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Methods of primary influencing steel and steel ingot structures
Stejskal, Marek ; Záděra, Antonín (referee) ; Blažík, Petr (advisor)
This bachelor thesis is focused on the ways of influencing metal structure during it’s solidification in the mold that leads to changes in mechanical properties. In the first part there is explained the principle of metal crystalization, it’s types and mechanisms, there is also described the issue of metal solidification in the mold. In the second part of the thesis there is a general view of methods being used for primal influencing of steel structure. The principles and ways of use for these methods in foundry industry are explained.
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Controled crystallisation of aluminium alloys castings poured in shell moulds
Mašková, Lenka ; Střítecký, František (referee) ; Roučka, Jaromír (advisor)
The aim of this thesis is to verify a possibility of controlling the crystallisation of aluminium alloys poured in shell moulds in order to achieve directional solidification. For this purpose, new cooling plant has been designed and fabricated. Several sample castings were produced under different initial conditions. Based on the evaluation of measured temperatures, a numerical simulation of heat transfer was created using the ProCAST software. Finally, the sample castings were sectioned into specimens that were, subsequently, metallographically polished and the evaluation of their structure with respect to the amount and types of defects was performed.
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Methods of primary influencing steel and steel ingot structures
Stejskal, Marek ; Záděra, Antonín (referee) ; Blažík, Petr (advisor)
This bachelor thesis is focused on the ways of influencing metal structure during it’s solidification in the mold that leads to changes in mechanical properties. In the first part there is explained the principle of metal crystalization, it’s types and mechanisms, there is also described the issue of metal solidification in the mold. In the second part of the thesis there is a general view of methods being used for primal influencing of steel structure. The principles and ways of use for these methods in foundry industry are explained.
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Controled crystallisation of aluminium alloys castings poured in shell moulds
Mašková, Lenka ; Střítecký, František (referee) ; Roučka, Jaromír (advisor)
The aim of this thesis is to verify a possibility of controlling the crystallisation of aluminium alloys poured in shell moulds in order to achieve directional solidification. For this purpose, new cooling plant has been designed and fabricated. Several sample castings were produced under different initial conditions. Based on the evaluation of measured temperatures, a numerical simulation of heat transfer was created using the ProCAST software. Finally, the sample castings were sectioned into specimens that were, subsequently, metallographically polished and the evaluation of their structure with respect to the amount and types of defects was performed.
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METALLURGY AND PROPERTIES OF ADVANCED NiAl-Mo EUTECTICS
Barták, Tomáš ; Kuchařová, Květa ; Záležák, Tomáš ; Dlouhý, Antonín
A NiAl-Mo eutectic alloy was melt from 99,99% purity components and cast by the drop casting technique. The drop-cast ternary alloy (nominal composition of Ni-45Al-9Mo at. %), was re-melted and directionally solidified using a high temperature optical floating zone furnace. A resulting in-situ composite consists of Ni-45,2Al matrix and Mo-10Al-4Ni fibers, all in at. %. The volume fraction of 14% Mo-fibers stems from the eutectic composition. Backscatter diffraction shows that the NiAl-matrix and the Mo-fibers are both < 001 >-oriented with respect to the axis of the cylindrical rods. Preliminary creep experiments confirmed an immense improvement of high temperature strength due to the fine distribution of Mo-fibres. The amount of strengthening in terms of minimum creep rate can be as high as 7 orders of magnitude. Post-mortem transmission electron microscopy experiments provided evidence that creep in the temperature range of 800 - 900 degrees C results in an extensive formation of subgrain boundaries. The strengthening effect is very likely associated with the reactions between subgrain boundaries and fine Mo-fibres.
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