Effect of S Content on the MnS Precipitation in Steel with Oxide Nuclei.

Wakoh, Masamitsu; Sawai, Takashi; Mizoguchi, Shozo

doi:10.2355/isijinternational.36.1014

Cited by 132 publications

(79 citation statements)

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“…Control of microstructure through such technique has been termed as 'Oxides Metallurgy', and has become one of the active areas of research in Inclusion Engineering in recent years. 3,4) Precise evaluation of inclusion formation during solidification calls for the solution of a combination of microsegregation and thermodynamic models. Several studies have been reported in literature.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Model for Prediction of Composition of Inclusions Formed during Solidification of Liquid Steel

2009

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Section: Introductionmentioning

confidence: 99%

Mathematical Model for Prediction of Composition of Inclusions Formed during Solidification of Liquid Steel

2009

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“…In particular, MnS precipitation in association with oxides has been noted due to the synergetic effect of the Mn-depleted zone created in the vicinity of the inclusions to promote the potency of inclusions. [20][21][22][23][24] However, there is still a lack of understanding about the nature of inclusions in steels, which is essential to elucidating the heterogeneous nucleation mechanisms of ferrite from inclusions. For the effective utilization of inclusions, the nature of inclusions in steels has to be exploited in a quantitative way during steel making processes.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Size, Composition, and Morphology of Primary and Secondary Inclusions in Si/Mn and Si/Mn/Ti Deoxidized Steels.

Kim

Lee

2002

ISIJ International

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Primary and secondary inclusions in Si/Mn and Si/Mn/Ti deoxidized structural steels subjected to different thermal histories were investigated in view of evolution of size, composition, and morphology. Primary inclusions quenched from 1 600°C contained very low levels of sulfur, and hence MnS precipitation on them was hardly found. The mean diameter of secondary inclusions lied in the range of 1-3 mm depending on the cooling rate and chemical compositions of steels. Both MnO and MnS content were higher in smaller secondary inclusions. MnS which precipitated on manganese silicate inclusions in Si/Mn deoxidized steels mostly grew into the inclusions. As inclusion size increased, the number of MnS precipitates on each inclusion was also increased. Titanium in steel had a tendency to reduce SiO 2 content in inclusions and to associate with MnO in the inclusions to form a stoichiometric relationship of Mn/Ti ratio in the inclusions. If Ti content in Si/Mn/Ti deoxidized steels was low, the secondary inclusions were found to form with multiple phases; viz., manganese silicate phase, Mn-Ti oxide phase, and MnS phase. The MnS phase always precipitated in the manganese silicate phase. The proportion of manganese silicate phase in each inclusion decreased with a corresponding increase in Ti content in the steel, and eventually disappeared completely when the Ti content exceeded a certain level (70 ppm in the present steel compositions). In this case MnS was found to precipitate outside Mn-Ti oxide inclusions and grew into the steel matrix. In order to interpret and predict the behavior of inclusion precipitation and growth, a model has been developed which incorporates both thermodynamic and kinetic considerations.

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“…On the other hand, Wakoh has investigated the effect of sulfur content on the MnS precipitation with oxide nuclei in steel deoxidated by Mn-Si, Mn-Ti, Al and Zr, respectively. 23) It is found that the precipitation ratio of MnS on oxide is large in almost all oxides when the content of sulfur is higher than 0.01 mass% in steel. The present precipitation of Cu x S on pure silicon oxide may be also that case.…”

Section: Analysis Methodsmentioning

confidence: 99%

Isothermal Precipitation Behavior of Copper Sulfide in Ultra Low Carbon Steel

2007

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Copper and sulfur are typical residual elements or impurity elements in steel. Sufficient removal of them during steelmaking process is difficult for copper and costly for sulfur. Utilization of copper and sulfur in steel, especially in steel scrap, has been an important issue for a long period for metallurgists.Copper and sulfur may combine to form a copper sulfide, which may provide a prospect to avoid the detrimental effects of copper and sulfur in steel. Unfortunately the formation mechanism of a copper sulfide in steel has not been completely clarified so far. In the present paper, solution treatment of samples containing copper and sulfur are firstly performed at 1 623 K for 2.7ϫ10 3 s followed by quenching into water. The samples are then isothermally heat-treated at 673 K, 873 K, 1 073 K, 1 273 K and 1 373 K for different time followed by quenching into water again. The size, morphology, constituent and crystallography of sulfide precipitates in these samples are investigated by SEM and TEM equipped with EDS. Fine copper sulfides (less than 100 nm) are observed to co-exist with silicon oxide in samples even isothermally heattreated at 1 373 K for 1.44ϫ10 4 s; Film-like copper sulfides are generally observed to co-exist with iron sulfide in all samples; Plate-like copper sulfides are observed especially in sample isothermally heat-treated at 1 073 K for 1.44ϫ10 4 s. The formation mechanisms of these copper sulfides have been discussed in detail.KEY WORDS: copper sulfide; isothermal precipitation; morphology; crystallography; ultra low carbon steel.up to 780 K at 36.60 at% S and down to 345 K at 35.65 at% S. Therefore, the high Digenite is the most probable phase that is expected in steel at high temperature. But people have confusedly presumed and reported several crystal structures and phases, 11,[13][14][15]20) for example cubic Cu 1.8 S or Cu 1.6 S or CuS 2 , hexagonal CuS and rhombohedral Cu 1.6 S and so on, for copper sulfide in steel.In the previous papers, 5,6,8) the authors found that copper sulfides could be formed in strip casting steel. Differently from the formerly reported copper sulfides in steel/ iron, [10][11][12][13][14][15] which usually coexisted with MnS, almost pure copper sulfides with various morphologies were found in the previous strip casting steels. In the present paper, the formation mechanism such as precipitation temperature, stability and crystallography of various copper sulfides have been investigated during isothermal heat treatment process. Experimental Procedures Materials and Heat Treatment ConditionsThe chemical composition of the present steel is shown in Table 2. The steel is firstly prepared in an induction heating furnace under flowing argon gas. About 350 g of electrolytic iron is melted at 1 873 K. After the alloying elements (Cu, S) are added to the melted iron, the melt is cooled to room temperature with the furnace. An ingot with size of f40ϫH50 mm (hereafter named as sample H00) then could be obtained for the following heat treatment.The solution treatment o...

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Effect of S Content on the MnS Precipitation in Steel with Oxide Nuclei.

Cited by 132 publications

References 1 publication

Mathematical Model for Prediction of Composition of Inclusions Formed during Solidification of Liquid Steel

Mathematical Model for Prediction of Composition of Inclusions Formed during Solidification of Liquid Steel

Evolution of Size, Composition, and Morphology of Primary and Secondary Inclusions in Si/Mn and Si/Mn/Ti Deoxidized Steels.

Isothermal Precipitation Behavior of Copper Sulfide in Ultra Low Carbon Steel

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