J. Kubicki, B. Piekarski - Aluminium Protective Coatings Produced on Creep-Resisting Steel Directly in a Casting Mould

     The structure of coatings and their ability to protect the castings made of G-X25NiCrSi 36-17 (DIN 17006) cast steel against carburization have been described. Al-Cu and Al-Si protective coatings, produced directly in a casting mould, have a considerable thickness (400 - 2000 µm), and complex multiphase structure. Its main structural constituents are: g(Fe, Ni, Cr), a(Fe, Ni, Cr), bAl(Ni, Fe), carbides M₂₃C₆ and M₇C₃. In Al-Si ferritic coatings are also present: g(Ni, Fe), a(Fe, Al, Ni, Cr) and (Cr, Si)₃Ni₂Si. Carburisation changes substantially the structure of coatings, what results in an increase of the amount of g(Fe, Ni, Cr) or g(Ni, Fe) and carbides, and a decrease of the amount of a(Fe, Ni, Cr) and bAl(Ni, Fe). Apart from above mentioned changes, the investigated coatings reduce the carbon diffusion by 20 - 65 % Al-Cu, about 55 % Al-Si (austenitic), and 75 % Al-Si (ferritic), so they can provide a temporary protection against high-temperature corrosion. pdf - 408 kB

F. Lofaj, F. Dorčáková - The Effect of Lanthanides on Viscosity of Re-SI-MG-O-N Glasses

     Compressive creep behavior of RE-Si-Mg-O-N glasses (RE = La, Yb, Sm and Lu) was investigated to determine temperature dependency of their viscosity in temperature range from 770 °C up to 895 °C. Viscosity and heat transfer through the glass (T_g) were increased by > 10 times and by 26 °C, when La is replaced with Lu in the corresponding glasses. Assuming valence Z = +3 and coordination number CN = 6 of the RE ions, T_g depends approximately linearly on cationic field strength except Yb. T_g of Yb-containing glass also falls on linear dependence provided CN = 8 in the case of Yb. Lanthanides seem to modify the structure of the corresponding glasses and bond strength rather than the mechanisms of deformation. pdf - 167 kB

A. Konstanciak - High-Temperature Investigation of the Properties of Blast Furnace Coke

     The behavior of coke in the blast furnace is discussed in this article. The methods of taking charge coke samples from blast furnace have been verified. The tests of the effect of temperature on coke (subjected to laboratory tests reproducing, to a certain extent, the conditions prevailing at the tuyere level of the blast furnace) have established factors responsible for the degradation of coke. This has allowed the parameters characterizing the structure to be described as follows: L_c, the crystallite height is contained in range 1.5932 - 3.2620 nm; L_a, the crystallite width is in the range 2.82013 - 5.7737 nm; and the crystallinity factor, W_k, is contained in the range 0.147 - 0.77014. pdf - 350 kB

V. Goryany, I. Mamuzić, V. Radsinsky - Influence of Cooling on the Resistance of Chrom-Nickel Iron Rolls

     The work deals with findings of possibility to increase the wear resistance of grooves of 250 wire mill finishing stand rolls by improving their cooling conditions, which provides increase in operating resistance of rolls 1.5-2 times. pdf - 70 kB

P. Kováč, J. Kijac, V. Masek, P. Marek, P. Kalmár, K. Michalek - Steel Cleanliness Improvement through Tundish Configuration Optimizing

     In continuous casting process, liquid steel flows through the tundish, which is supposed to operate as a continuous refining finisher. To provide a functionality of such a device, a pack of tundish metallurgy techniques must be applied, whose efficiency is conditioned especially with optimal symmetrical and dynamical melt flow. Flow optimizing can be achieved through the shaping of inside tundish configuration, using flow control devices such as turbulence inhibitors, impact pads, baffles, weirs, dams, etc. The theme of the present paper is the precise employment of a turbulence inhibitor, commercially known as TURBOSTOPTM, together with a pair of baffles & a flat impact pad in slab custer to improve steel cleanliness and a fluid flow phenomenon in a two strands tundish. pdf - 255 kB

D. Rydz, H. Dyja, S. Berski - The Prediction of Curvature of Bimetallic Plate Al-Cu During Asymmetrical Cold Rolling

     In the paper, solving a problem of rolling Al-Cu plates by the numerical way is presented. In the development of new technologies in rolling of bimetallic plates there are many problems both with ensuring a uniform strain distribution and producing a straight plate as well. Such a solution within research of the numerical simulation was obtained at the Forge 2 program based on finite element method. The cold rolling process was carried out at the temperature of 20 °C for 10 %, 20 % and 25 % relative rolling reduction. The curvature of bimetallic plate was numerically controlled by changing the speed of one roll. In this article the numerical analysis of asymmetrical rolling processes of plate composed with two metal layers, Al and Cu, has been done. At the work an influence of rotary speed ratio and value deformation on change of curvature bimetallic plate is determined. pdf - 148 kB

M. Holtzer, J. Dańko, R. Dańko - Environmental Impact of the Use of Automotive Scrap as Charge Material in Metallurgical Processes

     Increased content of automotive scrap in metallurgical charge raises the content of zinc and lead in the dust from melting installations. Every year 1.2 mln tons of zinc-coated scrap comes to the market to be recycled. The cost of the waste dumping will be systematically growing, this comes refers to both the dumping fee and costs of transport from the plant to the dumping ground. The dust collected in the process of melting is, on one hand, a valuable raw material while, on the other, special processes are required for its effective management. Zinc-containing dust can be processed by two methods: hydrometallurgical refining and pyrometallurgical refining. pdf - 138 kB

Ľ. Mihok, D. Baricová - Recycling of Oxygen Converter Flue Dust into Oxygen Converter Charge

     The paper deals with aspects and effects of oxygen converter flue dust recycling into the oxygen converter charge. Flue dust was recycled when solidificated into form of briquettes. No significant effects of the recycling on process of hot metal refining and on quality of produced steel were recorded. Recycling of flue dust briquettes influenced composition and structure of steel making slag, namely its zinc contents and composition of oxygen converter flue dust. Recommendation on recycling of up to 4 000 kg of flue dust briquettes into the 160 t charge of oxygen converter was suggested. pdf - 172 kB