PSI - Issue 75

Nina Grözinger et al. / Procedia Structural Integrity 75 (2025) 642–649 Author name / Structural Integrity Procedia (2025)

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In Fig. 5, the lifetimes for the tested specimens at 0.3%, 0.4 % and 0.5 % strain amplitude are compared with literature values from other specimens out of stainless steels tested in air and HTW with similar strain rates, pressures, water chemistry and temperatures. It can be clearly seen, that HTW specimens tend to have shorter lifetimes, as it was also found out with the tested specimens. Also, in literature there is a quite large scattering at each strain amplitude level. Of course, this can be influenced by slightly different strain rates, but nonetheless the data gained in this work shows less scattering and is located in the midfield of the data set. 4. Conclusion and outlook The database for the typically nuclear materials AISI 321 and ER 308L has been extended. Comparisons were drawn between air and HTW environment as well as between base material (AISI 321) and welding material (ER 308L). The specimens tested in HTW had a shorter lifetime than the specimens tested in air. ER 308L specimens have a lower maximum stress than AISI 321 specimens, while there are no significant differences in lifetime between the two materials. In addition to obtaining data, it was also possible to reproduce the method that was used before at MPA (Veile and Weihe 2024), (Veile et al. 2024a), (Veile et al. in review), (Kammerer 2020). A testing program for AISI 316 and AISI 304 specimens is currently being planned with the intention to add data from more materials to the database. Also, it is planned to use a smaller geometry of specimens, making it possible to extract specimens from piping components. Acknowledgements The authors thank the Federal Ministry for Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV), Germany for the financial support of this research project CoVer. Publication bibliography Blug, Andreas; Regina, David Joel; Eckmann, Stefan; Senn, Melanie; Bertz, Alexander; Carl, Daniel; Eberl, Chris (2019): Real-Time GPU-Based Digital Image Correlation Sensor for Marker-Free Strain-Controlled Fatigue Testing. In Applied Sciences 9 (10), p. 2025. DOI: 10.3390/app9102025. Chen, W.; Spätig, P.; Seifert, H. P. (2021): Role of mean stress on fatigue behavior of a 316L austenitic stainless steel in LWR and air environments. In International Journal of Fatigue 145, p. 106111. DOI: 10.1016/j.ijfatigue.2020.106111. Chopra, O. K. (1999): Effects of LWR Coolant Environments on Fatigue Design Curves of Austenitic Stainless Steels (NUREG/CR-5704, ANL-98/31). Washington. Chopra, O. K. (2002): Mechanism and Estimation of Fatigue Crack Initiation in Austenitic Stainless Steels in LWR Environments (NUREG/CR-6787, ANL-01/25). Washington. Chopra, O. K.; Shack, W. J. (2003): Review of the Margins for ASME Code Fatigue Design Curve - Effects of Surface Roughness and Material Variability (NUREG/CR-6815, ANL-02/39). Washington. Chopra, O. K.; Stevens, Gary L. (2018): Effect of LWR Water Environments on the Fatigue Life of Reactor Materials (NUREG/CR-6909, Revision 1) – Final Report. Washington.