22 KB1494 KB19 KB200020242011Kafexhiu, FevziVojvodič-Tuma, Jelenaštevilka:4letnik:45str. 357-361ISSN:1580-2949COBISSID:866730URN:URN:NBN:SI:doc-NAEPYB7KenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijejekloneporušne preiskaveparovodiLifetime evaluation of a steam pipeline using NDE methods| Ocena preostale trajnostne dobe parovoda z uporabo neporušitvenih preiskav (NDE)|Before its shutdown, the steam pipeline made from X20CrMoV121 steel in the Power Plant Toplarna - Ljubljana operated at 530 °C and 95 bar for 150 000 h. A non-destructive evaluation (NDE) of the microstructure using the replica method and hardness measurements on pipeline bends and welded joints with the aim to evaluate for possible damage due to creep deformation was applied. The hardness of the different zones of the welded joints, base material, heat-affected zone and the weld material itself was appropriate and corresponded to the tensile strength in the range required by the standards. A martensitic appearance in all the observed locations was noticeable. Micro-voids that arise due to creep deformation along the former austenite grain boundaries and along the martensite lamellas on the inspected sites were not observed. According to the VGB'classification, the steel corresponds to the 2b classOb zaustavitvi je bil parovod v Termoelektrarni-Toplarni Ljubljana v obratovanju že 150 000 h pri tlaku 95 bar in temperaturi pare 530 °C. Parovod je izdelan iz jekla X20CrMoV121. Na cevnih kolenih in zvarjenih spojih parovoda smo naredili neporušitvene preiskave (NDE) mikrostrukture po metodi replik in meritve trdote za oceno stanja parovoda ter ocenili morebitne poškodbe zaradi deformacije z lezenjem. Trdota različnih delov zvara, osnovnega materiala, toplotno vplivanega področja in vara je ustrezna in ustreza natezni trdnosti, ki je v mejah, določenih po standardu. Martenzitni habitus je na vseh mestih izrazit. Mikropore, ki nastanejo zaradi deformacije z lezenjem po mejah prvotnih avstenitnih zrn in po martenzitnih lamelah, na pregledanih mestih nismo opazili. Po klasifikaciji VGB1 ustreza jeklo razredu 2bTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije