JP2003105431A - Method for preparing steel plate for thin sheet and its cast slab - Google Patents
Method for preparing steel plate for thin sheet and its cast slabInfo
- Publication number
- JP2003105431A JP2003105431A JP2001295878A JP2001295878A JP2003105431A JP 2003105431 A JP2003105431 A JP 2003105431A JP 2001295878 A JP2001295878 A JP 2001295878A JP 2001295878 A JP2001295878 A JP 2001295878A JP 2003105431 A JP2003105431 A JP 2003105431A
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- mass
- molten steel
- concentration
- low carbon
- steel sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Continuous Casting (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、加工性、成形性に
優れた低炭素薄鋼板の溶製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 a method for melting a low carbon thin steel sheet having excellent workability and formability.
【０００２】[0002]
【従来の技術】転炉や真空処理容器で精錬された溶鋼中
には、多量の溶存酸素が含まれており、この過剰酸素は
酸素との親和力が強い強脱酸元素であるＡｌにより脱酸
されるのが一般的である。しかし、Ａｌは脱酸によりア
ルミナ系介在物を生成し、これが凝集合体して粗大なア
ルミナクラスターとなる。このアルミナクラスターは鋼
板製造時に表面疵発生の原因となり、薄鋼板の品質を大
きく劣化させる。特に、炭素濃度が低く、精錬後の溶存
酸素濃度が高い薄鋼板用素材である低炭素溶鋼では、ア
ルミナクラスターの量が非常に多く、表面疵の発生率が
極めて高く、アルミナ系介在物の低減対策は大きな課題
となっている。2. Description of the Related Art A large amount of dissolved oxygen is contained in molten steel refined in a converter or a vacuum processing vessel, and this excess oxygen is deoxidized by Al, which is a strong deoxidizing element having a strong affinity with oxygen. It is generally done. However, Al produces alumina-based inclusions by deoxidation, and these are aggregated to form coarse alumina clusters. This alumina cluster causes surface defects during the production of the steel sheet and significantly deteriorates the quality of the thin steel sheet. In particular, low carbon molten steel, which is a material for thin steel sheets with low carbon concentration and high dissolved oxygen concentration after refining, has a very large amount of alumina clusters, extremely high surface flaw occurrence rate, and reduced alumina inclusions. Countermeasures have become a major issue.
【０００３】これに対して、従来は特開平５−１０４２
１９号公報の介在物吸着用フラックスを溶鋼表面に添加
してアルミナ系介在物を除去する方法、或いは特開昭６
３−１４９０５７号公報の注入流を利用してＣａＯフラ
ックスを溶鋼中に添加し、これによりアルミナ系介在物
を吸着除去する方法が提案、実施されてきた。一方、ア
ルミナ系介在物を除去するのではなく、生成させない方
法として、特開平５−３０２１１２号公報にあるように
溶鋼をＭｇで脱酸し、Ａｌでは殆ど脱酸しない薄鋼板用
溶鋼の溶製方法も開示されている。On the other hand, in the past, the conventional technique is Japanese Patent Laid-Open No. 5-1042.
The method of removing the alumina-based inclusions by adding the flux for adsorbing the inclusions of JP-A No. 19 to the surface of the molten steel, or JP-A-Sho 6
A method has been proposed and implemented in which a CaO flux is added to molten steel by utilizing the injection flow of Japanese Patent No. 3-149057, and thereby alumina inclusions are adsorbed and removed. On the other hand, as a method in which alumina inclusions are not removed, but not generated, as described in JP-A-5-302112, molten steel is deoxidized with Mg and Al is hardly deoxidized. Methods are also disclosed.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上述し
たアルミナ系介在物を除去する方法では、低炭素溶鋼中
に多量に生成したアルミナ系介在物を表面疵が発生しな
い程度まで低減することは非常に難しい。また、アルミ
ナ系介在物を全く生成しないＭｇ脱酸では、Ｍｇの蒸気
圧が高く、溶鋼への歩留まりが非常に低いため、低炭素
鋼のように溶存酸素濃度が高い溶鋼をＭｇだけで脱酸す
るには多量のＭｇを必要とし、製造コストを考えると実
用的なプロセスとは言えない。However, in the method of removing the alumina-based inclusions described above, it is extremely difficult to reduce the amount of the alumina-based inclusions generated in the low carbon molten steel to the extent that surface flaws do not occur. difficult. In addition, in Mg deoxidation that does not generate alumina inclusions at all, since the vapor pressure of Mg is high and the yield to molten steel is very low, molten steel with a high dissolved oxygen concentration such as low carbon steel is deoxidized with Mg alone. In order to do so, a large amount of Mg is required, which is not a practical process considering the manufacturing cost.
【０００５】これらの問題を鑑み、本発明は溶鋼中の介
在物を低減すると共に、凝集・合体を防止し溶鋼中に介
在物を微細分散させることにより、確実に表面疵を防止
できる薄鋼板用素材の低炭素溶鋼を溶製する方法を提示
することを課題とする。In view of these problems, the present invention reduces the inclusions in the molten steel, prevents aggregation and coalescence, and finely disperses the inclusions in the molten steel, thereby making it possible to reliably prevent surface flaws. It is an object of the present invention to present a method for producing low carbon molten steel as a raw material.
【０００６】[0006]
【課題を解決するための手段】上記課題を解決するため
に、本発明は以下の構成を要旨とする。即ち、（１）低
炭素薄鋼板の溶製方法において、炭素濃度を０．０１質
量％以下まで脱炭した後、該溶鋼にＬａを添加し、溶鋼
中の溶存酸素濃度を０．００１質量％以上、０．０２質
量％以下に調整した溶鋼を鋳造することを特徴とする低
炭素薄鋼板の溶製方法である。また、（２）低炭素薄鋼
板の溶製方法において、炭素濃度を０．０１質量％以下
まで脱炭した後、該溶鋼にＴｉとＬａを添加し、溶鋼中
の溶存酸素濃度を０．００１質量％以上、０．０２質量
％以下に調整した溶鋼を鋳造することを特徴とする低炭
素薄鋼板の溶製方法である。また、（３）低炭素薄鋼板
の溶製方法において、真空脱ガス処理により炭素濃度を
０．０１質量％以下まで脱炭した後、該溶鋼にＬａを添
加し、溶鋼中の溶存酸素濃度を０．００１質量％以上、
０．０２質量％以下に調整した溶鋼を鋳造することを特
徴とする低炭素薄鋼板の溶製方法である。また、（４）
低炭素薄鋼板の溶製方法において、真空脱ガス処理によ
り炭素濃度を０．０１質量％以下まで脱炭した後、該溶
鋼にＴｉとＬａを添加し、溶鋼中の溶存酸素濃度を０．
００１質量％以上、０．０２質量％以下に調整した溶鋼
を鋳造することを特徴とする低炭素薄鋼板の溶製方法で
ある。また、（５）低炭素薄鋼板の溶製方法において、
電磁攪拌、或いは電磁場を印加する機能を有する鋳型で
鋳造することを特徴とする請求項１から４記載の低炭素
薄鋼板の溶製方法である。また、（６）請求項１から５
の方法で溶製し、連続鋳造して得られた鋳片において、
直径０．５μｍから３０μｍの微細酸化物が鋳片内に１
０００個／ｍｍ3以上、１０００００個／ｍｍ3未満分散
していることを特徴とする連続鋳造鋳片である。In order to solve the above problems, the present invention has the following structures. That is, (1) in the method for producing a low carbon thin steel sheet, after decarburizing the carbon concentration to 0.01% by mass or less, La is added to the molten steel so that the dissolved oxygen concentration in the molten steel is 0.001% by mass. As described above, the molten steel adjusted to 0.02 mass% or less is cast, which is a method for melting a low carbon thin steel sheet. Further, (2) in the method for producing a low carbon thin steel sheet, after decarburizing the carbon concentration to 0.01% by mass or less, Ti and La are added to the molten steel so that the dissolved oxygen concentration in the molten steel is 0.001. It is a method for melting a low carbon thin steel sheet, which comprises casting molten steel adjusted to a mass% to 0.02 mass%. In addition, (3) in the method for producing a low carbon thin steel sheet, after decarburizing the carbon concentration to 0.01 mass% or less by vacuum degassing treatment, La is added to the molten steel to adjust the dissolved oxygen concentration in the molten steel. 0.001 mass% or more,
A method for melting a low carbon thin steel sheet is characterized by casting molten steel adjusted to 0.02 mass% or less. Also, (4)
In the melting method of a low carbon thin steel sheet, after decarburizing the carbon concentration to 0.01 mass% or less by vacuum degassing treatment, Ti and La are added to the molten steel to reduce the dissolved oxygen concentration in the molten steel to 0.
A method for melting a low carbon thin steel sheet is characterized by casting molten steel adjusted to 001% by mass or more and 0.02% by mass or less. In addition, (5) in the method of melting a low carbon thin steel sheet,
5. The method for producing a low carbon thin steel sheet according to claim 1, wherein the casting is performed with a mold having a function of applying electromagnetic stirring or an electromagnetic field. Further, (6) Claims 1 to 5
Melted by the method of, in the slab obtained by continuous casting,
Fine oxides with a diameter of 0.5 μm to 30 μm in the slab 1
It is a continuous cast slab characterized in that 000 pieces / mm 3 or more and less than 100,000 pieces / mm 3 are dispersed.
【０００７】[0007]
【発明の実施の形態】以下に本発明を詳細に説明する。
本発明の溶製法では、転炉や電気炉等の製鋼炉で精錬し
て、或いはさらに真空脱ガス処理等して、炭素濃度を
０．０１質量％以下とした溶鋼にＬａを添加して、溶存
酸素濃度を０．００１〜０．０２質量％になるように調
整する。この溶製法の基本思想は、鋳造時にＣと反応し
てＣＯガスを発生させない程度の溶存酸素を残し、この
溶存酸素により溶鋼とランタンオキサイド系介在物の界
面エネルギーを制御することにより、介在物同士の凝集
合体を抑制し、微細なランタンオキサイド系介在物を溶
鋼中に分散させることにある。BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
In the melting method of the present invention, La is added to molten steel having a carbon concentration of 0.01 mass% or less by refining in a steelmaking furnace such as a converter or an electric furnace, or by further performing vacuum degassing treatment, The dissolved oxygen concentration is adjusted to be 0.001 to 0.02 mass%. The basic idea of this melting method is to leave dissolved oxygen to the extent that it does not generate CO gas by reacting with C during casting, and control the interfacial energy between the molten steel and the lanthanum oxide-based inclusions by this dissolved oxygen, so that the inclusions The purpose is to suppress the agglomeration and coalescence of and to disperse fine lanthanum oxide-based inclusions in molten steel.
【０００８】転炉や真空処理容器で脱炭処理された溶鋼
中には、多量の溶存酸素が含まれており、この溶存酸素
は通常Ａｌの添加により殆ど脱酸される（（１）式の反
応）ため、多量のアルミナ系介在物を生成する。
２Ａｌ＋３Ｏ＝Ａｌ2Ｏ3 （１）
このアルミナ系介在物は脱酸直後からお互いに凝集合体
し、粗大なアルミナ系介在物となり、鋼板製造時に表面
欠陥の原因となる。しかし、溶存酸素を残すようにＬａ
を添加すれば、溶存酸素量に相当する分だけランタンオ
キサイド系介在物の生成量を低減することができる。さ
らに、本発明者らは、Ｌａ添加後の溶存酸素濃度を変化
させて、溶鋼中のランタンオキサイド系介在物の凝集挙
動を実験的に評価したところ、Ｌａで溶存酸素を殆ど脱
酸した状態でもランタンオキサイド系介在物はアルミナ
系介在物に比べて凝集合体が起こり難いこと、さらに溶
存酸素濃度を０．００１質量％以上にすると溶存酸素濃
度の増加と共に、ランタンオキサイド系介在物がさらに
微細化することを見いだした。この理由は、アルミナ系
介在物からランタンオキサイド系介在物に組成を変化さ
せること、さらに溶鋼中の溶存酸素濃度を高くすること
の両効果により、介在物と溶鋼間の界面エネルギーが大
きく低下し、介在物同士の凝集合体が抑制されたためで
ある。本発明によって得られた鋳片内の介在物分散状態
を評価したところ、直径０．５μｍから３０μｍの微細
酸化物を鋳片内に１０００個／ｍ3以上１０００００個
／ｍ3未満分散しており、このような酸化物分散状態を
有する鋳片では圧延後に表面欠陥は発生しなかった。以
上の結果から、本発明により介在物量を低減し、その上
で介在物を溶鋼中に微細分散させることができるため、
鋼板製造時に介在物は表面疵発生の原因とならず、薄鋼
板の品質は大きく向上する。A large amount of dissolved oxygen is contained in the molten steel that has been decarburized in a converter or a vacuum treatment vessel, and this dissolved oxygen is usually almost deoxidized by the addition of Al (equation (1)). Therefore, a large amount of alumina-based inclusions are generated. 2Al + 3O = Al 2 O 3 (1) These alumina-based inclusions agglomerate and coalesce with each other immediately after deoxidation, and become coarse alumina-based inclusions, which cause surface defects during steel sheet production. However, to leave dissolved oxygen, La
By adding, the amount of lanthanum oxide-based inclusions produced can be reduced by an amount corresponding to the amount of dissolved oxygen. Furthermore, the present inventors experimentally evaluated the agglomeration behavior of the lanthanum oxide-based inclusions in the molten steel by changing the dissolved oxygen concentration after the addition of La, and found that even when the dissolved oxygen was almost deoxidized in La. Lanthanum oxide-based inclusions are less likely to cause agglomeration and coalescence than alumina-based inclusions. Further, when the dissolved oxygen concentration is 0.001 mass% or more, the dissolved oxygen concentration is increased and the lanthanum-oxide-based inclusions are further miniaturized. I found a thing. The reason for this is that the interfacial energy between the inclusions and the molten steel is greatly reduced due to both effects of changing the composition from the alumina-based inclusions to the lanthanum oxide-based inclusions and further increasing the dissolved oxygen concentration in the molten steel, This is because the agglomeration of inclusions was suppressed. When the dispersed state of inclusions in the cast piece obtained by the present invention was evaluated, it was found that fine oxides having a diameter of 0.5 μm to 30 μm were dispersed in the cast piece in the range of 1000 / m 3 or more and less than 100000 / m 3. No surface defects occurred in the cast slab having such an oxide dispersed state after rolling. From the above results, it is possible to reduce the amount of inclusions and finely disperse the inclusions in the molten steel according to the present invention.
Inclusions do not cause surface defects during the production of steel sheets, and the quality of thin steel sheets is greatly improved.
【０００９】薄板用鋼板は、自動車用外板等の加工が厳
しい用途に用いられるため、加工性を付加する必要か
ら、Ｃ濃度を０．０５質量％以下、好ましくは０．０１
質量％以下にするのが良い。Since the steel sheet for thin plates is used for applications such as outer panels for automobiles where processing is severe, it is necessary to add workability, so the C concentration is 0.05 mass% or less, preferably 0.01%.
It is better to make it less than mass%.
【００１０】脱炭処理後に多量の溶存酸素を含む溶鋼を
脱酸せずにそのまま鋳造すると、凝固時にＣＯ気泡が発
生し、鋳造性が大きく低下する。このため、従来はＡｌ
等の脱酸材を脱炭処理後の溶鋼中に添加し、溶存酸素が
殆ど残らない程度まで溶鋼を脱酸していた。しかし、加
工性が求められる薄板用鋼板ではＣ濃度が低いため、或
程度の溶存酸素が残っていても、鋳造時に（２）式で示
されるＣＯ気泡発生の反応は起こり難い。
Ｃ＋Ｏ＝ＣＯ （２）
ＣＯ気泡が発生しない限界溶存酸素濃度は、Ｃ濃度が
０．０４質量％で０．００６質量％程度、Ｃ濃度が０．
０１質量％で０．０１質量％程度となり、さらにＣ濃度
の低い極低炭素鋼では０．０１５質量％程度まで溶存酸
素を残してもＣＯ気泡は発生しない。最近では、連続鋳
造機に鋳型内電磁攪拌装置が装備されるようになってお
り、凝固時に溶鋼を攪拌すれば、より高い溶存酸素、例
えば０．０２質量％程度まで残してもＣＯ気泡は鋳片に
捕捉されない。このため、Ｃ濃度が０．０１質量％以下
の薄鋼板用の溶鋼では、０．０２質量％程度まで溶存酸
素を残して鋳造することができ、反対に溶存酸素濃度が
０．０２質量％を超えると薄鋼板用の溶鋼でもＣＯ気泡
が発生してしまう。If molten steel containing a large amount of dissolved oxygen is cast as it is after decarburization without being deoxidized, CO bubbles will be generated during solidification, and the castability will be greatly reduced. Therefore, in the past, Al
Deoxidizing agents such as the above were added to the molten steel after the decarburization treatment to deoxidize the molten steel to such an extent that dissolved oxygen hardly remains. However, since the C concentration is low in a steel sheet for thin plates, which is required to have workability, even if some dissolved oxygen remains, the reaction of CO bubble generation shown in the formula (2) is unlikely to occur during casting. C + O = CO (2) The critical dissolved oxygen concentration at which CO bubbles are not generated is about 0.006% by mass at a C concentration of 0.04% by mass, and the C concentration is about 0.
When the content is 01% by mass, the content is about 0.01% by mass, and in an ultra-low carbon steel having a lower C concentration, CO bubbles are not generated even if dissolved oxygen is left up to about 0.015% by mass. Recently, a continuous casting machine has been equipped with an in-mold electromagnetic stirrer. If molten steel is stirred during solidification, higher dissolved oxygen, for example, CO bubbles can be cast even if about 0.02 mass% is left. Not caught in one piece. For this reason, molten steel for thin steel sheets having a C concentration of 0.01% by mass or less can be cast with dissolved oxygen remaining up to about 0.02% by mass, and conversely, a dissolved oxygen concentration of 0.02% by mass can be obtained. If it exceeds, CO bubbles will be generated even in molten steel for thin steel sheets.
【００１１】また、溶存酸素濃度が低くなると溶鋼と介
在物の界面エネルギーを大きく低下させることができ
ず、ランタンオキサイド系介在物であっても介在物同士
の凝集合体が徐々に進み、介在物が一部粗大化する。実
験的な検討では、介在物の粗大化を防止するには、０．
００１質量％以上の溶存酸素が必要であった。よって、
溶存酸素濃度を０．００１質量％から０．０２質量％に
限定した。Further, when the dissolved oxygen concentration becomes low, the interfacial energy between the molten steel and the inclusions cannot be greatly reduced, and even with the lanthanum oxide-based inclusions, the agglomeration and coalescence of the inclusions gradually progresses, and the inclusions are formed. Partly coarsen. According to an experimental study, in order to prevent the coarsening of inclusions,
Dissolved oxygen of 001 mass% or more was required. Therefore,
The dissolved oxygen concentration was limited to 0.001% by mass to 0.02% by mass.
【００１２】Ｌａの添加は介在物の微細化に効果的であ
るが、非常に強い脱酸材であるため、溶鋼中に多量に添
加すると、溶存酸素濃度が大きく低下し、本発明の介在
物微細化効果が損なわれる。このため、Ｌａは溶鋼中の
溶存酸素濃度を０．００１質量％から０．０２質量％残
せる範囲内で添加する必要がある。溶鋼中へのＬａの添
加は必ずしも高純度のＬａを使用する必要はなく、例え
ばミッシュメタルのような低純度のＬａ含有合金を使用
して十分な効果が得られる。また、薄板用鋼板では、鋼
板中の固溶Ｃを固定する必要から溶鋼中にＴｉを添加す
る場合がある。ＴｉはＬａと比べて脱酸力が弱いが、そ
れでも溶鋼中に多量に添加すると溶存酸素濃度を低下さ
せてしまう。このため、本発明では溶存酸素を０．００
１質量％から０．０２質量％残せる範囲で、Ｌａに加え
て更にＴｉを添加することができる。Although the addition of La is effective for refining inclusions, it is a very strong deoxidizer, so if a large amount is added to the molten steel, the dissolved oxygen concentration will drop significantly, and the inclusions of the present invention will The miniaturization effect is impaired. For this reason, La needs to be added within the range in which the dissolved oxygen concentration in the molten steel can remain from 0.001 mass% to 0.02 mass%. The addition of La to the molten steel does not necessarily need to use high-purity La, and a sufficient effect can be obtained by using a low-purity La-containing alloy such as misch metal. Further, in a steel sheet for thin plates, Ti may be added to the molten steel in some cases because it is necessary to fix the solid solution C in the steel sheet. Ti has a weaker deoxidizing power than La, but if it is added to molten steel in a large amount, it will reduce the dissolved oxygen concentration. Therefore, in the present invention, the dissolved oxygen content is 0.00
Ti can be further added in addition to La in a range where 1% by mass to 0.02% by mass can be left.
【００１３】本発明では、凝集合体し易いアルミナ系介
在物を生成させないように、溶鋼中にＡｌを添加しない
ことが望ましいが、必要な場合には微量Ａｌを添加する
ことは可能である。この場合、溶鋼中に溶存酸素を０．
００１質量％以上残す必要があり、熱力学的な計算によ
れば１６００℃で溶存Ａｌ濃度が０．００５質量％以下
であれば良い。In the present invention, it is desirable not to add Al to the molten steel so as to prevent the formation of alumina-based inclusions which tend to be aggregated and coalesced, but it is possible to add a trace amount of Al if necessary. In this case, the dissolved oxygen in the molten steel should be 0.
It is necessary to leave 001 mass% or more, and according to thermodynamic calculation, the dissolved Al concentration at 1600 ° C. should be 0.005 mass% or less.
【００１４】[0014]
【実施例】以下に、実施例及び比較例を挙げて、本発明
について説明する。EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples.
【００１５】実施例１
転炉での精錬と環流式真空脱ガス装置での処理により炭
素濃度を０．００３質量％とした３００ｔの取鍋内溶鋼
をＬａで脱酸し、Ｌａ濃度０．０００２質量％で溶存酸
素濃度を０．００１４質量％とした。この溶鋼を連続鋳
造法で厚み２５０ｍｍ、幅１８００ｍｍのスラブに鋳造
した。鋳造した鋳片は８５００ｍｍ長さに切断し、１コ
イル単位とした。このようにして得られたスラブは、常
法により熱間圧延、冷間圧延し、最終的には０．７ｍｍ
厚みで幅１８００ｍｍコイルの冷延鋼板とした。鋳片品
質については、冷間圧延後の検査ラインで目視観察を行
い、１コイル当たりに発生する表面欠陥の発生個数を評
価した。その結果、表面欠陥は発生しなかった。Example 1 300 t of molten steel in a ladle having a carbon concentration of 0.003 mass% by refining in a converter and treatment in a reflux type vacuum degasser was deoxidized with La to obtain a La concentration of 0.0002. The dissolved oxygen concentration was set to 0.0014 mass% in mass%. This molten steel was cast into a slab having a thickness of 250 mm and a width of 1800 mm by the continuous casting method. The cast slab was cut into a length of 8500 mm to make one coil unit. The slab thus obtained is hot-rolled or cold-rolled by a conventional method to finally obtain 0.7 mm.
The thickness was a cold-rolled steel sheet with a width of 1800 mm. Regarding the slab quality, the number of surface defects generated per coil was evaluated by visual observation on the inspection line after cold rolling. As a result, no surface defect was generated.
【００１６】実施例２
転炉での精錬と環流式真空脱ガス装置での処理により炭
素濃度を０．００３質量％とした３００ｔの取鍋内溶鋼
をＴｉおよびＬａで脱酸し、Ｔｉ濃度０．００８質量
％、Ｌａ濃度０．０００１質量％で溶存酸素濃度を０．
００２２質量％とした。この溶鋼を連続鋳造法で厚み２
５０ｍｍ、幅１８００ｍｍのスラブに鋳造した。鋳造し
た鋳片は８５００ｍｍ長さに切断し、１コイル単位とし
た。このようにして得られたスラブは、常法により熱間
圧延、冷間圧延し、最終的には０．７ｍｍ厚みで幅１８
００ｍｍコイルの冷延鋼板とした。鋳片品質について
は、冷間圧延後の検査ラインで目視観察を行い、１コイ
ル当たりに発生する表面欠陥の発生個数を評価した。そ
の結果、表面欠陥は発生しなかった。Example 2 300 t of ladle steel in a ladle having a carbon concentration of 0.003 mass% by refining in a converter and treatment in a reflux type vacuum degasser was deoxidized with Ti and La, and the Ti concentration was 0. Dissolved oxygen concentration was 0.008% by mass and La concentration was 0.0001% by mass.
It was set to 0022 mass%. This molten steel has a thickness of 2 by continuous casting.
It was cast into a slab having a width of 50 mm and a width of 1800 mm. The cast slab was cut into a length of 8500 mm to make one coil unit. The slab thus obtained is hot-rolled and cold-rolled by a conventional method, and finally has a thickness of 0.7 mm and a width of 18 mm.
It was a cold rolled steel plate with a 00 mm coil. Regarding the slab quality, the number of surface defects generated per coil was evaluated by visual observation on the inspection line after cold rolling. As a result, no surface defect was generated.
【００１７】比較例１
転炉での精錬と環流式真空脱ガス装置での処理により炭
素濃度を０．００３質量％とした取鍋内溶鋼をＡｌで脱
酸し、Ａｌ濃度０．０４質量％、溶存酸素濃度０．００
０２質量％とした。この溶鋼を連続鋳造法で厚み２５０
ｍｍ、幅１８００ｍｍのスラブに鋳造した。鋳造した鋳
片は８５００ｍｍ長さに切断し、１コイル単位とした。
このようにして得られたスラブは、常法により熱間圧
延、冷間圧延し、最終的には０．７ｍｍ厚みで幅１８０
０ｍｍコイルの冷延鋼板とした。鋳片品質については、
冷間圧延後の検査ラインで目視観察を行い、１コイル当
たりに発生する表面欠陥の発生個数を評価した。その結
果、スラブ平均で５個／コイルの表面欠陥が発生した。Comparative Example 1 Molten steel in a ladle having a carbon concentration of 0.003 mass% by refining in a converter and treatment in a reflux type vacuum degassing device was deoxidized with Al to obtain an Al concentration of 0.04 mass%. , Dissolved oxygen concentration 0.00
It was set to 02 mass%. This molten steel is continuously cast to a thickness of 250
mm, and a slab having a width of 1800 mm was cast. The cast slab was cut into a length of 8500 mm to make one coil unit.
The slab thus obtained is hot-rolled and cold-rolled by a conventional method, and finally has a thickness of 0.7 mm and a width of 180 mm.
A 0 mm coil cold-rolled steel sheet was used. For slab quality,
The number of surface defects generated per coil was evaluated by visual observation on the inspection line after cold rolling. As a result, 5 slabs / coil surface defects were generated.
【００１８】[0018]
【発明の効果】以上に説明したように、本発明による
と、溶鋼中の介在物を低減し、その上で溶鋼中に介在物
を微細分散させることができるため、確実に表面疵を防
止できる加工性、成形性に優れた薄鋼板用の低炭素溶鋼
を溶製することが可能となる。As described above, according to the present invention, inclusions in molten steel can be reduced and inclusions can be finely dispersed in the molten steel, so that surface defects can be reliably prevented. It becomes possible to produce a low-carbon molten steel for thin steel sheets, which has excellent workability and formability.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｂ２２Ｄ 11/00 Ｂ２２Ｄ 11/00 Ａ 11/04 ３１１ 11/04 ３１１Ｊ 11/108 11/108 Ｃ 27/02 27/02 Ｖ Ｃ２１Ｃ 7/00 Ｃ２１Ｃ 7/00 Ｈ 7/06 7/06 7/068 7/068 7/10 7/10 Ａ (72)発明者 大橋 渡 富津市新富20−１ 新日本製鐵株式会社技 術開発本部内 Ｆターム(参考） 4E004 MB12 NB01 NC01 4K013 AA07 AA09 BA08 BA14 CB00 CE01 CF13 EA18 EA26 FA02─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI theme code (reference) B22D 11/00 B22D 11/00 A 11/04 311 11/04 311J 11/108 11/108 C 27/02 27/02 V C21C 7/00 C21C 7/00 H 7/06 7/06 7/068 7/068 7/10 7/10 A (72) Inventor Watashi Ohashi 20-1 Shintomi, Futtsu City Nippon Steel Corporation Company Technology Development Division F-term (reference) 4E004 MB12 NB01 NC01 4K013 AA07 AA09 BA08 BA14 CB00 CE01 CF13 EA18 EA26 FA02
Claims (6)
濃度を０．０１質量％以下まで脱炭した後、該溶鋼にＬ
ａを添加し、溶鋼中の溶存酸素濃度を０．００１質量％
以上、０．０２質量％以下に調整した溶鋼を鋳造するこ
とを特徴とする低炭素薄鋼板の溶製方法。1. A method for smelting a low carbon thin steel sheet, which comprises decarburizing a carbon concentration to 0.01% by mass or less and then adding L to the molten steel.
a is added and the dissolved oxygen concentration in the molten steel is 0.001% by mass.
As described above, the method for melting a low carbon thin steel sheet is characterized by casting molten steel adjusted to 0.02 mass% or less.
濃度を０．０１質量％以下まで脱炭した後、該溶鋼にＴ
ｉとＬａを添加し、溶鋼中の溶存酸素濃度を０．００１
質量％以上、０．０２質量％以下に調整した溶鋼を鋳造
することを特徴とする低炭素薄鋼板の溶製方法。2. A method for melting a low-carbon thin steel sheet, which comprises decarburizing a carbon concentration to 0.01% by mass or less and then adding T to the molten steel.
i and La were added, and the dissolved oxygen concentration in the molten steel was adjusted to 0.001.
A method for melting a low carbon thin steel sheet, which comprises casting molten steel adjusted to a mass% to 0.02 mass%.
脱ガス処理により炭素濃度を０．０１質量％以下まで脱
炭した後、該溶鋼にＬａを添加し、溶鋼中の溶存酸素濃
度を０．００１質量％以上、０．０２質量％以下に調整
した溶鋼を鋳造することを特徴とする低炭素薄鋼板の溶
製方法。3. A method for producing a low carbon thin steel sheet, wherein decarburization is carried out by vacuum degassing to a carbon concentration of 0.01 mass% or less, and then La is added to the molten steel to adjust the dissolved oxygen concentration in the molten steel. A method for melting a low carbon thin steel sheet, which comprises casting molten steel adjusted to 0.001 mass% or more and 0.02 mass% or less.
脱ガス処理により炭素濃度を０．０１質量％以下まで脱
炭した後、該溶鋼にＴｉとＬａを添加し、溶鋼中の溶存
酸素濃度を０．００１質量％以上、０．０２質量％以下
に調整した溶鋼を鋳造することを特徴とする低炭素薄鋼
板の溶製方法。4. A method for producing a low carbon thin steel sheet, which comprises decarburizing a carbon concentration to 0.01 mass% or less by vacuum degassing, and then adding Ti and La to the molten steel to dissolve oxygen in the molten steel. A method for melting a low carbon thin steel sheet, which comprises casting molten steel having a concentration adjusted to 0.001 mass% or more and 0.02 mass% or less.
攪拌、或いは電磁場を印加する機能を有する鋳型で鋳造
することを特徴とする請求項１から４のいずれかに記載
の低炭素薄鋼板の溶製方法。5. The low carbon thin steel sheet according to any one of claims 1 to 4, wherein the low carbon thin steel sheet is melted by a mold having a function of applying electromagnetic stirring or an electromagnetic field. Method of melting.
し、連続鋳造して得られた鋳片において、直径０．５μ
ｍから３０μｍの微細酸化物が鋳片内に１０００個／ｍ
ｍ3以上、１０００００個／ｍｍ3未満分散していること
を特徴とする連続鋳造鋳片。6. A slab obtained by continuous casting, which is obtained by melting according to any one of claims 1 to 5, and has a diameter of 0.5 μm.
Fine oxides of m to 30 μm in the slab 1000 pieces / m
A continuously cast slab characterized in that m 3 or more and less than 100,000 pieces / mm 3 are dispersed.
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|---|---|---|---|
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|---|---|---|---|
| JP2001295878A JP4660037B2 (en) | 2001-09-27 | 2001-09-27 | Method for melting steel sheet for thin plate and cast piece thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005045083A1 (en) * | 2003-11-05 | 2005-05-19 | Nippon Steel Corporation | Thin steel sheet excelling in surface property, moldability and workability and process for producing the same |
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|---|---|---|---|---|
| JPS57118846A (en) * | 1981-01-14 | 1982-07-23 | Nippon Steel Corp | Production of continuously cast ingot |
| JPH08155613A (en) * | 1994-12-07 | 1996-06-18 | Nippon Steel Corp | Method for continuously casting molten metal |
| JPH11100611A (en) * | 1997-09-29 | 1999-04-13 | Kawasaki Steel Corp | Production of titanium-containing extra low carbon steel |
| JPH11343516A (en) * | 1998-03-30 | 1999-12-14 | Kawasaki Steel Corp | Titanium killed steel product having good surface property and its production |
-
2001
- 2001-09-27 JP JP2001295878A patent/JP4660037B2/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57118846A (en) * | 1981-01-14 | 1982-07-23 | Nippon Steel Corp | Production of continuously cast ingot |
| JPH08155613A (en) * | 1994-12-07 | 1996-06-18 | Nippon Steel Corp | Method for continuously casting molten metal |
| JPH11100611A (en) * | 1997-09-29 | 1999-04-13 | Kawasaki Steel Corp | Production of titanium-containing extra low carbon steel |
| JPH11343516A (en) * | 1998-03-30 | 1999-12-14 | Kawasaki Steel Corp | Titanium killed steel product having good surface property and its production |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005045083A1 (en) * | 2003-11-05 | 2005-05-19 | Nippon Steel Corporation | Thin steel sheet excelling in surface property, moldability and workability and process for producing the same |
| KR100889402B1 (en) * | 2003-11-05 | 2009-03-20 | 신닛뽄세이테쯔 카부시키카이샤 | Cast slab, hot rolled steel sheet, colled rolled annealing steel sheet of ultralow carbon steel and method for producing the colled rolled annealing steel sheet |
| US9017492B2 (en) | 2003-11-05 | 2015-04-28 | Nippon Steel & Sumitomo Metal Corporation | Thin gauge steel sheet excellent in surface conditions, formability, and workability and method for producing the same |
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| Publication number | Publication date |
|---|---|
| JP4660037B2 (en) | 2011-03-30 |
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