JP2000126850A - Continuous casting method - Google Patents

Continuous casting method

Info

Publication number
JP2000126850A
JP2000126850A JP10304294A JP30429498A JP2000126850A JP 2000126850 A JP2000126850 A JP 2000126850A JP 10304294 A JP10304294 A JP 10304294A JP 30429498 A JP30429498 A JP 30429498A JP 2000126850 A JP2000126850 A JP 2000126850A
Authority
JP
Japan
Prior art keywords
molten steel
mold
flow
immersion nozzle
inert gas
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
Application number
JP10304294A
Other languages
Japanese (ja)
Other versions
JP3385982B2 (en
Inventor
Tadashi Hirashiro
正 平城
Hideo Mizukami
英夫 水上
Makoto Fukagawa
信 深川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Sumitomo Metal Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Sumitomo Metal Industries Ltd filed Critical Sumitomo Metal Industries Ltd
Priority to JP30429498A priority Critical patent/JP3385982B2/en
Publication of JP2000126850A publication Critical patent/JP2000126850A/en
Application granted granted Critical
Publication of JP3385982B2 publication Critical patent/JP3385982B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Landscapes

  • Continuous Casting (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a continuous casting method, with which an immersion nozzle is difficult to clog during casting and pin hole state defect and powder state defect are not developed on the surface of a cast slab and the cast slab excellent in cleanliness is obtd. SOLUTION: Molten steel flowing speed near a meniscus of the molten steel in a mold is controlled so that the difference between the max. value of the flowing 9d toward short sides of the mold from the neighborhood of the immersion nozzle and the max. value of the flowing 9c toward the immersion nozzle from the short sides of the mold developed with inert gas blown at the interval from a molten steel supplying hole of a tundish into the mold to a spouting hole in the immersion nozzle becomes <=20 cm/sec.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、鋳造中に溶鋼中の
酸化物による浸漬ノズルの詰まりが発生することなく、
鋳片表面にピンホール性欠陥やパウダ性欠陥がなくて表
面性状に優れ、かつ清浄度にも優れた鋳片を得ることが
可能な鋼の連続鋳造方法に関する。
BACKGROUND OF THE INVENTION The present invention relates to a method and an apparatus for manufacturing a cast iron, wherein clogging of an immersion nozzle by an oxide in molten steel does not occur during casting.
The present invention relates to a continuous casting method of steel capable of obtaining a slab excellent in surface properties and having excellent cleanliness without pinhole defects or powder defects on the slab surface.

【0002】[0002]

【従来の技術】鋼の連続鋳造では、生産性の向上のた
め、連続して長時間の鋳造を可能にすることが重要な課
題である。しかし、溶鋼中には鋳片に残存し非金属介在
物となる酸化物が存在し、長時間の鋳造にともない、こ
の酸化物が浸漬ノズルの内壁に付着し、最終的には浸漬
ノズルが閉塞する場合がある。
2. Description of the Related Art In continuous casting of steel, it is important to continuously cast steel for a long time in order to improve productivity. However, in the molten steel, oxides that remain in the slab and become non-metallic inclusions exist, and with the long-time casting, these oxides adhere to the inner wall of the immersion nozzle, and eventually the immersion nozzle is closed. May be.

【0003】この浸漬ノズルの閉塞を防止するために、
タンディッシュの鋳型への給湯孔から浸漬ノズルの吐出
孔の間で、溶鋼中に不活性ガスを吹き込む方法が提案さ
れている。
In order to prevent the clogging of the immersion nozzle,
A method has been proposed in which an inert gas is blown into molten steel from a hot water supply hole to a tundish mold to a discharge hole of a dipping nozzle.

【0004】特開平2−37948号公報には、鋳造速
度に応じて浸漬ノズル内の溶鋼中への不活性ガスの吹き
込み量を3.0〜5.0リットル/溶鋼tとすることに
より、浸漬ノズルの閉塞を防止する方法が提案されてい
る。しかし、この方法では、吹き込む量が多すぎて、鋳
片の表面に不活性ガスの気泡に起因するピンホール性の
欠陥が発生する場合がある。
[0004] Japanese Patent Application Laid-Open No. 2-37948 discloses that the amount of inert gas blown into molten steel in an immersion nozzle is adjusted to 3.0 to 5.0 liters / t of molten steel according to the casting speed. Methods for preventing nozzle blockage have been proposed. However, in this method, the amount of air blown is too large, and a pinhole defect may be generated on the surface of the slab due to bubbles of the inert gas.

【0005】ピンホール性欠陥は、その後の熱間圧延や
冷間圧延の際に製品の鋼板に残存し、鋼板の表面が膨れ
る、いわゆるふくれ疵と称される製品の欠陥となる場合
がある。また、鋳片の表面をスカーフィング(酸素ガス
による表面の溶削)により手入れする場合に、手入れさ
れた鋳片の表面に開口した気泡の穴が残存し、熱間圧延
前に鋳片を加熱炉で加熱する際に、酸化して生成したス
ケールがこの気泡の穴に残存し、圧延した製品の鋼板の
表面にへげ疵と称される線状欠陥が発生する場合があ
る。
[0005] The pinhole defect may remain in the steel sheet of the product during the subsequent hot rolling or cold rolling and cause a product defect called a so-called blister, which causes the surface of the steel sheet to swell. In addition, when the surface of the cast slab is groomed by scarfing (cutting of the surface with oxygen gas), holes of air bubbles that remain open on the surface of the groomed slab remain, and the slab is heated before hot rolling. When heated in a furnace, scales generated by oxidation remain in the pores of the bubbles, and linear defects called dents may occur on the surface of the rolled product steel sheet.

【0006】とくに、自動車用の鋼板に用いられる炭素
含有量が50ppm以下の極低炭素鋼の鋳片には、上述
したピンホール性の欠陥が発生しやすい。ピンホール性
欠陥を防止するため、浸漬ノズルに吹き込む不活性ガス
の量を減らすと、鋳造中に浸漬ノズルの詰まりが発生し
やすくなる。また、鋳型内の凝固殻に未溶融のモールド
パウダが捕捉されて、鋳片の表面にパウダ性欠陥も発生
しやすい。
[0006] In particular, the above-mentioned defect of the pinhole property is liable to occur in a cast piece of ultra-low carbon steel having a carbon content of 50 ppm or less used for a steel sheet for automobiles. If the amount of inert gas blown into the immersion nozzle is reduced in order to prevent pinhole defects, clogging of the immersion nozzle during casting tends to occur. In addition, unmelted mold powder is captured by the solidified shell in the mold, and powder defects are likely to occur on the surface of the slab.

【0007】極低炭素鋼の鋳片の表面のピンホール性欠
陥や浸漬ノズルの詰まりの対策として、特開平9−19
2803号公報では、鋳造速度に応じて、浸漬ノズルに
約4リットル/溶鋼tの量の不活性ガスを吹き込み、か
つ両側の浸漬ノズルと鋳型の短辺との間に、移動磁場印
加装置を配置し、溶鋼の表面に浮上してくる不活性ガス
の量が、両側の浸漬ノズルと鋳型の短辺との間で、同じ
量になるように移動磁場印加装置を制御することが提案
されている。
As measures against pinhole defects on the surface of a slab of ultra-low carbon steel and clogging of an immersion nozzle, Japanese Patent Application Laid-Open No. 9-19 / 1991 has been proposed.
In the publication 2803, according to the casting speed, an inert gas is blown into an immersion nozzle in an amount of about 4 liters / t of molten steel, and a moving magnetic field applying device is arranged between the immersion nozzle on both sides and the short side of the mold. It has been proposed to control the moving magnetic field applying device so that the amount of the inert gas floating on the surface of the molten steel is the same between the immersion nozzles on both sides and the short side of the mold. .

【0008】この方法は、鋳型内の溶鋼の表面に浮上し
てくる不活性ガスを回収し、測定された不活性ガスの量
にもとづき、浸漬ノズルを挟んで鋳型内の両側の移動磁
場の強さを独立に制御する方法である。しかし、回収し
た不活性ガスの量を、瞬時に、正確に測定することは困
難であり、また、鋳型内の溶鋼の流動は短時間で変化す
るので、回収したガス量の測定値にもとづいて溶鋼の流
動を制御することは困難な場合が多い。さらに、浸漬ノ
ズル内の溶鋼に吹き込む不活性ガス量が多すぎて、ピン
ホール性欠陥が発生しやすいという問題がある。
In this method, an inert gas floating on the surface of molten steel in a mold is collected, and based on the measured amount of the inert gas, the strength of the moving magnetic field on both sides in the mold with the immersion nozzle interposed therebetween. This is a method of independently controlling the height. However, it is difficult to measure the amount of the recovered inert gas instantaneously and accurately, and the flow of molten steel in the mold changes in a short time. It is often difficult to control the flow of molten steel. Further, there is a problem in that the amount of inert gas blown into the molten steel in the immersion nozzle is too large, so that pinhole defects are likely to occur.

【0009】[0009]

【発明が解決しようとする課題】本発明は、鋳造中に浸
漬ノズルの詰まりが発生することなく、かつ鋳片表面に
ピンホール性欠陥やパウダ性欠陥がなくて表面性状に優
れ、かつ清浄度にも優れた鋳片を得ることが可能な鋼の
連続鋳造方法を提供することを目的とする。
DISCLOSURE OF THE INVENTION The present invention provides an improved surface property without clogging of an immersion nozzle during casting, no pinhole or powdery defects on the slab surface, and cleanliness. It is an object of the present invention to provide a continuous casting method of steel capable of obtaining an excellent slab.

【0010】[0010]

【課題を解決するための手段】本発明の要旨は、下記
(1)および(2)に示す連続鋳造方法にある。
The gist of the present invention resides in a continuous casting method shown in the following (1) and (2).

【0011】(1)吐出流が鋳型の短辺側に向かう吐出
孔を備える浸漬ノズルを用いるとともに、タンディッシ
ュの鋳型への給湯孔から上記浸漬ノズルの吐出孔の間
で、溶鋼中に不活性ガスを吹き込みつつ連続鋳造する方
法であって、鋳型内の溶鋼のメニスカス近傍での溶鋼流
速を、吹き込まれた上記不活性ガスにより発生する浸漬
ノズル近傍から鋳型の短辺に向かう流れの最大値と鋳型
の短辺側から浸漬ノズルに向かう流れの最大値との差が
20cm/秒以下となるように制御する鋼の連続鋳造方
法。
(1) An immersion nozzle having a discharge hole whose discharge flow is directed to the short side of the mold is used, and inert gas is introduced into the molten steel between the hot water supply hole to the mold of the tundish and the discharge hole of the immersion nozzle. A method of continuous casting while blowing gas, the molten steel flow velocity near the meniscus of the molten steel in the mold, the maximum value of the flow from the vicinity of the immersion nozzle generated by the injected inert gas toward the short side of the mold A continuous casting method for steel in which the difference from the maximum value of the flow from the short side of the mold to the immersion nozzle is controlled to be 20 cm / sec or less.

【0012】(2)鋳型の長辺の外側に鋳型を挟んで設
けた電磁力による溶鋼流動制動装置により、鋳型内の溶
鋼の流動を制動しつつ、不活性ガスの吹き込み量0.2
〜3.0(Nリットル/溶鋼t)の範囲内で鋳造する上
記(1)に記載の鋼の連続鋳造方法。
(2) The flow rate of the inert gas is controlled to 0.2 while the flow of molten steel in the mold is braked by a molten steel flow braking device by electromagnetic force provided outside the long side of the mold with the mold interposed therebetween.
The continuous casting method for steel according to the above (1), wherein the steel is cast within a range of from 3.0 to 3.0 (N liter / molten steel t).

【0013】極低炭素鋼の精錬過程では、溶鋼中のAl
2 3 の量が多くなりやすく、そのため、鋳造中に浸漬
ノズルが詰まりやすい。一方、浸漬ノズルの詰まりを防
止するために、浸漬ノズル内の溶鋼中に不活性ガスを吹
き込むと、吹き込まれた不活性ガスの気泡が、鋳型内の
凝固殻に捕捉されやすい。本発明の方法は、2つの課題
を同時に解決しようとするものである。
In the refining process of ultra-low carbon steel, Al
The amount of 2 O 3 is likely to be large, so that the immersion nozzle is likely to be clogged during casting. On the other hand, when an inert gas is blown into molten steel in the immersion nozzle in order to prevent clogging of the immersion nozzle, bubbles of the blown inert gas are likely to be captured by the solidified shell in the mold. The method of the present invention seeks to solve two problems simultaneously.

【0014】不活性ガスを吹き込む部分は、タンディッ
シュの鋳型への給湯孔から上記浸漬ノズルの吐出孔の間
に設ける。詳しくは後述する図2に示すように、タンデ
ィッシュ1の鋳型への給湯孔に備えた上ノズル耐火物
2、浸漬ノズル4を取り付けたスライディングプレート
3または浸漬ノズル4に設ける。
The portion into which the inert gas is blown is provided between the hot water supply hole to the mold of the tundish and the discharge hole of the immersion nozzle. As shown in detail in FIG. 2 described later, the tundish 1 is provided on the upper nozzle refractory 2 provided for the hot water supply hole to the mold, the sliding plate 3 to which the immersion nozzle 4 is attached, or the immersion nozzle 4.

【0015】鋳型内のメニスカス近傍の溶鋼流速とは、
溶鋼の表面から50mm内の平均流速を意味する。詳し
くは後述する図1に示す鋳型内の溶鋼の流れにおいて、
溶鋼の吐出流9に起因する溶鋼の反転流9cおよび不活
性ガスに起因する溶鋼の流れ9dのことである。
The molten steel flow velocity near the meniscus in the mold is
It means the average flow velocity within 50 mm from the surface of molten steel. In detail, in the flow of molten steel in the mold shown in FIG.
The reverse flow 9c of the molten steel caused by the discharge flow 9 of the molten steel and the flow 9d of the molten steel caused by the inert gas.

【0016】吐出流に起因する溶鋼の反転流9cの流速
は、鋳型の短辺近傍で最大となる。また、不活性ガスに
起因する溶鋼の流れ9dの流速は、浸漬ノズル近傍で最
大となる。
The flow rate of the reverse flow 9c of the molten steel caused by the discharge flow becomes maximum near the short side of the mold. Further, the flow velocity of the flow 9d of the molten steel caused by the inert gas becomes maximum near the immersion nozzle.

【0017】本発明の方法では、溶鋼の反転流9cの流
速の最大値と不活性ガスによる溶鋼の流れ9dの流速の
最大値との差を20cm/秒以下とするが、その理由は
次のとおりである。すなわち、それぞれの流速の最大値
との差をこの範囲の値とすることにより、浸漬ノズルの
詰まりの発生もなく、また、溶鋼の反転流9cと溶鋼の
流れ9dが衝突する位置で、溶鋼の湯面が波立つことも
なく、気泡や未溶融のパウダ8aが凝固殻に捕捉される
こともないためである。
In the method of the present invention, the difference between the maximum value of the flow rate of the reverse flow 9c of molten steel and the maximum value of the flow rate of the flow 9d of molten steel caused by the inert gas is set to 20 cm / sec or less. It is as follows. That is, by setting the difference between the maximum value of the flow velocity and the maximum value of the flow velocity in this range, clogging of the immersion nozzle does not occur, and the position of the reverse flow 9c of molten steel and the flow 9d of molten steel collide with each other. This is because the molten metal surface does not undulate, and bubbles and unmelted powder 8a are not trapped in the solidified shell.

【0018】[0018]

【発明の実施の形態】図1は、吐出流の方向が鋳型6の
両側の短辺を向いている浸漬ノズル4を用い、浸漬ノズ
ル内の溶鋼中に不活性ガスを吹き込んだときの、鋳型内
の溶鋼12の流動状況を模式的に示す図である。溶鋼の
吐出流9は、鋳型の短辺近傍の凝固殻10に衝突後、上
下に分岐する。溶鋼の下降流9bと反対方向に向かう溶
鋼の上昇流9aは、溶鋼の表面、すなわち、メニスカス
7に達した後、鋳型の短辺側から浸漬ノズルの方向に向
かう溶鋼の反転流9cとなり、浸漬ノズル近傍で潜り込
んで循環流となる。吹き込まれた不活性ガスは気泡13
となり、この気泡は溶鋼中を浮上し、浸漬ノズル近傍の
位置で溶鋼の表面に達する。このとき、気泡の浮力によ
り形成された上向きの溶鋼の流れが溶鋼の表面に達して
後に、浸漬ノズルから鋳型短辺に向かう溶鋼の流れ9d
が形成される。この溶鋼の流れ9dは、溶鋼の反転流9
cと衝突し、潜り込んで循環流となる。
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a case where an immersion nozzle 4 whose discharge flow is directed to the short sides on both sides of a mold 6 and an inert gas is blown into molten steel in the immersion nozzle. It is a figure which shows typically the flow condition of the molten steel 12 inside. The molten steel discharge flow 9 collides with the solidified shell 10 near the short side of the mold and then branches up and down. The rising flow 9a of the molten steel flowing in the opposite direction to the descending flow 9b of the molten steel reaches the surface of the molten steel, that is, the meniscus 7, and then becomes a reverse flow 9c of the molten steel flowing from the short side of the mold toward the immersion nozzle. It sinks near the nozzle and forms a circulating flow. The injected inert gas is bubbles 13
The air bubbles float in the molten steel and reach the surface of the molten steel at a position near the immersion nozzle. At this time, after the upward flow of the molten steel formed by the buoyancy of the bubbles reaches the surface of the molten steel, the flow 9d of the molten steel from the immersion nozzle toward the short side of the mold is formed.
Is formed. The flow 9d of the molten steel is the reverse flow 9 of the molten steel.
It collides with c and sinks into a circulating flow.

【0019】図2は、タンディッシュの鋳型への給湯
孔、浸漬ノズル、不活性ガスの吹き込み口3aなどの配
置を模式的に示す図である。鋳型への給湯孔には上ノズ
ル耐火物2を配置し、浸漬ノズル4を取り付けたスライ
ディングプレート3を上ノズルに固定する。スライディ
ングプレートは、鋳型へ供給する溶鋼の流量を調整する
ための板状の耐火物である。
FIG. 2 is a diagram schematically showing the arrangement of hot water supply holes to the mold of the tundish, immersion nozzles, inert gas blowing ports 3a, and the like. The upper nozzle refractory 2 is arranged in the hot water supply hole to the mold, and the sliding plate 3 to which the immersion nozzle 4 is attached is fixed to the upper nozzle. The sliding plate is a plate-like refractory for adjusting the flow rate of molten steel supplied to the mold.

【0020】溶鋼中のAl2 3 などが浸漬ノズル4の
内壁や吐出孔5近傍に付着し、最終的には浸漬ノズルが
詰まり、鋳造ができなくなる。これを防止するため、多
孔質の耐火物や内径が0.5mm程度の微細径の鋼製の
管を複数個埋め込んだ不活性ガスの吹き込み口3aの耐
火物を、上ノズル耐火物2やスライディングプレート3
または浸漬ノズル4に設け、不活性ガスを吹き込む。
Al 2 O 3 and the like in the molten steel adhere to the inner wall of the immersion nozzle 4 and the vicinity of the discharge hole 5, and finally the immersion nozzle is clogged, so that casting cannot be performed. To prevent this, a porous refractory or a refractory of an inert gas blowing port 3a in which a plurality of fine-diameter steel pipes having an inner diameter of about 0.5 mm are embedded are inserted into an upper nozzle refractory 2 or a sliding nozzle. Plate 3
Alternatively, an inert gas is blown into the immersion nozzle 4.

【0021】本発明の方法では、吹き込まれた不活性ガ
スにより発生する浸漬ノズルから鋳型の短辺に向かう溶
鋼流速の最大値と鋳型の短辺から浸漬ノズルに向かう溶
鋼流速の最大値との差を、20cm/秒以下となるよう
に制御する。20cm/秒を超える場合には、上述した
ように、溶鋼の反転流9cと溶鋼の流れ9dが衝突する
位置で、溶鋼の湯面が激しく波立ち、そのため気泡や未
溶融のパウダが凝固殻に捕捉されやすくなるからであ
る。
In the method of the present invention, the difference between the maximum value of the flow rate of the molten steel from the immersion nozzle generated by the blown inert gas toward the short side of the mold and the maximum value of the flow rate of the molten steel from the short side of the mold toward the immersion nozzle. Is controlled to be 20 cm / sec or less. When the flow rate exceeds 20 cm / sec, the molten steel surface vibrates violently at the position where the reverse flow 9c of the molten steel and the flow 9d of the molten steel collide as described above, so that bubbles and unmelted powder are trapped in the solidified shell. This is because it is easy to be done.

【0022】メニスカス近傍の溶鋼の流速は、溶鋼に浸
漬するタイプのカルマン渦の発生原理を応用した流速計
を用いることもできるし、溶鋼に対して非接触式のもの
を用いてもよい。
The flow velocity of the molten steel in the vicinity of the meniscus may be a flow meter which utilizes the principle of generating Karman vortices of the type immersed in the molten steel, or may be a non-contact type flow meter for the molten steel.

【0023】吐出流に起因する溶鋼の反転流9cの流速
の最大値および不活性ガスに起因する溶鋼の流れ9dの
流速の最大値は、鋳型の短辺近傍および浸漬ノズル近傍
で、それぞれ2〜3の位置で測定することにより求めら
れる。
The maximum value of the flow velocity of the reverse flow 9c of the molten steel caused by the discharge flow and the maximum value of the flow velocity of the flow 9d of the molten steel caused by the inert gas are 2 to 2 near the short side of the mold and near the immersion nozzle, respectively. It is determined by measuring at position 3.

【0024】溶鋼の反転流9cの溶鋼流速の最大値と不
活性ガスによる溶鋼の流れ9dの溶鋼流速の最大値との
差を20cm/秒以下に制御する方法は、不活性ガスの
吹き込み量を浸漬ノズルの詰まりが発生しない程度に減
らしながら、電磁力による溶鋼流動制動装置により、鋳
型内の溶鋼の流動を制動することが望ましい。もう少し
詳しく、次に説明する。
The method of controlling the difference between the maximum value of the flow velocity of the molten steel in the reverse flow 9c of the molten steel and the maximum value of the flow velocity of the molten steel in the flow 9d of the molten steel due to the inert gas to 20 cm / sec or less is as follows. It is desirable to brake the flow of the molten steel in the mold by a molten steel flow braking device using electromagnetic force while reducing the immersion nozzle to a level that does not cause clogging. This will be described in more detail below.

【0025】鋳型の短辺から浸漬ノズルの方向に向かう
溶鋼の反転流9cの溶鋼流速は、一般的に不活性ガスに
よる溶鋼の流れ9dの溶鋼流速よりも速い。そこで、溶
鋼流速の最大値の差を制御する方法として、不活性ガス
の吹き込み量を多くする方法もあるが、このときには、
凝固殻に気泡が捕捉されやすくなる。したがって、不活
性ガスの吹き込み量を浸漬ノズルの詰まりが発生しない
程度に減らしていくのが望ましいが、不活性ガスの吹き
込み量を、単に減らすだけでは、溶鋼の反転流9cの流
速は速いままであり、溶鋼の反転流9cと溶鋼の流れ9
dが衝突する位置で、メニスカス近傍の溶鋼の湯面は波
立ちやすくなる。そこで、不活性ガスの吹き込み量を減
らすと同時に、溶鋼の反転流9cの流速を溶鋼流動制動
装置により遅くするのが望ましい。
The molten steel flow velocity of the reverse flow 9c of the molten steel from the short side of the mold toward the immersion nozzle is generally higher than the molten steel flow velocity of the molten steel flow 9d due to the inert gas. Therefore, as a method of controlling the difference between the maximum values of the flow rate of the molten steel, there is a method of increasing the blowing amount of the inert gas.
Air bubbles are likely to be trapped in the solidified shell. Therefore, it is desirable to reduce the blowing amount of the inert gas to such an extent that the clogging of the immersion nozzle does not occur. However, if the blowing amount of the inert gas is simply reduced, the flow rate of the reverse flow 9c of the molten steel is kept high. Yes, reverse flow 9c of molten steel and flow 9 of molten steel
At the position where d collides, the molten steel surface of the molten steel in the vicinity of the meniscus tends to undulate. Therefore, it is desirable that the flow rate of the reverse flow 9c of the molten steel be reduced by the molten steel flow braking device while the amount of the inert gas blown is reduced.

【0026】図3は、鋳型内に設ける溶鋼流動制動装置
の例を模式的に示す図である。溶鋼流動制動装置11と
しては、電磁ブレーキなどを用いることができる。鋳型
内の幅方向に、浸漬ノズル4を挟んで2列、高さ方向に
3段で、合計6対の溶鋼流動制動装置11を設けた例を
示す。溶鋼流動制動装置の1対とは、図示していない
が、鋳型の相対する長辺の外側に、長辺を挟んで設けた
装置が1対である。鋳型の高さ方向に3段設ける場合に
は、上段が溶鋼のメニスカス近傍相当、中段が浸漬ノズ
ルからの吐出流近傍相当、下段が鋳型の出側近傍相当の
位置とするのが効果的である。少なくともメニスカス近
傍の1段を設けるのが望ましい。
FIG. 3 is a diagram schematically showing an example of a molten steel flow braking device provided in a mold. As the molten steel flow braking device 11, an electromagnetic brake or the like can be used. An example in which a total of six pairs of molten steel flow braking devices 11 are provided in two rows across the immersion nozzle 4 and three steps in the height direction in the width direction in the mold. Although not shown, one pair of the molten steel flow braking devices is a pair of devices that are provided outside the opposite long sides of the mold with the long sides interposed therebetween. When three stages are provided in the height direction of the mold, it is effective that the upper stage corresponds to the vicinity of the meniscus of molten steel, the middle stage corresponds to the vicinity of the discharge flow from the immersion nozzle, and the lower stage corresponds to the vicinity of the exit side of the mold. . It is desirable to provide at least one stage near the meniscus.

【0027】電磁力により鋳型内の溶鋼の流動を制動し
つつ、不活性ガスの吹き込み量は0.2〜3.0(Nリ
ットル/溶鋼t)とするのが望ましい。
It is desirable that the flow of the inert gas be 0.2 to 3.0 (N liter / t of molten steel) while damping the flow of the molten steel in the mold by the electromagnetic force.

【0028】0.2(Nリットル/溶鋼t)未満では、
少なすぎて浸漬ノズルが詰まりやすくなる。さらに、不
活性ガスによる鋳型内の溶鋼中の酸化物の浮上促進効果
が少なくなる。また、3.0(Nリットル/溶鋼t)を
超えて吹き込むと、不活性ガスの気泡が凝固殻に捕捉さ
れやすくなる。さらに、鋳型内の浸漬ノズル近傍の溶鋼
の表面において、ボイリング(溶鋼表面から不活性ガス
が噴出し、溶鋼表面が泡立つ状態)が発生し、未溶融パ
ウダーの巻き込みが発生しやすい。製品の鋼板の表面性
状がとくに厳しく要求される場合には、1.0(Nリッ
トル/溶鋼t)以下にするのがより望ましい。
If it is less than 0.2 (N liter / t of molten steel),
When the amount is too small, the immersion nozzle is easily clogged. Further, the effect of promoting the floating of the oxide in the molten steel in the mold by the inert gas is reduced. In addition, when the gas is blown over 3.0 (N liters / t of molten steel), bubbles of the inert gas are easily captured by the solidified shell. Furthermore, boiling (a state in which an inert gas is ejected from the molten steel surface and the molten steel surface foams) occurs on the surface of the molten steel in the vicinity of the immersion nozzle in the mold, and the unmelted powder is likely to be entrained. When the surface properties of the steel sheet of the product are particularly strictly required, it is more preferable to set the steel sheet to 1.0 (N liter / molten steel t) or less.

【0029】したがって、不活性ガスの吹き込み量は
0.2〜3.0(Nリットル/溶鋼t)が望ましく、
0.2〜1.0(Nリットル/溶鋼t)が、さらに望ま
しい。
Therefore, the amount of the inert gas to be blown is desirably 0.2 to 3.0 (N liter / t of molten steel).
0.2 to 1.0 (N liter / t of molten steel) is more desirable.

【0030】[0030]

【実施例】垂直部長さが3mの垂直曲げ型連続鋳造機を
用いて、断面形状が厚み270mm、幅1500mm
で、炭素含有率が0.004重量%の極低炭素鋼(アル
ミキルド鋼)のスラブを、1.50m/分の速度で鋳造
した。
EXAMPLE Using a vertical bending type continuous casting machine having a vertical length of 3 m, a cross-sectional shape was 270 mm in thickness and 1500 mm in width.
A slab of ultra low carbon steel (aluminum killed steel) having a carbon content of 0.004% by weight was cast at a speed of 1.50 m / min.

【0031】図3に示す合計6対の装置構成の電磁ブレ
ーキ装置を鋳型に設けた。また、スライディングプレー
トに、不活性ガス吹き込み用の貫通孔(径0.3mm、
孔数10個)を埋め込んだ耐火物を設けてArガスを吹
き込んだ。
The mold was provided with a total of six pairs of electromagnetic brake devices as shown in FIG. In addition, a through hole (diameter 0.3 mm,
Ar gas was blown in with a refractory in which 10 holes were buried.

【0032】鋳造速度が一定となった状態で鋳造された
鋳片から、鋳造方向に長さ1mの鋳片のサンプルを採取
し、鋳片の表面のピンホール性欠陥、パウダ性欠陥およ
び鋳片の表面から内部にかけての清浄度を調査した。ま
た、鋳造中に浸漬ノズルの詰まり状況を観察した。詰ま
りが発生した場合には、鋳造速度を一定に維持しようと
して浸漬ノズルに供給する溶鋼の量を制御するスライデ
ィングプレートの開度が大きくなる現象が現れるので、
その開度の変化を観察することにより、浸漬ノズルの詰
まり発生状況を判断した。
A sample of a slab having a length of 1 m in the casting direction was sampled from a slab cast at a constant casting speed, and pinhole defects, powder defects, and slabs on the surface of the slab were sampled. The cleanliness from the surface to the inside was investigated. Further, the state of clogging of the immersion nozzle was observed during casting. When clogging occurs, a phenomenon occurs in which the opening of the sliding plate that controls the amount of molten steel supplied to the immersion nozzle increases in order to maintain the casting speed constant,
By observing the change in the opening, the state of clogging of the immersion nozzle was determined.

【0033】鋳片の表面のピンホール性欠陥の調査方法
は、次のとおりである。得られた鋳片のサンプルから、
一辺が50mmの正方形の鋳片表面を含む試料を切り出
し、鋳片表面から1mm深さまで研削した。その研磨し
た表面を、光学顕微鏡にて100倍の倍率で、100μ
m以上の穴あき状のピンホール性欠陥の個数を調査し
た。同時に、研磨前の研削したままの鋳片の表面に、未
溶融のパウダがあるかどうかを目視で調査した。ピンホ
ール性欠陥の個数の最も少なかった試験の試験結果を指
数1.0として、その他の試験結果を評価した。
The method of investigating the pinhole defect on the surface of the slab is as follows. From the obtained slab sample,
A sample including a square slab surface with a side of 50 mm was cut out and ground to a depth of 1 mm from the slab surface. The polished surface was observed with an optical microscope at a magnification of 100 times, 100 μm.
The number of perforated pinhole defects of m or more was investigated. At the same time, it was visually inspected for unmelted powder on the surface of the as-ground slab before polishing. Other test results were evaluated with the test result of the test in which the number of pinhole defects was the smallest as an index of 1.0.

【0034】鋳片の表面から内部にかけての清浄度の調
査は、次のようにして行った。鋳片の幅方向の1/4の
位置で、縦10mm、横50mmの長方形の鋳片表面を
含む鋳片全厚の試料を採取した。この試料から、鋳片の
厚み方向に10mmの間隔で、サイコロ状の試料を切り
出した。この試料の鋳片表面を向いた断面について、J
IS G 0555で規定する試験方法により、光学顕
微鏡により400倍の倍率で清浄度を調査した。もっと
も清浄度が悪かった断面の清浄度を、その鋳片の清浄度
とした。清浄度の最も良かった試験の試験結果を指数
1.0として、その他の試験結果を評価した。
The cleanliness from the surface of the slab to the inside of the slab was investigated as follows. A sample of the entire thickness of the slab including the surface of a rectangular slab having a length of 10 mm and a width of 50 mm was sampled at a position 1/4 in the width direction of the slab. From this sample, dice-shaped samples were cut out at intervals of 10 mm in the thickness direction of the slab. The cross section of this sample facing the slab surface is J
According to the test method specified in IS G 0555, the cleanliness was examined with an optical microscope at a magnification of 400 times. The cleanliness of the section having the worst cleanliness was defined as the cleanliness of the slab. Other test results were evaluated, with the test result of the test with the best cleanliness being the index 1.0.

【0035】表1に、試験条件と試験結果を示す。Table 1 shows test conditions and test results.

【0036】[0036]

【表1】 [Table 1]

【0037】本発明例の試験No.1〜No.3では、
本発明で規定する範囲内の溶鋼流速の最大値の差とし、
さらに望ましい範囲内のAr量を吹き込み、3段の電磁
ブレーキを作用させた。試験No.1〜No.3では、
得られた鋳片の表面のピンホール性欠陥は少なく、また
鋳片の清浄度も良好であった。また、パウダ性欠陥はな
く、浸漬ノズル詰まりも発生せず、良好な結果であっ
た。
Test No. of the present invention example 1 to No. In 3,
The difference between the maximum value of the molten steel flow velocity within the range specified by the present invention,
Further, an Ar amount within a desirable range was blown, and a three-stage electromagnetic brake was applied. Test No. 1 to No. In 3,
The surface of the obtained slab had few pinhole defects, and the slab had good cleanliness. In addition, there were no powdery defects, no clogging of the immersion nozzle, and good results were obtained.

【0038】本発明例の試験No.4〜No.6では、
電磁ブレーキを2段、試験No.7では、電磁ブレーキ
を1段のみで試験した。また、溶鋼流速の最大値の差と
吹き込みAr量の条件は、本発明で規定する範囲内また
は望ましい範囲内とした。いずれの試験も、鋳片の表面
のピンホール性欠陥指数は1.2〜1.3、鋳片の清浄
度指数は1.2〜1.3で良好であった。また、パウダ
性欠陥もなく、浸漬ノズルの詰まりも発生しなかった。
Test No. of the present invention example. 4-No. In 6,
Test No. 2 with electromagnetic brake In No. 7, the electromagnetic brake was tested in only one stage. The difference between the maximum value of the molten steel flow rate and the amount of blown Ar was set within the range specified in the present invention or within a desirable range. In any of the tests, the pinhole defect index on the surface of the slab was 1.2 to 1.3, and the cleanness index of the slab was 1.2 to 1.3. In addition, there was no powder defect, and no clogging of the immersion nozzle occurred.

【0039】比較例の試験No.8では、ピンホール性
欠陥指数が5.5と高く、清浄度指数も4.5と悪かっ
た。また、パウダ性欠陥も認められた。その理由は、A
rガスの吹き込み量は望ましい範囲内であったが、電磁
ブレーキを用いなかったので、溶鋼流速の最大値の差が
30cm/秒と速くなり、鋳型内の浸漬ノズル近傍で溶
鋼の表面が波立ちが顕著であったためである。
Test No. of Comparative Example In No. 8, the pinhole defect index was as high as 5.5, and the cleanliness index was as poor as 4.5. In addition, powder defects were also observed. The reason is A
Although the amount of r gas blown was within the desired range, the difference in the maximum value of the molten steel flow velocity was as fast as 30 cm / sec because no electromagnetic brake was used, and the surface of the molten steel was wavy near the immersion nozzle in the mold. This is because it was remarkable.

【0040】比較例の試験No.9では、ピンホール性
欠陥指数が8.0と高く、悪い結果であった。清浄度指
数も4.0と悪かった。パウダ性欠陥も認められた。そ
の理由は、電磁ブレーキを用いずに、Arガスの吹き込
み量を、望ましい範囲外で大きくしたので、溶鋼流速の
最大値の差が25cm/秒まで低減したが、Arガス量
が多いために、鋳型内の溶鋼の表面にボイリングが発生
しためである。
Test No. of Comparative Example In No. 9, the pinhole defect index was as high as 8.0, which was a bad result. The cleanliness index was also bad at 4.0. Powder defects were also observed. The reason is that the blowing amount of Ar gas was increased outside the desired range without using the electromagnetic brake, so that the difference in the maximum value of the flow rate of molten steel was reduced to 25 cm / sec. This is because boiling occurs on the surface of the molten steel in the mold.

【0041】比較例の試験No.10では、Arガスの
吹き込み量を、望ましい範囲外で少なくし、かつ上部の
1段の電磁ブレーキを用いた。1段の電磁ブレーキを用
いたが、Ar量が少ないこともあって、溶鋼流速の最大
値の差は30cm/秒と速くなった。ピンホール性欠陥
指数は3.0で悪かった。また、清浄度指数が7.0と
高くなり、悪かった。Ar量が少なくて、溶鋼中の酸化
物の浮上が少なかったためである。
Test No. of Comparative Example In No. 10, the blowing amount of Ar gas was reduced outside the desired range, and an upper one-stage electromagnetic brake was used. Although a one-stage electromagnetic brake was used, the difference in the maximum value of the flow rate of the molten steel was as fast as 30 cm / sec because of the small amount of Ar. The pinhole defect index was bad at 3.0. Further, the cleanliness index was as high as 7.0, which was bad. This is because the amount of Ar was small and the floating of the oxide in the molten steel was small.

【0042】[0042]

【発明の効果】本発明の方法の適用により、鋳造中に浸
漬ノズルの詰まりが発生することなく、鋳片表面にピン
ホール性欠陥やパウダ性欠陥がなく、表面性状に優れ、
かつ清浄度に優れた鋳片を得ることが可能である。
According to the method of the present invention, no clogging of the immersion nozzle occurs during casting, there is no pinhole defect or powder defect on the slab surface, and the surface properties are excellent.
In addition, it is possible to obtain a slab excellent in cleanliness.

【図面の簡単な説明】[Brief description of the drawings]

【図1】浸漬ノズル内の溶鋼中に不活性ガスを吹き込ん
だときの、鋳型内の溶鋼の流動状況を模式的に示す図で
ある。
FIG. 1 is a view schematically showing a flow state of molten steel in a mold when an inert gas is blown into molten steel in an immersion nozzle.

【図2】タンディッシュの鋳型への給湯孔、浸漬ノズ
ル、不活性ガス吹き込み位置などの配置を模式的に示す
図である。
FIG. 2 is a diagram schematically showing an arrangement of a hot water supply hole to a mold of a tundish, an immersion nozzle, an inert gas blowing position, and the like.

【図3】鋳型内に設ける溶鋼流動制動装置の例を模式的
に示す図である。
FIG. 3 is a diagram schematically illustrating an example of a molten steel flow braking device provided in a mold.

【符号の説明】[Explanation of symbols]

1: タンディッシュ 2:上ノズル耐火
物 3: スライディングプレート 3a:不活性ガス吹
き込み口 4: 浸漬ノズル 5:吐出孔 6: 鋳型 7:メニスカス 8: パウダー 8a:未溶融パウダ 8
b:溶融パウダ 9: 溶鋼の吐出流 9a:溶鋼の上昇流 9
b:溶鋼の下降流 9c:溶鋼の反転流 9d:不活性ガスによる溶鋼
の流れ 10: 凝固殻 11:溶鋼流動制動装置 12: 溶鋼 13:気泡
1: Tundish 2: Upper nozzle refractory 3: Sliding plate 3a: Inert gas injection port 4: Immersion nozzle 5: Discharge hole 6: Mold 7: Meniscus 8: Powder 8a: Unmelted powder 8
b: molten powder 9: discharge flow of molten steel 9a: ascending flow of molten steel 9
b: downflow of molten steel 9c: reverse flow of molten steel 9d: flow of molten steel by inert gas 10: solidified shell 11: molten steel flow braking device 12: molten steel 13: air bubble

───────────────────────────────────────────────────── フロントページの続き (72)発明者 深川 信 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 AA09 HA01 HA02 MB11 MB20 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shin Fukagawa F-term (reference) 4E004 AA09 HA01 HA02 MB11 MB20 in 4-33 Kitahama, Chuo-ku, Osaka-shi, Osaka

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】吐出流が鋳型の短辺側に向かう吐出孔を備
える浸漬ノズルを用いるとともに、タンディッシュの鋳
型への給湯孔から上記浸漬ノズルの吐出孔の間で、溶鋼
中に不活性ガスを吹き込みつつ連続鋳造する方法であっ
て、鋳型内の溶鋼のメニスカス近傍での溶鋼流速を、吹
き込まれた上記不活性ガスにより発生する浸漬ノズル近
傍から鋳型の短辺に向かう流れの最大値と鋳型の短辺側
から浸漬ノズルに向かう流れの最大値との差が20cm
/秒以下となるように制御することを特徴とする鋼の連
続鋳造方法。
An immersion nozzle provided with a discharge hole whose discharge flow is directed to the short side of the mold, and an inert gas is introduced into the molten steel from a hot water supply hole to the mold of the tundish to a discharge hole of the immersion nozzle. Is a method of continuous casting while blowing the molten steel, wherein the molten steel flow velocity near the meniscus of the molten steel in the mold, the maximum value of the flow from the vicinity of the immersion nozzle generated by the injected inert gas to the short side of the mold and the mold The difference from the maximum value of the flow from the short side to the immersion nozzle is 20 cm
A continuous casting method for steel, characterized in that the control is performed so as to be not more than / sec.
【請求項2】鋳型の長辺の外側に鋳型を挟んで設けた電
磁力による溶鋼流動制動装置により、鋳型内の溶鋼の流
動を制動しつつ、不活性ガスの吹き込み量0.2〜3.
0(Nリットル/溶鋼t)の範囲内で鋳造することを特
徴とする請求項1に記載の鋼の連続鋳造方法。
2. An inert gas blowing amount of 0.2 to 3. while the flow of molten steel in the mold is braked by a molten steel flow braking device by an electromagnetic force provided outside the long side of the mold with the mold interposed therebetween.
The continuous casting method for steel according to claim 1, wherein the casting is performed within a range of 0 (N liter / t molten steel).
JP30429498A 1998-10-26 1998-10-26 Continuous casting method Expired - Fee Related JP3385982B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP30429498A JP3385982B2 (en) 1998-10-26 1998-10-26 Continuous casting method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP30429498A JP3385982B2 (en) 1998-10-26 1998-10-26 Continuous casting method

Publications (2)

Publication Number Publication Date
JP2000126850A true JP2000126850A (en) 2000-05-09
JP3385982B2 JP3385982B2 (en) 2003-03-10

Family

ID=17931311

Family Applications (1)

Application Number Title Priority Date Filing Date
JP30429498A Expired - Fee Related JP3385982B2 (en) 1998-10-26 1998-10-26 Continuous casting method

Country Status (1)

Country Link
JP (1) JP3385982B2 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109047695A (en) * 2018-08-01 2018-12-21 东北大学 A kind of immersed nozzle for continuous casting mould Argon control method
CN111872338A (en) * 2020-07-10 2020-11-03 上海大学 Method for judging flow field form of slab crystallizer
CN113426972A (en) * 2021-06-04 2021-09-24 北京首钢股份有限公司 Crystallizer casting powder control method, device, equipment and storage medium
CN113500173A (en) * 2021-06-11 2021-10-15 上海大学 Control method for molten steel flow field form of medium-section slab crystallizer

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109047695A (en) * 2018-08-01 2018-12-21 东北大学 A kind of immersed nozzle for continuous casting mould Argon control method
CN109047695B (en) * 2018-08-01 2019-06-18 东北大学 A kind of immersed nozzle for continuous casting mould Argon control method
CN111872338A (en) * 2020-07-10 2020-11-03 上海大学 Method for judging flow field form of slab crystallizer
CN111872338B (en) * 2020-07-10 2021-11-05 上海大学 Method for judging flow field form of slab crystallizer
CN113426972A (en) * 2021-06-04 2021-09-24 北京首钢股份有限公司 Crystallizer casting powder control method, device, equipment and storage medium
CN113500173A (en) * 2021-06-11 2021-10-15 上海大学 Control method for molten steel flow field form of medium-section slab crystallizer
CN113500173B (en) * 2021-06-11 2022-10-11 上海大学 Control method for molten steel flow field form of medium-section slab crystallizer

Also Published As

Publication number Publication date
JP3385982B2 (en) 2003-03-10

Similar Documents

Publication Publication Date Title
KR100710714B1 (en) Method and Apparatus for Controlling Flow of Molten Steel in Mold, and Method for Producing Continuous Castings
Thomas Fluid flow in the mold
JP2000126850A (en) Continuous casting method
JP3365362B2 (en) Continuous casting method
JP3649143B2 (en) Continuous casting method
JP5076330B2 (en) Steel continuous casting method
JP3508420B2 (en) Method of controlling molten steel flow in continuous casting mold of steel
JP4407260B2 (en) Steel continuous casting method
JP4972776B2 (en) Flow control method for molten steel in mold and surface quality judgment method for continuous cast slab
JP3524507B2 (en) Steel continuous casting method
JP4427429B2 (en) Method and apparatus for controlling flow in strand pool
JP3697040B2 (en) Immersion nozzle for continuous casting of steel and method for continuous casting of steel using the same
JP4474948B2 (en) Steel continuous casting method
JP4932985B2 (en) Steel continuous casting method
JP2000052003A (en) Molten steel continuous casting method
JP3527122B2 (en) Slab with few nonmetallic inclusions
JP3460687B2 (en) Steel continuous casting method
JP4220848B2 (en) Tundish for continuous casting of steel with heating function
JP2002103009A (en) Continuous casting method
JPH10263777A (en) Method for continuously casting steel
JP2000202602A (en) Method for removing inclusion in tundish for continuos casting
JP4492333B2 (en) Steel continuous casting method
JP2000288722A (en) Immersion nozzle and continuous casting method
JPH08229649A (en) Continuous casting apparatus and method thereof
JP2010005691A (en) Continuous casting method for steel

Legal Events

Date Code Title Description
FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20080110

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20090110

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100110

Year of fee payment: 7

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110110

Year of fee payment: 8

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120110

Year of fee payment: 9

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130110

Year of fee payment: 10

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130110

Year of fee payment: 10

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: 20130110

Year of fee payment: 10

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140110

Year of fee payment: 11

LAPS Cancellation because of no payment of annual fees