JP3817188B2 - Thin slab manufacturing method using twin drum type continuous casting machine having scum weir and scum weir - Google Patents

Thin slab manufacturing method using twin drum type continuous casting machine having scum weir and scum weir Download PDF

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JP3817188B2
JP3817188B2 JP2002070062A JP2002070062A JP3817188B2 JP 3817188 B2 JP3817188 B2 JP 3817188B2 JP 2002070062 A JP2002070062 A JP 2002070062A JP 2002070062 A JP2002070062 A JP 2002070062A JP 3817188 B2 JP3817188 B2 JP 3817188B2
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molten metal
scum
scum weir
weir
drum
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JP2003266154A (en
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英明 山村
正 池本
友英 竹内
英明 小林
渡 大橋
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Nippon Steel Corp
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Nippon Steel Corp
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【０００１】
【発明の属する技術分野】
本発明は、相対する一対の冷却ドラムの周面の一部に湯溜まり部を形成し、そこに注入した溶融金属を冷却・凝固せしめて、薄肉鋳片を製造する双ドラム式連続鋳造方式による薄肉鋳片の鋳造方法において、スカム堰を用いて薄肉鋳片を連続鋳造する鋳造方法に関するものである。
【０００２】
【従来の技術】
近年、溶湯等の溶融金属から最終形状に近い数ｍｍから数十ｍｍの肉厚鋳片を直接製造する方法が注目されている。この方法によれば、従来法のような圧延工程を省略できる、あるいは、圧延工程での負荷コストを軽減できるので、工程や設備の簡略化を図ることができる。
【０００３】
この種の連続鋳造方法としては、互いに逆方向に回転する一対の冷却ドラムの間に湯溜まり部を形成する双ドラム方式、冷却ドラムとベルトの間に湯溜まり部を形成するドラムベルト方式、一本の冷却ドラムの周面の一部に湯溜まりを形成する単ドラム方式がある。これらの方式においては、いずれも冷却ドラムの周囲に接する部分で、溶融金属の冷却・凝固が進行し、凝固シェルを生成する。従って、この凝固シェルを安定して成長せしめることが良好な表面性状を有する鋳片を製造することにおいてきわめて重要である。
【０００４】
双ドラム式連続鋳造装置では、図１に示すように、軸を水平にし互いに接近して並行に設置され、且つ、互いに逆方向に回転する一対の冷却ドラム２ａ、２ｂと、冷却ドラム２ａ、２ｂの両端面に圧着されたサイド堰３ａ、３ｂとを主要な構成部材としている。冷却ドラム２ａ、２ｂとサイド堰３ａ、３ｂとで形成された湯溜まり部７の上方にはシールチャンバー８が設けられ、シールチャンバー８内には不活性ガスが供給される。湯溜まり部７にタンディッシュ１１から浸漬ノズル９を介し溶融金属１を連続的に供給することにより、溶融金属１は冷却ドラム２ａ、２ｂとの接触部で凝固シェル４ａ、４ｂを形成し、凝固シェル４ａ、４ｂは冷却ドラム２ａ、２ｂの回転に伴って回転ドラム表面に同期して移動し、キッシングポイント６で両側の凝固シェルが圧着され薄肉鋳片５となる。
【０００５】
湯溜まり部７の溶融金属中には脱酸生成物その他の酸化物が含まれており、この酸化物は湯溜まり部６において浮上し、溶融金属１表面にスカムとして浮遊することとなる。鋳造を行うに際し、湯だまり部７に注入された溶融金属１の表面に浮遊する酸化物（スカム）が冷却ドラム２の表面と溶融金属１の表面との接触部１２に到達すると、冷却ドラム２ａ、２ｂの回転とともに、流れ込む溶融金属に付随して引き込まれ、鋳片の凝固シェル４の表面に付着して鋳片に取り込まれる場合がある。この結果、鋳造された薄肉鋳片に割れやスカム疵、さらに圧延、焼鈍、酸洗後の製品で割れが原因となったヘゲ、スカム疵、光沢むらが発生し、鋳片および製品の品質が損なわれる。
【０００６】
特開平６−３３９７５４号公報には、湯溜まり内に図１に示すようなスカム堰１０ａ、１０ｂを配し、スカム堰１０ａ、１０ｂとサイド堰３ａ、３ｂに囲まれたスペースに、スカムを溶融状態に保つフラックスを添加しながら溶湯１を注入し、溶融状のスカムを除去しながら鋳造を行う方法が記載されている。
【０００７】
【発明が解決しようとする課題】
溶融金属１の中の酸化物は、スカム堰１０ａ、１０ｂの間の空間に浮上するのみならず、スカム堰１０ａとドラム２ａとの間の空間にも浮上する。このような位置に浮上したスカムはスカム堰１０ａ、１０ｂによって捕獲することはできず、このようなスカムを巻き込むことによって欠陥が生じる。また、溶融状のスカムを除去することは困難である。本発明は、スカムの巻き込みに起因する鋳片表面の割れやスカム疵や製品板における光沢むらの発生を防止して、表面性状の優れた薄肉鋳片さらにこれを圧延して得られる表面性状の優れた鋼板を製造するものである。
【０００８】
【課題を解決するための手段】
即ち、本発明の要旨とするところは以下のとおりである。
（１）一対の冷却ドラム２の周囲の一部とサイド堰３で形成した湯溜まり部７に溶融金属１を注入し、溶融金属１を冷却ドラム２の回転周面で冷却、凝固しながら薄肉鋳片５を連続鋳造する鋳造方法において溶融金属中に配置するスカム堰１０であって、溶融金属と反応あるいは溶解して溶融金属の表面張力を低下させる元素の化合物の含有量が３０ｍｏｌ％以下である材料を使用してなることを特徴とするスカム堰。
（２）前記溶融金属が溶鋼であり、表面張力を下げる元素がＢ、Ｎ、Ｓであることを特徴とする（１）に記載のスカム堰。
（３）一対の冷却ドラム２の周囲の一部とサイド堰３で形成した湯溜まり部７に溶融金属１を注入し、溶融金属１を冷却ドラム２の回転周面で冷却、凝固しながら薄肉鋳片５を連続鋳造する鋳造方法において溶融金属中に配置するスカム堰１０であって、溶融金属と反応あるいは溶解して溶融金属の表面張力を上昇させる元素の化合物を１０ｍｏｌ％以上含有する材料を使用してなることを特徴とするスカム堰。
（４）前記溶融金属が溶鋼であり、表面張力を上昇させる元素がＷ、Ｔｉであることを特徴とする（３）に記載のスカム堰。
（５）ＺｒＯ2、Ａｌ2Ｏ3、ＭｇＯの少なくとも１種類を主成分とする材料を使用してなることを特徴とする（１）〜（４）に記載のスカム堰。
（６）上記（１）〜（５）に記載のスカム堰１０を使用して薄肉鋳片を鋳造することを特徴とする双ドラム式連続鋳造方法。
【０００９】
【発明の実施の形態】
本発明者は図１に示す双ドラム式連続鋳造機において種々の材質のスカム堰１０を用いて鋳造試験を行った。本発明はその結果を基になされたものである。鋳造中に湯溜り部７の溶鋼の湯面にスカムが浮上してくる。この状況下において、スカム堰１０にＢＮのように溶鋼と反応して表面張力を低下させるＢやＮが溶鋼中に溶解する成分を含有する材質のものを用いると、スカム堰近傍の溶鋼の表面張力を低下させる。すると、スカム堰近傍の湯面上にあるスカムは、スカム堰近傍からはじかれるようにスカム堰から離れていく。この結果、冷却ドラム２とスカム堰１０との間の湯面において、はじかれたスカムは、冷却ドラム２の回転とともに流れ込む溶鋼に付随して引き込まれる現象が観察される。即ち、スカム堰の材質として溶融金属の表面張力を低下させる元素を含有したものを用いることにより、スカム堰近傍の溶融金属の表面張力が低下し、湯溜まり部の溶融金属表面において、ドラムと溶融金属表面の接触部１２付近の溶融金属とスカム堰近傍の溶融金属との間に表面張力勾配が生じて、スカム堰から接触部１２に向かう表面流動が生じるためであると考えられる。この流動によってスカムが接触部１２に移動していくと推定される。
【００１０】
一方、スカム堰に表面張力を低減する元素を含まない場合には溶融金属の表面張力の低下が起こらず、冷却ドラム近傍の湯面上にあるスカムは、ドラムに向かって移動する現象が起こりにくくなる。この結果、スカムは湯溜まりの中央部に移動して集積し、ドラムに引き込まれてのスカムの巻き込みは激減する。
【００１１】
従って、スカム堰１０には表面張力を下げる作用の大きい元素（溶融金属が溶鋼である場合にはＢ、Ｎ、Ｓ）を含まないことが望ましいが、これら元素の化合物の含有量が３０ｍｏｌ％以下であれば実際上問題がないので、これらの含有量は３０ｍｏｌ％以下とした。化合物としてはセラッミックスに用いられるＢＮ、ＡｌＮ、Ｓｉ3Ｎ4、Ｂ4Ｃ、ＭｏＳ2等である。表面張力を低下させる元素の化合物の含有量は、１０ｍｏｌ％以下であればより好ましい。５ｍｏｌ％以下であればさらに好ましい。また、主成分としては溶融金属と反応しにくいＡｌ2Ｏ3，ＺｒＯ2，ＭｇＯであることが望ましい。
【００１２】
スカム堰１０に溶融金属の表面張力を上昇させる元素を含む場合には、元素が溶融金属中に溶解することによって溶融金属の表面張力が上昇して、スカム堰近傍の溶融金属の表面張力を上昇させる。すると、湯面上に浮遊するスカムがスカム堰１０に引き寄せられ、冷却ドラム２近傍の湯面上にあるスカムはドラム２から離れていく。この結果、スカムはスカム堰近傍に移動して集積し、ドラムに引き込まれてのスカムの巻き込みは激減する。これは、スカム堰近傍の溶融金属の表面張力が上昇し、ドラムと溶融金属表面の接触部１２付近の溶融金属とスカム堰近傍の溶融金属との間に表面張力勾配が生じて、ドラム界面からスカム堰に向かう表面流動が生じるためであると考えられる。この流動によってスカムがスカム堰側に移動していくと推定される。
【００１３】
従って、スカム堰１０を構成する材料には表面張力を上げる作用の大きい元素（溶融金属が溶鋼である場合にはＷ、Ｔｉ）を含むことが望ましく、これら元素の化合物を１０ｍｏｌ％以上含有すると効果が得られるので、含有量は１０ｍｏｌ％以上とした。表面張力を上げる作用を有する化合物としてはＷＯ、ＴｉＯ2が望ましい。表面張力を上昇させる元素の化合物の含有量は、３０ｍｏｌ％以上であればより好ましい。５０ｍｏｌ％以上であればさらに好ましい。残部は表面張力の低下元素を含まず、溶融金属と反応しにくいＡｌ2Ｏ3，ＺｒＯ2，ＭｇＯを主体とすることが望ましい。
【００１４】
また、スカム堰１０をドラム端部以外の部分に限定することによって、ドラム端部では、スカムがドラム界面に引き込まれるので、湯溜まり中央部へのスカムの集積が減少し、これらスカムが湯面変動や波立ち等の鋳造状態の変動によって巻き込まれて発生するスカム疵を低減させることが可能となる。この際、中間成品である帯状鋼板から成品の薄鋼板を製造するには、例えば、成品となる薄鋼板の板幅寸法を一定に揃えるために、中間成品である帯状鋼板の幅方向の両端部をトリミングにより切り落して屑鋼とし、残部を成品の薄鋼板にする。従って、中間成品である帯状鋼板においては、多数の表面疵が幅方向の両端部のトリミング代内に存在していても、成品の品質上の支障にはならない。
【００１５】
本発明を用いることにより、たとえ湯溜まり部７の溶融金属中に存在する酸化物の量が多くても、鋳片に巻き込まれるスカムの量が大幅に低減する。従って、従来おこなっていたスカム量低減を目的とした溶鋼清浄化のための精錬や酸化防止のためのシールを軽減することが可能となる。
【００１６】
【実施例】
ＳＵＳ３０４鋼を図１に示す双ドラム連続鋳造機により表１に示す組成のスカム堰１０を用いて鋳造し、薄肉鋳片を製造した。鋳造条件は以下のとおりである。
鋳造ドラムの寸法：直径１３００ｍｍ、幅１０００ｍｍ
鋳造ドラムの構造：内部水冷式、表面Ｎｉメッキの銅製
鋳造鋼種 ：ＳＵＳ３０４
鋳造速度 ：６０ｍ／分
鋳片厚 ：３ｍｍ。
【００１７】
この鋳片に発生した割れおよびスカム疵の発生率を調査した。この鋳片は、幅２５ｍｍをトリミングした後、常法によって冷延、熱処理、酸洗を行い成品とした。その製品に発生したスカム疵および鋳片の割れが原因であるヘゲ疵の発生率、表面光沢を調査した。評点は、１：全くなし、２：認められる、３：著しく認められるである。
【００１８】
調査結果を表２に示す。Ｎｏ１〜１４は本発明の実施例である。鋳片ではスカム疵、割れは認められず、製品板でもスカム疵、ヘゲ疵は認められず、光沢むらも低減している。Ｎｏ１５、１６は比較材である。Ｎｏ１５は表面張力低下元素の含有量がはずれたものである。Ｎｏ１６は表面張力低下元素と表面張力上昇元素の両者を含有し、表面張力上昇元素の含有量がはずれたものである。比較材は鋳片にスカム疵が認められ、割れが生じていた。さらに製品板でもスカム疵、ヘゲ疵、光沢むらが認められた。
【００１９】
【表１】

Figure 0003817188
【００２０】
【表２】
Figure 0003817188
【００２１】
【発明の効果】
本発明によると、双ドラム式連続鋳造による薄肉鋳片の製造において、湯溜り部の溶融金属の湯面に浮上しているスカムを、ドラム近傍から離れた位置に移動させて、ドラム表面への巻き込みを防止することが可能となり、鋳片の割れやスカム疵、製品板での光沢むらの発生を防止して、表面性状の優れた薄肉鋳片およびそれを圧延して得られる製品板を製造することができる。また、本発明によると、従来おこなっていたスカム量低減を目的とした溶湯清浄化のための精錬や酸化防止のためのシールを軽減することが可能となる。
【図面の簡単な説明】
【図１】双ドラム式の連続鋳造装置の概略を示す図である。
【符号の説明】
１…溶融金属
２ａ、２ｂ…冷却ドラム（双ドラム）
３ａ、３ｂ…サイド堰
４ａ、４ｂ…凝固シェル
５…薄肉鋳片
６…キッシングポイント
７…湯溜まり
８…シールチャンバー
９…浸漬ノズル
１０ａ、１０ｂ…スカム堰
１１…タンディッシュ
１２ 接触部[0001]
BACKGROUND OF THE INVENTION
The present invention is based on a twin-drum continuous casting method in which a hot water pool is formed on a part of the peripheral surface of a pair of opposing cooling drums, and the molten metal injected therein is cooled and solidified to produce a thin cast piece. The present invention relates to a casting method for continuously casting thin slabs using a scum weir in a thin slab casting method.
[0002]
[Prior art]
In recent years, a method of directly producing a thick cast piece of several mm to several tens mm close to the final shape from a molten metal such as a molten metal has attracted attention. According to this method, the rolling process as in the conventional method can be omitted, or the load cost in the rolling process can be reduced, so that the process and equipment can be simplified.
[0003]
This type of continuous casting method includes a double drum system in which a hot water reservoir is formed between a pair of cooling drums rotating in opposite directions, a drum belt system in which a hot water reservoir is formed between the cooling drum and the belt, There is a single drum system in which a hot water pool is formed on a part of the peripheral surface of the cooling drum of the book. In any of these methods, the molten metal is cooled and solidified at a portion in contact with the periphery of the cooling drum, and a solidified shell is generated. Therefore, it is extremely important to produce a cast slab having a good surface property to stably grow the solidified shell.
[0004]
In the twin-drum type continuous casting apparatus, as shown in FIG. 1, a pair of cooling drums 2a and 2b which are installed in parallel with each other in a horizontal axis and close to each other and rotate in opposite directions to each other, and cooling drums 2a and 2b Side weirs 3a and 3b that are crimped to both end faces are used as main constituent members. A seal chamber 8 is provided above the hot water reservoir 7 formed by the cooling drums 2 a and 2 b and the side weirs 3 a and 3 b, and an inert gas is supplied into the seal chamber 8. By continuously supplying the molten metal 1 from the tundish 11 to the hot water reservoir 7 through the immersion nozzle 9, the molten metal 1 forms solidified shells 4a and 4b at the contact portions with the cooling drums 2a and 2b, and solidifies. The shells 4a and 4b move in synchronization with the surface of the rotating drum as the cooling drums 2a and 2b rotate, and the solidified shells on both sides are pressure-bonded at the kissing point 6 to form a thin cast piece 5.
[0005]
The molten metal in the hot water reservoir 7 contains deoxidation products and other oxides, and this oxide floats in the hot water reservoir 6 and floats on the surface of the molten metal 1 as scum. When performing casting, when oxide (scum) floating on the surface of the molten metal 1 injected into the puddle portion 7 reaches the contact portion 12 between the surface of the cooling drum 2 and the surface of the molten metal 1, the cooling drum 2a. With the rotation of 2b, it may be drawn accompanying the molten metal flowing in, and may adhere to the surface of the solidified shell 4 of the slab and be taken into the slab. As a result, the cast thin-walled slab has cracks and scum defects, as well as whipping, scum defects, and uneven luster caused by cracks in the rolled, annealed and pickled products. Is damaged.
[0006]
In JP-A-6-339754, scum weirs 10a and 10b as shown in FIG. 1 are arranged in a hot water pool, and the scum is melted in a space surrounded by the scum weirs 10a and 10b and the side weirs 3a and 3b. A method is described in which the molten metal 1 is injected while adding a flux for maintaining the state, and casting is performed while removing the molten scum.
[0007]
[Problems to be solved by the invention]
The oxide in the molten metal 1 floats not only in the space between the scum weirs 10a and 10b but also in the space between the scum weir 10a and the drum 2a. The scum that has floated to such a position cannot be captured by the scum weirs 10a and 10b, and defects are caused by entraining such scum. Moreover, it is difficult to remove the molten scum. The present invention prevents the occurrence of cracks on the surface of the slab due to scum entrainment and the occurrence of uneven scum and gloss unevenness on the product plate, and the surface property obtained by rolling the thin slab with excellent surface property. An excellent steel sheet is manufactured.
[0008]
[Means for Solving the Problems]
That is, the gist of the present invention is as follows.
(1) Molten metal 1 is poured into a hot water reservoir 7 formed by a part of the periphery of the pair of cooling drums 2 and the side weir 3, and the molten metal 1 is cooled and solidified on the rotating peripheral surface of the cooling drum 2 to be thin-walled. A scum weir 10 disposed in a molten metal in a casting method for continuously casting a slab 5, wherein the content of an element compound that reacts or dissolves with the molten metal to lower the surface tension of the molten metal is 30 mol% or less. A scum weir characterized by using a certain material.
(2) The scum weir described in (1), wherein the molten metal is molten steel, and the elements that lower the surface tension are B, N, and S.
(3) The molten metal 1 is poured into the hot water reservoir 7 formed by a part of the periphery of the pair of cooling drums 2 and the side weir 3, and the molten metal 1 is cooled and solidified on the rotating peripheral surface of the cooling drum 2. A scum weir 10 disposed in a molten metal in a casting method for continuously casting a slab 5, comprising a material containing 10 mol% or more of a compound of an element that reacts or dissolves with the molten metal to increase the surface tension of the molten metal. A scum weir characterized by being used.
(4) The scum weir described in (3), wherein the molten metal is molten steel, and the elements that increase the surface tension are W and Ti.
(5) The scum weir described in any one of (1) to (4), wherein a material mainly containing at least one of ZrO 2 , Al 2 O 3 , and MgO is used.
(6) A twin-drum continuous casting method, wherein a thin cast piece is cast using the scum weir 10 according to (1) to (5) above.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present inventor conducted a casting test using the scum weir 10 of various materials in the twin drum type continuous casting machine shown in FIG. The present invention has been made based on the results. During the casting, the scum rises on the molten steel surface of the hot water reservoir 7. Under this circumstance, if the scum weir 10 is made of a material containing a component such as BN that reacts with the molten steel to lower the surface tension and dissolves B or N in the molten steel, the surface of the molten steel near the scum weir Reduce tension. Then, the scum on the hot water surface near the scum weir moves away from the scum weir so as to be repelled from the vicinity of the scum weir. As a result, a phenomenon is observed in which the scum repelled on the molten metal surface between the cooling drum 2 and the scum weir 10 is drawn accompanying the molten steel flowing along with the rotation of the cooling drum 2. That is, by using a material containing an element that lowers the surface tension of the molten metal as the material of the scum weir, the surface tension of the molten metal near the scum weir is lowered, and the molten metal surface of the hot water pool is melted with the drum. It is considered that this is because a surface tension gradient occurs between the molten metal near the contact portion 12 on the metal surface and the molten metal near the scum weir, and surface flow from the scum weir toward the contact portion 12 occurs. It is estimated that this flow causes the scum to move to the contact portion 12.
[0010]
On the other hand, when the scum weir does not contain an element that reduces the surface tension, the surface tension of the molten metal does not decrease, and the scum on the molten metal surface near the cooling drum is unlikely to move toward the drum. Become. As a result, the scum moves to the central part of the hot water pool and accumulates, and the scum entrainment drawn into the drum is drastically reduced.
[0011]
Therefore, it is desirable that the scum weir 10 does not contain an element having a large effect of reducing the surface tension (B, N, S when the molten metal is molten steel), but the content of the compound of these elements is 30 mol% or less. If there is no problem in practice, the content thereof is set to 30 mol% or less. Examples of the compound include BN, AlN, Si 3 N 4 , B 4 C, and MoS 2 used for ceramics. The content of the elemental compound that lowers the surface tension is more preferably 10 mol% or less. More preferably, it is 5 mol% or less. The main component is preferably Al 2 O 3 , ZrO 2 , or MgO that does not easily react with the molten metal.
[0012]
When the scum weir 10 contains an element that increases the surface tension of the molten metal, the element dissolves in the molten metal, so that the surface tension of the molten metal increases and the surface tension of the molten metal near the scum weir increases. Let Then, the scum floating on the hot water surface is drawn to the scum weir 10, and the scum on the hot water surface near the cooling drum 2 moves away from the drum 2. As a result, the scum moves and accumulates in the vicinity of the scum weir, and the scum entrainment drawn into the drum is drastically reduced. This is because the surface tension of the molten metal in the vicinity of the scum weir increases, and a surface tension gradient is generated between the molten metal in the vicinity of the contact portion 12 between the drum and the molten metal surface and the molten metal in the vicinity of the scum weir. This is thought to be due to the surface flow toward the scum weir. It is estimated that this flow causes the scum to move to the scum weir side.
[0013]
Therefore, it is desirable that the material constituting the scum weir 10 contains an element having a large effect of increasing the surface tension (W, Ti when the molten metal is molten steel). Therefore, the content was set to 10 mol% or more. WO and TiO 2 are desirable as the compound having the effect of increasing the surface tension. The content of the elemental compound that increases the surface tension is more preferably 30 mol% or more. More preferably, it is 50 mol% or more. The balance is preferably composed mainly of Al 2 O 3 , ZrO 2 , and MgO that do not contain an element that lowers the surface tension and does not easily react with the molten metal.
[0014]
Further, by limiting the scum weir 10 to a portion other than the drum end portion, the scum is drawn into the drum interface at the drum end portion, so that the accumulation of scum in the central portion of the hot water pool is reduced, and these scum It is possible to reduce scum soot that is generated due to fluctuations in the casting state such as fluctuations and undulations. At this time, in order to produce a product thin steel plate from the strip steel plate that is an intermediate product, for example, both end portions in the width direction of the strip steel plate that is an intermediate product in order to uniformize the sheet width dimension of the thin steel plate that is the product Is trimmed to make scrap steel, and the remainder is made into a thin steel plate. Therefore, in the strip-shaped steel plate which is an intermediate product, even if a large number of surface flaws exist within the trimming margins at both ends in the width direction, it does not hinder the quality of the product.
[0015]
By using the present invention, even if the amount of oxide present in the molten metal in the hot water pool 7 is large, the amount of scum that is caught in the slab is greatly reduced. Therefore, it is possible to reduce the refining for cleaning the molten steel and the seal for preventing oxidation, which have been conventionally performed for the purpose of reducing the amount of scum.
[0016]
【Example】
SUS304 steel was cast using a scum weir 10 having the composition shown in Table 1 by a twin drum continuous casting machine shown in FIG. 1 to produce a thin cast slab. The casting conditions are as follows.
Casting drum dimensions: Diameter 1300mm, width 1000mm
Casting drum structure: Internal water-cooled, surface Ni-plated copper casting steel type: SUS304
Casting speed: 60 m / min. Cast slab thickness: 3 mm.
[0017]
The occurrence rate of cracks and scum defects in the slab was investigated. This slab was trimmed to a width of 25 mm, and then cold rolled, heat treated, and pickled to obtain a finished product. We investigated the rate of occurrence of scum flaws and scabs on the products, and the occurrence of bald wrinkles caused by cracks in the slab, and the surface gloss. The grades are 1: none at all, 2: recognized, 3: markedly recognized.
[0018]
The survey results are shown in Table 2. Nos. 1 to 14 are examples of the present invention. No scum flaws or cracks were observed on the slab, and no scum flaws or bald spots were observed on the product plate, and uneven gloss was reduced. No. 15 and 16 are comparative materials. No. 15 is one in which the content of the surface tension reducing element is off. No16 contains both the surface tension decreasing element and the surface tension increasing element, and the content of the surface tension increasing element is off. The comparative material had scum flaws on the slab and cracks. In addition, scum wrinkles, bald wrinkles, and uneven gloss were also found on the product plates.
[0019]
[Table 1]
Figure 0003817188
[0020]
[Table 2]
Figure 0003817188
[0021]
【The invention's effect】
According to the present invention, in the production of a thin cast piece by twin-drum type continuous casting, the scum floating on the molten metal surface of the molten metal pool is moved to a position away from the vicinity of the drum, It is possible to prevent entrainment and prevent the occurrence of cracks in slabs, scum flaws, and uneven luster on product plates, and manufacture thin cast slabs with excellent surface properties and product plates obtained by rolling them. can do. Further, according to the present invention, it is possible to reduce the refining for cleaning the molten metal for the purpose of reducing the amount of scum and the seal for preventing oxidation which have been conventionally performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a twin drum type continuous casting apparatus.
[Explanation of symbols]
1 ... Molten metal 2a, 2b ... Cooling drum (double drum)
3a, 3b ... side weirs 4a, 4b ... solidified shell 5 ... thin slab 6 ... kissing point 7 ... water pool 8 ... sealing chamber 9 ... immersion nozzle 10a, 10b ... scum weir 11 ... tundish 12 contact part

Claims (6)

一対の冷却ドラムの周囲の一部とサイド堰で形成した湯溜まり部に溶融金属を注入し、該溶融金属を該冷却ドラムの回転周面で冷却、凝固しながら薄肉鋳片を連続鋳造する鋳造方法において溶融金属中に配置するスカム堰であって、溶融金属と反応あるいは溶解して溶融金属の表面張力を低下させる元素の化合物の含有量が３０ｍｏｌ％以下である材料を使用してなることを特徴とするスカム堰。Casting by injecting molten metal into a hot water pool formed by a part of the periphery of a pair of cooling drums and side weirs, and continuously casting thin slabs while cooling and solidifying the molten metal on the rotating peripheral surface of the cooling drum A scum weir disposed in a molten metal in the method, wherein a material having a compound content of 30 mol% or less that reacts or dissolves with the molten metal to lower the surface tension of the molten metal is used. Characteristic scum weir. 前記溶融金属が溶鋼であり、表面張力を下げる元素がＢ、Ｎ、Ｓであることを特徴とする請求項１に記載のスカム堰。2. The scum weir according to claim 1, wherein the molten metal is molten steel, and the elements that lower the surface tension are B, N, and S. 3. 一対の冷却ドラムの周囲の一部とサイド堰で形成した湯溜まり部に溶融金属を注入し、該溶融金属を該冷却ドラムの回転周面で冷却、凝固しながら薄肉鋳片を連続鋳造する鋳造方法において溶融金属中に配置するスカム堰であって、溶融金属と反応あるいは溶解して溶融金属の表面張力を上昇させる元素の化合物を１０ｍｏｌ％以上含有する材料を使用してなることを特徴とするスカム堰。Casting by injecting molten metal into a hot water pool formed by a part of the periphery of a pair of cooling drums and side weirs, and continuously casting thin slabs while cooling and solidifying the molten metal on the rotating peripheral surface of the cooling drum A scum weir disposed in a molten metal in the method, characterized by using a material containing 10 mol% or more of a compound of an element that reacts or dissolves with the molten metal to increase the surface tension of the molten metal. Scum weir. 前記溶融金属が溶鋼であり、表面張力を上昇させる元素がＷ、Ｔｉであることを特徴とする請求項３に記載のスカム堰。The scum weir according to claim 3, wherein the molten metal is molten steel, and the elements that increase the surface tension are W and Ti. ＺｒＯ2、Ａｌ2Ｏ3、ＭｇＯの少なくとも１種類を主成分とする材料を使用してなることを特徴とする請求項１乃至４のいずれかに記載のスカム堰。 ZrO 2, Al 2 O 3, MgO of at least one scum dams according to any one of claims 1 to 4, characterized by comprising using a material mainly containing. 請求項１乃至５のいずれかに記載のスカム堰を使用して薄肉鋳片を鋳造することを特徴とする双ドラム式連続鋳造方法。A twin-drum type continuous casting method, wherein a thin cast piece is cast using the scum weir according to any one of claims 1 to 5.
JP2002070062A 2002-03-14 2002-03-14 Thin slab manufacturing method using twin drum type continuous casting machine having scum weir and scum weir Expired - Fee Related JP3817188B2 (en)

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