Abstract
Current creep-fatigue evaluation approaches based on the creep-fatigue Damage-diagram are complex and very conservative. Simplified Model Test (SMT) method is an alternative approach to determine cyclic life at elevated temperatures. The SMT-based creep-fatigue evaluation methodology avoids parsing the damage into creep and fatigue components and greatly simplifies the evaluation procedure for elevated-temperature cyclic service. In this study, the effects of sustained primary-stress loading are evaluated in support of the development of SMT-based creep-fatigue design curves for Alloy 617. Experiments were designed and performed using internal pressurized tubular specimens at 950° on Alloy 617. The sustained primary-load was introduced by the internal pressure. A newly developed SMT technique, single-bar SMT, was extended to these tests and SMT creep-fatigue test data were generated with various elastic follow-ups, internal pressures and strain ranges. The test results from this study along with the original SMT data on Alloy 617 demonstrate that, although internal pressure is within the allowable stress limit per ASME Section III Division 5 Code Case N-898, the SMT creep-fatigue cycles to failure were reduced for the cases tested with primarypressure load. The reduction of SMT creep-fatigue life due to primary-load was found to be dependent on strain ranges and elastic follow up. Approaches to handle the primary-load effect on SMT design curves are discussed.
| Original language | English |
|---|---|
| Title of host publication | Codes and Standards |
| Publisher | American Society of Mechanical Engineers (ASME) |
| ISBN (Electronic) | 9780791885314 |
| DOIs | |
| State | Published - 2021 |
| Event | ASME 2021 Pressure Vessels and Piping Conference, PVP 2021 - Virtual, Online Duration: Jul 13 2021 → Jul 15 2021 |
Publication series
| Name | American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP |
|---|---|
| Volume | 1 |
| ISSN (Print) | 0277-027X |
Conference
| Conference | ASME 2021 Pressure Vessels and Piping Conference, PVP 2021 |
|---|---|
| City | Virtual, Online |
| Period | 07/13/21 → 07/15/21 |
Funding
The research was sponsored by the U.S. Department of Energy, Office of Nuclear Energy, under contract No. DE-AC05-00OR22725 with Oak Ridge National Laboratory (ORNL), managed and operated by UT-Battelle, LLC, and under contract No. DE-AC0500OR22725 with Idaho National Laboratory (INL), managed and operated by Battelle Energy Alliance, LLC. Programmatic direction was provided by the Office of Nuclear Reactor Deployment of the Office of Nuclear Energy. This manuscript has been co-authored by Battelle Energy Alliance, LLC, under Contract No. DE-AC07-05ID14517 and by UT-Battelle LLC, under Contract No. DE-AC0500OR22725, with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.
Keywords
- Creep-fatigue
- Elastic-follow-up
- Internal pressure