JPH07178526A - Continuous casting method anf apparatus therefor - Google Patents

Abstract

PURPOSE:To stably obtain a cast slab having uniform composition over the whole range in the width direction without center segregation by using a mold provided with many recessed parts or recessed lines in the center part of a long side surface, thereby slowly cooling the center part of the long side surface of a slab. CONSTITUTION:This method is constituted of single or combined method by which the center part of the long side surface is slowly cooled. (a) The recessed parts are provided on the inner wall surface 11 at the center part 1h of the long side surface. The recessed parts can be provided with many fine small holes by machining of drilling machining, milling machining, etc., or shot-blasting, etc. (b) Secondary cooling water flowing density at the center part 9i in the slab width is defined as <=75% of water flowing density at the part 9c except the center part. The secondary cooling spraying is executed by the method such as water spraying, mist spraying so that the piping systems for secondary cooling water are separated from each other in both zone. (c) A heat-insulating layer consisting of low thermal-conductive material is provided at the part in contact with the center part 6h of the slab width of a supporting roll, reduction roll and drawing roll for continuous casting. The formation of the heat- insulating layer is executed by thermal-spraying ceramic material or the like.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】この発明は、断面が長方形のスラ
ブの連続鋳造において、鋳片の中心偏析を防止するため
の連続鋳造方法および装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting method and apparatus for preventing center segregation of a slab in continuous casting of a slab having a rectangular cross section.

【０００２】[0002]

【従来の技術】連続鋳造法で鋳片を製造する場合には、
しばしば中心偏析と呼ばれる内部欠陥が問題となる。こ
の連続鋳造鋳片の中心偏析は、鋳片の厚み中心部にＣ，
Ｓ，Ｐ，Ｓｉ，Ｍｎなどの溶鋼成分が正偏析する現象
で、厚板用素材においては特に深刻な問題であり、偏析
部分における靭性の低下や、水素誘起割れの原因となる
ことが知られている。連続鋳造鋳片の中心偏析は、冶金
的要因のみで決まる鋼塊の場合と異なり、連鋳機特有の
機械的要因にも影響されることが多く、その発生機構は
複雑でまた形態も多様である。2. Description of the Related Art When a slab is manufactured by a continuous casting method,
Internal defects, often called central segregation, are a problem. The center segregation of the continuously cast slab is C,
This is a phenomenon in which molten steel components such as S, P, Si, and Mn are positively segregated, which is a particularly serious problem in thick plate materials, and is known to cause deterioration of toughness in the segregated portion and hydrogen-induced cracking. ing. Unlike the case of steel ingot, which is determined only by metallurgical factors, the center segregation of continuously cast slabs is often influenced by mechanical factors specific to continuous casting machines, and its generation mechanism is complicated and its morphology is diverse. is there.

【０００３】連続鋳造鋳片の中心偏析の発生には、鋳片
中心部の凝固組織の影響が大きく、凝固末期におけるデ
ンドライト樹間残溶鋼がバルジングあるいは凝固収縮等
の原因によって、マクロ的に移動することと、濃化溶鋼
が局部的に集積するために生じることが分かっている。
中心偏析防止対策の一つとしては、凝固先端部付近を何
らかの方法で圧下することによって、末期凝固部の凝固
収縮分を補償して濃化溶鋼の流動を抑制する方法が提案
されている。The occurrence of center segregation in a continuously cast slab is greatly affected by the solidification structure in the center of the slab and the dendrite residual molten steel at the end of solidification moves macroscopically due to bulging or solidification shrinkage. It is known that this occurs due to localized accumulation of concentrated molten steel.
As one of the measures for preventing the center segregation, there has been proposed a method of suppressing the flow of the concentrated molten steel by compensating for the solidification shrinkage of the final solidification portion by reducing the vicinity of the solidification tip portion by some method.

【０００４】しかし、圧下のみによる中心偏析の改善
は、ロール圧下、金型圧下のいずれの手段においても、
図１０に示すように、スラブ形状の鋳片では、幅（Ｌ）
方向の凝固不均一が不可避な場合には、幅方向全体にわ
たって中心偏析の改善が得られないという欠点を有して
いる。これは、図１０（ａ）に示すように、スラブ形状
の鋳片では、幅中央部（１／４Ｌ〜３／４Ｌ）に比較し
て幅端部（１／４Ｌ〜短辺面（エッジ）側Ａおよび３／
４Ｌ〜短辺面（エッジ）側Ｂにおいて凝固の進行が遅
く、図１０（ｂ）に示すように、幅方向で最終凝固位置
が異なるために均一な圧下ができず、図１０（ｃ）に示
すように、鋳片１０の凝固が遅れた部分で偏析２１が悪
化するというものである。However, the improvement of the center segregation by only the rolling reduction can be achieved by any means of rolling reduction and die reduction.
As shown in FIG. 10, with the slab-shaped slab, the width (L)
If solidification nonuniformity in the direction is unavoidable, there is a drawback that improvement of the center segregation cannot be obtained over the entire width direction. As shown in FIG. 10 (a), in the slab-shaped slab, the width end portion (1/4 L to short side surface (edge)) is larger than the width center portion (1/4 L to 3/4 L). Side A and 3 /
From 4L to the short side surface (edge) side B, the progress of coagulation is slow, and as shown in FIG. 10 (b), the final coagulation position is different in the width direction, so uniform rolling cannot be performed. As shown, the segregation 21 deteriorates in the portion where the solidification of the slab 10 is delayed.

【０００５】この幅方向凝固不均一の起源は、鋳型内で
生じている可能性が強く、図１１に示すように、鋳型１
内で浸漬ノズル２からの溶融金属３の吐出流の当たる部
分で、凝固が遅れていると考えられる。さらに、鋳型１
内では、バルジングにより幅中央部と鋳型１の接触が良
好であるために、鋳片の幅中央近傍の方が幅端部よりも
凝固の進行が早い。また、この幅方向凝固不均一は、鋳
型１を出てからの２次冷却により、助長されるものと考
えられる。なお、４は凝固シェル、５はパウダーを示
す。It is highly possible that the origin of this non-uniform solidification in the width direction occurs in the mold, and as shown in FIG.
It is considered that the solidification is delayed in the portion where the discharge flow of the molten metal 3 from the immersion nozzle 2 hits. Furthermore, mold 1
In the inside, since the contact between the center of the width and the mold 1 is good due to bulging, the progress of solidification proceeds near the width center of the slab rather than at the width end. In addition, it is considered that this non-uniform solidification in the width direction is promoted by the secondary cooling after leaving the mold 1. In addition, 4 shows a solidification shell and 5 shows powder.

【０００６】幅方向凝固不均一解消による中心偏析の改
善方法としては、鋳片の凝固厚みが鋳片厚みの５〜９０
％に生成する区間で鋳片幅方向の凝固シェルを均一に生
長せしめるように該鋳片幅方向の冷却について夫々の位
置により強弱差を与え、しかも前記鋳片のクレーターエ
ンド付近に少なくとも２対以上の圧下ロールを配置し、
所定の圧下を加える方法（特公昭５４−３９２１６号公
報）が提案されている。この特公昭５４−３９２１６号
公報に開示の方法は、２次冷却を主眼としたものである
が、冷却に関する定量的な記述がされていないため、エ
ッジ部の中心偏析改善の再現性がなく、しかも、鋳片幅
に応じて凝固遅れ部が変わるため、それに追随するよう
な冷却制御が２次冷却のみでは非常に難しく、制御範囲
がばらつき易い。その結果、鋳片の表面割れ等、表面品
質に悪影響を及ぼすという問題点を有している。As a method of improving the center segregation by eliminating the uneven solidification in the width direction, the solidification thickness of the slab is 5 to 90 times the thickness of the slab.
%, The strength of the cooling in the width direction of the slab is varied so as to uniformly grow the solidified shell in the width direction of the slab, and at least two pairs or more are provided near the crater end of the slab. Place the reduction roll of
A method of applying a predetermined reduction (Japanese Patent Publication No. 54-39216) has been proposed. The method disclosed in Japanese Patent Publication No. 54-39216 focuses on secondary cooling, but since quantitative description of cooling is not given, there is no reproducibility of improvement of center segregation at the edge portion, Moreover, since the solidification delay portion changes depending on the width of the slab, it is very difficult to control the cooling so as to follow it by only the secondary cooling, and the control range tends to vary. As a result, there is a problem that the surface quality of the slab, such as surface cracking, is adversely affected.

【０００７】また、本願出願人の出願に関わる特願平４
−２４７６０号に示されるような鋳型長辺側の幅中央部
の凝固の進行の早い部分のみ、図１８に示すとおり、鋳
片の厚みを大きくとる段差厚鋳型が提案されている（段
差部１ｇ）。しかし、この方法では、鋳型１の段差部１
ｇの厚みを少なくとも３ｍｍ以上設定することが必要で
あるため、鋳片パスラインの設定が困難であり、段差部
１ｇでの鋳片バルジングにより内部割れを誘発しやすい
という問題点を有していた。さらに、この方法は鋳片の
幅替えに対応しにくく、実用的でなかった。[0007] Further, Japanese Patent Application No. Hei.
No. 24760, there is proposed a step thickness mold in which the thickness of the slab is increased as shown in FIG. 18 only in the part where the solidification progresses in the width center part on the long side of the mold (step part 1g ). However, in this method, the step portion 1 of the mold 1 is
Since it is necessary to set the thickness of g at least 3 mm or more, it is difficult to set the slab pass line, and there is a problem in that slab bulging at the step portion 1g easily induces internal cracking. . Furthermore, this method is not practical because it is difficult to change the width of the slab.

【０００８】また、鋳型直下から引き抜き方向に配列さ
れたガイドロールの鋳片厚さ方向の間隔を段階的に増加
させてバルジングを生ぜしめ、スラブ鋳片の厚さを前記
鋳型短辺の２〜３倍としたのち、クレータエンド付近に
おいて小径ロールにより軽圧下を行う方法（特開平１−
１７８３５５号公報、材料とプロセスｖｏｌ．２（１９
８９），ｐ１１５９）が提案されている。しかし、この
特開平１−１７８３５５号公報等に開示の方法では、バ
ルジングという現象が鋳片まかせであるので、未凝固厚
みが安定的には一定にならない。また、太鼓型スラブを
圧下するため、幅中央部の圧下量が大きくなり、幅方向
で均一圧下をするのは困難である。Further, the interval between the guide rolls arranged in the drawing direction immediately below the casting mold in the thickness direction of the cast piece is gradually increased to cause bulging, and the thickness of the slab cast piece is set to 2 to the short side of the mold. After triple the amount, a method of performing light reduction with a small-diameter roll near the crater end (JP-A-1-
178355, Material and Process vol. 2 (19
89), p1159) have been proposed. However, in the method disclosed in Japanese Patent Laid-Open No. 1-178355 and the like, the phenomenon of bulging is left to the slab, so the unsolidified thickness is not stable and stable. Further, since the drum-shaped slab is rolled down, the rolling down amount at the width center portion becomes large, and it is difficult to carry out uniform rolling down in the width direction.

【０００９】また、他の方法としては、鋳型内部の全面
もしくは一部に均等に配置された多数の凹部を包含し、
前記凹部の直径もしくは幅が２．５ｍｍ以下であり、か
つ前記鋳型の内面の該凹部を含む部分における該凹部総
面積の占める比率が２０％以上９０％以下である鋳型
（特公昭５７−１１７３５号公報）、鋳型表面の鋳型内
溶鋼のメニスカス近傍に、深さ０．５〜１．０ｍｍ、幅
０．３〜１．０ｍｍの切り欠き部を設け、前記切り欠き
部を鋳片引き抜き方向と平行に５〜１０ｍｍの間隔で配
置し、かつ、鋳造時の鋳造速度（Ｖｃ）と鋳型振動周期
（ｆ）との関係を、１０＞Ｖｃ／ｆ×１０００を満足さ
せる方法（特開平２−６０３７号公報）等が提案されて
いる。Another method is to include a large number of recesses evenly arranged on the entire surface or a part of the inside of the mold,
A mold in which the diameter or width of the recess is 2.5 mm or less, and the ratio of the total area of the recess in the inner surface of the mold including the recess is 20% or more and 90% or less (Japanese Patent Publication No. 57-11735). Gazette), a notch having a depth of 0.5 to 1.0 mm and a width of 0.3 to 1.0 mm is provided in the vicinity of the meniscus of molten steel in the mold on the surface of the mold, and the notch is parallel to the slab drawing direction. At a distance of 5 to 10 mm and satisfying the relation between the casting speed (Vc) and the mold vibration period (f) during casting to be 10> Vc / f × 1000 (Japanese Patent Laid-Open No. 2-6037). Gazette) etc. have been proposed.

【００１０】[0010]

【発明が解決しようとする課題】上記特公昭５７−１１
７３５号公報、特開平２−６０３７号公報等に開示の方
法は、鋳型の溶鋼側の面に凹部ゾーンを設置して初期凝
固域を緩冷却するもので、鋳型内面と溶鋼との接触部の
面積率を低下させることにより全体として緩冷却を行
い、抜熱量のムラを少なくすることにより、縦割れ等の
表面疵を防止しようというものである。しかし、これら
の方法は、いずれも初期凝固域での溶鋼の全体的な緩冷
却により縦割れ等の表面疵防止を主目的としたものであ
るため、長辺面全体にわたって凹部が設置されており、
特定部位に凹部ゾーンを設置する発想は見当たらない。
連続鋳造における鋳片の中心偏析を改善するには、凝固
末期における軽圧下が有効であることが知られている。
しかし、単に軽圧下を行うのみでは、スラブの幅方向で
不均一凝固が生じた場合に、幅方向全域にわたっての中
心偏析改善効果が期待できないという問題点を有する。[Problems to be Solved by the Invention] Japanese Patent Publication No. 57-11
The method disclosed in Japanese Patent Laid-Open No. 735, JP-A No. 2-6037, etc. is to provide a concave zone on the surface of the mold on the molten steel side to gently cool the initial solidification zone, and to prevent the contact between the inner surface of the mold and the molten steel. By reducing the area ratio, gentle cooling is performed as a whole, and unevenness in the amount of heat removal is reduced to prevent surface defects such as vertical cracks. However, since all of these methods are mainly intended to prevent surface flaws such as vertical cracks by the overall slow cooling of molten steel in the initial solidification region, recesses are installed over the entire long side surface. ,
There is no idea of setting a recessed zone at a specific site.
It is known that a light reduction at the final stage of solidification is effective for improving the center segregation of the slab in continuous casting.
However, there is a problem in that, if only the light reduction is performed, the effect of improving the center segregation over the entire width direction cannot be expected when uneven solidification occurs in the width direction of the slab.

【００１１】この発明の目的は、連続鋳造におけるスラ
ブの中心偏析改善に対する軽圧下の効果を有効に機能さ
せるために、スラブ幅方向の不均一凝固を解消できる連
続鋳造方法および装置を提供することにある。An object of the present invention is to provide a continuous casting method and apparatus capable of eliminating uneven solidification in the slab width direction in order to effectively function the effect of light reduction for improving the center segregation of the slab in continuous casting. is there.

【００１２】[0012]

【課題を解決するための手段】本発明者らは、上記目的
を達成すべく鋭意試験研究を重ねた結果、溶鋼が鋳型内
を通過するときの凝固および鋳型の抜熱の態様と中心偏
析との関係について下記のような知見を得た。スラブの
幅端部近傍では、後述する２つの作用の相乗効果によ
り、幅中央部に比べ未凝固厚みが大きい。すなわち、
（１）浸漬ノズルからの溶鋼吐出流が短辺にあたり、そ
の近傍である幅端部近傍で凝固の進行が遅れる作用と、
（２）バルジングにより幅中央部の凝固シェルは鋳型と
の接触が良好であるが、一方、幅端部での凝固シェルは
鋳型との接触が悪いことにより、幅端部近傍は幅中央部
よりも相対的に凝固が遅れる作用の相乗効果による。Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, solidification when molten steel passes through the mold, heat removal of the mold, and center segregation. The following findings have been obtained regarding the relationship. In the vicinity of the width end portion of the slab, the unsolidified thickness is larger than that in the width center portion due to the synergistic effect of two actions described below. That is,
(1) The action that the molten steel discharge flow from the immersion nozzle hits the short side, and the progress of solidification is delayed in the vicinity of the width end, which is the vicinity thereof,
(2) Due to bulging, the solidified shell at the center of the width has good contact with the mold, while the solidified shell at the width end has poor contact with the mold. Also due to the synergistic effect of the relative delay of coagulation.

【００１３】このような鋳型内における長辺面の幅方向
の凝固不均一は、凝固末期まで残存し、軽圧下による凝
固収縮分の補償を行っても凝固の遅れた部分で偏析が悪
化する。そこで、この長辺面の幅方向の凝固挙動の不均
一を補正する緩冷却作用を幅中央部に与えることによっ
て、幅方向全体にわたって抜熱作用を均一に維持できる
こととなり、均一な圧下が可能となることを究明し、こ
の発明に到達した。Such non-uniform solidification in the width direction of the long side surface in the mold remains until the final stage of solidification, and segregation deteriorates in the part where solidification is delayed even if compensation for the solidification shrinkage due to light pressure is performed. Therefore, by providing a gentle cooling action for correcting the unevenness of the solidification behavior in the width direction of the long side surface to the central portion of the width, the heat removal action can be maintained uniformly over the entire width direction, and a uniform reduction is possible. It was clarified that it became, and this invention was reached.

【００１４】すなわち本願の第１発明は、スラブ形状の
鋳片の連続鋳造方法において、スラブ長辺面の中央部を
中央部以外に比較して緩冷却することを特徴とする連続
鋳造方法である。That is, the first invention of the present application is a continuous casting method for continuously casting a slab-shaped slab, characterized in that the central portion of the long side surface of the slab is gently cooled as compared with a portion other than the central portion. .

【００１５】また、本願の第２発明は、スラブ長辺面の
中央部を中央部以外に比較して緩冷却する方法におい
て、鋳型の鋳込み方向に沿った長辺面の中央部に多数の
凹部または凹条を設け、長辺面中央部の鋳型冷却水流速
を中央部以外の冷却水流速の７０％以下にすることを特
徴とする連続鋳造方法である。The second invention of the present application is a method for slowly cooling the central portion of the long side surface of the slab as compared with the central portion other than the central portion, wherein a large number of concave portions are formed in the central portion of the long side surface along the casting direction of the mold. Alternatively, the continuous casting method is characterized in that a recessed line is provided and the mold cooling water flow velocity in the central portion of the long side surface is set to 70% or less of the cooling water flow velocity in the portions other than the central portion.

【００１６】さらに、本願の第３発明は、スラブ長辺面
の中央部を中央部以外に比較して緩冷却する方法におい
て、スラブ幅中央部の２次冷却水量密度を中央部以外の
水量密度の７５％以下にすることを特徴とする連続鋳造
方法である。Further, the third invention of the present application is a method for slowly cooling the central portion of the long side surface of the slab as compared with the central portion other than the central portion, wherein the secondary cooling water amount density of the central portion of the slab width is changed to the water amount density other than the central portion. Is less than 75% of the continuous casting method.

【００１７】さらにまた、本願の第４発明は、相対向す
る一対の長辺面と相対向する一対の短辺面によって鋳造
空間を画定する内壁が形成される断面長方形のスラブの
連続鋳造用鋳型において、鋳込み方向に沿った長辺面の
中央部に多数の凹部または凹条を設けたことを特徴とす
る連続鋳造用鋳型である。Furthermore, the fourth invention of the present application is a mold for continuous casting of a slab having a rectangular cross section in which an inner wall defining a casting space is formed by a pair of long side surfaces facing each other and a pair of short side surfaces facing each other. In the above, there is provided a continuous casting mold characterized in that a large number of concave portions or concave lines are provided in the central portion of the long side surface along the casting direction.

【００１８】本願の第５発明は、鋳込み方向に沿った長
辺面の中央部に多数の凹部または凹条を設けた連続鋳造
用鋳型において、引き抜き方向に沿ってメニスカス近傍
から鋳型出側までの間のみに多数の凹部または凹条を設
けたことを特徴とする連続鋳造用鋳型である。According to a fifth aspect of the present invention, in a continuous casting mold in which a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction, from the vicinity of the meniscus to the mold outlet side along the drawing direction. The continuous casting mold is characterized in that a large number of recesses or grooves are provided only in the spaces.

【００１９】また、本願の第６発明は、鋳込み方向に沿
った長辺面の中央部に多数の凹部または凹条を設けた連
続鋳造用鋳型において、長辺面中央部の鋳型冷却水の面
と鋳型溶鋼面の距離が中央部以外の鋳型冷却水の面と鋳
型溶鋼面の距離よりも５ｍｍ以上大きくなっていること
を特徴とする連続鋳造用鋳型である。The sixth invention of the present application is a continuous casting mold in which a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction. And the distance between the molten steel surface of the mold and the molten steel surface of the mold other than the central portion are larger than the distance between the molten steel surface and the molten steel surface by 5 mm or more.

【００２０】さらに、本願の第７発明は、スラブ形状の
鋳片の連続鋳造用の支持ロール、圧下ロールおよび引抜
ロールであって、ロールのスラブ幅中央部に接する部分
に低熱伝導率材料からなる断熱層を設けたことを特徴と
する連続鋳造用ロールである。Further, a seventh invention of the present application is a support roll, a reduction roll and a drawing roll for continuous casting of a slab-shaped slab, which is made of a material having a low thermal conductivity in a portion in contact with the central portion of the slab width of the roll. A roll for continuous casting, characterized in that a heat insulating layer is provided.

【００２１】さらにまた、本願の第８発明は、スラブ形
状の鋳片の連続鋳造用の支持ロール、圧下ロールおよび
引抜ロールであって、ロールのスラブ幅中央部に接する
部分に多数の凹部または凹条を設けたことを特徴とする
連続鋳造用ロールである。Furthermore, the eighth invention of the present application is a support roll, a reduction roll and a drawing roll for continuous casting of slab-shaped slabs, wherein a large number of recesses or depressions are provided in a portion in contact with the slab width central portion of the roll. A continuous casting roll characterized by having a strip.

【００２２】本願の第９発明は、スラブ長辺面の中央部
を中央部以外に比較して緩冷却する連続鋳造方法におい
て、鋳型の鋳込み方向に沿った長辺面の中央部に多数の
凹部または凹条を設け、スラブ幅中央部の２次冷却水量
密度を中央部以外の水量密度の７５％以下にすることを
特徴とする連続鋳造方法である。A ninth invention of the present application is a continuous casting method in which the central portion of the long side surface of the slab is slowly cooled as compared with the central portion other than the central portion, and a large number of concave portions are formed in the central portion of the long side surface along the casting direction of the mold. Alternatively, the continuous casting method is characterized in that a recessed line is provided and the secondary cooling water amount density in the central portion of the slab width is set to 75% or less of the water amount density other than the central portion.

【００２３】また、本願の第１０発明は、スラブ長辺面
の中央部を中央部以外に比較して緩冷却する連続鋳造装
置において、鋳型の鋳込み方向に沿った長辺面の中央部
に多数の凹部または凹条を設けると共に、支持ロール、
圧下ロールおよび引抜ロールのスラブ幅中央部に接する
部分に多数の凹部を設けたことを特徴とする連続鋳造装
置である。Further, the tenth invention of the present application is a continuous casting apparatus for gently cooling the central portion of the long side surface of the slab as compared with the central portion other than the central portion, in which a large number are provided at the central portion of the long side surface along the casting direction of the mold. And the support roll,
The continuous casting apparatus is characterized in that a large number of concave portions are provided in portions of the pressing roll and the drawing roll which are in contact with the central portion of the slab width.

【００２４】さらに、本願の第１１発明は、スラブ長辺
面の中央部を中央部以外に比較して緩冷却する連続鋳造
方法において、支持ロール、圧下ロールおよび引抜ロー
ルのスラブ幅中央部に接する部分に多数の凹部を設ける
と共に、スラブ幅中央部の２次冷却水量密度を中央部以
外の水量密度の７５％以下にすることを特徴とする連続
鋳造方法である。Furthermore, the eleventh invention of the present application is in contact with the central portion of the slab width of the support roll, the pressing roll and the drawing roll in the continuous casting method in which the central portion of the long side surface of the slab is slowly cooled compared to the central portion other than the central portion. The continuous casting method is characterized in that a large number of recesses are provided in the portion and the secondary cooling water amount density in the central part of the slab width is set to 75% or less of the water amount density in the parts other than the central part.

【００２５】さらにまた、本願の第１２発明は、スラブ
長辺面の中央部を中央部以外に比較して緩冷却する連続
鋳造方法において、鋳型の鋳込み方向に沿った長辺面の
中央部に多数の凹部または凹条を設け、支持ロール、圧
下ロールおよび引抜ロールのスラブ幅中央部に接する部
分に多数の凹部を設けると共に、スラブ幅中央部の２次
冷却水量密度を中央部以外の水量密度の７５％以下にす
ることを特徴とする連続鋳造方法である。Furthermore, the twelfth invention of the present application is a continuous casting method in which the central portion of the long side surface of the slab is slowly cooled as compared with the central portion other than the central portion, in the central portion of the long side surface along the casting direction of the mold. A large number of recesses or grooves are provided, and a large number of recesses are provided in the portions of the supporting roll, the pressing roll, and the drawing roll that are in contact with the central portion of the slab width. Is less than 75% of the continuous casting method.

【００２６】[0026]

【作用】図１０（ａ）に示すとおり、従来のスラブの連
続鋳造においては、スラブの幅端部近傍（図中Ａ，Ｂ）
で凝固が遅れ、これが原因となって幅端部近傍の中心偏
析が悪化する。この不均一凝固の態様は、図１０（ｂ）
に示すように縦断面ではＷ型のクレーターエンド形状を
していることからＷ型不均一凝固と呼称することにす
る。本発明者らは、スラブ幅方向の不均一凝固と幅端部
および幅中央部の中心偏析の関係を調査した。図１９に
末期凝固部で軽圧下を行った時の鋳片幅方向の未凝固厚
み差Ｄ_max−Ｄ_minと鋳片エッジより１５０ｍｍ位置およ
び幅中央部のＣの中心偏析度の関係を示す。ここで、未
凝固厚み差Ｄ_max−Ｄ_minとは、鋳片の幅方向の不均一凝
固量を指数化したもので、図１７に示すようにスラブ幅
方向の最大未凝固厚みＤ_maxと最小未凝固厚みＤ_minの差
をとったものである。また、本発明では、軽圧下ゾーン
における均一圧下が主眼であるので、軽圧下ゾーン入り
側における鋳片幅方向の未凝固厚み差Ｄ_max−Ｄ_minの値
を採用した。未凝固厚みは、ＦｅＳ添加法、Ｐｂ添加
法、鋲打法、ストランド電磁撹拌によるホワイトバンド
（ＷＢ法）等により測定することができる。中心偏析の
程度を示すＣ偏析度（Ｃ／Ｃ₀）は、鋳片幅中央部の中
心偏析部のＣ濃度を発光分析法で１０点測定し、その中
のピーク値Ｃと鋼の平均Ｃ濃度Ｃ₀の比として評価し
た。As shown in FIG. 10 (a), in the conventional continuous casting of the slab, the vicinity of the width end of the slab (A and B in the figure)
The solidification is delayed at this point, which causes the center segregation near the width end to deteriorate. The mode of this uneven solidification is shown in FIG.
As shown in FIG. 5, the vertical cross section has a W-shaped crater end shape, and is therefore referred to as W-shaped non-uniform solidification. The present inventors investigated the relationship between the uneven solidification in the slab width direction and the center segregation of the width end and the width center. FIG. 19 shows the relationship between the unsolidified thickness difference D _max -D _{min in the} width direction of the slab and the center segregation degree of C at the position 150 mm from the slab edge and at the center of the width when light reduction is performed at the final stage solidification part. Here, the unsolidified thickness difference D _max -D _min is an index of the uneven solidified amount in the width direction of the slab, and as shown in FIG. 17, the maximum unsolidified thickness D _max and the minimum unsolidified thickness in the slab width direction. This is the difference in the unsolidified thickness D _min . Further, in the present invention, since the main purpose is uniform reduction in the light reduction zone, the value of the unsolidified thickness difference _{Dmax- Dmin in} the width direction of the cast piece on the entry side of the light reduction zone is adopted. The unsolidified thickness can be measured by a FeS addition method, a Pb addition method, a rivet driving method, a white band (WB method) by electromagnetic stirring of a strand, or the like. The C segregation degree (C / C ₀ ) indicating the degree of center segregation is measured by measuring the C concentration in the center segregation part at the center of the slab width by emission spectrometry at 10 points, and the peak value C and the average C of the steel. It was evaluated as the ratio of the concentration C ₀ .

【００２７】図１９に示すとおり、幅端部と幅中央部の
Ｃ偏析度（Ｃ／Ｃ₀）を共にほぼ１．０として幅全体に
わたって中心偏析を好転する範囲は、−２≦Ｄ_max−Ｄ
_min≦２であることが明らかとなった。これは、図１２
（ａ）に示すように幅方向の凝固が均一であるために、
軽圧下が均一に行われたからである。また、鋳片幅方向
の未凝固厚み差Ｄ_max−Ｄ_min＞２の範囲では、Ｄ_max−
Ｄ_minが大きくなるにつれて幅中央部ではＣ偏析度（Ｃ
／Ｃ₀）が若干増加するのみであるが、幅端部近傍のＣ
偏析度（Ｃ／Ｃ₀）が顕著に増加する。幅端部近傍のＣ
偏析度（Ｃ／Ｃ₀）が大きく増加するのは、図１２
（ｂ）に示すように凝固プロフィールが幅端部近傍で凝
固が遅れるＷ型不均一凝固となるために幅端部に圧下が
及ばないためである。幅中央部のＣ偏析度（Ｃ／Ｃ₀）
が微増するのは、幅方向の不均一圧下のために、幅方向
の溶鋼流動が生じるためである。[0027] As shown in FIG. 19, the range of improvement center segregation across the width together as approximately 1.0 C a segregation ratio (C / C ₀₎ of the width end and the width central portion, -2 ≦ D _max - D
It became clear that _min ≦ 2. This is shown in FIG.
Since the solidification in the width direction is uniform as shown in (a),
This is because the light reduction was performed uniformly. Further, in the range of the unsolidified thickness difference D _max −D _min > 2 in the width direction of the cast slab, D _max −
As the D _min increases, the C segregation degree (C
/ C ₀ ) only slightly increases, but C near the width end
The segregation degree (C / C ₀ ) significantly increases. C near the width edge
FIG. 12 shows that the segregation degree (C / C ₀ ) greatly increases.
This is because, as shown in (b), the solidification profile is a W-shaped non-uniform solidification in which solidification is delayed in the vicinity of the width end, so that the width end is not rolled down. Degree of C segregation in the width center (C / C ₀ )
Is slightly increased because the molten steel flows in the width direction due to the non-uniform reduction in the width direction.

【００２８】さらに、鋳片幅方向の未凝固厚み差Ｄ_max
−Ｄ_min＜−２の範囲では、Ｄ_max−Ｄ_minが小さくなる
につれて幅中央部、幅端部共にＣ偏析度（Ｃ／Ｃ₀）は
微増するが、実用上問題となる範囲までは増加しなかっ
た。また、鋳片幅方向の未凝固厚み差Ｄ_max−Ｄ_min＜−
２の範囲でのＣ偏析度（Ｃ／Ｃ₀）は、ほぼ均一であ
り、Ｄ_max−Ｄ_min＞２の範囲のように幅端部のＣ偏析度
（Ｃ／Ｃ₀）が大きく悪化するということはなかった。
この領域での凝固プロフィールは、図１２（ｃ）のよう
になる。この凝固形態は、クレーターエンド形状が縦断
面ではＵ型となることからＵ型不均一凝固と呼称するこ
とにする。すなわち、Ｕ型不均一凝固は、幅端部近傍が
先に凝固完了し、最後に幅中央部が凝固完了するという
凝固態様となるため、幅端部近傍で軽圧下が効き易く、
幅中央部で軽圧下が効き難いということになる。この場
合も幅方向の軽圧下としては、不均一圧下であるため
に、幅方向の溶鋼流動によってＣ偏析度（Ｃ／Ｃ₀）は
微増する。しかし、幅端部の凝固完了後も幅中央部に
は、圧下が及ぶため、それほど顕著にはＣ偏析度（Ｃ／
Ｃ₀）は悪化しない。Ｗ型不均一凝固（図１２（ｂ））
とＵ型不均一凝固（図１２（ｃ））では、同じ不均一圧
下でも最後に凝固する部位３ａ（図１２（ｂ）では幅端
部，図１２（ｃ）では幅中央部）への圧下の効く度合い
が異なるのは次の理由による。すなわち、Ｗ型不均一凝
固（図１２（ｂ））の場合の幅中央部の凝固完了後の幅
端部は、圧下抵抗の大きい領域４ａが３ヵ所あるのに対
し、Ｕ型不均一凝固（図１２（ｃ））の場合の幅端部の
凝固完了後の幅中央部は、圧下抵抗の大きい領域４ａが
２ヵ所で済むためである。Further, the unsolidified thickness difference D _{max in the} width direction of the cast piece
In the range of −D _min <-2, the C segregation degree (C / C ₀ ) in both the width center part and the width end part slightly increases as D _max −D _min decreases, but increases to a range that poses a practical problem. I didn't. In addition, the difference in unsolidified thickness in the width direction of the slab D _max −D _min <−
The C segregation degree (C / C ₀ ) in the range of 2 is substantially uniform, and the C segregation degree (C / C ₀ ) at the width end is greatly deteriorated as in the range of D _max -D _min > 2. There was no such thing.
The coagulation profile in this region is as shown in FIG. This solidification form will be referred to as U-shaped non-uniform solidification because the crater end shape is U-shaped in the vertical cross section. That is, the U-shaped non-uniform solidification has a solidification mode in which solidification is completed first in the vicinity of the width end and finally solidification is completed in the width center, so that light reduction easily occurs near the width end,
It means that it is difficult to apply light reduction at the center of the width. Also in this case, since the light reduction in the width direction is a non-uniform reduction, the C segregation degree (C / C ₀ ) slightly increases due to the molten steel flow in the width direction. However, even after the completion of solidification at the width end portion, the reduction occurs in the width center portion, so that the C segregation degree (C /
C ₀ ) does not get worse. W-type non-uniform solidification (Fig. 12 (b))
In the case of U-shaped non-uniform solidification (FIG. 12 (c)), even if the same non-uniform pressure is applied, the final solidification is performed on the portion 3a (width end in FIG. 12 (b), center width in FIG. 12 (c)). The effectiveness of is different for the following reasons. That is, in the case of W-shaped non-uniform solidification (FIG. 12 (b)), the width end after the completion of solidification of the width center part has three regions 4a with large reduction resistance, whereas the U-shaped non-uniform solidification ( This is because, in the case of FIG. 12C, the central portion of the width after the completion of the solidification of the width end portion requires only two regions 4a having a large reduction resistance.

【００２９】以上のことから、スラブの中心偏析防止で
避けるべきは、鋳片幅方向の未凝固厚み差Ｄ_max−Ｄ_min
＞２の範囲であり、理想的には−２≦Ｄ_max−Ｄ_min≦２
の範囲であるが、Ｄ_max−Ｄ_min≦２にすれば、スラブ幅
方向に亘って中心偏析が抑制された鋳片が得られること
になる。幅方向全体の中心偏析を抑制するためには、現
状におけるＷ型不均一凝固（図１２（ｂ））に示すよう
な凝固プロフィールを、鋳片の冷却を幅方向にわたって
制御して均一凝固（図１２（ａ））、Ｕ型不均一凝固
（図１２（ｃ））のように変えることが重要であり、そ
の中でも特にスラブの幅中央部の緩冷却が極めて効果的
である。From the above, what should be avoided in preventing the center segregation of the slab is the difference in unsolidified thickness D _max -D _{min in the} width direction of the slab.
> 2, ideally −2 ≦ D _max −D _min ≦ 2
However, if D _max −D _min ≦ 2, a slab with center segregation suppressed in the slab width direction can be obtained. In order to suppress center segregation in the entire width direction, the solidification profile as shown in the current W-type non-uniform solidification (Fig. 12 (b)) is controlled by cooling the slab in the width direction to obtain uniform solidification (Fig. 12 (a)) and U-type non-uniform solidification (FIG. 12 (c)) are important, and in particular, gentle cooling of the central portion of the width of the slab is extremely effective.

【００３０】この発明における緩冷却を行う鋳片幅中央
部とは、スラブの鋳型内における幅方向の凝固プロフィ
ールの一例を概念的に示す図１０（ａ）の例では、鋳型
内において長辺面の幅をＷとして、短辺面エッジＡより
１／２０Ｌおよび１９／２０Ｌ位置の凝固シェル厚が幅
方向で最小（未凝固厚が最大Ｄｍａｘ）なり、１／２０
Ｌ→１／４Ｌの間および１９／２０Ｌ→３／４Ｌの間は
シェル厚が増加する。そして、１／４Ｌ〜３／４Ｌの間
では凝固シェル厚が幅方向で最大（未凝固厚が最小Ｄｍ
ｉｎ）であり、ほぼ一定となる。したがって、図１に示
すように、鋳片の抜熱能分布を幅方向の凝固プロフィー
ルに応じて設定することにより図１２（ａ）に示すよう
に、凝固シェル４厚が幅方向でほぼ一定となり、未凝固
厚みの幅方向一定制御が可能となる。すなわち、緩冷却
を行うべき幅中央部は、１／４Ｌ〜３／４Ｌ近傍のこと
であり、さらには、幅方向凝固プロフィールを事前に調
査しておき、凝固進行の早い部分を緩冷却するのが好ま
しい。なお、鋳片幅中央部の緩冷却は、理想的には幅方
向の未凝固厚を一定値にするためのものであるが、不幸
にも幅中央の緩冷却をしすぎてＵ型不均一凝固となって
も、前記したとおり中心偏析が実用上問題になることは
なく、Ｗ型不均一凝固よりも好ましい凝固プロフィール
を得ることができる。In the example of FIG. 10 (a) which conceptually shows an example of the solidification profile in the width direction of the slab in the mold, the slab width center portion for gentle cooling in the present invention has a long side surface in the mold. Is W, and the solidified shell thickness at positions 1 / 20L and 19 / 20L from the short side edge A is the minimum in the width direction (the maximum unsolidified thickness is Dmax),
The shell thickness increases between L → 1 / 4L and between 19 / 20L → 3 / 4L. And between 1 / 4L and 3 / 4L, the solidified shell thickness is maximum in the width direction (the unsolidified thickness is the minimum Dm.
in), which is almost constant. Therefore, by setting the heat removal capacity distribution of the slab according to the solidification profile in the width direction as shown in FIG. 1, the thickness of the solidified shell 4 becomes substantially constant in the width direction as shown in FIG. It becomes possible to control the unsolidified thickness in the width direction. That is, the central part of the width where the slow cooling should be performed is in the vicinity of 1 / 4L to 3 / 4L, and further, the width direction solidification profile is investigated in advance, and the portion where the solidification progresses quickly is slowly cooled. Is preferred. The gentle cooling of the slab width center is ideally for keeping the unsolidified thickness in the width direction at a constant value, but unfortunately, the gradual cooling of the width center is too much to make the U-shaped uneven. Even if solidification occurs, center segregation does not pose a practical problem as described above, and a solidification profile more preferable than W-type nonuniform solidification can be obtained.

【００３１】図２０に鋳片凝固開始位置から鋳片凝固終
了位置までの幅中央部の緩冷却率Ｓ．Ｃ．Ｒ．と鋳片幅
方向の未凝固厚み差Ｄ_max−Ｄ_minの関係を示す。ここ
で、Ｓ．Ｃ．Ｒ．は（１）式により求められる。 Ｓ．Ｃ．Ｒ．（％）＝Ｑ_s／Ｑ_c×１００ （１）式 Ｑ_s：鋳片幅中央部緩冷却を行った場合の鋳片凝固開始
位置から軽圧下を行うまでの幅中央部の熱流速の平均値
（ｋｃａｌ／ｍ²・ｈｒ） Ｑ_c：鋳片幅方向冷却制御を行わない場合（従来法）の
鋳片凝固開始位置から軽圧下を行うまでの幅中央部の熱
流速の平均値（ｋｃａｌ／ｍ²・ｈｒ） なお、Ｑ_sとＱ_cの比較は、同一サイズ、同一鋼種、同一
鋳造速度、同一溶鋼過熱度が前提である。FIG. 20 shows the slow cooling rate S.E. at the center of the width from the slab solidification start position to the slab solidification end position. C. R. And the unsolidified thickness difference _{Dmax- Dmin in} the slab width direction are shown. Here, S. C. R. Is calculated by the equation (1). S. C. R. (%) = Q _s / Q _c × 100 (1) Formula Q _s : Average of heat flow velocity in the center of width from the solidification start position of the slab to the case of performing mild reduction when the slab width center is gently cooled Value (kcal / m ² · hr) Q _c : Average value of heat flow velocity (kcal) at the center of the width from the solidification start position of the slab to the light reduction when the slab width direction cooling control is not performed (conventional method) / M ² · hr) Note that the comparison of Q _s and Q _c is based on the same size, the same steel type, the same casting speed, and the same molten steel superheat degree.

【００３２】図２０の例では、Ｓ．Ｃ．Ｒ．を９０％以
下にすることで、幅方向全体の中心偏析が良好となる未
凝固厚み差Ｄ_max−Ｄ_min≦２の範囲にすることが可能で
あった。また、幅中央部の緩冷却化は、図１に示すよう
に、鋳型１（図１（ａ））、２次冷却装置９（図１
（ｂ））、連鋳用ロール６，７，８（図１（ｃ））等ど
の部位で行ってもＳ．Ｃ．Ｒ．を９０％以下にするのが
可能である。さらに、緩冷却の方法としては、鋳型の内
壁（溶鋼面）やロールの表面に凹部あるいは凹条（以下
凹部という）を設置する方法、鋳型の冷却水流速を幅中
央部のみ小さくする方法、鋳型の内壁（溶鋼面）やロー
ルの表面にセラミックス溶射、メッキ等、低熱伝導率材
料による緩冷却層を設置する方法等、いずれの方法でも
よい。In the example shown in FIG. C. R. Was 90% or less, it was possible to achieve a range of unsolidified thickness difference D _max −D _min ≦ 2 in which the center segregation in the entire width direction was good. Further, as shown in FIG. 1, the cooling in the central portion of the width is performed by the mold 1 (FIG. 1A), the secondary cooling device 9 (FIG.
(B)), continuous casting rolls 6, 7, 8 (FIG. 1 (c)), the S. C. R. Can be 90% or less. Furthermore, as a method of gentle cooling, a method of installing a recess or a groove (hereinafter referred to as a recess) on the inner wall of the mold (molten steel surface) or the surface of the roll, a method of reducing the cooling water flow velocity of the mold only in the width center, Any method may be used, such as a method of installing a slow cooling layer made of a low thermal conductivity material such as ceramics spraying or plating on the inner wall (molten steel surface) or the surface of the roll.

【００３３】スラブ長辺面の緩冷却の効果は、凝固シェ
ル厚が小さく、熱抵抗の小さい領域である程大きい。こ
のような観点からいうと鋳型内で緩冷却のための対策を
講じるのが最も効果的である。さらに、本発明者らは、
緩冷却の中でも、エアーギャップを故意に設ける方法が
最も効果的であることを知見した。The effect of gentle cooling of the long side surface of the slab becomes greater as the solidified shell thickness becomes smaller and the heat resistance becomes smaller. From this point of view, it is most effective to take measures for gentle cooling in the mold. Furthermore, the inventors
It was found that the method of intentionally providing the air gap is the most effective in the slow cooling.

【００３４】本願の第１発明においては、スラブ長辺面
の中央部を中央部以外に比較して緩冷却にすることによ
って、スラブ鋳片の幅中央部の抜熱量がそれ以外の部分
よりも小さくなるから、スラブ長辺面の幅方向の凝固が
ほぼ均一となり、軽圧下ゾーンにおける均一圧下が可能
で、スラブの幅方向全体の中心偏析を抑制することがで
きる。In the first invention of the present application, the central portion of the long side surface of the slab is cooled more slowly than the central portion, so that the heat removal amount in the central portion of the width of the slab slab is larger than that in other portions. Since it becomes smaller, solidification in the width direction of the long side surface of the slab becomes substantially uniform, uniform reduction in the light reduction zone is possible, and center segregation in the entire width direction of the slab can be suppressed.

【００３５】本願の第２発明においては、鋳型の鋳込み
方向に沿った長辺面の中央部に多数の凹部を設け、長辺
面中央部の鋳型冷却水流速を中央部以外の冷却水流速の
７０％以下にすることによって、鋳型冷却水流速ｕと鋳
型表面温度Ｔ_surfの関係を示す図２３に示すとおり、長
辺面中央部の鋳型表面温度Ｔ_surfは約１００℃上昇す
る。鋳型表面温度Ｔ_surfが上昇した場合、鋳片表面温度
も同様に上昇するために、凝固シェルの強度が小さくな
り、連鋳パウダーが凝固シェルと鋳型間に流入し易くな
ってパウダー厚みが大きくなるため、冷却水流速低減部
の緩冷却化が可能となる。しかし、鋳型冷却水流速ｕの
幅方向制御のみでは、未凝固厚み差Ｄ_max−Ｄ_minの低減
に効果を示さないが、鋳型内壁の幅中央部に凹部を設け
た鋳型を用いることによって、非常に効果を示すのであ
る。また、不均一凝固緩和能は、長辺面の中央部に多数
の凹部を設けた鋳型を用い、冷却水流速を変えなかった
場合に比べて向上しているので、鋳造速度が大きくな
り、浸漬ノズルからの溶鋼吐出流が大きくなった場合に
も対応可能である。In the second invention of the present application, a large number of concave portions are provided in the central portion of the long side surface along the casting direction of the mold, and the mold cooling water flow rate at the central portion of the long side surface is set to the cooling water flow rate other than the central portion. by 70% or less, as shown in FIG. 23 showing the relationship between the mold cooling water flow rate u and the mold surface temperature T _surf, mold surface temperature T _surf the Nagahenmen central portion rises about 100 ° C.. When the mold surface temperature T _surf rises, the slab surface temperature also rises, so the strength of the solidified shell becomes small, the continuous casting powder easily flows between the solidified shell and the mold, and the powder thickness becomes large. Therefore, the cooling water flow velocity reducing section can be gently cooled. However, although only controlling the mold cooling water flow velocity u in the width direction has no effect on reducing the unsolidified thickness difference D _max -D _min , by using a mold in which a concave portion is provided in the width center portion of the mold inner wall, Is effective. Further, the nonuniform solidification relaxation ability is improved as compared with the case where the cooling water flow rate is not changed by using a mold having a large number of recesses in the central portion of the long side surface, so that the casting speed increases and the immersion It is also possible to deal with the case where the molten steel discharge flow from the nozzle becomes large.

【００３６】図２４に本願の第２発明の長辺面の中央部
に多数の凹部を設けた鋳型および幅方向の鋳型冷却水流
速ｕのみを制御した鋳型の幅中央部と幅中央部以外の冷
却水流速比ｕ_c／ｕ_eと未凝固厚み差Ｄ_max−Ｄ_minの関係
を示す。本願の第２発明では、幅中央部の鋳型冷却水流
速ｕ_cを中央部以外の冷却水流速ｕ_eの７０％以下とする
ことにより、未凝固厚み差Ｄ_max−Ｄ_minは大幅に低減し
ている。一方、長辺面の中央部に多数の凹部を設けない
従来の鋳型を用い、幅方向の冷却水流速ｕの制御のみを
行った場合は、中央部の冷却水流速ｕ_cを１０％以下に
しても未凝固厚み差Ｄ_max−Ｄ_minはほとんど低減しな
い。長辺面中央部の鋳型冷却水流速ｕ_cを中央部以外の
冷却水流速ｕ_eの７０％以下とするには、図５に示すと
おり、鋳型１の中央部１ｊの鋳型冷却水流速ｕ_cが中央
部以外１ｋの冷却水流速ｕ_eの７０％以下となるよう
に、幅中央部１ｊと幅中央部以外１ｋとの冷却水を別の
配管系統となし、個別に冷却水流速を設定することによ
り達成することができる。FIG. 24 shows a mold in which a large number of concave portions are provided in the center of the long side surface of the second invention of the present application, and a mold center in which only the mold cooling water flow rate u in the width direction is controlled and other than the width center part. The relationship between the cooling water flow rate ratio u _c / u _e and the unsolidified thickness difference D _max -D _min is shown. In the second invention of the present application, the uncooled thickness difference D _max −D _min is significantly reduced by setting the mold cooling water flow rate u _c in the width center part to 70% or less of the cooling water flow rate u _{e in} the parts other than the center part. ing. On the other hand, when only the cooling water flow velocity u in the width direction is controlled using a conventional mold in which a large number of concave portions are not provided in the central portion of the long side surface, the cooling water flow velocity u _c in the central portion is set to 10% or less. However, the unsolidified thickness difference _{Dmax- Dmin} is hardly reduced. Nagahenmen template cooling water flow rate u _c of the central portion to 70% or less of the cooling water flow rate u _e other than the central portion, as shown in FIG. 5, the mold cooling water flow rate u _c of the central portion 1j of the mold 1 So as to be 70% or less of the cooling water flow rate u _e of 1k other than the central part, the cooling water of the width center part 1j and the cooling water of 1k other than the width center part are set as separate piping systems, and the cooling water flow speeds are individually set. Can be achieved by

【００３７】本願の第３発明においては、スラブ幅中央
部の２次冷却水量密度を中央部以外の水量密度の７５％
以下にすることによって、２次冷却水の幅中央部の水量
密度と中央部以外の水量密度比Ｑ_c／Ｑ_e×１００と未凝
固厚み差Ｄ_max−Ｄ_minの関係を示す図２７に示すとお
り、未凝固厚み差Ｄ_max−Ｄ_minを２ｍｍ以下とすること
が可能である。スラブ幅中央部の２次冷却水量密度を中
央部以外の水量密度の７５％以下にするには、図１
（ｂ）に示すようにスラブ幅中央部９ｉの水量密度（Ｌ
／ｍｉｎ・ｍ²）が中央部以外９ｃの水量密度の７５％
以下になるよう、２次冷却水の配管系統を幅中央部９ｉ
と幅中央部以外９ｃで別系統とすることにより達成する
ことができる。また、２次冷却水のスプレーの態様とし
ては、水スプレー、ミストスプレー等どの方法でも良
い。図２１（ｂ）は、本願の第３発明における２次冷却
を鋳型を出てから軽圧下終了まで適用した場合の未凝固
厚み差Ｄ_max−Ｄ_minの鋳造方向推移を示す。図２１
（ｂ）に示すとおり、未凝固厚み差Ｄ_max−Ｄ_minは、２
次冷却水量密度の幅方向制御の効果によって、鋳型を出
てから減少し、軽圧下ゾーン入り側で大きく減少し、不
均一凝固緩和能を有することが明らかである。In the third invention of the present application, the secondary cooling water amount density in the central portion of the slab width is 75% of the water amount density other than the central portion.
FIG. 27 showing the relationship between the water amount density in the width center part of the secondary cooling water and the water amount density ratio Q _c / Q _e × 100 other than the center part and the unsolidified thickness difference D _max -D _{min by} the following. As described above, it is possible to set the unsolidified thickness difference D _max −D _min to 2 mm or less. To make the secondary cooling water volume density in the central part of the slab width 75% or less of the water content density other than the central part,
As shown in (b), the water amount density (L
/ Min · m ² ) is 75% of the water density of 9c except for the central part
Connect the secondary cooling water piping system to the width center part 9i
And 9c other than the width center part can be achieved by a separate system. The secondary cooling water may be sprayed by any method such as water spray or mist spray. FIG. 21 (b) shows the transition of the unsolidified thickness difference D _max -D _{min in} the casting direction when the secondary cooling in the third invention of the present application is applied from the time when the mold is discharged until the end of the light reduction. Figure 21
As shown in (b), the unsolidified thickness difference D _max -D _min is 2
It is clear that the effect of the widthwise control of the secondary cooling water amount density is that it decreases after exiting the mold, and that it greatly decreases on the entry side of the light reduction zone, and that it has a nonuniform solidification relaxation capability.

【００３８】本願の第４発明においては、鋳込み方向に
沿った長辺面の中央部に多数の凹部を設けたことによっ
て、凹部の抜熱能が小さく、長辺面の中央部を緩冷却す
ることができ、スラブ長辺面の幅方向の凝固がほぼ均一
となり、軽圧下ゾーンにおける均一圧下が可能で、スラ
ブの幅方向全体の中心偏析を抑制することができる。本
願の第４発明の鋳型は、図２，３に示すようにスラブの
ように偏平比の高い断面長方形の鋳型であって、長辺面
１１の内壁面の特定部に凹部１ａを設けたもので、図２
は凹条１ａの場合を、図３は凹部１ａの形状がディンプ
ルである場合の一例を示すものである。いずれの場合も
凹部１ａは、ボール盤、フライス盤等による機械加工に
より得ることができる。その他にも緩冷却に必要な凹部
設置ゾーン１ｂの面積率が確保されていれば、ショット
ブラスト等により、多数の微細な小孔を設ける方法も可
能である。In the fourth invention of the present application, since a large number of recesses are provided at the center of the long side surface along the casting direction, the heat removal capability of the recesses is small and the center portion of the long side surface is cooled slowly. As a result, the solidification of the long side surface of the slab in the width direction becomes substantially uniform, uniform reduction in the light reduction zone is possible, and center segregation in the width direction of the slab can be suppressed. The mold of the fourth invention of the present application is a mold having a rectangular cross section with a high aspect ratio like a slab, as shown in FIGS. 2 and 3, in which a concave portion 1a is provided in a specific portion of the inner wall surface of the long side surface 11. Then, Fig. 2
Shows the case of the concave stripe 1a, and FIG. 3 shows an example of the case where the shape of the concave portion 1a is a dimple. In any case, the recess 1a can be obtained by machining with a drilling machine, a milling machine, or the like. In addition, if the area ratio of the recess installation zone 1b required for gentle cooling is secured, a method of providing a large number of fine small holes by shot blasting or the like is also possible.

【００３９】また、凹部の形状は、図２、図３に示す以
外に、例えば、凹条がある角度で傾斜していても効果は
同等である。ただし、あまり複雑な凹部形状は、加工上
困難で実用的でないので、図２のような凹条形状が一般
的となる。図２（ｂ）に示すような凹条１ａまたは図３
に示すような凹部１ａを設置すると、図２（ｃ）に示す
ようにエアーギャップ６₁が大きくなる。例えば、深さ
２００μｍ程度の凹条を設置すると伝熱抵抗は、図１４
に示すように凹条のない通常の鋳型と比べて２倍以上と
大幅に増加し、抜熱能が極めて小さくなり、緩冷却が可
能となる。通常の鋳型の場合は、鋳型下端におけるエア
ーギャップ量δは５０〜９０μｍと推定されるので、２
００μｍというオーダーが非常に大きいことがわかる。In addition to the shapes of the recesses shown in FIGS. 2 and 3, the same effect can be obtained even if the recesses are inclined at a certain angle. However, since a recessed shape that is too complicated is difficult to process and is not practical, a recessed stripe shape as shown in FIG. 2 is generally used. Recessed strip 1a as shown in FIG. 2 (b) or FIG.
When the concave portion 1a as shown in FIG. 2 is installed, the air gap 6 ₁ becomes large as shown in FIG. 2 (c). For example, when a recessed line having a depth of about 200 μm is installed, the heat transfer resistance is
As shown in (1), it greatly increases to more than twice as much as that of a normal mold having no recessed line, the heat removal capability becomes extremely small, and gentle cooling becomes possible. In the case of a normal mold, the air gap amount δ at the lower end of the mold is estimated to be 50 to 90 μm, so 2
It can be seen that the order of 00 μm is very large.

【００４０】鋳型への凹部１ａの設置位置は、本願第１
発明の緩冷却ゾーンの設定方法と同様である。好ましい
実施態様例としては、図２，３に示す本発明鋳型は長辺
側内面（溶鋼が接する面）の幅中央近傍の凝固進行の早
い位置１ｂ（一例として、長辺面の幅をＷとして、１／
４Ｌ位置から３／４Ｌ位置までの幅中央側）には凹部１
ａが設置され、その部分は緩冷却となるように抜熱能が
小さくなるように構成されている。幅端部の凝固進行の
遅い位置１ｃ（前述の例では約１／４Ｌよりエッジの間
および３／４Ｌよりエッジの間）は、凹部ゾーンを設置
せず抜熱能を従来のままとする。ただし、本願第１発明
の場合と同様、凝固シェル厚が最大および最小となる位
置は、ノズル形状や鋳造速度により変動するため、幅方
向凝固プロフィールは事前に調査しておき、それに応じ
て幅方向の凹部設置位置を決定するのが望ましい。The installation position of the recess 1a in the mold is the first
This is similar to the method of setting the slow cooling zone of the invention. As a preferred embodiment, the mold of the present invention shown in FIGS. 2 and 3 has a position 1b where solidification proceeds rapidly near the center of the width of the inner surface on the long side (the surface in contact with molten steel) (for example, the width of the long side is W). , 1 /
The concave portion 1 is provided on the width center side from the 4L position to the 3 / 4L position).
a is installed, and the heat removal capability is reduced so that the part is slowly cooled. At the position 1c where the solidification progresses slowly at the width end (between the edges of about 1 / 4L and between the edges of 3 / 4L in the above-described example), the heat removal capability is maintained as it is without setting the recessed zone. However, as in the case of the first invention of the present application, the positions where the solidification shell thickness becomes maximum and minimum vary depending on the nozzle shape and the casting speed. Therefore, the width-direction solidification profile should be investigated in advance and the width-direction solidification profile should be adjusted accordingly. It is desirable to determine the position where the recess is installed.

【００４１】本願発明の第５発明においては、鋳込み方
向に沿った長辺面の中央部に多数の凹部または凹条を設
けた連続鋳造用鋳型において、引き抜き方向に沿ってメ
ニスカス近傍から鋳型出側までの間のみに多数の凹部を
設けたことによって、メニスカス近傍にただ単に凹部を
設置したのみでは、ブレークアウトという操業上のトラ
ブルが生じることがあるので、図４に示すように凹部の
幅Ｗ（溝の幅またはディンプルの径）を小さくする必要
がある等、凹部加工に精密な仕様が必要となる。したが
って、ブレークアウトが生じやすい場合には、メニスカ
ス部に凹部が設置されていない鋳型にすると、凹部の仕
様がそれほど厳密でなくなるという利点を有する。According to a fifth aspect of the present invention, in a continuous casting mold in which a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction, the mold outlet side from the vicinity of the meniscus along the drawing direction. Since a large number of recesses are provided only up to, the recesses may cause operational troubles such as breakout if the recesses are simply installed near the meniscus. Therefore, as shown in FIG. Precise specifications are required for processing the recess, such as (the width of the groove or the diameter of the dimple) needs to be reduced. Therefore, when breakout is likely to occur, the use of a mold in which the concave portion is not installed in the meniscus portion has an advantage that the concave portion is not so strict in specifications.

【００４２】従来の緩冷却鋳型の主眼は、鋳片の縦割れ
等の表面疵防止であるため、メニスカス近傍に凹部を設
置することが絶対条件であったが、本願の第５発明の主
眼は、末期凝固域における幅方向未凝固厚を一定に制御
することであるため、必ずしもメニスカス１ｄ近傍に凹
部１ａを設置する必要はなく、むしろ、メニスカス１ｄ
近傍には意図的に凹部ゾーンを設置しないものとする。
ただし、凹部設置位置をあまりメニスカス１ｄから遠ざ
けた場合は、緩冷却効果が期待できなくなるので、トラ
ブルの起こらない範囲で凹部ゾーンの上縁のレベルをで
きるだけメニスカスに近くする必要がある。凹部ゾーン
の上縁とメニスカス１ｄとの距離Ｈと鋳型出口における
凝固シェル厚の関係は、図１５に示すとおり、凹部ゾー
ンの上縁とメニスカス１ｄとの距離Ｈが大きくなるほ
ど、凝固シェル厚は大きくなるため、メニスカス１ｄま
で凹部が設置してある鋳型と比較して緩冷却効果があま
り期待できなくなる。凹部ゾーンの上縁とメニスカス１
ｄとの距離Ｈを１００ｍｍ程度とすれば、図１５に示す
ように緩冷却効果が十分あり、したがって、未凝固厚を
幅方向一定値に制御が可能であり、かつ、ブレークアウ
ト等のトラブルの心配は従来鋳型並に低くなる。Since the main object of the conventional slow cooling mold is to prevent surface flaws such as vertical cracks of the slab, it is absolutely necessary to install the concave portion near the meniscus, but the main object of the fifth invention of the present application is. Since the width direction uncoagulated thickness in the terminal coagulation region is controlled to be constant, it is not always necessary to install the concave portion 1a in the vicinity of the meniscus 1d, but rather the meniscus 1d.
No concave zone is intentionally installed in the vicinity.
However, if the recess installation position is far away from the meniscus 1d, the slow cooling effect cannot be expected, so it is necessary to set the upper edge level of the recess zone as close to the meniscus as possible without causing trouble. As shown in FIG. 15, the relationship between the distance H between the upper edge of the recessed zone and the meniscus 1d and the thickness of the solidified shell at the outlet of the mold is as shown in FIG. Therefore, the slow cooling effect cannot be expected so much as compared with the mold in which the concave portion is installed up to the meniscus 1d. Upper edge of concave zone and meniscus 1
If the distance H from d is set to about 100 mm, there is a sufficient cooling effect as shown in FIG. 15, and therefore, the unsolidified thickness can be controlled to a constant value in the width direction, and trouble such as breakout can be prevented. Worry is as low as conventional molds.

【００４３】本発明鋳型における凹部の形状および隣合
う凹部の間隔等は以下に述べるような仕様が望ましい。
図２２に本願の第４および第５発明の鋳型を使用した場
合の幅中央部の凹部の深さｄ_mと凹部ゾーンの総面積率
α_mが未凝固厚み差Ｄ_max−Ｄ_minに及ぼす影響を示す。
ここで、凹部ゾーンの総面積率α_mは下記（２）式によ
り定義される。 総面積率α_m（％）＝（凹部１ａの総面積／鋳型の長辺面の面積）×１００ （２）式 本願の第４および第５発明の鋳型共に、凹部の深さｄ_m
と凹部ゾーンの総面積率α_mの組み合わせによって、幅
方向全体の中心偏析を好転するための範囲未凝固厚み差
Ｄ_max−Ｄ_min≦２の範囲にすることが可能である。ただ
し、本願の第５発明の鋳型は、メニスカス部分に凹部が
設置されていない分、本願の第４発明の鋳型よりも凹部
の深さｄ_m、凹部ゾーンの総面積率α_m共に大きくする必
要がある。The following specifications are desirable for the shape of the recesses and the space between the adjacent recesses in the mold of the present invention.
FIG. 22 shows the influence of the depth d _m of the recessed portion at the center of the width and the total area ratio α _{m of the} recessed zones on the unsolidified thickness difference D _max -D _min when the molds of the fourth and fifth inventions of the present application are used. Indicates.
Here, the total area ratio α _m of the recessed zone is defined by the following equation (2). Total area ratio α _m (%) = (total area of concave portion 1a / area of long side surface of mold) × 100 (2) Formula For both the molds of the fourth and fifth inventions of the present application, the depth d _{m of the} concave portion
It is possible to set the range of the unsolidified thickness difference D _max −D _min ≦ 2 for improving the center segregation in the entire width direction by the combination of the total area ratio α _m of the concave zone and the total area ratio α _m . However, since the mold of the fifth invention of the present application has no recess in the meniscus portion, both the depth d _{m of} the recess and the total area ratio α _m of the recess zones need to be larger than those of the mold of the fourth invention of the present application. There is.

【００４４】ただし、本願の第４発明の鋳型は、凹部へ
の地金付着防止、パウダー侵入防止等の操業安定性と考
え併せると、凹部の深さｄ_mは、０．２≦ｄ_m≦１．０、
凹部ゾーンの総面積率α_mは、α_m≧２５、また、本願の
第５発明の鋳型は、凹部の深さｄ_mは、０．５≦ｄ_m≦
２．０、凹部ゾーンの総面積率α_mは、α_m≧２５の範囲
にするのが望ましい。本願の第５発明の鋳型の方が凹部
の深さｄ_mの値を小さくする必要があるのは、メニスカ
スに凹部が設置されている分、凹部へ地金が付着し易か
ったり、パウダーが侵入し易いため、制約が大きいから
である。なお、図１４に示したように、０．２ｍｍ以上
の凹部深さを設置した場合の伝熱抵抗は、約４０×１０
^-4ｈｒ・℃／ｋｃａｌであり、通常鋳型の伝熱抵抗約２
０×１０^-4ｈｒ・℃／ｋｃａｌに対し、２倍以上の伝熱
抵抗である。However, considering the operational stability such as prevention of metal adhesion to the recess and prevention of powder intrusion, the mold of the fourth invention of the present application has a recess depth d _m of 0.2 ≦ d _m ≦ 1.0,
The total area ratio α _m of the recessed zone is α _m ≧ 25, and in the mold of the fifth invention of the present application, the depth d _{m of the} recessed portion is 0.5 ≦ d _m ≦
2.0, the total area ratio α _m of the recessed zones is preferably in the range of α _m ≧ 25. In the mold of the fifth invention of the present application, it is necessary to reduce the value of the depth d _m of the concave portion because the concave portion is installed in the meniscus, so that the metal is easily attached to the concave portion or the powder enters This is because it is easy to do so, and the restrictions are large. As shown in FIG. 14, the heat transfer resistance when the recess depth is 0.2 mm or more is about 40 × 10.
^-4 hr · ° C / kcal, the heat transfer resistance of the normal mold is about 2
The heat transfer resistance is more than double that of 0 × 10 ⁻⁴ hr · ° C./kcal.

【００４５】さらに、凹部の幅または径Ｗｍは、本願の
第４および第５発明の鋳型では異なる。すなわち、本願
の第４発明の鋳型では、メニスカス近傍に凹部があるた
め、凹部ゾーンへのパウダー流入を防止する観点から凹
部の幅または径Ｗｍは１．０ｍｍ以下にするのが望まし
い。一方、本願の第５発明の鋳型は、バルジング防止の
観点から凹部の幅または径Ｗｍは２００ｍｍ以下が望ま
しいが、メニスカス近傍に凹部がある本願の第４発明の
緩冷却鋳型に比べてそれほど厳密に幅または径Ｗｍを設
計する必要はなく、この点、本願の第５発明の鋳型の方
が凹部加工の自由度が大きい。隣合う凹部の間隔Ｉｍ
は、凹部設置部の不均一凝固防止の観点から１０ｍｍ以
下が望ましい。これは間隔Ｉｍが１０ｍｍよりも大きい
場合は、図１６に示すように凹部１ａと凹無部１ｅに対
応する凝固シェル４厚の差が大きくなるからである。Furthermore, the width or diameter Wm of the recess differs in the molds of the fourth and fifth inventions of the present application. That is, in the mold of the fourth invention of the present application, since there is a recess near the meniscus, it is desirable that the width or diameter Wm of the recess be 1.0 mm or less from the viewpoint of preventing powder from flowing into the recess zone. On the other hand, in the mold of the fifth invention of the present application, the width or diameter Wm of the recess is preferably 200 mm or less from the viewpoint of preventing bulging, but it is more rigorous than the slow cooling mold of the fourth invention of the present application having a recess near the meniscus. It is not necessary to design the width or the diameter Wm, and in this respect, the mold of the fifth invention of the present application has a greater degree of freedom in recess processing. Im between adjacent recesses
Is preferably 10 mm or less from the viewpoint of preventing uneven solidification of the recess installation portion. This is because when the distance Im is larger than 10 mm, the difference in thickness between the solidified shells 4 corresponding to the concave portion 1a and the concave portion 1e becomes large as shown in FIG.

【００４６】次に、本願の第４および第５発明の鋳型に
よる不均一凝固緩和効果を不均一凝固量の鋳造方向推移
に着目して説明する。本発明鋳型使用時と従来鋳型使用
時の未凝固厚み差Ｄ_max−Ｄ_minの鋳造方向推移は図２１
（ａ）のように示される。なお、本発明の鋳型使用時に
おいては、表１、表２のような凹部仕様としてある。従
来鋳型使用時鋳型内において生じた未凝固厚み差Ｄ_max
−Ｄ_minがメニスカス下２．０ｍ位置まで増加する。こ
れは、図１３に示すように鋳型出口における幅方向鋳片
温度分布が不均一であるため、２次冷却域において冷却
不均一が助長されるためである。その後、凝固進行が遅
れる部分と凝固進行が早い部分の伝熱抵抗の差により、
未凝固厚み差Ｄ_max−Ｄ_minは減少していくが、軽圧下ゾ
ーン入り側においても未凝固厚み差Ｄ_max−Ｄ_minは１０
ｍｍ程度（片側シェル厚５ｍｍ）存在する。この未凝固
厚み差Ｄ_max−Ｄ_minは、最終凝固位置の差ΔＬにして
（図１０（ｂ））１．０ｍ程度に相当し、これが軽圧下
の幅方向不均一につながり、凝固遅れ部で偏析の程度を
大きくさせることになる。これに対し、本願の第４発明
の鋳型の場合は、鋳型内でほぼ未凝固厚み差Ｄ_max−Ｄ
_minが皆無となり、この未凝固厚み差Ｄ_max−Ｄ_minは軽
圧下ゾーン入り側まで皆無の状態で維持される。Next, the uneven solidification mitigation effect of the molds of the fourth and fifth inventions of the present application will be described by focusing on the transition of the uneven solidification amount in the casting direction. The transition of the unsolidified thickness difference D _max -D _min between when using the mold of the present invention and when using the conventional mold is shown in FIG.
It is shown as (a). In addition, when using the mold of the present invention, the recess specifications are as shown in Tables 1 and 2. Unsolidified thickness difference D _max that occurred in the mold when using the conventional mold
-D _min increases up to 2.0 m below the meniscus. This is because the temperature distribution in the widthwise slab at the outlet of the mold is non-uniform as shown in FIG. 13, so that non-uniform cooling is promoted in the secondary cooling region. After that, due to the difference in heat transfer resistance between the part where the progress of solidification is delayed and the part where the progress of solidification is early,
The unsolidified thickness difference D _max -D _min decreases, but the unsolidified thickness difference D _max -D _min is 10 even on the entry side of the light reduction zone.
There is about mm (shell thickness on one side: 5 mm). This unsolidified thickness difference D _max- D _min corresponds to about 1.0 m in terms of the final solidified position difference ΔL (FIG. 10 (b)), which leads to unevenness in the width direction under light pressure reduction and at the solidification delay portion. The degree of segregation will be increased. On the other hand, in the case of the mold of the fourth invention of the present application, the difference in the unsolidified thickness _Dmax- D in the mold is almost equal.
_Since there is no _min , this unsolidified thickness difference D _max -D _min is maintained in a none state up to the entry side of the light reduction zone.

【００４７】[0047]

【表１】 [Table 1]

【００４８】[0048]

【表２】 [Table 2]

【００４９】本願の第６発明においては、鋳込み方向に
沿った長辺面の中央部に多数の凹部または凹条を設けた
連続鋳造用鋳型において、長辺面中央部の鋳型冷却水の
面と鋳型溶鋼面の距離を中央部以外の鋳型冷却水の面と
鋳型溶鋼面の距離よりも５ｍｍ以上大きくしたことによ
って、鋳型冷却水の面から鋳型溶鋼面の距離ｄ₁と鋳型
表面温度Ｔ_surfの関係を示す図２５に示すとおり、鋳型
冷却水の面から鋳型溶鋼面の距離ｄ₁が５ｍｍ異なる
と、鋳型表面温度Ｔ_surfは約１００℃異なる。このた
め、前記の鋳型冷却水流速ｕの場合と同様に、連鋳パウ
ダーの厚みが増大することによる緩冷却化が可能であ
る。本発明者らは、鋳型冷却水の面から鋳型溶鋼面の距
離ｄ₁の幅方向制御についても、それのみでは未凝固厚
み差Ｄ_max−Ｄ_minの低減に効果を示さないが、鋳型内壁
の幅中央部に凹部を設けた本願の第４、第５発明の鋳型
と組み合わせることにより、非常に良い効果を示すこと
を知見した。図２６に本願の第６発明の鋳型と幅方向の
鋳型冷却水の面から鋳型溶鋼面の距離ｄ₁のみを制御し
た鋳型のそれぞれについて、鋳型冷却水の面から鋳型溶
鋼面の距離ｄ₁と未凝固厚み差Ｄ_max−Ｄ_minの関係を示
す。本願の第６発明の鋳型では、幅中央部の鋳型冷却水
の面から鋳型溶鋼面の距離ｄ₁を中央部以外の鋳型冷却
水の面から鋳型溶鋼面の距離ｄ₁よりも５ｍｍ以上大き
くすることによって、未凝固厚み差Ｄ_max−Ｄ_minは大幅
に低減している。一方、幅方向の鋳型冷却水の面から鋳
型溶鋼面の距離ｄ₁のみの制御を行った鋳型では、中央
部の鋳型冷却水の面から鋳型溶鋼面の距離ｄ₁を中央部
以外の鋳型冷却水の面から鋳型溶鋼面の距離ｄ₁より１
０ｍｍ大きくしても、未凝固厚み差Ｄ_max−Ｄ_minはほと
んど低減しなかった。In the sixth invention of the present application, in a continuous casting mold in which a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction, the surface of the mold cooling water in the central portion of the long side surface is By making the distance of the molten steel surface of the mold 5 mm or more larger than the distance between the surface of the mold cooling water other than the central portion and the surface of the mold cooling water, the distance d ₁ from the surface of the mold cooling water to the molten steel surface of the mold and the mold surface temperature T _surf As shown in FIG. 25 showing the relationship, when the distance d ₁ from the mold cooling water surface to the mold molten steel surface differs by 5 mm, the mold surface temperature T _surf differs by about 100 ° C. Therefore, as in the case of the mold cooling water flow rate u described above, slow cooling can be achieved by increasing the thickness of the continuous casting powder. The present inventors have no effect on the reduction of the unsolidified thickness difference D _max -D _min by controlling the distance d ₁ from the surface of the mold cooling water to the surface of the molten steel in the mold, but the control of the inner wall of the mold is not effective. It has been found that a very good effect is exhibited by combining with the molds of the fourth and fifth inventions of the present application in which the concave portion is provided in the width center portion. For each sixth surface of the mold cooling water of the mold in the width direction of the aspect of the invention the mold with controlled only the distance d ₁ of the mold the molten steel surface in FIG. 26, from the surface of the mold cooling water to the distance d ₁ of the mold molten steel surface The relationship of unsolidified thickness difference _{Dmax- Dmin} is shown. In the mold of the sixth invention of the present application, the distance d ₁ from the surface of the mold cooling water at the center of the width to the molten steel surface of the mold is made 5 mm or more larger than the distance d _{1 of the} surface of the molten mold from the surface of the cooling water of the mold other than the central portion. As a result, the unsolidified thickness difference D _max -D _min is significantly reduced. On the other hand, in the mold in which only the distance d _{1 of the} molten steel surface from the surface of the mold cooling water in the width direction is controlled, the distance d _{1 of the} molten steel surface of the mold from the surface of the cooling water in the central portion is set to the cooling temperature of the molds other than the central portion. ₁ from the distance d ₁ from the water surface to the molten steel surface of the mold
Even if the thickness was increased by 0 mm, the unsolidified thickness difference D _max -D _min was hardly reduced.

【００５０】また、本発明鋳型を使用した場合の未凝固
厚み差Ｄ_max−Ｄ_minの鋳造方向推移は、図２１（ａ）の
ように示される。図２１（ａ）は、メニスカス部に凹部
を設けていない本願の第５発明の鋳型で、鋳型冷却水の
面から鋳型溶鋼面の距離ｄ₁の幅方向制御を行ったもの
であるが、本願の第４発明の鋳型とほぼ同一の挙動を取
り、未凝固厚み差Ｄ_max−Ｄ_minは、鋳型内でほぼ皆無と
なり、この状態は軽圧下ゾーン入り側まで皆無の状態で
維持される。すなわち、本願の第６発明の鋳型において
も、鋳型冷却水の面から鋳型溶鋼面の距離ｄ₁の幅方向
制御をすることにより、不均一凝固緩和能が向上してい
ることが明らかである。したがって、本願の第６発明の
鋳型は、目的とする不均一凝固緩和能を得るために溶鋼
面側の凹部設置と、鋳型冷却水の面から鋳型溶鋼面の距
離ｄ₁の幅方向制御を行うことによって、本願の第２発
明と同様、凹部の仕様を操業上安定な方向に設定するこ
とができる。さらに、本願の第６発明の鋳型は、冷却水
の配管系統を幅中央とそれ以外で同一にできるので、構
造を単純にできる利点を有する。また、本願の第６発明
の鋳型の不均一凝固緩和能は、本願の第４、第５発明の
鋳型に比べて向上するので、鋳造速度が大きくなり、浸
漬ノズルからの溶鋼吐出流が大きくなった場合にも対応
可能である。The transition of the unsolidified thickness difference D _max -D _{min in} the casting direction when the mold of the present invention is used is shown in FIG. 21 (a). FIG. 21 (a) shows the mold of the fifth invention of the present application in which the meniscus portion is not provided with a recess, and the width direction control of the distance d ₁ from the mold cooling water surface to the mold molten steel surface is performed. The mold has substantially the same behavior as the mold of the fourth invention, and the unsolidified thickness difference D _max -D _min is almost completely absent in the mold, and this state is maintained even at the light pressure zone entering side. That is, also in the mold of the sixth invention of the present application, it is apparent that the nonuniform solidification relaxation ability is improved by controlling the width direction of the distance d ₁ from the mold cooling water surface to the molten steel surface of the mold. Therefore, in the mold of the sixth invention of the present application, in order to obtain the desired nonuniform solidification relaxation ability, the recessed portion is provided on the molten steel surface side, and the width direction control of the distance d ₁ from the surface of the mold cooling water to the molten steel surface of the mold is performed. This makes it possible to set the specifications of the recesses in a stable operation direction, as in the second invention of the present application. Furthermore, the mold of the sixth invention of the present application has the advantage that the structure of the cooling water can be simplified because the cooling water piping system can be made the same in the width center and in other areas. Further, since the uneven solidification relaxation ability of the mold of the sixth invention of the present application is improved as compared with the molds of the fourth and fifth inventions of the present application, the casting speed is increased and the molten steel discharge flow from the immersion nozzle is increased. It is also possible to deal with the case.

【００５１】連続鋳造用の支持ロール、圧下ロールおよ
び引抜ロールは、その名が示すとおり鋳片の支持、引抜
の役割を果たすと同時に、鋳片との接触熱伝達による鋳
片冷却の役割をも果たしている。通常の連鋳機は、少な
くとも２０本以上のロールを有しているため、連鋳鋳片
の凝固特性に及ぼすロール冷却の影響は大きい。本願の
第７発明においては、スラブ形状の鋳片の連続鋳造用の
支持ロール、圧下ロールおよび引抜ロールのスラブ幅中
央部に接する部分に低熱伝導率材料からなる断熱層を設
けたことによって、幅中央部の冷却能がそれ以外の部分
よりも緩冷却となり、長辺面の中央部を緩冷却すること
ができ、スラブ長辺面の幅方向の凝固がほぼ均一とな
り、軽圧下ゾーンにおける均一圧下が可能で、スラブの
幅方向全体の中心偏析を抑制することができる。本願の
第７発明の支持ロール、圧下ロールおよび引抜ロールに
用いる低熱伝導率材料の断熱層としては、Ａｌ₂Ｏ₃、Ｚ
ｒＯ₂等のセラミックス材料を溶射する方法、Ｎｉおよ
びＮｉ−Ｃｒメッキの層の厚みを大きくする方法等が挙
げられる。一般に連鋳ロールは、２次冷却と併用される
ためにセラミックス材料は水分を含有すると劣化等の問
題点が生じるので、ＮｉおよびＮｉ−Ｃｒメッキの層の
厚みを大きくする方法が実用的である。ただし、ドライ
キャスティングのように水を使わない場合は、Ａｌ
₂Ｏ₃、ＺｒＯ₂等のセラミックス材料を溶射する方法も
有効となり得る。As the name implies, the support rolls, reduction rolls, and drawing rolls for continuous casting play the role of supporting and drawing the slab, and at the same time, have the role of cooling the slab by contact heat transfer with the slab. Is playing. Since an ordinary continuous casting machine has at least 20 rolls or more, the influence of roll cooling on the solidification characteristics of the continuous cast slab is great. In the seventh invention of the present application, the width of the support roll for continuous casting of the slab-shaped slab, the reduction roll, and the drawing roll provided with the heat insulating layer made of the low thermal conductivity material in the portion in contact with the central portion of the slab width. The cooling capacity of the central part is slower than that of other parts, and the central part of the long side surface can be gently cooled, solidification in the width direction of the long side surface of the slab is almost uniform, and uniform rolling in the light reduction zone is achieved. It is possible to suppress center segregation in the entire width direction of the slab. As the heat insulating layer of the low thermal conductivity material used for the supporting roll, the pressing roll and the drawing roll of the seventh invention of the present application, Al ₂ O ₃ , Z
Examples include a method of spraying a ceramic material such as rO ₂ and a method of increasing the thickness of the Ni and Ni—Cr plated layers. Generally, continuous casting rolls are used together with secondary cooling, and therefore, when the ceramic material contains water, problems such as deterioration occur. Therefore, a method of increasing the thickness of the Ni and Ni-Cr plated layers is practical. . However, if water is not used as in dry casting, Al
A method of spraying a ceramic material such as ₂ O ₃ or ZrO ₂ may also be effective.

【００５２】本願の第７発明の連続鋳造用ロールにおい
て、ロールの幅中央相当部分に配した低熱伝導率材料に
よる断熱層の厚みｔと未凝固厚み差Ｄ_max−Ｄ_minの関係
を図２８に示す。図２８は、ＺｒＯ₂を中央部に溶射し
たロールについて示してある。２次冷却は、ドライキャ
スティングであり、最終凝固位置までに鋳片が通過する
ロール本数は５０本である。図２８に示すとおり、ロー
ルの断熱層の厚みｔが大きくなるほど未凝固厚み差Ｄ
_max−Ｄ_minは低減し、ロールの断熱層の厚みｔを１ｍｍ
以上にすると、鋳片の幅方向全体の中心偏析を好転でき
る未凝固厚み差Ｄ_max−Ｄ_min≦２ｍｍにすることが可能
である。本願の第７発明の連続鋳造用ロールを鋳型を出
てから軽圧下終了まで適用した場合の未凝固厚み差Ｄ
_max−Ｄ_minの鋳造方向推移は、図２１（ｂ）に示すとお
り、ロール冷却の幅方向制御の効果によって、未凝固厚
み差Ｄ_max−Ｄ_minは鋳型を出てから減少し、軽圧下ゾー
ン入り側でほぼ皆無となり、不均一凝固緩和能を有する
ことが明らかである。In the continuous casting roll of the seventh invention of the present application, the relationship between the thickness t of the heat insulating layer made of the low thermal conductivity material and the unsolidified thickness difference D _max -D _min , which is arranged in the roll width center, is shown in FIG. Show. FIG. 28 shows a roll having ZrO ₂ sprayed on the central portion. The secondary cooling is dry casting, and the number of rolls through which the slab passes until the final solidification position is 50. As shown in FIG. 28, the unsolidified thickness difference D increases as the thickness t of the heat insulating layer of the roll increases.
_max- D _min is reduced, and the thickness t of the heat insulating layer of the roll is 1 mm
By the above, it is possible to make the unsolidified thickness difference D _max −D _min ≦ 2 mm, which can improve the center segregation of the entire slab in the width direction. Unsolidified thickness difference D when the continuous casting roll of the seventh invention of the present application is applied from the time when the mold is released until the end of the light reduction.
_As shown in FIG. 21 (b), the transition of _max- D _{min in} the casting direction decreases the unsolidified thickness difference D _max -D _min after leaving the mold due to the effect of the roll cooling width direction control. It is clear that it has almost no heterogeneous solidification relaxation ability on the entrance side.

【００５３】本願の第８発明においては、スラブ形状の
鋳片の連続鋳造用の支持ロール、圧下ロールおよび引抜
ロールのスラブ幅中央部に接する部分に多数の凹部を設
けたことによって、幅中央部の冷却能がそれ以外の部分
よりも緩冷却となり、長辺面の中央部を緩冷却すること
ができ、スラブ長辺面の幅方向の凝固がほぼ均一とな
り、軽圧下ゾーンにおける均一圧下が可能で、スラブの
幅方向全体の中心偏析を抑制することができる。本願の
第８発明の支持ロール、圧下ロールおよび引抜ロールの
凹部の形状は、前記鋳型の場合と同様、必要とする緩冷
却能があれば、凹条であってもディンプルであっても良
い。また、加工方法もボール盤、フライス盤等による機
械加工、ショットブラスト等による方法でもよい。In the eighth invention of the present application, a large number of concave portions are provided at the portions in contact with the central portion of the slab width of the support roll, the pressing roll and the drawing roll for continuous casting of the slab-shaped slab, whereby the width central portion is provided. The cooling capacity of the slab is slower than that of other parts, and the central part of the long side surface can be gently cooled, solidification in the width direction of the long side surface of the slab is almost uniform, and uniform reduction in the light reduction zone is possible. Thus, center segregation in the entire width direction of the slab can be suppressed. The shapes of the recesses of the supporting roll, the pressing roll and the drawing roll of the eighth invention of the present application may be concave stripes or dimples, as in the case of the above-mentioned mold, as long as they have the required slow cooling ability. Further, the processing method may be mechanical processing using a drilling machine, a milling machine or the like, or a method using shot blasting or the like.

【００５４】本願の第８発明の支持ロール、圧下ロール
および引抜ロールの凹部の仕様は、以下のように決定さ
れる。図２９に本願の第８発明の連続鋳造用ロールにお
いてロールの幅中央相当部分に配した凹部の深さｄ_rお
よび凹部ゾーンの面積率α_rと未凝固厚み差Ｄ_max−Ｄ
_minの関係を示す。なお、凹部ゾーンの面積率α_rは下記
（３）式により定義される。 面積率α_r（％）＝凹部の総面積／ロール長辺面相当の
面積×１００ （３）式 本願の第８発明の連続鋳造用ロールは、凹部の深さｄ_r
と凹部ゾーンの面積率α_rの組み合わせによって、鋳片
の幅方向全体の中心偏析を好転できる未凝固厚み差Ｄ
_max−Ｄ_minを≦２ｍｍにすることが可能である。ただ
し、ロール摩耗防止の観点から凹部の仕様は、凹部ゾー
ンの面積率α_r≦５０％、凹部の深さｄ_r≦２．０ｍｍの
範囲にするのが望ましい。The specifications of the recesses of the supporting roll, the pressing roll and the drawing roll of the eighth invention of the present application are determined as follows. 29. In FIG. 29, in the continuous casting roll of the eighth invention of the present application, the depth d _r of the concave portion and the area ratio α _{r of the} concave portion zone and the unsolidified thickness difference D _max −D arranged in the width center portion of the roll
Indicates the relationship of _min . The area ratio α _r of the recessed zone is defined by the following equation (3). Area ratio α _r (%) = total area of recesses / area corresponding to roll long side surface × 100 (3) Formula The continuous casting roll according to the eighth aspect of the present invention has a depth d _{r of} recesses.
The unsolidified thickness difference D that can improve the center segregation of the entire slab in the width direction by the combination of the area ratio α _r of
It is possible to have _max- D _min ≦ 2 mm. However, from the viewpoint of preventing roll wear, it is preferable that the recesses have specifications such that the area ratio α _r ≦ 50% of the recess zone and the depth d _r ≦ 2.0 mm of the recess.

【００５５】本願の第８発明の連続鋳造用ロールの凹部
の間隔または径Ｗｒは、理論上凹部での鋳片のバルジン
グが防止できる範囲であれば良いが、２次冷却水の流入
を防ぐために１．０ｍｍ以下が適当である。本願の第８
発明の連続鋳造用ロールの隣合う凹部の間隔Ｉｒは、ロ
ール摩耗防止の観点から１．０ｍｍ以上が適当である。
本願の第８発明の連続鋳造用ロールを鋳型をでてから軽
圧下終了まで適用した場合の未凝固厚み差Ｄ_max−Ｄ_min
の鋳造方向推移は、図２１（ｂ）に示すとおり、本願の
第７発明の連続鋳造用ロールの場合とほぼ同様である。
すなわち、未凝固厚み差Ｄ_max−Ｄ_minは、ロール冷却の
幅方向制御の効果によって鋳型を出てから減少し、軽圧
下ゾーン入り側でほぼ皆無となっており、不均一凝固緩
和能を有することが明らかである。The interval or diameter Wr of the recesses of the continuous casting roll of the eighth invention of the present application may theoretically be within a range capable of preventing bulging of the slab in the recesses, but in order to prevent the inflow of secondary cooling water. 1.0 mm or less is suitable. Eighth of the present application
The distance Ir between adjacent concave portions of the continuous casting roll of the invention is preferably 1.0 mm or more from the viewpoint of preventing roll wear.
Unsolidified thickness difference D _max -D _min when the continuous casting roll of the eighth invention of the present application is applied from the time when the mold is released until the end of the light reduction.
21 (b), the transition of the casting direction is substantially the same as that of the continuous casting roll of the seventh invention of the present application.
That is, the unsolidified thickness difference D _max -D _min decreases after exiting the mold due to the effect of controlling the width direction of roll cooling, and becomes almost nonexistent on the entry side of the light reduction zone, and has a nonuniform solidification relaxation ability. It is clear.

【００５６】なお、前記本願の第２〜第８発明において
は、（１）鋳型による幅方向冷却制御、（２）２次冷却
による幅方向冷却制御、（３）ロールによる幅方向冷却
制御のいずれかであるが、これら（１）〜（３）のうち
の少なくとも２つ以上を組合わせることに、非常に大き
い鋳片の幅中央部の緩冷却能を得ることができる。これ
ら（１）〜（３）の組合せとしては、任意に選択するこ
とができるが、これら（１）〜（３）のうちの少なくと
も２つ以上を組合わせることによって、必要とする緩冷
却能を得るために各々の部分の緩冷却能を小さくするこ
とによって、初期凝固域〜末期凝固域に至るまでまんべ
んなく幅方向の冷却制御をすることが可能となる。した
がって、この発明では、鋳造速度、溶鋼過熱度、２次冷
却条件等、操業パラメーターが変更されても柔軟に対応
することが可能である。In the second to eighth inventions of the present application, any of (1) widthwise cooling control by the mold, (2) widthwise cooling control by secondary cooling, and (3) widthwise cooling control by rolls. However, by combining at least two or more of these (1) to (3), it is possible to obtain the slow cooling capacity of the width center portion of a very large slab. The combination of (1) to (3) can be arbitrarily selected, but by combining at least two or more of these (1) to (3), the required slow cooling capacity can be obtained. By reducing the slow cooling capacity of each part in order to obtain it, it becomes possible to uniformly control the cooling in the width direction from the initial solidification region to the final solidification region. Therefore, according to the present invention, it is possible to flexibly cope with changes in operating parameters such as casting speed, degree of superheat of molten steel, secondary cooling conditions, and the like.

【００５７】本願の第９発明においては、鋳型の鋳込み
方向に沿った長辺面の中央部に多数の凹部または凹条を
設け、スラブ幅中央部の２次冷却水量密度を中央部以外
の水量密度の７５％以下にすることによって、鋳型によ
る幅方向中央部の緩冷却効果と、２次冷却水による幅方
向中央部の緩冷却の相乗効果によって、スラブ長辺面の
幅方向の凝固がほぼ均一となり、軽圧下ゾーンにおける
均一圧下が可能で、スラブの幅方向全体の中心偏析を抑
制することができる。In the ninth invention of the present application, a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction of the mold, and the secondary cooling water amount density in the central portion of the slab width is set to the amount of water other than the central portion. By setting the density to 75% or less, the solidification in the width direction of the long side surface of the slab is almost achieved by the synergistic effect of the mild cooling effect of the mold in the width direction central portion and the slow cooling of the width direction center portion by the secondary cooling water. It becomes uniform, uniform rolling in the light rolling zone is possible, and center segregation in the entire width direction of the slab can be suppressed.

【００５８】また、本願の第１０発明においては、鋳型
の鋳込み方向に沿った長辺面の中央部に多数の凹部また
は凹条を設けると共に、支持ロール、圧下ロールおよび
引抜ロールのスラブ幅中央部に接する部分に多数の凹部
を設けたことによって、鋳型による幅方向中央部の緩冷
却効果と、支持ロール、圧下ロールおよび引抜ロールに
よる幅方向中央部の緩冷却の相乗効果によって、スラブ
長辺面の幅方向の凝固がほぼ均一となり、軽圧下ゾーン
における均一圧下が可能で、スラブの幅方向全体の中心
偏析を抑制することができる。Further, in the tenth invention of the present application, a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction of the mold, and the central portion of the slab width of the supporting roll, the pressing roll and the drawing roll is provided. By providing a large number of recesses in the part in contact with the slab, the synergistic effect of mild cooling of the widthwise center part by the mold and the slow cooling of the widthwise center part by the support rolls, reduction rolls and drawing rolls The solidification in the width direction is almost uniform, uniform reduction in the light reduction zone is possible, and center segregation in the entire width direction of the slab can be suppressed.

【００５９】さらに、本願の第１１発明においては、支
持ロール、圧下ロールおよび引抜ロールのスラブ幅中央
部に接する部分に多数の凹部を設けると共に、スラブ幅
中央部の２次冷却水量密度を中央部以外の水量密度の７
５％以下にすることによって、支持ロール、圧下ロール
および引抜ロールによる幅方向中央部の緩冷却効果と、
２次冷却水による幅方向中央部の緩冷却の相乗効果によ
って、スラブ長辺面の幅方向の凝固がほぼ均一となり、
軽圧下ゾーンにおける均一圧下が可能で、スラブの幅方
向全体の中心偏析を抑制することができる。Further, in the eleventh invention of the present application, a large number of concave portions are provided in the portions of the supporting roll, the pressing roll and the drawing roll in contact with the central portion of the slab width, and the secondary cooling water amount density in the central portion of the slab width is set to the central portion. Water density other than 7
By making it 5% or less, the effect of gentle cooling of the widthwise central portion by the supporting roll, the pressing roll and the drawing roll,
Due to the synergistic effect of the slow cooling of the widthwise central part by the secondary cooling water, the solidification in the width direction of the long side surface of the slab becomes almost uniform,
Uniform reduction in the light reduction zone is possible, and center segregation in the entire width direction of the slab can be suppressed.

【００６０】さらにまた、本願の第１２発明において
は、鋳型の鋳込み方向に沿った長辺面の中央部に多数の
凹部または凹条を設け、支持ロール、圧下ロールおよび
引抜ロールのスラブ幅中央部に接する部分に多数の凹部
を設けると共に、スラブ幅中央部の２次冷却水量密度を
中央部以外の水量密度の７５％以下にすることによっ
て、鋳型による幅方向中央部の緩冷却効果と、支持ロー
ル、圧下ロールおよび引抜ロールによる幅方向中央部の
緩冷却と、さらに、２次冷却水による幅方向中央部の緩
冷却の相乗効果によって、スラブ長辺面の幅方向の凝固
が均一化され、軽圧下ゾーンにおける均一圧下が可能
で、スラブの幅方向全体の中心偏析を防止することがで
きる。Furthermore, in the twelfth invention of the present application, a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction of the mold, and the slab width central portion of the support roll, the pressing roll and the drawing roll is provided. By providing a large number of recesses in the part in contact with the slab and setting the secondary cooling water amount density in the central part of the slab width to 75% or less of the water amount density other than the central part, the effect of gentle cooling of the central part in the width direction by the mold and supporting By the synergistic effect of the gentle cooling of the widthwise central portion by the rolls, the pressing rolls and the drawing rolls, and the gentle cooling of the widthwise central portion by the secondary cooling water, the solidification in the widthwise direction of the long side surface of the slab is made uniform, Uniform reduction is possible in the light reduction zone, and center segregation in the entire width direction of the slab can be prevented.

【００６１】図３０は、本願の第４発明の鋳型を使用し
た場合、本願の第４発明の鋳型と本願の第３発明の二次
冷却を使用した第９発明の場合、本願の第４発明の鋳型
と本願の第８発明の連続鋳造用ロールを使用した第１０
発明の場合、本願の第４発明の鋳型と本願の第３発明の
二次冷却と本願の第８発明の連続鋳造用ロールを使用し
た第１２発明の場合のそれぞれについて、鋳型凹部深さ
ｄ_mと未凝固厚み差Ｄ_max−Ｄ_minとの関係を調査した。
その結果を図３０に示す。図３０に示すとおり、同じ鋳
型凹部深さｄ_mの場合は、第４発明、第９発明、第１０
発明、第１２発明の順に未凝固厚み差Ｄ_max−Ｄ_minが小
さくなっており、本願の第２〜第８発明の組み合わせの
適用によって同一の未凝固厚み差Ｄ_max−Ｄ_minが得られ
ることになり、操業のフレキシビリティーが極めて増す
ことになる。FIG. 30 shows the case where the mold of the fourth invention of the present application is used, the mold of the fourth invention of the present application and the ninth invention of using the secondary cooling of the third invention of the present application, and the fourth invention of the present application. No. 10 using the mold of No. 6 and the continuous casting roll of the eighth invention of the present application
In the case of the invention, the mold recess depth d _{m is obtained} for each of the case of the twelfth invention using the mold of the fourth invention of the present application, the secondary cooling of the third invention of the present application, and the continuous casting roll of the eighth invention of the present application. And the unsolidified thickness difference _{Dmax- Dmin} were investigated.
The result is shown in FIG. As shown in FIG. 30, in the case of the same mold recess depth d _m , the fourth invention, the ninth invention, and the tenth invention
The unsolidified thickness difference D _max -D _min decreases in the order of the invention and the twelfth invention, and the same unsolidified thickness difference D _max -D _min can be obtained by applying the combination of the second to eighth inventions of the present application. Therefore, the flexibility of operation will be greatly increased.

【００６２】なお、本願の第５発明の鋳型と本願の第３
発明の二次冷却と本願の第８発明の連続鋳造用ロールを
組合せた連続鋳造方法を、鋳型〜メニスカス下４．０ｍ
まで適用した場合の未凝固厚み差Ｄ_max−Ｄ_minの鋳造方
向推移は、図２１（ｂ）のように示される。図２１
（ｂ）に示すとおり、本願の第５発明の鋳型と本願の第
３発明の二次冷却と本願の第８発明の連続鋳造用ロール
をを組合せたＫの場合は、未凝固厚み差Ｄ_max−Ｄ_minは
鋳型内でほぼ皆無となり、その後、メニスカス下４．０
ｍで皆無となり、極めて大きい幅中央部の緩冷却能（不
均一凝固緩和能）を有することが明らかである。上記の
結果からも明らかなとおり、本願の第９〜第１２発明以
外に、第２〜第８発明の多数の組合せがあるが、これら
はいずれも第９〜第１２発明と同様に極めて大きい幅中
央部の緩冷却能を有していることは明白であり、本願発
明に包含されることはいうまでもない。The mold of the fifth invention of the present application and the third mold of the present invention
The continuous casting method in which the secondary cooling of the invention and the roll for continuous casting of the eighth invention of the present application are combined is carried out by a mold to a meniscus under 4.0 m.
21 (b) shows the transition of the unsolidified thickness difference D _max -D _{min in} the casting direction when applied up to. Figure 21
As shown in (b), in the case of K in which the mold of the fifth invention of the present application, the secondary cooling of the third invention of the present application, and the continuous casting roll of the eighth invention of the present application are combined, the unsolidified thickness difference D _max. -D _min almost disappeared in the mold, and then 4.0 below the meniscus.
It is apparent that the film has nothing at m, and has an extremely large gentle cooling capacity (uneven solidification relaxation capacity) at the center of the width. As is clear from the above results, there are many combinations of the second to eighth inventions other than the ninth to twelfth inventions of the present application, but all of them have an extremely large width like the ninth to twelfth inventions. It is obvious that the central portion has a slow cooling ability, and it goes without saying that it is included in the present invention.

【００６３】[0063]

【実施例】【Example】

実施例１ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から図２に示す構造で表３に示す仕様の鋳型１
に鋳込み、鋳造速度０．８ｍ／ｍｉｎ、鋳型長さ７００
ｍｍで厚さ２５０ｍｍ、幅２０００ｍｍのスラブ鋳片を
サポートロール群６、圧下ロール群７、そしてピンチロ
ール８を経て鋳造するに際し、表４に示す２次冷却装置
の仕様、表５に示す連鋳ロールの仕様で、圧下ゾーン長
さ５ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラ
ブ鋳片とした。得られたスラブ鋳片のスラブエッジから
の距離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共
に、圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差
Ｄ_max−Ｄ_minを測定した。その結果を表６に示す。な
お、未凝固厚みはＦｅＳ添加法により測定した。Example 1 As a continuous casting machine, a curved continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and molten metal 3 had a degree of superheat of molten steel ΔT20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates, the mold 1 having the structure shown in FIG.
Casting, casting speed 0.8m / min, mold length 700
When a slab slab having a thickness of 250 mm and a width of 2000 mm is cast through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the specifications of the secondary cooling device shown in Table 4 and the continuous casting shown in Table 5 are used. According to the roll specifications, a slab slab was obtained by lightly reducing the final zone of solidification with a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab were measured, and the unsolidified thickness difference D _max -D _min in the slab width direction on the rolling zone entering side was measured. It was measured. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００６４】実施例２ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から図３に示す構造で表３に示す仕様の鋳型１
に鋳込み、鋳造速度０．８ｍ／ｍｉｎ、鋳型長さ７００
ｍｍで厚さ２５０ｍｍ、幅２０００ｍｍのスラブ鋳片を
サポートロール群６、圧下ロール群７、そしてピンチロ
ール８を経て鋳造するに際し、表４に示す２次冷却装置
の仕様、表５に示す連鋳ロールの仕様で、圧下ゾーン長
５ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラブ
鋳片とした。得られたスラブ鋳片のスラブエッジからの
距離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共
に、圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差
Ｄ_max−Ｄ_minを測定した。その結果を表６に示す。な
お、未凝固厚みはＦｅＳ添加法により測定した。Example 2 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates, the mold 1 having the structure shown in FIG.
Casting, casting speed 0.8m / min, mold length 700
When a slab slab having a thickness of 250 mm and a width of 2000 mm is cast through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the specifications of the secondary cooling device shown in Table 4 and the continuous casting shown in Table 5 are used. According to the roll specifications, a slab slab was obtained by lightly reducing the final zone of solidification with a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab were measured, and the unsolidified thickness difference D _max -D _min in the slab width direction on the rolling zone entering side was measured. It was measured. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００６５】実施例３ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から図４に示す構造で表３に示す仕様の鋳型１
に鋳込み、鋳造速度０．８ｍ／ｍｉｎ、鋳型長さ７００
ｍｍで厚さ２５０ｍｍ、幅２０００ｍｍのスラブ鋳片を
サポートロール群６、圧下ロール群７、そしてピンチロ
ール８を経て鋳造するに際し、表４に示す２次冷却装置
の仕様、表５に示す連鋳ロールの仕様で、圧下ゾーン長
５ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラブ
鋳片とした。得られたスラブ鋳片のスラブエッジからの
距離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共
に、圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差
Ｄ_max−Ｄ_minを測定した。その結果を表６に示す。な
お、未凝固厚みはＦｅＳ添加法により測定した。Example 3 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates, the mold 1 having the structure shown in FIG.
Casting, casting speed 0.8m / min, mold length 700
When a slab slab having a thickness of 250 mm and a width of 2000 mm is cast through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the specifications of the secondary cooling device shown in Table 4 and the continuous casting shown in Table 5 are used. According to the roll specifications, a slab slab was obtained by lightly reducing the final zone of solidification with a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab were measured, and the unsolidified thickness difference D _max -D _min in the slab width direction on the rolling zone entering side was measured. It was measured. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００６６】実施例４ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から図５に示す構造で表３に示す仕様の鋳型１
に鋳込み、鋳造速度０．８ｍ／ｍｉｎ、鋳型長さ７００
ｍｍで厚さ２５０ｍｍ、幅２０００ｍｍのスラブ鋳片を
サポートロール群６、圧下ロール群７、そしてピンチロ
ール８を経て鋳造するに際し、表４に示す２次冷却装置
の仕様、表５に示す連鋳ロールの仕様で、圧下ゾーン長
５ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラブ
鋳片とした。得られたスラブ鋳片のスラブエッジからの
距離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共
に、圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差
Ｄ_max−Ｄ_minを測定した。その結果を表６に示す。な
お、未凝固厚みはＦｅＳ添加法により測定した。Example 4 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates, the mold 1 having the structure shown in FIG.
Casting, casting speed 0.8m / min, mold length 700
When a slab slab having a thickness of 250 mm and a width of 2000 mm is cast through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the specifications of the secondary cooling device shown in Table 4 and the continuous casting shown in Table 5 are used. According to the roll specifications, a slab slab was obtained by lightly reducing the final zone of solidification with a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab were measured, and the unsolidified thickness difference D _max -D _min in the slab width direction on the rolling zone entering side was measured. It was measured. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００６７】実施例５ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から図６に示す構造で表３に示す仕様の鋳型１
に鋳込み、鋳造速度０．８ｍ／ｍｉｎ、鋳型長さ７００
ｍｍで厚さ２５０ｍｍ、幅２０００ｍｍのスラブ鋳片を
サポートロール群６、圧下ロール群７、そしてピンチロ
ール８を経て鋳造するに際し、表４に示す２次冷却装置
の仕様、表５に示す連鋳ロールの仕様で、圧下ゾーン長
５ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラブ
鋳片とした。得られたスラブ鋳片のスラブエッジからの
距離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共
に、圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差
Ｄ_max−Ｄ_minを測定した。その結果を表６に示す。な
お、未凝固厚みはＦｅＳ添加法により測定した。Example 5 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a molten steel superheat degree ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plate, the mold 1 having the structure shown in FIG.
Casting, casting speed 0.8m / min, mold length 700
When a slab slab having a thickness of 250 mm and a width of 2000 mm is cast through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the specifications of the secondary cooling device shown in Table 4 and the continuous casting shown in Table 5 are used. According to the roll specifications, a slab slab was obtained by lightly reducing the final zone of solidification with a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab were measured, and the unsolidified thickness difference D _max -D _min in the slab width direction on the rolling zone entering side was measured. It was measured. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００６８】実施例６ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から従来の鋳型１に鋳込み、鋳造速度０．８ｍ
／ｍｉｎ、鋳型長さ７００ｍｍで厚さ２５０ｍｍ、幅２
０００ｍｍのスラブ鋳片をサポートロール群６、圧下ロ
ール群７、そしてピンチロール８を経て鋳造するに際
し、図１（ｂ）に示す構造の２次冷却装置を使用し、表
４に示す２次冷却装置の仕様、表５に示す連鋳ロールの
仕様で、圧下ゾーン長５ｍ、圧下勾配１ｍｍ／ｍで凝固
末期軽圧下してスラブ鋳片とした。得られたスラブ鋳片
のスラブエッジからの距離（ｍｍ）とＣ偏析度（Ｃ／Ｃ
₀）を測定すると共に、圧下ゾーン入り側でのスラブ幅
方向の未凝固厚み差Ｄ_max−Ｄ_minを測定した。その結果
を表６に示す。なお、未凝固厚みはＦｅＳ添加法により
測定した。Example 6 A bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used as the continuous casting machine, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates is cast from the immersion nozzle 2 into the conventional mold 1, and the casting speed is 0.8 m.
/ Min, mold length 700 mm, thickness 250 mm, width 2
When casting a 000 mm slab slab through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the secondary cooling device having the structure shown in FIG. According to the equipment specifications and the specifications of the continuous casting roll shown in Table 5, a slab slab was obtained by lightly reducing the final stage of solidification with a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge of the obtained slab slab and the C segregation degree (C / C
₀ ) and the unsolidified thickness difference D _max -D _min in the slab width direction on the side of entering the reduction zone. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００６９】実施例７ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から従来の鋳型１に鋳込み、鋳造速度０．８ｍ
／ｍｉｎ、鋳型長さ７００ｍｍで厚さ２５０ｍｍ、幅２
０００ｍｍのスラブ鋳片をサポートロール群６、圧下ロ
ール群７、そしてピンチロール８を経て鋳造するに際
し、図７に示す構造の支持ロール群、圧下ロール群、ピ
ンチロール群を使用し、表４に示す２次冷却装置の仕
様、表５に示す連鋳ロールの仕様で、圧下ゾーン長５
ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラブ鋳
片とした。得られたスラブ鋳片のスラブエッジからの距
離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共に、
圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差Ｄ
_max−Ｄ_minを測定した。その結果を表６に示す。なお、
未凝固厚みはＦｅＳ添加法により測定した。Example 7 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 was molten steel superheat degree ΔT 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates is cast from the immersion nozzle 2 into the conventional mold 1, and the casting speed is 0.8 m.
/ Min, mold length 700 mm, thickness 250 mm, width 2
When casting a 000 mm slab slab through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the support roll group, the reduction roll group, and the pinch roll group having the structure shown in FIG. 7 are used. With the specifications of the secondary cooling device shown and the specifications of the continuous casting rolls shown in Table 5, the reduction zone length is 5
m, a reduction gradient of 1 mm / m, and lightly reduced at the final stage of solidification to obtain a slab slab. While measuring the distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab,
Unsolidified thickness difference D in the width direction of the slab on the side entering the reduction zone
_{The max-} D _min was measured. The results are shown in Table 6. In addition,
The unsolidified thickness was measured by the FeS addition method.

【００７０】実施例８ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から従来の鋳型１に鋳込み、鋳造速度０．８ｍ
／ｍｉｎ、鋳型長さ７００ｍｍで厚さ２５０ｍｍ、幅２
０００ｍｍのスラブ鋳片をサポートロール群６、圧下ロ
ール群７、そしてピンチロール８を経て鋳造するに際
し、図８に示す構造の支持ロール群、圧下ロール群、ピ
ンチロール群を使用し、表４に示す２次冷却装置の仕
様、表５に示す連鋳ロールの仕様で、圧下ゾーン長５
ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラブ鋳
片とした。得られたスラブ鋳片のスラブエッジからの距
離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共に、
圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差Ｄ
_max−Ｄ_minを測定した。その結果を表６に示す。なお、
未凝固厚みはＦｅＳ添加法により測定した。Example 8 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates is cast from the immersion nozzle 2 into the conventional mold 1, and the casting speed is 0.8 m.
/ Min, mold length 700 mm, thickness 250 mm, width 2
When casting a 000 mm slab slab through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the support roll group, the reduction roll group, and the pinch roll group having the structure shown in FIG. 8 are used. With the specifications of the secondary cooling device shown and the specifications of the continuous casting rolls shown in Table 5, the reduction zone length is 5
m, a reduction gradient of 1 mm / m, and lightly reduced at the final stage of solidification to obtain a slab slab. While measuring the distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab,
Unsolidified thickness difference D in the width direction of the slab on the side entering the reduction zone
_{The max-} D _min was measured. The results are shown in Table 6. In addition,
The unsolidified thickness was measured by the FeS addition method.

【００７１】実施例９ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から図３に示す構造で表３に示す仕様の鋳型１
に鋳込み、鋳造速度０．８ｍ／ｍｉｎ、鋳型長さ７００
ｍｍで厚さ２５０ｍｍ、幅２０００ｍｍのスラブ鋳片を
サポートロール群６、圧下ロール群７、そしてピンチロ
ール８を経て鋳造するに際し、図１（ｂ）に示す構造の
２次冷却装置を使用し、表４に示す２次冷却装置の仕
様、表５に示す連鋳ロールの仕様で、圧下ゾーン長５
ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラブ鋳
片とした。得られたスラブ鋳片のスラブエッジからの距
離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共に、
圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差Ｄ
_max−Ｄ_minを測定した。その結果を表６に示す。なお、
未凝固厚みはＦｅＳ添加法により測定した。Example 9 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates, the mold 1 having the structure shown in FIG.
Casting, casting speed 0.8m / min, mold length 700
When a slab slab having a thickness of 250 mm, a width of 2000 mm and a width of 2000 mm is cast through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the secondary cooling device having the structure shown in FIG. 1 (b) is used, With the specifications of the secondary cooling device shown in Table 4 and the specifications of the continuous casting rolls shown in Table 5, a reduction zone length of 5
m, a reduction gradient of 1 mm / m, and lightly reduced at the final stage of solidification to obtain a slab slab. While measuring the distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab,
Unsolidified thickness difference D in the width direction of the slab on the side entering the reduction zone
_{The max-} D _min was measured. The results are shown in Table 6. In addition,
The unsolidified thickness was measured by the FeS addition method.

【００７２】実施例１０ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から図３に示す構造で表３に示す仕様の鋳型１
に鋳込み、鋳造速度０．８ｍ／ｍｉｎ、鋳型長さ７００
ｍｍで厚さ２５０ｍｍ、幅２０００ｍｍのスラブ鋳片を
サポートロール群６、圧下ロール群７、そしてピンチロ
ール８を経て鋳造するに際し、支持ロール６群の一部と
して図８に示す構造の支持ロールを使用し、表４に示す
２次冷却装置の仕様、表５に示す連鋳ロールの仕様で、
圧下ゾーン長５ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧
下してスラブ鋳片とした。得られたスラブ鋳片のスラブ
エッジからの距離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測
定すると共に、圧下ゾーン入り側でのスラブ幅方向の未
凝固厚み差Ｄ_max−Ｄ_minを測定した。その結果を表６に
示す。なお、未凝固厚みはＦｅＳ添加法により測定し
た。Example 10 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates, the mold 1 having the structure shown in FIG.
Casting, casting speed 0.8m / min, mold length 700
When casting a slab slab having a thickness of 250 mm and a width of 2000 mm through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the support roll having the structure shown in FIG. The specifications of the secondary cooling device shown in Table 4 and the specifications of the continuous casting roll shown in Table 5 are used.
A slab slab was obtained by lightly reducing the final stage of solidification at a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab were measured, and the unsolidified thickness difference D _max -D _min in the slab width direction on the rolling zone entering side was measured. It was measured. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００７３】実施例１１ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から従来の鋳型１に鋳込み、鋳造速度０．８ｍ
／ｍｉｎ、鋳型長さ７００ｍｍで厚さ２５０ｍｍ、幅２
０００ｍｍのスラブ鋳片をサポートロール群６、圧下ロ
ール群７、そしてピンチロール８を経て鋳造するに際
し、図１（ｂ）に示す構造の２次冷却装置と支持ロール
群の一部として図８に示す構造の支持ロールを使用し、
表４に示す２次冷却装置の仕様、表５に示す連鋳ロール
の仕様で、圧下ゾーン長５ｍ、圧下勾配１ｍｍ／ｍで凝
固末期軽圧下してスラブ鋳片とした。得られたスラブ鋳
片のスラブエッジからの距離（ｍｍ）とＣ偏析度（Ｃ／
Ｃ₀）を測定すると共に、圧下ゾーン入り側でのスラブ
幅方向の未凝固厚み差Ｄ_max−Ｄ_minを測定した。その結
果を表６に示す。なお、未凝固厚みはＦｅＳ添加法によ
り測定した。Example 11 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates is cast from the immersion nozzle 2 into the conventional mold 1, and the casting speed is 0.8 m.
/ Min, mold length 700 mm, thickness 250 mm, width 2
When casting a 000 mm slab slab through the support roll group 6, the reduction roll group 7, and the pinch roll 8, as a part of the secondary cooling device and the support roll group having the structure shown in FIG. Use the support roll of the structure shown,
Using the specifications of the secondary cooling device shown in Table 4 and the specifications of the continuous casting roll shown in Table 5, a slab slab was obtained by lightly reducing the final stage of solidification with a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge of the obtained slab slab and the C segregation degree (C /
C ₀ ) was measured, and the unsolidified thickness difference D _max −D _min in the slab width direction on the rolling zone entry side was measured. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００７４】実施例１２ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から図３に示す構造で表３に示す仕様の鋳型１
に鋳込み、鋳造速度０．８ｍ／ｍｉｎ、鋳型長さ７００
ｍｍで厚さ２５０ｍｍ、幅２０００ｍｍのスラブ鋳片を
サポートロール群６、圧下ロール群７、そしてピンチロ
ール８を経て鋳造するに際し、図１（ｂ）に示す構造の
２次冷却装置と支持ロール群の一部として図８に示す構
造の支持ロールを使用し、表４に示す２次冷却装置の仕
様、表５に示す連鋳ロールの仕様で、圧下ゾーン長５
ｍ、圧下勾配１ｍｍ／ｍで凝固末期軽圧下してスラブ鋳
片とした。得られたスラブ鋳片のスラブエッジからの距
離（ｍｍ）とＣ偏析度（Ｃ／Ｃ₀）を測定すると共に、
圧下ゾーン入り側でのスラブ幅方向の未凝固厚み差Ｄ
_max−Ｄ_minを測定した。その結果を表６に示す。なお、
未凝固厚みはＦｅＳ添加法により測定した。Example 12 As the continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates, the mold 1 having the structure shown in FIG.
Casting, casting speed 0.8m / min, mold length 700
When casting a slab slab having a thickness of 250 mm and a width of 2000 mm through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the secondary cooling device and the support roll group having the structure shown in FIG. 8 is used as a part of the structure, the specifications of the secondary cooling device shown in Table 4 and the specifications of the continuous casting roll shown in Table 5 are used, and the reduction zone length is 5
m, a reduction gradient of 1 mm / m, and lightly reduced at the final stage of solidification to obtain a slab slab. While measuring the distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab,
Unsolidified thickness difference D in the width direction of the slab on the side entering the reduction zone
_{The max-} D _min was measured. The results are shown in Table 6. In addition,
The unsolidified thickness was measured by the FeS addition method.

【００７５】比較例１ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から溝が長辺面全幅にわたって設置されている
表３に示す仕様の鋳型１に鋳込み、鋳造速度０．８ｍ／
ｍｉｎ、鋳型長さ７００ｍｍで厚さ２５０ｍｍ、幅２０
００ｍｍのスラブ鋳片をサポートロール群６、圧下ロー
ル群７、そしてピンチロール８を経て鋳造するに際し、
２次冷却装置の幅方向冷却制御と支持ロール、圧下ロー
ル及び、ピンチロールの幅方向冷却制御がされていない
表４に示す２次冷却装置の仕様、表５に示す連鋳ロール
の仕様で、圧下ゾーン長５ｍ、圧下勾配１ｍｍ／ｍで凝
固末期軽圧下してスラブ鋳片とした。得られたスラブ鋳
片のスラブエッジからの距離（ｍｍ）とＣ偏析度（Ｃ／
Ｃ₀）を測定すると共に、圧下ゾーン入り側でのスラブ
幅方向の未凝固厚み差Ｄ_max−Ｄ_minを測定した。その結
果を表６に示す。なお、未凝固厚みはＦｅＳ添加法によ
り測定した。Comparative Example 1 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a degree of superheat of molten steel ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates is cast from the dipping nozzle 2 into the mold 1 having the specifications shown in Table 3 in which grooves are installed over the entire width of the long side surface, and the casting speed is 0.8 m. /
min, mold length 700 mm, thickness 250 mm, width 20
When casting a 00 mm slab slab through the support roll group 6, the reduction roll group 7, and the pinch roll 8,
In the width direction cooling control of the secondary cooling device and the support roll, the reduction roll, and the width direction cooling control of the pinch roll, the specifications of the secondary cooling device shown in Table 4 and the specifications of the continuous casting roll shown in Table 5 are used. A slab slab was obtained by lightly reducing the final stage of solidification at a reduction zone length of 5 m and a reduction gradient of 1 mm / m. The distance (mm) from the slab edge of the obtained slab slab and the C segregation degree (C /
C ₀ ) was measured, and the unsolidified thickness difference D _max −D _min in the slab width direction on the rolling zone entry side was measured. The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００７６】比較例２ 連鋳機として図９に示す湾曲半径１２．５ｍの湾曲型連
鋳機を使用し、溶融金属３として溶鋼過熱度ΔＴ２０℃
のＣ：０．１５〜０．２０％の厚板用４０Ｋ鋼を、浸漬
ノズル２から従来の鋳型１に鋳込み、鋳造速度０．８ｍ
／ｍｉｎ、鋳型長さ７００ｍｍで厚さ２５０ｍｍ、幅２
０００ｍｍのスラブ鋳片をサポートロール群６、圧下ロ
ール群７、そしてピンチロール８を経て鋳造するに際
し、２次冷却装置の幅方向冷却制御と支持ロール、圧下
ロール及び、ピンチロールの幅方向冷却制御がされてい
ない表４に示す２次冷却装置の仕様、表５に示す連鋳ロ
ールの仕様で、圧下ゾーン長５ｍ、圧下勾配１ｍｍ／ｍ
で凝固末期軽圧下してスラブ鋳片とした。得られたスラ
ブ鋳片のスラブエッジからの距離（ｍｍ）とＣ偏析度
（Ｃ／Ｃ₀）を測定すると共に、圧下ゾーン入り側での
スラブ幅方向の未凝固厚み差Ｄ_max−Ｄ_minを測定した。
その結果を表６に示す。なお、未凝固厚みはＦｅＳ添加
法により測定した。Comparative Example 2 As a continuous casting machine, a bending type continuous casting machine having a bending radius of 12.5 m shown in FIG. 9 was used, and the molten metal 3 had a molten steel superheat degree ΔT of 20 ° C.
C: 0.15 to 0.20% of 40K steel for thick plates is cast from the immersion nozzle 2 into the conventional mold 1, and the casting speed is 0.8 m.
/ Min, mold length 700 mm, thickness 250 mm, width 2
When casting a 000 mm slab slab through the support roll group 6, the reduction roll group 7, and the pinch roll 8, the width direction cooling control of the secondary cooling device and the support roll, the reduction roll, and the pinch roll width direction cooling control are performed. With the specifications of the secondary cooling device shown in Table 4 and the specifications of the continuous casting roll shown in Table 5, the reduction zone length is 5 m and the reduction gradient is 1 mm / m.
At the end of solidification, a light reduction was applied to form a slab slab. The distance (mm) from the slab edge and the C segregation degree (C / C ₀ ) of the obtained slab slab were measured, and the unsolidified thickness difference D _max -D _min in the slab width direction on the rolling zone entering side was measured. It was measured.
The results are shown in Table 6. The unsolidified thickness was measured by the FeS addition method.

【００７７】[0077]

【表３】 [Table 3]

【００７８】[0078]

【表４】 [Table 4]

【００７９】[0079]

【表５】 [Table 5]

【００８０】[0080]

【表６】 [Table 6]

【００８１】表６から明らかなように、比較例１，２の
従来の連鋳法は、スラブエッジに近い位置の中心偏析が
著しかったが、本発明の実施例１〜１２の場合は、いず
れもエッジに近い部分の中心偏析が大幅に低減され、巾
方向に均一な組成で且つＣ偏析度が１．００近傍の良好
な鋳片を製造することができた。また、厳密に見れば、
実施例４，１２は幅中央の緩冷却が効きすぎて未凝固厚
み差Ｄ_max−Ｄ_min≦−２となりＵ型不均一凝固となった
ため、幅中央部のＣ偏析度が微増している。しかし、こ
れとて実用上問題とはならない。なお、実施例９〜１２
は、実施例３の鋳型と２次冷却、ロール冷却の幅方向冷
却制御を組み合わせたものであるが、明らかに緩冷却能
は向上し、Ｗ型不均一凝固の緩和に寄与している。As is clear from Table 6, in the conventional continuous casting methods of Comparative Examples 1 and 2, the center segregation at the position close to the slab edge was remarkable, but in the cases of Examples 1 to 12 of the present invention, The center segregation of the portion near the edge was significantly reduced, and a good cast piece having a uniform composition in the width direction and a C segregation degree of about 1.00 could be manufactured. Also, strictly speaking,
In Examples 4 and 12, moderate cooling at the center of the width was too effective and the unsolidified thickness difference D _max −D _min ≦ −2, resulting in U-shaped non-uniform solidification, and thus the degree of C segregation at the center of the width slightly increased. However, this is not a practical problem. In addition, Examples 9 to 12
Is a combination of the mold of Example 3 and the widthwise cooling control of the secondary cooling and the roll cooling, but the slow cooling capacity is obviously improved and contributes to the alleviation of the W-type non-uniform solidification.

【００８２】ブレークアウト発生頻度は、本発明の実施
例１，２では凹部幅Ｗを小さくすることにより、従来鋳
型の場合と同等のブレークアウト頻度とすることが可能
であった。また、本発明の実施例３〜５、９〜１０、１
２においては、従来鋳型の場合と同等のブレークアウト
頻度であった。In the first and second embodiments of the present invention, the breakout frequency can be made equal to that of the conventional mold by reducing the recess width W. In addition, Examples 3 to 5, 9 to 10 and 1 of the present invention
In No. 2, the breakout frequency was the same as that of the conventional mold.

【００８３】[0083]

【発明の効果】以上述べたとおり、この発明の連続鋳造
方法および装置によれば、スラブの幅方向の不均一凝固
が解消され、凝固末期の軽圧下が幅方向に均一に行わ
れ、幅端部の中心偏析が大幅に改善され、幅方向全域で
均一組成となり、かつ中心偏析のない鋳片を安定して鋳
造することが可能となる。As described above, according to the continuous casting method and apparatus of the present invention, the uneven solidification in the width direction of the slab is eliminated, and the light reduction at the final stage of solidification is uniformly performed in the width direction. The center segregation of the portion is significantly improved, and it becomes possible to stably cast a slab having a uniform composition in the entire width direction and having no center segregation.

【図面の簡単な説明】[Brief description of drawings]

【図１】この発明の連続鋳造方法における冷却の数例を
示すもので、（ａ）図は鋳型による幅中央部緩冷却の例
を、（ｂ）図は２次冷却による幅中央部緩冷却の例を、
（ｃ）図はロールによる幅中央部緩冷却の例を示す図で
ある。FIG. 1 shows several examples of cooling in the continuous casting method of the present invention. FIG. 1 (a) is an example of moderate cooling in the width center part by a mold, and FIG. 1 (b) is a moderate cooling in the width center part by secondary cooling. Example of
FIG. 6C is a diagram showing an example of gentle cooling in the width center portion by a roll.

【図２】この発明の凹部が凹条形状である鋳型の一例を
示すもので、（ａ）図は鋳型の平面図、（ｂ）図は鋳型
長辺面を内面（溶鋼側の面）から見た図、（ｃ）図は凝
固シェルの生成状況を示す縦断面図である。2A and 2B show an example of a mold in which the concave portions of the present invention are in the form of ridges. FIG. 2A is a plan view of the mold, and FIG. 2B is a plan view of the mold long side surface from the inner surface (surface on the molten steel side). The view, (c), is a vertical cross-sectional view showing the generation state of the solidified shell.

【図３】この発明の凹部がディンプル形状である鋳型の
鋳型長辺面を内面（溶鋼側の面）から見た図である。FIG. 3 is a view of a long side surface of a mold of the present invention in which the recess has a dimple shape, as viewed from the inner surface (surface on the molten steel side).

【図４】この発明の凹部が凹条形状である他の鋳型の一
例を示すもので、（ａ）図は鋳型長辺面を内面（溶鋼側
の面）から見た図、（ｂ）図は凝固シェルの生成状況を
示す縦断面図である。4A and 4B show an example of another mold in which the concave portion of the present invention has a concave shape, in which FIG. 4A is a view of the long side surface of the mold seen from the inner surface (surface on the molten steel side), and FIG. FIG. 4 is a vertical cross-sectional view showing a generation state of a solidified shell.

【図５】この発明の鋳型の一例を示す平面図である。FIG. 5 is a plan view showing an example of the mold of the present invention.

【図６】この発明の鋳型の一例を示す平面図である。FIG. 6 is a plan view showing an example of the mold of the present invention.

【図７】この発明のロールで低熱伝導率材料の断熱層に
よる幅中央部緩冷却の一例を示す平面図である。FIG. 7 is a plan view showing an example of gentle cooling in the width center portion by the heat insulating layer of the low thermal conductivity material in the roll of the present invention.

【図８】この発明のロールで凹部による幅中央部緩冷却
の一例を示す平面図である。FIG. 8 is a plan view showing an example of moderate cooling of the width center portion by the concave portion in the roll of the present invention.

【図９】実施例で使用した連続鋳造装置の一例を示す図
である。FIG. 9 is a diagram showing an example of a continuous casting apparatus used in Examples.

【図１０】従来鋳型で鋳造したスラブの幅方向不均一凝
固の概念図で、（ａ）図は鋳造中のスラブの横断面を示
す概念図、（ｂ）図は鋳造中のスラブの縦断面を示す概
念図、（ｃ）図は製品スラブの中心偏析発生状況の概念
図である。FIG. 10 is a conceptual diagram of uneven solidification in the width direction of a slab cast by a conventional mold, where (a) is a conceptual diagram showing a cross section of the slab during casting, and (b) is a longitudinal section of the slab during casting. And (c) are conceptual diagrams of the state of center segregation of the product slab.

【図１１】スラブの幅方向不均一凝固の原因の一つと考
えられる浸漬ノズルから吐出される溶鋼流れを示した概
念図である。FIG. 11 is a conceptual diagram showing a flow of molten steel discharged from an immersion nozzle which is considered to be one of causes of uneven solidification in the width direction of a slab.

【図１２】この発明の鋳型を使用した場合と従来鋳型を
使用した場合の凝固状況を比較した概念図で、（ａ）図
はこの発明により幅方向の凝固シェル生成状況が均一に
なった場合を示す概念図、（ｂ）図は従来のＷ型不均一
凝固を示す概念図、（ｃ）図はこの発明により幅中央を
緩冷却し過ぎた場合のＵ型不均一凝固を示す概念図であ
る。FIG. 12 is a conceptual diagram comparing the solidification states of the case of using the mold of the present invention and the case of using the conventional mold. FIG. 12 (a) is a case in which the situation of forming solidified shells in the width direction is uniform according to the present invention. Is a conceptual diagram showing conventional W-type non-uniform solidification, and (c) is a conceptual diagram showing U-type non-uniform solidification when the center of the width is excessively cooled by the present invention. is there.

【図１３】図１２の（ａ）〜（ｃ）の場合の鋳型出口に
おける鋳片の表面温度の幅方向分布を示す概念図であ
る。FIG. 13 is a conceptual diagram showing the widthwise distribution of the surface temperature of a cast piece at the mold outlet in the case of (a) to (c) of FIG.

【図１４】鋳型内壁と鋳片との間のエアーギャップ量と
伝熱抵抗との関係を示すグラフである。FIG. 14 is a graph showing the relationship between the heat transfer resistance and the amount of air gap between the inner wall of the mold and the slab.

【図１５】この発明鋳型における凹部ゾーンの上縁とメ
ニスカスと間の距離Ｈと鋳型出口シェル厚との関係を示
すグラフである。FIG. 15 is a graph showing the relationship between the distance H between the upper edge of the recessed zone and the meniscus in the inventive mold and the mold outlet shell thickness.

【図１６】この発明の鋳型において隣合う凹部の間隔Ｉ
が大きい場合の凝固シェル生成状況を示す概念図であ
る。FIG. 16 is a space I between adjacent recesses in the mold of the present invention.
It is a conceptual diagram which shows the solidification shell production | generation situation when is large.

【図１７】スラブの未凝固厚み差Ｄ_max−Ｄ_minの定義図
である。FIG. 17 is a definition diagram of an unsolidified thickness difference D _max −D _min of a slab.

【図１８】従来の段差厚鋳型の概念図である。FIG. 18 is a conceptual view of a conventional step thickness mold.

【図１９】スラブ幅端部および幅中央部の未凝固厚み差
Ｄ_max−Ｄ_minとＣ偏析度の関係を示すグラフである。FIG. 19 is a graph showing the relationship between the unsolidified thickness difference D _max −D _min at the slab width end and the width center and the C segregation degree.

【図２０】鋳片凝固開始位置から鋳片凝固終了までの緩
冷却率Ｓ．Ｃ．Ｒ．と未凝固厚み差Ｄ_max−Ｄ_minとの関
係を示すグラフである。FIG. 20: Slow cooling rate S. from the solidification start position of the slab to the end of solidification of the slab. C. R. It is a graph which shows the relationship between the unsolidified thickness difference _{Dmax- Dmin} .

【図２１】この発明適用時と従来の場合のそれぞれの未
凝固厚み差Ｄ_max−Ｄ_minの鋳造方向の経時的変化を示す
もので、（ａ）図は従来鋳造装置の場合と本願の第２、
第４〜第６発明を適用した場合を示すグラフ、（ｂ）は
従来鋳造装置の場合と本願の第３、第７〜８および本願
発明を組合せたＫの場合を示すグラフである。FIG. 21 shows changes over time in the casting direction of the unsolidified thickness difference D _max -D _min in the case of applying the present invention and in the conventional case. FIG. 21 (a) shows the case of the conventional casting apparatus and that of the present application. 2,
The graph which shows the case where 4th-6th invention is applied, (b) is a graph which shows the case of the conventional casting device and the case of K which combined 3rd, 7th-8 of this application, and this invention.

【図２２】本願の第４、第５発明の鋳型を使用した場合
の幅中央部の凹部深さｄ_mと凹部ゾーン面積率α_mが未凝
固厚み差Ｄ_max−Ｄ_minに及ぼす影響を示すグラフで、
（ａ）図は本願の第４発明の鋳型を使用した場合のグラ
フ、（ｂ）図は本願の第５発明の鋳型を使用した場合の
グラフである。FIG. 22 shows the influence of the recess depth d _m and the recess zone area ratio α _{m in} the width center on the unsolidified thickness difference D _max -D _min when the molds of the fourth and fifth inventions of the present application are used. In the graph,
(A) is a graph when the mold of the fourth invention of the present application is used, and (b) is a graph when the mold of the fifth invention of the present application is used.

【図２３】鋳型冷却水流速ｕと鋳型表面温度Ｔ_surfの関
係を示すグラフである。FIG. 23 is a graph showing the relationship between the mold cooling water flow rate u and the mold surface temperature T _surf .

【図２４】本願の第２発明を適用した場合と、幅方向の
鋳型冷却水流速のみを制御した場合の鋳型の幅中央部の
鋳型冷却水流速ｕ_cと中央部以外の鋳型冷却水流速ｕ_eの
比ｕ_c／ｕ_e×１００と未凝固厚み差Ｄ_max−Ｄ_minの関係
を示すグラフである。FIG. 24 shows the mold cooling water flow rate u _c at the center of the width of the mold and the mold cooling water flow rate u other than the center when the second invention of the present application is applied and when only the mold cooling water flow rate in the width direction is controlled. is a graph showing the relationship between the specific u _c / u _e × 100 as unsolidified thickness difference D _max -D _min of _e.

【図２５】鋳型冷却水の面から鋳型溶鋼面の距離ｄ₁と
鋳型表面温度Ｔ_surfの関係を示すグラフである。FIG. 25 is a graph showing the relationship between the mold surface temperature T _surf and the distance d ₁ from the mold cooling water surface to the mold molten steel surface.

【図２６】本願の第６発明の鋳型幅方向の鋳型冷却水流
速のみを制御した鋳型の幅中央部と幅中央部以外の鋳型
冷却水の面から鋳型溶鋼面の距離ｄ₁の差Δｄ₁と未凝固
厚み差Ｄ_max−Ｄ_minとの関係を示すグラフである。FIG. 26 is a difference Δd _{1 in} the distance d ₁ from the mold cooling water surface to the mold molten steel surface other than the center of the width of the mold in which only the mold cooling water flow velocity in the mold width direction of the sixth invention of the present application is controlled. It is a graph which shows the relationship between the unsolidified thickness difference _{Dmax- Dmin} .

【図２７】本願の第３発明の２次冷却装置の幅中央部の
水量密度Ｑ_cと中央部以外の水量密度Ｑ_e比Ｑ_c／Ｑ_e×１
００と未凝固厚み差Ｄ_max−Ｄ_minとの関係を示すグラフ
である。FIG. 27 is a ratio Q _c / Q _e × 1 of the water amount density Q _c at the center of the width and the water amount density Q _{e at} other than the center of the secondary cooling device of the third invention of the present application
It is a graph which shows the relationship of 00 and unsolidified thickness difference _{Dmax- Dmin} .

【図２８】本願の第７発明の連鋳ロールの幅中央部の断
熱層厚みｔと未凝固厚み差Ｄ_max−Ｄ_minとの関係を示す
グラフである。FIG. 28 is a graph showing the relationship between the thickness t of the heat insulating layer at the center of the width of the continuous casting roll of the seventh invention of the present application and the unsolidified thickness difference D _max −D _min .

【図２９】本願の第８発明の連鋳ロールの幅中央部の凹
部深さｄ_rと凹部ゾーン面積率α_rが未凝固厚み差Ｄ_max
−Ｄ_minに及ぼす影響を示すグラフである。FIG. 29 is a non-solidified thickness difference D _max between the recess depth d _r and the recess zone area ratio α _{r in} the width center portion of the continuous casting roll of the eighth invention of the present application.
Is a graph showing the effect on -D _min.

【図３０】本願の第４発明の鋳型を使用した場合、本願
の第４発明の鋳型と本願の第３発明の二次冷却を使用し
た第９発明の場合、本願の第４発明の鋳型と本願の第８
発明の連続鋳造用ロールを使用した第１０発明の場合、
本願の第４発明の鋳型と本願の第３発明の二次冷却と本
願の第８発明の連続鋳造用ロールを使用した第１２発明
の場合のそれぞれの鋳型凹部深さｄ_mと未凝固厚み差Ｄ
_max−Ｄ_minとの関係を示すグラフである。FIG. 30 shows the mold of the fourth invention of the present application and the mold of the fourth invention of the present application in the case of the ninth invention of using the secondary cooling of the third invention of the present application when the mold of the fourth invention of the present application is used. Eighth of the present application
In the case of the tenth invention using the continuous casting roll of the invention,
The respective mold recess depths d _m and unsolidified thickness differences in the case of the twelfth invention using the mold of the fourth invention of the present application, the secondary cooling of the third invention of the present application, and the continuous casting roll of the eighth invention of the present application D
It is a graph which shows the relationship with _{max- Dmin} .

【符号の説明】[Explanation of symbols]

１１ 鋳型長辺面 １２ 鋳型短辺面 １ａ、６ａ、７ａ、８ａ 凹部 １ｂ 凹部設置ゾーン １ｃ 凹部未設置ゾーン １ｄ メニスカス １ｅ 凹無部 １ｆ 鋳型冷却水路 １ｇ 段差部 １ｈ 緩冷却ゾーン １ｉ 緩冷却手段付与部 １ｊ 冷却水低減ゾーン（幅中央部） １ｋ 冷却水未低減ゾーン（幅中央部以外） １ｌ 鋳型のｄ₁が小さい部分（幅中央部） １ｍ 鋳型のｄ₁が大きい部分（幅中央部以外） １ｎ 鋳型の冷却水の面 １ｏ 鋳型の溶鋼側の面 ２ 浸漬ノズル ３ 溶融金属 ３ａ 凝固遅れ部 ４ 凝固シェル ４ａ 圧下抵抗の大きい部分 ５ パウダー ６₁ エアーギャップ ６ サポートロール群 ７ 圧下ロール群 ８ ピンチロール ６ｂ、７ｂ、８ｂ 断熱層 ６ｃ、７ｃ、８ｃ 緩冷却手段未設置ゾーン ６ｅ、７ｅ、８ｅ 凹無部 ６ｈ、７ｈ、８ｈ 緩冷却ゾーン ９ ２次冷却装置 ９ｃ 非緩冷却ゾーン ９ｈ 緩冷却ゾーン ９ｉ 緩冷却ゾーン内のスプレー ９ｊ 非緩冷却ゾーン内のスプレー １０ 鋳片11 mold long side surface 12 mold short side surface 1a, 6a, 7a, 8a recess 1b recess installation zone 1c recess not installed zone 1d meniscus 1e no recess 1f mold cooling water channel 1g step 1h slow cooling zone 1i slow cooling means applying part 1j Cooling water reduced zone (central width portion) 1k Cooling water non-reduced zone (other than central width portion) 1l Part with small d _{1 of} mold (central width portion) 1m Part with large d _{1 of} mold (other than central width portion) 1n Surface of cooling water of mold 1o Surface of molten steel of mold 2 Immersion nozzle 3 Molten metal 3a Solidification delay part 4 Solidification shell 4a Larger reduction resistance part 5 Powder 6 ₁ Air gap 6 Support roll group 7 Reduction roll group 8 Pinch roll 6b , 7b, 8b Heat-insulating layer 6c, 7c, 8c Slow cooling means non-installed zone 6e, 7e, 8e No concave portion 6h, 7h, 8h Slow cooling zone 9 Spray 10 sprays 9j non slow cooling zone follows the cooling device 9c non slow cooling zone 9h in slow cooling zone 9i slow cooling zone slab

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.⁶ 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｂ２２Ｄ 11/128 ３４０ Ｂ (72)発明者 笠井 宣文 茨城県鹿島郡鹿島町大字光３番地 住友金 属工業株式会社鹿島製鉄所内─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B22D 11/128 340 B (72) Inventor Nobufumi Kasai 3rd light, Kashima-cho, Kashima-gun, Ibaraki Sumitomo Kashima Steel Works, Kinka Kogyo Co., Ltd.

Claims (12)

【特許請求の範囲】[Claims] 【請求項１】 スラブ形状の鋳片の連続鋳造方法におい
て、スラブ長辺面の中央部を中央部以外に比較して緩冷
却することを特徴とする連続鋳造方法。1. A continuous casting method for continuously casting a slab-shaped slab, characterized in that the central portion of the long side surface of the slab is gently cooled as compared with a portion other than the central portion. 【請求項２】 スラブ長辺面の中央部を中央部以外に比
較して緩冷却する方法において、鋳型の鋳込み方向に沿
った長辺面の中央部に多数の凹部または凹条を設け、長
辺面中央部の鋳型冷却水流速を中央部以外の冷却水流速
の７０％以下にすることを特徴とする連続鋳造方法。2. A method of slowly cooling a central portion of a long side surface of a slab as compared with a portion other than the central portion, wherein a large number of concave portions or concave lines are provided in the central portion of the long side surface along the casting direction of the mold. A continuous casting method, characterized in that the mold cooling water flow velocity in the central portion of the side surface is 70% or less of the cooling water flow velocity in portions other than the central portion. 【請求項３】 スラブ長辺面の中央部を中央部以外に比
較して緩冷却する方法において、スラブ幅中央部の２次
冷却水量密度を中央部以外の水量密度の７５％以下にす
ることを特徴とする連続鋳造方法。3. In the method of gently cooling the central part of the long side surface of the slab as compared with the part other than the central part, the secondary cooling water amount density in the central part of the slab width is set to 75% or less of the water amount density other than the central part. A continuous casting method characterized by: 【請求項４】 相対向する一対の長辺面と相対向する一
対の短辺面によって鋳造空間を画定する内壁が形成され
る断面長方形のスラブの連続鋳造用鋳型において、鋳込
み方向に沿った長辺面の中央部に多数の凹部または凹条
を設けたことを特徴とする連続鋳造用鋳型。4. A continuous casting mold of a slab having a rectangular cross section in which an inner wall defining a casting space is formed by a pair of long side faces facing each other and a pair of short side faces facing each other, and a length along a casting direction. A continuous casting mold characterized in that a large number of recesses or grooves are provided in the central portion of the side surface. 【請求項５】 鋳込み方向に沿った長辺面の中央部に多
数の凹部または凹条を設けた連続鋳造用鋳型において、
引き抜き方向に沿ってメニスカス近傍から鋳型出側まで
の間のみに多数の凹部または凹条を設けたことを特徴と
する連続鋳造用鋳型。5. A continuous casting mold having a large number of recesses or grooves at the center of the long side surface along the casting direction,
A continuous casting mold characterized in that a large number of recesses or ridges are provided only between the vicinity of the meniscus and the mold outlet side along the drawing direction. 【請求項６】 鋳込み方向に沿った長辺面の中央部に多
数の凹部または凹条を設けた連続鋳造用鋳型において、
長辺面中央部の鋳型冷却水の面と鋳型溶鋼面の距離が中
央部以外の鋳型冷却水の面と鋳型溶鋼面の距離よりも５
ｍｍ以上大きくなっていることを特徴とする連続鋳造用
鋳型。6. A continuous casting mold having a large number of recesses or ridges at the center of the long side surface along the casting direction,
The distance between the mold cooling water surface at the center of the long side and the molten steel surface of the mold is 5 more than the distance between the surface of the mold cooling water other than the center and the molten steel surface of the mold.
A mold for continuous casting, which is characterized by being larger than mm. 【請求項７】 スラブ形状の鋳片の連続鋳造用の支持ロ
ール、圧下ロールおよび引抜ロールであって、ロールの
スラブ幅中央部に接する部分に低熱伝導率材料からなる
断熱層を設けたことを特徴とする連続鋳造用ロール。7. A support roll, a reduction roll, and a drawing roll for continuous casting of slab-shaped slabs, wherein a heat insulating layer made of a low thermal conductivity material is provided at a portion in contact with the central portion of the slab width of the roll. Characteristic continuous casting roll. 【請求項８】 スラブ形状の鋳片の連続鋳造用の支持ロ
ール、圧下ロールおよび引抜ロールであって、ロールの
スラブ幅中央部に接する部分に多数の凹部を設けたこと
を特徴とする連続鋳造用ロール。8. A support roll, a reduction roll, and a drawing roll for continuous casting of slab-shaped slabs, characterized in that a large number of recesses are provided in a portion in contact with the central portion of the slab width of the roll. For rolls. 【請求項９】 スラブ長辺面の中央部を中央部以外に比
較して緩冷却する連続鋳造方法において、鋳型の鋳込み
方向に沿った長辺面の中央部に多数の凹部または凹条を
設け、スラブ幅中央部の２次冷却水量密度を中央部以外
の水量密度の７５％以下にすることを特徴とする連続鋳
造方法。9. A continuous casting method in which a central portion of a long side surface of a slab is slowly cooled as compared with a central portion other than the central portion, and a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction of the mold. The continuous casting method is characterized in that the secondary cooling water amount density in the central part of the slab width is set to 75% or less of the water amount density other than the central part. 【請求項１０】 スラブ長辺面の中央部を中央部以外に
比較して緩冷却する連続鋳造装置において、鋳型の鋳込
み方向に沿った長辺面の中央部に多数の凹部または凹条
を設けると共に、支持ロール、圧下ロールおよび引抜ロ
ールのスラブ幅中央部に接する部分に多数の凹部を設け
たことを特徴とする連続鋳造装置。10. A continuous casting apparatus for slowly cooling a central portion of a long side surface of a slab as compared with a portion other than the central portion, wherein a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction of the mold. At the same time, the continuous casting apparatus is characterized in that a large number of concave portions are provided in the portions of the supporting roll, the pressing roll, and the drawing roll in contact with the central portion of the slab width. 【請求項１１】 スラブ長辺面の中央部を中央部以外に
比較して緩冷却する連続鋳造方法において、支持ロー
ル、圧下ロールおよび引抜ロールのスラブ幅中央部に接
する部分に多数の凹部を設けると共に、スラブ幅中央部
の２次冷却水量密度を中央部以外の水量密度の７５％以
下にすることを特徴とする連続鋳造方法。11. A continuous casting method in which a central portion of a long side surface of a slab is slowly cooled compared to a portion other than the central portion, and a large number of recesses are provided in portions of the supporting roll, the pressing roll and the pulling roll which contact the central portion of the slab width. At the same time, the secondary casting water amount density in the central portion of the slab width is set to 75% or less of the water amount density other than in the central portion. 【請求項１２】 スラブ長辺面の中央部を中央部以外に
比較して緩冷却する連続鋳造方法において、鋳型の鋳込
み方向に沿った長辺面の中央部に多数の凹部または凹条
を設け、支持ロール、圧下ロールおよび引抜ロールのス
ラブ幅中央部に接する部分に多数の凹部を設けると共
に、スラブ幅中央部の２次冷却水量密度を中央部以外の
水量密度の７５％以下にすることを特徴とする連続鋳造
方法。12. A continuous casting method in which a central portion of a long side surface of a slab is gently cooled as compared with a portion other than the central portion, and a large number of recesses or ridges are provided in the central portion of the long side surface along the casting direction of the mold. , The supporting roll, the pressing roll, and the drawing roll are provided with a large number of concave portions in the portions in contact with the central portion of the slab width, and the secondary cooling water density of the central portion of the slab width is set to 75% or less of the water density other than the central portion Characteristic continuous casting method.