JP4932985B2 - Steel continuous casting method - Google Patents

Steel continuous casting method Download PDF

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Publication number
JP4932985B2
JP4932985B2 JP2000273019A JP2000273019A JP4932985B2 JP 4932985 B2 JP4932985 B2 JP 4932985B2 JP 2000273019 A JP2000273019 A JP 2000273019A JP 2000273019 A JP2000273019 A JP 2000273019A JP 4932985 B2 JP4932985 B2 JP 4932985B2
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Japan
Prior art keywords
nozzle
molten steel
mold
immersion
slab
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JP2000273019A
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Japanese (ja)
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JP2002079355A (en
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征一郎 南部
久生 山崎
健二 大島
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JFE Steel Corp
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JFE Steel Corp
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Description

【0001】
【発明の属する技術分野】
本発明は、浸漬ノズルとして2孔ノズルを用いて溶鋼を鋳型内に供給する連続鋳造方法に関する。
【0002】
【従来の技術】
連続鋳造によって鋳片を製造する場合、溶鋼をタンディッシュから鋳型内に供給する。鋳型内に供給された溶鋼は鋳型と接触して冷却され、薄い凝固層(以下、凝固シェルという)を形成する。また、鋳型と凝固シェルとの潤滑,鋳型内の溶鋼の保温,溶鋼浴面の酸化防止等を目的として、鋳型内の溶鋼の浴面にモールドパウダーを投入する。こうして溶鋼を鋳型内に注入しながら凝固シェルを下方へ引き抜き、さらに鋳型下方に配設された複数個のサポートロールの間隙からスプレーノズルを介して冷却水を鋳片に吹き付けて冷却することによって鋳片を製造する。
【0003】
このとき、タンディッシュに配設されたタンディッシュノズルの目詰まりを防止するために、タンディッシュに収容された溶鋼中にArガスを吹き込む。またタンディッシュノズルを介してタンディッシュから鋳型へ溶鋼を供給する際に、溶鋼が空気によって酸化されるのを防止し、かつ介在物やモールドパウダーが溶鋼中へ巻き込まれるのを防止するために、浸漬ノズルを使用する。
【0004】
浸漬ノズルは、先端部に配設された吐出口を鋳型内の溶鋼に浸漬した状態で使用され、吐出口が下方に向かって開口して溶鋼を下方へ吐出する浸漬ノズル(以下、ストレートノズルという)、あるいは吐出口が鋳型の短辺方向に対向して両側に1個ずつ開口して溶鋼を鋳型の短辺方向へ吐出する浸漬ノズル(以下、2孔ノズルという)等が知られている。
【0005】
ストレートノズルを用いる場合は、吐出口から下方へ向かって吐出する溶鋼が、凝固シェル内の未凝固の溶鋼に浸入する深さが深くなるので凝固シェルの成長が遅く、鋳込速度を低下して操業しなければならない。また溶鋼に巻き込まれた介在物やモールドパウダーが、凝固シェル内の未凝固の溶鋼中に深く浸入するので、鋳片に表面欠陥や内部欠陥が発生する原因になる。
【0006】
それに対して2孔ノズルを用いる場合は、溶鋼が吐出口から鋳型の短辺方向へ向かって吐出するので、凝固シェル内の未凝固の溶鋼に浸入する深さは浅い。したがって凝固シェルの成長速度は向上し、かつ鋳片の表面欠陥や内部欠陥は抑制される。
さらに2孔ノズルを用いて鋳片の品質をより一層改善するために、種々の技術が提案されている。
【0007】
たとえば特開平5-329596号公報には、連続鋳造モールド内溶鋼流動制御方法が開示されている。この方法は、2孔ノズルの吐出口から吐出した溶鋼が鋳型の短辺に当たって上下に分離したうちの、上方へ向かって流れる溶鋼流(以下、メニスカス流という)に移動磁界を印加して、メニスカス流の流速を10〜60cm/sec に制御することによって表面欠陥を抑制しようとするものである。しかしこの方法では、メニスカス流がモールドパウダーを巻き込み、鋳片に内部欠陥が発生する原因になる可能性があるという問題があった。
【0008】
【発明が解決しようとする課題】
本発明は上記のような問題を解消し、鋼の連続鋳造を行なう際に、表面欠陥や内部欠陥のない鋳片を製造する連続鋳造方法を提供することを目的とする。
【0009】
【課題を解決するための手段】
本発明者らは、鋳型内の溶鋼の挙動について水モデル実験によって種々検討した。その結果、メニスカス流の流速が、30cm/sec 未満では鋳片にブローホールが発生する可能性が増大し、40cm/sec を超えると未凝固の溶鋼中にモールドパウダーが巻き込まれる可能性が増大することを見出した。メニスカス流の流速は、移動磁界を印加しない場合でも、鋳込速度,ノズル詰まり防止用Arガスの流量,浸漬ノズルの吐出角および浸漬ノズルの浸漬深さに応じて変動するので、鋳片の表面欠陥や内部欠陥を防止するためには、これらの要因を適性範囲に維持する必要がある。
【0010】
本発明は、浸漬ノズルとして2孔ノズルを用いる鋼の連続鋳造方法において、鋳片の鋳込速度Vが 0.5〜3.0 m/min の範囲を満足し、ノズル詰まり防止用Arガスの流量Qが3〜50N-liter/min の範囲を満足し、浸漬ノズルの吐出角θが0〜45°の範囲を満足し、浸漬ノズルの浸漬深さDが30〜400mm の範囲を満足し、かつ鋳込速度V(m/min )、Arガス流量Q(N-liter/min )、吐出角θ(°)および浸漬深さD(mm)が下記の (1)式を満足する鋼の連続鋳造方法である。
【0011】
0≦18×V− 4.9×θ+2.35×Q−0.08×D+34≦40 ・・・ (1)
V:鋳片の鋳込速度(m/min )
Q:ノズル詰まり防止用Arガスの流量(N-liter/min )
θ:浸漬ノズルの吐出角(°)
D:浸漬ノズルの浸漬深さ(mm)
【0012】
【発明の実施の形態】
図1は、本発明を適用する連続鋳造設備の要部を示す断面図である。タンディッシュ1には、溶鋼2を鋳型8内に供給するためにタンディッシュノズル4が配設される。溶鋼2がタンディッシュノズル4を介してタンディッシュ1から鋳型8内に供給されるときに、空気によって酸化されるのを防止ために、タンディッシュノズル4に接続して浸漬ノズル5が配設される。浸漬ノズル5は、先端部に配設された吐出口6を鋳型8内の溶鋼2に浸漬した状態で使用される。なお本発明においては、浸漬ノズル5として2孔ノズルを使用する。
【0013】
タンディッシュ1内の溶鋼2は、タンディッシュノズル4および浸漬ノズル5を通って、吐出口6から鋳型8内に供給される。鋳型8内に注入された溶鋼2は鋳型8によって冷却され、凝固シェル9を形成する。鋳型8内の溶鋼2の浴面には、鋳型8と凝固シェル9との潤滑,溶鋼2の保温,溶鋼2浴面の酸化防止等を目的としてモールドパウダー7を投入する。
【0014】
なおタンディッシュノズル4の目詰まりを防止するために、溶鋼2中にArガス3を吹き込む。本発明においては、溶鋼2中へArガス3を吹き込む方法は特定の方法に限定しない。従来から知られている方法を使用すれば良いのであって、たとえばタンディッシュノズル4としてポーラスノズルを使用する方法やガススリーブノズルを使用する方法、あるいはガス吹込みストッパーを使用する方法等を用いれば良い。
【0015】
浸漬ノズル5の吐出口6から鋳型8内に供給される溶鋼2は、矢印aの方向に吐出した後、鋳型8の短辺に当たって、下向き(すなわち矢印bの方向)の流れと上向き(すなわち矢印cの方向)の流れに分離する。この矢印cで示した流れがメニスカス流である。
連続鋳造で製造した鋳片の欠陥としては、 Al23 等の介在物やモールドパウダーの巻き込み、あるいはブローホールが発生する頻度が高い。これらの欠陥のうち、介在物の巻き込みおよびブローホールはメニスカス流の流速が遅いときに発生しやすい。一方、モールドパウダーの巻き込みはメニスカス流の流速が速いときに発生しやすい。
【0016】
メニスカス流の流速は、鋳込速度V(m/min ),ノズル詰まり防止用Arガスの流量Q(N-liter/min ),浸漬ノズルの吐出角θ(°)および浸漬ノズルの浸漬深さD(mm)に応じて変動する。ここで、浸漬ノズルの吐出角θ(°)は、溶鋼2が吐出口6から吐出される矢印aの方向と水平方向とのなす角を指し、浸漬ノズルの浸漬深さD(mm)は、鋳型8内の溶鋼2の浴面から吐出口6の開口部の中心までの深さを指す。
【0017】
そこで連続鋳造の操業で得られた多数のデータを解析した結果、メニスカス流の流速を変動させる要因である鋳込速度V(m/min ),ノズル詰まり防止用Arガスの流量Q(N-liter/min ),浸漬ノズルの吐出角θ(°)および浸漬ノズルの浸漬深さD(mm)に応じて、鋳片の欠陥の発生状況も変化することを見出した。
【0018】
また、鋳片の欠陥の発生状況は、下記の (2)式で算出される指標αの値と相関関係があることも判明した。
指標α=18×V− 4.9×θ+2.35×Q−0.08×D+34 ・・・ (2)
V:鋳片の鋳込速度(m/min )
Q:ノズル詰まり防止用Arガスの流量(N-liter/min )
θ:浸漬ノズルの吐出角(°)
D:浸漬ノズルの浸漬深さ(mm)
すなわち、連続鋳造で製造した鋳片を熱間圧延し、さらに冷間圧延して冷延コイルを製造した。冷延コイルの表面欠陥のヘゲ,スケールおよびスリーバーを、目視で検査して、コイル内欠陥混入率(%)を算出し、前記 (2)式で算出される指標αの値との関係を調査した。なお、コイル内欠陥混入率(%)は下記の (3)式で算出される値である。
【0019】
コイル内欠陥混入率(%)
= 100×(ΣLD /LC ) ・・・ (3)
D :表面欠陥の欠陥長さ(m)
C :コイル全長の長さ(m)
前記 (2)式で算出される指標αの値と前記 (3)式で算出されるコイル内欠陥混入率(%)との関係を図2に示す。図2から明らかなように、指標α値が0〜40の範囲ではコイル内欠陥混入率が極めて低く抑えられているが、指標α値が0未満の範囲および40を超える範囲ではコイル内欠陥混入率が上昇する。つまり鋳片の表面欠陥や内部欠陥を抑制するためには、指標α値が0〜40の範囲を満足する必要がある。すなわち前記 (1)式の範囲を満足する必要がある。
【0020】
【実施例】
表1に示す成分の極低炭素鋼を1500t溶製した後、図1に示す装置を用いて連続鋳造を行なった。連続鋳造の鋳込速度Vは 1.5〜2.2 m/min ,ノズル詰まり防止用Arガスの流量Qは5〜40N-liter/min ,浸漬ノズルの吐出角θは15°,浸漬ノズルの浸漬深さDは30〜300mm であり、鋳片の寸法は厚さ220mm ,幅1000〜1600mmであった。なお、前記 (2)式で算出される指標αの値は0〜40であり、前記 (1)式の範囲を満足した。鋳型内の溶鋼の浴面にはモールドパウダーを投入した。連続鋳造で得られた鋳片を熱間圧延し、さらに冷間圧延して冷延コイルを製造した。これを発明例とする。
【0021】
【表1】
【0022】
また表1に示す成分の極低炭素鋼を1500t溶製した後、鋳込速度Vを 1.5〜 2.2 m/min とし、メニスカス流に移動磁界を印加してメニスカス流の流速を30〜40cm/sec として連続鋳造を行なった。鋳片の寸法は厚さ220mm ,幅1000〜 1600mmであった。なおこの場合、前記 (2)式で算出される指標αの値は、前記 (1)式の範囲を外れるものとした。鋳型内の溶鋼の浴面にはモールドパウダーを投入した。連続鋳造で得られた鋳片を熱間圧延し、さらに冷間圧延して冷延コイルを製造した。これを比較例とする。
【0023】
発明例および比較例の冷延コイルについて、表面欠陥と内部欠陥とによる格落ち率を比べると、発明例の格落ち率は比較例の1/5程度であった。
【0024】
【発明の効果】
本発明では、浸漬ノズルとして2孔ノズルを使用して鋼の連続鋳造を行なう際に、鋳片の表面欠陥や内部欠陥を抑制できる。
【図面の簡単な説明】
【図1】本発明を適用する連続鋳造設備の要部を示す断面図である。
【図2】指標α値とコイル内欠陥混入率との関係を示すグラフである。
【符号の説明】
1 タンディッシュ
2 溶鋼
3 Arガス
4 タンディッシュノズル
5 浸漬ノズル(2孔ノズル)
6 吐出口
7 モールドパウダー
8 鋳型
9 凝固シェル
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a continuous casting method for supplying molten steel into a mold using a two-hole nozzle as an immersion nozzle.
[0002]
[Prior art]
When producing a slab by continuous casting, molten steel is supplied from a tundish into a mold. The molten steel supplied into the mold is cooled in contact with the mold to form a thin solidified layer (hereinafter referred to as a solidified shell). In addition, mold powder is poured into the molten steel bath surface in the mold for the purpose of lubricating the mold and the solidified shell, keeping the molten steel in the mold warm, preventing oxidation of the molten steel bath surface, and the like. In this way, the molten steel is poured into the mold while the solidified shell is pulled downward, and cooling water is sprayed from the gaps between the plurality of support rolls arranged below the mold through the spray nozzle to cool the casting. Manufacture pieces.
[0003]
At this time, in order to prevent clogging of the tundish nozzle disposed in the tundish, Ar gas is blown into the molten steel accommodated in the tundish. In addition, when supplying molten steel from the tundish to the mold via the tundish nozzle, the molten steel is prevented from being oxidized by air, and inclusions and mold powder are prevented from being caught in the molten steel. Use an immersion nozzle.
[0004]
The immersion nozzle is used in a state where the discharge port provided at the tip is immersed in the molten steel in the mold, and the discharge port opens downward and discharges the molten steel downward (hereinafter referred to as a straight nozzle). Or an immersion nozzle (hereinafter referred to as a two-hole nozzle) that discharges molten steel in the direction of the short side of the mold with discharge ports opened one by one on both sides facing the direction of the short side of the mold.
[0005]
When using a straight nozzle, the molten steel discharged downward from the discharge port has a deeper depth that penetrates into the unsolidified molten steel in the solidified shell, so the growth of the solidified shell is slow and the casting speed is reduced. Must operate. In addition, since inclusions and mold powder caught in the molten steel penetrate deeply into the unsolidified molten steel in the solidified shell, it causes surface defects and internal defects in the slab.
[0006]
On the other hand, when the two-hole nozzle is used, the molten steel is discharged from the discharge port toward the short side of the mold, so that the depth of penetration into the unsolidified molten steel in the solidified shell is shallow. Therefore, the growth rate of the solidified shell is improved, and surface defects and internal defects of the slab are suppressed.
Furthermore, various techniques have been proposed in order to further improve the quality of the slab using a two-hole nozzle.
[0007]
For example, JP-A-5-329596 discloses a method for controlling molten steel flow in a continuous casting mold. This method applies a moving magnetic field to a molten steel flow (hereinafter referred to as a meniscus flow) that flows upward while the molten steel discharged from the discharge port of the two-hole nozzle hits the short side of the mold and is separated vertically. It is intended to suppress surface defects by controlling the flow velocity of the flow to 10 to 60 cm / sec. However, this method has a problem that the meniscus flow entrains the mold powder and may cause internal defects in the slab.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a continuous casting method for solving the above-described problems and producing a slab having no surface defects or internal defects when performing continuous casting of steel.
[0009]
[Means for Solving the Problems]
The present inventors have studied various behaviors of molten steel in the mold by water model experiments. As a result, when the flow velocity of the meniscus flow is less than 30 cm / sec, there is an increased possibility of blowholes in the slab, and when it exceeds 40 cm / sec, the possibility of mold powder being caught in unsolidified molten steel increases. I found out. Even when no moving magnetic field is applied, the meniscus flow velocity varies depending on the casting speed, the flow rate of Ar gas for preventing nozzle clogging, the discharge angle of the immersion nozzle, and the immersion depth of the immersion nozzle. In order to prevent defects and internal defects, it is necessary to maintain these factors within a suitable range.
[0010]
According to the present invention, in a continuous casting method of steel using a two-hole nozzle as an immersion nozzle, the casting speed V of the slab satisfies the range of 0.5 to 3.0 m / min, and the flow rate Q of Ar gas for preventing nozzle clogging is 3 Satisfies the range of -50N-liter / min, satisfies the range of the discharge angle θ of the immersion nozzle of 0-45 °, the immersion depth D of the immersion nozzle satisfies the range of 30-400mm, and casting speed This is a continuous casting method for steel in which V (m / min), Ar gas flow rate Q (N-liter / min), discharge angle θ (°) and immersion depth D (mm) satisfy the following formula (1). .
[0011]
0 ≦ 18 × V−4.9 × θ + 2.35 × Q−0.08 × D + 34 ≦ 40 (1)
V: Casting speed of the slab (m / min)
Q: Flow rate of Ar gas to prevent nozzle clogging (N-liter / min)
θ: Immersion nozzle discharge angle (°)
D: Immersion nozzle immersion depth (mm)
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view showing a main part of a continuous casting facility to which the present invention is applied. The tundish 1 is provided with a tundish nozzle 4 for supplying the molten steel 2 into the mold 8. In order to prevent the molten steel 2 from being oxidized by air when the molten steel 2 is supplied from the tundish 1 into the mold 8 via the tundish nozzle 4, an immersion nozzle 5 is connected to the tundish nozzle 4. The The immersion nozzle 5 is used in a state in which the discharge port 6 disposed at the tip is immersed in the molten steel 2 in the mold 8. In the present invention, a two-hole nozzle is used as the immersion nozzle 5.
[0013]
The molten steel 2 in the tundish 1 is supplied from the discharge port 6 into the mold 8 through the tundish nozzle 4 and the immersion nozzle 5. The molten steel 2 injected into the mold 8 is cooled by the mold 8 to form a solidified shell 9. Mold powder 7 is put on the bath surface of the molten steel 2 in the mold 8 for the purpose of lubricating the mold 8 and the solidified shell 9, keeping the molten steel 2 warm, preventing oxidation of the molten steel 2 bath surface, and the like.
[0014]
In order to prevent clogging of the tundish nozzle 4, Ar gas 3 is blown into the molten steel 2. In the present invention, the method of blowing Ar gas 3 into the molten steel 2 is not limited to a specific method. A conventionally known method may be used. For example, a method using a porous nozzle as the tundish nozzle 4, a method using a gas sleeve nozzle, or a method using a gas blowing stopper may be used. good.
[0015]
After the molten steel 2 supplied into the mold 8 from the discharge port 6 of the immersion nozzle 5 is discharged in the direction of the arrow a, it strikes the short side of the mold 8 and flows downward (that is, in the direction of the arrow b) and upward (that is, in the direction of the arrow). c)). The flow indicated by the arrow c is a meniscus flow.
As a defect of a slab produced by continuous casting, inclusions such as Al 2 O 3 , entrainment of mold powder, or blow holes are frequently generated. Among these defects, inclusions and blowholes tend to occur when the meniscus flow rate is low. On the other hand, entrainment of mold powder is likely to occur when the meniscus flow rate is high.
[0016]
The flow velocity of the meniscus is as follows: casting speed V (m / min), Ar gas flow rate Q (N-liter / min) for nozzle clogging prevention, immersion nozzle discharge angle θ (°), and immersion nozzle immersion depth D Varies according to (mm). Here, the discharge angle θ (°) of the immersion nozzle refers to the angle formed by the direction of the arrow a where the molten steel 2 is discharged from the discharge port 6 and the horizontal direction, and the immersion depth D (mm) of the immersion nozzle is: The depth from the bath surface of the molten steel 2 in the mold 8 to the center of the opening of the discharge port 6 is indicated.
[0017]
Therefore, as a result of analyzing a lot of data obtained in the continuous casting operation, the casting speed V (m / min), which is the factor that fluctuates the flow velocity of the meniscus flow, and the flow rate Q of the Ar gas for preventing nozzle clogging (N-liter) / Min), the discharge angle θ (°) of the immersion nozzle, and the immersion depth D (mm) of the immersion nozzle, it was found that the occurrence of defects in the slab also changes.
[0018]
It was also found that the occurrence of defects in the slab has a correlation with the value of the index α calculated by the following equation (2).
Index α = 18 × V−4.9 × θ + 2.35 × Q−0.08 × D + 34 (2)
V: Casting speed of the slab (m / min)
Q: Flow rate of Ar gas to prevent nozzle clogging (N-liter / min)
θ: Immersion nozzle discharge angle (°)
D: Immersion nozzle immersion depth (mm)
That is, a slab produced by continuous casting was hot-rolled and further cold-rolled to produce a cold-rolled coil. Visually inspect the surface defects of the cold rolled coil, scale and sliver, calculate the defect contamination rate (%) in the coil, and the relationship with the value of the index α calculated by the above equation (2) investigated. The defect mixing ratio (%) in the coil is a value calculated by the following equation (3).
[0019]
Defect contamination rate in coil (%)
= 100 x (ΣL D / L C ) (3)
L D : Defect length of surface defects (m)
L C : Length of the entire coil (m)
FIG. 2 shows the relationship between the value of the index α calculated by the equation (2) and the defect incorporation rate (%) in the coil calculated by the equation (3). As is clear from FIG. 2, the inclusion rate of defects in the coil is extremely low when the index α value is in the range of 0 to 40, but in the range where the index α value is less than 0 and exceeds 40, the inclusion of defects in the coil. The rate goes up. That is, in order to suppress the surface defects and internal defects of the slab, the index α value needs to satisfy the range of 0-40. That is, it is necessary to satisfy the range of the formula (1).
[0020]
【Example】
After melting 1500 tons of ultra-low carbon steel having the components shown in Table 1, continuous casting was performed using the apparatus shown in FIG. The casting speed V for continuous casting is 1.5 to 2.2 m / min, the flow rate Q of Ar gas for nozzle clogging prevention is 5 to 40 N-liter / min, the discharge angle θ of the immersion nozzle is 15 °, and the immersion depth D of the immersion nozzle The slab dimensions were 220mm thick and 1000-1600mm wide. The value of the index α calculated by the equation (2) was 0 to 40, which satisfied the range of the equation (1). Mold powder was put into the bath surface of the molten steel in the mold. The slab obtained by continuous casting was hot-rolled and further cold-rolled to produce a cold-rolled coil. This is an invention example.
[0021]
[Table 1]
[0022]
In addition, after melting 1500t of ultra low carbon steel with the components shown in Table 1, the casting speed V is set to 1.5 to 2.2 m / min, the moving magnetic field is applied to the meniscus flow, and the flow velocity of the meniscus flow is set to 30 to 40 cm / sec. As a result, continuous casting was performed. The dimensions of the slab were 220mm thick and 1000-1600mm wide. It should be noted that in this case, the value of the index α is calculated by the equation (2), was shall out of the range of the equation (1). Mold powder was put into the bath surface of the molten steel in the mold. The slab obtained by continuous casting was hot-rolled and further cold-rolled to produce a cold-rolled coil. This is a comparative example.
[0023]
For the cold rolled coils of the inventive example and the comparative example, the failure rate due to surface defects and internal defects was compared, and the failure rate of the inventive example was about 1/5 that of the comparative example.
[0024]
【Effect of the invention】
In this invention, when performing continuous casting of steel using a 2 hole nozzle as an immersion nozzle, the surface defect and internal defect of a slab can be suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a continuous casting facility to which the present invention is applied.
FIG. 2 is a graph showing a relationship between an index α value and a defect mixing rate in a coil.
[Explanation of symbols]
1 Tundish 2 Molten steel 3 Ar gas 4 Tundish nozzle 5 Immersion nozzle (2-hole nozzle)
6 Discharge port 7 Mold powder 8 Mold 9 Solidified shell

Claims (1)

浸漬ノズルとして2孔ノズルを用いる鋼の連続鋳造方法において、鋳片の鋳込速度Vが 0.5〜3.0 m/min の範囲を満足し、ノズル詰まり防止用Arガスの流量Qが3〜50N-liter/min の範囲を満足し、浸漬ノズルの吐出角θが0〜45°の範囲を満足し、浸漬ノズルの浸漬深さDが30〜400mm の範囲を満足し、かつ前記鋳込速度V(m/min )、前記Arガス流量Q(N-liter/min )、前記吐出角θ(°)および前記浸漬深さD(mm)が下記の (1)式を満足することを特徴とする鋼の連続鋳造方法。
0≦18×V− 4.9×θ+2.35×Q−0.08×D+34≦40 ・・・ (1)
V:鋳片の鋳込速度(m/min )
Q:ノズル詰まり防止用Arガスの流量(N-liter/min )
θ:浸漬ノズルの吐出角(°)
D:浸漬ノズルの浸漬深さ(mm)
In a continuous steel casting method using a two-hole nozzle as an immersion nozzle, the casting speed V of the slab satisfies the range of 0.5 to 3.0 m / min, and the flow rate Q of Ar gas for preventing nozzle clogging is 3 to 50 N-liter. / Min, the submerged nozzle discharge angle θ satisfies the range of 0 to 45 °, the submerged nozzle immersion depth D satisfies the range of 30 to 400 mm, and the casting speed V (m / Min), the Ar gas flow rate Q (N-liter / min), the discharge angle θ (°) and the immersion depth D (mm) satisfy the following formula (1): Continuous casting method.
0 ≦ 18 × V−4.9 × θ + 2.35 × Q−0.08 × D + 34 ≦ 40 (1)
V: Casting speed of the slab (m / min)
Q: Flow rate of Ar gas to prevent nozzle clogging (N-liter / min)
θ: Immersion nozzle discharge angle (°)
D: Immersion nozzle immersion depth (mm)
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JP4591156B2 (en) * 2005-03-31 2010-12-01 Jfeスチール株式会社 Steel continuous casting method
CN112643007B (en) * 2020-11-23 2022-05-20 首钢集团有限公司 Continuous casting method for reducing large-size impurities on surface layer of aluminum-containing steel casting blank

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