Thermodynamics on Control of Inclusions Composition in Ultra-clean Steels.

Suito, Hideaki; Inoue, Ryo

doi:10.2355/isijinternational.36.528

Cited by 264 publications

(132 citation statements)

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“…72,[75][76][77][78][79] Particle growth occurs at microscales depending on the microscale phenomena of bubble attachment, turbulent collisions, 27,72,75,76 interface reactions, reoxidation, and local thermodynamics. 20,[80][81][82][83] Finally, inclusion transport and removal at the slag or by bubble flotation 24,26,84,85 and particle entrapment in solidifying dendritic interfaces [3][4][5]73 depend on flow transport and on the nature of the flow pattern and shape of the metallurgical vessel. Different nano-and microscale models have been used to predict important specific phenomena.…”

Section: -10mentioning

confidence: 99%

Nucleation, Growth, Transport, and Entrapment of Inclusions During Steel Casting

Zhang

2013

JOM

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Section: -10mentioning

confidence: 99%

Nucleation, Growth, Transport, and Entrapment of Inclusions During Steel Casting

Zhang

2013

JOM

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“…the time spent for the completion of solidification and l the dendrite arm spacing. Partition coefficients of Mn and S for each alloy were calculated in the manner proposed in the literature 29) using partition coefficients for binary alloys, 29,30) interaction parameters, [31][32][33] and initial compositions of the alloys. The sample alloys were assumed as Fe-Cr-Ni-X (XϭMn or S) alloys.…”

Section: A Comparison Of the Alloys 1-5mentioning

confidence: 99%

The Effect of Alloy Solidification Path on Sulfide Formation in Fe–Cr–Ni Alloys

et al. 2009

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Solidification and sulfide precipitation in Fe-Cr-Ni alloys were investigated. Five samples containing 0.3 wt% S and 1.5 wt% Mn were investigated and each sample chemistry was adjusted to solidify as primary austenite, primary ferrite or eutectic by tailoring the Cr and Ni contents. 355© 2009 ISIJ or g, depending on the balance between Cr and Ni contents. In the 70wt%Fe-Cr-Ni system, if Ni content is less than 10-12 wt%, the alloy will encounter the d-liquidus first and begin to form d phase when it is cooled down from the liquid state, while if Ni content exceeds 10-12 wt% it will solidify as g phase first after passing the g-liquidus during cooling. 8,10,16) At this stage of solidification, the partition of Fe, Cr and Ni between the liquid and the primary solid phase is dependent on the slope of liquidus surface; i.e., the primary solid phase is rich in Fe and the remained liquid is rich in Cr and Ni. 6,8,15) In the region where Ni content lies between 10-12 wt%, the remaining liquid undergoes a eutectic reaction at the latter stage of solidification where the three phases coexist. When the liquid composition reaches a eutectic valley, partitions of solute elements in d and g phases will occur through eutectic reaction; i.e., d phase is rich in Cr and g phase rich in Ni. In summary, as a result of a specific solidification path along which an alloy undergoes, significant partitioning of alloying elements take place. 6,8,9,11,[13][14][15]17,18) Numerous papers have been published on morphology and characterization of sulfides in steel. Among sulfides, manganese sulfide (MnS) is commonly observed and utilized in steel, especially in free machining grades, and extensive studies have been devoted to understanding the formation of MnS.19-25) When S content is small (e.g., less than 1 wt%), MnS will form either in a monotectic or a eutectic manner during solidification, depending on the amounts of other alloying elements such as C, Si and Al. 20,22) Although these elements are not constituents of sulfides, they can switch the formation process of MnS from monotectic to eutectic reaction by lowering melting temperature of the metal matrix or supplying nucleation sites for MnS, which results in the change in morphology of sulfides. 20,22) Besides this change in sulfide morphology potentially caused by these elements, solidification structures, d, g, or the mixture of d and g, can influence the sulfide morphology as well as distribution and composition because partitions of S and sulfide forming elements vary from phase to phase which has a specific solubility limit of sulfide. Since sulfide morphology, distribution and composition have a critical effect on hot crack susceptibility, it is necessary to have a basic understanding of how sulfides precipitate in different solidification modes.Several researchers carried out in-situ observation of sulfide formation using a confocal scanning laser microscope (CSLM). 26,27) In Si-killed and Al-killed steels, MnS was seen to form rapidly as a film on the surface of the interd...

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“…Many experimental studies [1][2][3][4][5][6][7][8] have been performed on MnO-Al 2 O 3 -SiO 2 inclusion systems. In addition, several thermodynamic calculations, [9][10][11][12][13][14][15][16][17] simply based on the activity of slag and interaction parameters of alloying elements (such as Mn, Si, Al and O) in steel, have been conducted in order to help control MnO-Al 2 O 3 -SiO 2 type of inclusions. However, the work reported so far has limited itself in its practical application to steel production: (1) the work has been done for limited compositional and thermal conditions which are not enough to cover conditions prevailing in actual steel production, and (2) more importantly the accuracy of the work is not high enough in many compositional and thermal conditions of the system so that a precise prediction and control of this type of inclusions are difficult to achieve.…”

Section: Introductionmentioning

confidence: 99%

“…Most previous researches focused mainly on activity-composition relations of liquid slag/inclusion and liquid steel. [9][10][11][12][13][14][15][16][17] Without simultaneous consideration of phase equilibria of an inclusion system on hand, however, thermodynamic approach will suffer its limitation for a practical application to steel production which experiences various thermal treatments such as solidification, cooling, reheating, etc.…”

Section: Introductionmentioning

confidence: 99%

Inclusions Chemistry for Mn/Si Deoxidized Steels: Thermodynamic Predictions and Experimental Confirmations

2004

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Inclusions chemistry of Mn/Si deoxidized steel was studied through both thermodynamic computation and experimental method. The computational thermodynamics has proved to provide a powerful tool for controlling inclusions and precipitates in steel. For Mn/Si deoxidized steels, important factors in determining the liquidus temperature and primary phase of the inclusions are MnO/SiO 2 ratio and Al 2 O 3 content in inclusions. Provided that no further interaction with steel matrix during cooling, inclusions having MnO/SiO 2 mass% ratio near unity and Al 2 O 3 content in the range of 10-20 mass% give low liquidus temperatures (1150-1200°C) and primary phases of MnSiO 3 and Mn 3 Al 2 Si 3 O 12 both which are soft. For the case of MnϩSiϭ1.0 in mass%, the Mn/Si ratio of 2-5 meets the above conditions. Effect of the top slag on the inclusions chemistry can be predicted with accuracy, and hence it is possible to control the inclusions chemistry through proper design of the top slag composition so that the inclusions show a low liquidus temperature and soft primary phase. As the inclusions composition gradually changes with time toward the top slag composition, the length of refining time which determines the extent of reaction with the top slag is an important factor in determining the inclusions chemistry.KEY WORDS: inclusion; Mn/Si deoxidation; metal-inclusion reaction; the CaO-MnO-SiO 2 -Al 2 O 3 system; computational thermodynamics. namic computations, a thermodynamic database for slag and inclusion, which was optimized by the present authors, [19][20][21] was used, and all calculations were performed using the FactSage thermochemical software. 22) Thermodynamic Basis-Models and Database Liquid SteelMost investigators have used interaction parameter formalism developed by Wagner 23) and extended by Sigworth and Elliot. 24) This formalism has been widely used in metallurgy to calculate activity/activity coefficients of solutes in liquid steel. Many experiments have been conducted to evaluate interaction parameters among metallic elements, O, C, S, N etc. in molten iron and are well documented in the literature. 24,25) However, it fails sometimes to reproduce experimental data, particularly for those cases of 1) a highly concentrated region or 2) containing strong deoxidizer such as Al, Ca and Mg. In order to solve these problems in a thermodynamically sound way, Pelton and Bale 26-28) developed Unified Interaction Parameter Formalism (UIPM) which modifies Wagner formalism 23,24) and Darken formalism. 29) Moreover, in order to reproduce the deoxidation phenomena when strong deoxidizing elements exist, Jung et al. 30) proposed the use of associates such as Al*O, Ca*O, Si*O etc. in molten iron with UIPM. This UIPM with associates shows excellent agreement between calculation and experiments for deoxidation phenomena in liquid steel with a few model parameters. 30) Therefore, UIPM with associates was used to describe thermodynamic properties for liquid steel. All interaction parameters required for deoxidation of Mn, ...

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Thermodynamics on Control of Inclusions Composition in Ultra-clean Steels.

Cited by 264 publications

References 0 publications

Nucleation, Growth, Transport, and Entrapment of Inclusions During Steel Casting

Nucleation, Growth, Transport, and Entrapment of Inclusions During Steel Casting

The Effect of Alloy Solidification Path on Sulfide Formation in Fe–Cr–Ni Alloys

Inclusions Chemistry for Mn/Si Deoxidized Steels: Thermodynamic Predictions and Experimental Confirmations

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