JP2003010901A - Steel sheet manufacturing method and steel sheet manufacturing equipment - Google Patents
Steel sheet manufacturing method and steel sheet manufacturing equipmentInfo
- Publication number
- JP2003010901A JP2003010901A JP2001192725A JP2001192725A JP2003010901A JP 2003010901 A JP2003010901 A JP 2003010901A JP 2001192725 A JP2001192725 A JP 2001192725A JP 2001192725 A JP2001192725 A JP 2001192725A JP 2003010901 A JP2003010901 A JP 2003010901A
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- JP
- Japan
- Prior art keywords
- slab
- thickness
- transformation
- heating furnace
- cooling device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Continuous Casting (AREA)
Abstract
(57)【要約】
【課題】 加熱および圧延の能率を阻害することなく、
種々の厚鋼板において表面疵の発生を防止することがで
きる鋼板の製造方法およびその製造設備を提供するこ
と。
【解決手段】 鋼板の製造方法は、連続鋳造されたスラ
ブを高温状態で加熱炉４に装入した後に圧延するホット
チャージプロセスにより鋼板を製造する方法であって、
加熱炉４の入側に冷却装置２を設置し、前記冷却装置２
によりスラブを強制冷却してスラブ表面をフェライト変
態させてから前記加熱炉４に装入する。
(57) [Summary] [PROBLEMS] Without impairing the efficiency of heating and rolling,
An object of the present invention is to provide a method of manufacturing a steel plate capable of preventing occurrence of surface flaws in various thick steel plates, and a manufacturing facility therefor. SOLUTION: The method for manufacturing a steel sheet is a method for manufacturing a steel sheet by a hot charge process in which a continuously cast slab is charged into a heating furnace 4 at a high temperature and then rolled,
The cooling device 2 is installed on the inlet side of the heating furnace 4, and the cooling device 2
The slab is forcibly cooled to transform the slab surface into ferrite, and then charged into the heating furnace 4.
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、連続鋳造されたス
ラブを高温状態で加熱炉に装入した後に圧延するホット
チャージプロセスにより厚鋼板を製造する鋼板の製造方
法および製造設備に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel plate manufacturing method and manufacturing equipment for manufacturing a thick steel plate by a hot charge process in which a continuously cast slab is charged into a heating furnace at a high temperature and then rolled.
【０００２】[0002]
【従来の技術】近年エネルギー原単位低減を目的とし
て、連続鋳造されたスラブを室温まで冷却せずに高温の
まま加熱炉へ装入して圧延するホットチャージ圧延（Ｈ
ＣＲ）が広く採用されている。熱効率の観点からは、ス
ラブ温度はより高温が望ましいため、オーステナイト温
度域から加熱炉へ装入して圧延するγ−ＨＣＲも行われ
ている。2. Description of the Related Art In recent years, for the purpose of reducing the energy consumption rate, hot-charge rolling (H) in which a continuously cast slab is charged into a heating furnace at a high temperature and rolled without being cooled to room temperature.
CR) is widely used. From the viewpoint of thermal efficiency, it is desirable that the slab temperature is higher. Therefore, γ-HCR in which the slab is charged into the heating furnace from the austenite temperature range and rolled is also performed.
【０００３】このγ−ＨＣＲでは、冷却時にスラブ表層
がオーステナイト（γ）からフェライト（α）に変態し
ないため、γ→α変態、および、再加熱時のα→γ逆変
態に起因する組織の微細化が達成されず、粗大γ組織に
起因した表面疵が発生しやすい。特に、Ｎｂ，Ｔｉ，Ｖ
等のＡｒ３変態点を低下させる合金元素を含有するスラ
ブにおいて顕著である。In this γ-HCR, since the surface layer of the slab does not transform from austenite (γ) to ferrite (α) during cooling, the fine structure of the structure resulting from γ → α transformation and α → γ reverse transformation during reheating. Is not achieved, and surface defects due to the coarse γ structure are likely to occur. Especially, Nb, Ti, V
It is remarkable in slabs containing alloy elements that lower the Ar 3 transformation point such as.
【０００４】このＨＣＲにおける表面疵対策として、鋳
造後のスラブを所定時間放置し、その温度を一定温度ま
で冷却してスラブ表面をフェライト変態させる方法があ
るが、このような技術では一般にスラブの表面温度を測
定してこれが一定温度になるまで冷却しているため、所
望の組織が得られるか否かは不明である。また、鋼成分
により変態温度は異なるため必要な冷却温度は一定では
ない。このためフェライト変態を完全に行わせるために
過度の冷却を行わざるを得ず、スラブ温度が低下しＨＣ
Ｒの省エネルギー効果が低減してしまうという問題があ
った。As a countermeasure against surface flaws in this HCR, there is a method of leaving the slab after casting for a predetermined time and then cooling the temperature to a certain temperature to transform the surface of the slab into ferrite. In such a technique, the surface of the slab is generally used. Since the temperature is measured and the temperature is cooled to a constant temperature, it is unclear whether the desired tissue can be obtained. Further, the required cooling temperature is not constant because the transformation temperature varies depending on the steel composition. For this reason, excessive cooling must be performed in order to completely carry out the ferrite transformation, and the slab temperature decreases and HC
There is a problem that the energy saving effect of R is reduced.
【０００５】この問題を解決するために、いくつかの方
法が提案されている。特開平６−３０６４５８号公報
（従来技術）では、鋳造後のスラブに歪みが残留する
ように加工を施し、その後加工歪みにより再結晶が生じ
る温度以上、かつ、再結晶後の粒成長により粒が粗大化
する温度以下で加熱する方法が提案されている。Several methods have been proposed to solve this problem. In Japanese Unexamined Patent Publication No. 6-306458 (conventional technology), a slab after casting is processed so that strain remains, and thereafter, the temperature is higher than the temperature at which recrystallization is caused by the processing strain, and the grains are grown by grain growth after recrystallization. A method of heating at a temperature not higher than the coarsening temperature has been proposed.
【０００６】特開昭６２−３４６０２号公報（従来技術
）では、圧延条件を制御することにより表面疵の発生
を防止する技術が開示されている。すなわち、全圧下比
１．３以下までの圧延はＡｒ３変態点以上の高温側で圧
延し、全圧下比が１．３を超える部分ではスラブ表面温
度をＡｒ３＋５０℃〜Ａｒ３−１００℃で熱間圧延する
ことにより表面疵の発生を防止している。Japanese Unexamined Patent Publication (Kokai) No. 62-34602 (prior art) discloses a technique for preventing the occurrence of surface defects by controlling the rolling conditions. That is, rolling up to a total reduction ratio of 1.3 or less is performed on the high temperature side above the Ar 3 transformation point, and in the portion where the total reduction ratio exceeds 1.3, the slab surface temperature is Ar 3 + 50 ° C to Ar 3 -100 ° C. By hot rolling in, the occurrence of surface defects is prevented.
【０００７】また、ＨＣＲにおける低温靱性の改善を目
的として、結晶粒径を微細化する工夫もなされている。
特開平７−３３１３２９号公報（従来技術）では、ス
ラブ表面温度３００℃以上、Ａｒ３−１００℃以下で加
熱炉に装入し、圧下比３以上の圧延を行って鋼板表面温
度Ａｒ３−１００℃以上９５０℃以下で圧延を終了する
技術が提案されている。[0007] Further, in order to improve the low temperature toughness of the HCR, some efforts have been made to reduce the crystal grain size.
In JP-A-7-331329 discloses (prior art), the slab surface temperature 300 ° C. or higher, Ar 3 is charged into a heating furnace at -100 ° C. or less, the steel sheet surface temperature Ar 3 performs reduction ratio of 3 or more rolling -100 A technique has been proposed in which rolling is completed at a temperature of not lower than 950 ° C and not higher than 950 ° C.
【０００８】特開昭６３−３１７２０１号公報（従来技
術）では、スラブのγ→α変態量を検出し、検出値が
設定値に達したときにスラブを加熱炉に装入することに
より、組織の微細化を図り低温靱性を向上させる技術が
提案されている。この技術は、従来スラブ表面温度で管
理されていた加熱炉装入条件を、変態量検出装置によっ
て直接測定されるスラブ内部のフェライト変態率で制御
するものである。In Japanese Patent Laid-Open No. 63-317201 (conventional art), the amount of γ → α transformation of a slab is detected, and when the detected value reaches a set value, the slab is charged into a heating furnace to obtain a structure. A technique has been proposed for improving the low temperature toughness by miniaturizing. This technique controls the heating furnace charging condition, which was conventionally controlled by the slab surface temperature, by the ferrite transformation rate inside the slab, which is directly measured by a transformation amount detection device.
【０００９】[0009]
【発明が解決しようとする課題】しかしながら、上記従
来技術の方法では、連続鋳造後のスラブに歪みが残留
するように加工を施すことが可能な設備が必要であり現
実的ではない。また、加熱条件の制約があるため操業上
能率低下を生じてしまうという問題がある。However, the above-mentioned method of the prior art is not realistic because it requires equipment capable of performing processing so that strain remains in the slab after continuous casting. In addition, there is a problem that the efficiency of operation is lowered due to the restriction of heating conditions.
【００１０】また、上記従来技術の方法は、圧延条件
を規制する技術であり、鋼板サイズや要求される材質特
性の異なる厚鋼板へ広く適用することはできないという
問題がある。Further, the above-mentioned method of the prior art is a technology for controlling the rolling conditions and has a problem that it cannot be widely applied to thick steel plates having different steel plate sizes and required material characteristics.
【００１１】さらに、上記従来技術の方法は、加熱炉
装入温度と圧延条件を規定するため、上記従来技術の
方法と同様に、種々の厚鋼板へ適用することは不可能で
あるとともに、加熱、圧延能率を阻害するという問題が
ある。Further, since the above-mentioned conventional method defines the heating furnace charging temperature and rolling conditions, it cannot be applied to various thick steel plates like the above-mentioned conventional method, and the heating is not possible. However, there is a problem that the rolling efficiency is hindered.
【００１２】一方、スラブのγ→α変態量を変態量検出
装置により検出する従来技術は、所望の組織を得るの
に有効な手段である。しかし、検出値が所定値になるま
でその位置でスラブを待機させる必要があり、加熱炉装
入の作業効率が大幅に低下してしまう。また、靱性向上
のためにはスラブ厚の中心部まで所定量変態しているこ
とが必要であるが、このように変態させる場合、スラブ
全体の温度低下が避けられず省エネルギー効果が低減す
るという問題がある。On the other hand, the conventional technique of detecting the γ → α transformation amount of the slab by the transformation amount detecting device is an effective means for obtaining a desired structure. However, it is necessary to wait the slab at that position until the detected value reaches a predetermined value, which significantly reduces the work efficiency of charging the heating furnace. Further, in order to improve the toughness, it is necessary to transform a certain amount up to the center of the slab thickness, but when transforming in this way, the temperature decrease of the entire slab cannot be avoided and the energy saving effect decreases. There is.
【００１３】本発明は上記事情に鑑みてなされたもので
あって、ホットチャージプロセスにより厚鋼板を製造す
るに際し、加熱および圧延の能率を阻害することなくエ
ネルギーロスを最小限にしつつ、表面疵の発生を防止す
ることができる鋼板の製造方法およびその製造設備を提
供することを目的とする。The present invention has been made in view of the above circumstances, and when manufacturing a thick steel sheet by a hot charge process, the energy loss is minimized without impairing the efficiency of heating and rolling, and the surface flaw is prevented. An object of the present invention is to provide a method for manufacturing a steel sheet and a manufacturing facility for the steel sheet, which can prevent the generation of the steel sheet.
【００１４】[0014]
【課題を解決するための手段】上記課題を解決するた
め、本発明の第１の観点では、連続鋳造されたスラブを
高温状態で加熱炉に装入した後に圧延するホットチャー
ジプロセスにより厚鋼板を製造する方法であって、加熱
炉の入側に冷却装置を設置し、前記冷却装置によりスラ
ブを強制冷却してスラブ表面をフェライト変態させてか
ら前記加熱炉に装入することを特徴とする鋼板の製造方
法を提供する。In order to solve the above problems, according to a first aspect of the present invention, a thick steel sheet is formed by a hot charge process in which a continuously cast slab is charged into a heating furnace at a high temperature and then rolled. A method of manufacturing, wherein a cooling device is installed on the inlet side of the heating furnace, the slab is forcibly cooled by the cooling device to transform the surface of the slab into ferrite, and then the steel plate is charged into the heating furnace. A method for manufacturing the same is provided.
【００１５】また、本発明の第２の観点では、連続鋳造
されたスラブが装入される加熱炉と、前記加熱炉から搬
出されたスラブを圧延する圧延機とを具備し、連続鋳造
されたスラブを高温状態のまま圧延するホットチャージ
プロセスを行う厚鋼板の製造設備であって、前記加熱炉
の入側に設けられ、スラブを強制冷却してスラブ表面を
フェライト変態させる冷却装置をさらに具備することを
特徴とする鋼板の製造設備を提供する。Further, according to a second aspect of the present invention, a continuous heating is provided with a heating furnace into which the continuously cast slab is charged and a rolling mill for rolling the slab carried out from the heating furnace. A thick steel plate manufacturing facility for performing a hot charge process of rolling a slab in a high temperature state, further comprising a cooling device provided on the inlet side of the heating furnace to forcibly cool the slab and transform the surface of the slab into ferrite. A steel plate manufacturing facility characterized by the above is provided.
【００１６】上記本発明の第１および第２の観点によれ
ば、連続鋳造後のスラブ表面を強制冷却することによっ
て、スラブ表面を積極的にフェライト変態させ、これに
よりスラブ表面の組織微細化を促進するので、加熱およ
び圧延の能率を阻害することなくエネルギーロスを最小
限にしつつ、種々の厚鋼板において粗大γ組織に起因し
た表面疵の発生を防止することができる。According to the first and second aspects of the present invention, by forcibly cooling the surface of the slab after continuous casting, the surface of the slab is positively transformed into ferrite, whereby the structure of the surface of the slab is refined. Since the acceleration is promoted, it is possible to prevent the generation of surface flaws due to the coarse γ structure in various thick steel plates while minimizing the energy loss without impairing the efficiency of heating and rolling.
【００１７】本発明の第３の観点では、連続鋳造された
スラブを高温状態で加熱炉に装入した後に圧延するホッ
トチャージプロセスにより厚鋼板を製造する方法であっ
て、加熱炉の入側に冷却装置およびスラブ表面の変態厚
さを測定可能な変態率計を設置し、前記冷却装置により
スラブを強制冷却してスラブ表面をフェライト変態さ
せ、前記変態率計により強制冷却後のスラブ表面のフェ
ライト変態厚さを測定し、フェライト変態厚さが所定値
となってから前記加熱炉に装入することを特徴とする鋼
板の製造方法を提供する。According to a third aspect of the present invention, there is provided a method for producing a thick steel sheet by a hot charging process in which a continuously cast slab is charged into a heating furnace at a high temperature and then rolled, and the steel plate is provided on the inlet side of the heating furnace. A cooling device and a transformation rate meter that can measure the transformation thickness of the slab surface are installed, the slab is forcedly cooled by the cooling device to transform the slab surface into ferrite, and the transformation rate meter causes the ferrite on the slab surface after forced cooling. Provided is a method for producing a steel sheet, which comprises: measuring a transformation thickness, and charging the ferrite transformation thickness after the ferrite transformation thickness reaches a predetermined value.
【００１８】また、本発明の第４の観点では、連続鋳造
されたスラブが装入される加熱炉と、前記加熱炉から搬
出されたスラブを圧延する圧延機とを具備し、連続鋳造
されたスラブを高温状態のまま圧延するホットチャージ
プロセスを行う厚鋼板の製造設備であって、前記加熱炉
の入側に設けられ、スラブを強制冷却してスラブ表面を
フェライト変態させる冷却装置と、前記冷却装置と前記
加熱炉との間に設けられ、スラブ表面のフェライト変態
厚さを測定する変態率計とをさらに具備し、前記変態率
計により測定されたスラブ表面のフェライト変態厚さが
所定値となった際にスラブを前記加熱炉に装入すること
を特徴とする鋼板の製造設備を提供する。Further, according to a fourth aspect of the present invention, the continuous casting is provided with a heating furnace into which the continuously cast slab is charged and a rolling mill for rolling the slab carried out from the heating furnace. A facility for manufacturing a thick steel plate for performing a hot charge process of rolling a slab in a high temperature state, the cooling device being provided on the inlet side of the heating furnace, forcibly cooling the slab to transform the slab surface into ferrite, and the cooling device. Provided between the apparatus and the heating furnace, further comprising a transformation rate meter for measuring the ferrite transformation thickness of the slab surface, the ferrite transformation thickness of the slab surface measured by the transformation rate meter with a predetermined value Provided is a steel plate manufacturing facility characterized by charging a slab into the heating furnace when the temperature becomes low.
【００１９】上記本発明の第３および第４の観点によれ
ば、スラブ表面を強制冷却してフェライト変態させた後
にフェライト変態厚さを測定し、フェライト変態厚さが
十分な場合にスラブを加熱炉に装入するので、加熱およ
び圧延の能率を阻害することなくエネルギーロスを最小
限にしつつ、種々の厚鋼板において粗大γ組織に起因し
た表面疵の発生を確実に防止することができる。According to the third and fourth aspects of the present invention, the ferrite transformation thickness is measured after the surface of the slab is forcibly cooled to undergo the ferrite transformation, and the slab is heated when the ferrite transformation thickness is sufficient. Since it is charged into the furnace, it is possible to reliably prevent the generation of surface flaws due to the coarse γ structure in various thick steel plates while minimizing energy loss without impairing the efficiency of heating and rolling.
【００２０】上記本発明の第３および第４の観点におい
て、前記所定値は、スラブ厚と製品厚との比で規定され
る圧下比、すなわち圧延機の圧下比に対応した値とする
ことが好ましく、例えば、前記圧下比が５以上のときに
はスラブ厚の５％とし、前記圧下比が５未満のときはス
ラブ厚の１０％とする。In the third and fourth aspects of the present invention, the predetermined value may be a reduction ratio defined by the ratio of the slab thickness to the product thickness, that is, a value corresponding to the reduction ratio of the rolling mill. Preferably, for example, when the reduction ratio is 5 or more, the slab thickness is 5%, and when the reduction ratio is less than 5, the slab thickness is 10%.
【００２１】また、フェライト変態厚さは、スラブに直
流磁場を印加して回転磁化領域の磁化状態に磁化し、こ
の状態のスラブの磁化部分について交流磁場を用いて電
磁気的特性の測定を行うことにより求めることが好適で
ある。For the ferrite transformation thickness, a DC magnetic field is applied to the slab to magnetize it into a magnetization state in the rotating magnetization region, and the electromagnetic characteristics of the magnetized portion of the slab in this state are measured using an AC magnetic field. It is preferable to obtain by
【００２２】さらに、前記測定されたスラブ表面のフェ
ライト変態厚さに応じて、それ以降のスラブの冷却条件
を制御することが好ましい。Further, it is preferable to control the cooling conditions of the subsequent slab according to the measured ferrite transformation thickness of the slab surface.
【００２３】上記本発明の第４の観点においては、前記
冷却装置の入側に設けられ、前記冷却装置の入側におけ
るスラブ表面のフェライト変態厚さを測定する他の変態
率計をさらに具備し、前記他の変態率計の測定したフェ
ライト変態厚さが所定値未満の場合に前記冷却装置でス
ラブの強制冷却を行い、前記他の変態率計の測定したフ
ェライト変態厚さが所定値以上の場合には前記冷却装置
でスラブの強制冷却を行わないようにしてもよい。連続
鋳造されたスラブは、冷却装置に装入されるまでの間に
その表面が十分にフェライト変態している可能性もある
ので、このように強制冷却前にフェライト変態厚さが十
分な場合にはスラブの強制冷却を行わないようにするこ
とで、スラブのエネルギーロスを最低限にすることがで
きる。In the fourth aspect of the present invention, it further comprises another transformation rate meter provided on the inlet side of the cooling device and for measuring the ferrite transformation thickness of the slab surface on the inlet side of the cooling device. , If the ferrite transformation thickness measured by the other transformation rate meter is less than a predetermined value, forced cooling of the slab is performed by the cooling device, and the ferrite transformation thickness measured by the other transformation rate meter is a predetermined value or more. In this case, the cooling device may not perform forced cooling of the slab. Since the surface of the continuously cast slab may have undergone sufficient ferrite transformation by the time it is loaded into the cooling device, if the ferrite transformation thickness is sufficient before forced cooling in this way, The energy loss of the slab can be minimized by not forcibly cooling the slab.
【００２４】上記本発明の第３および第４の観点におい
ては、フェライト変態厚さの測定は、スラブの幅方向中
央部のみで行うようにしてもよい。また、上記本発明の
いずれの観点においても、スラブの幅方向中央部のみを
強制冷却するようにしてもよい。In the third and fourth aspects of the present invention, the ferrite transformation thickness may be measured only at the widthwise central portion of the slab. Further, in any of the above aspects of the present invention, only the widthwise central portion of the slab may be forcibly cooled.
【００２５】[0025]
【発明の実施の形態】以下、本発明の実施の形態につい
て説明する。図１は、本発明の第１の実施形態に係る鋼
板の製造設備の配置を示す模式図である。図１に示すよ
うに、この鋼板の製造設備は、図示しない連続鋳造機で
製造されたスラブが搬送されるスラブ搬送ライン１と、
このスラブ搬送ライン１上に設けられ、スラブを強制冷
却する冷却装置２と、この冷却装置２の出側に設けら
れ、冷却されたスラブ表面の温度を測定する温度計３
と、温度計３で温度を測定した後のスラブがスラブ搬送
ライン１から装入される加熱炉４と、この加熱炉４の出
側に設けられ、スラブを圧延して鋼板とする圧延ライン
５とを有している。このうちスラブ搬送ライン１と、加
熱炉４と、圧延ライン５とは、通常の鋼板の製造設備と
同様のものを用いることができ、既存の設備を用いても
構わない。また、冷却装置２としては、スラブの上下面
を冷却可能なものであれば特に限定されるものではな
く、スプレーノズル等を備えた水冷式の通常のものを用
いることができる。温度計３もスラブ表面の温度測定に
用いる通常のものを用いればよい。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a schematic diagram showing an arrangement of steel plate manufacturing equipment according to a first embodiment of the present invention. As shown in FIG. 1, the steel plate manufacturing facility includes a slab transfer line 1 for transferring slabs manufactured by a continuous casting machine (not shown),
A cooling device 2 provided on the slab transfer line 1 for forcibly cooling the slab, and a thermometer 3 provided on the outlet side of the cooling device 2 for measuring the temperature of the cooled slab surface.
And a heating furnace 4 into which the slab whose temperature has been measured by the thermometer 3 is charged from the slab transfer line 1, and a rolling line 5 provided on the outlet side of the heating furnace 4 for rolling the slab into a steel plate. And have. Of these, the slab transfer line 1, the heating furnace 4, and the rolling line 5 can use the same equipment as a normal steel plate manufacturing facility, and may use existing facilities. The cooling device 2 is not particularly limited as long as it can cool the upper and lower surfaces of the slab, and a normal water-cooled device equipped with a spray nozzle or the like can be used. As the thermometer 3, a normal one used for measuring the temperature of the slab surface may be used.
【００２６】上記の製造設備を用いて鋼板を製造する際
には、まず、連続鋳造されたスラブをスラブ搬送ライン
１上で搬送して冷却装置２に搬入し、例えば冷却装置２
のスプレーノズルを用いて所定水量で所定時間冷却する
ことにより、スラブを強制冷却してスラブ表面をフェラ
イト変態させる。次に、温度計３でスラブ表面の温度を
確認し、スラブ搬送ライン１から加熱炉４に装入し、ス
ラブを加熱した後、スラブを圧延ライン５に搬入して圧
延することにより鋼板を製造する。When manufacturing a steel sheet using the above-mentioned manufacturing equipment, first, the continuously cast slab is conveyed on the slab conveying line 1 and carried into the cooling device 2, for example, the cooling device 2.
The spray nozzle is used to cool the slab with a predetermined amount of water for a predetermined time to forcibly cool the slab and transform the surface of the slab into ferrite. Next, the temperature of the slab surface is confirmed with the thermometer 3, the heating furnace 4 is charged from the slab transfer line 1, the slab is heated, and then the slab is carried into the rolling line 5 and rolled to manufacture a steel sheet. To do.
【００２７】このようなプロセスでは、冷却装置２でス
ラブを強制冷却してスラブ表面をフェライト変態させる
ことにより、スラブ表面の組織を微細化することができ
るので、スラブ表面の粗大γ組織に起因した表面疵の発
生を防止することができる。また、強制冷却することに
よりスラブ表面は温度低下するが、一般にスラブ厚は２
００ｍｍ以上と厚いため、板厚中心部からの復熱により
スラブ全体の温度は高温に保持されたままであり、冷却
によるエネルギーロスは僅かである。さらに、加熱炉４
に装入後の加熱条件、圧延条件はいすれも鋼種、要求寸
法、要求材質に応じて適宜決定すればよく、制約は不要
であり、これらの能率を阻害することなくどのような種
類のスラブにも適用することが可能である。In such a process, the structure of the slab surface can be miniaturized by forcibly cooling the slab by the cooling device 2 and subjecting the surface of the slab to ferrite transformation, so that the coarse γ structure of the slab surface results. It is possible to prevent the occurrence of surface defects. Also, the temperature of the slab surface decreases due to forced cooling, but generally the slab thickness is 2
Since the thickness is as thick as 00 mm or more, the temperature of the entire slab remains high due to the heat recovery from the central portion of the plate thickness, and the energy loss due to cooling is small. Furthermore, heating furnace 4
Any heating conditions and rolling conditions after charging may be appropriately determined according to the steel type, required dimension, required material, and no restrictions are required, and any type of slab can be used without hindering these efficiencies. Can also be applied.
【００２８】また、従来のホットチャージプロセスにお
いて、表面疵が発生しやすいのはスラブの幅方向中央部
である１／４ｗ〜３／４ｗ（ｗはスラブの幅を示す。）
付近であることが経験的に知られている。したがって、
冷却装置２でスラブの幅方向中央部のみを冷却して、表
面疵が発生しやすい部分のみをフェライト変態させても
よい。これによりスラブの温度低下を極力少なくして表
面疵の発生を有効に防止することが可能となる。Further, in the conventional hot charging process, it is 1 / 4w to 3 / 4w (w indicates the width of the slab) that the surface flaw is likely to occur at the center portion in the width direction of the slab.
It is empirically known to be in the vicinity. Therefore,
It is also possible to cool only the widthwise central portion of the slab with the cooling device 2 and subject only the portion where surface defects are likely to occur to ferrite transformation. This makes it possible to reduce the temperature drop of the slab as much as possible and effectively prevent the occurrence of surface defects.
【００２９】図２は、本発明の第２の実施形態に係る鋼
板の製造設備の配置を示す模式図である。図２に示すよ
うに、この鋼板の製造設備は、上記第１の実施形態に係
る鋼板の製造設備と同様の構成に加えて、冷却装置２と
加熱炉４との間に、スラブ板厚方向のフェライト変態厚
さを測定する変態率計６を有しており、この変態率計６
により冷却装置２で強制冷却されたスラブのフェライト
変態厚さが測定可能になっている。また、変態率計６か
ら出力された測定結果が入力され、その値に応じて冷却
装置２の冷却条件を制御可能な制御手段７が設けられて
いる。なお、この制御手段７は、スラブの鋼種（Ａｒ３
変態点）、圧延ライン５の圧下比等も入力可能に構成さ
れており、入力されたこれらのデータによっても冷却装
置２の冷却条件を制御可能である。FIG. 2 is a schematic view showing the arrangement of steel plate manufacturing equipment according to the second embodiment of the present invention. As shown in FIG. 2, in addition to the same structure as the steel plate manufacturing equipment according to the first embodiment, this steel plate manufacturing equipment has a slab plate thickness direction between the cooling device 2 and the heating furnace 4. Has a transformation rate meter 6 for measuring the ferrite transformation thickness of
By this, the ferrite transformation thickness of the slab forcedly cooled by the cooling device 2 can be measured. Further, the control unit 7 is provided which receives the measurement result output from the transformation rate meter 6 and can control the cooling condition of the cooling device 2 according to the value. The control means 7 controls the steel type of the slab (Ar 3
The transformation point), the reduction ratio of the rolling line 5 and the like are also inputtable, and the cooling conditions of the cooling device 2 can be controlled also by these input data.
【００３０】この変態率計６としては、本出願人が特願
２０００−０１１１２２において提案したもの、具体的
には、スラブに直流磁場を印加して回転磁化領域の磁化
状態に磁化する直流磁化手段と、スラブの磁化部分につ
いて交流磁場を用いて電磁気的特性の測定を行う検出手
段と、前記検出手段の測定した電磁気的特性値からスラ
ブ表面のフェライト変態厚さを求める変態測定手段とを
有するものを用いることができる。このような変態率計
６によれば、鋼種、加工履歴、熱履歴等の影響を受けず
にスラブのフェライト変態厚さを測定することができ、
また、スラブ板厚方向の広い範囲でフェライト変態厚さ
を測定することが可能である。The transformation rate meter 6 is the one proposed by the present applicant in Japanese Patent Application No. 2000-011122, specifically, a DC magnetizing means for applying a DC magnetic field to the slab to magnetize it into a magnetized state in a rotating magnetized region. And a detection means for measuring an electromagnetic characteristic of the magnetized portion of the slab by using an alternating magnetic field, and a transformation measuring means for obtaining a ferrite transformation thickness of the slab surface from the electromagnetic characteristic value measured by the detection means. Can be used. According to the transformation rate meter 6 as described above, the ferrite transformation thickness of the slab can be measured without being affected by steel type, working history, thermal history, and the like,
Further, it is possible to measure the ferrite transformation thickness in a wide range in the slab plate thickness direction.
【００３１】上記製造設備を用いて鋼板を製造する際に
は、まず、上記第１の実施形態と同様に、スラブをスラ
ブ搬送ライン１上で搬送して冷却装置２に搬入し、スラ
ブを強制冷却する。次いで、スラブを変態率計６に搬入
してスラブ板厚方向のフェライト変態厚さを測定し、測
定されたフェライト変態厚さが所定値以上の場合にはス
ラブを加熱炉４に装入してスラブを加熱した後、スラブ
を圧延ライン５に搬入して圧延することにより鋼板を製
造する。また、測定されたフェライト変態厚さが所定値
未満の場合にはスラブを再度冷却装置２に搬入して強制
冷却し、変態率計６で再度フェライト変態厚さを測定し
てフェライト変態厚さが所定値以上であることを確認し
た後、前記同様に加熱炉４に装入して加熱し、圧延ライ
ン５に搬入して圧延する。この場合に、搬送が錯綜する
ときにはスラブを再度冷却装置２に搬入する代わりに、
そのまま空冷により冷却するようにしてもよい。When manufacturing a steel sheet using the above-mentioned manufacturing equipment, first, as in the first embodiment, the slab is conveyed on the slab conveyance line 1 and carried into the cooling device 2 to force the slab. Cooling. Then, the slab is carried into the transformation rate meter 6 and the ferrite transformation thickness in the slab plate thickness direction is measured. When the measured ferrite transformation thickness is equal to or greater than a predetermined value, the slab is loaded into the heating furnace 4. After heating the slab, the slab is carried into the rolling line 5 and rolled to manufacture a steel sheet. When the measured ferrite transformation thickness is less than the predetermined value, the slab is again carried into the cooling device 2 and forcedly cooled, and the transformation rate meter 6 measures the ferrite transformation thickness again to determine the ferrite transformation thickness. After confirming that it is not less than a predetermined value, it is charged into the heating furnace 4 and heated in the same manner as described above, and then carried into the rolling line 5 and rolled. In this case, when the transportation is complicated, instead of carrying the slab into the cooling device 2 again,
You may make it cool by air cooling as it is.
【００３２】このようなプロセスでは、スラブを強制冷
却してスラブ表面をフェライト変態させた後に変態率計
６でフェライト変態厚さを測定し、測定されたフェライ
ト変態厚さが所定値以上場合にスラブを加熱炉４に装入
するので、スラブ表面の所定厚さを確実にフェライト変
態させることができ、スラブ表面の粗大γ組織に起因し
た表面疵の発生をより確実に防止することができる。ま
た、強制冷却後のフェライト変態厚さを測定しながらス
ラブを強制冷却することができるので、スラブ表面の温
度低下を抑制しつつ、十分なフェライト変態厚さとなる
ようにスラブを強制冷却することができ、これにより最
小限のエネルギーロスで表面疵の発生を適切に防止する
ことができる。さらに、本実施形態においても加熱炉４
に装入後の加熱条件、圧延条件はいすれも鋼種、要求寸
法、要求材質に応じて適宜決定すればよく、制約は不要
であり、加熱や圧延の能率を阻害することなくどのよう
な種類のスラブにも適用することが可能である。In such a process, after the slab is forcibly cooled to transform the surface of the slab into ferrite, the ferrite transformation thickness is measured by the transformation rate meter 6, and the slab is measured when the measured ferrite transformation thickness is a predetermined value or more. Since the slab is charged into the heating furnace 4, a predetermined thickness of the slab surface can be securely transformed into ferrite, and the occurrence of surface flaws due to the coarse γ structure of the slab surface can be more reliably prevented. Further, since it is possible to forcibly cool the slab while measuring the ferrite transformation thickness after forced cooling, it is possible to forcibly cool the slab so as to obtain a sufficient ferrite transformation thickness while suppressing the temperature decrease of the slab surface. This makes it possible to properly prevent the occurrence of surface defects with a minimum energy loss. Furthermore, the heating furnace 4 is also used in this embodiment.
The heating conditions and the rolling conditions after charging may be appropriately determined according to the steel type, the required size, the required material, no restrictions are required, and any kind of heating or rolling can be performed without hindering the efficiency. It can also be applied to slabs.
【００３３】表１に、本実施形態の製造設備を用い、ス
プレーノズルを備えた冷却装置２にスラブを搬入し、
０．５ｍ３／ｍｉｎ・ｍ２の水量密度にて種々の冷却時
間でスラブを強制冷却した後、変態率計６でフェライト
変態厚さを測定し、温度計３で加熱炉４装入時のスラブ
表面温度を測定した結果を示す。また、表１にはスラブ
を強制冷却せずに、空冷した場合のフェライト変態厚さ
およびスラブ表面温度を併せて示す。In Table 1, the slab was carried into the cooling device 2 equipped with the spray nozzle using the manufacturing equipment of this embodiment,
After forcibly cooling the slab at various cooling times at a water density of 0.5 m 3 / min · m 2 , the transformation rate meter 6 measures the ferrite transformation thickness, and the thermometer 3 measures when the heating furnace 4 is charged. The result of having measured the slab surface temperature is shown. Further, Table 1 also shows the ferrite transformation thickness and the slab surface temperature when the slab is air-cooled without being forcibly cooled.
【００３４】[0034]
【表１】 [Table 1]
【００３５】表１より、スラブを強制冷却することでス
ラブ表面をフェライト変態させることができ、冷却時間
とともにスラブ板厚方向のフェライト変態厚さが大きく
なることがわかる。さらに、同じフェライト変態厚さで
も強制冷却したスラブと空冷したスラブとでは加熱炉装
入時のスラブ表面温度が異なり、強制冷却したスラブで
は内部からの復熱により空冷したスラブよりも約１５０
℃スラブ表面温度が高くなっており、エネルギー原単位
低減の観点からも本発明が優れた効果を有していること
がわかる。また、従来のスラブ表面温度測定では、同じ
温度でも鋼種によりＡｒ３変態点が相違するためフェラ
イト変態厚さは異なっており、フェライト変態厚さを正
確に把握することは困難であったが、本実施形態におい
ては、上記のように変態率計６を用いることにより、フ
ェライト変態厚さを直接的かつ正確に測定することが可
能である。It can be seen from Table 1 that the slab surface can be transformed into ferrite by forcibly cooling the slab, and the ferrite transformation thickness in the slab plate thickness direction increases with cooling time. Furthermore, even with the same ferrite transformation thickness, the slab surface temperature at the time of charging in the heating furnace is different between the slab that has been forcibly cooled and the slab that has been air-cooled.
It can be seen that the present invention has an excellent effect from the viewpoint of reducing the energy consumption rate because the slab surface temperature is higher. Further, in the conventional slab surface temperature measurement, the ferrite transformation thickness differs because the Ar 3 transformation point varies depending on the steel type even at the same temperature, and it was difficult to accurately grasp the ferrite transformation thickness. In the embodiment, by using the transformation rate meter 6 as described above, it is possible to directly and accurately measure the ferrite transformation thickness.
【００３６】また、従来のようにスラブを空冷してスラ
ブ表面をフェライト変態させる場合、フェライト変態が
開始するまで長時間の空冷が必要であり、スラブ製造か
ら加熱炉装入までのリードタイムが長くなるため、工程
上の制約が生じる。これに対して、本発明においては強
制冷却することにより短時間でスラブ表面をフェライト
変態させることが可能であり、リードタイムの短縮によ
る製造能率の向上も達成することができる。When the slab is air-cooled to transform the surface of the slab into ferrite as in the conventional case, it is necessary to cool the air for a long time before the ferrite transformation starts, and the lead time from the slab production to the charging of the heating furnace is long. Therefore, there are restrictions on the process. On the other hand, in the present invention, the slab surface can be transformed into ferrite in a short time by forced cooling, and the improvement of manufacturing efficiency can be achieved by shortening the lead time.
【００３７】図３は、本実施形態の製造設備を用い、冷
却装置２でスラブ表面を種々の条件で冷却し、スラブ表
面の板厚方向のフェライト変態厚さを変態率計６で測定
した後、加熱炉４に装入してスラブを加熱し、熱間圧延
ライン５で熱間圧延した鋼板の表面疵発生状況を調査し
た結果を示すグラフである。この調査では、Ｎｂ、Ｖが
添加された２５０ｍｍ厚のスラブを用い、加熱炉４の加
熱温度は一律１１５０℃とし、圧延ライン５の圧下比を
２〜１０の範囲で変化させた。図３には横軸に圧延ライ
ン５の圧下比をとり縦軸に変態率計６で測定されたフェ
ライト変態厚さをとって、疵無しの場合を○、疵有りの
場合を×で示す。FIG. 3 shows that after the slab surface is cooled under various conditions by the cooling device 2 using the manufacturing equipment of this embodiment and the ferrite transformation thickness in the plate thickness direction of the slab surface is measured by the transformation rate meter 6. 2 is a graph showing the results of investigation of the surface flaw generation status of a steel sheet which was charged into a heating furnace 4 to heat a slab and hot rolled in a hot rolling line 5. In this investigation, a 250 mm-thick slab to which Nb and V were added was used, the heating temperature of the heating furnace 4 was uniformly set to 1150 ° C., and the rolling ratio of the rolling line 5 was changed in the range of 2 to 10. In FIG. 3, the horizontal axis represents the rolling reduction ratio of the rolling line 5, and the vertical axis represents the ferrite transformation thickness measured by the transformation rate meter 6. The case without defects is indicated by ◯, and the case with defects is indicated by x.
【００３８】図３に示すように、圧下比が５以上の場合
にはフェライト変態厚さが１２．５ｍｍ以上、すなわち
スラブ厚の５％以上であれば表面疵が発生しない。ま
た、圧下比が５％未満の場合にはフェライト変態厚さが
２５ｍｍ以上、すなわちスラブ厚の１０％以上であれば
表面疵が発生しない。このように、圧下比により表面疵
の発生状況は異なっており、圧下比に応じてスラブ表面
のフェライト変態厚さを制御することが好ましい。具体
的には、圧延ライン５の圧下比に応じて、所定のフェラ
イト変態厚さが得られるように、冷却装置２の冷却条
件、例えばスプレーノズルを用いる場合にはその水量密
度あるいは水冷時間を制御手段７により制御してスラブ
を冷却する。As shown in FIG. 3, when the reduction ratio is 5 or more, when the ferrite transformation thickness is 12.5 mm or more, that is, when the slab thickness is 5% or more, surface defects do not occur. When the reduction ratio is less than 5%, the surface transformation does not occur if the ferrite transformation thickness is 25 mm or more, that is, 10% or more of the slab thickness. As described above, the state of occurrence of surface defects varies depending on the reduction ratio, and it is preferable to control the ferrite transformation thickness of the slab surface according to the reduction ratio. Specifically, the cooling condition of the cooling device 2, for example, when using a spray nozzle, the water amount density or water cooling time is controlled so that a predetermined ferrite transformation thickness is obtained according to the rolling reduction of the rolling line 5. It is controlled by means 7 to cool the slab.
【００３９】本実施形態においては、変態率計６で測定
されたスラブのフェライト変態厚さに応じて、それ以降
のスラブの冷却条件（冷却時間、冷却水量、冷却部位
等）を制御手段７により制御するようにしてもよい。こ
のようにフェライト変態厚さの実測値に応じてスラブの
冷却条件を制御することによって、より適切にフェライ
ト変態厚さを調節することができる。In the present embodiment, according to the ferrite transformation thickness of the slab measured by the transformation rate meter 6, the control means 7 controls the cooling conditions (cooling time, cooling water amount, cooling site, etc.) of the slab thereafter. It may be controlled. In this way, by controlling the cooling conditions of the slab according to the actually measured value of the ferrite transformation thickness, the ferrite transformation thickness can be adjusted more appropriately.
【００４０】また、上述したように、表面疵が出やすい
のは経験的に１／４ｗ〜３／４ｗ付近の幅方向中央部で
あるから、変態率計６による測定をその部分のみで行う
ようにしてもよいし、上記実施形態と同様に冷却装置２
でスラブの幅方向中央部のみを冷却するようにしてもよ
い。Further, as described above, it is empirically that the surface defects are apt to occur in the central portion in the width direction in the vicinity of 1 / 4w to 3 / 4w. Therefore, the measurement by the transformation rate meter 6 should be performed only in that portion. Alternatively, the cooling device 2 may be used as in the above embodiment.
It is also possible to cool only the central portion in the width direction of the slab.
【００４１】図４は、表面をフェライト変態させたスラ
ブのフェライト変態厚さを幅方向の複数箇所で測定し、
横軸にスラブ幅方向位置をとり、縦軸にフェライト変態
厚さをとってフェライト変態厚さの分布を示したグラフ
である。図４に示すように、スラブの幅方向端部ではフ
ェライト変態厚さが大きく、上述の表面疵が出やすいス
ラブ幅方向中央部の１／４ｗ〜３／４ｗ付近では実質的
にフェライト変態が生じていないので、変態率計６をス
ラブ幅方向に複数個設けるか、あるいは変態率計６をス
ラブ幅方向に走査させて、スラブ幅方向のフェライト変
態厚さの分布状況を把握するようにし、測定されたフェ
ライト変態厚さが十分でない必要最小限の部分のみ（例
えば、幅方向中央部のみ）で強制冷却を行うようにして
もよい。これにより、スラブのエネルギーロスを最低化
することができる。FIG. 4 shows that the ferrite transformation thickness of a slab whose surface is ferrite transformed is measured at a plurality of positions in the width direction,
6 is a graph showing the distribution of ferrite transformation thickness, where the horizontal axis represents the slab width direction position and the vertical axis represents the ferrite transformation thickness. As shown in FIG. 4, the ferrite transformation thickness is large at the widthwise end portion of the slab, and the ferrite transformation occurs substantially in the vicinity of 1 / 4w to 3 / 4w in the center portion of the slab widthwise direction where the above-mentioned surface defects are likely to occur. Therefore, a plurality of transformation rate meters 6 are provided in the slab width direction, or the transformation rate meter 6 is scanned in the slab width direction to grasp the distribution state of the ferrite transformation thickness in the slab width direction. Forced cooling may be performed only in the minimum necessary portion (for example, only in the widthwise central portion) where the ferrite transformation thickness is not sufficient. Thereby, the energy loss of the slab can be minimized.
【００４２】図５は、本発明の第３の実施形態に係る鋼
板の製造設備の配置を示す模式図である。図５に示すよ
うに、この鋼板の製造設備は、上記第２の実施形態に係
る鋼板の製造設備と同様の構成に加えて、冷却装置２の
入側にも変態率計６′が設けられており、この変態率計
６′から出力された測定結果もまた制御手段７に入力さ
れるようになっている。FIG. 5 is a schematic view showing the arrangement of steel plate manufacturing equipment according to the third embodiment of the present invention. As shown in FIG. 5, this steel plate manufacturing facility is provided with a transformation rate meter 6 ′ on the inlet side of the cooling device 2 in addition to the same structure as the steel plate manufacturing facility according to the second embodiment. The measurement result output from the transformation rate meter 6'is also input to the control means 7.
【００４３】この製造設備を用いて鋼板を製造する際に
は、まず、スラブをスラブ搬送ライン１上で搬送し、変
態率計６′に搬入してフェライト変態厚さを測定した
後、スラブを冷却装置２に搬入する。このとき、変態率
計６′において測定されたフェライト変態厚さが所定値
以上の場合にはスラブの強制冷却を行わず、フェライト
変態厚さが所定値未満の場合にはスラブを強制冷却する
ように、制御手段７により冷却装置２を制御する。以
下、上記第２の実施形態と同様に、変態率計６において
スラブ表面のフェライト変態厚さを測定し、スラブを加
熱炉４に装入し、圧延ライン５で圧延して鋼板を得る。When manufacturing a steel sheet using this manufacturing equipment, first, the slab is carried on the slab carrying line 1 and carried into the transformation rate meter 6'to measure the ferrite transformation thickness, and then the slab is taken. It is carried into the cooling device 2. At this time, if the ferrite transformation thickness measured by the transformation rate meter 6'is not less than the predetermined value, the slab is not forcibly cooled, and if the ferrite transformation thickness is less than the predetermined value, the slab is forcibly cooled. Then, the controller 7 controls the cooling device 2. Hereinafter, similarly to the second embodiment, the ferrite transformation thickness of the slab surface is measured by the transformation rate meter 6, the slab is charged into the heating furnace 4, and rolled in the rolling line 5 to obtain a steel sheet.
【００４４】このようなプロセスによれば、スラブをス
ラブ搬送ライン１上で搬送している間にスラブ表面の十
分な厚さがフェライト変態している場合には、冷却装置
２においてスラブを強制冷却せずに加熱炉４に装入する
ので、スラブが必要以上に冷却されることを防止してス
ラブのエネルギーロスを最低限にすることができる。According to such a process, when the slab is conveyed on the slab conveyance line 1 while the slab surface has a sufficient thickness of ferrite transformation, the cooling device 2 forcibly cools the slab. Since it is charged into the heating furnace 4 without doing so, it is possible to prevent the slab from being cooled more than necessary and to minimize the energy loss of the slab.
【００４５】なお、本発明は上記実施の形態に限られる
ものではなく、種々変更が可能である。例えば、上記の
実施形態では、いずれも冷却装置２、変態率計６をスラ
ブ搬送ライン１上に設けた場合を示したがこれに限られ
るものではなく、クレーン等でスラブを搬送可能な位置
に冷却装置２や変態率計６を設けてもよい。The present invention is not limited to the above embodiment, but various changes can be made. For example, in each of the above-described embodiments, the case where the cooling device 2 and the transformation rate meter 6 are provided on the slab transfer line 1 is shown, but the present invention is not limited to this, and the slab can be transferred to a position where it can be transferred by a crane or the like. The cooling device 2 and the transformation rate meter 6 may be provided.
【００４６】[0046]
【実施例】以下、本発明の実施例について説明する。表
２に示す化学成分を有するＮｂ−Ｖ系の鋼ＡおよびＣｕ
−Ｎｉ系の鋼Ｂからなるスラブを連続鋳造により製造し
た。スラブ厚は鋼Ａでは３００ｍｍまたは２５０ｍｍと
し、鋼Ｂでは２５０ｍｍとした。この連続鋳造されたス
ラブを図２に示した鋼板の製造設備のスラブ搬送ライン
１に供給し、スプレーノズルを有する冷却装置２におい
て表３に示す水量密度および水冷時間で強制冷却し、次
いで変態率計６でスラブ表面のフェライト変態厚さを測
定してからスラブを加熱炉４に装入して加熱した後、圧
延ライン５に搬入して表３に示す圧延厚に圧延してＮ
ｏ．１〜１０の鋼板を得た。また、冷却装置２で強制冷
却する代わりに連続鋳造完了後約１０時間空冷し、その
他は前記と同様の工程によりＮｏ．１１の鋼板を得た。
表３にはまた、変態率計６で測定されたフェライト変態
厚さと、加熱炉４装入時のスラブ表面温度と、圧延ライ
ン５の圧下比と、加熱炉４の加熱温度と、鋼板における
表面疵発生の有無とを併せて示す。EXAMPLES Examples of the present invention will be described below. Nb-V based steels A and Cu having the chemical composition shown in Table 2
A slab of Ni-based steel B was produced by continuous casting. The slab thickness was 300 mm or 250 mm for Steel A and 250 mm for Steel B. This continuously cast slab is supplied to the slab transfer line 1 of the steel plate manufacturing facility shown in FIG. 2 and forcedly cooled in the cooling device 2 having a spray nozzle at the water amount density and the water cooling time shown in Table 3, and then the transformation rate. After the ferrite transformation thickness of the slab surface was measured with a total of 6, the slab was charged into the heating furnace 4 and heated, and then carried into the rolling line 5 and rolled to the rolling thickness shown in Table 3 and N
o. Steel sheets 1 to 10 were obtained. Further, instead of forcibly cooling by the cooling device 2, after the continuous casting is completed, air cooling is performed for about 10 hours, and otherwise, the same steps as described above are performed. 11 steel plates were obtained.
Table 3 also shows the ferrite transformation thickness measured by the transformation rate meter 6, the slab surface temperature at the time of charging the heating furnace 4, the rolling ratio of the rolling line 5, the heating temperature of the heating furnace 4, and the surface of the steel sheet. The presence / absence of defects is also shown.
【００４７】表３に示すように、冷却装置２で強制冷却
したＮｏ．１〜１０の鋼板においては、加熱炉装入時の
スラブ表面温度を大きく低下させることなく、スラブ表
面の所定厚さをフェライト変態させることができてい
た。さらに、圧下比が５以上かつフェライト変態厚さが
スラブ厚の５％以上を満足するか、圧下比が５未満かつ
フェライト変態厚さがスラブ厚の１０％以上を満足する
Ｎｏ．１〜７の鋼板では、表面疵の発生を防止すること
ができた。As shown in Table 3, No. 1 forcibly cooled by the cooling device 2 was used. In each of the steel sheets 1 to 10, it was possible to transform the predetermined thickness of the slab surface into ferrite without significantly lowering the slab surface temperature at the time of charging the heating furnace. Further, No. 1 having a reduction ratio of 5 or more and a ferrite transformation thickness of 5% or more of the slab thickness, or a reduction ratio of less than 5 and a ferrite transformation thickness of 10% or more of the slab thickness. With the steel sheets 1 to 7, it was possible to prevent the occurrence of surface defects.
【００４８】これに対して、冷却装置２で強制的な冷却
を行わずに空冷したＮｏ．１１の鋼板では、空冷でフェ
ライト変態厚さをスラブ厚の１０％以上とすることによ
り表面疵の発生を防止することはできたが、スラブ表面
温度は４５０℃まで低下しており、Ｎｏ．１〜１０の鋼
板と比べるとスラブ表面温度が１５０℃以上低く、大き
なエネルギーロスを生じていた。On the other hand, the cooling device 2 was cooled by air without forced cooling. In the steel sheet of No. 11, it was possible to prevent the generation of surface defects by making the ferrite transformation thickness 10% or more of the slab thickness by air cooling, but the slab surface temperature was lowered to 450 ° C. The slab surface temperature was 150 ° C. or more lower than that of the steel sheets 1 to 10 and a large energy loss was generated.
【００４９】[0049]
【表２】 [Table 2]
【００５０】[0050]
【表３】 [Table 3]
【００５１】[0051]
【発明の効果】本発明によれば、連続鋳造されたスラブ
を高温状態で加熱炉に装入した後に圧延するホットチャ
ージプロセスによる厚鋼板の製造において、加熱および
圧延の能率を阻害することなくエネルギーロスを最小限
にして、厚鋼板の表面疵を防止することが可能となり、
工業上有用な効果が得られる。EFFECTS OF THE INVENTION According to the present invention, in the production of a thick steel sheet by a hot charge process in which a continuously cast slab is charged in a heating furnace at a high temperature and then rolled, energy can be obtained without impairing the efficiency of heating and rolling. It is possible to minimize loss and prevent surface defects on thick steel plates,
Industrially useful effects are obtained.
【図１】本発明の第１の実施形態に係る鋼板の製造設備
の配置を示す模式図。FIG. 1 is a schematic diagram showing an arrangement of steel plate manufacturing equipment according to a first embodiment of the present invention.
【図２】本発明の第２の実施形態に係る鋼板の製造設備
の配置を示す模式図。FIG. 2 is a schematic diagram showing an arrangement of steel plate manufacturing equipment according to a second embodiment of the present invention.
【図３】鋼板の表面疵発生状況を調査した結果を示すグ
ラフ。FIG. 3 is a graph showing the results of an investigation of the occurrence of surface defects on steel sheets.
【図４】表面をフェライト変態させたスラブのフェライ
ト変態厚さを幅方向の複数箇所で測定し、横軸にスラブ
幅方向位置をとり、縦軸にフェライト変態厚さをとって
フェライト変態厚さの分布を示したグラフ。[Fig. 4] The ferrite transformation thickness of the slab whose surface is transformed with ferrite is measured at a plurality of positions in the width direction, the horizontal axis indicates the slab width direction position, and the vertical axis indicates the ferrite transformation thickness. A graph showing the distribution of.
【図５】本発明の第３の実施形態に係る鋼板の製造設備
の配置を示す模式図。FIG. 5 is a schematic diagram showing an arrangement of steel plate manufacturing equipment according to a third embodiment of the present invention.
１；スラブ搬送ライン ２；冷却装置 ３；温度計 ４；加熱炉 ５；圧延ライン（圧延機） ６，６′；変態率計 ７；制御手段 1; Slab transfer line 2; Cooling device 3; Thermometer 4; heating furnace 5: Rolling line (rolling machine) 6,6 '; Transformation rate meter 7; control means
───────────────────────────────────────────────────── フロントページの続き (72)発明者 加藤 宏晴 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 Ｆターム(参考） 4E002 AA05 AD07 BC05 BD02 BD07 CB01 CB03 CB07 4E004 MC01 NB01 NC01 SE03 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hiroharu Kato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Main Steel Pipe Co., Ltd. F-term (reference) 4E002 AA05 AD07 BC05 BD02 BD07 CB01 CB03 CB07 4E004 MC01 NB01 NC01 SE03
Claims (15)
炉に装入した後に圧延するホットチャージプロセスによ
り厚鋼板を製造する方法であって、加熱炉の入側に冷却
装置を設置し、前記冷却装置によりスラブを強制冷却し
てスラブ表面をフェライト変態させてから前記加熱炉に
装入することを特徴とする鋼板の製造方法。1. A method for producing a thick steel sheet by a hot charging process in which a continuously cast slab is charged into a heating furnace at a high temperature and then rolled, wherein a cooling device is installed on the inlet side of the heating furnace. A method for producing a steel sheet, comprising forcibly cooling a slab with a cooling device to transform the surface of the slab into ferrite, and then charging the slab into the heating furnace.
炉に装入した後に圧延するホットチャージプロセスによ
り厚鋼板を製造する方法であって、加熱炉の入側に冷却
装置およびスラブ表面の変態厚さを測定可能な変態率計
を設置し、前記冷却装置によりスラブを強制冷却してス
ラブ表面をフェライト変態させ、前記変態率計により強
制冷却後のスラブ表面のフェライト変態厚さを測定し、
フェライト変態厚さが所定値となってから前記加熱炉に
装入することを特徴とする鋼板の製造方法。2. A method for producing a thick steel plate by a hot charging process in which a continuously cast slab is charged into a heating furnace at a high temperature and then rolled, wherein a cooling device and a slab surface transformation are provided on the inlet side of the heating furnace. A transformation rate meter that can measure the thickness is installed, the slab is forcedly cooled by the cooling device to transform the slab surface into ferrite, and the transformation rate meter measures the ferrite transformation thickness of the slab surface after forced cooling,
A method for manufacturing a steel sheet, which comprises charging the heating furnace after the ferrite transformation thickness reaches a predetermined value.
で規定される圧下比に対応した値であることを特徴とす
る請求項２に記載の鋼板の製造方法。3. The method of manufacturing a steel sheet according to claim 2, wherein the predetermined value is a value corresponding to a reduction ratio defined by a ratio of a slab thickness and a product thickness.
きにはスラブ厚の５％であり、前記圧下比が５未満のと
きにはスラブ厚の１０％であることを特徴とする請求項
３に記載の鋼板の製造方法。4. The predetermined value is 5% of the slab thickness when the reduction ratio is 5 or more, and is 10% of the slab thickness when the reduction ratio is less than 5. A method for manufacturing the steel sheet described.
域の磁化状態に磁化し、この状態のスラブの磁化部分に
ついて交流磁場を用いて電磁気的特性の測定を行うこと
によりスラブ表面のフェライト変態厚さを測定すること
を特徴とする請求項２から請求項４のいずれか１項に記
載の鋼板の製造方法。5. A ferrite transformation on the slab surface by applying a DC magnetic field to the slab to magnetize it to a magnetization state in a rotating magnetization region and measuring the electromagnetic characteristics of the magnetized portion of the slab in this state using an AC magnetic field. The thickness is measured, The manufacturing method of the steel plate of any one of Claim 2 to Claim 4 characterized by the above-mentioned.
面のフェライト変態厚さに応じて、それ以降のスラブの
冷却条件を制御することを特徴とする請求項２から請求
項５のいずれか１項に記載の鋼板の製造方法。6. The cooling condition of the slab thereafter is controlled according to the ferrite transformation thickness of the slab surface measured by the transformation rate meter. A method for manufacturing a steel sheet according to item.
ブの幅方向中央部のみで測定することを特徴とする請求
項２から請求項６のいずれか１項に記載の鋼板の製造方
法。7. The method for producing a steel sheet according to claim 2, wherein the ferrite transformation thickness on the surface of the slab is measured only in the widthwise central portion of the slab.
部のみを強制冷却することを特徴とする請求項１から請
求項７のいずれか１項に記載の鋼板の製造方法。8. The method for manufacturing a steel sheet according to claim 1, wherein only the central portion in the width direction of the slab is forcibly cooled by the cooling device.
炉と、前記加熱炉から搬出されたスラブを圧延する圧延
機とを具備し、連続鋳造されたスラブを高温状態のまま
圧延するホットチャージプロセスを行う厚鋼板の製造設
備であって、 前記加熱炉の入側に設けられ、スラブを強制冷却してス
ラブ表面をフェライト変態させる冷却装置をさらに具備
することを特徴とする鋼板の製造設備。9. A hot furnace, comprising: a heating furnace into which a continuously cast slab is charged; and a rolling mill for rolling the slab carried out from the heating furnace, wherein the continuously cast slab is rolled in a high temperature state. A facility for manufacturing a thick steel plate for performing a charging process, further comprising a cooling device which is provided on the inlet side of the heating furnace and forcibly cools the slab to transform the surface of the slab into ferrite, .
熱炉と、前記加熱炉から搬出されたスラブを圧延する圧
延機とを具備し、連続鋳造されたスラブを高温状態のま
ま圧延するホットチャージプロセスを行う厚鋼板の製造
設備であって、 前記加熱炉の入側に設けられ、スラブを強制冷却してス
ラブ表面をフェライト変態させる冷却装置と、 前記冷却装置と前記加熱炉との間に設けられ、スラブ表
面のフェライト変態厚さを測定する変態率計とをさらに
具備し、 前記変態率計により測定されたスラブ表面のフェライト
変態厚さが所定値となった際にスラブを前記加熱炉に装
入することを特徴とする鋼板の製造設備。10. A hot furnace equipped with a heating furnace into which a continuously cast slab is charged, and a rolling mill for rolling the slab carried out from the heating furnace. A thick steel plate manufacturing facility for performing a charging process, which is provided on the inlet side of the heating furnace, and a cooling device forcibly cooling the slab to transform the surface of the slab into ferrite, and between the cooling device and the heating furnace. And a transformation rate meter provided to measure the ferrite transformation thickness of the slab surface, wherein the slab is heated when the ferrite transformation thickness of the slab surface measured by the transformation rate meter reaches a predetermined value. Steel plate manufacturing equipment characterized by charging into.
印加して回転磁化領域の磁化状態に磁化する直流磁化手
段と、スラブの磁化部分について交流磁場を用いて電磁
気的特性の測定を行う検出手段と、前記検出手段の測定
した電磁気的特性値からスラブ表面のフェライト変態厚
さを求める変態測定手段とを有することを特徴とする請
求項１０に記載の鋼板の製造設備。11. The transformation rate meter measures the electromagnetic characteristics by applying a DC magnetic field to the slab and magnetizing it to a magnetization state in a rotating magnetization region, and an AC magnetic field for the magnetized portion of the slab. The steel sheet manufacturing facility according to claim 10, further comprising: a detection unit; and a transformation measurement unit that obtains a ferrite transformation thickness of a slab surface from an electromagnetic characteristic value measured by the detection unit.
らに具備し、 前記制御手段は、前記変態率計の測定したフェライト変
態厚さに応じて、前記冷却装置がそれ以降のスラブを強
制冷却する条件を制御することを特徴とする請求項１０
または請求項１１に記載の鋼板の製造装置。12. The control device further comprises control means for controlling the cooling device, wherein the control device forcibly cools the subsequent slab according to the ferrite transformation thickness measured by the transformation rate meter. 11. The condition is controlled.
Alternatively, the steel plate manufacturing apparatus according to claim 11.
冷却装置の入側におけるスラブ表面のフェライト変態厚
さを測定する他の変態率計をさらに具備し、 前記他の変態率計の測定したフェライト変態厚さが所定
値未満の場合に前記冷却装置でスラブの強制冷却を行
い、前記他の変態率計の測定したフェライト変態厚さが
所定値以上の場合には前記冷却装置でスラブの強制冷却
を行わないことを特徴とする請求項１０から請求項１２
のいずれか１項に記載の鋼板の製造設備。13. The apparatus further comprises another transformation rate meter, which is provided on the inlet side of the cooling device and measures the ferrite transformation thickness of the slab surface on the entry side of the cooling device, the measurement of the other transformation rate meter. If the ferrite transformation thickness is less than a predetermined value, the slab is forcibly cooled by the cooling device, and if the ferrite transformation thickness measured by the other transformation rate meter is a predetermined value or more, the slab is cooled by the cooling device. The forced cooling is not performed, and the cooling is not performed.
The manufacturing equipment of the steel plate according to any one of 1.
イト変態厚さをスラブの幅方向中央部のみで測定するこ
とを特徴とする請求項１０から請求項１３のいずれか１
項に記載の鋼板の製造設備。14. The transformation rate meter measures the ferrite transformation thickness of the slab surface only in the widthwise central portion of the slab, according to any one of claims 10 to 13.
Manufacturing equipment of the steel sheet according to the item.
部のみを強制冷却することを特徴とする請求項９から請
求項１４のいずれか１項に記載の鋼板の製造設備。15. The steel sheet manufacturing facility according to claim 9, wherein the cooling device forcibly cools only the central portion in the width direction of the slab.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015136706A (en) * | 2014-01-21 | 2015-07-30 | Ｊｆｅスチール株式会社 | Steel cooling equipment and steel cooling method |
| CN114752746A (en) * | 2022-03-29 | 2022-07-15 | 太原重工工程技术有限公司 | Multi-mode steel pipe rolling process |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07331329A (en) * | 1994-06-08 | 1995-12-19 | Kobe Steel Ltd | Production of thick steel plate excellent in toughness at low temperature in hot charging process |
| JP2000304725A (en) * | 1999-04-20 | 2000-11-02 | Nkk Corp | Transformation layer thickness measurement method for steel |
-
2001
- 2001-06-26 JP JP2001192725A patent/JP4691839B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07331329A (en) * | 1994-06-08 | 1995-12-19 | Kobe Steel Ltd | Production of thick steel plate excellent in toughness at low temperature in hot charging process |
| JP2000304725A (en) * | 1999-04-20 | 2000-11-02 | Nkk Corp | Transformation layer thickness measurement method for steel |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015136706A (en) * | 2014-01-21 | 2015-07-30 | Ｊｆｅスチール株式会社 | Steel cooling equipment and steel cooling method |
| CN114752746A (en) * | 2022-03-29 | 2022-07-15 | 太原重工工程技术有限公司 | Multi-mode steel pipe rolling process |
| CN114752746B (en) * | 2022-03-29 | 2023-07-21 | 太原重工工程技术有限公司 | Multi-mode steel pipe rolling process |
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