JPS6358668B2 - - Google Patents
Info
- Publication number
- JPS6358668B2 JPS6358668B2 JP60095899A JP9589985A JPS6358668B2 JP S6358668 B2 JPS6358668 B2 JP S6358668B2 JP 60095899 A JP60095899 A JP 60095899A JP 9589985 A JP9589985 A JP 9589985A JP S6358668 B2 JPS6358668 B2 JP S6358668B2
- Authority
- JP
- Japan
- Prior art keywords
- nozzle
- gas
- steel
- inert gas
- flow rate
- 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
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- 229910000831 Steel Inorganic materials 0.000 claims description 35
- 239000010959 steel Substances 0.000 claims description 35
- 239000007789 gas Substances 0.000 claims description 28
- 239000011261 inert gas Substances 0.000 claims description 19
- 238000007654 immersion Methods 0.000 claims description 18
- 238000005266 casting Methods 0.000 claims description 9
- 238000009749 continuous casting Methods 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 7
- 238000002347 injection Methods 0.000 claims description 6
- 239000007924 injection Substances 0.000 claims description 6
- 239000000843 powder Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000007664 blowing Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 229910052786 argon Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 239000010953 base metal Substances 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000006249 magnetic particle Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Landscapes
- Continuous Casting (AREA)
Description
【発明の詳細な説明】
産業上の利用分野
本発明は連続鋳造による介在物レベルの極めて
低い清浄鋼、たとえば缶用鋼やシヤドウマスク用
鋼などの製造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 manufacturing clean steel with extremely low inclusion levels, such as steel for cans and steel for shadow masks, by continuous casting.
以下、便宜上、缶用鋼を例に挙げて説明する。 Hereinafter, for convenience, steel for cans will be described as an example.
従来の技術
連続鋳造法による缶用鋼の製造においては、タ
ンデイツシユ等の中間容器から浸漬ノズルを介し
てモールド内へ溶鋼を注入している。この場合、
溶鋼中のアルミナがノズル内面へ付着堆積し、ノ
ズルを詰らせ、その結果甚しい場合には屡々鋳造
を中断せざるを得なくなる。BACKGROUND ART In manufacturing can steel by continuous casting, molten steel is injected into a mold from an intermediate container such as a tundish through a submerged nozzle. in this case,
Alumina in the molten steel adheres and accumulates on the inner surface of the nozzle, clogging the nozzle, and as a result, in severe cases, casting must often be interrupted.
また、缶用鋼は、製缶工程において、厳しい加
工を強いられるため、100μｍ〜500μｍといつた
粗大介在物のみならず、50μｍ程度の微細な介在
物までも品質欠陥の原因となる。かかる問題に対
し、従来は、たとえば特開昭49−87527号公報に
示されるように、浸漬ノズルより溶鋼中へ５〜
250／ｔ−鋼の不活性ガスを吹込み注入溶鋼と
ともにモールド内へ注入し、モールド内で介在物
の浮上除去を促進する方法が提案されている。し
かし、かかる手法によつてはスラグ系および脱酸
生成物であるアルミナ系の介在物浮上除去の促進
ははかられるものの、吹込みガス流量が多すぎる
と、ガスの微細化がはかられず、粗大なガス気泡
のままモールド内溶鋼湯面上に浮上し、溶鋼上に
存在する溶融パウダー中で気泡が破裂し、その
際、溶融パウダーの一部を溶鋼中に懸濁せしめ、
懸濁した溶融パウダーが介在物となり、製品品質
の悪化をまねいている。 Moreover, since steel for cans is forced to undergo severe processing in the can manufacturing process, not only coarse inclusions of 100 μm to 500 μm, but also fine inclusions of about 50 μm cause quality defects. To solve this problem, conventionally, as shown in Japanese Unexamined Patent Publication No. 49-87527, 5 to
A method has been proposed in which an inert gas for 250/t-steel is injected into the mold together with the molten steel to promote floating and removal of inclusions within the mold. However, although this method can promote the floating removal of slag-based and alumina-based inclusions that are deoxidized products, if the blown gas flow rate is too large, the gas cannot be made finer. Coarse gas bubbles float above the surface of the molten steel in the mold, and the bubbles burst in the molten powder present on the molten steel, at which time a part of the molten powder is suspended in the molten steel,
Suspended molten powder becomes inclusions, leading to deterioration of product quality.
発明が解決しようとする問題点
本発明は従来技術の上記問題点を解消するもの
で、粗大ガス気泡によるパウダー巻き込みを防止
し、浸漬ノズルのノズル詰まりを防止し、微細介
在物の浮上除去の促進をはかることにより、缶用
鋼を鋳造歩留よく製造することを目的とする。Problems to be Solved by the Invention The present invention solves the above-mentioned problems of the prior art. It prevents powder entrainment by coarse gas bubbles, prevents nozzle clogging of submerged nozzles, and promotes floating removal of fine inclusions. The purpose is to manufacture steel for cans with a good casting yield by measuring the following.
問題点を解決するための手段
本発明は連続鋳造用浸漬２孔ノズルの筒状耐火
物内面より不活性ガスを均一に微細気泡として噴
出させるに際し、不活性ガスの噴出量を次式(1)を
満足するように、操業条件に合わせ、制御するこ
とを特徴とする溶鋼の連続鋳造方法である。Means for Solving the Problems In the present invention, when injecting inert gas uniformly as fine bubbles from the inner surface of a cylindrical refractory of a two-hole immersed nozzle for continuous casting, the amount of inert gas ejected is expressed by the following formula (1). This is a continuous casting method for molten steel that is characterized by being controlled according to the operating conditions so as to satisfy the following.
3.7×10-5DL≦QG≦4d-1/4Ql4/3 …(1)
（ただし、QGは吹込みガス量（Ｎ／min）、
Ｄは浸漬ノズル内径（mm）、ｄは浸漬ノズル吐出
口径（mm）、Ｌはガス吹込み用ノズル内スリツト
長さ（mm）、Qlは鋳造量（ｔ／min）を表わす。）
作 用
以下に図面に基づき本発明を説明する。3.7×10 -5 DL≦Q G ≦4d -1/4 Ql 4/3 …(1) (However, Q G is the amount of blown gas (N/min),
D is the inner diameter of the immersion nozzle (mm), d is the diameter of the outlet of the immersion nozzle (mm), L is the length of the slit in the gas injection nozzle (mm), and Ql is the casting amount (t/min). ) Effect The present invention will be explained below based on the drawings.
第１図は本発明の実施例を示す説明図、第２図
は不活性ガスの適正吹込流量と操業条件との関係
を示す説明図、第３図は本発明の効果を示す説明
図である。 Fig. 1 is an explanatory diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the relationship between the appropriate flow rate of inert gas blowing and operating conditions, and Fig. 3 is an explanatory diagram showing the effects of the present invention. .
第１図において、１は浸漬ノズル、２はガス吹
込み用管、３は浸漬ノズル内スリツト状間隙、４
はタンデイツシユ底部、５はストツパー、６はモ
ールド、７は鋳片、８はパウダー、９は微細気
泡、１０は粗大な気泡を示す。 In FIG. 1, 1 is an immersion nozzle, 2 is a gas blowing pipe, 3 is a slit-shaped gap in the immersion nozzle, and 4
5 indicates the bottom of the tundish, 5 indicates the stopper, 6 indicates the mold, 7 indicates the slab, 8 indicates the powder, 9 indicates the fine bubbles, and 10 indicates the coarse bubbles.
第１図は中心線で左右に区切り、左半分は吹込
みガス量が適正で、ガスの微細化の良好な状態を
示しているのに対し、右半分はガス吹込みガス量
が過多であり、ガスの微細化が不充分である状態
を示す図である。 Figure 1 is divided into left and right parts along the center line, and the left half shows that the amount of gas blown is appropriate and the gas is finely refined, whereas the right half shows that the amount of gas blown is excessive. , is a diagram showing a state in which the gas is insufficiently refined.
第１図に示すように、連続鋳造工程において
は、溶鋼がタンデイツシユから浸漬ノズルを介し
て、鋳型内へ導かれるが、浸漬ノズル１の内面に
アルミナや地金が付着、堆積し、ノズル閉塞する
のを防ぎ、かつ、モールド内での溶鋼中の介在物
の浮上除去を促進するため、ガスの供給管２より
浸漬ノズル１の内部に設けられたスリツトを介し
て、浸漬ノズル１の内面より不活性ガスを均一に
吹き込むことがよく行なわれている。 As shown in Fig. 1, in the continuous casting process, molten steel is guided from the tundish through the immersion nozzle into the mold, but alumina and base metal adhere and accumulate on the inner surface of the immersion nozzle 1, causing the nozzle to become clogged. In order to prevent this and promote the floating removal of inclusions in the molten steel in the mold, the gas is supplied from the inner surface of the immersion nozzle 1 through a slit provided inside the immersion nozzle 1 from the gas supply pipe 2. It is common practice to blow active gas uniformly.
この場合、不活性ガスの流量が多すぎる場合に
は、ノズル内に数μの大きさで吹き込まれた不活
性ガスが、ノズル吐出口部で数十mmの大きさま
で、合体粗大化し、浸漬ノズル１の吐出口より不
活性ガスが粗大気泡のまま吐出され、浸漬ノズル
近傍で急浮上し、溶鋼湯面で該粗大不活性ガス気
泡が破裂する。 In this case, if the flow rate of the inert gas is too large, the inert gas blown into the nozzle with a size of several micrometers will coalesce and become coarse at the nozzle outlet, up to a size of several tens of millimeters, and the immersion nozzle The inert gas is discharged from the discharge port 1 in the form of coarse bubbles, which suddenly rise to the surface near the immersion nozzle, and the coarse inert gas bubbles burst on the surface of the molten steel.
その際に、溶鋼湯面上に存在する溶融パウダー
８を溶鋼中に巻き込む。また、不活性ガス流量が
少なすぎる場合には、浸漬ノズルの閉塞防止効果
が不充分であるため、ノズル詰まり問題が顕在化
する。 At this time, the molten powder 8 present on the surface of the molten steel is drawn into the molten steel. Furthermore, if the inert gas flow rate is too low, the effect of preventing blockage of the submerged nozzle is insufficient, and the problem of nozzle clogging becomes apparent.
従つて、浸漬ノズルの内面より不活性ガスを吹
き込む際には、その流量が鋼の品質面、又操業安
定性からある範囲内に限定されるべきことは明白
である。本発明者らは種々の調査、実験より、か
かる不活性ガスの吹込流量の適正範囲は次式(1)で
整理されることを知得した。 Therefore, when inert gas is blown into the inner surface of the submerged nozzle, it is clear that the flow rate should be limited within a certain range from the standpoint of steel quality and operational stability. Through various investigations and experiments, the present inventors have learned that the appropriate range of the inert gas blowing flow rate is expressed by the following equation (1).
3.7×10-5DL≦QG≦4d-1/4Ql4/3 …(1)
（ただし、QGは吹込みガス量（Ｎ／min）、
Ｄは浸漬ノズル内径（mm）、ｄは浸漬ノズル吐出
口径（mm）、Ｌはガス吹込み用ノズル内スリツト
長さ（mm）、Qlは鋳造量（ｔ／min）を表わす。）
なお、ここで使用する不活性ガスとしては特に
限定するものではないがArガスがコストの点か
ら通常有利に使用される。3.7×10 -5 DL≦Q G ≦4d -1/4 Ql 4/3 …(1) (However, Q G is the amount of blown gas (N/min),
D is the inner diameter of the immersion nozzle (mm), d is the diameter of the outlet of the immersion nozzle (mm), L is the length of the slit in the gas injection nozzle (mm), and Ql is the casting amount (t/min). Note that the inert gas used here is not particularly limited, but Ar gas is usually advantageously used from the viewpoint of cost.
次に、ノズルの吐出口径ｄが50mmφ、70mmφ、
100mmφの場合のガス流量の最適範囲を、溶鋼流
量Qlとガス吹込み流量QGの関係を第２図に例示
する。 Next, the nozzle discharge opening diameter d is 50mmφ, 70mmφ,
The optimal range of gas flow rate in the case of 100 mmφ is illustrated in Fig. 2, which shows the relationship between molten steel flow rate Ql and gas injection flow rate QG .
浸漬ノズル内面から微細に吹き込まれた不活性
ガスは浸漬ノズル吐出口部の流れの状態によつ
て、合体粗大化するか、微細分散するか変化す
る。従つて、合体粗大化する限界のガス流量は吐
出口径ｄと、溶鋼流量Ql（ｔ／min）で決定され、
ノズルの内径Ｄやノズル内面積にはほとんど依存
しない。 The inert gas finely blown from the inner surface of the immersed nozzle changes depending on the flow condition at the outlet of the immersed nozzle, whether it coalesces and becomes coarse or becomes finely dispersed. Therefore, the limit gas flow rate for coalescence and coarsening is determined by the discharge port diameter d and the molten steel flow rate Ql (t/min),
It hardly depends on the inner diameter D of the nozzle or the inner area of the nozzle.
即ち、QGが4d-1/4Ql4/3以上になると、粗大気泡
となり、該粗大気泡が溶鋼湯面上で破裂する際
に、溶鋼湯面上に存在する溶融パウダーを溶鋼中
に巻き込み、品質悪化を招くので好ましくない。 That is, when Q G becomes 4d -1/4 Ql 4/3 or more, coarse bubbles form, and when the coarse bubbles burst on the surface of the molten steel, they entrain the molten powder present on the surface of the molten steel into the molten steel. , which is not preferable because it causes quality deterioration.
一方、QGの下限流量はノズル詰まり防止の観
点から決定されるべきである。ノズルの内面よ
り、不活性ガスを吹込むことにより、ノズル内面
と溶鋼との界面にガス層を形成し、ノズル詰まり
を防止できる。本発明者らは種々検討した結果、
単位面積当たりの必要流量が1.18×10-5（／
min・mm2）であることを知得した。従つて、ノズ
ルの内径をＤ、ガス吹込み用スリツト状間隙の長
さをＬとすると、ノズル詰まりを防止するための
必要最低ガス吹込み流量は3.7×10-5DL／min
となる。つまり、QGが3.7×10-5DL未満である
と、浸漬ノズルの閉塞を防止できず、操業の安定
性を著しく阻害するので、好ましくない。従つ
て、本発明はQGの適正範囲として、
3.7×10-5DL≦QG＜4d-1/4Ql4/3
を確立した。 On the other hand, the lower limit flow rate of Q G should be determined from the viewpoint of preventing nozzle clogging. By blowing inert gas through the inner surface of the nozzle, a gas layer is formed at the interface between the inner surface of the nozzle and the molten steel, thereby preventing nozzle clogging. As a result of various studies by the present inventors,
The required flow rate per unit area is 1.18×10 -5 (/
min・mm 2 ). Therefore, if the inner diameter of the nozzle is D and the length of the slit-shaped gap for gas injection is L, the minimum required gas injection flow rate to prevent nozzle clogging is 3.7×10 -5 DL/min.
becomes. In other words, if Q G is less than 3.7×10 −5 DL, clogging of the immersion nozzle cannot be prevented, which significantly impedes operational stability, which is not preferable. Therefore, the present invention has established 3.7×10 −5 DL≦Q G <4d −1/4 Ql 4/3 as the appropriate range of Q G .
以下実施例を挙げて説明する。 This will be explained below with reference to examples.
実施例
スラブ幅1820mm、スラブ厚250mm、鋳造速度
1m／min、鋳造量3.2t／minという缶用鋼の鋳造
条件に本発明を適用すると、ノズル内径90mmφ、
ノズルの吐出口径が70mmφ、スリツト長さ300mm
の場合には、吹込みアルゴンガスの適正流量は次
式のようになる。Example Slab width 1820mm, slab thickness 250mm, casting speed
When the present invention is applied to can steel casting conditions of 1m/min and casting amount of 3.2t/min, the nozzle inner diameter is 90mmφ,
Nozzle outlet diameter is 70mmφ, slit length is 300mm
In this case, the appropriate flow rate of blown argon gas is as follows.
１＜QG＜6.7／min
かかる知見に基づき、アルゴンガス流量を５
／minにし、鋳造したところ、ノズル詰まりも
発生せず、かつ、非金属介在物の低減を図ること
ができ、高清浄の缶用鋼を安定して鋳造できた。 1＜Q G ＜6.7/min Based on this knowledge, the argon gas flow rate was set to 5.
/min, no nozzle clogging occurred, nonmetallic inclusions were reduced, and highly clean steel for cans could be stably cast.
発明の効果
第３図に示すように、連続鋳造によつて製造し
た缶用鋼の品質を磁粉探傷で調査したところ、不
活性ガスを15N／min（5N／ｔ−鋼）吹き込
んでいた従来法に比べ、不活性ガス流量を適正化
し、5N／min吹き込んだ本発明法によると、
欠陥発生率が半減し、高品質の缶用鋼を鋳造歩留
よく、安定して製造できるようになつた。Effects of the invention As shown in Figure 3, when the quality of can steel manufactured by continuous casting was investigated by magnetic particle testing, it was found that the conventional method of injecting inert gas at 15N/min (5N/t-steel) Compared to the above, according to the method of the present invention, in which the inert gas flow rate was optimized and 5N/min was injected,
The defect rate has been halved, and high-quality steel for cans can now be manufactured stably with good casting yields.
なお、本説明においては缶用鋼を例に挙げて詳
述してきたが、基本的には本発明は介在物の要求
レベルの厳しい鋼種の製造に適用でき、かつ、該
鋼種の製造に本発明を適用することによつて、缶
用鋼の場合と同様な効果が得られる。 In this explanation, steel for cans has been described in detail as an example, but basically the present invention can be applied to the production of steel types with strict requirements for inclusions, and the present invention can be applied to the production of steel types with strict requirements for inclusions. By applying this, the same effect as in the case of can steel can be obtained.
第１図は本発明の実施例を説明する立面図、第
２図は不活性ガスの適正吹込流量と操業条件との
関係を示す説明図、第３図は本発明の効果を示す
説明図である。
１……浸漬ノズル、２……ガス吹込み管、３…
…浸漬ノズル内スリツト状間隙、４……タンデイ
ツシユ底部、５……ストツパー、６……モール
ド、７……鋳片、８……パウダー、９……微細気
泡、１０……粗大な気泡。
FIG. 1 is an elevational view explaining an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the relationship between the appropriate flow rate of inert gas and operating conditions, and FIG. 3 is an explanatory diagram showing the effects of the present invention. It is. 1...Immersion nozzle, 2...Gas blowing pipe, 3...
...Slit-like gap in the immersion nozzle, 4...Tundish bottom, 5...Stopper, 6...Mold, 7...Slab, 8...Powder, 9...Fine bubbles, 10...Coarse bubbles.
Claims (1)
より不活性ガスを均一に微細気泡として噴出させ
るに際し、不活性ガスの噴出量を次式(1)を満足す
るように操業条件に合わせ制御することを特徴と
する溶鋼の連続鋳造方法。 3.7×10-5DL≦QG≦4d-1/4Ql4/3 …(1) （ただし、QGは吹込みガス量（Ｎ／min）、
Ｄは浸漬ノズル内径（mm）、ｄは浸漬ノズル吐出
口径（mm）、Ｌはガス吹込み用ノズル内スリツト
長さ（mm）、Qlは鋳造量（ｔ／min）を表わす。）[Claims] 1. When injecting inert gas uniformly as fine bubbles from the inner surface of a cylindrical refractory of a two-hole immersion nozzle for continuous casting, the amount of inert gas ejected is set to satisfy the following formula (1). A continuous casting method for molten steel, which is characterized by control according to operating conditions. 3.7×10 -5 DL≦Q G ≦4d -1/4 Ql 4/3 …(1) (However, Q G is the amount of blown gas (N/min),
D is the inner diameter of the immersion nozzle (mm), d is the diameter of the outlet of the immersion nozzle (mm), L is the length of the slit in the gas injection nozzle (mm), and Ql is the casting amount (t/min). )
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9589985A JPS61255751A (en) | 1985-05-08 | 1985-05-08 | Continuous casting method for molten steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9589985A JPS61255751A (en) | 1985-05-08 | 1985-05-08 | Continuous casting method for molten steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61255751A JPS61255751A (en) | 1986-11-13 |
| JPS6358668B2 true JPS6358668B2 (en) | 1988-11-16 |
Family
ID=14150145
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9589985A Granted JPS61255751A (en) | 1985-05-08 | 1985-05-08 | Continuous casting method for molten steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61255751A (en) |
-
1985
- 1985-05-08 JP JP9589985A patent/JPS61255751A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61255751A (en) | 1986-11-13 |
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