Über die Entstehung von Tonerdeaufwachsungen im Tauchausguß beim Stranggießen von Stahl

Hauck, Federico; Maas, Wolfgang; Pötschke, Jürgen

doi:10.1002/srin.198205145

Cited by 2 publications

(1 citation statement)

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“…Investigations of nozzle deposits of Al‐killed steels with and without Ti have shown different characteristics. While accretions in Ti‐free steels mostly consist of network of coral‐shaped, dendritic, and plate‐like alumina inclusions, the structure of SEN‐deposits of Ti‐stabilized ULC seems to be more complex …”

Section: Introductionmentioning

confidence: 99%

Study on the Influence of FeTi‐Addition on the Inclusion Population in Ti‐Stabilized ULC Steels and Its Consequences for SEN‐Clogging

Dorrer

Michelic

Bernhard

et al. 2019

steel research int.

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During the continuous casting of Ti-stabilized ULC/IF steel grades clogging of the submerged entry nozzle (SEN) is frequently observed. A new statistical evaluation indicates that increasing Ti/Al-ratios in these steels lead to an increase in the occurrence of clogging and its intensity. Investigations of samples of two TiULC heats, taken at the RH-degasser, show a remarkable increase of inclusions due to FeTi-addition. The presence of Ti-bearing alumina particles contrary to the thermodynamical expectations, indicate that their formation takes place as a consequence of FeTi-addition. Laboratoryscale experiments confirm the formation of alumina inclusions containing traces of Ti. Their size is found to be significantly smaller compared to pure alumina inclusions. Rising numbers of small inclusions within the steel are suspected to accelerate the buildup of clogging deposits. Two mechanisms are proposed to explain the formation of these particles. On the one hand ferrotitanium acts as a source of oxygen, resulting in the formation of new inclusions during dissolution. On the other hand, the modification of preexisting deoxidation products in regions with high Ti-contents may play a role.

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Section: Introductionmentioning

confidence: 99%

Study on the Influence of FeTi‐Addition on the Inclusion Population in Ti‐Stabilized ULC Steels and Its Consequences for SEN‐Clogging

Dorrer

Michelic

Bernhard

et al. 2019

steel research int.

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Clogging of graphite-containing submerged nozzles in casting of steel on a continuous casting machine

Aksel'rod¹,

Baranovskii²,

Mel'nikova³

1991

Refractories

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Broadening of the use in domestic steel plants of submerged graphite-containing nozzles in casting of various types of steel has revealed a known complication in operation of continuous casting machines related to a decrease in the through cross-section of the channel and the holes of the submerged nozzle.This process is an obstacle to long continuous casting of steel.Clogging of submerged nozzles and prevention (slowing) of this process have more than once been the subject of investigations [1][2][3][4].In a number of works [3, 5] the influence of the submerged nozzle material on formation of alumina-containing deposits has been evaluated.The processes occurring at the temperature of casting of the steel in the refractory itself taking into consideration the presence in it of a deoxidizer, carbon (graphite, coke residue of the carbon binder), have been considered.The reaction has the general form:Refractory Refractory Gaseous Products In the gaseous state AI20 and SiO diffuse into the wall of the nozzle in the direction of growth of the temperature gradient toward the surface of the nozzle channel and then into the molten metal.On the interface of the phases and close to it reactions of oxidation of the gaseous suboxides occur :in which the oxidizer is oxygen of the steel liberated as the result of the decrease in the temperature of the metal in the layer near the wall and also oxygen liberated in occurrence of the reactionOne of the most important sources of alumina inclusinos must be assumed to be products of deoxidation of the steel with aluminum and depending upon the method of deoxidation, use of ladle treatment, and casting conditions products of either primary or secondary oxidation of the components of the steel predominate in the deposits.In continuous casting of steel containing more than 0.02% aluminum clogging of the nozzle channel occurs as the result of the aluminate deposit on its walls.Small amounts of Ca impurity form with the alumina type CaO.6AI203 hard refractory inclusions with a melting point above 1800~[6].The process of precipitation of oxides is promoted by the presence of irregularities on the inner surface of the submerged nozzle channel.Obviously a certain contribution to the process is made by the hydraulics of flow of metal through the channel of the submerged nozzle.Two features must be emphasized. In the first in the near-wall layer of the liquid (in the given case molten metal) the rate of flow is significantly less than along the axis of the channel while in the second in certain situations (condition of the tundish nozzle, conditions of stopping and shutting off the steel tapping hole) an eddy effect may occur in the stream of metal, especially in the lower portion of the nozzle in the zone of the holes.

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Über die Entstehung von Tonerdeaufwachsungen im Tauchausguß beim Stranggießen von Stahl

Abstract: Bisherige Vorstellungen. Gravimetrische und elektrochemische Untersuchung der Reaktionen zwischen Tauchausgußmaterial und Eisenschmelzen im Laborversuch. Aussagen über den Bildungsmechanismus der Oberflächenschicht. Einflußgrößen.

Cited by 2 publications

References 1 publication

Study on the Influence of FeTi‐Addition on the Inclusion Population in Ti‐Stabilized ULC Steels and Its Consequences for SEN‐Clogging

Study on the Influence of FeTi‐Addition on the Inclusion Population in Ti‐Stabilized ULC Steels and Its Consequences for SEN‐Clogging

Clogging of graphite-containing submerged nozzles in casting of steel on a continuous casting machine

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