Authors

Microstructure Analysis of Internally Oxidized Cu-C Composite
abstract, article page 79 - 84 pdf - 1231 kB

Design of Thermo Mechanicaln Processing and
Transformation Behaviour of Bulk Si-Mn Trip Steel
abstract, article page 85 - 91 pdf - 1715 kB

R. Rudolf, L. Kosec, A. Križman, I. Anžel - Microstructure Analysis of Internally Oxidized Cu-C Composite

    On the basis of experimentally obtained data, it was established that submicron-size bubbles are formed by the internal oxidation of Cu-C composite with fine dispersed graphite particles. They are homogeneously distributed in the Cu-matrix. This process starts with the dissolution of oxygen into the metal at the free surfaces, and continues with the diffusion of oxygen atoms into the volume of copper crystal lattice where they react with the graphite particles. The reactions of dissolved oxygen with carbon yield the gas products (CO₂, CO), which cannot be dissolved in the crystal lattice of the matrix. The gas molecules, which are enclosed in the space previously occupied by the graphite, have a greater specific volume than the solid graphite. Consequently, compressive stresses arise in the copper matrix around the bubbles. The interaction of these stress fields with gliding dislocations during loading could improve the mechanical properties of the copper. The internal oxidation kinetic in Cu-C composite depends on the diffusion of oxygen in the copper matrix, and the penetration depth of the internal oxidation front indicates the parabolic nature of the process. pdf - 1231 kB

J. Zrnik, I. Mamuzić, P. Lukaš, O. Muransky, P. Jenčuš, Z. Novy - Design of Thermo Mechanicaln Processing and Transformation Behaviour of Bulk Si-Mn Trip Steel

    In the last decade, a lot of effort has been paid to optimising the thermomechanical processing of TRIP steels that stands for transformation induced plasticity. The precise characterization of the resulting multiphase microstructure of low alloyed TRIP steels is of great importance for the interpretation and optimisation of their mechanical properties. The results obtained in situ neutron diffraction laboratory experiment concerning the austenite to ferrite transformation in Si-Mn bulk TRIP steel specimens, displaying the transformation induced plasticity (TRIP), are presented. The advancement of ferrite formation during transformation in conditioned austenite is investigated at different transformation temperatures and has been monitored using neutron diffraction method. The relevant information on transformation proceeding is extracted from neutron diffraction spectra. The integrated intensities of austenite and ferrite neutron diffraction profiles developed during the transformation are then assumed as a measure of the phase volume fractions of both phases in dependence on transformation temperature and austenite conditioning. According to the yielding information on ferrite volume fractions from isothermal transformation kinetics data the thermo mechanical processing of bulk specimen was designed in order to support austenite stabilization through bainitic transformation. The volume fractions of retained austenite resulting at alternating transformation conditions were measured by neutron and X-ray diffraction respectively. The stability of retained austenite in bulk specimens during room temperature mechanical testing was characterized by in situ neutron diffraction experiments as well. pdf - 1715 kB

M. Gavas - Increasing the Deep Drawability of Al-1050 Aluminum Sheet using Multi-Point Blank Holder

  Aluminum alloys have been widely used in the fields of automobile and aerospace industries. Due to their bad cold-formability in deep drawing, a lot of forming methods have been implemented to increase the drawing height and the limiting drawing rate (LDR). The conventional deep drawing process is limited to a certain limit drawing ratio beyond which failure will ensue. The purpose of this experimental study is to examine the possibilities of increasing this limitation using the multi-point blank holder. The results from the experiments showed that the multi-point blank holder is effective way to promote deep drawability of Al-1050 sheet. pdf - 1225 kB

V. V. Chygyryns'ky, I. Mamuzić, F. Vodopivec, I. V. Gordienko - The Influence of the Temperature Factor on Deformability of the Plastic Medium

  Using the solution of a closed problem of the theory of plasticity some analytic expressions were obtained for determination of the strain parameters of zone of deformation in view of the temperature factor. pdf - 494 kB

F. Trebuňa, F. Šimčák, M. Buršák, J. Bocko - Increasing of Reliability of Converter

  The innovative activities in steel production invoke exploitation of new machines with the higher production capacity and productivity of labor. The paper deals with deformation and stress analysis of carrying parts of converter pedestal on the base of which the proposals and supporting measures were made that had the aim to increase reliability of the converter during steel production. This was achieved by lifespan prolongation of anchor and connecting bolts of converter pedestal, by change of stiffness of connected elements as well as by correction of nuts of bolted connections. The realization of structural changes decreased loading amplitudes and consequently the vibrations of pedestal. Solution was verified by numerical and experimental procedures of mechanics. pdf - 1598 kB

V. Janotka, J. Viskup, B. Pandula, I. Lesso - Soil Profiles and Seismic Loading

  The contribution estimates different geotechnical profiles of site condition change and their influences on the computed seismic response spectra and time histories final values and forms applying on the seismic structures loading. The mentioned problems methodics attitude solution is based on the computed seismic motion parameters. pdf - 726 kB

J. Kijac - Study of the Metallurgical Aspects of Steel Micro-Alloying by Titan

  The metal properties upgrading applying it’s alloying with the simultaneous limitation of the impurities represents a prospective possibility of the metallurgical production further development. The interaction of the alloying substance active element with oxygen in metal and adjacent multiphase environment occurs under the actual conditions. Present paper is oriented particularly to the thermodynamic aspects of deoxygenation by titan in process of production of micro alloyed low carbon steel in two plants (oxygen converter 1-OC1 and 2-OC2) with the different effect of micro-alloy exploitation. Analysis of the effect of the metallurgical factors on the titan smelting loss in micro-alloyed steel production points at the need to master the metal preparation for the alloying and especially has got the decisive effect upon the oxidizing ability and rate of the slag phase availability. When comparing the micro-alloying matter yield among the individual production units, disclosed have been better results obtained in plant OC 2. Confirmed has been the effect of the slag amount (average amount of 7,3 t at OC 1 and 5,83 t at OC 2) and its quality during the steel tapping as one among the most significant factors affecting the alloying process and which also represent its oxidizing potential. pdf - 1650 kB

E. Štroffek, P. Peterka, J. Krešák, S. Kropuch - Diagnostics of Pipelines System

   Underground gas storage in Slovakia has a 25 years history. The first phase of building, the object for underground reservoir Láb began in 1977. The underground reservoir is separated into five independent parts, phases of building. All parts are concentrated in central control area. The oldest part of equipment for underground reservoir needs overhaul and maintenance today. The maintenance process uncovers a lot of problems that were created through building process. The great problems are uncovered in the area of pipeline system diagnostics. In the past, maintenance operators faced difficult decisions, to choose the best method or combination of methods to evaluate pipeline condition. pdf - 1014 kB

J. Dvořáček, V. Vodzinský, L. Domaracká - Industrial Wastes and Economics of their Utilization

   The contribution deals with the utilization of industrial wastes, especially from mining and metallurgical enterprises. The wastes are being processed into the form of hydraulic non-washable stowing which can be deposited in the closed underground mines. The economic aspects of this activity which compete with depositing of non-processed industrial wastes on surface stockyards are considered here. pdf - 363 kB