JP2001138018A - Method for continuously casting steel - Google Patents
Method for continuously casting steelInfo
- Publication number
- JP2001138018A JP2001138018A JP32218999A JP32218999A JP2001138018A JP 2001138018 A JP2001138018 A JP 2001138018A JP 32218999 A JP32218999 A JP 32218999A JP 32218999 A JP32218999 A JP 32218999A JP 2001138018 A JP2001138018 A JP 2001138018A
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- continuous casting
- steel
- sec
- slab
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Continuous Casting (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、鋳片表層部のホワ
イトバンド(負偏析)を抑制し、かつ鋳片内部の等軸晶
帯を確保し、高品質な連続鋳造鋳片を安定的に安価にて
製造することができる鋼の連続鋳造方法に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses white bands (negative segregation) in the surface layer of a slab, secures equiaxed zones in the slab, and stably produces a high-quality continuous cast slab. The present invention relates to a continuous casting method of steel that can be manufactured at low cost.
【0002】[0002]
【従来の技術】従来、鋳片の表層部及び内部品質向上を
目的として、例えば、以下のような電磁撹拌を用いた連
続鋳造方法が提案されている。2. Description of the Related Art Conventionally, for the purpose of improving the surface layer portion and internal quality of a slab, for example, the following continuous casting method using electromagnetic stirring has been proposed.
【0003】特開平6−606号では、鋳型内で一方向
に循環するメニスカス溶鋼流を形成するように電磁撹拌
用のコイル中心をメニスカス近傍に位置させると共に、
鋳型内におけるメニスカス溶鋼流速が10〜60cm/
secとなるように移動磁界を印加して、表面性状の向
上を図るようにするものが提案されている。In Japanese Patent Application Laid-Open No. 6-606, the center of a coil for electromagnetic stirring is positioned near the meniscus so as to form a meniscus molten steel flow circulating in one direction in a mold.
Meniscus molten steel flow rate in the mold is 10-60 cm /
A method has been proposed in which a moving magnetic field is applied so that the surface property is improved so as to improve the surface properties.
【0004】特開平9−47853号では、溶鋼流速が
20〜60cm/secとなるように、一方の短辺から
長辺に沿って内側に向かわせる初期の加速段階のローレ
ンツ力と、内側から他方の短辺に向かわせる後期の加速
段階のローレンツ力との比を規定して、凝固シェル上の
介在物除去、及び湯面のパウダー巻込みを防止し、品質
の向上を図るものが提案されている。In Japanese Patent Application Laid-Open No. 9-47853, the Lorentz force in an initial acceleration stage in which the molten steel flows inward from one short side to the long side so that the flow velocity of the molten steel is 20 to 60 cm / sec, and the other is from the inside to the other. In order to improve the quality, it defines the ratio to the Lorentz force in the later acceleration stage to move toward the short side, removes inclusions on the solidified shell, prevents powder entrainment of the molten metal surface, and improves quality. I have.
【0005】特開平8−187557号では、底を有し
ない筒状単孔型のノズルを用いて、溶鋼を鋳造方向に供
給し、メニスカスにおける溶鋼表面の流速に10〜30
cm/secの上下限値を設けて制御することで、メニ
スカスでの凝固(皮張り)抑制、介在物及び気泡性欠陥
の低減に加えて、過度なメニスカス溶鋼流動に起因する
パウダー巻込性欠陥を抑制するものが提案されている。In Japanese Patent Application Laid-Open No. 8-187557, molten steel is supplied in a casting direction using a cylindrical single-hole type nozzle having no bottom, and the flow velocity of the molten steel surface at the meniscus is increased by 10 to 30.
By controlling the upper and lower limits of cm / sec, the solidification (skinning) at the meniscus is suppressed, the inclusions and the porosity defects are reduced, and the powder entanglement defects due to the excessive meniscus flow of the molten steel. The one which suppresses is proposed.
【0006】ところが、電磁撹拌の撹拌強度が強すぎる
と、パウダー巻込性欠陥が増加することに加えて、撹拌
時の凝固界面に負偏析(以下、ホワイトバンドと称す)
を生じるといった問題がある。[0006] However, if the stirring intensity of the electromagnetic stirring is too high, powder seizure defects increase, and negative segregation occurs at the solidification interface during stirring (hereinafter referred to as white band).
Problem.
【0007】ホワイトバンドは、鋼材の焼き入れ性及び
表層部の機械的性質に支障を来すので、鋳片表層部の機
械的強度仕様の厳しい部材を、連続鋳造機で製造する際
には、鋳片表層部におけるホワイトバンドの生成を可及
的に抑制する必要がある。[0007] The white band interferes with the hardenability of the steel material and the mechanical properties of the surface layer portion. Therefore, when a member having severe mechanical strength specifications of the slab surface layer portion is manufactured by a continuous casting machine, It is necessary to suppress generation of a white band in the surface layer of the slab as much as possible.
【0008】こうしたホワイトバンドの生成を抑制する
ことを目的として、例えば、以下のような電磁撹拌を用
いた連続鋳造方法が提案されている。For the purpose of suppressing the generation of such white bands, for example, the following continuous casting method using electromagnetic stirring has been proposed.
【0009】特公昭63−48619号には、電磁撹拌
装置の配置位置を規定すると共に、鋳片未凝固部と凝固
部の界面における磁束密度と撹拌時間の積を規制するこ
とにより、ホワイトバンドの生成を抑制するものが提案
されている。In Japanese Patent Publication No. 63-48619, the position of the electromagnetic stirrer is specified, and the product of the magnetic flux density and the stirring time at the interface between the unsolidified portion and the solidified portion of the slab is regulated. Those that suppress generation have been proposed.
【0010】特公昭62−47103号には、ブルーム
鋳片の横断面面積凝固率が規定値を満足する範囲内に電
磁撹拌位置を配置することで、一定撹拌力で最大の等軸
晶帯を生成することができると共に、ホワイトバンドの
生成を抑制するものが提案されている。Japanese Patent Publication No. 62-47103 discloses that the maximum equiaxed zone is formed with a constant stirring force by arranging an electromagnetic stirring position within a range in which the cross-sectional area solidification rate of a bloom slab satisfies a specified value. A device that can generate the white band and suppresses the generation of the white band has been proposed.
【0011】特開昭53−45627号公報には、電磁
撹拌位置、磁束密度、鋳造速度を調整することで、凝固
組織を微細化し鋼材の内部性状を改善してホワイトバン
ドの生成を抑制するものが提案されている。Japanese Patent Application Laid-Open No. 53-45627 discloses a method in which the electromagnetic stirring position, magnetic flux density, and casting speed are adjusted to refine the solidification structure, improve the internal properties of steel, and suppress the generation of white bands. Has been proposed.
【0012】[0012]
【発明が解決しようとする課題】撹拌力を過度に増加す
ることによって生成されるホワイトバンドは、上記した
ように、鋼材の焼入性及び表層部の機械的性質に支障を
来す。従って、電磁撹拌を用いた鋼の連続鋳造方法にお
いては、原則として、未凝固溶鋼に電磁撹拌を付与して
凝固組織の等軸晶化を促進させつつも、なおかつホワイ
トバンドを生成させないことが望ましい。As described above, the white band generated by excessively increasing the stirring force impairs the hardenability of the steel material and the mechanical properties of the surface layer. Therefore, in the continuous casting method of steel using electromagnetic stirring, in principle, it is desirable to impart electromagnetic stirring to unsolidified molten steel to promote equiaxed crystallization of the solidified structure, but not to generate a white band. .
【0013】しかしながら、上記提案された従来の連続
鋳造方法では、鋳造する鋼種に応じて電磁撹拌条件を変
更しなければならないので、1つの連続鋳造機で種々の
鋼種を鋳造するに際し、多岐に亘る鋼種において高品質
な鋳片を製造するためには、各鋼種に対して、適正な電
磁撹拌条件を適用する必要がある。よって、従来のよう
に、多くの鋼種を同一の電磁撹拌条件によって鋳造する
と、鋼種によっては凝固組織に有害な欠陥を生じるとい
った問題があった。However, in the conventional continuous casting method proposed above, the electromagnetic stirring conditions must be changed according to the type of steel to be cast. Therefore, when casting various types of steel with one continuous casting machine, a wide variety of methods are required. In order to produce high quality slabs of steel types, it is necessary to apply appropriate electromagnetic stirring conditions to each steel type. Therefore, when many steel types are cast under the same electromagnetic stirring conditions as in the related art, there is a problem that a harmful defect occurs in a solidified structure depending on the steel type.
【0014】本発明は、上記した問題を解決するために
なされたものであり、1台の連続鋳造機において、偏析
の有害性が異なる複数の鋼種を鋳造するに際し、鋳造速
度が速くても鋳片表層部のホワイトバンドの生成を抑制
することができ、かつ鋳片中心部の等軸晶帯を確保して
連続鋳造を安定して効率的に行うことができる鋼の連続
鋳造方法を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. In a single continuous casting machine, when casting a plurality of steel types having different harmful effects of segregation, the casting speed is high even if the casting speed is high. Provided is a steel continuous casting method capable of suppressing generation of a white band in one surface layer portion, securing an equiaxed crystal zone in a central portion of a slab, and performing continuous casting stably and efficiently. The purpose is to:
【0015】[0015]
【課題を解決するための手段】本発明者らは、上記目的
を達成するために、各種の実験を行った結果、同一の電
磁撹拌強度であっても、溶鋼中の炭素濃度(以下溶鋼中
炭素濃度と記す)の高い高炭素鋼ほど、鋳片表皮下にホ
ワイトバンドが顕著に生じることを見出した。そして、
溶鋼中炭素濃度及び溶鋼流速とホワイトバンドの生成割
合の関係を実験により解明した結果、鋳型内における電
磁撹拌印加時のホワイトバンドの生成が、凝固シェルの
凝固速度に依存することも見出した。Means for Solving the Problems The present inventors have conducted various experiments to achieve the above object. As a result, even if the electromagnetic stirring strength is the same, the carbon concentration in the molten steel (hereinafter referred to as the molten steel It was found that the higher the carbon content of the steel, the higher the white band was formed under the surface of the slab. And
The relationship between the carbon concentration in the molten steel, the flow rate of the molten steel, and the formation ratio of the white band was clarified by experiments, and it was also found that the formation of the white band when the electromagnetic stirring was applied in the mold was dependent on the solidification speed of the solidified shell.
【0016】本発明の鋼の連続鋳造方法は、上記した知
見に基づいてなされたものであり、連続鋳造用の鋳型に
移動磁界を溶鋼に印加する電磁石コイルを設置して、鋳
型内で20mm厚以下の凝固シェルが生成する領域で、
凝固シェル界面における平均溶鋼流速をU(cm/se
c)、凝固シェルの平均凝固速度をV(cm/sec)
としたとき、鋳造方向に対して直交する溶鋼流動速度が
下式を満たすように電磁撹拌を行うものである。 5.0≦U≦(19.2×V0.195 )/溶鋼中炭素濃度 ただし、溶鋼中炭素濃度(%)≦1.0 V=0.001〜0.50cm/sec とする。The method for continuous casting of steel according to the present invention is based on the above-mentioned findings. An electromagnet coil for applying a moving magnetic field to molten steel is installed in a mold for continuous casting, and a 20 mm-thick steel sheet is formed in the mold. In the area where the following solidified shells form,
The average molten steel flow rate at the solidified shell interface is defined as U (cm / sec).
c), the average solidification speed of the solidified shell is V (cm / sec)
In this case, the electromagnetic stirring is performed so that the molten steel flow velocity perpendicular to the casting direction satisfies the following expression. 5.0 ≦ U ≦ (19.2 × V 0.195 ) / carbon concentration in molten steel However, carbon concentration (%) in molten steel ≦ 1.0 V = 0.001 to 0.50 cm / sec.
【0017】このようにすることで、鋳片表層部のホワ
イトバンドを抑制することができ、かつ鋳片中心部の等
軸晶帯も確保することができ、さらには、1台の連続鋳
造機で偏析の有害性が異なる複数の鋼種を安定して効率
的に鋳造することができる。By doing so, the white band at the surface layer of the slab can be suppressed, and the equiaxed crystal zone at the center of the slab can be secured. Thus, a plurality of steel types having different harmful effects of segregation can be cast stably and efficiently.
【0018】[0018]
【発明の実施の形態】本発明は、例えば次のように実施
される。図1(a)は丸ビレットの連続鋳造を、図1
(b)はスラブ連続鋳造用を、行うときの状況を各々示
す。これらの鋳型には、溶鋼2に移動磁界を印加するた
めの電磁石コイル3が設置されている。また、溶鋼2
は、浸漬ノズル4を経て鋳型へと各々注湯される。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is implemented, for example, as follows. FIG. 1A shows continuous casting of a round billet, and FIG.
(B) shows the situation when performing slab continuous casting, respectively. An electromagnet coil 3 for applying a moving magnetic field to the molten steel 2 is installed in these molds. In addition, molten steel 2
Are respectively poured into the mold through the immersion nozzle 4.
【0019】電磁石コイル3における磁場印加条件は、
周波数が1〜10Hz、電流値が100〜800A、移
動磁場が0〜1000テスラ(1G=100μT)と
し、鋳型に設置した電磁コイル3を使って溶鋼2に移動
磁場を印加する。このとき、凝固シェルに沿った水平方
向の溶鋼2の流動、つまり丸ビレットの連続鋳造では周
方向の旋回流動、スラブの連続鋳造では短辺から長辺に
沿った旋回流動、が誘起される。The conditions for applying a magnetic field to the electromagnet coil 3 are as follows:
The frequency is 1 to 10 Hz, the current value is 100 to 800 A, the moving magnetic field is 0 to 1000 Tesla (1 G = 100 μT), and the moving magnetic field is applied to the molten steel 2 using the electromagnetic coil 3 installed in the mold. At this time, a flow of the molten steel 2 in the horizontal direction along the solidified shell, that is, a swirling flow in the circumferential direction in continuous casting of round billets, and a swirling flow in short to long sides in continuous casting of slabs are induced.
【0020】溶鋼2の流動が誘起されると、凝固シェル
における未凝固溶鋼の界面付近(以下、「凝固前面」と
いう)は、洗浄効果を受けて凝固前面の液相濃度が低下
し、その結果、溶鋼2の平衡分配係数に応じて凝固前面
の固層側の溶質濃度は低下する。また、凝固シェル付近
の溶鋼流速が増加し過ぎると、つまり電磁撹拌による溶
鋼2の撹拌強度が大きいと、この撹拌の影響を受けた凝
固シェルにはホワイトバンド(負偏析帯)が生成される
ことになる。When the flow of the molten steel 2 is induced, the vicinity of the interface of the unsolidified molten steel in the solidified shell (hereinafter, referred to as the “solidified front”) is subjected to a washing effect, and the liquid phase concentration on the solidified front is reduced. The solute concentration on the solid layer side of the solidification front decreases in accordance with the equilibrium distribution coefficient of the molten steel 2. Also, if the molten steel flow velocity near the solidified shell is excessively increased, that is, if the stirring intensity of the molten steel 2 by the electromagnetic stirring is large, a white band (negative segregation zone) is generated in the solidified shell affected by the stirring. become.
【0021】ホワイトバンドは、鋼材の焼入性及び表層
部の機械的性質に支障を来すから、これを抑制するため
に、電磁撹拌による溶鋼撹拌強度を低下させることが要
求される。[0021] Since the white band interferes with the hardenability of the steel material and the mechanical properties of the surface layer, it is required to reduce the stirring strength of the molten steel by electromagnetic stirring in order to suppress this.
【0022】その一方で、電磁撹拌を実施することで、
鋳片中心部のポロシティ減少、等軸晶帯増加、鋳片表層
部の介在物・気泡除去など、鋳片品質を向上させる効果
があることは先に説明した通り周知である。本発明者ら
の実験においても、鋳片中心部の等軸晶率は、8.0%
以上確保することで中心部の正偏析の抑制及びポロシテ
ィ減少に効果があることを見出している。On the other hand, by performing electromagnetic stirring,
As described above, it is well known that there are effects of improving slab quality, such as decreasing porosity at the center of the slab, increasing the number of equiaxed crystal zones, and removing inclusions and bubbles from the surface layer of the slab. In the experiments of the present inventors, the equiaxed crystal ratio at the center of the slab was 8.0%.
It has been found that securing the above is effective in suppressing the positive segregation in the center and reducing the porosity.
【0023】従って、電磁撹拌使用時には、ホワイトバ
ンドが生成しない撹拌強度の限界値を正確に知る必要が
あり、その値以下で極力凝固シェル界面での溶鋼流動を
誘起させるよう電磁撹拌を実施することで鋳片の品質が
保証される。Therefore, when using electromagnetic stirring, it is necessary to accurately know the limit value of the stirring intensity at which a white band is not generated, and it is necessary to perform the electromagnetic stirring so as to induce the flow of molten steel at the solidified shell interface as much as the limit value or less. Guarantees the quality of the slab.
【0024】本発明者らは、丸ビレットの連造鋳造機を
用いて種々の溶鋼中炭素濃度の鋼種を鋳造し、電磁撹拌
実施時における鋳片表層部の偏析度Ci /C0 を調査し
た。なお、Ci は鋳片表層部20mm以内の平均の溶鋼
中炭素濃度(%)、C0 は母材の溶鋼中炭素濃度
(%)、を各々意味する。The present inventors cast various steel types having a carbon concentration in molten steel by using a round billet continuous casting machine, and investigated the segregation degree C i / C 0 of the surface layer of the slab during electromagnetic stirring. did. Incidentally, C i is the molten steel in the carbon concentration of the average within the slab surface portion 20 mm (%), C 0 is the molten steel in the carbon concentration in the mother material (%) means respectively.
【0025】図2は、鋳型内において、溶鋼中炭素濃度
の異なる鋼種溶鋼に電磁撹拌を実施した場合に発生する
凝固シェル付近の平均溶鋼流速U(cm/sec)と、
溶鋼中炭素濃度との関係を示す。ここでの平均流速と
は、図1(a)の丸ビレット連続鋳造の場合には、周方
向の旋回流動させた平均流速を、また、図1(b)のス
ラブの連続鋳造の場合には、短辺−長辺に沿った旋回流
動させた平均流速を、各々意味する。FIG. 2 shows the average molten steel flow velocity U (cm / sec) near the solidified shell generated when electromagnetic stirring is performed on molten steel having different carbon concentrations in molten steel in the mold.
The relationship with the carbon concentration in molten steel is shown. Here, the average flow velocity is the average flow velocity of the circular billet continuous casting shown in FIG. 1A, and the average flow velocity swirled in the circumferential direction. In the case of the continuous casting of the slab shown in FIG. , Mean mean flow velocity swirled along the short side-long side.
【0026】鋳型内における溶鋼流速の測定は、カルマ
ン渦流速計により測定した。この測定原理の概略を図6
に示す。図6において、サイアロン棒5付近で溶鋼流が
通過すると、サイアロン棒5のまわりにカルマン渦2a
が発生し、このカルマン渦2aがサイアロン棒5を介し
て振動板6を振動させる。この振動板6の左右振動を周
波数解析した後、流速に変換することで測定が行われ
る。The flow rate of molten steel in the mold was measured by a Karman vortex flow meter. An outline of this measurement principle is shown in FIG.
Shown in In FIG. 6, when the molten steel flow passes near the sialon rod 5, the Karman vortex 2a surrounds the sialon rod 5.
Is generated, and the Karman vortex 2 a vibrates the diaphragm 6 via the sialon rod 5. After the frequency analysis of the left-right vibration of the vibration plate 6, the measurement is performed by converting the vibration into a flow velocity.
【0027】本発明者らの実験の結果、偏析度Ci /C
0 は、溶鋼中炭素濃度が増加すると、図2のように凝固
シェル付近の平均溶鋼流速に拘わらず直線関係的に低下
することを知見した。また、図3には、偏析度Ci /C
0 と溶鋼の平均凝固速度V(cm/sec)との関係を
示す。平均凝固速度Vは、鋳片の二次デンドライトアー
ム間隔から測定した。図3に示すように、鋳片表層部の
偏析度Ci /C0 は、未凝固シェル付近の平均溶鋼流速
に拘わらず平均凝固速度Vに対し、指数関数的に増加す
ることが、実験により判明した。As a result of our experiments, the segregation degree C i / C
0 found that as the carbon concentration in the molten steel increased, it decreased linearly regardless of the average molten steel flow velocity near the solidified shell as shown in FIG. FIG. 3 shows the segregation degree C i / C
The relationship between 0 and the average solidification rate V (cm / sec) of molten steel is shown. The average solidification speed V was measured from the interval between the secondary dendrite arms of the slab. As shown in FIG. 3, experiments show that the segregation degree C i / C 0 at the surface layer of the slab increases exponentially with respect to the average solidification velocity V regardless of the average molten steel flow velocity near the unsolidified shell. found.
【0028】以上、図2及び図3から、偏析度Ci /C
0 と鋼種の溶鋼中炭素濃度、平均溶鋼流速U及び溶鋼の
平均凝固速度Vとの関係を多重回帰により求めた結果、
下記(1)式の関係が成り立つことを見出した。 Ci /C0 =1−[1.04 ×10-3×{(溶鋼中炭素濃度×U) /V0.195 }]…(1) ただし、この数式(1)は、溶鋼中炭素濃度が1.0%
以下、平均凝固速度Vは、0.001〜0.50cm/
secの範囲において成立する。As described above, from FIGS. 2 and 3, the segregation degree C i / C
As a result of obtaining the relationship between 0 and the carbon concentration in the molten steel of the steel type, the average molten steel flow velocity U and the average solidification velocity V of the molten steel by multiple regression,
It has been found that the relationship of the following equation (1) is established. C i / C 0 = 1− [1.04 × 10 −3 × {(carbon concentration in molten steel × U) / V 0.195 }] (1) However, in this equation (1), the carbon concentration in molten steel is 1.0. %
Hereinafter, the average solidification speed V is 0.001 to 0.50 cm /
It is satisfied in the range of sec.
【0029】通常、溶鋼中炭素濃度が、1.0%を超え
る鋼種はなく、また、平均凝固速度Vも、通常0.00
1〜0.5cm/secの範囲である。Normally, there is no steel type in which the carbon concentration in molten steel exceeds 1.0%, and the average solidification speed V is usually 0.00%.
It is in the range of 1 to 0.5 cm / sec.
【0030】さらに、本発明者らは、上記実験から鋳片
表層部の機械的強度を確保するためには、つまりホワイ
トバンドを抑制するためには、溶鋼中炭素濃度と溶鋼流
速Uとの関係において、偏析度Ci /C0 が0.98以
上であればよいことを知見した。Further, the present inventors have found from the above experiments that in order to secure the mechanical strength of the surface layer of the slab, that is, to suppress the white band, the relationship between the carbon concentration in the molten steel and the flow rate U of the molten steel was determined. , It was found that the segregation degree C i / C 0 should be 0.98 or more.
【0031】加えて、鋳片中心部の等軸晶率を8.0%
以上確保するためには、つまり中心部正偏析抑制及びポ
ロシティ減少のためには、図4に示すように、平均溶鋼
流速Uと鋳片中心部の等軸晶率との関係において、凝固
シェル界面における平均溶鋼流速Uを5.0cm/se
c以上、望ましくは平均流速Uを10.0cm/sec
以上とすればよいことを知見した。In addition, the equiaxed crystal ratio at the center of the slab is 8.0%.
In order to ensure the above, that is, to suppress the central positive segregation and reduce the porosity, as shown in FIG. 4, the relationship between the average molten steel flow velocity U and the equiaxed crystallinity at the center of the slab, The average molten steel flow rate U at 5.0 cm / sec
c or more, desirably an average flow velocity U of 10.0 cm / sec.
It was found that the above should be done.
【0032】従って、電磁撹拌を用いた鋼の連続鋳造方
法において、鋳片表層部のホワイトバンドを抑制しつつ
鋳片中心部の等軸晶を確保するためには、鋳型内の平均
溶鋼流速Uを、上記(1)式を変形して下記式の範囲に
規定すればよいのである。 5.0≦U≦(19.2×V0.195 )/溶鋼中炭素濃度 ただし、溶鋼中炭素濃度(%)≦1.0 V=0.001〜0.50cm/sec とする。Therefore, in the continuous casting method of steel using electromagnetic stirring, in order to suppress the white band on the surface layer of the slab and to secure the equiaxed crystal at the center of the slab, the average molten steel flow rate in the mold U Can be defined in the range of the following equation by modifying the above equation (1). 5.0 ≦ U ≦ (19.2 × V 0.195 ) / carbon concentration in molten steel However, carbon concentration (%) in molten steel ≦ 1.0 V = 0.001 to 0.50 cm / sec.
【0033】このように、溶鋼中炭素濃度、平均凝固速
度Vに基づいて、平均溶鋼流速Uを上記式の規定範囲内
とすることで、図5に示すように、ホワイトバンドの生
成を確実に抑制することができるようになる。As described above, by setting the average molten steel flow velocity U within the specified range of the above equation based on the carbon concentration in the molten steel and the average solidification velocity V, as shown in FIG. It can be suppressed.
【0034】[0034]
【実施例】以下に、本発明の鋼の鋳造方法の効果を確認
するために行った実施例について説明する。表1,2
は、直径が225mmの円形横断面を有する連続鋳造用
の鋳型を用いて、鋳造速度が2.0m/min、オシレ
ーションストロークが4.0mmの鋳造条件で丸ビレッ
ト鋳片を連続鋳造したときの各条件及び結果である。EXAMPLES Examples performed to confirm the effects of the steel casting method of the present invention will be described below. Tables 1, 2
Is obtained by continuously casting round billet slabs using a casting mold having a circular cross section having a diameter of 225 mm and a casting speed of 2.0 m / min and an oscillation stroke of 4.0 mm. These are the conditions and results.
【0035】表3は、長辺長さが1000mm、短辺長
さが300mmの角形横断面を有する連続鋳造用の鋳型
を用いて、鋳造速度が1.4m/min、オシレーショ
ンストロークが5.0mmの鋳込み条件でスラブ鋳片を
連続鋳造したときの各条件及び結果である。Table 3 shows that a continuous casting mold having a rectangular cross section with a long side length of 1000 mm and a short side length of 300 mm was used, the casting speed was 1.4 m / min, and the oscillation stroke was 5. It is each condition and result when a slab slab is continuously cast under the casting condition of 0 mm.
【0036】丸ビレット鋳片及びスラブ鋳片は共に普通
鋼であり、溶鋼中の主要成分は、C:0.01〜1.0
%、Si:0.01〜3.0%、Mn:0.01〜2.0
%、P:0.001〜0.5%、S:0.0001〜
0.05%である。なお、凝固シェルの凝固速度は、鋳
型内冷却水の水温及び冷却水流速を変化させることで制
御した。Both the round billet slab and the slab slab are ordinary steel, and the main components in the molten steel are C: 0.01 to 1.0.
%, Si: 0.01 to 3.0%, Mn: 0.01 to 2.0
%, P: 0.001 to 0.5%, S: 0.0001 to
0.05%. The solidification speed of the solidified shell was controlled by changing the temperature of the cooling water in the mold and the flow rate of the cooling water.
【0037】[0037]
【表1】 [Table 1]
【0038】[0038]
【表2】 [Table 2]
【0039】[0039]
【表3】 [Table 3]
【0040】表1〜表3に示すように、本発明の規定範
囲内に相当するA,B,D,E,G,H,J,L,N,
Q,R,S,V,Wについては、鋳片表層部における偏
析度Ci /C0 が0.98以上となり、従ってホワイト
バンドの抑制効果が見られ、加えて等軸晶率も8.0%
以上とすることができ、鋳片品質が向上した。As shown in Tables 1 to 3, A, B, D, E, G, H, J, L, N,
As for Q, R, S, V, and W, the segregation degree C i / C 0 in the surface layer of the slab is 0.98 or more, and therefore, an effect of suppressing a white band is observed, and the equiaxed crystal ratio is also 8. 0%
As a result, the slab quality was improved.
【0041】一方、本発明の規定範囲外に相当するC,
F,I,K,M,O,P,T,U,Xについては、等軸
晶率は8.0%以上となったが、鋳片表層部における偏
析度Ci /C0 が0.98より小さいため、ホワイトバ
ンドが生成され、鋳片表層部の機械強度の不足減少が発
生した。On the other hand, C, which is out of the specified range of the present invention,
For F, I, K, M, O, P, T, U, and X, the equiaxed crystal ratio was 8.0% or more, but the segregation degree C i / C 0 in the slab surface layer was 0.1%. Since it is smaller than 98, a white band was generated, and the shortage of mechanical strength of the surface layer portion of the slab was reduced.
【0042】なお、これら表1〜表3の結果以外にさら
に複数回実験した結果も加味して、一例として、平均凝
固速度Vが0.02cm/secの時の溶鋼中炭素濃度
と平均溶鋼流速Uとの関係を図5に示す。同図から明ら
かなように、本発明方法に適合した電磁撹拌を行うこと
を特徴とする連続鋳造によりホワイトバンドの生成が確
実に抑制できた。In addition to the results of Tables 1 to 3, in addition to the results of a plurality of experiments, as an example, the carbon concentration in the molten steel and the average molten steel flow rate when the average solidification velocity V is 0.02 cm / sec. FIG. 5 shows the relationship with U. As is clear from the figure, the formation of a white band was reliably suppressed by continuous casting characterized by performing electromagnetic stirring suitable for the method of the present invention.
【0043】[0043]
【発明の効果】以上のように、本発明の鋼の連続鋳造方
法は、溶鋼中炭素濃度と平均凝固速度Vに基づいて、電
磁撹拌による溶鋼平均流速Uを常に最適に規定して連続
鋳造を行うので、1台の連続鋳造機において、偏析の有
害性が異なる多数の鋼種を鋳造する場合においても、鋳
片表層部のホワイトバンドの生成を確実に抑制すること
ができ、かつ鋳片中心部の等軸晶帯を確保して連続鋳造
を安定して効率的に行うことができる。As described above, according to the continuous casting method of the present invention, the average flow velocity U of the molten steel by the electromagnetic stirring is always optimally defined based on the carbon concentration in the molten steel and the average solidification velocity V. Therefore, even in the case of casting a large number of steel types having different harmful effects of segregation in one continuous casting machine, it is possible to surely suppress the generation of white bands on the surface layer of the slab, and at the center of the slab. The continuous casting can be stably and efficiently performed by securing the equiaxed crystal zone.
【図1】電磁撹拌を用いた鋼の連続鋳造状況を示し、
(a)は丸ビレットの連続鋳造状況を、(b)はスラブ
連続鋳造状況を、各々示す図である。FIG. 1 shows a continuous casting state of steel using electromagnetic stirring.
(A) is a figure which shows the continuous casting situation of a round billet, (b) is a figure which shows the slab continuous casting situation, respectively.
【図2】溶鋼中炭素濃度と偏析度との関係を示す図であ
る。FIG. 2 is a diagram showing the relationship between the carbon concentration in molten steel and the degree of segregation.
【図3】平均凝固速度と偏析度との関係を示す図であ
る。FIG. 3 is a diagram showing the relationship between the average solidification rate and the degree of segregation.
【図4】平均溶鋼流速と鋳片中心部の等軸晶率との関係
を示す図である。FIG. 4 is a diagram showing the relationship between the average molten steel flow velocity and the equiaxed crystal ratio at the center of a slab.
【図5】溶鋼中炭素濃度と平均溶鋼流速との関係を示す
図である。FIG. 5 is a graph showing the relationship between the carbon concentration in molten steel and the average molten steel flow velocity.
【図6】溶鋼流速の測定原理を説明するための図であ
る。FIG. 6 is a view for explaining the principle of measuring the flow rate of molten steel.
2 溶鋼 3 電磁石コイル 4 浸漬ノズル 2 Molten steel 3 Electromagnetic coil 4 Immersion nozzle
Claims (1)
型内に注湯して鋳片を製造する際に、未凝固溶鋼に対し
て電磁撹拌を行う鋼の連続鋳造方法において、鋳型内で
20mm厚以下の凝固シェルが生成する領域で、凝固シ
ェル界面における平均溶鋼流速をU(cm/sec)、
凝固シェルの平均凝固速度をV(cm/sec)とした
とき、鋳造方向に対して直交する溶鋼流動速度が下式を
満たすように電磁撹拌を行うことを特徴とする鋼の連続
鋳造方法。 5.0≦U≦(19.2×V0.195 )/溶鋼中炭素濃度 ただし、溶鋼中炭素濃度(%)≦1.0 V=0.001〜0.50cm/sec とする。When a molten steel is poured into a casting mold for continuous casting through an immersion nozzle to produce a cast slab, a method of continuous casting steel in which electromagnetic stirring is performed on unsolidified molten steel is performed. In a region where a solidified shell having a thickness of 20 mm or less is formed, the average molten steel flow rate at the solidified shell interface is U (cm / sec),
A continuous casting method for steel, characterized in that electromagnetic stirring is performed such that a molten steel flow velocity perpendicular to a casting direction satisfies the following formula, when an average solidification speed of a solidified shell is V (cm / sec). 5.0 ≦ U ≦ (19.2 × V 0.195 ) / carbon concentration in molten steel However, carbon concentration (%) in molten steel ≦ 1.0 V = 0.001 to 0.50 cm / sec.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32218999A JP3257546B2 (en) | 1999-11-12 | 1999-11-12 | Steel continuous casting method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32218999A JP3257546B2 (en) | 1999-11-12 | 1999-11-12 | Steel continuous casting method |
Publications (2)
Publication Number | Publication Date |
---|---|
JP2001138018A true JP2001138018A (en) | 2001-05-22 |
JP3257546B2 JP3257546B2 (en) | 2002-02-18 |
Family
ID=18140947
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP32218999A Expired - Fee Related JP3257546B2 (en) | 1999-11-12 | 1999-11-12 | Steel continuous casting method |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP3257546B2 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006231396A (en) * | 2005-02-28 | 2006-09-07 | Jfe Steel Kk | Continuous casting method for extralow carbon steel slab |
JP2010052022A (en) * | 2008-08-29 | 2010-03-11 | Jfe Steel Corp | Method for continuously casting ferritic stainless steel |
JP2010227944A (en) * | 2009-03-26 | 2010-10-14 | Jfe Steel Corp | Continuous casting method for steel cast slab |
-
1999
- 1999-11-12 JP JP32218999A patent/JP3257546B2/en not_active Expired - Fee Related
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006231396A (en) * | 2005-02-28 | 2006-09-07 | Jfe Steel Kk | Continuous casting method for extralow carbon steel slab |
JP4569320B2 (en) * | 2005-02-28 | 2010-10-27 | Jfeスチール株式会社 | Continuous casting method of ultra-low carbon steel slab slab |
JP2010052022A (en) * | 2008-08-29 | 2010-03-11 | Jfe Steel Corp | Method for continuously casting ferritic stainless steel |
JP2010227944A (en) * | 2009-03-26 | 2010-10-14 | Jfe Steel Corp | Continuous casting method for steel cast slab |
Also Published As
Publication number | Publication date |
---|---|
JP3257546B2 (en) | 2002-02-18 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
KR100946612B1 (en) | A device and a method for continuous casting | |
US3952791A (en) | Method of continuous casting using linear magnetic field for core agitation | |
JPS645984B2 (en) | ||
JP3257546B2 (en) | Steel continuous casting method | |
US5137077A (en) | Method of controlling flow of molten steel in mold | |
JP2006281218A (en) | Method for continuously casting steel | |
JP2020015083A (en) | Flow control apparatus for thin slab continuous casting and continuous casting method for thin slab | |
JPH0523804A (en) | Production of cast steel slab | |
JPH05329594A (en) | Method for controlling molten steel flow in continuous casting mold | |
WO2022138002A1 (en) | Continuous casting method for steel | |
JP4910357B2 (en) | Steel continuous casting method | |
JP4163817B2 (en) | Method for continuous casting of molten steel, electromagnetic vibration applying device and continuous cast slab | |
JPH06606A (en) | Controller for flow of molten steel in continuous casting mold | |
JPH05237621A (en) | Continuous casting method | |
JP2885824B2 (en) | Metal continuous casting method | |
JP2607332B2 (en) | Flow control device for molten steel in continuous casting mold | |
JP2003275849A (en) | Method for producing continuously cast slab | |
JP3422946B2 (en) | Continuous casting method and continuous casting slab of molten steel | |
JPH0671400A (en) | Device for controlling flow of molten steel in continuous casting mold | |
JPH10180426A (en) | Electromagnetic stirring method in mold in continuous casting | |
RU2464123C1 (en) | Method of adjusting conditions of electromagnetic mixing of ingot liquid phase in slab continuous casting machine and device to this end | |
JPH09122833A (en) | Method for concentrating solute on surface layer of cast slab in continuous casting | |
JP2002126856A (en) | Continuous casting method and cast piece | |
JP2009535216A (en) | Stirrer | |
JPH08300113A (en) | Method for reducing non-metallic inclusion in continuous casting |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
TRDD | Decision of grant or rejection written | ||
R150 | Certificate of patent or registration of utility model |
Ref document number: 3257546 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20071207 Year of fee payment: 6 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20081207 Year of fee payment: 7 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091207 Year of fee payment: 8 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101207 Year of fee payment: 9 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101207 Year of fee payment: 9 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111207 Year of fee payment: 10 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111207 Year of fee payment: 10 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121207 Year of fee payment: 11 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131207 Year of fee payment: 12 |
|
S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131207 Year of fee payment: 12 |
|
R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
LAPS | Cancellation because of no payment of annual fees |