National Repository of Grey Literature 12 records found  previous11 - 12  jump to record: Search took 0.01 seconds. 
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.
Manufacturing and defects of steel castings
Smilovský, David ; Čamek, Libor (referee) ; Záděra, Antonín (advisor)
A content of this thesis is an analysis of a steel castings production mismatch in Tatra Metallurgy foundry. Most common defects found on castings are gas holes. Thesis shows a theoretical research on casting defects caused by gases in steel castings. It also describes melting and degassing problematics of molten steel and procedures to reduce gas contents. The last part of theoretical research describes oxidation of steel in contact with silica mold. Practical part of thesis analysis production of steel castings to determine the cause of origin of gas holes. Main attention is paid to mold mixture, chemical composition, casting temperatures and casting time. The last chapter metallographically analysis two defected castings to determine the origin of defects. Main attention is paid to shape and chemical composition of gas holes and to morphology of steel inclusions.

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