JP2009039745A - Powder for continuous casting, and method for continuously casting steel - Google Patents
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本発明は、Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼の連続鋳造に用いる連続鋳造用パウダー、及び、該高Ｓｉ高Ａｌ鋼の連続鋳造方法に関するものである。 The present invention relates to a powder for continuous casting used for continuous casting of a high Si high Al steel having a Si concentration of 2% by mass or more and an Al concentration of 0.5% by mass or more, and a continuous casting method of the high Si high Al steel. Is.
無方向性電磁鋼板は鉄損を低減するため、析出物形成元素のＣ、Ｓ、Ｎ等の高純化を図ることでヒステリシス損の低減を図るとともに、鋼中Ｓｉ、Ａｌ濃度を高めることで渦電流損を低減させている。そのため、このような用途の鋼は、Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼となっている。 Non-oriented electrical steel sheets reduce iron loss, so that the loss of hysteresis loss is reduced by increasing the purity of the precipitate-forming elements C, S, N, etc., and the vortex is increased by increasing the concentration of Si and Al in the steel. Current loss is reduced. Therefore, the steel for such use is a high Si high Al steel having a Si concentration of 2% by mass or more and an Al concentration of 0.5% by mass or more.
鋼の連続鋳造においては、鋳型内の溶鋼表面に連続鋳造用パウダーを投入し、この連続鋳造用パウダーが溶融して溶融スラグを形成する。溶融スラグは鋳型と凝固シェルとの間に流入し、凝固シェルの潤滑を図るとともに、凝固シェルから鋳型への抜熱特性を制御する働きを有する。連続鋳造用パウダーは、ＣａＯ、ＳｉＯ2、Ａｌ2Ｏ3をはじめとする酸化物に、フッ化物及び炭素源を含有している。 In continuous casting of steel, powder for continuous casting is put on the surface of molten steel in a mold, and the powder for continuous casting melts to form molten slag. The molten slag flows between the mold and the solidified shell, and serves to lubricate the solidified shell and to control the heat removal characteristics from the solidified shell to the mold. The powder for continuous casting contains fluoride and a carbon source in oxides such as CaO, SiO 2 and Al 2 O 3 .
Ａｌ濃度が０．５質量％以上の高Ａｌ鋼を連続鋳造する際には、パウダーが溶融して形成された溶融スラグ中のＳｉＯ2が、鋼中のＡｌによって還元される反応、即ち下記の（１）式の反応が顕著になる。
４［Ａｌ］＋３（ＳｉＯ2）→２（Ａｌ2Ｏ3）＋３［Ｓｉ］ （１）
When continuously casting a high Al steel having an Al concentration of 0.5% by mass or more, SiO 2 in the molten slag formed by melting the powder is reduced by Al in the steel, that is, The reaction of formula (1) becomes remarkable.
4 [Al] +3 (SiO 2 ) → 2 (Al 2 O 3 ) +3 [Si] (1)
上記（１）式の反応によって溶融スラグ中のＡｌ2Ｏ3濃度が上昇し、同時にＳｉＯ2濃度が低下して塩基度が上昇する。このような溶融スラグの成分変化に伴い、溶融スラグが鋳型と凝固シェルとの間に流入して温度が低下した際に、高融点結晶であるゲーレナイト（２ＣａＯ・Ａｌ2Ｏ3・ＳｉＯ2）が晶出するようになる。ゲーレナイトの晶出が起こると、鋳型内壁の湯面近傍に巨大なスラグベアが生じ、鋳型と凝固シェル間への溶融スラグの流入を阻害し、鋳型と凝固シェルとの間の焼き付きが生じる。その結果、連続鋳造鋳片の表面に凹みや割れなどの表面欠陥が発生し、さらに焼き付きが修復されない場合には凝固シェルが鋳型に拘束され、拘束性ブレークアウトの発生にいたる。 By the reaction of the above formula (1), the Al 2 O 3 concentration in the molten slag increases, and at the same time, the SiO 2 concentration decreases and the basicity increases. When the molten slag flows between the mold and the solidified shell and the temperature is lowered due to such a change in the composition of the molten slag, gelenite (2CaO.Al 2 O 3 .SiO 2 ) that is a high melting point crystal is formed. It begins to crystallize. When crystallization of gehlenite occurs, a huge slag bear is generated in the vicinity of the molten metal surface of the inner wall of the mold, which inhibits the inflow of molten slag between the mold and the solidified shell, and seizure occurs between the mold and the solidified shell. As a result, surface defects such as dents and cracks occur on the surface of the continuous cast slab, and when the seizure is not repaired, the solidified shell is restrained by the mold, resulting in the occurrence of a restrictive breakout.
特許文献１においては、Ａｌを０．５％以上含有する鋼の連続鋳造用として、ＳｉＯ2：４０〜６０％、ＣａＯ：１５〜３５％を含有し、さらにＡｌ2Ｏ3：１０％以下、ＭｇＯ：１０％以下、Ｎａ2Ｏ：１０％以下、Ｌｉ2Ｏ：１０％以下、Ｆ：１０％以下、Ｔ．Ｃ：１５％以下を含有する組成物からなり、ＣａＯ／ＳｉＯ2：０．２５〜０．８８、軟化点：１１００〜１２５０℃、１３００℃における粘度：１０．０ｐｏｉｓｅ以上の物性を有する連続鋳造用パウダーが開示されている。上記（１）式の反応で溶融スラグ組成が変化しても、凝固温度が上昇せず、高融点鉱物の結晶を晶出させないとしている。 In Patent Document 1, for continuous casting of steel containing Al of 0.5% or more, SiO 2 : 40 to 60%, CaO: 15 to 35%, further Al 2 O 3 : 10% or less, MgO: 10% or less; Na 2 O: 10% or less; Li 2 O: 10% or less; F: 10% or less; C: composed of a composition containing 15% or less, CaO / SiO 2 : 0.25 to 0.88, softening point: 1100 to 1250 ° C., viscosity at 1300 ° C .: physical properties of 10.0 poise or more A powder is disclosed. Even if the molten slag composition is changed by the reaction of the above formula (1), the solidification temperature does not increase, and crystals of the high melting point mineral are not crystallized.
特許文献２においては、Ａｌを０．８０質量％以上含有した鋼の連続鋳造用として、軟化点が１０５０℃以上で１３００℃における粘度が１．０Ｐａ・ｓ以上の物性を有する連続鋳造用パウダーが開示されている。塩基度が０．５０未満に調整されている。塩基度を０．５未満に調整することにより、上記（１）式の反応が起こっても、高融点結晶のゲーレナイトを晶出させないとしている。 In Patent Document 2, for continuous casting of steel containing 0.80% by mass or more of Al, a powder for continuous casting having a physical property of a softening point of 1050 ° C. or higher and a viscosity at 1300 ° C. of 1.0 Pa · s or higher is disclosed. It is disclosed. The basicity is adjusted to less than 0.50. By adjusting the basicity to less than 0.5, even if the reaction of the above formula (1) occurs, the high melting point crystal gehlenite is not crystallized.
特許文献１、２に記載の連続鋳造用パウダーは、１３００℃における粘度がそれぞれ１０．０ｐｏｉｓｅ以上、１．０Ｐａ・ｓ以上と高粘度である点が特徴である。このようなパウダーを高Ａｌ鋼の連続鋳造に用いた場合、上記（１）式の反応が進んで溶融スラグ中のＡｌ2Ｏ3濃度が上昇し、これがために溶融スラグの粘度はさらに上昇する。その結果、鋳型内からのパウダー消費量が減少し、鋳型内で溶融スラグが滞留し、（１）式の反応がさらに進行することになる。そのため、特許文献１、２に記載の連続鋳造用パウダーを用いても、高Ａｌ鋼を安定して連続鋳造することはできなかった。 The powders for continuous casting described in Patent Documents 1 and 2 are characterized in that the viscosity at 1300 ° C. is as high as 10.0 poise or more and 1.0 Pa · s or more, respectively. When such powder is used for continuous casting of high Al steel, the reaction of the above formula (1) proceeds to increase the concentration of Al 2 O 3 in the molten slag, which further increases the viscosity of the molten slag. . As a result, the amount of powder consumption from the mold is reduced, the molten slag stays in the mold, and the reaction of the formula (1) further proceeds. Therefore, even if the powder for continuous casting described in Patent Documents 1 and 2 is used, high Al steel cannot be stably continuously cast.
以上のような状況のため、高Ａｌ鋼についても、特許文献１、２に記載のパウダーよりも塩基度を上げ、これによって粘度を低下させたパウダーを用いていた。ところが、粘度の低いパウダーを用いた場合においても、高Ａｌ鋼の連続鋳造においては、鋳型内で溶融した後の溶融スラグは粘度が上昇し、スラグベアが形成される結果となった。 Because of the situation as described above, high Al steel has also been used with a powder whose basicity is higher than that of the powders described in Patent Documents 1 and 2, thereby reducing the viscosity. However, even when powder with low viscosity is used, in continuous casting of high Al steel, the molten slag after melting in the mold increases in viscosity, resulting in the formation of slag bear.
高Ｓｉ鋼においては、Ｓｉがフェライト安定化元素であるため、フェライト単相になりやすく、連続鋳造での冷却中においてもフェライト粒の粒成長が生じる。このようなフェライト粒成長を防止するため、鋳型内においても、凝固シェルから鋳型への抜熱を強化して強冷却とすることが必要である。ところが、従来の連続鋳造パウダーを用いた場合には、鋳型と凝固シェル間に存在するパウダーフィルムの熱伝導特性が十分ではなく、凝固シェルを十分に強冷却することができなかった。 In high Si steel, since Si is a ferrite stabilizing element, it tends to become a single phase of ferrite, and ferrite grains grow even during cooling in continuous casting. In order to prevent such ferrite grain growth, it is necessary to strengthen the heat removal from the solidified shell to the mold to achieve strong cooling even in the mold. However, when the conventional continuous casting powder is used, the thermal conductivity of the powder film existing between the mold and the solidified shell is not sufficient, and the solidified shell cannot be cooled sufficiently strongly.
本発明は、高Ｓｉ高Ａｌ鋼の連続鋳造において、鋳型内に形成される溶融スラグの粘度を適正な範囲に維持し、スラグベアの過剰な形成を防止し、鋳型内における凝固シェルの強冷却を実現することのできる連続鋳造用パウダー、連続鋳造方法を提供することを目的とする。 The present invention maintains the viscosity of the molten slag formed in the mold within an appropriate range in continuous casting of high-Si high-Al steel, prevents excessive formation of slag bear, and provides strong cooling of the solidified shell in the mold. An object of the present invention is to provide a continuous casting powder and a continuous casting method that can be realized.
高Ａｌ鋼の連続鋳造においては、上記（１）式の反応によって溶融スラグ中のＡｌ2Ｏ3濃度が増大しＳｉＯ2濃度が減少することは避けられない。このような成分変化があっても溶融スラグの粘度を十分に低い値に保持することが必要である。本発明においては、パウダー中のＮａ2Ｏ濃度を１０質量％以上とすることにより、パウダーの初期粘度を下げるとともに、連続鋳造中に溶融スラグ中Ａｌ2Ｏ3濃度が上昇しても粘度の上昇を抑えられることを見出した。 In continuous casting of high Al steel, it is inevitable that the Al 2 O 3 concentration in the molten slag increases and the SiO 2 concentration decreases due to the reaction of the above formula (1). Even if such a component change occurs, it is necessary to maintain the viscosity of the molten slag at a sufficiently low value. In the present invention, by setting the Na 2 O concentration in the powder to 10% by mass or more, the initial viscosity of the powder is lowered and the viscosity increases even if the Al 2 O 3 concentration in the molten slag increases during continuous casting. It was found that it can be suppressed.
高Ａｌ鋼の連続鋳造を行うと、溶融スラグ中のＡｌ2Ｏ3濃度が上昇し、溶融パウダーが鋳型壁で冷却されるときにゲーレナイトが晶出しやすい。ゲーレナイトの晶出は、スラグベアの成長を促すとともに、パウダーフィルムの熱伝導特性を劣化させるので好ましくない。本発明においては、パウダー中にＭｇＯを５質量％以上含有させることにより、ゲーレナイトの生成を防止できることを見出した。パウダーにＭｇＯを含有させた結果として、冷却中にスピネルの晶出が起こる可能性がある。本発明においては、溶融スラグの塩基度を１以下に抑えることにより、スピネルの生成を防止できることを見出した。 When continuous casting of high Al steel is performed, the Al 2 O 3 concentration in the molten slag increases, and gehlenite tends to crystallize when the molten powder is cooled by the mold wall. Crystallization of gehlenite is not preferable because it promotes the growth of slag bear and deteriorates the heat conduction characteristics of the powder film. In this invention, it discovered that the production | generation of gehlenite could be prevented by making MgO contain 5 mass% or more in powder. As a result of including MgO in the powder, spinel crystallization may occur during cooling. In this invention, it discovered that the production | generation of a spinel can be prevented by restraining the basicity of molten slag to 1 or less.
高Ｓｉ鋼の連続鋳造においては、パウダーフィルムの熱伝導特性を向上して強冷化するため、カスピダイン（３ＣａＯ・２ＳｉＯ2・ＣａＦ2）の晶出も防止しなければならない。本発明においては、溶融スラグの塩基度を１以下とするとともにＮａ2Ｏを１０％以上含有させることにより、カスピダインの晶出を防止できることを明らかにした。 In continuous casting of high Si steel, crystallization of caspodyne (3CaO · 2SiO 2 · CaF 2 ) must be prevented in order to improve the heat conduction characteristics of the powder film and to strengthen it. In the present invention, it has been clarified that crystallization of caspodyne can be prevented by setting the basicity of the molten slag to 1 or less and containing Na 2 O by 10% or more.
本発明は上記知見に基づいてなされたものであり、その要旨とするところは以下のとおりである。
（１）Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼の連続鋳造に用いる連続鋳造用パウダーであって、Ｔ．ＣａＯ／ＳｉＯ2が質量比で０．５以下であり、ＭｇＯ：５％以上１５％以下、Ｎａ2Ｏ：１０％以上、Ａｌ2Ｏ3：５％以下を含有し、１３００℃における粘度が１Ｐａ・ｓ未満、凝固温度が１０５０℃以下であることを特徴とする連続鋳造用パウダー。ここで、Ｔ．ＣａＯは、含有するＣａ分がすべてＣａＯであるとして算出した値である。
（２）さらに質量％で、Ｔ．ＣａＯ：１５％以上２５％以下、ＳｉＯ2：３５％以上５５％以下、Ｆ：１０％以下、Ｔ．Ｃ：１０％以下を含有することを特徴とする上記（１）に記載の連続鋳造用パウダー。
（３）Ｎａ2Ｏに替え、Ｎａ2Ｏ＋Ｌｉ2Ｏ：１０％以上であることを特徴とする上記（１）又は（２）に記載の連続鋳造用パウダー。
（４）Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼を連続鋳造するに際し、上記（１）乃至（３）のいずれかに記載の連続鋳造用パウダーを用いることを特徴とする鋼の連続鋳造方法。
（５）Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼の連続鋳造において、鋳型内に投入した連続鋳造用パウダーが溶融して形成された溶融スラグについて、Ｔ．ＣａＯ／ＳｉＯ2が質量比で１以下、組成が質量％で、ＭｇＯ：５％以上１５％以下、Ｎａ2Ｏ：１０％以上２０％以下、Ａｌ2Ｏ3：２０％以下であることを特徴とする鋼の連続鋳造方法。
（６）前記溶融スラグについて、１３００℃における粘度が１Ｐａ・ｓ以下であり、かつ凝固温度が１２００℃以下であることを特徴とする上記（５）に記載の鋼の連続鋳造方法。
（７）Ｎａ2Ｏに替え、Ｎａ2Ｏ＋Ｌｉ2Ｏ：１０％以上２０％以下であることを特徴とする上記（５）又は（６）に記載の鋼の連続鋳造方法。
This invention is made | formed based on the said knowledge, The place made into the summary is as follows.
(1) A powder for continuous casting used for continuous casting of high Si high Al steel having a Si concentration of 2 mass% or more and an Al concentration of 0.5 mass% or more, CaO / SiO 2 is 0.5 or less in mass ratio, MgO: 5% or more and 15% or less, Na 2 O: 10% or more, Al 2 O 3 : 5% or less, and viscosity at 1300 ° C. is 1 Pa A powder for continuous casting, characterized by being less than s and a solidification temperature of 1050 ° C. or lower. Here, T.W. CaO is a value calculated assuming that all of the Ca content is CaO.
(2) Further, in terms of mass%, T.I. CaO: 15% to 25%, SiO 2 : 35% to 55%, F: 10% or less, T.I. C: The powder for continuous casting as described in (1) above, containing 10% or less.
(3) instead of Na 2 O, Na 2 O + Li 2 O: above, wherein the at least 10% (1) or (2) Continuous casting powder according to.
(4) The powder for continuous casting according to any one of the above (1) to (3) when continuously casting a high Si high Al steel having an Si concentration of 2% by mass or more and an Al concentration of 0.5% by mass or more. A continuous casting method of steel, characterized by using
(5) In the continuous casting of high Si high Al steel having an Si concentration of 2% by mass or more and an Al concentration of 0.5% by mass or more, a molten slag formed by melting the continuous casting powder charged into the mold T. CaO / SiO 2 has a mass ratio of 1 or less, the composition is mass%, MgO: 5% or more and 15% or less, Na 2 O: 10% or more and 20% or less, and Al 2 O 3 : 20% or less. Steel continuous casting method.
(6) The continuous casting method for steel as described in (5) above, wherein the molten slag has a viscosity at 1300 ° C. of 1 Pa · s or less and a solidification temperature of 1200 ° C. or less.
(7) Instead of Na 2 O, Na 2 O + Li 2 O: 10% or more and 20% or less, The steel continuous casting method according to (5) or (6) above.
Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼の連続鋳造において、本発明の連続鋳造用パウダーを用いることにより、あるいは本発明の連続鋳造方法を適用することにより、鋳型内に形成される溶融スラグの粘度並びに凝固温度を適正な範囲に維持し、スラグベアの過剰な形成を防止し、鋳型内における凝固シェルの強冷却を実現することができるので、鋳造する鋳片の表面性状を良好に保持し、ブレークアウトの発生を防止し、高Ｓｉ鋼にもかかわらず鋳片表層付近のフェライト粒成長を防止することができる。 In continuous casting of high Si high Al steel having an Si concentration of 2 mass% or more and an Al concentration of 0.5 mass% or more, the continuous casting powder of the present invention is used or the continuous casting method of the present invention is applied. As a result, it is possible to maintain the viscosity and solidification temperature of the molten slag formed in the mold within an appropriate range, prevent excessive formation of the slag bear, and realize strong cooling of the solidified shell in the mold. The surface properties of the cast slab can be maintained well, the occurrence of breakout can be prevented, and the ferrite grain growth near the slab surface layer can be prevented despite the high Si steel.
本発明において、塩基度とはＴ．ＣａＯ／ＳｉＯ2の質量比をいう。またＴ．ＣａＯは、含有するＣａ分がすべてＣａＯであるとして算出した値である。 In the present invention, basicity means T.W. It refers to the mass ratio of CaO / SiO 2 . T. CaO is a value calculated assuming that all of the contained Ca is CaO.
本発明は、Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼の連続鋳造を対象とする。高Ａｌ鋼を鋳造するため、前記（１）式の反応は避けられず、投入した連続鋳造用パウダー中のＳｉＯ2が鋼中Ａｌと反応し、溶融スラグ中のＡｌ2Ｏ3濃度が上昇する。 The present invention is directed to continuous casting of high Si high Al steel having a Si concentration of 2 mass% or more and an Al concentration of 0.5 mass% or more. Since the high Al steel is cast, the reaction of the above formula (1) is unavoidable, and the SiO 2 in the continuously cast powder that has been charged reacts with Al in the steel, and the concentration of Al 2 O 3 in the molten slag increases. .
溶融スラグ中のＡｌ2Ｏ3濃度上昇に伴い、この溶融スラグが水冷鋳型と接して冷却されるときにゲーレナイトが晶出すると、鋳型内壁の湯面近傍に巨大なスラグベアが生じ、鋳型と凝固シェル間への溶融スラグの流入を阻害し、鋳型と凝固シェルとの間の焼き付きが生じるのは前述の通りである。 As the molten slag is cooled in contact with the water-cooled mold as the Al 2 O 3 concentration increases, a huge slag bear is formed in the vicinity of the molten metal surface of the inner wall of the mold, and the mold and the solidified shell. As described above, the molten slag is prevented from flowing in between and the seizure between the mold and the solidified shell occurs.
本発明においては、連続鋳造用パウダー中にＭｇＯを含有させることにより、たとえ溶融スラグ中でＡｌ2Ｏ3濃度が上昇したとしても、ゲーレナイトの晶出を防止できることを見いだした。図１（ａ）にＣａＯ−ＳｉＯ2−Ａｌ2Ｏ3三元系状態図を示す。Ａｌ2Ｏ3含有量が高い領域にゲーレナイト晶出領域が存在する。一方、図１（ｂ）に示すように、ＣａＯ−ＳｉＯ2−Ａｌ2Ｏ3−１０％ＭｇＯ四元系状態図においては、ゲーレナイト晶出領域が消滅していることが分かる。本発明においては、溶融スラグ中のＭｇＯ含有量を５質量％以上とすることにより、Ａｌ2Ｏ3濃度上昇が起こってもゲーレナイト晶出を防止できる。連続鋳造パウダー中のＭｇＯ含有量を５質量％以上とすることにより、この条件を具現することができる。一方、溶融スラグ中のＭｇＯ含有量が高すぎるとスピネル（ＭｇＯ・Ａｌ2Ｏ3）が晶出する可能性がある。溶融スラグ中のＭｇＯ含有量を１５質量％以下、そのためにパウダー中のＭｇＯ含有量を１５質量％以下とするとこにより、スピネルの晶出を防止することができる。 In the present invention, it has been found that by including MgO in the powder for continuous casting, crystallization of gehlenite can be prevented even if the Al 2 O 3 concentration is increased in the molten slag. FIG. 1 (a) shows a CaO—SiO 2 —Al 2 O 3 ternary phase diagram. A gehlenite crystallization region exists in a region where the Al 2 O 3 content is high. On the other hand, as shown in FIG. 1B, in the CaO—SiO 2 —Al 2 O 3 -10% MgO quaternary phase diagram, it can be seen that the gehlenite crystallization region disappears. In the present invention, by setting the MgO content in the molten slag to 5% by mass or more, even if Al 2 O 3 concentration rises, gehlenite crystallization can be prevented. This condition can be realized by setting the MgO content in the continuous casting powder to 5 mass% or more. On the other hand, if the MgO content in the molten slag is too high, spinel (MgO.Al 2 O 3 ) may crystallize. Spinel crystallization can be prevented by setting the MgO content in the molten slag to 15% by mass or less and the MgO content in the powder to 15% by mass or less.
図１（ｂ）からわかるように、１０質量％程度のＭｇＯを含有することにより、凝固温度が１４００℃以下の低凝固温度領域が低塩基度側で拡大している。この領域を利用し、溶融スラグ中の塩基度を１以下としてＭｇＯを５質量％以上含有することにより、ゲーレナイト晶出を防止するとともに溶融スラグの凝固温度を低減することができる。溶融スラグ中の塩基度を１以下とすることは、スピネルの晶出を防止する上でも有効である。 As can be seen from FIG. 1 (b), by containing about 10% by mass of MgO, the low solidification temperature region where the solidification temperature is 1400 ° C. or lower is expanded on the low basicity side. By using this region and containing 5% by mass or more of MgO with a basicity in the molten slag of 1 or less, gelenite crystallization can be prevented and the solidification temperature of the molten slag can be reduced. Setting the basicity in the molten slag to 1 or less is also effective in preventing spinel crystallization.
前述のように、高Ｓｉ鋼の連続鋳造においては、鋳型内での凝固シェルを強冷却することが必要であり、鋳型と凝固シェル間に形成されるパウダーフィルムを介した熱伝導特性を向上する必要がある。そのため、高Ｓｉ鋼の連続鋳造では、ゲーレナイトの晶出を防止するのみならず、カスピダインの晶出も防止する必要がある。カスピダイン晶出防止のためには、低温域まで安定して溶融ガラス状態を保持する、すなわち、凝固温度の低減を図る必要がある。 As described above, in the continuous casting of high Si steel, it is necessary to strongly cool the solidified shell in the mold, and the heat conduction characteristics through the powder film formed between the mold and the solidified shell are improved. There is a need. Therefore, in continuous casting of high-Si steel, it is necessary not only to prevent crystallization of gehlenite but also to prevent crystallization of caspidine. In order to prevent caspidine crystallization, it is necessary to stably maintain the molten glass state up to a low temperature range, that is, to reduce the solidification temperature.
本発明においては、溶融スラグ中の塩基度を１以下とするとともに、Ｆとの親和性がＣａＦ2よりも高いＮａ2Ｏを溶融スラグ中に含有することにより、下記（２）式の反応によりＣａＦ2をＮａＦとし、カスピダインの晶出を防止することができる。カスピダインの晶出は溶融スラグの塩基度とＦがＮａＦあるいはＣａＦ2のどちらと配位するかに依存する（下記（２）式の反応）。Ｎａ2Ｏが５％未満の場合ＦはＣａＦ2として配位するが、Ｎａ2Ｏが５％以上でＮａＦとして配位するようになり、１０％以上でカスピダインの晶出を抑制できる。
ＣａＦ2＋Ｎａ2Ｏ → ＣａＯ＋２ＮａＦ （２）
In the present invention, the basicity in the molten slag is set to 1 or less, and Na 2 O having an affinity for F higher than that of CaF 2 is contained in the molten slag. CaF 2 can be changed to NaF to prevent crystallization of caspidine. Crystallization of caspodyne depends on the basicity of the molten slag and whether F is coordinated with NaF or CaF 2 (reaction of the following formula (2)). When Na 2 O is less than 5%, F is coordinated as CaF 2 , but Na 2 O is coordinated as NaF when 5% or more, and crystallization of caspidyne can be suppressed at 10% or more.
CaF 2 + Na 2 O → CaO + 2NaF (2)
Ｎａ2Ｏを含有することによるカスピダイン晶出防止の効果として、凝固温度を低下させることができる。また、Ｎａ2Ｏ含有によってパウダーの１３００℃における粘度を低減できる。さらに、高Ａｌ鋼の連続鋳造で溶融スラグ中のＡｌ2Ｏ3濃度が上昇しても、溶融スラグの１３００℃粘度上昇を抑える効果を発揮することができる。即ち、溶融スラグ中のＮａ2Ｏ含有量を１０質量％以上とすることにより、カスピダインの晶出を防止し、溶融スラグの１３００℃粘度を１Ｐａ・ｓ以下に保持し、溶融スラグの凝固温度を１２００℃以下に保持することができる。パウダー中のＮａ2Ｏ含有量を１０質量％以上とするとともに溶融スラグの塩基度を１以下に保持することにより、溶融スラグ中のＮａ2Ｏ含有量を１０質量％以上とすることができる。またこれにより、パウダーの１３００℃粘度を１Ｐａ・ｓ以下とすることができる。溶融スラグの塩基度が１を超えると、たとえパウダー中のＮａ2Ｏ含有量を１０質量％以上であったとしても、溶融スラグ中のＳｉＯ2が少なすぎてＮａ2Ｏが安定に存在し得なくなり、Ｎａ2ＯがＡｌによって還元されてしまう。一方、溶融スラグ中のＮａ2Ｏ濃度が２０質量％超（パウダー中のＮａ2Ｏ濃度が２０質量％超）となっても効果は変わらないため、Ｎａ2Ｏ含有量の上限を２０質量％とする。本発明において、パウダーあるいは溶融スラグ中のＮａ含有量を分析し、そのすべてがＮａ2ＯになっているとしてＮａ2Ｏ含有量を計算する。 The solidification temperature can be lowered as an effect of preventing crystallization of caspodyne by containing Na 2 O. Further, it is possible to reduce the viscosity at 1300 ° C. the powder by Na 2 O content. Furthermore, even if the Al 2 O 3 concentration in the molten slag is increased by continuous casting of high Al steel, the effect of suppressing the 1300 ° C. viscosity increase of the molten slag can be exhibited. That is, by setting the Na 2 O content in the molten slag to 10% by mass or more, crystallization of caspidine is prevented, the 1300 ° C. viscosity of the molten slag is maintained at 1 Pa · s or less, and the solidification temperature of the molten slag is set to It can be kept at 1200 ° C. or lower. By setting the Na 2 O content in the powder to 10% by mass or more and keeping the basicity of the molten slag at 1 or less, the Na 2 O content in the molten slag can be set to 10% by mass or more. Thereby, 1300 degreeC viscosity of powder can be 1 Pa * s or less. When the basicity of the molten slag exceeds 1, even if the Na 2 O content in the powder is 10% by mass or more, there is too little SiO 2 in the molten slag and Na 2 O can exist stably. The Na 2 O is reduced by Al. On the other hand, since the effect does not change even if the Na 2 O concentration in the molten slag exceeds 20% by mass (Na 2 O concentration in the powder exceeds 20% by mass), the upper limit of the Na 2 O content is 20% by mass. And In the present invention, to analyze the Na content in the powder or molten slag, all of computing the content of Na 2 O as has become Na 2 O.
本発明において、鋳型内の溶融スラグ中Ａｌ2Ｏ3含有量を２０質量％以下に保持する。溶融スラグ中Ａｌ2Ｏ3含有量が２０質量％を超えると、スピネルが晶出する可能性があるとともに、溶融スラグの粘度が高くなり過ぎ、Ｎａ2ＯやＦを上限まで含有しても粘度を適正レベルに下げることができないからである。高Ａｌ鋼の連続鋳造を行うので、パウダー中のＳｉＯ2が鋼中Ａｌで還元されて溶融スラグ中のＡｌ2Ｏ3濃度が増大するが、パウダー中Ａｌ2Ｏ3含有量を５質量％以下とすることにより、溶融スラグ中のＡｌ2Ｏ3含有量を２０質量％以下とすることができる。ただし、パウダーの粘度が高すぎると、鋳型内の溶融スラグが十分に消費されずに鋳型内に滞留するので、（１）式の反応が過剰に進行してＡｌ2Ｏ3含有量が増大することとなる。パウダーの粘度を１３００℃で１Ｐａ・ｓ未満とすれば、（１）式の過剰進行を抑えることができる。 In the present invention, the Al 2 O 3 content in the molten slag in the mold is kept at 20% by mass or less. When the content of Al 2 O 3 in the molten slag exceeds 20% by mass, spinel may be crystallized, the viscosity of the molten slag becomes too high, and even if Na 2 O or F is contained up to the upper limit, the viscosity This is because the value cannot be lowered to an appropriate level. Since high Al steel is continuously cast, SiO 2 in the powder is reduced by Al in the steel and the concentration of Al 2 O 3 in the molten slag increases, but the content of Al 2 O 3 in the powder is 5% by mass or less. with the Al 2 O 3 content in the molten slag can be 20 mass% or less. However, when the viscosity of the powder is too high, the molten slag in the mold is not sufficiently consumed and stays in the mold, so that the reaction of the formula (1) proceeds excessively and the Al 2 O 3 content increases. It will be. If the viscosity of the powder is less than 1 Pa · s at 1300 ° C., excessive progression of the formula (1) can be suppressed.
本発明においては、Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼の連続鋳造において、鋳型内に投入した連続鋳造用パウダーが溶融して形成された溶融スラグについて、１３００℃における粘度が１Ｐａ・ｓ以下であり、かつ凝固温度が１２００℃以下であればよい。高Ａｌ鋼の連続鋳造によってパウダー中のＳｉＯ2が鋼中Ａｌで還元され、溶融スラグ中のＡｌ2Ｏ3濃度が増大するが、Ａｌ2Ｏ3濃度が増大した後において上記粘度と凝固温度を保持できているので、凝固中のゲーレナイト、カスピダイン、スピネルのいずれも晶出を防止することができる。 In the present invention, in the continuous casting of high Si high Al steel having an Si concentration of 2% by mass or more and an Al concentration of 0.5% by mass or more, the melt formed by melting the continuous casting powder charged into the mold About slag, the viscosity in 1300 degreeC should be 1 Pa.s or less, and solidification temperature should just be 1200 degrees C or less. By continuous casting of high Al steel, SiO 2 in the powder is reduced by Al in the steel, and the Al 2 O 3 concentration in the molten slag increases. After the Al 2 O 3 concentration increases, the viscosity and solidification temperature are increased. Since it can be held, crystallization can be prevented in any of galenite, caspidine, and spinel during solidification.
また、溶融スラグの塩基度を１以下、ＭｇＯ：５％以上１５％以下、Ｎａ2Ｏ：１０％以上２０％以下、Ａｌ2Ｏ3：２０％以下とすることにより、溶融スラグの１３００℃における粘度を１Ｐａ・ｓ以下とし、かつ凝固温度を１２００℃以下とすることができる。 Further, by setting the basicity of the molten slag to 1 or less, MgO: 5% to 15%, Na 2 O: 10% to 20%, Al 2 O 3 : 20% or less, the molten slag at 1300 ° C. The viscosity can be 1 Pa · s or less, and the solidification temperature can be 1200 ° C. or less.
本発明において、Ｓｉ濃度が２質量％以上、Ａｌ濃度が０．５質量％以上の高Ｓｉ高Ａｌ鋼の連続鋳造において、塩基度が０．５以下、１３００℃における粘度が１Ｐａ・ｓ未満、凝固温度が１０５０℃以下である連続鋳造用パウダーを用いることにより、鋳型内に投入した連続鋳造用パウダーが溶融して形成された溶融スラグの１３００℃における粘度を１Ｐａ・ｓ以下とし、かつ凝固温度を１２００℃以下とすることができる。 In the present invention, in the continuous casting of high Si high Al steel having a Si concentration of 2% by mass or more and an Al concentration of 0.5% by mass or more, the basicity is 0.5 or less, and the viscosity at 1300 ° C. is less than 1 Pa · s, By using a continuous casting powder having a solidification temperature of 1050 ° C. or less, the viscosity at 1300 ° C. of the molten slag formed by melting the continuous casting powder charged into the mold is 1 Pa · s or less, and the solidification temperature Can be 1200 degrees C or less.
また、パウダー組成を、ＭｇＯ：５％以上１５％以下、Ｎａ2Ｏ：１０％以上、Ａｌ2Ｏ3：５％以下とすることにより、上記パウダーの粘度と凝固温度を実現することができる。 Further, the powder composition, MgO: 15% 5% or more or less, Na 2 O: 10% or more, Al 2 O 3: by 5% or less, it is possible to realize the viscosity and solidification temperature of the powder.
高Ａｌ鋼の連続鋳造において、鋳型に投入した連続鋳造用パウダー中のＳｉＯ2が鋼中のＡｌで還元され、溶融スラグ中のＡｌ2Ｏ3濃度が上昇し、ＳｉＯ2濃度が減少する。そのため、溶融スラグの塩基度はパウダー塩基度よりも高い値となる。本発明において、パウダー塩基度を０．５以下とすれば、鋳造中に鋳型内で溶融スラグ中のＳｉＯ2濃度が減少しても、溶融スラグの塩基度を１以下に保持することができる。 In continuous casting of high Al steel, SiO 2 in the powder for continuous casting charged into the mold is reduced by Al in the steel, the Al 2 O 3 concentration in the molten slag is increased, and the SiO 2 concentration is decreased. For this reason, the basicity of the molten slag is higher than the powder basicity. In the present invention, if the powder basicity is 0.5 or less, the basicity of the molten slag can be maintained at 1 or less even if the SiO 2 concentration in the molten slag is reduced in the mold during casting.
本発明の連続鋳造用パウダーの好ましい成分範囲について説明する。 A preferred component range of the continuous casting powder of the present invention will be described.
ＣａＯは、鋼中Ａｌのような還元成分と反応しがたく、パウダーの主成分として添加している。安定な溶融スラグを形成するためにはＴ．ＣａＯで１５％以上が必要で２５％以上になると本発明で用いるパウダーとしては塩基度が高くなりすぎるため好ましくない。そこで、パウダー中のＴ．ＣａＯ含有量の範囲を１５〜２５質量％とする。 CaO is hard to react with a reducing component such as Al in steel and is added as a main component of powder. In order to form a stable molten slag, T.W. If CaO requires 15% or more and 25% or more, the powder used in the present invention is not preferable because the basicity becomes too high. Therefore, T. in the powder. The range of CaO content is 15 to 25% by mass.
ＳｉＯ2は、低融点化とガラス化を促進するために、パウダーの主成分として添加している。本発明で用いるパウダーとして塩基度を０．５以下とするため３５％以上必要である。一方、５５％を超えると塩基度が低くなりすぎるため本発明で用いるパウダーとしては好ましくない。 SiO 2 is added as a main component of the powder in order to promote low melting point and vitrification. The powder used in the present invention requires 35% or more in order to make the basicity 0.5 or less. On the other hand, if it exceeds 55%, the basicity becomes too low, which is not preferable as the powder used in the present invention.
Ｆは、粘度と融点を下げる目的で２％以上添加する。過剰に添加すると浸漬ノズルの溶損を促進するため１０％以下とする。 F is added in an amount of 2% or more for the purpose of lowering the viscosity and melting point. When excessively added, the melting loss of the immersion nozzle is promoted, so the content is made 10% or less.
Ｃは、パウダーの溶融速度調整や焼結防止のため必要に応じて０．５％以上含有させる。一方、１０％を超えると溶融が極端に遅れ、溶融スラグを十分確保できないことで潤滑不良や浸炭の問題がある。 C is contained in an amount of 0.5% or more as necessary for adjusting the melting rate of powder and preventing sintering. On the other hand, if it exceeds 10%, melting is extremely delayed, and there is a problem of poor lubrication or carburization because sufficient molten slag cannot be secured.
本発明においては、溶融スラグ中あるいはパウダー中のＮａ2Ｏに替え、Ｎａ2Ｏ＋Ｌｉ2Ｏ：１０％以上とすることができる。Lｉ2ＯはＮａ2Ｏと同様にＣａＦ2からＦを奪う効果及び凝固温度を低下させる効果を有する。Ｎａ2Ｏ＋Ｌｉ2Ｏ：１０％以上とすれば、Ｎａ2Ｏ：１０％以上と同様の効果を発揮することができる。一方、溶融スラグ中のＮａ2Ｏ＋Ｌｉ2Ｏ濃度が２０質量％超（パウダー中のＮａ2Ｏ＋Ｌｉ2Ｏ濃度が２０質量％超）となっても効果は変わらないため、Ｎａ2Ｏ＋Ｌｉ2Ｏ含有量の上限を２０質量％とする。 In the present invention, Na 2 O + Li 2 O: 10% or more can be used instead of Na 2 O in molten slag or powder. Li 2 O is has the effect of reducing the effects and coagulation temperature deprive F CaF 2, as with Na 2 O. If Na 2 O + Li 2 O: 10% or more, the same effect as Na 2 O: 10% or more can be exhibited. On the other hand, even if the Na 2 O + Li 2 O concentration in the molten slag exceeds 20% by mass (Na 2 O + Li 2 O concentration in the powder exceeds 20% by mass), the effect does not change, so the content of Na 2 O + Li 2 O The upper limit of 20 mass%.
本発明で鋳造する高Ｓｉ高Ａｌ鋼について、Ｓｉ濃度を２質量％以上と限定したのは、Ｓｉ濃度が２質量％未満では、鋳造鋳型内で凝固シェルを強冷却すべきという高Ｓｉ鋼特有の問題が生じないためである。またＡｌ濃度を０．５質量％以上と限定したのは、Ａｌ濃度が０．５質量％未満では、鋳造中の鋳型内で溶融スラグ中のＡｌ2Ｏ3濃度上昇が多くなく、高Ａｌ鋼特有の問題が生じないためである。 The high Si high Al steel cast in the present invention is limited to a Si concentration of 2% by mass or more because, if the Si concentration is less than 2% by mass, the solidified shell should be strongly cooled in the casting mold. This is because the problem does not occur. Moreover, the Al concentration is limited to 0.5% by mass or more because when the Al concentration is less than 0.5% by mass, the Al 2 O 3 concentration in the molten slag does not increase much in the casting mold, and high Al steel is used. This is because no particular problem occurs.
質量％で、Ｃ：０．００３％、Ｓｉ：３．０％、Ａｌ：０．６％、Ｍｎ：０．２％、Ｓ：０．００１％を含有した溶鋼を溶製した後、幅１０００ｍｍ×厚み２５０ｍｍの断面形状のスラブを鋳造速度１ｍ／分にて連続鋳造した。鋳造したスラブを用い、常法によって熱間圧延と冷間圧延を行った。 After melting a molten steel containing C: 0.003%, Si: 3.0%, Al: 0.6%, Mn: 0.2%, S: 0.001% in mass%, width 1000 mm X A slab having a cross-sectional shape with a thickness of 250 mm was continuously cast at a casting speed of 1 m / min. Using the cast slab, hot rolling and cold rolling were performed by a conventional method.
表１に示すパウダー１（本発明例）、パウダー２（比較例）の２種類の連続鋳造用パウダーを用いた。鋳造中、鋳型内の溶融スラグ、鋳型内で生成したスラグベアを採取した。鋳型内の溶融スラグについては成分を分析するとともに、再度カーボンルツボ内でスラグを溶融し、粘度測定と凝固温度測定を行った。また、採取した溶融スラグとスラグベアの断面を研磨した後、走査型電子顕微鏡での観察を行った。併せて、溶融スラグとスラグベアのＸ線回折を行い晶出物の調査を行った。 Two types of powders for continuous casting, powder 1 (invention example) and powder 2 (comparative example) shown in Table 1, were used. During casting, molten slag in the mold and slag bear generated in the mold were collected. Components of the molten slag in the mold were analyzed, and the slag was melted again in the carbon crucible, and viscosity measurement and solidification temperature measurement were performed. Moreover, after grind | polishing the cross section of the extract | collected molten slag and slag bear, observation with the scanning electron microscope was performed. At the same time, X-ray diffraction of molten slag and slag bear was conducted to investigate the crystallized matter.
連続鋳造用パウダー及び溶融スラグの粘度と凝固温度測定方法について説明する。連続鋳造用パウダー、溶融スラグのいずれも、カーボンルツボ内で溶融し、温度を下げながら粘度測定を行い、１３００℃における粘度ならびに凝固温度を測定する。ここで凝固温度とは粘度が急激に増加する温度を意味する。なお、本実施例で用いた粘度測定において、５Ｐａ・ｓを超える高粘度の測定が困難であった。そのため、温度を下げながら粘度測定を行う過程で、粘度が急激に増加することなく５Ｐａ・ｓに到達したサンプルについては、凝固温度がその到達した温度以下であると表示することにした。 A method for measuring the viscosity and solidification temperature of powder for continuous casting and molten slag will be described. Both the continuous casting powder and the molten slag are melted in a carbon crucible, the viscosity is measured while lowering the temperature, and the viscosity at 1300 ° C. and the solidification temperature are measured. Here, the solidification temperature means a temperature at which the viscosity rapidly increases. In the viscosity measurement used in this example, it was difficult to measure a high viscosity exceeding 5 Pa · s. Therefore, in the process of measuring the viscosity while lowering the temperature, for the sample that has reached 5 Pa · s without the viscosity increasing rapidly, it is determined that the solidification temperature is lower than the reached temperature.
鋳片表面性状については、目視観察を行い、鋳片長手方向に１０ｍｍピッチ程度の間隔で周期的に観察されるオシレーションマークの乱れの有無を評価した。乱れがないときは鋳片表面性状を良好と判断し、二重肌やブリード、割れ等が観察された場合は不良と判断した。鋼板表面性状については、線状疵で表面がめくれているものの面積比率を評価し、ヘゲ不良率とした。ヘゲ不良率が１％以下であれば良好と判断した。 About the slab surface property, visual observation was performed, and the presence or absence of disturbance of the oscillation mark observed periodically at intervals of about 10 mm pitch in the slab longitudinal direction was evaluated. When there was no disturbance, the slab surface property was judged as good, and when double skin, bleed, cracks, etc. were observed, it was judged as defective. About the steel sheet surface property, the area ratio of the surface turned up with the linear wrinkles was evaluated, and it was set as the shaving defect rate. It was judged that the bald defect rate was 1% or less.
鋳造結果を表２に示す。表２において、本発明例１、２はパウダー１を用いた鋳造結果であり、比較例１、２はパウダー２を用いた鋳造結果である。本発明例１、２とも、溶融スラグの塩基度は１以下であり、ＭｇＯ、Ｎａ2Ｏ、Ａｌ2Ｏ3含有量はいずれも本発明の良好範囲であった。そして、溶融スラグの１３００℃での粘度、凝固温度も好適範囲にあった。鋳造時のスラグベア発生はなく、パウダー消費量は０．３ｋｇ／ｔ以上で良好であった。一方比較例１、２は、塩基度が１超であり、ＭｇＯ、Ｎａ2Ｏ濃度が好適範囲の下限未満であり、Ａｌ2Ｏ3濃度が上限を超えていた。そして、溶融スラグの１３００℃での粘度、凝固温度が好適範囲から外れていた。鋳造時にスラグベアが発生し、パウダー消費量は０．３ｋｇ／ｔ未満で不十分であった。 Table 2 shows the casting results. In Table 2, Examples 1 and 2 of the present invention are the results of casting using powder 1, and Comparative Examples 1 and 2 are the results of casting using powder 2. In both inventive examples 1 and 2, the basicity of the molten slag was 1 or less, and the MgO, Na 2 O, and Al 2 O 3 contents were all within the good range of the present invention. And the viscosity at 1300 degreeC and solidification temperature of the molten slag were also in the suitable range. There was no generation of slag bear during casting, and the powder consumption was good at 0.3 kg / t or more. On the other hand, in Comparative Examples 1 and 2, the basicity was more than 1, the MgO and Na 2 O concentrations were less than the lower limit of the preferred range, and the Al 2 O 3 concentration exceeded the upper limit. And the viscosity and solidification temperature in 1300 degreeC of molten slag were remove | deviated from the suitable range. Slag bear was generated during casting, and the powder consumption was less than 0.3 kg / t, which was insufficient.
先ず、パウダー１、２及び本発明例１と比較例１で鋳型内から採取した溶融スラグについて、１３００℃から順次温度を低下させつつ粘度測定を行った。これにより、１３００℃における粘度ならびに凝固温度を測定した。測定結果を図２に示す。図２からわかるように、添加時のパウダーと溶融スラグとは物性値が大きく異なっていることがわかる。次にこれら２つの物性値と鋳造性ならびに鋳片表面性状との関係を調査した。その結果、パウダー１を用いた本発明例１の溶融スラグについては、１３００℃における粘度が１Ｐａ・ｓ以下、かつ凝固温度が１２００℃以下であり、鋳型内で過大なスラグベアが生じることがなかった。また、鋳型内での溶融スラグ厚みがほぼ２０ｍｍ程度で一定しており、添加したパウダーが滞留することなく消費されていた。加えて、鋳片表面性状ならびに形状も問題なかった。一方、パウダー２を用いた比較例２の溶融スラグについては、溶融スラグ中にゲーレナイトが観察され（図３（ａ））、加えて図３（ｂ）のカスピダインが認められた。カスピダインは（１）式の反応の結果、塩基度が増大することで晶出したものである。１３００℃における粘度を測定することができなかった。また、鋳型内で過大なスラグベアが観察され、スラグベア中にゲーレナイトが見られ、凝固温度が１２００℃超であり、１３００℃における粘度が１Ｐａ・ｓ超であった。 First, with respect to the powders 1 and 2 and the molten slag collected from the molds of Invention Examples 1 and Comparative Example 1, the viscosity was measured while sequentially decreasing the temperature from 1300 ° C. Thereby, the viscosity at 1300 ° C. and the solidification temperature were measured. The measurement results are shown in FIG. As can be seen from FIG. 2, the powder and molten slag at the time of addition are greatly different in physical property values. Next, the relationship between these two physical properties, castability and slab surface properties was investigated. As a result, the melted slag of Invention Example 1 using powder 1 had a viscosity at 1300 ° C. of 1 Pa · s or less and a solidification temperature of 1200 ° C. or less, and no excessive slag bear was generated in the mold. . Further, the thickness of the molten slag in the mold was constant at about 20 mm, and the added powder was consumed without stagnation. In addition, there was no problem with the slab surface properties and shape. On the other hand, with respect to the molten slag of Comparative Example 2 using the powder 2, gehlenite was observed in the molten slag (FIG. 3 (a)), and in addition, cuspidyne in FIG. 3 (b) was observed. Caspodyne is crystallized as the basicity increases as a result of the reaction of formula (1). The viscosity at 1300 ° C. could not be measured. In addition, excessive slag bear was observed in the mold, gehlenite was found in the slag bear, the solidification temperature was over 1200 ° C., and the viscosity at 1300 ° C. was over 1 Pa · s.
高Ｓｉ鋼の連続鋳造における鋳型内での冷却強度の適否について鋳片形状ならびに鋳片表層部のフェライト組織を調査した。なお、ナイタールエッチングによってフェライト組織を現出した。その結果、比較例１，２では短辺部についてはコーナー部より５ｍｍ以上、中には１０ｍｍ程度バルジングするとともに長辺部についてはコーナー部から５０ｍｍ程度離れた部位で５ｍｍ程度へこみが見られた。また、周囲よりもへこみが見られる部位のフェライト組織が周囲よりも粗大であった。一方、本発明例１，２では短辺部でのバルジングは見られず、また長辺部のコーナー部から離れた部位においてもへこみは見られなかった。また、フェライト組織は鋳片周方向でほぼ一様であった。 The shape of the slab and the ferrite structure of the slab surface were investigated for the suitability of the cooling strength in the mold during continuous casting of high-Si steel. In addition, a ferrite structure was revealed by nital etching. As a result, in Comparative Examples 1 and 2, the short side portion was bulged about 5 mm or more from the corner portion, and the inside was bulged by about 10 mm, and the long side portion was indented by about 5 mm at a site about 50 mm away from the corner portion. Moreover, the ferrite structure of the site where the dent was seen than the surroundings was coarser than the surroundings. On the other hand, in Examples 1 and 2 of the present invention, no bulging was observed at the short side portion, and no dent was observed at a site away from the corner portion of the long side portion. Further, the ferrite structure was almost uniform in the circumferential direction of the slab.
上記実施例１と同じ品種を同じ連続鋳造条件で鋳造するに際し、連続鋳造用パウダーのみ表３に示すパウダーに変更した。溶融スラグ及びスラグベアの評価も実施例１と同様に行った。結果を表３に示す。本発明範囲から外れる数値、及び好ましい範囲から外れる数値にアンダーラインを付している。 When casting the same type as in Example 1 under the same continuous casting conditions, only the powder for continuous casting was changed to the powder shown in Table 3. Evaluation of the molten slag and slag bear was performed in the same manner as in Example 1. The results are shown in Table 3. Numerical values that deviate from the scope of the present invention and numerical values that deviate from the preferred range are underlined.
表３の「鋳片表面性状」において、「ＯＳＭ乱れ」は鋳片表面オシレーションマークの乱れを意味する。正常な凝固状態であれば、オシレーションマークはほぼ規則正しく形成される。これに対し、過大なスラグベアが形成されるとオシレーションマークの間隔が不均一になったり部分的に不明瞭になったりする。このような現象をＯＳＭ乱れとして表記した。また「形状異常」とは、鋳片コーナー部の長辺側に発生するへこみを意味する。パウダー潤滑が不十分となり、鋳型と凝固シェルとの間に局部的にエアギャップが生じることで、鋳型内において短辺部がバルジングし、そのため長辺側のコーナー部にへこみが生じる。即ち、本来矩形であるべき形状が短辺部で一部が膨らみ、それによって長辺側コーナー部にへこみが生じるのである。 In Table 3, “Slab Surface Properties”, “OSM Disturbance” means disturbance of the slab surface oscillation mark. If the solidification state is normal, the oscillation marks are formed almost regularly. On the other hand, if an excessive slag bear is formed, the interval between the oscillation marks becomes non-uniform or partially unclear. Such a phenomenon was expressed as OSM disturbance. The “abnormal shape” means a dent that occurs on the long side of the slab corner. Powder lubrication becomes insufficient, and an air gap is locally generated between the mold and the solidified shell, whereby the short side portion is bulged in the mold, and a dent is generated in the corner portion on the long side. In other words, the shape that should originally be a rectangle is partially swelled at the short side portion, thereby causing a dent at the long side corner portion.
表３において、本発明例Ｎｏ．３〜５は、パウダー及び溶融スラグのいずれも、本発明の範囲あるいは好ましい数値範囲を実現しており、スラグベア発生状況、パウダー消費量、鋳片表面性状、鋼板ヘゲ不良率のいずれも良好であり、溶融スラグ中に結晶は観察されなかった。 In Table 3, Invention Example No. 3-5, both the powder and the molten slag achieve the range of the present invention or the preferred numerical range, and all of the slag bear generation status, powder consumption, slab surface properties, and the ratio of unsatisfactory steel plate are good. There were no crystals observed in the molten slag.
比較例Ｎｏ．３は、パウダーの塩基度、Ｎａ2Ｏ含有量、ＭｇＯ含有量が本発明範囲から外れ、そのためパウダーの凝固温度、溶融スラグの塩基度、Ｎａ2Ｏ含有量、ＭｇＯ含有量、粘度、凝固温度が本発明範囲あるいは好ましい範囲を外れている。 Comparative Example No. 3, the basicity, Na 2 O content, and MgO content of the powder are out of the scope of the present invention, so the solidification temperature of the powder, the basicity of the molten slag, the Na 2 O content, the MgO content, the viscosity, and the solidification temperature. Is outside the scope of the present invention or preferred range.
比較例Ｎｏ．４は、パウダーの塩基度が本発明範囲から外れ、そのため溶融スラグの塩基度が本発明範囲を外れるとともに、Ｎａ2Ｏが鋼中Ａｌで還元され、溶融スラグ中のＮａ2Ｏ濃度が低減した。 Comparative Example No. No. 4, the basicity of the powder was out of the scope of the present invention, so the basicity of the molten slag was out of the scope of the present invention, and Na 2 O was reduced with Al in the steel, and the Na 2 O concentration in the molten slag was reduced. .
比較例Ｎｏ．５は、パウダー中Ａｌ2Ｏ3含有量とＭｇＯ含有量が本発明範囲を外れており、パウダー凝固温度が高く、溶融スラグのＡｌ2Ｏ3含有量、ＭｇＯ含有量、粘度が好適範囲から外れる結果となった。 Comparative Example No. No. 5, the Al 2 O 3 content and the MgO content in the powder are outside the scope of the present invention, the powder solidification temperature is high, and the Al 2 O 3 content, MgO content, and viscosity of the molten slag are outside the preferred ranges. As a result.
比較例Ｎｏ．６、７は、パウダーのＮａ2Ｏ含有量が好適範囲を外れ、そのためパウダーの粘度と凝固温度が好適範囲を外れた。溶融スラグのＮａ2Ｏ含有量、粘度と凝固温度が好適範囲を外れたのみならず、溶融スラグの塩基度とＡｌ2Ｏ3含有量も好適範囲を外れた。パウダーの粘度が高すぎたために溶融スラグの消費速度が遅く、溶融スラグ中のＳｉＯ2とＮａ2Ｏが鋼中Ａｌで還元されたためである。比較例Ｎｏ．６は、さらにパウダーと溶融スラグのＭｇＯ含有量が好適範囲を外れている。 Comparative Example No. In Nos. 6 and 7, the Na 2 O content of the powder was out of the preferred range, so the viscosity and coagulation temperature of the powder were out of the preferred range. Not only the Na 2 O content, viscosity and solidification temperature of the molten slag were out of the preferred range, but the basicity and Al 2 O 3 content of the molten slag were also out of the preferred range. This is because the consumption rate of the molten slag was slow because the viscosity of the powder was too high, and SiO 2 and Na 2 O in the molten slag were reduced with Al in the steel. Comparative Example No. In No. 6, the MgO content of the powder and molten slag is outside the preferred range.
比較例Ｎｏ．３〜７のいずれも、スラグベアの発生があった。また比較例Ｎｏ．３〜５は鋳片表面にオシレーションマークの乱れが見られ、Ｎｏ．６、７は粘度が特に高かったために潤滑不良となり、鋳片表面の形状異常にまで至った。鋼板ヘゲ不良率も、比較例Ｎｏ．３〜５は不良、Ｎｏ．６、７は特に不良であった。 Comparative Example No. In any of 3 to 7, slag bear was generated. Comparative Example No. In Nos. 3 to 5, the oscillation mark was disturbed on the slab surface. Nos. 6 and 7 had a particularly high viscosity, resulting in poor lubrication and an abnormal shape of the slab surface. The steel plate shading failure rate is also shown in Comparative Example No. 3 to 5 are bad, no. 6 and 7 were particularly bad.
比較例Ｎｏ．３、５、６は溶融スラグ中のＭｇＯが不足し、結晶としてゲーレナイトが観察された。Ｎｏ．３、４、６、７はＮａ2Ｏが不足し、カスピダインが観察された。Ｎｏ．４、７は塩基度が１を超え、ゲーレナイトが晶出しないかわりにスピネルが観察された。 Comparative Example No. In 3, 5, and 6, MgO in the molten slag was insufficient, and gehlenite was observed as crystals. No. 3, 4, 6, and 7 were deficient in Na 2 O, and caspidine was observed. No. In 4 and 7, the basicity exceeded 1, and spinel was observed instead of no gehlenite crystallizing.
Claims (7)
ここで、Ｔ．ＣａＯは、含有するＣａ分がすべてＣａＯであるとして算出した値である。 A powder for continuous casting used for continuous casting of high-Si high-Al steel having a Si concentration of 2% by mass or more and an Al concentration of 0.5% by mass or more, CaO / SiO 2 is 0.5 or less in mass ratio, MgO: 5% or more and 15% or less, Na 2 O: 10% or more, Al 2 O 3 : 5% or less, and viscosity at 1300 ° C. is 1 Pa A powder for continuous casting, characterized by being less than s and a solidification temperature of 1050 ° C. or lower.
Here, T.W. CaO is a value calculated assuming that all of the contained Ca is CaO.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2011131241A (en) * | 2009-12-24 | 2011-07-07 | Nippon Steel Corp | Continuous casting method |
| JP2011218411A (en) * | 2010-04-09 | 2011-11-04 | Nippon Steel Corp | POWDER FOR CONTINUOUS CASTING OF HIGH-Si AND HIGH-Al STEEL AND CONTINUOUS CASTING METHOD |
| JP2014000611A (en) * | 2013-10-10 | 2014-01-09 | Nippon Steel & Sumitomo Metal | Continuous casting method |
| JP2018122326A (en) * | 2017-01-31 | 2018-08-09 | 新日鐵住金株式会社 | Mold powder for continuous casting and continuous casting method for steel |
| CN109175287A (en) * | 2018-11-05 | 2019-01-11 | 首钢集团有限公司 | A kind of high-aluminum steel sheet billet continuous casting method |
| JP2020111773A (en) * | 2019-01-10 | 2020-07-27 | 日本製鉄株式会社 | MELTING METHOD OF HIGH Al-CONTAINING STEEL |
| JP2020142262A (en) * | 2019-03-05 | 2020-09-10 | 日本製鉄株式会社 | Method for producing mold powder for continuous casting and continuous casting method for steel |
| JP2021025122A (en) * | 2019-08-09 | 2021-02-22 | 日本製鉄株式会社 | MELTING METHOD OF HIGH Al-CONTAINING STEEL |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002096146A (en) * | 2000-09-20 | 2002-04-02 | Sumitomo Metal Ind Ltd | Mold powder for continuous casting |
| JP2004223599A (en) * | 2003-01-27 | 2004-08-12 | Sumitomo Metal Ind Ltd | Mold flux for continuously casting steel and continuous casting method |
| JP2005152973A (en) * | 2003-11-27 | 2005-06-16 | Jfe Steel Kk | HIGH SPEED CASTING METHOD FOR HIGH Al STEEL |
-
2007
- 2007-08-08 JP JP2007206707A patent/JP4932635B2/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002096146A (en) * | 2000-09-20 | 2002-04-02 | Sumitomo Metal Ind Ltd | Mold powder for continuous casting |
| JP2004223599A (en) * | 2003-01-27 | 2004-08-12 | Sumitomo Metal Ind Ltd | Mold flux for continuously casting steel and continuous casting method |
| JP2005152973A (en) * | 2003-11-27 | 2005-06-16 | Jfe Steel Kk | HIGH SPEED CASTING METHOD FOR HIGH Al STEEL |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011131241A (en) * | 2009-12-24 | 2011-07-07 | Nippon Steel Corp | Continuous casting method |
| JP2011218411A (en) * | 2010-04-09 | 2011-11-04 | Nippon Steel Corp | POWDER FOR CONTINUOUS CASTING OF HIGH-Si AND HIGH-Al STEEL AND CONTINUOUS CASTING METHOD |
| JP2014000611A (en) * | 2013-10-10 | 2014-01-09 | Nippon Steel & Sumitomo Metal | Continuous casting method |
| JP2018122326A (en) * | 2017-01-31 | 2018-08-09 | 新日鐵住金株式会社 | Mold powder for continuous casting and continuous casting method for steel |
| CN109175287A (en) * | 2018-11-05 | 2019-01-11 | 首钢集团有限公司 | A kind of high-aluminum steel sheet billet continuous casting method |
| JP2020111773A (en) * | 2019-01-10 | 2020-07-27 | 日本製鉄株式会社 | MELTING METHOD OF HIGH Al-CONTAINING STEEL |
| JP7156041B2 (en) | 2019-01-10 | 2022-10-19 | 日本製鉄株式会社 | Melting method of high Al content steel |
| JP2020142262A (en) * | 2019-03-05 | 2020-09-10 | 日本製鉄株式会社 | Method for producing mold powder for continuous casting and continuous casting method for steel |
| JP7425280B2 (en) | 2019-03-05 | 2024-01-31 | 日本製鉄株式会社 | Method for producing mold powder for continuous casting and continuous casting method for steel |
| JP2021025122A (en) * | 2019-08-09 | 2021-02-22 | 日本製鉄株式会社 | MELTING METHOD OF HIGH Al-CONTAINING STEEL |
| JP7273306B2 (en) | 2019-08-09 | 2023-05-15 | 日本製鉄株式会社 | Melting method of high Al content steel |
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