Ferritic and martensitic ODS steel resistance upset welding of fuel claddings: Weldability assessment and metallurgical effects

Abstract Development and characterization of clad-to-plug resistance upset welds is presented for two oxide dispersion strengthened steels candidates for sodium-cooled fast reactors fuel cladding: 9Cr ferrito-martensitic steel and 14Cr ferritic steel. A comparative approach is adopted regarding these two materials implying weldability studies and weld mechanical strength tests. A special attention is paid on welding metallurgical effects on the specific microstructure of these materials. Among others, some major grain property modifications by dynamic recrystallization and a slight modification of precipitate sizes and volume fraction are found and discussed.