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V okviru magistrskega dela smo raziskovali vpliv usmerjevalcev toka jeklene taline v vmesni ponovci na vsebnost nekovinskih vključkov v kontinuirano ulitem slabu. V teoretičnem pregledu smo podrobno opisali postopek kontinuiranega ulivanja jekla, predvsem pomen vmesne ponovce in kokile, napake na polizdelkih ter razvoj nekovinskih vključkov. Prvi korak eksperimentalnega dela je bilo numerično modeliranje toka jeklene taline v vmesni ponovci. Simulirali smo tok taline v dveh vmesnih ponovcah, z vstavljenim umirjevalcem toka in z vstavljenim umirjevalcem toka in pregrado. Na napravi za kontinuirano ulivanje jekel smo pri enakih pogojih kot smo jih uporabili pri modeliranju ulili tri šarže s prvim tipom vmesne ponovce in tri šarže z drugim tipom vmesne ponovce. Rezultate numeričnih simulacij smo prikazali s slikami, ki predstavljajo tok taline z različno obarvanimi območji hitrosti ter s tokovnicami. Za izbrane prereze v prečni ter vzdolžni smeri smo izrisali diagrame vertikalne komponente hitrosti po višini in dolžini vmesne ponovce. Iz vseh šestih ulitih šarž smo vzeli vzorce končnih plošč ter naredili analizo vsebnosti nekovinskih vključkov po standardu DIN 50 602. Tako rezultati numeričnih simulacij kot analize nekovinskih vključkov kažejo, da je uporaba pregrade v vmesni ponovci smiselna, ker zmanjša število sulfidnih trakov v jeklu za skoraj polovico. In the master thesis, the influence of steel melt flow modifiers in the tundish on the content of non-metallic inclusions in the continuous casting slab was investigated. In the theoretical consideration, the process of continuous steel casting was described in detail, in particular the importance of tundish design, defects in the semi-finished product and the formation of non-metallic inclusions. The first step of the experimental work was the numerical modeling of the steel melt flow in the tundish. We simulated the flow of the melt in two tundishes, with the pouring box inserted and with the pouring box and weir inserted. We cast three batches with the first tundish type and three batches with the second tundish type on the continuous steel caster under the same conditions as in the modeling. The results of the numerical simulations were presented with pictures showing the flow of the melt with different colored velocity zones and with flow lines. For the selected cross sections in transverse and longitudinal directions, we drew plots of the vertical component of the velocity by height and length of the tundish We took samples of end plates from all six casting batches and analyzed the content of nonmetallic inclusions according to the standard DIN 50 602. Both the results of the numerical simulations and the analysis of non-metallic inclusions show that the use of a weir in the tundish is useful, as it reduces the number of sulfide bands in the steel by almost half. |
