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 Fe2+ ions up to 150 dpa. | Influence of the austenitic stainless steel microstructure on the void swelling under ion irradiation EPJ Nuclear Sci. Technol. 2 30 2016 Nuclear Sciences B. Rouxel et al. published by EDP Sciences 2016 amp Technologies DOI epjn 2016023 Available online at http REGULAR ARTICLE Influence of the austenitic stainless steel microstructure on the void swelling under ion irradiation Baptiste Rouxel1 Caroline Bisor2 Yann De Carlan1 Arnaud Courcelle2 and Alexandre Legris3 1 DEN-Service de Recherches Métallurgiques Appliquées CEA Université Paris-Saclay 91191 Gif-sur-Yvette France 2 DEN-Service d Études des Matériaux Irradiés CEA Université Paris-Saclay 91191 Gif-sur-Yvette France 3 Unité Matériaux et Transformations UMET UMR CNRS 8207 Université Lille 1 59655 Villeneuve d Ascq France Received 8 July 2015 Received in final form 16 November 2015 Accepted 20 May 2016 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 Fe2 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. 1 Introduction Swelling under irradiation depends on various micro- structural parameters such as the dislocation density 4 7 In the framework of the GEN IV Sodium Fast Reactors precipitates 7 10 and the chemical elements in solid SFR program CEA is developing new austenitic steels for solution 8 11 15 . Besides the role