Problematic and metallurgy of welding in the maintenance of the EDF's PWRs. Some applications from the return on experience - Weldability of aged cast austenitic-ferritic stainless steels

Peculiar specifications are applied to welding operations during the maintenance of pressurized equipment of EDF's PWR nuclear plants. These specifications can differ from fabrication technical requirements for different reasons: evolution of regulation, taking of material ageing into account and evolution of material weldability characteristics, intervention geometrical conditions, return on experience, impossibility to perform post-welding thermal treatments. Various examples are presented to illustrate these peculiarities: repair of coatings in austenitic stainless steel (either by working or by local welding), multiple assignments of heat-affected-zones, weldability of in-service aged cast austeno-ferritic stainless steels (tests on models)