Sobula, Sebastian
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inżynieria materiałowa
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Item type:Article, Access status: Open Access , An evaluation of combustion kinetics for the synthesis reaction of the reinforcing phase during casting(AGH University of Science and Technology Press, 2020) Wiktor, Tomasz; Sobula, Sebastian; Burbelko, Andriy A.; Ptasznik, MichałThe computer modeling of the solidification process in castings with local composite reinforcement (LCR) obtained as a result of in situ reactions of self-propagating high temperature synthesis (SHS) is difficult due to limited data on the thermo-physical parameters of exothermic effects and the kinetics of the synthesis reaction. In the present study, Hadfield cast steel casting was manufactured with LCR containing titanium carbide particles obtained in situ by the SHS method. Reaction kinetics of titanium carbide synthesis in the composite casting were determined on the basis of temperature measurements in the area of LCR during the process. For the estimation of the reaction, the Fourier Thermal Analysis method was used. The paper presents the results of temperature measurement and the results of the calculation of SHS reaction kinetics. It was found that the reaction time under the conditions of the analyzed casting is below 3 s.Item type:Book Chapter, Access status: Open Access , Symulacja numeryczna obróbki cieplnej odlewu ze staliwa i jej weryfikacja doświadczalna(Wydawnictwa AGH, 2023) Żołynia, Szymon; Sobula, SebastianThe problem of the heat treatment technology of cast steel with use of modern simulation tools is important to the today’s engineer. The main purpose of thesis was experimental verification of the numerical simulation results of L500-II carbon cast steel heat treatment. In accordance to the assumption, a computer simulation of the heat treatment process was carried out using the Visual-Weld (Sysweld) software. Experimental tests, during which the cooling curves were recorded, were carried out simultaneously. After conducted quenching in water, the hardness distribution on the cross-section of the sample was examined, as well as the microstructure in selected areas, using a light microscope and ImageJ software. It was shown, that the results of the numerical simulation are different from those obtained in the experiment.Item type:Doctoral Dissertation, Access status: Open Access , Wpływ warunków prowadzenia wytopów odzyskowo-tlenowych i argonowania na zawartość gazów w staliwie Hadfielda(Data obrony: 2007) Sobula, Sebastian
Wydział OdlewnictwaThe Hadfield cast steel is very popular material in nowadays because of its good wear resistance at dynamic stresses and price. At high manganesse content this steel has tendency to dissolve a lot of nitrogen in duration of melt. The higher nitrogen solubility in liquid state and very low solubility i solid state causes the formation of bubles during solidification. Nitrogen is introduced to the melt with a return scrap and some ferroalloys ($Fe-Si, Fe-Mn$). The nitrogen content decreases in the electric are furnace by oxygen blowing into the molten steel. Double killing in the ladle ($Al+Fe-Ti$) and the argon stirring with synthetic slag was used for improve cleannes of the steel. That treatment permmited to produce cast steel with $317,2 \pm 40ppm$ N and castings with $283,9 \pm 36,7$ ppm of nitrogen. This nitrogen concentration protects against gas bubles in castings (bubles are created over 400 ppm of nitrogen). It has been shown that nitrides and oxides formed during double-killing are eliminate during argon stirring.