WO2013190594A1 - Buse à entrée submergée pour permettre une coulée continue et procédé de coulée continue qui utilise cette dernière - Google Patents

Buse à entrée submergée pour permettre une coulée continue et procédé de coulée continue qui utilise cette dernière Download PDF

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Publication number
WO2013190594A1
WO2013190594A1 PCT/JP2012/004001 JP2012004001W WO2013190594A1 WO 2013190594 A1 WO2013190594 A1 WO 2013190594A1 JP 2012004001 W JP2012004001 W JP 2012004001W WO 2013190594 A1 WO2013190594 A1 WO 2013190594A1
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WO
WIPO (PCT)
Prior art keywords
continuous casting
immersion nozzle
refractory
spinel
graphite
Prior art date
Application number
PCT/JP2012/004001
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English (en)
Japanese (ja)
Inventor
塚口　友一
謙治 田口
Original Assignee
新日鐵住金株式会社
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Filing date
Publication date
Application filed by 新日鐵住金株式会社 filed Critical 新日鐵住金株式会社
Priority to PCT/JP2012/004001 priority Critical patent/WO2013190594A1/fr
Publication of WO2013190594A1 publication Critical patent/WO2013190594A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles

Definitions

  • the present invention relates to an immersion nozzle used for continuous casting of a refractory metal such as steel, and a continuous casting method of a refractory metal using the immersion nozzle.
  • molten metal is injected from a tundish into a mold through an immersion nozzle.
  • the immersion nozzle may be clogged when a high-melting point non-metallic inclusion typified by alumina adheres to the inner surface. Clogging of the immersion nozzle is a problem that greatly affects the operation and the quality of the slab.
  • Patent Document 1 discloses a spinel-periclase-graphite refractory as a refractory constituting an immersion nozzle.
  • this refractory forms a dense inner surface by a chemical reaction at a high temperature during casting, so that inclusions in molten steel are difficult to adhere.
  • Patent Document 2 discloses a magnesia-graphite, spinel-graphite, or magnesia-spinel-graphite-based refractory containing a low melting point beryl and forming a semi-molten layer on the inner surface as a refractory constituting an immersion nozzle.
  • beryls are partly melted by contact with high-temperature molten steel, and a low melting point film is formed on the surface of the refractory, so that inclusions in the molten steel adhere to the surface of the refractory. It is said that it is hard to do.
  • the present inventors configured the inner wall of the immersion nozzle with a refractory material containing a small amount (0.5 to 7% by mass) of CaO or the like in alumina graphite.
  • a method for preventing clogging of an immersion nozzle by passing molten steel at a flow rate is proposed.
  • a semi-molten glass layer can be formed on the portion of the immersion nozzle in contact with the molten steel while ensuring fire resistance.
  • inclusions are less likely to adhere to the refractory.
  • the effect of preventing the clogging of the immersion nozzle can be improved by using energization together.
  • This invention is made
  • the subject is providing the continuous casting method using the immersion nozzle for continuous casting which can suppress the obstruction
  • the present inventors repeated experiments and considerations on the adhesion of alumina inclusions to the surface of the refractory constituting the immersion nozzle. As a result, it has been found that adhesion of alumina inclusions and precipitation of alumina inclusions from the molten metal easily occur on the surface of alumina particles which are refractory raw materials.
  • magnesia as a refractory basic material to replace alumina. Since magnesia has a high melting point (about 2800 ° C.) similar to alumina and has better wettability with molten steel than alumina, it has been considered promising as a refractory base material to replace alumina. However, it has been found that a large coefficient of thermal expansion is disadvantageous in terms of resistance to thermal shock, and it is difficult to put it to practical use. Further, even when magnesia contains a small amount of CaO, it dissolves in a solid, and a low melting point liquid phase does not occur during continuous casting. Therefore, in an immersion nozzle using magnesia, inclusions cannot be made difficult to adhere by forming a semi-molten glass layer in a portion in contact with molten steel.
  • the crystal structure is different from the corundum structure of alumina. 2. It has better wettability with molten steel than alumina. 3. Must have a sufficiently high melting point. 4).
  • the coefficient of thermal expansion is smaller than that of magnesia, and preferably about the same as that of alumina. 5.
  • a low melting point liquid phase is produced during continuous casting by containing a small amount of CaO. 6). It can be easily obtained industrially.
  • “low melting point” means about 1700 ° C. or less
  • “high melting point” means about 1900 ° C. or more.
  • a trace amount means that the content is about 5% by mass or less.
  • the present inventors selected spinel as a refractory base material that satisfies the above six points.
  • Spinel is a spinel crystal structure whose crystal structure is different from the corundum structure.
  • Spinel is a substance composed of MgO and Al 2 O 3 , and, like alumina, contains a small amount of CaO to produce a low melting point liquid phase during continuous casting. Furthermore, spinel is readily available industrially as a raw material.
  • the present inventors examined an immersion nozzle using a refractory material (spinel graphite) containing graphite and a trace amount of CaO in spinel.
  • a refractory material spinel graphite
  • spinel graphite a refractory material containing graphite and a trace amount of CaO in spinel.
  • the inner surface is in a semi-molten and smooth state, and since the turbulence of the molten steel flow that promotes the adhesion of alumina inclusions does not occur, adhesion of inclusions can be suppressed.
  • the present invention has been completed on the basis of the above examination results and knowledge, and has the gist of the following (1) continuous casting immersion nozzle and (2) and (3) continuous casting methods.
  • An immersion nozzle for continuous casting in which a spinel graphite refractory is disposed on at least an inner surface, wherein the spinel graphite refractory is mass%, C: 11 to 45%, MgO: 6 to 25%, Al 2 O 3 : A continuous casting immersion nozzle characterized by containing 40 to 80% and CaO: 1 to 7%.
  • the immersion nozzle for continuous casting of the present invention According to the immersion nozzle for continuous casting of the present invention, nozzle clogging due to inclusions in continuous casting can be suppressed. Moreover, according to the continuous casting method of this invention, the obstruction
  • FIG. 1 is a diagram showing an outline of a continuous casting apparatus to which the continuous casting method of the present invention can be applied.
  • FIG. 2 is a longitudinal sectional view of the immersion nozzle used in the test.
  • FIG. 2A shows the immersion nozzle of the present invention example in which the spinel graphite refractory containing CaO is arranged on the inner surface
  • FIG.2 (c) shows the immersion nozzle of the comparative example which used the alumina graphite for the whole except a slag line.
  • the immersion nozzle for continuous casting of the present invention has a spinel graphite refractory disposed at least on the inner surface, the spinel graphite refractory being C: 11 to 45%, MgO: 6 to 25%, Al 2 O 3 : 40-80%, CaO: 1-7%.
  • Disposing the spinel graphite refractory on at least the inner surface of the immersion nozzle means that the spinel graphite refractory is disposed on the inner surface of the immersion nozzle in contact with the molten steel.
  • An example in which a spinel graphite refractory is thus arranged is shown in FIG.
  • the immersion nozzle may be entirely composed of the above-mentioned spinel graphite refractory, not just the inner surface.
  • the spinel raw material of a spinel graphite refractory can use the spinel raw material generally used as a refractory raw material without a restriction
  • composition of spinel graphite refractory C 11-45% If the content of C (carbon), which is the main component of graphite, is less than 11%, spinel graphite is vulnerable to thermal shock. On the other hand, if it exceeds 45%, spinel graphite is vulnerable to oxidation and erosion. Therefore, the C content is defined as 11 to 45%.
  • the C content is preferably 15 to 40%.
  • MgO 6-25%
  • the MgO content is less than 6%, the composition of the spinel graphite approaches the boundary with the corundum phase region, making it difficult to maintain a stable spinel. .
  • the MgO content is too low, the excellent corrosion resistance of the spinel is impaired.
  • the MgO content exceeds 25%, the spinel graphite becomes weak against thermal shock. Therefore, the MgO content is defined as 6 to 25%.
  • the MgO content is preferably 8 to 20%.
  • CaO 1-7%
  • the CaO content is preferably 2 to 5%.
  • Al 2 O 3 40-80%
  • Al 2 O 3 is a component of spinel together with MgO, and is a main component of spinel graphite used in the immersion nozzle of the present invention. If the Al 2 O 3 content is less than 40%, the content of MgO, which is the other spinel component, becomes relatively high, so that the composition of the spinel graphite approaches the boundary with the MgO phase region and is stable. It becomes difficult to maintain the spinel. Therefore, the Al 2 O 3 content is defined as 40 to 80%.
  • the Al 2 O 3 content is preferably 51 to 70%.
  • MgO / Al 2 O 3 0.10 to 0.65
  • MgO and Al 2 O 3 which is contained in the spinel graphite MgO / Al 2 O 3 is preferably satisfies 0.10 to 0.65 in mass ratio.
  • FIG. 1 is a diagram showing an outline of a continuous casting apparatus to which the continuous casting method of the present invention can be applied.
  • the molten steel 2 is supplied from the ladle 1 to the tundish 4.
  • the molten steel 2 injected from the tundish 4 through the upper nozzle 3, the sliding gate 5 and the immersion nozzle 6 into the mold 14 from the discharge port 13 of the immersion nozzle 6 is a mold 14 and a secondary cooling spray nozzle (not shown) below the mold 14.
  • the solidified shell 15 is formed to form a slab 16 by cooling with spray water sprayed from the slab.
  • Mold powder 17 is disposed on the surface of the molten steel 2 in the mold 14.
  • a continuous casting apparatus provided with a power supply device 10 is used.
  • One end of cables 9 a and 9 b is connected to the power supply device 10.
  • the other end of the cable 9 a is connected to an electrode 7 provided on the outer periphery of the upper portion of the immersion nozzle 6, and the other end of the cable 9 b is connected to one end of the counter electrode 8.
  • the counter electrode 8 is made of alumina graphite, and the other end is immersed in the molten steel 2 in the tundish 4.
  • An insulating refractory 12 is disposed between the counter electrode 8 and the tundish 4 to ensure insulation.
  • An insulating refractory 11 is also arranged between the immersion nozzle 6 and the sliding gate 5 to ensure insulation.
  • the property of spinel graphite which is more easily wetted by molten steel than alumina graphite and hardly adheres to alumina inclusions, is improved by energization. This is because mass transfer of electrons and ions occurs at the interface between the spinel graphite and the molten steel with energization, and a so-called reaction wetting phenomenon occurs due to a chemical reaction generated along with the mass transfer.
  • the electrode 7 is used as a cathode, that is, the spinel graphite refractory is used as a cathode, and the average current density in the immersion nozzle 6 is 1 to 30 mA / cm. 2 is preferable.
  • the action of maintaining the spinel graphite by preventing the generation of CO gas due to the oxidation of the graphite constituting the spinel graphite refractory, and the oxidation of Al in the molten steel by the CO gas Al 2
  • the average current density is less than 1 mA / cm 2
  • the effect of causing mass transfer due to energization is too small, and in order to flow a large current exceeding 30 mA / cm 2 , the energization cable and power supply device are enlarged and operated. Difficulties arise.
  • the average current density in the immersion nozzle 6 is the average value of the current flowing between the immersion nozzle 6 and the molten steel 2 when a voltage is applied between the immersion nozzle 6 and the counter electrode 8 using the power supply device 10. It is the value divided by the total area of the portion of the immersion nozzle 6 that contacts the molten steel 2.
  • Test Method A continuous casting apparatus having the configuration shown in FIG. 1 was used for the continuous casting test.
  • a mold having a thickness of 0.3 m and a width of 1.2 to 1.6 m was used.
  • the composition was C: 0.05%, Si: 0.01%, sol. 1200% of aluminum killed low carbon steel with Al: 0.05% was used, and the casting speed was 2 m / min excluding the unsteady part.
  • Table 1 shows the composition of the refractory used for the immersion nozzle.
  • Each of the refractories A to C is spinel graphite containing a trace amount (2% to 4%) of CaO, and is a refractory having a composition satisfying the provisions of the present invention.
  • the refractory D is spinel graphite not containing CaO, and the refractory E is general alumina graphite, which do not satisfy the provisions of the present invention.
  • the refractory F is zirconia graphite generally used for the slag line on the outer surface of the immersion nozzle.
  • FIG. 2 is a longitudinal sectional view of the immersion nozzle used in the test.
  • FIG. 2A shows the immersion nozzle of the present invention example in which a spinel graphite refractory containing CaO is arranged on the inner surface
  • FIG. The immersion nozzle of the comparative example which arranged the spinel graphite refractory which does not contain CaO on the inner surface
  • the figure (c) shows the immersion nozzle of the comparative example which used alumina graphite for the whole except a slag line.
  • the inner surface (shaded portion) is made of refractory A
  • the slag line (horizontal line portion) is made of refractory F
  • the other portion (white portion) is made of refractory E.
  • the submerged nozzle shown in FIG. 5B has the same configuration as the submerged nozzle shown in FIG. 5A except that the inner surface (black portion) is made of refractory D.
  • the slag line (horizontal line portion) is composed of the refractory F
  • the other portion (white portion) is composed of the refractory E.
  • Test numbers 1 to 3 are examples of the present invention using an immersion nozzle of the type shown in FIG. In Test No. 1, no current was supplied between the immersion nozzle and the molten steel. In Test No. 2, energization was performed with an immersion nozzle as an anode and an average current density of 10 mA / cm 2 . In test number 3, the immersion nozzle was used as the cathode, and the current was supplied with an average current density of 10 mA / cm 2 .
  • Test No. 4 is an immersion nozzle of the type shown in FIG. 5B and Test No. 5 is a comparative example using an immersion nozzle of the type shown in FIG. Did not do.
  • Test results Table 2 shows the average thickness of the deposit on the inner surface of the immersion nozzle as an evaluation item, together with the test conditions.
  • the thickness of the deposit was measured at an immersion nozzle after 1200 t of molten steel passed continuously.
  • the measurement range of the thickness of the deposit is a section from the upper end of the immersion nozzle to 620 mm, and the average thickness in this range is calculated as the average thickness of the deposit. did.
  • test number 1 which is an example of the present invention
  • test numbers 4 and 5 which are comparative examples. From this, it can be seen that the immersion nozzle using the spinel graphite refractory having the composition defined in the present invention can suppress the adhesion of inclusions mainly composed of alumina.
  • spinel graphite refractory was used on the inner surface of the immersion nozzle, it did not contain CaO, and therefore the effect of suppressing the adhesion of inclusions was smaller than that of Test No. 1.
  • Test No. 5 since alumina graphite was used on the inner surface of the immersion nozzle, inclusions were most easily adhered.
  • the present inventors similarly obtain the effect of suppressing the adhesion of inclusions when refractory B or C is used instead of refractory A. I confirmed that.
  • the immersion nozzle for continuous casting of the present invention it is possible to suppress clogging due to inclusions in continuous casting. Moreover, according to the continuous casting method of this invention, the obstruction

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)

Abstract

La présente invention se rapporte à une buse à entrée submergée pour permettre une coulée continue qui comporte du graphite recouvert de spinelle de grade réfractaire au moins sur la surface interne de cette dernière, ladite buse étant caractérisée en ce que le graphite recouvert de spinelle de grade réfractaire contient, en % en masse, une quantité de carbone (C) comprise entre 11 et 45 %, une quantité d'oxyde de magnésium (MgO) comprise entre 6 et 25 %, une quantité d'oxyde d'aluminium (Al2O3) comprise entre 40 et 80 % et une quantité d'oxyde de calcium (CaO) comprise entre 1 et 7 %. Le procédé de coulée continue pour des brames, selon lequel le métal en fusion est versé dans un moule à l'aide de la buse à entrée submergée pour permettre une coulée continue, est caractérisé en ce qu'une électrode est agencée sur la buse à entrée submergée pour permettre une coulée continue et la coulée est effectuée tout en faisant passer un courant électrique dans le métal en fusion à travers le graphite recouvert de spinelle de grade réfractaire. La fabrication de la cathode avec le graphite recouvert de spinelle de grade réfractaire, l'immersion de la contre-électrode anodique dans le métal en fusion et l'obtention d'une valeur de densité de courant moyenne pendant l'électrification comprise entre 1 et 30 mA/cm2 constituent des faits favorables. Ladite buse à entrée submergée pour permettre une coulée continue et le procédé de coulée continue qui utilise ladite buse à entrée submergée peuvent limiter le blocage de la buse à entrée submergée pendant une coulée continue.
PCT/JP2012/004001 2012-06-20 2012-06-20 Buse à entrée submergée pour permettre une coulée continue et procédé de coulée continue qui utilise cette dernière WO2013190594A1 (fr)

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PCT/JP2012/004001 WO2013190594A1 (fr) 2012-06-20 2012-06-20 Buse à entrée submergée pour permettre une coulée continue et procédé de coulée continue qui utilise cette dernière

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PCT/JP2012/004001 WO2013190594A1 (fr) 2012-06-20 2012-06-20 Buse à entrée submergée pour permettre une coulée continue et procédé de coulée continue qui utilise cette dernière

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3381587A4 (fr) * 2015-11-27 2018-10-03 Posco Busette de coulée, dispositif de coulée et procédé de coulée
CN113523262A (zh) * 2020-04-17 2021-10-22 宝山钢铁股份有限公司 防堵塞浸入式水口

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000263200A (ja) * 1999-03-18 2000-09-26 Shinagawa Refract Co Ltd 連続鋳造用浸漬ノズル
JP2004268142A (ja) * 2003-02-17 2004-09-30 Jfe Steel Kk 鋼の連続鋳造用浸漬ノズル
JP2004268143A (ja) * 2003-02-17 2004-09-30 Jfe Steel Kk 鋼の連続鋳造用浸漬ノズル
JP2010201504A (ja) * 2009-02-09 2010-09-16 Sumitomo Metal Ind Ltd 鋼の連続鋳造方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000263200A (ja) * 1999-03-18 2000-09-26 Shinagawa Refract Co Ltd 連続鋳造用浸漬ノズル
JP2004268142A (ja) * 2003-02-17 2004-09-30 Jfe Steel Kk 鋼の連続鋳造用浸漬ノズル
JP2004268143A (ja) * 2003-02-17 2004-09-30 Jfe Steel Kk 鋼の連続鋳造用浸漬ノズル
JP2010201504A (ja) * 2009-02-09 2010-09-16 Sumitomo Metal Ind Ltd 鋼の連続鋳造方法

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3381587A4 (fr) * 2015-11-27 2018-10-03 Posco Busette de coulée, dispositif de coulée et procédé de coulée
CN108778568A (zh) * 2015-11-27 2018-11-09 株式会社Posco 水口、铸造装置和铸造方法
CN113523262A (zh) * 2020-04-17 2021-10-22 宝山钢铁股份有限公司 防堵塞浸入式水口

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