Evolution of microstructure after irradiation creep in several austenitic steels irradiated up to 120 dpa at 320°C

Alexandra Renault-Laborne (1, 2) , J. Garnier (1, 2) , J. Malaplate (2, 1) , P. Gavoille (1, 3) , F. Sefta (4) , B. Tanguy (1, 3)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 SRMA - Service des Recherches Métallurgiques Appliquées
3 SEMI - Service d'Etudes des Matériaux Irradiés
4 EDF - EDF

Irradiation creep was investigated in different austenitic steels. Pressurized tubes with stresses of 127–220 MPa were irradiated in BOR-60 at 320°C to 120 dpa. Creep behavior was dependent on both chemical composition and metallurgical state of steels. Different steels irradiated with and without stress were examined by TEM. Without stress, the irradiation produced high densities of dislocation lines and Frank loops and, depending on the type of steels, precipitates. Stress induced an increase of the precipitate mean size and density and, for some grades, an increase of the mean loop size and a decrease of their density. An anisotropy of Frank loop density or size induced by stress was not observed systematically. Dislocation line microstructure seems not to be different between the stressed and unstressed specimens. No cavities were detectable in these specimens. By comparing with the data from this work, the main irradiation creep models are discussed.

Keywords: microstructure; cavities; anisotropy; irradiation creep; austenitic steels; dislocation lines

Domains: Nuclear Theory [nucl-th]; Nuclear Experiment [nucl-ex]

Alexandra Renault-Laborne, J. Garnier, J. Malaplate, P. Gavoille, F. Sefta, et al.. Evolution of microstructure after irradiation creep in several austenitic steels irradiated up to 120 dpa at 320°C. Journal of Nuclear Materials, 2016, 475, pp.209-226. ⟨10.1016/j.jnucmat.2016.04.020⟩. ⟨cea-02381473⟩