JP3952580B2

JP3952580B2 - Online quality judgment method and equipment for surface quality of slabs and steel slabs in continuous casting and ingot rolling

Info

Publication number: JP3952580B2
Application number: JP05706798A
Authority: JP
Inventors: 村健一郎木; 島智之中; 吹隆夫雪
Original assignee: Daido Steel Co Ltd
Current assignee: Daido Steel Co Ltd
Priority date: 1998-03-09
Filing date: 1998-03-09
Publication date: 2007-08-01
Anticipated expiration: 2018-03-09
Also published as: JPH11254115A

Description

【０００１】
【発明の属する技術分野】
本発明は、連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法および判定装置に係わり、さらに詳しくは、連続鋳造によって鋳片を得たのち切断鋳片を分塊圧延することによって鋼片を得る製造工程において分塊圧延後の鋼片の表面品質を鋳片の段階でしかもオンラインで事前にあらかじめ判定し、判定の結果予想される分塊圧延後の鋼片の表面品質に応じて鋼片に対する所要のスカーフィング量をあらかじめ増減（ないしは省略）管理してスカーフィングによる歩留り損失を最小化したうえで鋼片の表面品質のより一層の向上を実現できるようにした連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法および判定装置に関するものである。
【０００２】
【従来の技術】
従来、連続鋳造によって鋳片を得たのち切断鋳片を分塊圧延することによって鋼片を得る製造工程においては、分塊圧延後の鋼片の表面品質をより一層良好なものとするために、すべての鋼片に対してほぼ同量程度（例えば、１〜３ｍｍ程度）のスカーフィングを実施していた（例えば、第３版「鉄鋼便覧」ＩＩＩ（１）圧延基礎・鋼板第１７１頁〜第１９７頁“５．５精整”第１９７頁〜第２１５頁“５．６操業管理”昭和５５年５月１５日発行）。
【０００３】
【発明が解決しようとする課題】
しかしながら、分塊圧延後の鋼片によっては、スカーフィングを実施しなくともないしはスカーフィング量を極く少量としてもその表面品質が良好であるものも存在することから、このようなスカーフィングを実施しなくともないしはスカーフィング量を極く少量としても分塊圧延後の鋼片の表面品質が良好なものにできる鋼片に対しても通常通りのスカーフィングを実施することは歩留り損失を著しく大きなものにするという課題があった。
【０００４】
また、仮に、通常のスカーフィング程度では表面品質を良好なものとすることができない鋳片がもしあるとした場合には、スカーフィング後であっても表面品質が良くない鋼片が後工程に流れてしまうこともないとはいえないという課題があった。
【０００５】
【発明の目的】
本発明は、このような従来の課題にかんがみてなされたものであって、スカーフィングを実施しなくともないしはスカーフィング量を極く少量としても分塊圧延後の鋼片の表面品質が良好なものとなる鋼片の存在を連続鋳造完了の段階からあらかじめ事前に検知することができ、このような品質良好な鋼片に対するフカーフィング量を従来に比べて低減ないしは不要として歩留り損失を最小化し、鋼片の表面品質があまり良くなくなるものと予想される鋼片に対してだけ必要最少量のスカーフィングを実施するようにして、スカーフィングによる歩留り損失を最小限にしたうえで鋼片の表面品質のより一層の向上を図ることができるようにすることを目的としている。
【０００６】
【課題を解決するための手段】
本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法は、請求項１に記載しているように、タンディッシュ内の溶鋼を鋳型内に流下し、鋳型の下部より鋳片を引抜いてわん曲形状にすると共にわん曲形状の鋳片をピンチロールにより矯正して横向状態としたあと切断し、切断鋳片を水冷水槽内に浸漬して水冷することにより鋳片表層部の組織を微細化する連続鋳造工程において水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定するに際し、ピンチロールによる矯正前の鋳片温度と、水冷前の水槽水温と、水冷前の鋳片温度を連続的に記録し、トラッキング整理して鋳片単位での各熱履歴から水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定するようにしたことを特徴としている。
【０００７】
そして、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施態様においては、請求項２に記載しているように、鋳型内での初期凝固・鋳造条件をも連続的に記録するようにしたことを特徴としている。
【０００８】
同じく、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施態様においては、請求項３に記載しているように、鋳型内での初期凝固・鋳造条件をも連続的に記録するに際しては、過熱温度と湯面変動と引抜速度をも連続的に記録するようにしたことを特徴としている。
【０００９】
同じく、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施態様においては、請求項４に記載しているように、鋳型内での初期凝固・鋳造条件をも連続的に記録するに際しては、抜熱変動によりデプレッションないしは縦割れの有無をも連続的に記録するようにしたことを特徴としている。
【００１０】
同じく、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施態様においては、請求項５に記載しているように、ピンチロールによる矯正前の鋳片温度は、鋳片に割れが発生するおそれのない適正温度領域Ａ_Ｍと、鋳片にＡ_３変態点挙動による割れが発生するおそれのある変態点挙動温度領域Ａ_Ｈと、鋳片に延性不足による割れが発生するおそれのある延性不足温度領域Ａ_Ｌとに区分して連続的に記録するようにしたことを特徴としている。
【００１１】
同じく、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施態様においては、請求項６に記載しているように、水冷前の水槽水温は、鋳片の水冷に際し冷却能力不足となるおそれのない適正温度領域Ａ_１，Ａ_２，Ａ_６と、鋳片の水冷に際し冷却能力不足となるおそれのある上昇温度領域Ａ_３，Ａ_４，Ａ_５，Ａ_１０とに区分して連続的に記録するようにしたことを特徴としている。
【００１２】
同じく、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施態様においては、請求項７に記載しているように、水冷前の鋳片温度は、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７と、水冷時に鋳片の面部に割れが発生するおそれはないもののコーナー部に割れが発生するおそれのあるやや危険温度領域Ａ_８と、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのある危険温度領域Ａ_９とに区分して連続的に記録するようにしたことを特徴としている。
【００１３】
同じく、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施態様においては、請求項８に記載しているように、まず、ピンチロールによる矯正前の鋳片温度が適正温度領域Ａ_Ｍにあるか否かを判定し、次に、水冷前の水槽水温が鋳片の水冷に際し冷却不足のおそれのない適正温度領域Ａ_１，Ａ_２，Ａ_６にあるか否かを判定し、次いで、水冷前の鋳片温度が水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７にあるか否かを判定し、これらの順次判定をトラッキング整理して鋳片単位での上記熱履歴から水冷後の鋳片段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定するようにしたことを特徴としている。
【００１４】
同じく、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施態様においては、請求項９に記載しているように、ピンチロールによる矯正前の鋳片温度と水冷前の水槽水温と水冷前の鋳片温度におけるそれぞれの適正温度を鋼種毎に設定するようにしたことを特徴としている。
【００１５】
本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定装置は、請求項１０に記載しているように、タンディッシュ内の溶鋼を鋳型内に流下し、鋳型の下部より鋳片を引抜いてわん曲形状にすると共にわん曲形状の鋳片をピンチロールにより矯正して横向状態としたあと切断し、切断鋳片を水冷水槽内に浸漬して水冷することにより鋳片表層部の組織を微細化する連続鋳造工程において水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定する装置であって、ピンチロールによる矯正前の鋳片温度を測定するピンチロール矯正前鋳片温度センサーと、水冷前の水槽水温を測定する水槽水温センサーと、水冷前の鋳片温度を測定する水冷前鋳片温度センサーと、前記各センサーによる測温結果を連続的に記録すると共にトラッキング整理して鋳片単位での各熱履歴から水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定する表面品質オンライン判定手段を備えたことを特徴としている。
【００１６】
そして、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定装置の実施態様においては、請求項１１に記載しているように、鋳型壁面での抜熱変動を測定する鋳型壁面温度センサーを備え、表面品質オンライン判定手段は前記鋳型壁面温度センサーによる測温結果を連続的に記録すると共にトラッキング整理して鋳片単位での各熱履歴から水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定するものとしたことを特徴としている。
【００１７】
同じく、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定装置の実施態様においては、請求項１２に記載しているように、表面品質オンライン判定手段は、ピンチロールによる矯正前の鋳片温度と水冷前の水槽水温と水冷前の鋳片温度におけるそれぞれの適正温度領域を鋼種毎に定めた判定テーブルを備えているものとしたことを特徴としている。
【００１８】
【発明の実施の形態】
図１は、本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法の実施に使用するオンライン判定装置の一実施形態を示すものであって、この図１は、取鍋１内の溶鋼２をタンディッシュ３に受け、このタンディッシュ３内の溶鋼２を鋳型４内に流下し、鋳型４の下部より鋳片５を引抜いて図示しないサポートロールを通過しながらわん曲形状にすると共にわん曲形状の鋳片５をピンチロール６により矯正して横向きの水平状態としたあとフレームカッター８により切断し、ここで得た切断鋳片５（Ｂ）を水冷水槽１１内の冷却水１２中にに浸漬して水冷することにより鋳片表層部の組織を微細化する連続鋳造工程を示している。
【００１９】
そして、この水冷後の切断鋳片５（Ｂ）は、加熱炉１３内に装入されて所定の分塊圧延温度にまで加熱され、次いで、分解圧延機のロール１４で分塊圧延されることによって鋼片１５となる。
【００２０】
このような連続鋳造工程において、水冷後の鋳片５（Ｂ）の段階で分塊圧延後の鋼片１５の表面品質をオンラインで事前判定するための装置２０は、ピンチロール６による矯正前の鋳片温度（例えば、鋳片コーナー部温度）を測定するピンチロール矯正前鋳片温度センサー２１と、水冷前の水槽水温（冷却水１２の水温）を測定する水槽水温センサー２２と、水冷前の鋳片温度を測定する水冷前鋳片温度センサー２３と、鋳型４の内壁面での抜熱変動を測定する鋳型壁面温度センサー２４と、湯面変動などを測定する湯面センサー２５等をそなえている。
【００２１】
さらに、前記各センサー２１，２２，２３，２４，２５等による測温結果やロール回転速度から算出される引抜速度（鋳造速度：Ｖｃ）等のデータは信号変換器２６を経てデプレッション警報手段２７に入力されると共に、前記各センサー２１，２２，２３，２４，２５による測温結果を連続的に記録しかつまたこれらのデータをトラッキング（ｔｒａｃｋｉｎｇ）整理して鋳片単位での各熱履歴から水冷後の鋳片５（Ｂ）の段階で分塊圧延後の鋼片１５の表面品質をオンラインで事前判定する表面品質オンライン判定手段２８を備えている。
【００２２】
なお、鋳型壁面温度センサー２４を用いたデプレッションの検出は、デプレッションの発生によりデプレッション発生部分と鋳型４の壁面部分との間でエヤーギャップが形成された場合に鋳型温度が急激に低下することを利用したもので、鋳型４の上下に温度センサー２４として上部熱電対２４Ｕおよび下部熱電対２４Ｄを設けておくことによって、図２に示すように、正常な部分Ｎｍに対して、デプレッション発生部分Ｄｐでは鋳型温度の急激な下降位置が上部熱電対２４Ｕと下部熱電対２４Ｄとで若干ずれることを検出してデプレッションの有無を判定する。
【００２３】
そこで、このような連続鋳造工程において水冷後の鋳片５（Ｂ）の段階で分塊圧延後の鋼片１５の表面品質をオンラインで事前にあらかじめ判定するに際しては、ピンチロール矯正前鋳片温度センサー２１によってピンチロールによる矯正前の鋳片温度を測定し、水槽水温センサー２２によって水冷前の水槽水温を測定し、水冷前鋳片温度センサー２３によって水冷前の鋳片温度を測定してそれぞれ連続的に記録し、トラッキング整理して鋳片単位での各熱履歴から水冷後の鋳片５（Ｂ）の段階で分塊圧延後の鋼片１５の表面品質を表面品質オンライン判定手段２８によりオンラインで事前判定する。
【００２４】
この場合、鋳型４内での初期凝固・鋳造条件をも連続的に記録するようになすことができ、例えば、鋳型４内での初期凝固・鋳造条件をも連続的に記録するに際しては、溶鋼２の過熱温度（ＳＨ）と湯面センサー２５による湯面変動とピンチロール６の回転数で計算される引抜速度（Ｖｃ）をも連続的に記録するようになすことができ、また、鋳型４の壁面での抜熱変動によりデプレッションの有無をも連続的に記録するようになすことができる。
【００２５】
そして、表１に示すように、ピンチロールによる矯正前の鋳片温度は、鋳片に割れが発生するおそれのない適正温度領域Ａ_Ｍと、鋳片にＡ_３変態点挙動による割れが発生するおそれのある変態点挙動温度領域Ａ_Ｈと、鋳片に延性不足による割れが発生するおそれのある延性不足温度領域Ａ_Ｌとに区分して連続的に記録する。
【００２６】
また、水冷前の水槽水温は、表１および表２に示すように、鋳片の水冷に際し冷却能力不足となるおそれのない適正温度領域Ａ_１，Ａ_２，Ａ_６（図３参照）と、鋳片の水冷に際し冷却能力不足となるおそれのある上昇温度領域Ａ_３，Ａ_４，Ａ_５，Ａ_１０（図３，図４参照）とに区分して連続的に記録する。
【００２７】
さらにまた、水冷前の鋳片温度は同じく表１および表２に示すように、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７（図４参照）と、水冷時に鋳片の面部に割れが発生するおそれはないもののコーナー部に割れが発生するおそれのあるやや危険温度領域Ａ_８（図４参照）と、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのある危険温度領域Ａ_９（図４参照）とに区分して連続的に記録する。
【００２８】
そして、まず、ピンチロールによる矯正前の鋳片温度が適正温度領域Ａ_Ｍにあるか否かを判定し、次に、水冷前の水槽水温が鋳片の水冷に際し冷却不足のおそれのない適正温度領域Ａ_１，Ａ_２，Ａ_６にあるか否かを判定し、次いで、水冷前の鋳片温度が水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７にあるか否かを判定し、これらの順次判定をトラッキング整理して鋳片単位での上記熱履歴から水冷後の鋳片段階で分塊圧延後の鋼片１５の表面品質をオンラインで事前にあらかじめ判定する。
【００２９】
【表１】

【００３０】
【表２】

【００３１】
この結果、同じく表１に示すように、ピンチロール６による矯正前の鋳片温度が適正温度領域Ａ_Ｍにあり、水冷前の水槽水温が鋳片５の水冷に際し冷却不足のおそれのない適正温度領域Ａ_１にあり、水冷前の鋳片温度が水冷時に鋳片５の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７にあるものについては、あらかじめの実験データにより、分塊圧延後の鋼片１５においてスカーフィングが不要であることが確かめられているので、上記条件を満足した鋳片は分塊圧延後において鋼片に対するスカーフィングを省略する。
【００３２】
また、水冷時に鋳片の面部に割れが発生するおそれはないもののコーナー部に割れが発生するおそれのあるやや危険温度領域Ａ_８を経由した鋳片や、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのある危険温度領域Ａ_９を経由した鋳片については、分塊圧延後の鋼片に対して従来よりも軽度のスカーフィングを行う。
【００３３】
そして、変態点挙動温度領域Ａ_Ｈを経由したものや、延性不足温度領域Ａ_Ｌを経由したものについては、圧延後の鋼片に対して従来通りのスカーフィングを行う。
【００３４】
これらの各温度領域は、鋼種によってもそれぞれ異なるので、ピンチロールによる矯正前の鋳片温度と水冷前の水槽水温と水冷前の鋳片温度におけるそれぞれの適正温度を鋼種毎に設定した判定テーブルをそなえておくことが望ましい。
【００３５】
【実施例】
以下、本発明の実施例についてさらに具体的に説明するが、本発明はこのような実施例のみに限定されないことはいうまでもない。
【００３６】
この実施例においては、機械構造用鋼（クロム鋼：ＪＩＳＳＣＲ４２０Ｈ）について、浸炭時結晶粒粗大化防止のためＡｌ，Ｎを適切な量にコントロールしたもの（Ａｌ，Ｎコントロール材）、通常処理したもの（通常処理材）、含Ｐｂのもの（含Ｐｂ材）について、それぞ連続鋳造および分塊圧延を行い、鋼片における粒界割れや縦割れの発生状況について調べた。
【００３７】
そこで、図１に示した連続鋳造工程において、ピンチロール矯正前温度センサー２１によってピンチロールによる矯正前の鋳片温度を測定し、水槽水温センサー２２によって水冷前の水槽水温を測定し、水冷前鋳片温度センサー２３によって水冷前の鋳片温度を測定してそれぞれ連続的に記録し、トラッキング整理して鋳片単位での各熱履歴から水冷後の鋳片５（Ｂ）の段階で分塊圧延後の鋼片１５の表面品質を表面品質オンライン判定手段２８によりオンラインで事前判定することとした。
【００３８】
そして、このとき、鋳型４内での初期凝固・鋳造条件をも連続的に記録するに際しては、溶鋼２の過熱温度（ＳＨ）と湯面センサー２５による湯面変動とピンチロール６の回転数で計算される引抜速度（Ｖｃ）をも連続的に記録し、また、鋳型４の壁面での抜熱変動によりデプレッションの有無をも連続的に記録するようにした。
【００３９】
そして、表１に示したように、ピンチロールによる矯正前の鋳片温度は、鋳片に割れが発生するおそれのない適正温度領域Ａ_Ｍ（この実施例では、表３に示しているように、７４０〜８３０℃）と、鋳片にＡ_３変態点挙動による割れが発生するおそれのある変態点挙動温度領域Ａ_Ｈ（この実施例では、表３に示しているように、８３０℃超過）と、鋳片に延性不足による割れが発生するおそれのある延性不足温度領域Ａ_Ｌ（この実施例では、表３に示しているように、７４０℃未満）とに区分して連続的に記録した。
【００４０】
また、水冷前の水槽水温は、表１および表２に示したように、鋳片の水冷に際し冷却能力不足となるおそれのない適正温度領域Ａ_１，Ａ_２，Ａ_６（この実施例では、表３および図３に示しているように、４３℃以下）と、鋳片の水冷に際し冷却能力不足となるおそれのある上昇温度領域Ａ_３，Ａ_４，Ａ_５，Ａ_１０（この実施例では、表３および図３，図４に示しているように、４３℃超過）とに区分して連続的に記録した。
【００４１】
さらにまた、水冷前の鋳片温度は同じく表１および表２に示したように、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７（この実施例では、表３および図４に示しているように、８２０℃超過）と、水冷時に鋳片の面部に割れが発生するおそれはないもののコーナー部に割れが発生するおそれのあるやや危険温度領域Ａ_８（この実施例では、表３および図４に示しているように、７４０〜８２０℃）と、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのある危険温度領域Ａ_９（この実施例では、表３および図４に示しているように、７４０℃未満）とに区分して連続的に記録した。
【００４２】
そして、まず、ピンチロールによる矯正前の鋳片温度が適正温度領域Ａ_Ｍ（すなわち、７４０〜８３０℃）にあるか否かを判定し、次に、水冷前の水槽水温が鋳片の水冷に際し冷却不足のおそれのない適正温度領域Ａ_１，Ａ_２，Ａ_６（すなわち、４３℃以下）にあるか否かを判定し、次いで、水冷前の鋳片温度が水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７（すなわち、８２０℃超過）にあるか否かを判定し、これらの順次判定をトラッキング整理して鋳片単位での上記熱履歴から水冷後の鋳片段階で分塊圧延後の鋼片１５の表面品質を表面品質オンライン判定手段２８によりオンラインで事前にあらかじめ判定した。
【００４３】
【表３】

【００４４】
この結果、同じく表３に示すように、ピンチロールによる矯正前の鋳片温度が適正温度領域Ａ_Ｍ（すなわち、７４０〜８３０℃）にあり、水冷前の水槽水温が鋳片５の水冷に際し冷却不足のおそれのない適正温度領域Ａ_１（すなわち、４３℃以下）にあり、水冷前の鋳片温度が水冷時に鋳片５の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７（すなわち、８２０℃超過）にあるものについては、表３に示す実験データにより、分塊圧延後の鋼片１５において粒界割れや縦割れが発生していないことから、スカーフィングが不要であることが確かめられているので、上記条件を満足した鋳片は分塊圧延後において鋼片に対するスカーフィングを省略した。
【００４５】
また、水冷時に鋳片の面部に割れが発生するおそれはないもののコーナー部に割れが発生するおそれのあるやや危険温度領域Ａ_８（すなわち、７４０〜８２０℃）を経由した鋳片や、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのある危険温度領域Ａ_９（すなわち、７４０℃未満）を経由した鋳片についても、表３の実験データからは粒界割れや縦割れが発生していないので、分塊圧延後の鋼片に対してスカーフィングは不要である判断されるが、大事をとって分塊圧延後の鋼片に対して従来よりも軽度のスカーフィングを行った。
【００４６】
そして、変態点挙動温度領域Ａ_Ｈ（すなわち、８３０℃超過）を経由したものや、延性不足温度領域Ａ_Ｌ（すなわち、７４０℃未満）を経由したものについては、分塊圧延後の鋼片に対して従来通りのスカーフィングを行った。
【００４７】
なお、上記した各温度領域は、鋼種によってもそれぞれ異なるので、各鋼種毎に各温度領域を設定した判定テーブルをそなえておくのが望ましいことが確認された。
【００４８】
【発明の効果】
本発明による連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定方法では、請求項１に記載しているように、タンディッシュ内の溶鋼を鋳型内に流下し、鋳型の下部より鋳片を引抜いてわん曲形状にすると共にわん曲形状の鋳片をピンチロールにより矯正して横向状態としたあと切断し、切断鋳片を水冷水槽内に浸漬して水冷することにより鋳片表層部の組織を微細化する連続鋳造工程において水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定するに際し、ピンチロールによる矯正前の鋳片温度と、水冷前の水槽水温と、水冷前の鋳片温度を連続的に記録し、トラッキング整理して鋳片単位での各熱履歴から水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定するようにしたから、スカーフィングが軽減ないしは不要である鋼片に対しても従来通りのスカーフィングを行うことが回避されるので、スカーフィングに伴なう歩留り損失を必要最小量とすることが可能となり、歩留りの向上ならびに鋼片表面品質のより一層の向上を実現することが可能であるという著大なる効果がもたらされる。
【００４９】
そして、請求項２に記載しているように、鋳型内での初期凝固・鋳造条件をも連続的に記録するようになすことによって、鋳型内での初期凝固・鋳造条件をも警告ないしは判定要因に加味することが可能であるという著大なる効果がもたらされる。
【００５０】
また、請求項３に記載しているように、鋳型内での初期凝固・鋳造条件をも連続的に記録するに際しては、過熱温度と湯面変動と引抜速度をも連続的に記録するようになすことによって、これらの過熱温度と湯面変動と引抜速度をも警告ないしは判定要因に加味することが可能であるという著大なる効果がもたらされる。
【００５１】
さらにまた、請求項４に記載しているように、鋳型内での初期凝固・鋳造条件をも連続的に記録するに際しては、抜熱変動によりデプレッションの有無をも連続的に記録するようになすことによって、このようなデプレッションの有無をも警告ないしは判定要因に加味することが可能であるという著大なる効果がもたらされる。
【００５２】
さらにまた、請求項５に記載しているように、ピンチロールによる矯正前の鋳片温度は、鋳片に割れが発生するおそれのない適正温度領域Ａ_Ｍと、鋳片にＡ_３変態点挙動による割れが発生するおそれのある変態点挙動温度領域Ａ_Ｈと、鋳片に延性不足による割れが発生するおそれのある延性不足温度領域Ａ_Ｌとに区分して連続的に記録するようになすことによって、スカーフィングを軽微ないしは不要としうる鋼片をその鋼片に対応する鋳片の段階で判定することが可能であるという著大なる効果がもたらされる。
【００５３】
さらにまた、請求項６に記載しているように、水冷前の水槽水温は、鋳片の水冷に際し冷却能力不足となるおそれのない適正温度領域Ａ_１，Ａ_２，Ａ_６と、鋳片の水冷に際し冷却能力不足となるおそれのある上昇温度領域Ａ_３，Ａ_４，Ａ_５，Ａ_１０とに区分して連続的に記録するようになすことによって、スカーフィングを軽微ないしは不要としうる鋼片をその鋼片に対応する鋳片の段階で判定することが可能であるという著大なる効果がもたらされる。
【００５４】
さらにまた、請求項７に記載しているように、水冷前の鋳片温度は、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７と、水冷時に鋳片の面部に割れが発生するおそれはないもののコーナー部に割れが発生するおそれのあるやや危険温度領域Ａ_８と、水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのある危険温度領域Ａ_９とに区分して連続的に記録するようになすことによって、スカーフィングを軽微ないしは不要としうる鋼片をその鋼片に対応する鋳片の段階で判定することが可能であるという著大なる効果がもたらされる。
【００５５】
そしてまた、請求項８に記載しているように、まず、ピンチロールによる矯正前の鋳片温度が適正温度領域Ａ_Ｍにあるか否かを判定し、次に、水冷前の水槽水温が鋳片の水冷に際し冷却不足のおそれのない適正温度領域Ａ_１，Ａ_２，Ａ_６にあるか否かを判定し、次いで、水冷前の鋳片温度が水冷時に鋳片の面部およびコーナー部ともに割れが発生するおそれのない適正温度領域Ａ_７にあるか否かを判定し、これらの順次判定をトラッキング整理して鋳片単位での上記熱履歴から水冷後の鋳片段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定するようになすことによって、鋼片における粒界割れや縦割れの発生を矯正前鋳片温度＞水冷前の水槽水温＞水冷前の鋳片温度の条件で判定することにより、鋳片の段階で鋼片の表面品質を検知することが可能であるという著大なる効果がもたらされる。
【００５６】
さらにまた、請求項９に記載しているように、ピンチロールによる矯正前の鋳片温度と水冷前の水槽水温と水冷前の鋳片温度におけるそれぞれの適正温度を鋼種毎に設定するようになすことによって、各鋼種に対応したオンラインでの品質判定を行うことが可能であるという著大なる効果がもたらされる。
【００５７】
本発明による連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定装置によれば、請求項１０に記載しているように、タンディッシュ内の溶鋼を鋳型内に流下し、鋳型の下部より鋳片を引抜いてわん曲形状にすると共にわん曲形状の鋳片をピンチロールにより矯正して横向状態としたあと切断し、切断鋳片を水冷水槽内に浸漬して水冷することにより鋳片表層部の組織を微細化する連続鋳造工程において水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定する装置であって、ピンチロールによる矯正前の鋳片温度を測定するピンチロール矯正前鋳片温度センサーと、水冷前の水槽水温を測定する水槽水温センサーと、水冷前の鋳片温度を測定する水冷前鋳片温度センサーと、前記各センサーによる測温結果を連続的に記録すると共にトラッキング整理して鋳片単位での各熱履歴から水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定する表面品質オンライン判定手段を備えたものとしたから、スカーフィングが軽減ないしは省略が可能である鋼片に対しても従来のごときスカーフィングを行うことが回避されるので、スカーフィングに伴う歩留り損失を必要最小量とすることが可能となり、歩留りの向上ならびに鋼片表面品質のより一層の向上を実現することが可能であるという著大なる効果がもたらされる。
【００５８】
そして、請求項１１に記載しているように、鋳型壁面での抜熱変動を測定する鋳型壁面温度センサーを備え、表面品質オンライン判定手段は前記鋳型壁面温度センサーによる測温結果を連続的に記録すると共にトラッキング整理して鋳片単位での各熱履歴から水冷後の鋳片の段階で分塊圧延後の鋼片の表面品質をオンラインで事前判定するようになすことによって、抜熱変動の測定によるデプレッション（縦割れ）の発生の有無をも判定・警告することが可能であるという著大なる効果がもたらされる。
【００５９】
そしてまた、請求項１２に記載しているように、表面品質オンライン判定手段は、ピンチロールによる矯正前の鋳片温度と水冷前の水槽水温と水冷前の鋳片温度におけるそれぞれの適正温度領域を鋼種毎に定めた判定テーブルを備えているものとすることによって、各鋼種に対応したオンラインでの表面品質判定を行うことが可能であるという著大なる効果がもたらされる。
【図面の簡単な説明】
【図１】本発明に係わる連続鋳造・分塊圧延における鋳片・鋼片の表面品質オンライン判定装置の一実施形態を連続鋳造設備の概要と共に示す説明図である。
【図２】鋳型内壁でのデプレッションの検出原理を示す説明図である。
【図３】本発明の実施例において測定したピンチロールによる矯正前の鋳片（コーナー）温度と水槽水温との関係を例示するグラフである。
【図４】本発明の実施例において測定した水槽水温と冷却前の鋳片温度との関係を例示するグラフである。
【符号の説明】
１取鍋
２溶鋼
３タンディッシュ
４鋳型
５鋳片
５（Ｂ）切断鋳片
６ピンチロール
８フレームカッター
１１水冷水槽
１２冷却水
１３加熱炉
１４分塊圧延機のロール
１５鋼片
２０鋳片・鋼片の表面品質オンライン判定装置
２１ピンチロール矯正前鋳片温度センサー
２２水槽水温センサー
２３水冷前鋳片温度センサー
２４鋳型壁面温度センサー
２５湯面センサー
２６信号変換器
２７デプレッション警報手段
２８表面品質オンライン判定手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for determining the surface quality of slabs and steel slabs in continuous casting and ingot rolling. More specifically, the present invention relates to a method for determining the surface quality of slabs and steel slabs. In the manufacturing process of obtaining steel slabs, the surface quality of the steel slab after partial rolling is preliminarily determined in advance at the slab stage and online in advance at the slab stage. In response to this, continuous scarfing can be achieved by further increasing (or omitting) the required amount of scarfing on the billet to minimize the yield loss due to scarfing and further improving the surface quality of the billet. The present invention relates to an on-line determination method and determination apparatus for surface quality of cast slabs and steel slabs in block rolling.
[0002]
[Prior art]
Conventionally, in the manufacturing process of obtaining a steel slab by obtaining a slab by continuous casting and then rolling the cut slab in order to make the surface quality of the steel slab after the batch rolling even better. , Scarfing was carried out on almost all the steel pieces (for example, about 3 to 3 mm) (for example, 3rd edition “Steel Handbook” III (1) Rolling foundation / steel plate, page 171 to Page 197 “5.5 Refinement” pages 197 to 215 “5.6 Operation Management” issued on May 15, 1980.
[0003]
[Problems to be solved by the invention]
However, depending on the slab after the rolling, there are some which have good surface quality even if the scarfing is not performed or the scarfing amount is very small. Even if the amount of scarfing is not carried out or the amount of scarfing is extremely small, the normal scarfing of steel pieces that can improve the surface quality of the steel pieces after partial rolling will reduce yield loss. There was a problem of making it extremely large.
[0004]
In addition, if there is a slab that cannot be made to have good surface quality with a normal scarfing grade, a steel slab whose surface quality is not good even after scarfing is in the subsequent process. There was a problem that it could not be said that it would never flow.
[0005]
OBJECT OF THE INVENTION
The present invention has been made in view of such conventional problems, and the surface quality of the steel slab after split rolling is good even if scarfing is not performed or the scarfing amount is extremely small. The presence of steel slabs can be detected in advance from the stage of completion of continuous casting in advance, and the amount of fuffing for such steel slabs with good quality is reduced or unnecessary compared to conventional products, minimizing yield loss. The surface quality of the slab is minimized by reducing the scarfing yield loss by performing the minimum amount of scarfing only on the slab where the slab surface quality is expected to be poor. It aims at making it possible to aim at further improvement of.
[0006]
[Means for Solving the Problems]
According to the method for determining the surface quality of the slab / steel slab in continuous casting / slab rolling according to the present invention, the molten steel in the tundish flows down into the mold as described in claim 1, and the lower part of the mold The slab is drawn into a curved shape, and the curved slab is corrected with a pinch roll to be in a horizontal state and then cut, and the cut slab is immersed in a water-cooled water bath and cooled with water. In the continuous casting process to refine the structure of the surface layer part, the slab temperature before straightening with a pinch roll and water cooling when pre-determining the surface quality of the steel slab after ingot rolling at the stage of slab after water cooling. Continuously record the water temperature of the previous tank and the slab temperature before water cooling, track and arrange the surface quality of the steel slab after roll rolling at the stage of the slab after water cooling from each heat history in slab unit Was pre-determined online It is characterized by a door.
[0007]
In the embodiment of the method for determining the surface quality of the slab / steel slab in the continuous casting / slab rolling according to the present invention, the initial solidification / casting conditions in the mold as described in claim 2 Is also characterized by continuous recording.
[0008]
Similarly, in the embodiment of the method for determining the surface quality of the slab / steel slab in the continuous casting / slab rolling according to the present invention, the initial solidification / casting conditions in the mold as described in claim 3 Is also characterized in that the overheating temperature, the molten metal surface fluctuation, and the drawing speed are also recorded continuously.
[0009]
Similarly, in the embodiment of the method for determining the surface quality of the slab / steel slab in the continuous casting / slab rolling according to the present invention, the initial solidification / casting conditions in the mold as described in claim 4 In the case of continuous recording, the presence or absence of depletion or vertical cracking is continuously recorded due to fluctuations in heat removal.
[0010]
Similarly, in the embodiment of the method for determining the surface quality of the slab / steel slab in the continuous casting / slab rolling according to the present invention, the slab temperature before correction by the pinch roll as described in claim 5 Is the appropriate temperature region A where there is no risk of cracking in the slab _M And A on the slab ₃ Transformation point behavior temperature region A in which cracking due to transformation point behavior may occur _H And a ductility deficient temperature region A in which cracking due to insufficient ductility may occur in the slab. _L It is characterized by the fact that it is divided and recorded continuously.
[0011]
Similarly, in the embodiment of the method for determining the surface quality of the slab / steel slab in the continuous casting / slab rolling according to the present invention, as described in claim 6, Temperature range A with no fear of insufficient cooling capacity during water cooling ₁ , A ₂ , A ₆ And rising temperature region A, which may result in insufficient cooling capacity during water cooling of the slab ₃ , A ₄ , A ₅ , A ₁₀ It is characterized by the fact that it is divided and recorded continuously.
[0012]
Similarly, in the embodiment of the method for determining the surface quality of the slab / steel slab in the continuous casting / slab rolling according to the present invention, as described in claim 7, the slab temperature before water cooling is water cooling. Appropriate temperature range A where there is no risk of cracks occurring on both the slab face and corner ₇ Although there is no risk of cracking in the surface part of the slab during water cooling, there is a risk of cracking in the corner part. ₈ And a dangerous temperature region A where the surface portion and corner portion of the slab may crack during water cooling. ₉ It is characterized by the fact that it is divided and recorded continuously.
[0013]
Similarly, in the embodiment of the method for determining the surface quality of the slab / steel slab in the continuous casting / slab rolling according to the present invention, as described in claim 8, first, the casting before correction by the pinch roll is used. One temperature is the appropriate temperature range A _M Next, the temperature of the water tank before water cooling is an appropriate temperature region A where there is no risk of insufficient cooling when the slab is cooled with water. ₁ , A ₂ , A ₆ Next, the temperature of the slab before water cooling is an appropriate temperature region A in which there is no risk of cracks occurring on both the surface and corners of the slab during water cooling. ₇ The surface quality of the steel slab after the ingot rolling is pre-determined on-line in the slab stage after water cooling from the above heat history in slab units. It is characterized by doing so.
[0014]
Similarly, in the embodiment of the method for determining the surface quality of the slab / steel slab in the continuous casting / slab rolling according to the present invention, as described in claim 9, the slab temperature before correction with a pinch roll In addition, the temperature is set appropriately for each steel type in the water temperature of the water tank before water cooling and the slab temperature before water cooling.
[0015]
The on-line surface quality judgment apparatus for slab / steel slab in continuous casting / slab rolling according to the present invention, as described in claim 10, flows down the molten steel in the tundish into the mold, and lowers the mold. The slab is drawn into a curved shape, and the curved slab is corrected with a pinch roll so as to be in a horizontal state and then cut, and the cut slab is immersed in a water-cooled water bath and cooled with water. This is a device that pre-determines the surface quality of the steel slab after the batch rolling at the stage of the slab after water cooling in the continuous casting process for refining the structure of the surface layer part, and the slab temperature before correction by the pinch roll Slab temperature sensor before pinch roll correction to measure water temperature, water tank water temperature sensor to measure water tank water temperature before water cooling, water slab temperature sensor to measure slab temperature before water cooling, and temperature measurement results by each sensor The Equipped with surface quality online judgment means to pre-determine online the surface quality of the steel slab after split rolling at the stage of the slab after water cooling from each heat history in the slab unit by continuously recording and tracking It is characterized by that.
[0016]
And in the embodiment of the surface quality on-line judgment apparatus for the slab / steel slab in the continuous casting / slab rolling according to the present invention, as described in claim 11, the heat removal fluctuation at the mold wall surface is measured. The surface quality online determination means continuously records the temperature measurement result by the mold wall surface temperature sensor and tracks the slab after water cooling from each heat history in the slab unit. It is characterized in that the surface quality of the steel slab after ingot rolling is pre-determined online.
[0017]
Similarly, in the embodiment of the on-line surface quality determination device for slabs and steel slabs in continuous casting and ingot rolling according to the present invention, as described in claim 12, the surface quality on-line determination means is a pinch roll. It is characterized by having a determination table for each steel type, which is determined for each steel temperature in the slab temperature before correction, water tank water temperature before water cooling, and slab temperature before water cooling.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of an on-line determination apparatus used for carrying out a method for determining the surface quality of a slab / steel slab in continuous casting / slab rolling according to the present invention. The molten steel 2 in the ladle 1 is received by the tundish 3, the molten steel 2 in the tundish 3 flows down into the mold 4, the slab 5 is pulled out from the lower part of the mold 4 and passes through a support roll (not shown). The curved slab 5 is bent and corrected with a pinch roll 6 to make it horizontally horizontal and then cut with a frame cutter 8. The cut slab 5 (B) obtained here is stored in a water-cooled water tank 11. The continuous casting process which refines | miniaturizes the structure | tissue of a slab surface layer part by being immersed in the cooling water 12 of this and water-cooling is shown.
[0019]
Then, the water-cooled cut slab 5 (B) is charged into the heating furnace 13 and heated to a predetermined partial rolling temperature, and then is subjected to partial rolling with a roll 14 of a cracking rolling mill. The steel slab 15 is obtained.
[0020]
In such a continuous casting process, the device 20 for online determination of the surface quality of the steel slab 15 after the block rolling at the stage of the slab 5 (B) after water cooling is performed before the correction by the pinch roll 6. A slab temperature sensor 21 before pinch roll correction for measuring a slab temperature (for example, a slab corner temperature), a tank water temperature sensor 22 for measuring a tank water temperature (water temperature of the cooling water 12) before water cooling, A water-cooled slab temperature sensor 23 for measuring the slab temperature, a mold wall surface temperature sensor 24 for measuring the heat removal fluctuation on the inner wall surface of the mold 4, and a hot water surface sensor 25 for measuring the fluctuation of the molten metal surface are provided. Yes.
[0021]
Further, data such as the temperature measurement results obtained by the

sensors

21, 22, 23, 24, 25, and the drawing speed (casting speed: Vc) calculated from the roll rotation speed are sent to the depletion alarm means 27 via the signal converter 26. In addition to the input, the temperature measurement results by the

sensors

21, 22, 23, 24, and 25 are continuously recorded, and the data is tracked to be water-cooled from each heat history in the slab unit. Surface quality online determination means 28 for determining online the surface quality of the steel slab 15 after the ingot rolling at the stage of the subsequent slab 5 (B) is provided.
[0022]
Note that the detection of depletion using the mold wall temperature sensor 24 utilizes the fact that the mold temperature rapidly decreases when an air gap is formed between the depletion occurrence part and the wall surface part of the mold 4 due to the occurrence of depletion. Thus, by providing an upper thermocouple 24U and a lower thermocouple 24D as temperature sensors 24 above and below the mold 4, as shown in FIG. 2, the depletion generation portion Dp is moldless with respect to the normal portion Nm. The presence or absence of depletion is determined by detecting a slight shift in the temperature drop position between the upper thermocouple 24U and the lower thermocouple 24D.
[0023]
Therefore, when pre-determining online the surface quality of the steel slab 15 after ingot rolling at the stage of the slab 5 (B) after water cooling in advance in such a continuous casting process, the slab temperature before pinch roll correction The slab temperature before correction by the pinch roll is measured by the sensor 21, the tank water temperature before water cooling is measured by the water tank water temperature sensor 22, and the slab temperature before water cooling is measured by the water slab temperature sensor 23 before water cooling. The surface quality of the steel slab 15 after split rolling at the stage of the slab 5 (B) after water cooling is recorded online by the surface quality online judgment means 28 from the respective heat history in slab unit. Pre-determine with.
[0024]
In this case, the initial solidification / casting conditions in the mold 4 can be continuously recorded. For example, when the initial solidification / casting conditions in the mold 4 are continuously recorded, the molten steel 2 and the drawing speed (Vc) calculated from the fluctuation of the molten metal surface by the molten metal surface sensor 25 and the rotational speed of the pinch roll 6 can be recorded continuously. The presence / absence of depletion can be continuously recorded by the heat removal fluctuation on the wall surface.
[0025]
And as shown in Table 1, the slab temperature before correction by the pinch roll is an appropriate temperature region A where there is no possibility of cracking in the slab. _M And A on the slab ₃ Transformation point behavior temperature region A in which cracking due to transformation point behavior may occur _H And a ductility deficient temperature region A in which cracking due to insufficient ductility may occur in the slab. _L And record continuously.
[0026]
In addition, as shown in Tables 1 and 2, the water temperature of the water tank before water cooling is an appropriate temperature region A in which there is no possibility that the cooling capacity will be insufficient during the water cooling of the slab. ₁ , A ₂ , A ₆ (Refer to FIG. 3) and a rising temperature region A in which the cooling capacity may be insufficient during the water cooling of the slab. ₃ , A ₄ , A ₅ , A ₁₀ (See FIGS. 3 and 4) and recorded continuously.
[0027]
Furthermore, as shown in Tables 1 and 2, the slab temperature before water cooling is an appropriate temperature region A where there is no risk of cracks occurring on the surface and corners of the slab during water cooling. ₇ (Refer to FIG. 4) and a slightly dangerous temperature region A where there is no risk of cracking in the surface of the slab during water cooling, but there is a risk of cracking in the corner ₈ (Refer to FIG. 4) and dangerous temperature region A where the surface and corners of the slab may crack during water cooling ₉ (See FIG. 4) and recorded continuously.
[0028]
And first, the slab temperature before the correction by the pinch roll is an appropriate temperature region A. _M Next, the temperature of the water tank before water cooling is an appropriate temperature region A where there is no risk of insufficient cooling when the slab is cooled with water. ₁ , A ₂ , A ₆ Next, the temperature of the slab before water cooling is an appropriate temperature region A in which there is no risk of cracks occurring on both the surface and corners of the slab during water cooling. ₇ The surface quality of the steel slab 15 after the ingot rolling in the slab stage after water cooling is preliminarily online online from the above heat history in slab units. Judge in advance.
[0029]
[Table 1]

[0030]
[Table 2]

[0031]
As a result, as shown in Table 1, the slab temperature before correction by the pinch roll 6 is within the proper temperature range A. _M The temperature of the water tank before water cooling is an appropriate temperature region A where there is no fear of insufficient cooling when the slab 5 is cooled with water. ₁ And the slab temperature before water cooling is an appropriate temperature region A where there is no risk of cracks occurring on both the surface and corners of the slab 5 during water cooling. ₇ Since it has been confirmed from the experimental data in advance that no scarfing is required in the steel slab 15 after the block rolling, the slab satisfying the above conditions is a steel slab after the block rolling. Omit scarfing for.
[0032]
In addition, there is no risk of cracking in the surface part of the slab during water cooling, but there is a risk of cracking in the corner part. ₈ Critical temperature region A in which cracks may occur in the slab via the slab and on the surface and corners of the slab during water cooling ₉ About the slab which passed through, the scarfing which is lighter than before is performed with respect to the steel piece after a piece rolling.
[0033]
And the transformation point behavior temperature region A _H Or through ductile undertemperature range A _L For those passing through, the conventional scarfing is performed on the rolled steel slab.
[0034]
Each of these temperature regions varies depending on the steel type, so a judgment table in which the appropriate temperature for each steel type is set for the slab temperature before correction by the pinch roll, the water temperature of the water tank before water cooling, and the slab temperature before water cooling. It is desirable to have it.
[0035]
【Example】
Hereinafter, examples of the present invention will be described more specifically, but it is needless to say that the present invention is not limited to such examples.
[0036]
In this example, mechanical structural steel (chromium steel: JIS SCR420H), which was controlled to have an appropriate amount of Al and N (Al, N control material) to prevent grain coarsening during carburization, was normally treated. About the thing (normal processing material) and the thing (Pb containing material) containing Pb, the continuous casting and the lump rolling were performed, respectively, and the generation | occurrence | production situation of the intergranular crack and the vertical crack in the steel slab was investigated.
[0037]
Therefore, in the continuous casting process shown in FIG. 1, the slab temperature before correction by the pinch roll is measured by the temperature sensor 21 before the pinch roll correction, the water temperature of the tank before water cooling is measured by the water tank water temperature sensor 22, and the casting before water cooling is performed. The slab temperature before water cooling is measured by the slab temperature sensor 23 and continuously recorded, and tracking is performed, and the rolling rolling is performed at the stage of the slab 5 (B) after water cooling from each thermal history in slab unit. The surface quality of the subsequent steel slab 15 was preliminarily determined online by the surface quality online determining means 28.
[0038]
At this time, when continuously recording the initial solidification / casting conditions in the mold 4, the superheat temperature (SH) of the molten steel 2, the fluctuation of the molten metal surface by the molten metal surface sensor 25, and the rotational speed of the pinch roll 6 are used. The calculated drawing speed (Vc) was continuously recorded, and the presence / absence of depletion was continuously recorded due to the heat removal fluctuation on the wall surface of the mold 4.
[0039]
And as shown in Table 1, the slab temperature before correction by the pinch roll is an appropriate temperature region A where there is no possibility of cracking in the slab. _M (In this example, as shown in Table 3, 740-830 ° C.) ₃ Transformation point behavior temperature region A in which cracking due to transformation point behavior may occur _H (In this example, as shown in Table 3, over 830 ° C.) and a ductility deficient temperature region A in which cracking due to insufficient ductility may occur in the slab. _L (In this example, as shown in Table 3, the temperature was less than 740 ° C.) and recorded continuously.
[0040]
In addition, as shown in Tables 1 and 2, the water temperature of the water tank before water cooling is an appropriate temperature region A in which there is no possibility that the cooling capacity will be insufficient upon water cooling of the slab. ₁ , A ₂ , A ₆ (In this embodiment, as shown in Table 3 and FIG. 3, 43 ° C. or lower) and an elevated temperature region A that may cause a lack of cooling capacity during water cooling of the slab ₃ , A ₄ , A ₅ , A ₁₀ (In this example, as shown in Table 3, FIG. 3 and FIG. 4, it was over 43 ° C.) and recorded continuously.
[0041]
Furthermore, as shown in Table 1 and Table 2, the slab temperature before water cooling is an appropriate temperature region A where there is no risk of cracks occurring on the surface and corners of the slab during water cooling. ₇ (In this embodiment, as shown in Table 3 and FIG. 4, it exceeds 820 ° C.) and there is no risk of cracking in the surface part of the slab during water cooling, but there is a risk of cracking in the corner part. Hazardous temperature range A ₈ (In this example, as shown in Table 3 and FIG. 4, 740 to 820 ° C.) and dangerous temperature region A in which cracks may occur in the surface and corners of the slab during water cooling ₉ (In this example, as shown in Table 3 and FIG. 4, it was recorded continuously in a divided manner).
[0042]
And first, the slab temperature before the correction by the pinch roll is an appropriate temperature region A. _M (I.e., 740 to 830 ° C.), and next, the temperature of the water tank before water cooling is an appropriate temperature region A in which there is no fear of insufficient cooling when cooling the slab. ₁ , A ₂ , A ₆ (I.e., 43 ° C. or less), and then the slab temperature before water cooling is an appropriate temperature region A where there is no risk of cracks occurring on both the surface and corners of the slab during water cooling. ₇ (I.e., exceeding 820 ° C.), tracking order of these sequential determinations, and from the above heat history in slab units, the steel slab 15 after split rolling in the slab stage after water cooling in the slab stage The surface quality was previously determined online in advance by the surface quality online determination means 28.
[0043]
[Table 3]

[0044]
As a result, as shown in Table 3, the slab temperature before correction by the pinch roll is in the proper temperature range A. _M (That is, 740 to 830 ° C.) The temperature of the water tank before water cooling is an appropriate temperature region A where there is no fear of insufficient cooling when the slab 5 is cooled with water. ₁ (That is, 43 ° C. or less), and the slab temperature before water cooling is an appropriate temperature region A where there is no risk of cracks occurring on both the surface portion and the corner portion of the slab 5 during water cooling. ₇ (Thus, over 820 ° C.) According to the experimental data shown in Table 3, since no grain boundary cracking or vertical cracking occurs in the steel piece 15 after the block rolling, scarfing is unnecessary. Therefore, the slab satisfying the above conditions omits scarfing on the steel slab after partial rolling.
[0045]
In addition, there is no risk of cracking in the surface part of the slab during water cooling, but there is a risk of cracking in the corner part. ₈ (That is, dangerous temperature region A in which cracks may occur in both the slab through 740 to 820 ° C. and the surface part and corner part of the slab during water cooling. ₉ As for the slab that passed through (that is, less than 740 ° C.), no intergranular cracking or vertical cracking occurred from the experimental data in Table 3, so scarfing is unnecessary for the steel slab after split rolling. Although it was judged that it was important, the steel piece after the piece rolling was scarfed more lightly than before.
[0046]
And the transformation point behavior temperature region A _H (Ie, over 830 ° C.) _L About what passed through (that is, less than 740 degreeC), the scarfing as usual was performed with respect to the steel piece after partial rolling.
[0047]
In addition, since each said temperature range changes also with steel types, it was confirmed that it is desirable to have the determination table which set each temperature range for every steel type.
[0048]
【The invention's effect】
In the method for determining the surface quality of the slab / steel slab in continuous casting / slab rolling according to the present invention, as described in claim 1, the molten steel in the tundish flows down into the mold, and from the lower part of the mold. The slab surface is formed by drawing the slab into a curved shape and correcting the curved slab with a pinch roll to make it into a horizontal state and then cutting the slab into a water-cooled water bath and water cooling. In the continuous casting process that refines the structure of the part, the surface quality of the steel slab after partial rolling at the stage of the slab after water cooling is pre-determined online. The water temperature of the water tank and the slab temperature before water cooling are continuously recorded, and tracking is performed to determine the surface quality of the steel slab after block rolling at the stage of the slab after water cooling from each heat history in the slab unit. Predetermined online Therefore, since it is avoided to carry out the conventional scarfing even on a steel piece for which scarfing is reduced or unnecessary, it is possible to minimize the yield loss accompanying scarfing and to reduce the yield. As a result, it is possible to achieve a remarkable effect that it is possible to realize an improvement in the quality of steel and a further improvement in the surface quality of the steel slab.
[0049]
Further, as described in claim 2, the initial solidification / casting conditions in the mold are continuously recorded so that the initial solidification / casting conditions in the mold are also warned or determined. It has a great effect that it can be added to.
[0050]
In addition, as described in claim 3, when continuously recording the initial solidification / casting conditions in the mold, the overheating temperature, the molten metal surface fluctuation, and the drawing speed are also recorded continuously. By doing so, it is possible to bring about a remarkable effect that it is possible to add these superheating temperature, fluctuation of the molten metal surface, and drawing speed to the warning or determination factors.
[0051]
Furthermore, as described in claim 4, when continuously recording the initial solidification / casting conditions in the mold, the presence / absence of depletion is continuously recorded due to the heat removal fluctuation. As a result, a significant effect is brought about in that the presence or absence of such depletion can be taken into account in the warning or determination factor.
[0052]
Furthermore, as described in claim 5, the slab temperature before correction by the pinch roll is an appropriate temperature region A in which there is no possibility of cracking in the slab. _M And A on the slab ₃ Transformation point behavior temperature region A in which cracking due to transformation point behavior may occur _H And a ductility deficient temperature region A in which cracking due to insufficient ductility may occur in the slab. _L It is possible to determine the steel slab that can make scarfing light or unnecessary at the stage of the slab corresponding to the steel slab. Is brought about.
[0053]
Furthermore, as described in claim 6, the water tank water temperature before water cooling is an appropriate temperature region A in which there is no possibility that the cooling capacity becomes insufficient when the slab is cooled with water. ₁ , A ₂ , A ₆ And rising temperature region A, which may result in insufficient cooling capacity during water cooling of the slab ₃ , A ₄ , A ₅ , A ₁₀ It is possible to determine the steel slab that can make scarfing light or unnecessary at the stage of the slab corresponding to the steel slab. Is brought about.
[0054]
Furthermore, as described in claim 7, the slab temperature before water cooling is an appropriate temperature region A where there is no risk of cracks occurring on both the surface portion and the corner portion of the slab during water cooling. ₇ Although there is no risk of cracking in the surface part of the slab during water cooling, there is a risk of cracking in the corner part. ₈ And a dangerous temperature region A where the surface portion and corner portion of the slab may crack during water cooling. ₉ It is possible to determine the steel slab that can make scarfing light or unnecessary at the stage of the slab corresponding to the steel slab. Is brought about.
[0055]
Further, as described in claim 8, first, the slab temperature before correction by the pinch roll is in an appropriate temperature region A. _M Next, the temperature of the water tank before water cooling is an appropriate temperature region A where there is no risk of insufficient cooling when the slab is cooled with water. ₁ , A ₂ , A ₆ Next, the temperature of the slab before water cooling is an appropriate temperature region A in which there is no risk of cracks occurring on both the surface and corners of the slab during water cooling. ₇ The surface quality of the steel slab after the ingot rolling is pre-determined on-line in the slab stage after water cooling from the above heat history in slab units. By doing so, the occurrence of intergranular cracks and vertical cracks in the steel slab is judged by the condition of the slab temperature before correction> water tank water temperature before water cooling> slab temperature before water cooling, and at the stage of slab steel The great effect is that the surface quality of the piece can be detected.
[0056]
Furthermore, as described in claim 9, the slab temperature before correction by the pinch roll, the water bath water temperature before water cooling, and the appropriate slab temperature before water cooling are set for each steel type. This brings about a remarkable effect that it is possible to perform online quality judgment corresponding to each steel type.
[0057]
According to the apparatus for determining the surface quality of the slab / steel slab in continuous casting / slab rolling according to the present invention, as described in claim 10, the molten steel in the tundish flows down into the mold, The slab is pulled out from the bottom to form a curved shape, and the curved slab is corrected with a pinch roll to be in a horizontal state and then cut, and the cut slab is immersed in a water-cooled water bath and cooled by water. A device that pre-determines on-line the surface quality of a steel slab after partial rolling at the stage of a slab after water cooling in a continuous casting process for refining the structure of the surface part of the slab. A slab temperature sensor before straightening a pinch roll to measure the temperature, a tank water temperature sensor to measure the tank water temperature before water cooling, a water slab temperature sensor to measure the slab temperature before water cooling, and a temperature measurement by each of the sensors. Result Surface quality online judgment means to pre-determine the surface quality of the steel slab after ingot rolling at the stage of the slab after water cooling from each heat history in the slab unit by continuously recording and tracking tracking Because it is provided, it is avoided to carry out scarfing as usual for steel pieces that can reduce or omit scarfing, so the yield loss associated with scarfing should be minimized. As a result, it is possible to achieve a significant effect that it is possible to improve the yield and further improve the quality of the steel slab surface.
[0058]
Further, as described in claim 11, a mold wall surface temperature sensor for measuring a heat removal variation on the mold wall surface is provided, and the surface quality online determination means continuously records the temperature measurement result by the mold wall surface temperature sensor. In addition, it is possible to measure the heat removal fluctuation by tracking online and pre-determining the surface quality of the steel slab after partial rolling at the stage of the slab after water cooling from each heat history in slab unit. It is possible to determine and warn of the occurrence or non-occurrence of depletion (longitudinal crack) due to.
[0059]
In addition, as described in claim 12, the surface quality online determination means determines the appropriate temperature ranges of the slab temperature before correction by the pinch roll, the water temperature of the water tank before water cooling, and the slab temperature before water cooling. By providing the determination table defined for each steel type, a significant effect is brought about that it is possible to perform online surface quality determination corresponding to each steel type.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an embodiment of an apparatus for determining the surface quality of slab / steel slab in continuous casting / slab rolling according to the present invention together with an outline of continuous casting equipment.
FIG. 2 is an explanatory diagram showing the principle of detection of depletion on the inner wall of the mold.
FIG. 3 is a graph illustrating a relationship between a slab (corner) temperature before correction by a pinch roll and an aquarium water temperature measured in an example of the present invention.
FIG. 4 is a graph illustrating the relationship between the water temperature of the aquarium measured in the example of the present invention and the slab temperature before cooling.
[Explanation of symbols]
1 Ladle
2 Molten steel
3 Tundish
4 Mold
5 slab
5 (B) Cut slab
6 Pinch roll
8 Frame cutter
11 Water-cooled water tank
12 Cooling water
13 Heating furnace
14 Rolls of a batch rolling mill
15 Billet
20 Online quality judgment equipment for slab / steel surface quality
21 Pinch roll straightening slab temperature sensor
22 Tank temperature sensor
23 Pre-water-cooled slab temperature sensor
24 Mold wall surface temperature sensor
25 Hot water level sensor
26 Signal converter
27 Depression warning means
28 Surface quality online judgment means

Claims

The molten steel in the tundish flows down into the mold, and the slab is pulled out from the lower part of the mold to form a curved shape, and the curved shaped slab is corrected with a pinch roll to a horizontal state, then cut, and cut. The surface quality of the steel slab after block rolling at the stage of the slab after water cooling is pre-determined online in a continuous casting process where the structure of the slab surface is refined by immersing the piece in a water-cooled water bath and water cooling. When doing so, continuously record the slab temperature before straightening with the pinch roll, the water temperature of the water tank before water cooling, and the slab temperature before water cooling, tracking and organizing each heat history in slab unit after water cooling. A method for determining the surface quality of a slab / steel slab in continuous casting / slab rolling, wherein the surface quality of the slab after ingot rolling is pre-determined online at the slab stage.

The method for determining the surface quality of slab / steel slab in continuous casting / slab rolling according to claim 1, wherein initial solidification / casting conditions in the mold are continuously recorded.

3. The continuous casting / mining according to claim 2, wherein when the initial solidification / casting conditions in the mold are continuously recorded, the superheating temperature, the molten metal surface fluctuation, and the drawing speed are also continuously recorded. Online quality judgment method for slab / steel surface quality in ingot rolling.

4. The continuous casting / mining according to claim 2 or 3, wherein when the initial solidification / casting conditions in the mold are continuously recorded, the presence / absence of depletion is also continuously recorded due to fluctuations in heat removal. Online quality judgment method for slab / steel surface quality in ingot rolling.

Slab temperature before straightening by the pinch rolls, the appropriate temperature region A _M unlikely to cause cracks in the cast piece is produced, transformation behavior temperature region A that may crack due to A ₃ transformation point behavior occurs slab and _H, continuous casting according to any claims 1, characterized in that partitioning continuously recorded on the ductility insufficient temperature region a _L that may crack due to ductility insufficient to generate four to the slab・ On-line determination method for surface quality of slabs and steel slabs in block rolling.

The water temperature of the water tank before water cooling is an appropriate temperature region A ₁ , A ₂ , A ₆ where there is no risk of insufficient cooling capacity when cooling the slab, and an elevated temperature region A where cooling capacity may be insufficient when water cooling the slab. _{_{_{3, a 4, a 5,}}} a 10 and the surface of the slab-steel slab in continuous casting, blooming rolling according to are classified continuously recorded in any one of claims 1 to 5, wherein the Quality online judgment method.

Slab temperature before water cooling, and the appropriate temperature region A ₇ unlikely to cause water cooled during the cracking surface and corners both of the slab is generated, the corner portion although cracking surface of the slab to the water cooling time may not be generated features and somewhat dangerous temperature region a ₈ that may crack occurs that cracks in surface and corners both of the slab is divided and recorded continuously in the danger temperature range a ₉ that may occur cooled during A method for determining the surface quality of a slab / steel slab in continuous casting / slab rolling according to any one of claims 1 to 6.

First it determines whether the slab temperature before the correction by the pinch roll is in the proper temperature range A _M, then no possibility of the appropriate temperature region A of insufficient cooling upon water cooling water cooling before aquarium water temperature cast slab ₁ , A ₂ , A ₆ or not, and then whether the slab temperature before water cooling is in an appropriate temperature region A ₇ where there is no risk of cracks occurring on both the surface and corners of the slab during water cooling It is characterized in that the surface quality of the steel slab after ingot rolling is pre-determined on-line in the slab stage after water cooling from the above-mentioned thermal history in slab units by tracking and organizing these sequential judgments An on-line surface quality determination method for slabs / steel slabs in continuous casting / slab rolling according to claim 1.

The continuous temperature according to any one of claims 1 to 8, wherein an appropriate temperature is set for each steel type in a slab temperature before correction by a pinch roll, a tank water temperature before water cooling, and a slab temperature before water cooling. Online quality judgment method for slab / steel surface quality in casting / slabbing.

The molten steel in the tundish flows down into the mold, and the slab is pulled out from the lower part of the mold to form a curved shape, and the curved shaped slab is corrected with a pinch roll to a horizontal state, then cut, and cut. The surface quality of the steel slab after block rolling at the stage of the slab after water cooling is pre-determined online in a continuous casting process where the structure of the slab surface is refined by immersing the piece in a water-cooled water bath and water cooling. A slab temperature sensor that measures the slab temperature before straightening with a pinch roll, a slab temperature sensor that measures the tank water temperature before water cooling, and a slab temperature before water cooling Steel slab after rolling and rolling at the stage of slab after water cooling from each heat history in slab unit by continuously recording and tracking the temperature measurement result by each sensor The surface quality of Surface quality online determination device of the slab-steel slab in continuous casting, blooming rolling, characterized in that it comprises a pre-determined surface quality online determination means inline.

A mold wall surface temperature sensor that measures the heat removal fluctuation on the mold wall surface is provided, and the surface quality online judgment means continuously records the temperature measurement result by the mold wall surface temperature sensor and arranges the tracking to arrange each heat in the slab unit. The surface quality of the steel slab after the batch rolling is preliminarily determined online from the history at the stage of the slab after water cooling. Surface quality online judgment device.

The surface quality online judgment means is provided with a judgment table in which appropriate temperature regions are determined for each steel type in the slab temperature before correction by the pinch roll, the water temperature of the water tank before water cooling, and the slab temperature before water cooling. An apparatus for determining the surface quality of a slab / steel slab in continuous casting / slab rolling according to claim 10 or 11.