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Zaludova M.,Regional Materials Science and Technology Center | Smetana B.,Regional Materials Science and Technology Center | Zla S.,Regional Materials Science and Technology Center | Dobrovska J.,Regional Materials Science and Technology Center | And 5 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2013

The paper deals with the study of phase transformation temperatures of the model Fe-C-O based metallic alloys in the high temperature region (above 1,000 C). Six model alloys with graded carbon and oxygen content were prepared and studied. Temperatures of phase transitions were obtained using DTA method (differential thermal analysis). The Setaram SETSYS 18™ (TG/DTA/DSC/TMA) modular experimental system was used for measurements. Influence of composition change (carbon and oxygen content) on shift of phase transformation temperatures is investigated in this paper. New original data (phase transformation temperatures) were obtained in this study. Controlled heating of the alloys was conducted at the rates of 2, 4, 7, 10, 15 and 20 C min-1. Comparison of the obtained experimental data with the data presented in the literature was also carried out. It follows from comparison of the obtained results with the data accessible in the literature that a lack of experimental data exists, and these available data significantly differ. © 2012 Akadémiai Kiadó, Budapest, Hungary. Source


Kocich R.,VSB - Technical University of Ostrava | Kocich R.,Regional Materials Science and Technology Center | Kunicka L.,VSB - Technical University of Ostrava | Kunicka L.,Regional Materials Science and Technology Center | Machakova A.,Regional Materials Science and Technology Center
IOP Conference Series: Materials Science and Engineering | Year: 2014

The paper proposes a new variation of the application of SPD methods. For the suggested TCMAP (twist channel multi angular pressing) technology a larger strain is imposed more effectively while homogeneity of material is increased. The number of passes needed to obtain the ultra-fine to nano-scale grains in bulk materials can be significantly reduced. Commercially pure Al (99.97%) was used for the experimental verification of the suggested process. The deformation parameters of the process were also described using a numerical simulation based on a FE analysis. The predicted value of imposed strain after a single pass reached approximately 2.7. Deformation homogeneity was confirmed by micro-hardness tests. Due to the designed shape of the channel both ends of the processed sample are defined by a higher imposed strain and vertical faces. © Published under licence by IOP Publishing Ltd. Source


Smetana B.,VSB - Technical University of Ostrava | Smetana B.,Regional Materials Science and Technology Center | Zaludova M.,VSB - Technical University of Ostrava | Zaludova M.,Regional Materials Science and Technology Center | And 8 more authors.
METAL 2013 - 22nd International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2013

The paper deals with the study of latent heats of melting and solidifying of Fe based metallic alloys. One real steel grade and "pure" iron were investigated and values of latent heats of melting and solidifying were obtained. Latent heats are very important quantities for thermodynamic and kinetic modelling. Latent heats are valuable data for many SWs used for technological processes modelling. Many SWs for casting of alloys use these quantities. These data are also necessary for proper modelling of processes connected with welding simulation processes. The obtained data can serve for the addition and enhancement of many thermodynamic databases. Continuous thermal analysis (DSC) was performed to obtain the values of latent heats. Latent heats were studied using Setaram MHTC (Multi High Temperature Calorimeter) Line 96 equipped with 3D DSC sensor. Comparison between melting and solidifying latent heats was performed. Advantages of Setaram MHTC equipment are discussed also. Experimental measurements were realised under controlled heating and cooling rate in an inert atmosphere of He. Comparison of experimental, calculated and accessible data in the literature was performed. It follows from the obtained results the necessity of further systematic research of studied quantities. © 2013 TANGER Ltd., Ostrava.. Source


Smetana B.,Regional Materials Science and Technology Center | Zaludova M.,Regional Materials Science and Technology Center | Tkadleckova M.,Regional Materials Science and Technology Center | Dobrovska J.,Regional Materials Science and Technology Center | And 6 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2013

Heat capacity of alloys (metals) is one of the crucial thermophysical parameters used for process behaviour prediction in many applications. Heat capacity is an input variable for many thermodynamical (e.g. Thermocalc, Pandat, MTData,.) and kinetic programs (e.g. IDS-Solidification analysis package,.). The dependences of heat capacity on common variables (temperature, pressure,.) are also commonly used as the input data in software packages (e.g. ProCast, Magmasoft, ANSYS Fluent,.) that are applicable in the field of applied research for simulations of technological processes. It follows from the above that the heat capacities of materials, alloys in our case, play a very important role in the field of basic and applied research. Generally speaking, experimental data can be found in the literature, but corresponding (needed) data for the given alloy can very seldom be found or can differ from the tabulated ones. The knowledge of proper values of heat capacities of alloys at the corresponding temperature can be substantially used for addition to and thus towards the precision of the existing database and simulation software. This study presents the values of Cp measured for the hematite ingot mould and comparison of the measured data with the Cp values obtained using the software CompuTherm with respect to simulation of technological casting process. © 2013 Akadémiai Kiadó, Budapest, Hungary. Source


Smetana B.,VSB - Technical University of Ostrava | Smetana B.,Regional Materials Science and Technology Center | Zaludova M.,VSB - Technical University of Ostrava | Zaludova M.,Regional Materials Science and Technology Center | And 13 more authors.
METAL 2014 - 23rd International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2014

The paper deals with the study of phase transitions temperatures (mainly solidus and liquidus) with use of different thermal analysis methods. The key thermal analysis methods are at the present days DTA (Differential Thermal Analysis), DSC (Differential Scanning Calorimetry) and "direct" thermal analysis (TA). The study presents the basic principles of these methods, characteristics, advantages and disadvantages. There are presented results from the high temperature region (above) 1000 °C with focus on the melting and solidifying region of multicomponent alloys such as steels. The paper discusses obtained results with three mentioned methods at heating/cooling process, with different loads of samples and other factors that can influence the obtained results. The evaluation of heating/cooling curves, DTA (DSC) - curves at heating and cooling is demonstrated. The obtained solidus and liquidus temperatures are compared and discussed. Source

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