JPS59141355A - Production of weakly deoxidized steel by continuous casting method - Google Patents

Abstract

PURPOSE:To produce a billet for a steel material having excellent external and internal quality and excellent processability, etc. by subjecting a specific molten steel to electromagnetic induction stirring in a casting mold by magnetic field induced by the AC of which the specific frequency and magnetic flux density satisfies the specific equation. CONSTITUTION:A molten steel contg. <=0.25% C, <=0.02% Si, <=0.007% Al, and the balance Fe and other components and contg. <=150ppm free oxygen is supplied by an immersion nozzle into a casting mold of which the shape in the corner part is chamfered to the radius or straight line of 1/3 of the thickness on the short side of a billet or below. The molten steel is cast while a heat insulating type flux is charged onto the surface of the molten steel. The molten steel is drawn out continuously downward to solidify while the molten steel in the casting mold is stirred with electromagnetic induction around the axial center of the casting mold by the magnetic field induced by the AC current of which the range of a frequency f=1.5-10Hz and a magnetic flux density G satisfies the equation I . The weakly deoxidized steel is thus produced.

Description

【発明の詳細な説明】 本発明は、鋳型内電磁攪拌を利用して連続鋳造法番こよ
り製造する表面及び内部品質に１憂れ、かつ冷間鍛造性
等の加工性、切削加工時の工具寿命等の彼削性および焼
入性にすぐれた、特に棒ｉ１．Ｉ］および線材に好適な
ｊｌＩＹＩ材用法片の製造方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention is a continuous casting method using electromagnetic stirring inside a mold, which improves surface and internal quality, improves workability such as cold forgeability, and improves tooling during cutting. Especially the rod i1. has excellent machinability and hardenability such as life span. I] and a method for manufacturing a jlIYI material usage piece suitable for wire rods.

〜般６こ４間鍛造用棒鋼およひ線弓に対する主な要求特
性はモ分な変形能、良好な表面状態、内部品質、寸法精
度および均一性などである。このような棒３’ｆｉ＃　
＞よび線材の製造に連続鋳造法を適用する場合に、リム
ド鋼では強冷却と深い溶鋼プールとがリミングアクショ
ンの不調和な強さを助長して鋳型から／ｇ重を溢出さし
たり、凝固殻にフローホールか発生し、連続鋳造作業上
または製品として好葦しくないので、溶鋼を連続鋳造す
る前ｒこ脱酸することか必要である。従来、溶市中の酸
素を除去する場合の脱酸法としては真空脱ガス法、フェ
ロシリコン（フェロマンガン）、アルミニューム等ノ金
１、キ、脱酸剤による方法が知られているが、金属脱酸
剤を多量に使用すると、アルミナ系およびシリカ系の介
在物か増加して製品品質上好ましくない欠陥をひき起す
。このため、金属脱酸剤の含有はを少なくした鋼の連続
鋳造法として、例えば特公昭４７−４７２０９号公報や
特公昭５４　３８５６７号公報等にＪ己載された方法が
提案されており、金属脱酸剤として前者は／Ｗ’とＳｉ
　による復合弱１１９峻、後者は真空脱ガス法と少晴の
Δｌによる弱脱酸が用いられている。前者の５１添加弱
脱酸廟においては多量の脱酸剤を加えたキルド鋼におけ
るＳ　ｉ　Ｏ２やＡ　Ｉ　２０３（非金属）介在物に起
因する問題はかなり暖和されるが、新４たに次の様な問
題が派生する。すｔ□（わちＳｉを少＠添加し、しかも
Δｌの添加量を極力少なくするために鋼中に生成する酸
化物がＳ　１０２およびＭｎＯを主成分とするいわゆる
石１酸塩になって、この酸化物が鋼中に比１咬的に大き
い介在物として残留しやすく、しかも熱間圧延工程にお
いて塑性変形しやすいために圧延方向に線状に長く伸び
た形状になりやすい。そのために例えば圧延方向にそれ
らの棒鋼および線材を１居え込み、あるいはへツテイン
クなどの加工形式で冷間圧縮する場合に、圧延方向ｌこ
平行な割れか鋼材表面に発生し、はとんど加工に耐えな
いことがあり、１だその他にも長く伸びた線状介在物が
場合により棒鋼および線材表面に露出すれば線状の地き
すとなり表向性状を損なう原因にもなる欠点を持つ。こ
の様な圧縮による割れは熱間圧延のま丑の棒箱、および
線材にとくにｌ！ｉ′ｉ著に発生し、したがってこの銅
源は熱間圧延のままとして使用する場合には非常に用途
か制限されることになる。The main properties required for steel bars and wire bows for general 6-4 space forging are strong deformability, good surface condition, internal quality, dimensional accuracy, and uniformity. Bar 3'fi# like this
> When continuous casting is applied to the manufacture of rimmed steel and wire rods, the strong cooling and deep molten steel pool of rimmed steel promotes the unbalanced strength of the rimming action, causing overflow of /g weight from the mold and solidification. Flow holes occur in the shell, which is not good for continuous casting operations or as a product, so it is necessary to deoxidize the molten steel before continuous casting. Conventionally, known deoxidizing methods for removing oxygen in the melt include vacuum degassing, methods using metals such as ferrosilicon (ferromanganese) and aluminum, and methods using deoxidizing agents. If a large amount of metal deoxidizer is used, alumina-based and silica-based inclusions will increase, causing defects that are undesirable in terms of product quality. For this reason, as a continuous casting method for steel with a reduced content of metal deoxidizing agent, the method described in, for example, Japanese Patent Publication No. 47-47209 and Japanese Patent Publication No. 38567 of 1982 has been proposed. The former is /W' and Si as a deoxidizing agent.
The latter uses a vacuum degassing method and weak deoxidation using Shoharu's Δl. In the former 51-added weak deoxidizer, the problems caused by S i O2 and AI 203 (nonmetallic) inclusions in killed steel with a large amount of deoxidizer added are considerably alleviated, but Problems like this arise. (In other words, in order to add a small amount of Si and to minimize the amount of ∆l added, the oxides generated in the steel become so-called lithic salts whose main components are S102 and MnO. These oxides tend to remain as relatively large inclusions in the steel, and they also tend to be plastically deformed during the hot rolling process, so they tend to form a linearly elongated shape in the rolling direction. When steel bars and wire rods are rolled in one direction or cold compressed using processing methods such as flattening, cracks parallel to the rolling direction occur on the surface of the steel material, and it is difficult to withstand processing. In addition to this, if long linear inclusions are exposed on the surface of the steel bar or wire rod, they may form linear cracks and cause deterioration of the surface properties. Cracking occurs particularly in hot-rolled raw rods and wire rods, so the use of this copper source is very limited when used as hot-rolled. It turns out.

この線状介在物の影響を除去する方法としては、それら
の棒鋼および線材に対して冷間引抜タイスにより１！ｆ
Ｔ而イ威面率４０〜５０％Ｊジ、上の冷間引抜を行なわ
ねばならない。この工程を通過した棒鋼および線材の介
在物は引抜方向に細かく寸断され、材料特性におよぼす
介在物の影響は非常に少なくなりほとんど：ＩｊｊＥ視
できるが、しかしながら、４０〜５０％の断面減少率を
加えるには少なくとも３四以上のｌ台間引抜ダイス通過
の余分の工程を必要とする。One way to remove the influence of these linear inclusions is to cold-draw the steel bars and wires with 1! f
Therefore, cold drawing must be performed at a surface rate of 40 to 50%. The inclusions in the steel bars and wire rods that have passed through this process are finely shredded in the drawing direction, and the influence of the inclusions on the material properties is very small and can be seen as almost 40 to 50% reduction in area. Addition requires at least 3 or more extra steps of passing through a drawing die.

一方、後者の極低炭素弱脱酸鋼においては、キルド鋼や
Ｓ１添加弱脱酸鋼における介在物の問題はほとんど解消
されるが、以下の様な問題点かある。この極低炭素弱脱
酸個は真空脱ガス処理を行なって溶第１中の酸素および
炭素含有駄を低下させる等の処理を行ない、凝固時のガ
ス発生はを少なくすることを特徴としているが、このよ
うにカス発生１＃を少なくすると鋳型内の溶鋼の対流か
弱づり、ガスを滞留したま１凝固しやすくなり非負な表
面状態は期待できない。したがって理想としては、！ｉ
７１型に注入した直後溶鋼が放出すべきカスをほとんど
放出してしまい、以後はほとんどカスの発生が起らない
ような操業にするのが理想的であるが、そのため７−Ｌ
大速度を非常に遅くしたり、住人後−１寺庄人を中断し
たりして鋳型内でカスを放出してし甘うことも行なわれ
るが、生産性が著しく低下するため実用とはならない。On the other hand, in the latter ultra-low carbon weakly deoxidized steel, the problem of inclusions in killed steel and S1-added weakly deoxidized steel is almost eliminated, but there are the following problems. This ultra-low carbon weak deoxidizer is characterized by performing vacuum degassing treatment to reduce oxygen and carbon content in the melt, thereby reducing gas generation during solidification. If the scum generation 1# is reduced in this way, the convection of the molten steel in the mold will be weak, and the gas will remain and solidify easily, making it impossible to expect a non-negative surface condition. Therefore, ideally! i
Immediately after pouring into Type 71, the molten steel releases most of the scum that should be released, and ideally the operation should be such that almost no scum is generated after that.
It is also possible to release the scum in the mold by slowing down the mass speed or interrupting the molding process for -1 time after the molding, but this is not practical as it significantly reduces productivity.

寸た極低炭素弱脱酸１１１？ｉでは炭素量が０．０２％
以下とかなり低いため、液相線温度がかなり高くなり、
それに過熱度を加えた鋳造温度はさらに高くなる為、転
炉においては高温用事ｉとなり炉寿命の低下を招き又耐
人物の溶損が著しくレンカ等外来系の介在物か鋼中に存
在している介在物にイ」加されるので、溶１ｉ１Ｙｉの
消汀１度はかなり劣化する。炭素量が低いことは後に続
く圧延工程においても問題かあり、Ａ　ｒ　３変態温度
か高くなるので圧延温度を高くする分だけ加５′−！）
炉の総和１費も高くつき、口〜ルカリバーの損耗も著し
く圧延品も軟質であるｊ９めに１ｊｌ）がつきやすい。Extremely low carbon weak deoxidation 111? In i, the carbon content is 0.02%
The liquidus temperature is quite high, as it is quite low as below.
Adding the degree of superheating further increases the casting temperature, which causes high temperatures in the converter, leading to a reduction in the life of the furnace.Also, the corrosion resistance of the resistor is significant, and foreign inclusions such as casters are present in the steel. Since ion is added to the inclusions present, the quenching rate of the molten 1i1Yi deteriorates considerably. The low carbon content may also be a problem in the subsequent rolling process, and the A r 3 transformation temperature will be high, so an additional 5'-! )
The total cost of the furnace is high, and the wear and tear of the mouth to clarifier is significant, and the rolled product is also likely to be soft.

また製品も強度が３０　Ｋｇ／−級で軟質であるため、
くぎ、針金ａｐの軟箪１線伺に用途がかなり限定される
。In addition, the product is soft with a strength of 30 kg/-, so
Its use is quite limited to just one line of soft pegs for nails and wire ap.

本発明は、上記従来鋼種の技術的備点を解決して連続鋳
造法により比較的容易に表面がきれいで内部の品質も良
く、しかも加工性の１０れた特に棒鋼および線材に好適
な弱脱酸鋼の製造方法を新規に提供することを目的とし
ている。The present invention solves the above-mentioned technical drawbacks of conventional steel types, and has a continuous casting method that provides relatively easy surface cleanliness and good internal quality, as well as weak workability, which is particularly suitable for steel bars and wire rods. The aim is to provide a new method for producing acid steel.

すなわち、本発明は、冷間圧造用竪（Ｈに供する弱脱酸
鋼の連続鋳造法による製造方法として、Ｓ１無添加で０
．（Ｊ２％（ｗｔ％）す、−ド、５ｏｌＡｌが０．００
７％以下、全自由酸素ｍを１５０円捕以下で好甘しくは
全窒素＠３０１）ｌ）ｍ　以−ドに脱酸調整された溶鋼
を、浸漬ノズルで、コーナ一部の形状が鋳ハ（１，１、
ｊ辺ｊ￥の１／３　　若しくはそれ以下のＲ−４たけ直
線で角取りした鋳造用鋳型内に供給し、該鋳型内の溶羽
湯１ｍに断熱型フラックスを没入しつつ鋳造し、該鋳型
内部で溶鋼に均一な一定磁力の電磁攪拌をかけることに
より、溶鋼自身が有するＣ　、　ｋｉｎおよび／ｌＩ！
で脱酸を強化促進さすとともに、寓）、Ｆ　ノ１：！！
内に生成する酸化物および気泡に回転力を付加さし、説
固殻への凝集を抑制しながら、気泡に：ｒｉの介在物を
強制的に／７．−１＝促進させ、該溶’、Ｅｉｌｉを鋳
型ド方へ連続的に引き出して凝固させて、その結果Ｃ：
　０．２５％以ド、　Ｓｉ：０．０２％未満、Ｍｎ　　
：　　０．１５％超０．９％以Ｆ、５ｏｚＡｌ：　０．
００５％以下、残部は鉄と不可避的成分からなる偏析度
小さく表向品質の良好な軟質の加工性および焼入性の優
れた鋼材用連続鋳造鋳片を得ることができるようにした
ものである。That is, the present invention provides a method for manufacturing weakly deoxidized steel to be subjected to cold heading (H) by a continuous casting method.
．． (J2% (wt%) S, -do, 5olAl is 0.00
7% or less, total free oxygen m is less than 150 yen, preferably total nitrogen @ 301) l) m. The molten steel that has been deoxidized is heated with a submerged nozzle so that the shape of a part of the corner is (1,1,
The flux is supplied into a casting mold which has been chamfered with an R-4 straight line of 1/3 of the j side or less, and is cast while immersing the heat insulating flux into 1 m of molten metal in the mold. By applying electromagnetic stirring with a uniform constant magnetic force to the molten steel internally, the molten steel itself has C, kin and /lI!
In addition to strengthening and promoting deoxidation, F No. 1:! !
A rotational force is applied to the oxides and bubbles generated within the bubbles, and the inclusions of :ri are forced into the bubbles while suppressing aggregation into a solid shell./7. -1 = Acceleration, the melt is continuously drawn towards the mold and solidified, resulting in C:
0.25% or more, Si: less than 0.02%, Mn
: More than 0.15% and less than 0.9% F, 5oz Al: 0.
0.005% or less, with the remainder being iron and other unavoidable components, making it possible to obtain soft continuously cast slabs for steel materials with a low degree of segregation, good surface quality, and excellent workability and hardenability. .

本発明者等は、詳細に研究検討した結果、特殊なコーナ
ー形状を有する鋳型内に注入した溶鋼に回転力を加える
と、溶鋼中に溶解している自由酸素の大半がガス又は酸
化物に変化し、それ自身の浮力に回転力が加わって他の
浮遊している介在物も一緒に伴なって溶ｊ醐中から浮上
骨部することを見出した。寸た、」１記鋳型の適正なコ
ーナー形状は、鋳片短辺厚の１７３以下のｋもしくは直
線で角取りしたもので、さらに上記電磁攪拌は、鋳型内
で上記溶１４肖を周波数ｆ−１．九〜１０．　ＯＦ−Ｔ
ｚと磁束密度Ｇの範囲が １９５ｘｅ−０゛１８ｆ＜Ｇ≦１７９０ｘｅ−０２Ｏｆ
を満足する交流によって誘起された磁界により電磁誘導
攪拌すると溶鋼中の介在物の浮上促進および溶鋼表層部
の脱炭に効果的であることが判明した。これらの事実を
利用して、本発明は必要最小限度の金属脱酸剤を用いて
溶鋼の脱酸調整をし、その酸化物を電磁攪拌により除去
して表面品質のすぐれた軟質の加工性および焼入性のよ
い、特に線棒鋼抽として好適な鋼材を連続鋳造鋳片とし
て得ることができるものである。このようにして得られ
た鋼材は従来一般造塊から製造′したものに比して同−
址たはそれ以、上の品質を保つものである。As a result of detailed research and consideration, the inventors of the present invention found that when a rotational force is applied to molten steel injected into a mold with a special corner shape, most of the free oxygen dissolved in the molten steel changes into gas or oxides. However, it was discovered that the rotational force is added to the buoyancy of the bone itself, and other floating inclusions are taken with it, causing the bone to float out of the melt. The appropriate corner shape of the mold described in item 1 is one cut with a k or a straight line that is less than 173 of the thickness of the short side of the slab, and the electromagnetic stirring is performed at a frequency f- of the melt 14 in the mold. 1. 9-10. OF-T
The range of z and magnetic flux density G is 195xe-0゛18f<G≦1790xe-02Of
It has been found that electromagnetic induction stirring using a magnetic field induced by an alternating current that satisfies the following is effective in promoting the levitation of inclusions in molten steel and in decarburizing the surface layer of molten steel. Taking advantage of these facts, the present invention adjusts the deoxidization of molten steel using the minimum necessary metal deoxidizing agent, removes the oxides by electromagnetic stirring, and produces soft workable steel with excellent surface quality. A steel material with good hardenability and particularly suitable for wire bar drawing can be obtained as a continuously cast slab. The steel material obtained in this way is comparable to that produced from conventional ingots.
It maintains the same quality as before or even longer.

次に、本発明の実施例を図面に示す特性線図とともに述
べる。Next, embodiments of the present invention will be described with reference to characteristic diagrams shown in the drawings.

まず−」−下吹転炉を用いてＣ＝０．１８％以下へ４ｎ
＝０．１２〜０．２Ｑ％、Ｓｉ−痕跡の化学成分組成の
溶鋼を３チヤージ吹鏡し、出咽時にＡＪおよび１・ｅＭ
ｎ等の脱酸合金剤を取鍋内で添加して、Ｃ：０．２５％
］ジ、下、Ｓ＋：０．０２’Ｎ以Ｆ、　ＡＩ！：　０．
００７Ｚ以下、残部はＦ’ｅとその他の成分を有し、か
つ全白Ｉ１１酸素用を１５０　ｐｐｍ　　以■、捷た好
１しくは金窒素昂３Ｑ　ｐｐｍ以下を含む溶鋼をタンテ
ィシュ内に用意するようにする。この時、取鍋内等でア
ルゴン攪拌処理または真空処理などの溶鋼１処理により
溶鋼内の鋼中ガスを除去して出来るだけ清淳化処理する
ことが望ましい。タンディシュ内の溶飾６１の成分は、
Ｃが０．２５％以下、Ｓｉが０．０２％以下で、通常の
リムド鋼と同一組成にして、鋼の軟質化を企り、柔かい
軟鋼材を得ることができる。First, use a bottom blowing converter to reduce C to 0.18% or less.
= 0.12~0.2Q%, Si-trace chemical composition is 3-charge blowing mirror, AJ and 1 eM are discharged.
C: 0.25% by adding deoxidizing alloying agent such as n in a ladle.
] Ji, bottom, S+: 0.02'N or more F, AI! : 0.
007Z or less, the balance being F'e and other components, and molten steel containing less than 150 ppm of pure white I11 oxygen, preferably less than 3Q ppm of gold nitrogen, is prepared in a tan tissue. Do it like this. At this time, it is desirable to remove the gas in the molten steel by argon stirring treatment or vacuum treatment in a ladle or the like to make the molten steel as clean as possible. The ingredients of welding 61 in the tundish are:
By making the composition the same as that of ordinary rimmed steel, with C being 0.25% or less and Si being 0.02% or less, it is possible to soften the steel and obtain a soft mild steel material.

また、溶鋼の成分としてＡｊを０．００２％以下にした
時は鋼材の軟質化を大巾に促進することができる。この
ようにして得られた溶鋼１１を、通常の浸漬ノズルを用
いて特殊なコーナ形状を有する鋳造用鋳型内に投入し、
同時に＠型内に通常の断熱型フラックスを投入する。こ
の時取鍋〜タンディシュ間、タンディシュ−鋳型間をア
ルゴンを封入する等して溶ｒ、岡内に介在物等の生成を
防Ｉ」−する無酸化鋳造がなされることが好ましい。投
入する断熱フラックスは、例えばＳｉＯ２：３８４％、
Ｃａ　Ｏ：３６．４％、Ａｌ２Ｏ３：６６％、Ｆｅ２Ｏ
３：　２．３％、Ｎ　ａ　２０　：　８．０％、Ｆエフ
１％、Ｃ：１２％の成分よりなりフラックス本来の性能
を劣化させることなく、気泡の発生を阻止する効果を得
るに十分な範囲内で一定附添加する。なお、溶鋼６１鋳
型内でその含有する全自由酸素量が１５０　ｐｐｍ　以
下、好寸しくは１３０ＰＰｍＰ１下に自然にまたは強制
的に調整される。溶鋼の全自由酸素計が１５０ｐｐｎｌ
以上になると通常の断熱型フラックスを用いても（−分
に気泡の少ない安定した品質の鋳）−’ｊが得られる・
溶削はａｉ型内で、該鋳型壁に設けた電磁コイルによっ
て、印加した交流で誘起される磁界により電磁誘導攪拌
させながら、鋳型Ｆ方へ連続的に引き出されて凝固され
る。実験では溶市１１の全自由酸素用が１７０　ｐｐｍ
でも鋳片の飛１中炭素がＯ，’０５％のものを電磁攪拌
によって得ることができた。Further, when Aj is set to 0.002% or less as a component of molten steel, softening of the steel material can be greatly promoted. The molten steel 11 thus obtained is put into a casting mold with a special corner shape using a normal immersion nozzle,
At the same time, add normal heat-insulating flux into the @ mold. At this time, it is preferable to perform oxidation-free casting by sealing argon between the ladle and the tundish and between the tundish and the mold to prevent the formation of inclusions, etc. in the melt. The insulating flux to be added is, for example, SiO2: 384%,
CaO: 36.4%, Al2O3: 66%, Fe2O
3: 2.3%, Na20: 8.0%, F: 1%, and C: 12%, which is sufficient to prevent bubble generation without deteriorating the original performance of the flux. Add a certain amount within a certain range. The total amount of free oxygen contained in the molten steel 61 mold is naturally or forcibly adjusted to 150 ppm or less, preferably 130 PPmP1. Total free oxygen meter for molten steel is 150ppnl
If it is above, -'j can be obtained even if ordinary adiabatic flux is used (casting of stable quality with few bubbles).
The cutting process is carried out in the AI mold by an electromagnetic coil provided on the wall of the mold, and the material is continuously pulled out toward the mold F and solidified while being stirred by electromagnetic induction by a magnetic field induced by an applied alternating current. In the experiment, the total free oxygen concentration of Soichi 11 was 170 ppm.
However, by electromagnetic stirring, we were able to obtain slabs with a carbon content of 0.5% during the blast.

このように鋳型内に投入した溶）ｑｉ６１に回転力を加
えて回転すると溶（市中に溶解している自由酸素の大半
がその攪拌によってガスまたは酸化物（こ変化し、それ
自身のａカに回転計心力が加わって他の溶１ｊＪｊｌＪ
中に浮遊している介在物と一緒に溶鋼中から溶ｉ１；ｒ
ｉ外へ除去して、溶ｊ１；弓中の介在物を低減すること
かできると共に、溶鋼表層部の炭素術を低減してｉ］ｉ
ｍを中グ質化することができる。電磁攪拌による表層部
の炭素負偏析はへソダービリテイー向」二に寄′ｊ。When the melt (molten Qi61) put into the mold is rotated by applying rotational force, most of the free oxygen dissolved in the melt (molten liquid) is converted into gas or oxide (this is converted into its own a) by the stirring. The tachometer force is added to the other melt 1jJjlJ
Molten i1;r is removed from the molten steel along with the inclusions floating therein.
It is possible to reduce the inclusions in the molten steel by removing it outside the molten steel, and also to reduce the carbon content in the surface layer of the molten steel.
m can be made into a medium-sized material. Negative segregation of carbon in the surface layer due to electromagnetic stirring tends toward sterility.

すると考えられる。このように、鋳型内で（容１）Ｉこ
イ・ｊ−！Ｊする電磁攪拌の効果は、溶鋼の成分および
含有する全自由酸素用および溶鋼）の鋳型への注入条件
すなわち浸漬型ノズルからの注入と断熱型フラックスお
よび特殊なコーナー形状を角゛する鋳型の使用、ならび
に電磁攪拌の磁界強度に関係し、その結果は出来た鋼材
の偏析度、介在物、表面性状、冷間加工性、切削性、焼
入性および硬度に現われる。It is thought that then. In this way, in the mold (Content 1) Ikoi j-! The effects of electromagnetic stirring depend on the composition of the molten steel, the amount of total free oxygen contained in the molten steel, and the injection conditions of the molten steel into the mold, namely injection from a submerged nozzle, adiabatic flux, and the use of a mold with special corner shapes. , and the magnetic field strength of electromagnetic stirring, and the results appear in the degree of segregation, inclusions, surface texture, cold workability, machinability, hardenability, and hardness of the resulting steel.

第１図は、鋳型コーナーｋが１０　ｍｙｒ　（点線）と
影Ｊ　ｌ／３　　の鋳片短辺厚すなわち１２５龍（実線
）について、メニスカスからの下方への距ボとコーナ一
部の広面に対する凝固遅れ弔の関係を調査した結果を示
す。従来、連続鋳造用；鋳型のコーナー形状が大きくな
ると、凝固遅れによるコーナータテワレ等のａｖ片表面
欠陥を引き起すので鋳型コーナー形状は５〜１５ｍｍの
比較的小さいｋもしくは直線で角取りされていた。しか
し第１図に示す様に鋳型内電磁攪拌の採用によりコーナ
ーに拡大による凝固遅れはほとんど生じなくその結果、
０．０１％Ｃから０．８５％Ｃまでの条用鋼、腫で、コ
ーナータテワレ等の鋳片表面欠陥は全く発生しなく、健
全な切片を製造することができた。なお、鋳片コーナー
Ｉ（が、鋳片短辺厚の約１７３　　以上になると、隣り
合うコーナーが互Ｇこ接近してその間にある短辺の直線
ＺＪ法が小さくなって、該短辺に電磁攪拌用のコイルを
設置することができなくなり、コイルがないと溶ｖｉの
電磁攪拌力が低トする不具合が生じる。第２図は、非磁
性のステンレス鋼板製の１０Ｍ（点線）、７０ｍ７Ｎ（
一点鎖線）、１２５ｍノ〃（実線）のコーナー■（を何
する３種類の模擬１１１型にて、電磁攪拌を比較的強攪
拌側とした場合の各融ウッドメタルのａｆ型内周各位置
におけるＰＡｍ１変動量の調査結果を示す。コ〜す〜Ｒ
か大きくなる稈、湯面変動量は小さくなり、鋳型内のコ
ーナ一部でその影響が顕著に現われる。この現象は、コ
ーナー１く拡大によりウッドメタルの流動状１舊かｕｒ
型内全周にわたって円渭であり、流速もほに゛均一であ
ることを示している。捷だコーナーｋを直線で角取りし
た場合もほとんど同様な傾向を示すことが確認された。Figure 1 shows the solidification of the downward taper from the meniscus and the wide surface of a part of the corner when the mold corner k is 10 myr (dotted line) and the short side thickness of the slab is 125 myr (solid line). The results of an investigation into the relationship between delayed mourning are shown. Conventionally, for continuous casting; if the corner shape of the mold became large, it would cause AV side surface defects such as corner warpage due to solidification delay, so the mold corner shape was chamfered with a relatively small k of 5 to 15 mm or with a straight line. . However, as shown in Figure 1, by adopting electromagnetic stirring inside the mold, there is almost no solidification delay due to expansion at the corners, and as a result,
With steel strips containing 0.01% C to 0.85% C, no surface defects such as corner cracks occurred at all, and sound sections could be produced. In addition, when the slab corner I (is approximately 173 times thicker than the short side thickness of the slab), the adjacent corners approach each other by G, and the straight line ZJ of the short side between them becomes small, causing It becomes impossible to install a stirring coil, and if there is no coil, the electromagnetic stirring force of the molten VI will be reduced.Figure 2 shows a 10M (dotted line) and a 70m7N (dotted line) made of non-magnetic stainless steel plate.
(dotted chain line), 125 m (solid line) corner ■ The results of the survey on the amount of variation in PAm1 are shown.
As the culm becomes larger, the amount of fluctuation in the melt level becomes smaller, and the effect is noticeable in some corners of the mold. This phenomenon is caused by the fact that the fluidity of the wood metal is increased by enlarging the corners.
The flow is circular throughout the entire circumference of the mold, indicating that the flow velocity is also very uniform. It was confirmed that almost the same tendency was observed when rounded corner k was rounded with a straight line.

第３図は全自由酸素量が１１’Ｏｐ））ｍ　　に調整さ
れた溶鋼を鋳型が１０　ｍｍ　（点線）と１２５　ｍｍ
　（実、線）のコーナー１（を有する２種類の鋳型に注
入し、鋳型内電磁攪拌を比較的強攪拌側として得られた
鋳片について、鋳片表層各位置（広面及び狭面）におけ
る露出ピンホール個数を調査した。ピンホールの検出精
度を向上する目的で事前にスケールのみか剥離する程度
の軽い塩酸処理を行なった。露出ピンホール個数は、広
面および狭面中火部ては、コーナーＩ（の影響は少ない
が、コーナ一部近傍で特に差異か認められ、１０ｍｍ　
Ｒでは著しく増大し、１２５　Ｍ７７／　Ｒでは広面お
よび狭面中央部とほとんど変わらないことがわかった。Figure 3 shows molten steel whose total free oxygen content is adjusted to 11'Op))m with molds of 10 mm (dotted line) and 125 mm.
(solid, line) Corner 1 The number of pinholes was investigated.In order to improve pinhole detection accuracy, a light hydrochloric acid treatment was applied in advance to the extent that only the scale was removed.The number of exposed pinholes was The influence of I (is small, but a difference is observed especially near some corners,
In 125 M77/R, it increased significantly, and in 125 M77/R, it was found that there was almost no difference between the wide and narrow central areas.

このことは、第２図の結果とよく一致する。This agrees well with the results shown in FIG.

第４図は、溶鋼の中に含有する全自由酸素計を種々に代
えて、上記のクロく断熱型フラックスと共に、コーナー
ｋが約１７３　　の短辺厚（＝１２５關）の鋳型内に投
与して鋳型内電磁攪拌した後、得た鋳片のピンホール発
生率を示すもので、溶鋼中の全自由酸素量が１５’　Ｏ
ＰＰｍ以下の１侍には、そのピンホール発生率が大「１
］に小さいことが分る。第５図は、電磁攪拌の強度とし
て、印加する交流の各周波数毎に磁束密度を種々に代え
た場合について、夫々得たｌｉ片の持つ介在物指数を示
すもので、この種ｊ′Ｊｒ片として実用に供し得る鋳片
の介在物指数の許答範囲からみて、磁束密度は一定の範
囲内に限定されることが分る。すなわち、溶鋼に核溶質
を攪拌するべく一定の回り伝流動を与えるためには範囲
内に入る値は、周波数ｆが１．５〜ｌ　Ｑ、　Ｑ　１−
１ｚの間で磁束密度Ｇが １９５Ｘｅ　”””≦Ｇ≦１７９０ｘｅ　”２°ｆであ
ることが必要である。いいかえると、この範囲を超える
と、出来た鋳片の介在物が多くなって、冷間加工性が悪
く、かつ焼入時にはワレが生じて成品の不良率が高くな
る。Figure 4 shows various total free oxygen meters contained in molten steel, which were injected together with the above-mentioned black adiabatic flux into a mold with a corner k of about 173 cm and short side thickness (=125 cm). This shows the pinhole occurrence rate of the slab obtained after electromagnetic stirring in the mold, and the total free oxygen content in the molten steel is 15'O
One samurai with PPm or less has a pinhole occurrence rate of ``1''.
] is found to be small. Figure 5 shows the inclusion index of the obtained li pieces when the magnetic flux density was varied for each frequency of the applied alternating current as the intensity of electromagnetic stirring. It can be seen that the magnetic flux density is limited within a certain range, considering the acceptable range of the inclusion index of slabs that can be put to practical use. That is, in order to give a constant circular flow to stir the nuclear solute in molten steel, the frequency f must fall within the range of 1.5 to 1.
It is necessary that the magnetic flux density G between 1z and 1z is 195Xe ``''''≦G≦1790xe ''2°f. In other words, if it exceeds this range, the resulting slab will have a large number of inclusions, resulting in poor cold workability and cracking during quenching, resulting in a high rate of defective products.

すなわち、上記の如き方法で得た鋳片の介在物指数は、
電磁攪拌の効果に加えて溶鋼中の全自由酸素Ｊｉ）の抑
制によって向上し、さらに鋳片の表面性状は電磁攪拌の
効果に加えてミ溶増中のアルミ添加量の低減と、溶鋼中
の全自由酸素量の抑制によって向上することができる。In other words, the inclusion index of the slab obtained by the above method is
In addition to the effect of electromagnetic stirring, the surface quality of the slab is improved by suppressing the total free oxygen (J) in the molten steel.In addition to the effect of electromagnetic stirring, the surface quality of the slab is This can be improved by suppressing the total amount of free oxygen.

寸だ、伸線性、冷圧性等の鋳片の冷間加工性は溶鋼１の
清浄化すなわち電磁攪拌による介在物の低減と表層部の
炭素低減効果に加えて、溶鋼中のＡｌを０．００７％以
下にして結晶ＲＸｊＪｌ化による硬化防目二とＳｉ　を
０．０２％以下として硬化防１］二、および溶′＃Ｉ処
理、無酸化鋳込みによって向上することができるもので
あり、また、鋳片のＷ削性と焼入性は上記電磁効果に多
少とも依存し、特に焼入性はＡＡ’を０．００７％以下
にして整粗粒鋼としたことに依存する。さらに、溶鋼の
清狩化処理と無酸化鋳造は得た鋳片の介在物指数を低く
押えることに大きく影響する。また、溶精の全窒素令を
３０　ｐｐｍ　以下にすることによって、時効硬化がな
い効果かある。In addition to cleaning the molten steel (i.e., reducing inclusions through electromagnetic stirring and reducing carbon in the surface layer), the cold workability of the slab, such as wire drawability and cold pressability, is achieved by reducing Al in the molten steel by 0.007%. % or less, and hardening prevention 1]2 by setting Si to 0.02% or less, and can be improved by melt treatment and non-oxidation casting. The W machinability and hardenability of the piece depend to some extent on the above-mentioned electromagnetic effect, and in particular, the hardenability depends on the fact that the AA' is set to 0.007% or less to form a coarse-grained steel. Furthermore, cleaning treatment of molten steel and non-oxidation casting have a great influence on keeping the inclusion index of the obtained slab low. Further, by controlling the total nitrogen content of the melt to 30 ppm or less, there is an effect that there is no age hardening.

上記実施例に詳記した如く、本発明にかかる製造方法は
、Ｓｉ無添加で５ＯｚＡｌが０００７％脱酸調整された
溶鋼をコーナーＲが、約１／３の鋳片知辺厚を有する鋳
型内部で一定の磁Ｗ強度の電磁攪拌をかけることにより
、溶鋼自身が有するＣ・ＭｎおよびＡＩ！で脱酸を強化
促進させるとともに、鋳型内に生成する酸化物および気
泡に回転力を付加させ、凝固殻への凝集を抑制しながら
強制ｒｌ’Ｊ　ｉこｌ′￥］−促進さぜ、Ｃ：０．２５
％以下、Ｓｉ：０．０２％Ｉｄ、ド、Ｍｎ　　：　　０
．１　５％超０．９０％以下５ｏｌＡｌ　：（１，００
５％以以上残部はＦｃと不ｉｉＪ　ｉＷ的成分力）らな
る表向及び内部品質の慶れた冷間加工性の良Ｇ）条用連
続鋳造鋳片を得ることができるものである。As described in detail in the above embodiment, the manufacturing method according to the present invention is such that the molten steel, which has been deoxidized to 0,007% with 5OzAl without the addition of Si, is heated inside a mold with a corner radius having a width of about 1/3 of the width of the slab. By applying electromagnetic stirring with a constant magnetic W strength, the C/Mn and AI that the molten steel itself has! In addition to strengthening and promoting deoxidation, applying rotational force to the oxides and bubbles generated in the mold, and suppressing aggregation into a solidified shell while forcing the deoxidation process. :0.25
% or less, Si: 0.02%Id, Do, Mn: 0
．． 1 More than 5% 0.90% or less 5olAl: (1,00
The balance of 5% or more is Fc and non-continuously cast slabs for G) strips with good surface and internal quality and good cold workability.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図乃至第５図は、夫々、本発明の方法で製造した鋳
片の特性についての実験測定値を示す関係線図である。1 to 5 are relationship diagrams showing experimentally measured values of the characteristics of slabs produced by the method of the present invention, respectively.

Claims (1)

【特許請求の範囲】 １）Ｃ：　０．２５　＄Ｊ’ｌ下、Ｓｉ：Ｑ、Ｑ２ｑ／
以下、Ａｄ：０．００７％以下、残部はＩ′’　ｃとそ
の他の成分を角し、かつ自由酸素を１５０　ｐｐｍ以下
を含む溶鋼を、浸漬ノズルで、コーナ一部の形状が鋳片
短辺厚の１／３若しくはそれＵ下のＲ−ＩＨたは直線で
角取りしたａｊ造用鋳型内に供給し、該鋳型内の溶鋼湯
面に断熱型フラックスを投入しつつ鋳造し、鋳型内で上
記ｑＩ’ａを、周波数ｆ”　１．５〜Ｉ　Ｑ、Ｑ　Ｉｌ
ｚ　と磁ｑ已ぞ度（ガウス）Ｇの範囲が １９５ｘ　ｃ　Ｏ，１１３ｆ≦Ｇ≦１７９　ｏ’Ｘ　ｃ
−０２０’を満足する交流によって誘起された磁児によ
りｉＮｉ型軸芯の周りに電磁誘導攪拌させながら鋳型下
方へ連続的に引き出して凝固させる様にしたことを特徴
とする連続Ｑｉｆ造法進法る弱脱酸鋼の製造方法。 ２）上記情事１を清浄化溶鋼処理をして取鍋からタンテ
ィシュを介しａｔ型内に供給すると共に、取鍋とタンデ
ィシュ及びタンディシュと鋳型の夫々の間で無酸化υイ
造させる様にしたことを特徴とする特許 による弱脱酸鋼の製造方法。[Claims] 1) C: below 0.25 $J'l, Si: Q, Q2q/
Hereinafter, molten steel containing Ad: 0.007% or less, the remainder being I''c and other components, and free oxygen of 150 ppm or less, was heated using an immersion nozzle so that the shape of a part of the corner was on the short side of the slab. It is supplied into an R-IH or aj molding mold with a straight corner cut at 1/3 of the thickness or below it, and is cast while pouring adiabatic flux onto the surface of the molten steel in the mold. The above qI'a is expressed as the frequency f"1.5~IQ,QIl
The range of z and magnetic force (Gauss) G is 195x c O, 113f≦G≦179 o'X c
-020' continuous Qif manufacturing method characterized by electromagnetic induction stirring around the iNi type shaft core by magnets induced by alternating current satisfying -020' while continuously drawing it out below the mold and solidifying it. A method for producing weakly deoxidized steel. 2) The above-mentioned molten steel was subjected to cleaning molten steel treatment and supplied from the ladle to the AT mold through the tundish, and non-oxidized υ was formed between the ladle and the tundish and between the tundish and the mold. A patented method for producing weakly deoxidized steel characterized by: