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

Abstract

Irradiation creep was investigated in different austenitic steels. Pressurized tubes with stresses of 127 e220 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.

Integrated modeling of second phase precipitation in cold-worked 316 stainless steels under irradiation

“…Our CD model does not have He and therefore, we do not expect that current model be able to capture vacancy clustering and cavity evolution correctly. However, this drawback has minor effect at the temperature range of our interest (~ 300 °C) because most experimental observations at this temperature range did not report cavity formation in CW 316 SS [9,26,40].…”

Irradiation Creep in Materials

“…It must also be mentioned that according to Garner [Garner 1994] the derivation of B0 is confounded by the effect of differences in swelling in different alloys and the difficulty in separating the swelling strain and the irradiation creep strain. Anisotropic swelling [Flinn 2007] and the dependence of swelling on the stress (because the flux of point defects to different sinks is also affected by the stress) complicates the partitioning between swelling and irradiation creep strains [Séran 1990, Porter 1991, Foster 2003, Toloczko 2004. Differences between the definitions of strain and stress in different studies also makes it difficult to compare data from different sources.…”

Evidence of dislocation loop preferential nucleation in irradiated aluminum under stress

“…Finally, in high dose irradiations, loops interact with the dislocation network. This interaction alters the loop size distributions and makes the sole effect of stress on loops less easy to observe, especially if irradiations are performed ex-situ [16,34,18]. Therefore, in-situ, low dose irradiations should be preferred to investigate stress effects on loops.…”