JPH0649524A - Production of highly clean steel - Google Patents
Production of highly clean steelInfo
- Publication number
- JPH0649524A JPH0649524A JP4203899A JP20389992A JPH0649524A JP H0649524 A JPH0649524 A JP H0649524A JP 4203899 A JP4203899 A JP 4203899A JP 20389992 A JP20389992 A JP 20389992A JP H0649524 A JPH0649524 A JP H0649524A
- Authority
- JP
- Japan
- Prior art keywords
- slag
- molten steel
- ladle
- steel
- added
- 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.)
- Pending
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は高清浄鋼の製造方法に係
り、特に真空二次精錬におけるスラグを改質して、Ａｌ
2 Ｏ3 吸収能を向上させ、鋼中の［Ｏ］濃度及びＡｌ2
Ｏ3 介在物の極めて少ない優れた高清浄鋼を製造する方
法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing high-cleanliness steel, in particular, by modifying the slag in vacuum secondary refining to obtain Al.
2 O 3 absorption ability improves, in the steel [O] concentration and Al 2
The present invention relates to a method for producing an excellent highly clean steel having very few O 3 inclusions.
【０００２】[0002]
【従来の技術】近年、自動車鋼板を中心とした冷延鋼板
に対する需要者の要求は一段と厳しさを増し、これに伴
い極低炭素鋼の低酸素化、高清浄化が求められている。2. Description of the Related Art In recent years, demands from customers for cold-rolled steel sheets centering on automobile steel sheets have become more and more severe, and accordingly, extremely low carbon steels have been required to have low oxygen and high cleanliness.
【０００３】製鋼工程においては、極低炭素鋼の溶鋼清
浄化には真空二次精錬が重要な役割を果たしており、溶
鋼清浄化の徹底を図るためには真空二次精錬において溶
鋼汚染の原因となる取鍋スラグを脱酸、無害化し、Ａｌ
2 Ｏ3 介在物吸収能の高いスラグとすることが重要であ
る。In the steelmaking process, vacuum secondary refining plays an important role in cleaning molten steel of ultra low carbon steel, and in order to thoroughly purify molten steel, it is a cause of contamination of molten steel in the vacuum secondary refining. Deoxidize and detoxify ladle slag
It is important to use a slag having a high ability to absorb 2 O 3 inclusions.
【０００４】一般に極低炭素鋼の製造プロセスは、先ず
大気圧下で酸素を吹き込んで鉄の酸化損失の少ないＣ：
０．０３〜０．０５％まで粗脱炭する工程と、粗脱炭し
た溶鋼を取鍋に受鋼するに当たりスラグ脱酸剤を添加し
て溶鋼上に浮遊するスラグを改質する工程と、この溶鋼
を真空脱ガス処理する工程とからなっている。上記の如
きスラグの改質を図り高清浄鋼を得るために、従来多く
の提案がなされている。Generally, in the production process of ultra-low carbon steel, C is blown with oxygen at atmospheric pressure to reduce iron oxidation loss:
A step of roughly decarburizing to 0.03 to 0.05%; a step of modifying the slag floating on the molten steel by adding a slag deoxidizing agent when receiving the roughly decarburized molten steel in a ladle; This molten steel is vacuum degassed. Many proposals have heretofore been made in order to improve the slag as described above and obtain highly clean steel.
【０００５】例えば、特開昭６０−１５２６１１には
「溶鋼鍋内の溶鋼上に浮遊しているスラグ上にスラグ還
元剤を添加して酸化性スラグを改質する方法において、
上記スラグ還元剤と共にガス発生物質を併用添加するス
ラグ改質方法。」が開示されている。ガス発生物質とし
てはＣａＣＯ3 を使用し、溶鋼を撹拌するほか、生成し
たＣａＯにより溶鋼汚染物質のＦｅＯ、ＭｎＯ等を希釈
できるとしている。For example, in Japanese Patent Laid-Open No. 60-152611, "In a method for modifying an oxidizing slag by adding a slag reducing agent to slag floating on molten steel in a molten steel ladle,
A slag reforming method in which a gas generating substance is added together with the slag reducing agent. Is disclosed. It is stated that CaCO 3 is used as the gas generating substance, the molten steel is stirred, and the generated CaO can dilute the molten steel contaminants such as FeO and MnO.
【０００６】しかしながら、この方法では、ガス発生物
質としてＣａＣＯ3 を使用するため、ＣａＣＯ3 の熱分
解反応時の吸熱によりスラグの温度が低下してスラグの
流動性が悪化し、さらに、溶鋼の温度降下が不可避とな
るため、その分出鋼温度を上乗せしなければならないと
いう問題点がある。またスラグ還元剤としてＡｌを使用
した際には、スラグ還元時に発生するＡｌ2 Ｏ3 がＣａ
ＣＯ3 の熱分解によって生ずるＣＯ2 ガスによって大気
中に巻き上げられ多量の発塵の原因となるなど、環境上
の問題もある。However, in this method, since CaCO 3 is used as the gas generating substance, the temperature of the slag is lowered due to the endotherm during the thermal decomposition reaction of CaCO 3 , and the fluidity of the slag is deteriorated. Since the descent is inevitable, there is a problem that the tapped steel temperature must be increased accordingly. When Al is used as a slag reducing agent, Al 2 O 3 generated during slag reduction is Ca
There is also an environmental problem that CO 2 gas generated by the thermal decomposition of CO 3 is entrained in the atmosphere and causes a large amount of dust.
【０００７】また、特開平４−７２００９には「転炉等
の精錬炉で溶製した溶鋼を取鍋に出鋼する工程と前記取
鍋に受鋼した溶鋼上に浮遊するスラグを改質する工程
と、前記改質した溶鋼を真空脱ガス処理する工程とを有
して成る高清浄度鋼の溶製方法において、前記転炉等に
よる溶製工程においては予備処理溶銑を使用して未脱酸
のまま出鋼し、前記スラグの改質工程においては金属Ａ
ｌを含むＡｌ滓を還元剤として使用し、Ａｌ滓添加後の
取鍋内スラグに生石灰粉を添加してスラグ中の（Ｃａ
Ｏ）／（Ａｌ2 Ｏ3 ）の比を１．６〜１．８に制御する
ことを特徴とする高清浄度鋼の溶製方法。」が開示され
ている。Further, in Japanese Patent Laid-Open No. 4-72009, "Process of tapping molten steel melted in a refining furnace such as a converter into a ladle and reforming slag floating on the molten steel received in the ladle. In the method for smelting high-cleanliness steel, which comprises a step and a step of subjecting the modified molten steel to a vacuum degassing process, in the smelting step using the converter, etc. The acid is tapped, and metal A is used in the slag reforming process.
Using Al slag containing 1 as a reducing agent, quicklime powder was added to the slag in the ladle after the addition of Al slag to obtain (Ca
A method for smelting high-cleanliness steel, characterized in that the ratio of (O) / (Al 2 O 3 ) is controlled to be 1.6 to 1.8. Is disclosed.
【０００８】しかしながら、この方法では、Ａｌ滓添加
後に生石灰を投入するため、添加した生石灰が溶解しに
くく、（ＣａＯ）／（Ａｌ2 Ｏ3 ）の比を適切にコント
ロールするのが難い。従って、かえってスラグの流動性
を低下させてしまう危険性がある。また（ＣａＯ）／
（Ａｌ2 Ｏ3 ）の比を真空二次精錬直前で１．６〜１．
８という比較的高い値とした場合、真空二次精錬後も
０．９〜１．１という高い値となってスラグは依然溶融
状態のままとなるため、鋳造中の鍋交換時には取鍋スラ
グが連続鋳造のタンデッシュ内に流出し、ひいてはスラ
グが鋳型内に流出するという問題点がある。さらに復り
ん防止のために予備処理溶銑（脱りん溶銑）を使用しな
ければならないという工程上の制約もある。However, in this method, quick lime is added after the addition of Al slag, so the quick lime added is difficult to dissolve, and it is difficult to properly control the ratio of (CaO) / (Al 2 O 3 ). Therefore, there is a risk that the fluidity of the slag is rather lowered. Also (CaO) /
The ratio of (Al 2 O 3 ) is 1.6 to 1. Immediately before the secondary vacuum refining.
A relatively high value of 8 results in a high value of 0.9 to 1.1 even after the secondary vacuum refining, and the slag remains in a molten state. There is a problem that the slag flows out into the tundish of continuous casting, and the slag flows out into the mold. Further, there is a process restriction that pretreatment hot metal (dephosphorized hot metal) must be used to prevent re-phosphorization.
【０００９】[0009]
【発明が解決しようとする課題】本発明は、かかる事情
に鑑みてなされたもであって、転炉から出鋼された溶鋼
において、取鍋スラグの（Ｔ．Ｆｅ）を低減し、スラグ
のＡｌ2 Ｏ3 吸収能を向上させると同時に、取鍋スラグ
の連続鋳造タンデッシュ内流出を抑えた高清浄鋼の製造
方法を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in molten steel tapped from a converter, (T.Fe) of ladle slag is reduced to reduce slag content. An object of the present invention is to provide a method for producing high-purity steel that improves the Al 2 O 3 absorption capacity and at the same time suppresses the outflow of ladle slag into the continuous casting tundish.
【００１０】[0010]
【課題を解決するための手段】本発明は、上記課題を解
決するために、精錬炉で溶鋼を溶製する工程と、この溶
鋼を取鍋に出鋼する工程と、前記取鍋に受鋼した溶鋼上
に浮遊するスラグを脱酸する工程と、その溶鋼を真空脱
ガス処理する工程とを具備する高清浄鋼の製造方法であ
って、前記精錬炉で溶鋼を溶製する工程においては、溶
鋼を未脱酸のまま出鋼するとともに出鋼中の溶鋼に石灰
を添加し、また前記スラグの脱酸工程においては、金属
Ａｌをスラグ脱酸剤として添加して、スラグ中の（Ｃａ
Ｏ）／（Ａｌ2 Ｏ3 ）の比を、Ａｌ添加直後に１．３〜
１．５、真空脱ガス後に０．６〜０．８として真空脱ガ
ス後の取鍋スラグを固化させることを特徴とする高清浄
鋼の製造方法を提供する。SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a step of producing molten steel in a refining furnace, a step of tapping the molten steel into a ladle, and a steel receiving in the ladle. A method of producing highly clean steel comprising a step of deoxidizing slag floating on molten steel, and a step of vacuum degassing the molten steel, in the step of melting molten steel in the refining furnace, The molten steel is undeoxidized while being tapped, lime is added to the molten steel in the tapping, and in the slag deoxidizing step, metal Al is added as a slag deoxidizer to obtain (Ca
The ratio of (O) / (Al 2 O 3 ) should be 1.3-
Provided is a method for producing highly clean steel, characterized in that the ladle slag after vacuum degassing is solidified to 1.5 to 0.6 to 0.8 after vacuum degassing.
【００１１】本発明においては、転炉などの精錬炉にお
いて溶銑を粗脱炭精錬し、未脱酸のままいわゆるリムド
出鋼し、出鋼の際溶鋼中に石灰を添加し、出鋼終了後直
ちに金属Ａｌを取鍋スラグ上に均一に添加する。金属Ａ
ｌはスラグ中の（Ｔ．Ｆｅ）低減を目的として添加する
ため、その添加量はスラグ中の（Ｔ．Ｆｅ）値によって
決定される。しかしながら、取鍋スラグの組成を分析し
てその結果によることは時間の制約上できないので、金
属Ａｌの添加量は転炉の吹き止め時の酸素含有量によっ
て決定される。すなわち、吹き止め時の酸素含有量に対
して金属Ａｌを １．２×１０-3×酸素含有量［ppm ］−０．３５（酸素
含有量≧３００ppm ） の原単位で添加する。In the present invention, the hot metal is roughly decarburized and refined in a refining furnace such as a converter, so-called rimmed steel is tapped in the undeoxidized state, lime is added to the molten steel during tapping, and after tapping is finished. Immediately add metallic Al evenly onto the ladle slag. Metal A
Since l is added for the purpose of reducing (T.Fe) in the slag, the amount of addition is determined by the (T.Fe) value in the slag. However, since it is not possible to analyze the composition of the ladle slag and the result thereof due to time constraints, the addition amount of metallic Al is determined by the oxygen content at the time of blowing off the converter. That is, metallic Al is added in a basic unit of 1.2 × 10 −3 × oxygen content [ppm] -0.35 (oxygen content ≧ 300 ppm) with respect to oxygen content at the time of blowing.
【００１２】本願発明者らは真空二次精錬処理前のスラ
グ中の（Ｔ．Ｆｅ）を４％以下に低減し、かつＡｌによ
る生成Ａｌ2 Ｏ3 吸収能の高いスラグ組成に制御するた
め、石灰添加後金属Ａｌを投入してスラグ改質を行うこ
とを試みた。なお、本願発明者らの実験においては添加
石灰は粒径３０ｍｍ以下の焼石灰を、金属ＡｌとしてＡ
ｌ箔を使用した。In order to reduce the (T.Fe) content in the slag before the secondary vacuum refining treatment to 4% or less and to control the slag composition to have a high Al 2 O 3 absorption capacity by Al, After adding lime, it was tried to introduce metallic Al to perform slag modification. In addition, in the experiments conducted by the inventors of the present application, as the added lime, burned lime having a particle diameter of 30 mm or less was used as metal Al.
1 foil was used.
【００１３】本願発明者らは、石灰の添加に当たり、ス
ラグ中の（ＣａＯ）／（Ａｌ2 Ｏ3）の比を種々変えて
スラグのＡｌ2 Ｏ3 吸収能について調査した結果、（Ｃ
ａＯ）／（Ａｌ2 Ｏ3 ）の比が１．０〜１．８の範囲に
おいては、スラグのＡｌ2 Ｏ3 吸収能は大差ないことを
見出した。そのことを図１に示す。なお、Ａｌ2 Ｏ3吸
収能とは真空二次精錬後のスラグのＡｌ2 Ｏ3 ％から二
次精錬前のスラグのＡｌ2 Ｏ3 ％を引いたものであり同
一スラグ量（スラグ厚み）のヒートで比較した。The inventors of the present application investigated the Al 2 O 3 absorption capacity of the slag by changing the ratio of (CaO) / (Al 2 O 3 ) in the slag when adding lime.
It was found that when the ratio of (aO) / (Al 2 O 3 ) is in the range of 1.0 to 1.8, the Al 2 O 3 absorption capacity of the slag is not so different. This is shown in FIG. The Al 2 O 3 absorption capacity is obtained by subtracting the Al 2 O 3 % of the slag before the secondary refining from the Al 2 O 3 % of the slag after the vacuum secondary refining, which is the same as the slag amount (slag thickness). We compared by heat.
【００１４】この結果を踏まえて、本発明においては、
取鍋スラグの改質に当たり石灰添加後金属Ａｌを添加し
て（ＣａＯ）／（Ａｌ2 Ｏ3 ）の比を真空二次精錬直前
で１．３〜１．５となるように制御する方法をとること
とした。（ＣａＯ）／（Ａｌ2 Ｏ3 ）の比をこのような
範囲に限定したのは、高いＡｌ2 Ｏ3 吸収能を確保しつ
つ真空二次精錬後にはスラグが固化するようにするため
である。図２に示す如く、真空二次精錬処理時に発生す
るＡｌ2 Ｏ3 がスラグに吸収されることにより、スラグ
の（ＣａＯ）／（Ａｌ2 Ｏ3 ）は低下し、自ずと０．６
〜０．８付近に低下し徐々に取鍋スラグは固化するので
ある。なお、真空二次精錬炉としては、通常のＲＨ炉、
ＤＨ炉等を用いることができる。また、上記図２は真空
二次精錬炉としてＲＨ炉を使用した場合の結果を示した
ものであり、図中ＲＨｉは真空二次精錬開始時を示し、
ＲＨｆは終了時を示す。Based on this result, in the present invention,
In the modification of ladle slag, a method of controlling the ratio of (CaO) / (Al 2 O 3 ) to 1.3 to 1.5 immediately before the secondary refining by adding metal Al after adding lime. I decided to take it. The ratio of (CaO) / (Al 2 O 3 ) is limited to such a range in order to secure a high Al 2 O 3 absorption capacity and to make the slag solidify after the vacuum secondary refining. . As shown in FIG. 2, since the Al 2 O 3 generated during the vacuum secondary refining process is absorbed by the slag, the (CaO) / (Al 2 O 3 ) of the slag decreases, and the slag is naturally reduced to 0.6.
It decreases to around 0.8 and the ladle slag solidifies gradually. As the vacuum secondary refining furnace, an ordinary RH furnace,
A DH furnace or the like can be used. Further, FIG. 2 shows the result when the RH furnace is used as the vacuum secondary refining furnace, and in the figure, RHi indicates the start of the vacuum secondary refining,
RHf indicates the end time.
【００１５】[0015]
【作用】本発明においては、転炉出鋼中に石灰を添加す
るため、予備処理溶銑を使用しない場合においても出鋼
中の復りん量は極めて少ない。In the present invention, since lime is added to the steel output from the converter, the amount of reconstituted phosphorus in the steel output is extremely small even when the pretreated hot metal is not used.
【００１６】また、石灰添加後に金属Ａｌを添加するの
で、テルミット反応による多量の熱が添加した石灰を容
易に溶解する。従って出鋼中にスラグの流動性が低下す
ることはなく、スラグの（Ｔ．Ｆｅ）は均一に低減する
ことができる。さらに、ガス発生物質を用いないためス
ラグに金属Ａｌを投入する際の発塵も少ない。Further, since the metal Al is added after the addition of lime, a large amount of heat due to the Thermit reaction easily dissolves the added lime. Therefore, the fluidity of the slag does not decrease during tapping, and the (T.Fe) of the slag can be uniformly reduced. Further, since no gas generating substance is used, dust is less generated when metal Al is added to the slag.
【００１７】一方、スラグ中の（ＣａＯ）／（Ａｌ2 Ｏ
3 ）の比は真空二次精錬処理前は１．３〜１．５の範囲
に調整されているので、真空二次精錬におけるＡｌ脱酸
処理中に発生するＡｌ2 Ｏ3 介在物は効率よくスラグに
吸収され、かつスラグの（Ｔ．Ｆｅ）は安定して低減さ
れているので溶鋼再酸化の可能性も極めて低い。さらに
Ａｌ2 Ｏ3 介在物を吸収したスラグの（ＣａＯ）／（Ａ
ｌ2 Ｏ3 ）比は自ずと０．６〜０．８の範囲に低下し、
徐々にスラグは固化し、これにより鋳造中の鍋交換時に
発生する連続鋳造タンデッシュ内への取鍋スラグの流出
も抑制され、安定して高清浄鋼を製造することができ
る。On the other hand, (CaO) / (Al 2 O in the slag
Since the ratio of 3 ) is adjusted in the range of 1.3 to 1.5 before the secondary vacuum refining treatment, Al 2 O 3 inclusions generated during the Al deoxidizing treatment in the secondary vacuum refining are efficiently generated. Since it is absorbed by the slag and the (T.Fe) of the slag is stably reduced, the possibility of molten steel reoxidation is extremely low. Furthermore, (CaO) / (A of the slag that absorbed Al 2 O 3 inclusions
The l 2 O 3 ) ratio naturally decreases to the range of 0.6 to 0.8,
The slag is gradually solidified, whereby the outflow of the ladle slag into the continuous casting tundish, which occurs when the pot is replaced during casting, is also suppressed, and highly clean steel can be stably produced.
【００１８】[0018]
【実施例】以下、本発明の実施例について説明する。EXAMPLES Examples of the present invention will be described below.
【００１９】同一鋼種の普通銑を用い、本発明の実施例
では溶銑の脱燐を行わずに、従来例１、２ではＰ＝０．
０２０％まで脱りんした脱りん銑を用い、いずれも未脱
酸で取鍋へ出鋼した。出鋼時の酸素含有量は７００ppm
であった。Using ordinary pig iron of the same steel type, in the examples of the present invention, dephosphorization of the hot metal was not performed, and in the conventional examples 1 and 2, P = 0.
Using dephosphorized pig iron that had been dephosphorized to 020%, all were undeoxidized and tapped into a ladle. Oxygen content at tapping is 700ppm
Met.
【００２０】実施例の方法では、出鋼中に溶鋼に焼石灰
を１．３kg／ｔ添加し、出鋼終了後にＡｌ箔を０．４９
kg／ｔ添加して、（ＣａＯ）／（Ａｌ2 Ｏ3 ）が１．３
〜１．５になるようにした。一方、従来例１の方法で
は、出鋼中に溶鋼に生石灰を１．７kg／ｔ添加し、出鋼
終了後にＡｌ滓を１．９kg／ｔ添加した。また、従来例
２の方法では、出鋼終了後にＡｌ滓を１．５kg／ｔ添加
し、その後取鍋スラグの（ＣａＯ）／（Ａｌ2 Ｏ3 ）が
１．６〜１．８になるように生石灰を１．７kg／ｔ添加
した。その後、いずれも１５分間の脱炭処理及び１０分
間のＡｌ脱酸処理の真空二次精錬を行い、その処理が終
了後、無酸化注入により溶鋼を連続鋳造した。上記製造
条件を表１にまとめて記載する。同じく表１に改質材投
入時の発塵状況、鋳造された鋳片の酸素含有量、および
連々鋳５ヒート目のタンデッシュ内スラグ厚みを示し
た。In the method of the embodiment, 1.3 kg / t of burnt lime was added to molten steel during tapping, and 0.49 g of Al foil was added after tapping.
Addition of kg / t gives (CaO) / (Al 2 O 3 ) 1.3
It was set to ~ 1.5. On the other hand, in the method of Conventional Example 1, quick lime 1.7 kg / t was added to the molten steel during tapping, and 1.9 kg / t of Al slag was added after tapping. Further, in the method of Conventional Example 2, after the completion of tapping, 1.5 kg / t of Al slag was added, and then (CaO) / (Al 2 O 3 ) of the ladle slag was set to 1.6 to 1.8. 1.7 kg / t of lime was added. After that, vacuum secondary refining of 15 minutes of decarburizing treatment and 10 minutes of Al deoxidizing treatment was performed, and after the treatment was completed, molten steel was continuously cast by non-oxidizing injection. The above production conditions are summarized in Table 1. Similarly, Table 1 shows the dust generation state at the time of introducing the modifier, the oxygen content of the cast slab, and the slag thickness in the tundish at the fifth heat of continuous casting.
【００２１】[0021]
【表１】 [Table 1]
【００２２】表１から明らかなように、実施例は従来例
に比して、改質材投入時の発塵が少なく、タンデッシュ
内への取鍋スラグの流出も少なく、鋳片の酸素含有量の
少ない優れた清浄度を有していることが確認された。As is clear from Table 1, in the embodiment, as compared with the conventional example, less dust is generated when the modifier is added, less outflow of ladle slag into the tundish, and oxygen content of the slab. It was confirmed that it has excellent cleanliness with less.
【００２３】[0023]
【発明の効果】本発明によれば、転炉から取鍋への出鋼
に際しまず石灰を添加し、次に（ＣａＯ）／（Ａｌ2 Ｏ
3 ）の比が１．３〜１．５の範囲になる如く金属Ａｌを
添加し、真空二次精錬中のスラグのＡｌ2 Ｏ3 介在物吸
収能を向上させるとともに、真空二次精錬後にスラグを
固化させ鋳造時に取鍋からタンデッシュ内へ流出するス
ラグ量を低減することによって、次の効果を有する鋼清
浄鋼の製造方法が提供される。 （イ）鋳片中のＴ［Ｏ］（全酸素量）が２０ｐｐｍ未満
の高清浄鋼を安定して製造することができる。 （ロ）改質材投入時の発塵を抑制することができる。 （ハ）タンデッシュスラグの鋳型内流出による品質異常
が減少する。According to the present invention, when steel is tapped from the converter to the ladle, lime is first added, and then (CaO) / (Al 2 O).
Metal Al is added so that the ratio of 3 ) is in the range of 1.3 to 1.5 to improve the absorption capacity of Al 2 O 3 inclusions in the slag during the vacuum secondary refining, and the slag after the vacuum secondary refining is added. By solidifying and reducing the amount of slag flowing out from the ladle into the tundish during casting, a method for producing a steel-cleaning steel having the following effects is provided. (Ii) T [O] (total oxygen content) in the cast slab can stably produce highly clean steel of less than 20 ppm. (B) It is possible to suppress dust generation when the modifier is added. (C) Abnormal quality due to outflow of tundish slag into the mold is reduced.
【図１】真空二次精錬前の取鍋スラグの（ＣａＯ）／
（Ａｌ2 Ｏ3 ）比とスラグのＡｌ2 Ｏ3 吸収能との関係
を示す図。[Fig.1] (CaO) of ladle slag before vacuum secondary refining
(Al 2 O 3) ratio and illustrates the relationship between the Al 2 O 3 absorption capacity of the slag.
【図２】真空二次精錬前後のスラグ組成およびその状態
を示すスラグ組成図。FIG. 2 is a slag composition diagram showing the slag composition before and after vacuum secondary refining and its state.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 小松 喜美 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshimi Komatsu 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.
Claims (1)
を取鍋に出鋼する工程と、前記取鍋に受鋼した溶鋼上に
浮遊するスラグを脱酸する工程と、その溶鋼を真空脱ガ
ス処理する工程とを具備する高清浄鋼の製造方法であっ
て、前記精錬炉で溶鋼を溶製する工程においては、溶鋼
を未脱酸のまま出鋼するとともに出鋼中の溶鋼に石灰を
添加し、また前記スラグの脱酸工程においては、金属Ａ
ｌをスラグ脱酸剤として添加して、スラグ中の（Ｃａ
Ｏ）／（Ａｌ2 Ｏ3 ）の比を、Ａｌ添加直後に１．３〜
１．５、真空脱ガス後に０．６〜０．８として真空脱ガ
ス後の取鍋スラグを固化させることを特徴とする高清浄
鋼の製造方法。1. A step of producing molten steel in a refining furnace, a step of tapping the molten steel in a ladle, a step of deoxidizing slag floating on the molten steel received in the ladle, and the molten steel. A method for producing high-purity steel, which comprises degassing the molten steel in the refining furnace in the step of producing molten steel in the refining furnace while undeoxidizing the molten steel. Lime is added to the slag, and in the deoxidizing step of the slag, metal A
1 was added as a slag deoxidizer, and (Ca
The ratio of (O) / (Al 2 O 3 ) should be 1.3-
1.5, A method for producing highly clean steel, characterized in that the ladle slag after vacuum degassing is solidified by setting it to 0.6 to 0.8 after vacuum degassing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4203899A JPH0649524A (en) | 1992-07-30 | 1992-07-30 | Production of highly clean steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4203899A JPH0649524A (en) | 1992-07-30 | 1992-07-30 | Production of highly clean steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0649524A true JPH0649524A (en) | 1994-02-22 |
Family
ID=16481562
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4203899A Pending JPH0649524A (en) | 1992-07-30 | 1992-07-30 | Production of highly clean steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0649524A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9855728B2 (en) | 2001-02-20 | 2018-01-02 | Kingspan Insulation Llc | Protective drainage wraps |
-
1992
- 1992-07-30 JP JP4203899A patent/JPH0649524A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9855728B2 (en) | 2001-02-20 | 2018-01-02 | Kingspan Insulation Llc | Protective drainage wraps |
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