21 KB678 KB20 KB200020242009Dobrovská, JanaGontarev, VasilijKavička, FrantišekSekanina, BuhumilStetina, JozefStransky, Karelštevilka:2letnik:43str. 73-78ISSN:1580-2949COBISSID:725162URN:URN:NBN:SI:doc-4EKT9L2WenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijehlajenjelitinenumerične metodeohlajanjeoptimiranjestrjevanjeNumerical optimization of the method of cooling of a massive casting of ductile cast-iron| Numerična optimizacija postopka hlajenja pri masivnem ulivanju duktilne železove litine|An original application of ANSYS simulating the forming of the temperature field of a massive casting from ductile cast-iron during the application various methods of its cooling using steel chills. The numerical model managed to optimize more than one method of cooling but, in addition to that, provided serious results for the successive model of structural and chemical heterogeneity, and so it also contributes to influencing the as solidified microstructure. The file containing the acquired results from both models, as well as from their organic unification, brings new and, simultaneously, remarkable findings of causal relationships between the structural and chemical heterogeneity and the local solidification time in any point of the casting. Therefore the determined relations enable the prediction of the local density of the spheroids of graphite in dependence on the local solidification time. The calculated temperature field of a two-ton (500x500x 1000) mm casting of ductile cast-iron with various methods of cooling has successfully been compared with temperatures obtained experimentally. This has created a tool for the optimization of the microstructure with an even distribution of the spheroids of graphite in such a way so as to minimize the occurrence of degenerated shapes of graphite, which happens to be one of the conditions for achieving good mechanical properties of castings of ductile cast-ironUporaba originalnega programa ANSYS omogoča simulacijo tvorbe temperaturnega polja v masivnem litoželeznem ulitku pri različnih metodah hlajenja z jeklenimi hladilnimi telesi. Z numeričnim modelom se lahko optimira več metod hlajenja, dodatno pa je mogoč izračun pomembnih rezultatov za modeliranje strukturne in kemijske heterogenosti, kar tudi prispeva k vplivu na lito mikrostrukturo. Dobljeni rezultati obeh modelov omogočajo pomembne ugotovitve o odnosih med strukturno in kemijsko heterogenostjo ter lokalnim časom strjevanja v poljubni točki ulitka in napoved lokalne gostote krogličastega grafita v odvisnosti od lokalnega časa strjevanja. Izračunano temperaturno polje dvotonskega ulitka duktilne železove litine z izmerami (500x500x1000) mm je bilo v skladu z eksperimentalnimi rezultati pri različnih metodah hlajenja. Na podlagi teh ugotovitev je bilo izdelano orodje za optimizacijo mikrostrukture z enakomerno porazdelitvijo krogličastega grafita, s čimer se zmanjša pojav degeneriranih oblik grafita in se ustvarijo pogoji za dosego dobrih mehanskih lastnosti ulitkov duktilne železove litineTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije