b'Case Study: Testing of Inconel 718 Fasteners for Nuclear ApplicationsIn the nuclear energy sector, every fastening element must undergo extremely stringent quality checks. This case study describes a test Two studs with different campaign conducted by an accreditedeccentricitieslaboratory, Sigma Tre Lab (UNI CEI ENFor each production batch, the following ISO/IEC 17025:2018), commissioned bytests were conducted in order:EFS Srl, on fasteners made from Inconel 718 for use in nuclear plants. IDimensional control and traceability Material selection and operating context Each piece underwent precise The Inconel718 superalloy was chosenmetrological inspection using CMM and for its ability to perform under criticallaser gauges, ensuring correct tolerances conditionsoffering high resistance tofor thread profiles, diameters, fatigue, creep, temperatures up to 700C,and lengths.and corrosion. These properties makeIINon-destructive testing with liquid it ideal for mechanical components inpenetrantsnuclear power plants, where every partThis method detects micro-cracks and is exposed to significant thermal andsurface discontinuities, even down to a mechanical stress. few microns. It is cost-effective compared The testing campaign had two to X-ray or ultrasound methods and easy main objectives: to apply. However, it does not detectTo verify compliance with applicablesubsurface or internal flaws.regulations for components intendedThe testing process included:for the nuclear sectorSurface cleaning before application To guarantee mechanical and Application of red penetrant across chemical reliability for eachthe surfaceproduction batch, enhancing operational safetyRemoval of excess penetrant to Here are the various tests typicallyavoid false positivesapplied to these fasteners:Application of developer to bring outCompositional analysis, to confirmpenetrant indications from surface the correct presence of Ni, Cr, Fe, Nb discontinuities Microstructural evaluation through Final visual inspection to check for metallographic analysis, to excludemicro-cracks or critical Testing fasteners for nuclear applicationsdefects such as cracks, segregationssurface defectsand inclusions IIIHardness and impact tests adherence to standards, including ISOImpurity inspection, ensuring theThese tests assess performance under9001 certification.absence of inclusions that couldshock and vibrations. Contact here: compromise mechanical strength +39 031 2498999 Tensile testing, which evaluates breakinginfo@efsfasteners.com Case study: Non-destructive testing andstrength and yield load, was not feasiblewww.efsfasteners.commechanical checks due to the small dimensions of the This case focuses on two special partsfasteners. However, all obtained values in Inconel 718 intended for SMRs (Smallwere compared against regulatory limits, Modular Reactors), the next-generationensuring full compliance of eachnuclear reactors that Italy is also planningfastener batch.to adopt. EFS Srl maintains its focus on stringent The fasteners were custom-made basedtesting protocols and safety assurance, on engineering drawings and included: upholding a culture of continuous improvement and quality throughOne fully threaded hex head bolt31'