A Thermodynamic Database for Fe-Cr-Mn-Ni-Ti-S-C-N System

Oikawa, Katsunari; Mitsui, Hajime; Ishida, K.

doi:10.4028/www.scientific.net/msf.500-501.711

Cited by 12 publications

(7 citation statements)

References 31 publications

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“…The symbols in these figures represent the calculated results using CVM, and the solid lines show the Gibbs energy evaluated by fitting the CVM values using Eqs. (11) and (13). The solid lines in Fig.…”

Section: Calculated Formation Energy Kj/mol Of Atommentioning

confidence: 96%

“…Thermodynamic calculations based on the calculation of phase diagrams (CALPHAD) method have been performed to evaluate the thermodynamic properties of materials. 11,13) However, the thermodynamic parameters optimized in these calculations were obtained only using the experimental values, such as solubility products and phase equilibria, and the calculation accuracy greatly depends on the reliability of experimental values. Recently, first-principles calculations combined with a statistical thermodynamics technique have been applied to evaluate the thermodynamic stability of sulfides in IF steels at finite temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic Study on Solubility Products of Ti4C2S2 in Fe Using First-Principles Calculations

Saeki

Yamashita²,

Ohtani

2020

ISIJ Int.

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This study elucidates the solubility product of Ti 4 C 2 S 2 in steels by means of first-principles calculations and thermodynamic analysis. For this purpose, the Gibbs formation energy of Ti 4 C 2 S 2 was calculated theoretically by considering the effect of lattice vibration and thermal expansion. In addition, the Gibbs energies of the bcc and fcc phases in the Fe-TiC ternary system were also obtained using the cluster expansion and cluster variation method. Although some experimental data were considered as required, those results were evaluated as the calculation of phase diagrams (CALPHAD)-type thermodynamic parameters through fitting to the sublattice model. By using those thermodynamic functions, an approximate expression of the solubility product for Ti 4 C 2 S 2 was derived. The result agrees with an experimental result measured in a relatively large temperature range. Furthermore, the formation behavior of precipitates in typical interstitial-free steels was discussed, incorporating an earlier thermodynamic analysis on the Fe-Ti-S ternary system. The results show that NiAs-type TiS was the main precipitate at higher temperatures and that Ti 4 C 2 S 2 was the main precipitate at lower temperatures.

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Section: Calculated Formation Energy Kj/mol Of Atommentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Thermodynamic Study on Solubility Products of Ti4C2S2 in Fe Using First-Principles Calculations

Saeki

Yamashita²,

Ohtani

2020

ISIJ Int.

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“…Ti 4 C 2 S 2 precipitates when slab reheating temperature is lower than 1 100°C. Oikawa et al 15) explained by using Yamada and Niikura 28) report, that Ti 4 C 2 S 2 is stable but the activation energy for nucleation is large. Therefore the meta-stable TiS or MnS precipitates during slab reheating at around 1 200°C.…”

Section: Comparison With Previous Workmentioning

confidence: 99%

“…Computer simulation of precipitation in ULC Ti-stabilized steels has been done. Oikawa et al 15) reviewed the solubility products in the literatures in comparison with their thermodynamic calculation by CALPHAD. They concluded that Ti 4 C 2 S 2 is more stable than TiS and MnS.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mn on Solubility of Ti-sulfide and Ti-carbosulfide in Ultra-low C Steels

Mizui¹,

Takayama²,

Sekine

2008

ISIJ Int.

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“…We have already developed the thermodynamic database for Fe-Ti-C-Cr-S-Mn-Ni system. 18,19) In this study, we focused on the phase equilibria FeS-XS and MnS-XS (XS: TiS, NbS and VS) systems, because Ti, V and Nb are very strong affinity for sulfur in steels. Only a few works about phase stability and phase equilibria of sulfide mixtures in these system have been reported, 20,21) although these are essential information to determine the function of the thermodynamic database.…”

Section: Introductionmentioning

confidence: 99%

Phase Equilibria in FeS–XS and MnS–XS (X=Ti, Nb and V) Systems

et al. 2009

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The phase equilibria in the FeS-XS and MnS-XS (X: Ti, Nb and V) pseudo-binary systems were investigated by using an X-ray diffraction and electron probe micro analyzer. In the FeS-TiS and FeS-VS systems, a mono-sulfide with the NiAs structure form a complete solid solution, while two-phase separation of the mono-sulfide with the NiAs structure is observed in the FeS-NbS system. In all MnS-XS systems, twophase region of a Mn-rich mono-sulfide and X-rich mono-sulfide exists widely. Solubility of each elements in the Mn-rich mono-sulfide and X-rich mono-sulfide is small, except that of Mn in Nb-rich mono-sulfide.KEY WORDS: iron sulfide; manganese sulfide; titanium sulfide; niobium sulfide; vanadium sulfide; phase equilibria.powder-synthesizing method using high purity iron, manganese, titanium, niobium, vanadium and sulfur powder. The mixed powders were uniaxially pressed at 250 MPa to form a green compacts with a cylinder shape in a diameter of 15 mm. The green compacts were sealed in evacuated quartz capsules and heat treated at 673 K for 72 h, and then elevated to 1 173 K and kept for 24 h to promote a chemical reaction of each powder. The prepared specimens were cut into four pieces and sealed again in evacuated quartz capsules. The small pieces in the quartz capsule were equilibrated at 1 173-1 573 K, and then the quartz capsule was dropped into ice water.Microstructure observation and composition analysis of the mirror-polished sections of the specimens were carried out by using an electron probe micro analyzer (EPMA). Xray diffraction (XRD) was used for the analysis of crystal structure of the equilibrated specimens ground to powder of the FeS-XS systems. Experimental Results FeS-XS SystemsTypical backscattering electron images (BEI) of (Fe 0.2 Ti 0.8 )S mixture annealed at 1 273 K for 10 h is shown in Fig. 1. Black and white color regions are void and metallic phases, respectively and the matrix in gray color is the sulfide phase. According to the EPMA analysis of sulfide phase at several points, the chemical composition of sulfide was almost the same value at every analyzed point. This result suggests that the sulfide phase in Fig. 1(a) is a homogeneous phase. Every samples of the FeS-TiS system showed the similar microstructure.Figures 2(a) and 2(b) show the typical XRD patterns obtained from (Fe 0.6 Ti 0.4 )S and (Fe 0.2 Ti 0.8 )S, respectively. The spectrum peaks of Figs. 2(a) and 2(b) can be identified as the NiAs and Ti 8 S 9 structure by Joint Committee on Powder Diffraction Standards of International Center for Diffraction Data (JCPDS-ICDD cards), respectively.22) The NiAs structure is observed a composition region from pure FeS to (Fe 0.4 Ti 0.6 )S and pure TiS, while several samples with high Ti content show the Ti 8 S 9 structure which is called NiAstype superstructure.23) This Ti 8 S 9 structure phase might be transformed from the NiAs structure phase during the cooling, because the phase transformation from the NiAs to the Ti 8 S 9 is very sensitive to the cooling rate.24) The lattice parameter...

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A Thermodynamic Database for Fe-Cr-Mn-Ni-Ti-S-C-N System

Cited by 12 publications

References 31 publications

Thermodynamic Study on Solubility Products of Ti<sub>4</sub>C<sub>2</sub>S<sub>2</sub> in Fe Using First-Principles Calculations

Thermodynamic Study on Solubility Products of Ti<sub>4</sub>C<sub>2</sub>S<sub>2</sub> in Fe Using First-Principles Calculations

Effect of Mn on Solubility of Ti-sulfide and Ti-carbosulfide in Ultra-low C Steels

Phase Equilibria in FeS–XS and MnS–XS (X=Ti, Nb and V) Systems

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