JP3389368B2 - Nozzle blockage prevention method for Al-less Ti deoxidized steel - Google Patents
Nozzle blockage prevention method for Al-less Ti deoxidized steelInfo
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- JP3389368B2 JP3389368B2 JP11107395A JP11107395A JP3389368B2 JP 3389368 B2 JP3389368 B2 JP 3389368B2 JP 11107395 A JP11107395 A JP 11107395A JP 11107395 A JP11107395 A JP 11107395A JP 3389368 B2 JP3389368 B2 JP 3389368B2
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Description
【０００１】[0001]
【産業上の利用分野】本発明は鋼の製造において、最終
製品での薄板、厚板、条鋼等の各製品の欠陥につながる
鋼中の非金属介在物（以下介在物と略称する）およびノ
ズルの閉塞を防止する方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to non-metallic inclusions (hereinafter abbreviated as inclusions) and nozzles in steel in the production of steel, which lead to defects in each product such as thin plate, thick plate and bar steel in the final product. The present invention relates to a method for preventing the blockage of
【０００２】[0002]
【従来の技術】近年、自動車や家電用薄板材および海洋
構造物、貯槽、石油およびガス運搬用鋼管、高張力線材
などの各種製品表面や内質の欠陥に対する要求は厳しさ
を増してきている。これらの欠陥は、鋳片での表面気
泡、内部気泡、内部割れ、中心偏析、介在物等に起因し
て発生する。この中で介在物は薄板の表面疵、厚板の内
部欠陥の主原因となり、線材では線材圧延時の断線原因
となっている。これらの製品欠陥に観察される介在物
は、転炉出鋼後の溶湯の脱酸や２次精錬における脱炭精
錬後の溶湯に、過剰に存在する酸素を除去するために実
施する脱酸時の脱酸材からの反応生成物や、あるいは耐
火物、スラグなどの巻き込みに起因した外来介在物にそ
の起源がある。2. Description of the Related Art In recent years, demands for surface and internal defects of various products such as thin plate materials and marine structures for automobiles and home appliances, storage tanks, steel pipes for carrying oil and gas, and high-strength wire rods have become more severe. . These defects occur due to surface bubbles, internal bubbles, internal cracks, center segregation, inclusions, etc. in the cast slab. Among these, inclusions are the main cause of surface defects of thin plates and internal defects of thick plates, and in wire rods, they are the cause of disconnection during wire rod rolling. The inclusions observed in these product defects are the deoxidation of the molten metal after tapping of the converter and the deoxidation of the molten metal after decarburization in the secondary refining to remove excess oxygen. It originates in the reaction products from the deoxidizers, or foreign inclusions caused by the inclusion of refractories and slag.
【０００３】このような製品欠陥を防止するための溶湯
清浄化法は、例えば第１２７回、西山技術記念講座（１
９８８年）に示されるごとく多くの研究がなされてい
る。しかしながら、製品成分の制約上から、Ａｌのみで
脱酸しなければならないＡｌ脱酸鋼の場合は、脱酸の安
定性や作業性および材質の観点からは非常に優れている
が、介在物に起因した表面欠陥の撲滅するまでには至っ
ていない。また、溶湯中に懸濁している微細な脱酸生成
物が、ノズル内面に堆積して、ノズルを閉塞するため、
多連鋳が困難となりＡｌ脱酸における脱酸生成物は、効
率的生産の阻害要因になっている。The molten metal cleaning method for preventing such a product defect is, for example, the 127th Nishiyama Memorial Memorial Course (1
(1988), many studies have been conducted. However, in the case of Al deoxidized steel, which must be deoxidized only with Al due to restrictions on product components, it is extremely excellent in terms of stability of deoxidation, workability, and material, The surface defects caused by this have not been eliminated. In addition, the fine deoxidized product suspended in the molten metal is deposited on the inner surface of the nozzle and blocks the nozzle,
Multi-casting becomes difficult, and the deoxidation product in Al deoxidation is an obstacle to efficient production.
【０００４】これらのノズル閉塞防止対策として、本発
明者らは種々の研究開発の結果、ＣａＯ・ＺｒＯ2 粒を
含有したノズルを使用することにより、稼働面にＣａＯ
−Ａｌ2 Ｏ3 の低融点層を生成し、ノズル閉塞が防止で
きることを、材料とプロセスＶｏｌ．４（１９９１），
ｐ．２１９，２２０で報告した。しかし、これらの対策
によっても介在物に起因した製品欠陥を絶滅させるまで
には至っておらず、さらなる対策が必要とされている。
このようなＡｌ脱酸の欠点を回避するため、種々の脱酸
法について研究した結果、本発明者らはＡｌを非常に少
なくしたＴｉ脱酸（以下ＡｌレスＴｉ脱酸と略称）鋼は
薄板材質として非常に良好な特性を有し、また製造した
薄板の表面欠陥が低減できることの知見を得るに至っ
た。As a measure for preventing these nozzle blockages, the inventors of the present invention have conducted various researches and developments, and as a result, by using a nozzle containing CaO.ZrO 2 particles, the CaO can be used on the operating surface.
Generates a low melting point layer of -al 2 O 3, that nozzle clogging can be prevented, materials and processes Vol. 4 (1991),
p. 219, 220. However, even with these measures, it has not been possible to eliminate the product defects caused by inclusions, and further measures are needed.
In order to avoid such drawbacks of Al deoxidation, as a result of research on various deoxidation methods, the present inventors have found that Ti deoxidation (hereinafter abbreviated as Al-less Ti deoxidation) steel in which Al is extremely reduced is a thin plate. It has been found that the material has very good characteristics and the surface defects of the manufactured thin plate can be reduced.
【０００５】しかしながらＡｌレスＴｉ脱酸の場合、Ａ
ｌ脱酸以上に、取鍋ノズルや浸漬ノズルの閉塞が発生し
やすく、このような鋼の多量生産が困難であり、表面疵
の発生が非常に少ないＡｌレスＴｉ脱酸による薄板の多
量生産を実現するには、ノズル閉塞の発生を如何にして
防止するか、その対策が必要であった。However, in the case of Al-less Ti deoxidation, A
More than deoxidation, ladle nozzles and dipping nozzles are more likely to be clogged, making it difficult to mass produce such steel, and to produce thin plates with Al-less Ti deoxidation with very few surface defects. In order to realize it, it was necessary to take measures to prevent the occurrence of nozzle blockage.
【０００６】[0006]
【発明が解決しようとする課題】従って、薄板の表面欠
陥の低減が可能で、材質特性も良好なＡｌレスＴｉ脱酸
による薄板材を多量生産を実現するには、ノズル閉塞防
止方法を確立するのが当面の解決すべき重要課題であ
る。Therefore, in order to realize the mass production of thin plate material by Al-less Ti deoxidation, which is capable of reducing the surface defects of the thin plate and has good material characteristics, a nozzle clogging prevention method is established. Is an important issue to be solved for the time being.
【０００７】[0007]
【課題を解決するための手段】本発明の要旨とするとこ
ろは下記のとうりである。
（１）重量％で、Ａｌ：０．０１％以下、Ｔｉ：０．０
２〜０．１５％からなる鋼の連続鋳造において、タンデ
ィシュ溶湯の全酸素量を下記（１）式の範囲にすること
を特徴とするＡｌレスＴｉ脱酸鋼のノズル閉塞防止法。
Ｏ＜９５３．４／Ｔ0.509 ＋５ ・・・（１）
ただし、Ｔ：１つのノズルで鋳造する溶湯量（ｔ）
Ｏ：１つのノズルでＴ（ｔ）の鋳造を可能にするタンディシュ溶湯の
全酸素量（ｐｐｍ）
（２）重量％で、Ａｌ：０．０１％以下、Ｔｉ：０．０
２〜０．１５％からなる鋼の連続鋳造において、製品の
全酸素量を下記（２）式の範囲にすることを特徴とする
ＡｌレスＴｉ脱酸鋼のノズル閉塞防止法。
Ｏ′＜７７２．８／Ｔ0.482 ・・・（２）
ただし、Ｔ：１つのノズルで鋳造する溶湯量（ｔ）
Ｏ′：１つのノズルでＴ（ｔ）の鋳造を可能にする製品の分析全酸素量
（ｐｐｍ）The gist of the present invention is as follows. (1) Weight%, Al: 0.01% or less, Ti: 0.0
A method for preventing nozzle clogging of Al-less Ti deoxidized steel, characterized in that the total oxygen content of the tundish melt is set within the range of the following formula (1) in the continuous casting of steel composed of 2 to 0.15%. O <953.4 / T 0.509 +5 (1) However, T: the amount of molten metal cast by one nozzle (t) O: the total amount of tundish molten metal that enables casting of T (t) with one nozzle Oxygen amount (ppm) (2) wt%, Al: 0.01% or less, Ti: 0.0
A method for preventing nozzle clogging of Al-less Ti deoxidized steel, characterized in that the total oxygen content of the product is set within the range of the following formula (2) in the continuous casting of steel consisting of 2 to 0.15%. O '<772.8 / T 0.482 (2) where T: amount of molten metal cast by one nozzle (t) O': analysis of a product that enables casting of T (t) with one nozzle Total oxygen amount (ppm)
【０００８】[0008]
【作用および実施例】図１に表１の化学成分からなる極
低炭素鋼を、アルミナグラファイト質ノズルで連続鋳造
した場合に、ノズル１の内面に成長する地金２の発生実
態の一部を拡大してその概略を示した。ノズル１の内面
には地金２が成長しており、この地金２をミクロ観察し
た結果、地金２の中には微細な介在物が多量に観察さ
れ、クラスターを形成していた。[Operations and Examples] FIG. 1 shows a part of the actual state of generation of the metal 2 growing on the inner surface of the nozzle 1 when the ultra-low carbon steel composed of the chemical components shown in Table 1 is continuously cast with the alumina graphite nozzle. It is enlarged to show its outline. A metal 2 has grown on the inner surface of the nozzle 1. As a result of microscopically observing the metal 2, a large amount of fine inclusions were observed in the metal 2, forming clusters.
【０００９】[0009]
【表１】 [Table 1]
【００１０】本発明者らは、このクラスターとクラスタ
ー含有地金２の特徴をさらに調査研究した結果、このク
ラスターはクラスター生成物質として良く知られている
Ａｌ2 Ｏ3 ではなく、図２のＸ線回折結果に示すごと
く、Ａｌを若干含有したＴｉ3Ｏ5 で、投入Ａｌ量を少
なくしたＡｌレスＴｉ脱酸鋼の場合、介在物がＴｉ系介
在物であることを確認した。As a result of further investigation and study on the characteristics of this cluster and the cluster-containing ingot 2, the present inventors found that this cluster is not Al 2 O 3 which is well known as a cluster-forming substance, but the X-ray of FIG. As shown in the diffraction result, in the case of Al-less Ti deoxidized steel in which Ti 3 O 5 containing a small amount of Al and the input Al amount was reduced, it was confirmed that the inclusions were Ti-based inclusions.
【００１１】また、このクラスター含有地金２は加熱炉
内で融点以上に加熱しても、その形が崩れず、付着地金
は微細なＴｉ系介在物が粒間にスポンジに含む水のごと
く、溶湯を保持しながら成長・凝固して、ノズル閉塞の
多くがこのことが原因で発生することを確認するに至っ
た。さらに調査研究を進めた結果、溶湯を保持したクラ
スターの成長のきっかけは、ノズル内面に発生する凸部
であり、この凸部が凸部近傍の溶湯の流れを撹乱し、そ
の結果、溶湯に懸濁している、微細な介在物のノズル壁
への衝突・捕捉頻度が増大し、クラスター含有地金の成
長に至ることを知見するに至った。なおノズル内面に発
生する凸部はノズルに含まれる酸化能の高い成分や、繰
り返し使用のためノズル１の内面に発生している酸化物
と溶湯が反応することにより反応生成する。The cluster-containing metal 2 does not lose its shape even if it is heated to a temperature higher than its melting point in a heating furnace, and the adhered metal 2 has fine Ti-based inclusions in the interstitial grains like water contained in a sponge. It has been confirmed that many of the nozzle blockages are caused by this by growing and solidifying while holding the molten metal. As a result of further investigation and research, the reason for the growth of the cluster holding the molten metal was the convex portion generated on the inner surface of the nozzle, and this convex portion disturbs the molten metal flow near the convex portion, and as a result, it is suspended in the molten metal. We have found that the frequency of collision and capture of turbid, minute inclusions on the nozzle wall increases, leading to the growth of cluster-containing ingots. It should be noted that the convex portion generated on the inner surface of the nozzle is generated by a reaction between a component having a high oxidizing ability contained in the nozzle and an oxide generated on the inner surface of the nozzle 1 for repeated use and the molten metal.
【００１２】本発明者らは、このような知見に基づきＡ
ｌレスＴｉ脱酸鋼の安定な多量製造法をさらに研究し
た。図３はノズル閉塞が発生する鍋ノズル近傍の概略図
であり、図中３は下部ノズル、４はスライディングノズ
ル、６は上ノズル、５はロングノズル（浸漬ノズル）、
７は取鍋である。図４は図３の下部ノズル３やタンディ
シュの浸漬ノズル５の材質として、アルミナグラファイ
ト質を採用した場合の鋳造可能な溶湯量と、タンディシ
ュで採取した試料中の介在物酸素量の関係を示したもの
である。Based on such knowledge, the present inventors
The stable mass production method of l-less Ti deoxidized steel was further studied. FIG. 3 is a schematic view of the vicinity of a pan nozzle in which nozzle clogging occurs. In the drawing, 3 is a lower nozzle, 4 is a sliding nozzle, 6 is an upper nozzle, 5 is a long nozzle (immersion nozzle),
7 is a ladle. FIG. 4 shows the relationship between the amount of meltable metal that can be cast when alumina graphite is used as the material of the lower nozzle 3 and the immersion nozzle 5 of the tundish of FIG. 3 and the amount of inclusion oxygen in the sample collected in the tundish. It is a thing.
【００１３】なお介在物酸素量は下記（３）式で計算
し、鋳造可能な溶湯量は製品欠陥の原因となるストッパ
ーや、スライディングノズルの開度の異常で判定した。
介在物酸素量＝分析した全酸素量−平衡溶解酸素量＊ ・・・（３）
ただし、＊平衡溶解酸素量：Ｔｉ3 Ｏ5 の活量＝１とし
て、Ｔｉ量等に基づき平衡計算で算出した５ｐｐｍを採
用The amount of inclusion oxygen was calculated by the following equation (3), and the amount of melt that can be cast was determined by the stopper that causes product defects and the opening of the sliding nozzle. Inclusion oxygen amount = total oxygen content was analyzed - the equilibrium dissolved oxygen content * (3) where * the equilibrium dissolved oxygen content: as an active amount = 1 Ti 3 O 5, calculated by equilibrium calculation based on the amount of Ti or the like Adopted 5ppm
【００１４】図４の結果によると溶湯量に応じ完鋳を可
能にする介在物酸素量が存在して、完鋳を実現するには
（１）式を満足すればよいことが判る。
Ｏ＜９５３．４／Ｔ0.509 ＋５ ・・・（１）
ただし、Ｔ：１つのノズルで鋳造する溶湯量（ｔ）
Ｏ：１つのノズルでＴ（ｔ）の鋳造を可能にするタンデ
ィシュ溶湯の全酸素量（ｐｐｍ）From the results shown in FIG. 4, it is understood that there is an amount of inclusion oxygen that enables complete casting depending on the amount of molten metal, and it is sufficient to satisfy the formula (1) to realize complete casting. O <953.4 / T 0.509 +5 (1) However, T: Amount of molten metal cast by one nozzle (t) O: Total Tundish molten metal that enables casting of T (t) by one nozzle Oxygen amount (ppm)
【００１５】（１）式によれば、例えば３００（ｔ）の
溶湯をノズル閉塞なく完鋳するには、溶湯の介在物酸素
量を５０ｐｐｍ以下にする必要がある。さらに連々鋳の
場合、浸漬ノズルは１つのノズルで多量な溶湯を鋳造す
る必要があり、タンディシュ溶湯の介在物酸素量はさら
に少なくする必要がある。According to the equation (1), for example, in order to completely cast a molten metal of 300 (t) without closing the nozzle, the oxygen content of inclusions in the molten metal needs to be 50 ppm or less. Further, in the case of continuous casting, it is necessary to cast a large amount of molten metal with one nozzle as the immersion nozzle, and it is necessary to further reduce the amount of oxygen contained in the tundish molten metal .
【００１６】図５は製品の分析全酸素量と１つのノズル
で鋳造可能な溶湯量の関係を示したものである。製品の
全酸素量で整理した場合、鋳造可能な溶湯量は（２）式
で整理することができ、完鋳を実現するには（２）式を
満足すればよいことが判る。
Ｏ′＜７７２．８／Ｔ0.482 ・・・（２）
ただし、Ｔ：１つのノズルで鋳造する溶湯量（ｔ）
Ｏ′：１つのノズルでＴ（ｔ）の鋳造を可能にする製品
の分析全酸素量（ｐｐｍ）
以上のごとくＡｌレスＴｉ脱酸により極低炭素鋼を鋳造
した場合のノズル閉塞は溶湯の全酸素量を制限すること
により回避することが可能になった。FIG. 5 shows the relationship between the total amount of oxygen analyzed for a product and the amount of molten metal that can be cast with one nozzle. When the total amount of oxygen in the product is arranged, the amount of melt that can be cast can be arranged by the formula (2), and it is understood that the formula (2) should be satisfied in order to realize complete casting. O '<772.8 / T 0.482 (2) where T: amount of molten metal cast by one nozzle (t) O': analysis of a product that enables casting of T (t) with one nozzle Total oxygen content (ppm) As described above, nozzle clogging when casting ultra-low carbon steel by Al-less Ti deoxidation can be avoided by limiting the total oxygen content of the molten metal.
【００１７】[0017]
【発明の効果】以上のごとく本発明により、従来ノズル
閉塞により多量生産が困難であった、ＡｌレスＴｉ脱酸
鋼のノズル閉塞を防止し、薄板の表面欠陥の大幅な改善
が可能なＡｌレスＴｉ脱酸鋼の多量生産を可能にした。As described above, according to the present invention, it is possible to prevent the nozzle clogging of Al-less Ti deoxidized steel, which was difficult to mass-produce due to the conventional nozzle clogging, and to significantly improve the surface defects of the thin plate. Enables mass production of Ti deoxidized steel.
【図１】ＡｌレスＴｉ脱酸鋼をアルミナグラファイトノ
ズルで鋳造した場合のノズル内付着地金を示す一部拡大
図FIG. 1 is a partially enlarged view showing a metal adhered in a nozzle when an Al-less Ti deoxidized steel is cast by an alumina graphite nozzle.
【図２】付着地金から抽出した介在物のＸ線回折結果を
示す図FIG. 2 is a diagram showing an X-ray diffraction result of inclusions extracted from deposited metal.
【図３】取鍋とノズルの概略を示す図FIG. 3 is a diagram showing an outline of a ladle and a nozzle.
【図４】タンデシュの介在物酸素量と鋳造可能溶湯量の
関係を示す図FIG. 4 is a diagram showing the relationship between the amount of inclusion oxygen in the tundish and the amount of melt that can be cast.
【図５】製品の分析全酸素量と鋳造可能な溶湯量の関係
を示す図FIG. 5 is a diagram showing the relationship between the total amount of oxygen analyzed for a product and the amount of melt that can be cast.
１ ノズル ２ ノズル内面の付着地金 ３ 下部ノズル ４ スライディングノズル ５ ロングノズル ６ 上部ノズル ７ 取鍋 1 nozzle 2 Metal attached to the inner surface of the nozzle 3 Lower nozzle 4 sliding nozzles 5 long nozzle 6 Upper nozzle 7 ladle
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉井 健一 千葉県君津市君津１番地 新日本製鐵株 式会社 君津製鐵所内 (72)発明者 門矢 哲治 千葉県君津市君津１番地 新日本製鐵株 式会社 君津製鐵所内 (56)参考文献 特開 平６−299286（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B22D 11/11 B22D 11/00 B22D 11/10 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Yoshii, 1 Kimitsu, Kimitsu-shi, Chiba New Nippon Steel Co., Ltd. Inside the Kimitsu Works, Ltd. (72) Tetsuji Kadoya, Kimitsu, Chiba, Japan Kimitsu Works, Ltd. (56) References JP-A-6-299286 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) B22D 11/11 B22D 11/00 B22D 11 /Ten
Claims (2)
ｉ：０．０２〜０．１５％からなる鋼の連続鋳造におい
て、タンディシュ溶湯の全酸素量を下記（１）式の範囲
にすることを特徴とするＡｌレスＴｉ脱酸鋼のノズル閉
塞防止法。 Ｏ＜９５３．４／Ｔ0.509 ＋５ ・・・（１） ただし、Ｔ：１つのノズルで鋳造する溶湯量（ｔ） Ｏ：１つのノズルでＴ（ｔ）の鋳造を可能にするタンディシュ溶湯の 全酸素量（ｐｐｍ）1. By weight%, Al: 0.01% or less, T
i: Nozzle blockage prevention method for Al-less Ti deoxidized steel, characterized in that in continuous casting of steel consisting of 0.02 to 0.15%, the total oxygen content of the tundish melt is set within the range of the following formula (1) . O <953.4 / T 0.509 +5 (1) However, T: the amount of molten metal cast by one nozzle (t) O: the total amount of tundish molten metal that enables casting of T (t) with one nozzle Oxygen amount (ppm)
ｉ：０．０２〜０．１５％からなる鋼の連続鋳造におい
て、製品の全酸素量を下記（２）式の範囲にすることを
特徴とするＡｌレスＴｉ脱酸鋼のノズル閉塞防止法。 Ｏ′＜７７２．８／Ｔ0.482 ・・・（２） ただし、Ｔ：１つのノズルで鋳造する溶湯量（ｔ） Ｏ′：１つのノズルでＴ（ｔ）の鋳造を可能にする製品の分析全酸素量 （ｐｐｍ）2. Al: 0.01% or less by weight%, T
i: A nozzle clogging prevention method for Al-less Ti deoxidized steel, characterized in that, in continuous casting of steel consisting of 0.02 to 0.15%, the total oxygen content of the product is within the range of the following formula (2). O '<772.8 / T 0.482 (2) where T: amount of molten metal cast by one nozzle (t) O': analysis of a product that enables casting of T (t) with one nozzle Total oxygen amount (ppm)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11107395A JP3389368B2 (en) | 1995-04-13 | 1995-04-13 | Nozzle blockage prevention method for Al-less Ti deoxidized steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11107395A JP3389368B2 (en) | 1995-04-13 | 1995-04-13 | Nozzle blockage prevention method for Al-less Ti deoxidized steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08281391A JPH08281391A (en) | 1996-10-29 |
| JP3389368B2 true JP3389368B2 (en) | 2003-03-24 |
Family
ID=14551705
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11107395A Expired - Fee Related JP3389368B2 (en) | 1995-04-13 | 1995-04-13 | Nozzle blockage prevention method for Al-less Ti deoxidized steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3389368B2 (en) |
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1995
- 1995-04-13 JP JP11107395A patent/JP3389368B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08281391A (en) | 1996-10-29 |
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