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Fading of the inoculation in graphitic cast irons
Doubrava, Jiří ; Jelínek, Radim (referee) ; Záděra, Antonín (advisor)
The bachelor thesis is focused on the structure and properties of cast iron with flake graphite. In the theoretical part the problems of crystallization of cast irons, grafting, methods of grafting of graphitic cast irons are discussed. In the practical part, the time course of grafting structure in cast iron with flake graphite was verified. Two inoculations were verified and the fading effect of the inoculations was also determined. For this purpose, samples were taken continuously at regular time intervals. To check the disappearance of the grafting effect, the method of turbidity test, thermal analysis, chemical analysis and then metallographic smear were chosen to observe the structure and evaluate the image analysis.
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Properties and micropurity of steels produced using vacuum metallurgy
Krontorád, Jakub ; Pernica, Vítězslav (referee) ; Záděra, Antonín (advisor)
This master thesis contains analysis of metallurgical quality of medium alloyed steel from the perspective of microcleanliness and content of dissolved gases. Apart from thorough research there are result of three melts from vacuum induction furnace (VCAP-Consarc), from which, conclusions are made. Each of the scrap material types (steel scrap, VD scrap and ESR scrap) had different metallurgical quality and initial microcleanliness, which influenced the final quality of the ingot. Lastly both degassing process and the thermodynamical probability of the reaction of silicon-oxide based sampling pipe with melt has been examined and calculated.
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Casting production of an optimized inlet shape of pneumobile engine pneumatic cylinder
Bouchner, Jan ; Záděra, Antonín (referee) ; Krutiš, Vladimír (advisor)
Presented bachelor's thesis deals with production of a pneumatic component using hybrid investment casting technology. This method combines investment casting with additive technologies. The manufactured component, called cap-end, supplies compressed air to the pneumatic drive of a racing car. Complex design of this component was created using computer fluid dynamics optimization. This design was delivered by the Pneumobile racing team Brno. Presented thesis further contains a technological consideration taking into account solidification direction, on the basis of which the delivered geometry was modified. Manufacturability of the component is verified by a numerical simulation in the ProCAST environment. This thesis also describes printing process of a combustible model using fused deposition modelling technology. The combustible model is used in the production of a ceramic shell. Using said ceramic shell AlSi10Mg alloy casting was made. The component had to meet the requirements for leak tightness after machining and subsequent assembly. The leak tightness is assessed here as a pressure drop in a closed circuit measured over time. Furthermore, the effect of the cap-end on properties of the racing car in relation to the original geometry was investigated. The comparison is made on the basis of the race car's unloaded wheel speed measurements. The outcome of the thesis is a functional cap-end component that validates the results of a scientific article published by members of the Pneumobile racing team Brno.
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Surface quenching of ductile cast iron
Neduchal, Bronislav ; Roučka, Jaromír (referee) ; Záděra, Antonín (advisor)
This diploma thesis is focused on the surface hardening of cast irons with spheroidal graphite. The work describes a theoretical analysis of the structure and properties of cast irons and individual methods suitable for surface hardening. The practical part describes the production of cast iron castings with spheroidal graphite, on which the surface hardening is performed, tensile test, hardening of produced castings by induction and laser surface hardening, preparation of samples for measuring microhardness and metallographic analysis of metal structures.
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Effect of lead and antimony on the degradation of graphite shape in cast iron
Hlobil, Albert ; Kaňa, Václav (referee) ; Záděra, Antonín (advisor)
The bachelor thesis focuses on the effect of lead and antimony on the degradation of graphite in cast iron in relation to the lowered mechanical characteristics. This leads to the subsequent summary of the formation of degraded structures and unfavourable elements – the elements that are the cause of the formation. In the practical segment of the thesis, I will prove the effects of lead (or the combination of lead and antimony) on the degradation of graphite in cast iron with the focus lying at flake graphite. Furthermore, the thesis examines the mechanical characteristics and the attenuation of cast iron in relation to the formation of degraded graphite structures.
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Manufacture and defects of heavy castings
Vymazal, Aleš ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
Objective of diploma thesis is to proceed analysis of actual technology in operational terms for concrete casting of bearing . Constructed by foundry of steel ŽĎAS a.s., Žďár nad Sázavou. After designing changes in technological process accomplish detail evaluation of mechanical properties and chemical homogenity of metal at selected parts of sample casting.
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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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Production of castings from Cu-Ni based alloys
Kelbl, Michal ; Kaňa, Václav (referee) ; Záděra, Antonín (advisor)
This master thesis is focused on melting of Cu-Ni based alloys and production of castings from these alloys. The theoretical part includes introduction of Cu-Ni based alloys and their properties and application. At the end of this part is production foundry technology of Cu-Ni alloys described. In the practical part two proposed melt controls for cupronickel (Cu-Ni) and for monel (Ni-Cu) have been performed. From these melts trial castings, castings of blades and bearings have been produced. The trial casting and the casting of bearing have been produced by using sand moulds and the casting of blade by using ceramic shell. According to internall quality of produced castings the performed melt controls have been evaluated. In addition to the internal quality of the castings, the chemical composition, microstructure and mechanical properties were evaluated.
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Decarburisation and degassing of high-alloyed Cr steels under vacuum
Ertelt, Tomáš ; Pernica, Vítězslav (referee) ; Záděra, Antonín (advisor)
The work deals with the investigation of the effects of vacuum degassing and decarburization in high alloyed stainless steel. The reason for this is to increase corrosion resistance and mechanical properties. The theoretical part is devoted to the analysis of options to reduce carbon, nitrogen, hydrogen and manganese at atmospheric pressure and in vacuum. In experimental part there is the description of melting, calculation of conditions facilitating reduction of oxide inclusions as a function of the gas pressure in the furnace and the evaluation of the influence of vacuum on the content reduction of carbon, nitrogen and manganese.
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