SYMPOSIA PAPER Published: 01 January 1987
STP28146S

Cumulative Fatigue and Creep-Fatigue Damage at 350°C on Recrystallized Zircaloy-4

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An experimental program undertaken by CEA, EDF, and FRAGEMA with the aim of characterizing the fatigue and creep-fatigue behavior of Zircaloy-4 following different annealing treatments (recrystallization, stress relief, etc.) is in progress. The results given in this paper concern only recrystallized material. Low-cycle fatigue curves and creep behavior laws under high stresses have been established. Sequential tests of pure fatigue and creep-fatigue were performed.

The cumulative life fractions at fracture depend on the sequence of loading, stress history, and number of cycles of prestressing. Miner's rule appears to be conservative with regard to a low-high loading sequence, whereas it is not for the reverse high-low loading sequences. Fatigue and creep damage are not interchangeable. Pre-creep improves the fatigue resistance. Pre-fatigue improves the creep strength so long as the beneficial effect of cyclic hardening overcomes the damaging effect of surface cracking. The introduction of a tension hold time into the fatigue cycle slightly increases cyclic hardening and reduces the number of cycles to failure. For hold times of less than 1 h, the sum of fatigue and creep life fractions is close to one.

Author Information

Brun, G
Commissariat à l'Energie Atomique, Saclay, France
Pelchat, J
Commissariat à l'Energie Atomique, Saclay, France
Floz, JC
FRAGEMA, Lyon, France
Galimberti, M
Electricité de France, Lyon, France
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Details
Developed by Committee: B10
Pages: 597–616
DOI: 10.1520/STP28146S
ISBN-EB: 978-0-8031-5004-1
ISBN-13: 978-0-8031-0935-3