JPH0324296B2 - - Google Patents
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- Publication number
- JPH0324296B2 JPH0324296B2 JP17595185A JP17595185A JPH0324296B2 JP H0324296 B2 JPH0324296 B2 JP H0324296B2 JP 17595185 A JP17595185 A JP 17595185A JP 17595185 A JP17595185 A JP 17595185A JP H0324296 B2 JPH0324296 B2 JP H0324296B2
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- steel
- gas
- per ton
- cold
- 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 48
- 239000010959 steel Substances 0.000 claims description 48
- 238000007654 immersion Methods 0.000 claims description 16
- 230000007547 defect Effects 0.000 claims description 14
- 238000000137 annealing Methods 0.000 claims description 13
- 238000002347 injection Methods 0.000 claims description 13
- 239000007924 injection Substances 0.000 claims description 13
- 238000009749 continuous casting Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 8
- 238000005097 cold rolling Methods 0.000 claims description 7
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 6
- 238000005098 hot rolling Methods 0.000 claims description 6
- 238000001556 precipitation Methods 0.000 claims description 6
- 230000005587 bubbling Effects 0.000 description 6
- 229910000655 Killed steel Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000005266 casting Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- RQMIWLMVTCKXAQ-UHFFFAOYSA-N [AlH3].[C] Chemical compound [AlH3].[C] RQMIWLMVTCKXAQ-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
Description
【発明の詳細な説明】
（産業上の利用分野）
低炭素鋼冷延薄板は、一般に連続鋳造スラブに
熱間圧延と、冷間圧延を施したのち焼鈍を経て製
品とされるがこの焼鈍の際板面に、しばしば、幅
１〜４mm、長さ10〜60mmにもわたつて隆起した、
いわゆるふくれ欠陥を生じることがあり、鋼中Ｃ
含有量が0.015wt％以下の極低炭素鋼の場合にと
りわけ多発し勝ちであつて、製品歩留りの大幅低
下を招く。主要な原因に数えられる。[Detailed Description of the Invention] (Industrial Application Field) Low carbon steel cold-rolled thin sheets are generally made into products by subjecting continuously cast slabs to hot rolling and cold rolling, and then annealing. On the edge of the board, there is often a bulge measuring 1 to 4 mm in width and 10 to 60 mm in length.
So-called bulge defects may occur, and C in steel
This is especially common in ultra-low carbon steels with a content of 0.015wt% or less, resulting in a significant reduction in product yield. It is considered one of the major causes.
この種の鋼板は、溶鋼２次精練に関する目覚ま
しい発展、特に脱ガス技術の著しい進歩の結果、
非金属介在物の少ない、清浄鋼として極低炭素
Alキルド鋼の連続鋳造が可能になつたことから、
上記のように連続鋳造スラブを出発材としてつく
られるが、熱間圧延さらには冷間圧延を経た焼鈍
のあとに発生するふくれ欠陥は、多段にわたる加
工工程の手順を踏んだ最終工程に近いところか
ら、その歩留り低下が製鋼コストに及ぼす影響
は、ゆるがせにできない。 This type of steel plate has been developed as a result of remarkable developments in secondary smelting of molten steel, especially in degassing technology.
Extremely low carbon as a clean steel with few non-metallic inclusions
Since continuous casting of Al-killed steel became possible,
As mentioned above, continuous casting slabs are used as the starting material, but blistering defects that occur after hot rolling or even cold rolling and annealing occur near the final step of the multi-step processing process. , the impact of this reduction in yield on steel manufacturing costs cannot be ignored.
焼鈍時ふくれ欠陥の防止に関連してこの明細書
には、連続鋳造段階にまで遡つた原因の究明に由
来する開発研究の成果をここに提案するものであ
る。 In connection with the prevention of blistering defects during annealing, this specification proposes the results of research and development derived from the investigation of the causes that date back to the continuous casting stage.
（従来の技術）
一般にAlキルド鋼の連続鋳造の際には、タン
デイシユからモールドに至る溶鋼の移注のため、
タンテイシユに配備した、上ノズル、スライデイ
ングプレート、下ノズル及びモールド内浸漬管よ
り成るを例とする、いわゆる浸漬ノズルが用いら
れ、この浸漬ノズルには、その内面で、溶鋼移注
の反覆が度重なるにつれ、鋼中介在物とくに
Al2O3の析出によるノズル閉塞を回避するよう
に、溶鋼注入流に向かう多量のArガスの放散が
行われる例としている。(Prior art) Generally, during continuous casting of Al-killed steel, in order to transfer the molten steel from the tundish to the mold,
A so-called immersion nozzle is used, for example, consisting of an upper nozzle, a sliding plate, a lower nozzle, and an immersion tube in the mold, which are arranged in a tangent. As they overlap, inclusions in the steel, especially
This is an example in which a large amount of Ar gas is diffused toward the molten steel injection flow to avoid nozzle clogging due to Al 2 O 3 precipitation.
このArガスは、大部分浸漬ノズル中で溶鋼注
入流に逆からつて浮上するが、一部は溶鋼注入流
に巻込み帯同されて、モールド内溶鋼中に浸入
し、その大部分はAr気泡として浮上し、モール
ド内パウダ層内に吸収されるが、鋳片凝固殻に捕
捉されるものもある。 Most of this Ar gas flows against the molten steel injection flow in the immersion nozzle and rises to the surface, but some of it is entrained by the molten steel injection flow and enters the molten steel in the mold, and most of it forms Ar bubbles. Some of it floats up and is absorbed into the powder layer in the mold, but some of it is trapped in the solidified slab shell.
このAr気泡は熱間圧延を経たのちも鋼中で気
泡のまま残り易く、とくに気泡中に微細なAl2O3
の如き鋼中介在物を多く捕捉しているためにも圧
着が妨げられる。 These Ar bubbles tend to remain as bubbles in the steel even after hot rolling, and especially fine Al 2 O 3 in the bubbles.
Crimp bonding is also hindered because many inclusions in the steel are trapped.
冷間圧延に際して、このような未圧着気泡の内
圧が増加し、その後の焼鈍による軟化とともに薄
板表面を局部隆起に至らせるのであり、また未圧
着気泡に捕捉された硬いAl2O3に比しより軟いマ
トリツクスは冷間圧延に伴う伸びがより大きいた
めに両者の境界に形成されるボイドも含めて、焼
鈍雰囲気に用いられるAxガス中のH2溶解度の低
下による、浸入H2分圧の上昇もまた、ふくれ欠
陥を助長する。 During cold rolling, the internal pressure of these unpressed air bubbles increases, and as the sheet becomes softer due to subsequent annealing, the surface of the thin sheet becomes locally bulged . The softer matrix has a higher elongation due to cold rolling, including voids formed at the interface between the two , and a lower H2 solubility in the Ax gas used in the annealing atmosphere. Elevation also promotes blistering defects.
（発明が解決しようとする問題点）
極低炭素Alキルド鋼冷延板にしばしば発生し
たふくれ欠陥について調査を行つた結果、上記の
ようにその殆どが、Arガス気泡に由来すること
の究明結果に基づいて、浸漬ノズルにおけるガス
放散量の低減を試みたところ、こんどはノズル閉
塞の防止に支障となるうれいがある。(Problems to be Solved by the Invention) As a result of investigating the blistering defects that often occur in ultra-low carbon Al-killed cold-rolled steel sheets, it was found that most of the blistering defects were caused by Ar gas bubbles as described above. Based on this, attempts were made to reduce the amount of gas dissipated in the submerged nozzle, but this resulted in a hindrance to preventing nozzle clogging.
そこでこの発明は、ノズル塞りの回避に必要な
ガス放散量を充分に確保した上で上述の如きふく
れ欠陥を伴うことのない、極低炭素鋼冷延薄板向
けスラブの連続鋳造方法を確立することを、目的
とするものである。 Therefore, this invention establishes a method for continuous casting of slabs for cold-rolled thin sheets of ultra-low carbon steel, which ensures a sufficient amount of gas dissipation necessary to avoid nozzle clogging and is free from the above-mentioned blistering defects. This is the purpose of the project.
（問題点を解決するための手段）
この発明は熱間圧延と、冷間圧延及び焼鈍各工
程を経て極低炭素鋼冷延薄板に仕向けるスラブの
連続鋳造に当たり、モールド内への溶鋼注入を司
る浸漬ノズルの内面にて、その面上における鋼中
介在物の析出を回避すべく溶鋼トン当たり4N
をこえる充分な量にて溶鋼注入流に向かうガス放
散を行う際、溶鋼トン当たり4N以下に制限し
たArと、同じく10N以下に制限した残余量の
N2との混合ガスを用い、スラブ鋳片の内部に捕
捉されるガス気泡に基づく１mmφ以上のピンホー
ル数をトン当たり10こ以内に低減させることを特
徴とする、焼鈍時ふくれ欠陥を伴わぬ極低炭素鋼
冷延薄板向けスラブの連続鋳造方法である。(Means for Solving the Problems) This invention controls the injection of molten steel into the mold in continuous casting of slabs to be made into ultra-low carbon steel cold-rolled sheets through hot rolling, cold rolling and annealing processes. 4N per ton of molten steel on the inner surface of the immersion nozzle to avoid precipitation of inclusions in the steel on that surface.
When dissipating gas toward the molten steel injection stream in a sufficient amount exceeding
Using a mixed gas with N2 , the number of pinholes of 1mmφ or more due to gas bubbles trapped inside the slab slab is reduced to within 10 pinholes per ton.It is free from blistering defects during annealing. This is a continuous casting method for cold-rolled thin sheets of ultra-low carbon steel.
ここにガス容積についての単位「Ｎ」は標準
状態における体積である。 Here, the unit "N" for gas volume is the volume under standard conditions.
この発明に従い、浸漬ノズル内面における介在
物の析出堆積を回避するため溶鋼トン当り4N
をこえる充分な量でのガス放散にAr−N2混合ガ
スを、とくにAr流量につき溶鋼トン当たり4N
以下の制限下に用いると、ふくれ欠陥発生のひき
がねとなる、上記の未圧着Ar気泡が激減し、し
かも介在物の析出によるノズル塞りの防止に何ら
の支障も生じない。 According to this invention, in order to avoid precipitation and accumulation of inclusions on the inner surface of the immersion nozzle, 4N per ton of molten steel is applied.
Ar- N2 mixed gas is used for gas dissipation in a sufficient amount exceeding
When used under the following limitations, the unbonded Ar bubbles described above, which are a trigger for the occurrence of bulging defects, are drastically reduced, and there is no problem in preventing nozzle clogging due to precipitation of inclusions.
それというのは、混合ガス中のN2は溶鋼に可
溶であつて鋳片内部に未圧着気泡を生成しない
が、浸漬ノズル内面でのガス吹き込みによるバブ
リング作用は、Arの場合と同様にノズル内面に
対する清掃効果をもたらすのに充分役立つからで
あり、その上、鋼中へのN2溶解による鋼中Ｎの
ピツクアツプも、についてはあとで述べるように
溶鋼トン当たり10N以下に制限することにより
上記のArとの混合の下で、事実上、無視され得
る。 This is because N 2 in the mixed gas is soluble in molten steel and does not generate unbonded bubbles inside the slab, but the bubbling effect caused by gas injection on the inner surface of the immersion nozzle is similar to the case of Ar. This is because it is sufficiently useful to bring about a cleaning effect on the inner surface, and in addition, the pick-up of N in steel due to N2 dissolution into steel is also limited to 10N or less per ton of molten steel as described later. Under mixing with Ar, it can be virtually ignored.
さて第１図にＣ：0.002重量％、Si：0.01重量
％、Mn：0.1重量％、Al：0.035重量％、Ｐ：0.01
重量％、Ｓ：0.005重量％の組成になる極低炭素
Alキルド鋼を、厚み220mm、幅1500mmのスラブに
連続鋳造する際に、タンデツシユとモールドを連
ねる、浸漬ノズルの内面にて溶鋼の注入流に向か
うArガス流の放散量が、ノズル塞り傾向に及ぼ
す影響についての調査結果の一例を実線で図示し
たように、Arガス放散量が溶鋼トン当たり、4N
程度以下になると、ノズル塞りが多発する。 Now, Figure 1 shows C: 0.002% by weight, Si: 0.01% by weight, Mn: 0.1% by weight, Al: 0.035% by weight, P: 0.01.
Weight%, S: Extremely low carbon with a composition of 0.005% by weight
When continuously casting Al-killed steel into slabs with a thickness of 220 mm and a width of 1500 mm, the amount of Ar gas dissipated toward the molten steel injection flow on the inner surface of the immersion nozzle that connects the tundish and the mold tends to clog the nozzle. As shown by the solid line, an example of the research results on the influence of
Below this level, nozzle clogging occurs frequently.
ここに第１図の縦軸に示したノズル塞り指数
は、ノズルの閉塞を来し溶鋼注入が頓挫する状態
を指数５とし、それに至る溶鋼注入流の塞流の段
階を５区分して、それぞれ指数として４以下の値
で示してある。 Here, the nozzle clogging index shown on the vertical axis of Fig. 1 has an index of 5 when the nozzle is clogged and molten steel injection is stalled, and the stages of molten steel injection flow clogging that lead to this are divided into 5 categories. Each index is shown as a value of 4 or less.
従つて従来の浸漬ノズルに対するArガスバブ
リングにあつては、溶鋼トン当たり、4Nをこ
れる量でArガス放散が実行されていたのである。 Therefore, in conventional Ar gas bubbling with a submerged nozzle, Ar gas was diffused in an amount of less than 4N per ton of molten steel.
これに対しArガスの放散量が、連続鋳造スラ
ブの鋳片内における１mmφ以上のピンホールの発
生個数に及ぼす影響について第２図に、またこの
ピンホールの発生個数と、焼鈍後の冷延薄板表面
に現出するふくれ発生との関係を第３図に、それ
ぞれ示し、それらの結果をまとめて、吹込みAr
ガス量がふくれ発生におらぼす影響を第４図であ
らわした。 On the other hand, Fig. 2 shows the influence of the amount of Ar gas dissipated on the number of pinholes of 1 mmφ or more in the slab of a continuously cast slab. Figure 3 shows the relationship between the occurrence of blistering that appears on the surface, and summarizes the results.
Figure 4 shows the effect of gas amount on blistering.
ここにArガスの放散量が、浸漬ノズルの閉塞
防止に必要な、溶鋼トン当たり4Nをこえると
きには、ふくれ発生が避け得ないのは、もはや明
らかである。 It is clear that when the amount of Ar gas released exceeds 4N per ton of molten steel, which is necessary to prevent the immersion nozzle from clogging, blistering is unavoidable.
なお第５図にモールドへの移注を行いつつある
間における溶鋼の流動のありさまを、Arガスの
放散挙動にあわせ図解した。 Fig. 5 illustrates the flow of molten steel while it is being poured into a mold, along with the dissipation behavior of Ar gas.
図においては１は浸漬ノズル、２はモールド、
３は凝固過程の溶鋼、４はパウダ層、５は凝固
殻、６は連続鋳造機のフツトロールである。 In the figure, 1 is an immersion nozzle, 2 is a mold,
3 is molten steel in the solidification process, 4 is a powder layer, 5 is a solidified shell, and 6 is a foot roll of a continuous casting machine.
浸漬ノズル１は、通常タンデツシユ（図示略）
と一体をなす上ノズルａと、注入流の閉止、流入
を司るスライデイングプレートｂ、下ノズルｃ、
そして浸漬管ｄより成る。 The immersion nozzle 1 is usually a tundish (not shown).
an upper nozzle a that is integrated with the upper nozzle a, a sliding plate b that controls the closing and inflow of the injection flow, a lower nozzle c,
It consists of a dipping tube d.
上ノズルａ、スライデイングプレートｂ、下ノ
ズルｃおよび浸漬管ｄの内面にてArガスの放散
を、たとえばポーラスれんがの孔隙を通してて行
い、それぞれの区分放散量をQ1，Q2……Q4にて
示し、それらの合計放散量Ｑを、第２および４図
で横軸にとつた。 Ar gas is diffused on the inner surfaces of the upper nozzle a, sliding plate b, lower nozzle c, and immersion tube d, for example through the pores of porous bricks, and the respective sectional emission amounts are Q 1 , Q 2 ...Q 4 The total amount of radiation Q is plotted on the horizontal axis in FIGS. 2 and 4.
第５図において７は溶鋼注入流に巻込んで帯同
したAr気泡、８は凝固殻５に捕捉されたAr気泡
であり、これが、スラブ鋳片の内部ピンホールを
形成する。 In FIG. 5, reference numeral 7 indicates an Ar bubble entrained in the molten steel injection flow, and reference numeral 8 indicates an Ar bubble trapped in the solidified shell 5, which forms an internal pinhole in the slab slab.
第２図と第３図を参照してスラブ鋳片の内部に
Ar気泡が捕捉されることによるピンホール個数
が、溶鋼トン当たり10こ以内に抑制される吹込み
Arガス量、つまり溶鋼トン当たり4N以下に制
限した放散量の下では焼鈍後の冷延薄板表面のふ
くれ発生が、事実上回避され得るわけであるが、
単にArガス量を低減したときには、ノズル塞り
が頻発して生産性が著しく阻害される。 Inside the slab slab with reference to Figures 2 and 3.
Blowing that suppresses the number of pinholes to less than 10 per ton of molten steel by trapping Ar bubbles.
If the amount of Ar gas, that is, the amount of dissipation is limited to 4N or less per ton of molten steel, the occurrence of blistering on the surface of the cold rolled sheet after annealing can be practically avoided.
If the amount of Ar gas is simply reduced, nozzle clogging occurs frequently and productivity is significantly inhibited.
この点については再び第１図に破線で併示した
ように、N2ガスを溶鋼トン当たり3NとしてAr
ガスと混合した混合ガスを用いることによつて、
ノズル塞がりを有利に回避し、しかもふくれ発生
も激減する。 Regarding this point, as shown again in Figure 1 by the broken line, the N2 gas is set to 3N per ton of molten steel, and the Ar
By using a mixed gas mixed with gas,
Advantageously avoids nozzle clogging and also dramatically reduces the occurrence of blisters.
Arと混合するN2ガス量は、溶鋼トン当たり
10N以内であれば、鋼中Ｎの上昇は5ppmをこ
えることがないので品質上の問題はないがN2単
独の上昇の吹込みを行うと、事実上無視できない
鋼中Ｎの上昇を伴うので、Arとの混合ガスを用
いなければならない。 The amount of N2 gas mixed with Ar is per ton of molten steel.
If it is within 10N, the increase in N in the steel will not exceed 5ppm, so there is no quality problem.However, if N2 is injected to increase it alone, the increase in N in the steel will be virtually negligible. , a gas mixture with Ar must be used.
（作 用）
上記のように溶鋼トン当たり4N以下に低減
したArと同じく10N以下に制限したN2との混
合ガスは、その浸漬ノズル内におけるバブリング
の働きで、格別な鋼中Ｎの上昇を伴わずに浸漬ノ
ズル内面における介在物とくにAl2O3の析出によ
るノズル塞りを防止し、したがモールド内に巻込
み帯同するAr気泡の捕捉の機会を著しく低減し、
これを主因とする焼鈍後の冷延薄板表面における
ふくれ欠陥の発生を激減する。(Function) As mentioned above, the mixed gas of Ar reduced to 4N or less per ton of molten steel and N 2 also limited to 10N or less causes a remarkable increase in N in steel due to bubbling in the immersion nozzle. This prevents the nozzle from clogging due to the precipitation of inclusions, especially Al 2 O 3 , on the inner surface of the immersion nozzle, but it also significantly reduces the chance of trapping Ar bubbles entrained in the mold.
This drastically reduces the occurrence of blistering defects on the surface of cold-rolled thin sheets after annealing, which is mainly caused by this.
（実施例）
Ｃ：0.002％、Si：0.01％、Mn：0.10％、Al：
0.035％、の組成になる溶鋼を転炉で溶製し、ス
ラブ連続鋳造機により厚み2200mm、幅1500mmのス
ラブをつくつた。(Example) C: 0.002%, Si: 0.01%, Mn: 0.10%, Al:
Molten steel with a composition of 0.035% was melted in a converter, and a slab with a thickness of 2200 mm and a width of 1500 mm was made using a continuous slab casting machine.
この際浸漬ノズルの内面にて、Ar：N2＝１：
１の混合ガスの溶鋼トン当たり8Nバブリング
を行つたところ、このスラブの常法に従う熱間圧
延、冷間圧延を経たのち焼鈍の際における板面の
ふくれ欠陥の発生は、Arのみの、溶鋼トン当た
り8Nのバブリングのときのふくれ欠陥発生が、
次に示す指数表示で13であつたのに反しほぼ０で
あつた。 At this time, on the inner surface of the immersion nozzle, Ar:N 2 =1:
When 8N bubbling was performed per ton of molten steel with the mixed gas of 1, it was found that the occurrence of blistering defects on the plate surface during annealing after hot rolling and cold rolling in accordance with the conventional method for this slab was as follows. The occurrence of blistering defects when bubbling at 8N per
Although it was 13 in the index shown below, it was almost 0.
ここにふくれ発生指数は、 ふくれ発生コイル数／検査コイル数×1000 によつて、規定することとした。 Here, the blistering index is Number of blistering coils/number of inspected coils x 1000 It was decided to stipulate the following.
（発明の効果）
この発明によれば極低炭素アルミキルド鋼の如
き、冷延薄板製品に仕向けられる鋼スラブの連続
鋳造の際に、モールドへの溶鋼移注に供する浸漬
ノズルの内面に施される、バブリング用ガス組成
に加えた配慮によつて、ノズル塞りの防止機能に
影響なく、該ガスのスラブ内部での捕捉の機会を
著しく低減し、それに主として由来する、冷延薄
板の焼鈍の際のふくれ欠陥の発生を有利適切に回
避することができる。(Effects of the Invention) According to the present invention, during continuous casting of steel slabs to be made into cold-rolled thin sheet products such as ultra-low carbon aluminum killed steel, the process is applied to the inner surface of the immersion nozzle used for pouring molten steel into a mold. , the consideration given to the bubbling gas composition significantly reduces the chance of the gas being trapped inside the slab without affecting the nozzle clogging prevention function, which is mainly due to the fact that during annealing of cold-rolled sheets. The occurrence of blistering defects can be advantageously and appropriately avoided.
第１図は吹込みArガス量とノズル塞り指数の
関係グラフ、第２図は同じく鋳片内１mmφ以上の
ピンホール個数との関係グラフ、第３図はこのピ
ンホール個数とふくれ発生指数との関係グラフ、
第４図は吹込みArガス量とふくれ発生指数との
関係グラフであり、第５図は溶鋼のモールド内移
注挙動説明図である。
Figure 1 is a graph of the relationship between the amount of blown Ar gas and the nozzle clogging index, Figure 2 is a graph of the relationship between the number of pinholes of 1 mm diameter or more in the slab, and Figure 3 is a graph of the relationship between the number of pinholes and the blistering index. relationship graph,
FIG. 4 is a graph showing the relationship between the amount of blown Ar gas and the blistering index, and FIG. 5 is an explanatory diagram of the transfer behavior of molten steel in the mold.
Claims (1)
極低炭素鋼冷延薄板に仕向けるスラブの連続鋳造
に当たり、モールド内への溶鋼注入を司る浸漬ノ
ズルの内面にて、その面上における鋼中介在物の
析出を回避すべく溶鋼トン当たり4Nをこえる
充分な量にて溶鋼注入流に向かうガス放散を行う
際、 溶鋼トン当たり4N以下に制限したArと、同
じく10N以下に制限した残余量のN2との混合
ガスを用い、スラブ鋳片の内部に捕捉されるガス
気泡に基づく１mmφ以上のピンホール数をトン当
たり10こ以内に低減させる ことを特徴とする、焼鈍時ふくれ欠陥を伴わぬ極
低炭素鋼冷延薄板向けスラブの連続鋳造方法。[Scope of Claims] 1. During continuous casting of slabs to be made into ultra-low carbon steel cold-rolled sheets through hot rolling, cold rolling, and annealing processes, on the inner surface of the immersion nozzle that controls the injection of molten steel into the mold. , in order to avoid precipitation of inclusions in the steel on that surface, when dissipating gas toward the molten steel injection flow in a sufficient amount exceeding 4N per ton of molten steel, Ar is limited to 4N or less per ton of molten steel, and 10N is also used. It is characterized by reducing the number of pinholes of 1 mmφ or more based on gas bubbles trapped inside the slab slab to within 10 pinholes per ton by using a mixed gas with a residual amount of N 2 limited to the following: A method for continuous casting of slabs for cold-rolled thin sheets of ultra-low carbon steel without causing blistering defects during annealing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17595185A JPS6238747A (en) | 1985-08-12 | 1985-08-12 | Continuous casting method for slab for thin cold rolled sheet of dead soft steel without blister defect in annealing stage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17595185A JPS6238747A (en) | 1985-08-12 | 1985-08-12 | Continuous casting method for slab for thin cold rolled sheet of dead soft steel without blister defect in annealing stage |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6238747A JPS6238747A (en) | 1987-02-19 |
| JPH0324296B2 true JPH0324296B2 (en) | 1991-04-02 |
Family
ID=16005100
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17595185A Granted JPS6238747A (en) | 1985-08-12 | 1985-08-12 | Continuous casting method for slab for thin cold rolled sheet of dead soft steel without blister defect in annealing stage |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6238747A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2554105B2 (en) * | 1987-10-14 | 1996-11-13 | 川崎製鉄 株式会社 | Method for preventing blockage of immersion nozzle in continuous casting |
| JPH0771722B2 (en) * | 1987-12-21 | 1995-08-02 | 川崎製鉄株式会社 | Thin plate manufacturing equipment |
| CN106623886A (en) * | 2016-11-25 | 2017-05-10 | 上海意硕工程设备有限公司 | Continuous casting tundish stopper rod nitrogen-argon mixed blowing device |
-
1985
- 1985-08-12 JP JP17595185A patent/JPS6238747A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6238747A (en) | 1987-02-19 |
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