PSI - Issue 68

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com ScienceDirect

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ScienceDirect

Procedia Structural Integrity 68 (2025) 279–284

European Conference on Fracture 2024 Effects of Pressurized Water Reactor Environment and Cyclic Loading Parameters on the Low Cycle Fatigue Behavior of 316L Stainless Steel

Aleks Vainionpää a , Zaiqing Que a, *, Tommi Seppänen a a VTT Technical Research Centre of Finland, Kivimiehentie 3, 02150 Espoo, Finland

Abstract Austenitic stainless steels used in light water reactor coolant environments can be susceptible to environmentally assisted fatigue due to non-monotonic loading conditions. Effects of a pressurized water reactor (PWR) environment containing hydrogen and cyclic loading parameters on the low cycle fatigue (LCF) behavior of 316L stainless steel were investigated by comprehensive striation spacing evaluation. The exposure to a PWR environment results in a decreased LCF lifetime, an enhanced fatigue crack initiation, and an accelerated fatigue crack growth rate of 316L austenitic stainless steel. The effect of the loading waveform (periodic underload PUL, periodic overload POL, and constant amplitude sawtooth CA) was also evaluated. PUL reduces the low cycle fatigue lifetime, accelerates the fatigue crack growth rate, and advances the cycle where initiation of fatigue crack occurs compared to CA loading. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers Keywords: Low cycle fatigue; environmentally assisted fatigue; austenitic stainless steel; pressurized water reactor; hydrogen. 1. Introduction Austenitic stainless steels are extensively utilized in the primary circuit pipelines of nuclear power plants (NPP) due to their excellent mechanical properties and resilience against corrosion in high-temperature water environments. However, prolonged exposure to a pressurized water reactor (PWR) primary water environment can lead to © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers

* Corresponding author. Tel.: +34 943 712400 E-mail address: zaiqing.que@vtt.fi

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers 10.1016/j.prostr.2025.06.054