JP2897647B2 - Melting method of low hydrogen extremely low sulfur steel - Google Patents
Melting method of low hydrogen extremely low sulfur steelInfo
- Publication number
- JP2897647B2 JP2897647B2 JP19475394A JP19475394A JP2897647B2 JP 2897647 B2 JP2897647 B2 JP 2897647B2 JP 19475394 A JP19475394 A JP 19475394A JP 19475394 A JP19475394 A JP 19475394A JP 2897647 B2 JP2897647 B2 JP 2897647B2
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- immersion
- ladle
- tube
- 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.)
- Expired - Lifetime
Links
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- Treatment Of Steel In Its Molten State (AREA)
Description
【０００１】[0001]
【産業上の利用分野】この発明は、取鍋で真空精錬して
低水素極低硫鋼を溶製する方法に関するもので、詳しく
は筒状浸漬管（シュノーケル）を用い真空下で溶鋼の脱
ガス、脱硫処理を行う方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing low hydrogen ultra low sulfur steel by vacuum refining using a ladle, and more particularly, to removing molten steel under vacuum using a cylindrical immersion pipe (snorkel). The present invention relates to a method for performing gas and desulfurization treatment.
【０００２】[0002]
【従来の技術】近年、高級鋼においては、極低硫、極低
酸素、極低水素等の要件を満たす鋼の溶製に対する要求
がますます強くなってきている。極低硫鋼の溶製は、通
常、大気圧下で取鍋内溶鋼の上に脱硫フラックスを置い
た状態で、ガス撹拌あるいは脱硫用粉体をインジェクシ
ョンする方法が採られているが、大気中の空気との接触
による溶鋼の空気酸化あるいは窒素濃度の上昇を避ける
ため、取鍋蓋を使用することもある。上記の方法では、
極低硫鋼の溶製は可能であるが、極低硫化と同時に低水
素化を要求される鋼種については、大気圧下の脱硫処理
の前または後あるいはその前後に真空脱水素処理を行う
必要があり、２種の処理をすることによって、総処理時
間の延長ならびに温度低下の増大が生じてしまう。ま
た、処理工程が複雑となり、サイクルタイム延長による
工程ネック等によって生産性の低下を招き、大量処理に
は不向きである。2. Description of the Related Art In recent years, in high-grade steels, there has been an increasing demand for smelting steels satisfying requirements such as extremely low sulfur, extremely low oxygen, and extremely low hydrogen. For the production of extremely low sulfur steel, gas stirring or injection of powder for desulfurization is usually employed with the desulfurization flux placed on the molten steel in the ladle under atmospheric pressure. A ladle lid may be used to avoid air oxidation of the molten steel or an increase in the nitrogen concentration due to contact with the air. In the above method,
It is possible to melt ultra-low sulfur steel, but for steel types that require low hydrogenation at the same time as ultra-low sulfuration, it is necessary to perform vacuum dehydrogenation before, after, or before and after desulfurization at atmospheric pressure. However, by performing the two types of processing, the total processing time is prolonged and the temperature is increased. In addition, the processing process becomes complicated, and the productivity is reduced due to the process bottleneck due to the extension of the cycle time, which is not suitable for mass processing.
【０００３】最近では吸上式真空精錬法の一つであるＲ
Ｈ法においては、脱硫剤を添加することにより低水素極
低硫鋼を溶製する方法が提案されている。その場合の脱
硫剤の添加方法は、ＲＨ真空槽内上部合金ホッパーから
添加するか、ＲＨ真空槽内の上吹きランスから上吹きす
るか、ＲＨ真空槽耐火物内壁に設けた羽口から上吹きあ
るいはインジェクションするか、ＲＨ浸漬管のうち上昇
管の下方の浸漬ランスからインジェクションする等の方
法がとられている。また、他の方法としては、溶鋼を収
容した取鍋全体を真空槽内に取込み、真空槽内を排気減
圧した状態でガス撹拌あるいは脱硫剤インジェクション
し、極低硫鋼を溶製する方法が提案されている。Recently, one of the suction vacuum refining methods, R,
In the H method, a method has been proposed in which a low hydrogen extremely low sulfur steel is melted by adding a desulfurizing agent. In this case, the method of adding the desulfurizing agent is to add from the upper alloy hopper in the RH vacuum tank, blow up from the upper blowing lance in the RH vacuum tank, or blow up from the tuyere provided on the inner wall of the refractory of the RH vacuum tank. Alternatively, a method such as injection or injection from an immersion lance below an ascending tube in the RH immersion tube is employed. As another method, a method is proposed in which the entire ladle containing the molten steel is taken into a vacuum chamber, and gas is stirred or a desulfurizing agent is injected while the vacuum chamber is evacuated and depressurized to melt the extremely low sulfur steel. Have been.
【０００４】また、吸上式真空精錬法の他の方法におい
ては、真空槽内を減圧すると共に取鍋内にキャリヤーガ
スで脱硫剤を吹き込み、引き続いて真空槽内を真空状態
にしたまま脱硫剤の添加を止めて不活性ガス等のみ吹き
込みを行い、次いで真空槽内を大気圧に復圧したのち、
Ｃａ合金またはＣａ化合物を吹き込む方法（特公昭６３
−３２８４５号公報）、取鍋内溶鋼中に筒状浸漬管を浸
漬して溶鋼裸面を確保し、該浸漬管内を排気して真空に
した状態でランスまたは底部羽口より不活性ガスと共に
脱硫剤を吹き込む方法（特開平１−９２３１４号公報）
が提案されている。In another vacuum suction refining method, the pressure in the vacuum chamber is reduced and a desulfurizing agent is blown into the ladle with a carrier gas. Subsequently, the desulfurizing agent is kept in a vacuum state in the vacuum chamber. After stopping the addition and blowing only inert gas, etc., and then returning the pressure in the vacuum chamber to atmospheric pressure,
A method of injecting a Ca alloy or a Ca compound (Japanese Patent Publication Sho 63)
No. 32845), a cylindrical immersion tube is immersed in molten steel in a ladle to secure a bare surface of molten steel, and the interior of the immersion tube is evacuated to a vacuum and desulfurized with an inert gas from a lance or a bottom tuyere. Method of blowing agent (JP-A-1-92314)
Has been proposed.
【０００５】[0005]
【発明が解決しようとする課題】上記ＲＨ法による低水
素極低硫鋼の溶製は、脱硫剤を添加することにより溶鋼
脱硫が可能であるが、取鍋スラグの撹拌ができないため
スラグ改質が十分行えず、そのためＲＨ処理後に取鍋ス
ラグの低級酸化物から溶鋼側に徐々に酸素が供給され、
溶鋼の復硫および清浄性が悪化してしまうという問題点
を有している。したがって、この問題を回避するために
は、ＲＨ処理前に前処理として取鍋スラグの改質を十分
に行う必要があり、結局大気圧下での脱硫処理と同様に
２重処理が必要となってしまう。また、ラインパイプ等
に代表される耐水素誘起割れ鋼（以下耐ＨＩＣ鋼とい
う）では、溶鋼に金属Ｃａを添加する必要があるが、Ｃ
ａの飽和蒸気圧は約１．８気圧であるため、ＲＨ法のよ
うな真空処理装置ではその大半が蒸発してしまい、その
結果Ｃａ添加歩留が非常に低くなってしまい、Ｃａ原単
位増加によるコストアップを生じてしまうという問題点
も有している。Ｃａの歩留を上げるためには、ＲＨ処理
の後、大気圧下で処理するプロセスが必要となり、やは
り２重処理となってしまう。In the production of low hydrogen ultra low sulfur steel by the RH method, desulfurization of molten steel is possible by adding a desulfurizing agent, but slag reforming cannot be performed because ladle slag cannot be stirred. Is not sufficiently performed, and after the RH treatment, oxygen is gradually supplied from the lower oxide of the ladle slag to the molten steel side,
There is a problem that resulfurization and cleanliness of molten steel deteriorate. Therefore, in order to avoid this problem, it is necessary to sufficiently reform the ladle slag as a pre-treatment before the RH treatment, and as a result, a double treatment is required similarly to the desulfurization treatment under the atmospheric pressure. Would. In the case of hydrogen-induced cracking steel (hereinafter referred to as HIC-resistant steel) typified by line pipes and the like, it is necessary to add metallic Ca to molten steel.
Since the saturated vapor pressure of a is about 1.8 atm, most of the vacuum processing apparatus such as the RH method evaporates, and as a result, the Ca addition yield becomes extremely low, and the Ca unit consumption increases. However, there is also a problem that the cost is increased due to the above. In order to increase the yield of Ca, a process of performing the process under the atmospheric pressure after the RH process is required, which also results in a double process.
【０００６】さらに、溶鋼を収容した取鍋全体を真空槽
内に取込み、真空槽内を排気減圧した状態でガス撹拌あ
るいは脱硫剤インジェクションし、極低硫鋼を溶製する
方法は、真空下で処理するため脱硫効率は高いが、取鍋
全体を真空槽内に収容するため、莫大な設備費を必要と
するばかりでなく、取鍋を真空槽内に収容および取り出
すための作業に長時間を必要とし、生産性の低下を招
き、大量生産に適さないという問題点を有している。[0006] Furthermore, the method of taking the entire ladle containing molten steel into a vacuum tank, and performing gas agitation or injection of a desulfurizing agent while evacuating and depressurizing the vacuum tank to melt ultra-low sulfur steel is performed under vacuum. Although the desulfurization efficiency is high due to the treatment, storing the entire ladle in the vacuum tank not only requires enormous equipment costs, but also takes a long time to store and remove the ladle in the vacuum tank. However, there is a problem that it is necessary and causes a decrease in productivity and is not suitable for mass production.
【０００７】さらにまた、特公昭６３−３２８４５号公
報、特開平１−９２３１４号公報に開示の方法は、浸漬
管内に多量のスラグを収容するためスラグの撹拌も良好
で脱硫脱水素に有効である。さらに、この方法は、浸漬
管内を大気圧に復圧したのち、金属Ｃａを添加すればＲ
Ｈ法のようなＣａ歩留低下を防止できるが、浸漬管外側
に取り残された取鍋スラグの撹拌・改質が十分でないと
いう問題点を有している。Further, the methods disclosed in Japanese Patent Publication No. 63-32845 and Japanese Patent Application Laid-Open No. 1-92314 are effective for desulfurization and dehydrogenation because a large amount of slag is contained in a dip tube, and the slag is well stirred. . Further, in this method, after the pressure in the immersion tube is restored to the atmospheric pressure, R is added if metal Ca is added.
Although the decrease in Ca yield as in the H method can be prevented, there is a problem that the ladle slag left outside the immersion tube is not sufficiently stirred and reformed.
【０００８】この発明の目的は、従来の低水素極低硫鋼
の溶製方法において、問題となっていた取鍋スラグの撹
拌不足を生じさせない低水素極低硫鋼の溶製方法を提供
することにある。An object of the present invention is to provide a method for producing low hydrogen ultra low sulfur steel which does not cause insufficient stirring of ladle slag, which is a problem in the conventional method for producing low hydrogen ultra low sulfur steel. It is in.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、上記目的
を達成すべく種々試験検討を重ねた。その結果、脱硫速
度、処理後の浸漬管外側のスラグ中の低級酸化物濃度お
よび浸漬管補修頻度のそれぞれを同時に満足のいくレベ
ルにするには、浸漬管内径Ｄ1と取鍋内径Ｄ2との比（Ｄ
1／Ｄ2）を０．５〜０．８にすればよいこと、脱硫・脱
水素処理は１００Ｔｏｒｒ以下でなければならないこ
と、浸漬管内を４００Ｔｏｒｒから大気圧下にしたのち
ガス撹拌処理を行う場合、浸漬管の浸漬深さを０．５ｍ
以下とすることによって、浸漬管外側のスラグの撹拌・
改質が十分に行われることを究明し、この発明に到達し
た。Means for Solving the Problems The present inventors have conducted various tests and studies to achieve the above object. As a result, the desulfurization rate, to simultaneously satisfactory level of each lower oxide concentration and dip tube repairing frequency of the dip tube outside in the slag after the treatment, a dip tube inner diameter D 1 and the ladle inner diameter D 2 Ratio (D
1 / D 2 ) should be 0.5 to 0.8, desulfurization / dehydrogenation treatment must be 100 Torr or less, and gas stirring treatment is performed after the inside of the immersion tube is reduced from 400 Torr to atmospheric pressure. The immersion depth of the immersion tube is 0.5m
By the following, agitation of slag outside the immersion tube
The inventors have found that the reforming is sufficiently performed, and reached the present invention.
【００１０】すなわち本願の第１発明は、取鍋内の溶鋼
に筒状浸漬管を浸漬して溶鋼の精錬を行う方法におい
て、浸漬管の内径Ｄ1と取鍋の内径Ｄ2の比（Ｄ1／Ｄ2）
が０．５以上０．８以下を満足するような浸漬管および
取鍋を用い、浸漬管内を４００Ｔｏｒｒから大気圧下に
保持し、かつ浸漬管を溶鋼に浸漬深さ０．５ｍ以下で浸
漬した状態で溶鋼中に不活性ガスを２分間以上吹き込ん
でガス撹拌処理を行った後に、浸漬管内を１００Ｔｏｒ
ｒ以下の真空度に保持して不活性ガスを溶鋼中に吹き込
んで脱硫処理および脱水素処理を行うことを特徴とする
低水素極低硫鋼の溶製方法である。That is, the first invention of the present application is a method for refining molten steel by immersing a cylindrical immersion pipe in molten steel in a ladle, wherein the ratio (DD) of the inner diameter D 1 of the immersion pipe to the inner diameter D 2 of the ladle is described. 1 / D 2)
Using an immersion tube and a ladle that satisfies 0.5 or more and 0.8 or less, the inside of the immersion tube was maintained at an atmospheric pressure from 400 Torr, and the immersion tube was immersed in molten steel at an immersion depth of 0.5 m or less. After injecting an inert gas into the molten steel for 2 minutes or more to perform a gas agitation process, the inside of the immersion tube is kept at 100 Torr.
A method for producing a low hydrogen ultra low sulfur steel, characterized in that an inert gas is blown into molten steel while maintaining the degree of vacuum at or below r to perform desulfurization treatment and dehydrogenation treatment.
【００１１】また、本願の第２発明は、取鍋内の溶鋼に
筒状浸漬管を浸漬して溶鋼の精錬を行う方法において、
浸漬管の内径Ｄ1と取鍋の内径Ｄ2の比（Ｄ1／Ｄ2）が
０．５以上０．８以下を満足するような浸漬管および取
鍋を用い、浸漬管内を１００Ｔｏｒｒ以下の真空度に保
持して不活性ガスを溶鋼中に吹き込んで脱硫処理および
脱水素処理を行った後に、浸漬管内を４００Ｔｏｒｒか
ら大気圧下に保持し、かつ浸漬管を溶鋼に浸漬深さ０．
５ｍ以下で浸漬した状態で溶鋼中に不活性ガスを２分間
以上吹き込んでガス撹拌処理を行うことを特徴とする低
水素極低硫鋼の溶製方法である。Further, a second invention of the present application is a method for refining molten steel by immersing a cylindrical immersion pipe in molten steel in a ladle,
Using a dip tube and a ladle whose ratio (D 1 / D 2 ) of the inner diameter D 1 of the dip tube to the inner diameter D 2 of the ladle satisfies 0.5 or more and 0.8 or less, the inside of the dip tube is 100 Torr or less. After performing a desulfurization treatment and a dehydrogenation treatment by blowing an inert gas into the molten steel while maintaining the degree of vacuum, the inside of the immersion tube is maintained at an atmospheric pressure from 400 Torr, and the immersion tube is immersed in the molten steel at a depth of 0.1 mm.
This is a method for producing a low hydrogen ultra low sulfur steel, characterized in that an inert gas is blown into molten steel for 2 minutes or more while being immersed at a depth of 5 m or less to perform gas stirring treatment.
【００１２】さらに、本願の第３発明は、取鍋内の溶鋼
に筒状浸漬管を浸漬して溶鋼の精錬を行う方法におい
て、浸漬管の内径Ｄ1と取鍋の内径Ｄ2の比（Ｄ1／Ｄ2）
が０．５以上０．８以下を満足するような浸漬管および
取鍋を用い、浸漬管内を４００Ｔｏｒｒから大気圧下に
保持し、かつ浸漬管を溶鋼に浸漬深さ０．５ｍ以下で浸
漬した状態で溶鋼中に不活性ガスを２分間以上吹き込ん
でガス撹拌処理を行った後に、浸漬管内を１００Ｔｏｒ
ｒ以下の真空度に保持して不活性ガスを溶鋼中に吹き込
んで脱硫処理および脱水素処理を行い、その後再び浸漬
管内を４００Ｔｏｒｒから大気圧下に保持し、かつ浸漬
管を溶鋼に浸漬深さ０．５ｍ以下で浸漬した状態で溶鋼
中に不活性ガスを２分間以上吹き込んでガス撹拌処理を
行うことを特徴とする低水素極低硫鋼の溶製方法であ
る。Further, a third invention of the present application provides a method of refining molten steel by dipping a cylindrical immersion pipe in molten steel in a ladle, wherein the ratio of the inner diameter D 1 of the immersion pipe to the inner diameter D 2 of the ladle ( D 1 / D 2)
Using an immersion tube and a ladle that satisfies 0.5 or more and 0.8 or less, the inside of the immersion tube was maintained at an atmospheric pressure from 400 Torr, and the immersion tube was immersed in molten steel at an immersion depth of 0.5 m or less. After injecting an inert gas into the molten steel for 2 minutes or more to perform a gas agitation process, the inside of the immersion tube is kept at 100 Torr.
r, and the inert gas is blown into the molten steel to perform desulfurization treatment and dehydrogenation treatment. Thereafter, the inside of the immersion pipe is again maintained at 400 Torr under atmospheric pressure, and the immersion pipe is immersed in the molten steel at a depth of This is a method for producing a low hydrogen ultra low sulfur steel, characterized in that an inert gas is blown into molten steel for 2 minutes or more while being immersed at a depth of 0.5 m or less to perform gas stirring.
【００１３】[0013]
【作用】本願の第１発明においては、浸漬管の内径Ｄ1
と取鍋の内径Ｄ2の比（Ｄ1／Ｄ2）が０．５以上０．８
以下を満足するような浸漬管および取鍋を用い、浸漬管
内を４００Ｔｏｒｒから大気圧下に保持し、かつ浸漬管
を溶鋼中に深さ０．５ｍ以下浸漬した状態で溶鋼中に不
活性ガスを２分間以上吹き込んでガス撹拌処理すること
によって、不活性ガスの吹き込みによって生じた溶鋼の
上昇流が、浸漬管内鋼浴表面で浸漬管内壁に向かう水平
流となり、その水平溶鋼流が浸漬管内壁で完全な下降流
に変化せず、浸漬管外側での溶鋼流を形成し、浸漬管外
側のスラグの撹拌が十分に行われ、浸漬管外側のスラグ
中の低級酸化物濃度を低減することができる。また、浸
漬管内を１００Ｔｏｒｒ以下の真空度に保持して不活性
ガスを溶鋼中に吹き込んで脱硫処理および脱水素処理す
ることによって、脱硫速度、脱硫処理後の浸漬管外側の
スラグ中の低級酸化物濃度および浸漬管の補修頻度指数
を同時に満足のいくレベルに保持することができる。According to the first invention of the present application, the inner diameter D 1 of the immersion tube is set.
The ratio of the inner diameter D 2 of the ladle (D 1 / D 2) of 0.5 to 0.8
Using an immersion tube and a ladle that satisfies the following, the inside of the immersion tube is maintained at atmospheric pressure from 400 Torr, and an inert gas is introduced into the molten steel while the immersion tube is immersed in the molten steel at a depth of 0.5 m or less. By performing gas agitation treatment by blowing for 2 minutes or more, the rising flow of the molten steel caused by the blowing of the inert gas becomes a horizontal flow toward the inner wall of the immersion pipe on the surface of the steel bath in the immersion pipe, and the horizontal molten steel flow is generated by the inner wall of the immersion pipe. The molten steel flow is formed outside the immersion tube without changing to a complete descending flow, the slag outside the immersion tube is sufficiently stirred, and the lower oxide concentration in the slag outside the immersion tube can be reduced. . In addition, by maintaining the inside of the immersion tube at a degree of vacuum of 100 Torr or less and blowing an inert gas into the molten steel to perform desulfurization and dehydrogenation, the desulfurization rate and the lower oxides in the slag outside the immersion tube after the desulfurization treatment are reduced. The concentration and the repair frequency index of the dip tube can be kept at a satisfactory level at the same time.
【００１４】本願の第２発明においては、浸漬管の内径
Ｄ1と取鍋の内径Ｄ2の比（Ｄ1／Ｄ2）が０．５以上０．
８以下を満足するような浸漬管および取鍋を用い、浸漬
管内を１００Ｔｏｒｒ以下の真空度に保持して不活性ガ
スを溶鋼中に吹き込んで脱硫処理および脱水素処理する
ことによって、脱硫速度、脱硫処理後の浸漬管外側のス
ラグ中の低級酸化物濃度および浸漬管の補修頻度指数を
同時に満足のいくレベルに保持することができる。ま
た、浸漬管内を４００Ｔｏｒｒから大気圧下に保持し、
かつ浸漬管を溶鋼中に深さ０．５ｍ以下浸漬した状態で
溶鋼中に不活性ガスを２分間以上吹き込んでガス撹拌処
理することによって、不活性ガスの吹き込みによって生
じた溶鋼の上昇流が、浸漬管内鋼浴表面で浸漬管内壁に
向かう水平流となり、その水平溶鋼流が浸漬管内壁で完
全な下降流に変化せず、浸漬管外側での溶鋼流を形成
し、浸漬管外側のスラグの撹拌が十分に行われ、浸漬管
外側のスラグ中の低級酸化物濃度を低減することができ
る。In the second invention of the present application, the ratio (D 1 / D 2 ) of the inner diameter D 1 of the dip tube to the inner diameter D 2 of the ladle is 0.5 or more.
Desulfurization rate and desulfurization by using an immersion tube and a ladle that satisfies 8 or less and maintaining the inside of the immersion tube at a vacuum of 100 Torr or less and blowing inert gas into molten steel to perform desulfurization treatment and dehydrogenation treatment. The lower oxide concentration in the slag outside the dip tube after the treatment and the repair frequency index of the dip tube can be simultaneously maintained at a satisfactory level. Also, the inside of the immersion tube is kept under atmospheric pressure from 400 Torr,
And, by injecting an inert gas into the molten steel for 2 minutes or more in a state where the immersion pipe is immersed in the molten steel to a depth of 0.5 m or less and performing gas agitation processing, the upward flow of the molten steel caused by the injection of the inert gas is A horizontal flow toward the inner wall of the immersion pipe occurs on the surface of the steel bath in the immersion pipe, and the horizontal molten steel flow does not change to a completely downward flow on the inner wall of the immersion pipe, but forms a molten steel flow outside the immersion pipe, and the slag of the slag outside the immersion pipe is formed. Stirring is sufficiently performed, and the lower oxide concentration in the slag outside the immersion tube can be reduced.
【００１５】本願の第３発明においては、浸漬管の内径
Ｄ1と取鍋の内径Ｄ2の比（Ｄ1／Ｄ2）が０．５以上０．
８以下を満足するような浸漬管および取鍋を用い、浸漬
管内を４００Ｔｏｒｒから大気圧下に保持し、かつ浸漬
管を溶鋼中に深さ０．５ｍ以下浸漬した状態で溶鋼中に
不活性ガスを２分間以上吹き込んでガス撹拌処理するこ
とによって、不活性ガスの吹き込みによって生じた溶鋼
の上昇流が、浸漬管内鋼浴表面で浸漬管内壁に向かう水
平流となり、その水平溶鋼流が浸漬管内壁で完全な下降
流に変化せず、浸漬管外側での溶鋼流を形成し、浸漬管
外側のスラグの撹拌が十分に行われ、浸漬管外側のスラ
グ中の低級酸化物濃度を低減することができる。また、
浸漬管内を１００Ｔｏｒｒ以下の真空度に保持して不活
性ガスを溶鋼中に吹き込んで脱硫処理および脱水素処理
することによって、脱硫速度、脱硫処理後の浸漬管外側
のスラグ中の低級酸化物濃度および浸漬管の補修頻度指
数を同時に満足のいくレベルに保持することができる。
さらに、再度浸漬管内を４００Ｔｏｒｒから大気圧下に
保持し、かつ浸漬管を溶鋼中に深さ０．５ｍ以下浸漬し
た状態で溶鋼中に不活性ガスを２分間以上吹き込んでガ
ス撹拌処理することによって、不活性ガスの吹き込みに
よって生じた溶鋼の上昇流が、浸漬管内鋼浴表面で浸漬
管内壁に向かう水平流となり、その水平溶鋼流が浸漬管
内壁で完全な下降流に変化せず、浸漬管外側での溶鋼流
を形成し、浸漬管外側のスラグの撹拌が十分に行われ、
浸漬管外側のスラグ中の低級酸化物濃度をより低減する
ことができる。In the third invention of the present application, the ratio (D 1 / D 2 ) of the inner diameter D 1 of the dip tube to the inner diameter D 2 of the ladle is 0.5 or more and 0.5 mm or more.
Using an immersion tube and a ladle that satisfies the condition of 8 or less, the inside of the immersion tube is maintained at an atmospheric pressure from 400 Torr, and the immersion tube is immersed in the molten steel at a depth of 0.5 m or less. For 2 minutes or more to perform gas agitation treatment, the rising flow of molten steel generated by the blowing of the inert gas becomes a horizontal flow toward the inner wall of the immersion pipe on the surface of the steel bath in the immersion pipe, and the horizontal molten steel flow is applied to the inner wall of the immersion pipe. It does not change to a complete downflow, forms molten steel flow outside the immersion tube, sufficiently agitates the slag outside the immersion tube, and reduces the lower oxide concentration in the slag outside the immersion tube. it can. Also,
By maintaining the inside of the immersion tube at a degree of vacuum of 100 Torr or less and blowing an inert gas into molten steel to perform desulfurization treatment and dehydrogenation treatment, the desulfurization rate, the concentration of lower oxides in the slag outside the immersion tube after the desulfurization treatment, and The repair frequency index of the dip tube can be kept at a satisfactory level at the same time.
Further, the inside of the immersion tube is again maintained at atmospheric pressure from 400 Torr, and while the immersion tube is immersed in the molten steel at a depth of 0.5 m or less, an inert gas is blown into the molten steel for 2 minutes or more to perform gas stirring treatment. The upward flow of molten steel caused by the injection of the inert gas becomes a horizontal flow toward the inner wall of the immersion pipe on the surface of the steel bath in the immersion pipe, and the horizontal molten steel flow does not change to a completely downward flow on the inner wall of the immersion pipe. Forming the molten steel flow on the outside, the slag on the outside of the immersion tube is sufficiently stirred,
The lower oxide concentration in the slag outside the immersion tube can be further reduced.
【００１６】この発明において、浸漬管内径Ｄ1に対す
る取鍋内径Ｄ2の比（Ｄ1／Ｄ2）を０．５〜０．８とし
たのは、Ｄ1／Ｄ2が０．５未満では脱硫率、脱水素率が
十分でなく、また、０．８を超えると浸漬管寿命が大幅
に低下すると共に、浸漬管補修頻度が大幅に上昇するか
らである。すなわち、浸漬管の内径が大きいほど浸漬管
内の脱硫・脱水素反応が生じる反応界面の面積が増大
し、脱硫・脱水素反応速度が増加し、また、浸漬管の内
径が増加するにしたがって浸漬管外側の取鍋スラグ量の
比率が低減するため、脱水素処理後のガス撹拌処理にお
ける浸漬管外側のスラグ中の低級酸化物濃度の低減がよ
り容易となる。しかし、必要以上に浸漬管内径を大きく
すると浸漬管の溶損速度が高まり、耐火物の補修頻度が
増加したり、浸漬管寿命が低下するなどの問題を生じる
からである。In the present invention, the ratio (D 1 / D 2 ) of the inner diameter D 2 of the ladle to the inner diameter D 1 of the immersion tube is set to 0.5 to 0.8 because D 1 / D 2 is less than 0.5. In this case, the desulfurization rate and the dehydrogenation rate are not sufficient, and if it exceeds 0.8, the life of the immersion pipe is greatly reduced, and the frequency of repair of the immersion pipe is greatly increased. In other words, the larger the inner diameter of the immersion tube, the larger the area of the reaction interface where the desulfurization / dehydrogenation reaction occurs in the immersion tube, and the rate of the desulfurization / dehydrogenation reaction increases. Since the ratio of the outer ladle slag amount is reduced, the lower oxide concentration in the slag outside the immersion tube in the gas stirring process after the dehydrogenation process becomes easier. However, if the inner diameter of the immersion tube is made larger than necessary, the erosion speed of the immersion tube increases, and problems such as an increase in the frequency of repairing refractories and a reduction in the life of the immersion tube occur.
【００１７】また、この発明において、脱硫・脱水素処
理における浸漬管内の真空度を１００Ｔｏｒｒ以下とし
たのは、真空下で不活性ガスを吹き込むため、浸漬管内
の圧力が高くなるほど（真空度が悪化するほど）吹き込
みガスの撹拌力が弱くなり、平衡水素濃度が上昇し、浸
漬管内の真空度が１００Ｔｏｒｒを超えると、脱硫・脱
水素反応速度が著しく低下するからである。さらに、こ
の発明において、真空下での脱硫・脱水素処理したの
ち、浸漬管内を４００Ｔｏｒｒから大気圧下に保持し、
ガス撹拌処理する場合の浸漬管の溶鋼中への浸漬深さを
０．５ｍ以下としたのは、不活性ガス吹き込みにより生
じた溶鋼の上昇流が浸漬管内鋼浴表面で浸漬管内壁に向
かう水平流となり、浸漬管の溶鋼中への浸漬深さが０．
５ｍを超えると、その溶鋼流が浸漬管内壁で完全な下降
流へと変化するのに対し、浸漬管の溶鋼中への浸漬深さ
が０．５ｍ以下では、その水平溶鋼流が浸漬管内壁で完
全な下降流に変化せず、浸漬管外側での溶鋼流が形成さ
れ、浸漬管外側スラグの撹拌が可能となるからである。
また、ガス撹拌処理時間を２分間以上としたのは、ガス
撹拌処理時間が２分未満では、ガス撹拌処理の効果が十
分でなく、浸漬管外側のスラグ中の低級酸化物濃度が低
減しないからである。なお、ガス撹拌処理時間の上限
は、スラグ中の低級酸化物濃度によって変動するので、
特に限定するものではないが、通常５分程度で十分であ
る。Further, in the present invention, the reason why the degree of vacuum in the immersion tube in the desulfurization / dehydrogenation treatment is set to 100 Torr or less is that the inert gas is blown under vacuum, so that the higher the pressure in the immersion tube (the lower the degree of vacuum This is because when the stirring power of the blown gas is weakened, the equilibrium hydrogen concentration is increased, and the degree of vacuum in the immersion tube exceeds 100 Torr, the desulfurization / dehydrogenation reaction rate is significantly reduced. Further, in the present invention, after the desulfurization / dehydrogenation treatment under vacuum, the inside of the immersion tube is kept under atmospheric pressure from 400 Torr,
The reason why the immersion depth of the immersion tube in the molten steel in the case of performing the gas stirring treatment is set to 0.5 m or less is that the upward flow of the molten steel caused by the blowing of the inert gas is directed horizontally to the inner wall of the immersion tube at the steel bath surface in the immersion tube. And the immersion depth of the immersion tube into the molten steel is 0.
If it exceeds 5 m, the molten steel flow changes to a complete descending flow at the inner wall of the immersion pipe, whereas if the immersion depth of the immersion pipe into the molten steel is 0.5 m or less, the horizontal molten steel flow becomes This is because the molten steel flow is formed outside the immersion tube without changing to a complete downward flow, and the slag outside the immersion tube can be stirred.
In addition, the reason why the gas stirring time is set to 2 minutes or more is that if the gas stirring time is less than 2 minutes, the effect of the gas stirring treatment is not sufficient, and the lower oxide concentration in the slag outside the immersion tube does not decrease. It is. In addition, since the upper limit of the gas stirring treatment time varies depending on the concentration of the lower oxide in the slag,
Although not particularly limited, about 5 minutes is usually sufficient.
【００１８】さらにまた、この発明において、浸漬管内
を溶鋼中への浸漬して真空下で脱硫および脱水素処理す
るに先立つガス撹拌処理における浸漬管の溶鋼中への浸
漬深さ０．５ｍ以下で、ガス撹拌処理時間を２分以上行
うのは、脱硫および脱水素処理前のスラグ中の低級酸化
物濃度が非常に高い場合は、真空下での脱硫・脱水素後
の大気圧下のガス撹拌処理のみでは、完全に浸漬管外側
の取鍋スラグの改質が十分にできない場合があるため、
浸漬管外側スラグの撹拌により低級酸化物濃度を低減す
るためである。また、浸漬管内を復圧してガス撹拌処理
したのち、溶鋼に金属Ｃａ含有物質を添加すれば、同一
装置で真空下および大気圧処理を行える本発明法の特徴
を生かし、耐ＨＩＣ鋼を溶製することができる。また、
溶鋼への金属Ｃａ含有物質の添加は、上吹き、インジェ
クション、ワイヤー添加あるいは溶鋼上部より供給する
ことができる。さらに、真空下での脱硫処理時に脱硫用
粉体を浸漬管内に設置した上吹きランス、インジェクシ
ョンランスあるいは浸漬管内側の羽口から添加すれば、
脱硫処理時の脱硫速度、脱硫率を向上させることができ
る。浸漬管内を復圧してガス撹拌処理したのち、浸漬管
内にＣａＯあるいはＭｇＯを主成分とするスラグを添加
すれば、取鍋スラグの融点を上昇させ、固化したスラグ
による溶鋼の再酸化を防止すると共に、取鍋スラグと溶
鋼との間にＣａＯあるいはＭｇＯの濃度が高い層を形成
することによって、スラグによる溶鋼の再酸化を防止す
ることができる。Further, in the present invention, the immersion pipe is immersed in molten steel and subjected to a gas agitation treatment prior to desulfurization and dehydrogenation treatment under vacuum at a immersion depth of 0.5 m or less in the molten steel. When the gas agitation time is more than 2 minutes, if the concentration of lower oxides in the slag before desulfurization and dehydrogenation is very high, gas agitation under atmospheric pressure after desulfurization and dehydrogenation under vacuum The treatment alone may not be enough to completely modify the ladle slag outside the immersion tube,
This is because the lower oxide concentration is reduced by stirring the slag outside the immersion tube. In addition, after the pressure in the immersion pipe is restored and gas agitation treatment is performed, if a metal Ca-containing substance is added to the molten steel, HIC-resistant steel can be produced by utilizing the features of the method of the present invention, in which vacuum and atmospheric pressure treatment can be performed in the same apparatus. can do. Also,
The addition of the metal Ca-containing substance to the molten steel can be performed by top blowing, injection, wire addition, or supply from the top of the molten steel. Furthermore, if the powder for desulfurization is added from the upper blowing lance installed in the dip tube, the injection lance or the tuyere inside the dip tube during the desulfurization treatment under vacuum,
The desulfurization rate and desulfurization rate during the desulfurization treatment can be improved. After the pressure in the dip tube is restored and the gas is agitated, if the slag containing CaO or MgO as a main component is added to the dip tube, the melting point of the ladle slag is raised, and the re-oxidation of the molten steel by the solidified slag is prevented. By forming a layer having a high CaO or MgO concentration between the ladle slag and the molten steel, reoxidation of the molten steel by the slag can be prevented.
【００１９】[0019]
実施例１ 転炉から内径４ｍの２５０トン取鍋に出鋼時、脱硫フラ
ックスとしてＣａＯ８５％、ＣａＦ2１５％からなる脱
硫剤を溶鋼トン当たり１０ｋｇ添加して出鋼し、図１に
示すとおり、取鍋１に収容した硫黄濃度３０〜８０ｐｐ
ｍ、水素濃度５〜１５ｐｐｍの溶鋼２中に表１に示す内
径１．５〜３．５ｍの１本足浸漬管３を浸漬深さＬを
０．５ｍ以下で浸漬し、排気口４から真空引きして浸漬
管３内を真空排気し、０．８〜１．０Ｔｏｒｒの真空に
保持した状態で取鍋１底部のポーラスプラグ５からアル
ゴンガスを３Ｎｍ3／ｍｉｎで吹き込み、真空下で脱硫
・脱水素処理を行い、低水素極低硫鋼を溶製した。その
場合における浸漬管３内径Ｄ1に対する取鍋１内径Ｄ2の
比（Ｄ1／Ｄ2）と脱硫・脱水素結果を表１に示す。な
お、６は不活性ガス吹き込みランス、７は脱硫剤投入口
である。また、真空下で脱硫・脱水素処理後、浸漬管３
内を大気圧としたのち、取鍋１底部のポーラスプラグ５
からアルゴンガスを３Ｎｍ3／ｍｉｎで吹き込み、ガス
撹拌処理を行ない、ガス撹拌処理前後のスラグ中のＦｅ
Ｏ濃度を測定すると共に、溶鋼２の清浄度をＤ1／Ｄ2＝
０．３７５の場合を基準にして指数化した値を表２に示
す。また、浸漬管寿命および浸漬管補修頻度をＤ1／Ｄ2
＝０．３７５の場合を基準にして指数化した値を表２に
示す。なお、スラグ中のＦｅＯ濃度は、浸漬管外側で採
取したスラグ中のＦｅＯ濃度である。Example 1 At the time of tapping from a converter to a 250-ton ladle with an inner diameter of 4 m, a desulfurizing agent consisting of 85% CaO and 15% CaF 2 was added as a desulfurization flux by adding 10 kg per ton of molten steel, and tapping was performed, as shown in FIG. Sulfur concentration in ladle 1 30-80pp
m, a single-foot immersion pipe 3 having an inner diameter of 1.5 to 3.5 m shown in Table 1 at a immersion depth L of 0.5 m or less in molten steel 2 having a hydrogen concentration of 5 to 15 ppm The inside of the immersion tube 3 is evacuated to a vacuum, and while maintaining a vacuum of 0.8 to 1.0 Torr, argon gas is blown at 3 Nm 3 / min from the porous plug 5 at the bottom of the ladle 1 to perform desulfurization under vacuum. A dehydrogenation treatment was performed to produce a low hydrogen ultra low sulfur steel. Table 1 shows the ratio (D 1 / D 2 ) of the ladle 1 inner diameter D 2 to the immersion pipe 3 inner diameter D 1 in that case, and the results of desulfurization and dehydrogenation. Reference numeral 6 denotes a lance for blowing an inert gas, and reference numeral 7 denotes an inlet for a desulfurizing agent. After desulfurization and dehydrogenation treatment under vacuum,
After setting the inside to atmospheric pressure, the porous plug 5 at the bottom of the ladle 1
From the slag before and after the gas agitation by blowing argon gas at 3 Nm 3 / min.
While measuring the O concentration, the cleanliness of the molten steel 2 was determined as D 1 / D 2 =
Table 2 shows values indexed based on the case of 0.375. In addition, the life of the immersion pipe and the frequency of repair of the immersion pipe are set to D 1 / D 2
Table 2 shows values indexed based on the case of = 0.375. The FeO concentration in the slag is the FeO concentration in the slag collected outside the immersion tube.
【００２０】[0020]
【表１】 [Table 1]
【００２１】[0021]
【表２】 [Table 2]
【００２２】表１に示すとおり、真空下での脱硫・脱水
素処理時間は、１３〜１５分であり、浸漬管内径Ｄ1に
対する取鍋内径Ｄ2の比（Ｄ1／Ｄ2）が０．５以上で脱
硫率が大幅に上昇すると共に、脱水素率も大幅に上昇し
ており、浸漬管内径Ｄ1に対する取鍋内径Ｄ2の比（Ｄ1
／Ｄ2）が０．５以上が脱硫・脱水素条件として好まし
い。また、表２に示すとおり、浸漬管内径Ｄ1に対する
取鍋内径Ｄ2の比（Ｄ1／Ｄ2）が０．５以上で、スラグ
中のＦｅＯ濃度低減効果が顕著で、鋼の清浄性も大幅に
向上していると共に、浸漬管内径Ｄ1に対する取鍋内径
Ｄ2の比（Ｄ1／Ｄ2）が０．８以上で浸漬管の寿命が大
幅に低減し、補修頻度が著しく増加している。As shown in Table 1, the desulfurization / dehydrogenation treatment time under vacuum is 13 to 15 minutes, and the ratio (D 1 / D 2 ) of the ladle inner diameter D 2 to the immersion tube inner diameter D 1 is 0. with desulfurization rate .5 or higher is significantly increased, the dehydrogenation rate is greatly increased, the ratio of the ladle inner diameter D 2 with respect to the immersion tube inside diameter D 1 (D 1
/ D 2 ) is preferably 0.5 or more as desulfurization / dehydrogenation conditions. Further, as shown in Table 2, when the ratio (D 1 / D 2 ) of the ladle inner diameter D 2 to the immersion pipe inner diameter D 1 was 0.5 or more, the effect of reducing the FeO concentration in the slag was remarkable, and the cleanliness of the steel was improved. And the ratio (D 1 / D 2 ) of the inner diameter D 2 of the ladle to the inner diameter D 1 of the immersion pipe (D 1 / D 2 ) is 0.8 or more, the life of the immersion pipe is greatly reduced, and the repair frequency is significantly increased. doing.
【００２３】実施例２ 転炉から内径４ｍの２５０トン取鍋に出鋼時、脱硫フラ
ックスとしてＣａＯ８５％、ＣａＦ2１５％からなる脱
硫剤を溶鋼トン当たり１０ｋｇ添加して出鋼し、取鍋に
収容した硫黄濃度２０〜５０ｐｐｍ、水素濃度５〜１５
ｐｐｍの溶鋼中に内径１．５〜３．５ｍの１本足浸漬管
を深さ０．５ｍ以下で浸漬し、浸漬管内外を大気圧のま
まで取鍋底部のポーラスプラグからアルゴンガスを３Ｎ
ｍ3／ｍｉｎで吹き込んで１３〜１７分間脱硫処理した
のち、浸漬管内を真空排気して０．８〜１．１Ｔｏｒｒ
の真空に保持し、取鍋底部のポーラスプラグからアルゴ
ンガスを３Ｎｍ3／ｍｉｎで吹き込み、真空下で脱水素
処理を行い、低水素極低硫鋼を溶製した。その場合にお
ける浸漬管内径Ｄ1に対する取鍋内径Ｄ2の比（Ｄ1／
Ｄ2）と脱硫・脱水素結果を表３に示す。Example 2 When tapping steel from a converter to a 250-ton ladle with an inner diameter of 4 m, a desulfurizing agent consisting of 85% of CaO and 15% of CaF 2 was added as a desulfurization flux at a rate of 10 kg per ton of molten steel. Contained sulfur concentration 20-50 ppm, hydrogen concentration 5-15
A single-footed immersion pipe with an inner diameter of 1.5 to 3.5 m is immersed at a depth of 0.5 m or less in molten steel at a depth of 0.5 m or less.
After blowing for 13 to 17 minutes by blowing at m 3 / min, the inside of the immersion tube is evacuated to 0.8 to 1.1 Torr.
, And argon gas was blown in at 3 Nm 3 / min from a porous plug at the bottom of the ladle to perform dehydrogenation treatment under vacuum to melt low hydrogen ultra low sulfur steel. The ratio of the ladle inner diameter D 2 with respect to the immersion tube inner diameter D 1 in that case (D 1 /
Table 2 shows D 2 ) and the results of desulfurization and dehydrogenation.
【００２４】[0024]
【表３】 [Table 3]
【００２５】表３に示すとおり、大気圧下での脱硫時間
は、１３〜１５分であり、浸漬管内径Ｄ1に対する取鍋
内径Ｄ2の比（Ｄ1／Ｄ2）が０．５以上で脱硫率が大幅
に上昇すると共に、脱水素率も大幅に向上している。As shown in Table 3, the desulfurization time under atmospheric pressure is 13 to 15 minutes, and the ratio (D 1 / D 2 ) of the ladle inner diameter D 2 to the immersion tube inner diameter D 1 is 0.5 or more. As a result, the desulfurization rate has increased significantly, and the dehydrogenation rate has also improved significantly.
【００２６】実施例３ 転炉から内径４ｍの２５０トン取鍋に出鋼時、脱硫フラ
ックスとしてＣａＯ８５％、ＣａＦ2１５％からなる脱
硫剤を溶鋼トン当たり１０ｋｇ添加して出鋼し、取鍋に
収容した硫黄濃度２０〜５０ｐｐｍ、水素濃度５〜１５
ｐｐｍの溶鋼中に内径２．５ｍの１本足浸漬管を浸漬深
さを０．３〜１．０ｍの範囲で変化させて浸漬し、浸漬
管内を真空排気して１Ｔｏｒｒに保持し、取鍋底部のポ
ーラスプラグからアルゴンガスを３Ｎｍ3／ｍｉｎで吹
き込み、真空下で脱硫・脱水素処理を行い、低水素極低
硫鋼を溶製した。また、内径２．５ｍの１本足浸漬管を
浸漬深さを０．４ｍ一定とし、浸漬管内の真空度を１〜
１１０Ｔｏｒｒの範囲で変化させ、取鍋底部のポーラス
プラグからアルゴンガスを３Ｎｍ3／ｍｉｎで吹き込
み、真空下で１５分脱硫・脱水素処理を行い、低水素極
低硫鋼を溶製した。その場合における浸漬管の浸漬深さ
と脱硫率、脱水素率との関係を図２に、浸漬管内の真空
度と脱硫率、脱水素率との関係を図３に示す。Example 3 When tapping steel from a converter to a 250-ton ladle with an inner diameter of 4 m, a desulfurizing agent consisting of 85% CaO and 15% CaF 2 was added as a desulfurization flux by adding 10 kg per ton of molten steel, and tapping was performed. Contained sulfur concentration 20-50 ppm, hydrogen concentration 5-15
A single-foot immersion tube with an inner diameter of 2.5 m is immersed in molten steel of ppm with the immersion depth being changed in the range of 0.3 to 1.0 m, and the inside of the immersion tube is evacuated and maintained at 1 Torr. Argon gas was blown in from the bottom porous plug at 3 Nm 3 / min, and desulfurization / dehydrogenation treatment was performed under vacuum to produce low hydrogen ultra low sulfur steel. In addition, the immersion depth of a single-foot immersion tube having an inner diameter of 2.5 m is set to 0.4 m, and the degree of vacuum in the immersion tube is 1 to 1.
The pressure was changed within a range of 110 Torr, and argon gas was blown in at a rate of 3 Nm 3 / min from a porous plug at the bottom of the ladle, and desulfurization and dehydrogenation treatment was performed under vacuum for 15 minutes to produce a low hydrogen ultra low sulfur steel. FIG. 2 shows the relationship between the immersion depth of the immersion tube and the desulfurization rate and dehydrogenation rate, and FIG. 3 shows the relationship between the degree of vacuum in the immersion pipe and the desulfurization rate and dehydrogenation rate.
【００２７】図２に示すとおり、浸漬管の浸漬深さが
０．５ｍまでは、浸漬管内外のスラグの撹拌が十分で高
い脱硫率、脱水素率が得られているが、浸漬管の浸漬深
さが０．５ｍを超えると、脱硫率、脱水素率が低下して
いるのは、浸漬管外側のスラグの撹拌が不十分となった
ためと考えられる。また、図３に示すとおり、浸漬管内
の真空度が１１０Ｔｏｒｒで脱硫率、脱水素率が低下し
ているのは、脱硫・脱水素反応速度が著しく低下したた
めと考えられる。As shown in FIG. 2, the slag inside and outside the immersion pipe is sufficiently stirred to obtain a high desulfurization rate and dehydrogenation rate up to a immersion depth of 0.5 m. If the depth exceeds 0.5 m, the reason why the desulfurization rate and the dehydrogenation rate decrease is considered to be that the stirring of the slag outside the immersion tube was insufficient. In addition, as shown in FIG. 3, the reason why the desulfurization rate and the dehydrogenation rate decreased when the degree of vacuum in the immersion tube was 110 Torr is considered to be due to the remarkable decrease in the desulfurization / dehydrogenation reaction rate.
【００２８】実施例４ 転炉から内径４ｍの２５０トン取鍋に出鋼時、脱硫フラ
ックスとしてＣａＯ８５％、ＣａＦ2１５％からなる脱
硫剤を溶鋼トン当たり１０ｋｇ添加して出鋼し、取鍋に
収容した硫黄濃度２０〜５０ｐｐｍ、水素濃度５〜１５
ｐｐｍの溶鋼中に内径２．５ｍの１本足浸漬管を浸漬深
さ０．４ｍで浸漬し、浸漬管内を真空排気して１Ｔｏｒ
ｒに保持し、取鍋底部のポーラスプラグからアルゴンガ
スを３Ｎｍ3／ｍｉｎで吹き込み、真空下で脱硫・脱水
素処理を行い、その後浸漬管内を復圧すると同時にある
いは復圧後直ちに浸漬管内にＭｇＯを溶鋼トン当たり０
〜２ｋｇ添加し、さらにその後Ｃａ含有率３０％のＣａ
Ｓを溶鋼トン当たり１ｋｇ添加し、低水素極低硫鋼を溶
製した。得られた各鋼材は、０．８％ＣＨ3ＣＯＯＨを
添加した５％ＮａＣｌ水溶液にＨ2Ｓを１００〜２００
ｍｌ／ｍｉｎで供給して飽和させたｐＨ４．５（ｍａ
ｘ）、温度２４±２．８℃の溶液（ＮＡＣＥ浴）に９６
時間試験片を浸漬するシェルタイプの水素誘起割れ試験
を行った。その結果、ＭｇＯ添加量０ｋｇの鋼板は、割
れ発生率が０．００５％と非常に低かった。また、Ｍｇ
Ｏを溶鋼トン当たり２ｋｇ添加した鋼板は、割れ発生率
が０．００１％まで低下した。このように、真空下で脱
硫・脱水素処理を行ったのち、復圧してＣａ合金を添加
することによって、耐ＨＩＣ鋼を製造することができ
た。Example 4 At the time of tapping from a converter to a 250-ton ladle having an inner diameter of 4 m, a desulfurizing agent consisting of 85% of CaO and 15% of CaF 2 was added as a desulfurization flux at a rate of 10 kg per ton of molten steel. Contained sulfur concentration 20-50 ppm, hydrogen concentration 5-15
A single-foot immersion pipe with an inner diameter of 2.5 m is immersed in molten steel at a depth of 0.4 m, and the interior of the immersion pipe is evacuated and evacuated to 1 Torr.
r, and argon gas is blown in at 3 Nm 3 / min from a porous plug at the bottom of the ladle to perform desulfurization and dehydrogenation treatment under vacuum. 0 per ton of molten steel
~ 2 kg, and then Ca with a Ca content of 30%
S was added at 1 kg per ton of molten steel to produce a low hydrogen extremely low sulfur steel. Each of the obtained steel materials was prepared by adding H 2 S to a 5% NaCl aqueous solution to which 0.8% CH 3 COOH was added in an amount of 100 to 200%.
pH 4.5 (ma
x) 96 to a solution (NACE bath) at a temperature of 24 ± 2.8 ° C.
A shell-type hydrogen-induced cracking test in which a test piece was immersed for a time was performed. As a result, the steel sheet containing 0 kg of MgO had a very low cracking rate of 0.005%. In addition, Mg
The steel plate containing 2 kg of O per ton of molten steel had a crack generation rate reduced to 0.001%. As described above, after performing the desulfurization / dehydrogenation treatment under vacuum, the pressure was restored, and the Ca alloy was added, whereby the HIC-resistant steel could be manufactured.
【００２９】[0029]
【発明の効果】以上述べたとおり、この発明方法によれ
ば、真空下での脱硫・脱水素速度を高位に安定させ、取
鍋スラグ全体の低級酸化物濃度を低下せしめることによ
って、溶鋼中の硫黄ならびに水素濃度を低レベルに保持
して低水素極低硫鋼を溶製できると共に、耐火物の損耗
を抑制でき、浸漬管寿命の延長ならびに補修頻度を低減
できる。As described above, according to the method of the present invention, the desulfurization / dehydrogenation rate under vacuum is stabilized at a high level, and the lower oxide concentration in the entire ladle slag is reduced, whereby the molten steel in the molten steel is reduced. The sulfur and hydrogen concentrations can be maintained at low levels to produce low hydrogen ultra-low sulfur steel, refractory wear can be suppressed, the life of the immersion tube can be extended, and the frequency of repairs can be reduced.
【図１】この発明の脱硫・脱水素処理の説明図である。FIG. 1 is an explanatory view of a desulfurization / dehydrogenation treatment of the present invention.
【図２】実施例３における浸漬管の浸漬深さと脱硫率、
脱水素率との関係を示すグラフである。FIG. 2 shows the immersion depth and desulfurization rate of a dip tube in Example 3,
It is a graph which shows the relationship with a dehydrogenation rate.
【図３】実施例３における浸漬管内の真空度と脱硫率、
脱水素率との関係を示すグラフである。FIG. 3 shows the degree of vacuum and desulfurization rate in a dip tube in Example 3,
It is a graph which shows the relationship with a dehydrogenation rate.
１ 取鍋 ２ 溶鋼 ３ 浸漬管 ４ 排気口 ５ ポーラスプラグ ６ 不活性ガス吹き込みランス ７ 脱硫剤投入口 DESCRIPTION OF SYMBOLS 1 Ladle 2 Molten steel 3 Immersion pipe 4 Exhaust port 5 Porous plug 6 Inert gas blowing lance 7 Desulfurizer inlet
Claims (3)
鋼の精錬を行う方法において、浸漬管の内径Ｄ1と取鍋
の内径Ｄ2の比（Ｄ1／Ｄ2）が０．５以上０．８以下を
満足するような浸漬管および取鍋を用い、浸漬管内を４
００Ｔｏｒｒから大気圧下に保持し、かつ浸漬管を溶鋼
に浸漬深さ０．５ｍ以下で浸漬した状態で溶鋼中に不活
性ガスを２分間以上吹き込んでガス撹拌処理を行った後
に、浸漬管内を１００Ｔｏｒｒ以下の真空度に保持して
不活性ガスを溶鋼中に吹き込んで脱硫処理および脱水素
処理を行うことを特徴とする低水素極低硫鋼の溶製方
法。1. A method for refining molten steel by immersing a cylindrical immersion pipe in molten steel in a ladle, wherein the ratio (D 1 / D 2 ) of the inner diameter D 1 of the immersion pipe to the inner diameter D 2 of the ladle is adjusted. Use a dip tube and ladle that satisfies 0.5 or more and 0.8 or less, and
After maintaining the atmospheric pressure from 00 Torr and immersing the immersion tube in the molten steel at a immersion depth of 0.5 m or less, the inert gas was blown into the molten steel for at least 2 minutes to perform gas stirring treatment. A method for producing low-hydrogen ultra-low-sulfur steel, wherein desulfurization treatment and dehydrogenation treatment are performed by blowing an inert gas into molten steel while maintaining the degree of vacuum at 100 Torr or less.
鋼の精錬を行う方法において、浸漬管の内径Ｄ1と取鍋
の内径Ｄ2との比（Ｄ1／Ｄ2）が０．５以上０．８以下
を満足するような浸漬管および取鍋を用い、浸漬管内を
１００Ｔｏｒｒ以下の真空度に保持して不活性ガスを溶
鋼中に吹き込んで脱硫処理および脱水素処理を行った後
に、浸漬管内を４００Ｔｏｒｒから大気圧下に保持し、
かつ浸漬管を溶鋼に浸漬深さ０．５ｍ以下で浸漬した状
態で溶鋼中に不活性ガスを２分間以上吹き込んでガス撹
拌処理を行うことを特徴とする低水素極低硫鋼の溶製方
法。2. A method for refining molten steel by immersing a cylindrical immersion pipe in molten steel in a ladle, wherein a ratio (D 1 / D 2 ) of an inner diameter D 1 of the immersion pipe to an inner diameter D 2 of the ladle. Using an immersion tube and a ladle that satisfies 0.5 to 0.8, the inside of the immersion tube is maintained at a vacuum of 100 Torr or less, and an inert gas is blown into the molten steel to perform desulfurization treatment and dehydrogenation treatment. After performing, the inside of the immersion tube is maintained under the atmospheric pressure from 400 Torr,
And a method of injecting an inert gas into the molten steel for at least 2 minutes while immersing the immersion tube in the molten steel at a immersion depth of 0.5 m or less to perform gas agitation treatment, the method comprising: .
鋼の精錬を行う方法において、浸漬管の内径Ｄ1と取鍋
の内径Ｄ2の比（Ｄ1／Ｄ2）が０．５以上０．８以下を
満足するような浸漬管および取鍋を用い、浸漬管内を４
００Ｔｏｒｒから大気圧下に保持し、かつ浸漬管を溶鋼
に浸漬深さ０．５ｍ以下で浸漬した状態で溶鋼中に不活
性ガスを２分間以上吹き込んでガス撹拌処理を行った後
に、浸漬管内を１００Ｔｏｒｒ以下の真空度に保持して
不活性ガスを溶鋼中に吹き込んで脱硫処理および脱水素
処理を行い、その後再び浸漬管内を４００Ｔｏｒｒから
大気圧下に保持し、かつ浸漬管を溶鋼に浸漬深さ０．５
ｍ以下で浸漬した状態で溶鋼中に不活性ガスを２分間以
上吹き込んでガス撹拌処理を行うことを特徴とする低水
素極低硫鋼の溶製方法。3. A method for refining molten steel by dipping a cylindrical immersion tube in molten steel in a ladle, wherein the ratio (D 1 / D 2 ) of the inner diameter D 1 of the immersion tube to the inner diameter D 2 of the ladle is adjusted. Use a dip tube and ladle that satisfies 0.5 or more and 0.8 or less, and
After maintaining the atmospheric pressure from 00 Torr and immersing the immersion tube in the molten steel at a immersion depth of 0.5 m or less, the inert gas was blown into the molten steel for at least 2 minutes to perform gas stirring treatment. Inert gas is blown into the molten steel while maintaining the degree of vacuum at 100 Torr or less to perform desulfurization treatment and dehydrogenation treatment. Thereafter, the inside of the immersion tube is again maintained at 400 Torr under atmospheric pressure, and the immersion tube is immersed in the molten steel at a depth of immersion. 0.5
A method for producing a low hydrogen ultra low sulfur steel, characterized by performing a gas agitation treatment by blowing an inert gas into the molten steel for 2 minutes or more in a state of being immersed at a temperature of not more than m.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19475394A JP2897647B2 (en) | 1994-07-26 | 1994-07-26 | Melting method of low hydrogen extremely low sulfur steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19475394A JP2897647B2 (en) | 1994-07-26 | 1994-07-26 | Melting method of low hydrogen extremely low sulfur steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0841523A JPH0841523A (en) | 1996-02-13 |
| JP2897647B2 true JP2897647B2 (en) | 1999-05-31 |
Family
ID=16329667
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19475394A Expired - Lifetime JP2897647B2 (en) | 1994-07-26 | 1994-07-26 | Melting method of low hydrogen extremely low sulfur steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2897647B2 (en) |
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|---|---|---|---|---|
| CN102564156B (en) * | 2010-12-07 | 2014-04-02 | 宜兴市瑞华新型炉料厂 | Production method capable of prolonging service life of KR (Krypton) stirrer |
-
1994
- 1994-07-26 JP JP19475394A patent/JP2897647B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0841523A (en) | 1996-02-13 |
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