JP4493612B2 - Continuous casting method of aluminum killed steel - Google Patents

Continuous casting method of aluminum killed steel Download PDF

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JP4493612B2
JP4493612B2 JP2006064459A JP2006064459A JP4493612B2 JP 4493612 B2 JP4493612 B2 JP 4493612B2 JP 2006064459 A JP2006064459 A JP 2006064459A JP 2006064459 A JP2006064459 A JP 2006064459A JP 4493612 B2 JP4493612 B2 JP 4493612B2
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nozzle
steel
aluminum killed
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JP2007237255A (en
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法明 温品
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Nippon Steel Nisshin Co Ltd
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Description

本発明は、CaO成分を含有する鋳造用ノズルを用いて行うアルミキルド鋼、とりわけクロムを含有したアルミキルドステンレス鋼の連続鋳造方法に関する。   The present invention relates to a continuous casting method of aluminum killed steel, particularly aluminum killed stainless steel containing chromium, which is performed using a casting nozzle containing a CaO component.

鋳造用ノズルには、取鍋からタンディッシュに溶鋼を注入するのに用いるロングノズル、タンディッシュからモールドに溶鋼を注入するのに用いる浸漬ノズルがあり、その材質には主にアルミナ−黒鉛質が用いられている。アルミナ−黒鉛質は、耐スポーリング性、耐摩耗性、耐蝕性に優れているが、アルミキルド鋼の鋳造に用いた場合、鋼中のアルミが酸化して形成されるアルミナがノズル内孔面に付着してクラスタ化し、これが成長して大型の介在物となっては溶鋼流に剥ぎ取られて鋳片内に取込まれ、品質を低下させたり、ノズル内孔面に付着する介在物がより一層大きく成長してノズルを絞るノズル閉塞を生じたりする。この対策としてノズル内孔面からアルゴンガスを溶鋼中に吹き込んでアルミナの付着を阻止することが試みられているが、アルゴンガスの吹き込み量が多くなると、その気泡が鋳片内に取込まれてピンホールとなる欠陥を生じがちである。このためガスの吹き込み量には制約があって、必ずしも十分な対策とは成り得ていなかった。このほかの対策として、ノズルを構成する耐火材自体にアルミナ付着防止機能を持たせたものも知られる。下記特許文献1には、黒鉛と焼結カルシア、電融カルシア又はCaO成分を含むほかの窯業用原料と、残部が耐火性骨材粉からなり、CaO成分が20〜75質量%である混合粉を主成分とする耐火物を使用した鋳造用ノズルが開示されている。
特公昭61−44836号
Casting nozzles include a long nozzle used to inject molten steel from the ladle into the tundish, and an immersion nozzle used to inject molten steel from the tundish into the mold. The material is mainly alumina-graphite. It is used. Alumina-graphite is excellent in spalling resistance, wear resistance, and corrosion resistance, but when used for casting aluminum killed steel, alumina formed by oxidation of aluminum in the steel is formed on the nozzle bore surface. It adheres and clusters, grows into large inclusions, and is peeled off by the molten steel flow and taken into the slab, resulting in lower quality and more inclusions adhering to the nozzle bore surface. It may grow larger and cause nozzle clogging that squeezes the nozzle. In order to prevent this, it has been attempted to prevent the adhesion of alumina by blowing argon gas into the molten steel from the nozzle inner hole surface. It tends to cause defects that become pinholes. For this reason, there are restrictions on the amount of gas blown in, and it has not necessarily been a sufficient measure. As another countermeasure, there is also known a refractory material constituting the nozzle itself having an alumina adhesion preventing function. In the following Patent Document 1, a mixed powder containing graphite and sintered calcia, electrofused calcia or other ceramic materials containing a CaO component, the balance being refractory aggregate powder, and the CaO component being 20 to 75% by mass. Nozzle for casting using a refractory material containing as a main component is disclosed.
JP-B 61-44836

ノズルにCaOを含有する耐火物を用いると、CaOを含有する耐火物が有するアルミナの吸着作用と、CaOとアルミナが反応して生成されるCaO−Al系物質が低融点で液相を呈するため、ノズル内孔面が平滑になり、アルミナの付着を防止する作用との相乗効果により鋳片内のアルミナ系大型介在物の含有量を減少させることができるが、CaOの含有量は、鋳片中のアルミナ系大型介在物の存在を低減させる効果からいうと、多いほど望ましいが、反面、CaO成分が多くなると、溶損が大きくなる嫌いがある。 When a refractory containing CaO is used for the nozzle, the adsorption action of alumina possessed by the refractory containing CaO and the CaO—Al 2 O 3 based material produced by the reaction of CaO and alumina have a low melting point and a liquid phase. Therefore, the inner surface of the nozzle becomes smooth, and the content of alumina inclusions in the slab can be reduced by a synergistic effect with the action of preventing the adhesion of alumina, but the content of CaO is In terms of the effect of reducing the presence of large alumina inclusions in the slab, the larger the amount, the better, but on the other hand, the more the CaO component, the greater the discomfort.

本発明は、CaOを20質量%以上含有する鋳造用ノズルを用いて行うアルミキルド鋼の連続鋳造方法において、ノズルの溶損を改善することを目的とする。   An object of the present invention is to improve nozzle melting loss in a continuous casting method of aluminum killed steel using a casting nozzle containing 20 mass% or more of CaO.

請求項1に係わる発明は、CaOを20質量%以上含有するドロマイトグラファイト質の鋳造用ノズルを用いて行うアルミキルド鋼の連続鋳造方法において、鋼中のAl含有量を0.15質量%以下とし、ノズルを通る溶鋼の平均流速を900〜1600mm/secにしたことを特徴とする。   The invention according to claim 1 is an aluminum killed steel continuous casting method that is performed using a dolomite graphite casting nozzle containing 20 mass% or more of CaO, wherein the Al content in the steel is 0.15 mass% or less, The average flow velocity of the molten steel passing through the nozzle is set to 900 to 1600 mm / sec.

本発明において、鋳造用ノズルのCaO含有量を20質量%以上としたのは、20質量%未満ではアルミナの吸着能力とアルミナ付着防止能力が小さく、鋳片内のアルミナ系大型介在物の含有量の改善の程度が小さいためであり、CaOの含有量の上限を60質量%としたのは、CaO量が多くなると、溶損が大きくなるためである
In the present invention, the CaO content of the casting nozzle is set to 20% by mass or more. When the CaO content is less than 20% by mass, the alumina adsorption ability and the alumina adhesion preventing ability are small, and the content of the alumina-based inclusions in the slab is small. der for a low level of improvement in is, was a 60 wt% the upper limit of the content of CaO, when the amount of CaO increases, because the erosion increases.

図1は、Cr系アルミキルドステンレス鋼を連続鋳造したときの浸漬ノズル内孔面に付着するアルミナ介在物の付着速度とCaO量との関係を示す図で、図で見られるように、ノズルのCaO含有量が20質量%以上の場合、CaOの含有量が0のものと比べ、介在物の付着速度が大幅に低下していることが見られる。   FIG. 1 is a diagram showing the relationship between the deposition rate of alumina inclusions adhering to the inner surface of a submerged nozzle and the amount of CaO when Cr-based aluminum killed stainless steel is continuously cast. When the content is 20% by mass or more, it can be seen that the deposition rate of inclusions is greatly reduced as compared with the case where the content of CaO is 0.

ノズルに炭素を含有させたのは、耐スポーリング性を改善させるためで、その含有量を1〜40質量%としたのは、ノズルの耐溶損、耐磨耗性を向上させるためである。図2は、アルミキルドステンレス鋼の連続鋳造に用いる浸漬ノズルにおいて、カーボン含有量と耐磨耗性との関係を示す図で、指数は、カーボン量を60重量%としたときの耐摩耗性を100としたものである。
請求項2に係わる発明は、請求項1に係わる発明において、アルミキルド鋼はクロムを10〜30質量%含有するアルミキルドステンレス鋼であることを特徴とする。
The reason why carbon is contained in the nozzle is to improve the spalling resistance, and the content is set to 1 to 40% by mass in order to improve the melt resistance and wear resistance of the nozzle. FIG. 2 is a graph showing the relationship between the carbon content and the wear resistance in an immersion nozzle used for continuous casting of aluminum killed stainless steel. The index indicates the wear resistance when the carbon content is 60% by weight. It is what.
The invention according to claim 2 is the invention according to claim 1, characterized in that the aluminum killed steel is aluminum killed stainless steel containing 10 to 30% by mass of chromium.

本発明によると、ノズルにCaOを20質量%以上含有する耐火物を用いたことにより、鋳片内のアルミナ系大型介在物の含有量を減少させ、品質を向上させることができると共に、CaOを含有したことによりもたらされる欠点である、溶損をアルミキルド鋼中のAl含有量を0.15質量以下とし、かつノズルを通過する溶鋼の平均流速を900〜1600mm/secにすることにより改善することができる。   According to the present invention, by using a refractory containing 20% by mass or more of CaO in the nozzle, the content of large alumina inclusions in the slab can be reduced and the quality can be improved. Improvement of melting loss by setting the Al content in aluminum killed steel to 0.15 mass or less and the average flow rate of molten steel passing through the nozzle to 900 to 1600 mm / sec, which is a defect caused by the inclusion. Can do.

図3は、本発明方法で用いる浸漬ノズル1、すなわちタンディッシュ2からモールド3に溶鋼を注入するのに用いる内径60mmの浸漬ノズル1について示すもので、モールドは幅700〜1380mm、厚み200mmである。図中、4は溶鋼流を制御するストッパーである。   FIG. 3 shows the immersion nozzle 1 used in the method of the present invention, that is, the immersion nozzle 1 having an inner diameter of 60 mm used to inject molten steel from the tundish 2 into the mold 3. The mold has a width of 700 to 1380 mm and a thickness of 200 mm. . In the figure, 4 is a stopper for controlling the molten steel flow.

連続鋳造は、図3に示すタンディッシュ2に10〜30質量%のクロムを含有するアルミキルドステンレス鋼の溶鋼を入れて行い、数チャージごとにモールド3を出たスラブの板幅、板厚及び鋳造速度から浸漬ノズル1を通る溶鋼の平均流速を求めると共に、このとき得られたスラブから鋼中のAl濃度を求めた。そして数チャージごとに浸漬ノズル1の溶損や閉塞の程度を目視により観察した。結果を図4に示す。また、このとき使用した浸漬ノズルの成分を表1に示す。   Continuous casting is carried out by putting molten steel of aluminum killed stainless steel containing 10 to 30% by mass of chromium in the tundish 2 shown in FIG. 3, and the width, thickness and casting of the slab that comes out of the mold 3 every several charges. While calculating | requiring the average flow velocity of the molten steel which passes the immersion nozzle 1 from speed, the Al concentration in steel was calculated | required from the slab obtained at this time. Then, every several charges, the degree of melting and clogging of the immersion nozzle 1 was visually observed. The results are shown in FIG. The components of the immersion nozzle used at this time are shown in Table 1.

Figure 0004493612
Figure 0004493612

図4に示されるように、Cr系アルミキルドステンレス鋼の連続鋳造において、鋼中のAl濃度が0.15質量%以下であり、かつノズル1を通る溶鋼の平均流速が900〜1600mm/secであると、ノズル1に溶損や閉塞が認められなかった。   As shown in FIG. 4, in the continuous casting of Cr-based aluminum killed stainless steel, the Al concentration in the steel is 0.15% by mass or less, and the average flow velocity of the molten steel passing through the nozzle 1 is 900 to 1600 mm / sec. No nozzle 1 was melted or clogged.

本発明は、アルミキルド鋼、とりわけCr系アルミキルドステンレス鋼の連続鋳造に用いられる。   The present invention is used for continuous casting of aluminum killed steel, particularly Cr-based aluminum killed stainless steel.

ノズルのCaO含有量と介在物の付着速度との関係を示す図。The figure which shows the relationship between CaO content of a nozzle, and the adhesion rate of an inclusion. ノズルのカーボンの含有量と耐摩耗性との関係を示す図。The figure which shows the relationship between the carbon content of a nozzle, and abrasion resistance. 本発明で用いる連続鋳造設備の要部の断面図。Sectional drawing of the principal part of the continuous casting equipment used by this invention. 鋼中のアルミ濃度と鋳造速度との関係を示す図。The figure which shows the relationship between the aluminum concentration in steel, and casting speed.

符号の説明Explanation of symbols

1・・浸漬ノズル
2・・タンディッシュ
3・・モールド
4・・ストッパー
1 .... Immersion nozzle 2 ... Tundish 3 ... Mold 4 ... Stopper

Claims (2)

CaOを20〜60質量%、炭素を1〜40質量%、MgOを10〜50重量%含有するドロマイトグラファイト質の鋳造用ノズルを用いて行うアルミキルド鋼の連続鋳造方法において、鋼中のAl含有量を0.15質量%以下とし、ノズルを通る溶鋼の平均流速を900〜1600mm/secにしたことを特徴するアルミキルド鋼の連続鋳造方法。 In an aluminum killed steel continuous casting method using a dolomite graphite casting nozzle containing 20 to 60% by mass of CaO, 1 to 40% by mass of carbon, and 10 to 50% by mass of MgO , the Al content in the steel the 0.15 wt% or less, the continuous casting method of aluminum-killed steel, characterized in that the average flow velocity of molten steel through the nozzle 900~1600mm / sec. アルミキルド鋼はクロムを10〜30質量%含有するアルミキルドステンレス鋼であることを特徴とする請求項1記載のアルミキルド鋼の連続鋳造方法。
2. The method of continuous casting of aluminum killed steel according to claim 1, wherein the aluminum killed steel is aluminum killed stainless steel containing 10 to 30% by mass of chromium.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6144836A (en) * 1984-08-08 1986-03-04 Green Cross Corp:The Substituted styrene derivative
JP2000001716A (en) * 1998-06-18 2000-01-07 Kawasaki Steel Corp Method for melting chromium-containing steel
JP2004188421A (en) * 2002-12-06 2004-07-08 Sumitomo Metal Ind Ltd Immersion nozzle for continuous casting and continuous casting method
JP2005262301A (en) * 2004-03-22 2005-09-29 Nippon Steel Corp Immersion nozzle for continuous casting
JP2007231372A (en) * 2006-03-01 2007-09-13 Nisshin Steel Co Ltd Method for producing aluminum-killed steel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6144836A (en) * 1984-08-08 1986-03-04 Green Cross Corp:The Substituted styrene derivative
JP2000001716A (en) * 1998-06-18 2000-01-07 Kawasaki Steel Corp Method for melting chromium-containing steel
JP2004188421A (en) * 2002-12-06 2004-07-08 Sumitomo Metal Ind Ltd Immersion nozzle for continuous casting and continuous casting method
JP2005262301A (en) * 2004-03-22 2005-09-29 Nippon Steel Corp Immersion nozzle for continuous casting
JP2007231372A (en) * 2006-03-01 2007-09-13 Nisshin Steel Co Ltd Method for producing aluminum-killed steel

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