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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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Use of 3D technology in foundry industry
Straka, Pavel ; Krutiš, Vladimír (referee) ; Pernica, Vítězslav (advisor)
The work is focused on replacing a faulty briefcase handle with an aluminium substitution. The handle is fabricated with the help of reverse engineering, where the handle is scanned with a 3D scanner. With that information, a model copy of the part is made, which is 3Dprinted from PLA and PolyCast materials. These handles are used as expendable models, which are used for casting using an “investment casting” method. Those are made from an AlSi10Mg alloy. Theoretical part deals with additive technologies, which are mostly used for manufacturing of foundry models and moulds. Next, the basic principles of 3Dscanning are described, and the term reverse engineering is also explained.
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Defects in steel castings
Jakubec, Petr ; Kaňa, Václav (referee) ; Pernica, Vítězslav (advisor)
This bachelor’s thesis deals with the problems of defects that occur in steel castings. First, the use of steel in the foundry industry and the development of classification of casting defects are described. Furthermore, it defines the term ‘casting defect’ and its division. The main part of the thesis focuses on the most frequent defects in steel castings. The aim of this literature search is to describe the casting defects and their causes and to present possible precautions against their rise. Possible ways of removing the casting defects are discussed as well as their repairs.
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Lining of the induction furnaces
Kopečný, Vendelín ; Pernica, Vítězslav (referee) ; Myška, Martin (advisor)
This work deals with lining of electric induction furnaces. The first part describes the preparation of lining, its function during the running of furnace and also its tearing down at the end of work process. In the thesis is also discussed the use of rammed crucibles. The materials used for lining and rammed crucibles are described also in the sense of their chemical properties in connection with the possibilities of their use under different conditions. The practical part of the thesis describes the process of lining the electric induction furnace, which was realized by the author under the supervision of the supervisor.
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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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Foundry molding mixtures with biopolymer binders
Šindlerová, Eliška ; Janský, Vojtěch (referee) ; Pernica, Vítězslav (advisor)
This work is interested in a new modern solutions in the field of foundry binders. Several biopolymer materials suitable for foundry industry are described and the conditions for using these materials and few examples of casting tests with the use of the biopolymer binders. The main reason why the biopolymer materials are coming back to the industry is a huge amount of strict environmental requirements for the ecological behavior of industrial enterprises and current very bad ecological situation. However this inovative solutions doesn´t have to be only benefits for our environment but the can bring various simplifications to the production process, shortening the time required for preparation or technological breaks, and lower the costs of input material and subsequent waste treatment.
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Casting of manganese steels and their use
Dufka, Martin ; Šenberger, Jaroslav (referee) ; Pernica, Vítězslav (advisor)
Austenitic manganese steel, often referred as Hadfield´s steel after its discoverer, has an irreplaceable place in foundry due to its specific properties. Due to local pressures and shocks, surface of castings is hardened, but the cast core retains its toughness. Thus, manganese steel is used for castings of highly stressed machine parts that are subject to abrasive wear. This bachelor thesis is concerned about methods of production, chemical composition, influence of some alloying elements on properties and structure of steel, heat treatment, material properties, reinforcement mechanisms and types of individual deformation reinforcements. Further attention is paid to the most frequent use of manganese castings in practice.
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Melting equipment in foundries
Toufar, Tomáš ; Blažík, Petr (referee) ; Pernica, Vítězslav (advisor)
The aim of this Bachelor thesis is a description of the properties and operation of selected melting equipment in foundries. History of metal processing and development of melting equipment are briefly described. Based on the findings, smeltering systems used in foundry practice were classified and the individual systems were described in terms of their advantages, disadvantages and application. At the end of thesis, melting equipment was assessed from technical-economic point of view.
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Optimation of heavy steel castings
Pernica, Vítězslav ; Veselý, Pavel (referee) ; Šenberger, Jaroslav (advisor)
Diploma thesis deal with definnig the casuses of stell castings defects in the DSB EURO s.r.o Foundry. The main target is to optimise technological parameters for avoiding the surface casting defects. The first stage is the identification of the defects, describing of the main reasons and mechanic. Defect quantification is make from measuring of area and volume of the mended defects. In association with surface defects, the number of the crackings was observed. Finally there are suggested correction actions based on the previous investigation.
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