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1

Comparison of solidus and liquidus temperatures of real low carbon steel grade obtained by use of thermal analysis methods

Smetana B., Kawuloková M., Zlá S., Kalup A., Strouhalová M., Řeháčková L., Rosypalová S., Tkadlečková M., Michalek K., Dobrovská J.

Prace Instytutu Metalurgii Żelaza

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2016

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T. 68, nr 2

33--39

EN

Praca dotyczy badania temperatur przemian fazowych (temperatur solidus i likwidus) z użyciem różnych metod analizy termicznej. Obecnie kluczowymi metodami analizy termicznej są: różnicowa analiza termiczna DTA, skaningowa kalorymetria różnicowa oraz „bezpośrednia” analiza termiczna TA. Praca przedstawia podstawowe zasady, charakterystykę, zalety, wady i wyniki uzyskane przy użyciu tych trzech, bardzo często stosowanych metod. Przedstawiono wyniki z zakresu wysokiej temperatury (powyżej 1000°C) z naciskiem na zakres topnienia i krzepnięcia stali. Omówiono wyniki uzyskane przy zastosowaniu wspomnianych metod podczas procesu nagrzewania/chłodzenia, z uwzględnieniem różnych obciążeń analizowanych próbek i innych czynników, które mogą wpływać na uzyskane wyniki. Podano ocenę krzywych nagrzewanie/chłodzenie DTA i DSC. Porównano i omówiono uzyskane temperatury solidus i likwidus.

PL

The paper deals with the study of phase transition temperatures (solidus and liquidus temperatures) with the use of different thermal analysis methods. Currently, the key thermal analysis methods are DTA (Differential Thermal Analysis), DSC (Differential Scanning Calorimetry) and ‘direct’ thermal analysis (TA). The study presents the basic principles of these methods, their characteristics, advantages, disadvantages and results obtained with these three very often used methods. There paper presents results from the high temperature region (above 1000°C) with the focus on the melting and solidifying region of real steel grade – multicomponent alloy. The paper discusses results obtained with the three mentioned methods at heating/cooling process, with different loads of analysed samples and other factors that can influence the obtained results. The evaluation of heating/cooling curves, DTA and DSC – curves at heating and cooling is demonstrated. The obtained solidus and liquidus temperatures are compared and discussed.

2

Effect of Chemical Composition and Temperature on Viscosity and Structure of Molten CaO-Al2O3-SiO2 System

Řeháčková L., Rosypalová S., Dudek R., Ritz M., Matýsek D., Smetana B., Dobrovská J., Zlá S., Kawuloková M.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2873--2878

EN

The effects of the change of chemical composition and temperature on the viscosity of CaO-Al2O3-SiO2 oxide system with basicity from 0.78 to 1.63 were investigated in this paper. Experimental measurements of viscosity were performed with use of the high-temperature viscometer Anton Paar FRS 1600. Viscosity was measured in a rotational mode during heating at the rate of 2.2 K/min in the temperature interval from 1673 to 1873 K. Viscosity is often sensitive to the structural changes in molten oxide systems, which implies that the analysis of viscosity is an effective way to understand the structure of molten oxide systems. Exact clarification of the change of structure of the oxide system caused by increased content of CaO was performed by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction (XRD).

PL

W artykule badano wpływ zmian składu chemicznego i temperatury na lepkość układu tlenków CaO-Al2O3- SiO2 o zasadowości od 0.78 do 1.63. Pomiary doświadczalne lepkości przeprowadzono z użyciem wiskozymetru wysokotemperaturowego Anton Paar FRS 1600. Lepkość mierzono w układzie obrotowym w czasie ogrzewania z szybkością 2.2 K/min w zakresie temperatur 1673-1873 K. Lepkość jest często wrażliwa na zmiany strukturalne w ciekłych układach tlenkowych, co oznacza, że analiza lepkości jest skutecznym sposobem, aby zrozumieć strukturę układu ciekłych tlenków. Przeprowadzono dokładne wyjaśnienie zmiany struktury systemu tlenków spowodowane zwiększeniem zawartości CaO przy użyciu metody FTI R (Fourier transform infrared spectroscopy), spektroskopii Ramana i XRD (X-ray diffraction).

3

Influence of CaO content on viscosity of molten CaO-Al2O3-SiO2 system

Řeháčková L., Rosypalová S., Dudek R., Dobrovská J.

Archives of Materials Science and Engineering

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2013

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Vol. 59, nr 2

61--68

EN

Purpose: The objective of this work is experimental determination of temperature dependences of viscosity of the molten CaO-Al2O3-SiO2 system and assessment of impact of CaO on the viscosity of this system. Design/methodology/approach: The ternary oxide system CaO-Al2O3-SiO2, which represents a simplified basis of the casting powder, was chosen for the experiment. Dependencies of viscosity on the concentration of CaO and on the temperature were determined experimentally. For this purpose were prepared a concentration series with additions of 3, 6, 9, 12 and 15 wt.% of calcium oxide. Experimental measurements of viscosity was performed with use of the high-temperature viscometer Anton Paar FRS 1600. Findings: Viscosity of the studied systems decreases exponentially with the increasing temperature. Viscosity decreases with the increasing addition of CaO. Viscosity reaches its minimum value of 0.447 Pa.s (at T = 1723 K) at the basicity of CaO/SiO2 = 1.13. Viscosity increases with the further addition of CaO (CaO/SiO2 > 1.2). Influence of addition of CaO is more pronounced at higher temperatures. Research limitations/implications: Viscosity in molten oxide system is determined by the internal structure. Exact clarification of the change of structure of the oxide system caused by the increased content of CaO requires additional analyses, such as Fourier transformation infrared spectra and Raman spectra. Practical implications: The choice of an optimum slag mode influences not only the main metallurgical processes, but also the values of technical-economic indicators of the whole steelmaking process. Viscosity is an important factor affecting the service properties of slags, as it plays an important role in the area of mass transfer at chemical reactions in metallurgical processes. Originality/value: The viscosities of CaO-Al2O3-SiO2 system were measured under conditions of CaO/SiO2 = 0.78-1.44, 47.20-35.98 wt.% SiO2, 36.90-51.90 wt.% CaO and 15.90-12.12 wt.% Al2O3.

4

Study of Fe-C-based alloys by dynamic methods of thermal analysis

Gryc K., Smetana B., Žaludová M, Tkadlečková M., Michalek K., Socha L., Klus P., Dobrovská J., Machovčák P.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 2

694--699

EN

Purpose: of this paper is to determine the temperatures of liquidus/solidus temperatures for multicomponent Fe-C-based alloys (industrially produced steel grades). The obtained results could be used in settings of conditions of steel casting and/or in the numerical simulations of processes occurring during casting and solidification of steel. Design/methodology/approach: Two modern apparatus for dynamic thermal analysis were used. Measurements of liquidus/solidus temperatures were realized by two thermal analysis methods. Experiments by the differential scanning calorimetry were done using the new one Setaram Multi High Temperature Calorimeter with 3D sensor (smaller samples about 2.6 g). The direct thermal analysis was used for large samples (23 g) at the STA 449 F3 Jupiter equipment. Findings: The differences between calculated and experimentally obtained values of liquidus/solidus temperatures were found. Also temperatures of solidification process are different than for “equilibrium” conditions. Practical implications: Presented results will be implemented into steel production practice - lowering of superheating of steel during ingot casting. The obtained temperatures will be implemented also into numerical simulations of ingot solidification. Originality/value: Two thermal analysis methods with different sample mass of steel was used under conditions of one research team. The direct cooperation between steel plant experts and university research team was applied. The utilization of results is the next phases of cooperated research of the authors.

5

Vyhodnocení tvorby sulfidických vměstků v závislosti na chemickém složení a podmínkách tuhnutí

Francová H., Dobrovská J., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2008

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z. 92

43-44

6

Vyhodnocení difúzních koeficjentů niklu a jejich teplotní závislostí ve svarovém spoji ocelí

Řeháčková L., Kalousek J., Dobrovská J.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2008

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z. 92

55-56

7

Vliv hydraulických podmínek proudění taveniny oceli na účinnost filtrace keramickými filtry

Stránský K., Bažan J., Dobrovská J., Belko J., Podrábský T., Glownia J.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2007

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Vol. 321, z. 89

43-44

8

Application of high temperature DTA-technique to in 738LC superalloy

Dobrovská J., Smetana B., Dočekalová S.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2006

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z. 88

29-34

9

Vybrané mikrosegregační parametry po průřezu plynule litého sochoru

Dobrovská J., Dobrovská V., Rek A., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2004

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z. 78

57-60

10

Vliv podmínek krystalizace na tvorbu sulfidů v ocelích

Francová H., Dobrovská J., Dobrovský L., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2004

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z. 78

67-72

11

Příspěvek k modelování teplotní závislosti difúzních koeficientů ve svarovém spoji ocelí

Reháčková L., Million B., Dobrovská J., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2004

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z. 78

119-124

12

K chemické mikroheterogenitě mikrolegovaných ocelí

Dobrovská J., Dobrovská V., Rek A., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2004

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z. 78

61-66

13

Heterogenita slitiny Inconel 713 LC

Pospíšilová S., Stránský K., Podrábský T., Pantělejev L., Rek A., Dobrovská J., Juliš M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2004

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z. 78

185-190

14

Vliv chemického složení na parametry meze pevnosti při tečení slitiny in 713 LC

Podrábský T., Hrbáček K., Dobrovská J., Němec K., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2003

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z. 76

195-204

15

Lomové chování plynule lité ocelové bramy v intervalu teplot 25 (stopni) C - 1450 (stopni) C

Dobrovská J., Kozelský P., Dobrovská V., Věchet S., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2003

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z. 76

69-74

16

Kinetika redistribuce prvků v niklové superslitiné

Dobrovská J., Hrbáček K., Dobrovská V., Rek A., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2003

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z. 76

63-68

17

Chemická heterogenita litiny s kuličkovým grafitem

Dobrovská J., Bažan J., Dobrovská V., Winkler Z., Kavička F., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2003

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z. 76

57-62

18

Vliv tepelného zpracování na chemickou heterogenitu niklových superslitin

Dobrovská J., Dobrovská V., Kudrman J., Rek A., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2002

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z. 75

21-24

19

Koncentrační závislost rozdělovacích koeficientů prvků v systémech na bázi železa při tuhnutí - 1

Dobrovská J., Dobrovská V., Kavička F., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2002

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z. 75

25-28

20

Koncentrační závislost rozdělovacích koeficientů prvků v systémech na bázi železa při tuhnutí - 2

Dobrovská J., Dobrovská V., Kavička F., Stránský K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2002

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z. 75

29-32