JPH06207212A - Production of high creanliness extra-low carbon steel of extremely low s - Google Patents
Production of high creanliness extra-low carbon steel of extremely low sInfo
- Publication number
- JPH06207212A JPH06207212A JP115693A JP115693A JPH06207212A JP H06207212 A JPH06207212 A JP H06207212A JP 115693 A JP115693 A JP 115693A JP 115693 A JP115693 A JP 115693A JP H06207212 A JPH06207212 A JP H06207212A
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- JP
- Japan
- Prior art keywords
- molten steel
- less
- steel
- slag
- treatment
- 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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- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、成形性に優れた自動車
用鋼板または電磁特性に優れた無方向性珪素鋼板を経済
的に大量溶製するプロセスの実現に必要とされる、清浄
度の高い、特にＳ含有量の極めて少ない極低炭素鋼の製
造方法に関する。BACKGROUND OF THE INVENTION The present invention relates to a cleanliness required for realizing a process for economically mass-producing an automobile steel sheet having excellent formability or a non-oriented silicon steel sheet having excellent electromagnetic characteristics. The present invention relates to a method for producing an extremely low carbon steel having a high S content, particularly an extremely low S content.
【０００２】[0002]
【従来の技術】近年、自動車用鋼板などの分野において
は、優れた成形性を得るために、高純度鋼の需要が大き
い。すなわち、Ｃ：0.0030wt％以下の極低炭素鋼板、さ
らにはＣ：0.0015wt％以下でかつＳ：0.0020wt％以下と
した、Ｓ含有量の極めて少ない高清浄度極低炭素鋼の要
望が大きく、それの大量溶製技術の確立が強く望まれて
いる。2. Description of the Related Art In recent years, in the field of automobile steel sheets and the like, there is a great demand for high-purity steel in order to obtain excellent formability. That is, there is a great demand for an ultra-low carbon steel sheet having a C content of 0.0030 wt% or less, and further for a C-0.0015 wt% or less and S: 0.0020 wt% or less high-cleanliness ultra-low carbon steel having an extremely low S content. , Establishment of mass-production technology for it is strongly desired.
【０００３】なかでも、自動車用の一体成形サイドパネ
ルに供する、伸び55％以上、ｒ値2.5 以上の高加工性自
動車用鋼板を得るには、Ｓ：0.0020wt％以下で、さらに
Ｃ：0.0010wt％以下とした、高清浄度極低炭素鋼を必要
とする。Above all, in order to obtain a highly workable steel sheet for automobiles having an elongation of 55% or more and an r value of 2.5 or more, which is to be used as an integrally molded side panel for automobiles, S: 0.0020 wt% or less, and further C: 0.0010 wt%. %, A high cleanliness ultra-low carbon steel is required.
【０００４】また、無方向性珪素鋼板、特にSi：2.5 wt
％以下およびAl：0.2 wt％以上の高級無方向性珪素鋼板
では、Ｓ含有量の極めて少ない極低炭素鋼を使用すると
飽和磁束密度が高くなり、かつ鉄損値が著しく低下する
ことが知られている。特に、高級無方向性鋼板ではＣ：
0.0015wt％以下およびＳ：0.0010wt％以下とすること
が、電磁特性を向上させる上でより好ましい。Also, non-oriented silicon steel sheet, especially Si: 2.5 wt
% Or less and Al: 0.2 wt% or more in high grade non-oriented silicon steel sheets, it is known that when extremely low carbon steel with an extremely low S content is used, the saturation magnetic flux density increases and the iron loss value decreases significantly. ing. Especially in the case of high grade non-oriented steel sheet, C:
It is more preferable that the content is 0.0015 wt% or less and S: 0.0010 wt% or less in order to improve electromagnetic characteristics.
【０００５】Ｃ：0.0015wt％以下の極低炭素鋼は、例え
ば出願人が先に特願平３−30100 号にて提案した、直径
の太い環流管を用いることにより溶鋼の環流を促進でき
るようにしたＲＨ脱ガス装置を用いて、製造することが
できる。一方、Ｓ：0.0020wt％以下の高清浄度鋼は、
“鉄と鋼”72(1986),S263 に開示されているような、Ｒ
Ｈ脱ガス時に環流管直下の取鍋内溶鋼に脱硫剤をインジ
ェクションする方法（ＲＨ−ＦＩ法）によって製造する
ことができる。しかし、この方法は浸漬ランスを必要と
するので耐火物コストが高く、また、望ましい極低硫値
を得るには、Ｃ：0.06wt％以上の低または中炭素鋼での
適用に限られてしまう問題があった。C: 0.0015 wt% or less of ultra-low carbon steel can be used, for example, to accelerate the recirculation of molten steel by using a thick diameter recirculation pipe proposed by the applicant in Japanese Patent Application No. 3-30100. Can be manufactured using the RH degassing device described above. On the other hand, S: 0.0020 wt% or less high cleanliness steel,
R as disclosed in "Iron and Steel" 72 (1986), S263.
It can be produced by a method (RH-FI method) of injecting a desulfurizing agent into molten steel in a ladle immediately below the reflux pipe during H 2 degassing. However, this method requires an immersion lance and thus has a high refractory cost, and in order to obtain a desired extremely low sulfur value, the application is limited to C: 0.06 wt% or more of low or medium carbon steel. There was a problem.
【０００６】[0006]
【発明が解決しようとする課題】精錬工程において極低
炭素鋼を得るためには、スラグの酸素ポテンシャルが高
い方が良く、従ってスラグ中の（Ｔ．Fe）も高い方が良
い。一方、Ｓ含有量の極めて少ない、かつ、Ｏ含有量が
低い高清浄度鋼を得るためには、スラグの酸素ポテンシ
ャルは低い方が良く、従ってスラグ中の（Ｔ．Fe）も低
くする必要がある。In order to obtain an ultra-low carbon steel in the refining process, it is better that the oxygen potential of the slag is higher, and therefore (T.Fe) in the slag is also higher. On the other hand, in order to obtain a high cleanliness steel having an extremely low S content and a low O content, it is better that the oxygen potential of the slag is low, and therefore (T.Fe) in the slag needs to be low. is there.
【０００７】すなわち、Ｓ含有量の低い高清浄度極低炭
素鋼の溶製は、極低炭素鋼および高清浄度鋼の溶製プロ
セスを単に組合わせるだけでは不十分である。この種の
高純度鋼の大量溶製を実現するには、高炉出銑後の溶銑
から転炉精錬および２次精錬に至る全プロセスにわたっ
て適正な条件を付与する必要がある。そこで、本発明の
目的は、Ｓ含有量の低い高清浄度の極低炭素鋼を有利に
得るための溶製プロセスを提案することにある。That is, in the melting of the high cleanliness ultra-low carbon steel having a low S content, it is not enough to simply combine the melting processes of the ultra-low carbon steel and the high cleanliness steel. In order to realize the large-scale melting of this type of high-purity steel, it is necessary to give appropriate conditions to all processes from the hot metal after blast furnace tapping to converter smelting and secondary smelting. Therefore, an object of the present invention is to propose a melting process for advantageously obtaining an ultra-low carbon steel having a low S content and a high cleanliness.
【０００８】[0008]
【課題を解決するための手段】本発明は、Ｐ：0.030 wt
％以下およびＳ：0.003 wt％以下に脱燐および脱硫処理
した溶銑を転炉にて精錬し、Ｃ：0.020 〜0.050 wt％お
よびＳ：0.0050wt％以下の溶鋼とした後、該溶鋼を取鍋
に出鋼中および／または出鋼後に金属Alを含むスラグ改
質剤を添加し、スラグ成分を（Ｔ．Fe）＋（MnO ）≦７
wt％を満足するように調整し、次いでＲＨ真空脱炭処理
を行った後、金属Alによる脱酸処理およびCaO を主成分
とするフラックスをCaO 換算で４kg／ｔ以上、ＲＨ真空
槽内の溶鋼に添加する脱硫処理を施し、溶鋼成分をＣ：
0.0030wt％以下およびＳ：0.0020wt％以下に調整するこ
とを特徴とするＳ含有量の極めて少ない高清浄度極低炭
素鋼の製造方法である。The present invention provides P: 0.030 wt.
% And S: 0.003 wt% or less of dephosphorized and desulfurized hot metal is refined in a converter to make C: 0.020 to 0.050 wt% and S: 0.0050 wt% or less of molten steel, and then ladle A slag modifier containing metallic Al during and / or after tapping is added to the steel, and the slag component is (T.Fe) + (MnO) ≦ 7.
After adjusting so that wt% is satisfied, and then performing RH vacuum decarburization treatment, deoxidation treatment with metallic Al and flux containing CaO as the main component is 4 kg / t or more in terms of CaO, molten steel in the RH vacuum tank Is subjected to desulfurization treatment to add molten steel components to C:
A method for producing a high cleanliness ultra-low carbon steel having an extremely low S content, characterized by adjusting the content to 0.0030 wt% or less and S: 0.0020 wt% or less.
【０００９】[0009]
【作用】本発明方法の実施に当たっては、転炉に装入す
る溶銑のＰおよびＳの含有量は低い方が望ましく、Ｐ：
0.030 wt％以下およびＳ：0.003 wt％以下とする。すな
わち、Ｐが0.030 wt％を超えると、転炉で装入する副原
料のCaO を多量に要し、精錬コストが嵩むばかりでな
く、Ｐを酸化除去するための酸素ガスの上吹き量も多く
なり、生成するスラグの（Ｔ．Fe）を増加する結果とな
る。Ｐ：0.030 wt％以下ならば、これらに起因する実質
的な被害を回避することができる。In carrying out the method of the present invention, it is desirable that the contents of P and S in the hot metal charged into the converter are low, and P:
0.030 wt% or less and S: 0.003 wt% or less. That is, when P exceeds 0.030 wt%, a large amount of CaO, which is an auxiliary material to be charged in the converter, is required, which not only increases refining costs, but also increases the amount of oxygen gas blown upward to oxidize and remove P. The result is to increase the (T.Fe) of the generated slag. If P: 0.030 wt% or less, substantial damage due to these can be avoided.
【００１０】一方、転炉精錬における脱硫は殆ど進行し
ないため、本発明で必要とするような極低硫溶銑の場
合、炉壁に付着した前チャージのスラグの再溶解により
むしろ復硫するおそれがある。すなわち、溶鋼での脱硫
は限界があるので、より効率的に脱硫が進行する溶銑段
階でＳを除去するのが望ましく、Ｓ：0.003 wt％以下、
より望ましくは0.0024wt％以下とする。On the other hand, since the desulfurization in the converter refining hardly progresses, in the case of the extremely low sulfur hot metal as required in the present invention, there is a risk of re-sulfurization due to the remelting of the precharged slag adhering to the furnace wall. is there. That is, since there is a limit to desulfurization in molten steel, it is desirable to remove S in the hot metal stage where desulfurization proceeds more efficiently. S: 0.003 wt% or less,
More preferably, it is 0.0024 wt% or less.
【００１１】このような溶銑は、例えば、以下に述べる
ような方法によって得ることができる。まず、高炉出銑
後の溶銑は温度が1500℃前後、Ｃ：4.4 wt％，Si：0.2
wt％，Ｐ：0.100 wt％およびＳ：0.025 wt％程度を含有
するものである。この溶銑に酸化鉄を主成分とする酸化
剤を上吹きまたは溶銑中に吹き込むと、Si：0.10wt％以
下とすることができる。この脱珪後の溶銑をトピードカ
ーまたは溶銑鍋に受銑し、CaO と酸化鉄からなる脱燐フ
ラックスを吹き込むことで脱燐し、その後ソーダ灰を吹
き込むことで脱硫を行い、Ｐ：0.030 wt％以下および
Ｓ：0.003 wt％以下とする。特に、Ｓ：0.0024wt％以下
とするには、脱硫に使用するソーダ灰の使用量を、Ｓ：
0.003 wt％以下の場合に比べて10〜20％多く用いること
が有効である。なお、脱燐および脱硫処理における、溶
銑温度は1250〜1400℃程度とすることが好ましい。Such hot metal can be obtained, for example, by the method described below. First, the temperature of the hot metal after blast furnace tapping is around 1500 ° C, C: 4.4 wt%, Si: 0.2
wt%, P: 0.100 wt% and S: 0.025 wt%. When an oxidizer containing iron oxide as a main component is blown onto the hot metal or blown into the hot metal, Si: 0.10 wt% or less can be obtained. The hot metal after desiliconization is received in a hot car or a hot metal ladle, and dephosphorization is performed by blowing a dephosphorization flux consisting of CaO and iron oxide, and then desulfurization is performed by blowing soda ash. P: 0.030 wt% or less And S: 0.003 wt% or less. In particular, in order to make S: 0.0024 wt% or less, the amount of soda ash used for desulfurization should be S:
It is effective to use 10-20% more than 0.003 wt% or less. The hot metal temperature in the dephosphorization and desulfurization treatment is preferably about 1250 to 1400 ° C.
【００１２】次いで、かかる溶銑を転炉に装入する際に
は、脱燐および脱硫後のスラグを可能な限り分離し、転
炉に流入しないようにすることが好ましい。また、本発
明で対象とする、極低硫鋼の溶製に当たっては、Ｓ：0.
007 wt％以下となる予備精錬を転炉で前もって行い、不
可避的に残留するスラグ中のＳ濃度を下げるようにする
と良い。Next, when charging the molten pig iron into the converter, it is preferable to separate the slag after dephosphorization and desulfurization as much as possible so as not to flow into the converter. Further, in melting the extremely low-sulfur steel, which is the object of the present invention, S: 0.
It is advisable to carry out preliminary refining to 007 wt% or less in advance in a converter so that the S concentration in the slag that remains inevitably decreases.
【００１３】さらに、転炉出鋼時のＣ濃度を0.02〜0.05
wt％およびＳ：0.005 wt％以下に限定するのは、次の理
由による。Ｃが0.05wt％を超えると、ＲＨ法による脱炭
処理に長時間を要することとなり、時として、Ｃ：0.00
30wt％以下の溶鋼が得られないことがある。また、たと
えそのレベルのものが得られても、次工程の連続鋳造に
おける効率的な操業を阻害する。このため、製品の品質
劣化をまねくだけでなく、生産性を著しく損なうことか
ら、Ｃ：0.05wt％以下とする。一方、Ｃ：0.02wt％未満
に精錬すると、スラグ中の（Ｔ．Ｆe ）が著しく増加す
る。これは、次のスラグ改質での円滑化を妨げるだけで
なく、転炉耐火物の溶損増加および鉄歩留りの低下を招
く。Further, the C concentration at the time of tapping the converter is 0.02 to 0.05.
The reason for limiting wt% and S: 0.005 wt% or less is as follows. If C exceeds 0.05 wt%, it will take a long time for decarburization treatment by the RH method, and sometimes C: 0.00
Molten steel below 30wt% may not be obtained. Further, even if the material having that level is obtained, it hinders efficient operation in the continuous casting in the next step. For this reason, not only the quality of the product is deteriorated but also the productivity is remarkably impaired. Therefore, the C content is set to 0.05 wt% or less. On the other hand, when C: less than 0.02 wt% is smelted, (T.Fe) in the slag remarkably increases. This not only hinders smoothing in the subsequent slag reforming, but also causes an increase in melting loss of the converter refractory and a decrease in iron yield.
【００１４】また、Ｓが0.005 wt％を超えると、次工程
のＲＨ法による脱硫を行っても、Ｓ：0.0020wt％以下と
するために極めて多くのフラックスを必要とすることに
なり、実際的でない。従って、経済的に高清浄度の極低
炭素鋼を転炉で大量溶製するには、Ｃ：0.02〜0.05wt％
およびＳ：0.005 wt％以下で出鋼することが必要であ
る。Further, if S exceeds 0.005 wt%, even if desulfurization is carried out by the RH method in the next step, an extremely large amount of flux is required in order to keep S: 0.0020 wt% or less. Not. Therefore, in order to economically produce a large amount of ultra-low carbon steel with a high degree of cleanliness in a converter, C: 0.02 to 0.05 wt%
And S: It is necessary to tap steel at 0.005 wt% or less.
【００１５】次に、出鋼時に取鍋内へ不可避的に流入す
る転炉スラグは、（Ｔ．Fe）が10〜30％と高く、かつ
（MnO ）を数％含有するため、ＲＨ法による脱酸および
脱硫過程で有害である。そこで、出鋼中および／または
出鋼後に、金属Al, Al2O3,CaOを主成分とする改質剤を
スラグに添加して、Alによりスラグ中のFeO およびMnO
を還元する。なお、このスラグ改質剤中の金属Alは30〜
70％とするのが、改質効果の点で好ましい。なお、スラ
グ中の（Ｔ．Fe）＋（MnO ）は７％以下とする必要があ
り、より望ましくは４％以下とする。すなわち、（Ｔ．
Fe）＋（MnO ）が７％をこえると、ＲＨでの脱硫で極低
硫鋼を得られないだけでなく、溶鋼中の介在物を増す原
因となる。特に、この値が４％以下になると、脱硫に及
ぼす影響が少ないし、次の脱炭時に、例えば真空槽内酸
素上吹きを実施しても、（Ｔ．Fe）＋（MnO ）が７％を
こえることはない。（Ｔ．Fe）＋（MnO ）を４％以下と
するには、上述のスラグ改質剤を出鋼中と出鋼後に分割
して投入すると良い。Next, the converter slag, which inevitably flows into the ladle at the time of tapping, has a high (T.Fe) of 10 to 30% and contains a few% of (MnO). Harmful in deoxidation and desulfurization processes. Therefore, during and / or after tapping, a modifier containing metal Al, Al 2 O 3 , and CaO as main components is added to the slag, and Al is used to remove FeO and MnO in the slag.
Reduce. The metallic Al content in this slag modifier is 30-
70% is preferable from the viewpoint of modifying effect. The (T.Fe) + (MnO) content in the slag must be 7% or less, and more preferably 4% or less. That is, (T.
When Fe) + (MnO) exceeds 7%, not only ultra-low-sulfur steel cannot be obtained by desulfurization in RH, but it also causes inclusions in molten steel to increase. In particular, if this value is 4% or less, the influence on desulfurization is small, and (T.Fe) + (MnO) is 7% even if the upper deoxygenation in the vacuum tank is performed during the next decarburization. It never exceeds. In order to reduce (T.Fe) + (MnO) to 4% or less, it is advisable to separately add the above-mentioned slag modifier during and after tapping.
【００１６】引き続き、溶鋼はＲＨ法でＣ：0.0030wt％
以下、必要に応じて0.0015wt％以下まで脱炭する。脱炭
時には、図１に示すような、酸素上吹きランスを用いて
真空槽内浴面に酸素ガスを吹き付けると、反応が促進さ
れることが多い。Subsequently, the molten steel was C: 0.0030 wt% by the RH method.
Then, if necessary, decarburize to 0.0015 wt% or less. At the time of decarburization, the reaction is often promoted by blowing oxygen gas onto the bath surface in the vacuum tank using an oxygen top blowing lance as shown in FIG.
【００１７】なお、図１において符号１は取鍋、２は溶
鋼、３は真空槽を示しており、該真空槽３と取鍋１との
間で環流管４を介して溶鋼２が循環する仕組みになって
いる。そして、真空槽３内の溶鋼２に対しては、上吹き
ランス５を介して、フラックス６を酸素とともに吹き付
け、脱炭処理を行う。In FIG. 1, reference numeral 1 is a ladle, 2 is molten steel, 3 is a vacuum tank, and the molten steel 2 circulates between the vacuum tank 3 and the ladle 1 via a reflux pipe 4. It works. Then, the molten steel 2 in the vacuum tank 3 is decarburized by spraying the flux 6 together with oxygen through the upper blowing lance 5.
【００１８】所望のＣ濃度以下に溶鋼を脱炭したのち、
金属Alで脱酸を行い、かつCaO を主成分とするフラック
スをCaO 換算で４kg/t以上添加する。Al添加後３分間経
過したのちにフラックスを添加する必要があり、その後
10分間以上環流処理をすると、フラックスの脱硫反応効
率が向上する。フラックスは真空槽内に上方よりホッパ
ーを介して一括して添加しても良いが、図１に示した酸
素上吹きランスの酸素の代わりにArガスを用い、このラ
ンスからArとともに上吹きしてもよく、とくにこの場合
にはフラックスの脱硫反応効率が向上し、Ｓ：0.0010wt
％以下の極低硫鋼が得られやすい。なお、CaO で脱硫す
る場合、そのCaO 量は温度低下で実害の及ばない範囲で
多い方が良く、このCaO 量が４kg/t未満では安定して
Ｓ：0.0020wt％以下に脱硫することが難しい。After decarburizing the molten steel to a desired C concentration or less,
Deoxidize with metallic Al and add 4 kg / t or more of CaO-based flux in terms of CaO. It is necessary to add the flux after 3 minutes have passed since the addition of Al, and then
If the reflux treatment is performed for 10 minutes or more, the desulfurization reaction efficiency of the flux is improved. The flux may be added all at once from above into the vacuum chamber through the hopper, but Ar gas is used instead of oxygen in the oxygen top blowing lance shown in FIG. In particular, in this case, the desulfurization reaction efficiency of the flux is improved, and S: 0.0010wt
% Or less ultra low sulfur steel is easily obtained. When desulfurizing with CaO, the amount of CaO should be as large as possible within the range that does not cause actual harm due to temperature decrease. If the amount of CaO is less than 4 kg / t, it is difficult to stably desulfurize to S: 0.0020 wt% or less. .
【００１９】[0019]
【実施例】高炉鋳床で脱珪処理を行い、Si：0.10wt％と
した溶銑 200ｔをトピードカーに受銑し、CaO ：30％お
よび酸化鉄：70％からなる脱燐フラックスを搬送用空気
とともに溶銑中に450kg/min の吹き込み速度にて総量 6
5kg/t 吹き込み、続いてソーダ灰を搬送用空気とともに
溶銑中に100 kg/minの吹き込み速度にて総量7.2 kg/t吹
き込むことにより、Ｐ：0.022 wt％およびＳ：0.0024wt
％の脱燐および脱硫溶銑を得た。この溶銑を除滓しつつ
装入鍋に移し、さらに装入鍋で除滓して転炉に装入し
た。転炉では炉底からArガスを0.1Nm3/min・t で吹き込
みつつ、酸素を2.5Nm3/min・t で上吹きし、約15min の
吹練でＣ：0.035 wt％，Ｐ：0.005 wt％およびＳ：0.00
28wt％の溶鋼を得た。この溶鋼の温度は1635℃で、吹止
め時に採取したスラグの（Ｔ．Fe）は16.5wt％であっ
た。[Example] Desiliconization was performed in a blast furnace casting floor, 200 tons of hot metal with Si: 0.10 wt% was received by a speeded car, and dephosphorization flux composed of CaO: 30% and iron oxide: 70% was used together with carrier air. Total amount 6 at a blowing speed of 450 kg / min into the hot metal
By injecting 5 kg / t, and then injecting soda ash with hot air into the hot metal at a blowing rate of 100 kg / min with a total amount of 7.2 kg / t, P: 0.022 wt% and S: 0.0024 wt
% Of dephosphorized and desulfurized hot metal was obtained. This molten pig iron was transferred to a charging pot while being slagged, and further slagged in the charging pot and charged into a converter. Blowing from the furnace bottom in the converter Ar gas at 0.1Nm 3 / min · t, oxygen was blown up in 2.5Nm 3 / min · t, C in吹練about 15min: 0.035 wt%, P: 0.005 wt % And S: 0.00
28 wt% molten steel was obtained. The temperature of this molten steel was 1635 ° C., and the (T.Fe) of the slag collected during blowing was 16.5 wt%.
【００２０】次いで、CaO ：66wt％，Al2O3 ：17％およ
び金属Al：17wt％からなるスラグ改質剤を出鋼中の湯面
スラグ上には２kg／ｔ、そして出鋼後の湯面スラグ上に
は３kg／ｔにて分割添加した。ＲＨ処理前に採取したこ
のスラグの（Ｔ．Fe）＋（MnO ）は3.1 wt％であった。Next, a slag modifier consisting of CaO: 66 wt%, Al 2 O 3 : 17% and metallic Al: 17 wt% was 2 kg / t on the surface slag during tapping, and the hot water after tapping. The surface slag was divided and added at 3 kg / t. The (T.Fe) + (MnO) of this slag collected before the RH treatment was 3.1 wt%.
【００２１】この溶鋼に、ＲＨ処理装置による20分間の
脱炭処理を施した。脱炭処理前の温度は1590℃、溶鋼中
のフリー酸素は600ppmであり、処理時の真空度は 0.5〜
５torrとし、溶鋼環流量は100t/minであった。20分間の
脱炭処理後に、Ｃ：0.0008wt％の溶鋼が得られた。その
後、金属Alを添加し、溶鋼中のsol.Al：0.4 wt％とし
た。さらに、FeSi合金を添加し、Si：3.3 wt％に調整し
た。This molten steel was subjected to a decarburizing treatment for 20 minutes by an RH treatment device. The temperature before decarburization is 1590 ° C, the free oxygen in the molten steel is 600ppm, and the vacuum degree during processing is 0.5 ~
The flow rate of molten steel was 5 torr and the flow rate of molten steel was 100 t / min. After 20 minutes of decarburization treatment, C: 0.0008 wt% molten steel was obtained. After that, metallic Al was added to make sol.Al in molten steel: 0.4 wt%. Furthermore, FeSi alloy was added to adjust Si: 3.3 wt%.
【００２２】その後、CaO ：70％，CaF2：15％およびAl
2O3 ：15％からなる、予め溶融し冷却後に粉砕した脱硫
フラックスを、真空槽内に設置した上吹きランスを用い
て、Arガス５Nm3/min とともに150 kg/minの速度で槽内
浴面上に総量7.5 kg／ｔを添加した。かくして得られた
溶鋼は、Ｓ：0.0006wt％およびＯ：0.0008wt％と、清浄
度の高い極低炭素鋼であった。この溶鋼を連続鋳造し、
圧延して厚さ0.35mmの薄鋼板を得たのち、この薄鋼板の
電磁特性を調べたところ、従来の最高級無方向性珪素鋼
板より、約20％鉄損の低い、画期的な製品が得られた。Then, CaO: 70%, CaF 2 : 15% and Al
2 O 3 : 15% of desulfurization flux which was melted in advance, cooled and pulverized, was heated in an internal bath at a rate of 150 kg / min with Ar gas of 5 Nm 3 / min using an upper blowing lance installed in a vacuum chamber. A total of 7.5 kg / t was added on the surface. The molten steel thus obtained was S: 0.0006 wt% and O: 0.0008 wt%, which was a very low carbon steel with high cleanliness. Continuous casting of this molten steel,
After rolling to obtain a thin steel sheet with a thickness of 0.35 mm, the electromagnetic characteristics of this thin steel sheet were investigated, and it was an epoch-making product with about 20% lower iron loss than the conventional highest grade non-oriented silicon steel sheet. was gotten.
【００２３】[0023]
【発明の効果】以上説明したように本発明によれば、
Ｃ：0.0030wt％以下およびＳ：0.0020wt％以下の清浄度
の極めて高い極低炭素鋼を得ることができ、特に自動車
鋼板用薄鋼板向けにはＣ：0.0015wt％以下およびＳ：0.
0020wt％以下、高級無方向性珪素鋼板向けにはＣ：0.00
30wt％以下およびＳ：0.0010wt％以下に、それぞれ調整
することが可能であり、各鋼板の溶製に有利に適合する
溶鋼を提供し得る。As described above, according to the present invention,
C: 0.0030 wt% or less and S: 0.0020 wt% or less extremely low carbon steel having an extremely high cleanliness can be obtained, and especially for thin steel sheets for automobile steel sheets, C: 0.0015 wt% or less and S: 0.
0020wt% or less, C: 0.00 for high grade non-oriented silicon steel sheet
The molten steel can be adjusted to 30 wt% or less and S: 0.0010 wt% or less, respectively, and it is possible to provide molten steel that is advantageously suited to the melting of each steel sheet.
【図１】本発明に従う脱炭処理を説明する模式図であ
る。FIG. 1 is a schematic diagram illustrating a decarburization treatment according to the present invention.
１ 取鍋 ２ 溶鋼 ３ 真空槽 ４ 環流管 ５ 上吹きランス ６ フラックス 1 Ladle 2 Molten Steel 3 Vacuum Tank 4 Recirculation Tube 5 Top Blowing Lance 6 Flux
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｃ２１Ｃ 7/068 7412−4Ｋ (72)発明者 田口 整司 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究本部内 (72)発明者 藤井 徹也 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究本部内─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification number Reference number within the agency FI Technical display location C21C 7/068 7412-4K (72) Inventor Seiji Taguchi 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki (72) Inventor Tetsuya Fujii, 1 Kawasaki-machi, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd.
Claims (1)
％以下に脱燐および脱硫処理した溶銑を、転炉精錬に
て、Ｃ：0.020 〜0.050 wt％およびＳ：0.0050wt％以下
の溶鋼とし、この溶鋼の取鍋への出鋼中および／または
出鋼後に、金属Alを含むスラグ改質剤を添加してスラグ
成分が（Ｔ．Fe）＋（MnO ）≦７wt％を満足するように
調整し、次いでＲＨ真空脱炭処理を行った後、金属Alに
よる脱酸処理およびCaO を主成分とするフラックスをCa
O 換算で４kg／ｔ以上、ＲＨ真空槽内の溶鋼に添加する
脱硫処理を施し、溶鋼成分をＣ：0.0030wt％以下および
Ｓ：0.0020wt％以下に調整することを特徴とするＳ含有
量の極めて少ない高清浄度極低炭素鋼の製造方法。1. P: 0.030 wt% or less and S: 0.003 wt
% Of dephosphorized and desulfurized hot metal by converter smelting into C: 0.020 to 0.050 wt% and S: 0.0050 wt% or less of molten steel, and the molten steel is being tapped and / or tapped in a ladle. After steel, a slag modifier containing metallic Al was added to adjust the slag component to satisfy (T.Fe) + (MnO) ≦ 7 wt%, and then RH vacuum decarburization treatment was performed. Deoxidation treatment with Al and flux containing CaO as the main component
Desulfurization treatment is performed by adding 4 kg / t or more in terms of O to molten steel in the RH vacuum tank, and adjusting the molten steel components to C: 0.0030 wt% or less and S: 0.0020 wt% or less. A method of producing extremely low high cleanliness ultra-low carbon steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00115693A JP3627755B2 (en) | 1993-01-07 | 1993-01-07 | Method for producing high cleanliness ultra low carbon steel with extremely low S content |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00115693A JP3627755B2 (en) | 1993-01-07 | 1993-01-07 | Method for producing high cleanliness ultra low carbon steel with extremely low S content |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06207212A true JPH06207212A (en) | 1994-07-26 |
| JP3627755B2 JP3627755B2 (en) | 2005-03-09 |
Family
ID=11493580
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00115693A Expired - Fee Related JP3627755B2 (en) | 1993-01-07 | 1993-01-07 | Method for producing high cleanliness ultra low carbon steel with extremely low S content |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000109924A (en) * | 1998-10-06 | 2000-04-18 | Sumitomo Metal Ind Ltd | Method for melting extra-low sulfur steel |
| KR20030039107A (en) * | 2001-11-12 | 2003-05-17 | 주식회사 포스코 | Method for manufacturing ultra low carbon steel having ultra low sulphur |
| WO2003068996A1 (en) * | 2002-02-15 | 2003-08-21 | Nucor Corporation | Model-based system for determining process parameters for the ladle refinement of steel |
| JP2008063647A (en) * | 2006-09-11 | 2008-03-21 | Jfe Steel Kk | Method for desulfurizing molten steel |
| KR20110045037A (en) * | 2008-08-04 | 2011-05-03 | 누코 코포레이션 | Low cost manufacturing method of low carbon, low sulfur and low nitrogen steels using conventional steelmaking facilities |
| KR101484106B1 (en) * | 2010-06-23 | 2015-01-19 | 바오샨 아이론 앤 스틸 유한공사 | Method for Controlling Extremely Low Ti in Extra Low Carbon AlSi-Killed Steel |
| US11047015B2 (en) | 2017-08-24 | 2021-06-29 | Nucor Corporation | Manufacture of low carbon steel |
-
1993
- 1993-01-07 JP JP00115693A patent/JP3627755B2/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000109924A (en) * | 1998-10-06 | 2000-04-18 | Sumitomo Metal Ind Ltd | Method for melting extra-low sulfur steel |
| KR20030039107A (en) * | 2001-11-12 | 2003-05-17 | 주식회사 포스코 | Method for manufacturing ultra low carbon steel having ultra low sulphur |
| WO2003068996A1 (en) * | 2002-02-15 | 2003-08-21 | Nucor Corporation | Model-based system for determining process parameters for the ladle refinement of steel |
| US6808550B2 (en) | 2002-02-15 | 2004-10-26 | Nucor Corporation | Model-based system for determining process parameters for the ladle refinement of steel |
| US6921425B2 (en) | 2002-02-15 | 2005-07-26 | Nucor Corporation | Model-based system for determining process parameters for the ladle refinement of steel |
| US7211127B2 (en) | 2002-02-15 | 2007-05-01 | Nucor Corporation | Model-based system for determining process parameters for the ladle refinement of steel |
| JP2008063647A (en) * | 2006-09-11 | 2008-03-21 | Jfe Steel Kk | Method for desulfurizing molten steel |
| KR20110045037A (en) * | 2008-08-04 | 2011-05-03 | 누코 코포레이션 | Low cost manufacturing method of low carbon, low sulfur and low nitrogen steels using conventional steelmaking facilities |
| KR101484106B1 (en) * | 2010-06-23 | 2015-01-19 | 바오샨 아이론 앤 스틸 유한공사 | Method for Controlling Extremely Low Ti in Extra Low Carbon AlSi-Killed Steel |
| US11047015B2 (en) | 2017-08-24 | 2021-06-29 | Nucor Corporation | Manufacture of low carbon steel |
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|---|---|
| JP3627755B2 (en) | 2005-03-09 |
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