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

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.