysław Egner,
- Stanisław Mroziński
Abstract
P91 steel, which is one of the 9-12%Cr steel family members, is well suited for thick-walled pipes or forgings for the construction of boilers with extremely high operating requirements and steam generators, nuclear reactors, and other responsible devices operating at temperatures up to 6500C. High-temperature components of power plants are subjected to alternating cyclic changes in temperature and mechanical load, i.e. to thermomechanical fatigue. The commonly used fatigue life prediction models, such as the Coffin–Manson model or S–N curve-related models are based on the assumption that the response of a material experiencing low cycle fatigue loading is stabilized during some period. However, for many materials, P91 steel among them, such a stabilized state is hardly observed. In the case of such non-stabilizing steels, the common challenges are selecting and performing a suitable set of experimental tests to recognize various aspects of the material behavior under low-cycle thermomechanical fatigue, and adjusting proper constitutive modeling reflecting the real physical phenomena taking place in the material microstructure. Additionally, during the reparation of the power plant units, the variable load is often stopped, while the constant load is maintained, causing creep, which changes the nature of the load and the durability of the objects. In such a case, predicting the fatigue life based on the commonly used fatigue characteristics may lead to divergence between the experimental and predicted results. For the tests described in the present work, the load programs include: monotonic tensile/compressive tests, creep tests, low-cycle fatigue tests, tests in which the samples were subjected to alternating fatigue and creep loads in various order, and tests in which the samples were subjected to fatigue with a dwell time in each cycle. It was observed that the creep periods alternating with the fatigue load, as well as dwell time, reduce the fatigue life. Moreover, the sequence of events in the load program influences the durability of samples. It can be concluded that the creep failure and the fatigue failure are not independent, therefore the commonly used linear damage summation concept, which is insensitive to the sequence of load events, may lead to significant differences between the results of simulations and experimental tests. Disregarding the damage caused by creep in durability calculations may lead to significantly erroneous predictions.
- Record ID
- CUTfd2ddfa6415044f3b1d5e28b4efdb6ce
- Publication categories
- ; ;
- Author
- Pages
- 213
- Substantive notes
- Data wyd. wg daty konf.
- Book
- Diouri Abdeljebbar, Abdeljebbar Diouri Khachani Nacer, Nacer Khachani Saadi Mohamed Mohamed Saadi [et al.] (eds.): 4th International Congress on Materials & Structural Stability & RILEM Spring Convention, Rabat, Morocco, March 8-10, 2023 : abstracts & proceedings, 2023, [Rabat], [Mohammed V University]
- Keywords in English
- P91 steel, thermomechanical fatigue, creep failure
- URL
- https://www.rsc-cmss23.asmatec.org/Abstract%20Proceedings%20CMSS23.php Opening in a new tab
- Language
- eng (en) English
- License
- Score (nominal)
- 0
- Uniform Resource Identifier
- https://cris.pk.edu.pl/info/article/CUTfd2ddfa6415044f3b1d5e28b4efdb6ce/
- URN
urn:pkr-prod:CUTfd2ddfa6415044f3b1d5e28b4efdb6ce
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