JP4240736B2 - Non-oriented electrical steel sheet with low iron loss and high magnetic flux density and method for producing the same - Google Patents

Description

なお、統計的に有意な値を得るためには、１０００個以上の結晶粒方位について測定することが好ましい。
【００２１】
また、＜Γ＞は、Ｘ線回折により測定された極点図から方位分布関数（ＯＤＦ）を計算して求めることもできる。すなわち、このＯＤＦの結果からは、鋼板の特定の方向に対して、特定のミラー指数となる結晶粒の体積分率を計算することができる。この体積分率とミラー指数から求まるΓ値とを乗じたものを、各ミラー指数毎に足し合わせることを、面内の圧延方向から圧延直角方向までの各方向について行い、これを平均することにより、＜Γ＞が求められる。
この＜Γ＞が0.200 をこえる場合は、製品の磁束密度および鉄損ともに大きく劣化する。
【００２２】
以下、この発明を導くに到った実験結果について、詳述する。
発明者らは、従来の高Si系無方向性電磁鋼板の磁気特性向上に対する従来技術の限界を打破すべく鋭意検討を進めた結果、鋼板を構成する結晶の方位を適切に制御することによって磁気特性を大幅に向上できること、この結晶方位制御の指標として従来にない＜Γ＞値を用いることが有利であることを全く新規に見出した。また、これを実現するための、熱延板焼鈍条件や再結晶焼鈍条件についても深く考察研究し、特に有利な条件を新たに見い出した。
【００２３】
まず、AlやSbの影響について実験を行った。すなわち、成分として、Si：3.5mass％およびMn：0.10mass％を含み、Ｃ、Ｓ、Ｎ、ＯおよびＢを各々20ppm 以下に低減し、含有するAl量を種々に変化させた鋼塊群Ａと、成分として、Si：3.5mass％、Mn：0.10mass％およびSb：0.04mass％を含み、Ｃ、Ｓ、Ｎ、ＯおよびＢを各々20ppm 以下に低減し、含有するAl量を各種に変化させた鋼塊群Ｂとを、それぞれ溶製した。これらの鋼塊は、その後1040℃に加熱し熱間圧延にて2.3mm 厚に仕上げた。その後、1075℃×５分間の熱延板焼鈍を施し、冷却を 800〜400 ℃間の速度を20℃／ｓとして行った。さらに、これらの焼鈍後の鋼板を酸洗し、250 ℃の温度で冷間圧延を行って最終板厚の0.35mmに仕上げた。この冷間圧延後、これらの鋼板に500 〜700 ℃間の昇温速度を12℃／ｓとして昇温し、1050℃×10分間の再結晶焼鈍を行い製品板とした。これらの製品から内径100mm および外径150mm のリング状試験片を採取し、各鋼板の磁束密度および鉄損を測定した。
【００２４】
図２に、素材のAl含有量と製品板の磁束密度および鉄損との関係を示す。同図に示すように、磁気特性は素材のAl含有量により大きく変動し、0.0010mass％以上 0.10 mass％以下の範囲でＢ₅₀が1.68Ｔ以上かつＷ_15/50 が 2.1Ｗ／kg以下の良好な値が得られ、特に0.005 mass％〜0.020 mass％の範囲でＢ₅₀が1.70Ｔ以上、Ｗ_15/50 が 1.9Ｗ／kg以下の極めて優れた値が得られた。また、付加的にSbを添加した、鋼塊Ｂ群では、磁気特性の著しい向上が認められた。
【００２５】
さらに、優れた磁気特性が得られる理由を見い出すために、各製品板の結晶粒径を調査した。通常、無方向性電磁鋼板では、製品板の結晶粒径が粗大化すれば鉄損が向上するのであるが、この実験では製品板の結晶粒径に及ぼす素材Al量やSb添加の影響は小さく、いずれも粒径は 200〜300 μｍであり、磁気特性の値と再結晶焼鈍時の粒成長挙動とはほば無関係であった。従って、Al含有量が0.0010〜0.10mass％の範囲での磁気特性の向上、Sb添加によるさらなる磁気特性の向上は、結晶方位の改善によるものと考え、製品板の結晶粒方位の測定を、ＥＢＳＰを用いて行った。この測定は、鋼板表面における10mm×10mm角の領域における約2000個の結晶粒の方位を測定することによって行った。
【００２６】
ここで、発明者らは、新たに創出した、上述の＜Γ＞値を用いて解析することにより、＜Γ＞値と磁束密度との間に極めて強い相関があることを新規に見い出した。この＜Γ＞値を決定するΓ値は、結晶方向で固有の値となる。例えば、正キューブ方位である｛１００｝＜００１＞結晶粒に関して、各方向のΓ値を計算した結果について、図３に示す。同図に示すように、正キューブ方位結晶粒における圧延方向＜１００＞の場合（ｕ＝１，ｖ＝０，ｗ＝０であるのでΓ＝０）および圧延直角方向＜０１０＞の場合（ｕ＝０，ｖ＝１，ｗ＝０であるのでΓ＝０）は最小値０、圧延方向から45°傾いた方向＜１１０＞（ｕ＝１／√２，ｖ＝１／√２，ｗ＝０であるのでΓ＝0.25）の場合に最大値をとる。
【００２７】
上記した式（イ）にて定義されたΓ値を、製品板における約2000個の各結晶粒方位測定結果に基づいて同様に計算した。Γ値の計算は結晶方位粒ごとに、注目する方向（例えば圧延方向）のΓ値を計算し、その粒の面積に対する加重平均をとって算出した。その結果、Γ値と製品坂の磁束密度との間に強い相関があることを新規に見い出した。なお、比較として従来常用されてきたＸ線回折法を用いた、｛１１１｝面強度（以下Ｉ｛１１１｝と称す）と｛１００｝面強度（以下Ｉ｛１００｝と称す）との強度比▲１▼｛１００｝／Ｉ｛１１１｝に関する調査も行った。ちなみに、▲１▼｛１００｝／Ｉ｛１１１｝値は、特開平８−134606号公報に開示されている集合組織の評価法である。
【００２８】
まず、鋼塊群Ａに属するAl量が0.01mass％である、製品板の各方向の磁束密度（Ｂ₅₀）を圧延方向（０°）から圧延直角方向（90°）までの間の15°毎の方向からエプスタイン試料を、切出し方向を変えて調査した。図４に製品板の各方向における磁束密度、Γ値との関係を示す。図４に示すとおり、磁東密度およびΓ値は各方向により変動している。
【００２９】
さらに、図５に、磁東密度とΓ値との関係を示す。図５に示すように、製品板磁束密度とΓ値との間には強い相関があることが分かった。図４には、Ｉ｛１００｝／Ｉ｛１１１｝の値も併せて示したが、本来▲１▼｛１００｝／Ｉ｛１１１｝値は面強度であるから、図４に示すように、測定試料の各方向で値はほぼ一定であり、この場合磁束密度の変化を反映していないことがわかる。
【００３０】
このようにΓ値と磁束密度との間に強い相関が認められたことから、続いて各鋼塊群の製品板について同様に結晶粒方位測定とＸ線回折とを行い、リング試料における磁束密度の測定結果と圧延面内におけるΓ値の平均値およびＩ｛１００｝／Ｉ｛１１１｝との関係について調査を行った。なお、面内におけるΓ値の計算は圧延方向（０°）から圧延直角方向（90°）までの15°づつの各方向におけるΓ値を各結晶方位での測定結果を用いて計算し、これらの値の平均値を＜Γ＞として求めた。
【００３１】
すなわち、図６に製品板磁束密度と＜Γ＞の関係を示すように、リング試料における磁束密度と結晶粒方位測定から求められた面内での平均値＜Γ＞との間には強い相関が認められ、Ｂ₅₀＞1.65Ｔの高い磁束密度を得るためには＜Γ＞を0.200 以下とする必要があることがわかった。一方、図７に同一試料を用いて調査した、Ｉ｛１００｝／Ｉ｛ｌｌｌ｝と製品板磁束密度との関係を示すが、両者の間には明瞭な関係は認められない。
【００３２】
このように製品板の磁束密度と＜Γ＞との相関が極めて強いのに対して、▲１▼｛１００｝／Ｉ｛１１１｝との相関が弱いという、この実験の結果を得られた理由については明らかではないが、この発明による評価方法では、各結晶粒の方位から直接に鋼板の各方向における＜Γ＞を求め、これらの値から面内の平均値を算出するのに対し、Ｉ｛１１１｝／Ｉ｛１００｝を評価する方法では、ほぼ｛１１１｝、｛１００｝近傍のごく一部の結晶粒のみの強度を評価しており、それ以外の比較的重要な結晶粒、例えば｛５４４｝、｛２２１｝、｛３３２｝など多くの方位の結晶粒を無視し、これらの強度が磁気特性に及ぼす寄与を評価範囲から除外しているからであると推定される。
【００３３】
また、Γ値を用いる利点は他にもある。一般に、鉄以外の元素の含有量に応じて、鋼板の飽和磁束密度は変化する。このために、製品板が、たとえ同じ結晶粒の方位集積度を持つとしても、その磁束密度の値は変化する。従って、成分が異なる成分系の製品の方位集積度を比較する場合、磁束密度の値では単純に比較することはできないが、＜Γ＞は結晶方位自体で定まるために、合金成分に関係なく製品板の結晶粒方位の集積状態を評価可能であり、このため極めて有効な指標となる。
【００３４】
次に、Al含有量と不純物量との関係について検討した結果を述べる。
Si：3.5 mass％，Mn：0.10mass％およびSb：0.03mass％を含み、かつＣ，Ｓ，Ｎ，ＯおよびＢを各々50ppm 以下に低減し、Al量を種々に変更した鋼塊群Ｂ（発明範囲内）と、Si：3.5 mass％およびMn：0.12mass％を含み、かつＣ，Ｓ，Ｎ，ＯおよびＢの各含有量が 50ppm以上であり、その合計量も350ppm以上でかつAl量を種々に変更した鋼塊群Ｃ（発明範囲外）とを溶製した。これらの鋼塊は、その後1100℃に加熱し熱間圧延にて2.4mm 厚に仕上げた。次いで、1100℃×５分間の熱延板焼鈍を施したのち、 800〜400 ℃間を15℃／ｓの速度で冷却した。さらに、これらの焼鈍後の鋼板を酸洗し、200 ℃の温度での冷間圧延にて最終板厚の0.35mmに仕上げた。冷間圧延後、これらの鋼板に1050℃×10分の再結晶焼鈍を行い製品板とした。かくして得られた製品板の結晶粒方位の測定を、ＥＢＳＰにて、鋼板表面における10mm×10mm角の領域における約2000個の結晶粒の方位を測定して、圧延面内の平均値＜Γ＞を求めた。
【００３５】
図８に、各鋼塊群におけるAl含有量と＜Γ＞との関係を示すように、不純物元素Ｃ，Ｓ，Ｎ，ＯおよびＢを低減した鋼塊群Ｂでは＜Γ＞が 0.200以下であるが、不純物元素Ｃ，Ｓ，Ｎ，ＯおよびＢが多く含まれる鋼塊群Ｃでは、0.200 以下の＜Γ＞が得られていない。さらに、鋼塊群Ｂでは、Al量が10〜1000ppm の範囲において、特に磁束密度に有利な0.195 以下の＜Γ＞が得られている。
【００３６】
この実験を基にさらに鋭意研究を進めた結果、磁束密度の向上に有利な＜Γ＞が0.195 以下である、特に良好な集合組織を得るためには、Al含有量を制御するだけでなく、不純物元素Ｃ，Ｓ，Ｎ，ＯおよびＢを各々50ppm 以下に低減することが必須であることがわかった。
【００３７】
ところで、上述したように、Si量の高い高級無方向性電磁鋼板では、鉄損を改善するために、固有電気抵抗を増加させる手法が採用されてきた。また、この方法は結晶粒成長を抑制する鋼中析出物であるAlN を凝集粗大化させ、結晶粒の粒成長を促進させる効果もある。これらの効果を得るためには、Alの含有量は一定量以上確保することが必要であり、従来、Alの含有量は少なくとも0.1 mass％を超える量に規制され、通常は 0.4〜1.0 mass％程度の含有量となっている。しかし、発明者らの上記実験により得られた結果は、従来技術の範囲よりもはるかに低い含有量の範囲、特に0.0010〜0.10mass％の範囲で最も好適に集合組織が発達し、その結果＜Γ＞は0.195 以下となって磁束密度並びに鉄損とも最良値を示した。
【００３８】
このように素材成分における不純物元素Ｃ，Ｓ，Ｎ，ＯおよびＢを各々50ppm以下に低減して、Alの含有量を制御することによって、圧延面内での平均Γ値の低い良好な集合組織が発達する理由については必ずしも明らかではないが、発明者らは不純物の粒界移動抑制効果に関連付けて以下のように考えている。すなわち、素材の高純度化によって、不純物元素、特に粒界偏析傾向の強いＣ，Ｓ，Ｎ，ＯおよびＢの影響が排除されて粒界移動が容易になること、Alを0.10mass％以下に低減することにより、より純鉄に近い結晶格子の配列状態へと近づくため、粒界構造に依存する本来の移動速度差が顕在化して、再結晶に伴う粒成長過程で一部の粒界のみが優先的に移動し、｛１１１｝，｛５５４｝，｛３２１｝，など数多くの磁気的に不利な結晶粒の成長が抑制され、＜Γ＞が減少する方向への集合組織変化を起こし、磁気特性が向上したものと考えられる。Ｓｂに関しては、再結晶核生成時に磁気特性に有利な｛ｌ００｝方位近傍の結晶方位が優先的に再結晶する影響が認められ、上述のAlを低減した際の効果と組み合わせることによって、磁気特性が大きく向上するものと推定される。
【００３９】
また、Alが10ppm 未満の場合は、不純物元素Ｃ、Ｓ、Ｎ、ＯおよびＢの低減による磁気特性改善の効果が小さくなる。この場合、鋼中に粗大な窒化珪素が形成されていることが観察されており、これにより冷間圧延時の変形挙動が変化して、再結晶焼鈍後の組織における＜Γ＞が多少増加するものと推定される。よって、不純物元素低減により＜Γ＞が減少するものの、結果として磁気特性の改善は小さくなっているものと思われる。これに対し、Al量が10ppm 以上含まれる場合には、この粗大な窒化珪素の形成は抑制されており、上記のような冷間圧延時の変形挙動の変化による＜Γ＞の増加を回避できるため、磁気特性の改善に特に有利である。
【００４０】
このように、＜Γ＞値を0.200 以下にするためには、不純物元素Ｃ，Ｓ，Ｎ，ＯおよびＢを各々50ppm 以下とすることが肝要であるが、さらにAl含有量を0.001 〜0.10mass％に制御し、必要に応じて所定量のSbを含有させることにより、＜Γ＞値を磁気特性にさらに有利な0.195 以下に低減することが可能となる。
【００４１】
ちなみに、この発明に従う、Alを多量添加することなく、集合組織を改善して磁気特性を改善する手法では、合金元素の添加量が少ないので飽和磁束密度が高いという利点の他、硬度の上昇が回避されて製品の加工性が確保されるため、汎用電気製品への適用が促進される利点もある。
【００４２】
さらに、集合組織を改善して＜Γ＞値を0.200 以下にすることを可能とする、別の手法を確立すべく、熱延板焼鈍条件に関する実験を行った。
すなわち、Si：3.6 mass％，Mn：0.13mass％、Al：0.009 mass％およびSb：0.06mass％を含み、かつＣ，Ｓ，Ｎ，ＯおよびＢを各々20ppm 以下に低減した鋼塊を溶製した。この鋼塊は、その後1120℃に加熱し熱間圧延にて2.8mm に仕上げた。次いで、1100℃×５分間の熱延板焼鈍を施したのち、冷却速度を種々に変更して冷却を行った。さらに、これらの焼鈍後の鋼板を酸洗し、230 ℃の温度での冷間圧延にて最終板厚の0.50mmに仕上げた。冷間圧延後、1070℃×10秒間の再結晶焼鈍を行い製品板とした。かくして得られた製品板から内径100mm および外径150mm のリング試験片を採取し、各鋼板の磁束密度および鉄損を測定した。また、製品板の結晶粒方位の測定を、ＥＢＳＰにて鋼板表面における10mm×10mm角の領域における約2000個の結晶粒の方位を測定して、圧延面内の＜Γ＞を求めた。
【００４３】
図９に、熱延板焼鈍後の 800〜400 ℃の温度域での冷却速度と＜Γ＞との関係を示すように、冷却速度が５〜80℃／ｓの範囲とすることによって、＜Γ＞が0.195 以下の特に良好な集合組織が得られることがわかった。おそらく、冷却速度を規制することによって、微量に存在するAlN 析出物の分散状態が微細になる結果、冷間圧延時の不均一変形が促進されて再結晶組織が改善されるものと推定されるが、集合組織改善の本質的な機構は明らかではない。
【００４４】
次に、鉄損および磁束密度をさらに改善するための要件として、再結晶焼鈍条件を変更して、次のような実験を行った。
すなわち、Si：3.6 mass％，Mn：0.13mass％およびAl：0.30mass％を含み、Ｃ，Ｓ，Ｎ，ＯおよびＢを各々20ppm 以下に低滅した鋼塊Ｄ、Si：3.6 mass％，Mn：0.13mass％，Al：0.009 mass％およびSb：0.06mass％を含み、Ｃ，Ｓ，Ｎ，ＯおよびＢを各々20ppm 以下に低滅した鋼塊Ｅ、をそれぞれ溶製した。これらの鋼塊は、その後1070℃に加熱して熱間圧延にて2.5mm の厚さに仕上げた。その後、1170℃×５分の熱延板焼鈍を施し、 800〜400 ℃間の冷却速度を10℃／ｓとした冷却を行った。さらに、これらの焼鈍後の鋼板を酸洗し、200 ℃の温度で冷間圧延を行って最終板厚の0.35mmに仕上げた。この冷間圧延後、各鋼板から試料を採取し、以下に示す３種類の方法で再結晶焼鈍を別々に行って製品板とした。
【００４５】
〔焼鈍１〕
昇温速度：常温から 500℃間で平均30℃／ｓ、 500〜700 ℃間で平均15℃／ｓ、 700〜900 ℃間で平均８℃／ｓ、均熱 900℃×10秒
冷却速度：均熱から常温まで平均10℃／ｓ
焼鈍雰囲気：水素50％、窒素50％、露点−30℃
〔焼鈍２〕
昇温速度：常温から 500℃間で平均 100℃／ｈ、 500〜900 ℃間で50℃／ｈ、均熱 900℃×10時間、
冷却速度：均熱から常温まで平均 100℃／ｈ
雰囲気：Ar露点−30℃
〔焼鈍３〕
焼鈍１を行った後焼鈍２を行う。
【００４６】
これらの製品板から内径100mm および外径150mm のリング試験片を採取し、各試験片の磁束密度および鉄損を測定した。また、製品板の結晶粒方位の測定を、EBSPにて、鋼板表面における10mm×10mm角の領域における約2000個の結晶粒について行い、＜Γ＞値を求めた。
【００４７】
図10に再結晶焼鈍条件と磁気特性との関係を、また図11に再結晶焼鈍条件と＜Γ＞との関係を、それぞれ示す。まず、鉄損については、どの鋼塊とも、焼鈍１に比べて焼鈍２、さらに焼鈍３を経た鋼板の鉄損が良好になる。特に、Sbを添加した鋼塊Ｅの鉄損が良好である。一方、磁束密度については、Al, Sbを添加した鋼塊Ｅにおいて、焼鈍１に比較して焼鈍２、そして焼鈍３が向上しているが、Sbを含有せず、Alを発明範囲外の 0.3mass％で含有する鋼塊Ｅでは変化がない。また、＜Γ＞に関しては、磁束密度の変化に対応した変化を示しており、鋼塊Ｃにおいて最も低い＜Γ＞と高い磁束密度が得られている。
【００４８】
また、再結晶焼鈍後の粒径と再結晶焼鈍条件との関係を図12に示す。図12に示すように、各焼鈍条件において最高到達温度は 900℃と同一であるが、急速昇温である焼鈍１に比べて低速昇温である焼鈍２では、若干ではあるが粒成長が進行し、急速昇温を行った後に低速昇温を施した焼鈍３では、特に鋼塊Ｅにおいて焼鈍１、２に比べて著しく粒成長が進行していた。焼鈍２の場合、急速昇温である焼鈍１に比較して到達温度は同一であるが均熱時間が異なるために、粒成長が進行したものと考えられる。焼鈍３については熱効果的には焼鈍２との違いはわずかであるのにも拘わらず、焼鈍２に比べて著しく粒径が増大している。焼鈍２と焼鈍３を比較した場合、再結晶核生成時の昇温速度が異なっており、これに起因する集合組織形成過程の差異の基づく再結晶集合組織の違いが、続く粒成長挙動を大きく変えたものと推定されるが、本質的な機構は明らかでない。
【００４９】
さらに、素材の添加元素について検討を行ったところ、Niを添加することにより、製品の磁束密度が向上することを見い出した。この磁束密度の向上には、Niが強磁性体元素であることが何らかの理由で寄与しているものと推定されるが、理由は明らかでない。また、Sn，Cu，ＰおよびCrなどの添加により鉄損が改善する傾向が認められた。おそらく、電気抵抗を増加させることにより鉄損が低減されているものと推定される。
【００５０】
【発明の実施の形成】
以下に、この発明の各構成要件の限定理由について述べる。
すなわち、この発明の電磁鋼板の成分としては、Siを含有して電気抵抗を増大させて鉄損を低減する必要があるが、この鉄損改善のためには 1.5mass％以上のSiが必要である。一方、8.0 mass％をこえると、磁束密度が低下すること及び製品の二次加工性が著しく劣化するため、Si含有量は 1.5〜8.0 mass％に制限する。
【００５１】
Mnは、熱間加工性を良好にするために必要な成分であるが、0.005 mass％未満では効果に乏しく、一方2.50mass％を超えると飽和磁束密度が低下するため、0.005 〜2.50mass％の範囲とする。
【００５２】
また、この発明で所期する結晶方位を実現するために、鋼板の微量成分を低減することが必須である。すなわち、鋼板表面のコーティングを除く鋼板全体において、Ｃ，Ｓ，Ｎ，ＯおよびＢの含有量を各々50ppm 以下、望ましくは20ppm 以下にする必要があり、これ以上の含有量では、製品板結晶方位における＜Γ＞が増大して鉄損が大きくなる。
【００５３】
次に、この発明では結晶方位の制御が必須である。すなわち、良好な磁気特性を得るためには、上記した式（イ）により定まるΓ値の圧延面内における平均値＜Γ＞が0.200 以下であることが肝要であり、その理由は上述のとおりである。
【００５４】
次に、上記電磁鋼板を製造する方法について、詳述する。
始めに、溶鋼成分としては、Siを 1.5〜8.0 mass％およびMnを0.005 〜2.50mass％に規制するのは、上記したとおりである。
【００５５】
そして、Ｃ，Ｓ，Ｎ，ＯおよびＢの不純物元素の上限値を各々50ppm 、好ましくは20ppm として規制することが必須である。なお、Ｃに関しては、溶鋼成分の段階で50ppm 以下としてもよいし、溶鋼段階で50ppm を超えていても途中工程での脱炭処理により50ppm 以下としてもよく、少なくとも再結晶焼鈍より前に50ppm 以下とすることが必須である。これらの不純物の含有量が50ppm を超えた場合、特殊な結晶粒界の選択的移動が妨げられ、再結晶焼鈍後の＜Γ＞値が増加し磁気特性が劣化する。
【００５６】
また、Al量の制御は、この発明の＜Γ＞が0.200 以下である無方向性電磁鋼板を得るための最も有利な技術であり、特に集合組織の良好な＜Γ＞が0.195 以下の製品を得るためには、Alが0.0010〜0.10mass％の範囲にすることが好適である。すなわち、Alが0.10mass％を超えると、集合組織が変化して製品板における＜Γ＞が増加し、鉄損および磁束密度が劣化する。一方、Alが0.0010mass％未満になると、窒化硅素が析出して圧延時の変形挙動に影響を与え、集合組織が変化して＜Γ＞が多少増加して、不純物元素Ｃ、Ｓ、Ｎ、ＯおよびＢの低減による＜Γ＞減少の効果が小さくなるため、Alは0.0010mass％以上とすることが鉄損および磁束密度の改善に有利である。
【００５７】
以上の成分調整による手法に加えて、熱延板焼鈍を 800〜1200℃の温度範囲で施したのち、800 〜400 ℃での冷却を５〜80℃／ｓの速度で行うことが、良好な集合組織、具体的には＜Γ＞が 0.195以下となる組織をえるのに、有効である。
すなわち、熱延板焼鈍温度が 800℃未満であると、熱延板の再結晶が不十分となり、磁気特性の改善も不十分になり、一方熱延板焼鈍温度が1200℃を超えると、熱延板の結晶粒径が粗大化しすぎて冷間圧延時に割れを生じるため、 800〜1200℃とすることが好ましい。また、冷却速度については、上述の通りである。
【００５８】
さらに、Sbを付加的に添加することにより、再結晶核生成挙動を変化させて製品板の＜Γ＞を低減し、良好な磁気特性を得ることができる。すなわち、Sbの添加量が0.01mass％未満であると集合組織改善効果がなく、一方0.50mass％をこえると、脆化して冷間圧延が困難になるため、0.01〜0.50mass％の範囲とする。
【００５９】
次いで、再結晶焼鈍時における700 ℃以上での昇温速度を 100℃／ｈ以下と徐熱にして、 750℃以上1200℃以下の温度域まで到達させることが、粒成長を促進し磁気特性を向上させるために有効である。すなわち、700 ℃以上での昇温速度が100 ℃／ｈをこえると、集合組織の改善効果が小さくなるため、昇温速度は 100℃／ｈ以下とすることが好ましい。なお、昇温速度の下限は特に定めないが、昇温速度が１℃／ｈ未満であると、焼鈍時間が長すぎて経済的に不利である。一方、再結晶焼鈍の到達温度は、 750℃未満であると粒成長が不十分なために磁気特性が劣化し、1200℃をこえると表面酸化が進行して鉄損が劣化するため、再結晶焼鈍の到達温度は 750℃以上1200℃以下が好適である。均熱時間に関しては特に定めないが、良好な鉄損を得るためには経済的に許容される範囲内で長時間として粒成長を促進させることが有効である。
【００６０】
さらに、著しく粒成長を促進させて磁気特性を向上させるために、再結晶焼鈍の前半では、500 〜700 ℃間の昇温速度を２℃／ｓ以上の急速昇温として700 ℃以上に昇温して再結晶を完了させ、後半は、 700℃以下の温度へと冷却し、再び 700℃以上での昇温速度を 100℃／ｈ以下として 750℃以上1200℃以下の温度まで到達させることが有効である。
【００６１】
すなわち、再結晶焼鈍前半の昇温時の 500〜700 ℃間の昇温速度が２℃／ｓ未満であると、後半の焼鈍における粒成長の促進効果が小さくなるため、前半の再結晶焼鈍時における 500〜700 ℃間の昇温速度は２℃／ｓ以上とすることが好ましい。同様に、再結晶焼鈍前半の温度が 750℃未満、1200℃をこえる場合も、後半の焼鈍における粒成長の促進効果が小さくなるため、前半の再結晶焼鈍時における到達温度を 750〜1200℃とすることが望ましい。再結晶焼鈍後半における昇温速度が 100℃／ｈをこえると、集合組織の改善効果が小さくなるため、再結晶焼鈍後半における昇温速度の好適範囲は 100℃／ｈ以下とする。また、再結晶焼鈍後半の到達温度は 750℃未満であると粒成長が不十分なために磁気特性が劣化し、1200℃をこえると表面酸化が進行して鉄損が劣化するから、再結晶焼鈍後半の到達温度は 750℃以上1200℃以下とすることが好ましい。なお、再結晶焼鈍後半における均熱時間に関しては特に定めないが、良好な鉄損を得るためには経済的に許容される範囲内で長時間として粒成長を促進させることが有効である。
【００６２】
ここに、500 ℃までの昇温速度に関しては再結晶挙動に大きな影響を及ぼさないため、特に規制する必要はない。また、冷却条件についても、磁気特性上は特に規制する必要はないが、経済的には60℃／min 〜10℃／hrの範囲の速度が有利である。
【００６３】
さらに、磁束密度を向上させるためにNiを添加することができる。Niの添加量が0.01mass％未満であると磁気特性の向上量が小さくなり、一方1.50mass％をこえると、集合組織の発達が不十分で磁気特性が劣化するため、添加量は0.01〜1.50mass％とする。同様に、鉄損を向上させるために、Sn：0.01〜1.50mass％，Cu：0.01〜1.50mass％，Ｐ：0.005 〜0.50mass％，Cr：0.01〜1.50mass％を添加することも有効である。この範囲より添加量が少ない場合には鉄損改善効果がなく、添加量が多い場合には飽和磁束密度が低下する。
【００６４】
ちなみに、上記した成分を有する溶鋼は、通常の通常造塊法や連続鋳造法にてスラブとしてもよいし、100mm 以下の厚さの薄鋳片を直接鋳造法で製造してもよい。次いで、スラブは通常の方法で加熱して熱間圧延するが、鋳造後加熱せずに直ちに熱間圧延してもよい。薄鋳片の場合には、熱間圧延しても良いし、熱間圧延を省略してそのまま以後の工程に進んでもよい。引き続き、熱延板焼鈍を施し、必要に応じて中間焼鈍を挟む１回以上の冷間圧延を施した後連続焼鈍を行い、必要に応じて絶縁コーティングを施す。最後に、積層した鋼板の鉄損を改善するために、鋼板表面に絶縁コーティングが施されるが、この目的には２種類以上の被膜からなる多層膜であってもよいし、樹脂等を混合させたコーティングを施してもよい。
【００６５】
【実施例】
実施例１
表１に示す成分の鋼スラブを連続鋳造にて製造した後、スラブを1250℃で50分加熱し熱間圧延にて2.3mm 厚に仕上げた。その後、熱延板焼鈍を1150℃で60秒の条件で行って 800〜400 ℃間を15℃／ｓで冷却し、170 ℃の温度で冷間圧延を行って0.35mmの最終板厚に仕上げた。次いで、水素雰囲気で1050℃×３分の再結晶焼鈍を施し、半有機コーティング液を塗布して３００℃で焼き付けて製品とした。
【００６６】
そして、この製品板から、外径150 mmおよび内径100mm のリング状試料を採取して、その磁気特性を測定するとともに、製品板表面における10mm×10mm角領域のおける結晶粒の方位をＥＢＳＰにより測定して＜Γ＞を算出した。これらの測定結果を表１に併記するように、この発明に従う鋼板は良好な磁気特性が得られていることがわかる。
【００６７】
【表１】

【００６８】
実施例２
Ｃ：38ppm ，Si：3.24mass％，Mn：0.15mass％，Al：0.013 mass％，Sb：0.02mass％，Ｓ：11ppm ，Ｏ：７ppm ，Ｎ：９ppm およびＢ：２ppm を含み、残部が実質的にFeの成分組成のスラブを連続鋳造にて製造した。このスラブを、1150℃で30分加熱し熱間圧延にて2.9mm 厚に仕上げた。その後、熱延板焼鈍を1050℃で60秒間行って、 800〜400 ℃間を８℃／ｓで冷却し、冷間圧延にて0.35mm厚に仕上げた。次いで、水素雰囲気において、表２に示す昇温速度で昇温して最高温度に到達後冷却する再結晶焼鈍を施した。最後に、無機コーティング液を塗布して 300℃で焼き付けて製品とした。
【００６９】
そして、この製品板から、外径150 mmおよび内径100mm のリング状試料を採取して、その磁気特性を測定するとともに、製品板表面における10mm×10mm角領域のおける結晶粒の方位をＥＢＳＰにより測定して＜Γ＞を算出した。これらの測定結果を表２に併記するように、再結晶焼鈍時における常温から 700℃までの昇温速度を 200℃／ｈとし、700 ℃以上での平均昇温速度を１℃〜100 ℃／ｈとして 750℃以上1200℃以下の温度まで到達させることにより、特に磁気特性の良好な製品が得られることがわかる。
【００７０】
【表２】

【００７１】
実施例３
表３に示す成分からなる板厚4.5mm の薄鋳片を直接鋳造で製造した。次いで、熱延板焼鈍を1150℃30秒間で行って、 800〜400 ℃間を50℃／ｓで冷却し、室温での冷間圧延にて1.6mm 厚とした後、中間焼鈍を1000℃で60秒間行ったのち、室温での冷間圧延で0.20mm厚に仕上げた。最後に、Ar雰囲気において、表３に示す条件で第１次引き続いて第２次の再結晶焼鈍を施して製品とした。
【００７２】
そして、この製品板から、外径150 mmおよび内径100mm のリング状試料を採取して、その磁気特性を測定するとともに、製品板表面における10mm×10mm角領域のおける結晶粒の方位をＥＢＳＰにより測定して＜Γ＞を算出した。これらの測定結果を表３に併記するように、再結晶焼鈍時における 700℃以上での昇温速度を１℃〜100 ℃／ｈとして 750℃以上1200℃以下の温度まで到達させることにより、特に磁気特性の良好な製品が得られることがわかる。
【００７３】
【表３】

【００７４】
実施例４
表４に示す成分のスラブを連続鋳造にて製造した後、スラブを1200℃で50分加熱し熱間圧延にて2.6mm 厚に仕上げた。次いで、熱延板焼鈍を1180℃ 120秒で行って、 800〜400 ℃間を30℃／ｓで冷却し、150 ℃の温度で冷間圧延を行って0.35mmの最終板厚に仕上げた。その後、Ar雰囲気で1150℃×１分の再結晶焼鈍を施し、半有機コーティング液を塗布して 300℃で焼き付けて製品とした。
【００７５】
そして、この製品板から、外径150 mmおよび内径100mm のリング状試料を採取して、その磁気特性を測定するとともに、製品板表面における10mm×10mm角領域のおける結晶粒の方位をＥＢＳＰにより測定して＜Γ＞を算出した。これらの測定結果を表４に併記するように、この発明に従う鋼板は良好な磁気特性が得られていることがわかる。
【００７６】
【表４】

【００７７】
【発明の効果】
この発明によれば、従来技術で得られる磁気特性を凌駕した、優れた磁束密度並びに鉄損を有する無方向性電磁鋼板を得ることができる。
【図面の簡単な説明】
【図１】 ＜Γ＞の算出要領を説明するための図である。
【図２】 Al含有量と磁束密度および鉄損との関係を示す図である。
【図３】 製品板における各方向における＜Γ＞を示す図である。
【図４】 製品板における各方向における磁束密度および＜Γ＞を示す図である。
【図５】 製品板における磁束密度と＜Γ＞との関係を示す図である。
【図６】 製品板磁束密度と＜Γ＞値との関係を示す図である。
【図７】 製品板磁束密度と｛ｌ００｝／｛ｌｌｌ｝値との関係を示す図である。
【図８】 素材Al量と製品板＜Γ＞値との関係を示す図である。
【図９】 熱延板焼鈍後の冷却速度と製品板＜Γ＞値との関係を示す図である。
【図１０】 仕上焼鈍条件と製品板の鉄損および磁束密度との関係を示す図である。
【図１１】 仕上焼鈍条件と製品板＜Γ＞値との関係を示す図である。
【図１２】 仕上焼鈍条件と製品板粒径との関係を示す図である。[0001]
[Industrial application fields]
The present invention relates to a non-oriented electrical steel sheet mainly used for electrical equipment iron core materials and a method for producing the same.
[0002]
[Prior art]
In recent years, high efficiency of electric equipment has been strongly demanded in the movement of global electric power and energy saving. In addition, due to the demand for miniaturization of electrical equipment, there is an increasing demand for miniaturization of iron core materials.
[0003]
Conventionally, in order to reduce the iron loss of non-oriented electrical steel sheets, a method of increasing the content of Si, Al, Mn, etc. is generally used for the purpose of reducing eddy current loss by increasing electrical resistance. However, there has been an essential problem that this method cannot avoid a decrease in magnetic flux density.
[0004]
Further, not only the content of Si or Al is simply increased, but also reduction of C and S, addition of B as described in JP-A-58-15143, or JP-A-3-281758 Also known is a method of increasing alloy components, such as a method of adding Ni as described above. Although the iron loss is improved by the method of adding these alloy components, the effect of improving the magnetic flux density is small and not satisfactory. Moreover, in this method, the hardness increases as the alloy is added and the workability deteriorates. As a result, the non-oriented electrical steel sheet cannot be processed and used in electrical equipment, so its application is extremely limited and versatile. It was inferior to.
[0005]
Furthermore, several methods have been proposed for improving the magnetic properties by changing the manufacturing process to improve the degree of crystal orientation of the product plate, that is, the texture. For example, Japanese Patent Publication No. 58-181822 discloses that steel containing Si: 2.8 to 4.0 mass% and Al: 0.3 to 2.0 mass% is warm-rolled within a temperature range of 200 to 500 ° C., and {100} < The method of developing UVW> structure, and Japanese Patent Publication No. 3-294422 discloses that steel containing Si: 1.5 to 4.0 mass% and Al: 0.1 to 2.0 mass% is hot-rolled and then 1000 ° C to 1200 ° C. The following hot-rolled sheet annealing and cold rolling reduction ratios of 80 to 90% and methods for developing a {100} structure are described respectively. However, the improvement range of magnetic characteristics by these methods is small. For example, in Example 2 in Japanese Patent Publication No. 58-191922, the magnetic flux density of a product having a thickness of 0.35 mm made of a component steel containing Si: 3.40 mass% and Al: 0.60 mass% is B.₅₀1.70T, iron loss is W_15/50 About 2.1 W / kg, in Japanese Patent Publication No. 3-294422, the magnetic flux density of a steel with a thickness of 0.50 mm is B, which is a component steel containing Si: 3.0 mass%, Al: 0.30 mass% and Mn: 0.20 mass%.₅₀1.71T, iron loss is W_15/50 The value is about 2.5 W / kg.
[0006]
In addition, proposals for improving the manufacturing process have been made. However, in all cases, the achievement of low iron loss was insufficient and the magnetic flux density was low.
[0007]
[Problems to be solved by the invention]
The present invention seeks to provide a non-oriented electrical steel sheet having excellent magnetic flux density and iron loss that surpasses the magnetic characteristics obtained by the prior art, and a method for producing the same.
[0008]
[Means for Solving the Problems]
The inventors have intensively studied the problems in the prior art in order to achieve low iron loss and high magnetic flux density at the same time, and have come to develop a new non-oriented electrical steel sheet and a method for manufacturing the same. That is, the gist configuration of the present invention is as follows.
[0009]
  (1) Si: 1.5 to 8.0 mass%,Mn: 0.005 to 2.50 mass%and Al : 0.0010 ~ 0.10mass %, And the content of C, S, N, O and B is suppressed to 50 ppm or less respectively, and the composition is composed of the remaining Fe and unavoidable impurities, and is determined by the following formula from the orientation of each crystal grain of the steel sheet: A non-oriented electrical steel sheet characterized in that the average value <Γ> in the rolling plane of the value is 0.195 or less.
                                  Record
    Γ = u² v² + V² w² + W² u²
  Here, u, v, and w mean <u, v, w> obtained by converting the Miller index display into a unit vector in an arbitrary direction from the rolling direction of each crystal grain to the rolling perpendicular direction.
[0011]
  (2) the above(1) InIn addition, the non-oriented electrical steel sheet characterized by becoming a component composition containing Sb: 0.01-0.50mass% further.
[0012]
  (3) (1) aboveOr (2) In addition, Ni: 0.01 to 3.50 mass%, Sn: 0.01 to 1.50 mass%, Cu: 0.01 to 1.50 mass%, P: 0.005 to 0.50 mass%, and Cr: 0.01 to 1.50 mass% are contained. A non-oriented electrical steel sheet characterized by having a component composition.
[0013]
  (Four) Si: 1.5 to 8.0 mass%, Mn: 0.005 to 1.50 mass%, and Al:0.0010Suppresses the content of S, N, O, and B to 50ppm or less respectively, uses the molten steel of the component consisting of the balance Fe and inevitable impurities as slab, and then hot-rolled sheet annealing after hot rolling In the series of processes in which the steel sheet is subjected to cold rolling at least once with intermediate or intermediate annealing, finished to the final thickness, then recrystallized, and if necessary, an insulating coating is applied. Alternatively, the C content of the steel sheet is adjusted to 50 ppm or less in any process prior to recrystallization annealing, and after hot-rolled sheet annealing is performed at a temperature range of 800 to 1200 ° C, cooling at 800 to 400 ° C is performed 5 times. The recrystallization annealing is performed at a speed of ˜80 ° C./s, and the temperature rise rate in the temperature range of 700 ° C. or higher is set to 100 ° C./h or less to reach the temperature range of 750 ° C. to 1200 ° C. A method for producing a non-oriented electrical steel sheet.
[0014]
  (Five)   Si: 1.5 to 8.0 mass%,Mn: 0.005 to 2.50 mass%and Al : 0.0010 ~ 0.10mass %And the S, N, O and B contents are suppressed to 50 ppm or less, respectively, and the molten steel composed of the remaining Fe and inevitable impurities is used as a slab, and then hot-rolled sheet annealing is performed after hot rolling. From one or two or more cold rolls with intermediate annealing, finishing to the final thickness, and then performing recrystallization annealing and applying insulation coating as necessary, during molten steel or recrystallization In one of the processes prior to annealing, the C content of the steel sheet is adjusted to 50 ppm or less, and after performing hot-rolled sheet annealing in the temperature range of 800 to 1200 ° C, cooling at 800 to 400 ° C is performed to 5 to 80 ° C. The recrystallization annealing is performed at a rate of 500 to 700 ° C. or higher at a rate of temperature rise of 2 ° C./s or higher to 700 ° C. or higher to complete the recrystallization, and then the recrystallization annealing is performed at 700 ° C. Cool to the following temperature range, and increase the heating rate again in the temperature range above 700 ° C to 100 ° C / h Method for producing a non-oriented electrical steel sheet, characterized in that to reach a temperature range temperatures higher than 750 ℃ 1200 ° C. or less as a bottom.
[0015]
(6)the above(4) Or (5), Sb: 0.01 to 0.50 mass% is contained, The manufacturing method of the non-oriented electrical steel sheet characterized by the above-mentioned.
(7)Si: 1.5 to 8.0 mass%,Mn: 0.005 to 1.50 mass%, Al : 0.0010 ~ 0.10mass %And Sb: 0.01 to 0.50 mass%, S, N, O and B contents are suppressed to 50 ppm or less, respectively, and the molten iron composed of the remaining Fe and inevitable impurities is used as a slab, and then hot rolled. A series of hot-rolled sheet annealing, followed by cold rolling at least once with intermediate or intermediate annealing, finishing to the final thickness, followed by recrystallization annealing and applying insulation coating as required In the process, while adjusting the C content of the steel sheet to 50 ppm or less in either process before molten steel or prior to recrystallization annealing, and after performing hot-rolled sheet annealing in the temperature range of 800-1200 ° C, 800-400 ° C The manufacturing method of the non-oriented electrical steel sheet characterized by performing cooling in this at a speed | rate of 5-80 degrees C / s.
[0017]
(8)the above(4) Or (7), The molten steel further comprises at least Ni: 0.01-3.50 mass%, Sn: 0.01-1.50 mass%, Cu: 0.01-1.50 mass%, P: 0.005-0.50 mass%, and Cr: 0.01-1.50 mass%. The manufacturing method of the non-oriented electrical steel sheet characterized by including 1 type.
[0018]
(10) In any one of the above (5) to (9), the molten steel is further Ni: 0.01 to 3.50 mass%, Sn: 0.01 to 1.50 mass%, Cu: 0.01 to 1.50 mass%, P: 0.005 to 0.50 mass% And Cr: A method for producing a non-oriented electrical steel sheet having low iron loss and high magnetic flux density, characterized by containing at least one of 0.01 to 1.50 mass%.
[0019]
Here, the average value <Γ> in the rolling plane of the Γ value determined by the above formula (A) can be specifically determined according to the following method. First, the orientation of each crystal grain on the rolled steel sheet surface is measured using an Electron Back Scattering Pattern (hereinafter referred to as EBSP) or the like. That is, as shown in FIG. 1, the Miller index is obtained for each of the crystal grains j in a plurality of directions from the rolling direction 1 in the rolling plane of the steel plate to the rolling perpendicular direction m. Next, the Γ value is calculated using <u, v, w> obtained by unitizing the obtained Miller index.
Γ = u² v² + V² w² + W² u²
Is calculated.
[0020]
This Γ value is preferably determined for each crystal grain in the direction from at least 15 ° in the range from the rolling direction to the direction perpendicular to the rolling direction. The Γ values for the respective directions in the rolling plane of the respective crystal grains obtained in this way are averaged, and the average of all the measured crystal grains n is defined as <Γ>. Ie
[Expression 1]

In order to obtain a statistically significant value, it is preferable to measure 1000 or more crystal grain orientations.
[0021]
<Γ> can also be obtained by calculating an orientation distribution function (ODF) from a pole figure measured by X-ray diffraction. That is, from this ODF result, the volume fraction of crystal grains that have a specific Miller index can be calculated in a specific direction of the steel sheet. Multiplying this volume fraction and the Γ value obtained from the Miller index for each Miller index is performed for each direction from the in-plane rolling direction to the perpendicular direction of rolling, and this is averaged. , <Γ> is required.
If this <Γ> exceeds 0.200, both the magnetic flux density and the iron loss of the product are greatly deteriorated.
[0022]
Hereinafter, the experimental results leading to the present invention will be described in detail.
The inventors have intensively studied to overcome the limitations of the prior art for improving the magnetic properties of the conventional high-Si non-oriented electrical steel sheet, and as a result, the magnetic orientation is controlled by appropriately controlling the orientation of the crystals constituting the steel sheet. The inventors have found out that the characteristics can be greatly improved and that it is advantageous to use an unprecedented <Γ> value as an index for controlling the crystal orientation. In order to achieve this, we also studied deeply the hot-rolled sheet annealing conditions and recrystallization annealing conditions, and found new particularly advantageous conditions.
[0023]
First, an experiment was conducted on the effects of Al and Sb. That is, steel ingot group A containing Si: 3.5 mass% and Mn: 0.10 mass% as components, reducing C, S, N, O and B to 20 ppm or less and changing the amount of Al contained in various ways. And as a component, Si: 3.5mass%, Mn: 0.10mass% and Sb: 0.04mass% are included, C, S, N, O and B are reduced to 20ppm or less respectively, and the amount of Al contained is variously changed. Each of the steel ingot groups B was melted. These steel ingots were then heated to 1040 ° C. and finished to a thickness of 2.3 mm by hot rolling. Thereafter, hot-rolled sheet annealing was performed at 1075 ° C. for 5 minutes, and cooling was performed at a rate of 800 to 400 ° C. at 20 ° C./s. Further, these annealed steel plates were pickled and cold-rolled at a temperature of 250 ° C. to a final thickness of 0.35 mm. After this cold rolling, these steel sheets were heated at a rate of temperature increase from 500 to 700 ° C. at 12 ° C./s and subjected to recrystallization annealing at 1050 ° C. for 10 minutes to obtain product sheets. Ring-shaped test pieces having an inner diameter of 100 mm and an outer diameter of 150 mm were collected from these products, and the magnetic flux density and iron loss of each steel plate were measured.
[0024]
FIG. 2 shows the relationship between the Al content of the material, the magnetic flux density of the product plate, and the iron loss. As shown in the figure, the magnetic characteristics fluctuate greatly depending on the Al content of the material, and B in the range of 0.0010 mass% to 0.10 mass%.₅₀1.68T or more and W_15/50 A good value of 2.1 W / kg or less is obtained, especially B in the range of 0.005 mass% to 0.020 mass%.₅₀1.70T or more, W_15/50 However, an extremely excellent value of 1.9 W / kg or less was obtained. In addition, in the steel ingot group B to which Sb was additionally added, a significant improvement in magnetic properties was observed.
[0025]
Furthermore, in order to find out the reason why excellent magnetic properties can be obtained, the crystal grain size of each product plate was investigated. Normally, in non-oriented electrical steel sheets, iron loss improves as the crystal grain size of the product plate increases, but in this experiment, the effects of the amount of material Al and Sb addition on the crystal grain size of the product plate are small. In either case, the grain size was 200 to 300 μm, and the value of magnetic properties and the grain growth behavior during recrystallization annealing were almost irrelevant. Therefore, the improvement of the magnetic properties in the range of Al content of 0.0010 to 0.10 mass% and the further improvement of the magnetic properties by adding Sb are considered to be due to the improvement of the crystal orientation, and the measurement of the crystal grain orientation of the product plate is performed by EBSP. It was performed using. This measurement was performed by measuring the orientation of about 2000 crystal grains in a 10 mm × 10 mm square region on the steel sheet surface.
[0026]
Here, the inventors have newly found that there is an extremely strong correlation between the <Γ> value and the magnetic flux density by analyzing using the newly created <Γ> value. The Γ value that determines this <Γ> value is a unique value in the crystal direction. For example, FIG. 3 shows the result of calculating the Γ value in each direction for {100} <001> crystal grains having a normal cube orientation. As shown in the figure, in the case of the rolling direction <100> in the normal cube-oriented crystal grains (u = 1, v = 0, w = 0, Γ = 0) and in the case of the rolling perpendicular direction <010> (u = 0, v = 1, w = 0, so Γ = 0) is the minimum value 0, and the direction <110> (u = 1 / √2, v = 1 / √2, w = 45 ° inclined from the rolling direction) Since it is 0, the maximum value is obtained when Γ = 0.25).
[0027]
The Γ value defined by the above formula (A) was calculated in the same manner based on about 2000 crystal grain orientation measurement results on the product plate. The Γ value was calculated by calculating the Γ value in the direction of interest (for example, the rolling direction) for each crystal orientation grain and taking the weighted average for the area of the grain. As a result, it was newly found that there is a strong correlation between the Γ value and the magnetic flux density of the product slope. For comparison, the intensity ratio of {111} plane strength (hereinafter referred to as I {111}) and {100} plane strength (hereinafter referred to as I {100}) using an X-ray diffraction method that has been conventionally used for comparison. (1) A survey on {100} / I {111} was also conducted. Incidentally, {circle around (1)} {100} / I {111} value is a texture evaluation method disclosed in Japanese Patent Laid-Open No. 8-134606.
[0028]
First, the magnetic flux density (B of each direction of a product board whose Al amount which belongs to the steel ingot group A is 0.01 mass%.₅₀) The Epstein samples were examined from different directions of 15 ° between the rolling direction (0 °) and the direction perpendicular to the rolling direction (90 °) by changing the cutting direction. FIG. 4 shows the relationship between the magnetic flux density and the Γ value in each direction of the product plate. As shown in FIG. 4, the magnetic east density and the Γ value fluctuate in each direction.
[0029]
Further, FIG. 5 shows the relationship between the magnetic east density and the Γ value. As shown in FIG. 5, it was found that there is a strong correlation between the product plate magnetic flux density and the Γ value. In FIG. 4, the value of I {100} / I {111} is also shown. Originally, since {1} {100} / I {111} value is the surface strength, as shown in FIG. It can be seen that the value in each direction of the measurement sample is almost constant, and in this case, the change in magnetic flux density is not reflected.
[0030]
Thus, since a strong correlation was observed between the Γ value and the magnetic flux density, the grain orientation measurement and the X-ray diffraction were similarly performed on the product plates of each steel ingot group, and the magnetic flux density in the ring sample was measured. The relationship between the measurement result of γ, the average value of the Γ values in the rolling surface and I {100} / I {111} was investigated. The Γ value in the plane is calculated by calculating the Γ value in each direction of 15 ° from the rolling direction (0 °) to the direction perpendicular to the rolling direction (90 °) using the measurement results in each crystal orientation. The average value of was obtained as <Γ>.
[0031]
That is, as shown in FIG. 6 showing the relationship between the product plate magnetic flux density and <Γ>, there is a strong correlation between the magnetic flux density in the ring sample and the in-plane average value <Γ> obtained from the crystal grain orientation measurement. Is recognized, B₅₀In order to obtain a high magnetic flux density of> 1.65 T, it has been found that <Γ> needs to be 0.200 or less. On the other hand, FIG. 7 shows the relationship between I {100} / I {lll} and product plate magnetic flux density investigated using the same sample, but no clear relationship is recognized between the two.
[0032]
The reason why the result of this experiment was obtained that the correlation between the magnetic flux density of the product plate and <Γ> was extremely strong, whereas the correlation between {1} {100} / I {111} was weak. Although it is not clear, in the evaluation method according to the present invention, <Γ> in each direction of the steel sheet is directly obtained from the orientation of each crystal grain, and the in-plane average value is calculated from these values. In the method of evaluating {111} / I {100}, the strength of only a few crystal grains in the vicinity of {111} and {100} is evaluated, and other relatively important crystal grains, for example, This is presumed to be because crystal grains having many orientations such as {544}, {221}, and {332} are ignored and the contribution of these strengths to the magnetic properties is excluded from the evaluation range.
[0033]
There are other advantages of using the Γ value. In general, the saturation magnetic flux density of a steel sheet changes depending on the content of elements other than iron. For this reason, even if the product plate has the same degree of orientation of crystal grains, the value of the magnetic flux density changes. Therefore, when comparing the degree of orientation accumulation of products with different components, the magnetic flux density value cannot be simply compared. However, since <Γ> is determined by the crystal orientation itself, the product is independent of the alloy composition. It is possible to evaluate the accumulation state of the crystal grain orientation of the plate, which is an extremely effective index.
[0034]
Next, the result of examining the relationship between the Al content and the impurity content will be described.
Ingot group B (including Si: 3.5 mass%, Mn: 0.10 mass%, and Sb: 0.03 mass%, with C, S, N, O and B reduced to 50 ppm or less, and various amounts of Al changed) Within the scope of the invention), Si: 3.5 mass% and Mn: 0.12 mass%, and each content of C, S, N, O and B is 50 ppm or more, and the total amount is 350 ppm or more and Al content. Steel ingot group C (outside the scope of the invention) with various changes was made. These steel ingots were then heated to 1100 ° C and finished to a thickness of 2.4 mm by hot rolling. Subsequently, after hot-rolled sheet annealing was performed at 1100 ° C. for 5 minutes, it was cooled between 800 and 400 ° C. at a rate of 15 ° C./s. Further, these annealed steel plates were pickled and finished to a final thickness of 0.35 mm by cold rolling at a temperature of 200 ° C. After cold rolling, these steel plates were subjected to recrystallization annealing at 1050 ° C. for 10 minutes to obtain product plates. The crystal grain orientation of the product plate thus obtained was measured by EBSP by measuring the orientation of about 2000 crystal grains in a 10 mm × 10 mm square region on the steel plate surface, and the average value in the rolling plane <Γ> Asked.
[0035]
FIG. 8 shows the relationship between the Al content in each steel ingot group and <Γ>. In the steel ingot group B in which the impurity elements C, S, N, O, and B are reduced, <Γ> is 0.200 or less. However, in steel ingot group C containing a large amount of impurity elements C, S, N, O, and B, <Γ> of 0.200 or less is not obtained. Furthermore, in the steel ingot group B, <Γ> of 0.195 or less, which is particularly advantageous for the magnetic flux density, is obtained when the Al content is in the range of 10 to 1000 ppm.
[0036]
As a result of further diligent research based on this experiment, in order to obtain a particularly good texture with <Γ> 0.195 or less, which is advantageous for improving the magnetic flux density, not only controlling the Al content, It has been found that it is essential to reduce the impurity elements C, S, N, O and B to 50 ppm or less.
[0037]
By the way, as described above, in high-grade non-oriented electrical steel sheets having a high Si content, a technique for increasing the specific electrical resistance has been adopted in order to improve iron loss. This method also has the effect of agglomerating and coarsening AlN, which is a precipitate in the steel that suppresses crystal grain growth, and promoting crystal grain growth. In order to obtain these effects, it is necessary to secure a certain amount of Al or more. Conventionally, the Al content is regulated to an amount exceeding at least 0.1 mass%, and usually 0.4 to 1.0 mass%. It is about the content. However, the results obtained by the above experiments by the inventors show that the texture is most suitably developed in a content range far lower than the range of the prior art, particularly in the range of 0.0010 to 0.10 mass%. Γ> was 0.195 or less, and both the magnetic flux density and the iron loss showed the best values.
[0038]
Thus, by reducing the impurity elements C, S, N, O and B in the material components to 50 ppm or less and controlling the Al content, a good texture with a low average Γ value in the rolling plane is obtained. Although it is not necessarily clear why this develops, the inventors consider the following in relation to the effect of suppressing the grain boundary migration of impurities. That is, the high purity of the material eliminates the influence of impurity elements, particularly C, S, N, O, and B, which have a strong tendency to segregate at grain boundaries, and facilitates the movement of grain boundaries, and reduces Al to 0.10 mass% or less. By reducing it, the crystal lattice arrangement closer to that of pure iron is approached, and the inherent movement speed difference that depends on the grain boundary structure becomes apparent, and only some of the grain boundaries are produced during the grain growth process associated with recrystallization. Move preferentially, the growth of a large number of magnetically disadvantageous grains such as {111}, {554}, {321}, etc. is suppressed, causing a texture change in the direction in which <Γ> decreases, It is considered that the magnetic properties have been improved. Regarding Sb, the effect of pre-recrystallization of the crystal orientation in the vicinity of the {100} orientation, which is advantageous for the magnetic properties at the time of recrystallization nucleation, is recognized, and by combining with the above-described effect when Al is reduced, Is estimated to be greatly improved.
[0039]
Further, when Al is less than 10 ppm, the effect of improving the magnetic characteristics due to the reduction of the impurity elements C, S, N, O, and B becomes small. In this case, it has been observed that coarse silicon nitride is formed in the steel, which changes the deformation behavior during cold rolling and slightly increases <Γ> in the structure after recrystallization annealing. Estimated. Therefore, although <Γ> decreases due to the reduction of impurity elements, it seems that the improvement in magnetic properties is reduced as a result. On the other hand, when the Al content is 10 ppm or more, the formation of this coarse silicon nitride is suppressed, and an increase in <Γ> due to the change in deformation behavior during cold rolling as described above can be avoided. Therefore, it is particularly advantageous for improving the magnetic characteristics.
[0040]
Thus, in order to make the <Γ> value 0.200 or less, it is important that the impurity elements C, S, N, O, and B each be 50 ppm or less, but the Al content is further 0.001 to 0.10 mass. % And by adding a predetermined amount of Sb as required, the <Γ> value can be reduced to 0.195 or less, which is more advantageous for magnetic properties.
[0041]
By the way, the method of improving the texture by improving the texture without adding a large amount of Al according to the present invention increases the hardness in addition to the advantage of high saturation magnetic flux density because the added amount of alloy elements is small. Since it is avoided and processability of the product is ensured, there is also an advantage that application to general-purpose electrical products is promoted.
[0042]
Furthermore, in order to establish another technique that enables the texture to be improved and the <Γ> value to be 0.200 or less, an experiment on hot-rolled sheet annealing conditions was performed.
That is, a steel ingot containing Si: 3.6 mass%, Mn: 0.13 mass%, Al: 0.009 mass%, and Sb: 0.06 mass% and having C, S, N, O, and B reduced to 20 ppm or less each is melted. did. The ingot was then heated to 1120 ° C and finished to 2.8mm by hot rolling. Next, after hot-rolled sheet annealing at 1100 ° C. for 5 minutes, cooling was performed by changing the cooling rate in various ways. Further, these annealed steel plates were pickled and finished to a final thickness of 0.50 mm by cold rolling at a temperature of 230 ° C. After cold rolling, recrystallization annealing was performed at 1070 ° C. for 10 seconds to obtain a product plate. A ring test piece having an inner diameter of 100 mm and an outer diameter of 150 mm was taken from the product plate thus obtained, and the magnetic flux density and iron loss of each steel plate were measured. Further, the crystal grain orientation of the product plate was measured by measuring the orientation of about 2000 crystal grains in a 10 mm × 10 mm square region on the steel plate surface by EBSP to obtain <Γ> in the rolling plane.
[0043]
FIG. 9 shows the relationship between the cooling rate in the temperature range of 800 to 400 ° C. after the hot-rolled sheet annealing and <Γ>, so that the cooling rate is in the range of 5 to 80 ° C./s. It was found that a particularly good texture with Γ> of 0.195 or less can be obtained. Probably, by controlling the cooling rate, the dispersion state of the AlN precipitates that are present in minute amounts becomes finer, and as a result, non-uniform deformation during cold rolling is promoted and the recrystallized structure is improved. However, the essential mechanism of texture improvement is not clear.
[0044]
Next, as a requirement for further improving the iron loss and the magnetic flux density, the following experiment was performed by changing the recrystallization annealing conditions.
That is, steel ingot D including Si: 3.6 mass%, Mn: 0.13 mass%, and Al: 0.30 mass%, with C, S, N, O, and B each reduced to 20 ppm or less, Si: 3.6 mass%, Mn : Steel ingot E containing 0.13 mass%, Al: 0.009 mass%, and Sb: 0.06 mass%, each containing C, S, N, O, and B reduced to 20 ppm or less. These steel ingots were then heated to 1070 ° C. and finished to a thickness of 2.5 mm by hot rolling. Then, hot-rolled sheet annealing was performed at 1170 ° C. for 5 minutes, and cooling was performed at a cooling rate between 800 ° C. and 400 ° C. at 10 ° C./s. Further, these annealed steel plates were pickled and cold-rolled at a temperature of 200 ° C. to a final thickness of 0.35 mm. After this cold rolling, samples were taken from each steel plate, and recrystallized annealing was performed separately by the following three methods to obtain product plates.
[0045]
[Annealing 1]
Rate of temperature rise: 30 ° C / s on average from normal temperature to 500 ° C, 15 ° C / s on average between 500-700 ° C, 8 ° C / s on average between 700-900 ° C, soaking 900 ° C x 10 seconds
Cooling rate: Average 10 ℃ / s from soaking to room temperature
Annealing atmosphere: 50% hydrogen, 50% nitrogen, dew point -30 ℃
[Annealing 2]
Temperature increase rate: average 100 ° C / h between normal temperature and 500 ° C, 50 ° C / h between 500-900 ° C, soaking 900 ° C x 10 hours,
Cooling rate: average 100 ℃ / h from soaking to room temperature
Atmosphere: Ar dew point -30 ° C
[Annealing 3]
After annealing 1, annealing 2 is performed.
[0046]
Ring specimens having an inner diameter of 100 mm and an outer diameter of 150 mm were collected from these product plates, and the magnetic flux density and iron loss of each specimen were measured. Further, the crystal grain orientation of the product plate was measured by EBSP on about 2000 crystal grains in a 10 mm × 10 mm square region on the steel plate surface, and the <Γ> value was obtained.
[0047]
FIG. 10 shows the relationship between recrystallization annealing conditions and magnetic properties, and FIG. 11 shows the relationship between recrystallization annealing conditions and <Γ>. First, with respect to iron loss, the steel loss of any steel ingot after passing through annealing 2 and further annealing 3 is better than that of annealing 1. In particular, the iron loss of the steel ingot E to which Sb is added is good. On the other hand, regarding the magnetic flux density, in the steel ingot E to which Al and Sb were added, annealing 2 and annealing 3 were improved as compared with annealing 1, but Sb was not contained and Al was out of the scope of the invention. There is no change in the steel ingot E contained at mass%. Regarding <Γ>, the change corresponding to the change of the magnetic flux density is shown, and the lowest <Γ> and the high magnetic flux density are obtained in the steel ingot C.
[0048]
FIG. 12 shows the relationship between the grain size after recrystallization annealing and the recrystallization annealing conditions. As shown in FIG. 12, the maximum temperature reached in each annealing condition is the same as 900 ° C., but in the annealing 2 with a slow temperature rise compared to the annealing 1 with a rapid temperature rise, the grain growth proceeds slightly. However, in the annealing 3 in which the rapid temperature increase was performed and then the low temperature increase was performed, especially in the steel ingot E, the grain growth was progressing remarkably compared with the annealing 1 and 2. In the case of annealing 2, it is considered that the grain growth progressed because the reached temperature was the same as that of annealing 1, which is rapid temperature increase, but the soaking time was different. Although the annealing 3 is slightly different from the annealing 2 in terms of thermal effectiveness, the particle size is remarkably increased as compared with the annealing 2. When annealing 2 and annealing 3 are compared, the rate of temperature rise during recrystallization nucleation is different, and the difference in recrystallization texture based on the difference in the texture formation process resulting from this greatly increases the subsequent grain growth behavior. Presumed to have changed, but the essential mechanism is not clear.
[0049]
Furthermore, when the additive element of the material was examined, it was found that the magnetic flux density of the product was improved by adding Ni. It is presumed that Ni is a ferromagnetic element for some reason for the improvement of the magnetic flux density, but the reason is not clear. Moreover, the tendency for an iron loss to improve by addition of Sn, Cu, P, Cr, etc. was recognized. It is presumed that iron loss is reduced by increasing the electrical resistance.
[0050]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the reasons for limiting the respective constituent requirements of the present invention will be described.
That is, as a component of the electrical steel sheet of the present invention, it is necessary to contain Si and increase the electrical resistance to reduce the iron loss, but in order to improve this iron loss, 1.5 mass% or more of Si is necessary. is there. On the other hand, if it exceeds 8.0 mass%, the magnetic flux density is lowered and the secondary workability of the product is remarkably deteriorated, so the Si content is limited to 1.5 to 8.0 mass%.
[0051]
Mn is a component necessary for improving the hot workability, but if it is less than 0.005 mass%, the effect is poor, while if it exceeds 2.50 mass%, the saturation magnetic flux density decreases, so 0.005 to 2.50 mass%. Range.
[0052]
Further, in order to realize the crystal orientation expected in the present invention, it is essential to reduce the trace components of the steel sheet. That is, in the entire steel sheet excluding the coating on the steel sheet surface, the contents of C, S, N, O and B must each be 50 ppm or less, preferably 20 ppm or less. <Γ> increases and iron loss increases.
[0053]
Next, in the present invention, it is essential to control the crystal orientation. That is, in order to obtain good magnetic properties, it is important that the average value <Γ> in the rolling plane of the Γ value determined by the above formula (A) is 0.200 or less, for the reason described above. is there.
[0054]
Next, the method for producing the electromagnetic steel sheet will be described in detail.
First, as a molten steel component, as described above, the Si content is regulated to 1.5 to 8.0 mass% and the Mn content to 0.005 to 2.50 mass%.
[0055]
And it is essential to regulate the upper limit of impurity elements of C, S, N, O and B as 50 ppm, preferably 20 ppm. Regarding C, it may be 50 ppm or less at the molten steel component stage, or it may be 50 ppm or less by decarburization treatment in the intermediate process even if it exceeds 50 ppm at the molten steel stage, and at least 50 ppm or less before recrystallization annealing. It is essential. When the content of these impurities exceeds 50 ppm, the selective movement of special grain boundaries is hindered, and the <Γ> value after recrystallization annealing increases and the magnetic properties deteriorate.
[0056]
Further, the control of the Al amount is the most advantageous technique for obtaining a non-oriented electrical steel sheet having <Γ> of 0.200 or less according to the present invention, and in particular, products having a good texture <Γ> of 0.195 or less. In order to obtain it, it is suitable for Al to be in the range of 0.0010 to 0.10 mass%. That is, when Al exceeds 0.10 mass%, the texture changes, <Γ> in the product plate increases, and iron loss and magnetic flux density deteriorate. On the other hand, when Al is less than 0.0010 mass%, silicon nitride precipitates and affects the deformation behavior during rolling, the texture is changed, and <Γ> is slightly increased. Impurity elements C, S, N, Since the effect of <Γ> reduction due to the reduction of O and B becomes small, it is advantageous to improve the iron loss and magnetic flux density that Al is made 0.0010 mass% or more.
[0057]
In addition to the above-described method by adjusting the components, it is preferable to perform hot-rolled sheet annealing in the temperature range of 800 to 1200 ° C, and then perform cooling at 800 to 400 ° C at a rate of 5 to 80 ° C / s. It is effective to obtain a texture, specifically an organization where <Γ> is 0.195 or less.
That is, if the hot-rolled sheet annealing temperature is less than 800 ° C, recrystallization of the hot-rolled sheet becomes insufficient and the magnetic properties are not improved sufficiently, while if the hot-rolled sheet annealing temperature exceeds 1200 ° C, Since the crystal grain size of the rolled sheet becomes too coarse and cracks occur during cold rolling, the temperature is preferably set to 800 to 1200 ° C. The cooling rate is as described above.
[0058]
  Furthermore, by additionally adding Sb, the recrystallization nucleation behavior can be changed to reduce <Γ> of the product plate, and good magnetic properties can be obtained. That is, if the amount of Sb added is less than 0.01 mass%, there is no effect of improving the texture. On the other hand, if it exceeds 0.50 mass%, embrittlement and cold rolling become difficult, so the range is 0.01 to 0.50 mass%. .
[0059]
Next, the rate of temperature increase at 700 ° C or higher during recrystallization annealing is gradually increased to 100 ° C / h or less to reach the temperature range of 750 ° C to 1200 ° C, which promotes grain growth and improves magnetic properties. It is effective to improve. That is, when the temperature rising rate at 700 ° C. or higher exceeds 100 ° C./h, the effect of improving the texture is reduced. Therefore, the temperature rising rate is preferably 100 ° C./h or lower. In addition, although the minimum of a temperature increase rate is not defined especially, when a temperature increase rate is less than 1 degree-C / h, annealing time is too long and it is economically disadvantageous. On the other hand, when the recrystallization annealing temperature is less than 750 ° C, the grain growth is insufficient and the magnetic properties deteriorate, and when it exceeds 1200 ° C, the surface oxidation proceeds and the iron loss deteriorates. The ultimate temperature for annealing is preferably 750 ° C or higher and 1200 ° C or lower. The soaking time is not particularly defined, but in order to obtain good iron loss, it is effective to promote grain growth as long as it is economically acceptable.
[0060]
Furthermore, to remarkably promote grain growth and improve magnetic properties, in the first half of recrystallization annealing, the temperature increase rate between 500-700 ° C is increased to 700 ° C or higher as a rapid temperature increase of 2 ° C / s or higher. The recrystallization is then completed, and in the second half, the temperature is cooled to 700 ° C or lower, and the temperature rise rate at 700 ° C or higher is set to 100 ° C / h or lower to reach the temperature of 750 ° C or higher to 1200 ° C or lower. It is valid.
[0061]
That is, if the rate of temperature increase between 500 and 700 ° C. at the time of temperature increase in the first half of recrystallization annealing is less than 2 ° C./s, the effect of promoting grain growth in the latter half of annealing is reduced. The heating rate between 500 and 700 ° C. is preferably 2 ° C./s or more. Similarly, when the temperature of the first half of recrystallization annealing is less than 750 ° C and exceeds 1200 ° C, the effect of promoting grain growth in the latter half of annealing is reduced, so the ultimate temperature during the first half of recrystallization annealing is 750 to 1200 ° C. It is desirable to do. When the rate of temperature increase in the second half of the recrystallization annealing exceeds 100 ° C./h, the effect of improving the texture becomes small. Therefore, the preferred range of the temperature increase rate in the second half of the recrystallization annealing is set to 100 ° C./h or less. Also, if the temperature reached in the latter half of the recrystallization annealing is less than 750 ° C, the magnetic properties deteriorate due to insufficient grain growth, and if it exceeds 1200 ° C, surface oxidation proceeds and iron loss deteriorates. The ultimate temperature in the second half of annealing is preferably 750 ° C or higher and 1200 ° C or lower. The soaking time in the second half of the recrystallization annealing is not particularly defined, but it is effective to promote grain growth for a long time within an economically acceptable range in order to obtain good iron loss.
[0062]
Here, the rate of temperature increase up to 500 ° C. does not have a great influence on the recrystallization behavior, and thus there is no need to regulate it. Also, the cooling conditions need not be particularly restricted in terms of magnetic properties, but economically, a speed in the range of 60 ° C./min to 10 ° C./hr is advantageous.
[0063]
Furthermore, Ni can be added to improve the magnetic flux density. If the amount of Ni added is less than 0.01 mass%, the improvement in magnetic properties will be small. On the other hand, if it exceeds 1.50 mass%, the texture will be insufficient and the magnetic properties will deteriorate, so the amount added will be 0.01 to 1.50. Mass%. Similarly, in order to improve iron loss, it is also effective to add Sn: 0.01-1.50 mass%, Cu: 0.01-1.50 mass%, P: 0.005-0.50 mass%, Cr: 0.01-1.50 mass% . When the addition amount is less than this range, there is no iron loss improvement effect, and when the addition amount is large, the saturation magnetic flux density is lowered.
[0064]
Incidentally, the molten steel having the above-described components may be formed into a slab by a normal ordinary ingot casting method or a continuous casting method, or a thin cast piece having a thickness of 100 mm or less may be produced by a direct casting method. Next, the slab is heated and hot-rolled by a normal method, but may be immediately hot-rolled without being heated after casting. In the case of a thin slab, hot rolling may be performed, or the hot rolling may be omitted and the process may proceed as it is. Subsequently, hot-rolled sheet annealing is performed, and if necessary, after one or more cold rolling sandwiching the intermediate annealing, continuous annealing is performed, and if necessary, an insulating coating is applied. Finally, in order to improve the iron loss of the laminated steel plates, an insulating coating is applied to the steel plate surface. For this purpose, a multilayer film composed of two or more kinds of coatings may be used, or a resin or the like may be mixed. A coated coating may be applied.
[0065]
【Example】
Example 1
A steel slab having the components shown in Table 1 was manufactured by continuous casting, and then the slab was heated at 1250 ° C. for 50 minutes and finished to a thickness of 2.3 mm by hot rolling. Then, hot-rolled sheet annealing is performed at 1150 ° C for 60 seconds, cooled between 800-400 ° C at 15 ° C / s, and cold rolled at a temperature of 170 ° C to finish to a final thickness of 0.35mm. It was. Subsequently, recrystallization annealing was performed in a hydrogen atmosphere at 1050 ° C. for 3 minutes, a semi-organic coating solution was applied, and baked at 300 ° C. to obtain a product.
[0066]
Then, from this product plate, a ring-shaped sample with an outer diameter of 150 mm and an inner diameter of 100 mm is taken and its magnetic properties are measured, and the orientation of crystal grains in the 10 mm x 10 mm square region on the product plate surface is measured by EBSP. <Γ> was calculated. As these measurement results are also shown in Table 1, it can be seen that the steel sheet according to the present invention has good magnetic properties.
[0067]
[Table 1]

[0068]
Example 2
C: 38ppm, Si: 3.24mass%, Mn: 0.15mass%, Al: 0.013mass%, Sb: 0.02mass%, S: 11ppm, O: 7ppm, N: 9ppm and B: 2ppm, the balance being substantial A slab with a component composition of Fe was manufactured by continuous casting. This slab was heated at 1150 ° C. for 30 minutes and finished to a thickness of 2.9 mm by hot rolling. Then, hot-rolled sheet annealing was performed at 1050 ° C. for 60 seconds, cooled between 800 ° C. and 400 ° C. at 8 ° C./s, and finished to a thickness of 0.35 mm by cold rolling. Next, in a hydrogen atmosphere, recrystallization annealing was performed in which the temperature was raised at the rate of temperature rise shown in Table 2 and cooled after reaching the maximum temperature. Finally, an inorganic coating solution was applied and baked at 300 ° C. to obtain a product.
[0069]
Then, from this product plate, a ring-shaped sample with an outer diameter of 150 mm and an inner diameter of 100 mm is taken and its magnetic properties are measured, and the orientation of crystal grains in the 10 mm x 10 mm square region on the product plate surface is measured by EBSP. <Γ> was calculated. As shown in Table 2, these measurement results are shown in Table 2. The heating rate from room temperature to 700 ° C during recrystallization annealing is 200 ° C / h, and the average heating rate at 700 ° C or higher is 1 ° C to 100 ° C / h. It can be seen that a product having particularly good magnetic properties can be obtained by reaching a temperature of 750 ° C. or higher and 1200 ° C. or lower as h.
[0070]
[Table 2]

[0071]
Example 3
Thin cast slabs having a thickness of 4.5 mm made of the components shown in Table 3 were produced by direct casting. Next, hot-rolled sheet annealing is performed at 1150 ° C. for 30 seconds, cooled to 800 ° C./s at 50 ° C./s, made 1.6 mm thick by cold rolling at room temperature, and then subjected to intermediate annealing at 1000 ° C. After 60 seconds, it was finished to a thickness of 0.20 mm by cold rolling at room temperature. Finally, in the Ar atmosphere, the product was subjected to the first and second recrystallization annealing under the conditions shown in Table 3 to obtain a product.
[0072]
Then, from this product plate, a ring-shaped sample with an outer diameter of 150 mm and an inner diameter of 100 mm is taken and its magnetic properties are measured, and the orientation of crystal grains in the 10 mm x 10 mm square region on the product plate surface is measured by EBSP. <Γ> was calculated. As these measurement results are also shown in Table 3, by setting the rate of temperature increase at 700 ° C. or higher during recrystallization annealing to 1 ° C. to 100 ° C./h and reaching a temperature of 750 ° C. or higher and 1200 ° C. or lower, It can be seen that a product with good magnetic properties can be obtained.
[0073]
[Table 3]

[0074]
Example 4
After manufacturing the slab of the component shown in Table 4 by continuous casting, the slab was heated at 1200 ° C. for 50 minutes and finished to a thickness of 2.6 mm by hot rolling. Subsequently, hot-rolled sheet annealing was performed at 1180 ° C. for 120 seconds, cooled between 800 ° C. and 400 ° C. at 30 ° C./s, and cold-rolled at a temperature of 150 ° C. to a final sheet thickness of 0.35 mm. Thereafter, recrystallization annealing was performed in an Ar atmosphere at 1150 ° C. for 1 minute, and a semi-organic coating solution was applied and baked at 300 ° C. to obtain a product.
[0075]
Then, from this product plate, a ring-shaped sample with an outer diameter of 150 mm and an inner diameter of 100 mm is taken and its magnetic properties are measured, and the orientation of crystal grains in the 10 mm x 10 mm square region on the product plate surface is measured by EBSP. <Γ> was calculated. As these measurement results are also shown in Table 4, it can be seen that the steel sheet according to the present invention has good magnetic properties.
[0076]
[Table 4]

[0077]
【The invention's effect】
According to this invention, it is possible to obtain a non-oriented electrical steel sheet having excellent magnetic flux density and iron loss that surpasses the magnetic characteristics obtained by the prior art.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a procedure for calculating <Γ>.
FIG. 2 is a diagram showing the relationship between Al content, magnetic flux density, and iron loss.
FIG. 3 is a diagram illustrating <Γ> in each direction on a product plate.
FIG. 4 is a diagram showing magnetic flux density and <Γ> in each direction on a product plate.
FIG. 5 is a diagram illustrating a relationship between magnetic flux density in a product plate and <Γ>.
FIG. 6 is a diagram showing the relationship between product plate magnetic flux density and <Γ> value.
FIG. 7 is a diagram showing the relationship between product plate magnetic flux density and {l00} / {lll} value.
FIG. 8 is a diagram showing the relationship between the amount of material Al and the product plate <Γ> value.
FIG. 9 is a diagram showing the relationship between the cooling rate after hot-rolled sheet annealing and the product plate <Γ> value.
FIG. 10 is a diagram showing the relationship between finish annealing conditions and iron loss and magnetic flux density of a product plate.
FIG. 11 is a diagram showing the relationship between finish annealing conditions and product plate <Γ> value.
FIG. 12 is a diagram showing the relationship between finish annealing conditions and product plate particle size.

Claims (8)

Si: 1.5 ~8.0 mass%, Mn : 0.005 ~2.50mass% and Al: 0.0010 comprises ~ 0.10 mass%, and suppresses C, S, N, each of 50ppm or less content of O and B, the balance Fe and A non-oriented electrical steel sheet having a component composition consisting of inevitable impurities and having an average value <Γ> in a rolling plane of a Γ value determined by the following formula from the orientation of each crystal grain of the steel sheet is 0.195 or less.
Γ = u ² v ² + v ² w ² + w ² u ²
Here, u, v, and w mean <u, v, w> obtained by converting the Miller index display into a unit vector in an arbitrary direction from the rolling direction of each crystal grain to the rolling perpendicular direction. Oite to claim 1, further Sb: non-oriented electrical steel sheet characterized by comprising a component composition containing 0.01~0.50mass%. In any one of Claim 1 or 2 , Ni: 0.01-3.50mass%, Sn: 0.01-1.50mass%, Cu: 0.01-1.50mass%, P: 0.005-0.50mass% and Cr: 0.01-1.50mass% A non-oriented electrical steel sheet having a component composition containing at least one kind. Si: 1.5 to 8.0 mass%, Mn: 0.005 to 1.50 mass%, and Al: 0.0010 to 0.10 mass%, and the contents of S, N, O, and B are each suppressed to 50 ppm or less, the remainder Fe and inevitable The molten steel containing impurities is used as a slab, and then hot-rolled sheet annealing is performed after hot rolling, and then cold rolling is performed once or two or more times with intermediate annealing between them to finish to the final sheet thickness, and then recrystallization is performed. In a series of processes where annealing is performed and insulation coating is applied as necessary, the C content of the steel sheet is adjusted to 50 ppm or less in either process prior to molten steel or prior to recrystallization annealing, and hot-rolled sheet annealing is performed at 800 to After applying in the temperature range of 1200 ° C, cooling at 800-400 ° C is performed at a rate of 5-80 ° C / s, and recrystallization annealing is performed at a temperature increase rate of 700 ° C / h in a temperature range of 700 ° C or higher. The temperature range from 750 ° C to 1200 ° C is as follows. A method for producing grain-oriented electrical steel sheets. Si: 1.5 ~8.0 mass%, Mn : 0.005 ~2.50mass% and Al: comprises 0.0010 ~ 0.10 mass%, and S, N, and suppressing each 50ppm or less content of O and B, the balance Fe and unavoidable The hot metal strip is subjected to hot rolled sheet annealing after hot rolling, and then subjected to cold rolling twice or more with intermediate annealing and finished to the final sheet thickness. In a series of processes in which crystal annealing is performed and insulation coating is applied as necessary, the C content of the steel sheet is adjusted to 50 ppm or less in either of the processes prior to molten steel or prior to recrystallization annealing, and hot rolled sheet annealing is performed to 800 After applying in the temperature range of ~ 1200 ° C, cooling at 800-400 ° C is performed at a rate of 5-80 ° C / s, and recrystallization annealing is performed at a temperature increase rate of 2 in the temperature range of 500-700 ° C or higher. After the recrystallization is completed by raising the temperature to 700 ° C or higher at a temperature of ℃ / s or higher, A method for producing a non-oriented electrical steel sheet characterized by cooling to a temperature range and again reaching a temperature range of 750 ° C. to 1200 ° C. with a rate of temperature increase in the temperature range of 700 ° C. or more being 100 ° C./h or less . In Claim 4 or 5 , Sb: 0.01-0.50mass% is contained, The manufacturing method of the non-oriented electrical steel sheet characterized by the above-mentioned. Si: 1.5 ~8.0 mass%, Mn : 0.005 ~1.50mass%, Al: 0.0010 ~ 0.10mass% and Sb: comprises 0.01~0.50mass%, and S, N, below each 50ppm the content of O and B Suppress and make the molten iron of the component consisting of the balance Fe and inevitable impurities into slabs, then hot-rolled sheet annealing after hot rolling, and then cold rolling more than once with one or more intermediate annealing in between Finishing to the final thickness, then performing recrystallization annealing, adjusting the C content of the steel sheet to 50 ppm or less in either of the processes before molten steel or prior to recrystallization annealing in a series of processes for applying insulation coating as necessary And a method for producing a non-oriented electrical steel sheet, characterized by performing hot-rolled sheet annealing in a temperature range of 800 to 1200 ° C and then cooling at 800 to 400 ° C at a rate of 5 to 80 ° C / s. . The molten steel according to any one of claims 4 to 7 , further comprising Ni: 0.01 to 3.50 mass%, Sn: 0.01 to 1.50 mass%, Cu: 0.01 to 1.50 mass%, P: 0.005 to 0.50 mass%, and Cr: 0.01 to 1.50. A method for producing a non-oriented electrical steel sheet, comprising at least one mass%.

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