The Origin of MgO Type Inclusion in High Carbon Steel

Matsuno, Hidetoshi; Kikuchi, Yoshiteru

doi:10.2355/tetsutohagane1955.88.1_48

Cited by 21 publications

(18 citation statements)

References 5 publications

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“…In iron, extensive work has been made to create the stability diagrams of oxide inclusions corresponding to Mg and Al contents using the thermodynamic data experimentally obtained. [6][7][8] It has been proved that very small amounts of Mg and Al enable the formation of spinel.…”

Section: Introductionmentioning

confidence: 99%

Effect of Silica in Slag on Inclusion Compositions in 304 Stainless Steel Deoxidized with Aluminum

2004

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Experiments were carried out to determine the effect of silica in the slag of CaO-SiO 2 -Al 2 O 3 -MgO-F system on the formation of MgO · Al 2 O 3 spinel inclusion in 304 stainless steel deoxidized with Al. Immediately after the addition of Al into the molten steel, alumina clusters formed. Simultaneously, reduction of MgO in the slag occurred to raise Mg content in the steel. This resulted in the change in inclusion composition to MgO · Al 2 O 3 spinel which did not further change. In the previous experiments with CaO-Al 2 O 3 -MgO-F slag, however, spinel inclusions changed to MgO or liquid CaO-Al 2 O 3 -MgO system. The difference in behavior was caused by the existence of silica in the slag. Silica in the slag was considered to prevent the extensive reduction of MgO or CaO in the slag by Al to supply soluble Mg or Ca into the molten steel. A stability diagram of inclusions corresponding to Mg and Al contents in the steel was calculated employing available thermodynamic data. The inclusion compositions experimentally obtained well agreed with the diagram. This implies that spinel inclusions were the most stable in the molten 304 stainless steel deoxidized with Al under the presence of 10 mass% silica in the slag. As a result, it was concluded that silica in the slag enhanced the formation of spinel inclusions.

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Section: Introductionmentioning

confidence: 99%

Effect of Silica in Slag on Inclusion Compositions in 304 Stainless Steel Deoxidized with Aluminum

2004

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“…Wanibe et al 2) studied the reaction between molten iron and MgO crucible and deduced that the dissolution of Mg from the refractory occurs through a change in O content. Ito et al 3) and Matsuno et al 1) measured the inclusion composition of Al-deoxidized steel melted in a MgO-type crucible. According to their experimental results, Mg dissolved in the molten steel, and a MgO·Al2O3 spinel-type inclusion formed.…”

Section: Introductionmentioning

confidence: 99%

Dissolution Behavior of Mg from MgO into Molten Steel Deoxidized by Al

et al. 2014

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The formation of MgO·Al2O3 spinel-type inclusions has often been reported even when Mg is not added during treatment. Many researchers have investigated the dissolution behavior of Mg from slag; however, studies on the reaction between molten steel and MgO-type refractory are limited. In this paper, the inclusion composition of Al-deoxidized steel melted in a MgO crucible, and mass transfer rates of Mg from a MgO rod and MgO in slag to Al-deoxidized molten steel were investigated. These studies clarified that Mg dissolved in the molten steel and the spinel formed not only with the reaction of molten steel and slag but also with the reaction of molten steel and MgO crucible. The dissolution rate of Mg from MgO rod increased as the rotation rate and Al content in steel increased. The MgO·Al2O3 spinel layer formed at the interface between the metal and MgO rod. The Mg content was higher for the reaction between molten steel and MgO in slag compared to the reaction between molten steel and MgO rods, as it equilibrated with MgO activity in slag.

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“…With holding Al killed steel in an MgO crucible by use of CaO-Al 2 O 3 -MgO flux, Matsuno et al 5) discovered that the MgO type inclusion in high carbon steel was generated not only from reduction of the flux but also from reduction of the MgO crucible. After industrial experiment studies of the impact of ladle age on the formation of inclusions in steel using the ladles with carbon bearing MgO lining, Du et al 6,7) concluded that the ladle glaze was the major source of inclusions in the melt, and MgO inclusion could be formed in steel by slag-refractory lining reactions.…”

Section: Introductionmentioning

confidence: 99%

Behavior of Inclusions in Deoxidation Process of Molten Steel with <i>in Situ</i> Produced Mg Vapor

2007

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In the deoxidation process of molten steel with magnesium vapor produced in situ by aluminothermic reduction of magnesium oxide, the formed inclusions are usually small in size and of spherical shape. They tend not to aggregate and form cluster. The MgO content in the inclusions decreases, while the SiO 2 content increases with the progress of experiment. Larger inclusions are removed by floating up with the rising bubbles more easily and the fine inclusions tend to remain in the melt. The oxygen concentrations originated from the inclusions can be reasonably explained from the experimental analysis ones.By use of the MgO porous immersion tube, deoxidation proceeds slowly at the initial stage, but it continues until the later stage of experiment, in contrast to that using the dense Al 2 O 3 immersion tube. The formed inclusion number per unit area has a larger value than that with the dense Al 2 O 3 tube. The number of inclusions also increases with increasing the initial oxygen concentration and dividing pellets charging into several portions. When the carrier gas flow rate is large, the number of inclusions tends to increase at the later stage of experiment due to the strong involvement of inclusions from the melt surface into the melt.In the present deoxidation process, it is considered that the rapid removal of larger inclusions by rising bubbles is beneficial to produce high cleanness steel, while the remaining fine inclusions is helpful for the grain refinement of steel during the solidification and phase transformation process.KEY WORDS: deoxidation; magnesium vapor; pellet; magnesia; aluminothermic reduction; inclusion; clean steel; grain refinement. ISIJ International, Vol. 47 (2007), No. 5, © 2007 ISIJ crostructural control of steel in recent years. On the basis of in-situ observation of inclusions on the molten steel surface with a confocal scanning laser microscope, the attractive force between a pair of MgO inclusions was found to be one-tenth of that between a pair of alumina inclusions so that MgO inclusions had a much weaker tendency to aggregate or to form clusters. 17) The grain growth of Fe-10mass%Ni alloy was strongly inhibited by the primary inclusions of MgO particles, which were evenly distributed in the alloy after Mg deoxidation. 18) With using Fe-10mass%Ni alloy, Suito et al. systematically examined the dispersion of fine primary MgO inclusions, 19) studied the characteristics of size distribution of MgO particles 20) and the dispersion behavior of deoxidation particles of MgO during solidification, 21) furthermore, clarified the effect of primary deoxidation products of MgO on precipitation of TiN 22) and MnS 23) in the alloy. The effect of size distribution of MgO particles on austenite grain growth in Fe-0.05mass%C alloy was also investigated. 24) The purpose of present work is to study the behavior of the primary inclusions in deoxidation process of molten steel with magnesium vapor produced in situ by aluminothermic reduction of magnesium oxide. The produced magnesium vapor was i...

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The Origin of MgO Type Inclusion in High Carbon Steel

Cited by 21 publications

References 5 publications

Effect of Silica in Slag on Inclusion Compositions in 304 Stainless Steel Deoxidized with Aluminum

Effect of Silica in Slag on Inclusion Compositions in 304 Stainless Steel Deoxidized with Aluminum

Dissolution Behavior of Mg from MgO into Molten Steel Deoxidized by Al

Behavior of Inclusions in Deoxidation Process of Molten Steel with <i>in Situ</i> Produced Mg Vapor

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