JPH083619A - Method for melting stainless steel - Google Patents

Method for melting stainless steel

Info

Publication number
JPH083619A
JPH083619A JP13055894A JP13055894A JPH083619A JP H083619 A JPH083619 A JP H083619A JP 13055894 A JP13055894 A JP 13055894A JP 13055894 A JP13055894 A JP 13055894A JP H083619 A JPH083619 A JP H083619A
Authority
JP
Japan
Prior art keywords
blowing
gas
stainless steel
reduction
oxygen
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
Application number
JP13055894A
Other languages
Japanese (ja)
Other versions
JP4022266B2 (en
Inventor
Masaru Washio
勝 鷲尾
Hiroshi Nishikawa
廣 西川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
Kawasaki Steel Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Kawasaki Steel Corp filed Critical Kawasaki Steel Corp
Priority to JP13055894A priority Critical patent/JP4022266B2/en
Publication of JPH083619A publication Critical patent/JPH083619A/en
Application granted granted Critical
Publication of JP4022266B2 publication Critical patent/JP4022266B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

PURPOSE:To provide a melting technique of stainless steel, by which the oxide loss of chromium can be reduced and the unit consumption of Fe-Si for reduction can be restrained to low. CONSTITUTION:At the end stage of blowing before executing reduction, decarburization is executed by bottom-blowing of oxygen gas or mixed gas of oxygen gas and an inert gas, and for the gas blowing from a top-blowing lance, only inert gas is used. At the same time, slag-making agent alone or in combination with a reduction agent is charged into the molten steel. By this method, the production cost of the stainless steel is reduced.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】この発明は、ステンレス鋼の溶製
方法、とくに上底吹き転炉やAODを使ったステンレス
鋼の溶製に当たり、その吹錬末期におけるクロム酸化ロ
スの低減に有効に作用すると共にフェロアロイの無駄な
消費を避けてコスト低下を図るのに有効な溶製方法に関
するものである。
BACKGROUND OF THE INVENTION This invention relates to a method of melting stainless steel, and particularly to the melting of stainless steel using a top-bottom blowing converter or AOD, and effectively acts to reduce chromium oxidation loss at the final stage of blowing. In addition, the present invention relates to a melting method that is effective in avoiding wasteful consumption of ferroalloy and reducing costs.

【0002】[0002]

【従来の技術】ステンレス鋼の溶製に当たって、コスト
低減を図る上で重要なことは、還元用フェロアロイ(Fe
−Si) の原単位の低減を図ることである。それと同時
に、クロム酸化ロスの低減を図ることもまた重要であ
り、そのために、例えば「鉄鋼便覧II」:第3版;日本
鉄鋼協会編、第719 頁の表13.22 では、ように脱炭レベ
ルに応じて羽口から吹き込まれる酸素を不活性ガス(ア
ルゴンあるいは窒素)にて希釈する方法を提案してい
る。
2. Description of the Related Art In melting stainless steel, it is important to reduce costs by reducing ferroalloy (Fe).
-Si) is to reduce the basic unit. At the same time, it is also important to reduce chromium oxidation loss, and for this reason, for example, in “Steel Manual II”: 3rd edition; Japan Iron and Steel Institute, ed., Table 13.22, p. Accordingly, a method of diluting oxygen blown from the tuyere with an inert gas (argon or nitrogen) is proposed.

【0003】その他、CrをFe−Siで還元する前に、含ク
ロム溶鋼の浴面に上吹きランスを通じて窒素を吹き付
け、CO分圧を低下させることにより、Cr酸化ロスを低減
させる方法(特開平4−329818号公報参照)なども提案
されている。
In addition, before reducing Cr with Fe-Si, nitrogen is blown onto the bath surface of the chromium-containing molten steel through an upper blowing lance to reduce the CO partial pressure, thereby reducing Cr oxidation loss. No. 4-329818) is also proposed.

【0004】[0004]

【発明が解決しようとする課題】しかし、脱炭レベルに
応じてガス希釈を行う上記刊行物(鉄鋼便覧)記載の方
法は、依然としてクロムの酸化ロスが多く、しかも還元
用Fe−Si原単位が相変わらず高いためにコスト低減につ
ながらなかった。
However, the method described in the above publication (Steel Handbook) in which gas is diluted according to the decarburization level still has a large amount of chromium oxidation loss, and moreover, the Fe-Si basic unit for reduction is reduced. Since it is still expensive, it did not lead to cost reduction.

【0005】一方、前記特開平4−329818号公報に開示
された方法では、上吹きを実施する前のスラグ中の酸化
クロムは非常に高融点でかつ滓化性が悪いため、上吹き
を実施しても十分なFe−Si原単位の低下につながらず、
コスト低減に有効とは言えなかった。
On the other hand, in the method disclosed in the above-mentioned Japanese Patent Laid-Open No. 4-329818, the chromium oxide in the slag before the upper blowing has a very high melting point and poor slag forming property, and therefore the upper blowing is performed. Even if it does not lead to a sufficient decrease in Fe-Si unit consumption,
It was not effective in reducing costs.

【0006】本発明の目的は、クロムの酸化ロスが少な
くかつ還元用Fe−Siの原単位を低く抑えてコストダウン
に有効なステンレス鋼の溶製技術を提案することにあ
る。
An object of the present invention is to propose a technique for producing stainless steel which has a low oxidation loss of chromium and a low unit consumption of Fe-Si for reduction, which is effective for cost reduction.

【0007】[0007]

【課題を解決するための手段】本発明は上記目的を実現
する方法として開発した溶製方法であって、その特徴と
するところは、還元を実施する前の吹錬末期において
は、酸素ガスまたはこのガスと不活性ガスとの混合ガス
を底吹きして脱炭すると同時に、上吹きランスからのガ
ス吹精は総て不活性ガスを使用すると同時に、鋼浴中に
はこれにあわせてスラグ滓化剤を単独もしくはこの滓化
剤と共に還元剤を投入することにより、スラグ中の酸化
クロムを低下させてクロムの酸化ロスを防ぎ、かつ還元
用Fe−Si原単位の低下を図るようにした点の構成にあ
る。なお、本発明におけるステンレス鋼の溶製は、転炉
例えば上底吹き転炉やAODなどでの吹錬に適用され
る。また、本発明において、上記吹錬末期とは、脱炭末
期から仕上げ脱炭期にかけての段階を指し、いわゆる吹
き止めC%に達して還元段階に入る前までを言う。
The present invention is a melting method developed as a method for achieving the above object, which is characterized in that in the final stage of blowing before the reduction, oxygen gas or At the same time that the mixed gas of this gas and the inert gas is blown from the bottom to decarburize, at the same time all the gas blowing from the top blowing lance uses the inert gas, and at the same time in the steel bath, the slag slag is adjusted accordingly. By adding the reducing agent alone or together with this reducing agent, the chromium oxide in the slag is reduced to prevent the oxidation loss of chromium, and the reduction of the Fe-Si unit consumption for reduction is aimed at. In the configuration. The melting of stainless steel in the present invention is applied to blowing in a converter such as a top-bottom blowing converter or AOD. Further, in the present invention, the final stage of blowing refers to the stage from the final stage of decarburization to the final decarburization period, which is the period before reaching the so-called blow stop C% and before entering the reduction stage.

【0008】[0008]

【作用】図1は、各吹錬段階における上吹き、底吹きの
酸素の希釈比率の推移を示すものである。この図に明ら
かなように、一般的なステンレス鋼の溶製では、まず、
脱炭初期(C:1%程度まで)においては、底吹きガス
として酸素/不活性ガスを比率を3:1とし、酸素濃度
の比較的高い混合ガスを吹き込む。また、この時期にお
いては、上吹きランスからは、酸素あるいは酸素と不活
性ガスとの混合ガス(1:1)を吹き込んでもよい。
FIG. 1 shows changes in the dilution ratio of top-blown and bottom-blown oxygen in each blowing stage. As is clear from this figure, in general melting of stainless steel, first,
In the initial stage of decarburization (C: up to about 1%), the ratio of oxygen / inert gas is set to 3: 1 as the bottom blowing gas, and a mixed gas having a relatively high oxygen concentration is blown. At this time, oxygen or a mixed gas of oxygen and an inert gas (1: 1) may be blown from the top blowing lance.

【0009】次に、脱炭中期(C:1.0 〜0.6 %) にお
いては、底吹きガスの酸素/不活性ガスの比率を2:1
とし、脱炭初期と比較して酸素の濃度の低い混合ガスを
使用する。また、この時期についても、上吹きランスか
ら、酸素あるいは酸素と不活性ガスとの混合ガス(2:
1)を吹き込んでもよい。
Next, in the middle stage of decarburization (C: 1.0 to 0.6%), the oxygen / inert gas ratio of the bottom blowing gas is 2: 1.
Then, a mixed gas having a lower oxygen concentration than the initial decarburization is used. Also at this time, oxygen or a mixed gas of oxygen and an inert gas (2:
You may blow in 1).

【0010】次に、脱炭末期(C:0.6 〜0.3 %) にお
いては、底吹きガスの酸素/不活性ガスの比率は1:2
として、酸素の濃度のさらに低い混合ガスを吹き込み、
または、上吹きランスからのガスは、酸素と不活性ガス
との混合ガスを使用するかあるいは、送酸を停止する。
Next, in the final stage of decarburization (C: 0.6 to 0.3%), the ratio of oxygen / inert gas in the bottom blowing gas is 1: 2.
As a mixture gas with a lower oxygen concentration,
Alternatively, the gas from the top blowing lance uses a mixed gas of oxygen and an inert gas, or stops the oxygen transfer.

【0011】そして、仕上げ脱炭期(C:0.3 〜0.1
%) については、底吹きガスの酸素/不活性ガスの比率
を1:3としてさらに低濃度の酸素とし、そして吹き止
めCに達したら還元工程へ移行する。この時期では、上
吹きランスからの送酸は完全に停止する。なお、還元工
程では、不活性ガスのみを底吹きガスとして使用し、同
時に還元用Fe−Siを投入することにより酸化したCrを下
記の(1) 式により還元する。 2Cr2O3 +3Si=4Cr+3SiO2 (1)
The final decarburizing period (C: 0.3 to 0.1)
%), The oxygen / inert gas ratio of the bottom blown gas is set to 1: 3 to further lower the concentration of oxygen, and when the blowout stop C is reached, the reduction step is performed. At this time, the acid transfer from the top blowing lance is completely stopped. In the reduction step, only inert gas is used as the bottom-blown gas, and at the same time, reducing Fe—Si is added to reduce the oxidized Cr by the following formula (1). 2Cr 2 O 3 + 3Si = 4Cr + 3SiO 2 (1)

【0012】次に、本発明溶製方法について説明する。
図2は、従来溶製方法を示す図1と同様に、本発明方法
の下での送酸パターンを示すものである。本発明方法と
従来方法との違いは、吹錬末期、即ち脱炭末期から仕上
げ脱炭期において、上吹き酸素を停止するのに引き続い
て、不活性ガスのみを上吹きしながら、同時にこの上吹
きガスと共にスラグ滓化剤もしくは、このスラグ滓化剤
と還元剤との混合物を添加することにある。このことに
よって本発明によれば、スラグ中の酸化クロムを低下さ
せつつ脱炭を行うことができるようになる。
Next, the melting method of the present invention will be described.
FIG. 2 shows an acid transfer pattern under the method of the present invention, similar to FIG. 1 showing a conventional melting method. The difference between the method of the present invention and the conventional method is that at the end of blowing, that is, at the end of decarburization to the final decarburization, the top blowing oxygen is stopped, and then only the inert gas is blown upward while simultaneously It is to add a slag slagging agent or a mixture of the slag slagging agent and a reducing agent together with the blown gas. As a result, according to the present invention, decarburization can be performed while reducing the chromium oxide in the slag.

【0013】図3は、SUS304鋼を吹錬した場合の本発明
と従来法とのクロム酸化ロスと吹止Cとの関係を示す。
この図より明らかなように、吹止Cの低下に伴ってクロ
ム酸化ロスが増大することがわかる。即ち、一般的な既
知の溶製方法や上記特開平4−329818号公報に開示の従
来方法に比べ、本発明方法のクロム酸化ロスは明らかに
少なくなっていることがわかる。
FIG. 3 shows the relationship between chromium oxidation loss and blow stop C in the present invention and the conventional method when SUS304 steel is blown.
As is clear from this figure, the chromium oxidation loss increases as the blowout stop C decreases. That is, it can be seen that the chromium oxidation loss of the method of the present invention is obviously smaller than that of the generally known melting method and the conventional method disclosed in Japanese Patent Laid-Open No. 4-329818.

【0014】本発明方法の適用によってクロム酸化ロス
が減少する理由は、 精錬末期に不活性ガスを上吹きすることにより、COガ
スの分圧を低下させることで脱炭が促進されること、 上吹き不活性ガスとスラグ滓化剤(あるいはスラグ滓
化剤と還元剤の混合物)を添加することにより、スラグ
の融点を低下させると同時にそのスラグを溶鋼内に巻き
込ませることにより、下記(2) 式に示されるような溶鋼
のCとの反応を促進すること、 2Cr2O3 +6C=4Cr+6CO (2) にあるものと考えられる。
The reason why the chromium oxidation loss is reduced by applying the method of the present invention is that decarburization is promoted by lowering the partial pressure of CO gas by blowing up an inert gas at the final stage of refining. By adding a blowing inert gas and a slag slagging agent (or a mixture of a slag slagging agent and a reducing agent), the melting point of the slag is lowered and at the same time the slag is caught in the molten steel. It is considered that the reaction of molten steel with C as shown in the formula is promoted, that is, 2Cr 2 O 3 + 6C = 4Cr + 6CO (2).

【0015】なお、上記のスラグ滓化剤としては、ホタ
ル石やマグネシア,氷晶石などのスラグの融点を低下さ
せるものが用いられる。また、還元剤としては、コーク
スやカーボンなどを用いることができるが、この還元剤
は、上吹き酸素量を低下させたときにクロム酸化ロスが
大きくなるようなときに、積極的に添加することによっ
て還元の促進を図るときに有効である。なお、かかるス
ラグ滓化剤および上記還元剤の使用量は、クロム酸化ロ
スに応じて適宜に決定することが望ましい。また、添加
の方法は、上吹きガスとともに吹き込むかシュートを介
して投入してもよい。
As the above-mentioned slag slagging agent, those which lower the melting point of slag such as fluorspar, magnesia, and cryolite are used. Further, as the reducing agent, coke, carbon, etc. can be used, but this reducing agent should be positively added when chromium oxidation loss becomes large when the amount of top-blown oxygen is reduced. This is effective when promoting reduction by. The amounts of the slag slagging agent and the reducing agent used are preferably determined appropriately according to the chromium oxidation loss. In addition, as a method of addition, the gas may be blown together with the top blowing gas or may be put in through a chute.

【0016】図4は、実操業のときにおける従来法と本
発明法の還元用Fe−Si原単位の比較を示す。この図に明
らかなように、本発明方法の方が、クロム酸化ロスと同
様に還元用Fe−Si原単位が平均値で(14.8→12.5kg/t)
に低下していることがわかる。
FIG. 4 shows a comparison of the Fe—Si basic unit for reduction between the conventional method and the method of the present invention during actual operation. As is clear from this figure, in the method of the present invention, the reducing Fe-Si basic unit is an average value (14.8 → 12.5 kg / t) like chromium oxidation loss.
It can be seen that it has fallen to.

【0017】[0017]

【実施例】この実施例は、使用鋼種としてSUS304鋼を用
い、これを上底吹転炉を使って吹錬したときのクロム酸
化ロスとFe−Si原単位について試験したものである。そ
の結果を表1に示す。なお、各ヒートサイズは100 〜12
0t/ch とし、本発明方法の適合例No.1, No.2、従来方法
No.3, No.4につき、それぞれの装入C%は4.1 wt%、
4.2 wt%、4.0 wt%、3.9 wt%のものを用いた。吹錬パ
ターンを脱炭初期(C≦1.0 wt%) 、中期(C:1.0 〜
0.6 wt%) 、末期(C≦0.3 wt%) および仕上げ脱炭期
に分けて、上底吹きガスのO2 ならびにN2 ガスの流量
を制御した。
EXAMPLE In this example, SUS304 steel was used as the type of steel to be used, and the chrome oxidation loss and Fe-Si unit consumption were tested when this was blown using an upper-bottom blowing converter. Table 1 shows the results. Each heat size is 100-12
0t / ch, conforming example of the method of the present invention No.1, No.2, conventional method
For No.3 and No.4, the charging C% is 4.1 wt%,
4.2 wt%, 4.0 wt% and 3.9 wt% were used. The blowing pattern can be decarburized in the initial stage (C ≤ 1.0 wt%) and the middle stage (C: 1.0 ~
0.6 wt%), the final stage (C ≦ 0.3 wt%), and the final decarburization period, and the flow rates of O 2 and N 2 gas of the top and bottom blown gas were controlled.

【0018】また、本発明方法については、仕上げ脱炭
期にスラグ滓化剤としてホタル石をそして還元剤として
はコークスをそれぞれ所定量を上吹きランスを通じて吹
き込み添加した。以上の試験結果によれば、No. 1,2
の本発明例の場合、比較例に比べると、クロム酸化ロス
が少ないと共にFe−Si原単位も小さく、本発明方法の優
位が実証された。
Further, in the method of the present invention, a predetermined amount of fluorite as a slag slagging agent and coke as a reducing agent were added by bubbling through a top blowing lance in the final decarburizing period. According to the above test results, No. 1, 2
In the case of the present invention example, compared with the comparative example, the chromium oxidation loss is small and the Fe-Si unit is also small, demonstrating the superiority of the method of the present invention.

【0019】[0019]

【表1】 [Table 1]

【0020】[0020]

【発明の効果】以上説明したように本発明法によれば、
ステンレス鋼溶製時のクロム酸化ロスが少なくかつFe−
Si原単位の低下を確実に実現でき、ステンレス鋼製造コ
ストを低下させることが可能である。
As described above, according to the method of the present invention,
There is little loss of chromium oxidation when manufacturing stainless steel and Fe-
It is possible to surely reduce the silicon consumption rate and reduce the stainless steel manufacturing cost.

【図面の簡単な説明】[Brief description of drawings]

【図1】一般的なステンレス鋼溶製方法の吹錬パターン
を示す図である。
FIG. 1 is a view showing a blowing pattern of a general stainless steel melting method.

【図2】本発明の方法に基づくステンレス鋼の吹錬パタ
ーンを示す図である。
FIG. 2 is a diagram showing a blowing pattern of stainless steel based on the method of the present invention.

【図3】本発明方法と従来方法とのクロム酸化ロスと吹
止Cとの関係を示す図である。
FIG. 3 is a diagram showing the relationship between chromium oxidation loss and blow-off C between the method of the present invention and the conventional method.

【図4】従来方法と本発明方法の還元用Fe−Si原単位の
比較グラフである。
FIG. 4 is a comparison graph of Fe—Si unit consumption for reduction in the conventional method and the method of the present invention.

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 ステンレス鋼溶製時における還元前の吹
錬末期に、上吹き酸素含有ガスの吹精を停止した後も引
き続き不活性ガスのみを上吹きすると同時に、これにあ
わせて鋼浴中には、スラグ滓化剤を単独もしくは酸化ク
ロム還元剤とともに添加することを特徴とするステンレ
ス鋼の溶製方法。
1. At the end of blowing before the reduction during melting of stainless steel, only the inert gas is continuously blown up even after the blowing of the top-blown oxygen-containing gas is stopped, and at the same time, in the steel bath. In the method for melting stainless steel, a slag slag forming agent is added alone or together with a chromium oxide reducing agent.
JP13055894A 1994-06-13 1994-06-13 Stainless steel melting method Expired - Fee Related JP4022266B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP13055894A JP4022266B2 (en) 1994-06-13 1994-06-13 Stainless steel melting method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP13055894A JP4022266B2 (en) 1994-06-13 1994-06-13 Stainless steel melting method

Publications (2)

Publication Number Publication Date
JPH083619A true JPH083619A (en) 1996-01-09
JP4022266B2 JP4022266B2 (en) 2007-12-12

Family

ID=15037141

Family Applications (1)

Application Number Title Priority Date Filing Date
JP13055894A Expired - Fee Related JP4022266B2 (en) 1994-06-13 1994-06-13 Stainless steel melting method

Country Status (1)

Country Link
JP (1) JP4022266B2 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5325681A (en) * 1976-08-24 1978-03-09 Sun A Chemical Ind One way gas permeable laminated sheet
KR100947434B1 (en) * 2007-12-20 2010-03-12 주식회사 포스코 Method for manufacturing stainless steel
KR101400652B1 (en) * 2012-09-10 2014-05-27 주식회사 포스코 High speed decarburization method for austenite stainless steel
KR101400550B1 (en) * 2012-09-10 2014-05-28 주식회사 포스코 High speed decarburization method for high carbon stainless steel
KR101400498B1 (en) * 2012-09-10 2014-05-28 주식회사 포스코 High speed decarburization method for high purity stainless steel
KR101408228B1 (en) * 2012-12-28 2014-06-16 주식회사 포스코 Method for decarburizing stainless steel

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5325681A (en) * 1976-08-24 1978-03-09 Sun A Chemical Ind One way gas permeable laminated sheet
JPS5618382B2 (en) * 1976-08-24 1981-04-28
KR100947434B1 (en) * 2007-12-20 2010-03-12 주식회사 포스코 Method for manufacturing stainless steel
KR101400652B1 (en) * 2012-09-10 2014-05-27 주식회사 포스코 High speed decarburization method for austenite stainless steel
KR101400550B1 (en) * 2012-09-10 2014-05-28 주식회사 포스코 High speed decarburization method for high carbon stainless steel
KR101400498B1 (en) * 2012-09-10 2014-05-28 주식회사 포스코 High speed decarburization method for high purity stainless steel
KR101408228B1 (en) * 2012-12-28 2014-06-16 주식회사 포스코 Method for decarburizing stainless steel

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