Metalurgija 48 (2) 69

K. Michalek, K. Gryc, J. Morávka - Physical modelling of bath homogenisation in argon stirred ladle

The paper presents results of bath behaviour in the ladle model investigation during its gas argon bubbling realised by one or two stir elements situated in the ladle bottom. The study was performed with use of physical modelling method on a scale model 1 to 10. Development of homogenisation processes after start of bubbling was evaluated on the basis of electrical conductivity and temperature change, which were measured at three points of the ladle volume by conductivity and temperature sensors. Executed works were realised for conditions of 180 tons steel ladles.
PDF - 1094 kB

K. Michalek, J. Morávka, K. Gryc - Mathematical identification of homogenisation processes in argon stirred ladle

Mathematical models processed results of experimental investigation obtained during ladle gas argon bubbling realized by stir elements situated in the ladle bottom. Exact theoretical description of processes occurring at argon bubbling into steel would be very complex and it would lead to a system of non-linear partial differential equations describing transfer of momentum, heat, components, and with excitation function in the form of equation of so called deterministic chaos (argon bubbling). On the basis of pouring ladle model diagram and concentrations courses, the simplified linear physically adequate model was proposed, which described behavior of steel concentration in pouring ladle during its bubbling. The analysed process was understood in the form of a cybernetic model.
PDF - 261 kB

J. Vlček, V. Tomková, P. Babková, M. Vavro - Alkali-activated composites based on slags from iron and steel metallurgy

Slag as a secondary raw material from metallurgy is most often heaped in slag disposal areas without any profit. This paper deals with alkali activated slag from iron and steel production which can be used in the building industry. Products of alkali slag activation fulfill the role of inorganic binders.
PDF - 426 kB

J. Bažan, K. Stránský, D. Horáková - Chemical composition and morphology of oxidic ceramics at filtration of steel deoxidised by aluminium

Composition and morphology of filter ceramics were investigated during filtration of steel deoxidised by aluminium. Filtration was realized with use of filters based on oxidic ceramics Cr₂O₃, TiO₂, SiO₂, ZrO₂, Al₂O₃, 3Al₂O₃·2SiO₂ and MgO·Al₂O₃. It was established that change of interphase (coating) occurs during filtration of steel on the surface of capillaries of ceramics, where content of basic oxidic component decreases. Loss of oxidic component in the coating is replaced by increase of oxides of manganese and iron and it is great extent inversely proportional to the value of Gibbs' energy of oxide, which forms this initial basis of ceramics.
PDF - 1385 kB

M. Poíhoda, J. Molínek, R. Pyszko, M. Velička, M. Vaculík, J. Burda - Heat transfer during cooling of hot surfaces by water nozzles

Method of cooling in a secondary zone of continuous casting of steel has a significant influence on a quality of continuously cast products mainly from the point of view of internal and surface defects as well as zonal segregations. At the department of thermal engineering, a physical model of the secondary zone has been developed, which enables testing of both water and water-air nozzles. During laboratory measurements cooling effects of a cone nozzle have been expressed by means of three parameters. Most commonly used parameter is an admission characteristic, infrequently heat transfer coefficient is determined and newly a measuring of dynamic impact of the cooling water has been introduced.
PDF - 995 kB

R. Dudek, L'. Dobrovský, J. Dobrovská - Study of surface tension of inorganic melts based on their chemical composition and temperature

The paper deals with the investigation of selected physical - chemical properties of inorganic melts with respect to behavior of surfaces. An explorational approach was applied in order to acquire original data enabling extension of the existing databases of material properties. The research itself was realized on a series of samples of oxidic melts obtained by incremental additions of CaO. Temperature was another criterion for observation of changes of properties of investigated systems. The obtained data describing their macroscopic behavior were then interpreted on the basis of realized X-ray diffraction analyses and published theories on structures of ionic melts. This confrontation made it possible to complete theoretical notions of physical - chemical properties of melts, which worked so far only with homogenous systems.
PDF - 245 kB

T. Elbel, J. Hampl - Influence of Al and Ti on microstructure and quality of compacted graphite iron castings

The contribution is aimed at study of influence of chemical composition of compacted graphite cast iron (CGI) on microstructure and surface quality of castings, particularly on the occurrence of pinholes. It has been found out that aluminium and titanium in CGI effect the formation of this defect in castings. Aluminium content in the range of 0,02 up to 0,1 % is critical. Increased occurrence of pinholes was also determined with Ti contents above 0,1%. On the same set of experimental castings it has been found out that increased contents of those elements on the other hand support the crystallization of compacted graphite. But the utilization of that method for control of CGI microstructure is limited with a possibility of formation of surface defects in castings - pinholes, but also coldshuts and shrinkage cavities.
PDF - 666 kB

M. Greger, M. Černý, L. Kander, J. Kliber - Structure and properties of Titanium for dental implants

This paper describes manufacture of nano-structural titanium, its structure and properties. Nano-titanium has higher specific strength properties than ordinary (coarse-grained) titanium. Nano-titanium was produced by the equal-channel angular pressing (ETAP) process. The research it self was focused on physical base of strengthening and softening processes and developments occurring at the grain boundaries during the ECAP process at half-hot temperature. Strength of nano-titanium varies around 960 MPa, grain size around 300 nm.
PDF - 11832 kB

B. Strnadel, K. Matocha - Testing samples size effect on notch toughness of structural steels

In the paper notch toughness assessment of full scale testing samples (FS) form the upper bound toughness of sub-sized (SS) samples of structural carbon-manganese steels. The relations proposed by Schindler (2000) are in good agreement with experimental data. Empirical proportionality constant q* = 0,54 between notch toughness of full scale and sub-sized samples of studied structural steels agrees well with theoretically estimated constant q* = 0,50-0,54. More precise knowledge of the size effect of testing samples on temperature dependence of notch toughness requires an analysis of scatter in experimental data.
PDF - 2011 kB

J. Kliber, S. Aksenov, R. Fabík - Numerical study of deformation characteristics in plane strain compression test (PSCT) volume certified following microstructure

Thermal and mechanical parameters of forming and the process of microstructure development should be brought as close to real-world conditions as possible. The plane strain compression test and subsequent computer simulation provided an analysis of the recrystallization kinetics. A study of distribution of deformation characteristics in the sample upon upsetting was performed together with an analysis of microstructure of AISI 304 steel during hot forming. The result of the investigation is information on grain size in the sample in relation to applied strain.
PDF - 4794 kB

M. Greger, V. Vodárek, L. Kander, M. Černý - Working steel P2-04BCH by equal channel angular extrusion (ECAE)

The article presents results of investigation of structure and properties of low-carbon steel grade P2-04BCH after application of ECAE at temperature of approx. 290 C. The ECAE method leads to significant improvement of strength of investigated material. Investigation of structure was made by combination of TEM and FEG SEM together with EBSD. It was proven the ECAE method enables obtaining of ultra fine-grained ferritic structure formed by recrystallised grains with very low density of dislocations and with a small portion of spheroidised carbides, which occurred usually on the boundaries of ferritic grains.
PDF - 1676 kB

R. Kocich, J. Kliber, M. Herout - Finite elements method (FEM) simulation based prediction of deformation and temperature at rolling of tubes on a pilgrim mill

3D - FEM simulation was used as an efficient tool for description of stress-deformation thermal field at rolling of tubes on a pilgrim mill. The monitored objectives comprised also behaviour of working tools at this rolling. This paper assumes rolling of already pierced thick-walled blank, which passes through the pilgrim stand at simultaneous reduction of thickness of inside and outside diameters at the expense of elongation of initial length. Main attention is focused on the mentioned parameters with respect to various conditions of rolling, such as different heat transfer, different friction or different distance of insertion of the rolled product into the gauge. The input data used at simulation were derived from real conditions of tubemaking.
PDF - 2184 kB

R. Fabík, T. Kubina, S. Aksenov, K. Drozd, I. Schindler, J. Kliber - Verification of new model for calculation of critical strain for the initialization of dynamic recrystallization using laboratory rolling

This paper presents a new model for calculation of critical strain for initialization of dynamic recrystallization. The new model reflects the history of forming in the deformation zone during rolling. In this region of restricted deformation, the strain rate curve for the surface of the strip exhibits two peaks. These are the two reasons why the onset of dynamic recrystallization DRX near the surface of the rolled part occurs later than in theory during strip rolling. The present model had been used in a program for simulation of forming processes with the aid of FEM and a comparison between the physical experiment and a mathematical model had been drawn.
PDF - 3063 kB

Z A G R E B October / December 2 0 0 9		Original Scientific Paper	Preliminary Note	Review
Z A G R E B October / December 2 0 0 9		Review Paper	Professional Paper	ARCHIVE 1996 - 2009

48 year issue	Metalurgija - Journal for Theory and Practice in Metellurgy
Metallurgy 48 (4) 213 - 284 PDF - 42592 kB	ISSN 1334-2576 UDC:669+621.7+51/54(05)=163.42=111 METABK: 48 (3) 141 - 212 (2009)

Authors	Original Scientific Paper
K. Michalek, K. Gryc, J. Morávka	Physical modelling of bath homogenisation in argon stirred ladle abstract, article page 215 - 218 PDF - 1094 kB
K. Michalek, J. Morávka, K. Gryc	Mathematical identification of homogenisation processes in argon stirred ladle abstract, article page 219 - 222 PDF - 261 kB
J. Vlček, V. Tomková, P. Babková, M. Vavro	Alkali-activated composites based on slags from iron and steel metallurgy abstract, article page 223 - 227 PDF - 426 kB
J. Bažan, K. Stránský, D. Horáková	Chemical composition and morphology of oxidic ceramics at filtration of steel deoxidised by aluminium abstract, article page 229 - 233 PDF - 1385 kB
M. Poíhoda, J. Molínek, R. Pyszko, M. Velička, M. Vaculík, J. Burda	Heat transfer during cooling of hot surfaces by water nozzles abstract, article page 235 - 238 PDF - 995 kB
R. Dudek, L'. Dobrovský, J. Dobrovská	Study of surface tension of inorganic melts based on their chemical composition and temperature abstract, article page 239 - 242 PDF - 245 kB
T. Elbel, J. Hampl	Influence of Al and Ti on microstructure and quality of compacted graphite iron castings abstract, article page 243 - 247 PDF - 666 kB
M. Greger, M. Černý, L. Kander, J. Kliber	Structure and properties of Titanium for dental implants abstract, article page 249 - 252 PDF - 11832 kB
B. Strnadel, K. Matocha	Testing samples size effect on notch toughness of structural steels abstract, article page 253 - 256 PDF - 2011 kB
J. Kliber, S. Aksenov, R. Fabík	Numerical study of deformation characteristics in plane strain compression test (PSCT) volume certified following microstructure abstract, article page 257 - 261 PDF - 4794 kB
M. Greger, V. Vodárek, L. Kander, M. Černý	Working steel P2-04BCH by equal channel angular extrusion (ECAE) abstract, article page 263 - 266 PDF - 1676 kB
R. Kocich, J. Kliber, M. Herout	Finite elements method (FEM) simulation based prediction of deformation and temperature at rolling of tubes on a pilgrim mill abstract, article page 267 - 271 PDF - 2184 kB
R. Fabík, T. Kubina, S. Aksenov, K. Drozd, I. Schindler, J. Kliber	Verification of new model for calculation of critical strain for the initialization of dynamic recrystallization using laboratory rolling abstract, article page 273 - 276 PDF - 3063 kB

Home	Preliminary Note
M. Velička, R. Pyszko, M. Poíhoda, J. Molínek	Research of heat transport in mould for continuous casting of steel abstract, article page 277 - 280 PDF - 211 kB

Top of Page	Review Paper
D. Noskievičová	Statistical analysis of the blast furnace process output parameter using arima control chart with proposed methodology of control limits setting abstract, article page 281 - 284 PDF - 356 kB

October / December 2 0 0 9 Top of Page		Original Scientific Paper	Preliminary Note	Review
October / December 2 0 0 9 Top of Page		Review Paper	Professional Paper	ARCHIVE 1996 - 2009