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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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Influence of filters on running of metal flow
Makalouš, Jakub ; Veverka, Aleš (referee) ; Roučka, Jaromír (advisor)
This study deals with influence of filters on running of aluminum metal flow. The main objective was to describe hydraulic resistances of assorted filters and running of silting filters by inclusions. Theoretical part generally describes filtration process and also filtration from the point of view of aluminum alloys and the most important characteristics of each type of alumina inclusions. Experimental part deals with flow rate tests, influence of filters on gassiness of melt and metallographic analysis. It was find out, that filter GEPHAL made minimal hydraulic resistance, on the other hand ceramic foam filters type LD made the maximal hydraulic resistance. It is necessary to reduce filtration surface for study running of silting filters by inclusions. Metallographic analysis showed amorphous alumina film inclusions, spinell Al2O3.2MgO, sludge and carbide of silicon.
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Filtration of foundry alloys
Šíma, Jakub ; Láník, Boris (referee) ; Tomek, Ladislav (advisor)
Presented bachelor work deals with filtering of casting alloys. This issue is described with focus on the importance of filtration, the requirements placed on filters, a description of the filtering mechanisms, the influence of using filters on the melt flow, types of filters and options include filters in the gating system of casting. The second part contains case studies of the use of ceramic foam filters in foundry and analysis of samples taken from a particular casting.
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Metallurgy and properties of heavy steel castings
Kubík, Jiří ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
The work deals with the determination of the chemical composition and morphology of inclusions in experimental casting foundry in operating conditions as ŽĎAS in compliance with the optimum content appropriate deoxidation depending on the conditions of solidification. The introductory part is devoted to theoretical analysis of possible defects in castings. We also describe the experimental casting, sampling sites and their markings. Subsequently evaluated morphology microanalysis inclusions and the effect of inclusions on the mechanical properties and the formation of defects in the casting. The conclusion summarizes the results and proposal for further direction in the production of heavy steel castings.
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Reoxidation in steel
Kotásek, Petr ; Veselý, Pavel (referee) ; Šenberger, Jaroslav (advisor)
This work is about development and methodology verification of data collection which will be used in the research of the reoxidation in steel castings. To examine reoxidation rate will be measured oxygen activity in the furnace, in the ladle and in the mould. Next it will be evaluated the chemical structure of mould slag, the chemical changes of steel and measured the volume and the area of the casting defects. Each technique is briefly described by the principle of measurement and each method has the results which are analysed. In the conclusion the experiment is summarized and there are mentioned the observations from this experiment.
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Influence of using the secondary metallurgy on steel properties
Navrátil, Horymír ; Fila, Pavel (referee) ; Záděra, Antonín (advisor)
This bachelor thesis describes metallurgical processes of production of steel in electric arc furnaces. It also describes oxidation and reduction phases of melting. Furthermore, it describes the main elements of secondary metallurgy used in steel foundries and their applications. The thesis also concerns with impurities in the steel, namely non-metallic inclusions, gases and trace elements, which is also connected with final utility properties of the steel. This thesis also describes in detail the technological properties of steel. The influence of several selected elements on steel properties is also described. Finally, the thesis evaluates the effect of secondary metallurgy on the volume of defects in steel castings, on mechanical properties and the resulting chemical composition.
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Cleanliness of steels manufactured in vacuum induction furnaces
Pastyřík, Petr ; Záděra, Antonín (referee) ; Pernica, Vítězslav (advisor)
The topic of this thesis is the micropurity of steels manufactured in vacuum induction furnaces. The thesis describes 3 processes of steel melting using the same type of steel with different production parameters. Subsequently, samples were prepared and based on those samples the micropurities of the melting processes were evaluated. To obtain the results image analysis and electron microscope were used. Furthermore, elemental analyzer was used to measure the content of oxygen, nitrogen, sulphur and carbon. Afterwards, a discussion on micropurity and comparison of the melting processes is presented. In the conclusion section there are some possible suggestions concerning operation of the university foundry.
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Recrystallization study of free-cutting steel by in-situ SEM/EBSD technique
Babinský, Tomáš ; Němec, Karel (referee) ; Petrenec, Martin (advisor)
Placing recrystallization annealing in a manufacturing proces is often necessary in order to restore plasticity of worked blanks right before working products to its final shape. For better understanding of processes which are taking place in a material during annealing the use of in-situ techniques is favorable. Such observations enable us to watch changes in the materiál in real time at the original spot. Observations at grain-level are ideally made with scanning electron microscope – SEM by electron back-scattered diffraction – EBSD. The technique makes watching nucleation, growth and potential coarsening of recrystallized grains possible. Special construction of a tensile stage allows us to watch changes of a sample during tensile tests which can be used in observing influence of MnS inclusions on plasticity of free-cutting steels. Materials studied in this work are commonly used free-cutting steel 11SMnPb30 and its lead-free alternative 11SMnBi30.
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