Characterization of austenitic Stainless steels with regard to environmentally assisted fatigue in simulated light water reactor conditions
Résumé
A substantial amount of research effort has been applied to the field of environmentally assisted fatigue (EAF) due to the requirement to account for the EAF behaviour of metals for existing and new build nuclear power plants. We present the results of the European project INCEFA-PLUS during which the sensitivities of strain range, environment, surface roughness, mean strain and hold times as well as their interactions on the fatigue life of austenitic steels has been characterized. The project included a test campaign during which more than 250 fatigue tests have been performed. The tests did not reveal a significant effect of mean strain or hold time on fatigue life. An empirical equation model describing the fatigue life as a function of strain rate, environment and surface roughness is developed. Statistical evidence for the impact of the interactions of surface roughness with the environment as well as strain range have been found. However, their impact is too small for practical relevance. Reducing the environmental impact on fatigue life by modifying temperature or strain rate leads to an increase of the fatigue life in agreement with predictions based on NUREG/CR-6909.
A limited sub-programme on the sensitivity of hold times at elevated temperature at zero force conditions and at elevated temperature did not show the beneficial effect found in another study.
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