JP2001225152A - Continuous casting method for steel - Google Patents
Continuous casting method for steelInfo
- Publication number
- JP2001225152A JP2001225152A JP2000039341A JP2000039341A JP2001225152A JP 2001225152 A JP2001225152 A JP 2001225152A JP 2000039341 A JP2000039341 A JP 2000039341A JP 2000039341 A JP2000039341 A JP 2000039341A JP 2001225152 A JP2001225152 A JP 2001225152A
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- Prior art keywords
- mold
- mold powder
- continuous casting
- steel
- slab
- Prior art date
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、モールドパウダー
を用いた鋼の連続鋳造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously casting steel using mold powder.
【0002】[0002]
【従来の技術】鋼の連続鋳造においては、一般に、取り
鍋からタンディッシュに注湯された溶鋼が浸漬ノズルを
介して鋳型に注入され、鋳型内で形成された凝固シェル
が鋳型の底部に続いて設けられた案内ロール群の間でス
プレーノズルにより冷却されながら凝固され、鋳片とし
てピンチロールによって引き抜かれる。この際、鋳型内
の溶鋼湯面(以下、メニスカス部という)にモールドパ
ウダーを浮遊させ、溶鋼の熱によってモールドパウダー
を溶融させて鋳型と凝固シェルとの間に流入させ、鋳型
と凝固シェルとの摩擦を軽減して潤滑性を向上させてい
る。また、モールドパウダーにより、鋳型内壁に鋳片が
焼き付くことを防止するために、鋳型を所定の振動数、
所定の振幅で振動させる装置が用いられている。このよ
うなモールドパウダーを用いた鋼の連続鋳造において
は、適切なモールドパウダーを選択しないと、鋳片の表
面に縦割れが発生し、品質上の欠陥である鋳片表面欠陥
が生じるおそれがある。したがって、無手入れの圧延用
連続鋳造鋳片を安定して製造するためには、適切なモー
ルドパウダーを選択することが重要である。2. Description of the Related Art In continuous casting of steel, in general, molten steel poured into a tundish from a ladle is injected into a mold through an immersion nozzle, and a solidified shell formed in the mold continues to the bottom of the mold. It is solidified while being cooled by the spray nozzles between the guide rolls provided, and is pulled out as a cast by a pinch roll. At this time, the mold powder is floated on the molten steel surface (hereinafter, referred to as a meniscus portion) in the mold, the mold powder is melted by the heat of the molten steel, and flows between the mold and the solidified shell. It reduces friction and improves lubricity. In addition, in order to prevent the slab from burning on the inner wall of the mold by the mold powder, the mold is moved at a predetermined frequency,
A device that vibrates at a predetermined amplitude is used. In continuous casting of steel using such a mold powder, if an appropriate mold powder is not selected, a vertical crack is generated on the surface of the slab, and there is a possibility that a slab surface defect which is a quality defect is generated. . Therefore, in order to stably produce an unmaintained continuous cast slab for rolling, it is important to select an appropriate mold powder.
【0003】ところで、炭素含有量が0.08〜0.2
0%である鋼の連続鋳造においては、不均一凝固が生じ
やすいため鋳片に縦割れが生じやすく、これを防止する
ためには鋳型/鋳片(凝固シェル)間の伝熱を遅くす
る、いわゆる「緩冷却」が有効であることが従来より指
摘されている(例えば、鉄と鋼:67(1981),1508.)。こ
の緩冷却の手段としては、鋳型の材質を変更したり、鋳
型の冷却水量を減らしたりすることが試行されてきた
が、いずれの場合も十分な縦割れ防止効果を得ることが
できなかった。[0003] Incidentally, the carbon content is 0.08 to 0.2.
In continuous casting of 0% steel, uneven solidification is apt to occur, so vertical cracks are likely to occur in the slab. To prevent this, heat transfer between the mold and the slab (solidified shell) is slowed down. It has been pointed out that the so-called "slow cooling" is effective (for example, iron and steel: 67 (1981), 1508.). As a means of this slow cooling, attempts have been made to change the material of the mold or to reduce the amount of cooling water in the mold, but in any case, it was not possible to obtain a sufficient vertical crack preventing effect.
【0004】そのような状況において、近年、鋼の連続
鋳造に結晶析出温度の高いモールドパウダーを適用した
結果、鋳片の縦割れ発生頻度が大きく減少するという結
果が得られてきている(例えば、鉄と鋼:,83(1997),115
等)。ここで、結晶析出温度は、一度モールドパウダー
を溶融した後、一定の冷却速度で冷却した時に初晶が析
出する温度を言うが、一般に結晶析出温度の高いモール
ドパウダーは、TTT図における結晶析出領域が大き
い。つまり、いかに溶融したモールドパウダー中に結晶
相を析出させるかが鍵となる。そこで従来の技術におい
ては、モールドパウダー中の結晶相の一つであるCuspid
ine(3CaO・2SiO2・CaF2)が析出しやす
いように、添加元素を工夫してモールドパウダー設計を
行なっていた(前出、鉄と鋼:,83(1997),115等)。In such a situation, in recent years, as a result of applying mold powder having a high crystal precipitation temperature to continuous casting of steel, a result has been obtained that the frequency of occurrence of vertical cracks in the slab is greatly reduced (for example, Iron and steel:, 83 (1997), 115
etc). Here, the crystal precipitation temperature refers to the temperature at which primary crystals precipitate when the mold powder is once melted and then cooled at a constant cooling rate. In general, a mold powder having a high crystal precipitation temperature has a crystal precipitation region in the TTT diagram. Is big. That is, the key is how to precipitate the crystal phase in the molten mold powder. Therefore, in the prior art, Cuspid, one of the crystal phases in the mold powder, is used.
ine as (3CaO · 2SiO 2 · CaF 2 ) is likely to precipitate, by devising the added element has been subjected to mold powder design (supra, iron and steel:, 83 (1997), 115, etc.).
【0005】しかしながら、近年、環境問題への関心の
高まりに伴ないフッ素(F)の環境への排出が問題とな
りつつあり、上記CuspidineはFを含有していることか
ら、少量のFの添加でCuspidineの結晶相を析出させるこ
とのできるプロセスが求められている。[0005] However, in recent years, the emission of fluorine (F) into the environment has become a problem due to the growing interest in environmental issues. Since Cuspidine contains F, the addition of a small amount of F is There is a need for a process that can precipitate the crystal phase of Cuspidine.
【0006】また一方、レーザーフラッシュ法等で測定
したところによると、モールドパウダーの結晶相はガラ
ス相より熱伝導度が高く、このような結晶相を鋳型およ
び鋳片の間に介在させた場合、鋳片は強冷却されるはず
であるが、実際には鋳型の冷却水の温度上昇は低く、緩
冷却となっている。このように鋳型/鋳片間の伝熱挙動
については解明されていない部分も多く、モールドパウ
ダーは試行錯誤的に製造され試験されているのが実情で
ある。On the other hand, according to measurement by a laser flash method or the like, the crystal phase of the mold powder has a higher thermal conductivity than the glass phase, and when such a crystal phase is interposed between the mold and the slab, The slab should be strongly cooled, but in fact, the temperature rise of the cooling water of the mold is low and the slab is slowly cooled. In many cases, the heat transfer behavior between the mold and the slab has not been elucidated in many cases, and the mold powder is actually manufactured and tested by trial and error.
【0007】[0007]
【発明が解決しようとする課題】本発明は、かかる事情
に鑑みてなされたものであって、モールドパウダー中に
結晶相が析出しやすく、モールドパウダーにより緩冷却
を有効に行なうことができ、表面縦割れの極めて少ない
鋳片を製造することができる鋼の連続鋳造方法を提供す
ることを目的とする。DISCLOSURE OF THE INVENTION The present invention has been made in view of such circumstances, and a crystal phase is easily precipitated in a mold powder, and a slow cooling can be effectively performed by the mold powder. It is an object of the present invention to provide a continuous casting method of steel capable of producing a cast piece with extremely few vertical cracks.
【0008】[0008]
【課題を解決するための手段】従来の連続鋳造において
は、粉末もしくは顆粒のモールドパウダーが水分を吸収
すると、モールドパウダーがメニスカス上部に投入され
て溶融する際に熱が奪われるとともに、モールドパウダ
ーが溶融しにくくなることから、一般には鋳型近傍の雰
囲気を乾燥させている。これに対し、本発明者らは表面
縦割れの極めて少ない鋳片を製造すべく種々検討を重ね
た結果、溶融したモールドパウダーが凝固する際に鋳型
近傍の雰囲気中に水蒸気が存在すると、モールドパウダ
ー中に結晶核生成の起点が増えて結晶が析出しやすくな
ることを知見した。Means for Solving the Problems In conventional continuous casting, when powder or granule mold powder absorbs moisture, heat is taken away when the mold powder is put into the upper part of the meniscus and melted, and the mold powder is removed. Generally, the atmosphere near the mold is dried because it is difficult to melt. On the other hand, the present inventors have conducted various studies to produce a slab having extremely few vertical surface cracks. As a result, when steam is present in the atmosphere near the mold when the molten mold powder solidifies, the mold powder It was found that the number of starting points of crystal nucleus formation increased and crystals were easily precipitated.
【0009】本発明は、このような知見に基づいてなさ
れたものであって、モールドパウダーを用いた鋼の連続
鋳造方法であって、鋳型近傍における雰囲気中の水蒸気
分圧を0.05〜0.7atmとして連続鋳造を行なう
ことを特徴とする鋼の連続鋳造方法を提供する。The present invention has been made based on such findings, and is a method for continuously casting steel using mold powder, wherein the partial pressure of water vapor in the atmosphere near the mold is set to 0.05 to 0. The present invention provides a continuous casting method for steel, wherein continuous casting is performed at 0.7 atm.
【0010】また、上記の鋼の連続鋳造方法において、
さらに、凝固したモールドパウダーの表面粗さが5μm
以上となるように連続鋳造を行なうことを特徴とする鋼
の連続鋳造方法を提供する。[0010] In the above continuous casting method for steel,
Furthermore, the surface roughness of the solidified mold powder is 5 μm.
A continuous casting method for steel characterized by performing continuous casting as described above.
【0011】[0011]
【発明の実施の形態】以下、本発明について具体的に説
明する。本発明では、鋳型近傍における雰囲気中の水蒸
気分圧を0.05〜0.7atmとして連続鋳造を行な
うことにより、溶融モールドパウダー中に結晶核生成の
起点を増大させ、例えばCuspidine(3CaO・2Si
O2・CaF2)のような結晶相を従来よりも効率よく
析出することができるので、鋳片の緩冷却を有効に行な
って、鋳片に生じる縦割れを防止することができる。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. In the present invention, the starting point of crystal nucleation in the molten mold powder is increased by performing continuous casting with the partial pressure of water vapor in the atmosphere in the vicinity of the mold being 0.05 to 0.7 atm, for example, Cuspidine (3CaO.2Si).
Since a crystal phase such as O 2 · CaF 2 ) can be more efficiently precipitated than in the past, slow cooling of the slab can be effectively performed, and vertical cracks generated in the slab can be prevented.
【0012】鋳型近傍における雰囲気中の水蒸気分圧が
0.05atm未満では結晶核生成の起点を増大する効
果が十分でなく、結晶相を効率よく析出させることがで
きない。一方、水蒸気分圧が0.7atmを超えると、
モールドパウダー中のFと水蒸気が反応してHFを生成
し、Fが減少して結晶相であるCuspidineが析出しにく
くなる。また、水蒸気によってモールドパウダーが吸湿
し、メニスカス近傍の溶鋼面に投入された際に溶融しに
くくなり、鋳型/鋳片間に流れ込みにくくなってブレー
クアウト等の操業トラブルを発生させてしまう。このこ
とから、本発明では、鋳型近傍の水蒸気分圧を0.05
〜0.7atmとする。If the partial pressure of water vapor in the atmosphere near the mold is less than 0.05 atm, the effect of increasing the starting point of crystal nucleus formation is not sufficient, and the crystal phase cannot be efficiently precipitated. On the other hand, when the water vapor partial pressure exceeds 0.7 atm,
F in the mold powder reacts with water vapor to generate HF, which reduces F and makes it difficult to precipitate Cuspidine, which is a crystalline phase. In addition, the mold powder absorbs moisture due to water vapor, so that it is difficult to melt when poured into the molten steel surface near the meniscus, and it is difficult for the powder to flow between the mold and the slab, thereby causing operational troubles such as breakout. Therefore, in the present invention, the partial pressure of water vapor near the mold is set to 0.05%.
To 0.7 atm.
【0013】実際に、後述する表1のAに示すモールド
パウダーを用い、鋳型近傍である鋳造床の水蒸気分圧を
変化させて鋼の連続鋳造を行った結果、図1に示す結果
が得られた。図1は、横軸にその際の水蒸気分圧をと
り、縦軸に鋳片割れ個数をとって、これらの関係を示す
図である。図1に示すように、鋳型近傍の水蒸気雰囲気
を0.05〜0.7atmとした場合には鋳片表面に生
じる縦割れが顕著に抑制されており、有効に緩冷却が行
なわれていることがわかる。Actually, continuous casting of steel was carried out by using a mold powder shown in A of Table 1 to be described later and changing the steam partial pressure of the casting bed near the mold, and the result shown in FIG. 1 was obtained. Was. FIG. 1 is a diagram showing the relationship between the water vapor partial pressure at that time on the horizontal axis and the number of slab cracks on the vertical axis. As shown in FIG. 1, when the steam atmosphere in the vicinity of the mold is set to 0.05 to 0.7 atm, the vertical cracks generated on the slab surface are remarkably suppressed, and effective slow cooling is performed. I understand.
【0014】鋳型近傍における雰囲気中の水蒸気分圧を
上述の範囲とするためには、例えば、連続鋳造機の鋳型
近傍を囲う囲繞部材を配置し、この囲繞部材内側に水蒸
気分圧を調整した雰囲気を供給することにより行なうこ
とができる。また、鋳型近傍に設けたノズルから鋳型の
メニスカス部に向けて水蒸気分圧を調整した雰囲気を吹
き付けるようにしてもよい。In order to keep the partial pressure of water vapor in the atmosphere near the mold within the above-mentioned range, for example, a surrounding member surrounding the vicinity of the mold of the continuous casting machine is arranged, and an atmosphere in which the partial pressure of water vapor is adjusted is provided inside the surrounding member. Can be carried out. Further, an atmosphere in which the partial pressure of steam is adjusted may be blown from a nozzle provided near the mold toward the meniscus portion of the mold.
【0015】また、本発明では、以上のようにして行な
われる連続鋳造に際して、鋳片に生じる縦割れを一層有
効に抑制し、表面欠陥の極めて少ない鋼の鋳片を得るた
めに、凝固後のモールドパウダーの表面粗さを5μm以
上とすることが好ましい。凝固後のモールドパウダーの
表面粗さが5μm未満では、このように優れた縦割れ抑
制効果が発揮され難い。Further, in the present invention, in the continuous casting performed as described above, longitudinal cracks generated in the slab are more effectively suppressed, and a steel slab having extremely few surface defects is obtained. It is preferable that the surface roughness of the mold powder is 5 μm or more. If the surface roughness of the mold powder after solidification is less than 5 μm, it is difficult to exhibit such excellent longitudinal crack suppressing effect.
【0016】凝固後のモールドパウダーの表面粗さは、
連続鋳造を行なった後、メニスカスに生成したスラグリ
ムごと凝固したモールドパウダーを引き上げて回収し、
凝固したモールドパウダー表面の凹凸の谷(最小値)と
山(最大値)の差を測定することにより把握することが
できるが、この方法では連続鋳造の操業に支障をきたす
可能性があるため、以下の手法によりモールドパウダー
の表面粗さを推定してもよい。The surface roughness of the solidified mold powder is as follows:
After performing continuous casting, the mold powder solidified together with the slag rim generated in the meniscus is pulled up and collected,
It can be grasped by measuring the difference between the valley (minimum value) and the peak (maximum value) of the irregularities on the solidified mold powder surface, but this method may hinder the operation of continuous casting, The surface roughness of the mold powder may be estimated by the following method.
【0017】すなわち、鋼を鋳造する前に、予めイメー
ジ加熱炉を備えたレーザ顕微鏡を用いて、使用するモー
ルドパウダーを脱水したAr雰囲気下(つまり水蒸気分
圧が0atmの雰囲気)で加熱し溶融させた後、実機の
鋳型/鋳片間の冷却速度と推察される10K/secで
室温まで冷却し、レーザ顕微鏡の機能である表面形状測
定機能により、凝固したモールドパウダー表面の凹凸の
谷と山の差r2を測定する。このようにして測定された
r2と水蒸気分圧が0.2atmの雰囲気下で凝固した
モールドパウダーの表面粗さr3との間の関係を実測値
に基づいて把握した結果、 1.25×r2≦r3≦1.4×r2 の範囲となった。これら実測値から(r3/r2)の平
均値を求めると1.31となり、 r3=1.3×r2 と近似することができる。また、水蒸気の影響が現れる
水蒸気分圧0.05atm以上において、連続鋳造中に
凝固したモールドパウダーの表面粗さの実測値r1と上
記r3との間の関係を把握した結果、 1.75×r3≦r1≦2.20×r3 の範囲となった。これら実測値から(r1/r3)の平
均値を求めると2.00となり、 r1=2.0×r3 と近似することができる。したがって、鋳造前に使用す
るモールドパウダーのr2を測定しておけば、上記関係
式から、連続鋳造中に凝固したモールドパウダーの実際
の表面粗さr1を推定することができる。That is, before casting steel, the mold powder to be used is heated and melted in a dehydrated Ar atmosphere (ie, an atmosphere having a partial pressure of water vapor of 0 atm) using a laser microscope equipped with an image heating furnace in advance. After cooling to room temperature at 10 K / sec, which is estimated to be the cooling rate between the mold and the slab of the actual machine, the surface shape measurement function, which is the function of the laser microscope, is used to measure the valleys and hills Measure the difference r2. The relationship between r2 measured in this way and the surface roughness r3 of the mold powder solidified in an atmosphere having a water vapor partial pressure of 0.2 atm was ascertained based on actually measured values. As a result, 1.25 × r2 ≦ r3 ≦ 1.4 × r2. When the average value of (r3 / r2) is obtained from these actually measured values, it is 1.31, which can be approximated as r3 = 1.3 × r2. Also, as a result of grasping the relationship between the measured value r1 of the surface roughness of the mold powder solidified during continuous casting and the above-mentioned r3 at a steam partial pressure of 0.05 atm or more where the influence of steam appears, 1.75 × r3 ≦ r1 ≦ 2.20 × r3. When the average value of (r1 / r3) is obtained from these actually measured values, it is 2.00, which can be approximated as r1 = 2.0 × r3. Therefore, if the r2 of the mold powder used before casting is measured, the actual surface roughness r1 of the mold powder solidified during continuous casting can be estimated from the above relational expression.
【0018】なお、レーザ顕微鏡のイメージ加熱炉では
モールドパウダーを入れるセルが小さいため、モールド
パウダーが凝固する時に表面張力の影響を受けて表面粗
さが小さくなってしまうが、相対的な関係は維持される
ため、上述したように係数を乗ずる補正を行なうことに
よりイメージ加熱炉を用いた加熱および冷却後の表面粗
さを測定したデータで十分実機の状況を再現することが
できる。In the image heating furnace of the laser microscope, since the cell in which the mold powder is placed is small, the surface roughness is reduced due to the surface tension when the mold powder solidifies, but the relative relationship is maintained. Therefore, by performing the correction by multiplying the coefficient as described above, the data obtained by measuring the surface roughness after heating and cooling using the image heating furnace can sufficiently reproduce the situation of the actual machine.
【0019】実際に、水蒸気分圧0.3atmの雰囲気
で、種々の表面粗さを示すモールドパウダーを用いて連
続鋳造を行い、鋳片に生じた表面縦割れ個数を計測した
結果、図2に示す結果が得られた。図2は、横軸にその
際の凝固後のモールドパウダーの表面粗さをとり、縦軸
に鋳片割れ個数をとって、これらの関係を示す図であ
る。図2に示すように、凝固後のモールドパウダーの表
面粗さを5μm以上とすることによって、鋳片に生じる
縦割れを一層効果的に抑制することができることがわか
る。なお、ここでの凝固後のモールドパウダーの表面粗
さは、上記の手法により推定された値である。Actually, continuous casting was performed using mold powders having various surface roughnesses in an atmosphere having a partial pressure of water vapor of 0.3 atm, and the number of surface vertical cracks generated in the slab was measured. The results shown were obtained. FIG. 2 is a diagram showing the relationship between the surface roughness of the mold powder after solidification at that time on the horizontal axis and the number of slab cracks on the vertical axis. As shown in FIG. 2, it can be seen that by setting the surface roughness of the mold powder after solidification to 5 μm or more, vertical cracks generated in the slab can be more effectively suppressed. Here, the surface roughness of the mold powder after solidification is a value estimated by the above method.
【0020】なお、本発明の連続鋳造方法では、例え
ば、SiO2,CaO,Al2O3,Fe2O3,Mg
O,MnO,BaO,B2O3等の酸化物を母材とし、
その他にNa2O,K2O,Li2O等の金属酸化物、
NaF,KF,LiF,CaF 2,MgF2,Al
F3,Na3AlF6等のフッ化物、それら金属の炭酸
化物や硝酸化物等が添加された、一般的に用いられてい
るモールドパウダーを使用することができるが、これに
限定されるものではない。In the continuous casting method of the present invention, for example,
For example, SiO2, CaO, Al2O3, Fe2O3, Mg
O, MnO, BaO, B2O3And the like as the base material,
In addition, Na2O, K2O, Li2Metal oxides such as O,
NaF, KF, LiF, CaF 2, MgF2, Al
F3, Na3AlF6Such as fluoride, carbonic acid of those metals
Commonly used with the addition of
Mold powder can be used.
It is not limited.
【0021】[0021]
【実施例】次に、本発明の実施例を示す。表1に示す
A、Bのモールドパウダーを用いて、表2に示す鋳造速
度および水蒸気分圧の条件で鋼を連続鋳造し、表2に示
すサイズの鋳片を製造した。表2には、得られた鋳片の
縦割れ発生個数、それぞれのモールドパウダーを乾燥雰
囲気でイメージ加熱炉により溶融凝固させた場合の表面
粗さr2、所定の水蒸気分圧として溶融凝固させた場合
の表面粗さr3、および、連続鋳造後の実機から凝固し
たモールドパウダーを回収して測定した表面粗さr1を
併せて示す。なお、表2に示したr1〜r3の値は、そ
れぞれ10ヶ所以上で測定された表面粗さの平均値であ
る。Next, examples of the present invention will be described. Using mold powders A and B shown in Table 1, steel was continuously cast under the conditions of casting speed and steam partial pressure shown in Table 2, to produce cast pieces having the sizes shown in Table 2. Table 2 shows the number of vertical cracks generated in the obtained slab, the surface roughness r2 when each mold powder was melt-solidified by an image heating furnace in a dry atmosphere, and the case where the melt was solidified at a predetermined steam partial pressure. And the surface roughness r1 measured by collecting and solidifying the mold powder from the actual machine after continuous casting. The values of r1 to r3 shown in Table 2 are the average values of the surface roughness measured at 10 or more locations.
【0022】表2より、雰囲気中の水蒸気分圧を0.0
5〜0.7atmに制御し、凝固したモールドパウダー
の表面粗さを5μm以上とした場合には、鋳片の縦割れ
発生個数が大幅に減少していることがわかる。また、表
2にr3/r2およびr1/r3の値を示すが、これら
の平均値は1.3および2.00であり、r3=1.3
×r2、r1=2.0×r3の近似式を適用可能なこと
が確認された。According to Table 2, the partial pressure of water vapor in the atmosphere was set to 0.0
When the surface roughness of the solidified mold powder is controlled to 5 μm or more by controlling the solidified mold powder to 5 to 0.7 atm, it can be seen that the number of vertical cracks in the slab is greatly reduced. Table 2 shows the values of r3 / r2 and r1 / r3, the average values of which are 1.3 and 2.00, and r3 = 1.3.
It was confirmed that the approximate expression of × r2, r1 = 2.0 × r3 was applicable.
【0023】[0023]
【表1】 [Table 1]
【0024】[0024]
【表2】 [Table 2]
【0025】[0025]
【発明の効果】本発明によれば、モールドパウダー中に
結晶相が析出しやすく、モールドパウダーにより緩冷却
を有効に行なうことができるので、表面縦割れの極めて
少ない鋼の鋳片を製造することができる連続鋳造方法を
提供することができる。すなわち、無手入れ圧延が可能
な鋳片を安定して製造することができ、歩留まりの向
上、製造コストの低減等、その工業的効果は非常に大き
い。さらに、モールドパウダー中に結晶相を効率よく析
出させることができるので、環境へのF排出量低減も期
待することができる。According to the present invention, it is possible to produce a steel slab having extremely few surface vertical cracks, since a crystal phase is easily precipitated in the mold powder, and the mold powder can be slowly cooled effectively. Can be provided. That is, a cast slab that can be maintained without rolling can be stably manufactured, and its industrial effects such as improvement in yield and reduction in manufacturing cost are extremely large. Furthermore, since the crystal phase can be efficiently precipitated in the mold powder, a reduction in the amount of F discharged to the environment can be expected.
【図1】表1のAに示すモールドパウダーを用いて鋼を
連続鋳造した場合における、鋳型近傍の水蒸気分圧と、
得られた鋳片に生じた表面縦割れ個数との関係を示す
図。FIG. 1 shows a partial pressure of steam near a mold when steel is continuously cast using a mold powder shown in A of Table 1.
The figure which shows the relationship with the number of surface vertical cracks produced in the obtained slab.
【図2】水蒸気分圧0.3atmの雰囲気で、種々の表
面粗さのモールドパウダーを用いて鋼を連続鋳造した場
合における、モールドパウダーの表面粗さと、鋳片表面
の縦割れ個数との関係を示す図。FIG. 2 shows the relationship between the surface roughness of mold powder and the number of vertical cracks on the slab surface when steel is continuously cast using mold powders of various surface roughnesses in an atmosphere with a steam partial pressure of 0.3 atm. FIG.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 日野 光兀 宮城県仙台市青葉区荒巻字青葉02 東北大 学大学院工学研究科内 (72)発明者 長坂 徹也 宮城県仙台市青葉区荒巻字青葉02 東北大 学大学院工学研究科内 Fターム(参考) 4E004 MB14 MC02 MC30 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hikaru Hino 02 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi Pref.Graduate School of Engineering, Tohoku University (72) Tetsuya Nagasaka, Aoba 02, Aramaki, Aoba-ku, Sendai, Miyagi F-term in the Graduate School of Engineering, Tohoku University 4E004 MB14 MC02 MC30
Claims (2)
方法であって、鋳型近傍における雰囲気中の水蒸気分圧
を0.05〜0.7atmとして連続鋳造を行なうこと
を特徴とする鋼の連続鋳造方法。1. A continuous casting method for steel using a mold powder, wherein the continuous casting is performed by setting a partial pressure of water vapor in an atmosphere near a mold to 0.05 to 0.7 atm. Method.
面粗さが5μm以上となるように連続鋳造を行なうこと
を特徴とする請求項1に記載の鋼の連続鋳造方法。2. The continuous casting method for steel according to claim 1, wherein the continuous casting is performed so that the solidified mold powder has a surface roughness of 5 μm or more.
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009006388A (en) * | 2007-06-29 | 2009-01-15 | Nippon Steel Corp | Continuous casting method of steel |
JP2012213784A (en) * | 2011-03-31 | 2012-11-08 | Nippon Steel Corp | Continuous casting method of copper |
JP2021065906A (en) * | 2019-10-23 | 2021-04-30 | 品川リフラクトリーズ株式会社 | Mold powder |
CN113305274A (en) * | 2020-02-26 | 2021-08-27 | 宝山钢铁股份有限公司 | Medium carbon steel covering slag for continuous casting of wide and thick plates |
JP7097198B2 (en) | 2018-03-14 | 2022-07-07 | 日鉄建材株式会社 | Mold powder |
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CN113305274A (en) * | 2020-02-26 | 2021-08-27 | 宝山钢铁股份有限公司 | Medium carbon steel covering slag for continuous casting of wide and thick plates |
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