Influence of the austenitic stainless steel microstructure on the void swelling under ion irradiation

Abstract

Abstract. To understand the role of different metallurgical parameters on the void formation mechanisms, various austenitic stainless steels were elaborated and irradiated with heavy ions. Two alloys, in several metallurgical conditions (15Cr/15Ni-Ti and 15Cr/25Ni-Ti), were irradiated in the JANNUS-Saclay facility at 600°C with 2 MeV Fe 2+ ions up to 150 dpa. Resulting microstructures were observed by Transmission Electron Microscopy (TEM). Different effects on void swelling are highlighted. Only the pre-aged samples, which were consequently solute and especially titanium depleted, show cavities. The nickel-enriched matrix shows more voids with a smaller size. Finally, the presence of nano-precipitates combined with a dense dislocation network decreases strongly the number of cavities.

Materials for Sustainable Nuclear Energy: A European Strategic Research and Innovation Agenda for All Reactor Generations

“…Pathways to improve austenitic steels from the viewpoint of swelling and corrosion resistance (especially against heavy liquid metals) are being explored. Higher swelling resistance is pursued via microstructure stabilisation with selected alloying elements (for instance AIM1 and its bettered version AIM2) [269][270][271]. Enhanced corrosion resistance is sought for with corrosion barriers, either by implanting aluminum to change the surface composition and induce the formation of a protective alumina layer [272,273], or by directly depositing alumina (or other ceramics) layers to coat the metallic substrate [274][275][276].…”

Development of radiation damage during in-situ Kr++ irradiation of Fe Ni Cr model austenitic steels

“…The experimental materials 15Cr/15Ni-Ti and 15Cr/25Ni-Ti used in this study are model alloys developed from the industrial alloy AIM1. The experimental materials, made by Rouxel [1], are shaped by rolling in a way to obtain a microstructure close to the industrial alloy AIM1 (see figure 1). The composition of the ingots was measured after casting by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES).…”

“…Two model alloys, 15Cr/15Ni and 15Cr/25Ni, both stabilized with titanium, have been irradiated insitu at the Intermediate Voltage Electron Miscroscope (IVEM)-Tandem Facility (Argonne National Laboratory) with 1 MeV Kr ions. Those two model alloys had already shown different swelling beahaviour after Fe 2+ [2 MeV] ion-irradiation to 180 dpa KP [1]. The ob-jective of this work is to better understand the effect of nickel on the microstructural evolution of austenitic steels under irradiation at low doses.…”

“…Currently, the most optimized steel is a 15Cr/15Ni alloy (named AIM1) stabilized with titanium and used in the cold-worked condition. In order to understand the microstructural mechanisms behind the swelling phenomenon, several model alloys derived from AIM1, with different metallurgical states and chemical compositions, have been studied after ionirradiation by Rouxel et al [1]. Swelling under irradiation is dependent on various factors, such as the dislocation density [6,7,8], precipitates [7,9,10] and the chemical elements in solid solution [11,12,13].…”

“…The experiment was designed in the framework of cladding development for the GEN IV Sodium Fast Reactors (SFR). It is an extension of previous high dose irradiations on those model alloys at JANNuS-Saclay facility in France, aimed at investigating swelling mechanisms and microstructure evolution of these alloys under irradiation [1]. These studies showed a strong influence of Ni in decreasing swelling.…”