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 (500 × 500 × 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-iron. Key-words: ductile cast-iron, massive casting, cooling, temperature field, numerical model Uporaba originalnega programa ANSYS omogo~a simulacijo tvorbe temperaturnega polja v masivnem lito`eleznem ulitku pri razli~nih metodah hlajenja z jeklenimi hladilnimi telesi. Z numeri~nim modelom se lahko optimira ve~metod hlajenja, dodatno pa je mogo~izra~un pomembnih rezultatov za modeliranje strukturne in kemijske heterogenosti, kar tudi prispeva k vplivu na lito mikrostrukturo. Dobljeni rezultati obeh modelov omogo~ajo pomembne ugotovitve o odnosih med strukturno in kemijsko heterogenostjo ter lokalnim~asom strjevanja v poljubni to~ki ulitka in napoved lokalne gostote krogli~astega grafita v odvisnosti od lokalnega~asa strjevanja. Izra~unano temperaturno polje dvotonskega ulitka duktilne`elezove litine z izmerami (500 × 500 × 1000) mm je bilo v skladu z eksperimentalnimi rezultati pri razli~nih metodah hlajenja. Na podlagi teh ugotovitev je bilo izdelano orodje za optimizacijo mikrostrukture z enakomerno porazdelitvijo krogli~astega grafita, s~imer se zmanj{a pojav degeneriranih oblik grafita in se ustvarijo pogoji za dosego dobrih mehanskih lastnosti ulitkov duktilne`elezove litine. Klju~ne besede: temperaturno polje, strjevanje, ohlajanje, numeri~na optimizacija, strukturna in kemijska heterogenost

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The so‐called secondary cooling zone is an important part of the continuous casting machine. In this zone, a breakout may occur because of an increase of the local and temperature heterogeneity of steel, resulting from an increase of the stress caused by bending of the slab and by high local concentration of nonmetallic slag inclusions. Changes of the chemical composition of steel during continuous casting are particularly dangerous. In the event that two melts are cast one after another, that is, if the melt of steel with chemical composition A ends and is immediately followed by the steel B, it may automatically stop the continuous casting machine, and an atypical breakout may take place. It has happened during continuous casting of the slab, 250 × 1530 mm in the area of straightening, 20 min after flying change of tundish. In the present paper, by employing the dimensional analysis, eight dimensionless numbers are derived. If the values of these dimensionless numbers for two followed steels significantly differ, the atypical breakout may take place.

The quality of the working rollers from ductile-cast-iron used for rolling rails is determined by the chemical and structural composition of the material of the rollers and the production technology. The requirements of the quality cannot be ensured without perfect knowledge of the course of solidification, cooling and heat treatment of the cast rollers as well as the kinetics of the temperature field of the casting and mould. An original application of ANSYS simulated the forming of the temperature field of the entire system comprising the casting, the mold and ambient. In the experimental investigation of temperature field, an original methodology for the measurement of the distribution of temperatures and heat flows in the roller-mould system had been developed and verified in the operation. The kinetics of the solidification has a measurable and non-negligible influence on the chemical and structural heterogeneity of the investigated type of ductile-cast-iron. Tying on to the results of the model of the temperature field of the cast rollers, an original methodology was developed for the measurement of chemical microheterogeneity. The chemical and structural heterogeneity of the cast roller is therefore a significant function of the method of melting, modification and inoculation and the successive procedures of risering, casting and crystallization after cooling.