Ladislav Socha

Evaluation of Chemical and Structural Heterogeneity in a Continuously Cast Steel Billet

Crystallization of metallic materials occurs during their casting and following solidification. The influence of directional material solidification, the size of grains, chemical heterogeneity and existence of any non – compactness, can negatively affect properties of the final product. Microstructural analysis of its longitudinal section was performed to study heterogeneity in a continuously cast steel billet. Three typical areas of the cast structure of the billet were monitored (the chill zone, columnar crystals area and central area of equiaxed crystals). EDX microanalysis and micro-structural analysis were used for evaluation of chemical heterogeneity. Via X-ray microanalysis, concentrations of the following elements were observed: manganese, chromium, silicon, phosphorus, molybdenum and iron. The microanalytical measurements were completed by microhardness measurements in the investigated areas. Based on the measured data it was proven that central areas were enriched with all the substitutional elements including a considerable increase in phosphorus concentration.

Study of macro-segregations in a continuously cast billet

Ta clanek obravnava studij makro-izcej na vzdolžnem prerezu kontinuirno ulite gredice O 160 mm namenjene za proizvodnjo brezsivnih cevi. Ocena je sestavljena iz vizuelnega pregleda po makrojedkanju, iz ocene in kvantitativne rentgenske mikroanalize s pomocjo energijsko disperzijske rentgenske analize (EDX) izbranih podrocij. Izracunani so bili tudi parametri izcejanja s pomocjo podatkov zgorevne analize. Rezultati, prikazani v tem clanku, predstavljajo osnovno informacijo o notranji strukturi v kontinuirno uliti gredici. Rezultati bodo uporabljeni, poleg drugega, tudi za preverjanje rezultatov numericnega modeliranja kontinuirno ulitih gredic.

Distribution of porosity and macrosegregation in slab steel ingot

The paper presents a new knowledge and experiences with verification and optimization of production technology of heavy slab ingot weighing 40 t from tool steel using the results of numerical modelling and of operational experiments at a steel plant in the company VITKOVICE HEAVY MACHINERY a.s. The final porosity, macrosegregation and the risk of cracks were predicted. Based on the results, the slab ingot can be used instead of the conventional heavy steel ingot. Also, the ratio, the chamfer, and the external shape of the wall of the new design of the slab ingot was improved, which enabled to reduce production costs while the internal quality of steel ingots was still maintained at very high level.

Increase of chromium yield by slag reduction during production of chromium steels

The paper is focused on the evaluation of the course of Cr2O3 reduction from slag to alloyed steel under laboratory conditions. The experiments were aimed at the evaluation of increase in the chromium content in the melt together with the studying the behaviour of Cr2O3 and the mechanism of reduction by means of three reducing agents. Anthracite, ferrosilicon and mixtures of anthracite and ferrosilicon belong among the selected reducing agents. The experimental melts were focused on the proposal of a theoretical calculation of the consumption of selected reducing agents, study of reduction under laboratory conditions at application of alloyed steel with content of chromium of 12.16 wt. %, temperatures of 1600 °C and 1650 °C, together with the change of amount of reducing agents and reduction time. The results indicated in the paper constitute basic information on the possibilities of Cr2O3 reduction from slag; they will be used for verification of results in the pilot plant and operation experiments which will simulate operating conditions in the electric arc furnace.

Thermal Analysis Results and the Theoretical Determination of Solidus and Liquidus Temperatures for the Grain Oriented Electrical Steel

This paper is devoted to the comparison of theoretically defined solidus and liquidus temperatures based on above mentioned theoretical methods with the results of high-temperature thermal analysis carried out on two devices (Netzsch STA 449 F3 Jupiter; Setaram SETSYS 18TM). On large samples (23 g), the method of direct thermal analysis was applied. On small samples (200 mg), the experiments using differential thermal analysis were realized. It was found out that the solidus and liquidus temperatures for the studied steel grade can vary in dependence on the used determination method. The used methodology of thermal analysis is fully reproducible, and the these thermo-analytical results can be considered as necessary for the correct setting of critical parameters in applied research on the process of steel casting.

Industrial Experiments Filtration of Steel

The research on the process of steel filtration from non-metallic inclusions is currently entering the last phase of industrial experiments. Their positive effects confirm the previous theoretical assumptions and laboratory tests. The application of steel filtration as a permanent technological operation in the process of steel casting will remarkably improve its metallurgic purity. An additional advantage will be diminishing the probability of covering the outlet nozzle of a tundish. This paper presents an outline of the experiment results mentioned above.

Influence of the Steel Scrap Classes on the Liquid Steel Output Melt in Electric Arc Furnace

The paper analyses methods, the influence of use of charges of steel scrap of different qualities in the EAF on the index of liquid steel output from a melt using statistical analysing methods. The used research methodology consists of analytical simulation of variations in mass of liquid steel obtained from melts differing in steel scrap content in the metallic charge and of statistical analyses of industrial results acquired from the corresponding process documentation (so called melt cards). The obtained research results can be utilized in each steelmaking facility, which employs the Electric Steelmaking process, in order to “design” the metallic charge compositions, having in view the quality and economic aspects. The results presented in this paper are directed to the steelmakers employing the Electric Steelmaking process and constitute the authors original study.