20.500.12556/RUL-95585 Testiranje orodnega jekla s PVD prevlekami na odpornost proti temperaturnemu utrujanju Testing of tool steel with PVD coatings on thermal fatigue resistance Temperaturno utrujanje ima močan vpliv na življenjsko dobo orodij za delo v vročem in je eden izmed glavnih razlogov za njihovo ponovno popravilo oz. tudi konec življenjske dobe. Visoke temperature med obratovanjem povzročajo popustne efekte, ciklično ponavljanje ogrevanja in ohlajanja pa vodi do nastanka mreže razpok na površini. V diplomskem delu smo preizkušali nov test za temperaturno utrujanje, ki nam omogoča testiranje večih površin hkrati. V našem primeru smo preiskovali odpornost na temperaturno utrujanje treh površin. Uporabili smo nitriranje in DUPLEX obdelavo z dvema različnima prevlekama (TiAlSiN in (Ti,Al)N). Testiranje je potekalo na napravi Gleeble 1500 D. Opravili smo 2000 ciklov gretja na temperaturo 650 °C in hlajenja z zrakom. Vzorec se je porušil v po prvih nekaj 10 ciklih hlajenja z vodo. Na preseku vzorca smo opazovali razpoke. Na površinah s PVD prevlekami smo opazili večjo koncentracijo razpok v prevleki, ki so začele rasti v podlago. Na nitrirani površini pa se je razvilo manj toda daljših razpok. Velik del prevleke (Ti,Al)N se je odluščil po meji, ki je nastala zaradi prekinitve procesa nanašanja. Thermal fatigue is an imporant issue for hot-working tool steels and is usually the main reason for tool failures. High working temperatures reduce its mechanical properties. In such softened form it cannot withstand the strain caused by large temperature gradients and working loads, which leads to deformations, intense wear and cracking. In this work we used a new test rig for testing of thermal fatigue resistance. The main focus was assessment of thermal fatigue resistance for three different prepared surfaces. The test enabled testing at equal testing conditions and thus providing comparable results. We tested nitrided and two DUPLEX treated surfaces, i.e. with two different PVD coatings (TiAlSiN and (Ti,Al)N). A total of 2000 cycles of heating to a temperature of 650 °C and air cooling were performed on a system Gleeble 1500 D apparatus. A failure has occurred at the beginning of water-cooled cycles after a few 10 cycles. Cross-section revealed that DUPLEX treated surfaces had a higher concentration of short thermal cracks, while nitrided surfaces had fewer, longer cracks. Also, large portions of (Ti,Al)N had peeled off because of weak adhesion caused by interruption during coating application. temperaturno utrujanje PVD prevleke nitriranje orodna jekla razpoke thermal fatigue PVD coatings nitriding tool steels cracks true false false Slovenski jezik Angleški jezik Diplomsko delo/naloga 2017-09-21 07:15:50 2017-09-21 07:15:52 2022-08-10 06:34:22 0000-00-00 00:00:00 2017 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 1970-01-01 57404 483.pdf 483.pdf 1 E90541F785443D5B39B707D99C39BE76 19ccc0581f2de96b6a5f6c8523e714163027b38dff48411a495ec5c54fd922a3 cb208f36-a1b3-11eb-a523-00155dcfd717 20.500.12556/rul/ee697c22-80c6-4c7c-aed7-2d0f4063d78b https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=104203 Naravoslovnotehniška fakulteta 0 0 0