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Original Scientific Paper
Preliminary Note
Review
Review Paper
Professional Paper
ARCHIVES 1996 - 2004
40
year issue
Metalurgija - Journal for Theory and Practice in Metellurgy
Metallurgy 60 (64) page
ISSN 1334-2576    UDC: 669+51+53+54(05)=862=20=30    METABK: 40 (3) 125 - 184 (2001)
Authors
Original Scientific Paper
M. Terčelj,
R. Turk, P. Cvahte

Characterization of the Laboratory Tool Wear in Hot Extrusion of Aluminium
abstract, article page 135 - 138
V. V. Chygyryns´kyy,
I. Mamuzić

The Investigation of the Influence of Correcting Stress Component in the
Three-dimensional Solution on some Parameters of the Process of the Copuplex
Shapes Rolling abstract, article page 139 - 142
Authors
Preliminary Note
A. Trišč
Coke Combustion Efficiency in Sintering Process
abstract, article page 143 - 146
I. Koštial, Ľ. Dorčák,
J. Terpák, I. Petráš,
M. Rogáľ, M. Halmo,
P. Nemčovský
Real Time Blast Furnace Modelling
abstract, article page 147 - 150
D. Constantinescu
A Model of the Dynamics of Burned Gases in Heating Furnaces for Rolling Mills
abstract, article page 151 - 156
A. Varga, M. Pastor,
Z. Zsigraiova
Study of Flowing in Fixed Charge Bed
abstract, article page 157 - 159
N. A. Semashko,
E. V. Lanovenko,
V. V. Lanovenko,
A. V. Frolov
Research of Phase Transformations in Titanium and Titanium Alloys by
Ultrasonic Method abstract, article page 161 - 164
M. Knap,
R. Turk
Expert System for Determination of the Optimal Control Program for the
Workability Testing of Materials on the Gleeble 1500 Machine
abstract, article page 165 - 168
Authors
Professional Paper
J. Grum,
B. Pečnik, D. Fefer

Description of Various Degrees of Cold Plastic Deformation Structural Steel
Based on Barkhausen Noise abstract, article page 169 - 173
M. Tatič,
A. Mašlejová
Effect of MgO Addition into Slag on Refractory Wear
abstract, article page 175 - 180
V. Bauer,
F. Zeleňák
Environmental Impacts of Mining and Processing of Gold in Slovak Republic
abstract, article page 181 - 183
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 Original Scientific Paper

M. Terčelj, R. Turk, P. Cvahte - Characterization of the Laboratory Tool Wear in Hot Extrusion of Aluminium

     Laboratory testing of wear of the extrusion tools is much cheaper than direct determination of wear on true tools during the industrial operation. Its efficiency is expressed mainly as the control of influential parameters of the tribologic system, the way of mechanical loading, and the reduction of time needed for the estimation of tool life. In order to bring our testing conditions near to true physical characteristics of the hot extrusion process and to intensify (shorten) the process of wear analysis, a test named ¨block on disc¨ was developed and applied to simulate true tribologic system during the hot extrusion of aluminium. The tool was nitrided and tested in the new developed equipmet at different testing conditions. Wear volume depended on the aluminium temperature and normal force. Time needed to reach sufficiently high wear volume was relatively short in comparison to other wear tests.

V. V. Chygyryns´kyy, I. Mamuzić - The Investigation of the Influence of Correcting Stress Component in the Three-dimensional Solution on some Parameters of the Process of the Copuplex Shapes Rolling

     An analitical solution for a three-dimensional problem of the theory of plasticity has been obtained which represents a set of the basic solution along one of the planes and additional one making allowance for the linear interaction of adjacent elements of the strip. The influence of the last factor on the rolling process parameters in conditions of the non-uniform reduction was analysed. The mentioned correspondence was corroborated by experiment, which comes as evidence of the competent character of the physical statement of three-dimensional problem in such a version.

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Preliminary Note
A. Trišč - Coke Combustion Efficiency in Sintering Process

    The aim of this work was to determine conditions at which sinter quality is stable and fuel consumption is lower. The study of the coke combustion efficiency in sintered bed was carried out in laboratory scale. During experiments the sucked-out air rate was controlled in interval from 10 to 55 cm/s. The concentration of CO, CO2 in waste gases and temperatures in sintered bed and temperature of waste gases were recorded. It was find out that by decrease of sucked-out air rate the coke combustion efficiency (ratio CO2/CO) increases. At the same time, temperature in sintered bed increases and amount of the heat conducted away reduces.

I. Koštial, Ľ. Dorčák, J. Terpák, I. Petráš, M. Rogáľ, M. Halmo, P. Nemčovský - Real Time Blast Furnace Modelling

     The present blast furnace control systems are mainly based on black box principles. The great furnace capacity and transport have an inconvenient influence on their efficiency. The white box approach requires the combination of measurement and mathematical modeling. This approach was used for the blast furnace No. 3 at VSŽ Košice and a mathematical model for process observation, process prediction and process simulation was developped, which gives a picture of the processes in the furnace. The model is based on continous real time inputs and gives forward information on blast furnace state and processes and enables the operator to check decision alternatives. In the models is applied analytical, empirical and artificial inteligence approaches. The principal structure of the control system is described.

D. Constantinescu - A Model of the Dynamics of Burned Gases in Heating Furnaces for Rolling Mills

     The work establishes a model regarding the thermodynamics of a continuous heating furnace. Theoretical results are verified experimentally, using a physical hydraulic model. The results were applied to remodel the general aspect of the furnace. Using the theory of similitude, the work establishes a connection between the temperature, the speed and the general aspect of the dynamic of burned gases. To transfer the experimental results to the real furnace, it was necessary to take in consideration the dynamic aspects and the thermal aspects. The remodeling of the heating space of a continuous furnace takes into consideration the theoretical and experimental results regarding the temperature and the dynamic of the gases.

A. Varga, M. Pastor, Z. Zsigraiova - Study of Flowing in Fixed Charge Bed

     In the paper authors deal with problems of influence of outlet velocities as well as burner outlet jets incline on fuel - primary air stream penetration to secondary cooling air in a fixed charge bed.

N. A. Semashko, E. V. Lanovenko, V. V. Lanovenko, A. V. Frolov - Research of Phase Transformations in Titanium and Titanium Alloys by Ultrasonic Method

     Experimental researches of the acoustic properties of titanium materials at the broad temperature range are demonstrated in this paper. Sound velocity (C) and damping factor (a) were investigated. These physical characteristics of materials contain extensive information of structural, magnetic and other transformations in metals and alloys. The researches were carried out with an ultrasonic pulse method [1, 2]. Samples of a pivotal type and removing to the cold zone sensor were used for researching. Velocity of sound describes the forces of atom’s interactions that determine rigidity of a material. The damping coefficient characterizes ability of material for irreversible dispersion of elastic strain energy. This parameter allows to define a degree of relaxation of stresses that arises in the grain boundaries while polymorphic tranaforming, ferromagneting, etc. [3].

M. Knap, R. Turk - Expert System for Determination of the Optimal Control Program for the Workability Testing of Materials on the Gleeble 1500 Machine

     In research group has introduced an expert system into everyday testing practice. Its task was to control the whole route from the order, to the selection of the most appropriate type of test, control of experiment itself, and to the writing the protocol with the obtained results [1]. First results showed us that material databases formed in such a way are more accurate and closer to the users’ demands. This paper is limited to elucidation of determining the program for mechanical control of Gleeble 1500 testing machine, taking in account expected loads related to single materials, thermal and mechanical loads, and the selection of tool.
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Professional Paper

J. Grum, B. Pečnik, D. Fefer - Description of Various Degrees of Cold Plastic Deformation Structural Steel Based on Barkhausen Noise

     The magnetic Barkhausen effect is a phenomenon occurring during magnetisation of ferromagnetic materials and related to movements of magnetic domains under the influence of an alternating magnetic field. Behaviour of magnetic domains is dependent on microstructure characteristics such as grain size and grain orientation, cold deformation, microhardness, residual stresses, dislocations, impurities. In the investigation, a deep-drawing steel DIN St10 in the soft condition, in the form of plate and strips having various initial thicknesses, which were subsequently cold rolled to a uniform thickness, was used. The test pieces used were hardened by cold deformation, and had a changed microstructure and modified microhardness with regard to the degree of cold plastic deformation.

M. Tatič, A. Mašlejová - Effect of MgO Addition into Slag on Refractory Wear

     Prolongation of the oxygen converter refractory lining durability influences the price of the produced steel. Slag with low content of MgO has got the high dissolution capacity and high potential of the lining components diffusion into the slag. The objective of the slagging operation of the converter bottom modelling by the slag forming mixtures was to replace the removed MgO from the lining by its addition into the slag. Another goal was to estimate the optimum composition of the optimum thickness of the sticked slag-forming mixture, having suitable porosity of the slag forming-mixture after melting. pdf - 418 kB

V. Bauer, F. Zeleňák - Environmental Impacts of Mining and Processing of Gold in Slovak Republic

     In Slovakia, Au-Ag ores from the Hodruša ore region are traditionally exploited. The area of perspective mining extraction is also the deposit of tetraedrite ore of the Strieborná vein (Mária Baňa mine) in Rožňava. The extracted volume of these relatively poor ores is small and the production of Au is at the order of kilograms per year. The Au production meets many problems due to the low quality of the ore mined, the small capacity of the auriferous localities as well as the actually low price of Au on world markets. The so-called gold program is presently being realized in Slovakia in conformity with the ore mining transformation to precious metals. This transformation requires the yield of concentrate to be increased with a complex utilization of other components. Additionally, the winning and processing of Au and Ag have specific economical and ecological aspects and risks that should be solved and controlled. This article presents the possible environmental risks of mining and processing auriferous ores in Slovakia.
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