Factors to Determine Inclusion Compositions in Molten Steel during the Secondary Refining Process of Case-Hardening Steel

Yoshioka, Takanori; Nakahata, Kenichiro; Kawamura, Takanori; Ohba, Yasuhide

doi:10.2355/isijinternational.isijint-2016-324

Cited by 43 publications

(65 citation statements)

References 33 publications

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“…Note that before LF refining, the Ca content is significantly low, while the Mg content is even around 40 times higher than Ca. The increase trend in Table 3 is in line with our previous study 7) and the results of Yang et al 1) and Shin et al,17) while in the results of Yoshioka et al 4) the decrease of Mg and Ca has been seen after RH treatment. This difference might be related to the different experimental conditions.…”

Section: Composition Of Industrial Steel Samplessupporting

confidence: 82%

“…In the figure, alumina is observed in the Sample 1 though plotted in the In Table 3, a trace of dissolved Ca is formed during the refining process in the present study, and some calcium aluminate inclusions (Type 6 and Type 7) are found after LF refining and VD treatment. Many studies 1,2,4,6,17) pointed out that MgO·Al 2 O 3 spinel inclusions are not stable and would transform into calcium aluminate inclusions, when there is a trace of dissolved Ca in liquid steel. Note that these study results are mainly based on conventional Al-killed steel grades.…”

Section: Evolution Of Inclusions In Medium Mn Steelmentioning

confidence: 99%

“…Additionally, Todoroki et al 16) and Wang et al 20) also proposed SiO 2 in slag would hinder the formation of MgO·Al 2 O 3 inclusions. Moreover, many researchers [2][3][4][5][6][7] believed that when a trace of dissolved Ca is formed in liquid steel, the MgO·Al 2 O 3 inclusions in steel are not stable, and could be easily modified into CaO-MgO-Al 2 O 3 inclusions and even CaO-Al 2 O 3 with a low melting temperature.…”

Section: Introductionmentioning

confidence: 99%

“…In order to control these inclusions, a lot of researchers [1][2][3][4] have studied the formation and evolution mechanism of MgO·Al 2 O 3 spinel inclusions in steel. Some of them [7][8][9][10]12,21,29) thought that the formation of MgO·Al 2 O 3 spinel inclusions depends on the concentration of dissolved Mg, Al and O in liquid steel.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] Due to their high hardness and irregular shape, this kind of inclusions tend to induce microcosmic cracks and lead to fatigue failure of final product, and they are usually considered as harmful inclusions for steel.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Formation and Evolution of Non-metallic Inclusions in Medium Mn Steel during Secondary Refining Process

2017

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Section: Composition Of Industrial Steel Samplessupporting

confidence: 82%

Section: Evolution Of Inclusions In Medium Mn Steelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Formation and Evolution of Non-metallic Inclusions in Medium Mn Steel during Secondary Refining Process

2017

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Effects of Refractory and Ladle Glaze on Evolution of Non‐Metallic Inclusions in Al‐Killed Steel

Guang

Deng

Zhu

2017

steel research int.

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Laboratory experiments are carried out to study the effects of different refractories (Al 2 O 3 refractory, MgO refractory, and glazed Al 2 O 3 refractory) on the formation of spinel inclusions and calcium aluminate inclusions. The results show that Al 2 O 3 refractory has almost no influence on the inclusions in Al-killed steel, while MgO refractory and glazed Al 2 O 3 refractory can help the formation of spinel inclusions from alumina inclusions. Meanwhile, glazed Al 2 O 3 refractory can also contribute to the transformation of spinel inclusions into calcium aluminate inclusions. In contrast to ladle glaze, MgO refractory could supply more dissolved Mg to liquid steel. The formation of dissolved Mg and Ca holds the key for the evolution sequence of alumina, and spinel inclusions form earlier than calcium aluminate inclusions due to the faster formation of dissolved Mg. Besides, ladle glaze can also be a source of calcium aluminate inclusions.

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Mechanism of a CaS Formation in an Al-Killed High-S Containing Steel during a Secondary Refining Process without a Ca-Treatment

Yoshioka¹,

Shimamura²,

Karasev

et al. 2017

steel research int.

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A study is carried out to understand the CaS formation mechanism in an Al-killed high-S containing steel during the secondary refining process without a Ca-treatment. At the initial stage of the LF refining, CaS is formed on existing inclusions by the reaction between Ca and S due to the high S activity before the desulfurization. As the desulfurization progresses, the CaS phase changes into a CaO phase due to the decrease of the CaS stability. Since this composition change takes a long time due to the difficulty of a fast mass diffusion in the solid phase, it cannot be complete during the LF refining. During the following RH treatment, an FeS addition increases the activity of S, which reacts with the CaO in the inclusions to form a CaS phase. At the same time, the CaS phase is formed by the reaction between Ca and S. Consequently, the majority of the inclusions end up as an Al 2 O 3 þ CaS phase. The CaS formation behavior during the secondary refining process without a Ca-treatment obeys the thermodynamic driving forces with respect to two reactions: one is the reaction between CaO in inclusions and S and the other is the reaction between Ca and S.

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Factors to Determine Inclusion Compositions in Molten Steel during the Secondary Refining Process of Case-Hardening Steel

Cited by 43 publications

References 33 publications

Formation and Evolution of Non-metallic Inclusions in Medium Mn Steel during Secondary Refining Process

Formation and Evolution of Non-metallic Inclusions in Medium Mn Steel during Secondary Refining Process

Effects of Refractory and Ladle Glaze on Evolution of Non‐Metallic Inclusions in Al‐Killed Steel

Mechanism of a CaS Formation in an Al-Killed High-S Containing Steel during a Secondary Refining Process without a Ca-Treatment

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