JP3908901B2 - Cooling drum for continuous casting of thin-walled slab, thin-walled slab and its continuous casting method - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、普通鋼、ステンレス鋼、合金鋼、珪素鋼及びその他の鋼や合金、金属の溶湯から、直接、薄肉鋳片を鋳造する、単ドラム式連続鋳造機または双ドラム式連続鋳造機の冷却ドラムの表面構造に関するものである。
【０００２】
【従来の技術】
一対の冷却ドラム（以下「ドラム」ということがある。）を備えた双ドラム式連続鋳造装置、または、一個の冷却ドラムを備えた単ドラム式連続鋳造装置により、板厚１〜１０ｍｍの薄肉鋳片（以下「鋳片」ということがある。）を連続鋳造する技術が開発されている。
【０００３】
この技術は、最終製品に近い形状と肉厚の薄肉鋳片を製造するものであるから、歩留り良く、所要レベルの品質を有する最終製品を最終的に得るために、該技術に対しては、割れや亀裂等の表面欠陥が皆無の薄肉鋳片を製造することが不可欠のこととして要求される。
この表面欠陥は、薄肉鋳片を鋳造する際、冷却ドラムの表面における凝固シェルの生成が一様でないこと、即ち、溶湯の急冷凝固の態様が一様でないことに起因して生じる熱収縮応力の不均衡に基づいて形成されることが知られていて、これまで、この熱収縮応力の不均衡が鋳片内部に極力残らないように溶湯を冷却、凝固せしめる冷却ドラムの周面構造が種々提案されている。
【０００４】
例えば、特開平４−２３８６５１号公報には、周面に５０〜２００μｍの深さの窪みを１５〜３０％の面積率で形成するとともに、１０〜５０μｍの深さの窪みを４０〜６０％の面積率で形成した連続鋳造用の冷却ドラムが開示されている。また、特開平６−３２８２０４号公報には、周面に直径１００〜３００μｍ、深さ１００〜５００μｍの窪みを１５〜５０％の面積率で形成するとともに、直径４００〜１０００μｍ、深さ１０〜１００μｍ、周面の接線に対し垂直な線と窪みの側面とのなす角度が４５〜７５°の窪みを４０〜６０％の面積率で形成した連続鋳造用の冷却ドラムが開示されている。
【０００５】
そして、これらの冷却ドラムは、鋳片表面における表面割れや亀裂の発生を抑制するとともに、もう一方の代表的な表面欠陥である酸洗むらの発生を抑制するもので、光沢むらのないステンレス鋼薄板製品を製造する上において、顕著な効果を奏するものである。
また、特開平１１−１７９４９４号公報には、周面に多数の突起（好ましくは、高さ２０μｍ以上、直径０．２〜１．０ｍｍ、最近接間隔０．２〜１．０ｍｍ）を形成した連続鋳造用の冷却ドラムが開示されている。この冷却ドラムは、薄肉鋳片の連続鋳造において、表面欠陥を皆無に近い状態にまで抑制できるものである。
【０００６】
このように、板厚１〜１０ｍｍの薄肉鋳片を連続鋳造する技術においては、冷却ドラムの周面構造を改善・工夫することにより、酸洗むらを含む表面欠陥の発生を抑制するのに、大きな成功を納めている。
しかしながら、操業中、冷却ドラムとその両側に当接するサイド堰で形成される溶鋼を受容する湯溜まり部を不活性雰囲気で包囲し、スカムの生成をできるだけ抑制しても、溶鋼の内部から、介在物や混入したスラグが浮上したりして、相当量のスカムが、溶鋼表面上に浮遊し、凝集することは避けられない。そして、このスカムが冷却ドラムと溶鋼の間に巻き込まれて、薄肉鋳片の表面に酸洗むらが発現する。
【０００７】
この酸洗むらの部分は、最終薄板製品においては、光沢むらとして発現し、製品素材としての価値を低めるから、最終薄板製品の品質と歩留りを、さらに高めるためには、薄肉鋳片を連続鋳造する際、スカムの生成を極力抑制することに加え、スカムが巻き込まれても、薄肉鋳片に酸洗むらが発生するのを極力抑制できる、できれば該発生を皆無にする、何らかの対策が必要である。
【０００８】
そこで、本発明者は、その対策を探るべく、酸洗むらが発現した薄肉鋳片ついて詳細に調査した。その結果、本発明者は、酸洗むらが発現した領域とそうでない領域との境界近傍に、従前知られている表面割れとは形態の異なる“割れ”が発生しているのを発見した。この“割れ”（以下「酸洗むら付随割れ」という。）を、図１に示す。
【０００９】
図１から分かるように、“酸洗むら付随割れ”は、酸洗むらの発生していない部位で発生する表面割れ（以下「ディンプル割れ」ということがある。）とは、当然に、割れの起源、位置、形態等の点で異質なものである。
したがって、これまでの手段では、上記異質な“酸洗むら付随割れ”を防止することは困難である。
【００１０】
このように、薄肉鋳片の連続鋳造においては、“ディンプル割れ”及び“酸洗むら”の発生を抑制するという課題の他に、これらとは異質の“酸洗むら付随割れ”の発生を抑制するという課題を、新たに抱えることになった。
【００１１】
【発明が解決しようとする課題】
そこで、本発明は、薄肉鋳片の連続鋳造において、“ディンプル割れ”の発生を抑制するとともに、“酸洗むら”及び“酸洗むら付随割れ”の発生を抑制することを課題とし、該課題を、溶鋼の凝固態様に大きく影響する冷却ドラムの周面構造の点から解決することを目的とするものである。
【００１２】
【課題を解決するための手段】
酸洗むらは、スカムが付着した部位の溶鋼の凝固が遅くれ、その結果、スカム付着部の凝固組織が、その周辺の凝固組織と異なるものになることに起因して、酸洗後、鋳片表面に“むら”として発現したものであるから、冷却ドラムの表面上での溶鋼の凝固態様が、“酸洗むら付随割れ”の発生にも、大きく関与しているものと推測される。
【００１３】
そこで、本発明者は、まず、図１に示すような“酸洗むら付随割れ”が発生した薄肉鋳片の凝固態様について調査したところ、“酸洗むら付随割れ”は、基本的には、スカムの流入、付着によって、冷却ドラムと溶鋼との界面における熱抵抗が変化し、スカムが付着した部位とそうでない部位とで、形成される凝固シェルの厚さに差が生じることに起因するものであるところ、具体的には、凝固シェル厚の不均一度が２０％を超える部位で発生していることが判明した。
【００１４】
図２に、その発生機構を模式的に示す。スカム１が付着した部位では、冷却ドラム１０と溶鋼９との界面における熱抵抗が変化し、溶鋼の凝固が遅れるので、凝固シェル２の厚さは、他の部位における凝固シェルの厚さより薄いものとなるが、スカム１とディンプル３の凹面との間に形成されるガスギャップ４との相乗作用により、厚い凝固シェルと薄い凝固シェルとの境界部（凝固シェル厚の不均一部分）に、“歪み”が発生し、蓄積される。そして、この凝固シェル厚の不均一度が、２０％を超えると、図２に示すように、上記境界部で、“酸洗むら付随割れ５”が発生する。
【００１５】
上記のように、“酸洗むら付随割れ５”の原因となる“歪み”の発生、蓄積には、スカム１とディンプル３の凹部との間に形成されるガスギャップ４の存在も関連しているので、本発明者は、さらに、ディンプルの“深さ”を変えることにより溶鋼の凝固態様を変化させ、凝固態様の変化（この変化を示す指標として、“ディンプル深さ”を用いた。）と、“ディンプル割れ”及び“酸洗むら付随割れ”の発生状況（発生状況を示す指標として、“割れ長さ”を用いた。）との関連性を調査した。
【００１６】
その結果を、図３に示す。この図によれば、ディンプル深さ（μｍ）を深くすれば、“酸洗むら付随割れ”の発生を防止できるが、逆に、“ディンプル割れ”の発生を助長することが分かる。
このように、本発明者は、“ディンプル割れ”と“酸洗むら付随割れ”の発生もしくは発生抑制は、冷却ドラムの周面に形成したディンプルの深さとの関係でみると、トレードオフの関係にあることを見いだした。
【００１７】
ここで、図４に、“ディンプル割れ”の発生機構を模式的に示す。ディンプル３の頂部に当接した溶鋼部位に凝固核が生成し（図中「６」参照）、ここから凝固が進行するが、ディンプル３の凹部に侵入して形成される溶鋼の凸部７が凝固するとき、凝固はディンプル単位で比べると不均一であり、この不均一に起因して、ディンプル単位毎に不均一応力・歪みが蓄積される。そして、この不均一応力・歪みが原因となって、“ディンプル割れ８”が発生する。
【００１８】
溶鋼の凸部７が凝固するとき、スカム１が付着した部位では、スカムが熱抵抗となり、当然に凝固が遅れるが、この場合、凝固の遅れにより、上記不均一応力・歪みが緩和される。
以上の調査結果から得られた知見をまとめると、以下のとおりである。
（ａ）溶鋼は、ディンプルの頂部に接触するが、その底部には接触しないか、接触しても一部分である。
（ｂ）ディンプルの頂部に接触した溶鋼は、頂部に非接触の溶鋼より速く凝固する。
（ｃ）ディンプルの底部に接触しない溶鋼においては、核生成が遅れて、凝固が遅れる。
（ｄ）溶鋼の凝固は、ディンプル単位で比べると不均一であり、この不均一に起因する不均一応力・歪みが、ディンプル単位毎に蓄積される。これが、“ディンプル割れ”の原因となる。
（ｅ）スカムが付着した溶鋼では凝固が遅れ、そうでない溶鋼の凝固部分との境界に、不均一応力・歪みが蓄積される。これが、“酸洗むら付随割れ”の原因となる。
（ｆ）“ディンプル深さ”さが深ければ、スカム付着による溶鋼の凝固遅れで生じる不均一応力・歪みの蓄積は緩和されるが、逆に、ディンプル単位毎の不均一応力・歪みの蓄積が助長され、“ディンプル割れ”が頻発する。
【００１９】
“ディンプル割れ”と“酸洗むら付随割れ”が、いずれも冷却ドラム表面での“溶鋼の凝固態様”と密接に関連していることは明らかであるところ、本発明者は、これらの知見に基づき、ディンプルの形態において、まず、“酸洗むら”及び“酸洗むら付随割れ”の発生を抑制するのに充分な“ディンプル深さ”を確保し、この“ディンプル深さ”を前提に、ディンプルの表面に、
（ｘ）頂部に当接した溶鋼の凝固を遅らせ、かつ、
（ｙ）底部に当接した溶鋼の凝固を促進する、
機能を付与すれば、ディンプル単位毎に発生、蓄積する不均一応力・歪みを低減することができ、“酸洗むら付随割れ”の発生と“ディンプル割れ”の発生の両方を抑制できるのではないかとの発想に至った。
【００２０】
そして、本発明者は、上記発想の下において、冷却ドラムの周面に形成するディンプルにおいて、上記（ｘ）及び（ｙ）の機能を果たす表面形態について、種々調査した。その結果、ディンプルの頂部に、所定形状の“丸み”をつけるか、もしくは、所定形状の“細孔”を形成すると、ディンプルの頂部に当接した溶鋼の凝固を遅らせることができることを知見した。
【００２１】
また、ディンプルの頂部に“丸み”をつけたり、“細孔”を形成したりすると、溶鋼は、溶鋼の静圧や冷却ドラムの圧下力の下で、容易にディンプルの底部に当接し、発生した凝固核を起点にして凝固するが、ディンプルの底部に、所定形状の“微小突起”、“細孔”または“微小凹凸”を形成しておくと、凝固核の発生が促進されて、溶鋼の凝固がより速く進行することを知見した。
【００２２】
本発明は、以上の知見に基づき、さらにディンプルの形状と、ディンプルの頂部に形成する“丸み”や“細孔”の形状、また、ディンプルの底部に形成する“微小突起”、“細孔”もしくは“微小凹凸”の形状との好ましい関係を確認してなされたものである。
そして、薄肉鋳片連続鋳造用冷却ドラムに係る発明の要旨は、以下のとおりである。
（１）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの表面に、窪みの平均深さよりも小さい高さの微小突起であって、高さが１〜５０μｍ、円相当の径が５〜２００μｍの微小突起が形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（２）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの表面に、深さが５μｍ以上１５０μｍ以下、円相当の径が５〜２００μｍの細孔が形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（３）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの表面に、平均深さが１〜５０μｍ、円相当の径が１０〜２００μｍの微細凹凸が８０〜２５０μｍの間隔で形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（４）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの頂部に、高さが１〜５０μｍ、円相当の径が３０〜２００μｍの微小突起が隣接して形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（５）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの頂部に、高さが１〜５０μｍ、円相当の径が３０〜２００μｍの微小突起が隣接して形成され、かつ、窪みの表面に、窪みの平均深さよりも小さい高さの微小突起であって、高さが１〜５０μｍで、円相当の径が５〜２００μｍの微小突起が形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（６）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの頂部に、高さが１〜５０μｍ、円相当の径が３０〜２００μｍの微小突起が隣接して形成され、かつ、窪みの表面に、深さが５μｍ以上１５０μｍ以下、円相当の径が５〜２００μｍの細孔が形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（７）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの頂部に、高さが１〜５０μｍ、円相当の径が３０〜２００μｍの微小突起が隣接して形成され、かつ、窪みの表面に、平均深さが１〜５０μｍ、円相当の径が１０〜２００μｍの微細凹凸が８０〜２５０μｍの間隔で形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（８）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの頂部に、深さが５μｍ以上１５０μｍ以下、円相当の径が５〜２００μｍの細孔が形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（９）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの頂部に、深さが５μｍ以上１５０μｍ以下、円相当の径が５〜２００μｍの細孔が形成され、かつ、窪みの表面に、窪みの平均深さよりも小さい高さの微小突起であって、高さが１〜５０μｍで、円相当の径が５〜２００μｍの微小突起が形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（10）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの頂部及び表面に、深さが５μｍ以上１５０μｍ以下、円相当の径が５〜２００μｍの細孔が形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
（11）薄肉鋳片を連続鋳造する冷却ドラムであって、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されているとともに、窪みの頂部に、深さが５μｍ以上１５０μｍ以下、円相当の径が５〜２００μｍの細孔が形成され、かつ、窪みの表面に、平均深さが１〜５０μｍ、円相当の径が１０〜２００μｍの微細凹凸が８０〜２５０μｍの間隔で形成されていることを特徴とする薄肉鋳片連続鋳造用冷却ドラム。
【００２３】
また、前記（１）〜（11）のいずれかに記載の薄肉鋳片連続鋳造用冷却ドラムを用いる連続鋳造方法に係る発明の要旨は、以下のとおりである。
（12）一方向に回転する、前記（１）〜（11）のいずれかに記載の薄肉鋳片連続鋳造用冷却ドラムの周面上に溶鋼を注入し、該溶鋼を該冷却ドラムの周面で冷却、凝固させ、薄肉鋳片を連続鋳造することを特徴とする薄肉鋳片の連続鋳造方法。
（13）平行に配置され互いに逆方向に回転する一対の、前記（１）〜（11）のいずれかに記載の薄肉鋳片連続鋳造用冷却ドラムの周面の一部に湯溜り部を形成し、該湯溜り部に注入した溶鋼を、該冷却ドラムの周面で冷却、凝固させ、薄肉鋳片を連続鋳造することを特徴とする薄肉鋳片の連続鋳造方法。
【００２４】
さらに、前記（１）〜（11）のいずれかに記載の薄肉鋳片連続鋳造用冷却ドラムを用いて溶鋼を連続鋳造した薄肉鋳片に係る発明の要旨は、以下のとおりである。
（14）前記（１）〜（11）のいずれかに記載の薄肉鋳片連続鋳造用冷却ドラムを用いて溶鋼を連続鋳造した薄肉鋳片であって、溶鋼が、該冷却ドラムの周面上の窪みの頂部に当接した溶鋼部位で生成した凝固核発生起点を起点にして凝固を開始し、次いで、上記窪みの表面上の微小突起、細孔または微細凹凸に当接した溶鋼部位で生成した凝固核発生起点を起点にして凝固したことを特徴とする薄肉鋳片。
（15）前記窪みの頂部に当接する溶鋼部位で生成した凝固核発生起点は、円相当の径で０．５〜３ｍｍの環状に生成したものであることを特徴とする前記（14）に記載の薄肉鋳片。
（16）前記微小突起、細孔または微細凹凸に当接した溶鋼部位で生成した凝固核発生起点は、２５０μｍ以下の間隔で生成したものであることを特徴とする前記（14）または（15）に記載の薄肉鋳片。
（17）前記（１）〜（11）のいずれかに記載の薄肉鋳片連続鋳造用冷却ドラムを用いて溶鋼を連続鋳造した薄肉鋳片であって、該薄肉鋳片の表面には、溶鋼が該冷却ドラムの周面上の窪みの頂部に当接して凝固したことにより形成された網状の連続凹みが存在するとともに、該網状の連続凹みで区画されたそれぞれの領域の内には、微小な凹み及び／または微小な突起が存在することを特徴とする薄肉鋳片。
（18）前記網状の連続凹みで区画されたそれぞれの領域は、円相当の径で０．５〜３ｍｍの領域であることを特徴とする前記（17）に記載の薄肉鋳片。
（19）前記網状の連続凹みで区画されたそれぞれの領域の内には、微小な凹み及び／または微小な突起が、２５０μｍ以下の間隔で存在することを特徴とする前記（17）または（18）に記載の薄肉鋳片。
（20）前記網状の連続凹みの底部に、微小な凹み及び／または微小な突起が存在することを特徴とする前記（17）、（18）または（19）に記載の薄肉鋳片。
（21）前記（１）〜（11）のいずれかに記載の薄肉鋳片連続鋳造用冷却ドラムを用いて溶鋼を連続鋳造した薄肉鋳片であって、溶鋼が該冷却ドラムの周面上の窪みの頂部に当接した溶鋼部位に形成された網状の連続凹みに沿って生成した凝固核発生起点を起点にして、該網状の連続凹みの形状を保持したまま凝固を開始し、次いで、上記窪みの表面上の微小突起、細孔または微細凹凸に当接した溶鋼部位で生成した凝固核発生起点を起点にして凝固したことを特徴とする薄肉鋳片。
（22）前記網状の連続凹みで区画されたそれぞれの領域は、円相当の径で０．５〜３ｍｍの領域であることを特徴とする前記（21）に記載の薄肉鋳片。
（23）前記微小突起、細孔または微細凹凸に当接した溶鋼部位で生成した凝固核発生起点は、２５０μｍ以下の間隔で生成したものであることを特徴とする前記（21）または（22）に記載の薄肉鋳片。
【００２５】
【発明の実施の形態】
本発明について、さらに詳細に説明する。
本発明は、周面に、所定形状の窪みが、窪みの頂部を介して相互に隣接して形成されている冷却ドラムにおいて、ディンプル（窪み）の頂部及び／またはディンプル（窪み）の表面に、微小突起、細孔または微細凹凸を形成することを基本的な技術思想とする。
【００２６】
これは、前記知見に従い、ディンプルの頂部に、微小突起または細孔を形成することにより、溶鋼の凝固を遅らせる機能を付与し、また、ディンプルの表面に、微小突起、細孔または微細凹凸を形成することにより、溶鋼の凝固を促進する機能を付与したものである。
ディンプルを形成したままのディンプルの頂部は、鋭角的な形状をなしているが、該頂部に、多数の微小突起を形成すると、該微小突起は、狭い鋭角的形状の頂部で相互に連続した態様で形成されるので、ディンプルの頂部は“丸み”を帯びることになる。
【００２７】
上記“丸み”を帯びたディンプル頂部は、該頂部に当接した溶鋼における凝固核の生成を遅延せしめ、溶鋼の凝固の進行を遅くらせる作用をなす。また、上記“丸み”を帯びた頂部は、ディンプルの底部に溶鋼が侵入するのを促進する作用をなす。その結果、溶鋼は、溶鋼の静圧や冷却ドラムの圧下力の下で、容易にディンプルの底部に当接することになる。
【００２８】
鋭角的な形状のディンプル頂部に細孔を形成すると、該鋭角的な形状が消滅するとともに、ガスを保持する緩冷却部が形成されるので、“細孔”を有するディンプル頂部は、該頂部に当接した溶鋼における凝固核の生成を遅延せしめ、溶鋼の凝固の進行を遅くらせる作用をなす。
また、ディンプル頂部における細孔の存在により、ディンプルの底部に溶鋼が侵入するのが促進され、同様に、溶鋼の静圧や冷却ドラムの圧下力の下で、容易にディンプルの底部に当接することになる。
【００２９】
なお、ディンプルの頂部に、微小凹凸を形成すると、上記“丸み”の機能と、上記“細孔”の機能を併せ持つことになる。
一方、ディンプルの底部表面に形成した“微小突起”、“細孔”または“微細凹凸”は、該表面に当接した溶鋼における凝固核の生成を促進し、溶鋼の凝固を促進する作用をなす。
【００３０】
このように、本発明の薄肉鋳片連続鋳造用冷却ドラム（以下「本発明の冷却ドラム」という。）は、“酸洗むら”及び“酸洗むら付随割れ”の発生を抑制するのに充分な“ディンプル深さ”を確保したうえ、ディンプルの頂部においては、溶鋼の凝固を遅らせるとともに、ディンプル底部への溶鋼の侵入を促進し、かつ、ディンプルの底部表面においては、侵入して該表面に当接した溶鋼の凝固を促進する機能を有するものである。
【００３１】
したがって、本発明の冷却ドラムにおいては、冷却ドラム周面上での凝固の態様が均一化されているから、従来、ディンプルの単位毎に発生し、蓄積される不均一応力・歪み（“ディンプル割れ”の原因となる。）は低減されることになる。
また、本発明の冷却ドラムにおいては、かりに、冷却ドラムと溶鋼との間にスカムが巻き込まれ、スカムが付着した溶鋼部分の凝固が遅れ、スカム付着部位で、薄い凝固シェルが形成されたとしても、凝固シェル厚の不均一度は２０％以下に抑制されるから、凝固シェル厚の不均一部分に発生し、蓄積される“歪み”（“酸洗むら付随割れ”の原因となる。）は低減されることになる。
【００３２】
本発明の冷却ドラムにおいては、その周面に、平均深さが４０〜２００μｍ、円相当の径が０．５〜３ｍｍの窪みが、窪みの頂部を介して相互に隣接して形成されていることが好ましい。
窪み（ディンプル）の平均深さが４０μｍ未満であると、ディンプルによるマクロな応力・歪みの緩和効果が得られないので、下限は４０μｍとする。一方、窪み（ディンプル）の平均深さが２００μｍを超えると、ディンプル底部への溶鋼の侵入が不充分となるので、上限は２００μｍとする。
【００３３】
窪みの大きさは、円相当の径で０．５〜３ｍｍが好ましい。この径が０．５ｍｍ未満であると、ディンプル底部への溶鋼の侵入が不充分となるので、下限は０．５ｍｍとする。一方、円相当の径が３ｍｍを超えると、ディンプル単位での応力・歪みの蓄積が多くなり、ディンプル割れが発生し易くなるので、上限は３ｍｍとする。
【００３４】
そして、上記形状の窪みの表面に、所要形状の“微小突起”、“細孔”または“微細凹凸”を形成するのが好ましい。以下、それらの所要形状について説明する。
（ａ）微小突起
上記形状の窪みの表面に、高さが１〜５０μｍ、円相当の径が５〜２００μｍの微小突起を形成する。
【００３５】
高さが１μｍ未満であると、突起が溶鋼と充分に接触することができず、凝固核の生成が起こらないので、下限は１μｍとする。一方、高さが５０μｍを超えると、突起底部での溶鋼の凝固が遅れ、窪み内での凝固シェルの不均一が発生するので、上限は５０μｍとする。
また、円相当の径が５μｍ未満であると、突起での冷却が不充分となり、凝固核の生成が起こらないので、下限は５μｍとする。一方、円相当の径が２００μｍを超えると、突起への溶鋼の接触が不充分な部位が発生し、凝固核の生成が不均一となるので、上限は２００μｍとする。
（ｂ）細孔
上記形状の窪みの表面に、深さが５μｍ以上、円相当の径が５〜２００μｍの細孔を形成する。
【００３６】
深さが５μｍ未満であると、細孔部でのエアギャップの生成が不充分となり、細孔部以外の窪み表面での確実な凝固核の生成を達成できないので、下限は５μｍとする。
また、円相当の径が５μｍ未満であると、細孔部での冷却緩和効果が充分に発揮されず、凝固核の発生を細孔部以外の窪み表面に限定できないので、下限は５μｍとする。一方、円相当の径が２００μｍを超えると、細孔部にまで溶鋼が侵入し、侵入した溶鋼が凝固して凝固シェルを拘束し、歪の集中を起こし割れの発生を助長するので、上限は２００μｍとする。
（ｃ）微細凹凸
上記形状の窪みの表面に、平均深さが１〜５０μｍ、円相当の径が１０〜２００μｍの微細凹凸を形成する。
【００３７】
平均深さが１μｍ未満であると、凹凸部での凝固核の生成が起こらないので、下限は１μｍとする。一方、平均深さが５０μｍを超えると、凹凸底部での凝固が遅れ、窪み内での凝固シェルの不均一が発生するので、上限は５０μｍとする。
また、円相当の径が１０μｍ未満であると、凹凸部での凝固核の生成が起こらないので、下限は１０μｍとする。一方、円相当の径が２００μｍを超えると、凹凸部への溶鋼の接触が不充分な部位が発生し、凝固核の生成が不均一となるので、上限は２００μｍとする。
【００３８】
さらに、本発明の冷却ドラムにおいては、その周面に、窪みの頂部を介して相互に隣接して形成した“平均深さが４０〜２００μｍで、円相当の径が０．５〜３ｍｍの窪み”の頂部に、所要形状の微小突起を隣接して形成して、該頂部に“丸み”をつけるか、もしくは、所要形状の“細孔”を形成するのが好ましい。それらの所要形状について説明する。
（ｄ）微小突起
上記形状の窪みの頂部に、高さが１〜５０μｍ、円相当の径が３０〜２００μｍの微小突起を隣接して形成する。
【００３９】
高さが１μｍ未満であると、ティンプル頂上部での凝固核生成の遅延効果が得られないので、下限は１μｍとする。一方、高さが５０μｍを超えると、ディンプル底部への溶鋼の侵入が不充分となるので、上限は５０μｍとする。
また、円相当の径が３０μｍ未満であると、ディンプル頂上部での凝固核生成の遅延効果が得られないので、下限は３０μｍとする。一方、円相当の径が２００μｍを超えると、ディンプルによる応力・歪みの緩和効果が得られないので、上限は２００μｍとする。
（ｅ）細孔
上記形状の窪みの頂部に、深さが５μｍ以上、円相当の径が５〜２００μｍの細孔を形成する。
【００４０】
深さが５μｍ未満であると、細孔部でのエアギャップの形成が不充分となり、凝固核生成の遅延効果が得られないので、下限は５μｍとする。
また、円相当の径が５μｍ未満であると、細孔部以外の頂上近傍で凝固核が生成し、ディンプル底部への溶鋼の侵入促進効果が得られないので、下限は５μｍとする。一方、円相当の径が２００μｍを超えると、ディンプル頂上部の高さが見かけ上低くなり、応力・歪みの緩和効果が得られないので、上限は２００μｍとする。
【００４１】
本発明においては、鋼種や、所望の板厚、品質に応じ、上記（ａ）〜（ｅ）の微小突起、細孔及び微細凹凸を、適宜、組み合わせて、冷却ドラムの周面構造を構成することができる。
そして、本発明の冷却ドラムは、単ロール式の連続鋳造、及び、双ロール式の連続鋳造のいずれにも使用することができる。
【００４２】
次に、本発明の冷却ドラムを用い、単ロール式の連続鋳造、及び、双ロール式の連続鋳造のいずれかで連続鋳造した薄肉鋳片について説明する。
本発明の薄肉鋳片は、基本的には、溶鋼が、冷却ドラムの周面上の窪みの頂部に当接した溶鋼部位で生成した凝固核発生起点を起点にして凝固を開始し、次いで、上記窪みの表面上の微小突起、細孔または微細凹凸に当接した溶鋼部位で生成した凝固核発生起点を起点にして凝固したものである。
【００４３】
ここで、冷却ドラムの周面上の窪みの円相当の径が０．５〜３ｍｍであると、該窪みの頂部に当接した溶鋼部位では、凝固核発生起点が、該頂部に沿い、即ち、円相当の径で０．５〜３ｍｍの環状に生成する。
窪みの表面上の微小突起、細孔または微細凹凸に当接した溶鋼部位で生成する凝固核発生起点は、２５０μｍ以下の間隔で生成せしめることが好ましい。
【００４４】
即ち、上記窪みの表面には、円相当の径の上限が２００μｍの微小突起、細孔または微細凹凸を、２５０μｍ以下の間隔で形成し、上記凝固核発生起点の生成を促進することが好ましい。
本発明の薄肉鋳片においては、溶鋼が、冷却ドラムの周面上の窪みの“頂部”及び“底部表面”に当接して凝固することにより、その表面に、“網状の連続凹み”が形成されるとともに、該“網状の連続凹み”で区画されたそれぞれの領域の内に、“微小な凹み”及び／または“微小な突起”が形成されることがある。
【００４５】
上記“微小な凹み”及び／または“微小な突起”は、本発明の冷却ドラムの周面上の窪みの頂部に、“細孔”もしくは“微細凹凸”を形成した場合に、それらに対応して、薄肉鋳片の表面上に形成されるものである。
本発明の冷却ドラムの周面上の窪みの円相当の径が０．５〜３ｍｍであると、上記“網状の連続凹み”で区画されたそれぞれの領域は、該窪みの円相当の径に相応して、円相当の径で０．５〜３ｍｍの領域となる。
【００４６】
そして、また、上記網状の連続凹みで区画されたそれぞれの領域の内には、冷却ドラムの窪みの表面上の微小突起、細孔または微細凹凸に当接して“微小な凹み”及び／または“微小な突起”が形成される。この“微小な凹み”及び／または“微小な突起”は、２５０μｍ以下の間隔で存在することが好ましい。
本発明の薄肉鋳片は、最も好ましくは、溶鋼が、冷却ドラムの周面上の窪みの頂部に当接した溶鋼部位に形成された網状の連続凹みに沿って生成した凝固核発生起点を起点にして、該網状の連続凹みの形状を保持したまま凝固を開始し、次いで、上記窪みの表面上の微小突起、細孔または微細凹凸に当接した溶鋼部位で生成した凝固核発生起点を起点として凝固したものである。
【００４７】
さらに、好ましくは、上記薄肉鋳片において、上記網状の連続凹みで区画されたそれぞれの領域が、円相当の径で０．５〜３ｍｍの領域であり、及び／または、上記微小突起、細孔または微細凹凸に当接した溶鋼部位で生成した凝固核発生起点が、２５０μｍ以下の間隔で生成したものである。
以下、本発明の実施例について説明するが、本発明は、実施例で用いた冷却ドラムの周面構造、連続鋳造条件、及び、これら周面構造及び連続鋳造条件で得られた薄肉鋳片の形状・構造に限定されるものではない。
【００４８】
【実施例】
ＳＵＳ３０４系ステンレス鋼を示す双ドラム式連続鋳造機により、板厚３ｍｍの帯状薄肉鋳片を鋳造し、その後、該鋳片を冷間圧延して、板厚０．５ｍｍの薄板製品を製造した。上記帯状薄肉鋳片を鋳造するに際し、幅１３３０ｍｍ、直径１２００ｍｍの冷却ドラムの周面を、表１に示す条件で加工した。なお、表１において、“窪み”は、ショットブラストで加工したものである。
【００４９】
最終的に得られた薄板製品の表面品質は、表１、表２（表１の続き）及び表３（表２の続き）に示すとおりである。
なお、割れ・光沢むらは、薄肉鋳片を冷間圧延及び酸洗焼鈍した後に、肉眼観察により判定し、組織は、鋳片表面を研磨・エッチングした後、顕微鏡観察により判定し、表面の凹凸は、３次元粗度計で測定した。
【００５０】
【表１】
【表２】
【表３】
【発明の効果】
本発明によれば、表面割れ、亀裂等の表面欠陥や、酸洗むらに加え、酸洗むら付随割れのない薄肉鋳片を能率よく製造することができる。
したがって、本発明は、表面性状に優れ、かつ、光沢むらのない高品質のステンレス鋼薄鋼板を、歩留り良く安価に提供することができ、ステンレス鋼を、製品素材や、建材として使用する消費財製造業や、建築業等の発展に大きく寄与するものである。
【図面の簡単な説明】
【図１】連続鋳造した薄肉鋳片の表面に発現した“酸洗むら”と“酸洗むら付随割れ”の態様を示す図である。
【図２】図１に示す“酸洗むら付随割れ”の発生機構を模式的に示す図である。
【図３】“ディンプル深さ”（凝固態様）と、“ディンプル割れ”及び“酸洗むら付随割れ”の“割れ長さ”（発生状況）との関連性を示す図である。
【図４】“ディンプル割れ”の発生機構を模式的に示す図である。
【符号の説明】
１…スカム
２…凝固シェル
３…ディンプル
４…ガスギャップ
５…酸洗むら付随割れ
６…凝固核生成
７…溶鋼の凸部
８…ディンプル割れ
９…溶鋼
１０…冷却ドラム[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-drum continuous casting machine or a twin-drum continuous casting machine that casts a thin-walled slab directly from ordinary steel, stainless steel, alloy steel, silicon steel and other steels, alloys, and molten metal. The present invention relates to the surface structure of the cooling drum.
[0002]
[Prior art]
Thin-wall casting with a plate thickness of 1 to 10 mm by a twin-drum continuous casting apparatus equipped with a pair of cooling drums (hereinafter also referred to as “drums”) or a single-drum continuous casting apparatus equipped with a single cooling drum. A technique for continuously casting a piece (hereinafter sometimes referred to as “slab”) has been developed.
[0003]
Since this technique produces a thin cast slab having a shape and thickness close to that of the final product, in order to finally obtain a final product with a high yield and a required level of quality, It is essential to produce a thin cast slab having no surface defects such as cracks and cracks.
This surface defect is caused by heat shrinkage stress caused by non-uniform formation of solidified shells on the surface of the cooling drum when casting a thin slab, that is, the form of rapid solidification of the molten metal. It has been known that it is formed on the basis of imbalance, and various proposals have been made on the peripheral structure of the cooling drum that cools and solidifies the molten metal so that this imbalance of heat shrinkage stress does not remain inside the slab as much as possible. Has been.
[0004]
For example, in JP-A-4-238651, a recess having a depth of 50 to 200 μm is formed on the peripheral surface at an area ratio of 15 to 30%, and a recess having a depth of 10 to 50 μm is formed to 40 to 60%. A cooling drum for continuous casting formed with an area ratio is disclosed. Japanese Patent Application Laid-Open No. 6-328204 discloses a recess having a diameter of 100 to 300 μm and a depth of 100 to 500 μm formed on the peripheral surface with an area ratio of 15 to 50%, and a diameter of 400 to 1000 μm and a depth of 10 to 100 μm. A cooling drum for continuous casting is disclosed in which a depression having an angle of 45 to 75 ° formed by a line perpendicular to the tangential line of the peripheral surface and a side surface of the depression is formed at an area ratio of 40 to 60%.
[0005]
These cooling drums suppress the occurrence of surface cracks and cracks on the surface of the slab, and also suppress the occurrence of pickling unevenness, which is another typical surface defect. In producing a thin plate product, there is a remarkable effect.
In JP-A-11-179494, a large number of protrusions (preferably a height of 20 μm or more, a diameter of 0.2 to 1.0 mm, and a closest interval of 0.2 to 1.0 mm) are formed on the peripheral surface. A cooling drum for continuous casting is disclosed. This cooling drum can suppress surface defects to almost none in continuous casting of thin cast slabs.
[0006]
Thus, in the technique of continuously casting thin cast pieces having a thickness of 1 to 10 mm, by improving and devising the peripheral structure of the cooling drum, to suppress the occurrence of surface defects including pickling unevenness, With great success.
However, during operation, even if the hot water reservoir that receives the molten steel formed by the cooling drum and the side weirs abutting on both sides of the cooling drum is surrounded by an inert atmosphere and the generation of scum is suppressed as much as possible, intervening from the inside of the molten steel It is inevitable that a considerable amount of scum floats on the surface of the molten steel and agglomerates due to the floating of objects and mixed slag. And this scum is wound between a cooling drum and molten steel, and pickling unevenness appears on the surface of a thin cast slab.
[0007]
This pickling unevenness part is manifested as gloss unevenness in the final thin plate product and decreases its value as a product material. Therefore, in order to further improve the quality and yield of the final thin plate product, continuous casting of thin slabs In addition to suppressing the generation of scum as much as possible, even if the scum is caught, it is possible to suppress the occurrence of pickling unevenness in the thin cast slab as much as possible. is there.
[0008]
Therefore, the present inventor investigated in detail the thin-walled slab in which pickling unevenness was developed in order to find out the countermeasure. As a result, the present inventor has discovered that a “crack” having a form different from that of the conventionally known surface crack is generated in the vicinity of the boundary between the region where pickling unevenness appears and the region where the pickling unevenness does not occur. FIG. 1 shows this “crack” (hereinafter referred to as “accompanied crack pickling”).
[0009]
As can be seen from FIG. 1, “accompaniment crack” is a surface crack (hereinafter, sometimes referred to as “dimple crack”) that occurs in a portion where no pickling occurs. It is different in terms of origin, position, form, etc.
Therefore, it is difficult to prevent the above-mentioned extraneous “pickling accompanied by pickling” with the conventional means.
[0010]
In this way, in continuous casting of thin-walled slabs, in addition to the problem of suppressing the occurrence of “dimple cracking” and “pickling unevenness”, the occurrence of “cracking accompanied by pickling unevenness” that is different from these is suppressed. I had a new problem to do.
[0011]
[Problems to be solved by the invention]
Accordingly, the present invention has an object to suppress the occurrence of “dimple cracking” and the occurrence of “pickling unevenness” and “pickling accompanying cracking” in continuous casting of thin-walled slabs. Is intended to solve this problem from the viewpoint of the peripheral structure of the cooling drum that greatly affects the solidification mode of the molten steel.
[0012]
[Means for Solving the Problems]
For pickling, the solidification of the molten steel at the site where the scum adheres is delayed, and as a result, the solidification structure of the scum adhesion part is different from the surrounding solidification structure. Since it appears as “unevenness” on one surface, it is presumed that the solidification mode of the molten steel on the surface of the cooling drum is also greatly involved in the occurrence of “uneven cracking associated with pickling”.
[0013]
Therefore, the present inventor first investigated the solidification mode of the thin-walled slab in which the “acid pickling uneven crack” as shown in FIG. 1 occurred. Due to the inflow and adhesion of scum, the thermal resistance at the interface between the cooling drum and molten steel changes, resulting in a difference in the thickness of the solidified shell formed between the part where the scum is attached and the part where it is not. Thus, specifically, it has been found that the non-uniformity of the solidified shell thickness occurs at a site exceeding 20%.
[0014]
FIG. 2 schematically shows the generation mechanism. In the part where the
[0015]
As described above, the occurrence and accumulation of “strain” that causes “
[0016]
The result is shown in FIG. According to this figure, it can be seen that if the dimple depth (μm) is increased, the occurrence of “accompaniment cracks” can be prevented, but conversely, the occurrence of “dimple cracks” is promoted.
Thus, the present inventor has found that the occurrence or suppression of “dimple cracking” and “accompanied crack pickling” is a trade-off relationship when viewed in relation to the depth of the dimple formed on the peripheral surface of the cooling drum. I found out that
[0017]
Here, FIG. 4 schematically shows a generation mechanism of “dimple cracking”. Solidification nuclei are generated in the molten steel portion in contact with the top of the dimple 3 (see “6” in the figure), and solidification proceeds from here, but the
[0018]
When the
The findings obtained from the above survey results are summarized as follows.
(A) Although molten steel contacts the top part of a dimple, it does not contact the bottom part, or it is a part even if it contacts.
(B) Molten steel that contacts the top of the dimple solidifies faster than molten steel that does not contact the top.
(C) In molten steel that does not contact the bottom of the dimple, nucleation is delayed and solidification is delayed.
(D) Solidification of molten steel is non-uniform compared to dimple units, and non-uniform stress / strain caused by this non-uniformity is accumulated for each dimple unit. This causes “dimple cracking”.
(E) Solidification is delayed in molten steel to which scum is attached, and uneven stress and strain are accumulated at the boundary with the solidified portion of the molten steel that is not. This causes “accompaniment cracking”.
(F) If the “dimple depth” is deep, the accumulation of non-uniform stress / strain caused by the solidification delay of molten steel due to scum adhesion is alleviated, but conversely, the accumulation of non-uniform stress / strain for each dimple unit is reduced. Encouraged, "dimple cracks" occur frequently.
[0019]
It is clear that “dimple cracking” and “cracking crack accompanying cracks” are both closely related to “solidification mode of molten steel” on the surface of the cooling drum. On the basis of the dimple form, first, “dimple depth” sufficient to suppress the occurrence of “pickling unevenness” and “cracking accompanied by pickling unevenness” is secured, and on the premise of this “dimple depth” On the surface of the dimple,
(X) delay the solidification of the molten steel in contact with the top, and
(Y) promote solidification of the molten steel in contact with the bottom,
If the function is added, it is possible to reduce the uneven stress / strain that occurs and accumulates for each dimple unit, and it is not possible to suppress both the occurrence of “cracking accompanying cracks” and the occurrence of “dimple cracks”. I came up with the idea of heels.
[0020]
Then, the inventor conducted various investigations on the surface forms that fulfill the functions (x) and (y) in the dimples formed on the peripheral surface of the cooling drum under the above idea. As a result, it has been found that solidification of molten steel abutting on the top of the dimple can be delayed by forming a “round” having a predetermined shape on the top of the dimple or forming a “pore” having a predetermined shape.
[0021]
Also, when the top of the dimple is “rounded” or “pores” are formed, the molten steel easily abuts against the bottom of the dimple under the static pressure of the molten steel or the cooling force of the cooling drum. Solidification starts from the solidification nuclei. However, if “microprojections”, “pores” or “micro unevenness” with a predetermined shape is formed at the bottom of the dimple, the generation of solidification nuclei is promoted and the molten steel It was found that coagulation proceeds faster.
[0022]
Based on the above knowledge, the present invention further includes the shape of the dimple, the shape of “roundness” or “pore” formed at the top of the dimple, and the “microprojection” or “pore” formed at the bottom of the dimple. Or, it was made by confirming a preferable relationship with the shape of the “micro unevenness”.
And the summary of the invention which concerns on the cooling drum for thin cast slab continuous casting is as follows.
( 1 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. Are formed on the surface of the indentation, and are formed with minute projections having a height smaller than the average depth of the indentation and having a height of 1 to 50 μm and a circle equivalent diameter of 5 to 200 μm. A cooling drum for continuous casting of a thin-walled slab characterized by
( 2 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. A thin drum cast casting cooling drum characterized in that a pore having a depth of 5 μm to 150 μm and a diameter corresponding to a circle of 5 to 200 μm is formed on the surface of the recess. .
( 3 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. A thin-walled casting characterized in that fine irregularities having an average depth of 1 to 50 μm and a diameter corresponding to a circle of 10 to 200 μm are formed at intervals of 80 to 250 μm on the surface of the recess. A cooling drum for continuous casting.
( 4 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. For thin-walled slab continuous casting, characterized in that a minute protrusion having a height of 1 to 50 μm and a diameter corresponding to a circle of 30 to 200 μm is formed adjacent to the top of the recess. Cooling drum.
( 5 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. In addition, a minute protrusion having a height of 1 to 50 μm and a circle-equivalent diameter of 30 to 200 μm is formed adjacent to the top of the depression, and the average depth of the depression is determined on the surface of the depression. A cooling drum for continuous casting of a thin-walled slab, characterized in that microprojections having a small height and having a height of 1 to 50 μm and a diameter corresponding to a circle of 5 to 200 μm are formed.
( 6 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. In addition, a minute protrusion having a height of 1 to 50 μm and a circle-equivalent diameter of 30 to 200 μm is formed adjacent to the top of the depression, and the depth of the depression is 5 μm or more. A cooling drum for continuous casting of a thin cast slab, wherein pores having a diameter of 150 μm or less and a circle-equivalent diameter of 5 to 200 μm are formed.
( 7 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. In addition, a minute protrusion having a height of 1 to 50 μm and a diameter corresponding to a circle of 30 to 200 μm is formed adjacent to the top of the depression, and the average depth is 1 on the surface of the depression. A cooling drum for continuous casting of a thin cast slab, characterized in that fine irregularities having a diameter corresponding to a circle of 10 to 200 μm are formed at intervals of 80 to 250 μm.
( 8 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. A thin drum cast casting drum characterized in that, at the top of the recess, a pore having a depth of 5 μm or more and 150 μm or less and a diameter corresponding to a circle of 5 to 200 μm is formed. .
( 9 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. In addition, a pore having a depth of 5 μm or more and 150 μm or less and a circle-equivalent diameter of 5 to 200 μm is formed at the top of the recess, and the surface of the recess is smaller than the average depth of the recess. A cooling drum for continuous casting of a thin cast slab, characterized in that a minute projection having a height of 1 to 50 μm and a diameter corresponding to a circle of 5 to 200 μm is formed.
( Ten ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. For the continuous casting of thin-walled slabs characterized in that pores having a depth of 5 μm or more and 150 μm or less and a diameter equivalent to a circle of 5 to 200 μm are formed on the top and surface of the depression Cooling drum.
( 11 ) A cooling drum that continuously casts a thin-walled slab, and recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are adjacent to each other through the top of the recess. In addition, pores having a depth of 5 μm or more and 150 μm or less and a circle-equivalent diameter of 5 to 200 μm are formed at the top of the depression, and an average depth of 1 to 50 μm is formed on the surface of the depression. A cooling drum for continuous casting of a thin cast slab, wherein fine irregularities having a circle-equivalent diameter of 10 to 200 μm are formed at intervals of 80 to 250 μm.
[0023]
Moreover, said (1)-( 11 The gist of the invention according to the continuous casting method using the cooling drum for continuous casting of the thin cast slab is as follows.
( 12 ) Rotating in one direction (1) to ( 11 The molten steel is injected onto the peripheral surface of the cooling drum for continuous casting of the thin-walled slab according to any one of the above, and the molten steel is cooled and solidified on the peripheral surface of the cooling drum, thereby continuously casting the thin-walled slab. A method for continuously casting thin-walled slabs.
( 13 ) A pair of (1) to (1) arranged in parallel and rotating in opposite directions. 11 The hot water pool is formed on a part of the peripheral surface of the cooling drum for continuous casting of the thin cast slab according to any one of the above, and the molten steel injected into the hot water pool is cooled and solidified on the peripheral surface of the cooling drum. A method for continuously casting a thin-walled slab, comprising continuously casting a thin-walled slab.
[0024]
Furthermore, said (1)-( 11 The summary of the invention relating to the thin-walled slab in which the molten steel is continuously cast using the cooling drum for continuous casting of the thin-walled slab according to any one of the following is as follows.
( 14 ) (1) to ( 11 ) In which the molten steel is continuously cast using the cooling drum for continuous casting of the thin cast slab, wherein the molten steel is in contact with the top of the recess on the peripheral surface of the cooling drum. Solidification starts from the solidification nucleation starting point generated in
( 15 ) The solidification nucleation starting point generated at the molten steel portion in contact with the top of the depression is generated in an annular shape with a circle-equivalent diameter of 0.5 to 3 mm. 14 Thin-walled slab as described in).
( 16 ) The solidification nucleation starting points generated at the molten steel portion in contact with the microprotrusions, pores, or fine irregularities are generated at intervals of 250 μm or less ( 14 ) Or ( 15 Thin-walled slab as described in).
( 17 ) (1) to ( 11 ) In which molten steel is continuously cast using the cooling drum for continuous casting of the thin-walled cast slab, wherein the molten steel is formed on the surface of the thin-walled slab by depressions on the peripheral surface of the cooling drum. There is a continuous net-like dent formed by solidifying by contacting the top of the ridge, and there are micro-dents and / or micro-projections in each of the areas defined by the continuous network dent. A thin-walled slab characterized by
( 18 ) Each region defined by the mesh-like continuous dents is a region having a diameter corresponding to a circle and having a diameter of 0.5 to 3 mm. 17 Thin-walled slab as described in).
( 19 ) In each of the regions partitioned by the net-like continuous dents, minute dents and / or minute protrusions are present at intervals of 250 μm or less. 17 ) Or ( 18 Thin-walled slab as described in).
( 20 The above-mentioned (9), wherein the bottom of the continuous net-like recess has a minute recess and / or a minute protrusion. 17 ), ( 18 ) Or ( 19 Thin-walled slab as described in).
( twenty one ) (1) to ( 11 ) In which the molten steel is continuously cast using the cooling drum for continuous casting of the thin-walled slab, wherein the molten steel is in contact with the top of the recess on the peripheral surface of the cooling drum. Starting from the solidification nucleus generation starting point formed along the formed net-like continuous dent, solidification is started while maintaining the shape of the net-like continuous dent, then microprojections and pores on the surface of the dent Alternatively, a thin cast slab characterized by solidification starting from a solidification nucleus generation starting point generated in a molten steel portion in contact with fine irregularities.
( twenty two ) Each region defined by the mesh-like continuous dents is a region having a diameter corresponding to a circle and having a diameter of 0.5 to 3 mm. twenty one Thin-walled slab as described in).
( twenty three ) The solidification nucleation starting points generated at the molten steel portion in contact with the microprotrusions, pores, or fine irregularities are generated at intervals of 250 μm or less ( twenty one ) Or ( twenty two Thin-walled slab as described in).
[0025]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in further detail.
The present invention provides a cooling drum in which depressions of a predetermined shape are formed adjacent to each other through the tops of the depressions on the peripheral surface, and / or on the tops of the dimples (or depressions), The basic technical idea is to form minute protrusions, pores or minute irregularities.
[0026]
In accordance with the above knowledge, this provides the function of delaying solidification of the molten steel by forming microprojections or pores on the top of the dimples, and also forms microprojections, pores or micro unevenness on the surface of the dimples. By doing this, the function which accelerates | stimulates solidification of molten steel is provided.
The top of the dimple with the dimples formed has an acute shape, but when a large number of microprojections are formed on the top, the microprojections are continuous with each other at the top of the narrow acute shape. Therefore, the top of the dimple is rounded.
[0027]
The “round” dimple top portion delays the formation of solidification nuclei in the molten steel in contact with the top portion, thereby slowing the progress of solidification of the molten steel. Further, the “rounded” top portion promotes the penetration of the molten steel into the bottom portion of the dimple. As a result, the molten steel easily comes into contact with the bottom of the dimple under the static pressure of the molten steel or the reduction force of the cooling drum.
[0028]
When pores are formed at the top of the dimple having an acute shape, the sharp shape disappears and a slow cooling portion for holding gas is formed. Therefore, the dimple top having “pores” is formed at the top. It delays the formation of solidification nuclei in the abutting molten steel, and slows the progress of solidification of the molten steel.
In addition, the presence of pores at the top of the dimple promotes the penetration of the molten steel into the bottom of the dimple, and similarly, it can easily abut against the bottom of the dimple under the static pressure of the molten steel or the cooling force of the cooling drum. become.
[0029]
In addition, when the minute unevenness is formed on the top of the dimple, the “round” function and the “pore” function are combined.
On the other hand, “microprotrusions”, “pores” or “fine irregularities” formed on the bottom surface of the dimple promotes the formation of solidification nuclei in the molten steel in contact with the surface and promotes the solidification of the molten steel. .
[0030]
As described above, the cooling drum for continuous casting of the thin slab of the present invention (hereinafter referred to as “cooling drum of the present invention”) is sufficient to suppress the occurrence of “pickling unevenness” and “pickling accompanied by pickling unevenness”. In addition to ensuring a sufficient “dimple depth”, solidification of the molten steel is delayed at the top of the dimple, and the penetration of the molten steel into the bottom of the dimple is promoted. It has a function of promoting solidification of the molten steel that has come into contact.
[0031]
Therefore, in the cooling drum of the present invention, since the solidification mode on the circumferential surface of the cooling drum is uniform, conventionally, the nonuniform stress and strain ("dimple cracking" generated and accumulated for each unit of the dimple is conventionally generated. Will be reduced.).
Further, in the cooling drum of the present invention, even if the scum is caught between the cooling drum and the molten steel in the balance, the solidification of the molten steel portion to which the scum adheres is delayed, and a thin solidified shell is formed at the scum adhesion portion. Further, since the non-uniformity of the solidified shell thickness is suppressed to 20% or less, the “strain” (causing “accompaniment cracking”) that occurs and accumulates in the nonuniform portion of the solidified shell thickness. Will be reduced.
[0032]
In the cooling drum of the present invention, recesses having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm are formed adjacent to each other via the tops of the recesses. It is preferable.
If the average depth of the dents (dimples) is less than 40 μm, the effect of mitigating macro stress / strain by dimples cannot be obtained, so the lower limit is set to 40 μm. On the other hand, if the average depth of the dimples exceeds 200 μm, the penetration of the molten steel into the dimple bottom becomes insufficient, so the upper limit is 200 μm.
[0033]
The size of the recess is preferably 0.5 to 3 mm in diameter corresponding to a circle. If the diameter is less than 0.5 mm, the penetration of molten steel into the dimple bottom becomes insufficient, so the lower limit is set to 0.5 mm. On the other hand, if the diameter corresponding to the circle exceeds 3 mm, accumulation of stress / strain in the dimple unit increases and dimple cracking is likely to occur, so the upper limit is set to 3 mm.
[0034]
Then, it is preferable to form “microprojections”, “pores”, or “fine irregularities” of a required shape on the surface of the recess having the above shape. Hereinafter, those required shapes will be described.
(A) Micro protrusion
A minute protrusion having a height of 1 to 50 μm and a diameter corresponding to a circle of 5 to 200 μm is formed on the surface of the recess having the above shape.
[0035]
If the height is less than 1 μm, the protrusions cannot sufficiently contact the molten steel, and solidification nuclei do not occur, so the lower limit is set to 1 μm. On the other hand, if the height exceeds 50 μm, solidification of the molten steel at the bottom of the projection is delayed and non-uniformity of the solidified shell in the recess occurs, so the upper limit is set to 50 μm.
If the diameter corresponding to the circle is less than 5 μm, cooling at the protrusions is insufficient and solidification nuclei are not generated, so the lower limit is set to 5 μm. On the other hand, when the diameter corresponding to the circle exceeds 200 μm, a portion where the molten steel is not sufficiently in contact with the protrusion is generated, and the generation of solidified nuclei becomes nonuniform, so the upper limit is 200 μm.
(B) Pore
A pore having a depth of 5 μm or more and a diameter corresponding to a circle of 5 to 200 μm is formed on the surface of the recess having the above shape.
[0036]
If the depth is less than 5 μm, the air gap is not sufficiently generated in the pores, and the formation of solidified nuclei on the depression surface other than the pores cannot be achieved. Therefore, the lower limit is set to 5 μm.
Further, if the diameter corresponding to the circle is less than 5 μm, the cooling relaxation effect in the pores is not sufficiently exhibited, and the generation of solidification nuclei cannot be limited to the recessed surface other than the pores, so the lower limit is 5 μm. . On the other hand, when the equivalent circle diameter exceeds 200 μm, the molten steel penetrates into the pores, and the molten steel that has entered solidifies and consolidates the solidified shell, concentrating strain and promoting the occurrence of cracks. 200 μm.
(C) Fine irregularities
Fine irregularities having an average depth of 1 to 50 μm and a circle-equivalent diameter of 10 to 200 μm are formed on the surface of the recess having the above shape.
[0037]
If the average depth is less than 1 μm, solidification nuclei are not generated in the concavo-convex portion, so the lower limit is 1 μm. On the other hand, if the average depth exceeds 50 μm, solidification at the bottom of the unevenness is delayed and non-uniformity of the solidified shell in the recess occurs, so the upper limit is set to 50 μm.
Moreover, since the production | generation of the solidification nucleus in an uneven | corrugated | grooved part does not occur that the diameter equivalent to a circle is less than 10 μm, the lower limit is set to 10 μm. On the other hand, when the diameter corresponding to the circle exceeds 200 μm, a portion where the molten steel is not sufficiently in contact with the uneven portion is generated, and the generation of solidified nuclei becomes non-uniform.
[0038]
Furthermore, in the cooling drum of the present invention, a recess having an average depth of 40 to 200 μm and a circle-equivalent diameter of 0.5 to 3 mm is formed on the circumferential surface thereof adjacent to each other via the top of the recess. It is preferable that minute protrusions having a required shape are formed adjacent to the top of "", and the "top" is rounded, or "pores" having the required shape are formed. Those required shapes will be described.
(D) Minute protrusion
A minute protrusion having a height of 1 to 50 μm and a circle-equivalent diameter of 30 to 200 μm is formed adjacent to the top of the depression having the above shape.
[0039]
If the height is less than 1 μm, the effect of delaying solidification nucleation at the top of the temple is not obtained, so the lower limit is 1 μm. On the other hand, if the height exceeds 50 μm, the penetration of the molten steel into the dimple bottom becomes insufficient, so the upper limit is made 50 μm.
If the equivalent circle diameter is less than 30 μm, the effect of delaying solidification nucleation at the top of the dimple cannot be obtained, so the lower limit is set to 30 μm. On the other hand, if the diameter corresponding to the circle exceeds 200 μm, the stress / strain relaxation effect by dimples cannot be obtained, so the upper limit is set to 200 μm.
(E) Pore
A pore having a depth of 5 μm or more and a diameter corresponding to a circle of 5 to 200 μm is formed at the top of the depression having the above shape.
[0040]
If the depth is less than 5 μm, the air gap is not sufficiently formed in the pores, and the effect of delaying solidification nucleation cannot be obtained, so the lower limit is set to 5 μm.
Also, if the equivalent circle diameter is less than 5 μm, solidification nuclei are generated near the top other than the pores, and the effect of promoting the penetration of molten steel into the dimple bottom cannot be obtained, so the lower limit is set to 5 μm. On the other hand, if the diameter corresponding to the circle exceeds 200 μm, the height of the top of the dimple is apparently lowered, and a stress / strain relaxation effect cannot be obtained, so the upper limit is set to 200 μm.
[0041]
In the present invention, the peripheral structure of the cooling drum is configured by appropriately combining the fine protrusions, pores and fine irregularities of the above (a) to (e) according to the steel type, desired plate thickness, and quality. be able to.
The cooling drum of the present invention can be used for both single roll type continuous casting and twin roll type continuous casting.
[0042]
Next, the thin cast piece continuously cast by either the single roll type continuous casting or the twin roll type continuous casting using the cooling drum of the present invention will be described.
The thin-walled slab of the present invention basically starts solidification from the origin of solidification nucleation generated at the molten steel site where the molten steel is in contact with the top of the depression on the peripheral surface of the cooling drum, It is solidified with the origin of solidification nucleation generated at the molten steel portion in contact with the fine protrusions, pores or fine irregularities on the surface of the depression.
[0043]
Here, if the diameter corresponding to the circle of the depression on the peripheral surface of the cooling drum is 0.5 to 3 mm, the solidification nucleation starting point is along the top of the molten steel portion that is in contact with the top of the depression, that is, , With a diameter equivalent to a circle, it is formed in an annular shape of 0.5 to 3 mm.
It is preferable that the solidification nucleus generation starting points generated at the molten steel portion in contact with the fine protrusions, pores, or fine irregularities on the surface of the depression are generated at intervals of 250 μm or less.
[0044]
That is, it is preferable to form fine protrusions, pores, or fine irregularities with an upper limit of a diameter corresponding to a circle of 200 μm on the surface of the depression at intervals of 250 μm or less to promote the generation of the solidification nucleus generation start point.
In the thin-walled slab of the present invention, the molten steel abuts on the “top” and “bottom surface” of the recess on the peripheral surface of the cooling drum and solidifies to form a “net-like continuous recess” on the surface. In addition, a “micro-dent” and / or a “micro-projection” may be formed in each region defined by the “network-like continuous recess”.
[0045]
The above-mentioned “minute dents” and / or “minute projections” correspond to the case where “pores” or “fine irregularities” are formed at the top of the dents on the peripheral surface of the cooling drum of the present invention. And formed on the surface of the thin cast slab.
When the diameter corresponding to the circle of the depression on the peripheral surface of the cooling drum of the present invention is 0.5 to 3 mm, each region defined by the above “net-like continuous depression” has a diameter corresponding to the circle of the depression. Correspondingly, the area corresponding to a circle is 0.5 to 3 mm.
[0046]
In addition, in each of the regions defined by the mesh-like continuous recesses, “micro-dents” and / or “ A minute projection "is formed. The “minute dents” and / or “minute protrusions” are preferably present at intervals of 250 μm or less.
Most preferably, the thin-walled slab of the present invention starts from a solidification nucleation starting point where the molten steel is generated along a net-like continuous recess formed in a molten steel portion that is in contact with the top of the recess on the peripheral surface of the cooling drum. Then, solidification is started while maintaining the shape of the net-like continuous depression, and then the origin of solidification nucleation generated at the molten steel portion in contact with the minute projections, pores or minute irregularities on the surface of the depression is started. As a solidified product.
[0047]
Further preferably, in the thin cast slab, each region partitioned by the net-like continuous dent is a region having a diameter corresponding to a circle of 0.5 to 3 mm, and / or the microprojections and pores. Or the solidification nucleus generation | occurrence | production origin produced | generated in the molten steel site | part contact | abutted to the fine unevenness | corrugation is produced | generated by the space | interval of 250 micrometers or less.
Hereinafter, examples of the present invention will be described. The present invention relates to the peripheral structure of the cooling drum used in the examples, the continuous casting conditions, and the thin cast pieces obtained under these peripheral surface structures and the continuous casting conditions. The shape and structure are not limited.
[0048]
【Example】
A strip-shaped thin cast piece having a plate thickness of 3 mm was cast by a twin drum type continuous casting machine showing SUS304 stainless steel, and then the cast piece was cold-rolled to produce a thin plate product having a plate thickness of 0.5 mm. When casting the strip-shaped thin cast piece, the peripheral surface of a cooling drum having a width of 1330 mm and a diameter of 1200 mm was processed under the conditions shown in Table 1. In Table 1, “dents” are those processed by shot blasting.
[0049]
The surface quality of the finally obtained thin plate products is as shown in Table 1, Table 2 (continuation of Table 1) and Table 3 (continuation of Table 2).
In addition, cracks / gloss unevenness is determined by visual observation after cold rolling and pickling annealing of a thin slab, and the structure is determined by microscopic observation after polishing and etching the slab surface, Was measured with a three-dimensional roughness meter.
[0050]
[Table 1]
[Table 2]
[Table 3]
【The invention's effect】
According to the present invention, in addition to surface defects such as surface cracks and cracks and pickling unevenness, it is possible to efficiently produce a thin-walled slab free from pickling uneven cracks.
Therefore, the present invention can provide a high-quality stainless steel sheet with excellent surface properties and no unevenness of gloss at a low yield with good yield, and consumer goods that use stainless steel as a product material or building material. It greatly contributes to the development of manufacturing industry and construction industry.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing aspects of “pickling unevenness” and “pickling accompanied by pickling unevenness” developed on the surface of a continuously cast thin slab.
FIG. 2 is a diagram schematically showing a mechanism of occurrence of “accompaniment cracking accompanied by pickling” shown in FIG. 1;
FIG. 3 is a diagram showing the relationship between “dimple depth” (solidification mode) and “crack length” (occurrence state) of “dimple crack” and “crack accompanying crack”.
FIG. 4 is a diagram schematically showing a generation mechanism of “dimple cracking”.
[Explanation of symbols]
1 ... Scum
2 ... Solidified shell
3 ... Dimple
4 ... Gas gap
5 ... Cracking accompanying pickling
6 ... Solidification nucleation
7 ... Projection of molten steel
8 ... Dimple crack
9 ... Molten steel
10 ... Cooling drum
Claims (23)
Priority Applications (23)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000306711A JP3908901B2 (en) | 2000-10-05 | 2000-10-05 | Cooling drum for continuous casting of thin-walled slab, thin-walled slab and its continuous casting method |
| US10/031,349 US6896033B2 (en) | 2000-05-12 | 2001-05-11 | Cooling drum for continuously casting thin cast piece and fabricating method and device therefor and thin cast piece and continuous casting method therefor |
| AT05006812T ATE375833T1 (en) | 2000-05-12 | 2001-05-11 | COOLED CASTING ROLL FOR CONTINUOUS CASTING OF THIN PRODUCTS AND CONTINUOUS CASTING PROCESSES |
| EP05006812A EP1602424B2 (en) | 2000-05-12 | 2001-05-11 | A cooling drum for thin slab continuous casting and continuous casting method thereof |
| AT01930090T ATE361167T1 (en) | 2000-05-12 | 2001-05-11 | COOLED CASTING ROLL FOR CONTINUOUS CASTING OF THIN PRODUCTS AND CONTINUOUS STRONG CASTING PROCESS |
| DE60128217T DE60128217T2 (en) | 2000-05-12 | 2001-05-11 | COOLED CASTING ROLL FOR THE CONTINUOUS CONTINUOUS CASTING OF THIN PRODUCTS AND CONTINUOUS CASTING METHOD |
| PCT/JP2001/003965 WO2001085369A1 (en) | 2000-05-12 | 2001-05-11 | Cooling drum for continuously casting thin cast piece and fabricating method and device therefor and thin cast piece and continuous casting method therefor |
| ES05006812T ES2291995T5 (en) | 2000-05-12 | 2001-05-11 | A cooling drum for continuous thin plate casting and a continuous casting method with it |
| CA002377876A CA2377876C (en) | 2000-05-12 | 2001-05-11 | Cooling drum for thin slab continuous casting, processing method and apparatus thereof, and thin slab and continuous casting method thereof |
| KR1020057016119A KR100668126B1 (en) | 2000-05-12 | 2001-05-11 | Apparatus for processing cooling drum for continuously casting thin cast piece |
| EP05006814A EP1582279A1 (en) | 2000-05-12 | 2001-05-11 | A continuous cast thin slab |
| AT05006811T ATE446814T1 (en) | 2000-05-12 | 2001-05-11 | COOLED CASTING ROLL FOR CONTINUOUS CASTING OF THIN PRODUCTS |
| KR1020027000450A KR100668123B1 (en) | 2000-05-12 | 2001-05-11 | Cooling drum for continuously casting thin cast piece and fabricating method and device therefor and thin cast piece and continuous casting method therefor |
| EP05006811A EP1595621B1 (en) | 2000-05-12 | 2001-05-11 | A cooling drum for thin slab continuous casting |
| DE60131034T DE60131034T3 (en) | 2000-05-12 | 2001-05-11 | COOLED CASTING ROLL FOR THE CONTINUOUS CONTINUOUS CASTING OF THIN PRODUCTS AND CONTINUOUS CASTING METHOD |
| DE60140321T DE60140321D1 (en) | 2000-05-12 | 2001-05-11 | COOLED CASTING ROLL FOR CONTINUOUS CASTING OF THIN PRODUCTS |
| KR1020057016118A KR100692499B1 (en) | 2000-05-12 | 2001-05-11 | Method of processing cooling drum for continuously casting thin cast piece |
| ES01930090T ES2287125T3 (en) | 2000-05-12 | 2001-05-11 | COOLING DRUM FOR CONTINUOUS COLADA OF MOLDED THIN PIECES AND CONTINUOUS COLADA PROCEDURE FOR THE SAME. |
| AU56712/01A AU777752B2 (en) | 2000-05-12 | 2001-05-11 | Cooling drum for continuously casting thin cast piece and fabricating method and device therefor and thin cast piece and continuous casting method therefor |
| EP01930090A EP1281458B1 (en) | 2000-05-12 | 2001-05-11 | Cooling drum for continuously casting thin cast piece and continuous casting method therefor |
| ES05006811T ES2333232T3 (en) | 2000-05-12 | 2001-05-11 | A COOLING DRUM FOR CONTINUOUS COLADA OF THICK IRON. |
| EP05006813A EP1595622A1 (en) | 2000-05-12 | 2001-05-11 | A method of processing a cooling drum for metal cast strip by continuous casting and an apparatus therefor |
| US11/044,561 US7159641B2 (en) | 2000-05-12 | 2005-01-26 | Cooling drum for thin slab continuous casting, processing method and apparatus thereof, and thin slab and continuous casting method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000306711A JP3908901B2 (en) | 2000-10-05 | 2000-10-05 | Cooling drum for continuous casting of thin-walled slab, thin-walled slab and its continuous casting method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2002113557A JP2002113557A (en) | 2002-04-16 |
| JP3908901B2 true JP3908901B2 (en) | 2007-04-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000306711A Expired - Fee Related JP3908901B2 (en) | 2000-05-12 | 2000-10-05 | Cooling drum for continuous casting of thin-walled slab, thin-walled slab and its continuous casting method |
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| JP (1) | JP3908901B2 (en) |
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| AU2008100847A4 (en) | 2007-10-12 | 2008-10-09 | Bluescope Steel Limited | Method of forming textured casting rolls with diamond engraving |
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| JP2002113557A (en) | 2002-04-16 |
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