JP2001191158A - Continuous casting method of steel - Google Patents
Continuous casting method of steelInfo
- Publication number
- JP2001191158A JP2001191158A JP37444699A JP37444699A JP2001191158A JP 2001191158 A JP2001191158 A JP 2001191158A JP 37444699 A JP37444699 A JP 37444699A JP 37444699 A JP37444699 A JP 37444699A JP 2001191158 A JP2001191158 A JP 2001191158A
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- Prior art keywords
- slab
- mold
- casting
- continuous casting
- thickness
- Prior art date
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、垂直曲げ型連続鋳
造機を用い、厚さ８０〜１２０ｍｍの鋳片を、たとえば
３〜５ｍ／分の高速で鋳造する際に、鋳型内の溶鋼の周
期的な湯面レベル変動および鋳片表面の縦割れの発生を
防止できる鋼の連続鋳造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cycle of molten steel in a mold when a slab having a thickness of 80 to 120 mm is cast at a high speed of 3 to 5 m / min. The present invention relates to a continuous casting method of steel that can prevent a typical fluctuation of a molten metal level and the occurrence of a vertical crack on a slab surface.
【０００２】[0002]
【従来の技術】鋼のスラブ連続鋳造では、鋳片品質およ
び生産性の向上と確保の観点から、通常、長方形断面で
厚さ１５０〜３００ｍｍの鋳片が鋳造されている。一
方、連続鋳造機の小型化と関連する設備の建設費および
要員の削減の観点から、製品の厚さにより近い薄鋳片を
得る試みが進められている。とくに熱間圧延鋼帯を巻き
取ったホットコイルの製造では、薄鋳片の連続鋳造方法
と、これに続く鋳造ライン上に配置した簡易な熱間圧延
設備による圧延方法とを組み合わせた製造方法が実用化
されている。この簡易な熱間圧延設備の圧延用素材に
は、長方形断面で厚さ５０ｍｍ程度の薄鋳片が用いられ
ている。2. Description of the Related Art In continuous slab casting of steel, a slab having a rectangular cross section and a thickness of 150 to 300 mm is usually cast from the viewpoint of improving and maintaining the quality of the slab and the productivity. On the other hand, attempts are being made to obtain thin cast pieces that are closer to the thickness of the product from the viewpoints of reducing the size of the continuous casting machine and the construction costs of facilities and reduction of personnel. In particular, in the production of hot coils with hot rolled steel strips, a production method combining a continuous casting method of thin slabs and a rolling method using simple hot rolling equipment arranged on a subsequent casting line is used. Has been put to practical use. A thin slab having a rectangular cross section and a thickness of about 50 mm is used as a rolling material for this simple hot rolling facility.
【０００３】厚さ５０ｍｍ程度のスラブ薄鋳片を連続鋳
造する方法として、出側の厚さを５０ｍｍ程度とし、浸
漬ノズルを挿入する部分に相当する入側の厚さを出側の
厚さより厚くした鋳型を用いる方法がある。しかし、こ
のような鋳型を用いて鋳造すると、鋳型内の凝固殻が変
形を受けるので、鋳片表面に割れが発生しやすい。[0003] As a method of continuously casting a slab thin slab having a thickness of about 50 mm, the thickness of the outlet side is set to about 50 mm, and the thickness of the inlet side corresponding to the part where the immersion nozzle is inserted is made larger than the thickness of the outlet side. There is a method using a template that has been prepared. However, when casting is performed using such a mold, the solidified shell in the mold is deformed, and cracks are likely to occur on the surface of the slab.
【０００４】そこで、鋳片表面の割れの対策として、出
側の厚さが８０〜１２０ｍｍで、入側と出側の厚さがほ
ぼ同じである鋳型を用い、未凝固部が存在する鋳片を圧
下することにより厚さ５０ｍｍ程度の薄鋳片を得る方法
が採られている。この方法は、通常、垂直曲げ型連続鋳
造機を用い、３〜５ｍ／分程度の鋳造速度で実施され
る。Therefore, as a countermeasure against cracks on the surface of the slab, a mold having a thickness of 80 to 120 mm on the outlet side and substantially the same thickness on the inlet side and the outlet side is used. To obtain a thin slab having a thickness of about 50 mm by reducing the pressure. This method is usually performed using a vertical bending type continuous casting machine at a casting speed of about 3 to 5 m / min.
【０００５】垂直曲げ型連続鋳造機を用いるのは、ブレ
ークアウトの防止が目的である。湾曲型連続鋳造機の場
合には、鋳型が湾曲しているため、湾曲している外側の
鋳型内の凝固殻と浸漬ノズルとの間の距離は短くなる。
したがって、浸漬ノズルからの吐出流が、その凝固殻に
当たりやすい。さらに、鋳造速度が速い場合には、鋳型
内の凝固殻の厚さは薄い。これらのことから、鋳型内の
凝固殻が再溶解しやすくなり、ブレークアウトが発生し
やすくなる。そこで、通常、垂直曲げ型連続鋳造機が用
いられるのである。The use of a vertical bending type continuous casting machine is intended to prevent breakout. In the case of a curved continuous caster, the distance between the solidified shell in the outer curved mold and the immersion nozzle is reduced because the mold is curved.
Therefore, the discharge flow from the immersion nozzle easily hits the solidified shell. Further, when the casting speed is high, the thickness of the solidified shell in the mold is small. For these reasons, the solidified shell in the mold is easily redissolved, and breakout is likely to occur. Therefore, a vertical bending type continuous casting machine is usually used.
【０００６】また、３〜５ｍ／分程度の高速で鋳造が行
われるのは、簡易な熱間圧延設備の生産性（２００〜４
００ｔｏｎ／時間）に、連続鋳造方法の生産性を近づけ
るためである。[0006] Casting is performed at a high speed of about 3 to 5 m / min because of the productivity of simple hot rolling equipment (200 to 4 m / min).
(00 ton / hour) to make the productivity of the continuous casting method closer.
【０００７】しかし、垂直曲げ型連続鋳造機を用い、入
側と出側の厚さがほぼ同じである鋳型を用い、厚さ８０
〜１２０ｍｍの鋳片を３〜５ｍ／分程度の高速で鋳造す
ると、鋳型内の溶鋼の湯面レベルが周期性を持って変動
しやすくなる。極端な場合には、湯面レベル変動が次第
に大きくなって、溶鋼が鋳型の上端から溢れ出て、鋳造
の継続が困難になる場合がある。However, a vertical bending type continuous casting machine is used, and a mold having almost the same thickness on the inlet side and the outlet side is used.
When casting a slab of up to 120 mm at a high speed of about 3 to 5 m / min, the molten steel level in the mold tends to fluctuate with periodicity. In extreme cases, the fluctuation of the molten metal level gradually increases, and the molten steel may overflow from the upper end of the mold, making it difficult to continue casting.
【０００８】周期的な湯面レベル変動は、ガイドロール
対とガイドロール対との間で、未凝固部が存在する鋳片
がバルジングし、バルジングした鋳片がガイドロール対
で圧下されることに起因して発生する。鋳片がバルジン
グしても、圧下される厚さが鋳造方向で同じであれば、
周期的な湯面レベル変動は発生しない。しかし、通常、
鋳片の温度は、鋳造方向や鋳片の幅方向で一定ではない
ので、鋳片のバルジング厚さや圧下される厚さは鋳造方
向で異なる。したがって、周期的な湯面レベル変動が発
生する。[0008] Periodic fluctuations in the molten metal level are caused by bulging of a slab having an unsolidified portion between a pair of guide rolls, and the bulging slab is reduced by the pair of guide rolls. It occurs due to. Even if the slab is bulging, if the reduced thickness is the same in the casting direction,
No periodic level changes occur. But usually
Since the temperature of the slab is not constant in the casting direction or in the width direction of the slab, the bulging thickness and the thickness of the slab are different in the casting direction. Therefore, a periodic change in the level of the molten metal occurs.
【０００９】特開平４−６５７４２号公報では、鋳片の
バルジングおよび圧下の繰り返しによって発生する鋳型
内の溶鋼の湯面レベルの周期的な変動を防止する方法と
して、ガイドロール対とガイドロール対との間の間隔を
不均等な間隔とし、ガイドロール対の上下の各ロールを
鋳造方向に非対称にずらせる方法が提案されている。Japanese Patent Application Laid-Open No. 4-65742 discloses a method of preventing a periodic change in the molten steel surface level of a molten steel in a mold caused by repetition of bulging and reduction of a cast slab. A method has been proposed in which the intervals between the guide rolls are made unequal, and the upper and lower rolls of the guide roll pair are asymmetrically shifted in the casting direction.
【００１０】しかし、この方法でも、鋳型から引き抜か
れた直後の鋳片の二次冷却の条件によっては、周期的な
湯面レベル変動が発生する場合がある。[0010] However, even in this method, depending on the condition of the secondary cooling of the slab immediately after being drawn out of the mold, a periodic change in the level of the molten metal may occur.
【００１１】[0011]
【発明が解決しようとする課題】本発明は、垂直曲げ型
連続鋳造機を用い、厚さ８０〜１２０ｍｍの鋳片を、た
とえば３〜５ｍ／分の高速で鋳造するに際し、鋳型内の
溶鋼の周期的な湯面レベル変動の発生を防止し、さら
に、鋳片表面の縦割れの発生も防止できる連続鋳造方法
を提供することを目的とする。SUMMARY OF THE INVENTION The present invention relates to a method for casting a slab having a thickness of 80 to 120 mm at a high speed of, for example, 3 to 5 m / min using a vertical bending type continuous casting machine. It is an object of the present invention to provide a continuous casting method capable of preventing periodic fluctuations in the level of the molten metal and preventing the occurrence of vertical cracks on the slab surface.
【００１２】[0012]
【課題を解決するための手段】本発明の要旨は、垂直曲
げ型連続鋳造機を用い、断面形状が長方形で厚さが８０
〜１２０ｍｍの鋳片を鋳造するに際し、鋳型出側直後か
ら冷却を開始し、鋳型出側から鋳造方向の３ｍまでの間
において、鋳片の二次冷却に用いる全水量の５０〜６０
質量％を用いる条件で鋳片を冷却し、かつ、鋳片の両側
の長辺の単位面積当たりの水量密度を３００〜５００リ
ットル／ｍ2 ・分とする条件で鋳片を冷却する鋼の連続
鋳造方法にある。SUMMARY OF THE INVENTION The gist of the present invention is to use a vertical bending type continuous casting machine having a rectangular cross section and a thickness of 80 mm.
When casting a slab of up to 120 mm, cooling is started immediately after the mold exit side, and 50 to 60 of the total water amount used for secondary cooling of the slab from the mold exit side to 3 m in the casting direction.
A series of steel that cools a slab under the condition of using mass% and cools the slab under the condition that the water density per unit area of the long side on both sides of the slab is 300 to 500 l / m 2 · min. In the casting method.
【００１３】水量密度（リットル／ｍ2 ・分）とは、鋳
片を二次冷却する際の単位時間当たりの冷却水量（リッ
トル／分）を、二次冷却される鋳片の両側の長辺の表面
積（ｍ2 ）で除した値を意味する。The water density (liter / m 2 · minute) means the amount of cooling water per unit time (liter / minute) for secondary cooling of the slab, the long side of both sides of the slab to be secondary cooled. Means the surface area (m 2 ).
【００１４】本発明者らは、前述の課題を、次のように
して解決した。The present inventors have solved the above-mentioned problem as follows.
【００１５】垂直曲げ型連続鋳造機を用い、厚さ８０
〜１２０ｍｍの鋳片を３〜５ｍ／分程度の高速で鋳造す
ると、前述の特開平４−６５７４２号公報で提案されて
いる方法を用いても、鋳型内の溶鋼の湯面レベルが周期
性を持って変動しやすくなる。その理由は、次のとおり
である。Using a vertical bending type continuous casting machine, a thickness of 80
When a slab of up to 120 mm is cast at a high speed of about 3 to 5 m / min, the molten steel level in the mold will have a periodicity even if the method proposed in the above-mentioned JP-A-4-65742 is used. It becomes easy to fluctuate. The reason is as follows.
【００１６】すなわち、通常の厚さ２００〜２５０ｍｍ
程度の鋳片を２ｍ／分程度の速度で鋳造する方法に比
べ、厚さ８０〜１２０ｍｍの鋳片を３〜５ｍ／分の高速
で鋳造する方法では、鋳型出側から、その下方の長さ３
ｍ程度までの領域の凝固殻の厚さは薄い。凝固殻の厚さ
が薄いので、その領域で鋳片はバルジングしやすい。That is, a normal thickness of 200 to 250 mm
In the method of casting a slab having a thickness of 80 to 120 mm at a high speed of 3 to 5 m / min, as compared with a method of casting a slab of about 2 m / min at a speed of about 2 m / min, the length below the mold exit side 3
The thickness of the solidified shell in the region up to about m is thin. Since the thickness of the solidified shell is thin, the slab tends to bulge in that region.
【００１７】さらに、鋳片が垂直部を通過後に曲げ変形
を受ける際に、凝固殻の厚さが薄いため、鋳片の断面が
変形しやすい。この断面が変形した鋳片は、その下流側
でバルジングする。Furthermore, when the slab undergoes bending deformation after passing through the vertical portion, the cross section of the slab is liable to be deformed because the thickness of the solidified shell is small. The slab having this deformed cross section bulges downstream thereof.
【００１８】このように、通常のガイドロール対とガイ
ドロール対の間での鋳片のバルジングと圧下に加えて、
鋳片が垂直部を通過後に、曲げ応力により鋳片の断面が
変形することにより、鋳型内の溶鋼の周期的な湯面レベ
ル変動が大きくなる。As described above, in addition to the usual bulging and reduction of the slab between the guide roll pair,
After the slab passes through the vertical portion, the cross section of the slab is deformed due to bending stress, so that the periodic fluctuation of the molten metal level in the molten steel in the mold becomes large.
【００１９】鋳片が垂直部を通過した後に、曲げ応力に
より鋳片の断面が変形し、その後バルジングすることに
より発生する鋳型内の溶鋼の周期的な湯面レベル変動
は、前述のガイドロール対とガイドロール対との間の間
隔を不均等な間隔としたり、また、ガイドロール対の上
下の各ロールを鋳造方向に非対称にずらせる方法では、
防止するのが困難である。After the slab passes through the vertical portion, the cross section of the slab is deformed by bending stress, and then the bulging causes the periodic fluctuation of the molten steel level in the mold caused by the aforementioned guide roll pair. In the method in which the distance between the guide roll pair and the guide roll pair is not uniform, or the rolls above and below the guide roll pair are asymmetrically shifted in the casting direction,
Difficult to prevent.
【００２０】このような湯面レベル変動を防止するため
には、鋳型出側からその下方の長さ３ｍ程度までの領域
の鋳片を強冷却し、鋳片がバルジングしにくくするこ
と、および鋳片が垂直部を通過後に、曲げ応力により鋳
片の断面が変形しにくくすることが、鋳型内の溶鋼の周
期的な湯面レベル変動の発生防止に効果的である。In order to prevent such a change in the level of the molten metal, the slab in the region from the mold discharge side to a length of about 3 m below the slab is strongly cooled to make the slab less bulging. Making the cross section of the cast piece difficult to deform due to bending stress after the piece passes through the vertical portion is effective for preventing the occurrence of the periodic fluctuation of the molten metal level in the molten steel in the mold.
【００２１】一方、鋳型出側から、その下方の長さ３
ｍ程度までの領域の鋳片の冷却が、過度に強冷却となる
場合には、鋳片表面に縦割れが発生しやすくなる。過度
の強冷却によって、鋳片表面に大きな熱応力が作用し、
さらに、鋳片が垂直部を通過する際に、鋳片表面に曲げ
応力が作用する。このように鋳片表面に作用する大きな
応力によって、鋳片表面に縦割れが発生しやすくなるの
である。On the other hand, the length 3
If the cooling of the slab in the region up to about m is excessively strong, longitudinal cracks are likely to occur on the slab surface. Due to excessively strong cooling, large thermal stress acts on the slab surface,
Further, when the slab passes through the vertical portion, bending stress acts on the slab surface. Such large stress acting on the slab surface tends to cause vertical cracks on the slab surface.
【００２２】また、亜包晶鋼などの中炭素鋼を鋳造する
と、その鋼に特有の凝固特性から、鋳型内の凝固殻の厚
さが鋳片の幅方向で不均一になりやすいので、もともと
鋳片表面に縦割れが発生しやすい。さらに、３〜５ｍ／
分の高速で鋳造する条件、および鋳型出側から、その下
方の長さ３ｍ程度までの領域での鋳片の過度の強冷却の
条件が加わると、鋳片表面に縦割れが著しく発生しやす
い。When a medium-carbon steel such as hypoperitectic steel is cast, the thickness of the solidified shell in the mold tends to be uneven in the width direction of the slab due to the solidification characteristic of the steel. Longitudinal cracks easily occur on the slab surface. Furthermore, 3-5m /
When the conditions for casting at a high speed for one minute and the conditions for excessively strong cooling of the slab in the region up to about 3 m below the mold exit side are added, longitudinal cracks are liable to occur on the slab surface significantly. .
【００２３】そこで、鋳型出側から、その下方の長さ３
ｍ程度までの領域の鋳片を強冷却する際に、鋳片表面に
縦割れが発生しない程度の適度な強冷却が必要となる。Therefore, the length of 3 mm below the mold exit side
When strongly cooling a slab in a region up to about m, a moderately strong cooling that does not cause longitudinal cracks on the slab surface is required.
【００２４】本発明の方法では、鋳型出側直後から冷
却を開始し、鋳型出側から鋳造方向の３ｍまでの間にお
いて、鋳片の二次冷却に用いる全水量の５０〜６０質量
％を用いる条件で鋳片を冷却し、かつ、同じく鋳型出側
から鋳造方向の３ｍまでの間において、鋳片の両側の長
辺の単位面積当たりの水量密度を３００〜５００リット
ル／ｍ2 ・分とする条件で鋳片を冷却する。これによ
り、鋳型出側の垂直部を通過する鋳片およびその近傍の
鋳片が、適度な強冷却の条件で二次冷却される。In the method of the present invention, cooling is started immediately after the mold exit side, and 50 to 60% by mass of the total water used for secondary cooling of the slab is used from the mold exit side to 3 m in the casting direction. The slab is cooled under the conditions, and the water density per unit area of the long side on both sides of the slab is set to 300 to 500 liter / m 2 · min. Cool the slab under the conditions. As a result, the slab that passes through the vertical part on the mold exit side and the slab near the slab are secondarily cooled under moderately strong cooling conditions.
【００２５】[0025]
【発明の実施の形態】図１は、本発明の方法を実施する
場合の連続鋳造機および鋳片の断面を示す模式図であ
る。溶鋼８は浸漬ノズル７を経て鋳型１内に鋳造され
る。鋳型からピンチロール５により引き抜かれた鋳片２
は、二次冷却帯６において、ガイドロール対３で支持さ
れ、また、ミストノズル４により水を噴霧されて冷却さ
れる。FIG. 1 is a schematic view showing a cross section of a continuous casting machine and a slab when the method of the present invention is carried out. The molten steel 8 is cast into the mold 1 through the immersion nozzle 7. A slab 2 drawn from a mold by a pinch roll 5
Is supported by the guide roll pair 3 in the secondary cooling zone 6, and is cooled by spraying water with the mist nozzle 4.
【００２６】本発明が対象とする鋳片は、断面形状が長
方形で厚さが８０〜１２０ｍｍの鋳片である。The slab to which the present invention is directed is a slab having a rectangular cross section and a thickness of 80 to 120 mm.
【００２７】このようなサイズの鋳片であれば、前述の
とおり、入側と出側の厚さがほぼ同じである鋳型を用い
ることができるので、鋳型内の凝固殻が変形を受けるこ
とはなく、凝固殻が鋳型内で変形することによる鋳片表
面の割れの発生を防止できる。また、簡易な熱間圧延設
備の圧延用素材として用いられる厚さ５０ｍｍ程度の薄
鋳片は、厚さ８０〜１２０ｍｍの鋳片を未凝固圧下する
ことにより得ることができる。With a slab of such a size, as described above, a mold having substantially the same thickness on the inlet side and the outlet side can be used, so that the solidified shell in the mold is not deformed. In addition, the occurrence of cracks on the slab surface due to the deformation of the solidified shell in the mold can be prevented. A thin slab having a thickness of about 50 mm used as a rolling material for a simple hot rolling facility can be obtained by unsolidifying a slab having a thickness of 80 to 120 mm.
【００２８】厚さが８０ｍｍ未満では、入側と出側の厚
さがほぼ同じである鋳型を用いる場合に、浸漬ノズルの
肉厚を厚くできない。したがって、浸漬ノズルが溶損し
やすく、長時間の鋳造が困難であり、実用的でない。厚
さが１２０ｍｍを超えると、大型の連続鋳造機が必要と
なる。If the thickness is less than 80 mm, the thickness of the immersion nozzle cannot be increased when using a mold having substantially the same thickness on the inlet side and the outlet side. Therefore, the immersion nozzle is easily melted, and it is difficult to cast for a long time, which is not practical. When the thickness exceeds 120 mm, a large continuous casting machine is required.
【００２９】厚さが８０〜１２０ｍｍである鋳片の場合
に、垂直曲げ型連続鋳造機の垂直部の長さは、通常、１
ｍ程度である。したがって、鋳型出側から鋳造方向の３
ｍまでの間とは、鋳型出側の垂直部およびその下流側の
湾曲部までの領域を含むことを意味する。In the case of a slab having a thickness of 80 to 120 mm, the length of the vertical portion of the vertical bending type continuous casting machine is usually 1
m. Therefore, the casting direction 3
The expression up to m means that the region includes the vertical portion on the mold exit side and the curved portion on the downstream side.
【００３０】鋳片の二次冷却に用いる全水量は、通常、
鋳片サイズ、鋳造速度などによって変更される。しか
し、本発明が対象とする厚さが８０〜１２０ｍｍである
鋳片を鋳造する連続鋳造方法では、通常、同じ鋳造ライ
ン上に簡易な熱間圧延設備が配置される。鋳片は、熱間
圧延設備で圧延する前に加熱されることが多いが、鋳片
を加熱するエネルギーを少なくする観点から、鋳造され
た鋳片の温度は高い方が好ましい。The total amount of water used for secondary cooling of the slab is usually
It changes depending on the slab size, casting speed, and the like. However, in the continuous casting method according to the present invention for casting a slab having a thickness of 80 to 120 mm, a simple hot rolling facility is usually arranged on the same casting line. The slab is often heated before being rolled by the hot rolling equipment, but from the viewpoint of reducing the energy for heating the slab, the temperature of the cast slab is preferably higher.
【００３１】そこで、連続鋳造の操業に支障がない程度
に、鋳片の表面温度を高くするように、鋳片の二次冷却
に用いる全水量は少なく設定される。その全水量とは、
おおよそ３６００〜７２００リットル／分程度である。Therefore, the total amount of water used for the secondary cooling of the slab is set to be small so as to increase the surface temperature of the slab so as not to hinder the operation of continuous casting. The total amount of water
It is about 3600-7200 liters / minute.
【００３２】連続鋳造操業の支障とは、二次冷却水量が
少ないことにより、鋳片の温度が高く、凝固殻の厚さが
薄くなるので、たとえば、ブレークアウトが発生した
り、連続鋳造機の出側で鋳片がバルジングすることを意
味する。熱間圧延設備に配置された加熱炉に装入する鋳
片の表面温度は、９００〜１１００℃程度が望ましい。The problem with the continuous casting operation is that the amount of secondary cooling water is small, the temperature of the slab is high, and the thickness of the solidified shell is small. It means that the slab bulges on the delivery side. The surface temperature of the slab to be charged into the heating furnace arranged in the hot rolling equipment is desirably about 900 to 1100 ° C.
【００３３】鋳型出側から鋳造方向の３ｍまでの間にお
いて、鋳片を二次冷却する水量が鋳片の二次冷却に用い
る全水量の５０質量％未満の場合、または、鋳片の両側
の長辺の単位面積当たりの水量密度が３００リットル／
ｍ2 ・分未満の場合では、鋳片の二次冷却が弱いため
に、鋳片がバルジングしやすい。したがって、周期的な
湯面レベル変動が発生しやすい。When the amount of water for secondary cooling of the slab is less than 50% by mass of the total amount of water used for the secondary cooling of the slab from the mold exit side to 3 m in the casting direction, or on both sides of the slab. The water density per unit area of the long side is 300 liters /
In the case of less than m 2 · min, the slab tends to bulge because the secondary cooling of the slab is weak. Therefore, a periodic change in the molten metal level is likely to occur.
【００３４】鋳型出側から鋳造方向の３ｍまでの間にお
いて、鋳片を二次冷却する水量が鋳片の二次冷却に用い
る全水量の６０質量％を超える場合、または、鋳片長辺
側の単位面積当たりの水量密度が５００リットル／ｍ2
・分を超える場合には、鋳片の二次冷却が強すぎる。鋳
片表面が、過度に強冷却されるので、鋳片表面に大きな
熱応力などが作用する。そのため、鋳片表面に縦割れが
発生しやすい。When the amount of water for secondary cooling of the slab exceeds 60% by mass of the total amount of water used for secondary cooling of the slab from the mold exit side to 3 m in the casting direction, or on the long side of the slab. Water density per unit area is 500 l / m 2
-If the time exceeds minutes, the secondary cooling of the slab is too strong. Since the slab surface is excessively strongly cooled, a large thermal stress or the like acts on the slab surface. Therefore, vertical cracks are likely to occur on the surface of the slab.
【００３５】鋳片の二次冷却には、通常用いられている
ミストノズルを用いるのがよいが、これは、鋳片の表面
温度が均一になりやすいからである。For the secondary cooling of the slab, it is preferable to use a mist nozzle which is generally used, because the surface temperature of the slab tends to be uniform.
【００３６】[0036]
【実施例】垂直部の長さ１．５ｍ、湾曲半径３．５ｍ
で、１ストランドの垂直曲げ型連続鋳造機を用い、Ｃ含
有率０．１４〜０．２０質量％の中炭素鋼を、厚さ９０
ｍｍ、幅１２００ｍｍの鋳片に鋳造した。目標の鋳造速
度は３ｍ／分とした。二次冷却帯の長さは、鋳型出側か
ら鋳造方向に７．０ｍまでの間である。DESCRIPTION OF THE PREFERRED EMBODIMENTS The length of the vertical portion is 1.5 m and the radius of curvature is 3.5 m
Then, using a one-strand vertical bending type continuous casting machine, a medium carbon steel having a C content of 0.14 to 0.20 mass% and a thickness of 90% was used.
mm and a slab having a width of 1200 mm. The target casting speed was 3 m / min. The length of the secondary cooling zone is between 7.0 m from the mold exit side in the casting direction.
【００３７】二次冷却水量の全水量は、鋳造速度が３ｍ
／分の際に、本発明例の試験では、４７００リットル／
分、比較例の試験では、３３００〜６１００リットル／
分とした。連続鋳造機の出側の鋳片の幅中央部の目標の
表面温度を１０５０℃程度とした。各試験では、３ヒー
トを連続して鋳造した。１ヒートは約１００ｔｏｎであ
る。The total amount of the secondary cooling water is set at a casting speed of 3 m.
/ Min, in the test of the present invention example, 4700 liters /
Minutes, in the test of the comparative example, 3300 to 6100 liters /
Minutes. The target surface temperature at the center of the width of the slab on the exit side of the continuous casting machine was set to about 1050 ° C. In each test, three heats were cast continuously. One heat is about 100 tons.
【００３８】鋳造中に、鋳型内の溶鋼の周期的な湯面レ
ベル変動の発生状況を観察した。また、連続鋳造機の出
側で鋳片の幅中央部の表面温度を放射温度計を用いて測
定した。各ヒートから長さ１０ｍの代表的な鋳片をサン
プル採取し、鋳片表面の縦割れの発生状況を目視で観察
した。表１に試験条件および試験結果を示す。During casting, the occurrence of periodic fluctuations in the molten metal level in the molten steel in the mold was observed. The surface temperature at the center of the width of the slab at the outlet side of the continuous casting machine was measured using a radiation thermometer. A sample of a typical cast slab having a length of 10 m was sampled from each heat, and the occurrence of vertical cracks on the cast slab surface was visually observed. Table 1 shows test conditions and test results.
【００３９】[0039]
【表１】 [Table 1]
【００４０】本発明例の試験Ｎｏ．１では、本発明で規
定する条件の範囲内で、鋳型出側直後から冷却を開始
し、鋳型出側から鋳造方向の３ｍまでの間において、鋳
片の二次冷却に用いる全水量の５５質量％を用いる条件
で鋳片を冷却し、かつ、鋳片の両側の長辺の単位面積当
たりの水量密度を３６０リットル／ｍ2 ・分とする条件
で鋳片を二次冷却した。鋳造中に周期的な湯面レベル変
動は発生しなかった。また、鋳片表面の縦割れも発生せ
ず、良好な表面品質の鋳片が得られた。連続鋳造機の出
側での鋳片の温度は約１０５０℃であった。Test No. of the present invention example In 1, in the range specified by the present invention, cooling is started immediately after the mold exit side, and from the mold exit side to 3 m in the casting direction, 55 mass of the total water amount used for secondary cooling of the slabs. %, And the slab was secondarily cooled under the condition that the water density per unit area of the long sides on both sides of the slab was 360 l / m 2 · min. No periodic level changes occurred during casting. Also, vertical cracks did not occur on the slab surface, and slabs of good surface quality were obtained. The temperature of the slab at the outlet of the continuous casting machine was about 1050 ° C.
【００４１】比較例の試験Ｎｏ．２では、本発明で規定
する条件の範囲内で、鋳型出側直後から冷却を開始し、
鋳型出側から鋳造方向の３ｍまでの間において、鋳片の
二次冷却に用いる全水量の５５質量％を用いて鋳片を冷
却した。鋳片の両側の長辺の単位面積当たりの水量密度
は、本発明で規定する条件の範囲を外して、２５０リッ
トル／ｍ2 ・分とした。鋳片表面の縦割れは発生しなか
った。連続鋳造機の出側での鋳片の温度は約１１００℃
であった。しかし、鋳造途中で、周期的な湯面レベル変
動が発生したので、鋳造速度を２ｍ／分まで低下させて
鋳造した。Test No. of Comparative Example In 2, within the conditions specified in the present invention, cooling is started immediately after the mold exit side,
Between the mold exit side and 3 m in the casting direction, the slab was cooled using 55% by mass of the total water used for secondary cooling of the slab. The water density per unit area of the long sides of both sides of the slab was 250 liter / m 2 · min, excluding the range of the conditions specified in the present invention. No vertical cracks occurred on the slab surface. The temperature of the slab at the output side of the continuous casting machine is about 1100 ° C
Met. However, the casting level was reduced to 2 m / min, and the casting was performed because periodic fluctuations in the molten metal level occurred during the casting.
【００４２】比較例の試験Ｎｏ．３では、鋳型出側直後
から冷却を開始し、鋳型出側から鋳造方向の３ｍまでの
間において、本発明で規定する条件の範囲を外して、鋳
片の二次冷却に用いる全水量に対して４０質量％の水量
で鋳片を冷却した。また、鋳片の両側の長辺の単位面積
当たりの水量密度は、本発明で規定する条件の範囲を外
して、２２０リットル／ｍ2 ・分とした。鋳片表面の縦
割れは発生しなかった。また、連続鋳造機の出側での鋳
片の温度は約１１３０℃であった。しかし、鋳造途中
で、周期的な湯面レベル変動が発生したので、鋳造速度
を２ｍ／分まで低下させて鋳造した。Test No. of Comparative Example In 3, the cooling was started immediately after the mold exit side, and from the mold exit side to 3 m in the casting direction, the range of the conditions specified in the present invention was excluded, and the total water amount used for the secondary cooling of the slab was The slab was cooled with a water content of 40% by mass. The water density per unit area of the long sides of both sides of the slab was 220 liter / m 2 · min, excluding the range of the conditions specified in the present invention. No vertical cracks occurred on the slab surface. The temperature of the slab at the outlet of the continuous casting machine was about 1130 ° C. However, the casting level was reduced to 2 m / min, and the casting was performed because periodic fluctuations in the molten metal level occurred during the casting.
【００４３】比較例の試験Ｎｏ．４では、鋳型出側直後
から冷却を開始し、鋳型出側から鋳造方向の３ｍまでの
間において、本発明で規定する条件の範囲を外して、鋳
片の二次冷却に用いる全水量に対して６５質量％の水量
で鋳片を冷却した。また、鋳片の両側の長辺の単位面積
当たりの水量密度は、本発明で規定する条件の範囲を外
して、５５０リットル／ｍ2 ・分と多くした。鋳造中に
周期的な湯面レベル変動は発生しなかったが、鋳片表面
に著しい縦割れが発生した。また、連続鋳造機の出側で
の鋳片の温度は約８９０℃で低かった。Test No. of Comparative Example In 4, the cooling was started immediately after the mold exit side, and from the mold exit side to 3 m in the casting direction, the range of the conditions defined in the present invention was excluded, and the total amount of water used for the secondary cooling of the slab was The slab was cooled with a water amount of 65% by mass. The water density per unit area of the long sides of both sides of the cast slab was increased to 550 liter / m 2 · min, excluding the range of the conditions specified in the present invention. No periodic level change occurred during casting, but significant vertical cracks occurred on the slab surface. The temperature of the slab at the outlet side of the continuous casting machine was as low as about 890 ° C.
【００４４】[0044]
【発明の効果】本発明の連続鋳造方法の適用により、と
くに亜包晶鋼などの中炭素鋼を鋳造する際、鋳型内の溶
鋼の周期的な湯面レベル変動の発生を効果的に防止で
き、さらに、鋳片表面の縦割れの発生を効果的に防止で
きる。According to the continuous casting method of the present invention, it is possible to effectively prevent the periodic change of the molten metal level in the molten steel in the mold, especially when casting medium carbon steel such as hypoperitectic steel. Further, the occurrence of vertical cracks on the surface of the slab can be effectively prevented.
【図１】本発明の方法を実施する場合の連続鋳造機およ
び鋳片の断面を示す模式図である。FIG. 1 is a schematic view showing a cross section of a continuous casting machine and a slab when the method of the present invention is carried out.
１：鋳型 ２：鋳片 ３：ガ
イドロール対 ４：ミストノズル ５：ピンチロール ６：二
次冷却帯 ７：浸漬ノズル ８：溶鋼1: mold 2: slab 3: guide roll pair 4: mist nozzle 5: pinch roll 6: secondary cooling zone 7: immersion nozzle 8: molten steel
フロントページの続き (72)発明者 原 昌司 大阪府大阪市中央区北浜４丁目５番33号住 友金属工業株式会社内 Ｆターム(参考） 4E004 KA14 MC02 NA01 NB01 NC04Continued on the front page (72) Inventor Shoji Hara 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. F-term (reference) 4E004 KA14 MC02 NA01 NB01 NC04
Claims (1)
長方形で厚さが８０〜１２０ｍｍの鋳片を鋳造するに際
し、鋳型出側直後から冷却を開始し、鋳型出側から鋳造
方向の３ｍまでの間において、鋳片の二次冷却に用いる
全水量の５０〜６０質量％を用いる条件で鋳片を冷却
し、かつ、鋳片の両側の長辺の単位面積当たりの水量密
度を３００〜５００リットル／ｍ2 ・分とする条件で鋳
片を冷却することを特徴とする鋼の連続鋳造方法。1. When casting a slab having a rectangular cross section and a thickness of 80 to 120 mm using a vertical bending type continuous casting machine, cooling is started immediately after the mold exit side, and the casting direction is changed from the mold exit side to the casting direction. Up to 3 m, the slab is cooled under the condition of using 50 to 60% by mass of the total water amount used for the secondary cooling of the slab, and the water density per unit area of the long side on both sides of the slab is 300 A continuous casting method for steel, comprising cooling a slab under a condition of about 500 liter / m 2 · minute.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP37444699A JP2001191158A (en) | 1999-12-28 | 1999-12-28 | Continuous casting method of steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP37444699A JP2001191158A (en) | 1999-12-28 | 1999-12-28 | Continuous casting method of steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001191158A true JP2001191158A (en) | 2001-07-17 |
Family
ID=18503869
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP37444699A Pending JP2001191158A (en) | 1999-12-28 | 1999-12-28 | Continuous casting method of steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001191158A (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007330998A (en) * | 2006-06-15 | 2007-12-27 | Sumitomo Metal Ind Ltd | Continuous casting method |
| JP2010253481A (en) * | 2009-04-21 | 2010-11-11 | Jfe Steel Corp | Surface crack preventing method for continuously cast slab |
| JP2011131239A (en) * | 2009-12-24 | 2011-07-07 | Nippon Steel Corp | Continuous casting method for steel |
| JP2012187611A (en) * | 2011-03-11 | 2012-10-04 | Sumitomo Metal Ind Ltd | Continuous casting method of steel |
| JP2015016493A (en) * | 2013-07-11 | 2015-01-29 | 株式会社神戸製鋼所 | Continuous casting method |
| JP2016022498A (en) * | 2014-07-18 | 2016-02-08 | 新日鐵住金株式会社 | Production method of low carbon aluminum-killed steel |
| CN106270439A (en) * | 2016-09-30 | 2017-01-04 | 中冶赛迪工程技术股份有限公司 | A kind of Spraying Water of Nozzles in Secondary Cooling method improving continuous casting billet gross segregation |
| CN113680983A (en) * | 2021-09-13 | 2021-11-23 | 鞍钢股份有限公司 | Control method for reducing liquid level fluctuation in production of sub-peritectic steel |
-
1999
- 1999-12-28 JP JP37444699A patent/JP2001191158A/en active Pending
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007330998A (en) * | 2006-06-15 | 2007-12-27 | Sumitomo Metal Ind Ltd | Continuous casting method |
| JP4720640B2 (en) * | 2006-06-15 | 2011-07-13 | 住友金属工業株式会社 | Continuous casting method |
| JP2010253481A (en) * | 2009-04-21 | 2010-11-11 | Jfe Steel Corp | Surface crack preventing method for continuously cast slab |
| JP2011131239A (en) * | 2009-12-24 | 2011-07-07 | Nippon Steel Corp | Continuous casting method for steel |
| JP2012187611A (en) * | 2011-03-11 | 2012-10-04 | Sumitomo Metal Ind Ltd | Continuous casting method of steel |
| JP2015016493A (en) * | 2013-07-11 | 2015-01-29 | 株式会社神戸製鋼所 | Continuous casting method |
| JP2016022498A (en) * | 2014-07-18 | 2016-02-08 | 新日鐵住金株式会社 | Production method of low carbon aluminum-killed steel |
| CN106270439A (en) * | 2016-09-30 | 2017-01-04 | 中冶赛迪工程技术股份有限公司 | A kind of Spraying Water of Nozzles in Secondary Cooling method improving continuous casting billet gross segregation |
| CN106270439B (en) * | 2016-09-30 | 2018-06-12 | 中冶赛迪工程技术股份有限公司 | A kind of Spraying Water of Nozzles in Secondary Cooling method for improving continuous casting billet gross segregation |
| CN113680983A (en) * | 2021-09-13 | 2021-11-23 | 鞍钢股份有限公司 | Control method for reducing liquid level fluctuation in production of sub-peritectic steel |
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