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The Segregation in Ferrous Alloys when Casting Heavy Castings
Pernica, Vítězslav ; Čech, Jan (referee) ; Vodárek, Vlastimil (referee) ; Havlíček,, František (referee) ; Šenberger, Jaroslav (advisor)
This thesis is dedicated to the field of manufacture of heavy steel castings with resulting properties which are influenced by long solidification time. During the long solidification time a segregation process of additives in the steel occurs which results in numerous metallurgical defects. The work was intended to observe the macrosegregation effects in the wall of a heavy experimental steel casting respectively a part of a real superheavy casting intended for cement furnaces (weight 210 t). The steel casting for the research was manufactured in the joint-stock company of VHM where such heavy castings are commonly produced for the market. The supplied piece of the steel casting was cut into the smaller pieces for the better examination. The examination resulted in information about the casting macrostructure and chemical heterogeneity of chosen elements in the casting wall. The heterogeneity of the chosen elements (C, Mn, Si, Cr, S, P) is clearly shown in the worked out visual concentration maps. Based on the experimental data the measured results of segregations were confronted with the results of segregation modelling with the use of the commercial simulation software ProCAST. It resulted in the conclusion that the prediction of segregations is not in accordance with the reality. Furthermore, the results from the experimental casting are shortly compared with previously manufactured castings of the same type and the results summarizing the found range of macrosegregations of the tested sample are interpreted in the work conclusion.
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Design of a technology and checking the production of small steel ingots
Jakubčíková, Lucie ; Čamek, Libor (referee) ; Záděra, Antonín (advisor)
The thesis deals with the design of ingots from duplex (austenitic-ferritic) stainless steels in terms of minimal occurrence of axial porosity. The optimal shape and dimension of the ingot and the casting conditions are determined based on numerical simulations. The resulting internal quality of the realized ingot is evaluated. The presence of shrinkage porosity is determined by penetrant testing. The degree of chemical heterogeneity, the extent of macrosegregation, of selected elements in given ingot locations is measured by an optical emission spectrometer. Segregation values are compared with simulation results. The micro-purity of the ingot is assessed on the basis of metallographic samples.
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Macrosegregation and microsegregation in austenitic CrNi steels
Ostratický, Marek ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
This diploma thesis deals with segregation cycles in austenitic CrNi steels. In first section deals with theory of macrosegregation and microsegregation cycles. The second part is focused on this cycles in experimental casting. Macrosegregation was measured by spectrometric analyser and by MAGMA simulation program. Microsegregation was measured by electron microscope. The aim of this diploma thesis is verify the influence of setting conditions on heterogenity chemical composition in austenitic CrNi steel. For experimental casting with a wall thickness of about 500 mm will be verified effect of the setting time, residence time between solid and liquid phases and others parameters for macrosegregation and microsegregation in selected elements.
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Design of a technology and checking the production of small steel ingots
Jakubčíková, Lucie ; Čamek, Libor (referee) ; Záděra, Antonín (advisor)
The thesis deals with the design of ingots from duplex (austenitic-ferritic) stainless steels in terms of minimal occurrence of axial porosity. The optimal shape and dimension of the ingot and the casting conditions are determined based on numerical simulations. The resulting internal quality of the realized ingot is evaluated. The presence of shrinkage porosity is determined by penetrant testing. The degree of chemical heterogeneity, the extent of macrosegregation, of selected elements in given ingot locations is measured by an optical emission spectrometer. Segregation values are compared with simulation results. The micro-purity of the ingot is assessed on the basis of metallographic samples.
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Macrosegregation and microsegregation in austenitic CrNi steels
Ostratický, Marek ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
This diploma thesis deals with segregation cycles in austenitic CrNi steels. In first section deals with theory of macrosegregation and microsegregation cycles. The second part is focused on this cycles in experimental casting. Macrosegregation was measured by spectrometric analyser and by MAGMA simulation program. Microsegregation was measured by electron microscope. The aim of this diploma thesis is verify the influence of setting conditions on heterogenity chemical composition in austenitic CrNi steel. For experimental casting with a wall thickness of about 500 mm will be verified effect of the setting time, residence time between solid and liquid phases and others parameters for macrosegregation and microsegregation in selected elements.
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The Segregation in Ferrous Alloys when Casting Heavy Castings
Pernica, Vítězslav ; Čech, Jan (referee) ; Vodárek, Vlastimil (referee) ; Havlíček,, František (referee) ; Šenberger, Jaroslav (advisor)
This thesis is dedicated to the field of manufacture of heavy steel castings with resulting properties which are influenced by long solidification time. During the long solidification time a segregation process of additives in the steel occurs which results in numerous metallurgical defects. The work was intended to observe the macrosegregation effects in the wall of a heavy experimental steel casting respectively a part of a real superheavy casting intended for cement furnaces (weight 210 t). The steel casting for the research was manufactured in the joint-stock company of VHM where such heavy castings are commonly produced for the market. The supplied piece of the steel casting was cut into the smaller pieces for the better examination. The examination resulted in information about the casting macrostructure and chemical heterogeneity of chosen elements in the casting wall. The heterogeneity of the chosen elements (C, Mn, Si, Cr, S, P) is clearly shown in the worked out visual concentration maps. Based on the experimental data the measured results of segregations were confronted with the results of segregation modelling with the use of the commercial simulation software ProCAST. It resulted in the conclusion that the prediction of segregations is not in accordance with the reality. Furthermore, the results from the experimental casting are shortly compared with previously manufactured castings of the same type and the results summarizing the found range of macrosegregations of the tested sample are interpreted in the work conclusion.
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