Morphology of Sulfide Formed in the Fe-Cr-S Ternary Alloys.

Mitsui, Hajime; Oikawa, Katsunari; Ohnuma, Ikuo; Kainuma, Ryosuke; Ishida, K.

doi:10.2355/isijinternational.42.1297

Cited by 19 publications

(15 citation statements)

References 22 publications

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“…The occurrence of the morphology change of MnS in steels was shown to relate with the metastable monotectic reaction and stable eutectic reaction forming the liquid and solid sulfides, respectively. Similar results were also obtained in other alloys such as Fe-Cr alloys 13,14) and Cu alloys. 15) Ti, Nb and V are commonly used as alloying elements in steels to improve the material properties.…”

Section: Introductionsupporting

confidence: 76%

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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Section: Introductionsupporting

confidence: 76%

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

et al. 2009

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“…MnS is generally generated from the residual liquid steel with the enrichment of manganese and sulfur during the solidification procedure. Mathematical modeling is an important tool to investigate the formation of MnS, and several models have been proposed and developed to describe the formation process of MnS by previous studies [11][12][13][14][15][16][17]. In this paper, the direct observation of precipita-tion process of sulfides during solidification was investigated by using a high-temperature confocal laser scanning microscope.…”

Section: Introductionmentioning

confidence: 99%

Study of manganese sulfide precipitation in medium sulfur, non-quenched and tempered steel via experiments and thermodynamic calculation

Liu

et al. 2018

Metall. Res. Technol.

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In this study, the precipitation behavior of MnS was calculated during the solidification process of the medium sulfur, non-quenched and tempered 49 MnVS steel. And the precipitation process was directly observed by a high-temperature confocal laser scanning microscope (HT-CLSM) equipped with a gold-image furnace. Besides, the precipitated particles were proved to be MnS by using the Scanning Electron Microscope-Energy Dispersive spectroscopy (SEM-EDS) analysis. The modified thermodynamic calculation indicated that the MnS precipitated from the residual liquid steel when the product of manganese and sulfur concentrations exceeded the equilibrium value at 1417.0 °C. Meanwhile, the results calculated by FactSage software shown that the beginning precipitation temperature of MnS is about 1411.0 °C. The observation of HT-CLSM demonstrated that the primary solid on the free surface of the liquid steel was visualized at 1485.0 °C during the solidification process (cooled from 1520.0 °C to room temperature with a rate of −30 °C/min). Then, the MnS particles started to form at 1437.0 °C and rapidly grew up into shape on the solid-liquid boundary. And the precipitation of MnS continued to form in a large amount (90% of the total) in the next 10 degrees. The enrichment of Mn and S near the local melt surface may be conducive the MnS formation, which results a higher actual precipitation temperature than the calculated value.

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“…It is well known for these steels that inclusions of S enhance the precipitation of several sulfides and carbosulfide, such as NiAs-type TiS, NaCltype MnS, and Ti 4 C 2 S 2 ; hence, controlling the behavior of these precipitates plays a key role in determining the mechanical properties of the steels. [1][2][3][4][5][6][7][8][9][10][11][12] However, because of experimental difficulty in detecting small concentration of C and S in IF steels, the thermodynamic properties of these precipitates have remained unclear. In particular, discrepancies among the reported thermodynamic stabilities for the Ti 4 C 2 S 2 3,4,[6][7][8][9][10]12) have been found according to a variety of chemical compositions, temperatures, and experimental methods.…”

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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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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Morphology of Sulfide Formed in the Fe-Cr-S Ternary Alloys.

Cited by 19 publications

References 22 publications

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

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

Study of manganese sulfide precipitation in medium sulfur, non-quenched and tempered steel via experiments and thermodynamic calculation

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

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