JP2002249818A - Melting method of steel sheet for thin plate and slab cast using it - Google Patents
Melting method of steel sheet for thin plate and slab cast using itInfo
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- JP2002249818A JP2002249818A JP2001301618A JP2001301618A JP2002249818A JP 2002249818 A JP2002249818 A JP 2002249818A JP 2001301618 A JP2001301618 A JP 2001301618A JP 2001301618 A JP2001301618 A JP 2001301618A JP 2002249818 A JP2002249818 A JP 2002249818A
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Abstract
(57)【要約】
【課題】 本発明は、アルミナ系介在物を低減すると共
に、凝集合体を防止し溶鋼中に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。
【解決手段】 炭素濃度を０．０５質量％以下まで脱炭
した後、該溶鋼に脱酸材を添加し、溶鋼中の溶存酸素濃
度を０．００１質量％以上、０．０１５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。PROBLEM TO BE SOLVED: To reduce the amount of alumina-based inclusions, to prevent agglomeration and coalescence, and to finely disperse in molten steel, thereby to reliably prevent surface flaws in a low-carbon material for a thin steel sheet. An object of the present invention is to present a method for producing molten steel. SOLUTION: After decarbonizing to a carbon concentration of 0.05% by mass or less, a deoxidizing agent is added to the molten steel so that the dissolved oxygen concentration in the molten steel is 0.001% by mass or more and 0.015% by mass or less. This is a method for producing a low-carbon thin steel sheet, which comprises casting the adjusted molten steel.
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 producing a low carbon 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 Molten steel refined in a converter or a vacuum processing vessel contains a large amount of dissolved oxygen, and this excess oxygen is deoxidized by Al which is a strong deoxidizing element having a strong affinity for oxygen. It is generally done. However, Al generates alumina-based inclusions by deoxidation, and these aggregate and coalesce to form coarse alumina clusters. The alumina clusters cause surface flaws during the production of the steel sheet, and greatly deteriorate the quality of the thin steel sheet. In particular, low carbon molten steel, which is a material for thin steel sheets with a low carbon concentration and a high dissolved oxygen concentration after refining, has a very large amount of alumina clusters, an extremely high incidence of surface flaws, and a reduction in alumina-based inclusions. Countermeasures have become a major issue.
【０００３】これに対して、従来は特開平５−１０４２
１９号公報に記載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６３−１４９０５７号公報に記載の注入流を利用し
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
に開示されているように溶鋼を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提案されてい
る。On the other hand, in the prior art, Japanese Patent Laid-Open No. 5-1042
No. 19, a method for removing alumina-based inclusions by adding the flux for adsorbing inclusions to the surface of molten steel, or using an injection flow described in JP-A-63-149057 to remove CaO flux into molten steel. To thereby remove and adsorb alumina-based inclusions. On the other hand, as a method of not forming alumina-based inclusions instead of removing them, molten steel for thin steel sheets is disclosed in Japanese Patent Application Laid-Open No. 5-302112, in which molten steel is deoxidized with Mg and Al is hardly deoxidized. Has also been proposed.
【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 above-described method for removing alumina-based inclusions, it is very difficult to reduce the amount of alumina-based inclusions generated in a low-carbon molten steel to such an extent that surface flaws do not occur. difficult. In the case of Mg deoxidation that does not generate alumina-based 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. Requires a large amount of Mg, which is not a practical process in view of manufacturing costs.
【０００５】これらの問題を鑑み、本発明はアルミナ系
介在物を低減すると共に、凝集・合体を防止し溶鋼中に
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。[0005] In view of these problems, the present invention reduces the amount of alumina-based inclusions, prevents aggregation and coalescence, and finely disperses them in molten steel, thereby reliably preventing surface flaws. An object of the present invention is to present a method for producing molten steel.
【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）炭
素濃度を０．０５質量％以下まで脱炭した後、該溶鋼に
脱酸材を添加し、溶鋼中の溶存酸素濃度を０．００１質
量％以上、０．０１５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）炭素濃度を０．０５質量％以下まで脱炭し
た後、該溶鋼に脱酸材とＳを添加し、（溶鋼中の溶存酸
素濃度）＋０．４４×（溶鋼中のＳ濃度）を０．００１
質量％以上、溶存酸素濃度を０．０１５質量％以下、Ｓ
濃度を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）炭素濃度を０．０５質量％以下まで脱炭した後、
該溶鋼にＡｌを添加して脱酸し、溶鋼中の溶存酸素濃度
を０．００１質量％以上、０．０１５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）炭素濃度を０．０５質量％
以下まで脱炭した後、該溶鋼にＡｌとＳを添加し、（溶
鋼中の溶存酸素濃度）＋０．４４×（溶鋼中のＳ濃度）
を０．００１質量％以上、溶存酸素濃度を０．０１５質
量％以下、Ｓ濃度を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）電磁撹拌、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上記
（１）から（４）のいずれかに記載の低炭素薄鋼板の溶
製方法である。また、（６）上記（１）から（４）のい
ずれかの方法で溶製した溶鋼を、薄スラブに鋳造するこ
とを特徴とする低炭素薄鋼板の溶製方法である。また、
（７）上記（１）から（６）のいずれかの方法で溶製
し、連続鋳造して得られた鋳片において、直径０．５μ
ｍから３０μｍの微細酸化物が鋳片内に１０００個／mm
3 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用鋳片である。Means for Solving the Problems To solve the above problems, the present invention has the following constitution. That is, (1) after decarburizing the carbon concentration to 0.05% by mass or less, a deoxidizing agent is added to the molten steel, and the dissolved oxygen concentration in the molten steel is 0.001% by mass or more and 0.015% by mass or less. A low-carbon thin steel sheet, characterized by casting molten steel adjusted to a low temperature.
(2) After decarburizing the carbon concentration to 0.05% by mass or less, a deoxidizing agent and S are added to the molten steel, and (concentration of dissolved oxygen in the molten steel) + 0.44 × (S concentration in the molten steel) ) To 0.001
Mass% or more, dissolved oxygen concentration 0.015 mass% or less, S
A method for producing a low-carbon thin steel sheet, comprising casting molten steel having a concentration adjusted to 0.02% by mass or less. Also,
(3) After decarbonizing the carbon concentration to 0.05% by mass or less,
Al is added to the molten steel to be deoxidized, and a molten steel having a dissolved oxygen concentration adjusted to 0.001% by mass or more and 0.015% by mass or less is cast. It is a manufacturing method. Further, (4) the carbon concentration is set to 0.05% by mass.
After decarburizing to the following, Al and S were added to the molten steel, and (dissolved oxygen concentration in the molten steel) + 0.44 × (S concentration in the molten steel)
A low-carbon thin steel sheet, wherein the molten steel is adjusted to 0.001% by mass or more, the dissolved oxygen concentration to 0.015% by mass or less, and the S concentration to 0.02% by mass or less. . (5) The method for producing a low-carbon thin steel sheet according to any one of (1) to (4), wherein the casting is performed using a mold having a function of applying electromagnetic stirring or an electromagnetic field. (6) A low carbon thin steel sheet melting method characterized by casting molten steel melted by any one of the above methods (1) to (4) into a thin slab. Also,
(7) A slab obtained by melting and continuous casting according to any one of the above (1) to (6) has a diameter of 0.5 μm.
Minute oxide of m to 30 μm is 1000 pieces / mm in slab
It is a slab for continuous casting characterized in that 3 or more and less than 100000 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
０．０５質量％以下とした溶鋼に脱酸材を添加して、溶
存酸素濃度を０．００１〜０．０１５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
細な介在物を溶鋼中に分散させることにある。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the smelting method of the present invention, a deoxidizing material is added to molten steel having a carbon concentration of 0.05% by mass or less by refining in a steelmaking furnace such as a converter or an electric furnace, or further performing vacuum degassing or the like. The dissolved oxygen concentration is adjusted to be 0.001 to 0.015% by mass. The basic idea of this smelting method is to leave dissolved oxygen that does not generate CO gas by reacting with C during casting.
By controlling the interfacial energy between the molten steel and the inclusions by the dissolved oxygen, the agglomeration and coalescence of the inclusions is suppressed, and the fine inclusions are dispersed in the 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。[0008] Molten steel decarburized in a converter or a vacuum processing vessel contains a large amount of dissolved oxygen, and this dissolved oxygen is usually almost deoxidized by the addition of Al (formula (1)). As a result, a large amount of alumina-based inclusions are generated.
【０００９】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Ａｌ
を添加すれば、溶存酸素量に相当する分だけアルミナ系
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、溶存酸素が残っている溶鋼中でアルミナ系介
在物の凝集挙動を実験的に評価したところ、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、アルミナ系介在物の凝集合体が抑制され、溶鋼
中に微細なアルミナ系介在物が分散することを見いだし
た。2Al + 3O = Al 2 O 3 (1) These alumina-based inclusions aggregate with each other immediately after deoxidation to form coarse alumina-based inclusions, which cause surface defects during steel sheet production. However, Al
Is added, the amount of alumina-based inclusions can be reduced by an amount corresponding to the amount of dissolved oxygen. Furthermore, the present inventors experimentally evaluated the aggregation behavior of alumina-based inclusions in molten steel in which dissolved oxygen remained, and found that when the dissolved oxygen concentration was increased to 0.001% by mass or more, the dissolved oxygen concentration increased. In addition, it was found that coagulation and coalescence of alumina-based inclusions was suppressed, and fine alumina-based inclusions were dispersed in molten steel.
【００１０】この理由は、溶存酸素が介在物と溶鋼間の
界面エネルギーを低下させ、介在物同士の凝集合体を抑
制したためである。また、溶鋼中のＳも介在物と溶鋼間
の界面エネルギーを低下させ、介在物の凝集合体を抑制
することを見いだしており、溶存酸素の一部をＳで置き
換えることも可能である。The reason for this is that the dissolved oxygen reduces the interfacial energy between the inclusions and the molten steel, and suppresses the agglomeration and coalescence of the inclusions. In addition, it has been found that S in molten steel also lowers interfacial energy between inclusions and molten steel and suppresses agglomeration and coalescence of inclusions, and it is possible to replace a part of dissolved oxygen with S.
【００１１】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１０００
００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。When the dispersion state of inclusions in the slab obtained by the present invention was evaluated, the diameter was 0.5 μm to 30 μm.
1000 fine particles / m 3 or more in the slab
Less than 00 particles / m 3 were dispersed, and no surface defects occurred after rolling in the slab having such an oxide dispersion state. From the above results, the present invention reduces the amount of inclusions,
In addition, since inclusions can be finely dispersed in the molten steel, the inclusions do not cause surface flaws during the production of the steel sheet, and the quality of the thin steel sheet is greatly improved.
【００１２】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 a thin plate is used for an application in which processing such as an automobile outer panel is severe, it is necessary to add workability. Therefore, the C concentration is 0.05% by mass or less, preferably 0.01%.
It is good to make it below mass%.
【００１３】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。If the molten steel containing a large amount of dissolved oxygen is cast without deoxidization after the decarburization treatment, CO bubbles are generated at the time of solidification, and the castability is greatly reduced. For this reason, conventionally, Al
Such deoxidizing materials were added to the molten steel after the decarburization treatment, and the molten steel was deoxidized to such an extent that almost no dissolved oxygen remained. However, since the C concentration is low in a steel sheet for a sheet requiring workability, even if a certain amount of dissolved oxygen remains, the reaction of generating CO bubbles represented by the formula (2) during casting is unlikely to occur.
【００１４】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
造機に鋳型内電磁撹拌装置が装備されるようになってお
り、凝固時に溶鋼を撹拌すれば、より高い溶存酸素を残
してもＣＯ気泡は鋳片に捕捉されない。このため、Ｃ濃
度が０．０５質量％以下の薄鋼板用の溶鋼では、０．０
１５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０．０１５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。C + O = CO (2) The limit dissolved oxygen concentration at which no CO bubbles are generated is about 0.006% by mass at a C concentration of 0.04% by mass, and 0.
At 0.01% by mass, it becomes about 0.01% by mass. Further, in ultra-low carbon steel having a low C concentration, even if dissolved oxygen is left up to about 0.015% by mass, no CO bubbles are generated. Recently, a continuous casting machine has been equipped with an in-mold electromagnetic stirring device. If molten steel is stirred during solidification, CO bubbles are not captured in the slab even if higher dissolved oxygen is left. Therefore, in molten steel for thin steel sheets having a C concentration of 0.05% by mass or less, 0.0%
Casting can be performed with dissolved oxygen remaining up to about 15% by mass. Conversely, when the dissolved oxygen concentration exceeds 0.015% by mass, CO bubbles are generated even in molten steel for thin steel sheets.
【００１５】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が殆ど低下せず、介在物同士の凝
集合体が進み、介在物が粗大化する。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。Ｓも溶存酸素と同様に
介在物同士の凝集合体を抑制する効果を有しているため
に、溶存酸素の一部をＳで置き換えることができる。こ
の場合、Ｓは溶存酸素に比べて介在物の凝集合体抑制効
果が弱く、相当溶存酸素濃度は（溶存酸素濃度）＋０．
４４×（Ｓ濃度）で評価できることを実験的に明らかに
した。このため、Ｓを用いる場合は、上記相当溶存酸素
濃度を０．００１質量％以上にすれば良い。反対に、Ｓ
濃度が高くなり過ぎると圧延時にへげ疵が発生するた
め、Ｓ濃度は０．０２質量％以下にしておく必要があ
る。When the concentration of dissolved oxygen decreases, the interfacial energy between the molten steel and the inclusions hardly decreases, the agglomeration of the inclusions proceeds, and the inclusions become coarse. In an experimental study, to prevent inclusions from becoming coarse, 0.001 mass%
The above dissolved oxygen was required. Since S also has the effect of suppressing the aggregation and coalescence of inclusions, as in the case of dissolved oxygen, a part of dissolved oxygen can be replaced with S. In this case, S has a weaker effect of suppressing inclusions and coalescence of inclusions than dissolved oxygen, and the equivalent dissolved oxygen concentration is (dissolved oxygen concentration) +0.
It was clarified experimentally that the evaluation could be performed at 44 × (S concentration). Therefore, when S is used, the equivalent dissolved oxygen concentration may be set to 0.001% by mass or more. Conversely, S
If the concentration is too high, a flaw is generated during rolling, so the S concentration needs to be 0.02% by mass or less.
【００１６】本発明では、溶鋼中に溶存酸素を０．００
１質量％以上残す必要があるため、溶鋼中のＡｌ濃度に
は必然的に上限値が存在する。熱力学的な計算では、１
６００℃の溶鋼温度で溶存Ａｌ濃度を０．００５質量％
以下にする必要がある。In the present invention, the dissolved oxygen in the molten steel is 0.00
Since it is necessary to leave 1% by mass or more, there is necessarily an upper limit to the Al concentration in the molten steel. In thermodynamic calculations, 1
0.005 mass% dissolved Al concentration at 600 ° C molten steel temperature
It must be:
【００１７】本発明は、通常の２５０mm厚み程度のスラ
ブ鋳造に適用されるだけでなく、連続鋳造機の鋳型厚み
がそれより薄い、例えば１５０mm厚み以下の薄スラブ鋳
造に対しても十分な効果を発現し、極めて表面疵の少な
い薄スラブ鋳片を得ることができる。The present invention can be applied not only to ordinary slab casting having a thickness of about 250 mm, but also to a sufficient effect for casting a thin slab having a thickness of less than 150 mm, for example, a continuous casting machine. A thin slab slab which manifests and has very few surface flaws can be obtained.
【００１８】[0018]
【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。 ＜実施例１＞転炉での精錬と還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Ａｌで脱酸し、Ａｌ濃度を０．０００２
質量％、溶存酸素濃度を０．０１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。 ＜実施例２＞転炉での精錬により炭素濃度を０．０４質
量％とした３００ｔの取鍋内溶鋼をＡｌで脱酸し、Ａｌ
濃度を０．０００６質量％、溶存酸素濃度を０．００４
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８５
００mm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。 ＜実施例３＞転炉での精錬と還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
の取鍋内溶鋼にＡｌとＳを添加し、Ａｌ濃度を０．００
６質量％、溶存酸素濃度を０．０００９質量％、Ｓ濃度
を０．０１５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、表面欠陥は発生しなかった。 ＜比較例＞転炉での精錬と還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０．０００２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。The present invention will be described below with reference to examples and comparative examples. <Example 1> 300 tons of carbon concentration of 0.003 mass% by refining in a converter and treatment in a reflux type vacuum degasser
The molten steel in the ladle is deoxidized with Al and the Al concentration is reduced to 0.0002.
% By mass and the dissolved oxygen concentration was 0.01% by mass. This molten steel was cast into a slab having a thickness of 250 mm and a width of 1800 mm by a continuous casting method. The cast slab is cut to 8500mm length,
One coil unit was used. The slab thus obtained is hot-rolled and cold-rolled by a conventional method.
A cold-rolled steel sheet having a thickness of 7 mm and a coil width of 1800 mm was used. Regarding the slab quality, visual observation was performed on an inspection line after cold rolling, and the number of surface defects generated per coil was evaluated. As a result, no surface defects occurred. <Example 2> 300 t of molten steel in a ladle with a carbon concentration of 0.04 mass% was deoxidized with Al by refining in a converter.
Concentration of 0.0006 mass%, dissolved oxygen concentration of 0.004
% By mass. This molten steel is 250mm thick by continuous casting,
It was cast into a slab having a width of 1800 mm. The cast slab is 85
It was cut to a length of 00 mm to make one coil unit. The slab thus obtained was hot-rolled and cold-rolled by a conventional method to finally obtain a cold-rolled steel sheet having a thickness of 0.7 mm and a coil width of 1800 mm. Regarding the slab quality, visual observation was performed on an inspection line after cold rolling, and the number of surface defects generated per coil was evaluated. As a result, no surface defects occurred. <Example 3> 300 tons of carbon concentration of 0.003 mass% by refining in a converter and treatment in a reflux type vacuum degassing apparatus
Al and S were added to the molten steel in the ladle of
6 mass%, dissolved oxygen concentration was 0.0009 mass%, and S concentration was 0.015 mass%. This molten steel was cast into a slab having a thickness of 250 mm and a width of 1800 mm by a continuous casting method. The cast slab was cut to a length of 8500 mm and made into 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 cold-rolled steel sheet having a 0 mm coil was used. Regarding the slab quality, visual observation was performed on an inspection line after cold rolling, and the number of surface defects generated per coil was evaluated. As a result, no surface defects occurred. <Comparative Example> Molten steel in a ladle with a carbon concentration of 0.003% by mass was deoxidized with Al by refining in a converter and treatment with a reflux type vacuum degassing device. The oxygen concentration was 0.0002% by mass. This molten steel was cast into a slab having a thickness of 250 mm and a width of 1800 mm by a continuous casting method. The cast slab was cut to a length of 8500 mm and made into 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 cold-rolled steel sheet having a 0 mm coil was used. Regarding the slab quality, visual observation was performed on an inspection line after cold rolling, and the number of surface defects generated per coil was evaluated. As a result, surface defects of 5 pieces / coil were generated on the average of the slab.
【００１９】[0019]
【発明の効果】以上に説明したように、本発明による
と、溶鋼中のアルミナ系介在物を低減し、その上で溶鋼
中にアルミナ系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, alumina-based inclusions in molten steel can be reduced, and alumina-based inclusions can be finely dispersed in the molten steel. It becomes possible to smelt a low carbon molten steel for a thin steel sheet which is excellent in workability and formability capable of preventing flaws.
───────────────────────────────────────────────────── 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） Ｃ２１Ｃ 7/06 Ｃ２１Ｃ 7/06 Ｆターム(参考） 4E004 MB07 MB12 NB01 NC01 4K013 AA09 BA02 BA08 BA14 BA16 CC06 CE01 CF12 CF13 DA03 DA09 DA12 DA13 EA19 FA02──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) C21C 7/06 C21C 7/06 F term (Reference) 4E004 MB07 MB12 NB01 NC01 4K013 AA09 BA02 BA08 BA14 BA16 CC06 CE01 CF12 CF13 DA03 DA09 DA12 DA13 EA19 FA02
Claims (7)
した後、該溶鋼に脱酸材を添加し、溶鋼中の溶存酸素濃
度を０．００１質量％以上、０．０１５質量％以下に調
製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. After decarbonizing to a carbon concentration of 0.05% by mass or less, a deoxidizing agent is added to the molten steel so that the concentration of dissolved oxygen in the molten steel is 0.001% by mass or more and 0.015% by mass or less. A method for producing a low-carbon thin steel sheet, comprising casting the molten steel prepared as described above.
した後、該溶鋼に脱酸材とＳを添加し、（溶鋼中の溶存
酸素濃度）＋０．４４×（溶鋼中のＳ濃度）を０．００
１質量％以上、溶存酸素濃度を０．０１５質量％以下、
Ｓ濃度を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. After decarburizing to a carbon concentration of 0.05% by mass or less, a deoxidizing agent and S are added to the molten steel, and (dissolved oxygen concentration in the molten steel) + 0.44 × (S concentration in the molten steel) ) To 0.00
1% by mass or more, dissolved oxygen concentration of 0.015% by mass or less,
A method for producing a low-carbon thin steel sheet, comprising casting a molten steel having an S concentration adjusted to 0.02% by mass or less.
した後、該溶鋼にＡｌを添加して脱酸し、溶鋼中の溶存
酸素濃度を０．００１質量％以上、０．０１５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. After decarburizing to a carbon concentration of 0.05% by mass or less, Al is added to the molten steel for deoxidation, and the concentration of dissolved oxygen in the molten steel is 0.001% by mass or more and 0.015% by mass. % Of low carbon steel sheet, characterized by casting molten steel adjusted to at most%.
した後、該溶鋼にＡｌとＳを添加し、（溶鋼中の溶存酸
素濃度）＋０．４４×（溶鋼中のＳ濃度）を０．００１
質量％以上、溶存酸素濃度を０．０１５質量％以下、Ｓ
濃度を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. After decarburizing to a carbon concentration of 0.05% by mass or less, Al and S are added to the molten steel to obtain (concentration of dissolved oxygen in molten steel) + 0.44 × (S concentration in molten steel). 0.001
Mass% or more, dissolved oxygen concentration 0.015 mass% or less, S
A method for producing a low carbon steel sheet, comprising casting molten steel having a concentration adjusted to 0.02% by mass or less.
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のいずれかの項に記載の低炭素薄鋼板の溶製方法。5. The method for producing a low-carbon thin steel sheet according to claim 1, wherein the casting is performed using a mold having a function of applying electromagnetic stirring or an electromagnetic field.
方法で溶製した溶鋼を、薄スラブに鋳造することを特徴
とする低炭素薄鋼板の溶製方法。6. A method for producing a low-carbon thin steel sheet, comprising casting molten steel produced by the method according to claim 1 into a thin slab.
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１０
００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用鋳片。7. In a slab obtained by smelting by the method according to any one of claims 1 to 6 and continuously casting, a fine oxide having a diameter of 0.5 μm to 30 μm is contained in the slab. 10
00 pieces / mm 3 or more, slab continuous casting, characterized in that it is dispersed less than 100,000 / mm 3.
Priority Applications (1)
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|---|---|---|---|
| JP2001301618A JP2002249818A (en) | 2000-10-12 | 2001-09-28 | Melting method of steel sheet for thin plate and slab cast using it |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000312102 | 2000-10-12 | ||
| JP2000-312102 | 2000-12-18 | ||
| JP2000-384227 | 2000-12-18 | ||
| JP2000384227 | 2000-12-18 | ||
| JP2001301618A JP2002249818A (en) | 2000-10-12 | 2001-09-28 | Melting method of steel sheet for thin plate and slab cast using it |
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| Publication Number | Publication Date |
|---|---|
| JP2002249818A true JP2002249818A (en) | 2002-09-06 |
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ID=27344920
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| Country | Link |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007009235A (en) * | 2005-06-28 | 2007-01-18 | Sumitomo Metal Ind Ltd | Steel plate with excellent workability and method for producing the same |
-
2001
- 2001-09-28 JP JP2001301618A patent/JP2002249818A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007009235A (en) * | 2005-06-28 | 2007-01-18 | Sumitomo Metal Ind Ltd | Steel plate with excellent workability and method for producing the same |
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