JP2744466B2 - Melting method of high clean ultra low carbon steel - Google Patents
Melting method of high clean ultra low carbon steelInfo
- Publication number
- JP2744466B2 JP2744466B2 JP13574989A JP13574989A JP2744466B2 JP 2744466 B2 JP2744466 B2 JP 2744466B2 JP 13574989 A JP13574989 A JP 13574989A JP 13574989 A JP13574989 A JP 13574989A JP 2744466 B2 JP2744466 B2 JP 2744466B2
- Authority
- JP
- Japan
- Prior art keywords
- slag
- sio
- less
- concentration
- steel
- 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
- 229910001209 Low-carbon steel Inorganic materials 0.000 title claims description 13
- 238000000034 method Methods 0.000 title claims description 12
- 238000002844 melting Methods 0.000 title claims description 5
- 230000008018 melting Effects 0.000 title claims description 5
- 239000002893 slag Substances 0.000 claims description 44
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 32
- 238000009849 vacuum degassing Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 description 19
- 239000010959 steel Substances 0.000 description 19
- 238000005261 decarburization Methods 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 10
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 8
- 230000007423 decrease Effects 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000010079 rubber tapping Methods 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 2
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003607 modifier Substances 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、真空装置における高清浄極低炭素鋼の溶製
方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for melting high-purity ultra-low carbon steel in a vacuum apparatus.
〈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反応により脱
炭を行い、その後、Alを添加して溶鋼を完全に脱酸する
ため、真空脱ガス時に生成するAl2O3量が多く、また取
鍋スラグ中T.Fe濃度も低下せず、キルド処理以降、鋼中
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。<Conventional technology> Normally, ultra-low carbon steel does not completely deoxidize molten steel during tapping, but performs decarburization by a CO reaction between dissolved O and C during vacuum degassing, and then removes Al. Since the molten steel is added to completely deoxidize the molten steel, the amount of Al 2 O 3 generated during vacuum degassing is large, and the T.Fe concentration in the ladle slag does not decrease.
The amount of Al 2 O 3 generated by the reaction between Al and slag also increases, and there are more inclusions in the steel than low-carbon Al-killed steel.
鋼中Alとスラグとの反応を抑えるために、特開昭59-7
0710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、この方法ではスラグの酸化度を低下させすぎた場合
には、真空脱ガス装置での脱炭反応速度が低下し、必要
な炭素レベルにまで脱炭するのに要する時間が長くな
る。また、スラグの酸化度の低下が不十分であると、真
空脱ガス処理後の鋼中Alとスラグとの反応を抑えること
ができず鋼中Al2O3量が多くなる。To suppress the reaction between Al in steel and slag, see JP-A-59-7
No. 0710 discloses a technique for adding a slag modifier to ladle slag to reduce the degree of oxidation of the slag. However, in this method, if the degree of oxidation of the slag is excessively reduced, the decarburization reaction rate in the vacuum degassing device decreases, and the time required for decarburization to the required carbon level becomes longer. Further, if the degree of oxidation of the slag is not sufficiently reduced, the reaction between Al in the steel after the vacuum degassing and the slag cannot be suppressed, and the amount of Al 2 O 3 in the steel increases.
〈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、真空
装置での極低炭素鋼の溶製において、脱炭反応速度を低
下させることなく鋼中介在物を低減できる高清浄極低炭
素鋼の溶製方法を提供するためになされたものである。<Problems to be Solved by the Invention> The present invention has been made in view of the above-described problems of the related art, and in melting of ultra-low carbon steel in a vacuum device, inclusions in steel without reducing the decarburization reaction rate. The present invention has been made to provide a method for smelting a high-purity ultra-low carbon steel capable of reducing the carbon content.
〈課題を解決するための手段〉 本発明は、真空装置で脱炭処理を行う極低炭素鋼溶製
において、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、８重量％以下、SiO2濃度を20重量％
以下とし、かつ取鍋耐火物中SiO2含有率を30重量％以下
とすることを特徴とする高清浄極低炭素鋼の溶製方法で
ある。<Means for Solving the Problems> The present invention relates to an ultra-low carbon steel smelting process in which decarburization is performed by a vacuum device, and the T.Fe concentration in a ladle slag before vacuum degassing is 0.5% by weight or more. 8% by weight or less, SiO 2 concentration 20% by weight
A method for melting high-purity ultra-low carbon steel, wherein the content of SiO 2 in a ladle refractory is 30% by weight or less.
〈作用〉 清浄度を表す指標の一つとして鋼中トータル酸素濃度
〔Ｏ〕Tがある。すなわち圧延製品である極低炭素鋼冷
延コイルの介在物性欠陥数と該製品を製造するために使
用した溶鋼中の〔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は０と
なり品質上問題にならないレベルにまで低下する。そこ
で発明者等は〔Ｏ〕T＜30ppmを得るための条件を調査し
た結果、次のことを見出した。<Operation> One of the indexes indicating the cleanliness is the total oxygen concentration [O] T in steel. That is, there is a relationship as shown in FIG. 1 between the number of inclusion defects in the cold rolled ultra low carbon steel coil, which is a rolled product, and the [O] T in the molten steel used to manufacture the product. [O] When T <30 ppm, the inclusion defect index becomes 0, which is reduced to a level that does not cause a problem in quality. Thus, the present inventors have investigated the conditions for obtaining [O] T <30 ppm and found the following.
〔Ｏ〕Tに及ぼす取鍋耐火物中SiO2含有率の影響を第
２図に示しているが、スラグ中T.Fe 0.5重量％（以下％
と略す）以上、15％以下とし、SiO2濃度を４％以上、30
％以下とした場合、取鍋耐火物中SiO2含有率を30％以下
とすることによって〔Ｏ〕Tの平均値が30ppm以下とな
る。更に耐火物中SiO2含有率が小さい程〔Ｏ〕Tは低く
なっている。これは耐火物中SiO2含有率が低いと、耐火
物中SiO2と溶鋼中Alとの反応で生成するAl2O3の量が少
なくなり〔Ｏ〕Tが低下すると考えられる。[O] The effect of the SiO 2 content in the ladle refractory on T is shown in FIG.
) And 15% or less, and the SiO 2 concentration is 4% or more and 30% or less.
% Or less, the average value of [OT] T becomes 30 ppm or less by setting the SiO 2 content in the ladle refractory to 30% or less. Further, the lower the SiO 2 content in the refractory, the lower the [OT] T. It is considered that when the SiO 2 content in the refractory is low, the amount of Al 2 O 3 generated by the reaction between the SiO 2 in the refractory and Al in the molten steel decreases, and [O] T decreases.
次に、〔Ｏ〕Tに及ぼすスラグ組成の影響を第３図，
第４図に示す。第３図は、スラグ中SiO2濃度を４％以
上、30％以下とし、耐火物中SiO2含有率を30％以下とし
た場合のスラグ中のT.Feと〔Ｏ〕Tとの関係を示し、第
４図は、スラグ中T.Feを８％以下とし、耐火物中SiO2含
有率を30％以下とした場合のスラグ中SiO2含有率と
〔Ｏ〕Tとの関係を示している。Next, the effect of slag composition on [O] T is shown in FIG.
As shown in FIG. Fig. 3 shows the relationship between T.Fe and [O] T in slag when the SiO 2 concentration in the slag is 4% or more and 30% or less and the SiO 2 content in the refractory is 30% or less. FIG. 4 shows the relationship between the SiO 2 content in the slag and [O] T when the T.Fe in the slag is 8% or less and the SiO 2 content in the refractory is 30% or less. I have.
この第３図、第４図から取鍋耐火物中SiO2含有率30％
以下の場合、スラグ中のT.Feを８％以下にし、かつSiO2
を20％以下とすることによって〔Ｏ〕Tを30ppm以下とす
ることができることが判明した。スラグ中のFeOやSiO2
が鋼中Alと次に示すような反応を起こしてAl2O3を生成
するため、スラグ中のT.Fe濃度やSiO2濃度が高いと
〔Ｏ〕Tが増加すると考えられる。Figures 3 and 4 show that the content of SiO 2 in the ladle refractory is 30%.
In the following cases, T.Fe in the slag is reduced to 8% or less, and SiO 2
It has been found that [O] T can be reduced to 30 ppm or less by setting the content of O to 20% or less. FeO and SiO 2 in slag
The following reaction occurs with Al in steel to generate Al 2 O 3 , and thus it is considered that [OT] T increases when the concentration of T.Fe or SiO 2 in the slag is high.
２Al＋3FeO＝Al2O3＋３Fe ２Al＋3/2SiO2＝Al2O3＋3/2Si しかしながら、極低炭素鋼の場合、RH法において真空
脱炭処理を施すが、第５図に示すようにスラグ中T.Fe濃
度が0.5％以下になると、真空脱炭中の脱炭反応速度が
低下し、操業時間内に炭素濃度が目標値まで低下しなく
なる。これは、脱炭反応に要する鋼中Ｏのうちある割合
はスラグからの供給でまかなわれるが、スラグ中のT.Fe
が低い場合にはこの量が不足するために生ずると考えら
れる。 2 Al + 3FeO = Al 2 O 3 +3 Fe 2 Al + 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 method, shown in Figure 5 When the T.Fe concentration in the slag becomes 0.5% or less, the decarburization reaction rate during vacuum decarburization decreases, and the carbon concentration does not decrease to the target value within the operation time. This is because a certain percentage of O in steel required for the decarburization reaction is covered by supply from slag, but T.Fe in slag is
Is low, it is considered that this amount is insufficient.
したがって、〔Ｏ〕Tを30ppm以下とするためには、取
鍋耐火物中SiO2含有率を30％以下とし、かつスラグ中の
T.Fe濃度を0.5％以上８％以下、SiO2濃度を20％以下と
することが必要である。Therefore, in order to reduce the [O] T to 30 ppm or less, the SiO 2 content in the ladle refractory should be 30% or less, and the
It is necessary that the T.Fe concentration be 0.5% or more and 8% or less, and the SiO 2 concentration be 20% or less.
極低炭素鋼は未脱酸出鋼し、RH法で真空脱炭するた
め、スラグ中のT.Fe,SiO2濃度を下げる場合に鋼中酸素
を脱酸しない方法を取る必要がある。例えば出鋼時に取
鍋へ流出したスラグを除去し、酸素ポテンシャルの低い
合成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。しかしスラグ還元によってスラグ中
のT.Fe濃度を低下させる場合には、T.Fe濃度を0.5％以
下にしないでSiO2を十分還元することは難しいので、吹
錬中の塩基度調整等により取鍋に流出するスラグ中のSi
O2を低くしておく必要がある。Since ultra-low carbon steel is not deoxidized and subjected to vacuum decarburization by the RH method, it is necessary to adopt a method that does not deoxidize oxygen in steel when lowering the concentration of T.Fe and SiO 2 in slag. For example, removing slag flowing into the ladle during tapping and adding synthetic slag with a low oxygen potential, adding a reducing agent such as metallic Al or Al slag to the ladle, reducing only the slag, etc. Is adopted. However, when the T.Fe concentration in the slag is reduced by slag reduction, it is difficult to sufficiently reduce SiO 2 without reducing the T.Fe concentration to 0.5% or less. Si in the slag flowing into the pot
O 2 needs to be kept low.
〈実施例〉 本発明の実施例と比較例とをまとめて第１表に示す。<Examples> Examples of the present invention and comparative examples are summarized in Table 1.
実施例１では出鋼時に取鍋へ流出したスラグを除去し
た後、合成スラグ（CaO:SiO2：Al2O3:FeO＝55:9:35:1）
を添加した。実施例2,3及び比較例1,2,3,4では取鍋スラ
グ上にAl滓を添加してスラグを還元した。In Example 1, after removing slag flowing out to the ladle during tapping, synthetic slag (CaO: SiO 2 : Al 2 O 3 : FeO = 55: 9: 35: 1)
Was added. In Examples 2 and 3 and Comparative Examples 1, 2, 3 and 4, Al slag was added to the ladle slag to reduce the slag.
取鍋耐火物中SiO2含有率を30％以下とし、かつスラグ
中T.Fe 0.5％以上８％以下、SiO2濃度を30％以下とした
実施例の場合には〔Ｏ〕Tが30ppm以下となり、また鋼中
炭素濃度〔Ｏ〕fが処理時間内に目標値以下まで下がっ
ている。In the case of an embodiment in which the content of SiO 2 in the ladle refractory is 30% or less, the content of T.Fe in the slag is 0.5% or more and 8% or less, and the concentration of SiO 2 is 30% or less, [O] T is 30 ppm or less. And the carbon concentration [O] f in the steel falls below the target value within the treatment time.
これに対して、比較例１ではスラグ中T.Fe濃度すなわ
ち（T.Fe）が0.5％以下となったため、処理時間内に鋼
中〔Ｏ〕fが目標値〔Ｃ〕まで下がらなかった。また比
較例２ではスラグ中T.Fe濃度すなわち（T.Fe）が８％以
上、あるいは比較例３ではスラグ中SiO2濃度（SiO2）が
20％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。比較例４では取鍋耐火物中SiO2
含有率が30％以上であるため、スラグ中T.Fe濃度すなわ
ち（T.Fe）≦８％、スラグ中SiO2濃度（SiO2）≦20％で
あっても〔Ｏ〕Tが30ppm以上となった。On the other hand, in Comparative Example 1, the T.Fe concentration in the slag, that is, (T.Fe) was 0.5% or less, so that [O] f in the steel did not decrease to the target value [C] within the treatment time. In Comparative Example 2, the T.Fe concentration in the slag, that is, (T.Fe) was 8% or more. In Comparative Example 3, the SiO 2 concentration (SiO 2 ) in the slag was
Since the content was 20% or more, [O] T was 30 ppm or more, and high-purity steel could not be obtained. In Comparative Example 4, SiO 2 in the ladle refractory
Since the content is 30% or more, even if the T.Fe concentration in the slag, that is, (T.Fe) ≦ 8%, and the SiO 2 concentration (SiO 2 ) ≦ 20% in the slag, the [O] T is 30 ppm or more. became.
〈発明の効果〉 本発明方法によると、脱炭速度を低下させることな
く、鋼中介在物が低減された高清浄極低炭素鋼を溶製す
ることができる。 <Effects of the Invention> According to the method of the present invention, it is possible to smelt a high-purity ultra-low carbon steel with reduced inclusions in steel without reducing the decarburization rate.
第１図は、鋼中酸素〔Ｏ〕Tと介在物性欠陥との関係を
示す特性図、第２図は、取鍋耐火物中SiO2含有率と
〔Ｏ〕Tとの関係を示す特性図、第３図は、スラグ中
（T.Fe）と〔Ｏ〕Tとの関係を示す特性図、第４図は、
スラグ中（SiO2）と〔Ｏ〕Tとの関係を示す特性図、第
５図は、スラグ中（T.Fe）と脱炭不良率との関係を示す
特性図である。FIG. 1 is a characteristic diagram showing a relationship between oxygen [O] T in steel and inclusion defect, and FIG. 2 is a characteristic diagram showing a relationship between SiO 2 content in ladle refractory and [O] T. FIG. 3 is a characteristic diagram showing the relationship between (T.Fe) in slag and [O] T, and FIG.
FIG. 5 is a characteristic diagram showing a relationship between (SiO 2 ) in slag and [O] T. FIG. 5 is a characteristic diagram showing a relationship between (T.Fe) in slag and a decarburization failure rate.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭63−277708（ＪＰ，Ａ) 特開 平２−250915（ＪＰ，Ａ) 特開 平１−92311（ＪＰ，Ａ) ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-277708 (JP, A) JP-A-2-250915 (JP, A) JP-A-1-92311 (JP, A)
Claims (1)
において、 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、８重量％以下、SiO2濃度を20重量％以下とし、
かつ取鍋耐火物中SiO2含有率を30重量％以下とすること
を特徴とする高清浄極低炭素鋼の溶製方法。(1) In the production of ultra-low carbon steel which is decarburized by a vacuum device, the T.Fe concentration in the ladle slag before vacuum degassing is 0.5% by weight or more and 8% by weight or less, and SiO 2 concentration. 20% by weight or less,
A method for melting high-purity ultra-low carbon steel, wherein the content of SiO 2 in the ladle refractory is 30% by weight or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13574989A JP2744466B2 (en) | 1989-05-31 | 1989-05-31 | Melting method of high clean ultra low carbon steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13574989A JP2744466B2 (en) | 1989-05-31 | 1989-05-31 | Melting method of high clean ultra low carbon steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH032315A JPH032315A (en) | 1991-01-08 |
| JP2744466B2 true JP2744466B2 (en) | 1998-04-28 |
Family
ID=15158972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13574989A Expired - Lifetime JP2744466B2 (en) | 1989-05-31 | 1989-05-31 | Melting method of high clean ultra low carbon steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2744466B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100452304B1 (en) * | 1999-12-28 | 2004-10-08 | 주식회사 포스코 | Manufacturing method of ultra-low-carbon steel with high cleanliness |
-
1989
- 1989-05-31 JP JP13574989A patent/JP2744466B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH032315A (en) | 1991-01-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2575827B2 (en) | Manufacturing method of ultra low carbon steel for continuous casting with excellent cleanliness | |
| JPH09263820A (en) | Method for producing Al-killed steel without clusters | |
| JP2003073726A (en) | Method for producing low Ti steel | |
| CN101463411B (en) | Low carbon steel sheet, low carbon steel cast piece and method for production thereof | |
| JP2744466B2 (en) | Melting method of high clean ultra low carbon steel | |
| JP3319245B2 (en) | Method for producing highly clean austenitic stainless steel | |
| JP3282531B2 (en) | Melting method of high clean steel | |
| JPH10317049A (en) | Melting method of high clean steel | |
| JPH10158720A (en) | High purification refining method for stainless steel | |
| JP3577357B2 (en) | Method for producing ultra-low carbon steel with excellent surface properties | |
| JP2690350B2 (en) | Highly clean ultra low carbon steel melting method | |
| JP3297992B2 (en) | Melting method of high clean ultra low carbon steel | |
| EP0163784B1 (en) | Two stage deoxidation process in steel-making | |
| JPH10195520A (en) | High purification method for Al-containing stainless steel | |
| JP3253138B2 (en) | Melting method of high cleanness ultra low carbon steel | |
| JP3742615B2 (en) | Method of melting high cleanliness steel | |
| JP3297998B2 (en) | Melting method of high clean ultra low carbon steel | |
| JP3390478B2 (en) | Melting method of high cleanliness steel | |
| JP3198250B2 (en) | Vacuum refining method for molten steel containing chromium | |
| JP2855334B2 (en) | Modification method of molten steel slag | |
| JPH07316631A (en) | Deoxidation and cleaning method for molten steel | |
| JPH05331523A (en) | Method for refining molten steel for bearing steel | |
| JPH0730388B2 (en) | Low oxygen ultra low carbon steel manufacturing method | |
| JPH03153816A (en) | Smelting method for high purity steel | |
| JP3525793B2 (en) | Method of melting ultra-low carbon steel |