E. Čižmárová, J. Micheľ, I. Mamuzić, M. Buršák - Influence of Strain Rate on Properties of Microalloyed S-MC Steel Grades

     The influence of strain rate on properties of microalloyed steel for cold drawing of S 315 MC and S 460 MC gra-des was analysed. It has been shown by testing these steel that strain rates in the range from 10^-3 up to 1 s^-1 do not influence the mechanical properties significantly. Significant strengthening started at strain rates exceeding 2 s^-1. It has been shown also that the basic mechanical properties of the coldworked tested steel by 5 to 25 % were not influenced by prestrain at 10^-3 to 10³ s^-1 strain rates. It is supposed according to the results, that the susceptibility to cold work of these steel was not influenced significantly by the strain rates usually used at coldwork (less than 1 s^-1) and that the products after coldwork maintain their mechanical properties.

J. Ševčíková, J. Kocich - Contribution to the Investigation of Corrosion Properties of the Ni-Ti Alloy with Shape Memory

     Responsible application of metals with shape memory needs to know degradation processes taking place during their exploitation in real conditions. The contribution investigates corrosion properties of an Ni-Ti alloy containing 55.2 % Ni and 44.8 % Ti in physiological salt solution (0.9 % NaCl at 40 ± 1 °C). The performed laboratory tests found out a high corrosion resistance of the material used mainly in human medicine for implants. By measuring the electrochemical characteristics it could be acknowledged that this is related to the formation of a passive state on the alloy surface during its exploitation.

J. Tušek - Submerged Arc Surfacing with a Multiple-Wire Electrode

     Submerged arc surfacing with a multiple-wire electrode is a new process variant which has been rarely used, in spite of its numerous advantages in comparison to other processes, in practical applications. The unit for surfacing with the multiple - electrode differs little from a classic unit for submerged arc welding with a single-wire electrode. The difference between them consists in that in our unit several wires travel through a joint contact tube simultaneously. All of the wires are fed with the same rate and have a joint regulation and power source. In welding with the multiple-wire electrode it is possible to weld with two, three, four or even more wires simultaneously. In the joint contact tube wires of different diameters and different chemical composition and solid or flux-cored wires may be used. Mechanical properties of surfacing welds depend on the type the parent metal and the filler material, welding parameters and the type of welding flux used.

M. Kundak, J. Črnko, Đ. Nikolić - The Profile of a Pusher-Type Furnace and Fuel Consumption

     Operating data for two pusher-type furnaces, old and new, of approximately identical length but having different longitudinal profiles were analysed. The old furnace had a partly inclined longitudinal profile and the new one had a rectangular longitudinal profile. Results of analysis showed a higher rate of specific fuel consumption for the old furnace than for the new one. To reduce the difference a possibility was considered of building in an air-preheating recuperator instead of relocating the burners and altering the longitudinal profile of the old furnace. Results of quantification demonstrated that by building a recuperator into the old furnace specific fuel consumption would greatly diminish and would become comparable to that of the new furnace.

L. Lazić, P. Jelić, S. Pavlenić - Optimization of Timely Replacement of Sectional Furnace Refractory Lining

     The goal of the study is to establish the influence of temporal wearing of refractory lining on energy losses of the furnaces by conducting heat through the furnaces walls. Object of the study were sectional furnaces, type SELAS, situated in the seam tubes production line in Željezara Sisak, Croatia. In order to reduce production costs, it was attempted to define the timely replacement of refractory lining by the criteria of comparing the costs resulted by heat loss through the furnace lining with the costs of refractory lining replacement. Data for the calculation of heat losses was obtained by use of the infrared camera.

V. Baričak - Fluid Flow within Slide Bearings - the Cause of Self-Exciting Vibration

     Due to rotor rotation fluid in bearing and/or seal is forced to rotate and rotating fluid force is generated. This force induce self-excited vibrations having very high amplitudes. Fluid induced self-excited vibrations model and their characteristics are discussed.

A. Miškufová, T. Kuffa - Problems and Perspectives in Preparation of CaO Refractory

    The development of new materials and technologies is essential for the intensification of the industrial production. This effort is apparent also in the field of the refractory materials, therefore also dead burned lime (CaO) as a refractory material for steel industry is considered. A low hydration and corrosion resistance are the reasons why the CaO refractory has not been widely applied. Research results achieved recently as well as necessary effort for future research activities are discussed in this paper.

D. Bauman - Twenty Six Years of the Scanning Electron Microscopy Tradition in Željezara Sisak

    This retrospective review outlines the direction of development and application of scanning electron microscopy in Željezara Sisak, with emphasis on the 26-years old tradition of scanning electron microscopy in Sisak´s Željezara and the city of Sisak.