JP2000087128A - Secondary refining method of molten steel - Google Patents
Secondary refining method of molten steelInfo
- Publication number
- JP2000087128A JP2000087128A JP10253497A JP25349798A JP2000087128A JP 2000087128 A JP2000087128 A JP 2000087128A JP 10253497 A JP10253497 A JP 10253497A JP 25349798 A JP25349798 A JP 25349798A JP 2000087128 A JP2000087128 A JP 2000087128A
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- treatment
- inclusion
- deoxidizing
- alloy
- 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.)
- Granted
Links
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、溶鋼の二次精錬方
法に関し、特に、清浄鋼の製造に好適な溶鋼の二次精錬
方法に関する。The present invention relates to a method for secondary refining of molten steel, and more particularly to a method for secondary refining of molten steel suitable for producing clean steel.
【0002】[0002]
【従来の技術】転炉等で一次精錬して出鋼した溶鋼をさ
らに二次精錬する方法として、真空度を10〜300mmHg と
して真空脱ガス処理を行い、この間に製品用途に応じ所
望の合金元素を添加し、成分調整を行う方法(以下真空
処理という)がある。この処理プロセスは、一般に、脱
炭、脱酸、成分調整合金添加、攪拌を順次行うというも
のである。2. Description of the Related Art As a method of further refining molten steel produced by primary refining in a converter or the like and then tapping, a vacuum degree of 10 to 300 mmHg is applied and vacuum degassing is performed. To adjust the components (hereinafter referred to as vacuum treatment). In this treatment process, generally, decarburization, deoxidation, addition of a component adjusting alloy, and stirring are sequentially performed.
【0003】その具体例として、特開昭57−73118 号公
報に、溶鋼を真空脱ガス処理中に所望の合金元素を分割
ないし一括して真空脱ガス処理槽内の溶鋼に添加して清
浄鋼を製造する方法において、前記所望の合金元素の最
終添加後、少なくとも(V/F)×aで表される時間t
1 (分)、真空度10〜300 (mmHg)で該溶鋼を攪拌、揺
動処理することが記載されている。ここに、V:溶鋼量
(t) 、F:環流量(t/分) 、a:製品に要求される清浄
度によって決まる定数(範囲:1〜10)である。この方
法は、真空脱ガス法の大きな攪拌力またはDH式真空脱
ガス処理の大きな揺動力を、介在物の衝突凝集(合体)
に利用し、極小の介在物に至るまで浮上効率を上げて清
浄度を高めようとするもので、その合体浮上に必要な時
間として前記時間t1 を規制したものである。[0003] As a specific example, Japanese Patent Application Laid-Open No. 57-73118 discloses a method in which a desired alloy element is divided or collectively added to molten steel in a vacuum degassing tank during the vacuum degassing treatment of molten steel. After the final addition of the desired alloying element, at least a time t represented by (V / F) × a
It describes that the molten steel is stirred and oscillated at 1 (minute) and a degree of vacuum of 10 to 300 (mmHg). Where: V: amount of molten steel
(t), F: annular flow rate (t / min), a: constant (range: 1 to 10) determined by cleanliness required for the product. In this method, the large agitation force of the vacuum degassing method or the large rocking force of the DH vacuum degassing process is applied to the collisional aggregation (coalescence) of inclusions.
Utilized, the intention is to increase the cleanliness by increasing the floating efficiency up to inclusions minimum, it is obtained by regulating the time t 1 as the time required for the combined flying.
【0004】[0004]
【発明が解決しようとする課題】しかながら、例えば自
動車外板用高張力鋼や珪素鋼においては、前記従来法で
二次精錬を行って連続鋳造プロセスによって凝固させて
スラグ等の鋳片とする際に連続鋳のタンディッシュとモ
ールド間の浸漬ノズルを通過するときに溶鋼中の介在物
がノズル内に堆積してノズル詰まりを誘起する等の問題
があり、また、圧延以降の製品にしばしば表面欠陥が発
生することから鋳片の清浄度も未だ十分なものではなか
った。However, for example, in the case of high-strength steel or silicon steel for automobile outer panels, secondary refining is performed by the conventional method and solidified by a continuous casting process to obtain slag or other slabs. When passing through the immersion nozzle between the continuous casting tundish and the mold, there are problems such as inclusions in the molten steel accumulating in the nozzle and inducing nozzle clogging. Because of the occurrence of defects, the cleanliness of the slab was still not sufficient.
【0005】本発明は、上記従来技術の問題を解決し、
連鋳でのノズル詰まりを誘起せずに鋳片の清浄度を十分
に高め得る溶鋼の二次精錬方法を提供することを目的と
する。The present invention solves the above-mentioned problems of the prior art,
An object of the present invention is to provide a method for secondary refining of molten steel capable of sufficiently increasing the cleanliness of a slab without inducing nozzle clogging in continuous casting.
【0006】[0006]
【課題を解決するための手段】本発明は、真空脱ガス装
置により溶鋼の脱炭、脱酸、および溶鋼への合金元素の
添加を行う溶鋼の二次精錬方法において、前記合金元素
の添加を脱炭処理中に行い、その後脱酸処理を行うこと
を特徴とする溶鋼の二次精錬方法である。前記合金元素
添加用の合金剤は、脱酸能を有しないものであることが
好ましい。SUMMARY OF THE INVENTION The present invention relates to a method for secondary refining of molten steel, which comprises decarburizing, deoxidizing, and adding alloying elements to molten steel by a vacuum degassing apparatus. This is a secondary refining method for molten steel, which is performed during a decarburization process and then performed a deoxidation process. The alloying agent for adding an alloying element preferably has no deoxidizing ability.
【0007】[0007]
【発明の実施の形態】従来、真空脱ガス装置を用いた二
次精錬においては、溶鋼中への合金元素の添加は、Al、
Ti等の脱酸剤を溶鋼に添加した後に行われるのが常であ
った。ところが、本発明らが、この合金元素の添加時か
ら鋳造までの間の溶鋼中の介在物の挙動を詳細に追跡し
たところ、合金元素の添加直後あるいは添加から鋳造の
間に介在物が増加する傾向があることをつきとめた。そ
の原因を調査したところ、合金元素添加用の合金剤に含
有される水分、酸素、酸化物、あるいは合金剤に付着し
た水分や酸化物が溶鋼への合金剤の添加に伴って溶鋼中
に入り、溶鋼中のAl、Tiといった脱酸剤を酸化してAl2O
3 やTiO2等の介在物を増加させていることが明らかとな
った。DESCRIPTION OF THE PREFERRED EMBODIMENTS Conventionally, in secondary refining using a vacuum degassing apparatus, the addition of alloying elements into molten steel includes Al,
It is usually performed after adding a deoxidizing agent such as Ti to molten steel. However, the present inventors have closely tracked the behavior of inclusions in molten steel from the time of addition of the alloying element to the time of casting, and the number of inclusions increases immediately after the addition of the alloying element or during the casting from the addition of the alloying element. I found that there was a tendency. After investigating the cause, moisture, oxygen, and oxides contained in the alloying agent for adding alloying elements, or moisture and oxides adhering to the alloying agent entered the molten steel with the addition of the alloying agent to the molten steel. Oxidizes deoxidizers such as Al and Ti in molten steel to form Al 2 O
It became clear that inclusions such as 3 and TiO 2 were increased.
【0008】そこで、本発明では、これら酸素源を有す
る合金剤の添加を、脱酸処理の後ではなく、真空脱ガス
装置における溶鋼の脱炭精錬時に行うことにしたのであ
る。前記溶鋼の脱炭精錬は、転炉等の一次精錬炉におい
てリムド出鋼(未脱酸又は、わずかの脱酸剤のみの添加
にとどめ、溶鋼中の酸素を残す出鋼方法)した溶鋼を真
空脱ガス装置において減圧し、溶存C、Oの反応によっ
て脱炭するか、あるいは、前記減圧下でランスや羽口か
ら溶鋼に酸素ガスを供給することによって行われる。Therefore, in the present invention, the addition of the alloying agent having an oxygen source is performed not after the deoxidizing treatment but at the time of decarburizing and refining molten steel in a vacuum degassing apparatus. The decarburization and refining of the molten steel is carried out in a primary smelting furnace such as a converter by removing rimmed steel (non-deoxidized or only a small amount of a deoxidizing agent and leaving oxygen in the molten steel). The degassing is performed by reducing the pressure in the degassing device and decarburizing by the reaction of dissolved C 2 and O , or by supplying oxygen gas to the molten steel from a lance or tuyere under the reduced pressure.
【0009】本発明によれば、脱炭処理中に合金元素を
添加し、脱酸処理後、攪拌処理するようにしたから、脱
酸後に合金元素添加する従来法で生じていた前記問題、
すなわち、添加される合金元素に伴う酸素源によって溶
鋼中の脱酸剤が酸化されてAl 2O3 やTiO2等の介在物が増
加するという問題は解消する。本発明において添加した
合金剤に含まれる酸素、水分、酸化物に起因する酸素
は、溶鋼中に入った後は、主として溶鋼の脱炭精錬に消
費されることとなり、介在物を形成することはない。仮
に一時的に非金属介在物が形成されたとしても、真空処
理による攪拌力と溶鋼のC−Oボイルによる攪拌によっ
て、直ちに溶鋼中のCと反応して還元されるか、凝集浮
上し速やかにスラグ中に移行するので、最後まで(すな
わち連続鋳造段階まで)非金属介在物として残存するこ
とはない。According to the present invention, the alloying element is removed during the decarburization process.
After the addition and deoxidation, the mixture was agitated.
The above-mentioned problem that has occurred in the conventional method of adding an alloy element after the acid,
In other words, melting by the oxygen source accompanying the added alloy element
Deoxidizer in steel is oxidized to Al TwoOThreeAnd TiOTwoInclusions increase
The problem of adding is resolved. Added in the present invention
Oxygen due to oxygen, moisture and oxides contained in alloying agents
After entering the molten steel, it is mainly used for decarburization and refining of the molten steel.
Will be spent and will not form inclusions. Provisional
Even if non-metallic inclusions are temporarily formed in
The stirring power of the steel and the stirring of the molten steel by the CO boil
Immediately reacts with C in molten steel and is reduced or coagulated
As it moves up during the slag immediately,
That is, it remains as a nonmetallic inclusion until the continuous casting stage).
And not.
【0010】本発明で、脱炭精錬時に添加する合金剤
は、脱酸能を有しないものであることが好ましい。すな
わち、AlやTiなどの強脱酸能を有する元素の場合、添加
と同時に溶鋼中の溶存酸素と結合して還元し難いAl2O3
やTiO2などの非金属介在物が大量に発生する。これによ
って、溶鋼中の溶存酸素量が一挙に減少してしまい、脱
炭反応が停止し、極低炭素鋼を得ることが困難になるう
え、生成した多量の非金属介在物の一部は連続鋳造段階
まで残存するため鋳片の品質を損なったり、浸漬ノズル
を閉塞するので好ましくない。また、SiやMnなどの弱脱
酸元素の場合、溶鋼中の溶存酸素と結合してSiO2やMnO
などの低級酸化物が生成するが、これらはスラグ中に移
行し、のちに強脱酸元素であるAlやTiを添加したのち
に、溶鋼中に緩慢に酸素を供給する働きをし、二次精錬
から連続鋳造に至る途中で溶鋼中のAlやTiを酸化し、非
金属介在物を増大させる源となるので好ましくない。In the present invention, the alloying agent added during the decarburization refining preferably has no deoxidizing ability. That is, in the case of an element having a strong deoxidizing ability, such as Al and Ti, Al 2 O 3 which is hard to be reduced by being combined with dissolved oxygen in molten steel at the same time of addition.
Non-metallic inclusions, such as TiO 2 and a large amount generated. As a result, the amount of dissolved oxygen in the molten steel is reduced at once, and the decarburization reaction is stopped, making it difficult to obtain an ultra-low carbon steel. Since it remains until the casting stage, the quality of the slab is impaired and the immersion nozzle is closed, which is not preferable. Also, in the case of a weak deoxidizing element such as Si and Mn, SiO 2 and MnO in combination with dissolved oxygen in the molten steel
Lower oxides, etc., which migrate into the slag, and after the addition of Al and Ti, which are strong deoxidizing elements, work slowly to supply oxygen into the molten steel, Al and Ti in the molten steel are oxidized during the process from refining to continuous casting, which is a source of increasing nonmetallic inclusions, which is not preferable.
【0011】脱炭能を有しない合金剤の具体的な例とし
ては、P 、Ni、Co、Cu、Ag、Mo、Wなどが挙げられる。
これらの元素は単体あるいは鉄との合金の形態で添加し
てもよい。Specific examples of the alloying agent having no decarburizing ability include P, Ni, Co, Cu, Ag, Mo, W and the like.
These elements may be added alone or in the form of an alloy with iron.
【0012】[0012]
【実施例】C:19ppm 、Si:0.01%、Mn:0.33%、P:
0.095 %、S:0.007 %、Al:0.034 %を含有する高P
極低炭素鋼の溶製にあたり、転炉にて一次精錬し取鍋に
出鋼した溶鋼をRH真空脱ガス装置により二次精錬する
ときのプロセスとして、従来の「脱炭→脱酸→合金剤
(Fe−P)添加→攪拌」プロセスに代えて本発明の「脱
炭(処理中に合金剤(Fe−P)添加)→脱酸→攪拌」プ
ロセスを採用したところ、図1に示すように、代表トー
タル酸素(定義:連続鋳造において当該チャージを40〜
60%鋳造時のタンディッシュ内溶鋼から採取されたサン
プルに含有される全酸素濃度) が従来よりも大幅に低減
し、二次精錬後の連々鋳工程では、図2に示すようにイ
マージョンノズル当たりの連々数が従来の4チャージか
ら7チャージにまで増大して、生産性が格段に向上し、
さらに、当該連鋳鋳片を熱延−冷延−焼鈍−表面処理し
て得た製品コイルの表面欠陥(不良率指数)は、図3に
示すように、従来に対し約4割も低減するという顕著な
効果が得られた。[Example] C: 19 ppm, Si: 0.01%, Mn: 0.33%, P:
High P containing 0.095%, S: 0.007%, Al: 0.034%
In the process of smelting ultra-low carbon steel, the process of primary smelting in a converter and the secondary smelting of molten steel discharged into a ladle using an RH vacuum degasser is performed using the conventional "decarburization → deoxidation → alloying agent". When the "decarburization (addition of alloying agent (Fe-P) during processing) → deoxidation → stirring" process of the present invention was adopted instead of the (Fe-P) addition → stirring "process, as shown in FIG. , Representative total oxygen (definition: 40-
The total oxygen concentration contained in the sample collected from the molten steel in the tundish at the time of 60% casting) was significantly reduced compared to the conventional method, and in the continuous casting process after the secondary refining, as shown in FIG. Increases from 4 charges to 7 charges in the past, and the productivity is dramatically improved.
Further, as shown in FIG. 3, the surface defects (defective rate index) of the product coil obtained by subjecting the continuous cast slab to hot rolling-cold rolling-annealing-surface treatment are reduced by about 40% as compared with the related art. The remarkable effect was obtained.
【0013】[0013]
【発明の効果】かくして本発明によれば、連鋳でのイマ
ージョンノズル詰まりがなくなり連々鋳の生産性が向上
するとともに、鋳片の清浄度が高くなって熱延−冷延−
焼鈍−表面処理−プレス後の表面欠陥が低減するという
優れた効果を奏する。As described above, according to the present invention, clogging of the immersion nozzle in continuous casting is eliminated and the productivity of continuous casting is improved.
An excellent effect of reducing surface defects after annealing-surface treatment-pressing is achieved.
【図1】本発明と従来の代表トータル酸素を示すグラフ
である。FIG. 1 is a graph showing representative total oxygen of the present invention and a conventional one.
【図2】本発明と従来の連々鋳での生産性を示すグラフ
である。FIG. 2 is a graph showing productivity of the present invention and the conventional continuous casting.
【図3】本発明と従来の製品段階での不良率指数を示す
グラフである。FIG. 3 is a graph showing a defect rate index in a product stage according to the present invention and a conventional product.
フロントページの続き (72)発明者 野村 寛 千葉県千葉市中央区川崎町1番地 川崎製 鉄株式会社千葉製鉄所内 Fターム(参考) 4K013 AA00 BA02 BA08 BA14 CA04 CE01 DA02 DA08 DA12 DA13 EA18 EA19 Continued on the front page (72) Inventor Hiroshi Nomura 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba F-term (reference) 4K013 AA00 BA02 BA08 BA14 CA04 CE01 DA02 DA08 DA12 DA13 EA18 EA19
Claims (2)
酸、および溶鋼への合金元素の添加を行う溶鋼の二次精
錬方法において、前記合金元素の添加を脱炭処理中に行
い、その後脱酸処理を行うことを特徴とする溶鋼の二次
精錬方法。In a secondary refining method for molten steel, wherein decarburization, deoxidation, and addition of alloying elements to molten steel by a vacuum degassing apparatus, the alloying elements are added during the decarburization process, A secondary refining method for molten steel, which comprises performing a deoxidation treatment.
を有しないものである請求項1記載の方法。2. The method according to claim 1, wherein the alloying agent for adding an alloying element has no deoxidizing ability.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP25349798A JP4055260B2 (en) | 1998-09-08 | 1998-09-08 | Secondary refining method for molten steel |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP25349798A JP4055260B2 (en) | 1998-09-08 | 1998-09-08 | Secondary refining method for molten steel |
Publications (2)
Publication Number | Publication Date |
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JP2000087128A true JP2000087128A (en) | 2000-03-28 |
JP4055260B2 JP4055260B2 (en) | 2008-03-05 |
Family
ID=17252210
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JP25349798A Expired - Fee Related JP4055260B2 (en) | 1998-09-08 | 1998-09-08 | Secondary refining method for molten steel |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008528802A (en) * | 2005-01-28 | 2008-07-31 | インジェクション アロイズ リミテッド | Wire for refining molten metal and associated manufacturing method |
US7998237B2 (en) * | 2003-06-07 | 2011-08-16 | Sms Siemag Aktiengesellschaft | Method and installation for the production of steel products having an optimum surface quality |
JP2017106105A (en) * | 2015-11-27 | 2017-06-15 | 新日鐵住金株式会社 | Method for producing sulfur-added steel |
CN109715835A (en) * | 2015-11-27 | 2019-05-03 | 新日铁住金株式会社 | The manufacturing method of sulphur addition material and resulphurized steel(s) in molten steel |
JP2020002408A (en) * | 2018-06-26 | 2020-01-09 | 日本製鉄株式会社 | Manufacturing method of steel |
-
1998
- 1998-09-08 JP JP25349798A patent/JP4055260B2/en not_active Expired - Fee Related
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7998237B2 (en) * | 2003-06-07 | 2011-08-16 | Sms Siemag Aktiengesellschaft | Method and installation for the production of steel products having an optimum surface quality |
JP2008528802A (en) * | 2005-01-28 | 2008-07-31 | インジェクション アロイズ リミテッド | Wire for refining molten metal and associated manufacturing method |
US9200349B2 (en) | 2005-01-28 | 2015-12-01 | Injection Alloys Limited | Wire for refining molten metal and associated method of manufacture |
JP2017106105A (en) * | 2015-11-27 | 2017-06-15 | 新日鐵住金株式会社 | Method for producing sulfur-added steel |
CN109715835A (en) * | 2015-11-27 | 2019-05-03 | 新日铁住金株式会社 | The manufacturing method of sulphur addition material and resulphurized steel(s) in molten steel |
KR20190053882A (en) | 2015-11-27 | 2019-05-20 | 닛폰세이테츠 가부시키가이샤 | Preparation method of sulfur additive and sulfur-added steel for molten steel |
US11098384B2 (en) | 2015-11-27 | 2021-08-24 | Nippon Steel Corporation | Sulfur additive for molten steel and method for producing resulfurized steel |
JP2020002408A (en) * | 2018-06-26 | 2020-01-09 | 日本製鉄株式会社 | Manufacturing method of steel |
JP7119642B2 (en) | 2018-06-26 | 2022-08-17 | 日本製鉄株式会社 | steel manufacturing method |
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