JP4153570B2 - Method for producing non-oriented electrical steel sheet with high magnetic flux density and low iron loss - Google Patents

Description

【００４９】
仕上熱間圧延時に、実際にロールに噴霧される際の潤滑油の動粘度、およびロール冷却水中に占める体積分率を変更して試験を行い、製品磁束密度との関係を詳細に調査した。αγ変態点を有する成分系の鋼ＡのＡｒ_３ 点は９０４℃であり、Ａｒ_１ 点は８７０℃である。このため、鋼Ａの熱延仕上げ温度は（Ａｒ_３ ＋Ａｒ_１ ）／２以下かつ７００℃以上である８６０℃とした。一方、αγ変態点を有しない成分系の鋼Ｂは熱延終了温度を８８０℃とした。鋼Ａ，Ｂともに２．５mm厚の熱延板に仕上げた後、水冷して５５０℃で巻き取った。
【００５０】
次いで、これらの熱延板を酸洗、冷延して０．５０mm厚とし、脱脂した後、鋼Ａは７５０℃、３０秒焼鈍しエプスタイン試料を切断して磁気特性を測定した。また、鋼Ｂは酸洗、冷延し０．５０mm厚とし、脱脂した後、９５０℃、３０秒焼鈍し、エプスタイン試料を切断して磁気特性を測定した。
【００５１】
鋼Ａの実験結果による仕上熱延時の潤滑油の動粘度とロール冷却水中の潤滑油の濃度と成品磁束密度との関係を図１に、同じく鋼Ｂの実験結果を図２に示す。図１、図２によれば潤滑油のロール冷却水に対する体積分率が１．０％以上１０％以下であり、かつ潤滑油の動粘度を２００ｃＳｔ以上とすることで、鋼Ａ、鋼Ｂとも成品磁束密度が上昇することが分かる。
【００５２】
図１、および図２にも示されるとおり、潤滑油の動粘度が２００ｃＳｔ未満では製品の磁束密度向上効果が不十分である。また、潤滑油の動粘度が８００ｃＳｔを超えると、その効果が飽和するとともに動粘度の高い潤滑油を搬送する配管系で詰まりが生じやすくなり、また冷えた潤滑油がスタンドやロールに付着してその除去のために操業を頻繁に停止しなければならなくなるので、潤滑油の動粘度は８００ｃＳｔ以下とする。
【００５３】
また、潤滑油のロール冷却水に対する体積分率が１．０％未満では磁束密度改善効果が無く、１０％を超えるとその効果が飽和して不経済であるので、ロール冷却水中の潤滑油濃度は体積分率で１．０％以上１０％以下とする。
【００５４】
以上の実験から示されるように、仕上熱延において、ワークロールに噴射される潤滑油の動粘度が式（１）を満たし、かつロール冷却水中の潤滑油濃度を式（２）の規定する範囲内とすることによって、成品磁束密度が上昇することがわかる。
【００５５】
次に、冷間圧延前に熱延板焼鈍を施す場合において、仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度の成品磁気特性に対する影響を調査するため下記の様な実験を行った。表２に示す成分の鋼を溶製し仕上げ熱延を実施した。
仕上熱間圧延時に、実際にロールに噴霧される際の潤滑油の動粘度、およびロール冷却水中に占める体積分率を変更して試験を行い、製品磁束密度との関係を詳細に調査した。熱延板は仕上熱延終了温度を９００℃とし、２．５mm厚に仕上げ水冷して５５０℃で巻き取った。
【００５６】
この熱延コイルを連続焼鈍炉で鋼Ｃを９５０℃で９０秒の焼鈍を行った。これを酸洗、冷延し０．３５mm厚とし、脱脂した後、９５０℃３０秒焼鈍しエプスタイン試料を切り出して磁気特性を測定した。
【００５７】
鋼Ｃの仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度と成品磁束密度の関係を図３に示す。図３によれば潤滑油のロール冷却水に対する体積分率が１．０％以上１０％以下でありかつ、潤滑油の動粘度が２００ｃＳｔ以上において鋼Ｃの成品磁束密度が上昇することがわかる。
以上の実験から示されるように、仕上熱延において、ワークロールに噴射される潤滑油の動粘度が式（１）を満たし、かつ式（２）で規定されるようにロール冷却水中の潤滑油濃度は体積分率で１．０％以上１０％以下を満たしていれば、成品磁束密度が上昇することがわかる。
【００５８】
次に、連続焼鈍による熱延板焼鈍時間、熱延板焼鈍温度が磁束密度に与える影響を調査するため、以下の様な実験を行った。表２の成分の鋼Ｃを溶製しスラブとし、粗熱延を行ってシートバーとした後、仕上げ熱延を実施した。
【００５９】
【表２】

【００６０】
仕上熱延終了温度は９００℃で一定として２．０mm厚に仕上げ、熱延終了後急冷し、５００℃で巻取った。仕上熱延機のロール冷却水中に３％の潤滑油を混入し、ノズルからワークロールへ噴射した。ロール冷却水の温度は５５℃に保ち、潤滑油の動粘度は２８０ｃＳｔに保った。
この熱延コイルを連続焼鈍炉で焼鈍温度は９５０℃一定で焼鈍時間を変えて焼鈍を行った。また、一方で連続焼鈍による熱延板焼鈍の時間を９０秒として焼鈍温度を変化させた。これを酸洗、冷延し０．３５mm厚とし、脱脂した後、９００℃、３０秒焼鈍しエプスタイン試料を切断して磁気特性を測定した。
【００６１】
連続焼鈍による熱延板焼鈍時間の製品磁束密度に対する影響を図４に示した。図４に示されるとおり、焼鈍時間が２０秒未満では熱延板焼鈍による磁束密度向上効果が得られず、焼鈍時間が５分以上では鋼板表面に深いスケールが生成し酸洗不良が発生し、鋼板表層に著しい肌荒れが生じた。このため、本発明では連続焼鈍による熱延板焼鈍時間は２０秒以上５分以下とする。なお焼鈍の効果、および経済性からみた好ましい連続焼鈍による熱延板焼鈍時間は３０秒以上３分以下である。
【００６２】
連続焼鈍による熱延板焼鈍温度の製品磁束密度に対する影響を図５に示した。図５に示されるとおり、焼鈍温度が８５０℃未満では連続焼鈍での熱延板焼鈍による磁束密度向上効果が得られず、また焼鈍温度が１１５０℃を超えると深いスケールの生成により酸洗不良が発生し、鋼板表層に著しい肌荒れが生じた。このため、本発明では連続焼鈍による熱延板焼鈍温度は８５０℃以上１１５０℃以下とする。焼鈍の効果、および酸洗性等の経済性からみた好ましい連続焼鈍による熱延板焼鈍温度は８５０℃以上１０００℃以下である。
【００６３】
本発明では熱延板焼鈍を箱焼鈍により行っても良い。その際、熱延板焼鈍温度が７５０℃未満であると製品磁気特性の改善に必要な焼鈍時間が著しく長くなり、不経済である。また焼鈍温度が８５０℃を超えると、炉の設備投資に多額の費用を要するとともに、焼鈍時にコイルが焼き付く現象が発生する。以上の理由で箱焼鈍による熱延板焼鈍を実施する場合は、焼鈍温度を７５０℃以上８５０℃以下とする。その際、箱焼鈍での熱延板焼鈍時間が５分以下であると製品磁気特性の改善に必要な焼鈍温度が著しく高くなり、炉そのものの設備投資が過大となり不経済であるので焼鈍時間は５分以上とする。また、熱延板焼鈍時間が３０時間を超えると焼鈍温度が過度に高い場合と同様に、コイルの焼き付きが生じるので箱焼鈍での熱延板焼鈍時間は３０時間以内とする。
【００６４】
次に、熱延コイルの保有熱により自己焼鈍を行うプロセスにおいて、仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度の成品磁気特性に対する影響を調査するため下記の様な実験を行った。表３に示す成分の鋼を溶製しスラブとし、粗熱延を行ってシートバーとした後、仕上げ熱延を実施した。仕上熱延機のロール冷却水中に４％の潤滑油を混入し、ノズルからワークロールへ噴射した。この際ロール冷却水の温度を変化させることで、潤滑油の動粘度を変化させた。
【００６５】
【表３】

【００６６】
熱延終了温度は１０００℃とし、水冷して８６０℃で巻取り、直ちに保熱カバーをかぶせてガス加熱による補助加熱を施し、コイルの保有熱により８５０℃１時間の自己焼鈍を施した。
これを酸洗、冷延し０．５０mm厚とし、脱脂した後、鋼Ｄは９００℃で、鋼Ｅは９８０℃で４５秒焼鈍しエプスタイン試料を切断して磁気特性を測定した。
【００６７】
仕上熱延時の潤滑油の動粘度に対する製品磁束密度の依存性を図６に示した。図６より、仕上熱延時の潤滑油の動粘度が２００ｃＳｔ以上であると成品磁束密度が上昇することがわかる。
【００６８】
仕上熱延終了後、熱延板をコイルに巻き取り、自己焼鈍を行うようにしてもよい。自己焼鈍を行う際のコイルの巻取温度は、７５０℃未満では磁気特性の改善が不十分であるので、７５０℃以上とする。一方１０００℃を超えるとコイルの巻きずれが発生しやすくなり、鋼板表層の酸化も激しくなるため１０００℃以下とする。
【００６９】
自己焼鈍の時間は、５分未満では磁気特性改善が不十分であるので、５分以上行う。また、５時間を超えると鋼板の酸化が激しくなり酸洗不良が発生しやすくなるので、５時間以下とする。焼鈍の効果、および経済性からみた好ましい自己焼鈍時間は３０分から１２０分である。また自己焼鈍中のコイルの酸化を防止するため、水素を含有する還元性雰囲気、あるいは窒素、アルゴン等の不活性ガス雰囲気、あるいは減圧下で自己焼鈍を行ってもよい。
【００７０】
次に、仕上熱延終了後一定時間の無注水を設けるプロセスにおいて、仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度の成品磁気特性に対する影響を調査するため下記の様な実験を行った。表４に示す成分の鋼Ｆを溶製し仕上げ熱延を実施した。
【００７１】
【表４】

【００７２】
仕上熱延終了温度は１０５０℃で一定とした。この時、仕上熱延機のロール冷却水中に１．５％の潤滑油を混入し、ノズルからワークロールへ噴射した。この際ロール冷却水の温度を変化させることで、潤滑油の動粘度を変化させた。また、式（４）および式（５）に基づき、無注水時間は４．０秒とし、その後冷却して６８０℃で巻き取った。
これを酸洗、冷延し０．５０mm厚とし、脱脂した後、９００℃、３０秒焼鈍しエプスタイン試料を切断して磁気特性を測定した。
【００７３】
仕上熱延時の潤滑油の動粘度に対する製品磁束密度の依存性を図７に示した。図７より、仕上熱延時の潤滑油の動粘度が２００ｃＳｔ以上であると成品磁束密度が上昇することがわかる。
【００７４】
コイルの巻取温度については規定を設けていないが、高温で熱延を終了した鋼板表面に過度の酸化層が生じ、酸洗性が悪化することを防止するため、７５０℃以下で巻き取ることが好ましい。
【００７５】
以下、熱延終了後の無注水設定時間ｔについて述べる。
本発明では仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度の成品磁気特性に対する影響を調査するとともに、仕上熱延において熱延終了温度Ｔ（℃）、熱延終了後注水開始までの時間ｔ（秒）と磁気特性との関係を発明者等は詳細に検討を行った結果、
９５０≦Ｔ≦１１５０ ・・・式（４）
９．６−８×１０^−３Ｔ≦ｔ≦１５．６−８×１０^−３Ｔ・・・式（５）
にて定められる範囲内において、酸洗性、通板速度、磁気特性を満足する良好な条件を定めることが可能となった。
【００７６】
熱延終了温度Ｔ（℃）が式（４）で定められる下限の９５０℃を下回った場合は、磁気特性の改善が不十分である。また、熱延終了温度Ｔ（℃）を式（４）で定められる上限である１１５０℃超にするためには、通常の粗圧延、仕上圧延を有する熱延工程ではスラブの加熱温度を著しく高める必要があり、スラブ加熱中に再固溶した析出物が熱延中に微細に析出し、磁気特性を著しく悪化させる。以上の理由により、熱延終了温度は式（４）で定められる９５０℃以上１１５０℃以下とする。
【００７７】
また、熱延終了後注水開始までの時間が式（５）で定めた時間を超えると、鋼板を冷却する時間が不足し、高温でコイルを巻き取るか、冷却を十分に施すために圧延速度を低下させねばならず、生産性が悪化する。高温でのコイル巻取りは巻きずれの発生や酸洗性の悪化等の弊害を招くので好ましくない。このため無注水時間ｔ（秒）は式（５）で定めたように、１５．６−８×１０^−３Ｔ以下とする。逆に、式（５）で定められる時間よりも無注水時間が短くなると磁気特性の改善が不十分である。このため、仕上熱延終了後の無注水時間ｔ（秒）は式（５）で定めたように、９．６−８×１０^−３Ｔ以上とする。
【００７８】
【実施例】
次に、本発明の実施例について述べる。
［実施例１］
熱延板焼鈍省略一回冷延工程法により製造されるフルプロセス材における、仕上熱間圧延時の潤滑油の動粘度および、ロール冷却水中の潤滑油の濃度の製品磁気特性に対する影響を調査するため、下記の様な実験を行った。
ここで、フルプロセス材とは、一回又は中間焼鈍をはさむ二回以上の冷延後、焼鈍を施し最終製品とする工程で製造される製品を指していう。
表５に示した成分を有する無方向性電磁鋼用スラブを通常の方法にて加熱し、粗圧延機により厚み４０mmのシートバーとし、次いで仕上熱延機により２．５mm厚の熱延板とした。
【００７９】
【表５】

【００８０】
鋼Ｇ、鋼Ｈはαγ変態を有するため、熱延仕上温度は（Ａｒ_３ ＋Ａｒ_１ ）／２以下で７００℃以上である８６０℃とし、水冷して６５０℃で巻き取った。鋼Ｉの熱延仕上温度は８９０℃とし、水冷して６５０℃で巻き取った。
仕上熱延機のロール冷却水中に４％の潤滑油を混入し、ノズルからワークロールへ噴射した。ロール冷却水の温度および潤滑油の種類を変更することで、潤滑油の動粘度を変化させた。
【００８１】
本実施例では、高動粘度の潤滑油を使用して仕上熱延を行うため、個々のシートバーの噛み混み不良が生じやすくなるのを避け、安定して仕上熱延を行うため、粗圧延後のシートバーを先行するシートバーに溶接し、仕上熱間圧延を連続して行った。
【００８２】
これらの鋼を酸洗後、鋼Ｇは７５０℃、鋼Ｈは８３０℃、鋼Ｉは９５０℃でそれぞれ３０秒焼鈍を行い、エプスタイン試料を切り出して磁束密度を測定した。表６に本発明と比較例と磁気測定結果をあわせて示す。表６に示されるように仕上熱延時の潤滑油の動粘度が２００ｃＳｔ以上であると製品磁束密度が向上することがわかる。
【００８３】
【表６】

【００８４】
［実施例２］
熱延板焼鈍省略一回冷延工程法により製造されるフルプロセス材における、仕上熱間圧延時の潤滑油の濃度が製品磁気特性に与える影響を調査するため、下記の様な実験を行った。
表５の鋼Ｉに示した成分を有する無方向性電磁鋼用スラブを通常の方法にて加熱し、粗圧延機により厚み４０mmのシートバーとし、次いで仕上熱延機により２．５mm厚の熱延板とした。
仕上熱延機のロール冷却水の温度を４０℃、５０℃、７０℃に調整し、異なる体積分率の潤滑油をロール冷却水中に予めエマルジョン状態で混入し、潤滑油の濃度が製品磁気特性に与える影響を調査した。このとき各温度における潤滑油の動粘度はそれぞれ４００ｃＳｔ、３００ｃＳｔであった。潤滑油を含んだロール冷却水は、ノズルからワークロールへ噴射した。
【００８５】
この鋼Ｉを酸洗後、９５０℃で３０秒焼鈍を行い、エプスタイン試料を切り出して磁束密度を測定した。表７に本発明と比較例と磁気測定結果をあわせて示す。表７に示されるように仕上熱延時の潤滑油の濃度が1．０％以上であると製品磁束密度が向上することがわかる。
【００８６】
【表７】

【００８７】
［実施例３］
熱延板焼鈍法によるフルプロセス材およびセミプロセス材における、仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度の製品磁気特性に対する影響を調査するため、下記の様な実験を行った。
ここで、セミプロセス材とは、一回又は中間焼鈍をはさむ二回以上の冷延後、焼鈍を施し、その後スキンパスを施した状態で最終製品とする製造法での製品を指していう。
表８に示した成分を有する無方向性電磁鋼用スラブを通常の方法にて加熱し、粗圧延機により厚み４０mmのシートバーとし、次いで仕上熱延機により２．０mm厚の熱延板とした。仕上熱延終了温度は９００℃とし、熱延終了後直ちに水冷して５５０℃で熱延板を巻き取った。
【００８８】
【表８】

【００８９】
仕上熱延機のロール冷却水中に３．５％の潤滑油を混入し、ノズルからワークロールへ噴射した。ロール冷却水の温度および潤滑油の種類を変更することで、潤滑油の動粘度を変化させた。
本実施例では、高動粘度の潤滑油を使用して仕上熱延を行うため、個々のシートバーの噛み混み不良が生じやすくなるのを避け、安定して仕上熱延を行うため、粗圧延後のシートバーを先行するシートバーに溶接し、仕上熱間圧延を連続して行った。
【００９０】
得られた熱延板に熱延板焼鈍を連続焼鈍炉で鋼Ｊは９００℃、鋼Ｋは１０００℃でそれぞれ２分間施した。その後、鋼Ｊについてはフルプロセス及びセミプロセスでの特性を、鋼Ｋについてはフルプロセスでの特性を調査した。
【００９１】
鋼Ｊ、鋼Ｋのフルプロセス工程として、熱延板焼鈍後の熱延板に酸洗を施し、冷間圧延により０．５０mmに仕上た。これを連続焼鈍炉にて鋼Ｊは９００℃で、鋼Ｋは９８０℃でそれぞれ３０秒間焼鈍した。その後、エプスタイン試料を切り出し、磁気特性を測定した。
【００９２】
さらに、鋼Ｊのセミプロセス工程として、熱延板焼鈍、酸洗までは同一条件とし、その後冷間圧延の仕上板厚を０．５５mmにし、これを連続焼鈍炉にて９００℃で３０秒間焼鈍した。その後、スキンパス圧延を施し０．５０mmに仕上、エプスタイン試料に切断し、その後、通常は需要家において実施される７５０℃２時間の歪取り焼鈍を施し、磁気特性を測定した。
【００９３】
表９に鋼Ｊ、鋼Ｋの本発明と比較例の成分と磁気測定結果をあわせて示す。表９に示されるように仕上熱延時の潤滑油の動粘度が８０ｃＳｔ以上、特に２００ｃＳｔ以上であると製品磁束密度が向上することがわかる。
【００９４】
【表９】

【００９５】
削除
【００９６】
削除
【００９７】
削除
【００９８】
削除
【００９９】
削除
【０１００】
［実施例５］
箱焼鈍による熱延板焼鈍・一回冷延法により製造されるフルプロセス無方向性電磁鋼板における、仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度の製品磁気特性に対する影響を調査するため、下記の様な実験を行った。
表１２に示した成分を有する無方向性電磁鋼用スラブを通常の方法にて加熱し、粗圧延機により厚み４０mmのシートバーとし、次いで仕上熱延機により２．０mm厚の熱延板とした。仕上熱延終了温度は９００℃とし、圧延終了後冷却して６５０℃で巻き取った。
【０１０１】
【表１２】

【０１０２】
仕上熱延機のロール冷却水中に４．０％の潤滑油を混入し、ノズルからワークロールへ噴射した。ロール冷却水の温度および潤滑油の種類を変更することで、潤滑油の動粘度を変化させた。
得られた熱延板に熱延板焼鈍を箱焼鈍炉で８００℃、５時間施した。その後、酸洗を施し、冷間圧延により０．５０mm厚に仕上た。これを連続焼鈍炉にて鋼Ｍは９００℃で３０秒間、鋼Ｎは９８０℃で３０秒間焼鈍した。その後、エプスタイン試料を切り出し、磁気特性を測定した。
【０１０３】
表１３に本発明と比較例の成分と磁気測定結果をあわせて示す。表１３に示されるように、仕上熱延時の潤滑油の動粘度が２００ｃＳｔ以上であると製品磁束密度が向上することがわかる。
【０１０４】
【表１３】

【０１０５】
［実施例６］
自己焼鈍プロセス一回冷延工程により製造されるフルプロセス無方向性電磁鋼板における仕上熱間圧延時の潤滑油の動粘度、およびロール冷却水中の潤滑油の濃度の製品磁気特性に対する影響を調査するため、下記の様な実験を行った。 表１４に示した成分を有する無方向性電磁鋼用スラブを通常の方法にて加熱し、粗圧延機により厚み５０mmのシートバーとし、次いで仕上熱延機により２．５mm厚の熱延板とした。
【０１０６】
【表１４】

【０１０７】
仕上熱延機のロール冷却水中に３．０％の潤滑油を混入し、ノズルからワークロールへ噴射した。ロール冷却水の温度および潤滑油の種類を変更することで、潤滑油の動粘度を変化させた。
仕上熱延終了温度は１０００℃とし、圧延終了後冷却して８７５℃で巻き取り、直ちにコイルを保熱炉に装入し８５０℃で１時間の自己焼鈍を施した。その後、酸洗を施し、冷間圧延により０．５０mm厚に仕上た。これを連続焼鈍炉にて鋼Ｏは９５０℃で３０秒間、鋼Ｐは９７５℃で３０秒間、鋼Ｑは８５０℃で３０秒間焼鈍した。その後、エプスタイン試料を切り出し、磁気特性を測定した。
【０１０８】
表１５に本発明と比較例の成分と磁気測定結果をあわせて示す。表１５に示されるように、仕上熱延時の潤滑油の動粘度が２００ｃＳｔ以上であると製品磁束密度が向上することがわかる。
【０１０９】
【表１５】

【０１１０】
［実施例７］
仕上熱延後一定時間の無注水時間を設け、一回冷延法により製造されるフルプロセス無方向性電磁鋼板において、仕上熱間圧延時のロール冷却水中に混入される潤滑油の動粘度の製品磁気特性に対する影響を調査するため、下記の様な実験を行った。
表１６に示した成分を有する無方向性電磁鋼用スラブを通常の方法にて加熱し、粗圧延機により厚み５０mmのシートバーとし、次いで仕上熱延機により２．５mm厚のシートバーとした。
【０１１１】
【表１６】

【０１１２】
仕上熱延機のロール冷却水中に３．２％の潤滑油を混入し、ノズルからワークロールへ噴射した。ロール冷却水の温度および潤滑油の種類を変更することで、潤滑油の動粘度を変化させた。
仕上熱延終了温度は１０２０℃とした。この場合、式（４）及び式（５）で規定される無注水時間ｔは１．４４秒以上７．４４秒以下であるので、無注水時間を４．５秒とし、６４０℃で巻き取った。その後、酸洗を施し、冷間圧延により０．５０mm厚とした。これを連続焼鈍炉にて鋼Ｒは９５０℃で、鋼Ｓは９８０℃でそれぞれ３０秒間焼鈍した。その後、エプスタイン試料を切り出し、磁気特性を測定した。
【０１１３】
表１７に本発明と比較例の成分と磁気測定結果をあわせて示す。表１７に示されるように、仕上熱延時の潤滑油の動粘度が２００ｃＳｔ以上であると製品磁束密度が向上することがわかる。
【０１１４】
【表１７】

【０１１５】
［実施例８］
仕上熱延後一定時間の無注水時間を設け、一回冷延法により製造されるフルプロセス無方向性電磁鋼板において、無注水時間が製品磁気特性に与える影響を調査するために以下の実験を行った。
表１８に示した成分を有する無方向性電磁鋼用スラブを通常の方法にて加熱し、粗圧延機により厚み５０mmのシートバーとし、次いで仕上熱延機により２．５mm厚の熱延板とした。
【０１１６】
【表１８】

【０１１７】
熱延終了温度は１０５０℃とし、無注水時間を変化させ、巻取温度は６８０℃で一定とした。この場合、式（４）および式（５）で規定される無注水時間は１．２秒以上７．２秒以下である。
仕上熱延機のロール冷却水中に３．２％の潤滑油を混入し、ノズルからワークロールへ噴射した。潤滑油の動粘度は３２０ｃＳｔとした。その後、酸洗を施し、冷間圧延により０．５０mm厚とした。これを連続焼鈍炉にて９００℃で３０秒間焼鈍した。その後、エプスタイン試料を切り出し、磁気特性を測定した。
【０１１８】
表１９に熱延条件と磁気測定結果をあわせて示す。表１９に示されるように、無注水時間が１．２秒以上であれば良好な磁気特性が得られていることがわかる。
【０１１９】
以上のように、仕上熱延時の潤滑油の動粘度よびロール冷却水中の濃度を適切に制御するとともに、仕上熱延を高温で仕上た後、熱延終了後の無注水時間を適切に制御することにより、磁束密度の値が高い無方向性電磁鋼板を得ることが可能である。
【０１２０】
【表１９】

【０１２１】
［実施例９］
仕上熱間圧延後、冷間圧延を施すことなく最終製品とする無方向性電磁鋼板製造プロセスにおける、仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度の製品磁気特性に対する影響を調査するため下記の様な実験を行った。
表２０に示した成分を有する無方向性電磁鋼用スラブを通常の方法にて加熱し、粗圧延機により厚み４０mmのシートバーとし、次いで仕上熱延機により０．８mm厚の熱延板とした。
【０１２２】
【表２０】

【０１２３】
鋼Ｕ、鋼Ｖはαγ変態を有するため、熱延仕上温度は（Ａｒ_３ ＋Ａｒ_１ ）／２以下で７００℃以上である８６０℃とし、水冷して７５０℃で巻き取った。仕上熱延機のロール冷却水中に５％の潤滑油を混入し、ノズルからワークロールへ噴射した。ロール冷却水の温度を４０℃から８０℃まで変化させることで、潤滑油の動粘度を変化させた。
一方で、仕上熱延のロール冷却水中の潤滑油濃度の製品磁束密度への影響を調べるため、ロール冷却水に種々の濃度の潤滑油潤滑油をエマルジョン状に混合して実験を行った。この際、ロール冷却水と潤滑油との混合液の温度を５０℃として、冷却水中の潤滑油の動粘度を３５０ｃＳｔとした。
本実施例では、高動粘度の潤滑油を使用して仕上熱延を行うため、個々のシートバーの噛み混み不良が生じやすくなるのを避け、安定して仕上熱延を行うため、粗圧延後のシートバーを先行するシートバーに溶接し、仕上熱間圧延を連続して行った。得られた熱延板からエプスタイン試料を切り出し、磁束特性を測定した。
【０１２４】
表２１、表２２に本発明と比較例と磁気特性の測定結果をあわせて示す。表２１より、仕上熱延時の潤滑油の動粘度が２００ｃＳｔ以上であると製品磁束密度が向上することがわかる。また表２２より、ロール冷却水中の潤滑油濃度が１．０％以上であると、製品磁束密度が向上することがわかる。
【０１２５】
【表２１】

【０１２６】
【表２２】

【０１２７】
【発明の効果】
以上のように本願発明によれば、磁束密度が高い無方向性電磁鋼板を製造することが可能である。
【図面の簡単な説明】
【図１】 ０．３％Ｓｉ系成分の熱延板焼鈍省略一回冷延法における仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度と製品磁束密度との関係を示す図表である。
【図２】 ２％Ｓｉ系成分の熱延板焼鈍省略一回冷延法における仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度と製品磁束密度との関係を示す図表である。
【図３】 ２％Ｓｉ系成分の熱延板焼鈍一回冷延法における仕上熱間圧延時の潤滑油の動粘度およびロール冷却水中の潤滑油の濃度と製品磁束密度との関係を示す図表である。
【図４】 ２％Ｓｉ系成分の連続焼鈍による熱延板焼鈍一回冷延法における熱延板焼鈍時間と製品磁束密度との関係を示す図表である。
【図５】 ２％Ｓｉ系成分の連続焼鈍による熱延板焼鈍一回冷延法における熱延板焼鈍温度と製品磁束密度との関係を示す図表である。
【図６】 ２％Ｓｉおよび３％Ｓｉ系成分の熱延後自己焼鈍プロセス一回冷延法における仕上熱延時のロール冷却水中の潤滑油の動粘度と磁束密度との関係を示す図表である。
【図７】 ２．５％Ｓｉ成分系の仕上熱延終了後、無注水時間を設定するプロセスでの一回冷延法における仕上熱延時のロール冷却水中の潤滑油の動粘度と製品磁束密度との関係を示す図表である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a non-oriented electrical steel sheet having a high magnetic flux density, which is used as an iron core material for electrical equipment.
[0002]
[Prior art]
In recent years, in the fields of electrical machinery, especially rotating machines where non-oriented electrical steel sheets are used as iron core materials, and in the fields of medium and small transformers, global power conservation, energy conservation, and global environmental conservation such as CFC regulations Among these trends, the trend toward higher efficiency is spreading rapidly. For this reason, in order to increase the efficiency by reducing the iron loss, which is an energy loss at the time of use, demands for low iron loss electromagnetic steel sheets by customers are increasing. On the other hand, in order to reduce the size of the iron core and obtain the same output in a rotating machine, it is necessary to increase the operating magnetic flux density. For this purpose, a high magnetic flux density non-oriented electrical steel sheet is required. As described above, the downsizing of the rotating machine leads to a reduction in the weight of automobiles, trains, etc., which are mobile bodies mounted on the rotating machine, and thus has an advantage of saving energy consumed by the rotating machine. For this reason, non-oriented electrical steel sheets with low iron loss and high magnetic flux density are now strongly demanded by customers.
In addition, in the present age of entering into the world of global competition, the demand for cost reduction for non-oriented electrical steel sheets is severe, coupled with the above-mentioned trend toward higher efficiency of electrical equipment, the price is If it is the same, the actual situation is that the non-oriented electrical steel sheet having excellent magnetic properties is selected by consumers.
[0003]
By the way, in a non-oriented electrical steel sheet, conventionally, as a means for reducing iron loss, a method of increasing the content of Si, Al, or the like from the viewpoint of reducing eddy current loss due to increased electrical resistance has been taken. However, this method has a problem that a decrease in magnetic flux density is inevitable. In order to overcome such a problem, a method of mainly improving the magnetic flux density by coarsening the hot rolled plate crystal grain size has been performed.
[0004]
Conventionally, in a non-oriented electrical steel sheet having a high Si content, the growth of the crystal structure after finish hot rolling is insufficient, and in order to provide a material with high magnetic flux density and low iron loss, Therefore, it has been essential to subject the crystal structure to coarsening by subjecting it to hot rolling by some method. However, even if it is possible to improve the magnetic properties of some products by performing hot-rolled sheet annealing, it is not sufficient to meet the demands of customers for the high magnetic flux density and low iron loss materials.
[0005]
In view of such problems, as a means for improving the magnetic properties of high-Si non-oriented electrical steel sheets, Japanese Patent Application Laid-Open No. 59-74224 discloses that the Si content is 2.5% to 4.0%. In steel, in addition to the provisions for limiting S ≦ 15 ppm, O ≦ 20 ppm, and N ≦ 25 ppm, which are impurities in the single cold rolling method, the hot-rolled sheet annealing conditions are prescribed, and the cold rolling rate is regulated to 65% or more. In Japanese Patent Application Laid-Open No. 59-74225, in the second cold rolling method, in addition to the provisions of S ≦ 15 ppm, O ≦ 20 ppm, N ≦ 25 ppm, the intermediate annealing conditions are prescribed and the second cold rolling ratio is set. Each of the technologies defined as 70% or more is disclosed.
However, as in these methods, the technology centered on the purification of steel does not solve the problem peculiar to high-Si non-oriented electrical steel sheets that the magnetic flux density is not sufficiently improved even if the iron loss is improved. It was.
[0006]
Japanese Patent Application Laid-Open No. 54-76422 discloses a hot rolled sheet after finish hot rolling as a technique for increasing the magnetic flux density by coarsening the crystal structure of the non-oriented electrical steel sheet before cold rolling at a low cost. Is a self-annealing method in which the coil is annealed with the retained heat of the coil. A method for recrystallization and grain growth of a hot-rolled structure before winding on a so-called runout table is disclosed.
However, with this technique, even if the crystal grain growth of the hot-rolled structure is attempted, the problem peculiar to the high-Si non-oriented electrical steel sheet that the improvement of the magnetic flux density is still insufficient cannot be solved.
[0007]
JP-A-59-74222 discloses a technique for improving the magnetic properties of high-grade non-oriented electrical steel sheets having a high Si-based component with slow progress of recrystallization and grain growth by controlled hot rolling. A technique is disclosed in which the rolling reduction of the final rolled stand is 20% or more, and the winding temperature of the hot-rolled sheet is 700 ° C. or higher. In this prior application, the final stand reduction ratio is increased to raise the coiling temperature, thereby promoting the recrystallization and grain growth of the hot rolled structure after the completion of hot rolling, and as a result, improving the magnetic properties. . However, when the Si content in the steel sheet is high, the subsequent grain growth is insufficient, and the problem unique to the high Si non-oriented electrical steel sheet that the magnetic flux density is not sufficiently improved has not been solved.
[0008]
On the other hand, in JP-A-56-38420, in order to improve the magnetic properties of a low-grade non-oriented electrical steel sheet having transformation, finish hot rolling is performed at a temperature not higher than the intermediate temperature of the αγ2 phase region and not lower than 750 ° C. The finished controlled hot rolling technology is published. However, the present situation is that the high magnetic flux density non-oriented electrical steel sheet requested by the customer cannot be supplied only by increasing the hot rolling end temperature.
[0009]
[Problems to be solved by the invention]
As described above, in the prior art, the non-oriented electrical steel sheet having a sufficiently high magnetic flux density and low iron loss in both the low grade with a low Si content and the high grade non-oriented electrical steel sheet with a high Si content. However, it was not possible to meet the demands of the above-mentioned customers for non-oriented electrical steel sheets.
An object of the present invention is to provide a method for producing a non-oriented electrical steel sheet having a sufficiently high magnetic flux density and low iron loss.
[0010]
[Means for Solving the Problems]
The present invention is as follows.
(1) In mass%,
0.10% <Si ≦ 3.09%
0.10% ≦ Mn ≦ 1.50%
Slab containing Fe and the inevitable impurities, and hot-rolled into a hot-rolled sheet, used as a product as it is, or subjected to one or more cold rolling sandwiching intermediate annealing. Next, in the method for producing a non-oriented electrical steel sheet, which is subjected to finish annealing, an insulating film is applied, or an end product is not applied, the lubricating oil used during finish hot rolling satisfies the following formula (1), A method for producing a non-oriented electrical steel sheet, wherein the lubricating oil is mixed in roll cooling water so as to satisfy the formula (2) and used for finishing hot rolling lubrication.
200 ≦ ρ ≦ 800 Formula (1)
1.0 ≦ v ≦ 10.0 Formula (2)
Where ρ: kinematic viscosity of the lubricating oil (cSt: centistokes)
v: Volume fraction of lubricating oil mixed in roll cooling water (%)
[0011]
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[0012]
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[0013]
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[0014]
( 2 ) mass %, Further containing 0.10% ≦ Al ≦ 1.00% (1) Description No A method for producing grain-oriented electrical steel sheets.
[0015]
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[0016]
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[0017]
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[0018]
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[0019]
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[0020]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is not limited to the viewpoint of hot rolling end temperature and pass schedule management as seen in the control hot rolling performed in the prior art, but conventionally, the rolling reaction force is reduced and the work roll of the finishing hot rolling machine is reduced. By paying attention to the characteristics of the lubricating oil that has been used for the purpose of extending the service life and appropriately controlling it, the magnetic flux density of the non-oriented electrical steel sheet product is increased.
[0021]
Then, when controlling the characteristics of finish hot rolling lubricating oil as in the present invention, the sheet bar after rough rolling is joined to the preceding sheet bar before finish hot rolling, and the sheet bar is continuously subjected to finish hot rolling. By using this, finishing hot rolling can be stably performed even when a lubricant having a higher kinematic viscosity is used.
[0022]
The present invention is described in detail below.
First, the components will be described. Si is added to increase the specific resistance of the steel sheet, reduce the eddy current loss, and improve the iron loss value. If the Si content is 0.10% or less, the specific resistance cannot be obtained sufficiently, so it exceeds 0.10%. Amount Need to be added. On the other hand, Si content is 3.09 If the percentage exceeds 50%, the cracks at the time of rolling will increase significantly, making rolling difficult and increasing costs. 3.09 % Or less is required.
[0023]
Al, like Si, has the effect of increasing the specific resistance of the steel sheet and reducing eddy current loss, so it is added as necessary. When improving the iron loss value by adding Al, 0.10% or more of Al is added. On the other hand, if the Al content exceeds 1.00%, the magnetic flux density decreases and the cost increases, so the content is made 1.00% or less. In addition, even if the Al content in the steel is less than 0.10%, the effect of the present invention is not impaired at all, but in this case, the effect of improving the iron loss value by adding Al cannot be expected.
[0024]
Mn, like Al and Si, has the effect of increasing the specific resistance of the steel sheet and reducing eddy current loss. For this purpose, the Mn content is 0.10% or more. On the other hand, if the Mn content exceeds 1.50%, deformation resistance at the time of hot rolling increases and hot rolling becomes difficult, and the crystal structure after hot rolling is easily refined and the magnetic properties are deteriorated. The amount needs to be 1.50% or less.
The amount of Mn added is also extremely important from the viewpoint of securing the strength of the high-temperature sheet bar joint before hot rolling. This is because the low melting point sulfide is present at the crystal grain boundary to prevent hot embrittlement of the sheet bar joint. For this reason, it is preferable that the value of Mn / S which is the ratio of the weight concentration of Mn and S is 20 or more. Thereby, the low melting point sulfide becomes coarse, and it becomes possible to prevent breakage of the seat bar joint.
[0025]
In addition, one or more of P, B, Ni, Cr, Sb, Sn, and Cu are contained in steel for the purpose of improving the mechanical properties, magnetic properties, rust resistance of products, and other purposes. Even if it is made to contain, the effect of this invention is not impaired.
[0026]
The content of C is not particularly limited, but in order to prevent magnetic aging during use and maintain good iron loss, the C content is 0.0050% or less, more preferably 0.0020% or less. Preferably there is. On the contrary, in an application where an increase in iron loss due to magnetic aging during use does not become a problem, this value may be exceeded. Furthermore, the C content may be adjusted in the range of 100 to 300 ppm in order to ensure the hardness at the time of punching and to improve the punchability at the consumer.
[0027]
Although there is no particular limitation on the contents of S and N, these elements are partly re-dissolved during slab heating in the hot rolling process, and sulfides such as MnS and nitrides such as AlN are added during hot rolling. Form. The presence of these hinders the grain growth of the hot rolled structure and deteriorates the iron loss, so S is 0.0050%, more preferably 0.0020% or less, and N is 0.0050% or less, more preferably 0.0020. % Or less.
In particular, as described above, the S content preferably has a value of Mn / S, which is the ratio of the weight concentration of Mn and S, of 20 or more in order to ensure the strength of the sheet bar joint.
[0028]
Next, the process conditions of the present invention will be described.
The steel slab composed of the above components is melted in a converter and manufactured by continuous casting or ingot-bundling rolling. The steel slab is heated by a known method. The slab is subjected to rough rolling to form a sheet bar, which is subsequently subjected to finish hot rolling to obtain a hot rolled sheet.
[0029]
In the present invention, the kinematic viscosity of the lubricating oil used in the finish hot rolling satisfies the following formula (1), and the lubricating oil is mixed in roll cooling water so as to satisfy the formula (2). It is characterized by being used for hot rolling lubrication.
200 ≦ ρ ≦ 800 Formula (1)
1.0 ≦ v ≦ 10.0 Formula (2)
Where ρ: kinematic viscosity of the lubricating oil (cSt: centistokes)
v: Volume fraction of lubricating oil mixed in roll cooling water (%)
[0030]
At this time, since the kinematic viscosity of the lubricating oil decreases exponentially with respect to the temperature rise, it is necessary to appropriately control not only the temperature of the lubricating oil itself but also the temperature of the roll cooling water. In the present invention, it is important that the kinematic viscosity of the lubricating oil when mixed with roll cooling water and actually used for lubrication satisfies the value of the formula (1) or the formula (3). Further, v denotes the volume fraction of the lubricating oil in the mixed liquid of roll cooling water and lubricating oil that is actually used for the lubrication of the finish hot rolling.
[0031]
Here, the lubricating oil used in the present invention will be described.
Lubricating oils used in finish hot rolling are usually composed of components such as base oils, extreme pressure additives, adhesion improvers, and oiliness agents as main components. A refined mineral oil is usually used as the base oil.
[0032]
The oily agent is composed of a nonpolar hydrocarbon group and a polar group, and the hydrocarbon group bears affinity with the base oil molecule that is the main component of the lubricating oil. On the other hand, since the polar group of the oily agent has affinity with the metal and water molecules as the material to be rolled, the oily agent adsorbs to the metal and water to form an adsorption film on the metal surface. This adsorption film suppresses friction and wear between the steel sheet and the work roll when the load is low. As the oily agent, various fats and oils represented by long chain fatty acids such as oleic acid, various synthetic oils and the like are used.
[0033]
Extreme pressure additives act when the load increases. When the load increases, some metal breaks through the adsorption film and comes into direct contact with the roll, and the heat generated by frictional heat raises the roll temperature to cause further destruction of the adsorption film, causing seizure and scuffing. The extreme pressure additive is added for the purpose of preventing lubrication of the metal surface in such a lubrication state and enabling lubrication. Phosphate ester polymer, metal dithiophosphate salt, organic sulfur compound Organic halogen compounds and the like are used.
[0034]
The adhesion improver is added for the purpose of improving the adhesion of the lubricating oil to the surface of the work roll and the surface of the hot-rolled steel piece, and usually a hydrocarbon polymer or the like is used.
[0035]
Recently, in order to increase the viscosity of the lubricating oil and improve the roll life, a lubricating oil composed of a component system in which the viscosity of the extreme pressure additive is increased and the oily agent is omitted is also used.
[0036]
Examples of the lubricating oils that have been described above are Cudoll 5149, Cudoll 0B068, and Cudoll 4B313 (all trade names of Kyodo Yushi Co., Ltd.).
[0037]
However, in the present invention, the magnetic flux density of the non-oriented electrical steel sheet is improved by appropriately controlling the kinematic viscosity of the lubricating oil used during finish hot rolling and the concentration in the roll cooling water. is there. Therefore, the lubricating oil used when practicing the present invention is not limited to the one constituted by the component system described above.
[0038]
When finishing hot rolling using a lubricating oil having a high kinematic viscosity as in the present invention, a single slab is roughly rolled into one sheet bar, and when this is rolled one by one, It becomes easy for the seat bar to be bitten. In order to solve this problem, there is a method of reducing the speed when the seat bar is jammed, but the productivity is remarkably impaired. As a result of diligent studies to solve this problem, the inventors joined the leading end of the sheet bar obtained by rough rolling the slab to the trailing end of the preceding sheet bar to form a plurality of sheet bars. It has also been found that it is particularly effective to integrate the plurality of integrated sheet bars and subject them to continuous hot rolling. In other words, it is possible to prevent the biting failure by continuous hot rolling and to stably perform finish hot rolling.
[0039]
As a method of joining the preceding seat bar and the succeeding seat bar, the rear end portion of the preceding seat bar and the leading end of the succeeding seat bar are abutted and the abutting portion is welded. And a method of pressure welding after welding the butt portion. Further, welding may be performed while applying a pressing force to the butt portion. In addition, as a method of welding a butt | matching part, the method by the laser welding method, induction heating, etc. are mention | raise | lifted, for example.
[0040]
Hot rolled sheets that are continuously manufactured by finishing hot rolling are installed by placing multiple pinch rolls in front of the coiler at the time of winding, performing high-speed shearing between them, and winding the coils in order, so that the finishing heat It is possible to minimize the fluctuation of the tension applied to the hot-rolled sheet during rolling and wind it up in a good shape.
[0041]
The obtained hot-rolled sheet can be used as it is as a product by omitting cold rolling, especially for customers who place importance on low cost, or it can be pickled to obtain a product. The product may be made as it is or after light pressure is applied to improve the surface properties, and then the insulating film is applied or not applied. When producing a non-oriented electrical steel sheet by such a so-called hot final process, when the component system has an αγ transformation point, the finish hot rolling finish temperature is 800 ° C. or higher ((3 × Ar ₁ +2 x Ar ₃ ) / 5) It is preferable that the hot-rolled sheet is wound in a temperature range of 600 ° C. or higher and 850 ° C. or lower.
[0042]
In the case of a component-type hot final non-oriented electrical steel sheet having an αγ transformation point, if the finishing temperature of the finish hot rolling is less than 800 ° C., the high magnetic flux density intended by the present invention cannot be obtained, so the finish hot rolling is finished. The temperature is preferably 800 ° C. or higher. On the other hand, the finish hot rolling end temperature is ((3 × Ar ₁ +2 x Ar ₃ ) / 5) If it exceeds ° C., the γ phase present in the steel sheet after hot rolling is transformed into a fine α phase upon cooling, the crystal structure of the hot rolled sheet is refined, and the magnetic properties are greatly deteriorated. Therefore, the finish hot rolling finish temperature is ((3 × Ar ₁ +2 x Ar ₃ ) / 5) It is preferable that it is below ℃. Moreover, about coiling temperature, since the high magnetic flux density unidirectional electrical steel plate which this invention intends is less than 600 degreeC, it is preferable that it is 600 degreeC or more. On the other hand, if the coiling temperature exceeds 850 ° C., the oxidized layer on the surface of the coiled hot rolled sheet increases and the pickling cost increases. Therefore, the coiling is preferably performed in a temperature range of 850 ° C. or less.
[0043]
On the other hand, in the case of a component-type hot final non-oriented electrical steel sheet having no αγ transformation point, if the finishing temperature of finish hot rolling is less than 800 ° C., the high magnetic flux density intended by the present invention cannot be obtained, so the finish heat The end temperature of the rolling is preferably 800 ° C. or higher. On the other hand, if the finish hot rolling finish temperature exceeds 1100 ° C., the winding of the steel sheet becomes extremely difficult, and coil winding deviation and shape defects are likely to occur. Therefore, the finish hot rolling finish temperature is 1100 ° C. or less. Is preferred. Moreover, about coiling temperature, since the high magnetic flux density unidirectional electrical steel plate which this invention intends is less than 600 degreeC, it is preferable that it is 600 degreeC or more. On the other hand, if the coiling temperature exceeds 850 ° C., the oxidized layer on the surface of the coiled hot rolled sheet increases and the pickling cost increases.
[0044]
In addition, the hot-rolled sheet obtained by the finish hot rolling of the present invention should be cold-rolled twice or more with one time or intermediate annealing, and then subjected to finish annealing, or to further improve the magnetic properties. The purpose is to perform hot-rolled sheet annealing by continuous annealing or box annealing before the first cold rolling, or coil the coil at high temperature and perform self-annealing with the retained heat, or finish hot rolling at a high temperature and keep constant It is good also as a product by the method of setting the above non-water-filling time, cooling and winding up after that, and using for cold rolling.
[0045]
The hot-rolled sheet obtained by the above steps may be subjected to a single cold rolling step and then subjected to finish annealing, or may be further subjected to a skin pass rolling step to obtain a product. If the skin pass rolling rate is less than 2%, the effect cannot be obtained. If the skin pass rolling rate exceeds 20%, the magnetic properties deteriorate, so the range is set from 2% to 20%.
The finish annealing is performed by continuous annealing. At that time, as disclosed in JP-A-61-231120, the annealing is performed for a short time of 5 seconds to 1 minute in the temperature range of 950 ° C. to 1100 ° C. Further, finish annealing may be performed by a method such as holding at 800 ° C. to 950 ° C. for 10 seconds to 2 minutes in the subsequent stage.
[0046]
The steel sheet after cold rolling is either finished with or without an insulating coating.
[0047]
Hereinafter, the reasons for defining each process defined by the present invention will be described.
First, the process conditions of the present invention when hot-rolled sheet annealing is omitted will be described. The following experiment was conducted to investigate the influence of the kinematic viscosity of the lubricating oil and the concentration of the lubricating oil in the roll cooling water on the product magnetic flux density during the finish hot rolling. Steels having the components shown in Table 1 were melted to form slabs, subjected to rough hot rolling to form sheet bars, and then finish hot rolling was performed.
[0048]
[Table 1]

[0049]
During finish hot rolling, tests were performed by changing the kinematic viscosity of the lubricating oil that was actually sprayed on the roll and the volume fraction of the roll cooling water, and the relationship with the product magnetic flux density was investigated in detail. Ar of component steel A with αγ transformation point ₃ The point is 904 ° C and Ar ₁ The point is 870 ° C. For this reason, the hot rolling finishing temperature of steel A is (Ar ₃ + Ar ₁ ) / 2 ° C. or lower and 700 ° C. or higher. On the other hand, the steel B of the component system having no αγ transformation point has a hot rolling end temperature of 880 ° C. Both steels A and B were finished into 2.5 mm thick hot-rolled sheets, then cooled with water and wound at 550 ° C.
[0050]
Next, these hot-rolled sheets were pickled, cold-rolled to a thickness of 0.50 mm, degreased, steel A was annealed at 750 ° C. for 30 seconds, Epstein samples were cut, and magnetic properties were measured. Steel B was pickled and cold rolled to a thickness of 0.50 mm, degreased, annealed at 950 ° C. for 30 seconds, cut an Epstein sample, and measured for magnetic properties.
[0051]
FIG. 1 shows the relationship between the kinematic viscosity of the lubricating oil during finish hot rolling, the concentration of the lubricating oil in the roll cooling water, and the product magnetic flux density, and FIG. 2 shows the experimental result of steel B. According to FIG. 1 and FIG. 2, the volume fraction of the lubricating oil with respect to the roll cooling water is 1.0%. more than It can be seen that the product magnetic flux density increases in both steel A and steel B by setting the kinematic viscosity of the lubricating oil to 200 cSt or more when the viscosity is 10% or less.
[0052]
As shown in FIG. 1 and FIG. 2, the kinematic viscosity of the lubricating oil is 200 cSt Less than However, the effect of improving the magnetic flux density of the product is insufficient. If the kinematic viscosity of the lubricating oil exceeds 800 cSt, the effect is saturated and the piping system that conveys the lubricating oil having a high kinematic viscosity is likely to be clogged, and the cooled lubricating oil adheres to the stand or roll. Since the operation must be frequently stopped for the removal, the kinematic viscosity of the lubricating oil is set to 800 cSt or less.
[0053]
Moreover, the volume fraction of the lubricating oil with respect to the roll cooling water is 1.0%. Less than Since there is no effect of improving the magnetic flux density, if it exceeds 10%, the effect is saturated and uneconomical, so the lubricating oil concentration in the roll cooling water is 1.0% in terms of volume fraction. more than 10% or less.
[0054]
As shown from the above experiment, in the finish hot rolling, the kinematic viscosity of the lubricating oil injected into the work roll is (1) It can be seen that the product magnetic flux density increases when the lubricating oil concentration in the roll cooling water is within the range defined by Equation (2).
[0055]
Next, in order to investigate the influence of the kinematic viscosity of the lubricating oil during finish hot rolling and the concentration of the lubricating oil in the roll cooling water on the product magnetic properties when hot-rolled sheet annealing is performed before cold rolling, the following is performed. Experiments were conducted. Steels having the components shown in Table 2 were melted and subjected to finish hot rolling.
During finish hot rolling, tests were performed by changing the kinematic viscosity of the lubricating oil that was actually sprayed on the roll and the volume fraction of the roll cooling water, and the relationship with the product magnetic flux density was investigated in detail. The hot-rolled sheet was finished at a finish hot-rolling temperature of 900 ° C., finished to 2.5 mm in thickness, and wound at 550 ° C.
[0056]
This hot-rolled coil was annealed at 950 ° C. for 90 seconds in a continuous annealing furnace. This was pickled, cold rolled to 0.35 mm thickness, degreased, annealed at 950 ° C. for 30 seconds, cut out an Epstein sample, and measured for magnetic properties.
[0057]
FIG. 3 shows the relationship between the kinematic viscosity of the lubricating oil during finish hot rolling of steel C, the concentration of the lubricating oil in the roll cooling water, and the product magnetic flux density. According to FIG. 3, the volume fraction of the lubricating oil with respect to the roll cooling water is 1.0%. more than It can be seen that the product magnetic flux density of Steel C increases when the lubricant viscosity is 10% or less and the kinematic viscosity of the lubricating oil is 200 cSt or more.
As shown from the above experiments, in the finish hot rolling, the lubricating oil in the roll cooling water so that the kinematic viscosity of the lubricating oil injected to the work roll satisfies the formula (1) and is defined by the formula (2). Concentration is 1.0% in volume fraction more than It can be seen that the product magnetic flux density is increased if it is less than 10%.
[0058]
Next, in order to investigate the influence of the hot rolled sheet annealing time and the hot rolled sheet annealing temperature on the magnetic flux density by continuous annealing, the following experiment was conducted. Steel C having the components shown in Table 2 was melted into a slab, subjected to rough hot rolling to form a sheet bar, and then finish hot rolling was performed.
[0059]
[Table 2]

[0060]
The finish hot rolling finish temperature was 900 ° C. and a constant thickness of 2.0 mm, and after the hot rolling was finished, it was cooled rapidly and wound at 500 ° C. 3% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine and sprayed from the nozzle onto the work roll. The temperature of the roll cooling water was kept at 55 ° C., and the kinematic viscosity of the lubricating oil was kept at 280 cSt.
This hot-rolled coil was annealed in a continuous annealing furnace with the annealing temperature constant at 950 ° C. and changing the annealing time. On the other hand, the annealing temperature was changed by setting the time for hot-rolled sheet annealing by continuous annealing to 90 seconds. This was pickled, cold-rolled to a thickness of 0.35 mm, degreased, annealed at 900 ° C. for 30 seconds, cut an Epstein sample, and measured for magnetic properties.
[0061]
FIG. 4 shows the influence of the hot-rolled sheet annealing time by continuous annealing on the product magnetic flux density. As shown in FIG. 4, if the annealing time is less than 20 seconds, the effect of improving the magnetic flux density by hot-rolled sheet annealing cannot be obtained, and if the annealing time is 5 minutes or more, a deep scale is generated on the steel sheet surface, resulting in pickling failure. Significant skin roughness occurred on the steel sheet surface layer. For this reason, in this invention, the hot-rolled sheet annealing time by continuous annealing shall be 20 second or more and 5 minutes or less. In addition, the hot-rolled sheet annealing time by the preferable continuous annealing seen from the effect of annealing and economical efficiency is 30 second or more and 3 minutes or less.
[0062]
FIG. 5 shows the influence of the hot-rolled sheet annealing temperature by continuous annealing on the product magnetic flux density. As shown in FIG. 5, if the annealing temperature is less than 850 ° C., the effect of improving the magnetic flux density by hot-rolled sheet annealing in continuous annealing cannot be obtained, and if the annealing temperature exceeds 1150 ° C., pickling defects are caused by the generation of deep scale. It occurred and marked skin roughening occurred on the steel sheet surface layer. For this reason, in this invention, the hot-rolled sheet annealing temperature by continuous annealing shall be 850 degreeC or more and 1150 degrees C or less. The hot-rolled sheet annealing temperature by preferable continuous annealing in view of the effect of annealing and economic efficiency such as pickling is 850 ° C. or more and 1000 ° C. or less.
[0063]
In the present invention, hot-rolled sheet annealing may be performed by box annealing. At that time, if the hot-rolled sheet annealing temperature is less than 750 ° C., the annealing time required for improving the magnetic properties of the product becomes remarkably long, which is uneconomical. Further, if the annealing temperature exceeds 850 ° C., a large amount of cost is required for the capital investment of the furnace, and a phenomenon that the coil is seized during annealing occurs. For the above reasons, when performing hot-rolled sheet annealing by box annealing, the annealing temperature is set to 750 ° C. or higher and 850 ° C. or lower. At that time, if the hot-rolled sheet annealing time in the box annealing is 5 minutes or less, the annealing temperature necessary for improving the product magnetic properties becomes remarkably high, and the equipment investment of the furnace itself becomes excessive and uneconomical, so the annealing time is 5 minutes or more. Further, when the hot-rolled sheet annealing time exceeds 30 hours, coil seizure occurs as in the case where the annealing temperature is excessively high. Therefore, the hot-rolled sheet annealing time in the box annealing is set within 30 hours.
[0064]
Next, in order to investigate the influence of the kinematic viscosity of the lubricating oil during finish hot rolling and the concentration of the lubricating oil in the roll cooling water on the product magnetic properties in the process of self-annealing by the heat retained in the hot-rolled coil, the following Experiments were conducted. Steels having the components shown in Table 3 were melted to form slabs, subjected to rough hot rolling to form sheet bars, and then finish hot rolling was performed. 4% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine and sprayed from the nozzle onto the work roll. At this time, the kinematic viscosity of the lubricating oil was changed by changing the temperature of the roll cooling water.
[0065]
[Table 3]

[0066]
The hot rolling end temperature was 1000 ° C., water-cooled, wound up at 860 ° C., immediately covered with a heat retaining cover, subjected to auxiliary heating by gas heating, and self-annealed at 850 ° C. for 1 hour with the retained heat of the coil.
This was pickled, cold-rolled to a thickness of 0.50 mm, degreased, steel D was annealed at 900 ° C. and steel E was annealed at 980 ° C. for 45 seconds, and an Epstein sample was cut to measure magnetic properties.
[0067]
FIG. 6 shows the dependence of the product magnetic flux density on the kinematic viscosity of the lubricating oil during finish hot rolling. Fig. 6 shows the kinematic viscosity of the lubricating oil during finish hot rolling. 200 It can be seen that the product magnetic flux density increases when it is greater than or equal to cSt.
[0068]
After finishing hot rolling, the hot-rolled sheet may be wound around a coil and self-annealed. If the coil winding temperature during self-annealing is less than 750 ° C., the improvement of the magnetic properties is insufficient, so it is set to 750 ° C. or higher. On the other hand, if the temperature exceeds 1000 ° C., coil winding is likely to occur, and oxidation of the steel sheet surface layer becomes violent.
[0069]
If the self-annealing time is less than 5 minutes, the improvement of the magnetic properties is insufficient, so it is performed for 5 minutes or more. Further, if it exceeds 5 hours, oxidation of the steel sheet becomes violent and pickling failure tends to occur, so it is set to 5 hours or less. The preferable self-annealing time from the viewpoint of the effect of annealing and economy is 30 minutes to 120 minutes. In order to prevent oxidation of the coil during self-annealing, self-annealing may be performed in a reducing atmosphere containing hydrogen, an inert gas atmosphere such as nitrogen or argon, or under reduced pressure.
[0070]
Next, in order to investigate the influence of the kinematic viscosity of the lubricating oil during finish hot rolling and the concentration of the lubricating oil in the roll cooling water on the product magnetic properties in the process of providing non-injection water for a certain period of time after finishing hot rolling, Various experiments were conducted. Steel F having the components shown in Table 4 was melted and finish hot rolled.
[0071]
[Table 4]

[0072]
The finish hot rolling finish temperature was constant at 1050 ° C. At this time, 1.5% of lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine, and sprayed from the nozzle to the work roll. At this time, the kinematic viscosity of the lubricating oil was changed by changing the temperature of the roll cooling water. Moreover, based on Formula (4) and Formula (5), the non-water-filling time was 4.0 second, and it cooled after that and wound up at 680 degreeC.
This was pickled, cold-rolled to a thickness of 0.50 mm, degreased, annealed at 900 ° C. for 30 seconds, cut an Epstein sample, and measured for magnetic properties.
[0073]
The dependence of the product magnetic flux density on the kinematic viscosity of the lubricating oil during finish hot rolling is shown in FIG. Fig. 7 shows the kinematic viscosity of the lubricating oil during finish hot rolling. 200 It can be seen that the product magnetic flux density increases when it is greater than or equal to cSt.
[0074]
Although there is no provision for coiling temperature, coiling should be performed at 750 ° C. or lower in order to prevent an excessive oxidation layer from being generated on the surface of the steel sheet that has been hot-rolled at a high temperature and deterioration of pickling properties. Is preferred.
[0075]
Hereinafter, the non-injection water set time t after the end of hot rolling will be described.
In the present invention, the influence of the kinematic viscosity of the lubricating oil during the finish hot rolling and the concentration of the lubricating oil in the roll cooling water on the product magnetic properties is investigated, and the hot rolling end temperature T (° C.) and the hot rolling end in the finish hot rolling. As a result of detailed studies by the inventors on the relationship between the time t (seconds) until the start of post-water injection and the magnetic properties,
950 ≦ T ≦ 1150 Formula (4)
9.6-8 × 10 ^-3 T ≦ t ≦ 15.6-8 × 10 ^-3 T ... Formula (5)
In the range determined by (1), it is possible to define favorable conditions satisfying pickling properties, sheet feeding speed, and magnetic characteristics.
[0076]
When the hot rolling end temperature T (° C.) is lower than the lower limit 950 ° C. defined by the formula (4), the improvement of the magnetic properties is insufficient. Further, in order to make the hot rolling end temperature T (° C.) exceed 1150 ° C. which is the upper limit determined by the formula (4), the heating temperature of the slab is remarkably increased in the hot rolling process having normal rough rolling and finish rolling. It is necessary, and precipitates re-dissolved during slab heating are finely precipitated during hot rolling, and the magnetic properties are remarkably deteriorated. For the above reasons, the hot rolling end temperature is set to 950 ° C. or more and 1150 ° C. or less determined by the equation (4).
[0077]
In addition, when the time from the end of hot rolling to the start of water injection exceeds the time determined by Equation (5), the time for cooling the steel sheet is insufficient, and the rolling speed is sufficient to wind the coil at a high temperature or to sufficiently cool the steel sheet. Must be reduced, and productivity deteriorates. Winding the coil at a high temperature is not preferable because it causes adverse effects such as occurrence of winding deviation and deterioration of pickling properties. For this reason, the non-water-filling time t (seconds) is 15.6-8 × 10 as defined in the equation (5). ^-3 T or less. On the contrary, if the non-injection time is shorter than the time determined by the equation (5), the improvement of the magnetic characteristics is insufficient. For this reason, the non-water-filling time t (seconds) after the finish hot rolling is finished is 9.6-8 × 10 as defined by the equation (5). ^-3 T or more.
[0078]
【Example】
Next, examples of the present invention will be described.
[Example 1]
Investigate the effect of the kinematic viscosity of the lubricating oil during finish hot rolling and the concentration of the lubricating oil in the roll cooling water on the product magnetic properties of a full-process material manufactured by the single cold rolling process method that omits hot-rolled sheet annealing. Therefore, the following experiment was conducted.
Here, a full process material refers to the product manufactured in the process of giving annealing and making it a final product after cold rolling of 2 times or more which interposes intermediate annealing.
A slab for non-oriented electrical steel having the components shown in Table 5 was heated by a normal method to form a sheet bar having a thickness of 40 mm by a rough rolling mill, and then a hot rolled sheet having a thickness of 2.5 mm by a finishing hot rolling machine. did.
[0079]
[Table 5]

[0080]
Since Steel G and Steel H have αγ transformation, the hot rolling finishing temperature is (Ar ₃ + Ar ₁ ) / 2 or less and 700 ° C. or more and 860 ° C., water cooled and wound up at 650 ° C. The hot rolling finish temperature of Steel I was 890 ° C., water cooled, and wound up at 650 ° C.
4% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine and sprayed from the nozzle onto the work roll. The kinematic viscosity of the lubricating oil was changed by changing the temperature of the roll cooling water and the type of the lubricating oil.
[0081]
In this embodiment, the finish hot rolling is performed using a high kinematic viscosity lubricating oil, so that the individual seat bars tend to be poorly mixed. Become In order to stably perform finish hot rolling, the sheet bar after rough rolling was welded to the preceding sheet bar, and finish hot rolling was continuously performed.
[0082]
After pickling these steels, steel G was annealed at 750 ° C., steel H was 830 ° C., and steel I was annealed at 950 ° C. for 30 seconds, and an Epstein sample was cut out to measure the magnetic flux density. Table 6 shows the present invention, comparative examples, and magnetic measurement results together. As shown in Table 6, the kinematic viscosity of the lubricating oil during finish hot rolling 200 It turns out that a product magnetic flux density improves that it is more than cSt.
[0083]
[Table 6]

[0084]
[Example 2]
The following experiment was conducted to investigate the effect of the concentration of lubricating oil during finish hot rolling on the product magnetic properties in a full-process material manufactured by the single cold rolling process method, omitting hot-rolled sheet annealing. .
A slab for non-oriented electrical steel having the components shown in Steel I in Table 5 is heated by a normal method to form a sheet bar having a thickness of 40 mm by a rough rolling mill, and then heated to 2.5 mm by a finishing hot rolling machine. It was a sheet.
The temperature of the roll cooling water of the finishing hot rolling machine is adjusted to 40 ° C, 50 ° C, 70 ° C, and lubricant oils with different volume fractions are mixed in advance in the state of emulsion in the roll cooling water. The effects on the At this time, the kinematic viscosity of the lubricating oil at each temperature is 400 cSt, 300 cSt there were. Roll cooling water containing lubricating oil was sprayed from the nozzle to the work roll.
[0085]
After this steel I was pickled, it was annealed at 950 ° C. for 30 seconds, an Epstein sample was cut out, and the magnetic flux density was measured. Table 7 shows the present invention, comparative examples, and magnetic measurement results together. As shown in Table 7, the concentration of lubricating oil during finish hot rolling is 1.0%. more than It can be seen that the product magnetic flux density is improved.
[0086]
[Table 7]

[0087]
[Example 3]
In order to investigate the influence of the kinematic viscosity of lubricating oil during finish hot rolling and the concentration of lubricating oil in roll cooling water on product magnetic properties in full-process and semi-processed materials by hot-rolled sheet annealing, the following The experiment was conducted.
Here, the semi-process material refers to a product in a manufacturing method in which a final product is obtained after performing cold rolling at least once with intermediate annealing or annealing, and then applying a skin pass.
A slab for non-oriented electrical steel having the components shown in Table 8 is heated by a normal method to form a sheet bar having a thickness of 40 mm by a rough rolling mill, and then a hot rolled sheet having a thickness of 2.0 mm by a finishing hot rolling machine. did. The finish hot rolling finish temperature was 900 ° C., and immediately after the hot rolling was finished, the product was cooled with water and the hot rolled plate was wound up at 550 ° C.
[0088]
[Table 8]

[0089]
3.5% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine and sprayed from the nozzle onto the work roll. The kinematic viscosity of the lubricating oil was changed by changing the temperature of the roll cooling water and the type of the lubricating oil.
In this embodiment, since the hot rolling is performed using a high kinematic viscosity lubricating oil, rough rolling is performed in order to avoid the tendency of individual sheet bars to become jammed and to stably perform the hot rolling. The subsequent sheet bar was welded to the preceding sheet bar, and finish hot rolling was continuously performed.
[0090]
The obtained hot-rolled sheet was subjected to hot-rolled sheet annealing in a continuous annealing furnace at 900 ° C. for steel J and 1000 ° C. for steel K for 2 minutes. Thereafter, the full process and semi-process characteristics of Steel J and the full process characteristics of Steel K were investigated.
[0091]
As a full process step for Steel J and Steel K, the hot-rolled sheet after hot-rolled sheet annealing was pickled and finished to 0.50 mm by cold rolling. In a continuous annealing furnace, steel J was annealed at 900 ° C. and steel K was annealed at 980 ° C. for 30 seconds. Thereafter, the Epstein sample was cut out and the magnetic properties were measured.
[0092]
Furthermore, as a semi-process step for steel J, the same conditions are applied until hot-rolled sheet annealing and pickling, and then the finished sheet thickness of cold rolling is 0.55 mm, and this is annealed at 900 ° C. for 30 seconds in a continuous annealing furnace. did. Thereafter, skin pass rolling was performed to finish to 0.50 mm, and the Epstein sample was cut, and then subjected to strain relief annealing at 750 ° C. for 2 hours, which is usually performed by a customer, and the magnetic properties were measured.
[0093]
Table 9 shows the components of the present invention and comparative examples of steel J and steel K, and the magnetic measurement results. As shown in Table 9, it can be seen that the product magnetic flux density is improved when the kinematic viscosity of the lubricating oil during finish hot rolling is 80 cSt or more, particularly 200 cSt or more.
[0094]
[Table 9]

[0095]
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[0096]
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[0097]
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[0098]
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[0099]
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[0100]
[Example 5]
Product magnetic properties of kinematic viscosity of lubricating oil during finish hot rolling and concentration of lubricating oil in roll cooling water in full-process non-oriented electrical steel sheet manufactured by hot-rolled sheet annealing / single cold rolling method by box annealing The following experiment was conducted to investigate the effect on the.
A slab for non-oriented electrical steel having the components shown in Table 12 was heated by a normal method to form a sheet bar having a thickness of 40 mm by a rough rolling mill, and then a hot rolled sheet having a thickness of 2.0 mm by a finishing hot rolling machine. did. The finish hot rolling finish temperature was 900 ° C., and after finishing the rolling, it was cooled and wound up at 650 ° C.
[0101]
[Table 12]

[0102]
4.0% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine and sprayed from the nozzle onto the work roll. The kinematic viscosity of the lubricating oil was changed by changing the temperature of the roll cooling water and the type of the lubricating oil.
The obtained hot-rolled sheet was subjected to hot-rolled sheet annealing in a box annealing furnace at 800 ° C. for 5 hours. Then, pickling was performed and it finished in 0.50 mm thickness by cold rolling. In a continuous annealing furnace, steel M was annealed at 900 ° C. for 30 seconds, and steel N was annealed at 980 ° C. for 30 seconds. Thereafter, the Epstein sample was cut out and the magnetic properties were measured.
[0103]
Table 13 shows the components of the present invention and comparative examples and the magnetic measurement results. As shown in Table 13, the kinematic viscosity of the lubricating oil during finish hot rolling 200 It turns out that a product magnetic flux density improves that it is more than cSt.
[0104]
[Table 13]

[0105]
[Example 6]
To investigate the effect of lubricant kinematic viscosity during finish hot rolling and the concentration of lubricant in roll cooling water on product magnetic properties in full-process non-oriented electrical steel sheets produced by a single cold rolling process of self-annealing process Therefore, the following experiment was conducted. A slab for non-oriented electrical steel having the components shown in Table 14 was heated by a normal method to form a sheet bar having a thickness of 50 mm by a rough rolling mill, and then a hot rolled sheet having a thickness of 2.5 mm by a finishing hot rolling machine. did.
[0106]
[Table 14]

[0107]
A 3.0% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine and sprayed from the nozzle onto the work roll. The kinematic viscosity of the lubricating oil was changed by changing the temperature of the roll cooling water and the type of the lubricating oil.
The finish hot rolling finish temperature was 1000 ° C., and after completion of rolling, the product was cooled and wound up at 875 ° C., and the coil was immediately placed in a heat-retaining furnace and subjected to self-annealing at 850 ° C. for 1 hour. Then, pickling was performed and it finished in 0.50 mm thickness by cold rolling. In a continuous annealing furnace, steel O was annealed at 950 ° C. for 30 seconds, steel P was annealed at 975 ° C. for 30 seconds, and steel Q was annealed at 850 ° C. for 30 seconds. Thereafter, the Epstein sample was cut out and the magnetic properties were measured.
[0108]
Table 15 shows the components of the present invention and comparative examples and the magnetic measurement results. As shown in Table 15, kinematic viscosity of lubricating oil during finish hot rolling 200 It turns out that a product magnetic flux density improves that it is more than cSt.
[0109]
[Table 15]

[0110]
[Example 7]
In a full-process non-oriented electrical steel sheet manufactured by a single cold rolling method with a non-water injection time of a certain time after finish hot rolling, the kinematic viscosity of the lubricating oil mixed in the roll cooling water during finish hot rolling In order to investigate the influence on the product magnetic properties, the following experiment was conducted.
A slab for non-oriented electrical steel having the components shown in Table 16 was heated by a normal method, and a sheet bar having a thickness of 50 mm was formed by a rough rolling mill, and then a sheet bar having a thickness of 2.5 mm was formed by a finishing hot rolling machine. .
[0111]
[Table 16]

[0112]
3.2% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine, and sprayed from the nozzle onto the work roll. The kinematic viscosity of the lubricating oil was changed by changing the temperature of the roll cooling water and the type of the lubricating oil.
The finish hot rolling finish temperature was 1020 ° C. In this case, since the non-water-filling time t defined by the formulas (4) and (5) is 1.44 seconds or more and 7.44 seconds or less, the non-water-filling time is 4.5 seconds and winding is performed at 640 ° C. It was. Thereafter, pickling was performed, and the thickness was reduced to 0.50 mm by cold rolling. In the continuous annealing furnace, steel R was annealed at 950 ° C. and steel S was annealed at 980 ° C. for 30 seconds. Thereafter, the Epstein sample was cut out and the magnetic properties were measured.
[0113]
Table 17 shows the components of the present invention and comparative examples and the magnetic measurement results. As shown in Table 17, kinematic viscosity of lubricating oil during finish hot rolling 200 It turns out that a product magnetic flux density improves that it is more than cSt.
[0114]
[Table 17]

[0115]
[Example 8]
In order to investigate the effect of non-water-injection time on product magnetic properties in full-process non-oriented electrical steel sheets manufactured by a single cold-rolling method with a non-injection time of a certain time after finish hot rolling, the following experiment was conducted. went.
A slab for non-oriented electrical steel having the components shown in Table 18 was heated by a normal method to form a sheet bar having a thickness of 50 mm by a rough rolling mill, and then a hot rolled sheet having a thickness of 2.5 mm by a finishing hot rolling machine. did.
[0116]
[Table 18]

[0117]
The hot rolling end temperature was 1050 ° C., the non-water injection time was changed, and the coiling temperature was constant at 680 ° C. In this case, the non-water-filling time defined by the equations (4) and (5) is 1.2 seconds or more and 7.2 seconds or less.
3.2% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine, and sprayed from the nozzle onto the work roll. The kinematic viscosity of the lubricating oil was 320 cSt. Thereafter, pickling was performed, and the thickness was reduced to 0.50 mm by cold rolling. This was annealed at 900 ° C. for 30 seconds in a continuous annealing furnace. Thereafter, the Epstein sample was cut out and the magnetic properties were measured.
[0118]
Table 19 shows hot rolling conditions and magnetic measurement results together. As shown in Table 19, it can be seen that good magnetic properties are obtained when the non-water injection time is 1.2 seconds or longer.
[0119]
As described above, the kinematic viscosity of the lubricating oil during finish hot rolling and the concentration in the roll cooling water are appropriately controlled, and the finish hot rolling is finished at a high temperature, and then the non-injection time after the hot rolling is properly controlled. Thus, it is possible to obtain a non-oriented electrical steel sheet having a high magnetic flux density.
[0120]
[Table 19]

[0121]
[Example 9]
Product magnetic properties of kinematic viscosity of lubricating oil during finishing hot rolling and concentration of lubricating oil in roll cooling water in the manufacturing process of non-oriented electrical steel sheet to be finished product after finishing hot rolling without cold rolling The following experiment was conducted to investigate the effect on the.
A slab for non-oriented electrical steel having the components shown in Table 20 was heated by a normal method to form a sheet bar having a thickness of 40 mm by a rough rolling mill, and then a hot rolled sheet having a thickness of 0.8 mm by a finishing hot rolling machine. did.
[0122]
[Table 20]

[0123]
Since Steel U and Steel V have αγ transformation, the hot rolling finishing temperature is (Ar ₃ + Ar ₁ ) / 2 or less and 700 ° C. or more to 860 ° C., water-cooled and wound up at 750 ° C. 5% lubricating oil was mixed in the roll cooling water of the finishing hot rolling machine and sprayed from the nozzle onto the work roll. The kinematic viscosity of the lubricating oil was changed by changing the temperature of the roll cooling water from 40 ° C. to 80 ° C.
On the other hand, in order to investigate the influence of the finish hot rolling on the product magnetic flux density of the lubricating oil concentration in the roll cooling water, various concentrations of lubricating oil lubricating oil were mixed in the form of an emulsion in the roll cooling water. At this time, the temperature of the mixed liquid of the roll cooling water and the lubricating oil was set to 50 ° C., and the kinematic viscosity of the lubricating oil in the cooling water was set to 350 cSt.
In this embodiment, since the hot rolling is performed using a high kinematic viscosity lubricating oil, rough rolling is performed in order to avoid the tendency of individual sheet bars to become jammed and to stably perform the hot rolling. The subsequent sheet bar was welded to the preceding sheet bar, and finish hot rolling was continuously performed. An Epstein sample was cut out from the obtained hot-rolled sheet, and the magnetic flux characteristics were measured.
[0124]
Tables 21 and 22 collectively show the measurement results of the present invention, comparative examples, and magnetic properties. From Table 21, it can be seen that the product magnetic flux density is improved when the kinematic viscosity of the lubricating oil during finish hot rolling is 200 cSt or more. Also, from Table 22, the lubricating oil concentration in the roll cooling water is 1.0%. more than It can be seen that the product magnetic flux density is improved.
[0125]
[Table 21]

[0126]
[Table 22]

[0127]
【The invention's effect】
As described above, according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet having a high magnetic flux density.
[Brief description of the drawings]
FIG. 1 Relationship between the kinematic viscosity of lubricating oil during finish hot rolling and the concentration of lubricating oil in roll cooling water and the product magnetic flux density in a single cold rolling method in which hot-rolled sheet annealing of 0.3% Si-based components is omitted. It is a chart which shows.
FIG. 2 shows the relationship between the kinematic viscosity of the lubricating oil during finish hot rolling and the concentration of the lubricating oil in the roll cooling water and the product magnetic flux density in the single cold rolling method in which hot-rolled sheet annealing of 2% Si-based components is omitted. It is a chart.
FIG. 3 is a chart showing the relationship between the kinematic viscosity of the lubricating oil and the concentration of the lubricating oil in the roll cooling water and the product magnetic flux density during finish hot rolling in the single cold rolling method of 2% Si-based hot-rolled sheet annealing. It is.
FIG. 4 is a chart showing the relationship between hot-rolled sheet annealing time and product magnetic flux density in a hot-rolled sheet annealing single cold rolling method by continuous annealing of 2% Si-based components.
FIG. 5 is a chart showing a relationship between a hot-rolled sheet annealing temperature and a product magnetic flux density in a single-rolling method of hot-rolled sheet annealing by continuous annealing of a 2% Si-based component.
FIG. 6 is a chart showing the relationship between the kinematic viscosity of the lubricating oil in the roll cooling water and the magnetic flux density during finish hot rolling in the single cold rolling method after hot rolling of the 2% Si and 3% Si-based components. .
FIG. 7 shows the kinematic viscosity and product magnetic flux density of the lubricant in the roll cooling water during the finish hot rolling in the single cold rolling method in the process of setting the non-injection time after finishing the finish hot rolling of the 2.5% Si component system. It is a chart which shows the relationship.

Claims (2)

% By mass
0.10% <Si ≦ 3.09%
0.10% ≦ Mn ≦ 1.50%
Slab containing Fe and the inevitable impurities, and hot-rolled into a hot-rolled sheet, used as a product as it is, or subjected to one or more cold rolling sandwiching intermediate annealing. Next, in the method for producing a non-oriented electrical steel sheet, which is subjected to finish annealing, an insulating film is applied, or an end product is not applied, the lubricating oil used during finish hot rolling satisfies the following formula (1), A method for producing a non-oriented electrical steel sheet, wherein the lubricating oil is mixed in roll cooling water so as to satisfy the formula (2) and used for finishing hot rolling lubrication.
200 ≦ ρ ≦ 800 Formula (1)
1.0 ≦ v ≦ 10.0 Formula (2)
Where ρ: kinematic viscosity of the lubricating oil (cSt: centistokes)
v: Volume fraction of lubricating oil mixed in roll cooling water (%) % By mass
0.10% <Si ≦ 3.09%
0.10% ≦ Mn ≦ 1.50%
In addition,
0.10% ≦ Al ≦ 1.00%
The manufacturing method of the non-oriented electrical steel sheet according to claim 1, wherein a slab containing Fe and the balance of Fe and inevitable impurities is used.

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