JP7099129B2 - Carbon steel thin-walled slab manufacturing equipment, carbon steel thin-walled slab manufacturing method - Google Patents

Carbon steel thin-walled slab manufacturing equipment, carbon steel thin-walled slab manufacturing method Download PDF

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JP7099129B2
JP7099129B2 JP2018140895A JP2018140895A JP7099129B2 JP 7099129 B2 JP7099129 B2 JP 7099129B2 JP 2018140895 A JP2018140895 A JP 2018140895A JP 2018140895 A JP2018140895 A JP 2018140895A JP 7099129 B2 JP7099129 B2 JP 7099129B2
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武政 村尾
隆 諸星
雅文 宮嵜
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Nippon Steel Corp
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本発明は、炭素鋼薄肉鋳片の製造装置、炭素鋼薄肉鋳片の製造方法及び炭素鋼薄肉鋳片に関するものである。 The present invention relates to a carbon steel thin-walled slab manufacturing apparatus, a carbon steel thin-walled slab manufacturing method, and a carbon steel thin-walled slab.

省工程・省エネルギーの観点から、最終品に近い薄板を鋳造段階で製造する技術、すなわちニア・ネット・シェイプ連続鋳造の開発が行われている。このうち、薄板系のニア・ネット・シェイプ連続鋳造として有力なものとして、双ロール(双ドラムともいう)式連続鋳造方法が特許文献1に開示されている。双ロール式連続鋳造装置を用いた薄肉鋳片の連続鋳造においては、図3に示すように互いに逆方向に回転する一対の鋳造ロール1により区画された溶鋼プール10に、溶鋼を浸漬ノズル2の吐出孔3から供給することにより薄肉鋳片13を鋳造するようになっている。 From the viewpoint of process saving and energy saving, a technique for manufacturing a thin plate close to the final product at the casting stage, that is, near net shape continuous casting is being developed. Of these, Patent Document 1 discloses a double-roll (also referred to as double-drum) type continuous casting method as a promising thin plate-based near-net shape continuous casting. In continuous casting of thin-walled slabs using a twin-roll continuous casting device, molten steel is immersed in a molten steel pool 10 partitioned by a pair of casting rolls 1 rotating in opposite directions as shown in FIG. The thin-walled slab 13 is cast by supplying it from the discharge hole 3.

双ロール式連続鋳造法で鋳造した低炭素鋼薄肉鋳片の凝固組織は、鋳片内部まで真っ直ぐに成長した柱状晶からなっている。凝固組織の形態は溶鋼中のC濃度と凝固時の固液界面の温度勾配に強く影響され、低炭素鋼のようにC濃度が0.1質量%以下で、双ロール鋳造のように温度勾配が大きくなると、柱状晶が極めて成長し易くなる。双ロール式連続鋳造法で製造された数mm厚の薄肉鋳片は、最終板厚まで冷間圧延されるが、従来の250mm厚程度で鋳造される連続鋳造鋳片とは異なり圧下率を大きく確保できない。その結果、凝固組織成長の方向性が最終薄鋼板にも残留し、加工時に異方性として現れ、例えば製缶時に深絞り加工を施すと缶の円周方向に山部と谷部が交互に続く、いわゆるイヤリングが発生する。このイヤリングが大きいと製缶の歩留まりが低下すると共に、イヤリング部が金型に接触し製缶トラブルにつながるため、双ロール式連続鋳造法で得た薄鋼板は高い成形性・加工性を要求される用途には適用できていないのが現状である。 The solidification structure of low-carbon steel thin-walled slabs cast by the double-roll continuous casting method consists of columnar crystals that grow straight up to the inside of the slabs. The morphology of the solidified structure is strongly influenced by the C concentration in the molten steel and the temperature gradient of the solid-liquid interface during solidification. The larger the value, the easier it is for columnar crystals to grow. Thin-walled slabs with a thickness of several mm manufactured by the double-roll continuous casting method are cold-rolled to the final plate thickness, but unlike the conventional continuous-cast slabs cast with a thickness of about 250 mm, the rolling reduction is large. Cannot be secured. As a result, the direction of solidification structure growth remains on the final thin steel sheet and appears as anisotropy during processing. For example, when deep drawing is performed during can manufacturing, peaks and valleys alternate in the circumferential direction of the can. Then, so-called earrings occur. If these earrings are large, the yield of cans will decrease, and the earrings will come into contact with the mold, leading to can making troubles. At present, it cannot be applied to various applications.

双ロール式連続鋳造法で製造した薄鋼板で異方性が生じるのは、低炭素溶鋼を急冷凝固させることにより発達した柱状晶組織に起因する。この異方性の発現機構に基づけば、低炭素鋼の凝固組織を等軸晶化することが異方性の低減に有効である。 The anisotropy of the thin steel sheet manufactured by the double-roll continuous casting method is due to the columnar crystal structure developed by quenching and solidifying the low-carbon molten steel. Based on this anisotropy expression mechanism, equiaxed crystallization of the solidified structure of low carbon steel is effective in reducing anisotropy.

双ロール式連続鋳造法で鋳造する鋼種によっては、何ら対策を施さずとも等軸晶組織を得やすい鋼種もあるが、積極的に制御せずに生成する等軸晶は粗大であり、たとえ等軸晶が生成したとしても中心偏析やポロシティが発生しやすい。 Depending on the steel type cast by the twin-roll continuous casting method, it is easy to obtain an equiaxed crystal structure without any measures, but the equiaxed crystals generated without positive control are coarse, even if Even if axial crystals are generated, central segregation and porosity are likely to occur.

双ロール式連続鋳造法における等軸晶化の方法は主に、接種の効果によるものが報告されている。特許文献2には、低炭素溶鋼中にMgを添加して少なくともアルミナ介在物やチタニア介在物の表層部をマグネシアまたはアルミナマグネシアスピネルに改質し、それらの介在物を等軸晶生成の核として活用することにより双ロール式連続鋳造法で凝固組織を等軸晶化する方法が開示されている。また特許文献3には、マルテンサイト系ステンレス鋼を双ロール式薄板鋳造工程により製造するに際し、Ti添加により等軸晶化を図る方法が開示されている。 It has been reported that the method of equiaxed crystallization in the bi-roll continuous casting method is mainly due to the effect of inoculation. In Patent Document 2, Mg is added to low carbon molten steel to modify at least the surface layer of alumina inclusions and titania inclusions into magnesia or alumina magnesia spinel, and these inclusions are used as nuclei for equiaxed crystal formation. A method of equiaxed crystallization of a solidified structure by a twin-roll continuous casting method is disclosed by utilizing it. Further, Patent Document 3 discloses a method for achieving equiaxed crystallization by adding Ti when producing martensitic stainless steel by a double-roll type thin plate casting process.

特許文献4には、連続鋳造の鋳型内において金属の凝固面に超音波を印加するための振動子を備えた連続鋳造装置が開示されている。超音波によって凝固面のデンドライトを微細化するためのものである。振動子は、超音波の発信部と浸漬部とを有し、浸漬部の先端は、凝固面から20mm以内の位置に配置されている。また特許文献5には、鋳造中、鋳型銅板に超音波振動を鋳型内面から付与して初期凝固シェルへの介在物、気泡の付着を防止する、金属の連続鋳造方法が開示されている。 Patent Document 4 discloses a continuous casting apparatus including a vibrator for applying ultrasonic waves to a solidified surface of a metal in a continuous casting mold. The purpose is to miniaturize the dendrites on the solidified surface by ultrasonic waves. The vibrator has an ultrasonic wave transmitting portion and a dipping portion, and the tip of the dipping portion is arranged at a position within 20 mm from the solidification surface. Further, Patent Document 5 discloses a continuous metal casting method in which ultrasonic vibration is applied to a mold copper plate from the inner surface of a mold during casting to prevent inclusions and bubbles from adhering to the initial solidification shell.

非特許文献1には、Al-Si合金の鋳型内凝固時に超音波振動を付加することにより、凝固結晶を微細粒状化できることが開示されている。非特許文献2には、Al-Si溶湯をノズルから流出させて鋳型内で凝固するに際し、ノズルの溶湯吸引部直上に超音波ホーンを配置してキャビテーションを発生させることにより、初晶Si粒子の微細化が達成できることが記載されている。特許文献3には、鋳型内での鋳鉄の凝固に際して超音波振動を付加することにより、鋳鉄中の黒鉛が微細化することが記載されている。 Non-Patent Document 1 discloses that solidified crystals can be finely granulated by applying ultrasonic vibration during solidification in a mold of an Al—Si alloy. In Non-Patent Document 2, when the Al—Si molten metal flows out from the nozzle and solidifies in the mold, an ultrasonic horn is arranged directly above the molten metal suction portion of the nozzle to generate cavitation, thereby causing primary crystal Si particles. It is stated that miniaturization can be achieved. Patent Document 3 describes that graphite in cast iron becomes finer by applying ultrasonic vibration when solidifying cast iron in a mold.

特開昭60-137562号公報Japanese Unexamined Patent Publication No. 60-137562 特開2017-131933号公報Japanese Unexamined Patent Publication No. 2017-131933 特表2013-512347号公報Special Table 2013-512347 Gazette 特開2011-212737号公報Japanese Unexamined Patent Publication No. 2011-212737 特開2001-25846号公報Japanese Unexamined Patent Publication No. 2001-25846

「超音波振動による凝固組織の微細化」鋳造工学 第72巻(2000)第11号733~738頁"Miniaturization of solidified structure by ultrasonic vibration" Foundry Engineering Vol. 72 (2000) No. 11 pp. 733-738 「超音波鋳造におけるキャビテーション現象とその工業的利用」鉄と鋼 第102巻(2016)第3号75~81頁"Cavitation Phenomenon in Ultrasonic Casting and Its Industrial Use" Iron and Steel Vol. 102 (2016) No. 3, pp. 75-81 「鋳鉄の凝固他組織におよぼす超音波振動の影響」鋳物 第67巻(1995)第5号325~330頁"Effects of ultrasonic vibration on solidification of cast iron and other structures" Casting Vol. 67 (1995) No. 5, pp. 325-330

双ロール式連続鋳造法は図3に示すように、鋳造ロール1の表面に凝固シェル12が形成開始してから凝固が完了して薄肉鋳片13として引き出されるまでが極めて短時間であるため、溶融金属中に混在する介在物の浮上除去時間が確保できない。そのため、前記接種を行って等軸晶化を実現する方法においては、溶鋼の清浄性の悪化につながる懸念がある。接種法以外にも、低温鋳造及び低速鋳造方法も提案されているが、これらの方法は鋳造中にノズルが詰まって操業が不安定で生産性が低下する課題がある。 As shown in FIG. 3, in the double-roll continuous casting method, it takes an extremely short time from the start of formation of the solidification shell 12 on the surface of the casting roll 1 to the completion of solidification and the extraction as the thin-walled slab 13. It is not possible to secure the floating removal time of inclusions mixed in the molten metal. Therefore, in the method of performing the inoculation to realize equiaxed crystallization, there is a concern that the cleanliness of the molten steel may be deteriorated. In addition to the inoculation method, low-temperature casting and low-speed casting methods have also been proposed, but these methods have a problem that the nozzle is clogged during casting, the operation is unstable, and the productivity is lowered.

従来から、溶融金属の凝固時に超音波振動を付加することにより、凝固組織を微細化する技術が、前述のように知られている。しかし、非特許文献1~3に記載のものは、Al-Si金属の凝固に関するもの(非特許文献1、非特許文献2)、鋳鉄の凝固に関するもの(非特許文献3)であり、鋼の連続鋳造に関するものではない。また、特許文献4、5に記載のものは鋼の連続鋳造に関するものではあるが、特許文献4は凝固面の直近に超音波振動子の先端を配置するものであり、特許文献5は鋳型そのものに超音波を付与するものであり、いずれも、双ロール式連続鋳造法による炭素鋼薄肉鋳片の製造に適用できるものではなかった。 Conventionally, as described above, a technique for miniaturizing a solidified structure by applying ultrasonic vibration during solidification of a molten metal has been known. However, those described in Non-Patent Documents 1 to 3 relate to solidification of Al—Si metal (Non-Patent Document 1 and Non-Patent Document 2) and solidification of cast iron (Non-Patent Document 3), and are related to solidification of steel. It is not about continuous casting. Further, although those described in Patent Documents 4 and 5 relate to continuous casting of steel, Patent Document 4 arranges the tip of an ultrasonic transducer in the immediate vicinity of the solidification surface, and Patent Document 5 describes the mold itself. However, none of them can be applied to the production of carbon steel thin-walled slabs by the double-roll continuous casting method.

本発明は、双ロール式連続鋳造によって連続鋳造するに際し、以上の課題を解決するために、接種法以外の方法を用いることにより、薄肉鋳片に微細な等軸晶を十分に形成させ、操業を安定させ、清浄性を確保しつつ加工性・成形性に優れた微細等軸晶組織を得ることのできる、炭素鋼薄肉鋳片の製造装置、炭素鋼薄肉鋳片の製造方法及び炭素鋼薄肉鋳片を提供することを目的とする。 In the present invention, in order to solve the above problems in continuous casting by twin-roll type continuous casting, by using a method other than the inoculation method, fine equiaxed crystals are sufficiently formed in the thin-walled slab and operated. A carbon steel thin-walled slab manufacturing device, a carbon steel thin-walled slab manufacturing method, and a carbon steel thin-walled slab that can obtain a fine equiaxed crystal structure with excellent workability and formability while ensuring cleanliness. The purpose is to provide slabs.

即ち、本発明の要旨とするところは以下のとおりである。
(1)双ロールで囲まれた溶鋼プール中に浸漬ノズルから溶鋼を供給して鋳造を行う、双ロール式連続鋳造による炭素鋼薄肉鋳片の製造装置であって、
前記浸漬ノズルの側面の前記溶鋼プールに浸漬する位置に溶鋼の吐出孔を有し、
超音波振動子を有し、前記超音波振動子は超音波発信器と振動伝達部を有し、
前記超音波振動子を、平面視において、前記吐出孔と吐出孔両端から浸漬ノズル側面に垂直に引いた2本の直線との間の空間に配置するとともに、前記振動伝達部の加振先端部を、前記吐出孔の上端よりも上方に配置し、
前記振動伝達部の前記加振先端部は、前記溶鋼プールの溶鋼中に浸漬可能であることを特徴とする炭素鋼薄肉鋳片の製造装置。
That is, the gist of the present invention is as follows.
(1) An apparatus for producing thin-walled carbon steel slabs by double-roll continuous casting, in which molten steel is supplied from a dipping nozzle into a molten steel pool surrounded by twin rolls to perform casting.
A molten steel discharge hole is provided at a position on the side surface of the immersion nozzle to be immersed in the molten steel pool.
It has an ultrasonic oscillator, and the ultrasonic oscillator has an ultrasonic transmitter and a vibration transmission unit.
The ultrasonic vibrator is arranged in a space between the discharge hole and two straight lines drawn perpendicularly to the side surface of the immersion nozzle from both ends of the discharge hole in a plan view, and the vibration tip portion of the vibration transmission unit is provided. Is placed above the upper end of the discharge hole.
A carbon steel thin-walled slab manufacturing apparatus, wherein the vibration tip portion of the vibration transmission portion can be immersed in the molten steel of the molten steel pool.

(2)上記(1)に記載の炭素鋼薄肉鋳片の製造装置を用いた炭素鋼薄肉鋳片の製造方法であって、
双ロールで囲まれた溶鋼プール中に浸漬ノズルから溶鋼を供給し、前記振動伝達部の加振先端部を前記溶鋼プールの溶鋼中に浸漬させて溶鋼プール中の溶鋼に超音波振動を加え、炭素鋼薄肉鋳片を連続鋳造することを特徴とする炭素鋼薄肉鋳片の製造方法
(3)前記超音波振動子の超音波発信器により、周波数18~25kHz、振幅(p-p)14~50μmの超音波を発生させることを特徴とする上記(2)に記載の炭素鋼薄肉鋳片の製造方法。
(2) A method for manufacturing a carbon steel thin-walled slab using the carbon steel thin-walled slab manufacturing apparatus according to (1) above.
The molten steel is supplied from the immersion nozzle into the molten steel pool surrounded by the twin rolls, the vibration tip of the vibration transmission portion is immersed in the molten steel of the molten steel pool, and ultrasonic vibration is applied to the molten steel in the molten steel pool. A method for manufacturing a carbon steel thin-walled slab, which comprises continuously casting carbon steel thin-walled slabs .
(3) The carbon steel thin wall according to ( 2) above, wherein the ultrasonic transmitter of the ultrasonic transducer generates ultrasonic waves having a frequency of 18 to 25 kHz and an amplitude (pp) of 14 to 50 μm. Method of manufacturing slabs.

本発明は、双ロール式連続鋳造において、超音波発信器と振動伝達部を具備する超音波振動子を有し、振動伝達部の加振先端部を溶鋼プールの溶鋼中に浸漬して溶鋼に超音波振動を励起する。これにより、薄肉鋳片に微細な等軸晶を十分に形成させ、操業を安定させ、清浄性を確保しつつ加工性・成形性に優れた微細等軸晶組織を得ることができる。 The present invention has an ultrasonic oscillator provided with an ultrasonic transmitter and a vibration transmission unit in a twin-roll type continuous casting, and the vibration tip of the vibration transmission unit is immersed in the molten steel of the molten steel pool to form molten steel. Exciting ultrasonic vibrations. As a result, it is possible to sufficiently form fine equiaxed crystals on the thin-walled slab, stabilize the operation, and obtain a fine equiaxed crystal structure having excellent workability and moldability while ensuring cleanliness.

本発明の薄肉鋳片の製造装置の一例を示す図であり、(A)はA-A矢視側面断面図、(B)(C)は平面図である。It is a figure which shows an example of the manufacturing apparatus of the thin-walled slab of this invention, (A) is a side sectional view taken along the line AA, (B) (C) is a plan view. 本発明の薄肉鋳片の製造装置の一例を示す図であり、(A)はA-A矢視側面断面図、(B)は平面図である。It is a figure which shows an example of the manufacturing apparatus of the thin-walled slab of this invention, (A) is a side sectional view taken along the line AA, (B) is a plan view. 薄肉鋳片の製造装置の一例を示す図であり、(A)はA-A矢視側面断面図、(B)は平面図である。It is a figure which shows an example of the manufacturing apparatus of a thin-walled slab, (A) is a side sectional view taken along the line AA, (B) is a plan view.

本発明が対象とする双ロール式の鋼の連続鋳造においては、図3に示すように、1対の鋳造ロール1(鋳造ドラムともいう)とその両端に位置するサイド堰8で囲まれた領域に溶鋼を満たして溶鋼プール10とし、溶鋼プール10中に浸漬ノズル2から溶鋼を供給し、鋳造ロール表面に凝固シェル12を形成し、2本の鋳造ロール1を反対方向に回転させて、2本の鋳造ロール間の距離が最も狭い隙間部9から薄肉鋳片13が下方に引き出される。溶鋼は浸漬ノズル2から溶鋼プール10内に供給される。 In the continuous casting of double-roll type steel, which is the object of the present invention, as shown in FIG. 3, a region surrounded by a pair of casting rolls 1 (also referred to as a casting drum) and side dams 8 located at both ends thereof. The molten steel pool 10 is filled with molten steel, and the molten steel is supplied from the immersion nozzle 2 into the molten steel pool 10, a solidified shell 12 is formed on the surface of the casting roll, and the two casting rolls 1 are rotated in opposite directions. The thin-walled slab 13 is pulled downward from the gap 9 where the distance between the casting rolls of the book is the shortest. The molten steel is supplied into the molten steel pool 10 from the immersion nozzle 2.

図1(A)、図2(A)は、双ロール式連続鋳造の双ロール部の側面部分断面図であり、図1(B)(C)、図2(B)は平面図である。図1(B)(C)、図2(B)において、溶鋼プール表面31とその四周の溶鋼プールの縁32が記載されている。溶鋼プールの縁32は、溶鋼プール表面31と鋳造ロール1との境界、溶鋼プール表面31とサイド堰8との境界に位置している。 1 (A) and 2 (A) are side sectional views of a double roll portion of a double roll type continuous casting, and FIGS. 1 (B) and 2 (B) are plan views. In FIGS. 1 (B) and 1 (C) and FIG. 2 (B), the surface 31 of the molten steel pool and the edges 32 of the molten steel pool around the surface 31 are shown. The edge 32 of the molten steel pool is located at the boundary between the molten steel pool surface 31 and the casting roll 1 and the boundary between the molten steel pool surface 31 and the side weir 8.

浸漬ノズル2の側面20の溶鋼プール10に浸漬する位置に溶鋼の吐出孔3を有し、浸漬ノズル2に供給された溶鋼は、吐出孔3から溶鋼プール10中に吐出する。吐出孔3を有する浸漬ノズル2の側面20は、鋳造ロール1の回転軸に平行に配置される。吐出孔3から、当該側面20に垂直方向に吐出した溶鋼の吐出流14は、鋳造ロール1の側面に到達するとそこから鋳造ロール1の表面を駆け上がり、溶鋼プール表面31付近に到達すると溶鋼流11は左右(鋳造ロール1の軸方向)に流れ方向を変え、サイド堰8付近に到達すると反転する流路を形成する(図1(A)、図3(B)参照)。 A molten steel discharge hole 3 is provided at a position of being immersed in the molten steel pool 10 on the side surface 20 of the immersion nozzle 2, and the molten steel supplied to the immersion nozzle 2 is discharged from the discharge hole 3 into the molten steel pool 10. The side surface 20 of the immersion nozzle 2 having the discharge hole 3 is arranged parallel to the rotation axis of the casting roll 1. When the molten steel discharge flow 14 discharged from the discharge hole 3 in the direction perpendicular to the side surface 20 reaches the side surface of the casting roll 1, it runs up the surface of the casting roll 1 from there, and when it reaches the vicinity of the molten steel pool surface 31, the molten steel flow 11 changes the flow direction to the left and right (axial direction of the casting roll 1), and forms a flow path that reverses when reaching the vicinity of the side dam 8 (see FIGS. 1 (A) and 3 (B)).

本発明は、炭素鋼の薄肉鋳片を製造する製造装置を対象とする。鋳造対象として炭素鋼を対象とするのは、炭素鋼において微細等軸晶を安定的に生成させることは従来困難であり、本発明が大きな効果を発揮するからである。ここで炭素鋼とは、炭素を0.001%以上0.6%以下含有する鋼を意味する。特に炭素濃度が0.05質量%以下の低炭素鋼において、本発明は大きな効果を発揮する。 The present invention is intended for a manufacturing apparatus for manufacturing thin-walled slabs of carbon steel. The reason why carbon steel is targeted for casting is that it is conventionally difficult to stably generate fine equiaxed crystals in carbon steel, and the present invention exerts a great effect. Here, the carbon steel means a steel containing 0.001% or more and 0.6% or less of carbon. In particular, the present invention exerts a great effect on low carbon steel having a carbon concentration of 0.05% by mass or less.

本発明の炭素鋼薄肉鋳片の製造装置は、超音波振動子4を有する。超音波振動子4は超音波発信器5と振動伝達部6を有し、振動伝達部6の一方の端部が超音波発信器5に接続される。超音波発信器5にて超音波を発信し、発信した超音波は、超音波発信器5に接続された振動伝達部6内を伝搬して振動伝達部6の先端まで達する。超音波発信器5に接続される側の反対側における振動伝達部6の端部が加振先端部7となる。加振先端部7を溶鋼プール10の溶鋼中に浸漬することにより、加振先端部7の先の溶鋼中に超音波振動を励起することができる。 The carbon steel thin-walled slab manufacturing apparatus of the present invention has an ultrasonic vibrator 4. The ultrasonic vibrator 4 has an ultrasonic transmitter 5 and a vibration transmission unit 6, and one end of the vibration transmission unit 6 is connected to the ultrasonic transmitter 5. The ultrasonic wave is transmitted by the ultrasonic transmitter 5, and the transmitted ultrasonic wave propagates in the vibration transmission unit 6 connected to the ultrasonic transmitter 5 and reaches the tip of the vibration transmission unit 6. The end portion of the vibration transmission portion 6 on the opposite side to the side connected to the ultrasonic transmitter 5 is the vibration tip portion 7. By immersing the vibration tip portion 7 in the molten steel of the molten steel pool 10, ultrasonic vibration can be excited in the molten steel at the tip of the vibration tip portion 7.

上記本発明の炭素鋼薄肉鋳片の製造装置を用いた、炭素鋼薄肉鋳片の製造方法においては、2つの鋳造ロール1で囲まれた溶鋼プール10中に浸漬ノズル2から溶鋼を供給し、振動伝達部6の加振先端部7を溶鋼プール10の溶鋼中に浸漬させて、溶鋼プール10中の溶鋼に超音波振動を加える。 In the method for producing carbon steel thin-walled slabs using the carbon steel thin-walled slab manufacturing apparatus of the present invention, molten steel is supplied from a dipping nozzle 2 into a molten steel pool 10 surrounded by two casting rolls 1. The vibration tip portion 7 of the vibration transmission unit 6 is immersed in the molten steel of the molten steel pool 10, and ultrasonic vibration is applied to the molten steel in the molten steel pool 10.

振動伝達部6の加振先端部7を溶鋼プール10の溶鋼中に浸漬させて、溶鋼プール中の溶鋼に超音波振動を加えると、加振先端部付近の溶鋼中にキャビテーションが形成されることが知られている(非特許文献2参照)。超音波振動子によって生成するキャビテーションとは、液体に超音波振動を与えることで無数の気泡が発生し、ある条件で崩壊する現象である。 When the vibration tip portion 7 of the vibration transmission unit 6 is immersed in the molten steel of the molten steel pool 10 and ultrasonic vibration is applied to the molten steel in the molten steel pool, cavitation is formed in the molten steel near the vibration tip portion. Is known (see Non-Patent Document 2). Cavitation generated by an ultrasonic vibrator is a phenomenon in which innumerable bubbles are generated by applying ultrasonic vibration to a liquid and collapse under certain conditions.

溶鋼中にキャビテーションが発生すると、このキャビテーションによって溶鋼中に微細な等軸晶の核が形成する。発生した等軸晶の核を維持し、連続鋳造中の鋳片の厚み中心部に供給することができれば、これにより鋳片の厚み中心部に異方性の小さい等軸晶組織が生成し、鋼板の加工性・成形性を改善することが期待される。しかし、通常の連続鋳造において超音波振動を付与した場合、通常の連続鋳造では冷却速度が遅いため、超音波振動によるキャビテーションで等軸晶核が形成したとしても、その後、生成した等軸晶核が合体/成長するか、又は再溶解して消滅しやすいため、たとえ鋳型内で超音波振動を励起したとしても、鋳片の厚み中心部に微細な等軸晶部を形成することができなかった。 When cavitation occurs in the molten steel, this cavitation forms fine equiaxed nuclei in the molten steel. If the generated equiaxed crystal core can be maintained and supplied to the center of thickness of the slab during continuous casting, this will generate an equiaxed crystal structure with small anisotropy in the center of thickness of the slab. It is expected to improve the workability and formability of steel sheets. However, when ultrasonic vibration is applied in normal continuous casting, the cooling rate is slow in normal continuous casting, so even if equiaxed crystal nuclei are formed by cavitation due to ultrasonic vibration, the equiaxed crystal nuclei generated thereafter are generated. Is liable to coalesce / grow or redistribute and disappear, so even if ultrasonic vibration is excited in the mold, it is not possible to form a fine equiaxed crystal part in the center of the thickness of the slab. rice field.

これに対して、双ロール式連続鋳造法における溶鋼プール内において超音波を励起すると、鋳造した薄肉鋳片の厚み中心部に微細な等軸晶部を形成できることがはじめて判明した。双ロール式連続鋳造の溶鋼プール内は、キャビテーションによって溶鋼中に等軸晶核が生成すると、短時間のうちに固液界面に堆積して、等軸晶核が合体/成長あるいは消滅する前に、鋳造する鋳片中に取り込まれ、鋳片の厚み中心部に微細な等軸晶帯が形成されるのである。また、鋳造後の鋳片の冷却速度が速く、微細な等軸晶として鋳造が可能となる。さらに、微細な等軸晶が双ロールにより圧下され充填することで、中心偏析やポロシティの形成を抑制する。 On the other hand, it was found for the first time that a fine equiaxed crystal part can be formed in the center of the thickness of the cast thin-walled slab by exciting ultrasonic waves in the molten steel pool in the twin-roll continuous casting method. In the molten steel pool of bi-roll type continuous casting, when equiaxed crystal nuclei are generated in the molten steel by cavitation, they are deposited on the solid-liquid interface in a short time, and before the equiaxed crystal nuclei coalesce / grow or disappear. , It is taken into the slab to be cast, and a fine equiaxed crystal zone is formed in the center of the thickness of the slab. In addition, the cooling rate of the slab after casting is high, and casting becomes possible as fine equiaxed crystals. Further, fine equiaxed crystals are compressed and filled by the twin rolls to suppress central segregation and formation of porosity.

超音波振動によって加振先端部の先の溶鋼中に微細等軸晶を生成するに際し、キャビテーションが生じる範囲が加振先端部の先の狭い領域内に限定されるので、微細等軸晶核の発生もこのキャビテーション領域内に限定される。そこで、鋳片に等軸晶帯を生成させるために有利な方法を見いだすべく、超音波振動子4の配置を変えて効果を検討した。 When a fine equiaxed crystal is generated in the molten steel at the tip of the vibration tip by ultrasonic vibration, the range where cavitation occurs is limited to the narrow region at the tip of the vibration tip. Occurrence is also limited to this cavitation area. Therefore, in order to find an advantageous method for forming an equiaxed crystal zone in the slab, the effect was examined by changing the arrangement of the ultrasonic vibrator 4.

双ロール式連続鋳造法では、浸漬ノズル2の吐出孔3から出た溶鋼は、図1(A)、図3(B)に示すように、一度ロールを駆け上がったのちにサイド堰8方向に流動し、その後サイド堰8で反転することが分かった。そこで、平面視において、吐出孔3と吐出孔両端から浸漬ノズル側面20に垂直に引いた2本の直線22との間の空間であって鋳造ロール1に到達するまでの間(図1(B)の領域A)に超音波振動子4を設置したところ、吐出流14の流動とともに微細等軸晶も流動し、幅方向に均一に分布することが分かった。同時に、振動伝達部6の加振先端部7は、吐出孔3の上端よりも上方に配置することにより、吐出孔3からの吐出流14中にキャビテーション部を配置することができるので、最も優れた効果を発揮することができる。以下、超音波振動子4の上記のような配置を「配置(A)」と呼ぶ。 In the double-roll type continuous casting method, the molten steel discharged from the discharge hole 3 of the immersion nozzle 2 runs up the roll once and then moves in the direction of the side weir 8 as shown in FIGS. 1 (A) and 3 (B). It was found that it flowed and then reversed at the side weir 8. Therefore, in a plan view, it is a space between the discharge hole 3 and the two straight lines 22 drawn perpendicularly to the side surface 20 of the immersion nozzle from both ends of the discharge hole until the casting roll 1 is reached (FIG. 1 (B). When the ultrasonic transducer 4 was installed in the region A) of), it was found that the fine equiaxed crystals also flowed along with the flow of the discharge flow 14 and were uniformly distributed in the width direction. At the same time, by arranging the vibration tip portion 7 of the vibration transmission portion 6 above the upper end of the discharge hole 3, the cavitation portion can be arranged in the discharge flow 14 from the discharge hole 3, which is the most excellent. Can exert the effect. Hereinafter, the above-mentioned arrangement of the ultrasonic vibrator 4 is referred to as "arrangement (A)".

超音波振動子4を配置(A)に配置して超音波振動を付与すると、浸漬ノズル2の吐出孔3からの吐出流14に直接に微細等軸晶を生成させるので、吐出流14が固液共存状態になる。この結果、吐出流溶鋼は微細等軸晶を含有するためにその粘性が増加し、溶鋼のロールへの駆け上がりを抑制することができた。溶鋼のロールへの駆け上がりは溶鋼プールの湯面変動の原因となり、鋳片表面の割れを発生させる。従って、配置(A)にて超音波振動を付与することにより、鋳片表面の割れを防止することが可能となる。 When the ultrasonic vibrator 4 is arranged in the arrangement (A) and ultrasonic vibration is applied, fine equiaxed crystals are directly generated in the discharge flow 14 from the discharge hole 3 of the immersion nozzle 2, so that the discharge flow 14 is solid. It becomes a liquid coexistence state. As a result, since the discharged molten steel contains fine equiaxed crystals, its viscosity increased, and it was possible to suppress the run-up of the molten steel to the roll. The run-up of the molten steel to the roll causes the molten metal pool to fluctuate, causing cracks on the surface of the slab. Therefore, it is possible to prevent cracking on the surface of the slab by applying ultrasonic vibration in the arrangement (A).

超音波振動子の配置位置を、図1(C)に示すように、浸漬ノズルの吐出孔が設けられている側面20と鋳造ロールの間の空間ではあるものの、領域Aからは外れた位置(領域B)に配置した場合(設置(B))、形成された等軸晶核の一部は溶鋼流動に乗って移動するので鋳片の等軸晶帯生成に寄与するものの、配置(A)に配置した場合に比較すると効果が弱まり、特に板幅中心での等軸晶率が配置(A)の場合より低下した。 As shown in FIG. 1 (C), the position of the ultrasonic vibrator is located at a position outside the region A, although it is a space between the side surface 20 where the discharge hole of the immersion nozzle is provided and the casting roll. When arranged in the region B) (installation (B)), a part of the formed equiaxed crystal nuclei moves along with the molten steel flow, which contributes to the formation of the equiaxed crystal zone of the slab, but the arrangement (A). The effect was weaker than that in the case of the arrangement (A), and the equiaxed crystal ratio at the center of the plate width was lower than that in the case of the arrangement (A).

超音波振動子の配置位置を、図2に示すように、ノズル脇(吐出孔3を有しない側面21の側)(領域C)に配置した場合(配置(C)という)、超音波振動付与による鋳片の等軸晶帯生成に効果を発揮するものの、反転流によりさらに等軸晶の流動が抑えられ、板厚中心部およびサイド堰近傍での等軸晶率が配置(B)の場合より低下した。このことから、等軸晶を均一に分散させるにはノズル吐出孔正面の領域Aに超音波振動子4を設置するのが望ましい。 As shown in FIG. 2, when the ultrasonic vibrator is arranged on the side of the nozzle (the side of the side surface 21 having no discharge hole 3) (region C) (referred to as arrangement (C)), ultrasonic vibration is applied. Although it is effective in forming the equiaxed crystal zone of the slab, the flow of the equiaxed crystal is further suppressed by the reversal flow, and the equiaxed crystal ratio is arranged in the center of the plate thickness and near the side dam (B). It was lower. For this reason, it is desirable to install the ultrasonic transducer 4 in the region A in front of the nozzle discharge hole in order to uniformly disperse the equiaxed crystals.

超音波振動子4の加振先端部7の先の溶鋼中にキャビテーションによる等軸晶生成を促すに際し、超音波振動子の超音波発信器における好適な条件が存在する。即ち、超音波発信器は、周波数18~25kHz、振幅(p-p)14~50μmの超音波を発生させると好ましい。周波数は、18kHz以上25kHz以下として試験を行った結果、実施範囲において、微細等軸晶が生成した。振幅(p-p)14μm以上とすると好ましいのは、振幅(p-p)14μm未満では、等軸晶生成量が少なく、製品に異方性が発生してしまうからである。振幅(p-p)を50μm以下とすると好ましいのは、振幅(p-p)が50μm超では、溶鋼湯面に浮遊するスカムを巻き込んでしまい、製品欠陥につながるからである。振幅(p-p)については、超音波発信器の設定値を意味する。 In promoting the formation of equiaxed crystals by cavitation in the molten steel at the tip of the vibration tip portion 7 of the ultrasonic vibrator 4, there are suitable conditions for the ultrasonic transmitter of the ultrasonic vibrator. That is, it is preferable that the ultrasonic transmitter generates ultrasonic waves having a frequency of 18 to 25 kHz and an amplitude (pp) of 14 to 50 μm. As a result of the test in which the frequency was set to 18 kHz or more and 25 kHz or less, fine equiaxed crystals were generated in the implementation range. It is preferable that the amplitude (pp) is 14 μm or more because the amount of equiaxed crystals produced is small and the product becomes anisotropy when the amplitude (pp) is less than 14 μm. It is preferable that the amplitude (pp) is 50 μm or less because if the amplitude (pp) is more than 50 μm, scum floating on the molten steel surface is involved, which leads to product defects. The amplitude (pp) means the set value of the ultrasonic transmitter.

本発明の厚みが5mm以下の炭素鋼薄肉鋳片は、本発明の炭素鋼薄肉鋳片の製造装置を用いた炭素鋼薄肉鋳片の製造方法を適用することにより製造することができる。得られた炭素鋼薄肉鋳片は、等軸晶率が20%以上、等軸晶平均粒径が0.1mm以下であることを特徴とする。鋳片の厚みを5mm以下とするのは、これによってニア・ネット・シェイプ連続鋳造の効果を十分に発揮できるからである。等軸晶率を20%以上、等軸晶平均粒径を0.1mm以下とするのは、このような品質の鋳片は本発明によってはじめて可能になったものであり、またこのような等軸晶率と等軸晶平均粒径を確保することにより、清浄性を確保しつつ加工性・成形性に優れた微細等軸晶組織となるからである。 The carbon steel thin-walled slab having a thickness of 5 mm or less of the present invention can be produced by applying the method for producing a carbon steel thin-walled slab using the carbon steel thin-walled slab manufacturing apparatus of the present invention. The obtained carbon steel thin-walled slab is characterized by having an equiaxed crystal ratio of 20% or more and an equiaxed crystal average particle size of 0.1 mm or less. The reason why the thickness of the slab is 5 mm or less is that the effect of the near net shape continuous casting can be fully exerted. The equiaxed crystal ratio of 20% or more and the equiaxed crystal average particle size of 0.1 mm or less are made possible for the first time by the present invention for slabs of such quality. This is because by ensuring the axial crystal ratio and the equiaxed crystal average particle size, a fine equiaxed crystal structure having excellent workability and moldability while ensuring cleanliness can be obtained.

ロール幅1000mm、ロール直径1200mmの一対の鋳造ロール1を有する双ロール鋳造装置(図1、図2参照)を用いて、60tの鋼の鋳造を行い、厚さ2mmの鋳片を製造した。鋳造に際して、鋳造速度を0.9m/sとした。超音波振動子4は超音波発信器5と振動伝達部6を有する。振動伝達部6はφ50mmの円柱形状である。振動伝達部6の加振先端部7を溶鋼プール10に浸漬し、溶鋼中に超音波を付与した。加振先端部7が浸漬ノズル2の吐出孔3上端の高さに合うように設置した。超音波振動子4の位置は平面視において領域A、領域B、領域Cの領域に配置し、それぞれ配置(A)(図1(B)参照)、配置(B)(図1(C)参照)、配置(C)(図2(B)参照)とした。超音波振動子の振幅(p-P)は超音波発振器の設定値を示す。 Using a twin-roll casting apparatus (see FIGS. 1 and 2) having a pair of casting rolls 1 having a roll width of 1000 mm and a roll diameter of 1200 mm, 60 tons of steel was cast to produce a slab having a thickness of 2 mm. At the time of casting, the casting speed was set to 0.9 m / s. The ultrasonic vibrator 4 has an ultrasonic transmitter 5 and a vibration transmission unit 6. The vibration transmission unit 6 has a cylindrical shape with a diameter of 50 mm. The vibration tip portion 7 of the vibration transmission portion 6 was immersed in the molten steel pool 10, and ultrasonic waves were applied to the molten steel. The vibration tip portion 7 was installed so as to match the height of the upper end of the discharge hole 3 of the immersion nozzle 2. The positions of the ultrasonic transducers 4 are arranged in the regions A, B, and C in a plan view, and are arranged (A) (see FIG. 1 (B)) and arranged (B) (see FIG. 1 (C), respectively). ), Arrangement (C) (see FIG. 2B). The amplitude (pp) of the ultrasonic oscillator indicates the set value of the ultrasonic oscillator.

鋳造した薄肉鋳片の1/2幅部(幅端面から400~600mmの位置)、1/4幅部(幅端面から100~300mmの位置)の位置より鋳片サンプルを採取し、等軸晶率、等軸晶粒径、等軸晶率の幅方向均一性、ポロシティ、スカムの巻き込み、鋳片表面割れについて評価を行った。
等軸晶率の測定:1/2幅部の鋳片断面をピクリン酸エッチングして凝固組織を現出し、鋳片サンプルを等軸晶帯面積/板観察面面積×100(%)として算出した。
等軸晶粒径の測定:1/2厚部の鋳片断面をピクリン酸エッチングして凝固組織を現出し、代表的な等軸晶20個の円相当径を算出し、平均粒径とした。
等軸晶率の幅方向均一性:1/2幅部と1/4幅部の鋳片断面をピクリン酸エッチングして凝固組織を現出し、等軸晶率を測定し、等軸晶率(%)の差が15ポイント未満であれば、◎、差が15~30ポイントであれば○、差が30ポイント超であれば△とした。
ポロシティ:1/2幅部と1/4幅部の鋳片断面を光学顕微鏡で観察し、長径で0.2mm以上のポロシティが発生した場合は「ポロシティ」を「あり」、長径で0.2mm以上のポロシティが無い場合は「なし」とした。
スカムの巻き込み::1/2幅部と1/4幅部の鋳片断面を光学顕微鏡で観察し、円径相当で0.5mm以上の酸化物系の異物が存在する場合を「あり」、なければ「なし」とした。
鋳片表面割れ:1/2幅部と1/4幅部の鋳片断面を光学顕微鏡で観察し、表面まで続く0.5mm以上の割れが発生した場合は鋳片表面割れを「あり」、0.5mm未満であれば「なし」とした。
A slab sample is collected from the 1/2 width part (position 400 to 600 mm from the width end face) and 1/4 width part (position 100 to 300 mm from the width end face) of the cast thin-walled slab, and equiaxed crystals are collected. The rate, equiaxed grain size, isoaxial crystalliteity in the width direction, porosity, scum entrainment, and slab surface cracking were evaluated.
Measurement of equiaxed crystal ratio: The cross section of the slab in the 1/2 width part was etched with picric acid to reveal the solidified structure, and the slab sample was calculated as the equiaxed crystal zone area / plate observation surface area × 100 (%). ..
Measurement of equiaxed crystal grain size: A solidified structure was revealed by etching the cross section of a slab of 1/2 thick part with picric acid, and the equivalent circle diameter of 20 typical equiaxed crystals was calculated and used as the average grain size. ..
Width uniformity of equiaxed crystal ratio: The cross section of the slab in the 1/2 width part and the 1/4 width part is picric acid etched to reveal the solidified structure, and the equiaxed crystal ratio is measured. %) Was evaluated as ⊚ if the difference was less than 15 points, ◯ if the difference was 15 to 30 points, and Δ if the difference was more than 30 points.
Porosity: Observe the cross section of the slab in the 1/2 width part and the 1/4 width part with an optical microscope, and if porosity of 0.2 mm or more occurs in the major axis, "Porosity" is "Yes" and the major axis is 0.2 mm. If there is no above porosity, it is set to "None".
Scum entrainment :: Observe the cross section of the slab in the 1/2 width part and the 1/4 width part with an optical microscope, and if there is an oxide-based foreign substance with a diameter equivalent to 0.5 mm or more, "Yes". If not, it was "None".
Fragment surface cracks: Observe the slab cross sections of 1/2 width and 1/4 width with an optical microscope, and if cracks of 0.5 mm or more that continue to the surface occur, there is a slab surface crack. If it is less than 0.5 mm, it is set as "None".

鋳造した溶鋼成分(単位は質量%)を表1、鋳造条件と鋳造結果を表2に示す。 Table 1 shows the cast molten steel components (unit: mass%), and Table 2 shows the casting conditions and casting results.

Figure 0007099129000001
Figure 0007099129000001

Figure 0007099129000002
Figure 0007099129000002

実施例1~5、10~11は本発明例である。中でも、実施例1~5は、超音波振幅が本発明の好適範囲であり、超音波振動子の配置位置が好適位置である配置(A)であり、等軸晶率、等軸晶粒径、等軸晶率の幅方向均一性のいずれも良好であった。その結果、ポロシティ発生、スカム巻き込み、鋳片表面割れのいずれも「なし」であり、最も良好な結果を得ることができた。 Examples 1 to 5, 10 to 11 are examples of the present invention. Among them, Examples 1 to 5 have an arrangement (A) in which the ultrasonic amplitude is in the preferable range of the present invention and the arrangement position of the ultrasonic vibrator is a suitable position, and the equiaxed crystal ratio and the equiaxed crystal grain size. , The uniformity of the equiaxed crystal ratio in the width direction was good. As a result, all of porosity generation, scum entrainment, and slab surface cracking were "none", and the best results could be obtained.

参考例6~9は超音波振動子の配置位置が最適位置(配置(A))からは外れており、等軸晶率、等軸晶粒径は良好な結果を得ているものの、等軸晶率の幅方向均一性が上記実施例1~5ほどには良好でなかった。また、ロールへの溶鋼駆け上がりによる鋳片割れが発生した。 In Reference Examples 6 to 9, the arrangement position of the ultrasonic transducer is out of the optimum position (arrangement (A)), and although the equiaxed crystal ratio and equiaxed crystal grain size are obtained with good results, the equiaxed axis is obtained. The uniformity in the width direction of the crystal ratio was not as good as in Examples 1 to 5 above. In addition, slab cracking occurred due to the run-up of molten steel on the roll.

実施例10は超音波振幅が本発明の好適範囲下限を外れており、等軸晶率、等軸晶粒径の改善効果がやや低かったとともに、ポロシティの発生が見られた。実施例11は超音波振幅が本発明の好適範囲上限を外れており、ポロシティ、鋳片表面割れ成績は良好であったものの、スカム巻き込みが見られた。 In Example 10, the ultrasonic amplitude was out of the lower limit of the preferable range of the present invention, the effect of improving the equiaxed crystal ratio and the equiaxed crystal grain size was slightly low, and porosity was observed. In Example 11, the ultrasonic amplitude was out of the upper limit of the preferable range of the present invention, and although the porosity and the surface cracking of the slab were good, scum entrainment was observed.

比較例1,2は、超音波振動を付与しなかった場合である。比較例1は等軸晶率が0%、比較例2は等軸晶率が4%であり、ほぼ柱状晶組織であった。若干の等軸晶組織生成する場合はあるが幅方向に組織不均一であった。等軸晶の充填がなくポロシティが発生した。ロールへの溶鋼駆け上がりによる鋳片割れが発生した。 Comparative Examples 1 and 2 are cases where ultrasonic vibration is not applied. Comparative Example 1 had an equiaxed crystal ratio of 0%, and Comparative Example 2 had an equiaxed crystal ratio of 4%, and had a substantially columnar crystal structure. Although some equiaxed crystal structure was formed, the structure was non-uniform in the width direction. Porosity occurred without filling with equiaxed crystals. Fragment cracking occurred due to the run-up of molten steel on the roll.

1 鋳造ロール
2 浸漬ノズル
3 吐出孔
4 超音波振動子
5 超音波発信器
6 振動伝達部
7 加振先端部
8 サイド堰
9 隙間部
10 溶鋼プール
11 溶鋼流
12 凝固シェル
13 鋳片
14 吐出流
20 側面
21 側面
22 直線
31 溶鋼プール表面
32 溶鋼プール表面の縁
1 Casting roll 2 Immersion nozzle 3 Discharge hole 4 Ultrasonic oscillator 5 Ultrasonic transmitter 6 Vibration transmission part 7 Vibration tip part 8 Side dam 9 Gap part 10 Molten steel pool 11 Molten steel flow 12 Solidified shell 13 Cast piece 14 Discharge flow 20 Side 21 Side 22 Straight 31 Molten steel pool surface 32 Edge of molten steel pool surface

Claims (3)

双ロールで囲まれた溶鋼プール中に浸漬ノズルから溶鋼を供給して鋳造を行う、双ロール式連続鋳造による炭素鋼薄肉鋳片の製造装置であって、
前記浸漬ノズルの側面の前記溶鋼プールに浸漬する位置に溶鋼の吐出孔を有し、
超音波振動子を有し、前記超音波振動子は超音波発信器と振動伝達部を有し、
前記超音波振動子を、平面視において、前記吐出孔と吐出孔両端から浸漬ノズル側面に垂直に引いた2本の直線との間の空間に配置するとともに、前記振動伝達部の加振先端部を、前記吐出孔の上端よりも上方に配置し、
前記振動伝達部の前記加振先端部は、前記溶鋼プールの溶鋼中に浸漬可能であることを特徴とする炭素鋼薄肉鋳片の製造装置。
A carbon steel thin-walled slab manufacturing device by double-roll continuous casting, in which molten steel is supplied from a dipping nozzle into a molten steel pool surrounded by double-rolls for casting.
A molten steel discharge hole is provided at a position on the side surface of the immersion nozzle to be immersed in the molten steel pool.
It has an ultrasonic oscillator, and the ultrasonic oscillator has an ultrasonic transmitter and a vibration transmission unit.
The ultrasonic vibrator is arranged in a space between the discharge hole and two straight lines drawn perpendicularly to the side surface of the immersion nozzle from both ends of the discharge hole in a plan view, and the vibration tip portion of the vibration transmission unit is provided. Is placed above the upper end of the discharge hole.
A carbon steel thin-walled slab manufacturing apparatus, wherein the vibration tip portion of the vibration transmission portion can be immersed in the molten steel of the molten steel pool.
請求項1に記載の炭素鋼薄肉鋳片の製造装置を用いた炭素鋼薄肉鋳片の製造方法であって、
双ロールで囲まれた溶鋼プール中に浸漬ノズルから溶鋼を供給し、前記振動伝達部の加振先端部を前記溶鋼プールの溶鋼中に浸漬させて溶鋼プール中の溶鋼に超音波振動を加え、炭素鋼薄肉鋳片を連続鋳造することを特徴とする炭素鋼薄肉鋳片の製造方法。
A method for manufacturing a carbon steel thin-walled slab using the carbon steel thin-walled slab manufacturing apparatus according to claim 1.
The molten steel is supplied from the immersion nozzle into the molten steel pool surrounded by the twin rolls, the vibration tip of the vibration transmission portion is immersed in the molten steel of the molten steel pool, and ultrasonic vibration is applied to the molten steel in the molten steel pool. A method for manufacturing a carbon steel thin-walled slab, which comprises continuously casting carbon steel thin-walled slabs.
前記超音波振動子の超音波発信器により、周波数18~25kHz、振幅(p-p)14~50μmの超音波を発生させることを特徴とする請求項2に記載の炭素鋼薄肉鋳片の製造方法。 The production of a carbon steel thin-walled slab according to claim 2, wherein an ultrasonic wave having a frequency of 18 to 25 kHz and an amplitude (pp) of 14 to 50 μm is generated by the ultrasonic transmitter of the ultrasonic transducer. Method.
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JP2017131933A (en) 2016-01-28 2017-08-03 新日鐵住金株式会社 Production method for low-carbon steel thin-walled cast slab, the thin-walled cast slab, and production method for low-carbon thin-walled steel sheet

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