JP4216642B2 - Immersion nozzle and continuous casting method using the same - Google Patents

Description

【００６３】
図１１に示すように、浸漬ノズルは、ひさし部の傾斜角度（上向き１０度から下向き３５度の範囲）、浸漬ノズルの浸漬深さ（１５０〜３５０ｍｍ）、及びアルゴンガス（Ａｒガス）の吹き込み量（０．２〜２０ＮＬ／分）の各条件を変化させても、不具合の発生率が０．３５未満となっており、高品質の鋳片を製造できることを確認できた。なお、不具合の発生率は、鋳片の引き抜き速度が０．５〜１．７（ｍｍ／分）の範囲においても殆ど変わらず、やはり高品質の鋳片を製造できることを確認できた。
【００６４】
一方、第１の従来例に係る浸漬ノズル５８は、図１１に示すように、鋳片の引き抜き速度が低速になる程、即ち０．７（ｍｍ／分）未満の場合、鋳片にヘゲ、スリバ等が発生し、鋳片表層の品質を低下させる。また、鋳片の引き抜き速度が高速になる程、即ち１．５（ｍｍ／分）を超える場合、鋳片に、気泡、介在物等の起因による内部欠陥が発生する。
従って、不具合の発生率が、実施例に係る浸漬ノズルと比較して、大幅に高くなることが分かる。
以上のことから、実施例に係る浸漬ノズルを使用することで、鋳型内の溶鋼の流れを緩慢にし、かつ均一な流れを形成して、気泡や介在物欠陥を防止して高速鋳造を可能にできる。
【００６５】
なお、前記した第２、第３の実施の形態に係る浸漬ノズル２３、２６の比Ｌ１／Ｄ１のみを、前記した範囲から外した各浸漬ノズルでは、図１１に示した結果よりも不具合の発生率を１０％低減できた。
また、前記した第１の実施の形態に係る浸漬ノズル１０では、図１１に示した結果よりも不具合の発生率を２０％低減できた。
このように、吐出流の緩慢化及び均一化を図って溶鋼を鋳型内に吐出できるので、鋳型内の溶鋼の流れを緩慢にし、かつ均一な流れを形成して、気泡や介在物欠陥を防止して高速鋳造を可能にする。
【００６６】
以上、本発明を、実施の形態を参照して説明してきたが、本発明は何ら上記した実施の形態に記載の構成に限定されるものではなく、特許請求の範囲に記載されている事項の範囲内で考えられるその他の実施の形態や変形例も含むものである。例えば、前記したそれぞれの実施の形態や変形例の一部又は全部を組合せて本発明の浸漬ノズル及びこれを用いた連続鋳造方法を構成する場合も本発明の権利範囲に含まれる。
前記実施の形態においては、各吐出口の上部のみにひさし部を設けた場合、また各吐出口の上部、下部、及び両側部に、各吐出口を囲むようにひさし部を設けた場合について説明した。しかし、ひさし部は各吐出口の少なくとも上部及び下部のいずれか一方又は双方に設けられればよいため、ひさし部を各吐出口の下部のみ、又は上部及び下部のみに設けることも可能である。
そして、前記実施の形態においては、ひさし部の幅を筒状部の外径と実質的に同じにした場合について説明したが、筒状部の外径よりも側方に突出した状態で設けることも可能である。
【００６７】
【発明の効果】
請求項１〜７記載の浸漬ノズル、及び請求項８〜１５記載の連続鋳造方法においては、鋳型内に形成される吐出口からの溶鋼の吐出流を緩慢、かつ均一な流れにでき、形成される溶鋼の下向き流を弱く、しかも、偏流のない均一な流れにできる。これにより、下向き流の減衰と均一化によって鋳片深部へ侵入する気泡や介在物を減少させることができ、鋳片の欠陥を防止できる。また、極端な上向きの吐出流の発生を抑制できるので、湯面の変動を回避してパウダーの巻き込みなどの欠陥や湯面近傍への熱供給を適正にして、安定した鋳造が可能になる。そして、鋳片の凝固殻の内側のウォッシング効果を積極的に発現して、凝固殻に捕捉される気泡や介在物を速やかに浮上させて、表層部の欠陥を減少することができる。更に、吐出流を緩慢にできるので、高速鋳造が可能になり、鋳造の生産性を向上できる。なお、ひさし部により吐出口から吐出する溶鋼の拡散を抑制して、均一な流れにすることができる。
従って、気泡や介在物欠陥を防止した高品質の鋳片を効率的、かつ経済的に安定して製造できる。
また、例えばひさし部の傾斜角度を変えることにより、溶鋼の吐出流の吐出方向（吐出角度）を容易に変更することができるので、浸漬ノズルの構造を簡素化でき、しかも従来のような例えばボックス部を設ける必要性が無くなるので、耐火物、製造の両コストを低減でき経済的である。
【００６８】
特に、請求項２記載の浸漬ノズル、及び請求項１０記載の連続鋳造方法においては、ひさし部の突出長さＬ１と筒状部の内径Ｄ１との比Ｌ１／Ｄ１、及びひさし部の幅Ｗと筒状部の内径Ｄ１との比Ｗ／Ｄ１をそれぞれ設定するので、下降流の形成を更に抑制して、気泡及び介在物が鋳片の深部に侵入することを抑制、更には防止できる。これにより、吐出口から吐出する溶鋼の拡散を抑制、更には防止して、更に均一な流れにすることができる。
【００６９】
請求項３記載の浸漬ノズル、及び請求項１１記載の連続鋳造方法においては、吐出口の基端からひさし部の先端へかけての流路長さＬ２と、筒状部の内径Ｄ１との比Ｌ２／Ｄ１を設定するので、下降流の形成を更に抑制して、気泡及び介在物が鋳片の深部に侵入することを抑制、更には防止でき、高品質の鋳変を製造できる。
【００７０】
請求項１記載の浸漬ノズル、及び請求項８記載の連続鋳造方法においては、各吐出口に溶鋼を吐出可能な複数の小孔が形成された吐出部が設けられているので、複数の小孔によって吐出流を広範囲に分散することができ、吐出する溶鋼の低流速化を図ることができる。これにより、吐出部から吐出する溶鋼の流れを、緩慢で、かつ偏流の無い流れにすることができる。
【００７１】
請求項４記載の浸漬ノズル、及び請求項１２記載の連続鋳造方法においては、吐出部の前端からひさし部の先端へかけての流路長さＬ３と、筒状部の内径Ｄ１との比Ｌ３／Ｄ１を設定するので、下降流の形成を更に抑制して、気泡及び介在物が鋳片の深部に侵入することを抑制、更には防止でき、高品質の鋳変を製造できる。
【００７２】
請求項１記載の浸漬ノズル、及び請求項８記載の連続鋳造方法においては、一方側の吐出口の内断面積Ｓ１と、複数の小孔の総断面積Ｓ２との比Ｓ１／Ｓ２を設定するので、各小孔から吐出する溶鋼の流速を均一にでき、しかも反転流の悪影響を抑制できる。
【００７３】
請求項１記載の浸漬ノズル、及び請求項８記載の連続鋳造方法においては、小孔による圧損を増加させて溶鋼の流速を低減でき、更に溶鋼の二次メニスカス位置を上昇できるため、吐出部の上端部と下端部との間の溶鋼の圧力差を小さくでき、溶鋼の流量を吐出部の高さ方向に均一にできる。これにより、溶鋼の圧損の変動の解消と、吐出口からの溶鋼の吐出流の合体によって吐出流が強くなり、鋳型内壁に衝突して反転する下向き、上向きの溶鋼の流れを抑制して、気泡や介在物の深部への侵入を防止できる。
【００７４】
請求項５記載の浸漬ノズル、及び請求項１３記載の連続鋳造方法においては、複数の小孔から吐出する溶鋼の流速を低減でき、しかも、例えば、パウダーの巻き込み、気泡、介在物の侵入深さを、従来よりも浅くできるので、気泡欠陥や介在物欠陥を防止した高品質の鋳片を製造できる。
【００７５】
請求項１記載の浸漬ノズル、及び請求項８記載の連続鋳造方法においては、吐出部の材質がドロマイトを主体としているので、例えば貫通孔にＡｌ₂Ｏ₃が付着しても、貫通孔の内側面にＡｌ₂Ｏ₃−ＣａＯ系液相が形成され、これが貫通孔を流れる溶鋼によって下流側へ流されるので、従来のようなアルミナ系介在物による小孔の孔詰まりを防止でき、製造する鋳片の品質を向上できる。
【００７７】
請求項６記載の浸漬ノズル、及び請求項１４記載の連続鋳造方法においては、筒状部の下部を除く部分に縮径部を設けるので、筒状部内に落下する溶鋼の落下力を縮径部で吸収でき、従来発生していた吐出流の偏流を抑制でき、良好な品質を備えた鋳片を製造できる。
【００７８】
請求項７記載の浸漬ノズル、及び請求項１５記載の連続鋳造方法においては、筒状部内に落下する溶鋼の落下力を整流部材で吸収でき、しかも整流部材の各貫通孔によって整流部材を通過する溶鋼の落下流を均一化できるので、従来発生していた吐出流の偏流を更に抑制でき、良好な品質を備えた鋳片を製造できる。
【００７９】
請求項９記載の連続鋳造方法においては、ひさし部の傾斜角度、及び鋳型内の溶鋼への浸漬ノズルの浸漬深さを規定することで、吐出口から吐出する溶鋼の上向き流及び下向き流の速度を抑制することができるので、上向き流に起因する湯面変動やパウダー巻き込みによる欠陥、下向き流に起因する気泡や介在物の鋳片深部への侵入を抑制することができ、高品質の鋳片を製造できる。しかも、溶鋼の吐出流の偏流が無いので、例えばひさし部の傾斜角度を従来よりも広い範囲に設定でき、同時に浸漬深さをメニスカス位置から１５０〜３５０ｍｍの範囲にして、安定した高速鋳造が可能になり、生産性を高めることができる。
【図面の簡単な説明】
【図１】（Ａ）、（Ｂ）はそれぞれ本発明の第１の実施の形態に係る浸漬ノズルの側断面図、平面図である。
【図２】本発明の第２の実施の形態に係る浸漬ノズルの側断面図である。
【図３】本発明の第３の実施の形態に係る浸漬ノズルの側断面図である。
【図４】（Ａ）、（Ｂ）はそれぞれ本発明の第４の実施の形態に係る浸漬ノズルの側断面図、平面図である。
【図５】同浸漬ノズルの吐出部の正面図である。
【図６】本発明の第１の実施の形態に係る浸漬ノズルを用いた連続鋳造方法の説明図である。
【図７】（Ａ）〜（Ｃ）はそれぞれ第１の従来例に係る浸漬ノズルの使用状態の説明図、第２の従来例に係る浸漬ノズルの使用状態の説明図、第１の実施例に係る浸漬ノズルの使用状態の説明図である。
【図８】製造した鋳片中の気泡侵入量の説明図である。
【図９】（Ａ）、（Ｂ）はそれぞれ第１の従来例に係る浸漬ノズルの使用状態の説明図、第２の実施例に係る浸漬ノズルの使用状態の説明図である。
【図１０】製造した鋳片中の気泡侵入量の説明図である。
【図１１】製造した鋳片の不具合発生指数と鋳造速度との関係を示す説明図である。
【符号の説明】
１０：浸漬ノズル、１１：溶鋼、１２：筒状部、１３、１４：吐出口、１５、１６：ひさし部、２０：筒状部、２１：湯面位置、２２：縮径部、２３：浸漬ノズル、２４：筒状部、２５：整流部材、２６：浸漬ノズル、２７：係止部、２８：貫通孔、３０：浸漬ノズル、３１：筒状部、３２、３３：吐出口、３４、３５：ひさし部、３６：小孔、３７、３８：吐出部、４０：タンディッシュ、４１：鋳型、４２：支持セグメント、４３：凝固殻、４４：軽圧下セグメント、４５：ピンチロール、４６：鋳片、５０：浸漬ノズル、５１、５２：吐出口、５３、５４：ひさし部、５５：筒状部、５６、５７：吐出口、５８：浸漬ノズル、６０：筒状部、６１、６２：吐出口、６３、６５：浸漬ノズル、６６、６７：吐出口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an immersion nozzle for injecting molten metal into a mold in continuous casting and a continuous casting method using the same, and more specifically, a slow and uniform flow of a molten steel flow discharged from the discharge port of the immersion nozzle into the mold. In addition, the present invention relates to a submerged nozzle capable of suppressing high-speed casting by suppressing intrusion of bubbles and inclusions accompanying the molten steel flow into a deep portion, and a continuous casting method using the same.
[0002]
[Prior art]
Conventionally, in continuous casting, when pouring molten metal into a mold, the following is disclosed as an immersion nozzle (also referred to as an immersion nozzle for continuous casting) that makes the flow of molten steel discharged into the mold slow and uniform. Yes.
For example, the immersion nozzle disclosed in Patent Document 1 is provided with a pair of upper and lower discharge ports on the left and right sides of the immersion nozzle, and the distance D between the upper and lower discharge ports is D <LZ-64Y-370 It is. Here, L is the mold length, Y is the throughput, and Z is the distance from the upper end of the mold to the meniscus.
In order to prevent the entrainment of the powder, this formula sets the distance X from the upper end of the discharge port to the meniscus, that is, X> 80 (0.8Y−1), and prevents the occurrence of breakout. That is, an expression obtained based on D <L− (X + Z + 450).
In addition, the immersion nozzle disclosed in Patent Document 2 has a discharge port that protrudes sideways, and a CaO-containing body such as a lattice or bar shape mainly composed of CaO is attached to the protrusion, and clean steel is used. It can be cast.
The immersion nozzle disclosed in Patent Document 3 is provided with an enlarged box having a plurality of small-diameter discharge ports formed on the side surface at the bottom of the immersion nozzle, and discharges molten steel from each discharge port. By doing so, the discharge flow is dispersed to reduce the flow velocity of the molten steel.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2-187240
[Patent Document 2]
Japanese Utility Model Publication No. 63-85358
[Patent Document 3]
Japanese Utility Model Publication No. 60-71462
[0004]
[Problems to be solved by the invention]
However, since the submerged nozzle of Patent Document 1 has a discharge port that is horizontally long and limited to two holes in the height direction, when the interval between the two holes is close, the flow after the discharge port merges. The effect of discharging the molten steel from the two holes is lost. On the other hand, when the interval between the two holes is wide, the balance of the flow rate passing through the upper and lower discharge ports is lost due to the pressure difference in the height direction of the molten steel, that is, the flow rate from the lower discharge port is increased, resulting in a discharge flow velocity. Therefore, the effect that the molten steel is dispersed and discharged from the two holes is reduced.
For this reason, the flow of the molten steel could not be made slow and uniform, and the reaction product with the refractory and inclusions that were oxides in the molten steel penetrated into the deep part of the slab, which deteriorated the quality of the slab. .
[0005]
Moreover, the immersion nozzle of patent document 2 can determine the direction of the flow of the molten steel to be discharged by extending the discharge port to the side. However, if the inclination angle is downward, the inclusion is caused by the flow of the molten steel. Can not be brought deep into the mold and floated, so that clean steel cannot be obtained. On the other hand, if the inclination angle is upward, the flow velocity of the upward flow cannot be reduced, and powder is entrained along with the flow, so that clean steel cannot be obtained. In addition, in order to reduce the discharge flow rate and prevent inclusions and powder from getting involved, it is necessary to set the flow path between the lattices or the gaps of the bars to an appropriate size. Absent. And CaO is Al in molten steel₂ O_Three It is difficult to maintain the effect of this structure over the entire casting time only by using CaO as a main component.
[0006]
In the immersion nozzle of Patent Document 3, since the dropping force of the molten steel acts directly on the pores, the flow of the molten steel discharged from the discharge portion cannot be made slow and uniform. Further, since the downward flow is formed by the discharge port provided in the lower part, the downward flow becomes strong, and bubbles and inclusions penetrate into the deep part of the slab and accumulate to cause internal surface layer defects.
In particular, since a space portion is provided outside the main discharge port and a plurality of small-diameter discharge ports are arranged on the outside, the structure becomes complicated and the manufacturing cost increases. In addition, since it becomes difficult to restrain the flow, so that it becomes the molten steel flow discharged from the discharge port formed in the peripheral part of the box, the discharged molten steel flow diffuses radially. On the other hand, the molten steel flow discharged from the discharge port formed in the central portion of the box is restrained by the molten steel flow discharged from the peripheral portion of the box. For this reason, the molten steel flow velocity from each discharge port is strong at the center and weak at the outer periphery, and the molten steel flow discharged from each discharge port cannot be made to an appropriate uniform flow velocity, and is uniform at a plurality of discharge ports. There is a problem that a simple flow velocity distribution cannot be formed.
The present invention has been made in view of such circumstances, and an immersion nozzle that slows the flow of molten steel in a mold and forms a uniform flow to prevent bubbles and inclusion defects and enable high-speed casting, and It aims at providing the continuous casting method using this.
[0007]
[Means for Solving the Problems]
The immersion nozzle according to the first aspect of the present invention is provided in a cylindrical part through which molten steel passes from the top to the bottom and a left and right pair provided at the lower part of the cylindrical part and capable of discharging the molten steel in the lateral direction. With discharge portThe ratio D2 / D1 between the inner diameter D1 of the portion excluding the lower portion of the cylindrical portion and the interval D2 between the discharge ports is 0.8 to 1.2.In the immersion nozzle,
At least one or both of the upper and lower portions of each discharge port is provided with an eaves portion capable of guiding the flow of the molten steel discharged from each discharge port,Moreover, the discharge port is provided with a discharge portion in which a plurality of small holes capable of discharging the molten steel are formed, and an inner cross-sectional area S1 of the discharge port on one side and a total cross-sectional area S2 of the plurality of small holes. And the ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion is 2-8,
Furthermore, the discharge part uses dolomite clinker as a part of the aggregate, the mass ratio W1 / W2 of the CaO component content W1 and the MgO component content W2 is 0.46 to 3.0, and MgO 30 to 70% by mass of the component, and 1 to 10% by mass of the carbon component, SiO ₂ And Fe ₂ O _Three Each content of is composed of refractory that is 3% by mass or lessThe
Thus, since at least one or both of the upper and lower portions of each discharge port are provided with eaves, the formation of a downward flow is suppressed and bubbles and inclusions enter the deep portion of the slab. Can be suppressed.
Further, the inner diameter D1 of each portion excluding the lower portion of the cylindrical portion and each dischargemouthSince the ratio D2 / D1 to the interval D2 is set to 0.8 to 1.2, the shape of the immersion nozzle can be simplified without complicating it.
[0008]
Here, when the ratio D2 / D1 between the inner diameter D1 and the distance D2 is smaller than 0.8, the distance D2 becomes too small with respect to the inner diameter D1, so that the dropping force of the molten steel that has fallen into the cylindrical portion is applied to the discharge port. Directly acting, the formation of the downward flow cannot be suppressed, and bubbles and inclusions penetrate into the deep part of the slab. On the other hand, when the ratio D2 / D1 between the inner diameter D1 and the distance D2 is larger than 1.2, the distance D2 becomes too large with respect to the inner diameter D1, so that the shape of the immersion nozzle becomes complicated, and the strength decreases and the refractory material Increases costs.
In view of the above, the ratio D2 / D1 of the inner diameter D1 and the distance D2 is preferably set to 0. 0 in order to simplify the shape of the immersion nozzle and to prevent bubbles and inclusions from entering the deep part of the slab. It is preferably 85 to 1.15, more preferably 0.9 to 1.1.
[0009]
In the immersion nozzle according to the second aspect of the invention, the ratio L1 / D1 between the protrusion length L1 of the eaves portion and the inner diameter D1 of the cylindrical portion is 0.00. The ratio W / D1 between the width W of the eaves portion and the inner diameter D1 of the tubular portion is 1 to 3.
Thus, the ratio L1 / D1 between the protrusion length L1 of the eaves part and the inner diameter D1 of the cylindrical part, and the ratio W / D1 of the eaves part width W and the inner diameter D1 of the cylindrical part are set. It is possible to further suppress the formation of the downward flow, and to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab.
[0010]
Here, the larger the ratio L1 / D1 between the protrusion length L1 of the eaves part and the inner diameter D1 of the cylindrical part, the greater the effect of suppressing the formation of the downward flow, but when the ratio L1 / D1 exceeds 2, For example, the distance from the tip of the eaves portion to the short side member of the mold becomes too small, the collision flow velocity against the short side member increases, the downward flow velocity increases, and the formation of the downward flow cannot be suppressed. On the other hand, when the ratio L1 / D1 is smaller than 0.5, the effect of suppressing the formation of the downward flow by the eaves part becomes small.
From the above, in order to suppress the formation of the downward flow by the eaves part and to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab, the protrusion length L1 of the eaves part and the tube The ratio L1 / D1 with the inner diameter D1 of the shape portion is preferably set to 0.8 to 1.7, more preferably 1 to 1.5.
[0011]
In addition, the larger the ratio W / D1 between the width W of the eaves part and the inner diameter D1 of the cylindrical part, the greater the effect of suppressing the formation of the downward flow, but when the ratio W / D1 exceeds 3, the ratio of the eaves part For example, the distance from both side ends to the long side member of the mold becomes too small, the collision flow velocity to the long side member rises, the descending flow velocity rises, and the formation of the downward flow cannot be suppressed. On the other hand, when the ratio W / D1 is smaller than 1, the effect of suppressing the formation of the downward flow by the eaves part becomes small.
From the above, in order to suppress the formation of the downward flow by the eaves part and to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab, the width W of the eaves part and the cylindrical part The ratio W / D1 to the inner diameter D1 is preferably set to 1.1 to 2.5, more preferably 1.2 to 2.
[0012]
The immersion nozzle according to the third aspect of the invention that meets the above-described object is the immersion nozzle according to the first and second aspects, wherein the flow path length L2 extends from the base end of the discharge port to the tip of the eaves part, Ratio L2 / D1 with the said internal diameter D1 of the said cylindrical part is 1-2.
Thus, since the ratio L2 / D1 between the flow path length L2 from the base end of the discharge port to the tip of the eaves portion and the inner diameter D1 of the cylindrical portion is set, the formation of the downward flow is further suppressed. Thus, it is possible to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab.
Here, the larger the ratio L2 / D1 between the flow path length L2 and the inner diameter D1 of the cylindrical portion, the greater the effect of suppressing the formation of the downward flow, but when the ratio L2 / D1 exceeds 2, the eaves portion For example, the distance from the tip of the mold to the short side member of the mold becomes too small, the collision flow velocity to the short side member increases, the downward flow velocity increases, and the formation of the downward flow cannot be suppressed. On the other hand, when the ratio L2 / D1 is smaller than 1, the effect of suppressing the formation of the downward flow by the eaves part becomes small.
From the above, in order to suppress the formation of the downward flow by the eaves part and to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab, the flow path length L2 and the cylindrical part The ratio L2 / D1 with respect to the inner diameter D1 is preferably set to 1.2 to 1.8, more preferably 1.3 to 1.7.
[0013]
In line with the purpose1In the immersion nozzle according to the invention, each of the discharge ports is provided with a discharge portion in which a plurality of small holes capable of discharging the molten steel are formed.
Thus, since each discharge port is provided with a discharge portion in which a plurality of small holes capable of discharging molten steel are formed, the discharge flow can be dispersed over a wide range by the plurality of small holes and discharged. The flow velocity of molten steel can be reduced.
[0014]
In line with the purpose4The immersion nozzle according to the invention is the first1 and 2In the immersion nozzle according to the invention, the ratio L3 / D1 of the flow path length L3 from the front end of the discharge part to the tip of the eaves part and the inner diameter D1 of the cylindrical part is 1-2. .
Thus, since the ratio L3 / D1 between the flow path length L3 from the front end of the discharge part to the tip of the eaves part and the inner diameter D1 of the cylindrical part is set, the formation of the downward flow is further suppressed. It is possible to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab.
Here, the larger the ratio L3 / D1 between the flow path length L3 and the inner diameter D1 of the cylindrical portion, the greater the effect of suppressing the formation of the downward flow, but when the ratio L3 / D1 exceeds 2, the eaves portion For example, the distance from the tip of the mold to the short side member of the mold becomes too small, the collision flow velocity to the short side member increases, the downward flow velocity increases, and the formation of the downward flow cannot be suppressed. On the other hand, when the ratio L3 / D1 is smaller than 1, the effect of suppressing the formation of the downward flow by the eaves part becomes small.
From the above, in order to suppress the formation of the downward flow by the eaves part and to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab, the flow path length L3 and the cylindrical part The ratio L3 / D1 with the inner diameter D1 is preferably set to 1.2 to 1.8, more preferably 1.3 to 1.7.
[0015]
In line with the purpose1The immersion nozzle according to the invention has a ratio S1 / S2 between the inner cross-sectional area S1 of the discharge port on one side and the total cross-sectional area S2 of the plurality of small holes.2~5.5It is.
Thus, since the ratio S1 / S2 of the inner cross-sectional area S1 of the discharge port on one side and the total cross-sectional area S2 of the plurality of small holes is set, the flow rate of the molten steel discharged from each small hole can be made uniform. Moreover, the adverse effect of the reversal flow formed by the discharged molten steel colliding with the inner wall of the mold can be suppressed.
Here, when the ratio S1 / S2 of the inner cross-sectional area S1 and the total cross-sectional area S2 exceeds 6.5, the flow of the molten steel discharged from the small holes is not sufficiently diffused, and a suction flow is generated in a part and the like. The flow rate cannot be obtained. On the other hand, when the ratio S1 / S2 is smaller than 1, the molten steel flow from the small holes merges, the discharge flow becomes too strong, and the adverse effect of the reverse flow occurs.
From the above, in order to obtain a uniform flow velocity and to suppress or prevent the adverse effect of the reverse flow, the ratio S1 / S2 of the inner sectional area S1 to the total sectional area S2 is set to 2-5. 5 and more preferably 3 to 5.
[0016]
In line with the purpose1In the immersion nozzle according to the invention, a ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion is 2 to 8.
Thus, since the ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion is set, the pressure loss due to the small hole can be increased, the flow velocity of the molten steel can be reduced, and the secondary meniscus position of the molten steel ( Since the molten steel surface position in the cylindrical portion can be raised, the pressure difference of the molten steel between the upper end portion and the lower end portion of the discharge portion can be reduced, and the flow rate of the molten steel can be made uniform in the height direction of the discharge portion.
[0017]
Here, when the ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion exceeds 8, the inner diameter d of the small hole becomes too small with respect to the inner diameter D1 of the cylindrical portion. Each small hole is blocked by the inclusions, or the inner diameter D1 of the cylindrical portion is larger than the inner diameter d of the small hole, so that the clearance in the mold cannot be secured. On the other hand, when the ratio D1 / d is smaller than 2, the pressure loss due to the small holes becomes small, and the flow velocity reduction effect cannot be obtained.
From the above, in order to ensure clearance in the mold without causing clogging of each small hole and to obtain the effect of reducing the flow rate of the molten steel discharged from the discharge portion, the inner diameter d of the small hole and the tubular shape The ratio D1 / d with respect to the inner diameter D1 of the part is preferably set to 2 to 6, more preferably 2 to 5.
[0018]
In line with the purpose5The immersion nozzle according to the invention is the first1No.4In the immersion nozzle according to the invention, a ratio S3 / S2 between the total cross-sectional area S2 of the plurality of small holes and the inner cross-sectional area S3 of the cylindrical portion is 0.5 to 1.5.
Thus, since the ratio S3 / S2 of the total cross-sectional area S2 of the plurality of small holes and the inner cross-sectional area S3 of the cylindrical portion is set, the average discharge flow rate of the molten steel discharged from the plurality of small holes is reduced. Moreover, it is possible to suppress and further prevent an increase in the penetration depth of powder, bubbles, and inclusions.
Here, when the ratio S3 / S2 of the total cross-sectional area S2 to the inner cross-sectional area S3 exceeds 1.5, the total cross-sectional area S2 of the small holes with respect to the inner cross-sectional area S3 becomes too small, and discharge is performed from a plurality of small holes. The average discharge flow rate of molten steel cannot be reduced. On the other hand, when the ratio S3 / S2 is smaller than 0.5, the total cross-sectional area S2 of the small holes with respect to the inner cross-sectional area S3 becomes too large, and the effect of imparting pressure loss due to the small holes is reduced. Therefore, it is necessary to provide at a shallow position or deep position, which causes an increase in the penetration depth of powder, bubbles, and inclusions.
From the above, in order to reduce the average discharge flow rate of molten steel discharged from a plurality of small holes, and to suppress and further prevent the increase of the penetration depth of powder, bubbles and inclusions, The ratio S3 / S2 between the area S2 and the inner cross-sectional area S3 is preferably set to 0.7 to 1.3, more preferably 0.8 to 1.2.
[0019]
In line with the purpose1In the immersion nozzle according to the invention, the discharge portion is made of a refractory material mainly composed of dolomite.
Here, dolomite contains a CaO component and a MgO component, and is generated by the oxidation of Al in molten steel.₂O_ThreeAnd Al contained in molten steel₂O_ThreeIs attached to the surface, CaO component and Al₂O_ThreeReacts with a low melting point compound, that is, Al₂O_Three-A CaO-based liquid phase can be formed.
As a result, for example, Al₂O_ThreeAl is attached to the inner surface of the small hole (also referred to as molten steel contact surface or working surface).₂O_ThreeSince the CaO-based liquid phase is formed and flows downstream by the molten steel flowing through the small holes, it is possible to prevent clogging of the small holes due to the alumina inclusions.
[0021]
In line with the purpose6The immersion nozzle according to the invention is first to first.5The immersion nozzle which concerns on this invention WHEREIN: The diameter reduction part is provided in the part except the lower part of the said cylindrical part.
Thus, since the reduced diameter portion is provided in the portion other than the lower portion of the cylindrical portion, the dropping force of the molten steel falling into the cylindrical portion can be absorbed by the reduced diameter portion.
[0022]
In line with the purpose7The immersion nozzle according to the invention is first to first.6The immersion nozzle which concerns on this invention WHEREIN: The rectification | straightening member provided with the several through-hole which lets the said molten steel pass is provided in the part except the lower part of the said cylindrical part.
As described above, since the rectifying member having a plurality of through holes is provided in a portion other than the lower portion of the cylindrical portion, the dropping force of the molten steel falling into the cylindrical portion can be absorbed by the rectifying member, and each through hole of the rectifying member can be absorbed. By this, the falling flow of the molten steel passing through the rectifying member can be made uniform.
[0023]
In line with the purpose8The continuous casting method according to the invention includes an inner diameter D1 of a cylindrical portion through which molten steel passes from the top to the bottom, and a discharge port that is provided at the lower portion of the cylindrical portion and forms a left and right pair capable of discharging the molten steel in a lateral direction. The ratio D2 / D1 with the interval D2 between is 0.8 to 1.2, and the flow of the molten steel discharged from each discharge port is at least one or both of the upper and lower portions of each discharge port. Inductable eaves part is providedIn addition, a discharge portion in which a plurality of small holes capable of discharging the molten steel is formed in the discharge port, an inner cross-sectional area S1 of the discharge port on one side, and a total cross-sectional area S2 of the plurality of small holes, The ratio S1 / S2 is 2 to 5.5, the ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion is 2 to 8, and the discharge section is dolomite Using clinker as part of the aggregate, the mass ratio W1 / W2 of the CaO component content W1 and the MgO component content W2 is 0.46 to 3.0, and the MgO component is 30 to 70% by mass Moreover, it contains 1 to 10% by mass of a carbon component, and SiO ₂ And Fe ₂ O _Three Each content of is composed of refractory that is 3% by mass or lessThe molten steel is poured into the mold through the immersion nozzle, and the molten steel is pulled out from the mold at a casting speed of 0.6 m / min or more while solidifying the molten steel.
In this way, by using the immersion nozzle configured as described above and pouring molten steel into the mold, the molten steel discharge flow from the discharge port formed in the mold can be made slow and uniform and formed. Since the downward flow is weak and can be a uniform flow without uneven flow, it is possible to suppress the inclusion of reaction products with the cylindrical portion and inclusions which are oxides in the molten steel into the deep portion of the slab.
Here, by setting the casting speed to 0.6 m / min or more, it is possible to manufacture a slab having no slab surface layer or internal defects. However, the productivity is improved and the slab is heated at a high temperature after a heating furnace or the like. In order to effectively use the thermal energy by supplying it to the process, the casting speed is preferably 0.8 m / min or more, and more preferably 1.0 m / min or more. On the other hand, although an upper limit is not specified, it is preferable to cast at a casting speed of 2.3 m / min or less, for example, considering the cooling capacity of a continuous casting facility that solidifies molten steel.
[0024]
In line with the purpose9The continuous casting method according to the invention is8In the continuous casting method according to the invention, an inclination angle of the eaves portion is set in a range of 10 degrees upward to 35 degrees downward with respect to a horizontal state, and the discharge port is set in a range of 150 to 350 mm from the meniscus position in the mold. In the molten steel, the amount of argon gas blown is 0.2 to 20 NL / min.
In this way, by defining the inclination angle of the eaves part, the immersion depth of the immersion nozzle into the molten steel in the mold, and the amount of argon gas blown in, the upward and downward flow of the molten steel discharged from each discharge port The speed can be suppressed, and defects due to fluctuations in the molten metal surface caused by upward flow and powder entrainment, and intrusion of bubbles and inclusions due to downward flow into the deep part of the slab can be suppressed. Moreover, since there is no drift in the discharge flow of molten steel, for example, the inclination angle of the eaves can be set in a wider range than before, and at the same time the immersion depth can be set in the range of 150 to 350 mm from the meniscus position, enabling stable high speed casting. become.
[0025]
Here, when the inclination angle of the eaves part exceeds 10 degrees upward with respect to the horizontal position, fluctuation of the molten metal surface or entrainment of powder occurs due to the upward flow. On the other hand, when the inclination angle of the eaves part exceeds 35 degrees downward with respect to the horizontal position, the downward flow becomes strong, and inclusions and bubbles accompanying the downward flow penetrate into the deep part of the slab, and internal defects of the slab This makes it impossible to produce high quality slabs.
From the above, in order to manufacture a high quality slab, it is preferable that the inclination angle of the eaves part is in the range of 5 degrees upward to 20 degrees downward relative to the horizontal position, and further to the horizontal position. It is preferable that the angle be in the range of 5 degrees upward to 15 degrees downward.
[0026]
For example, when the immersion depth of the upper end of the discharge port of the immersion nozzle becomes shallower than 150 mm, the upward flow of the molten steel discharged from each discharge port acts on the molten metal surface, causing the molten metal surface fluctuation and powder entrainment. Become. On the other hand, when the immersion depth exceeds 350 mm, the downward flow of the molten steel becomes strong, air bubbles and inclusions accompany the deep part of the slab, hindering its floating, and lowering the quality inside the slab.
From the above, in order to produce a high quality slab, the immersion depth at the upper end of the discharge port of the immersion nozzle is preferably 200 to 300 mm, and more preferably 200 to 250 mm.
[0027]
If the amount of argon gas (also referred to as Ar gas) is less than 0.2 NL / min, the effect of preventing the closing of the immersion nozzle by Ar gas bubbles is reduced and the effect of promoting the floating of inclusions by Ar gas bubbles is achieved. Decrease. On the other hand, when the blowing amount is higher than 20 NL / min, the effect of preventing the closing of the immersion nozzle can be improved. However, the fluctuation of the molten metal surface due to the increase of Ar gas bubbles, the entrainment of powder, the trapping of bubbles in the solidified shell, This may cause problems such as the intrusion of bubbles into the slab, leading to deterioration of the quality of the slab.
From the above, the amount of Ar gas blown is preferably set to 0.2 to 10 NL / min, more preferably 0.2 to 5 NL / min, so that the levitation force of the bubbles of Ar gas can be utilized to immerse the gas. Low melting point Al produced by reaction with CaO component, which is a component of the nozzle₂ O_Three -Promoting the floating of CaO-based products and producing slabs with high cleanliness.
[0028]
In line with the purpose10The continuous casting method according to the invention is8And the second9In the continuous casting method according to the invention, the ratio L1 / D1 between the projection length L1 of the eaves part and the inner diameter D1 of the tubular part is 0.5 to 2, and the width W of the eaves part and the Ratio W / D1 with the said internal diameter D1 of a cylindrical part is 1-3.
Thus, the ratio L1 / D1 between the protrusion length L1 of the eaves part and the inner diameter D1 of the cylindrical part, and the ratio W / D1 of the eaves part width W and the inner diameter D1 of the cylindrical part are set. It is possible to further suppress the formation of the downward flow, and to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab.
[0029]
In line with the purpose11The continuous casting method according to the invention is8No.10In the continuous casting method according to the invention, the ratio L2 / D1 of the flow path length L2 from the base end of the discharge port to the tip of the eaves part and the inner diameter D1 of the cylindrical part is 1-2. It is.
Thus, since the ratio L2 / D1 between the flow path length L2 from the base end of the discharge port to the tip of the eaves portion and the inner diameter D1 of the cylindrical portion is set, the formation of the downward flow is further suppressed. Thus, it is possible to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab.
[0030]
In line with the purpose8In the continuous casting method according to the invention, each of the discharge ports is provided with a discharge portion in which a plurality of small holes capable of discharging the molten steel are formed.
Thus, since each discharge port is provided with a discharge portion in which a plurality of small holes capable of discharging molten steel are formed, the discharge flow can be dispersed over a wide range by the plurality of small holes and discharged. The flow velocity of molten steel can be reduced.
[0031]
In line with the purpose12The continuous casting method according to the invention is8th to 10thIn the continuous casting method according to the invention, the ratio L3 / D1 of the flow path length L3 from the front end of the discharge part to the tip of the eaves part and the inner diameter D1 of the cylindrical part is 1-2. is there.
Thus, since the ratio L3 / D1 between the flow path length L3 from the front end of the discharge part to the tip of the eaves part and the inner diameter D1 of the cylindrical part is set, the formation of the downward flow is further suppressed. It is possible to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab.
[0032]
In line with the purpose8In the continuous casting method according to the invention, the ratio S1 / S2 between the inner cross-sectional area S1 of the discharge port on one side and the total cross-sectional area S2 of the plurality of small holes is2~5.5It is.
Thus, since the ratio S1 / S2 of the inner cross-sectional area S1 of the discharge port on one side and the total cross-sectional area S2 of the plurality of small holes is set, the flow rate of the molten steel discharged from each small hole can be made uniform. Moreover, the adverse effect of the reverse flow can be suppressed.
[0033]
In line with the purpose8In the continuous casting method according to the invention, a ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion is 2 to 8.
Thus, since the ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion is set, the pressure loss due to the small hole can be increased, the flow velocity of the molten steel can be reduced, and the secondary meniscus position of the molten steel can be set. Since it can raise, the pressure difference of the molten steel between the upper end part and lower end part of a discharge part can be made small, and the flow volume of molten steel can be made uniform in the height direction of a discharge part.
[0034]
In line with the purpose13The continuous casting method according to the invention is8No.12In the continuous casting method according to the invention, the ratio S3 / S2 between the total cross-sectional area S2 of the plurality of small holes and the inner cross-sectional area S3 of the cylindrical portion is 0.5 to 1.5.
Thus, since the ratio S3 / S2 of the total cross-sectional area S2 of the plurality of small holes and the inner cross-sectional area S3 of the cylindrical portion is set, the average discharge flow rate of the molten steel discharged from the plurality of small holes is reduced. Moreover, it is possible to suppress and further prevent an increase in the penetration depth of powder, bubbles, and inclusions.
[0035]
In line with the purpose8In the continuous casting method according to the invention, the discharge part is made of a refractory material mainly composed of dolomite.
As a result, for example, Al₂O_ThreeEven if it adheres, Al on the inner surface of the small hole₂O_ThreeSince the CaO-based liquid phase is formed and flows downstream by the molten steel flowing through the small holes, it is possible to prevent clogging of the small holes due to the alumina inclusions.
[0037]
In line with the purpose14The continuous casting method according to the invention is8No.13In the continuous casting method according to the invention, a reduced diameter portion is provided in a portion excluding the lower portion of the cylindrical portion.
Thus, since the reduced diameter portion is provided in the portion other than the lower portion of the cylindrical portion, the dropping force of the molten steel falling into the cylindrical portion can be absorbed by the reduced diameter portion.
[0038]
In line with the purpose15The continuous casting method according to the invention is8No.14In the continuous casting method according to the invention, a rectifying member having a plurality of through holes through which the molten steel passes is provided in a portion excluding the lower portion of the cylindrical portion.
As described above, since the rectifying member having a plurality of through holes is provided in a portion other than the lower portion of the cylindrical portion, the dropping force of the molten steel falling into the cylindrical portion can be absorbed by the rectifying member, and each through hole of the rectifying member can be absorbed. By this, the falling flow of the molten steel passing through the rectifying member can be made uniform.
[0039]
That is, the inventors of the present invention have a conventional immersion nozzle with two holes. As the casting speed increases, the flow velocity of the downflow near the mold increases and the penetration depth of bubbles and inclusions increases. As a result of studying the nozzle structure to obtain a stabilized flow by reducing the discharge flow rate, the submerged nozzle of the present invention and this It was confirmed that a uniform discharge flow can be obtained at a low flow rate by a continuous casting method using a slag.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIGS. 1A and 1B are respectively a side sectional view and a plan view of an immersion nozzle according to the first embodiment of the present invention, and FIG. 2 is an immersion according to the second embodiment of the present invention. 3 is a side sectional view of the nozzle, FIG. 3 is a side sectional view of the immersion nozzle according to the third embodiment of the present invention, and FIGS. 4A and 4B are immersion according to the fourth embodiment of the present invention. FIG. 5 is a front view of a discharge portion of the immersion nozzle, FIG. 6 is an explanatory view of a continuous casting method using the immersion nozzle according to the first embodiment of the present invention, and FIG. (A)-(C) is explanatory drawing of the use condition of the immersion nozzle which concerns on a 1st prior art example, respectively, The explanatory drawing of the use condition of the immersion nozzle which concerns on a 2nd prior art example, The immersion nozzle which concerns on a 1st Example FIG. 8 is an explanatory view of the amount of bubble intrusion in the manufactured slab, FIG. 9 is (A), (B) is the first conventional one, respectively. FIG. 10 is an explanatory view of the state of use of the immersion nozzle according to the second embodiment, FIG. 10 is an explanatory view of the state of use of the immersion nozzle according to the second embodiment, FIG. 10 is an explanatory view of the amount of bubble penetration in the manufactured slab, and FIG. It is explanatory drawing which shows the relationship between this malfunction occurrence index and casting speed.
[0041]
As shown in FIGS. 1 (A) and 1 (B), an immersion nozzle (also referred to as a continuous casting immersion nozzle) 10 according to the first embodiment of the present invention has a cylindrical shape through which molten steel 11 passes from top to bottom. A portion 12 and a discharge port 13 and 14 which are provided at the lower portion of the cylindrical portion 12 and which are left and right pairs capable of discharging the molten steel 11 in the lateral direction, and an inner diameter D1 ( For example, a ratio D2 / D1 of 50 to 90 mm) and a distance between the discharge ports 13 and 14 (a distance between the base ends of the discharge ports 13 and 14) D2 is 0.8 to 1.2. is there. This will be described in detail below.
[0042]
Each of the discharge ports 13 and 14 has a rectangular shape when viewed from the front. The discharge ports 13 and 14 are respectively disposed on both sides of the tubular portion 12 as a center, and the tubular portions are disposed above the discharge ports 13 and 14. Eaves portions 15 and 16 projecting forward from 12 are provided. In addition, each eaves part 15 and 16 guides the flow of the molten steel discharged from each discharge port 13 and 14.
Here, the ratio L1 / D1 between the protruding length L1 of the eaves 15 and 16 from the tubular portion 12 and the inner diameter D1 of the tubular portion 12 is set to 0.5 to 2, and the eaves 15 The ratio W / D1 between the width W of 16 and the inner diameter D1 of the cylindrical portion 12 is set to 1 to 3. In addition, the ratio between the flow path length L2 from the base end of each discharge port 13 and 14, ie, the inner surface of the cylindrical part 12, to the tip of the eaves parts 15 and 16, and the inner diameter D1 of the cylindrical part 12 L2 / D1 is set in the range of 1-2.
[0043]
The inclination angle θ of each of the eaves 15 and 16 is set in a range of 10 degrees upward to 35 degrees downward with respect to the horizontal position. In this way, by changing the inclination angle of the eaves 15 and 16, the flow direction of the molten steel 11 discharged from the discharge ports 13 and 14 can be easily changed, so that the flow of the molten steel 11 can be easily stabilized. In addition, it is possible to perform casting adapted to the steel type and casting conditions.
In addition, the cylindrical part 12 can be formed using the refractory for immersion nozzles conventionally used, for example, an alumina graphite refractory (AG).
[0044]
Moreover, as shown in FIG. 2, the immersion nozzle 23 which concerns on the 2nd Embodiment of this invention is a part except the lower part of the cylindrical part 20, ie, the hot_water | molten_metal surface of the molten steel 11 which exists in the inside of the cylindrical part 20. As shown in FIG. On the inner peripheral portion of the cylindrical portion 20, for example, 50 to 300 mm above the position (secondary meniscus position) 21, the reduced diameter portion 22 (for example, 1/2 ×) whose inner diameter D3 is smaller than the inner diameter D1 of the cylindrical portion 20. D1 ≦ D3 <D1) is provided. The cylindrical portion 20 has substantially the same configuration as the cylindrical portion 12 except that the reduced diameter portion 22 is provided.
Thereby, the falling molten steel 11 can collide with the level | step-difference part of the reduced diameter part 22, and the fall energy of the molten steel 11 can be attenuated.
[0045]
Further, as shown in FIG. 3, the immersion nozzle 26 according to the third embodiment of the present invention is, for example, 50 than the molten metal surface position (secondary meniscus position) 21 of the molten steel 11 existing inside the cylindrical portion 24. A rectifying member 25 is provided on the inner peripheral portion of the cylindrical portion 24 that is ˜300 mm above.
Here, inside the cylindrical part 24, there is provided a locking part 27 having an inner diameter slightly reduced (for example, 5 to 10 mm) and having a step, and a rectifying member 25 is provided on the upper surface of the locking part 27. The lower surface of this is placed in contact. The cylindrical portion 24 has substantially the same configuration as the cylindrical portion 12 except that the locking portion 27 is provided.
[0046]
The rectifying member 25 has a cylindrical outer shape, and is provided at substantially equal angles with the axial center of the rectifying member 25 as the center, and the molten steel 11 formed in the axial direction of the rectifying member 21 passes therethrough. A plurality of possible through holes 28 (for example, 4 or more) are provided. For this reason, the inner side surface of each through-hole 28 becomes an operation surface (hereinafter also referred to as a molten steel contact surface).
As a result, the molten steel 11 that has fallen into the immersion nozzle 26 is not directly collided with the molten metal surface of the molten steel 11 in the immersion nozzle 26, and after the decay energy of the molten steel 11 is once attenuated by the rectifying member 25, Since it can disperse | distribute by 28 and can supply further downstream, the fluctuation | variation of the hot_water | molten_metal surface in the immersion nozzle 26 can be suppressed.
The rectifying member 25 is preferably made of a refractory mainly composed of dolomite. In this case, at least a portion where the cylindrical portion 24 and the rectifying member 25 are in contact with each other, as described above, a zirconia-based mortar. Is used.
[0047]
Next, an immersion nozzle (also referred to as a continuous casting immersion nozzle) 30 according to a fourth embodiment of the present invention will be described.
As shown in FIGS. 4A and 4B, the immersion nozzle 30 is provided in a cylindrical portion 31 through which the molten steel 11 passes from top to bottom, and a lower portion of the cylindrical portion 31, and the molten steel 11 extends in the lateral direction. It has the discharge ports 32 and 33 which become the right and left pair which can discharge.
[0048]
Each of the discharge ports 32 and 33 has a rectangular shape when viewed from the front, and is disposed on both sides of the tubular portion 31 as a center, and the upper, lower, and both sides of each of the discharge ports 32 and 33. The part is provided with eaves parts 34 and 35 that project from the cylindrical part 31 in both directions and surround the discharge ports 32 and 33.
Here, the ratio L1 / D1 between the protruding length L1 of the eaves 34 and 35 from the tubular portion 31 and the inner diameter D1 of the tubular portion 31 is set to 0.5 to 2, and the eaves 34 and 35 are also set. The ratio W / D1 between the width W of the cylindrical portion 31 and the inner diameter D1 of the cylindrical portion 31 is set to 1 to 3. As described above, since each of the discharge ports 32 and 33 is surrounded by the eaves portions 34 and 35 having the above-described size, it is possible to reduce the entrainment of bubbles and the disturbance of the discharge flow.
Further, the inclination angle θ of the eaves portions 34 and 35 is set in a range of 10 degrees upward to 35 degrees downward with respect to the horizontal position. In this way, by changing the inclination angle θ of the eaves 34 and 35, the flow direction of the molten steel 11 discharged from the discharge ports 32 and 33 can be easily changed, so that the flow of the molten steel 11 can be easily performed. It is possible to stabilize the casting, and it is possible to perform casting adapted to the steel type and casting conditions.
[0049]
As shown in FIGS. 4 (A), 4 (B), and 5, the discharge ports 32 and 33 have substantially the same inner diameter d, can discharge the molten steel 11, and the upper end portion to the lower end portion. Discharge portions 37 and 38 in which a plurality of (for example, 5 to 20) small holes 36 are disposed so as to be dispersed are provided.
Here, the ratio D2 / D1 between the inner diameter D1 (for example, 50 to 90 mm) of the portion excluding the lower portion of the cylindrical portion 31 and the interval between the discharge ports 32 and 33, that is, the interval D2 between the discharge portions 37 and 38, is 0. .8 to 1.2, and the ratio L3 / D1 between the flow path length L3 from the front ends of the discharge portions 37 and 38 to the tips of the eaves portions 34 and 35 and the inner diameter D1 of the cylindrical portion 31. Is set to 1-2.
The ratio S1 / S2 between the inner cross-sectional area S1 of the discharge port 32 on one side and the total cross-sectional area S2 of the plurality of small holes 36 is set to 1 to 6.5, and the inner diameter d of the small hole 36 and the cylinder The ratio D1 / d with respect to the inner diameter D1 of the cylindrical portion 31 is set to 2 to 8, and the ratio S3 / S2 between the total sectional area S2 of the plurality of small holes 36 and the inner sectional area S3 of the cylindrical portion 31 is 0. .5 to 1.5.
[0050]
Since each of the discharge units 37 and 38 has substantially the same configuration, only the discharge unit 37 on one side will be described below.
The discharge part 37 is comprised with the refractory material which made dolomite the main body.
The refractory constituting the discharge unit 37 has, for example, a mass ratio W1 / W2 of the CaO component content W1 and the MgO component content W2 of 0.46 to 3.0, and the MgO component of 30 to 30. 70 mass% is contained. In addition, in this refractory material, 1-10 mass% of carbon components are contained. Further, in this refractory, the mass ratio W1 / W3 of the content W1 of the CaO component to the content W3 of the remaining component excluding the CaO component and the MgO component is 2 to 30, in particular, SiO in the remaining component.₂ And Fe₂ O_Three Each content of is adjusted to be 3% by mass or less.
[0051]
In order to satisfy the above-described composition, this refractory uses dolomite clinker as a part of the aggregate, and, for example, 3 to 30% by mass of MgO particles having a particle size of 0.5 mm or less are added thereto, and further bonded. As a material, for example, a phenol resin can be added and adjusted.
And the discharge part 37 can be formed by forming the discharge part which formed several small holes previously from the above-mentioned refractory material, and hardening-processing a phenol resin.
Moreover, the cylindrical part 31 can be formed using the refractory material for immersion nozzles conventionally used, for example, an alumina graphite refractory material.
Since the alumina graphite refractory and dolomite react, zirconia-based mortar is used at least at the portion where the cylindrical portion 31 and the discharge portion 37 are in contact with each other. In addition, it is also possible to comprise cylindrical part itself with a zirconia graphite refractory.
[0052]
Thus, since the discharge part 37 is comprised with the refractory material which has dolomite as a main body, Al to several small holes 36 is carried out.₂ O_Three Can be suppressed and further prevented as compared with the prior art.
Moreover, the discharge part 37 is a refractory mainly composed of alumina graphite refractory or zirconia graphite refractory (ZG), and the content of one or both of the carbon component and the silicon component is 1% by mass or less. It is also possible to configure.
Thereby, after the molten steel 11 is discharged from each small hole 36 and the flow of the molten steel 11 is dispersed over a wide range so as to have a low flow rate, it can be guided to the front of the discharge ports 32 and 33 by the eaves portions 34 and 35.
[0053]
Then, the continuous casting method using the immersion nozzle 10 which concerns on the 1st Embodiment of this invention is demonstrated.
As shown in FIG. 6, the molten steel 11 was put in the tundish 40 and further poured into the mold 41 through the immersion nozzle 10 provided below the tundish 40. In addition, the casting_mold | template 41 is a cross-sectional rectangular shape of 250 mm x 1000-1800 mm, for example. The solidified shell (solidified shell) 43 is generated by cooling with the mold 41 and cooling with water spray from the cooling water nozzle provided on the support segment 42, and the growth of the solidified shell 43 is promoted. A pressing roll (not shown) is used for reduction, and the pinch roll 45 is pulled out from the mold 41 at a casting speed of 0.6 m / min or more to cast a slab 46.
[0054]
The immersion nozzle 10 is so arranged that the upper ends of the discharge ports 13 and 14 of the immersion nozzle 10 are immersed in the molten steel 11 in the mold 41 at a depth in the range of, for example, 150 to 350 mm from the meniscus (water surface) position. Placed and fixed. In addition, when argon gas is blown into the immersion nozzle 10, the amount of argon gas blown into the immersion nozzle 10 through the upper nozzle and sliding nozzle (SN) plate provided in the tundish 40, and immersion through the slits. The total amount of argon gas blown into the nozzle 10 is adjusted to, for example, 0.2 to 20 NL / min.
[0055]
In addition, when the immersion nozzle 30 was used instead of the immersion nozzle 10, it was produced | generated from Al in the molten steel 11 by discharging the molten steel 11 into the casting_mold | template 41 from the some small hole 36 of each discharge part 37 and 38. Al₂ O_Three Adheres to the working surface which is the inner surface of each small hole 36, but the adhered Al₂ O_Three Reacts with CaO in the dolomite clinker to lower the melting point of Al₂ O_Three -CaO-based liquid phase is formed, and excess Al₂ O_Three Formation of the -CaO-based liquid phase can be suppressed, and digestion of the refractory can also be suppressed.
In addition, SiO grain at grain boundaries of dolomite clinker crystal particles₂ And Fe₂ O_Three By being present, it reacts with CaO in the dolomite clinker to form a low-melting compound, activates the movement of CaO, and improves the reactivity of CaO. The corrosion resistance on the operating surface side can be improved by the MgO-rich layer formed on the operating surface side.
Thereby, the discharge flow of the molten steel 11 can be made slow and the flow velocity distribution can be made uniform, the fluctuation of the molten metal surface can be suppressed, and the entrainment of the powder can be prevented, and it penetrates into the deep part of the slab accompanying the discharge flow. It is possible to prevent slab quality defects caused by bubbles, inclusions, and the like.
[0056]
【Example】
The result of applying the continuous casting method according to the above-described embodiment and performing a test will be described.
In FIG. 7, it shows about the state of the flow of the molten steel formed in the casting_mold | template 41. FIG.
When the immersion nozzle 50 according to the first embodiment in which the eaves portion of the immersion nozzle 10 is inclined upward is used, each discharge port 51 formed in the mold 41 is shown in FIG. 7C. 52, the discharge flow of the molten steel 11 can be made slow and uniform, and the downward flow of the formed molten steel 11 can be made weak and uniform with no uneven flow. Further, the generated upward discharge flow collides with the eaves portions 53 and 54, and the flow velocity is reduced.
[0057]
On the other hand, an immersion nozzle 58 according to the first conventional example is provided at the lower part of the cylindrical portion 55, with the discharge ports 56 and 57 each having an axis inclined downward and capable of discharging the molten steel 11 in a downward oblique direction. When used, the downward flow velocity cannot be reduced as shown in FIG. As a result, bubbles and inclusions accompanying the strong downward flow penetrate into the deep part of the slab, so that defects caused by bubbles and inclusions inside the slab cannot be prevented, resulting in deterioration of the slab quality, The problem that can not be manufactured stably occurs.
In addition, an immersion nozzle 63 according to the second conventional example is provided at the lower part of the cylindrical part 60, the axis of which is inclined upward, and the respective discharge ports 61 and 62 capable of discharging the molten steel 11 in an obliquely upward direction are provided. When used, as shown in FIG. 7B, the flow velocity of the downward flow can be reduced, but the flow velocity of the upward flow cannot be reduced. For this reason, fluctuations in the molten metal surface and powder entrainment due to upward flow occur, and it is not possible to prevent defects due to bubbles and interposition inside the slab, leading to deterioration in the quality of the slab, and inability to stably manufacture the slab. appear.
[0058]
Here, FIG. 8 shows a comparison of the amount of bubble intrusion contained in the slab manufactured using the immersion nozzle 58 according to the first conventional example and the immersion nozzle 50 according to the first embodiment. In addition, the bubble penetration amount index is obtained by setting the amount of bubbles in a slab manufactured to 100 when the casting speed is 1.0 (m / min) using the immersion nozzle 58 of the first conventional example. The higher the index is, the more bubbles are present during the casting change, indicating that the quality of the slab is lowered.
When casting is performed using the immersion nozzle 58 according to the first conventional example, the bubble penetration amount index is increased by increasing the casting speed from 1.0 (m / min) to 1.6 (m / min). Increases 1.6 times. On the other hand, when casting is performed using the immersion nozzle 50 according to the first embodiment, the bubble penetration index is 60 when the casting speed is 1.0 (m / min), which is compared with the immersion nozzle 58. It can be seen that the reduction can be achieved. It can also be seen that even when the casting speed was increased to 1.6 (m / min), the bubble penetration amount index was about 80, which was about half that of the immersion nozzle 58.
From the above, by using the immersion nozzle 50 according to the first embodiment, it is possible to suppress and further prevent the drift of the discharge flow of the molten steel 11 from the discharge ports 51 and 52, and to produce a high-quality casting. The piece can be cast at a higher speed than before.
[0059]
Subsequently, in FIGS. 9A and 9B, the immersion nozzle 58 according to the first conventional example and the immersion nozzle according to the second embodiment having substantially the same configuration as the immersion nozzle 30 described above, respectively. It shows about the state of the flow of the molten steel 11 formed in the casting_mold | template 41 at the time of using 65. FIG.
When the immersion nozzle 65 according to the second embodiment is used, the discharge flow of the molten steel 11 from the discharge ports 66 and 67 formed in the mold 41 is slow and uniform as shown in FIG. 9B. Therefore, the downward flow of the molten steel 11 to be formed can be weakened and the flow can be made uniform without drift.
On the other hand, when the immersion nozzle 58 according to the first conventional example is used, the flow velocity of the downward flow cannot be reduced as shown in FIG. As a result, bubbles and inclusions accompanying the strong downward flow penetrate into the deep part of the slab, so that defects caused by bubbles and inclusions inside the slab cannot be prevented, resulting in deterioration of the slab quality, The problem that can not be manufactured stably occurs.
[0060]
Here, FIG. 10 shows a comparison of the amount of bubble intrusion contained in the slab manufactured using the immersion nozzle 58 according to the first conventional example and the immersion nozzle 65 according to the second embodiment.
When casting is performed using the immersion nozzle 65 according to the second embodiment, the bubble penetration index is 40 when the casting speed is 1.0 (m / min), which is significantly larger than that of the immersion nozzle 58. It can be seen that it can be reduced. Moreover, even if it raises a casting speed to 1.6 (m / min), the bubble penetration | invasion amount index | exponent is about 50, and it turns out that a high quality slab can be manufactured also by high-speed casting.
From the above, by using the immersion nozzle 65 according to the second embodiment, the uneven flow of the discharge flow of the molten steel 11 from each discharge port 66, 67 is suppressed, further prevented, and further improved in quality. The slab can be cast at a higher speed than before.
[0061]
Subsequently, FIG. 11 shows the immersion nozzle according to the example in which only the ratio L1 / D1 and the ratio L2 / D1 of the immersion nozzle 10 according to the first embodiment are excluded from the above-described range. The relationship of the malfunction (defective product) generation | occurrence | production index of a slab manufactured using the immersion nozzle 58 which concerns on a prior art example, and a casting speed is shown. In addition, the defect occurrence index of the slab indicates the occurrence ratio of defects with respect to the slab (10 to 20 slabs) manufactured within a predetermined period. Is shown. Here, as shown in Table 1, the test was performed by changing each condition of the inclination angle of the eaves portion, the immersion depth of the immersion nozzle, and the amount of argon gas (Ar gas) blown.
[0062]
[Table 1]

[0063]
As shown in FIG. 11, the immersion nozzle has an inclination angle of the eaves part (range of 10 degrees upward to 35 degrees downward), the immersion depth of the immersion nozzle (150 to 350 mm), and the amount of argon gas (Ar gas) blown in Even if each condition (0.2 to 20 NL / min) was changed, the failure rate was less than 0.35, and it was confirmed that a high-quality slab could be produced. In addition, it was confirmed that the occurrence rate of defects hardly changed even when the drawing speed of the slab was in the range of 0.5 to 1.7 (mm / min), and that a high-quality slab could be produced.
[0064]
On the other hand, the immersion nozzle 58 according to the first conventional example, as shown in FIG. 11, has a stagnation on the slab when the drawing speed of the slab becomes lower, that is, less than 0.7 (mm / min). Sliver and the like are generated, and the quality of the slab surface layer is lowered. Further, when the drawing speed of the slab becomes higher, that is, when the slab exceeds 1.5 (mm / min), internal defects due to bubbles, inclusions and the like are generated in the slab.
Therefore, it can be seen that the occurrence rate of defects is significantly higher than that of the immersion nozzle according to the example.
From the above, by using the immersion nozzle according to the embodiment, the flow of the molten steel in the mold is slowed down and a uniform flow is formed, which prevents high-speed casting by preventing bubbles and inclusion defects. it can.
[0065]
Incidentally, in each of the immersion nozzles in which only the ratio L1 / D1 of the immersion nozzles 23 and 26 according to the second and third embodiments described above is excluded from the above-described range, a problem is generated more than the result shown in FIG. The rate could be reduced by 10%.
Moreover, in the immersion nozzle 10 which concerns on above-described 1st Embodiment, the malfunction occurrence rate was able to be reduced 20% rather than the result shown in FIG.
In this way, the molten steel can be discharged into the mold by slowing and uniforming the discharge flow, so that the molten steel flow in the mold is slowed down and a uniform flow is formed to prevent bubbles and inclusion defects. To enable high speed casting.
[0066]
As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the immersion nozzle of the present invention and a continuous casting method using the same are configured by combining some or all of the above-described embodiments and modifications are also included in the scope of the right of the present invention.
In the above-described embodiment, a description is given of a case where an eaves portion is provided only at the upper portion of each discharge port, and a case where an eave portion is provided so as to surround each discharge port at the upper portion, lower portion, and both side portions of each discharge port. did. However, since the eaves portion only needs to be provided in at least one or both of the upper and lower portions of each discharge port, the eaves portion can be provided only in the lower portion of each discharge port, or only in the upper portion and lower portion.
And in the said embodiment, although the case where the width | variety of an eaves part was made substantially the same as the outer diameter of a cylindrical part was demonstrated, it provides in the state protruded to the side rather than the outer diameter of a cylindrical part. Is also possible.
[0067]
【The invention's effect】
Claims 1 to7Immersion nozzle according to claim, and claim8~15In the described continuous casting method, the discharge flow of the molten steel from the discharge port formed in the mold can be made slow and uniform flow, the downward flow of the formed molten steel is weak, and there is no uniform flow. Can be. Thereby, the bubble and inclusion which penetrate | invade into a slab deep part can be reduced by attenuation | damping and equalization of a downward flow, and the defect of a slab can be prevented. In addition, since the generation of an extremely upward discharge flow can be suppressed, stable casting can be achieved by avoiding fluctuations in the molten metal surface and appropriately supplying defects such as entrainment of powder and heat supply to the vicinity of the molten metal surface. Then, the washing effect inside the solidified shell of the slab can be positively expressed, and bubbles and inclusions trapped in the solidified shell can be promptly floated to reduce defects in the surface layer portion. Furthermore, since the discharge flow can be made slow, high-speed casting becomes possible, and casting productivity can be improved. In addition, it can be made a uniform flow by suppressing the diffusion of the molten steel discharged from the discharge port by the eaves portion.
Therefore, a high-quality slab in which bubbles and inclusion defects are prevented can be produced efficiently and economically stably.
In addition, for example, by changing the inclination angle of the eaves part, the discharge direction (discharge angle) of the discharge flow of molten steel can be easily changed, so that the structure of the immersion nozzle can be simplified and, for example, a conventional box Since there is no need to provide a part, both refractory and manufacturing costs can be reduced, which is economical.
[0068]
In particular, an immersion nozzle according to claim 2, and claim10In the described continuous casting method, the ratio L1 / D1 between the protrusion length L1 of the eaves portion and the inner diameter D1 of the cylindrical portion, and the ratio W / D1 of the eaves portion width W and the inner diameter D1 of the cylindrical portion are respectively set. Therefore, it is possible to further suppress the formation of the downward flow and to suppress and further prevent the bubbles and inclusions from entering the deep part of the slab. Thereby, diffusion of the molten steel discharged from the discharge port can be suppressed, further prevented, and a more uniform flow can be achieved.
[0069]
An immersion nozzle according to claim 3, and claim11In the described continuous casting method, the ratio L2 / D1 between the flow path length L2 from the base end of the discharge port to the tip of the eaves portion and the inner diameter D1 of the cylindrical portion is set, so that the downward flow is formed. Can be further suppressed, and air bubbles and inclusions can be suppressed and further prevented from penetrating into the deep part of the slab, and a high quality casting can be produced.
[0070]
Claim1Immersion nozzle according to claim, and claim8In the continuous casting method described, since each discharge port is provided with a discharge portion formed with a plurality of small holes capable of discharging molten steel, the discharge flow can be widely dispersed by the plurality of small holes, The flow velocity of the molten steel to be discharged can be reduced. Thereby, the flow of the molten steel discharged from a discharge part can be made into the flow which is slow and does not have a drift.
[0071]
Claim4Immersion nozzle according to claim, and claim12In the continuous casting method described, since the ratio L3 / D1 between the flow path length L3 from the front end of the discharge portion to the tip of the eaves portion and the inner diameter D1 of the cylindrical portion is set, the downward flow is formed. Further suppressing, it is possible to suppress and further prevent bubbles and inclusions from penetrating into the deep part of the slab, thereby producing a high quality casting change.
[0072]
Claim1Immersion nozzle according to claim, and claim8In the described continuous casting method, since the ratio S1 / S2 between the inner cross-sectional area S1 of the discharge port on one side and the total cross-sectional area S2 of the plurality of small holes is set, the flow rate of the molten steel discharged from each small hole is set to It can be made uniform and the adverse effect of the reverse flow can be suppressed.
[0073]
Claim1Immersion nozzle according to claim, and claim8In the described continuous casting method, the pressure loss due to the small holes can be increased to reduce the flow velocity of the molten steel, and the secondary meniscus position of the molten steel can be raised, so the pressure of the molten steel between the upper end and the lower end of the discharge portion The difference can be reduced, and the flow rate of the molten steel can be made uniform in the height direction of the discharge part. This eliminates fluctuations in the pressure loss of the molten steel and combines the discharge flow of molten steel from the discharge port, strengthening the discharge flow, suppressing the downward and upward flow of molten steel that collides with the inner wall of the mold and suppresses the flow of bubbles. And the penetration of inclusions into the deep part can be prevented.
[0074]
Claim5Immersion nozzle according to claim, and claim13In the described continuous casting method, the flow rate of molten steel discharged from a plurality of small holes can be reduced, and further, for example, the entrapment depth of powder, bubbles and inclusions can be made shallower than before, so that bubble defects and High quality slabs with no inclusion defects can be produced.
[0075]
Claim1Immersion nozzle according to claim, and claim8In the described continuous casting method, since the material of the discharge part is mainly dolomite, for example, the through hole is made of Al.₂O_ThreeEven if it adheres to the inner surface of the through-hole, Al₂O_ThreeSince a CaO-based liquid phase is formed and is flowed downstream by molten steel flowing through the through-holes, it is possible to prevent clogging of small holes due to alumina-based inclusions as in the past, and to improve the quality of the slab to be manufactured .
[0077]
Claim6Immersion nozzle according to claim, and claim14In the described continuous casting method, since the reduced diameter portion is provided in the portion excluding the lower portion of the cylindrical portion, the dropping force of the molten steel falling into the cylindrical portion can be absorbed by the reduced diameter portion, and the discharge flow that has been generated conventionally can be absorbed. It is possible to suppress drift and manufacture a slab having good quality.
[0078]
Claim7Immersion nozzle according to claim, and claim15In the continuous casting method described above, since the dropping force of the molten steel falling into the cylindrical portion can be absorbed by the rectifying member, and the falling flow of the molten steel passing through the rectifying member can be made uniform by the respective through holes of the rectifying member, it is generated conventionally. It is possible to further suppress the uneven flow of the discharge flow, and to produce a slab having good quality.
[0079]
Claim9In the described continuous casting method, by controlling the inclination angle of the eaves part and the immersion depth of the immersion nozzle in the molten steel in the mold, the speed of the upward and downward flow of the molten steel discharged from the discharge port is suppressed. As a result, it is possible to suppress defects due to fluctuations in the molten metal surface due to upward flow, powder entrainment, intrusion of bubbles and inclusions due to downward flow into the deep part of the slab, and high quality slabs can be manufactured. . Moreover, since there is no drift in the discharge flow of molten steel, for example, the inclination angle of the eaves can be set in a wider range than before, and at the same time the immersion depth can be set in the range of 150 to 350 mm from the meniscus position, enabling stable high speed casting. And increase productivity.
[Brief description of the drawings]
FIGS. 1A and 1B are a side sectional view and a plan view, respectively, of an immersion nozzle according to a first embodiment of the present invention.
FIG. 2 is a side sectional view of an immersion nozzle according to a second embodiment of the present invention.
FIG. 3 is a side sectional view of an immersion nozzle according to a third embodiment of the present invention.
4A and 4B are a side sectional view and a plan view of an immersion nozzle according to a fourth embodiment of the present invention, respectively.
FIG. 5 is a front view of a discharge unit of the immersion nozzle.
FIG. 6 is an explanatory diagram of a continuous casting method using an immersion nozzle according to the first embodiment of the present invention.
FIGS. 7A to 7C are explanatory diagrams of the usage state of the immersion nozzle according to the first conventional example, the explanatory diagrams of the usage state of the immersion nozzle according to the second conventional example, and the first embodiment. It is explanatory drawing of the use condition of the immersion nozzle which concerns on.
FIG. 8 is an explanatory diagram of the amount of bubble intrusion in the manufactured slab.
FIGS. 9A and 9B are explanatory diagrams of the usage state of the immersion nozzle according to the first conventional example, and are explanatory diagrams of the usage state of the immersion nozzle according to the second embodiment, respectively.
FIG. 10 is an explanatory diagram of the amount of bubble penetration in the manufactured slab.
FIG. 11 is an explanatory diagram showing a relationship between a defect occurrence index and a casting speed of a manufactured slab.
[Explanation of symbols]
10: immersion nozzle, 11: molten steel, 12: cylindrical part, 13, 14: discharge port, 15, 16: eaves part, 20: cylindrical part, 21: hot water surface position, 22: reduced diameter part, 23: immersion Nozzle, 24: cylindrical part, 25: rectifying member, 26: immersion nozzle, 27: locking part, 28: through-hole, 30: immersion nozzle, 31: cylindrical part, 32, 33: discharge port, 34, 35 : Eaves part, 36: small hole, 37, 38: discharge part, 40: tundish, 41: mold, 42: support segment, 43: solidified shell, 44: segment under light pressure, 45: pinch roll, 46: slab , 50: immersion nozzle, 51, 52: discharge port, 53, 54: eaves portion, 55: cylindrical portion, 56, 57: discharge port, 58: immersion nozzle, 60: cylindrical portion, 61, 62: discharge port 63, 65: immersion nozzle, 66, 67: discharge port

Claims (15)

A cylindrical portion which molten steel passes from top to bottom, is provided in the lower portion of the cylindrical portion, possess a discharge port wherein the molten steel in the horizontal direction to enable discharge of the right and left pair, a lower portion of the cylindrical portion In the immersion nozzle in which the ratio D2 / D1 between the inner diameter D1 of the removed portion and the interval D2 between the discharge ports is 0.8 to 1.2 ,
At least one or both of the upper and lower portions of each discharge port is provided with an eaves portion capable of guiding the flow of the molten steel discharged from each discharge port, and the molten steel is discharged to the discharge port. A discharge portion having a plurality of possible small holes is provided, and a ratio S1 / S2 between the inner cross-sectional area S1 of the discharge port on one side and the total cross-sectional area S2 of the plurality of small holes is 2 to 5. 5 and the ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion is 2 to 8,
Furthermore, the discharge part uses dolomite clinker as a part of the aggregate, the mass ratio W1 / W2 of the CaO component content W1 and the MgO component content W2 is 0.46 to 3.0, and MgO comprise components 30 to 70 wt%, yet contains 1 to 10 wt% of carbon component, characterized Rukoto each content of SiO ₂ and Fe ₂ O ₃ is it consists of a refractory material comprising a both 3 wt% or less Immersion nozzle.   The immersion nozzle according to claim 1, wherein a ratio L1 / D1 between a protruding length L1 of the eaves portion and the inner diameter D1 of the tubular portion is 0.5 to 2, and the width W of the eaves portion and the The immersion nozzle, wherein the ratio W / D1 of the cylindrical portion to the inner diameter D1 is 1 to 3.   The immersion nozzle according to any one of claims 1 and 2, wherein a flow path length L2 from a base end of the discharge port to a tip end of the eaves portion and the inner diameter D1 of the cylindrical portion. An immersion nozzle, wherein the ratio L2 / D1 is 1-2. The immersion nozzle according to any one of claims 1 and 2 , wherein a ratio between a flow path length L3 from a front end of the discharge part to a tip of the eaves part and the inner diameter D1 of the cylindrical part. L3 / D1 is 1-2, the immersion nozzle characterized by the above-mentioned. The immersion nozzle according to any one of claims 1 to 4 , wherein a ratio S3 / S2 between a total cross-sectional area S2 of the plurality of small holes and an inner cross-sectional area S3 of the cylindrical portion is 0.5 to 1. A submerged nozzle characterized in that it is .5. The immersion nozzle according to any one of claims 1 to 5 , wherein a reduced diameter portion is provided in a portion excluding a lower portion of the cylindrical portion. The immersion nozzle according to any one of claims 1 to 6 , wherein a portion other than a lower portion of the cylindrical portion is provided with a rectifying member having a plurality of through holes through which the molten steel passes. A featured immersion nozzle. Ratio D2 / of the inner diameter D1 of the cylindrical part through which the molten steel passes from the top to the bottom and the interval D2 between the left and right discharge ports provided at the lower part of the cylindrical part and capable of discharging the molten steel in the lateral direction D1 is 0.8 to 1.2, and at least one or both of the upper and lower portions of each discharge port is provided with an eaves portion capable of guiding the flow of the molten steel discharged from each discharge port , And the discharge part in which the some small hole which can discharge the said molten steel was formed in the said discharge port is provided, and internal cross-sectional area S1 of the said discharge port of one side, and total cross-sectional area S2 of the said some small hole The ratio S1 / S2 is 2 to 5.5, the ratio D1 / d between the inner diameter d of the small hole and the inner diameter D1 of the cylindrical portion is 2 to 8, and the discharge section is a dolomite clinker Is used as part of the aggregate, and the mass of the CaO component content W1 and the MgO component content W2 W1 / W2 is 0.46 to 3.0, and comprises an MgO component 30 to 70 mass%, yet contains 1 to 10 wt% of carbon component, 3 both the content of SiO ₂ and Fe ₂ O ₃ mass The molten steel is poured into a mold through an immersion nozzle composed of a refractory that is less than or equal to%, and the molten steel is solidified and pulled out from the mold at a casting speed of 0.6 m / min or more. Continuous casting method. 9. The continuous casting method according to claim 8 , wherein an inclination angle of the eaves portion is set in a range of 10 degrees upward to 35 degrees downward with respect to a horizontal state, and the discharge port is set in a range of 150 to 350 mm from a meniscus position. A continuous casting method, wherein the molten steel is immersed in the molten steel, and an argon gas blowing rate is 0.2 to 20 NL / min. In continuous casting method according to any one of claims 8 and 9, and the ratio L1 / D1 of the inner diameter D1 of the cylindrical portion and the projecting length L1 of the eaves portion is a 0.5-2 The continuous casting method is characterized in that a ratio W / D1 of the width W of the eaves part and the inner diameter D1 of the cylindrical part is 1 to 3. In the continuous casting method according to any one of claims 8 to 10 , the flow path length L2 from the base end of the discharge port to the tip of the eaves part, and the inner diameter D1 of the cylindrical part The ratio L2 / D1 of the continuous casting method is 1-2. The continuous casting method according to any one of claims 8 to 10 , wherein a flow path length L3 from a front end of the discharge part to a tip of the eaves part and the inner diameter D1 of the cylindrical part Ratio L3 / D1 is 1-2, The continuous casting method characterized by the above-mentioned. The continuous casting method according to any one of claims 8 to 12 , wherein a ratio S3 / S2 between the total cross-sectional area S2 of the plurality of small holes and the inner cross-sectional area S3 of the cylindrical portion is 0.5 to 0.5. A continuous casting method characterized by being 1.5. The continuous casting method according to any one of claims 8 to 13 , wherein a reduced diameter portion is provided in a portion excluding a lower portion of the cylindrical portion. The continuous casting method according to any one of claims 8 to 14 , wherein a portion of the cylindrical portion excluding a lower portion is provided with a rectifying member having a plurality of through holes through which the molten steel passes. A continuous casting method characterized by the above.

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