Abstract
Ni-based superalloys, such as alloy 263, have excellent
creep strength at high temperatures due to precipitation
of gamma prime. Therefore they are candidate materials
for thick section components as well as tubing in
advanced ultra-supercritical (A-USC) power plants where
temperatures exceed 700 °C. Because of the lower thermal
expansion coefficient the Ni-based superalloys are less
prone to thermal fatigue damage than the austenitic
stainless steels. A series of creep-fatigue (CF) and low
cycle fatigue (LCF) tests have been performed in order to
study the effect of the test temperature, hold time,
total strain range and a pre-creep exposure of 178MPa /
3000h / 750ºC on the creep-fatigue life of alloy 263. All
LCF and CF tests were per-formed using the high precision
pneumatic loading system (HIPS) at temperatures in the
range of 700-750ºC, the total strain range between
0.5-1.0% and with hold periods up to 10h in both tension
and compression. In this paper stress relaxation time
plots, ?-N plots and ??-N plots are presented for alloy
263. The creep-fatigue test results are analysed using
time fraction ap-proach utilized in the nuclear material
assessment and design codes, such as RCC-MRx and ASME III
NH. The results are compared against public domain data
and fitted to the recently developed ? -model. The ?
-model utilizes the creep rupture strength and tensile
strength for predicting CF life with a minimum amount of
fitting parameters. It is shown that the number of cycles
to failure for CF data for alloy 263 can be accurately
predicted by the ? -model. Furthermore, the practicality
in using the time fraction approach for presenting the
combined CF damage is discussed and recommendations for
alternative approaches are made
| Original language | English |
|---|---|
| Title of host publication | 10th Liege Conference on Materials for Advanced Power Engineering 2014 |
| Editors | Jacqueline Lecomte-Beckers, Olivier Dedry, J. Oakey, B. Kuhn |
| Pages | 678-687 |
| Publication status | Published - 2014 |
| MoE publication type | A4 Article in a conference publication |
| Event | 10th Liège Conference on Materials for Advanced Power Engineering - Palais des Congrès, Liège, Belgium Duration: 14 Sept 2014 → 17 Sept 2014 Conference number: 10 |
Conference
| Conference | 10th Liège Conference on Materials for Advanced Power Engineering |
|---|---|
| Country/Territory | Belgium |
| City | Liège |
| Period | 14/09/14 → 17/09/14 |
Keywords
- superalloys
- nickel
- alloy 263
- creep
- fatigue
- stress
- modelling