JPH03197614A - Method for melting extremely low carbon steel with rh degassing treatment - Google Patents
Method for melting extremely low carbon steel with rh degassing treatmentInfo
- Publication number
- JPH03197614A JPH03197614A JP33717989A JP33717989A JPH03197614A JP H03197614 A JPH03197614 A JP H03197614A JP 33717989 A JP33717989 A JP 33717989A JP 33717989 A JP33717989 A JP 33717989A JP H03197614 A JPH03197614 A JP H03197614A
- Authority
- JP
- Japan
- Prior art keywords
- low carbon
- steel
- half period
- extremely low
- carbon 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.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 19
- 229910001209 Low-carbon steel Inorganic materials 0.000 title claims abstract description 16
- 238000007872 degassing Methods 0.000 title claims abstract description 13
- 238000002844 melting Methods 0.000 title claims abstract description 7
- 230000008018 melting Effects 0.000 title claims abstract description 7
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 35
- 239000010959 steel Substances 0.000 claims abstract description 35
- 238000006243 chemical reaction Methods 0.000 claims abstract description 18
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 15
- 238000005261 decarburization Methods 0.000 claims description 24
- 238000010992 reflux Methods 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000007796 conventional method Methods 0.000 abstract description 6
- 238000005262 decarbonization Methods 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 11
- 239000011261 inert gas Substances 0.000 description 10
- 229910052760 oxygen Inorganic materials 0.000 description 10
- 239000001301 oxygen Substances 0.000 description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 238000007664 blowing Methods 0.000 description 6
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000007654 immersion Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000011819 refractory material Substances 0.000 description 3
- 238000009849 vacuum degassing Methods 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001021 Ferroalloy Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はRH脱ガス処理による極低炭素鋼の溶製方法に
係り、特にC≦20ppm範囲の低炭素域で脱炭を促進
する溶製方法に関する。Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing ultra-low carbon steel by RH degassing treatment, and in particular, a method for producing ultra-low carbon steel that promotes decarburization in the low carbon range of C≦20 ppm. Regarding the method.
一般に極低炭素鋼の溶製工程は、先ず大気圧下で酸素を
吹込んで鉄の酸化損失の少いC: 0.03〜0.05
%まで粗脱炭する工程と、該溶鋼を減圧下に露出させて
00分圧を低減することにより、出鋼時500〜700
ppmに調整した溶存酸素と鋼中の〔C〕とのCoガス
化を促進させて、C;10〜20PP■まで脱炭する工
程と、に大別される。Generally, in the melting process of ultra-low carbon steel, oxygen is first injected under atmospheric pressure to reduce iron oxidation loss by C: 0.03 to 0.05.
%, and exposing the molten steel under reduced pressure to reduce the partial pressure of 500 to 700%.
It is roughly divided into a process of promoting Co gasification between dissolved oxygen adjusted to ppm and [C] in the steel, and decarburizing to C; 10 to 20 PP.
本発明は後者の工程に関するものである。The present invention relates to the latter process.
上記分野での従来技術では、不活性ガスを大量に吹込む
方法、減圧下での気体酸素の吹込み、減圧溶鋼中への酸
化鉄粉の吹込方法等が知られているが、これらには次の
如き問題点がある。Conventional techniques in the above-mentioned fields include a method of blowing in large amounts of inert gas, a method of blowing gaseous oxygen under reduced pressure, and a method of blowing iron oxide powder into molten steel under reduced pressure. There are the following problems.
すなわち、不活性ガスの大量吹込みに関しては松永ら(
鉄と鋼、Vol、63、No、13.1977年)、特
願昭63−093467等いくつかの文献が見られるが
、これらは、脱ガス処理中の溶鋼環流速度の向上、もし
くはスプラッシュの増加による気液界面の増加により脱
炭速度の向上を図ったものである。しかしながら、これ
らの方法では脱炭速度の向上がみられる反面、真空脱ガ
ス槽内の地金付着が増加するため、溶鋼成分調整用の合
金鉄歩留の不安定化のほか、鉄分歩留の減少、真空脱ガ
ス槽内付着地金除去のための休止時間の発生、RH脱ガ
ス環流管の耐火物の寿命の低下等の多くの操業上の問題
が生じていた。In other words, regarding the injection of large amounts of inert gas, Matsunaga et al.
There are several documents such as Tetsu to Hagane, Vol. 63, No. 13, 1977) and Japanese Patent Application No. 63-093467, which discuss improvements in the molten steel circulation speed during degassing treatment or an increase in splash. The aim is to improve the decarburization rate by increasing the gas-liquid interface. However, although these methods improve the decarburization rate, they also increase the amount of metal adhesion in the vacuum degassing tank, which not only destabilizes the ferroalloy yield for adjusting the molten steel composition, but also reduces the iron content yield. Many operational problems have arisen, such as reduction in fuel consumption, downtime to remove metal deposits in the vacuum degassing tank, and reduced lifespan of refractories in the RH degassing recirculation pipe.
また減圧下の溶鋼浴面や浴面下に気体酸素を吹込む方法
は溶存酸素量の増加を図ることになり、反応速度の向上
を図ることができるが、溶鋼浴面吹付けの場合は、不活
性ガスの大量吹込みと同様にスプラッシュの増加を伴う
問題があり、また浴面下に吹込む方法は、著しいスプラ
ッシュの増加に加え、羽口周辺耐火物の損耗に伴う真空
脱ガス槽の寿命低下を招く欠点がある。更に両方法とも
溶鋼全体の溶解酸素量を増大させるため、脱酸処理後の
脱酸生成物が大量発生し、溶鋼清浄度の悪化およびこれ
に起因する鋼材製品における疵の発生の増加を助長する
おそれがあり、この面での配慮に欠けていた。In addition, the method of blowing gaseous oxygen into the molten steel bath surface or below the bath surface under reduced pressure increases the amount of dissolved oxygen and can improve the reaction rate, but in the case of molten steel bath surface spraying, Similar to large amounts of inert gas injection, there is a problem with an increase in splash, and the method of blowing below the bath surface not only causes a significant increase in splash, but also reduces the vacuum degassing tank due to wear and tear on the refractories around the tuyeres. It has the disadvantage of shortening its lifespan. Furthermore, since both methods increase the amount of dissolved oxygen in the entire molten steel, a large amount of deoxidation products are generated after deoxidation treatment, which worsens the cleanliness of molten steel and increases the occurrence of defects in steel products due to this. There was a lack of consideration in this aspect.
更に、特開昭60−181217や、日本鉄鋼協会講演
論文集CAMP −I S I J Vol、1(1
988,P、1185)等に見られる如き、減圧下で溶
鋼面に酸化物粉体を上吹きする方法、もしくは、特開昭
63−169321に開示された如き、減圧下の溶鋼に
酸素ポテンシャルの高い粉体を浴面下に設けた羽口より
直接溶鋼中に吹込む方法では、鋼浴内に侵入、拡散した
粉体の近傍に酸素ポテンシャルの高い部分が生成し、局
部的な領域での脱炭が促進される結果、溶鋼全体の清浄
度悪化を制御しなから脱炭限界の向上、極低炭素域にお
ける脱炭速度の向上が可能となる反面、スプラッシュの
増加や、羽口の損耗の問題は解決されておらず、特に極
低炭素処理を行っていない場合でも、羽口の閉塞防止の
ために不活性ガスを吹き続けなければならない点は1羽
口周辺耐火物の損耗を助長するだけでなく、コスト的に
も無駄の多い技術と言わざるを得ない。Furthermore, Japanese Patent Application Laid-open No. 181217/1983, Collection of Lectures by the Iron and Steel Institute of Japan, CAMP-IS I J Vol. 1 (1
988, P, 1185), etc., or the method of top-blowing oxide powder onto the surface of molten steel under reduced pressure, or the method of adding oxygen potential to molten steel under reduced pressure, as disclosed in JP-A-63-169321. In the method of directly injecting high-oxygen powder into molten steel through tuyeres installed below the bath surface, areas with high oxygen potential are generated near the powder that has entered and diffused into the steel bath, causing As a result of accelerated decarburization, it is possible to improve the decarburization limit and increase the decarburization speed in the extremely low carbon range without controlling the deterioration of the cleanliness of the entire molten steel. The problem has not been resolved, and the fact that inert gas must be continuously blown to prevent the tuyeres from clogging, even when ultra-low carbon treatment is not performed, contributes to the wear and tear of the refractories around the tuyeres. It must be said that this technology is not only wasteful in terms of cost, but also wasteful in terms of cost.
更に、RH脱ガス処理における極低炭素鋼の溶製操業に
おいて、C≦20ppmの極低炭素域において、脱炭速
度が急激に落ちる開運を解決するため、特開昭60−6
3311および特開昭63−213617においては、
Ar等の環流用不活性ガス吹込量を増大させ、環流溶鋼
量を増大させる方法が開示されている。すなわち、特開
昭60−63311では、減圧速度を平均速度で120
ト一ル/win以上として真空度の早期向上により、c
o気泡の発生を促進し反応界面積の増大を図ると共に、
環流用不活性ガス吹込量Q (Nm3/5in)の下限
を次の如く限定している。Furthermore, in order to solve the problem that the decarburization rate drops rapidly in the ultra-low carbon range of C≦20ppm in the melting operation of ultra-low carbon steel in RH degassing treatment, JP-A-60-6
3311 and JP-A-63-213617,
A method of increasing the amount of recirculated molten steel by increasing the amount of reflux inert gas such as Ar is disclosed. That is, in JP-A-60-63311, the average speed of decompression is 120
C
o In addition to promoting the generation of bubbles and increasing the reaction interface area,
The lower limit of the reflux inert gas injection amount Q (Nm3/5in) is set as follows.
ただし D: 浸漬管内径(m)
また、特開昭63−213617では、RH脱ガス処理
中の溶鋼環流量を鋼中C含有量〔C〕に基づいて次の如
く次第に増加する方法をとっている。However, D: Immersion pipe inner diameter (m) Furthermore, in JP-A-63-213617, a method is adopted in which the flow rate of molten steel during RH degassing treatment is gradually increased based on the C content [C] in the steel as follows. There is.
すなわち、
(イ)処理開始から〔C〕≦1100pp1までは15
0 t /鳳in未満
(ロ)〔C〕が1100pp未満から30ppmまで1
50 t / win以上200 t / akin未
満(ハ)〔C〕が30pP朧未満では200 t /
win以上と限定している。That is, (a) 15 from the start of processing until [C]≦1100pp1
Less than 0 t/in (B) [C] from less than 1100 ppm to 30 ppm 1
50 t/win or more and less than 200 t/akin (c) If [C] is less than 30 pP hazy, 200 t/win
Limited to win or above.
しかしながら、本発明者が浸漬管内径600m+aのR
H脱ガス槽を用いて処理時間を延長して実験した結果C
≦20ppmの低炭素域で脱炭が停滞することを確認し
た。However, the inventor of the present invention
Results of an experiment using a H degassing tank and extending the processing time C
It was confirmed that decarburization stagnates in the low carbon range of ≦20 ppm.
本発明の目的は、RH脱ガス処理による極低炭素鋼の溶
製方法における上記従来技術の問題点を解決し、〔C〕
≦20ppmの極低炭素域においても、脱炭反応が円滑
に促進し得る効果的な溶製方法を提供するにある。The purpose of the present invention is to solve the above-mentioned problems of the prior art in a method for producing ultra-low carbon steel by RH degassing treatment, and [C]
The object of the present invention is to provide an effective melting method that can smoothly promote the decarburization reaction even in the extremely low carbon range of ≦20 ppm.
本発明の要旨とするところは次の如くである。 The gist of the present invention is as follows.
すなわち、RH脱ガス処理中の溶鋼環流量を鋼中のC含
有量〔C〕に基づいて変化させる極低炭素鋼の溶製方法
において、前記〔C〕が〔C〕〉20ppmまでの脱炭
反応の前半期には環流ガス量を33〜42 N Q /
min、txとし、〔C〕≦20ppmの脱炭反応の後
半期に環流ガス量を8〜25 N Q /min、aa
に低下させることを特徴とするRH説ガス処理による極
低炭素鋼の溶製方法である。ここで環流ガス量は浸漬管
内径1aIl、1分間当りの量を示すものである。That is, in a method for producing ultra-low carbon steel in which the flow rate of molten steel during RH degassing treatment is changed based on the C content [C] in the steel, decarburization is performed until the above [C] is [C]>20 ppm. In the first half of the reaction, the reflux gas amount was set at 33 to 42 NQ/
min, tx, and in the latter half of the decarburization reaction when [C]≦20 ppm, the reflux gas amount is 8 to 25 N Q /min, aa
This is a method for producing ultra-low carbon steel by RH theory gas treatment, which is characterized by reducing the amount of carbon. Here, the amount of reflux gas indicates the amount per minute when the inner diameter of the immersion tube is 1aIl.
本発明者が実施した実験に基づき本発明を説明する。転
炉で粗脱炭した〔C〕 ’= 300ppmの約160
0℃の溶鋼についてRH処理を施した結果は第1図に示
すとおりである。第1図には斜線を施した従来法による
結果を併せ示した。The present invention will be explained based on experiments conducted by the inventor. Roughly decarburized in a converter [C]' = approximately 160 of 300 ppm
The results of RH treatment on molten steel at 0°C are shown in Figure 1. Figure 1 also shows the results obtained by the conventional method, which are shaded.
すなわち、従来法によって環流ガス量を変化せずにRH
処理した場合には、〔C〕がほぼ20ppmで停滞して
それ以上の脱炭が不可能であったが1本発明においては
RH処理開始から〔C〕420ppmまでは42 N
Q /win、ca (浸漬管の内径11当り、1分間
当りの環流ガス流量)とし、〔C〕弁20ppm以降は
環流ガス流量を17NQ/min、cmに低減したとこ
ろ、脱炭反応はそれ以後も促進されて、処理開始後20
分を経過して〔C〕≦l0PP園を達成することができ
た。In other words, the conventional method can reduce the RH without changing the amount of recirculated gas.
When treated, [C] stagnates at approximately 20 ppm and further decarburization is impossible; however, in the present invention, from the start of RH treatment to [C] 420 ppm, 42 N
Q/win, ca (recirculation gas flow rate per minute per inner diameter of the immersion tube), and after [C] valve 20 ppm, the recirculation gas flow rate was reduced to 17NQ/min, cm, and the decarburization reaction continued after that. Also promoted, 20 minutes after the start of treatment
After a few minutes passed, I was able to achieve [C]≦l0PP garden.
また、この場合のRH後半期の溶鋼中の酸素Oは平均2
0ppm、Nは平均20ppmで、最終〔C〕=8 p
p@であった。In addition, in this case, the average oxygen O in the molten steel in the latter half of RH is 2
0 ppm, N is 20 ppm on average, final [C] = 8 p
It was p@.
従来法による場合は、〔C〕≦20ppimの極低炭素
域においては、第2図に示すように環流溶鋼2中に微細
気泡4が多く発生し、環流溶鋼量が多い場合、すなわち
環流速度が大きい時は取鍋6にも微細気泡4が環流して
戻るので脱炭が停滞するものと考えられる。In the case of the conventional method, in the ultra-low carbon range of [C]≦20ppm, many fine bubbles 4 are generated in the reflux molten steel 2 as shown in Fig. 2, and when the amount of reflux molten steel is large, that is, the reflux velocity is low. When the bubbles are large, the fine bubbles 4 also flow back into the ladle 6, so decarburization is considered to be stagnant.
なお、
環流溶鋼量: W (t /w+in)不活性ガス吹込
深さ:H(m)
不活性ガス吹込量:QNrn’/醜in浸漬管内径:D
(m)
なる関係があるので、環流溶鋼量は不活性ガス吹込量に
比例するので、本発明において不活性ガスの吹込量を〔
C〕≦20pP−の極低炭素域で減少することにより、
環流速度が低下して溶鋼中の微細CO気泡の真空槽内の
滞留時間が延長され、気散除去されるので脱炭反応が極
低炭素域でも促進され、〔C〕≦10pp■の極低炭素
鋼の溶製が可能となったものと考えられる。In addition, circulating molten steel amount: W (t/w+in) Inert gas injection depth: H (m) Inert gas injection amount: QNrn'/Ugly in immersion pipe inner diameter: D
(m) Since the amount of circulating molten steel is proportional to the amount of inert gas blown, in the present invention, the amount of inert gas blown is
C] ≦20pP- by decreasing in the extremely low carbon range,
The reflux rate decreases, and the residence time of fine CO bubbles in the molten steel in the vacuum chamber is extended, and the decarburization reaction is promoted even in the extremely low carbon range, and the decarburization reaction is promoted even in the extremely low carbon range. It is thought that this made it possible to melt carbon steel.
RH脱炭ガス処理による極低炭素鋼の溶製に際し、特に
〔C〕≦20ppmの極低炭素域における脱炭を促進す
るために、環流ガス量を多く流し、環流溶鋼サイクルを
上げた方が効果があるとの従来技術と反対に、本発明は
、脱炭の〔C〕〉20ppmまでの前半期の環流ガス量
を33〜42 N Q /min、allとし、 〔C
〕≦20ppmの脱炭反応の後半期に環流ガス量を8〜
25 N Q /n+in。When melting ultra-low carbon steel by RH decarburization gas treatment, it is better to flow a large amount of recirculation gas and increase the recirculation molten steel cycle, especially in order to promote decarburization in the ultra-low carbon range of [C]≦20ppm. Contrary to the conventional technology which is said to be effective, the present invention sets the reflux gas amount in the first half of decarburization to [C] 20 ppm to 33 to 42 N Q /min, all [C]
] ≦20ppm In the latter half of the decarburization reaction, the amount of reflux gas is reduced to 8~
25 N Q /n+in.
■に低減することにより、脱炭の後半期においても、脱
炭反応が停滞することなく促進し、〔C〕≦l0PPI
Iの極低炭素鋼の溶製が可能となる効果を挙げることが
できた。■By reducing the temperature, the decarburization reaction is promoted without stagnation even in the latter half of decarburization, and [C]≦l0PPI
We were able to achieve the effect of making ultra-low carbon steel (I) possible.
第1図は本発明によるRH脱ガス処理による極低炭素鋼
溶製の実施例におけるRH処理時間と溶鋼のC濃度との
関係を従来例と対比する線図、第2図は〔C〕≦20p
pmの極低炭素域における従来法↓こおける脱炭反応の
停滞を説明する模式断面図である。
4・・・・・・・・・微細気泡
6・・・・・・・・・取鍋Figure 1 is a diagram comparing the relationship between the RH treatment time and the C concentration of molten steel in an example of ultra-low carbon steel melting by RH degassing treatment according to the present invention with a conventional example, and Figure 2 is a diagram comparing [C]≦ 20p
It is a schematic cross-sectional view explaining the stagnation of the decarburization reaction in the conventional method ↓ in the extremely low carbon range of pm. 4・・・・・・・・・Fine bubbles 6・・・・・・Ladle
Claims (1)
〔C〕に基づいて変化させる極低炭素鋼の溶製方法にお
いて、前記〔C〕が〔C〕>20ppmまでの脱炭反応
の前半期には環流ガス量を33〜42Nl/min、c
mとし、〔C〕≦20ppmの脱炭反応の後半期に環流
ガス量を8〜25Nl/min、cmに低下させること
を特徴とするRH脱ガス処理による極低炭素鋼の溶製方
法。(1) In an ultra-low carbon steel melting method in which the molten steel circulation flow rate during RH degassing treatment is changed based on the C content [C] in the steel, the above [C] is degassed until [C] > 20 ppm. In the first half of the carbon reaction, the reflux gas amount was set at 33 to 42 Nl/min, c
A method for producing ultra-low carbon steel by RH degassing treatment, characterized in that the amount of recirculated gas is reduced to 8 to 25 Nl/min, cm in the latter half of the decarburization reaction when [C]≦20 ppm.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP33717989A JPH06104845B2 (en) | 1989-12-26 | 1989-12-26 | Method of melting ultra low carbon steel by RH degassing |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP33717989A JPH06104845B2 (en) | 1989-12-26 | 1989-12-26 | Method of melting ultra low carbon steel by RH degassing |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH03197614A true JPH03197614A (en) | 1991-08-29 |
JPH06104845B2 JPH06104845B2 (en) | 1994-12-21 |
Family
ID=18306193
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP33717989A Expired - Lifetime JPH06104845B2 (en) | 1989-12-26 | 1989-12-26 | Method of melting ultra low carbon steel by RH degassing |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH06104845B2 (en) |
-
1989
- 1989-12-26 JP JP33717989A patent/JPH06104845B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JPH06104845B2 (en) | 1994-12-21 |
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