Formation Mechanism of CaS-Al2O3 Inclusions in Low Sulfur Al-Killed Steel After Calcium Treatment

Xu, Jianfei; Huang, Fuxiang; Wang, Xinhua

doi:10.1007/s11663-016-0599-8

Cited by 43 publications

(26 citation statements)

References 18 publications

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“…However, more often in more recent steels, inclusions are spherical (the result of efforts of so‐called “inclusion shape control”) as a result of good deoxidation practice which encourages a liquid film on the surface of the liquid steel. The widespread use of Ca to supplement deoxidation by Al is a good example relying on the generation of a low‐melting point eutectic between the oxides alumina and calcia . Thus, the turbulent pouring does not result in bifilm cracks but in the formation of a scattered size range of spherical slag droplets.…”

Section: Discussionmentioning

confidence: 99%

“…">1.At steel casting temperatures, the oxide film may be liquid. This is the case for carbon steels which have been deoxidized with the correct proportions of Al and Ca, because the Al 2 O 3 and CaO oxides form a eutectic with a melting point of only about 1400° C . When these oxidized surfaces impinge during turbulent transfers, the liquid‐to‐liquid impingement simply mutually assimilates, forming droplets which quickly float out.…”

Section: Introductionmentioning

confidence: 99%

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Melting, Remelting, and Casting for Clean Steel

Campbell

2016

steel research int.

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The control of the metallurgy of steels is now highly developed. This is in contrast to the casting techniques for steels. Although continuous casting is generally conducted well, current ingot casting techniques are poor, unnecessarily introducing masses of oxides. For some steel compositions, double oxide films, bifilms, are entrained. This mechanism, occurring naturally during pouring, but till now generally overlooked, appears to be capable of explaining most of the features of steel defects in all their forms. For most Ni alloys and some steels it appears capable of generating a dense population of cracks, greatly impairing subsequent mechanical working and even final properties. In other steels the effects are much less severe. The techniques to avoid this damage to liquid steels and Ni alloys are described, including contact pouring, and naturally pressurized filling system designs. An ultimate system is counter gravity casting. For remelting processes, the risks of unreliability because of cracks intrinsic to VIM and VAR are discussed for both shop floor production and laboratory research. The potential crack‐free properties of ESR when correctly made are recommended. Even so, remelting processes might constitute an unnecessary luxury if steels and Ni alloys were cast to avoid the entrainment of oxides.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Melting, Remelting, and Casting for Clean Steel

Campbell

2016

steel research int.

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“…The elimination of inclusions in steel is the use of appropriate technology in the steelmaking process to remove inclusions from the liquid steel, and the main technologies include gas stirring [5][6][7], electromagnetic purification [8,9], slag washing [10], and filter technique [11]. The methods of inclusions modification include calcium (Ca) treatment [12][13][14][15], magnesium (Mg) treatment [16][17][18], calcium-magnesium treatment [19,20], and so on. Zhang et al [16,17] reported that Mg has very strong thermodynamic affinities with oxygen and sulfur, and magnesia inclusions present a poor agglomeration character than alumina inclusions.…”

Section: Introductionmentioning

confidence: 99%

Effect of adding yttrium on precipitation behaviors of inclusions in E690 ultra high strength offshore platform steel

Yang

et al. 2020

High Temperature Materials and Processes

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The mechanism of inclusions precipitation of the E690 offshore platform steel, with and without addition of yttrium, was studied using the thermodynamic calculation method. The results show that in the E690 steel in the absence of yttrium, the MnS inclusions were precipitated in the liquid phase at the solidification front. By adding the yttrium, MnS inclusions were replaced by spindle and spherical yttrium-containing oxide and sulfide complex inclusions, and the precipitation sequence of yttrium-containing inclusions in the liquid steel was Y2O3, Y2O2S, and YS. However, Y2S3 inclusions cannot be precipitated in the liquid steel under the experimental conditions. It was also found that Al2O3 inclusions can be formed in the liquid steel with and without addition of yttrium. The thermodynamic calculation results are in accordance with the experimental results.

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“…8) The type, morphology and size of inclusions after Ca treatment are related to the Ca content of steel. 9) In the production process of consumable electrode, Ca treatment is used commonly to obtain high purity consumable electrode, meanwhile, most of the inclusions can be controlled in the low-melting-temperature region ( < 1 873 K) after Ca treatment. It has been demonstrated that the types of inclusions in consumable electrode is one of the reason for affecting the inclusions in remelted ingot, because the original inclusions in electrode can hardly be eliminated completely through ESR process.…”

Section: Introductionmentioning

confidence: 99%

Formation and Evolution of Non-Metallic Inclusions in Calcium Treatment H13 Steel during Electroslag Remelting Process

Wang

Shi

et al. 2019

ISIJ Int.

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In the current study, the evolution of inclusions in H13 steel electrode with different Ca content refined through ESR process were analyzed, the formation and evolution of sulfide and oxide inclusions during ESR process was determined based on experiments and thermodynamic calculation. The results showed: The inclusions of remelted ingot were Al 2 O 3 , CaO-Al 2 O 3-CaS and CaO-Al 2 O 3-MgO-CaS, more than half of the total inclusions were smaller than 3 μm. The cleanliness and inclusions of remelted ingot had no difference with different Ca content in electrode. MnS inclusions in electrode precipitated while the solid fraction reached 0.98. MnS inclusions cannot precipitate due to the low level of S content in remelted ingot and the decrease of Mn and S segregation on the front edge of solidified shell. The low-meltingtemperature inclusions were dissolved and disappeared completely before liquid metal droplets collected in the liquid metal pool. The different of local cooling intensity during ESR process and high Al 2 O 3 content of liquid inclusion in molten pool promoted the formation of large amount of tiny Al 2 O 3 inclusions in remelted ingot.

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Formation Mechanism of CaS-Al2O3 Inclusions in Low Sulfur Al-Killed Steel After Calcium Treatment

Cited by 43 publications

References 18 publications

Melting, Remelting, and Casting for Clean Steel

Melting, Remelting, and Casting for Clean Steel

Effect of adding yttrium on precipitation behaviors of inclusions in E690 ultra high strength offshore platform steel

Formation and Evolution of Non-Metallic Inclusions in Calcium Treatment H13 Steel during Electroslag Remelting Process

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