JPH02250915A - Method for producing high clean dead soft steel - Google Patents
Method for producing high clean dead soft steelInfo
- Publication number
- JPH02250915A JPH02250915A JP6924589A JP6924589A JPH02250915A JP H02250915 A JPH02250915 A JP H02250915A JP 6924589 A JP6924589 A JP 6924589A JP 6924589 A JP6924589 A JP 6924589A JP H02250915 A JPH02250915 A JP H02250915A
- Authority
- JP
- Japan
- Prior art keywords
- slag
- weight
- steel
- less
- ladle
- 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
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 22
- 239000010959 steel Substances 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 8
- 239000002893 slag Substances 0.000 claims abstract description 40
- 238000009849 vacuum degassing Methods 0.000 claims abstract description 10
- 238000010079 rubber tapping Methods 0.000 claims abstract description 8
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 13
- 238000002844 melting Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 239000003638 chemical reducing agent Substances 0.000 claims description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 8
- 238000000034 method Methods 0.000 abstract description 7
- 230000007547 defect Effects 0.000 abstract description 6
- 229910052681 coesite Inorganic materials 0.000 abstract description 4
- 229910052906 cristobalite Inorganic materials 0.000 abstract description 4
- 239000000377 silicon dioxide Substances 0.000 abstract description 4
- 235000012239 silicon dioxide Nutrition 0.000 abstract description 4
- 229910052682 stishovite Inorganic materials 0.000 abstract description 4
- 229910052905 tridymite Inorganic materials 0.000 abstract description 4
- 238000005261 decarburization Methods 0.000 description 10
- 230000007423 decrease Effects 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000002184 metal Substances 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
- 230000000704 physical effect Effects 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
〈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。
〈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０とＣとのＣＯ反応によって脱
炭が行われる。脱炭後、＾ｌ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Ａｆｉ、Ｏ
，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＾ｌとスラグとの反応で
生成する１、０゜量も多（なり、低次＾２キルド鋼に比
べて、鋼中介在物が多い。
鋼中の＾ｌとスラグとの反応を抑えるために、特開昭５
９−７０７１０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
てい名、シかし、この方法をＦｆ４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。
〈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。
く課題を解決するための手段〉
本発明は、■真空脱ガス装置で晟炭処理を施す極低炭素
鋼の溶製において、真空脱ガス処理前の取鍋スラグ中、
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％以下とする手段
を用いることを特徴とする高洗浄極低炭素鋼の溶製方法
であり、また■出鋼時に取鍋に流出した取鍋スラグを除
去した後、Ｔ、Ｆｅ濃度が０．５重量％以上、６．０重
量％以下で、かつＳｉＯ２濃度が１５．０１１１ｔ％以
下の合成スラグをｔｓｔｔａの上に添加することを特徴
とする高洗浄極低炭素鋼の溶製方法で、かつ■出鋼時に
取鍋に流出した取鍋スラグ上にＡｊ！あるいはへ２滓の
ような還元剤を添加して該スラグ中、Ｔ、 Ｆｅ１１１
１度を０．５重量％以上、６．０重量％以下で、かつＳ
ｉＯ２濃度が１５．０重量％以下とすることを特徴とす
る高洗浄極低炭素鋼の溶製方法である。
〈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<Industrial Application Field> The present invention relates to a method for producing ultra-low carbon steel by vacuum degassing treatment. <Conventional technology> Ultra-low carbon steel usually does not completely deoxidize molten steel during tapping.
Decarburization is performed by CO reaction between solid solution 0 and C during vacuum degassing treatment. After decarburization, in order to completely deoxidize the molten steel by adding ^l, Afi, O produced during vacuum degassing treatment is
, the amount of (T, Fe) in the ladle slag does not decrease, and the amount of 1,0° produced by the reaction between the ^l in the steel and the slag after the kill treatment is also large (and low ^2 Compared to killed steel, there are more inclusions in the steel. In order to suppress the reaction between ^l in the steel and slag,
Publication No. 9-70710 discloses a technique for reducing the degree of oxidation of slag by adding a slag modifier to ladle slag. The decarburization reaction rate in the gas equipment decreases and the required C
There was a problem in that it took a long time to decarburize to a certain level, and the actual situation was that it was not used in ultra-low carbon steels because the reason for this was not clear. <Problems to be Solved by the Invention> In view of the problems of the prior art as described above, the present invention has been made to solve the problems of the prior art as described above. The present invention relates to a melting method that can reduce the amount of waste. Means for Solving the Problems> The present invention provides: (1) In the melting of ultra-low carbon steel that is subjected to charcoal treatment in a vacuum degassing device, in the ladle slag before the vacuum degassing treatment,
A method for producing highly clean ultra-low carbon steel characterized by using means for controlling the T, Fe concentration to 0.5% by weight or more and 6.0% by weight or less, and the SiO2 concentration to 15.0% by weight or less. and after removing the ladle slag that flowed into the ladle during tapping, the T and Fe concentrations are 0.5% by weight or more and 6.0% by weight or less, and the SiO2 concentration is 15.0111t% or less. A highly clean ultra-low carbon steel melting method characterized by adding synthetic slag of Aj! Alternatively, a reducing agent such as slag may be added to reduce T, Fe111 in the slag.
1 degree by 0.5% by weight or more and 6.0% by weight or less, and S
This is a method for producing highly clean ultra-low carbon steel, characterized in that the iO2 concentration is 15.0% by weight or less. <Process and effects leading to the invention> The total oxygen concentration in steel is one of the indicators of the cleanliness of steel.
〔０〕７がある。極
低炭素鋼冷延コイルの介在物性欠陥数とThere is [0]7. Number of inclusion defects in ultra-low carbon steel cold-rolled coils
〔０〕７との間
には第１図に示すような関係があり、（０） ｔ ＜３
６ｐｐｍ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、（０） ｙ ＜３０ｐｐｗｍを得るための条件
を調査した結果、次のことが判明した。There is a relationship between [0]7 as shown in Figure 1, and (0) t <3
At 6 ppm, the inclusion defect index decreases to a level that does not pose a problem. Therefore, as a result of investigating the conditions for obtaining (0) y < 30 ppwm, the following was found.
〔０〕！に及ぼすスラグ組成、特に（Ｔ、 Ｆｅ） 。
（Ｓｉｎｇ）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（Ｓｉｎｇ）を１５％以下とする
ことにより[0]! The effect of slag composition on, especially (T, Fe). The influence of (Sing) is shown in Figures 2 and 3. From these figures, it is clear that (T, Fe) in the slag is 6% by weight or less (hereinafter abbreviated as %) and (Sing) is 15%. By doing the following
〔０〕７を３０ｐｐｍ以下とできることが明
らかである。スラグ中の（ＦｅＯ）や（Ｓｉ０、）が鋼
中＾ｌと次に示すような反応をして八！２０、を生成す
るため（Ｔ、 Ｆｅ）や（Ｓｉｎｇ）濃度が高いと〔０
〕７が増加すると考えられる。
２＾Ｊ！＋３ＰｅＯ−ＡＩ！、０３ ＋３Ｆｅ２ ＡＮ
＋３／２ＳｉＯ＊ −ＡＮ ＊＊＊ ＋ ３／２ Ｓ
ｌ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（なる。
これは、脱炭反応に要する０のうちある割合はスラグか
ら供給されていたが、（Ｔ、 ｒｅ）が低い場合には、
この■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。
したがって、スラグ中の（Ｔ、 Ｆｅ）を０．５％以上
、６％以下とし、かつ（Ｓｉｎ、）を１５％以下とする
ことによって、It is clear that [0]7 can be reduced to 30 ppm or less. (FeO) and (Si0,) in the slag react with the steel as shown below. 20, when the (T, Fe) or (Sing) concentration is high,
] 7 is considered to increase. 2^J! +3PeO-AI! , 03 +3Fe2 AN
+3/2SiO* -AN *** +3/2 S
However, in the case of ultra-low carbon steel, vacuum decarburization treatment is performed in the RH equipment, but as shown in Figure 4 (T, Fe
) decreases to below 0.5%, the decarburization defect rate index increases,
The decarburization rate during vacuum decarburization decreases, and the C concentration does not fall to the target value within the operating time. When T, re) is low,
It is thought that the decarburization rate decreases due to the lack of this (■). This new discovery is the reason for the present invention. Therefore, by setting (T, Fe) in the slag to 0.5% or more and 6% or less, and (Sin,) to 15% or less,
〔０〕７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。
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） 、 （ＳｉＯ
ｌ）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０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へｌある
いは＾２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Ｓｉｎｇ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５ｌｏｚを低（しておく必要がある
。
〈実施例〉
実施例と比較例とを以下に説明する。
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＋６
０％、 Ｓｉ０ｇ８８％、 Ａ ｌ ＊Ｏｓ：３１．
４％、Ｔ。
Ｆｅ： ０．６％＞ ３．０００ｋｇを添加した例
である。
実施例２では溶ｆｌ１２８０を上の取鍋スラグ１．００
０贈に対し、へｉ滓（４７２４５０％） ３００ｋｇ
を添加し、実施例３では溶鋼２８０を上の取鍋スラグ１
．０００ｋｇに対し、＾ｌ滓（＾１：５０％） ５０
０ｋｇを添加した。
これに対し、比較例１． ２． ３では溶鋼２８０を上
の取鍋スラグ１，０００ｋｇに対して＾ｌ滓（Ａｊ！
：５０％）を夫々６００ｋｇ、 １５０ｋｇ、 ３
８０ｋｇ添加した。
スラグの成分特に（Ｔ−Ｆｅ） 、（Ｓｉｆｔ）はＲＨ
処理前に、溶鋼中[0]7 is 30 ppm or less, the inclusion defect index is reduced to a level that does not pose a problem, and the decarburization rate is not reduced. Ultra-low carbon steel is tapped without deoxidation and vacuum decarburized in an RH device, so (T, Fe), (SiO
l), it is necessary to adopt a method that does not deoxidize the oxygen in the steel.For example, ladle slag that flows into the ladle during tapping is removed, and synthesized slag with low oxygen potential is used. A method of adding a reducing agent such as l or 2 slag to the metal onto the ladle slag and reducing only the slag can be adopted. When reducing (T, Fe) by slag reduction, (T, Fe)
Since it is difficult to sufficiently reduce Sing without reducing Sing to 0.5% or less, it is necessary to keep the 5Loz in the slag flowing into the ladle low by adjusting the basicity during blowing. 〉 Examples and comparative examples will be described below. In Example 1, after removing the ladle slag that flowed into the ladle during tapping, synthetic slag (CaO + 6
0%, Si0g88%, A l *Os: 31.
4%, T. This is an example in which Fe: 0.6%>3.000 kg was added. In Example 2, melt fl 1280 was added to the upper ladle slag 1.00
For 0 gifts, hei slag (472450%) 300kg
In Example 3, molten steel 280 was added to the ladle slag 1 above.
．． 000kg, ^l slag (^1:50%) 50
0 kg was added. In contrast, comparative example 1. 2. In 3, molten steel 280 is added to 1,000 kg of ladle slag above and slag (Aj!
:50%) respectively 600kg, 150kg, 3
80 kg was added. The components of slag, especially (T-Fe) and (Sift), are RH
During molten steel before processing
〔０〕ア、（Ｃ）ｒはＲＨ処理後に確
認した。
以上の結果を第１表に、纏めて示した。
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（Ｓｉｆｔ）が１
５％以下の場合には、（０〕１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。
第１図は、鋼中全酸素濃度（０）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（０）７との関係を示す特性図、第３図は、（
ＳｉＯｚ）と〔Ｏ１２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。[0]A, (C)r was confirmed after RH treatment. The above results are summarized in Table 1. As shown in the examples in Table 1, ``(T.Fe) in the slag is 0.5% or more and 6% or less, and (Sift) is 1
When it is 5% or less, (0)1 becomes 30 ppm or less, and (C) decreases to below the target value within the treatment time. Figure 1 shows the total oxygen concentration in the steel (0)T and the intervening Figure 2 is a characteristic diagram showing the relationship between the physical property defect index and Figure 3 is a characteristic diagram showing the relationship between (T. Fe) and (0)7.
FIG. 4 is a characteristic diagram showing the relationship between (SiOz) and [O12] and FIG. 4 is a characteristic diagram showing the relationship between (T, Fe) and the decarburization failure rate index.
Claims (3)
製において、真空脱ガス処理前の取鍋スラグ中、Ｔ、Ｆ
ｅ濃度を０．５重量％以上、６．０重量％以下とし、か
つＳｉＯ＿２濃度を１５．０重量％以下とする手段を用
い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 melting of ultra-low carbon steel that is decarburized using a vacuum degassing device, T and F are found in the ladle slag before vacuum degassing.
A method for producing highly clean ultra-low carbon steel, characterized by using means for controlling the e concentration to 0.5% by weight or more and 6.0% by weight or less, and the SiO_2 concentration to 15.0% by weight or less.
、Ｔ、Ｆｅ濃度が０．５重量％以上、６．０重量％以下
で、かつＳｉＯ＿２濃度が１５．０重量％以下の合成ス
ラグを溶鋼の上に添加することを特徴とする高洗浄極低
炭素鋼の溶製方法。(2) After removing the ladle slag that flowed into the ladle during tapping, the T and Fe concentrations are 0.5% by weight or more and 6.0% by weight or less, and the SiO_2 concentration is 15.0% by weight or less. A method for producing highly clean ultra-low carbon steel characterized by adding synthetic slag onto molten steel.
いはＡｌ滓のような還元剤を添加して該スラグ中、Ｔ、
Ｆｅ濃度を０．５重量％以上、６．０重量％以下で、か
つＳｉＯ＿２濃度が１５．０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。(3) A reducing agent such as Al or Al slag is added to the steel tapping slag that flows into the ladle during tapping, and T,
A method for producing highly clean ultra-low carbon steel, characterized in that the Fe concentration is 0.5% by weight or more and 6.0% by weight or less, and the SiO_2 concentration is 15.0% by weight or less.
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 true JPH02250915A (en) | 1990-10-08 |
| JP2690350B2 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) |
Citations (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
Patent Citations (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 |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2690350B2 (en) | 1997-12-10 |
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