JPH0368083B2 - - Google Patents
Info
- Publication number
- JPH0368083B2 JPH0368083B2 JP56111356A JP11135681A JPH0368083B2 JP H0368083 B2 JPH0368083 B2 JP H0368083B2 JP 56111356 A JP56111356 A JP 56111356A JP 11135681 A JP11135681 A JP 11135681A JP H0368083 B2 JPH0368083 B2 JP H0368083B2
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- gas
- flow rate
- decarburization
- recirculation
- 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
- 239000007789 gas Substances 0.000 claims description 41
- 229910000831 Steel Inorganic materials 0.000 claims description 39
- 239000010959 steel Substances 0.000 claims description 39
- 238000005261 decarburization Methods 0.000 claims description 30
- 238000007664 blowing Methods 0.000 claims description 20
- 238000007872 degassing Methods 0.000 claims description 16
- 238000010992 reflux Methods 0.000 claims description 13
- 238000007654 immersion Methods 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 4
- 230000001737 promoting effect Effects 0.000 claims description 3
- 238000007670 refining Methods 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims 1
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 229920006395 saturated elastomer Polymers 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 3
- 238000009849 vacuum degassing Methods 0.000 description 3
- 238000010079 rubber tapping Methods 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000005262 decarbonization Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
Description
この発明は溶鋼の真空精錬方法に関し、なかで
も環流式真空処理いわゆるRH脱ガス法の改善、
とくに脱ガス処理中における脱炭の有効な促進を
図ろうとするものである。
鋼の高級化ならびにその需要の増加に伴ない
RH脱ガス処理には従来以上の脱ガス脱炭能が要
求され、併せて処理時間の短縮も強く要求される
ようになつた。
一般にRH脱ガスの反応サイトは、
(1) 真空槽内溶鋼自由表面
(2) 上昇管内ガス気泡表面
であるとされ、このうち脱炭反応については(1)の
真空槽内溶鋼自由表面の寄与率が大きく、およそ
全脱炭の70〜90％であるとされている。
そこで従来は、(1)の真空槽内溶鋼自由表面積を
増大させるという点に注目して溶鋼環流速度を増
大すべくアルゴンガスを代表例とする不活性気体
の吹込量の増加の外、環流管路口径の拡大や、該
管路数の増加により脱炭能を高め、その処理時間
の短縮をはかつてきた。しかし該真空槽つまり
RH脱ガス槽内の環流を司る上昇管内に供給する
環流用吹込ガスを増量すると、ある程度までは溶
鋼環流量および、槽内撹拌効果が増大するが、環
流量の増加傾向はしだいに鈍化して飽和状態に至
る。従来かような飽和傾向が生起する場合には、
前記環流用吹込ガスは、もはや脱炭反応の促進に
は十分な寄与がないばかりでなくとくに、飽和状
態を超えて環流用ガス吹込量を増すと吹抜け、そ
の他ガス偏流のため無益に逸出するガス量が増
し、かえつて環流量の低下をもたらすと考えられ
て、環流用吹込ガスは、前記飽和傾向が生起する
量をその吹込み上限量とし、その限度内で上昇管
中に供給をし、これによつて溶鋼の脱炭が行われ
ていたものである。
発明者らの経験によると、250トン程度のRH
脱ガス槽における溶鋼環流量と環流用吹込みガス
流量の関係につき、上昇管の口径をパラメータと
して第１図に示すが、従来タイプの口径300mmφ
では、溶鋼環流量が約30t／minで限界に達し、
またこの口径を400mmφおよび450mmφに拡大して
それぞれ約70t／minおよび約90t／minの飽和環
流量が得られる。
従つて第１図に明らかなように口径450mmφの
上昇管を用いるとき環流用吹込ガス流量が約
1800Nl／min以上において環流量はほぼ一定とな
り飽和するため従来1500〜1800Nl／minの範囲内
の環流量吹込ガス流量をもつてする操作での脱ガ
ス処理が一般に行なわれていたものである。
このようにして環流能力を拡大し、その環流量
を最大とすべく環流用吹込ガス量を溶鋼環流量の
飽和領域附近に設定して脱ガスを行う場合におい
て、とくにその処理時間延長を図つたとしても、
到達〔Ｃ〕はほぼ30ppm程度が限界であり、また
その処理時間の延長は直ちに処理中の温度降下を
甚しくして転炉出鋼温度を高くする必要を生じこ
れはとくに出鋼温度上昇に伴つて炉材原単位の増
加のみならず処理時間増により溶鋼供給面におい
て連鋳の安定操業を害するなど不利な問題を派生
する。
この発明は上記問題を解決してRH脱ガス槽に
おける脱ガス時の脱炭促進に効率のよい方法を提
供するもので、現状のRH脱ガス設備を変えるこ
となく、上昇管に供給する環流用吹込ガス流量を
とくに上掲の溶鋼環流量の飽和領域を超える量と
することによつて脱炭反応の著しい促進、脱ガス
時間の短縮が予期に反して実現されることの知見
に基づくものである。
この実験に用いたRH真空処理設備の要部を第
２図に示し、図中１は容量250トンの真空槽の底
壁への取付けフランジ、２は溶鋼の上昇流を導く
内径450mmφの浸潰管、３はその鉄心、４はその
耐火物であり、５はとくに４mmφの口径で浸潰管
２の下部内面16か所で開口する吹込み用細管羽
口、６はとくに20mmφの口径で浸潰管の下部中央
で上向きに開口する追加吹込み用ランスである。
発明者らは、RH真空処理による脱ガスの効率
を上げるべく種々の実験を行い、環流量の増加を
目指して、上昇管下降管とも口径の拡大による効
果の確認につとめた。実験の過程で、従来はじめ
にのべたように寄与の程度が極めて低いために殆
どかえりみられなかつた上昇管内に生成する吹込
ガス気泡の表面が、吹込ガス流量の如何により特
異の挙動を呈する意外な事実に着目したものであ
る。
このようにして環流用吹込ガス流量をして、溶
鋼環流量の飽和領域を超える吹込み量とし、とく
に上昇管内におけるガス気泡表面を増大させるこ
とにより次のような脱炭能の向上が実現された。
すなわち第３図に環流用吹込ガスの吹込み量
と、真空脱ガス処理15分後の到達Ｃ値を示した。
上昇管は口径450mmφにおいて図に示すように
1800Nl／minをこえる2000〜5000Nl／minの吹込
み量すなわち、溶鋼の環流量飽和領域を超えたガ
ス吹込みを行つてとくにすぐれた脱炭効果が示さ
れ、この脱炭は、溶鋼環流量の飽和領域を大きく
超えた5000Nl／minに達してはじめて飽和に至
る。
この結果は、上述した従来の考え方のもとには
到底予期され得なかつたところであり、例えばこ
の真空脱ガス槽の通常の吹込み量1800Nl／minの
場合は、リムド処理中の脱炭速度定数ｋは
0.158min-1なるが、この発明に従い溶鋼環流量飽
和領域を超える吹込み量として、3000Nl／minお
よび5000Nl／minの吹込みを行つた場合、ｋはそ
れぞれ0.203min-1、0.228min-1となり、おのおの
約1.3倍、1.4倍強の値となる。第１図につきのべ
た結果に従いいずれの場合も溶鋼環流量はほぼ同
程度であるため、真空脱ガス槽内における自由表
面からの脱炭速度も同等と考えると、従来の
1800Nl／min（環流飽和点）の場合、全脱炭量に
対する上昇管内Ar気泡表面のみの寄与率を従来
知られている最大に見積つて30％とすれば、
3000Nl／minの場合におけるその寄与率は45.5
％、または5000Nl／minの場合の寄与率は51.5％
にも達するのである。
ここにリムド中における脱炭反応は見掛上次の
１次反応として表わされ、これを上記計算の基礎
とした。
dc／dt＝−ｋ・ｔ
ｃ：〔Ｃ〕分析値（％）
ｋ：見掛けの脱炭速度定数（min-1）
ｔ：反応時間（min）
またここに脱炭速度定数は処理前〔Ｃ〕値すな
わち処理時間Ｔ＝０のときの〔Ｃ〕値をCp、そし
てＴ時間後の〔Ｃ〕値をCTであらわして
loCO／CT＝−ｋ・Ｔ
の関係により求めることができる。
かくしてこの発明に従う上昇管内脱炭寄与率の
上記改善に及ぼす環流用吹込ガス流量の関係は、
第４図に示すとおりである。
すなわち、従来考えられていたように溶鋼環流
量の飽和領域を超える環流ガス吹込みは無駄であ
るのではなく、この発明に従い環流ガスを溶鋼環
流量の飽和領域を超えるような大流量にした場合
には、従来考えられていた以上に上昇管内のAr
気泡表面での脱炭が進行して脱ガス時の脱炭促進
がはたされていると考えられる。
従つて到達Ｃ値によつてガス吹込量を定めてガ
ス供給を行なえば所定処理時間内での脱炭操作が
可能となり、このガス供給量は上述、上昇管内の
Ar気泡表面における脱炭反応と推察されること
から、上昇管内断面積と吹込量の関係で表わすこ
とができ、従つて上記3000Nl／minは、ほぼ
1.8Nl／min・cm2、5000Nl／minはほぼ3.2Nl／
min・cm2として、一般のRH脱ガス処理時の上昇
管内環流用吹込ガス量として定めれば同様な効果
を得ることができる。
また、上例において環流用吹込ガスを
5000Nl／min程度で吹込むことにより〔Ｃ〕
10ppm台の極低炭素鋼を溶製することもでき、従
つてこの発明による脱炭促進は、5000Nl／min、
すなわち3.15Nl／min・cm2を、環流用吹込みガス
の吹込み量上限として、脱炭反応のより有効な促
進を図ることができる。
以下実施例についてのべる。
口径450mmφの浸漬管２の下縁部に溶鋼の環流
用吹込ガスの吹込みのため内径４mmで16孔をそな
える鋼管羽口５を設け、これよりArガスを
2000Nl／minで、一方浸漬管２の下部中央に内径
20mmφの耐火物被覆をもつランスを配置しこれよ
り、Arガスを1000Nl／minで、従つて都合
3000Nl／minの吹き込み、処理中の真空度は0.5
〜10torrの範囲内で行ない、脱炭を目的とするリ
ムド処理に15分、Al添加後の脱酸を目的とする
キルド処理に20分、合計35分の処理時間を要し
た。
以上の条件に伴う実験結果の一例は次の通りで
ある。
This invention relates to a method for vacuum refining of molten steel, and in particular, improvement of the reflux vacuum processing so-called RH degassing method.
In particular, the aim is to effectively promote decarburization during degassing treatment. With the increasing quality of steel and the increase in demand for it
RH degassing treatment requires greater degassing and decarburization ability than before, and there is also a strong demand for shorter treatment time. In general, the reaction sites for RH degassing are (1) the free surface of the molten steel in the vacuum chamber, and (2) the surface of gas bubbles in the riser pipe.For the decarburization reaction, the contribution of (1) the free surface of the molten steel in the vacuum chamber is The rate is large, and is said to be approximately 70 to 90% of all decarburization. Conventionally, focusing on (1) increasing the free surface area of molten steel in the vacuum chamber, in order to increase the molten steel reflux velocity, in addition to increasing the amount of inert gas blown in, typically argon gas, By increasing the pipe diameter and the number of pipes, the decarburization ability has been improved and the processing time has been shortened. However, the vacuum chamber is clogged.
Increasing the amount of recirculation blowing gas supplied to the riser pipe that controls the recirculation in the RH degassing tank will increase the molten steel recirculation flow rate and the stirring effect in the tank to a certain extent, but the increasing trend in the recirculation flow rate will gradually slow down. reaching saturation. When such a saturation tendency occurs,
Not only does the reflux blown gas no longer make a sufficient contribution to promoting the decarburization reaction, but especially when the reflux gas blown amount is increased beyond the saturated state, it wastefully escapes due to blow-through and other gas drifts. It is thought that the amount of gas increases and the recirculation flow rate decreases, so the upper limit of the blowing gas for recirculation is set to the amount at which the saturation tendency occurs, and the gas is supplied into the riser within that limit. This was how molten steel was decarburized. According to the inventors' experience, the RH of about 250 tons
The relationship between the molten steel recirculation flow rate and the recirculation blowing gas flow rate in the degassing tank is shown in Figure 1 using the diameter of the riser pipe as a parameter.
In this case, the flow rate of molten steel reaches its limit at approximately 30t/min.
Furthermore, by enlarging this diameter to 400 mmφ and 450 mmφ, saturated recirculation flow rates of approximately 70 t/min and approximately 90 t/min can be obtained, respectively. Therefore, as shown in Figure 1, when using a riser pipe with a diameter of 450 mm, the flow rate of the blown gas for circulation is approximately
Since the recirculation flow rate becomes almost constant and saturated above 1800 Nl/min, degassing treatment has conventionally been carried out by operating the recirculation gas flow rate within the range of 1500 to 1800 Nl/min. In this way, the recirculation capacity is expanded, and when degassing is performed by setting the recirculation blowing gas amount near the saturation region of the molten steel recirculation flow rate in order to maximize the recirculation flow rate, the processing time is particularly extended. Even though
The limit for the attainment [C] is approximately 30 ppm, and extending the processing time immediately causes a severe temperature drop during the treatment, making it necessary to raise the converter tapping temperature, which is particularly important for the rise in the tapping temperature. This not only increases the unit consumption of furnace materials but also increases the processing time, leading to disadvantageous problems such as impairing the stable operation of continuous casting in terms of molten steel supply. This invention solves the above problems and provides an efficient method for promoting decarburization during degassing in an RH degassing tank. This is based on the knowledge that the decarburization reaction is significantly accelerated and the degassing time is unexpectedly shortened by setting the blowing gas flow rate to a value that exceeds the above-mentioned saturation region of the molten steel circulation flow rate. be. The main parts of the RH vacuum processing equipment used in this experiment are shown in Figure 2. In the figure, 1 is the mounting flange to the bottom wall of the vacuum chamber with a capacity of 250 tons, and 2 is the immersion flange with an inner diameter of 450 mmφ that guides the upward flow of molten steel. The pipe, 3 is its iron core, 4 is its refractory, 5 is a narrow tube tuyere for blowing which has a diameter of 4 mm and opens at 16 places on the inner surface of the lower part of the dipping tube 2, and 6 is a tube with a diameter of 20 mm and is immersed. This is a lance for additional blowing that opens upward at the center of the bottom of the collapse tube. The inventors conducted various experiments in order to increase the efficiency of degassing by RH vacuum processing, and aimed at increasing the recirculation amount, and endeavored to confirm the effect of increasing the diameter of both the ascending and descending pipes. During the course of the experiment, we discovered the surprising fact that the surface of the blown gas bubbles generated in the riser pipe, which had been hardly seen due to their extremely low contribution as mentioned at the beginning, exhibited peculiar behavior depending on the blown gas flow rate. The focus is on In this way, the flow rate of the reflux blowing gas is set to exceed the saturated region of the molten steel reflux flow rate, and by increasing the surface of gas bubbles in the riser pipe in particular, the following improvement in decarburization performance is achieved. Ta. That is, FIG. 3 shows the amount of blowing gas for reflux and the C value reached after 15 minutes of vacuum degassing treatment.
The rising pipe has a diameter of 450mmφ as shown in the figure.
Particularly excellent decarburization effects have been shown when gas is injected at an injection rate of 2000 to 5000 Nl/min, which exceeds 1800 Nl/min, that is, beyond the saturation region of the molten steel circulation flow rate. Saturation is reached only when it reaches 5000Nl/min, which is far beyond the saturation region. This result could not have been expected based on the conventional thinking described above. For example, in the case of the normal injection rate of 1800 Nl/min for this vacuum degassing tank, the decarburization rate constant during rimmed treatment k is
0.158 min -1 , but when the injection amount exceeds the molten steel circulation flow saturation region according to the present invention at 3000 Nl/min and 5000 Nl/min, k becomes 0.203 min -1 and 0.228 min -1, respectively. , the values are about 1.3 times and over 1.4 times, respectively. According to the results shown in Figure 1, the molten steel circulation flow rate is almost the same in both cases, and if we consider that the decarburization rate from the free surface in the vacuum degassing tank is also the same, then the conventional
In the case of 1800Nl/min (reflux saturation point), if the contribution rate of only the surface of Ar bubbles in the riser pipe to the total amount of decarburization is estimated to be 30% at the conventionally known maximum, then
The contribution rate in the case of 3000Nl/min is 45.5
%, or the contribution rate in the case of 5000Nl/min is 51.5%
It also reaches. Here, the decarburization reaction in Rimdo is apparently expressed as the following first-order reaction, and this was used as the basis for the above calculation. dc/dt=-k・t c: [C] Analysis value (%) k: Apparent decarburization rate constant (min -1 ) t: Reaction time (min) Here, the decarburization rate constant is the value before treatment [C ] value, that is, the [C] value when the processing time T = 0 is expressed as C p , and the [C] value after T time is expressed as C T , and is determined by the relationship of l o C O /C T = -k・T. be able to. Thus, the relationship of the recirculation blowing gas flow rate to the above improvement in the decarburization contribution rate in the riser pipe according to the present invention is as follows:
As shown in Figure 4. In other words, it is not wasteful to inject recirculation gas that exceeds the saturation range of the molten steel recirculation flow rate, as was previously thought, but instead, according to the present invention, if the recirculation gas is increased to a large flow rate that exceeds the saturation range of the molten steel recirculation flow rate. The amount of Ar in the riser pipe is greater than previously thought.
It is thought that decarburization progresses on the bubble surface and promotes decarburization during degassing. Therefore, if the gas injection amount is determined based on the achieved C value and the gas is supplied, decarburization operation can be performed within the specified treatment time, and this gas supply amount is determined by the amount of gas in the riser pipe as described above.
Since it is assumed that the decarburization reaction occurs on the surface of Ar bubbles, it can be expressed as the relationship between the cross-sectional area inside the riser pipe and the amount of injection. Therefore, the above 3000Nl/min is approximately
1.8Nl/min・cm 2 , 5000Nl/min is approximately 3.2Nl/
A similar effect can be obtained if min·cm 2 is defined as the amount of gas blown into the riser pipe for recirculation during general RH degassing treatment. In addition, in the above example, the blowing gas for recirculation is
By blowing at about 5000Nl/min [C]
It is also possible to melt ultra-low carbon steel with a level of 10 ppm, and therefore decarburization by this invention can be achieved at a rate of 5000 Nl/min,
That is, the decarburization reaction can be promoted more effectively by setting 3.15 Nl/min·cm 2 as the upper limit of the blowing amount of the reflux blowing gas. Examples will be described below. A steel pipe tuyere 5 with an inner diameter of 4 mm and 16 holes is provided at the lower edge of the immersion pipe 2 with a diameter of 450 mmφ for blowing gas for circulation of the molten steel, and from this a steel pipe tuyere 5 with 16 holes is installed.
At 2000Nl/min, on the other hand, the inner diameter is
A lance with a refractory coating of 20 mmφ was placed, and Ar gas was pumped through it at a rate of 1000 Nl/min.
Blow at 3000Nl/min, degree of vacuum during processing is 0.5
The treatment time was 35 minutes in total, including 15 minutes for the rimmed treatment for decarburization and 20 minutes for the kill treatment for deoxidization after addition of Al. An example of experimental results under the above conditions is as follows.
【表】
この発明は上記のように、従来の考え方とし
て、環流量を増大すること、つまり環流用吹込ガ
ス流量の増加および浸漬管口径の拡大によつては
単に脱炭反応への寄与率の大部分を占める真空槽
内溶鋼自由表面の更新割合いを増大させることに
よる脱炭能の向上を目指すにすぎずこの場合現状
設備でたとえば浸漬管の口径が450mmφのときは
環流用吹込ガス流量が1800Nl／min以上で溶鋼の
環流量は一定となつて飽和量に達してしまい、真
空槽内溶鋼自由表面の増大は望まれ得なかつたと
ころにつき、とくに浸漬管内で溶鋼の上昇流を導
く吹込ガス気泡それ自体の表面における、全脱炭
素に占める脱炭寄与率の向上が、吹込みガス流量
の、溶鋼流量の飽和領域を超える増加により、有
効にもたらされることの新規知見に基いて、在来
の上記固定観念を打破して、単なる処理時間の延
長によるような不利はもちろん、それによる場合
の限界的な制限を伴うことなく、著しい脱炭能の
改善を遂げることができる。[Table] As mentioned above, the conventional concept of this invention is to increase the reflux flow rate, that is, increase the flow rate of blown gas for reflux and enlarge the immersion pipe diameter. The aim is simply to improve the decarburization ability by increasing the renewal rate of the free surface of the molten steel in the vacuum chamber, which occupies most of the area. At 1800 Nl/min or more, the recirculation flow rate of molten steel becomes constant and reaches a saturation amount, and an increase in the free surface of molten steel in the vacuum chamber is undesirable. Based on the new knowledge that the contribution of decarburization to the total decarbonization on the surface of the bubbles itself is effectively brought about by increasing the blown gas flow rate beyond the saturation region of the molten steel flow rate, Breaking away from the above-mentioned stereotypes, it is possible to achieve a significant improvement in decarburization performance without the disadvantages of simply prolonging the processing time, as well as without the limitations caused by it.
第１図は溶鋼環流量の増加に及ぼす環流用吹込
ガス流量の影響を、該吹込みに供する浸漬管の口
径に従う環流量の飽和傾向について示したグラ
フ、第２図は、この発明に従う環流用ガス吹込み
に供する浸漬管の要部断面を示した説明図、第３
図は脱炭能に及ぼす環流用吹込ガス流量の影響を
示すグラフであり、第４図はこの発明による上昇
管内脱炭寄与率の、吹込ガス流量の増加による増
強効果を示すグラフである。
Fig. 1 is a graph showing the influence of the flow rate of the reflux blowing gas on the increase in the molten steel recirculation flow rate, with respect to the saturation tendency of the recirculation flow rate according to the diameter of the immersion pipe used for the blowing. Explanatory diagram showing a cross section of the main part of the immersion pipe used for gas injection, Part 3
The figure is a graph showing the influence of the flow rate of the blowing gas for recirculation on the decarburization ability, and FIG. 4 is a graph showing the effect of increasing the decarburization contribution rate in the riser pipe according to the present invention by increasing the flow rate of the blowing gas.
Claims (1)
れら浸漬管と連通する真空槽をもつて、上記浸漬
管のうち少くとも１の浸漬管内に該溶鋼に対し事
実上不活性な気体を供給して該溶鋼の真空槽への
上昇流を導くとともに、残りの浸漬管を通して真
空槽からの下降流を導いた該真空槽内における溶
鋼の還流下に該溶鋼を連続して脱ガス処理するに
際し、溶鋼の上昇流を強いる上記気体を、上昇管
内断面積に対し1.8〜3.2Nl／min・cm2の吹込み量
で供給し、それによる溶鋼上昇流中の気泡表面に
おける脱炭反応を促進させることを特徴とする溶
鋼の真空精錬方法。 ２ 気体がアルゴンガスである特許請求の範囲第
１項に記載の溶鋼の真空精錬方法。[Scope of Claims] 1. A plurality of immersion pipes opening below the surface of a bath of molten steel and a vacuum chamber communicating with these immersion pipes, in which at least one of the immersion pipes is provided with a liquid steel that is in contact with the molten steel. The molten steel is continuously supplied with an inert gas to guide an upward flow of the molten steel into the vacuum tank, and a reflux of the molten steel in the vacuum tank by guiding a downward flow from the vacuum tank through the remaining immersion pipe. When degassing the molten steel, the gas that forces the upward flow of the molten steel is supplied at a blowing rate of 1.8 to 3.2 Nl/min・cm 2 to the cross-sectional area of the riser pipe, thereby reducing the surface of bubbles in the upward flow of the molten steel. A vacuum refining method for molten steel characterized by promoting a decarburization reaction in. 2. The vacuum refining method for molten steel according to claim 1, wherein the gas is argon gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11135681A JPS5811721A (en) | 1981-07-16 | 1981-07-16 | Vacuum refining method for molten steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11135681A JPS5811721A (en) | 1981-07-16 | 1981-07-16 | Vacuum refining method for molten steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5811721A JPS5811721A (en) | 1983-01-22 |
| JPH0368083B2 true JPH0368083B2 (en) | 1991-10-25 |
Family
ID=14559114
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11135681A Granted JPS5811721A (en) | 1981-07-16 | 1981-07-16 | Vacuum refining method for molten steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5811721A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU601602B2 (en) * | 1987-06-29 | 1990-09-13 | Kawasaki Steel Corporation | Method and apparatus for degassing molten metal utilizing RH method |
| JPS6479317A (en) * | 1987-06-29 | 1989-03-24 | Kawasaki Steel Co | Gas blowing method of reflux type degassing device |
| FR2712216B1 (en) * | 1993-11-12 | 1996-02-09 | Lorraine Laminage | Plunger of a steel vacuum decarburization treatment chamber and vacuum decarburization chamber provided with such a plunger. |
| DE19815298C2 (en) * | 1998-04-06 | 2000-05-31 | Thyssenkrupp Stahl Ag | Process for reducing the carbon content of a molten steel |
| KR100398379B1 (en) * | 1998-10-20 | 2003-12-18 | 주식회사 포스코 | A method for decarburizing steel melts in rh vaccum degassing equipment |
| JP4806863B2 (en) * | 2001-06-13 | 2011-11-02 | Ｊｆｅスチール株式会社 | Method for refining molten steel in RH vacuum degassing equipment |
| JP2007031807A (en) * | 2005-07-29 | 2007-02-08 | Jfe Steel Kk | Method for manufacturing ultra-low carbon steel |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS525614A (en) * | 1975-07-02 | 1977-01-17 | Kawasaki Steel Corp | Production process of steel of extremely low carbocontent |
| JPS54118318A (en) * | 1978-03-07 | 1979-09-13 | Daido Steel Co Ltd | Ricirculating type vacuum degassing method of molten steel |
-
1981
- 1981-07-16 JP JP11135681A patent/JPS5811721A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS525614A (en) * | 1975-07-02 | 1977-01-17 | Kawasaki Steel Corp | Production process of steel of extremely low carbocontent |
| JPS54118318A (en) * | 1978-03-07 | 1979-09-13 | Daido Steel Co Ltd | Ricirculating type vacuum degassing method of molten steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5811721A (en) | 1983-01-22 |
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