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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

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.

3

Crystallisation and microstructure of low-silicon silumins with alloy additions

Pietrowski S.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 3

113-124

EN

The paper presents the results of the analysis of crystallisation and microstructure of non-alloy silumins that contain: 2,0-6,0% of Si and alloy additions, approximately: 4,0% Ni, 4,0% of Cu and 0,5% of Mg, the knowledge of which is still very little. It has been proven that in non-alloy silumins, the increase of silicone concentration causes extending of crystallisation time of the eutectic mixture [...] and refinement of \alfa phase dendrites. It also causes the increase of the temperature of crystallisation of the eutectic mixture [...]. Alloy additions: Ni, Cu and Mg decrease by approximately 30 C the liquidus and solidus temperatures of silumins and extend the time of their crystallisation by around 100 sec. in comparison with non-alloy silumins. It is caused by crystallisation of additional phases Al3NiCu, Mg2Si and Al2Cu. Nickel, copper and magnesium refine the microstructure of castings.

4

Wpływ dodatków stopowych na temperaturę krzepnięcia staliwa austenitycznego

Garbiak M.

Archiwum Technologii Maszyn i Automatyzacji

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2008

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Vol. 28, nr 3

35-40

PL

W artykule przedstawiono wyniki badań, których celem była ocena wpływu niobu, tytanu i krzemu na wartość temperatury początku i końca krzepnięcia staliwa austenitycznego typu 0,3 C--30Ni-18Cr. Metodą ATD rejestrowano krzywe krzepnięcia 15 stopów zawierających 0,03÷3% Nb, 0,03÷5-1,4% Ti oraz 1,6÷4,3% Si. Wykazano, że badane składniki stopowe zwiększają zakres temperaturowy i wydłużają czas krzepnięcia. W stopach z górną zawartością wprowadzonych pierwiastków rejestrowano dwa przystanki temperaturowe i tworzenie się dodatkowego składnika fazowego w mikrostrukturze stopów.

EN

The paper presents the results of research on TDA cooling curves of austenitic cast steel 30Ni-18Cr with niobium, titanium and silicon. The liquidus and the end of solidification temperature were determined for 15 experimental alloys in which the content of alloying elements varied in a range of 0.03-3% Nb, 0.03-1.4% Ti and 1.6÷4.3% Si. It has been found that all the alloying additions decrease the liquidus and end of solidification temperature and they cause an enlargement of the solidification interval. For alloys of the highest total content of Nb, Ti and Si the second temperature arrest on TDA curve was recorded and simultaneously G phase precipitates have been observed in the microstructure.

5

Precision forging of thixoforming materials

Łapkowski W., Sińczak J.

Metallurgy and Foundry Engineering

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2001

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Vol. 27, no. 1

97-103

EN

Aluminium based alloys were tested. The thixoforming conditions were obtained using SIMA method. Before thixoforming the alloys were deformed in the room temperatures and then heated to the temperature above the solidus. The temperatures of beginning and end of recrystallization as well as volume of solid particles surrounded by liquid phase were determined during heating in these experiments. The relationships describing kinetics of recrystallization and coagulation of particles were established. Developed procedure has been used for thixoforging of model forgings with a complex shape in one operation

PL

Praca dotyczy plastycznego odkształcania stopów metali w wysokich temperaturach homologicznych, tj. powyżej punktu solidus (stan półciekły, struktura tiksotropowa). Przeprowadzono próby zastosowania metody odkształcania w obecności fazy ciekłej w konkretnym procesie technologicznym, tj. precyzyjnym kuciu matrycowym odkuwek. Celem badań było eksperymentalne określenie możliwości kształtowania odkuwek o bardzo złożonych kształtach geometrycznych w jednym zabiegu technologicznym (jednym wykroju). Do badań wybrano stopy z grupy durali, tj, stop PA6 (A2017 wg ASTM). W wyniku przeprowadzonych badań stwierdzono, że stan półciekły stwarza niespotykane dotąd warunki wytwarzania odkuwek o złożonych kształtach w jednym wykroju, bezpośrednio z materiału wyjściowego.