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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

Influence of Direct Thermal Analysis Experimental Conditions on Determination of the High Temperature Phase Transformation Temperatures

Gryc K., Strouhalová M., Smetana B., Socha L., Michalek K.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2867--2872

EN

Thermo-physical and thermodynamic properties of metallic systems represent some of the most important data that allows to describe their behaviour under strictly specified conditions. These data are the basic, input data for simulative programs, which can model this behaviour and they can be applied to real conditions. Method of direct thermal analysis is the one of the methods of enabling to obtain such data. This paper deals with application of this method on particular sample of pure standard material. The experimental laboratory system for thermal analysis Netzsch STA 449 F3 Jupiter was used for experimental measurements. This paper is studying the influence of experimental conditions on the obtained temperature of phase transformations and on shift of phase transformation temperatures with respect to the monitored experimental conditions, accuracy and credibility of the measured data. Acquired values of this data could be significantly influenced by experimental conditions, size (mass) of samples, purity of inert atmosphere and also by regimes of controlled heating and cooling rates.

PL

Właściwości fizyczne i termodynamiczne układów metalicznych stanowią jedne z najważniejszych danych, które pozwalają opisać ich zachowanie w ściśle określonych warunkach. Dane te są podstawowymi danymi wejściowymi dla programu, który może symulować model tych zachowań i które mogą być zastosowane do rzeczywistych warunków. Metoda prostej (bezpośredniej) analizy termicznej jest jedną z metod pozwalających na uzyskanie takich danych. Niniejszy artykuł dotyczy zastosowania tej metody, w szczególności próbki czystego materiału standardowego. Do pomiarów eksperymentalnych było używane urządzenie dla analizy termicznej Netzsch STA 449 F3 Jupiter. W artykule analizowano wpływ warunków doświadczalnych na uzyskane temperatury przemian fazowych oraz na zmiany temperatur przemian fazowych z uwzględnieniem monitorowanych warunków doświadczalnych, dokładności i wiarygodności danych pomiarowych. Warunki doświadczalne, wielkości (masa) próbek, czystość atmosfery obojętnej, a przedziały kontrolowanej szybkości ogrzewania i chłodzenia mogą w znaczący sposób wpływać na otrzymane wartości tych danych.

3

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).

4

The effect of boundary conditions of casting on the size of porosity of heavy steel ingot

Tkadlečková M., Michalek K., Gryc K., Smetana B., Machovčák P., Socha L.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 56, nr 1

29--37

EN

Purpose: The paper presents new knowledge from numerical modelling of porosity in heavy steel ingot using ProCAST software. The main aim of numerical modelling realized under the conditions of the Department of Metallurgy and Foundry and Regional Materials Science and Technology Centre at the VSB-TU Ostrava is the optimization of the production of heavy steel ingots produced at the companyVítkovice Heavy Machinery a.s. Design/methodology/approach: The selected method of numerical modelling enables 3D fully dimensional numerical simulation of steel casting and the subsequent solidification of steel with the possibility of prediction of ingot defects. Findings: The numerical modelling of casting and solidification of the 90 ton heavy steel ingot under different boundary conditions of the casting led to these main conclusions: In all simulated variants, the final character of solidification was very similar. The lowest level of porosities were achieved in the variant when we used the longer filling time together with decrease of casting temperatures. However, the tested adjustment of casting technology appeared to have only small impact on the resulting porosity. Practical implications: The change of geometry of the mould will have probably more effect on the character of the solidification than only the small changes of the casting parameters which are dependent on the steel grade. Originality/value: On the basis of applied research in close collaboration with industry companies, the obtained data can contribute significantly to optimization the operating conditions, thereby increasing the efficiency of the steelmaking technology and final quality of cast steel.

5

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.

6

Utilization of thermal analysis to thermo physical properties study of real steel grades

Klus P., Zaludova M, Gryc K., Smetana B., Michalek K., Dobrovska J., Tkadleckova M., Socha L.

Archives of Materials Science and Engineering

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2012

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Vol. 58, nr 2

116--119

EN

Purpose: This paper deals with determining the temperatures of phase transformations in real steel grades. It also includes the study of industrially produced steel grades using the methods of thermal analysis by experimental equipment STA 449 F3 Jupiter made by NETZSCH and Setsys 18TM made by SETARAM. Design/methodology/approach: Selected methods of thermal analysis (DSC and DTA) enable to obtain the temperatures of phase transformations taking place in steel during the linear heating/cooling. Within the casting technology of steel, thermal analysis is used to determine the solidus temperature and especially the crucial liquidus temperature. Findings: Experimentally obtained solidus and liquidus temperatures are higher in the DSC method (max. 3.8°C). The difference between the temperatures of phase transformation (T) running between the solidus temperature (TS) and liquidus (TL) for both methods (DTA and DSC) differ by a maximum of 3.2°C. The results from experimental measurements were compared with theoretical calculations of liquidus and solidus temperatures by different authors and with the computed results from thermodynamic database COMPUTHERM and also with temperatures from the equilibrium phase diagram of Fe-Cr-C. Experimentally obtained solidus temperatures are lower than the calculated equilibrium solidus temperatures. Experimentally obtained liquidus temperatures are in the range of temperatures obtained using computational relations. The temperatures mentioned in the equilibrium phase diagram (diagram for a particular steel grades was not found) are higher than experimentally obtained temperatures. Research limitations/implications: The results of experimental studies can be used to refine the knowledge of basic physical properties of steel and for example replacement of the tabulated values or estimated values of phase transformation temperatures and thermal capacity. Furthermore, the obtained data will be implemented in the material databases of numerical programs used for the simulation of metallurgical processes. Originality/value: On the basis of applied research in close collaboration with industry companies, the obtained data can contribute significantly to optimize the operating conditions, thereby increasing the efficiency of the steelmaking technology and final quality of cast steel.

7

Study of lead-free solders liquidus and solidus temperatures by means of DTA-method

Docekalova S., Smetana B., Drapala J., Perinova K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2007

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Vol. 321, z. 89

99-99

EN

The thermal analysis is very effective tool in the study of thermophysical and thermodynamical properties (e.g. temperatures of phase transformations, latent heats -enthalpies of phase transformations,...) among others, metallic systems. One of the most widespread methods of thermal analysis used for the description of metallic systems behaviour is the Differential Thermal Analysis - DTA. The aim of our work was study of characteristic phase transformation temperatures (temperatures of solidus - T$ and liquidus - TL) of lead-free solders on the base of tin. In total 22 alloys with different ratios of individual elements Ag, Cu, In, Sb, Bi, Zn and Sn were prepared experimentally. In addition, six alloys of lead-free solders produced commercially (Kovohute Pf ibram) were used and the Pb-Sn solder served as a comparative alloy. The alloys were prepared by smelting of input metals in the graphite crucible followed by casting into graphite boat. Temperatures of solidus and liquidus were obtained with use of experimental laboratory system SET ARAM SETSYS 18TM TG/DTA/TMA. Samples of solders in the form of small disordered pieces (size up to approx. 3 mm and max. mass 0.2 g) were during measurement heated and cooled in a controlled manner at the rate of 4°C/min. The A12O3 crucibles were used for measurement. Argon (purity > 99.999999%) was used for washing of the inert space of oven before each analysis (flow time approx. 15 min), then evacuation followed and again filling up with argon. During analysis the constant dynamical atmosphere was kept in the oven space (flow rate of argon was 2 1/h). Differences between experimentally determined temperatures of Ts, TL acquired during controlled heating and cooling were observed. These differences could be influenced not only by undercooling, but also by dynamics of measuring process.

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