Characterisation of thermal stability and phase transformation energetics in tempered 9Cr–1Mo steel using drop and differential scanning calorimetry

Raju, S.; Ganesh, B. Jeya; Banerjee, Aritra; Mohandas, E.

doi:10.1016/j.msea.2007.01.127

Cited by 58 publications

(41 citation statements)

References 33 publications

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“…For low heating rates, the time of the sample exposure extends and the surface of the sample may undergo decarburization. This is also noticed by other authors [20][21][22].…”

Section: Selection Of Experimental Conditionssupporting

confidence: 87%

Investigations of Temperatures of Phase Transformations of Low-Alloyed Reinforcing Steel within the Heat Treatment Temperature Range

Kargul

2017

Archives of Metallurgy and Materials

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The paper presents the results of DSC analysis of steel B500SP produced in the process of continuous casting, which is intended for the production reinforcement rods with high ductility. Studies were carried out in the temperature range below 1000°C in a protective atmosphere of helium during samples heating program. The main objective of the study was to determine the temperature range of austenite structure formation during heating. As a result of performed experiments: Ac 1s , Ac 1f -temperatures of the beginning and finish of the eutectoid transformation, Ac 2 -Curie temperature of the ferrite magnetic transformation and the temperature Ac 3 of transformation of proeutectoid ferrite into austenite were elaborated. Experimental determination of phase transformations temperatures of steel B500SP has great importance for production technology of reinforcement rods, because good mechanical properties of rods are formed by the special thermal treatment in Tempcore process.

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“…For low heating rates, the time of the sample exposure extends and the surface of the sample may undergo decarburization. This is also noticed by other authors [20][21][22].…”

Section: Selection Of Experimental Conditionssupporting

confidence: 87%

Investigations of Temperatures of Phase Transformations of Low-Alloyed Reinforcing Steel within the Heat Treatment Temperature Range

Kargul

2017

Archives of Metallurgy and Materials

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“…After these considerations, the first peak starting at 700°C can be attributed to the magnetic transformation point [7], where T C (760°C) corresponds to the Curie point, e.g., the temperature at which the metal loses its ferromagnetic properties (for pure iron the Curie point is at 770°C).…”

Section: Resultsmentioning

confidence: 99%

“…carbide ? austenite phase region [7]. After A C3 , the sample is mostly austenitic, although the complete homogenization of this phase may not yet be realized at this stage, as attested by the presence of an endothermic peak at about 930°C [8].…”

Section: Resultsmentioning

confidence: 99%

Microstructural Evolution of a Continuously Cooled Air Hardening Steel

Brunelli

Bassani²,

Lecis

et al. 2013

Metallogr. Microstruct. Anal.

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This study studied the phase transformations occurring at different continuous cooling rates in an air hardening steel used in the rock-crushing industry. Samples of this steel were submitted for calorimetric testing using the differential scanning calorimetry (DSC) technique. In the experimental run, the samples were heated at the rate of 0.33°C/s from 50 to 1050°C and equilibrated at this temperature for 900 s, then cooled at seven different cooling rates between 0.05 and 0.5°C/s. For all the cooling rates, the DSC traces of the samples showed a first exothermic peak at about 500°C and for samples cooled at rates higher than 0.15°C/s, a second exothermic peak at about 295°C was observed. From the microstructural investigations carried out by light microscopy (LM) and scanning electron microscopy (SEM), it was observed that all the samples after DSC treatment were characterized by the presence of bainite. In the samples cooled at rates higher than 0.15°C/s, martensite was also detected. Comparing the results of DSC and SEM, it was concluded that the first peak at 500°C corresponds to the austenite ? bainite transformation, while the second peak at 295°C corresponds to the austenite ? martensite transformation. The experimentally determined bainite and martensite start temperatures were compared to the values derived from a number of well-known empirical equations.

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“…The description of the equipment, calibration (Caluire, France) of heat flux into effective enthalpy and data analysis procedures have been presented in detail in our previous publications and therefore are not elaborated upon here [19,20]. The experiment in its essence consists of instantaneously dropping a sample kept at a fixed reference temperature (T o ) to a well-equilibrated pure alumina bed, maintained at the desired experimental temperature (T) to within ±0.1 K. The alumina bed is located well within the isothermal zone of a resitively heated graphite furnace.…”

Section: Inverse Drop Calorimetrymentioning

confidence: 99%

Drop Calorimetry Studies on 9Cr–1W–0.23V–0.06Ta–0.09C Reduced Activation Steel

et al. 2010

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The temperature dependence of enthalpy increment (H T − H 298 ) of 9 mass% Cr-1 mass% W-0.23 mass% V-0.06 mass% Ta-0.09 mass% C reduced activation steel has been measured by inverse drop calorimetry in the temperature range 400 K to 1273 K. A critical comparison of present isothermal enthalpy measurements with the results of our previous dynamic calorimetry studies has been made to reveal clearly the occurrence of various diffusional phase transformations that occur at high temperature. These phase changes are marked by the presence of distinct inflections or cusps in an overall nonlinear variation of enthalpy values with temperature. The principal thermal relaxation step of the martensitic microstructure obtained through quenching from the high-temperature γ -austenite phase is observed around 793 K. The ferromagnetic-to-paramagnetic transition of the α-ferrite phase is found to occur at 1015 K. The equilibrium values of γ -austenite start (Ae 1 ) and finish (Ae 3 ) temperatures are found to be 1063 K and 1148 K, respectively. A value of 12 J · g −1 has been estimated for • H α→γ the latent heat associated with the α → γ transformation. The measured enthalpy increment variation of the α-ferrite phase with temperature has been fitted to a suitable empirical function to estimate the temperature-dependent values of the specific heat. A comparison of the drop calorimetry-based indirect estimate of the specific heat with the direct differential scanning calorimetry-based values revealed that the drop calorimetry estimates are systematically lower than its dynamic calorimetry counterpart. This difference is attributed to the fact that, under finite heating rate conditions that are typical of dynamic calorimetry, measurements 123 400 Int J Thermophys (2010) 31:399-415 are made under nonequilibrium conditions. Notwithstanding this limitation, there is a good overall agreement between the two C p values and also among the phase transformation temperatures so that a reliable assessment of thermal properties and phase transformation characteristics of reduced activation steel can be determined by a combined analysis of the results of drop and differential scanning calorimetry.

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Characterisation of thermal stability and phase transformation energetics in tempered 9Cr–1Mo steel using drop and differential scanning calorimetry

Cited by 58 publications

References 33 publications

Investigations of Temperatures of Phase Transformations of Low-Alloyed Reinforcing Steel within the Heat Treatment Temperature Range

Investigations of Temperatures of Phase Transformations of Low-Alloyed Reinforcing Steel within the Heat Treatment Temperature Range

Microstructural Evolution of a Continuously Cooled Air Hardening Steel

Drop Calorimetry Studies on 9Cr–1W–0.23V–0.06Ta–0.09C Reduced Activation Steel

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