JPH0465883B2 - - Google Patents
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- Publication number
- JPH0465883B2 JPH0465883B2 JP62054216A JP5421687A JPH0465883B2 JP H0465883 B2 JPH0465883 B2 JP H0465883B2 JP 62054216 A JP62054216 A JP 62054216A JP 5421687 A JP5421687 A JP 5421687A JP H0465883 B2 JPH0465883 B2 JP H0465883B2
- Authority
- JP
- Japan
- Prior art keywords
- ppm
- deoxidizing
- decarburization
- low carbon
- region
- 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
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- 238000005261 decarburization Methods 0.000 claims description 49
- 229910000831 Steel Inorganic materials 0.000 claims description 25
- 239000010959 steel Substances 0.000 claims description 25
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 15
- 229910052760 oxygen Inorganic materials 0.000 claims description 15
- 239000001301 oxygen Substances 0.000 claims description 15
- 239000003795 chemical substances by application Substances 0.000 claims description 11
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000000034 method Methods 0.000 description 18
- 230000008569 process Effects 0.000 description 13
- 230000000694 effects Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は転炉出鋼後の取鍋溶鋼を減圧下で脱炭
処理する方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for decarburizing molten steel in a ladle after being tapped in a converter under reduced pressure.
（従来の技術）
自動車用の熱冷延鋼板は深絞り性、張り出し性
等の加工性向上のため、鋼材中の〔Ｃ〕濃度を極
力低減する必要がある。このニーズに対し、製鋼
工程では転炉での吹止〔Ｃ〕の低減及び二次精錬
工程での減圧下脱炭処理（第３版鉄鋼便覧製銑
製鋼671〜685頁に各種の処理装置が示されてい
る）によつて対処してきた。特にRH、DH等の
熱力学的に有利な減圧下での脱炭過程を利用した
プロセスでは、これまで環流量の増大、真空度の
向上等の対策により処理後の達成〔Ｃ〕も徐々に
減少しているが、〔Ｃ〕20ppm以下は通常処理の
15〜20分程度では容易には達成できていない。(Prior Art) In order to improve workability such as deep drawability and stretchability in hot and cold rolled steel sheets for automobiles, it is necessary to reduce the [C] concentration in the steel material as much as possible. To meet this need, the steelmaking process includes reduction of blowout [C] in the converter and decarburization treatment under reduced pressure in the secondary refining process (see the 3rd edition Iron and Steel Handbook, pp. 671-685 for various processing equipment). (as shown). In particular, in processes that utilize thermodynamically advantageous decarburization processes such as RH and DH under reduced pressure, it has been possible to gradually achieve [C] after treatment by increasing the recirculation flow rate and improving the degree of vacuum. However, [C] less than 20ppm is less than normal treatment.
This cannot be achieved easily in about 15 to 20 minutes.
（発明が解決しようとする問題点）
本発明は従来の二次精錬における減圧下脱炭プ
ロセスの前記の限界が解消でき、短時間で極低炭
域が到達可能な減圧下脱炭処理法を提供すること
を目的とする。(Problems to be Solved by the Invention) The present invention provides a method for decarburizing under reduced pressure that can overcome the above-mentioned limitations of the conventional decarburization process under reduced pressure in secondary refining and can reach an extremely low carbon range in a short time. The purpose is to provide.
（問題点を解決するための手段）
本発明の要旨とするところは下記のとおりであ
る。(Means for solving the problems) The gist of the present invention is as follows.
(1) 転炉から出鋼された未脱酸溶鋼をRH、DH
の減圧下脱炭処理するに際し、処理開始から
〔Ｃ〕30ppm到達までの間、鋼中の溶解酸素
〔Ｏ〕fを400ppm以上に制御し、その後〔Ｃ〕
30ppm未満の領域において脱酸剤を一括投入す
ることによつて鋼中溶解酸素〔Ｏ〕fを50〜
200ppmに弱脱酸した後、さらに処理し、その
後完全脱酸することを特徴とする極低炭素鋼の
製造方法。(1) Undeoxidized molten steel tapped from the converter is subjected to RH and DH
When decarburizing under reduced pressure, the dissolved oxygen [O] f in the steel is controlled to 400 ppm or more from the start of the process until [C] reaches 30 ppm, and then [C]
By adding a deoxidizer all at once in the region of less than 30 ppm, the dissolved oxygen [O] f in steel can be reduced to 50~50 ppm.
A method for producing ultra-low carbon steel, which is characterized by weakly deoxidizing to 200 ppm, further processing, and then complete deoxidizing.
(2) 転炉から出鋼された未脱酸溶鋼をRH、DH
の減圧下脱炭処理するに際し、処理開始から
〔Ｃ〕30ppm到達までの間、鋼中の溶解酸素
〔Ｏ〕fを400ppm以上に制御し、その後〔Ｃ〕
30ppm未満の領域において脱酸剤を溶鋼環流量
にしたがつて所定原単位になるように連続的又
は断続的に添加して鋼中溶解酸素〔Ｏ〕fを50〜
200ppmに弱脱酸した後、さらに処理し、その
後完全脱酸することを特徴とする極低炭素鋼の
製造方法。(2) Undeoxidized molten steel tapped from the converter is subjected to RH and DH
When decarburizing under reduced pressure, the dissolved oxygen [O] f in the steel is controlled to 400 ppm or more from the start of the process until [C] reaches 30 ppm, and then [C]
In the region of less than 30 ppm, a deoxidizing agent is added continuously or intermittently to a predetermined basic unit according to the molten steel circulation flow rate to reduce the dissolved oxygen [O] f in the steel to 50~50 ppm.
A method for producing ultra-low carbon steel, which is characterized by weakly deoxidizing to 200 ppm, further processing, and then complete deoxidizing.
以下本発明を具体的に説明する。 The present invention will be specifically explained below.
本発明者らは、減圧下での脱炭プロセスの能力
向上のため主としてRHを用い脱炭挙動に及ぼす
各種要因について調査検討した。その結果、第１
図に示すように減圧下での脱炭推移は脱炭速度の
大きい領域と脱炭速度の小さい領域、領域
のほぼ３領域に分けられ、主として真空排気の遅
れが原因でおこる低脱炭速度の領域を除き、
領域、領域の脱炭速度に及ぼす要因として次の
ことがわかつた。 The present inventors mainly used RH to investigate and study various factors that affect decarburization behavior in order to improve the ability of the decarburization process under reduced pressure. As a result, the first
As shown in the figure, the decarburization transition under reduced pressure can be divided into three areas: a high decarburization rate area, a low decarburization rate area, and a low decarburization rate area, which is mainly caused by a delay in evacuation. except for the area
The following factors were found to affect the decarburization rate in different regions.
ほぼ〔Ｃ〕30ppm程度までの領域については
従来から環流量の増大等により脱炭速度が増大す
ることは周知であるが、本発明者らは領域の脱
炭について第２図に示すように最適〔Ｏ〕fが存在
することを見出した。なお、第２図において、
Kcは脱炭速度定数（１／min）であり(1)式より
求められる。 It is well known that the decarburization rate increases due to an increase in the recirculation flow in the region up to approximately [C] 30ppm, but the present inventors have developed an optimal method for decarburization in the region as shown in Figure 2. We found that [O] f exists. In addition, in Figure 2,
Kc is the decarburization rate constant (1/min) and is obtained from equation (1).
−ｄ〔Ｃ〕／dt＝Kc〔Ｃ〕 ……(1)
すなわち基本的には脱炭反応の〔Ｃ〕当量に見
合う以上の〔Ｏ〕f量が必要であり本発明者らの実
験結果では処理前〔Ｃ〕150〜350ppm程度の範囲
であれば最適〔Ｏ〕fは400ppm以上であることが
わかつた。しかも〔Ｏ〕fの制御方法として、転炉
吹止〔Ｏ〕の制御又は処理開始前又は直後の酸素
吹付（OB）または酸化鉄の添加等による酸素付
加は効果的であるが、処理開始後約５分以降から
のOB等による酸素付加は最適〔Ｏ〕fであつても
効果がないかあるいはむしろ逆効果であることも
明らかとなつた。 −d[C]/dt=Kc[C]...(1) In other words, basically, an amount of [O] f that is greater than the equivalent of [C] for the decarburization reaction is required, and the experimental results of the present inventors It was found that the optimal [O] f is 400 ppm or more when the pre-treatment [C] is in the range of about 150 to 350 ppm. Moreover, as a control method for [O] f , controlling the converter blow-off [O], oxygen blowing (OB) before or immediately after the start of treatment, or adding oxygen by adding iron oxide, etc. is effective, but after the start of treatment, It has become clear that adding oxygen by OB or the like after about 5 minutes has no effect, or even has the opposite effect, even at the optimum [O] f .
又〔Ｃ〕30ppm未満の低〔Ｃ〕域である領域
の脱炭速度には特願昭61−82239号に示されてい
る〔Ｏ〕fへの影響が本発明者らの実機実験でも認
められ、第３図に示すようにAl等によつて弱脱
酸し、ほぼ50〜200ppmの〔Ｏ〕fにした場合、脱
炭速度が最も大きくなることがわかつた。さらに
本発明者らの実験の結果、実機脱炭プロセスで
領域の〔Ｏ〕fを50〜200ppmに弱脱酸し、制御す
る際、第４図に示すように弱脱酸前の〔Ｏ〕fが
400ppm以上の高い値の場合に効果が大きく、
400ppm未満から弱脱酸を行なつても効果が小さ
いことが明らかとなつた。したがつて、領域
全体で考えると弱脱酸前の〔Ｏ〕fは400ppm以上
が良いことになる。又、弱脱酸を行なう弱脱酸剤
として脱酸力の弱いTiを用いた場合、Al等の強
脱酸剤より効果的であることも明らかとなつた。
なお弱脱酸の方法として、Alで一部脱酸後Tiで
脱酸する方法も有効である。 In addition, the decarburization rate in the low [C] region of less than 30 ppm has an influence on [O] f as shown in Japanese Patent Application No. 61-82239, which was also recognized in actual experiments conducted by the present inventors. As shown in FIG. 3, it was found that the decarburization rate was the highest when weakly deoxidized with Al or the like to bring the [O] f to approximately 50 to 200 ppm. Furthermore, as a result of experiments conducted by the present inventors, when the [ O ] f is
The effect is greater when the value is higher than 400ppm,
It became clear that even weak deoxidation at less than 400 ppm had little effect. Therefore, considering the entire region, [O] f before weak deoxidation is preferably 400 ppm or more. It has also become clear that when Ti, which has a weak deoxidizing power, is used as a weak deoxidizing agent, it is more effective than a strong deoxidizing agent such as Al.
Note that as a weak deoxidation method, it is also effective to partially deoxidize with Al and then deoxidize with Ti.
なお、領域での〔Ｏ〕f制御として、処理中の
OBが効果がないか、むしろ逆効果であるのは溶
鋼自由表面にＣ−Ｏ反応を阻害するFeO膜が生成
し、またFeO膜の消失にある程度の時間が必要で
あるからと考えられる。領域において、脱炭に
最適な〔Ｏ〕f範囲として〔Ｏ〕fの上限がある理由
については過剰〔Ｏ〕が表面活性元素として働き
脱炭反応を阻害するからであると考えられる。他
方、領域における脱炭に最適な〔Ｏ〕fの範囲の
下限を50ppmと限定した理由は、第３図に領域
における〔Ｏ〕fと脱炭速度定数Kcとの関係を示
すように、脱炭速度係数Kcは〔Ｏ〕fが50ppm未
満になると急激に低下して、本発明の効果が達成
されなくなるからである。また領域での〔Ｏ〕f
の弱脱酸制御において、弱脱酸前の〔Ｏ〕fが
400ppm以上の高い場合、効果的である理由は、
弱脱酸生成物がCO気泡生成核として働くためそ
の脱酸生成物が多いほど効果的であることによる
と考えられる。さらに弱脱酸制御に用いる脱酸剤
としてAl等に比べTiが効果的な理由は、Al等の
脱酸力の強い脱酸材使用の場合、〔Ｏ〕fが50〜
200ppmでは、鋼中にAlは残存しないが、Tiの場
合、(2)、(3)式の学振推奨平衡値（昭和59年11月日
本学術振興会製鋼第19委員会発行）よれば約30〜
290ppm存在するため最適〔Ｏ〕fの範囲内でも表
面活性元素の〔Ｏ〕fがある程度溶鋼自由表面に富
化しようとするのを妨げる効果を有し、脱炭反応
が促進されるためと考えられる。 In addition, as [O] f control in the area, the
The reason why OB is ineffective, or rather has the opposite effect, is thought to be because an FeO film is formed on the free surface of the molten steel, which inhibits the C-O reaction, and it takes a certain amount of time for the FeO film to disappear. The reason why there is an upper limit of [O] f as the optimum [O] f range for decarburization in this region is thought to be that excess [O] acts as a surface active element and inhibits the decarburization reaction. On the other hand, the reason why the lower limit of the optimal range of [O] f for decarburization in the region was limited to 50 ppm is as shown in Figure 3, which shows the relationship between [O] f in the region and the decarburization rate constant Kc. This is because the coal velocity coefficient Kc rapidly decreases when [O] f becomes less than 50 ppm, and the effects of the present invention cannot be achieved. Also, [O] f in the area
In weak deoxidation control, [O] f before weak deoxidation is
The reason why it is effective when it is higher than 400ppm is that
This is thought to be because weak deoxidation products act as CO bubble generation nuclei, and the more deoxidation products there are, the more effective it is. Furthermore, the reason why Ti is more effective than Al etc. as a deoxidizing agent used for weak deoxidation control is that when using a deoxidizing agent with strong deoxidizing power such as Al, [O] f is 50~
At 200 ppm, no Al remains in the steel, but in the case of Ti, according to the JSPS recommended equilibrium value of equations (2) and (3) (published by the 19th Steelmaking Committee of the Japan Society for the Promotion of Science in November 1981), approximately 30～
This is thought to be because even within the optimum [O] f range, the surface-active element [O] f has the effect of preventing the surface-active element [O]f from enriching to some extent on the free surface of molten steel, promoting the decarburization reaction. It will be done.
3Ti＋５Ｏ＝Ti3O5(S) ……(2)
iog Ｋ＝log a3 Tiap 5＝−89300／Ｔ＋30.30 ……(3)
また、弱脱酸用の脱酸剤の添加方法として真空
槽内に一括して添加した場合、添加直後は真空槽
内溶鋼が局部的に強脱酸され、取鍋内溶鋼は未脱
酸の状態から徐々に均一混合されるに従つて全体
が弱脱酸鋼となるが、その間は脱炭反応が十分進
まない状態となるので、溶鋼環流量に見合つて所
定原単位となるよう脱酸剤を連続的に又は所定原
単位の脱酸剤を断続的に、例えば２〜10分割して
添加すれば、脱炭反応が主として進むと考えられ
る真空槽内の脱炭反応が脱酸剤添加直後から進む
ことになり効果的である。3Ti+5 O = Ti 3 O 5 (S) ...(2) iog K=log a 3 Ti a p 5 = -89300/T+30.30 ...(3) Also, how to add a deoxidizer for weak deoxidation When added all at once into a vacuum chamber, immediately after addition, the molten steel in the vacuum chamber is strongly deoxidized locally, and the molten steel in the ladle is gradually and homogeneously mixed from an undeoxidized state until the whole becomes deoxidized. Although the steel becomes weakly deoxidized, the decarburization reaction does not progress sufficiently during this period, so the deoxidizing agent is applied continuously or at a predetermined basic unit depending on the molten steel circulation flow rate. If it is added intermittently, for example in 2 to 10 portions, the decarburization reaction in the vacuum chamber, where the decarburization reaction is thought to proceed, will proceed immediately after the addition of the deoxidizing agent, which is effective.
溶鋼環流量を表す式としては下式が実湯での実
験結果として、鉄と鋼、54（1968）1342頁に提案
されており、本実験式に基づいて溶鋼環流量を処
理中に変更することができる。 As a formula for expressing the molten steel recirculation flow rate, the following formula is proposed in Tetsu to Hagane, 54 (1968) p. 1342 as a result of experiments with actual hot water, and based on this experimental formula, the molten steel recirculation flow rate can be changed during processing. be able to.
Ｗ＝0.02D1.5G0 0.33 ……(4)
ここに、Ｗ：溶鋼環流量（ｔ／min）
Ｄ：上昇管内径（cm）
G0：環流Arガス流量（Ｎ／min）
（作用）
本発明に従い、領域の〔Ｏ〕fを〔Ｃ〕30ppm
到達までの間、400ppm以上に制御することによ
り高い脱炭速度を維持し、短時間で低〔Ｃ〕領域
である領域に到達することができ、次いで領
域で弱脱酸して〔Ｏ〕fを50〜200ppmに制御する
ことにより、脱炭に必要な〔Ｏ〕f当量以上の過剰
な〔Ｏ〕が表面活性元素として働き、反応界面で
の脱炭反応の阻害およびCOガス離脱の阻害を防
止すると共に、弱脱酸時に生成したTiO2、Al2O3
等の酸化物が脱炭反応時に生成するCO気泡生成
核となり、このため低〔Ｃ〕域の領域での脱炭
速度の低下が小さくなり、減圧下脱炭プロセスと
して短時間で20ppm以下の極低〔Ｃ〕溶鋼が製造
可能となる。 W=0.02D 1.5 G 0 0.33 ...(4) Where, W: Molten steel circulation flow rate (t/min) D: Rising pipe inner diameter (cm) G 0 : Circulation Ar gas flow rate (N/min) (action) According to the invention, [O] f in the area [C] 30ppm
By controlling the decarburization rate to 400 ppm or higher, it is possible to maintain a high decarburization rate and reach a low [C] region in a short time, and then weakly deoxidizes in the [O] f region. By controlling the amount of [O] to 50 to 200 ppm, excess [O] exceeding the [O] f equivalent required for decarburization acts as a surface active element, inhibiting the decarburization reaction at the reaction interface and inhibiting CO gas separation. In addition to preventing TiO 2 and Al 2 O 3 generated during weak deoxidation.
These oxides become the CO bubble generation nucleus generated during the decarburization reaction, and as a result, the decrease in decarburization rate in the low [C] region becomes small, and as a decarburization process under reduced pressure, the decarburization process can be carried out in a short period of time to a maximum of 20 ppm or less. Low [C] molten steel can be manufactured.
（実施例） 以下、実施例に基づき本発明を更に説明する。(Example) The present invention will be further explained below based on Examples.
第５図に本発明例（、）及び比較例の
RHでの試験結果を示す。 Figure 5 shows examples of the present invention (,) and comparative examples.
Test results at RH are shown.
本発明例（、）、比較例ともRHでのOB
等による〔Ｏ〕f制御をしていない例であり、比較
例の場合、〔Ｏ〕fが領域で400ppm未満で、
領域で〔Ｏ〕fが300ppm以上の場合の結果である
が、処理時間が15〜20分で到達〔Ｃ〕レベルは20
〜25ppmと高い。 OB at RH for both the invention example (,) and comparative example
This is an example in which [O] f control is not performed by etc., and in the case of a comparative example, [O] f is less than 400 ppm in the area,
This is the result when [O] f is 300 ppm or more in the area, but the [C] level reached in 15 to 20 minutes is 20
~25ppm high.
一方本発明例の場合、領域の〔Ｏ〕fを510
〜550ppmとし、処理開始10分後の〔Ｃ〕22ppm
到達時点でAlを一括投入して脱酸し、〔Ｏ〕fを
165ppmとした後、６分間〔Ｏ〕fを150〜165ppm
の状態で処理したもので領域の脱炭速度は大き
く且つ領域の脱炭速度の停滞も小さく比較例
に比べ脱炭速度は大きく処理16分の結果として
〔Ｃ〕16ppmが得られた。 On the other hand, in the case of the present invention, the area [O] f is 510
~550ppm, 10 minutes after starting treatment [C] 22ppm
At that point, Al is added all at once to deoxidize, and [O] f is
After setting it to 165ppm, set [O] f to 150 to 165ppm for 6 minutes.
The decarburization rate in the region was high and the stagnation in the decarburization rate in the region was small, and the decarburization rate was higher than that of the comparative example, and 16 ppm of [C] was obtained as a result of treatment in 16 minutes.
さらに本発明例の場合、領域の〔Ｏ〕fを
630〜680ppmとし、処理開始10分の〔Ｃ〕19ppm
到達時点でTiをRH槽内に環流量に見合つて連続
的に投入して脱酸し〔Ｏ〕fを90ppmとした後、６
分間〔Ｏ〕fを80〜100ppmの状態で処理したもの
で、本発明例と同様領域の脱炭速度は大き
く、領域の脱炭速度は本発明例より大きくな
つている。本発明例の場合は、処理16分で
〔Ｃ〕12ppmが得られた。 Furthermore, in the case of the present invention example, [O] f of the area is
630-680ppm, 19ppm [C] 10 minutes after starting treatment
At that point, Ti was continuously added into the RH tank in proportion to the recirculation amount to deoxidize the [O] f to 90 ppm, and then
The decarburization rate in the same region as the example of the present invention is high, and the decarburization rate in the region is higher than that of the example of the present invention. In the case of the present invention, 12 ppm of [C] was obtained after 16 minutes of treatment.
さらに第６図に転炉吹止〔Ｏ〕fが低くRHにて
酸素吹付（OB）による酸素付加を行なつた場合
の本発明例と比較例の場合を示す。 Furthermore, FIG. 6 shows an example of the present invention and a comparative example in which oxygen was added by oxygen blowing (OB) at RH with a low converter blow-off [O] f .
本発明例の場合、転炉吹止〔Ｏ〕fが450ppm
であり、RH処理開始前に〔Ｏ〕fが380ppmとなつ
たが、OBにより〔Ｏ〕fを680ppmとし、その後
RH処理を開始した例であり、〔Ｏ〕fを600〜
680ppmで処理し、次いで〔Ｃ〕28ppm時点でAl
により弱脱酸を行ない〔Ｏ〕fを120ppmとした後、
約８分間処理した例であり領域の脱炭速度は大
きく、処理16分で〔Ｃ〕16ppmが得られた。 In the case of the present invention, the converter blow-off [O] f is 450 ppm
Therefore, [O] f was 380 ppm before the start of RH treatment, but [O] f was changed to 680 ppm by OB, and then
This is an example of starting RH processing, and setting [O] f to 600
680ppm, then [C] Al at 28ppm
After weakly deoxidizing [O] f to 120 ppm,
This is an example in which the treatment was carried out for about 8 minutes, and the decarburization rate in this region was high, with 16 ppm of [C] obtained in 16 minutes of treatment.
比較例の場合、〔Ｏ〕fが転炉吹止で420ppm、
開始時点で350ppmであり、RH処理後５分時点
でOBを行ない、〔Ｏ〕fを330ppmから720ppmに富
化し処理を続け、ついで〔Ｃ〕25ppm時点にAl
により弱脱酸を行ない、〔Ｏ〕f80ppmとした後、
約７分間処理した例であるが、領域でOBを行
ない酸素付加しても脱炭速度の向上は認められ
ず、結果的に〔Ｃ〕20ppm以下を得るのに処理時
間20分を要した。 In the case of the comparative example, [O] f was 420 ppm at the converter blow-off,
350ppm at the start, OB was performed 5 minutes after RH treatment, [O] enriched f from 330ppm to 720ppm and treatment continued, and then [C] Al was added at 25ppm.
After weak deoxidation to [O] f 80ppm,
In this example, the treatment was performed for about 7 minutes, but no improvement in the decarburization rate was observed even when oxygen was added by performing OB in the area, and as a result, it took 20 minutes to obtain [C] of 20 ppm or less.
（発明の効果）
以上説明したとおり、本発明により、短時間で
極低炭素域まで容易に到達できる経済的且つ効率
的な減圧下脱炭処理が可能となつた。(Effects of the Invention) As explained above, according to the present invention, economical and efficient decarburization treatment under reduced pressure that can easily reach an extremely low carbon range in a short time has become possible.
第１図は、減圧した脱炭プロセスの処理中の
〔Ｃ〕推移を示す図、第２図は減圧下脱炭プロセ
スにおける領域での脱炭速度定数（Kc）と溶
解酸素〔Ｏ〕fとの関係を示す図、第３図は減圧下
脱炭プロセスにおける領域での脱炭速度定数
（KC）と溶解酸素〔Ｏ〕fとの関係を示す図、第４
図は減圧下脱炭プロセスにおける領域での脱炭
速度定数（KC）と弱脱酸前溶解酸素〔Ｏ〕fとの
関係を示す図、第５図、第６図は本発明例と比較
例での〔Ｃ〕、〔Ｏ〕推移を示す図である。
Figure 1 shows the change in [C] during the decarburization process under reduced pressure, and Figure 2 shows the decarburization rate constant (Kc) and dissolved oxygen [O] f in the decarburization process under reduced pressure. Figure 3 is a diagram showing the relationship between the decarburization rate constant (KC) and dissolved oxygen [O] f in the region in the decarburization process under reduced pressure.
The figure shows the relationship between the decarburization rate constant (KC) and the dissolved oxygen [O] f before weak deoxidation in the region of the decarburization process under reduced pressure. Figures 5 and 6 are examples of the present invention and comparative examples. It is a diagram showing the transition of [C] and [O] in .
Claims (1)
の減圧下脱炭処理するに際し、処理開始から
〔Ｃ〕30ppm到達までの間、鋼中の溶解酸素〔Ｏ〕
fを400ppm以上に制御し、その後〔Ｃ〕30ppm未
満の領域において脱酸剤を一括投入することによ
つて鋼中溶解酸素〔Ｏ〕fを50〜200ppmに弱脱酸
した後、さらに処理し、その後完全脱酸すること
を特徴とする極低炭素鋼の製造方法。 ２ 弱脱酸する脱酸剤として、TiあるいはAlを
用いることを特徴とする特許請求の範囲第１項記
載の極低炭素鋼の製造方法。 ３ 弱脱酸はAlで一部脱酸した後、Tiで脱酸す
ることを特徴とする特許請求の範囲第１項記載の
極低炭素鋼の製造方法。 ４ 転炉から出鋼された未脱酸溶鋼をRH、DH
の減圧下脱炭処理するに際し、処理開始から
〔Ｃ〕30ppm到達までの間、鋼中の溶解酸素〔Ｏ〕
fを400ppm以上に制御し、その後〔Ｃ〕30ppm未
満の領域において脱酸剤を溶鋼環流量にしたがつ
て所定原単位になるように連続的又は断続的に添
加して鋼中溶解酸素〔Ｏ〕fを50〜200ppmに弱脱
酸した後、さらに処理し、その後完全脱酸するこ
とを特徴とする極低炭素鋼の製造方法。 ５ 弱脱酸する脱酸剤として、TiあるいはAlを
用いることを特徴とする特許請求の範囲第４項記
載の極低炭素鋼の製造方法。 ６ 弱脱酸はAlで一部脱酸した後、Tiで脱酸す
ることを特徴とする特許請求の範囲第４項記載の
極低炭素鋼の製造方法。[Claims] 1. Undeoxidized molten steel tapped from a converter is subjected to RH and DH.
During decarburization treatment under reduced pressure of
f is controlled to 400 ppm or more, and then a deoxidizing agent is added all at once in the region of [C] less than 30 ppm to weakly deoxidize the dissolved oxygen [O] f in the steel to 50 to 200 ppm, and then further treatment is performed. , followed by complete deoxidation. 2. The method for producing ultra-low carbon steel according to claim 1, characterized in that Ti or Al is used as the deoxidizing agent that performs weak deoxidation. 3. The method for producing ultra-low carbon steel according to claim 1, wherein the weak deoxidation is performed by partially deoxidizing with Al and then deoxidizing with Ti. 4 Undeoxidized molten steel tapped from the converter is subjected to RH and DH
During decarburization treatment under reduced pressure of
f is controlled to 400 ppm or more, and then a deoxidizing agent is added continuously or intermittently to a predetermined basic unit according to the molten steel circulation flow rate in the region of [C] less than 30 ppm to reduce dissolved oxygen [O ] A method for producing ultra-low carbon steel, which comprises weakly deoxidizing f to 50 to 200 ppm, further processing, and then completely deoxidizing. 5. The method for producing ultra-low carbon steel according to claim 4, characterized in that Ti or Al is used as the deoxidizing agent for weakly deoxidizing. 6. The method for producing ultra-low carbon steel according to claim 4, wherein the weak deoxidation is performed by partially deoxidizing with Al and then deoxidizing with Ti.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61-224874 | 1986-09-25 | ||
| JP22487486 | 1986-09-25 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63190113A JPS63190113A (en) | 1988-08-05 |
| JPH0465883B2 true JPH0465883B2 (en) | 1992-10-21 |
Family
ID=16820521
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5421687A Granted JPS63190113A (en) | 1986-09-25 | 1987-03-11 | Production of dead low carbon steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63190113A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0717937B2 (en) * | 1989-04-20 | 1995-03-01 | 川崎製鉄株式会社 | Manufacturing method of high cleanliness ultra low carbon steel |
| JPH0730388B2 (en) * | 1989-07-26 | 1995-04-05 | 川崎製鉄株式会社 | Low oxygen ultra low carbon steel manufacturing method |
| JPH049423A (en) * | 1990-04-27 | 1992-01-14 | Kawasaki Steel Corp | Method for smelting dead soft steel |
| JP3548273B2 (en) * | 1995-04-20 | 2004-07-28 | 新日本製鐵株式会社 | Melting method of ultra low carbon steel |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5418415A (en) * | 1977-07-12 | 1979-02-10 | Kawasaki Steel Co | Method of treating molten steel for preventing nitrogen increase in steel |
-
1987
- 1987-03-11 JP JP5421687A patent/JPS63190113A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5418415A (en) * | 1977-07-12 | 1979-02-10 | Kawasaki Steel Co | Method of treating molten steel for preventing nitrogen increase in steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63190113A (en) | 1988-08-05 |
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