JP4746398B2 - Steel continuous casting method - Google Patents
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Description
本発明は、内部品質に優れた鋳片を安定して製造するための鋼の連続鋳造方法に関するものである。 The present invention relates to a steel continuous casting method for stably producing a slab having excellent internal quality.
浸漬ノズルからの溶鋼の吐出流を安定させて良好な内部品質を有する鋳片を製造するために、従来から電磁ブレーキを用いた種々の技術が開発されている。特許文献1には、浸漬ノズルの吐出孔角度を−28°〜−32°としてシールガスを供給し、このシールガスと静磁場の電磁ブレーキの作用によって介在物の浮上促進等を行い、品質を向上させる技術が開示されている。特許文献2には、浸漬ノズルからの溶鋼吐出角度を下向き50°以上として溶鋼を注入するとともに、浸漬ノズル吐出口より下に極芯を位置させた静磁場発生装置を設けて静磁場を作用させる技術が開示されている。特許文献3には、連続鋳造鋳型の対向側壁の背面に配設した磁極にて静磁界を発生させ、これにより浸漬ノズルから該鋳型内に供給される溶鋼の噴流に対して制動を加える技術が開示されている。 Conventionally, various techniques using an electromagnetic brake have been developed in order to produce a cast slab having good internal quality by stabilizing the discharge flow of molten steel from an immersion nozzle. In Patent Document 1, a seal gas is supplied by setting the discharge hole angle of the immersion nozzle to −28 ° to −32 °, and the floating of the inclusion is promoted by the action of the electromagnetic brake of the seal gas and the static magnetic field. Techniques for improving are disclosed. In Patent Document 2, molten steel is injected with the discharge angle of molten steel from the immersion nozzle set to 50 ° or more downward, and a static magnetic field generating device having a pole core positioned below the discharge nozzle discharge port is provided to act on the static magnetic field. Technology is disclosed. Patent Document 3 discloses a technique in which a static magnetic field is generated by a magnetic pole disposed on the back surface of an opposing side wall of a continuous casting mold, and thereby a brake is applied to a jet of molten steel supplied into the mold from an immersion nozzle. It is disclosed.
また、特許文献4には、鋳型の長辺側メニスカス近傍に電磁攪拌装置を対向して設置するとともにその下方に電磁ブレーキを設置し、電磁攪拌装置によって鋳型内の溶鋼に幅方向の電磁攪拌流を付与するとともに、磁束密度が電磁攪拌装置の最大磁束密度の50%以下である位置に浸漬ノズルの吐出口を設置して、浸漬ノズルからの吐出流に電磁的にブレーキをかけて鋳造する連続鋳造方法が開示されている。しかしながら、当該開示に係る方法においては、浸漬ノズルの吐出口の位置が電磁ブレーキの磁束密度の低い箇所に配置されるような場合があって、吐出流に効果的にブレーキをかけることができないことがあった。このような場合には、非金属介在物が巻き込まれて効果的に浮上分離させることができず、圧延後の鋼板に内部欠陥が発生してプレス成形時などにおける割れの起点となってしまう。したがって、浸漬ノズルからの吐出流が磁束密度が十分高い範囲内にあるように電磁ブレーキを最適に配置する必要がある。
本発明は、上記したような従来の問題点を解決し、浸漬ノズルからの吐出流に効果的に電磁ブレーキをかけて、内部品質に優れた鋳片を製造するための鋼の連続鋳造方法を提供することを課題とする。 The present invention solves the conventional problems as described above, effectively applies an electromagnetic brake to the discharge flow from the immersion nozzle, and produces a continuous casting method of steel for producing a slab excellent in internal quality. The issue is to provide.
上記の課題を解決するためになされた本発明の鋼の連続鋳造方法は、
連続鋳造設備における断面が長方形の鋳型の長辺側メニスカス近傍に電磁攪拌装置を対向して設置したうえに、その下方で鋳型の範囲内に、浸漬ノズルの吐出孔から吐出流が鋳型壁に衝突するまでの領域が最大磁束密度の50%以上となるようにして、電磁ブレーキを設置して、前記電磁攪拌装置によって鋳型内の溶鋼に巾方向の電磁攪拌流を付与するとともに、鋳型壁に衝突する前の浸漬ノズルからの吐出流を前記電磁ブレーキにより形成される静磁場に導入してその流速を抑えながら鋳造することを特徴とするものである。
The continuous casting method of the steel of the present invention made to solve the above problems is as follows.
In a continuous casting facility, an electromagnetic stirrer is placed opposite the long side meniscus of the mold with a rectangular cross section , and the discharge flow collides with the mold wall from the discharge hole of the immersion nozzle below the mold. The electromagnetic brake is installed so that the area until the magnetic flux density is 50% or more of the maximum magnetic flux density, and the electromagnetic stirring flow in the width direction is applied to the molten steel in the mold by the electromagnetic stirring device, and the mold wall collides. Casting is carried out while introducing the discharge flow from the submerged nozzle before the introduction into the static magnetic field formed by the electromagnetic brake and suppressing the flow rate.
本発明は、鋳型の横巾、浸漬ノズルの浸漬深さ、浸漬ノズルの溶鋼吐出角に対応して、磁束密度が電磁ブレーキの最大磁束密度の50%以上である静磁場の範囲を設定して、電磁ブレーキを配置するので、浸漬ノズルからの吐出流を常に高い磁束密度の範囲内に存在させることができる。よって、浸漬ノズルから吐出する溶鋼に効果的にブレーキをかけて内部性状に優れた鋳片を製造することができる。 The present invention sets the range of the static magnetic field in which the magnetic flux density is 50% or more of the maximum magnetic flux density of the electromagnetic brake, corresponding to the width of the mold, the immersion depth of the immersion nozzle, and the molten steel discharge angle of the immersion nozzle. Since the electromagnetic brake is arranged, the discharge flow from the immersion nozzle can always exist within the range of the high magnetic flux density. Therefore, the slab excellent in internal property can be manufactured by effectively braking the molten steel discharged from the immersion nozzle.
以下に本発明を図面に基づき説明する。
図1は本発明を実施するための連続鋳造設備の鋳型近傍の構成図であって、鋳型の長辺方向からみた構造を示す。図において、1は断面が長方形の鋳片を鋳込むための鋳型、2は浸漬ノズル、3は電磁攪拌装置、4は電磁ブレーキである。
The present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of the vicinity of a mold of a continuous casting facility for carrying out the present invention, and shows a structure viewed from the long side direction of the mold. In the figure, 1 is a mold for casting a slab having a rectangular cross section, 2 is an immersion nozzle, 3 is an electromagnetic stirring device, and 4 is an electromagnetic brake.
図示の鋳型1は短辺側のものであって、この鋳型1内には下端に斜め下向きの二つの吐出孔5を有する浸漬ノズル2が高さ調整自在に配置されている。また、電磁攪拌装置3は、鋳型1の長辺側メニスカス近傍に一対が対向して配置されており、この電磁攪拌装置4による電磁攪拌で鋳型1内の溶鋼に鋳片横巾方向の電磁攪拌流6を形成する。浸漬ノズル2の吐出口5は、電磁攪拌装置3の下方で、電磁攪拌装置3の磁束密度がその最大磁束密度の50%以下となる低磁束密度の領域に配置されている。このように位置させることによって、電磁攪拌流6と、浸漬ノズル2からの吐出流7の衝突を回避して湯面を安定させることができる。 The illustrated mold 1 is on the short side, and an immersion nozzle 2 having two discharge holes 5 obliquely downward at the lower end is disposed in the mold 1 so as to be adjustable in height. In addition, the electromagnetic stirrer 3 is disposed in the vicinity of the long side meniscus of the mold 1 so as to face each other, and electromagnetic stir by the electromagnetic stirrer 4 in the molten steel in the mold 1 in the width direction of the slab. Stream 6 is formed. The discharge port 5 of the immersion nozzle 2 is disposed below the electromagnetic stirring device 3 in a low magnetic flux density region in which the magnetic flux density of the electromagnetic stirring device 3 is 50% or less of the maximum magnetic flux density. By positioning in this way, collision of the electromagnetic stirring flow 6 and the discharge flow 7 from the immersion nozzle 2 can be avoided, and the molten metal surface can be stabilized.
浸漬ノズル2の吐出口5近傍には電磁ブレーキ4が配置されている。電磁ブレーキ4の設置位置は、浸漬ノズル2の浸漬深さl、浸漬ノズル2の溶鋼吐出角度θ、鋳型1の横巾Wとの間で下式の関係を満たす位置に設置する必要がある。
電磁ブレーキ4を設置するに当って、L−α≦lとするのは、L−αがlより大きいと吐出孔5の位置が上方50%Bmax位置の上方となって、50%Bmaxの範囲内に吐出孔5を位置させることができないからである。
一方、L+α≧l+(W/2)tanθとするのは、L+αがl+(W/2)tanθより小さいと溶鋼が下方50%Bmaxの範囲を外れて吐出することになり、吐出流7に効果的にブレーキをかけることができないからである。即ち、(W/2)tanθは浸漬ノズル2からの吐出流7が鋳型壁に衝突するまでの、吐出孔5からの垂直方向の距離であって、L+αがl+(W/2)tanθより小さい場合には、吐出流7が鋳型壁に衝突してしまって、アルミナなどの非金属介在物が凝固シェルに捕捉されたりして浮上分離することができないからである。したがって、電磁ブレーキ4を、(1)、(2)式を満たすように設置する必要がある。
When installing the electromagnetic brake 4, L−α ≦ l is set so that when L−α is larger than l, the position of the discharge hole 5 is above the upper 50% Bmax position, and the range is 50% Bmax. This is because the discharge hole 5 cannot be positioned inside.
On the other hand, when L + α ≧ l + (W / 2) tan θ, when L + α is smaller than 1+ (W / 2) tan θ, the molten steel will be discharged out of the range of 50% Bmax below, which is effective for the discharge flow 7. This is because the brake cannot be applied. That is, (W / 2) tan θ is a vertical distance from the discharge hole 5 until the discharge flow 7 from the immersion nozzle 2 collides with the mold wall, and L + α is smaller than l + (W / 2) tan θ. In this case, the discharge flow 7 collides with the mold wall and non-metallic inclusions such as alumina cannot be levitated and separated by being trapped by the solidified shell. Therefore, it is necessary to install the electromagnetic brake 4 so as to satisfy the expressions (1) and (2).
以上のように、電磁ブレーキ4を配置することによって、浸漬ノズル2の吐出孔5から、吐出流7が鋳型壁に衝突するまでの領域を50%Bmax以上の高磁束密度の領域とすることができるので、吐出流7に確実に電磁ブレーキをかけることができる。 As described above, by arranging the electromagnetic brake 4, the region from the discharge hole 5 of the immersion nozzle 2 until the discharge flow 7 collides with the mold wall can be a region having a high magnetic flux density of 50% Bmax or more. Therefore, the electromagnetic brake can be reliably applied to the discharge flow 7.
以下、実施例に基づき本発明を詳細に説明する。
極低炭素鋼の溶鋼300トンを転炉−RH工程にて溶製した。タンディッシュ内の溶鋼温度を1560〜1580℃として浸漬ノズル2から鋳型内に溶鋼を注入し、厚さ250mm、幅900〜1600mmの鋳片を鋳造速度1.6〜2.5m/minで製造した。鋳造に当っては溶鋼を電磁攪拌装置3で水平方向に旋回させつつ、その下方に電磁ブレーキ4を設置して浸漬ノズル2からの吐出流7にブレーキをかけながら鋳造した。引き続いて鋳片を通常の方法で熱延、酸洗、冷延、焼鈍して0.7〜1.2mmの冷延鋼板として、内部性状を調査した。試験結果を表1に示す。
Hereinafter, the present invention will be described in detail based on examples.
300 tons of extremely low carbon steel was melted in the converter-RH process. The molten steel temperature in the tundish was set to 1560 to 1580 ° C., and molten steel was injected into the mold from the immersion nozzle 2 to produce a slab having a thickness of 250 mm and a width of 900 to 1600 mm at a casting speed of 1.6 to 2.5 m / min. . In casting, the molten steel was swung in the horizontal direction with the electromagnetic stirring device 3, and the electromagnetic brake 4 was installed below the molten steel, and the discharge flow 7 from the immersion nozzle 2 was braked while casting. Subsequently, the slab was hot-rolled, pickled, cold-rolled, and annealed by a usual method to examine the internal properties as a cold-rolled steel sheet of 0.7 to 1.2 mm. The test results are shown in Table 1.
比較例1、2のものは、電磁ブレーキ4の設置が不適切で、L-αが浸漬ノズル2の浸漬深さlより大きく、且つL+αがl+(W/2)tanθより小さい。即ち、浸漬ノズルの吐出孔5の位置が上方50%Bmax位置の上方であるうえに、下方50%Bmaxの範囲を外れて吐出流が流動してしまい吐出流に有効にブレーキをかけることができなかった。このため、非金属介在物を効果的に浮上させることができず鋼板に内部欠陥が発生した。 In Comparative Examples 1 and 2, installation of the electromagnetic brake 4 is inappropriate, L-α is larger than the immersion depth l of the immersion nozzle 2, and L + α is smaller than l + (W / 2) tan θ. That is, the position of the discharge hole 5 of the immersion nozzle is above the upper 50% Bmax position, and the discharge flow flows out of the lower 50% Bmax range, so that the discharge flow can be effectively braked. There wasn't. For this reason, nonmetallic inclusions could not be effectively levitated, and internal defects occurred in the steel sheet.
また、比較例3、4のものはL−αはlより小さいが、L+αがl+(W/2)tanθより小さい。このため、吐出流が鋳型壁の凝固シェルに衝突して非金属介在物を効果的に浮上させることができずやはり内部性状に劣るものであった。 In Comparative Examples 3 and 4, L-α is smaller than l, but L + α is smaller than l + (W / 2) tan θ. For this reason, the discharge flow collides with the solidified shell of the mold wall and the non-metallic inclusions cannot be effectively levitated, and the internal properties are also inferior.
以上のような比較例に対して実施例1〜4のものは、何れもL-αが浸漬ノズル2の浸漬深さlより小さく、且つL+αがl+(W/2)tanθより大きい。即ち溶鋼を50%Bmaxより大きい領域で吐出させることができ、且つ、吐出流を鋳型壁の凝固シェルに衝突させることなく有効にブレーキをかけることができた。この結果、非金属介在物を効果的に浮上させることができて内部欠陥の発生がない鋼板を得ることができた。 In each of Examples 1 to 4 as compared with the above comparative example, L-α is smaller than the immersion depth l of the immersion nozzle 2 and L + α is larger than l + (W / 2) tan θ. That is, the molten steel could be discharged in a region larger than 50% Bmax, and the brake could be effectively applied without causing the discharge flow to collide with the solidified shell of the mold wall. As a result, a non-metallic inclusion can be effectively levitated and a steel plate free from internal defects can be obtained.
1 鋳型、2 浸漬ノズル、3 電磁攪拌装置、4 電磁ブレーキ 1 mold, 2 immersion nozzle, 3 electromagnetic stirrer, 4 electromagnetic brake
Claims (1)
In a continuous casting facility, an electromagnetic stirrer is placed opposite the long side meniscus of the mold with a rectangular cross section , and the discharge flow collides with the mold wall from the discharge hole of the immersion nozzle below the mold. The electromagnetic brake is installed so that the area until the magnetic flux density is 50% or more of the maximum magnetic flux density, and the electromagnetic stirring flow in the width direction is applied to the molten steel in the mold by the electromagnetic stirring device, and the mold wall collides. A continuous casting method for steel, characterized by introducing a discharge flow from an immersion nozzle before casting into a static magnetic field formed by the electromagnetic brake and performing casting while suppressing the flow rate.
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JP5047742B2 (en) * | 2007-09-13 | 2012-10-10 | 新日本製鐵株式会社 | Steel continuous casting method and continuous casting apparatus |
JP5014934B2 (en) * | 2007-09-13 | 2012-08-29 | 新日本製鐵株式会社 | Steel continuous casting method |
KR101505160B1 (en) | 2013-04-30 | 2015-03-23 | 현대제철 주식회사 | Method for sorting steel product |
BR112017013367A2 (en) | 2015-03-31 | 2018-01-09 | Nippon Steel & Sumitomo Metal Corporation | continuous casting method for steel |
KR102324300B1 (en) * | 2017-04-25 | 2021-11-09 | 제이에프이 스틸 가부시키가이샤 | Method of continuous casting of steel |
BR112020013272A2 (en) * | 2018-02-26 | 2020-12-01 | Nippon Steel Corporation | molding installation |
JP7389339B2 (en) | 2020-01-09 | 2023-11-30 | 日本製鉄株式会社 | electromagnetic stirring device |
JP7385116B2 (en) | 2020-01-09 | 2023-11-22 | 日本製鉄株式会社 | electromagnetic stirring device |
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JPH11285786A (en) * | 1998-03-31 | 1999-10-19 | Nippon Steel Corp | Production of sequentially continuous cast slab excellent in quality in joint part |
JPH11300454A (en) * | 1998-04-16 | 1999-11-02 | Nippon Steel Corp | Production of continuously casting slab excellent in cleanliness |
JP2000015404A (en) * | 1998-07-02 | 2000-01-18 | Nippon Steel Corp | Production of continuously cast slab having little inclusion defect |
JP2001047195A (en) * | 1999-08-12 | 2001-02-20 | Nippon Steel Corp | Continuous casting method |
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JPH11285786A (en) * | 1998-03-31 | 1999-10-19 | Nippon Steel Corp | Production of sequentially continuous cast slab excellent in quality in joint part |
JPH11300454A (en) * | 1998-04-16 | 1999-11-02 | Nippon Steel Corp | Production of continuously casting slab excellent in cleanliness |
JP2000015404A (en) * | 1998-07-02 | 2000-01-18 | Nippon Steel Corp | Production of continuously cast slab having little inclusion defect |
JP2001047195A (en) * | 1999-08-12 | 2001-02-20 | Nippon Steel Corp | Continuous casting method |
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