JP3852227B2 - Non-oriented electrical steel sheet and manufacturing method thereof - Google Patents

Description

【００１７】
【表２】

【００１８】
上記実験工程の過程および得られた製品について、以下のように組織と特性値の測定を行った。
▲１▼ 熱延板焼鈍の前後における鋼板断面の再結晶率（全視野面積に対する再結晶粒の占める面積の百分率）
▲２▼ 製品に対する標準測定法によるエプスタイン試験ならびに４方向測定法による各種試験
▲３▼ モータ効率の測定（固定子外径130mm、回転子径50mm、胴長70mmの３相６極120Hz、120v、400wの誘導モータによる）
測定結果はまとめて表３に示す。
【００１９】
【表３】

【００２０】
表３に示すようにA-4（鋼Aに対し処理4を行った場合、以下同様）、A-5、B-4、B-5、Ｂ-6およびC-4、C-5、C-6は、標準測定法において磁束密度も鉄損も優れているが、モータ効率はA-2の場合のみが優れている。すなわち、モータ効率には製品の磁気特性が必ずしも反映されていない。この理由を調査した結果、A-2の製品は２方向測定試験による磁気特性の測定は劣るが、４方向測定試験の磁気特性は、鉄損W_15/50が2.325W/kg（これに対しA-6は2.483W/kg）と極めて良好な値を示しているためであることが分かった。また、A-2の場合、４方向測定法における1.5T、50Hzの透磁率の値が12310 G/θと高かったのに対し、A-6の場合は11590 G／θしかなく、これがモータ効率を下げる原因となっている。
【００２１】
このような標準測定法と４方向測定法との間の測定値の乖離は、主として鋼板の結晶組織のうち、集合組織によってもたらされる。すなわち、標準測定法による測定では圧延方向および圧延直角方向の２方向のみに優れた集合組織を有する材料が特に有利に評価されるのに対し、４方向測定法では鋼板面内における異方性の少ない集合組織がより有利に評価され、回転機の特性評価として適切なものになる。ちなみに、A-2の製品の結晶組織の主要集合組織は｛１００｝＜ｕｖｗ＞であった。
【００２２】
このように、標準測定法による結果と４方向測定法による結果の乖離は、材料の異方性を表す指標となるので、本発明においては両者の比により異方性定数を定義する。すなわち、鉄損の異方性定数として、４方向測定法によるW_15/50の値を標準測定法によるW_15/50の測定値で割った値を採用し、また、透磁率異方性定数として、標準測定法による1.0T、50Hzの透磁率の値を４方向測定法による1.0T、50Hzの透磁率の値で割った値を採用する。異方性定数は１に近いほど異方性が弱く、モータ特性にとって有利である。
【００２３】
この場合、モータなどの回転機用材料に対する４方向測定法の測定条件としては、上記のように、鉄損については、1.5T、50Hzの条件が、透磁率については1.0T、50Hzの条件が一般的に受け入れられるものとなるが、、設計磁場や、高周波設計されたモータに対しては、当然、より低磁束度側または高磁束密度側あるいはより高周波側の測定条件を採用することができる。
【００２４】
さらに、本発明者は、表３の結果からB₅₀/Bsの値とモータ効率はよい相関があり、優れたモータ効率を得るためにはB₅₀/Bsが0.8以上であることが必要であるとの知見を得た。ここにBsとは、電磁鋼板の飽和磁束密度であり、B₅₀ は5000A/mの最大磁場で、50Hzにおける最大磁束密度をいう。単にBs値が高くても、異方性が大きいときにはモーターなど回転にの実機特性の改善は顕著とならない。なお、B₅₀/Bsの値が１を超えることはあり得ないので、B₅₀/Bsが１に近い材料が回転機用には適した材料となる。
【００２５】
すなわち、モータのティース部はモータ内で特に容積が小さくなっている部分であり、磁束が集中するので、その部分の磁束密度が高くなければ、モータの実機特性が向上しない。しかも、モータのティース部は電磁鋼板の圧延方向に対して360°の全方向に分布しており、圧延方向と圧延直角方向のみを評価する標準測定法ではこのような条件に対応できない。４方向測定法によるB₅₀の値を用いて算出したB₅₀/Bsの値はティース部の材料特性評価としてより適切であり、従来の基準に替わるものである。
【００２６】
上記のように、本発明は回転機の実機特性の面から無方向性電磁鋼板の特性を再検討し、新しい評価基準を確立し、従来にない特性を有する回転機用無方向性電磁鋼板を提案するものである。しかしながら、本発明は、従来からの評価基準である鉄損値W_15/50および磁束密度B₅₀の価値を否定するものではなく、これらの値が優れていれば一層効果のあることは当然である。
【００２７】
以下、上記本発明の特性を有する無方向性電磁鋼板を製造する手段について説明する。
【００２８】
まず、出発材料であるスラブの組成として、Sn及び／又はSbを含有することが必要である。表３に示したA-2とB-2を対比すると、これらは同一の熱延、熱処理工程および冷延工程を受けているにもかかわらず、A-2の結晶組織は主として｛１００｝＜ｕｖｗ＞の集合組織からなり、優れた回転機実機特性を示しているのに対し、B-2の４方向測定法の結果は、鉄損値、磁束密度、透磁率ともに劣り、かつ、組織的にも｛１１１｝＜ｕｖｗ＞が主方位であり、異方性は小さいものの、磁気特性上好ましくないものとなっていた。
【００２９】
A-2とB-2の相違点は、鋼中にSnやSbなどの粒界偏析元素を含有しているか否の点にある。さらに詳細にSnおよびSbに影響を調査したところ、これら元素を合計量で0.003%〜0.20%含有する場合には、これら元素が冷間圧延前の結晶粒界に偏析し、冷延後の焼鈍段階で｛１１１｝＜ｕｖｗ＞方位粒の再結晶を抑制し、結晶主方位として｛１００｝＜ｕｖｗ＞を有する粒の再結晶・粒成長を促進されることが判明した。したがって、SnあるいはSbを単独あるいは複合して合計量で0.003%以上を含有させる。しかしながら、0.20%を超えると、加工性が劣化し実用的でないので、0.20%以下に留める。
【００３０】
次に、結晶粒を十分成長させ、｛１００｝＜ｕｖｗ＞集合組織を発達させる手段を講ずることが必要である。この条件の一つには、前述のSnあるいはSbの適量添加である。ちなみに、前記A-2は結晶粒径が120μｍと粗大であるのに対し、B-2は90μmであった。
【００３１】
しかし、それだけでは十分ではない。不純物元素の含有量を十分低下させることが必要である。このことは、鋼Ｃを用いて鋼Ａと同一の処理２（表２参照）を行った場合、鋼Cが鋼Aと同様Sbを含有し、表３に示すように４方向測定法による透磁率において良好な値を示しているにも拘わらず、C-2の場合は結晶粒径が55μmと小さく、そのため、鉄損値が増加し、モータ効率を劣化させていることから明らかである。なお、C-2の場合、集合組織が｛１００｝＜ｕｖｗ＞となっているとはいえ、その強度が弱く、そのため４方向測定法によるB₅₀/Bsも劣っていた。
【００３２】
不純物としては、S：0.0050%以下、N：0.0040%以下、O：0.0030%以下とするほか、Ti：0.0030%以下、Zr：0.0030%以下、V：0.0050%以下、B：0.0010%以下、Nb：0.0050%以下に制限する必要がある。この不純物を低下させることによって、従来再結晶・粒成長の駆動力が極めて弱く、かつ、結晶粒径が小さく細粒化しやすいとされてきた｛１００｝＜ｕｖｗ＞集合組織を十分に発達させることができる。
【００３３】
本発明に係る回転機の実機特性の優れた無方向性電磁鋼板を得るためには、熱間仕上げ圧延で十分な歪を熱延板に導入することが必要である。ちなみに、鋼Aについて、熱延スケジュールのみを変更した場合において、処理１を行った場合（A-1）に比べ、処理２を行った場合（A-2）の方が回転機用として良好な磁気特性となっている。本発明においては、熱間仕上げ圧延の際の歪の導入の程度を仕上げ圧延の後段４パスの累積圧下率で評価し、その値を65%以上とする。これにより、熱延コイル中に高密度の加工歪を含有させることができる。しかし、95%を超えると仕上げ圧延自体が困難となるので95%以下とする。なお、仕上げ圧延の後段における圧下率を高めるため、必要とあらば、粗圧延を省略するなどの手段をとることも可能である。
【００３４】
また、上記により歪みの導入された熱延板を焼鈍するに際し、熱延板から歪を除去しながら、再結晶を抑制する条件を採用することが必要である。これにより、熱延板の焼鈍過程、特に、回復過程で、内部のサブグレインの組織を良好なものとする。すなわち、旧結晶粒界およびから旧結晶粒内の変形帯から｛１１１｝＜ｕｖｗ＞を有する結晶粒の再結晶を抑制することが可能になり、旧結晶粒内から｛１００｝＜ｕｖｗ＞の方位を有する粒の再結晶が促進される。
【００３５】
具体的には、まず、仕上げ圧延終了後の熱延コイル巻取り温度を700℃以下とする。コイル巻取り温度を700℃を超える温度とした場合には、鋼板の一部が再結晶を開始し、これにより｛１１１｝＜ｕｖｗ＞方位の集合組織が増加し、回転機の実機の効率を低下するからである。そのため、熱延終了後、仕上げ圧延機出側においてジェット水を噴射するなどの手段を取り、巻取り温度が700℃以下となるようにするのがよい。
【００３６】
次に、上記熱延板に対し、圧延ひずみを回復しながら再結晶率を40%以下とする熱処理を施す。再結晶率が40％を超える場合、再結晶粒の粒界から｛１１１｝＜ｕｖｗ＞方位の再結晶粒が増加し、製品の集合組織ならびに磁気特性が劣化するからである。ちなみに、A-2とA-4、A-5あるいはA-6とを比較すればわかるように、A-4、A-5、A-6の場合は、冷間圧延前の鋼板の再結晶率が高く、そのため、冷間圧延、仕上げ焼鈍後に再結晶粒の結晶粒界から｛１１１｝＜ｕｖｗ＞を主方位とする再結晶が進行し、磁気特性の劣化が生じている。このことは、別の実験結果からも確認されており、したがって、熱処理の温度と時間を選択して再結晶率を40%以下としなけらばならない。なお、再結晶率とは、対象とする鋼板の熱処理後における再結晶粒の割合をいい、全視野面積に対する再結晶粒の占める面積の百分率によって定義する。
【００３７】
具体的な熱処理条件としては、次の態様によって行うことができる。
▲１▼ 600〜700℃における10分以上の保熱・自己焼鈍
この場合には、コイル巻き取り温度を600〜700℃とし、巻き取り後、適当な保温装置内において保温して、自己焼鈍させる。
▲２▼ 500〜700℃における10分以上の連続あるいは箱焼鈍
この場合は、低温巻き取りしたコイルあるいは、巻き取り後冷却したコイルを、コイル状態で箱焼鈍するか、あるいは巻き戻して連続焼鈍する。
▲３▼ 650〜850℃における3秒以上の連続焼鈍
この場合は、低温巻き取りしたコイルあるいは、巻き取り後冷却したコイルを巻き戻して連続焼鈍する。
【００３８】
しかしながら、700℃以上の温度で10分以上もしくは850℃以上の温度で3秒以上の熱処理を施す場合は再結晶が急激に進行し、好ましくない方位の再結晶の粒が出現する頻度が高くなるので適切ではない。したがって、上記手段を採用しながら熱処理の温度と時間の上限を規制して、再結晶率を40%以下とすることが肝要である。
【００３９】
熱延鋼板は、上記の所要の熱処理を経た後、冷間圧延によって最終板厚とされる。このとき、冷間圧延の圧下率を75〜98%とする。冷間圧延を75%以上とすることにより、より好ましい集合組織の抑制が可能となるからである。しかし、98%以上とすることは、工業的に無理が多いので75〜98%とする。
【００４０】
以上により、本発明の基本的な構成について説明したが、以下、本発明の本質ではないが、本発明を実施するため一般的条件について説明する。
【００４１】
まず、電磁鋼板は、Sn、Sb以外に下記の成分を含有する。
Ｃ：0.010%以下
Ｃは良好な磁気特性を得るためには有害な元素であり、含有量を0.010%（重量%、以下同じ）とする。
【００４２】
Si：0.1〜7.0%
Siは電気抵抗を高め、鉄損を低減するのに有効な元素であり、0.1重量％以上を含有させる。但し、7.0重量％を超えると加工が困難となるので、0.1〜7.0%とする。
【００４３】
Mn：0.03〜3.5%
Mnも電気抵抗を高め鉄損を低減する作用を有するので、0.03%以上を含有させる。しかし、3.5%を超えた場合、高温の仕上げ焼鈍の際に変態が起こり鉄損が劣化するので、0.03〜3.5%とする。
【００４４】
Al：0.10%以上あるいは0.001%以下
Alは電気抵抗を高め、鉄損を低減する作用があるので有効である。その作用を得るためには、0.10%以上を含有させることが好ましい。但し、2.0重量％を超えてる場合、鋼板の酸化・窒化が進行し鉄損の劣化を招くので含有量を0.10〜2.0重量％の範囲とするのが好ましい。一方、Alの含有量が0.10%未満の場合にはAlNを形成し、粒成長性を阻害して鉄損が劣化するので、Alを無添加とする場合には0.001%以下に制限する必要がある。
【００４５】
以上の元素の他に、P、Cu、Ni、Crを含有させることも、電気抵抗を高め鉄損を低減する作用があるので有効である。そのため、Pを0.01〜0.30%、Cuを0.01〜1.0%、Niを0.01〜0.5%、Crを0.01〜1.0%を含有させることができる。
なお、Sn、Sbの含有及び不純物元素の制限についてはすでに説明したとおりである。
【００４６】
上記の組成を有する鋼は、常法により連続鋳造によりスラブとされ、スラブ加熱ののち、熱間圧延により熱延コイルとされ、さらに冷間圧延される。その際、省エネルギーのため、スラブ加熱を行わず連続鋳造後、直接熱間圧延を行う手段、あるいは、スラブの温度保持を行う手段を採用することも可能である。また、冷延に際し、素材のSiなど電気抵抗増加成分の含有量が高い場合には100〜400℃の温間圧延を行うことも可能である。なお、本発明の特徴である熱間圧延、および冷間圧延の条件については、すでに詳細に説明した。
【００４７】
冷間圧延により最終板厚となった鋼板は、高温での仕上げ焼鈍を施されて結晶粒の粒成長を行い製品とする。この場合、いわゆるセミプロセスを採用することを妨げず、さらに、鋼板の表面に必要に応じて、無機、有機あるいは半有機の絶縁コーティングを施すことも可能である。また、溶接性の改善などの目的で鋼板表面の粗度を増すことも可能である。
【００４８】
【実施例１】
表４に示す鋼記号Ｄの組成を有する溶鋼を連続鋳造し、厚さ220mmのスラブを18本作製し、1220℃の温度で3時間保持した後、厚さ40mmに粗圧延した。さらに、７パスのタンデム仕上げ圧延機によって、40mm→30mm→18mm→10mm→6.4mm→4.8mm→3.2mm→2.2mmのパススケジュール（後段４パス累積圧下率72％）によって厚さ2.2mmのコイルに熱間圧延した。熱間圧延終了温度は810〜830℃であり、熱間圧延終了後、ジェット水噴流をかけて速度40〜55℃/sで急冷し、温度580〜600℃で巻取った。
【００４９】
【表４】

【００５０】
これらのコイルには酸洗後、520〜700℃の温度で、30分〜10時間の熱延板焼鈍を施した後、タンデム圧延機によって厚さ0.35mmに圧延し（冷間圧下率：92.5%）、脱脂処理を行い1050℃において40秒保持する仕上げ焼鈍を施し、重クロム酸マグネシウムと有機樹脂を主剤とする半有機コートを塗布・焼付け製品とした。
【００５１】
各製品から試験片を切り出し、標準測定法によるエプスタイン磁気測定と、４方向測定法による磁気測定を行い、W_15/50の鉄損、B₅₀の磁束密度、1.0T、50Hzでの透磁率を得た。また、鉄損の異方性定数、透磁率の異方性定数、およびB₅₀/Bsの値を求めた。さらに、これら製品から固定子の外径220mm、回転子径120mm、胴長60mmの８極200Hz、60VのＤＣブラシレスモータを作製し、この効率測定を行った。なお、熱延板焼鈍後、鋼板の再結晶率を測定した。
【００５２】
上記測定結果は、モータ効率と熱延板焼鈍後の結晶組織の再結晶率との関係としてを図１に示す。また、上記製品の鉄損W_15/50の異方性定数、1.5T、50Hzでの透磁率の異方性定数、およびB₅₀/Bsの値とモータ効率との関係を図２に示す。
【００５３】
図１に示すように、500℃以上の温度での熱延板焼鈍において再結晶率を40％以下とした本発明の方法によって、優れたモータ効率が得られており、また、優れたモータ効率を得るためには、鉄損W_15/50の異方性定数が1.05以下、かつ1.0T、50Hzでの透磁率の異方性定数が1.07以下、かつB₅₀/Bsの値が0.80以上であることが必要であることが実証されている。
【００５４】
【実施例２】
表５に示す鋼記号Ｅ、ＦおよびＧの組成を有する溶鋼を連続鋳造し、各７本の厚さ220mmのスラブとし、1000℃以上の温度に維持して直接熱間圧延を行い厚さ2.0mmのコイルに熱間圧延した。熱間圧延の終了温度はいずれも780〜810℃の間であり、終了後直ちにジェット水を噴射し40℃/sの速度で急冷し、500℃で巻取った。得られたコイルには酸洗後、所要の熱処理を施した。同一鋼記号から得られた各７本のスラブの圧延スケジュールおよび焼鈍条件はそれぞれ表６に示すとおりである。
【００５５】
【表５】

【００５６】
【表６】

【００５７】
上記により、得られた熱延板に対し、冷間圧延を施して0.35mmの最終板厚に圧延した。冷間圧下率は、82.5%であった。得られた冷延鋼板に露点−20℃、75%Ｈ₂+25%Ｎ₂雰囲気中で1000℃、１分の焼鈍を施し、リン酸アルミニウムを主剤とする無機コートを塗布して製品とした。
【００５８】
得られた製品から、30 x 280mmの試料を採取して磁気測定を行った。この試験片により、標準測定法と、４方向測定法による磁気測定を行い、鉄損値（W_15/50）、磁束密度（B₅₀）、1.0T、50Hzでの透磁率（G/θ）を求めた。また、鉄損の異方性定数、透磁率の異方性定数、およびB₅₀/Bsの値を求めた。さらに、これら製品から固定子の外径150mm、回転子径60mm、胴長80mmの単相4極300HzのＤＣブラシレスモータを作製し、この効率測定を行った。なお、熱延板焼鈍後、鋼板の再結晶率を測定した。試験結果は表７にまとめて示す。
【００５９】
【表７】

【００６０】
表７から明らかなように、鋼Eのうち処理１を受けたもの（E-1と略記する。以下、同様）、E-6、F-4、F-6、G-4、G-6の各製品においては、標準測定法では磁束密度と鉄損値が優れているが、モータ効率は、記号E-2、E-5の製品が優れている。さらに、標準測定法と４方向測定法から求めた材料の磁気特性評価は、E-2およびE-5において、鉄損の異方性定数がそれぞれ1.003、1.014、透磁率の異方性定数がそれぞれ1.032、1.038、またB₅₀/Bsの値が085、0.84と極めて優れた値を示した。
【００６１】
【実施例３】
表８に示す鋼記号H〜OおよびＱ、Ｒの組成を有するスラブを電磁攪拌を印加しつつ鋳込み、厚さ250mmのスラブとした。得られたスラブを1200℃に加熱した後、粗圧延し、厚さ35mmのシートバーとし、さらに６パスのタンデム圧延機によって熱間仕上げ圧延し、2.4mmの熱延コイルとした。このときのパススケジュールは35mm→27mm→18mm→10.2mm→6.8mm→4.0mm→2.4mmのパススケジュール（後段４パス累積圧下率：86.6％）とし、熱間圧延終了温度は、鋼記号Ｈのコイルは850℃、鋼記号Ｉ〜Ｋのコイルは830℃、鋼記号ＬとＭのコイルは790℃、鋼記号Ｎ、Ｏ、ＱおよびＲのコイルは760℃とした。また、熱間圧延終了後直ちにジェット水を噴射して50〜65℃/sの速度で急冷し、550℃の温度で巻取った。
【００６２】
【表８】

【００６３】
得られたコイルは２分割し、一方は本発明による焼鈍を施し、他方には、比較例として、本発明に係る条件から外れた焼鈍を施した。本発明による焼鈍は、鋼Hは550℃で6時間、鋼I〜Kは550℃で6時間、鋼LおよびMは550℃で１時間、鋼N、O、QおよびRは530℃で3時間のコイル状態での箱焼鈍であった。一方、比較例の焼鈍は、酸洗後の連続焼鈍であって、鋼Hは950℃で2分、鋼I〜Kは920℃で2分、鋼L〜OおよびQならびにRは860℃で5分間の条件であった。
【００６４】
焼鈍されたコイルはタンデム圧延機によって0.50mmの厚みに冷間圧延し（冷間圧下率：79.5%）、さらに脱脂処理を行い鋼Ｉ〜Ｋの鋼板は1050℃で１分、鋼ＬとＭの鋼板は1000℃で１分、鋼ＮとＯの鋼板は830℃で１分、鋼Ｑの鋼板は800℃で２分、鋼Ｒの鋼板は780℃で２分の仕上げ焼鈍を施し、有機、無機混合コートを塗布して製品とした。
【００６５】
得られた製品から、30 x 280mmの試料を採取して磁気測定を行った。測定は標準測定法のエプスタイン試験ならびに、４方向測定試験によった。さらに、これら製品から固定子の外径100mm、回転子径40mm、モータ胴長30mmの単相、４極100HzのＣＤブラシレスモータを作製し、これらのモータの効率測定を行った。なお、熱延板焼鈍後、鋼板の再結晶率を測定した。
【００６６】
測定結果をを表９にまとめて示す。表９に示されるように、本発明にしたがって製造された製品は、異方性が低く、比較材に比べ極めて良好なモータ効率が得られている。
【００６７】
【表９】

【００６８】
【実施例４】
表１０に示す鋼記号ＰおよびＳの組成を有する溶鋼を電解攪拌を印加しつつ連続鋳造機で厚さ50mmの薄スラブを各２本ずつ鋳込んだ。このスラブが鋳込み後、冷却途中でスラブ中心温度が1220℃に到達したときに、７スタンドのタンデム圧延機によって次の２つのパススケジュールにより直後仕上げ圧延を行い熱延コイルとした。
▲１▼ 50mm→38mm→28mm→20mm→12.5mm→7.2mm→4.2mm→2.7mm
（後段４パス累積圧下率：86.5％）
▲２▼50mm→34mm→25mm→18mm→11.8mm→5.4mm→3.0mm→1.8mm
（後段４パス累積圧下率：90.0％）
【００６９】
【表１０】

【００７０】
熱間圧延終了温度は750℃とし、熱間圧延終了後、22〜25℃/sの速度で冷却し、620℃で巻取り、コイル保護カバーを設けて、620〜640℃の温度で１時間滞留する熱処理を施した。
【００７１】
得られた熱延コイルは酸洗後、タンデム圧延機で厚さ0.50mmに圧延した。この場合、冷延圧下率は▲１▼の場合、81.5%であり発明例に該当し、▲２▼の場合、72.2%であって比較例に該当する。冷延後、脱脂処理を行った後、鋼記号Ｐの鋼板は820℃で30秒、鋼記号Ｓの鋼板は780℃で１分の仕上げ焼鈍を施した上、有機、無機混合コートを塗布して製品とした。
【００７２】
得られた製品から、30 x 280mmの試料を採取して磁気測定を行った。測定は標準測定法、ならびに、４方向測定法によった。さらに、これら製品から固定子の外径150mm、回転子径80mm、胴長70mmの３相、６極120Hzの誘導モータを作製し、これらのモータの効率測定を行った。結果を表１１にまとめて示す。表１１に示されるように、本発明例の製品は、比較材に比べてB₅₀/Bsの値が大きく鉄損および透磁率の異方性の低くモータ効率が良好である。
【００７３】
【表１１】

【００７４】
【発明の効果】
本発明は上記のように構成したから、従来に比べモータなど回転機に使用する無方向性電磁鋼板の実機特性をきわめて優れたものとすることができ、また、その製造を工業的に行うことが可能になり、それにより多大の省エネルギー効果が得られる。
【図面の簡単な説明】
【図１】モータ効率と熱延板焼鈍後の結晶組織の再結晶率との関係図である。
【図２】モータ効率と鉄損や透磁率の異方性定数およびB₅₀/Bsの値との関係図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-oriented electrical steel sheet used for an iron core of an electric motor or a generator, and more particularly to a non-oriented electrical steel sheet excellent in actual machine characteristics of a rotating machine and a manufacturing method thereof.
[0002]
[Prior art]
Non-oriented electrical steel sheet is a material used for iron cores of generators, electric motors, small transformers, etc. In order to reduce energy saving, it is necessary to reduce energy loss lost in motors and generators. In addition, electromagnetic characteristics such as iron loss are improved. Conventionally, the iron loss of a non-oriented electrical steel sheet is generally the iron loss when magnetized to 1.5T at a frequency of 50 Hz (W _15/50 (W / kg)) and magnetic flux density when magnetized with a magnetizing force of 5000 A / m (B ₅₀ (T)) is highly evaluated. The measurement method is based on the standard Epstein test method in which half of the sample is magnetized in the rolling direction and the remaining half is magnetized in the direction perpendicular to the rolling direction.
[0003]
The methods for reducing the iron loss of non-oriented electrical steel sheets are as follows: (1) Increasing the electrical resistance of the steel sheet by containing Si, Al or Mn, (2) Impurities such as S, O and N in the steel sheet A method of reducing the crystal grain growth property and increasing the crystal grain size of the product, and (3) a method of improving the crystal texture of the product to a preferable one. However, the first method is difficult to step up from the current situation because the rollability of the steel sheet and the workability at the time of product processing deteriorate, and the second impurity is currently S 20 ppm or less, O However, the effect of improving the magnetic properties is not as great as the increase in cost even if it is further reduced.
[0004]
The third method is a method of reducing the texture of the (111) orientation, which is an unfavorable crystal orientation in terms of magnetic properties. As a typical example, the crystal grain size before cold rolling is coarsened, and the old crystal grains There is a method of suppressing the recrystallization of (111) grains generated from the boundaries and increasing the density of (110) grains generated from the deformation bands in the old crystal grains. As a development of this method, as disclosed in Japanese Patent Laid-Open No. 55-97426 or Japanese Patent No. 2501219, hot-rolled sheet annealing is performed for a short time at a high temperature, There are a method of coarsening the crystal grain size and a method of annealing a hot-rolled sheet at 800 to 950 ° C. for a long time. Also, as disclosed in Japanese Patent Publication Nos. 56-54370 and 58-30926, hot rolled sheets containing Sb and Sn in steel are annealed at 700 to 1000 ° C. There is a method of further promoting the above-described effect by coarsening the grain size and segregating Sb and Sn at the grain boundaries.
[0005]
[Problems to be solved by the invention]
However, both of these methods reduce the {111} <uvw> series texture of the product and increase the grains having the (110) [001] orientation. Therefore, in order to evaluate the electromagnetic characteristics of the non-oriented electrical steel sheet, a measurement test (hereinafter simply referred to as a conventional method) in which half of the sample is magnetized in the rolling direction and the remaining half is magnetized in the direction perpendicular to the rolling direction. In the “standard measurement method”), even if good results were obtained, the actual machine characteristics of a rotating machine such as a generator and an electric motor were not necessarily good. This is because the conventional standard measurement method is suitable for applications in which characteristics in only two directions are important, such as the E1 core, but applications in which characteristics in all directions are required such as rotating machines. It was because it was not appropriate.
[0006]
In view of the above circumstances, in order to obtain excellent machine characteristics when the non-oriented electrical steel sheet is used for an iron core of a rotating machine such as a generator or an electric motor, It was made for the purpose of establishing evaluation standards for non-oriented electrical steel sheets used for applications, and further proposing products that satisfy the evaluation standards and manufacturing methods thereof.
[0007]
[Means for Solving the Problems]
The present inventor has intensively studied to solve the above-mentioned problems, and for the actual machine characteristics of the rotating machine, in addition to the conventional standard measurement method for measuring the characteristic value in the direction perpendicular to the rolling direction and the rolling direction, in the rolling direction. On the other hand, the anisotropy characteristic value including the measured value in the direction of ± 45 ° is important, and the magnetic flux density B with respect to the saturation magnetic flux density Bs ₅₀ In order to establish the evaluation criteria and to achieve the evaluation criteria, knowing that the ratio of steel is important, the hot-rolled sheet annealing shall be different from the conventional method to suppress recrystallization and promote recovery. The present invention has been completed by newly discovering the necessity.
[0008]
In the present invention, first, the anisotropy constant of permeability at 1.0 T and 50 Hz is 1.07 or less, the anisotropy constant of iron loss at 1.5 T and 50 Hz is 1.05 or less, and B measured by a four-direction measurement method. ₅₀ Value of B ₅₀ By satisfying /Bs≧0.80, the actual machine characteristics of the non-oriented electrical steel sheet rotating machine will be excellent. Here, the four-direction measurement method is an Epstein test or the like performed on a total of 500 g of test pieces of equal amounts cut from a rolling direction, a direction perpendicular to the rolling direction, and ± 45 ° to the rolling direction. Say.
[0009]
In the present invention, the preferred composition of the non-oriented electrical steel sheet is a total of one or two of C: 0.010% or less, Si: 0.1-7.0%, Mn: 0.03-3.5%, Sb, Sn as a weight ratio. Amounts: 0.003 to 0.20%, impurity elements S: 0.0050% or less, N: 0.0040% or less, O: 0.0030% or less, Ti: 0.0030% or less, Zr: 0.0030% or less, V: 0.0050% or less, B: It is limited to 0.0010% or less, Nb: 0.0050% or less, and the balance is substantially made of Fe.
[0010]
In addition to the above composition, Al: 0.10 to 2.0%, P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Cr: 0.01 to 1.0% Or Al: 0.001% or less and P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Cr: 0.01 to 1.0% I will do it.
[0011]
Moreover, as a manufacturing method of the non-oriented electrical steel sheet, a steel slab containing C: 0.010% or less, Si: 0.1-7.0%, Mn: 0.03-3.5% by weight ratio is hot-rolled by hot rolling. In the manufacturing process of the non-oriented electrical steel sheet consisting of a series of steps to make the final sheet thickness by one cold rolling after the hot-rolled sheet annealing and further finish annealing, the composition of the steel slab is Sb, Sn In a total amount of 0.003 to 0.20%, and the impurity elements are: S: 0.0050% or less, N: 0.0040% or less, O: 0.0030% or less, Ti: 0.0030% or less, Zr: 0.0030% or less, V: 0.0050% or less, B: 0.0010% or less, Nb: 0.0050% or less, and the hot rolling has a cumulative rolling reduction of 65 to 95% in the subsequent four passes of the finish rolling, and the coil winding after the hot rolling The heating temperature is 700 ° C. or lower, and the hot-rolled sheet annealing is to recover the rolling strain to a recrystallization rate of 40% or lower, and In rolling, the rolling reduction is 75 to 98%.
[0012]
Further, in the above production method, the slab further contains one or more of Al: 0.10 to 2.0%, P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Cr: 0.01 to 1.0%. Or Al: 0.001% or less, and P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Cr: 0.01 to 1.0% are preferably contained. And
[0013]
In addition, the above-mentioned hot-rolled sheet annealing is a heat retention / self-annealing at 600 to 700 ° C. for 10 minutes or more, a continuous or box annealing at 500 to 700 ° C. for 10 minutes or more, or a continuous annealing at 650 to 850 ° C. for 3 seconds or more. It shall be either.
[0014]
In addition, the present invention makes the cold rolling a warm rolling at 100 to 450 ° C. and makes the effects of the above inventions more remarkable.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail including experimental results leading to the invention.
Molten steel having each composition of A, B and C shown in Table 1 was cast by continuous casting to form seven slabs each having a thickness of 230 mm. Each slab was heated at a temperature of 1170 ° C. for 3 hours, made into a sheet bar by rough rolling, and then finish-rolled to obtain a hot-rolled sheet having a thickness of 2.2 mm. The hot rolling end temperature was between 820 and 840 ° C. Immediately after the end of hot rolling, jet water was jetted to quench and roll up at 500 ° C. The obtained hot-rolled sheet was annealed and then cold-rolled to a final sheet thickness of 0.5 mm. Further, the dew point was −20 ° C. and 75% H. ₂ + 25% N ₂ The product was annealed at 1000 ° C. for 1 minute in a mixed atmosphere, and an organic / inorganic mixed coat was applied to obtain a product. The hot rolling schedule and annealing conditions at that time were as shown in treatment symbols 1 to 7 shown in Table 2.
[0016]
[Table 1]

[0017]
[Table 2]

[0018]
The structure and characteristic values of the process of the above experimental process and the obtained product were measured as follows.
(1) Recrystallization rate of steel sheet cross section before and after hot-rolled sheet annealing (percentage of area occupied by recrystallized grains with respect to the total visual field area)
(2) Epstein test by standard measurement method and various tests by four-direction measurement method for products
(3) Motor efficiency measurement (Three-phase 6-pole 120Hz, 120v, 400w induction motor with stator outer diameter 130mm, rotor diameter 50mm, barrel length 70mm)
The measurement results are summarized in Table 3.
[0019]
[Table 3]

[0020]
As shown in Table 3, A-4 (when treatment 4 was applied to steel A, the same applies below), A-5, B-4, B-5, B-6 and C-4, C-5, C -6 has excellent magnetic flux density and iron loss in the standard measurement method, but motor efficiency is excellent only in the case of A-2. In other words, the motor efficiency does not necessarily reflect the magnetic characteristics of the product. As a result of investigating the reason, the product of A-2 is inferior in the measurement of the magnetic property by the two-direction measurement test, but the magnetic property of the four-direction measurement test is the iron loss W _15/50 Was 2.325W / kg (as opposed to A-6 2.83W / kg), which was found to be a very good value. In the case of A-2, the permeability value of 1.5T, 50Hz in the four-direction measurement method was as high as 12310 G / θ, whereas in the case of A-6, there was only 11590 G / θ, which is the motor efficiency. Is the cause of lowering.
[0021]
Such a difference in measured value between the standard measurement method and the four-direction measurement method is mainly caused by the texture of the crystal structure of the steel sheet. That is, in the measurement by the standard measurement method, a material having an excellent texture only in two directions of the rolling direction and the direction perpendicular to the rolling direction is particularly advantageously evaluated, whereas in the four-direction measurement method, the anisotropy in the steel sheet surface is evaluated. Less texture is evaluated more advantageously, making it suitable for characterization of rotating machines. Incidentally, the main texture of the crystal structure of the product A-2 was {100} <uvw>.
[0022]
As described above, the difference between the result obtained by the standard measurement method and the result obtained by the four-direction measurement method serves as an index representing the anisotropy of the material. Therefore, in the present invention, the anisotropy constant is defined by the ratio between the two. That is, as an anisotropy constant of iron loss, W by four-direction measurement method _15/50 The value of W by standard measurement method _15/50 In addition, the permeability anisotropy constant is taken as 1.0T, 50Hz permeability value by the standard measurement method, and 1.0T, 50Hz permeability value by the four-direction measurement method. Use the divided value. The closer the anisotropy constant is to 1, the weaker the anisotropy, which is advantageous for motor characteristics.
[0023]
In this case, as described above, the measurement conditions of the four-direction measurement method for materials for rotating machines such as motors are 1.5T and 50Hz for iron loss, and 1.0T and 50Hz for permeability. Although generally accepted, it is obvious that lower magnetic flux side or higher magnetic flux density side or higher frequency side measurement conditions can be adopted for a designed magnetic field or a high frequency designed motor. .
[0024]
Furthermore, the present inventor ₅₀ There is a good correlation between the value of / Bs and motor efficiency. ₅₀ It was found that / Bs should be 0.8 or more. Here, Bs is the saturation magnetic flux density of the electrical steel sheet, and B ₅₀ Denotes the maximum magnetic flux density at 50 Hz with a maximum magnetic field of 5000 A / m. Even if the Bs value is simply high, when the anisotropy is large, the improvement of the actual machine characteristics such as the motor rotation is not remarkable. B ₅₀ Because the value of / Bs cannot exceed 1, B ₅₀ Materials with / Bs close to 1 are suitable for rotating machines.
[0025]
That is, the tooth portion of the motor is a portion where the volume is particularly small in the motor, and the magnetic flux concentrates. Therefore, unless the magnetic flux density of the portion is high, the actual machine characteristics of the motor are not improved. In addition, the teeth of the motor are distributed in all directions of 360 ° with respect to the rolling direction of the magnetic steel sheet, and the standard measurement method that evaluates only the rolling direction and the direction perpendicular to the rolling cannot cope with such conditions. B by 4-way measurement method ₅₀ B calculated using the value of ₅₀ The value of / Bs is more appropriate for evaluating the material properties of the tooth part and replaces the conventional standard.
[0026]
As described above, the present invention reexamines the characteristics of the non-oriented electrical steel sheet from the viewpoint of the actual machine characteristics of the rotating machine, establishes a new evaluation standard, and provides a non-oriented electrical steel sheet for a rotating machine having unprecedented characteristics. It is what we propose. However, the present invention has a conventional iron loss value W which is an evaluation standard. _15/50 And magnetic flux density B ₅₀ The value of is not negated, and it is natural that these values are more effective if they are excellent.
[0027]
Hereinafter, means for producing the non-oriented electrical steel sheet having the characteristics of the present invention will be described.
[0028]
First, it is necessary to contain Sn and / or Sb as the composition of the starting slab. When A-2 and B-2 shown in Table 3 are compared, the crystal structure of A-2 is mainly {100} <although they are subjected to the same hot rolling, heat treatment and cold rolling processes. uvw> is a texture and shows excellent rotating machine characteristics, while the results of the B-2 four-way measurement method are inferior in iron loss value, magnetic flux density, and magnetic permeability. In addition, {111} <uvw> is the main orientation and the anisotropy is small, but it is not preferable in terms of magnetic properties.
[0029]
The difference between A-2 and B-2 is whether the steel contains grain boundary segregation elements such as Sn and Sb. When investigating the effect on Sn and Sb in more detail, when these elements contained 0.003% to 0.20% in total amount, these elements segregated at the grain boundaries before cold rolling and annealed after cold rolling. It was found that recrystallization of grains with {111} <uvw> orientation was suppressed at the stage, and recrystallization / growth of grains having {100} <uvw> as the crystal main orientation was promoted. Therefore, Sn or Sb is contained alone or in combination to contain 0.003% or more in total. However, if it exceeds 0.20%, the workability deteriorates and is not practical, so it is kept at 0.20% or less.
[0030]
Next, it is necessary to take measures to sufficiently grow the crystal grains and develop the {100} <uvw> texture. One of the conditions is addition of an appropriate amount of the aforementioned Sn or Sb. Incidentally, the crystal grain size of A-2 was as large as 120 μm, whereas B-2 was 90 μm.
[0031]
But that is not enough. It is necessary to sufficiently reduce the content of impurity elements. This is because steel C contains Sb as in steel A when steel C is subjected to the same treatment 2 as steel A (see Table 2). In spite of showing a good value in magnetic susceptibility, in the case of C-2, the crystal grain size is as small as 55 μm, which is apparent from the fact that the iron loss value increases and the motor efficiency is deteriorated. In the case of C-2, although the texture is {100} <uvw>, its strength is weak, so B by the four-direction measurement method is used. ₅₀ / Bs was also inferior.
[0032]
Impurities include S: 0.0050% or less, N: 0.0040% or less, O: 0.0030% or less, Ti: 0.0030% or less, Zr: 0.0030% or less, V: 0.0050% or less, B: 0.0010% or less, Nb : Must be limited to 0.0050% or less. By reducing this impurity, the {100} <uvw> texture that has been considered to have a very weak driving force for recrystallization / growth and a small crystal grain size and easy to refine has been developed. Can do.
[0033]
In order to obtain a non-oriented electrical steel sheet excellent in actual machine characteristics of the rotating machine according to the present invention, it is necessary to introduce sufficient strain into the hot-rolled sheet by hot finish rolling. By the way, for Steel A, when only the hot rolling schedule is changed, the treatment 2 (A-2) is better for the rotating machine than the treatment 1 (A-1). It has magnetic properties. In the present invention, the degree of introduction of strain at the time of hot finish rolling is evaluated by the cumulative rolling reduction ratio of the subsequent four passes of finish rolling, and the value is set to 65% or more. Thereby, a high-density process distortion can be contained in a hot-rolled coil. However, if it exceeds 95%, finish rolling itself becomes difficult, so the content is made 95% or less. In addition, in order to increase the rolling reduction in the latter stage of finish rolling, it is possible to take means such as omitting rough rolling if necessary.
[0034]
Moreover, when annealing a hot-rolled sheet into which strain has been introduced as described above, it is necessary to employ conditions for suppressing recrystallization while removing the strain from the hot-rolled sheet. Thereby, the structure of the internal subgrains is improved in the annealing process of the hot-rolled sheet, particularly in the recovery process. That is, it becomes possible to suppress recrystallization of the crystal grains having {111} <uvw> from the old crystal grain boundary and the deformation zone in the old crystal grain, and {100} <uvw> from the old crystal grain. Recrystallization of grains having an orientation is promoted.
[0035]
Specifically, first, the hot rolling coil winding temperature after finish rolling is set to 700 ° C. or lower. When the coil winding temperature is set to a temperature exceeding 700 ° C., a part of the steel sheet starts to recrystallize, thereby increasing the texture of {111} <uvw> orientation and improving the efficiency of the actual rotating machine. It is because it falls. Therefore, after completion of hot rolling, it is preferable to take measures such as jetting jet water on the exit side of the finish rolling mill so that the winding temperature is 700 ° C. or lower.
[0036]
Next, heat treatment is performed on the hot-rolled sheet so that the recrystallization rate is 40% or less while recovering the rolling strain. This is because when the recrystallization rate exceeds 40%, the recrystallized grains in the {111} <uvw> orientation increase from the grain boundaries of the recrystallized grains, and the texture and magnetic properties of the product deteriorate. By the way, as can be seen by comparing A-2 with A-4, A-5 or A-6, in the case of A-4, A-5, A-6, recrystallization of the steel plate before cold rolling Therefore, after cold rolling and finish annealing, recrystallization with {111} <uvw> as the main orientation proceeds from the grain boundary of the recrystallized grains, resulting in deterioration of magnetic properties. This has been confirmed from other experimental results, and therefore, the recrystallization rate must be 40% or less by selecting the temperature and time of the heat treatment. The recrystallization rate refers to the ratio of recrystallized grains after heat treatment of the target steel sheet, and is defined by the percentage of the area occupied by the recrystallized grains with respect to the entire visual field area.
[0037]
Specific heat treatment conditions can be carried out in the following manner.
(1) Heat retention and self-annealing at 600-700 ° C for 10 minutes or more
In this case, the coil winding temperature is set to 600 to 700 ° C., and after coiling, the coil is kept in a suitable heat retaining device and self-annealed.
(2) Continuous or box annealing for 10 minutes or more at 500-700 ° C
In this case, the coil that has been wound at low temperature or the coil that has been cooled after winding is subjected to box annealing in the coiled state, or unwinding and continuous annealing.
(3) Continuous annealing for 3 seconds or more at 650-850 ° C
In this case, the coil wound at low temperature or the coil cooled after winding is unwound and continuously annealed.
[0038]
However, when heat treatment is performed at a temperature of 700 ° C. or more for 10 minutes or more or at a temperature of 850 ° C. or more for 3 seconds or more, recrystallization proceeds rapidly, and the frequency of appearance of unfavorable orientation recrystallized grains increases. So it is not appropriate. Therefore, it is important to regulate the upper limit of the temperature and time of heat treatment while adopting the above means so that the recrystallization rate is 40% or less.
[0039]
The hot-rolled steel sheet is subjected to the above-described required heat treatment, and then made into a final thickness by cold rolling. At this time, the rolling reduction of cold rolling is set to 75 to 98%. This is because by making the cold rolling 75% or more, it is possible to more preferably suppress the texture. However, since it is unreasonable industrially to set it to 98% or more, it is set to 75 to 98%.
[0040]
Although the basic configuration of the present invention has been described above, the general conditions for implementing the present invention will be described below, although not the essence of the present invention.
[0041]
First, the electromagnetic steel sheet contains the following components in addition to Sn and Sb.
C: 0.010% or less
C is a harmful element for obtaining good magnetic properties, and its content is set to 0.010% (% by weight, hereinafter the same).
[0042]
Si: 0.1-7.0%
Si is an element effective for increasing electric resistance and reducing iron loss, and contains 0.1% by weight or more. However, if it exceeds 7.0% by weight, it becomes difficult to process, so 0.1 to 7.0%.
[0043]
Mn: 0.03-3.5%
Mn also has an effect of increasing electric resistance and reducing iron loss, so 0.03% or more is contained. However, if it exceeds 3.5%, transformation occurs during high-temperature finish annealing and iron loss deteriorates, so 0.03 to 3.5% is set.
[0044]
Al: 0.10% or more or 0.001% or less
Al is effective because it increases electric resistance and reduces iron loss. In order to acquire the effect | action, it is preferable to contain 0.10% or more. However, if it exceeds 2.0% by weight, the oxidation and nitriding of the steel sheet proceeds and the iron loss is deteriorated, so the content is preferably in the range of 0.10 to 2.0% by weight. On the other hand, when the Al content is less than 0.10%, AlN is formed, which inhibits grain growth and deteriorates iron loss.Therefore, when Al is not added, it is necessary to limit it to 0.001% or less. is there.
[0045]
In addition to the above elements, inclusion of P, Cu, Ni, and Cr is also effective because it has an effect of increasing electrical resistance and reducing iron loss. Therefore, 0.01 to 0.30% of P, 0.01 to 1.0% of Cu, 0.01 to 0.5% of Ni, and 0.01 to 1.0% of Cr can be contained.
Note that the contents of Sn and Sb and the limitation of impurity elements are as described above.
[0046]
The steel having the above composition is made into a slab by continuous casting by a conventional method, and after slab heating, it is made into a hot-rolled coil by hot rolling, and further cold-rolled. At this time, in order to save energy, it is possible to adopt means for directly performing hot rolling after continuous casting without performing slab heating or means for maintaining the temperature of the slab. Further, in the case of cold rolling, when the content of the electrical resistance increasing component such as Si is high, it is possible to perform warm rolling at 100 to 400 ° C. The conditions for hot rolling and cold rolling, which are the characteristics of the present invention, have already been described in detail.
[0047]
The steel sheet having the final thickness by cold rolling is subjected to finish annealing at a high temperature to grow crystal grains to obtain a product. In this case, it is possible to apply an inorganic, organic or semi-organic insulating coating on the surface of the steel sheet as required without obstructing the adoption of a so-called semi-process. It is also possible to increase the roughness of the steel sheet surface for the purpose of improving weldability.
[0048]
[Example 1]
Molten steel having the composition of steel symbol D shown in Table 4 was continuously cast, 18 slabs having a thickness of 220 mm were produced, held at a temperature of 1220 ° C. for 3 hours, and then roughly rolled to a thickness of 40 mm. Furthermore, using a 7-pass tandem finish rolling mill, a coil with a thickness of 2.2 mm according to a pass schedule of 40 mm-> 30 mm-> 18 mm-> 10 mm-> 6.4 mm-> 4.8 mm-> 3.2 mm-> 2.2 mm (the subsequent 4-pass cumulative rolling reduction rate is 72%). Hot rolled. The hot rolling end temperature was 810 to 830 ° C., and after the hot rolling was finished, a jet water jet was applied to quench at a speed of 40 to 55 ° C./s, and the product was wound at a temperature of 580 to 600 ° C.
[0049]
[Table 4]

[0050]
These coils were pickled, hot-rolled sheet annealed at a temperature of 520 to 700 ° C. for 30 minutes to 10 hours, and then rolled to a thickness of 0.35 mm by a tandem rolling mill (cold reduction ratio: 92.5 %), Degreased, and annealed at 1050 ° C. for 40 seconds. A semi-organic coating mainly composed of magnesium dichromate and organic resin was applied and baked.
[0051]
Cut out test pieces from each product, perform Epstein magnetic measurement by standard measurement method and magnetic measurement by four-direction measurement method, _15/50 Iron loss, B ₅₀ Magnetic flux density of 1.0T, magnetic permeability at 50Hz was obtained. Also, the iron loss anisotropy constant, the permeability anisotropy constant, and B ₅₀ The value of / Bs was obtained. Furthermore, an 8-pole 200 Hz, 60 V DC brushless motor having a stator outer diameter of 220 mm, a rotor diameter of 120 mm, and a barrel length of 60 mm was produced from these products, and this efficiency was measured. In addition, the recrystallization rate of the steel plate was measured after hot-rolled sheet annealing.
[0052]
The above measurement results are shown in FIG. 1 as the relationship between the motor efficiency and the recrystallization rate of the crystal structure after hot-rolled sheet annealing. In addition, iron loss W of the above products _15/50 Anisotropy constant, 1.5T, anisotropy constant of permeability at 50Hz, and B ₅₀ The relationship between the value of / Bs and the motor efficiency is shown in FIG.
[0053]
As shown in FIG. 1, excellent motor efficiency is obtained by the method of the present invention in which the recrystallization rate is 40% or less in hot-rolled sheet annealing at a temperature of 500 ° C. or higher, and excellent motor efficiency. To get iron loss W _15/50 Anisotropy constant of 1.05 or less and 1.0T, the anisotropy constant of permeability at 50 Hz is 1.07 or less, and B ₅₀ It has been demonstrated that the value of / Bs needs to be 0.80 or higher.
[0054]
[Example 2]
Molten steel having the composition of steel symbols E, F, and G shown in Table 5 is continuously cast into seven slabs each having a thickness of 220 mm, and is directly hot-rolled at a temperature of 1000 ° C. or more to obtain a thickness of 2.0 Hot rolled into mm coil. The end temperature of hot rolling was between 780 to 810 ° C., and immediately after the end, jet water was sprayed, rapidly cooled at a rate of 40 ° C./s, and wound at 500 ° C. The obtained coil was pickled and then subjected to the required heat treatment. Table 6 shows the rolling schedule and annealing conditions of each of the seven slabs obtained from the same steel symbol.
[0055]
[Table 5]

[0056]
[Table 6]

[0057]
As described above, the obtained hot-rolled sheet was cold-rolled to a final sheet thickness of 0.35 mm. The cold reduction rate was 82.5%. The resulting cold-rolled steel sheet has a dew point of -20 ° C and 75% H ₂ + 25% N ₂ Annealing was performed at 1000 ° C. for 1 minute in an atmosphere, and an inorganic coat mainly composed of aluminum phosphate was applied to obtain a product.
[0058]
From the obtained product, a 30 x 280 mm sample was collected and subjected to magnetic measurement. With this test piece, magnetic measurement is performed by the standard measurement method and the four-direction measurement method, and the iron loss value (W _15/50 ), Magnetic flux density (B ₅₀ ), Magnetic permeability (G / θ) at 1.0 T, 50 Hz. Also, the iron loss anisotropy constant, the permeability anisotropy constant, and B ₅₀ The value of / Bs was obtained. Furthermore, a single-phase 4-pole 300 Hz DC brushless motor having a stator outer diameter of 150 mm, a rotor diameter of 60 mm, and a trunk length of 80 mm was produced from these products, and the efficiency was measured. In addition, the recrystallization rate of the steel plate was measured after hot-rolled sheet annealing. The test results are summarized in Table 7.
[0059]
[Table 7]

[0060]
As is apparent from Table 7, steel E that received treatment 1 (abbreviated as E-1, hereinafter the same), E-6, F-4, F-6, G-4, G-6 In these products, the magnetic flux density and iron loss value are excellent in the standard measurement method, but the motor efficiency is excellent in the products of symbols E-2 and E-5. Furthermore, the magnetic properties of the material obtained from the standard measurement method and the four-direction measurement method are as follows. In E-2 and E-5, the anisotropy constant of iron loss is 1.003 and 1.014, respectively, and the anisotropy constant of permeability is 1.032, 1.038 and B respectively ₅₀ The values of / Bs were 085 and 0.84, which were extremely excellent values.
[0061]
[Example 3]
Slabs having the compositions of steel symbols H to O and Q and R shown in Table 8 were cast while applying electromagnetic stirring to form slabs with a thickness of 250 mm. The obtained slab was heated to 1200 ° C. and then roughly rolled to form a sheet bar having a thickness of 35 mm, followed by hot finish rolling with a 6-pass tandem rolling mill to obtain a 2.4 mm hot rolled coil. The pass schedule at this time is 35 mm → 27 mm → 18 mm → 10.2 mm → 6.8 mm → 4.0 mm → 2.4 mm pass schedule (following 4 pass cumulative reduction ratio: 86.6%). The coils were 850 ° C, the steel symbols I to K were 830 ° C, the steel symbols L and M were 790 ° C, and the steel symbols N, O, Q, and R were 760 ° C. Further, immediately after the hot rolling was completed, jet water was sprayed, rapidly cooled at a speed of 50 to 65 ° C./s, and wound at a temperature of 550 ° C.
[0062]
[Table 8]

[0063]
The obtained coil was divided into two, one was annealed according to the present invention, and the other was annealed as a comparative example that deviated from the conditions according to the present invention. In the annealing according to the present invention, steel H is 550 ° C. for 6 hours, steels I to K are 550 ° C. for 6 hours, steels L and M are 550 ° C. for 1 hour, and steels N, O, Q, and R are 530 ° C. for 3 hours. It was box annealing in a coiled state for hours. On the other hand, the annealing of the comparative example is continuous annealing after pickling. Steel H is 950 ° C for 2 minutes, Steels I to K are 920 ° C for 2 minutes, Steels L to O, Q, and R are 860 ° C. The condition was 5 minutes.
[0064]
The annealed coil was cold-rolled to a thickness of 0.50 mm with a tandem rolling mill (cold reduction ratio: 79.5%), further degreased, and steels I to K at 1050 ° C for 1 minute, steels L and M Steel plate No. 1 is 1000 ° C for 1 minute, Steel N and O steel plate is 830 ° C for 1 minute, Steel Q steel plate is 800 ° C for 2 minutes, Steel R steel plate is 780 ° C for 2 minutes, and annealed for 2 minutes. Then, an inorganic mixed coat was applied to obtain a product.
[0065]
From the obtained product, a 30 x 280 mm sample was collected and subjected to magnetic measurement. The measurement was based on the Epstein test of the standard measurement method and the four-direction measurement test. Furthermore, from these products, single-phase, 4-pole 100 Hz CD brushless motors with a stator outer diameter of 100 mm, a rotor diameter of 40 mm, and a motor barrel length of 30 mm were manufactured, and the efficiency of these motors was measured. In addition, the recrystallization rate of the steel plate was measured after hot-rolled sheet annealing.
[0066]
The measurement results are summarized in Table 9. As shown in Table 9, the products manufactured according to the present invention have low anisotropy, and extremely good motor efficiency is obtained as compared with the comparative material.
[0067]
[Table 9]

[0068]
[Example 4]
Two thin slabs each having a thickness of 50 mm were cast into a molten steel having compositions of steel symbols P and S shown in Table 10 by a continuous casting machine while applying electrolytic stirring. When this slab was cast and when the slab center temperature reached 1220 ° C. during cooling, it was immediately finished and rolled into a hot-rolled coil by a 7-stand tandem rolling mill according to the following two pass schedules.
▲ 1 ▼ 50mm → 38mm → 28mm → 20mm → 12.5mm → 7.2mm → 4.2mm → 2.7mm
(Rolling 4-pass cumulative reduction ratio: 86.5%)
▲ 2 ▼ 50mm → 34mm → 25mm → 18mm → 11.8mm → 5.4mm → 3.0mm → 1.8mm
(Rolling 4-pass cumulative reduction ratio: 90.0%)
[0069]
[Table 10]

[0070]
The hot rolling end temperature is set to 750 ° C. After the hot rolling is finished, it is cooled at a speed of 22-25 ° C / s, wound at 620 ° C, provided with a coil protection cover, and at a temperature of 620-640 ° C for 1 hour. A staying heat treatment was applied.
[0071]
The obtained hot rolled coil was pickled and then rolled to a thickness of 0.50 mm with a tandem rolling mill. In this case, the cold rolling reduction ratio is 81.5% in the case of (1), which corresponds to the invention example, and in the case of (2), it is 72.2%, which corresponds to the comparative example. After cold rolling, after degreasing, steel plate with steel symbol P was subjected to a final annealing at 820 ° C for 30 seconds, and steel plate with steel symbol S at 780 ° C for 1 minute, and then an organic and inorganic mixed coat was applied. Product.
[0072]
From the obtained product, a 30 x 280 mm sample was taken and subjected to magnetic measurement. The measurement was based on a standard measurement method and a four-direction measurement method. In addition, three-phase, six-pole, 120-Hz induction motors with a stator outer diameter of 150 mm, rotor diameter of 80 mm, and barrel length of 70 mm were produced from these products, and the efficiency of these motors was measured. The results are summarized in Table 11. As shown in Table 11, the product of the present invention is B compared to the comparative material. ₅₀ The value of / Bs is large, the iron loss and permeability anisotropy are low, and the motor efficiency is good.
[0073]
[Table 11]

[0074]
【The invention's effect】
Since the present invention is configured as described above, the actual machine characteristics of the non-oriented electrical steel sheet used in the rotating machine such as a motor can be made extremely superior compared to the conventional one, and the production thereof can be performed industrially. This makes it possible to obtain a great energy saving effect.
[Brief description of the drawings]
FIG. 1 is a relationship diagram between motor efficiency and recrystallization rate of a crystal structure after hot-rolled sheet annealing.
[Fig. 2] Motor efficiency, iron loss, magnetic permeability anisotropy constant and B ₅₀ It is a relationship figure with the value of / Bs.

Claims (7)

The composition contains, by weight, C: 0.010% or less, Si: 0.1-7.0%, Mn: 0.03-3.5%, and the total amount of one or two of Sb and Sn: 0.003-0.20%, and impurities Element: S: 0.0050% or less, N: 0.0040% or less, 0: 0.0030% or less, Ti: 0.0030% or less, Zr: 0.0030% or less, V: 0.0050% or less, B: 0.0010% or less, Nb: 0.0050% or less It consists of the remaining Fe and unavoidable impurities, the anisotropy constant of permeability at 1.0T, 50Hz is 1.07 or less, the anisotropy constant of iron loss at 1.0T, 50Hz is 1.05 or less, and is measured in four directions non-oriented electrical steel sheet value of B ₅₀ by law and satisfies the B ₅₀ / B _s ≧ 0.80.
Here, the magnetic permeability anisotropy constant is the value obtained by dividing the value of the magnetic permeability of 1.0T by the standard measurement method at 50 Hz and the value of the magnetic permeability by 1.0T by the four-direction measurement method by 50 THz . The anisotropy constant is a value obtained by dividing the value of W _15/50 by the four-direction measurement method by the value of W _15/50 by the standard measurement method.   The composition further contains at least one of Al: 0.10 to 2.0%, P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Cr: 0.01 to 1.0%. The non-oriented electrical steel sheet according to claim 1, wherein   The composition further includes Al: 0.001% or less, and P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, and Cr: 0.01 to 1.0%. The non-oriented electrical steel sheet according to claim 1. Steel slab containing C: 0.010% or less, Si: 0.1-7.0%, Mn: 0.03-3.5% by weight ratio is made into hot-rolled sheet by hot rolling, and after hot-rolled sheet annealing, it is finally finished by cold rolling In the manufacturing method of non-oriented electrical steel sheet consisting of a series of steps to make plate thickness and further finish annealing,
The steel slab contains 0.003 to 0.20% of Sb and Sn in total amount, and the impurity elements are S: 0.0050% or less, N: 0.0040% or less, 0: 0.0030% or less, Ti: 0.0030% or less, Zr: 0.0030% or less, V: 0.0050% or less, B: 0.0010% or less, Nb: 0.0050% or less,
In the hot rolling, the cumulative rolling reduction of the final four passes after the finish rolling is 65 to 95%, and the coil winding temperature after the hot rolling is 700 ° C. or less,
The hot rolled sheet annealing is, 600 - 700 ° C. 10 minutes or more heat-keeping, self-annealing at 500 to 700 or more consecutive 10 min at ° C. or box annealing, or 650 to any of three seconds or more continuous annealing at 850 ° C. As a result, the recrystallization rate should be 40% or less.
The method for producing a non-oriented electrical steel sheet, wherein the cold rolling has a rolling reduction of 75 to 98%.   The slab further contains at least one of Al: 0.10 to 2.0%, P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0, 5%, and Cr: 0.01 to 1.0%. The method for producing a non-oriented electrical steel sheet according to claim 4, wherein the actual machine characteristics of the rotating machine according to claim 4 are excellent.   The slab further contains Al: 0.001% or less, and contains at least one of P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Cr: 0.01 to 1.0%. The manufacturing method of the non-oriented electrical steel sheet according to claim 4 characterized by the above-mentioned. The manufacturing method of the non-oriented electrical steel sheet according to any one of claims 4 to 6 , wherein the cold rolling is warm rolling at 100 to 450 ° C.

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