20.500.12556/RUL-144499 Vpliv reakcij med žlindro in jeklom z visokim žveplom na napake pri litju v ingot magistrsko delo The influence of slag and high sulphur steel interactions on defects during ingot casting master's thesis Magistrsko delo ''Vpliv reakcij med žlindro in jeklom z visokim žveplom na napake pri litju v ingot'' je bila izvedena z namenom ugotovitve vzroka vključevanja žlindre v livni sistem pred koncem procesa litja, ko je v ponovci še znatna količina taline. Pri tem smo preiskali vzorec žlindre iz korenike livnega sistema s SEM mikroskopom, mikrostrukturne komponente pa določili z EDS analizo. Žlindri za jeklo PK339 smo določili kemijsko sestavo z ICP-OES in XRF metodama, preračunali sestavo vzorcev in jim legirali žveplo (0, 2,5, 5 in 10 mas. %). Vzorce smo stalili v indukcijski peči, ulili v croning merilno celico, kjer smo jim merili temperaturo in električno upornost. Z uporabo termodinamičnega izračuna smo vzorcem žlindre določili vsebnosti faz pri določenih temperaturah in jih primerjali med sabo. Izvedli smo tudi XRD analizo vseh vzorcev sintetične žlindre. S SEM analizo smo ugotovili, da so jeklene kapljice zajete v žlindro obdane s slojem CaS, kar bi lahko bil eden izmed vzrokov vključevanja žlindre v livni sistem. Po izvedbi meritev električne upornosti vseh štirih vzorcev žlindre pa smo lahko tudi potrdili povečanje električne upornosti žlinder z večanjem vsebnosti žvepla, kar pomeni, da se z večanjem vsebnosti žvepla v jeklu povečuje viskoznost žlindre, kar je poleg prej omenjenega lepljenja CaS na površino jekla razlog za vključevanje žlindre v livni sistem. Izvedli pa smo tudi Thermo-Calc izračune, s katerimi smo določili faze, ki se izločajo med strjevanjem in ohlajanjem žlinder. The master’s thesis on The influence of the slag and high sulphur steel interactions on defects during ingot casting was carried out with the aim of determining the cause of the inclusion of slag into the casting system before the end of casting process, where there is still a significant amount of melt in the ladle. In doing so, we examined slag sample from rhizome of the casting system with SEM microscope, microstructural components were determined by EDS analysis. The chemical composition of the slag of PK339 steel was determined by ICP-OES and XRF methods, the composition of the samples was recalculated and they were alloyed with sulphur (0, 2,5, 5, 10 wt. %). We melted the samples in induction furnace, casted into a croning measuring cell, where we measured their temperature and electrical resistance. With thermodynamic calculations we characterized the phases in slag at certain temperatures and compared samples with one another. We also made XRD analysis of synthetic slag samples. With SEM analysis, we found that the steel droplets captured in slag are surrounded by a layer of CaS, which could be one of the causes of slag inclusion into the casting system. After measuring the electrical resistance of all four slag samples, we were also able to confirm the increase in the electrical resistance of the slag with increasing sulphur content, which means that as the sulphur content in the steel increases, the viscosity of the slag also increases, which, in addition to the aforementioned adhesion of CaS to the steel surface, is the reason for inclusion of slag in the casting system. We also performed Thermo-Calc calculations to determine the phases during solidification and cooling of slag. Jeklo PK339 žlindra električna upornost viskoznost termodinamika steel PK339 slag electrical resistance viscosity thermodynamics true false false [M. Praznik] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2023-02-25 09:00:02 2023-02-25 09:00:09 2023-03-23 10:12:11 0000-00-00 00:00:00 2023 0 Ljubljana 0 Ljubljana XIV, 59 str. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 1970-01-01 669 90627 146258179 13468.pdf 13468.pdf 1 6CAD47F73208EA152A9FCF77DEF8F9EA 27fe85b166ffb4a771ce7032770ae32a95a05bd4425aadaca76487112b748db6 6c9222ba-b4e2-11ed-a314-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=166832 Naravoslovnotehniška fakulteta 0 0 0