JPH05228598A - Production of continuously cast slab having excellent internal quality - Google Patents
Production of continuously cast slab having excellent internal qualityInfo
- Publication number
- JPH05228598A JPH05228598A JP3350492A JP3350492A JPH05228598A JP H05228598 A JPH05228598 A JP H05228598A JP 3350492 A JP3350492 A JP 3350492A JP 3350492 A JP3350492 A JP 3350492A JP H05228598 A JPH05228598 A JP H05228598A
- Authority
- JP
- Japan
- Prior art keywords
- casting
- tundish
- molten steel
- reduction
- slab
- 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.)
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Links
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- Continuous Casting (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、内部品質に優れた連続
鋳造鋳片の製造方法に関し、特に、中心偏析やポロシテ
ィが改善された連続鋳造鋳片の製造方法に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a continuously cast ingot having excellent internal quality, and more particularly to a method for producing a continuously cast ingot having improved center segregation and porosity.
【０００２】[0002]
【従来の技術】従来より、連続鋳造鋳片（以下鋳片と言
う）の中心部に生じる中心偏析やポロシティを低減する
ための技術が提案されている。例えば、特公昭62-34460
号公報には、溶鋼を電磁攪拌により攪拌して鋳造組織の
微細化を図ることに加え、鋳片凝固末期部の固相線のク
レータエンドから上流側に向かって少なくとも 2ｍの範
囲を、 450mm以下のロールピッチに設定された圧下ロー
ルによって圧下率 0.5mm／ｍ以上で軽圧下し、これによ
って、鋳片に生じるバルジングを防止するとともに、鋳
片中心部の固液共存相内溶鋼の流動を防止し、偏析のな
い連続鋳造鋳片を製造する方法が提供されている。2. Description of the Related Art Conventionally, there has been proposed a technique for reducing center segregation and porosity generated at the center of a continuously cast slab (hereinafter referred to as slab). For example, Japanese Examined Japanese Patent Sho 62-34460
In the gazette, in addition to refining the cast structure by stirring molten steel with electromagnetic stirring, a range of at least 2 m from the crater end to the upstream side of the solidus line at the final stage of solidification of the slab is 450 mm or less. With a reduction roll set to a roll pitch of 0, the reduction rate is 0.5 mm / m or more, and light reduction is performed, which prevents bulging that occurs in the slab and prevents the flow of molten steel in the solid-liquid coexisting phase at the center of the slab. However, a method for producing a continuously cast slab without segregation is provided.
【０００３】また、本出願人は、上記特公昭62-34460号
公報に開示されている鋳片の製造方法では、圧下ロール
のロール径が 450mm以下の小径ロールとなることから、
厚さに比べて幅が大きいスラブ鋳片、あるいは鋳片断面
形状が正方形に近いブルームやビレットに対しては、中
心偏析やポロシティが充分に改善され難いことを知見
し、先に、これらの鋳片に適用して充分に中心偏析やポ
ロシティを改善し得る内部品質に優れた連続鋳造鋳片の
製造方法を発明し出願した（特願平 2−143598号参
照）。Further, the applicant of the present invention, in the method for producing a cast piece disclosed in the above Japanese Patent Publication No. 62-34460, since the roll diameter of the reduction roll is a small diameter roll of 450 mm or less,
We found that center segregation and porosity were difficult to be sufficiently improved for slab casts having a width larger than the thickness, or for blooms and billets whose cast cross-sections were close to square. We have invented and filed a method for producing a continuously cast slab with excellent internal quality that can be applied to a piece to sufficiently improve center segregation and porosity (see Japanese Patent Application No. 2-143598).
【０００４】[0004]
【発明が解決しようとする課題】周知のように、連続鋳
造による鋳片の製造は、取鍋内の溶鋼をタンディッシュ
を介して鋳型に注湯し、鋳型内で冷却して凝固殻を形成
させるとともに鋳型の下方へ引抜き、さらに鋳型下方の
冷却帯で冷却して製造されている。そして、従来より、
鋳造初期にはタンディッシュのレンガ等による吸熱があ
ってタンディッシュ内溶鋼の過熱度（ΔＴ）が大きく低
下し、また鋳造終了時にはタンディッシュ内の溶鋼量の
減少に伴ってやはりタンディッシュ内溶鋼の過熱度（Δ
Ｔ）が大きく低下する現象が発生していた。そしてこの
ため、これらの現象が起こる非定常部位では、鋳片内の
凝固末期位置が変動することから上述した内部品質に優
れた連続鋳造鋳片の製造方法を的確に適用することが難
しく、中心偏析やポロシティの改善が充分になされない
上に、圧下による内部割れの懸念がある。また上記非定
常部位を除いた定常部位であっても、タンディッシュ内
の過熱度（ΔＴ）が比較的大きく変動する場合には、同
様の理由から、中心偏析やポロシティの改善が充分にな
されていないことがある。As is well known, in the production of a slab by continuous casting, molten steel in a ladle is poured into a mold through a tundish and cooled in the mold to form a solidified shell. It is manufactured by pulling it down the mold and cooling it in a cooling zone below the mold. And from the past,
At the beginning of casting, the superheat degree (ΔT) of the molten steel in the tundish is greatly reduced due to heat absorption by the tundish bricks, etc. At the end of casting, the amount of molten steel in the tundish is also reduced and Superheat (Δ
There was a phenomenon that T) was greatly reduced. And for this reason, in the unsteady part where these phenomena occur, it is difficult to accurately apply the method for producing a continuously cast slab excellent in internal quality described above because the final solidification position in the slab varies, In addition to insufficient segregation and improvement of porosity, there is a concern of internal cracking due to rolling. In addition, even if the above-mentioned unsteady region is excluded, if the degree of superheat (ΔT) in the tundish relatively varies, center segregation and porosity are sufficiently improved for the same reason. Sometimes there is not.
【０００５】本発明は、上記の問題点に鑑みてなされた
ものであって、その目的は、連続鋳造における鋳造初期
および鋳造終了時の所謂非定常部位の鋳片の中心偏析や
ポロシティを改善し得ると同時に、圧下による内部割れ
の無い内部品質に優れた連続鋳造鋳片の製造方法を提供
することである。The present invention has been made in view of the above problems, and an object thereof is to improve center segregation and porosity of a so-called unsteady portion of a slab at the beginning of casting and the end of casting in continuous casting. At the same time, it is to provide a method for producing a continuously cast slab that is excellent in internal quality without internal cracking due to rolling.
【０００６】[0006]
【課題を解決するための手段】上記の目的を達成するた
めに、本発明の内部品質に優れた連続鋳造鋳片の製造方
法は、タンディッシュに付帯した加熱装置によってタン
ディッシュ内の溶鋼を加熱し、鋳造初期および鋳造終了
時のタンディッシュ内溶鋼の過熱度の大きな低下を抑制
するとともに、その間の鋳造中のタンディッシュ内溶鋼
の過熱度の変動幅を小さく制御して鋳型に注湯する一
方、鋳型から引き抜かれた鋳片の凝固末期部に鋳片の厚
さの２〜５倍の直径を有する圧下ロールを２乃至３段配
設し、１段目の圧下ロールの圧下率を 1.5〜 4.0％に、
２段目の圧下ロールの圧下率を 2.0〜 4.5％に設定して
圧下するものである。In order to achieve the above object, a method for producing a continuously cast slab having excellent internal quality according to the present invention is to heat molten steel in a tundish with a heating device attached to the tundish. While suppressing a large decrease in the degree of superheat of molten steel in the tundish at the beginning of casting and at the end of casting, while controlling the fluctuation range of the degree of superheat of molten steel in the tundish during casting to be small while pouring into the mold. , 2 to 3 stages of reduction rolls having a diameter of 2 to 5 times the thickness of the slab are arranged at the final stage of solidification of the slab extracted from the mold, and the reduction ratio of the first stage reduction roll is 1.5 to To 4.0%,
The reduction rate of the second-stage reduction roll is set to 2.0 to 4.5% for reduction.
【０００７】そして、上記内部品質に優れた連続鋳造鋳
片の製造方法においては、鋳造初期および鋳造終了時を
除く間のタンディッシュ内溶鋼の過熱度の変動幅は、±
2℃以内に制御することが望ましい。In the method for producing a continuously cast slab having excellent internal quality, the fluctuation range of the superheat degree of the molten steel in the tundish during the period excluding the initial stage of casting and the end of casting is ±
It is desirable to control within 2 ℃.
【０００８】また、上記３段目の圧下ロールによる圧下
を行う場合は、その圧下率を 2.0〜4.5％に設定して圧
下することが望ましい。Further, when performing the reduction by the third-stage reduction roll, it is desirable to set the reduction rate to 2.0 to 4.5% and perform the reduction.
【０００９】[0009]
【作用】本発明では、取鍋より受湯したタンディッシュ
内溶鋼を、タンディッシュに付帯した加熱装置によって
加熱し得るので、鋳造初期および鋳造終了時のタンディ
ッシュ内溶鋼の過熱度（ΔＴ）の大きな低下が抑制で
き、またその間の鋳造中のタンディッシュ内溶鋼の過熱
度（ΔＴ）も変動幅を小さく制御できる。そして、この
ように制御したタンディッシュ内溶鋼を鋳型に注湯し、
且つ、鋳型から引き抜かれた鋳片の凝固末期部に鋳片の
厚さの２〜５倍の直径を有する圧下ロールを２乃至３段
配設し、１段目の圧下ロールの圧下率を 1.5〜 4.0％
に、２段目の圧下ロールの圧下率を 2.0〜 4.5％に設定
して圧下するので、鋳造初期から鋳造終了までの鋳片全
長に渡って中心偏析やポロシティが改善されると同時に
圧下による内部割れの懸念も無くなる。In the present invention, the molten steel in the tundish received from the ladle can be heated by the heating device attached to the tundish, so that the degree of superheat (ΔT) of the molten steel in the tundish at the beginning and end of casting can be controlled. A large decrease can be suppressed, and the fluctuation range of the superheat degree (ΔT) of the molten steel in the tundish during casting can be controlled to be small. Then, the molten steel in the tundish controlled in this way is poured into the mold,
In addition, 2 to 3 stages of reduction rolls having a diameter of 2 to 5 times the thickness of the slab are arranged at the final stage of solidification of the slab extracted from the mold, and the reduction ratio of the first reduction roll is 1.5. ~ 4.0%
In addition, since the reduction ratio of the second-stage reduction roll is set to 2.0-4.5%, the center segregation and porosity are improved over the entire length of the slab from the beginning of casting to the end of casting, and at the same time the internal reduction There is no concern about cracking.
【００１０】そして、上記の作用を効果的に得るために
は、鋳造初期および鋳造終了時を除く間のタンディッシ
ュ内溶鋼の過熱度の変動幅を± 2℃以内に制御すること
が望ましく、この範囲内であれば、より安定して中心偏
析やポロシティが改善されると同時に圧下による内部割
れの懸念も無くなる。In order to obtain the above effect effectively, it is desirable to control the fluctuation range of the superheat degree of the molten steel in the tundish within ± 2 ° C except during the initial stage of casting and the end of casting. Within the range, center segregation and porosity are more stably improved, and at the same time, there is no concern about internal cracking due to rolling.
【００１１】次に、本発明における圧下ロールの径、圧
下率などの特定理由を説明するが、これらは、本出願人
が先に出願（特願平 2−143598号）した発明に述べた理
由と同様であって、圧下ロールの径を鋳片厚さの２〜５
倍の範囲に特定した理由は、２倍未満では、未凝固部の
断面積圧縮量，未凝固部の変形量が小さく中心偏析等の
改善効果が期待できなくなり、一方、５倍以上になる
と、圧下ロール間隔が大きくなりすぎ、圧下ロール間で
鋳片のバルジングが生じ、鋳片の凝固末期部の圧下作用
が充分に得られなくなるためで、２〜５倍の範囲内であ
れば、これらの問題が無くなるためである。Next, the specific reasons such as the diameter of the reduction roll and the reduction rate in the present invention will be explained. These are the reasons described in the invention previously filed by the applicant (Japanese Patent Application No. 2-143598). And the diameter of the reduction roll is 2 to 5 of the thickness of the slab.
The reason why the double range is specified is that if it is less than 2 times, the cross-sectional area compression amount of the unsolidified portion and the amount of deformation of the unsolidified portion are small and improvement effects such as center segregation cannot be expected, while if it is 5 times or more, This is because the interval between the pressing rolls becomes too large, bulging of the slab occurs between the pressing rolls, and the pressing action at the final solidification stage of the slab cannot be sufficiently obtained. This is because the problem disappears.
【００１２】また、１段目の圧下ロールの圧下率を 1.5
〜 4.0％に特定した理由は、圧下率が 1.5％未満では圧
下が少なく偏析、特にＶ偏析が発生し、一方、圧下率が
4.0％超では圧下が大きくなりすぎ内部割れを生じるた
めで、圧下率が 1.5〜 4.0％の範囲内であれば、これら
の問題が無くなるためである。The rolling reduction of the first rolling roll is 1.5
The reason for specifying to 4.0% is that when the rolling reduction is less than 1.5%, the rolling reduction is small and segregation, particularly V segregation occurs, while the rolling reduction is
If it exceeds 4.0%, the rolling reduction becomes too large and internal cracking occurs, and if the rolling reduction is within the range of 1.5 to 4.0%, these problems will disappear.
【００１３】また、２段目の圧下ロールの圧下率を 2.0
〜 4.5％に特定した理由は、圧下率が 2.0％未満では１
段目の圧下ロールの場合と同様に圧下が少なく偏析、特
にＶ偏析が発生し、一方、圧下率が 4.5％超では圧下が
大きくなりすぎ内部割れを生じると共に、未凝固溶鋼が
上流に流れ逆Ｖ偏析が生じるためで、圧下率が 2.0〜4.
5％の範囲内であれば、これらの問題が無くなるためで
ある。Further, the reduction ratio of the second-stage reduction roll is 2.0
The reason for specifying ~ 4.5% is 1 if the rolling reduction is less than 2.0%.
As in the case of the third-stage rolling roll, the reduction is small and segregation, especially V segregation occurs. On the other hand, if the reduction ratio exceeds 4.5%, the reduction becomes too large and internal cracking occurs, and unsolidified molten steel flows upstream. Because of V segregation, the rolling reduction is 2.0 to 4.
This is because these problems will disappear if it is within the range of 5%.
【００１４】またさらに、３段目の圧下ロールを設け圧
下を加えるのであれば、上記１段および２段の圧下に加
え、圧下率で 2.0〜 4.5％の圧下を加えるとよい。その
理由は、２段目の圧下ロールによる圧下で十分ではある
が、より中心偏析やポロシティが改善されるためで、圧
下率が 2.0％未満では改善効果が得られず、また 4.5％
を超えると圧下が大きくなりすぎ内部割れを生じると共
に、未凝固溶鋼が上流に流れ逆Ｖ偏析が生じるためであ
る。Furthermore, if a third-stage reduction roll is provided and reduction is performed, it is preferable to add reduction of 2.0 to 4.5% in terms of reduction rate in addition to the reductions of the first and second stages. The reason is that the reduction by the second-stage reduction roll is sufficient, but the center segregation and porosity are further improved. If the reduction ratio is less than 2.0%, the improvement effect cannot be obtained, and 4.5%.
This is because the rolling reduction becomes excessively large and internal cracking occurs, and the unsolidified molten steel flows upstream and reverse V segregation occurs.
【００１５】また、圧下をかける位置は、連続鋳造され
る鋳片の凝固末期部であるが、好ましくは、一般に用い
られている下記凝固の式により求められる等軸晶開始点
の前後から凝固終了点（クレーターエンド）までの長さ
（ａ）の間がよく、１段目の圧下ロールはａ〜ａ／２の
範囲に設けるとよい。 （凝固の式） χ＝Ｋ（Ａ／Ｖ）-1/2 χ：凝固シェル厚さ（mm） Ｋ：凝固係数（mm・ min-1/2） Ａ：メニスカスからの距離（ｍ） Ｖ：鋳造速度（ｍ／ min）The position where the reduction is applied is the final stage of solidification of the continuously cast slab, but preferably the solidification ends before and after the equiaxed crystal starting point obtained by the following commonly used solidification equation. The length (a) to the point (crater end) is good, and the first-stage pressing roll is preferably provided in the range of a to a / 2. (Formulation of solidification) χ = K (A / V) -1/2 χ: Solidification shell thickness (mm) K: Solidification coefficient (mm · min -1/2 ) A: Distance from meniscus (m) V: Casting speed (m / min)
【００１６】[0016]
【実施例】以下、本発明の実施例を説明する。２ストラ
ンド用タンディッシュに出力が自動コントロールできる
溝型誘導過熱式ヒータを埋設し、また、鋳型下方の冷却
帯に図１に示す３段圧下装置を配設し、これらを用いて
下表に示す鋼種を断面 300× 430mm2 の鋳片を連続鋳造
した。なお、図１において、１は凝固末期部における鋳
片、２は鋳片内の未凝固溶鋼部、３はロール径が1000mm
の圧下ロール、４は上圧下ロール３を圧下するためのシ
リンダを示す。EXAMPLES Examples of the present invention will be described below. A two-strand tundish is embedded with a groove-type induction heating heater capable of automatically controlling the output, and the three-stage rolling-down device shown in Fig. 1 is arranged in the cooling zone below the mold. A steel piece having a cross section of 300 × 430 mm 2 was continuously cast. In FIG. 1, 1 is a cast piece in the final stage of solidification, 2 is an unsolidified molten steel portion in the cast piece, 3 is a roll diameter of 1000 mm
The rolling rolls 4 and 4 are cylinders for rolling down the upper rolling roll 3.
【００１７】[0017]
【表１】 [Table 1]
【００１８】〔従来例〕タンディッシュ内の上記鋼種の
溶鋼を、溝型誘導過熱式ヒータを使用せずに従来通りの
条件で溶鋼過熱度（ΔＴ）を30℃に保持するようにして
鋳型に注湯する一方、１ストランドは鋳造速度0.72ｍ／
分で且つ圧下ロールを使用し、１段目の圧下率を 2.5
％、２段目の圧下率を 2.7％に設定して連続鋳造した。
またもう１ストランドは鋳造速度0.72ｍ／分で圧下ロー
ルを使用せずに連続鋳造した。[Conventional Example] Molten steel of the above-mentioned steel types in a tundish is cast into a mold by keeping the molten steel superheat degree (ΔT) at 30 ° C. under the conventional condition without using a groove-type induction heating heater. While pouring, the casting speed of one strand is 0.72 m /
Minute and using a reduction roll, the reduction rate of the first stage is 2.5
%, The second stage rolling reduction was set to 2.7%, and continuous casting was performed.
The other strand was continuously cast at a casting speed of 0.72 m / min without using a reduction roll.
【００１９】上記によって得られた鋳片の長手方向の C
偏析最大比（最大 C偏析／平均 C偏析）を調査した。そ
の結果を図２にタンディッシュ内溶鋼過熱度（ΔＴ）の
測定結果と併せて示す。C in the longitudinal direction of the slab obtained above
The maximum segregation ratio (maximum C segregation / average C segregation) was investigated. The results are shown in FIG. 2 together with the measurement results of the molten steel superheat degree (ΔT) in the tundish.
【００２０】図２より明らかなように、タンディッシュ
内溶鋼過熱度（ΔＴ）は、鋳造初期の鋳片長さで約15ｍ
の長さの間と、鋳造終了時の約10ｍの間で大きく変動
し、鋳造初期にはΔＴ＝10℃まで低下した。また鋳造終
了時も徐々にではあるがΔＴ＝10℃まで低下した。そし
てこの部位の C偏析最大比は、圧下ロールを使用したに
も関わらず、僅かに改善された程度であって依然大きな
値を示した。その偏析状態を図３ａに示す。As is clear from FIG. 2, the molten steel superheat degree (ΔT) in the tundish is about 15 m in the length of the slab in the early stage of casting.
During the casting and about 10 m at the end of casting, the value fluctuated to ΔT = 10 ° C at the beginning of casting. At the end of casting, the temperature gradually decreased to ΔT = 10 ° C. The maximum C segregation ratio at this part was slightly improved and still showed a large value, despite the use of the reduction roll. The segregated state is shown in FIG. 3a.
【００２１】〔実施例１〕タンディッシュ内の上記鋼種
の溶鋼を溝型誘導過熱式ヒータによって加熱し、溶鋼過
熱度（ΔＴ）を30℃に保持して鋳型に注湯する一方、１
ストランドは鋳造速度0.72ｍ／分で且つ圧下ロールを使
用し、１段目の圧下率を 2.5％、２段目の圧下率を 2.7
％に設定して連続鋳造した（本発明例１）。またもう１
ストランドは鋳造速度0.72ｍ／分で圧下ロールを使用せ
ずに連続鋳造した（比較例１）。[Example 1] Molten steel of the above steel types in a tundish is heated by a groove-type induction heating heater to keep the molten steel superheat (ΔT) at 30 ° C and pour into a mold, while
Strands are cast at a casting speed of 0.72 m / min and use a reduction roll. The reduction rate of the first stage is 2.5% and the reduction rate of the second stage is 2.7%.
%, And continuous casting was performed (invention example 1). Another one again
The strand was continuously cast at a casting speed of 0.72 m / min without using a reduction roll (Comparative Example 1).
【００２２】上記によって得られた鋳片の長手方向の C
偏析最大比を調査した。その結果を図４にタンディッシ
ュ内溶鋼過熱度の測定結果と併せて示す。C in the longitudinal direction of the slab obtained as described above
The maximum segregation ratio was investigated. The result is shown in FIG. 4 together with the measurement result of the molten steel superheat degree in the tundish.
【００２３】図４より明らかなように、本発明例１で
は、溝型誘導過熱式ヒータを使用することにより、上記
従来例に見られるような鋳造初期におけるタンディッシ
ュ内溶鋼の過熱度（ΔＴ）の低下が防止され、また鋳造
終了時においてもその低下が小さく抑えられ、これに加
えて、圧下ロールを使用することにより偏析が鋳片全長
に渡って改善されることが分かる。またさらに、鋳片中
心部にはポロシティや内部割れも観察されなかった。As is apparent from FIG. 4, in Example 1 of the present invention, the superheat degree (ΔT) of the molten steel in the tundish in the early stage of casting as seen in the above-mentioned conventional example is used by using the groove type induction heating heater. It can be seen that the decrease in the slab is prevented, and the decrease is suppressed even at the end of casting. In addition, segregation is improved over the entire length of the slab by using the reduction roll. Furthermore, neither porosity nor internal cracking was observed in the center of the slab.
【００２４】〔実施例２〕タンディッシュ内の上記鋼種
の溶鋼を溝型誘導過熱式ヒータによって加熱し、溶鋼過
熱度（ΔＴ）を15℃に保持して鋳型に注湯すると共に鋳
造速度0.76ｍ／分で鋳造する以外は、上記実施例１と同
じ条件で１ストランドを圧下ロールを使用し（本発明例
２）、もう１ストランドを圧下ロールを使用せず（比較
例２）に連続鋳造を行い、得られた鋳片も同様に調査し
た。その結果を図５にタンディッシュ内溶鋼過熱度の測
定結果と併せて示す。[Embodiment 2] Molten steel of the above steel types in a tundish is heated by a groove-type induction heating heater to keep the molten steel superheat (ΔT) at 15 ° C and pour into a mold and a casting speed of 0.76 m. / Strand was used under the same conditions as in Example 1 above, except that one strand was used as a reduction roll (Invention Example 2) and another strand was not used as a reduction roll (Comparative Example 2) for continuous casting. The cast piece obtained was examined in the same manner. The result is shown in FIG. 5 together with the measurement result of the molten steel superheat degree in the tundish.
【００２５】図５より明らかなように、本発明例２で
は、上記本発明例１と同様に、溝型誘導過熱式ヒータを
使用したので、上記従来例に見られるような鋳造初期に
おけるタンディッシュ内溶鋼の過熱度（ΔＴ）の低下が
防止され、また鋳造終了時においてもその低下が小さく
抑えられ、これに加えて、圧下ロールを使用することに
より偏析が鋳片全長に渡って改善されるとともに、さら
に図３ｂに示す本発明例２の鋳片断面のマクロ組織より
明らかなように、鋳片中心部の等軸晶が多くなりより偏
析が改善されることが分かる。As is apparent from FIG. 5, in Example 2 of the present invention, as in Example 1 of the present invention, since the groove-type induction heating heater was used, the tundish in the early stage of casting as seen in the above-mentioned conventional example. A decrease in the superheat degree (ΔT) of the in-molten steel is prevented, and the decrease is suppressed even at the end of casting. In addition, segregation is improved over the entire length of the slab by using a reduction roll. At the same time, as is clear from the macrostructure of the ingot cross section of Inventive Example 2 shown in FIG.
【００２６】[0026]
【発明の効果】上述したように、本発明に係わる内部品
質に優れた連続鋳造鋳片の製造方法によれば、中心偏析
やポロシティが比較的少ない、且つ内部割れのない内部
品質に優れた連続鋳造鋳片が製造できる。また、タンデ
ィッシュに付帯した加熱装置によって、タンディッシュ
内溶鋼の過熱度を低くして一定に保持し得るので、安定
した低温鋳造が行え鋳片中心部に等軸晶を多く生成させ
ることができ、より偏析が改善された連続鋳造鋳片が製
造できる。As described above, according to the method for producing a continuously cast slab having excellent internal quality according to the present invention, continuous segregation having a relatively small center segregation and porosity and being excellent in internal quality without internal cracking. Cast slabs can be manufactured. Further, since the heating device attached to the tundish can keep the superheat degree of the molten steel in the tundish low and keep it constant, stable low temperature casting can be performed and a large amount of equiaxed crystals can be generated in the center of the slab. A continuous cast slab with improved segregation can be manufactured.
【図１】本発明に係わる３段圧下装置の概要図である。FIG. 1 is a schematic view of a three-stage rolling-down device according to the present invention.
【図２】従来例による鋳片長手方向に対するタンディッ
シュ内溶鋼の過熱度および C偏析最大比の関係を示すグ
ラフ図である。FIG. 2 is a graph showing a relationship between a superheat degree and a maximum C segregation ratio of molten steel in a tundish with respect to a longitudinal direction of a slab according to a conventional example.
【図３】鋳片の金属組織図であって、（ａ）は従来法に
よる鋳片の金属組織図、（ｂ）は本発明例による鋳片の
金属組織図である。FIG. 3 is a metallographic view of a slab, where (a) is a metallographic diagram of a slab according to a conventional method and (b) is a metallographic diagram of a slab according to the present invention.
【図４】本発明の実施例による鋳片長手方向に対するタ
ンディッシュ内溶鋼の過熱度および C偏析最大比の関係
を示すグラフ図である。FIG. 4 is a graph showing the relationship between the degree of superheat of molten steel in a tundish and the maximum C segregation ratio with respect to the longitudinal direction of a slab according to an example of the present invention.
【図５】本発明の他の実施例による鋳片長手方向に対す
るタンディッシュ内溶鋼の過熱度および C偏析最大比の
関係を示すグラフ図である。FIG. 5 is a graph showing the relationship between the degree of superheat of molten steel in the tundish and the maximum C segregation ratio with respect to the longitudinal direction of the slab according to another embodiment of the present invention.
１：凝固末期部における鋳片 ２：鋳片内の未凝
固溶鋼部 ３：圧下ロール ４：圧下シリンダ1: Cast piece at the final stage of solidification 2: Non-solidified molten steel part in cast piece 3: Reduction roll 4: Reduction cylinder
─────────────────────────────────────────────────────
─────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成４年１１月２６日[Submission date] November 26, 1992
【手続補正１】[Procedure Amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】図３[Name of item to be corrected] Figure 3
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【図３】 鋳片の金属組織を示す図面代用写真であっ
て、（ａ）は従来法による鋳片の金属組織を示す図面代
用写真、（ｂ）は本発明例による鋳片の金属組織を示す
図面代用写真である。FIG. 3 is a drawing-substituting photograph showing the metallographic structure of a slab, where (a) is a drawing-representation showing the metallographic structure of a slab by a conventional method
Showing use photos, the slab of the metal structure by (b) the present invention embodiment
It is a drawing substitute photograph .
【手続補正２】[Procedure Amendment 2]
【補正対象書類名】図面[Document name to be corrected] Drawing
【補正対象項目名】図３[Name of item to be corrected] Figure 3
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【図３】 [Figure 3]
Claims (3)
ってタンディッシュ内の溶鋼を加熱し、鋳造初期および
鋳造終了時のタンディッシュ内溶鋼の過熱度の大きな低
下を抑制するとともに、その間の鋳造中のタンディッシ
ュ内溶鋼の過熱度の変動幅を小さく制御して鋳型に注湯
する一方、鋳型から引き抜かれた鋳片の凝固末期部に鋳
片の厚さの２〜５倍の直径を有する圧下ロールを２乃至
３段配設し、１段目の圧下ロールの圧下率を 1.5〜 4.0
％に、２段目の圧下ロールの圧下率を 2.0〜 4.5％に設
定して圧下することを特徴とする内部品質に優れた連続
鋳造鋳片の製造方法。1. The molten steel in the tundish is heated by a heating device attached to the tundish to suppress a large decrease in the degree of superheat of the molten steel in the tundish at the beginning of casting and at the end of casting, and the tundish during casting during that time is suppressed. While controlling the fluctuation range of the superheat degree of the molten steel in the dish to be small and pouring it into the mold, at the end of solidification of the cast piece pulled out from the mold, a reduction roll having a diameter of 2 to 5 times the thickness of the cast piece is installed. Two to three stages are installed, and the reduction ratio of the first stage rolling roll is 1.5 to 4.0.
%, And the reduction ratio of the second-stage reduction roll is set to 2.0 to 4.5% for reduction, and a continuous cast slab having excellent internal quality is produced.
ンディッシュ内溶鋼の過熱度の変動幅を± 2℃以内に制
御する請求項１記載の内部品質に優れた連続鋳造鋳片の
製造方法。2. The method for producing a continuously cast slab having excellent internal quality according to claim 1, wherein the fluctuation range of the superheat degree of the molten steel in the tundish is controlled within ± 2 ° C. except during the initial stage of casting and the end of casting. ..
4.5％に設定して圧下する請求項１または２記載の内部
品質に優れた連続鋳造鋳片の製造方法。3. The rolling reduction of the third rolling roll is 2.0 to
The method for producing a continuously cast slab having excellent internal quality according to claim 1 or 2, wherein the slab is reduced to 4.5%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3350492A JPH05228598A (en) | 1992-02-20 | 1992-02-20 | Production of continuously cast slab having excellent internal quality |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3350492A JPH05228598A (en) | 1992-02-20 | 1992-02-20 | Production of continuously cast slab having excellent internal quality |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05228598A true JPH05228598A (en) | 1993-09-07 |
Family
ID=12388381
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3350492A Pending JPH05228598A (en) | 1992-02-20 | 1992-02-20 | Production of continuously cast slab having excellent internal quality |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05228598A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001205407A (en) * | 2000-01-25 | 2001-07-31 | Nippon Steel Corp | Method for continuous casting of billet |
| JP2002103010A (en) * | 2000-10-03 | 2002-04-09 | Kawasaki Steel Corp | Method for producing cast billet having good machinability in center part |
| CN106232263A (en) * | 2014-05-14 | 2016-12-14 | 新日铁住金株式会社 | The continuous casing of strand |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS632209U (en) * | 1986-06-19 | 1988-01-08 | ||
| JPH0437456A (en) * | 1990-05-31 | 1992-02-07 | Kobe Steel Ltd | Production of continuously cast slab having excellent internal quality |
-
1992
- 1992-02-20 JP JP3350492A patent/JPH05228598A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS632209U (en) * | 1986-06-19 | 1988-01-08 | ||
| JPH0437456A (en) * | 1990-05-31 | 1992-02-07 | Kobe Steel Ltd | Production of continuously cast slab having excellent internal quality |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001205407A (en) * | 2000-01-25 | 2001-07-31 | Nippon Steel Corp | Method for continuous casting of billet |
| JP2002103010A (en) * | 2000-10-03 | 2002-04-09 | Kawasaki Steel Corp | Method for producing cast billet having good machinability in center part |
| JP4631145B2 (en) * | 2000-10-03 | 2011-02-16 | Ｊｆｅスチール株式会社 | Method for producing a slab with good machinability at the center |
| CN106232263A (en) * | 2014-05-14 | 2016-12-14 | 新日铁住金株式会社 | The continuous casing of strand |
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