JP2690350B2 - Highly clean ultra low carbon steel melting method - Google Patents
Highly clean ultra low carbon steel melting methodInfo
- Publication number
- JP2690350B2 JP2690350B2 JP1069245A JP6924589A JP2690350B2 JP 2690350 B2 JP2690350 B2 JP 2690350B2 JP 1069245 A JP1069245 A JP 1069245A JP 6924589 A JP6924589 A JP 6924589A JP 2690350 B2 JP2690350 B2 JP 2690350B2
- Authority
- JP
- Japan
- Prior art keywords
- slag
- low carbon
- carbon steel
- ultra
- concentration
- 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 - Fee Related
Links
- 229910001209 Low-carbon steel Inorganic materials 0.000 title claims description 21
- 238000002844 melting Methods 0.000 title claims description 14
- 230000008018 melting Effects 0.000 title claims description 14
- 238000000034 method Methods 0.000 title claims description 11
- 239000002893 slag Substances 0.000 claims description 41
- 229910000831 Steel Inorganic materials 0.000 claims description 21
- 239000010959 steel Substances 0.000 claims description 21
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 17
- 238000009849 vacuum degassing Methods 0.000 claims description 17
- 238000010079 rubber tapping Methods 0.000 claims description 6
- 230000003749 cleanliness Effects 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000003638 chemical reducing agent Substances 0.000 claims description 3
- 238000005261 decarburization Methods 0.000 description 14
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Description
【発明の詳細な説明】 ＜産業上の利用分野＞ 本発明は、真空脱ガス処理によって溶製される極低炭
素鋼の溶製方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing ultra-low carbon steel produced by vacuum degassing.
＜従来の技術＞ 極低炭素鋼は、通常出鋼時に溶鋼を完全には脱酸せ
ず、真空脱ガス処理時に固溶ＯとＣとのCO反応によって
脱炭が行われる。脱炭後、Alを添加して溶鋼を完全に脱
酸するために、真空脱ガス処理時に生成するAl2O3量が
多く、また取鍋スラグ中の（T.Fe）も低下せず、キルド
処理以降に鋼中のAlとスラグとの反応で生成するAl2O3
量も多くなり、低炭Alキルド鋼に比べて、鋼中介在物が
多い。<Prior Art> Ultra-low carbon steel does not completely deoxidize molten steel at the time of tapping, but is decarburized by a CO reaction between solute O and C during vacuum degassing. After decarburization, Al is added to completely deoxidize molten steel, so the amount of Al 2 O 3 produced during vacuum degassing is large, and (T.Fe) in the ladle slag does not decrease, Al 2 O 3 formed by the reaction between Al in steel and slag after the killing treatment
The amount is also large, and there are more inclusions in the steel than the low carbon Al killed steel.
鋼中のAlとスラグとの反応を抑えるために、特開昭59
−70710号公報には取鍋スラグ上にスラグ改質材を添加
し、スラグの酸化度を低下させる技術が開示されてい
る。しかし、この方法を極低炭素鋼に適用すると真空脱
ガス装置での脱炭反応速度が低下し、所要のＣレベルに
まで脱炭するのに要する時間が長くなるという問題があ
り、また、その理由が解明されず極低炭素鋼には使用さ
れていなかったのが実状であった。In order to suppress the reaction between Al in steel and slag, JP-A-59
Japanese Patent No. 70710 discloses a technique of adding a slag modifier on a ladle slag to reduce the degree of oxidation of the slag. However, when this method is applied to ultra-low carbon steel, there is a problem that the decarburization reaction rate in the vacuum degassing apparatus decreases, and the time required for decarburization to the required C level becomes long. The reason is that it was not used for ultra-low carbon steel for unknown reasons.
＜発明が解決しようとする課題＞ 本発明は、前述のような従来技術の問題に鑑み、極低
炭素鋼の真空脱ガス処理・溶製時において、脱炭速度を
低下させることなく鋼中介在物を低減することのできる
溶製方法に関するものである。<Problems to be Solved by the Invention> In view of the problems of the prior art as described above, the present invention intervenes in steel during vacuum degassing / melting of ultra-low carbon steel without reducing the decarburization rate. The present invention relates to a melting method capable of reducing the amount of materials.
＜課題を解決するための手段＞ 本発明は、真空脱ガス処理で脱炭処理を施す極低炭
素鋼の溶製にあたり、真空脱ガス処理前の取鍋スラグ中
のT.Fe濃度を0.5重量％以上、6.0重量％以下とし、かつ
SiO2濃度を15.0重量％以下とすることを特徴とする高清
浄度極低炭素鋼の溶製方法であり、また真空脱ガス処
理で脱炭処理を施す極低炭素鋼の溶製にあたり、出鋼時
に取鍋に流出した取鍋スラグを除去し、T.Fe濃度が0.5
重量％以上、6.0重量％以下で、かつSiO2濃度が15.0重
量％以下の合成スラグを溶鋼の上に添加した後、真空脱
ガス処理することを特徴とする高清浄度極低炭素鋼の溶
製方法であり、また真空脱ガス処理で脱炭処理を施す
極低炭素鋼の溶製にあたり、出鋼時に取鍋に流出した取
鍋スラグ上にAlあるいはAl滓のような還元剤を添加して
該スラグ中のT.Fe濃度を0.5重量％以上、6.0重量％以下
とし、かつSiO2濃度を15.0重量％以下とした後、真空脱
ガス処理することを特徴とする高清浄度極低炭素鋼の溶
製方法である。<Means for Solving the Problems> The present invention, when melting ultra-low carbon steel to be subjected to decarburization treatment by vacuum degassing treatment, has a T.Fe concentration of 0.5 wt% in ladle slag before vacuum degassing treatment. % Or more and 6.0% by weight or less, and
It is a method for melting ultra-clean ultra-low carbon steel, which is characterized by setting the SiO 2 concentration to 15.0% by weight or less.Also, when melting ultra-low-carbon steel that is decarburized by vacuum degassing, The ladle slag that had flowed out to the ladle during steel was removed, and the T.Fe concentration was 0.5.
A high-cleanliness ultra-low carbon steel melt characterized by performing vacuum degassing after adding synthetic slag with a weight percentage of 6.0 wt% or more and a SiO 2 concentration of 15.0 wt% or less onto molten steel. It is a manufacturing method, and when melting ultra-low carbon steel that is decarburized by vacuum degassing, adding a reducing agent such as Al or Al slag to the ladle slag that flowed out to the ladle at the time of tapping. After the T.Fe concentration in the slag is 0.5 wt% or more and 6.0 wt% or less and the SiO 2 concentration is 15.0 wt% or less, vacuum degassing treatment is performed, which is characterized by high cleanliness and extremely low carbon content. It is a method of melting steel.
＜発明をなすに至った経過および作用＞ 鋼の清浄度を表す指標の一つとして鋼中全酸素濃度
〔Ｏ〕Ｔがある。極低炭素鋼冷延コイルの介在物性欠陥
数と〔Ｏ〕Ｔとの間には第１図に示すような関係があ
り、〔Ｏ〕Ｔ＜30ppmで介在物性欠陥指数が問題になら
ないレベルにまで低下する。そこで、〔Ｏ〕Ｔ＜30ppm
を得るための条件を調査した結果、次のことが判明し
た。<Processes and Actions Leading to Invention> One of the indexes showing the cleanliness of steel is the total oxygen concentration [O] T in steel. There is a relationship as shown in Fig. 1 between the number of inclusion defects in the ultra low carbon steel cold-rolled coil and [O] T. At [O] T <30 ppm, the inclusion defect index is at a level that does not matter. Falls to. Therefore, [O] T <30ppm
As a result of investigating the conditions for obtaining, the following was found.
〔Ｏ〕Ｔに及ぼすスラグ組成、特に（T.Fe），（Si
O2）の影響を第２図，第３図に示したが、この図から、
スラグ中の（T.Fe）を６重量％（以下％と略す）以下に
し、かつ（SiO2）を15％以下とすることにより〔Ｏ〕Ｔ
を30ppm以下とできることが明らかである。スラグ中の
（FeO）や（SiO2）が鋼中Alと次に示すような反応をし
てAl2O3を生成するため（T.Fe）や（SiO2）濃度が高い
と〔Ｏ〕Ｔが増加すると考えられる。[O] Slag composition affecting T , especially (T.Fe), (Si
The effect of O 2 ) is shown in Fig. 2 and Fig. 3.
By making (T.Fe) in the slag 6 wt% (hereinafter abbreviated as%) or less and (SiO 2 ) 15% or less, [O] T
It is clear that can be 30ppm or less. Since (FeO) and (SiO 2 ) in slag react with Al in steel to produce Al 2 O 3 as follows, if the (T.Fe) and (SiO 2 ) concentration is high, [O] It is considered that T increases.
2Al＋3FeO＝Al2O3＋3Fe 2Al＋3/2SiO2＝Al2O3＋3/2 Si しかしながら、極低炭素鋼の場合、RH装置において真
空脱炭処理を施すが、第４図に示すように（T.Fe）が0.
5％以下まで下がると脱炭不良率指数が上り、真空脱炭
中の脱炭速度が低下し、操業時間内にＣ濃度が目標値ま
で下がらなくなる。これは、脱炭反応に要するＯのうち
ある割合はスラグから供給されていたが、（T.Fe）が低
い場合には、この量が不足するために脱炭速度が低下す
ると考えられる。この新発見が本発明をなすに至った理
由である。 2Al + 3FeO = Al 2 O 3 + 3Fe 2Al + 3 / 2SiO 2 = Al 2 O 3 +3/2 Si , however, in the case of ultra low carbon steel, subjected to vacuum decarburization in RH apparatus, as shown in FIG. 4 (T. Fe) is 0.
If it falls below 5%, the decarburization defect rate index rises, the decarburization rate during vacuum decarburization decreases, and the C concentration does not fall to the target value within the operating time. It is considered that a certain ratio of O required for the decarburization reaction was supplied from the slag, but when (T.Fe) was low, the decarburization rate was decreased due to lack of this amount. This new discovery is the reason why the present invention was made.
したがって、スラグ中の（T.Fe）を0.5％以上、６％
以下とし、かつ（SiO2）を15％以下とすることによっ
て、〔Ｏ〕Ｔは30ppm以下となり、介在物性欠陥指数が
問題にならないレベルまで低下し、かつ脱炭速度が低下
することはない。Therefore, (T.Fe) in slag is 0.5% or more, 6%
By setting the content to the following and (SiO 2 ) to 15% or less, [O] T becomes 30 ppm or less, the inclusion property defect index decreases to a level at which no problem occurs, and the decarburization rate does not decrease.
極低炭素鋼は、脱酸せずに出鋼し、RH装置で真空脱炭
するので、スラグ中の（T.Fe），（SiO2）を下げる場合
に、鋼中酸素を脱酸しない方法を採用する必要がある。
例えば、出鋼時に取鍋へ流出した取鍋スラグを除去し、
酸素ポテンシャルの低い合成した溶製用スラグを添加す
る方法、取鍋スラグ上へ金属AlあるいはAl滓のような還
元剤を添加してスラグのみ還元する方法等を採用するこ
とができる。スラグ還元によって（T.Fe）を低下させる
場合には、（T.Fe）を0.5％以下にしないでSiO2を十分
還元することはむずかしいので、吹錬中の塩基度調整等
により取鍋へ流出するスラグ中のSiO2を低くしておく必
要がある。Ultra-low carbon steel is tapped without deoxidation and vacuum decarburized with an RH device, so when lowering (T.Fe) and (SiO 2 ) in slag, a method that does not deoxidize oxygen in steel Need to be adopted.
For example, remove the ladle slag that has flowed to the ladle when tapping,
A method of adding a synthetic slag for melting, which has a low oxygen potential, a method of adding only a reducing agent such as metal Al or Al slag onto the ladle slag and reducing only the slag can be adopted. When reducing (T.Fe) by slag reduction, it is difficult to reduce SiO 2 sufficiently without lowering (T.Fe) to 0.5% or less, so adjust the basicity during blowing to place it in the ladle. It is necessary to keep the SiO 2 in the slag flowing out low.
＜実施例＞ 実施例と比較例とを以下に説明する。<Examples> Examples and comparative examples will be described below.
実施例１では、出鋼時に取鍋へ流出した取鍋スラグを
除去した後、溶鋼280tに対し合成スラグ（CaO:60％,SiO
2:8％,Al2O3:31.4％,T.Fe:0.6％）3,000kgを添加した例
である。In Example 1, after removing the ladle slag that had flown into the ladle at the time of tapping, the synthetic slag (CaO: 60%, SiO
2 : 8%, Al 2 O 3 : 31.4%, T.Fe: 0.6%) 3,000 kg.
実施例２では溶鋼280t上の取鍋スラグ1,000kgに対
し、Al滓（Al:50％）300kgを添加し、実施例３では溶鋼
280t上の取鍋スラグ1,000kgに対し、Al滓（Al:50％）50
0kgを添加した。In Example 2, 300 kg of Al slag (Al: 50%) was added to 1,000 kg of ladle slag on 280 tons of molten steel, and in Example 3, molten steel was added.
Al slag (Al: 50%) 50 for 1,000kg of ladle slag on 280t
0 kg was added.
これに対し、比較例1,2,3では溶鋼280t上の取鍋スラ
グ1,000kgに対してAl滓（Al:50％）を夫々600kg,150kg,
380kg添加した。スラグの成分特に（Ｔ・Fe），（Si
O2）はRH処理前に、溶鋼中〔Ｏ〕T,〔Ｃ〕ｆはRH処理後
に確認した。On the other hand, in Comparative Examples 1, 2, and 3, 600 kg, 150 kg of Al slag (Al: 50%) was added to 1,000 kg of ladle slag on molten steel 280 t, respectively.
380 kg was added. Slag components, especially (T ・ Fe), (Si
O 2 ) was confirmed before RH treatment, and [O] T and [C] f in molten steel were confirmed after RH treatment.
以上の結果を第１表に，纏めて示した。 The above results are summarized in Table 1.
第１表の実施例に示すように、スラグ中（T.Fe）が0.
5％以上６％以下、かつ（SiO2）が15％以下の場合に
は、〔Ｏ〕Ｔが30ppm以下となり、また〔Ｃ〕が処理時
間内に目標値以下まで下がっている。As shown in the examples of Table 1, the content of slag (T.Fe) is 0.
When the content of (SiO 2 ) is 5% or more and 6% or less and the content of (SiO 2 ) is 15% or less, [O] T is 30 ppm or less, and [C] is decreased to the target value or less within the processing time.
これに対して、比較例１では（T.Fe）が0.5％以下と
なったため、処理時間内に〔Ｃ〕が目標値まで下がらな
かった。また、比較例2,3では（T.Fe）が６％以上ある
いは（SiO2）が15％以上であるため〔Ｏ〕Ｔが30ppm以
上となり、高清浄度鋼が得られなかった。 On the other hand, in Comparative Example 1, since (T.Fe) was 0.5% or less, [C] did not fall to the target value within the processing time. Further, in Comparative Examples 2 and 3, since (T.Fe) was 6% or more or (SiO 2 ) was 15% or more, [O] T was 30 ppm or more, and high cleanliness steel could not be obtained.
＜発明の効果＞ 本発明によると、極低炭素鋼の溶製において、脱炭速
度を低下させることなく、鋼中介在物を低減させること
ができた。<Effects of the Invention> According to the present invention, it was possible to reduce inclusions in steel during melting of ultra-low carbon steel without decreasing the decarburization rate.
第１図は、鋼中全酸素濃度〔Ｏ〕Ｔと介在物性欠陥指数
との関係を示す特性図、第２図は、（T.Fe）と〔Ｏ〕Ｔ
との関係を示す特性図、第３図は、（SiO2）と〔Ｏ〕Ｔ
との関係を示す特性図、第４図は、（T.Fe）と脱炭不良
率指数との関係を示す特性図である。FIG. 1 is a characteristic diagram showing the relationship between the total oxygen concentration [O] T in steel and the inclusion property defect index, and FIG. 2 is (T.Fe) and [O] T.
Fig. 3 is a characteristic diagram showing the relationship between and (SiO 2 ) and [O] T
And FIG. 4 is a characteristic diagram showing the relationship between (T.Fe) and the decarburization failure rate index.
Claims (3)
鋼の溶製にあたり、真空脱ガス処理前の取鍋スラグ中の
T.Fe濃度を0.5重量％以上、6.0重量％以下とし、かつSi
O2濃度を15.0重量％以下とすることを特徴とする高清浄
度極低炭素鋼の溶製方法。1. When melting ultra-low carbon steel to be decarburized by vacuum degassing, in ladle slag before vacuum degassing
T.Fe concentration is 0.5 wt% or more and 6.0 wt% or less, and Si
A method for producing a high cleanliness ultra-low carbon steel, characterized in that the O 2 concentration is 15.0% by weight or less.
鋼の溶製にあたり、出鋼時に取鍋に流出した取鍋スラグ
を除去し、T.Fe濃度が0.5重量％以上、6.0重量％以下
で、かつSiO2濃度が15.0重量％以下の合成スラグを溶鋼
の上に添加した後、真空脱ガス処理することを特徴とす
る高清浄度極低炭素鋼の溶製方法。2. When melting ultra-low carbon steel that is decarburized by vacuum degassing, the ladle slag that has flowed into the ladle at the time of tapping is removed, and the T.Fe concentration is 0.5% by weight or more and 6.0. A method for producing a highly clean ultra-low carbon steel, which comprises adding synthetic slag having a SiO 2 concentration of not more than 15.0% by weight to the molten steel and then performing vacuum degassing treatment.
鋼の溶製にあたり、出鋼時に取鍋に流出した取鍋スラグ
上にAlあるいはAl滓のような還元剤を添加して該スラグ
中のT.Fe濃度を0.5重量％以上、6.0重量％以下とし、か
つSiO2濃度を15.0重量％以下とした後、真空脱ガス処理
することを特徴とする高清浄度極低炭素鋼の溶製方法。3. When melting ultra-low carbon steel to be decarburized by vacuum degassing, by adding a reducing agent such as Al or Al slag to the ladle slag that has flown into the ladle at the time of tapping. High cleanliness ultra-low carbon steel characterized in that the T.Fe concentration in the slag is 0.5 wt% or more and 6.0 wt% or less and the SiO 2 concentration is 15.0 wt% or less, and then vacuum degassing treatment is performed. Method of melting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1069245A JP2690350B2 (en) | 1989-03-23 | 1989-03-23 | Highly clean ultra low carbon steel melting method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1069245A JP2690350B2 (en) | 1989-03-23 | 1989-03-23 | Highly clean ultra low carbon steel melting method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02250915A JPH02250915A (en) | 1990-10-08 |
| JP2690350B2 true JP2690350B2 (en) | 1997-12-10 |
Family
ID=13397171
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1069245A Expired - Fee Related JP2690350B2 (en) | 1989-03-23 | 1989-03-23 | Highly clean ultra low carbon steel melting method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2690350B2 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5531148A (en) * | 1978-08-28 | 1980-03-05 | Nippon Steel Corp | Manufacture of clean cast steel product |
| JPS60152611A (en) * | 1984-01-18 | 1985-08-10 | Nippon Steel Corp | Method for modifying slag |
| JPS63262412A (en) * | 1987-04-20 | 1988-10-28 | Nippon Steel Corp | Method for cleaning molten steel |
-
1989
- 1989-03-23 JP JP1069245A patent/JP2690350B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02250915A (en) | 1990-10-08 |
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