JP4331900B2 - Oriented electrical steel sheet and method and apparatus for manufacturing the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、変圧器等の静止誘導器に使用される方向性電磁鋼板おいて、鉄損を低減した鋼板、及びその製造方法並びに製造装置に関する。
【０００２】
【従来の技術】
方向性電磁鋼板は、主として変圧器に代表される静止誘導器に使用される。その満たすべき特性としては、▲１▼交流で励磁したときのエネルギー損失すなわち鉄損が小さいこと、▲２▼機器の使用励磁域での透磁率が高く容易に励磁できること、▲３▼騒音の原因となる磁歪が小さいこと等があげられる。特に▲１▼に関しては、変圧器が据え付けられてから廃棄されるまでの長期間にわたって連続的に励磁され、エネルギー損失を発生し続けることから、変圧器の価値を表わす指標であるＴ．Ｏ．Ｃ．(Total Owning Cost) を決定する主要なパラメータとなる。
【０００３】
この方向性電磁鋼板の鉄損を低減するために、今までに多くの開発がなされてきた。すなわち、▲１▼ゴス方位と呼ばれる（１１０）［００１］方位への集積を高めること、▲２▼電気抵抗を高めるＳｉ等固溶元素の含有量を高めること、▲３▼鋼板の板厚を薄くすること、▲４▼鋼板に面張力を与えるセラミック被膜や絶縁被膜を付与すること、▲５▼結晶粒の大きさを小さくすること等である。
しかし、これら冶金学的な手法による鉄損改善には限度があり、他の手法による鉄損低減が求められていた。
【０００４】
この課題に対して、A.Fiedler,W.Pepperhof は、方向性電磁鋼板の表面にカッター等で溝をつけ磁区構造を変えることによって鉄損を低減する手法を提案している（ＵＳＰ３，６４６，５７５号）。方向性電磁鋼板は一般的に、互いに反対方向の磁化成分を持つスラブ状の磁区が交互に並んだ磁区構造を持ち、これら磁区が外部磁場下で拡大／縮小することによって磁化が行われる。従って、方向性電磁鋼板が磁化されるときには、隣接する磁区の境界（磁壁）の部分のみで磁化変化が生じる。この磁化変化に伴って鋼板中には渦電流が流れ、前述した鉄損の原因の６０〜７０％をしめる（渦電流損）。渦電流損は渦電流の２乗に比例し、渦電流は磁壁の移動速度に比例する。磁区幅を狭くすると、渦電流の発生する部位は多くなるが、磁壁の移動速度は磁区幅に逆比例して小さくなるから、結果として渦電流損は磁区幅にほぼ比例して小さくなる。
【０００５】
この磁区細分化の手法を工業的に利用可能にするため、さらに様々な提案がなされた。例えば特公昭５８−５９６８号公報にあるように、鋼板面に直径０．２〜１０mmの小球を押しつけながら回転させ、表面にキズをつけずに歪みを導入する方法、特公昭５７−２２５２号公報にあるように、圧延方向とほぼ直角方向にレーザービームを照射し微少塑性歪を加える方法、特開昭６２−９６６１７号公報にあるような、圧延方向とほぼ直角方向にプラズマ炎を線状に放射する方法等がある。
これらは何れも鋼板に微少な塑性歪を導入し、磁歪の逆効果によって安定化された圧延方向と直角方向の磁化成分を持つ磁区を利用して、磁区を細分化する技術であり、巻鉄心を作製した際の歪取り焼鈍によってその効果が失われてしまうものであった。
【０００６】
さらにこれらの磁区細分化手法に対し、歪取り焼鈍によっても効果の失われない耐熱型の磁区細分化手法が検討され、例えば特公昭６３−４４８０４号公報にあるような、仕上げ焼鈍後の鋼板に歯車型ロールで線状、点状または破線状等の凹部と、その後に行う７５０℃以上の熱処理よって微細結晶粒を生じさせる方法、あるいは特公平５−６９２８４号公報にあるような、フォトエッチングによって鋼板表面に溝部を形成する方法、特公平８−６１４０号公報にあるような、グラビア印刷でレジスト膜を焼き付け電解腐食により溝を形成する方法等が提案されている。
これらの方法は、溝部／微細結晶粒に生じる磁極による静磁エネルギーの増大を、スラブ状の磁区の幅を狭めることにより補償することを基本的な原理としており、歪取り焼鈍によってその効果が失われることはない。
【０００７】
【発明が解決しようとする課題】
このようにして、方向性電磁鋼板の鉄損は著しく改善されてきたが、文明化、工業化によってエネルギー消費は伸びており、また化石エネルギー資源の枯渇に対する懸念、ＣＯ２ による地球温暖化に対する要望から、より一層の鉄損低減が求められている。また変電設備が都市部に作られるようになり変圧器の発生する騒音を低減することが求められてきている。
【０００８】
【課題を解決するための手段】
本発明者らは、鋼板表面での溝形成を用いた低鉄損方向性電磁鋼板を鋭意研究した結果、溝下に選択的に二次再結晶粒界を形成することによって、極めて低い鉄損で、かつ低騒音の方向性電磁鋼板を製造することを知見した。
すなわち、本発明の要旨は以下の構成からなる。
【０００９】
（１）圧延方向と直角から３０°以内に線状の溝を有し、その溝下部の長さにして１５％以上９０％以下の部分に二次再結晶粒界が存在することを特徴とする方向性電磁鋼板。
（２）方向性電磁鋼板の製造方法において、最終冷延後、再結晶温度まで加熱し、断面の金属組織で観察した再結晶比率で９０％以上完了させた後、圧延方向と直角から３０°以内に線状の溝を機械加工によって形成した後、湿水素中の焼鈍により脱炭を行い、その後、二次再結晶焼鈍を行うことにより、線状溝下部の長さにして１５％以上９０％以下の部分に二次再結晶粒界を存在せしめることを特徴とする方向性電磁鋼板の製造方法。
（３）再結晶温度までの加熱方法が通電加熱あるいは誘導加熱であることを特徴とする前記（２）記載の方向性電磁鋼板の製造方法。
（４）方向性電磁鋼板製造工程において、最終冷延後に冷延板を再結晶温度まで加熱する加熱装置と、圧延方向と直角から３０°以内に線状あるいは不連続な線状の溝を機械加工によって形成する溝形成装置を組み込んだことを特徴とする方向性電磁鋼板の製造装置。
（５）加熱装置による加熱が通電加熱または誘導加熱であることを特徴とする前記（４）に記載の方向性電磁鋼板の製造装置。
（６）再結晶温度までの加熱が通電加熱あるいは誘導加熱であることを特徴とする前記（４）記載の方向性電磁鋼板の製造装置。
【００１０】
【発明の実施の形態】
本発明者等は、質量にして３．２％のＳｉと、インヒビター成分としてＭｎＳ，ＡｌＮを含む方向性電磁鋼板の冷延板（板厚０．２３mm）から、▲１▼鋼板表面の片面にほぼ圧延方向とほぼ直角方向に機械的に線状の溝を加工した後に、６５０℃まで加熱し鋼板の９０％以上を再結晶させた試料、▲２▼６５０℃まで加熱し鋼板の９０％以上を再結晶させた後に、鋼板表面片面のほぼ圧延直角方向に機械的に線状の溝を加工した試料、▲３▼機械加工を行わずに６５０℃まで加熱し、鋼板の９０％以上を再結晶させた試料を作製した。
【００１１】
これらの試料に湿水素中で均熱温度８５０℃で２分間の脱炭を目的とした焼鈍を行い、鋼板表面にＭｇＯの焼鈍分離剤を塗布した後、１２００℃で２０時間の二次再結晶を目的とする焼鈍を施した。前記▲３▼の鋼板には二次再結晶焼鈍後に、▲１▼、▲２▼と同様に鋼板表面片面のほぼ圧延直角方向に機械的に線状の溝を加工した。それぞれの線状溝の間隔は５mm、溝深さは１６μｍであった。
これら試料から単板の磁気測定試料を切り出し、８００℃で３時間の歪取り焼鈍を施した。各試料の磁気測定結果を表１に示す。鉄損、磁束密度、磁歪は、それぞれ鋼板に応力を負荷しない状態で磁束正弦波条件で測定した値である。
【００１２】
【表１】
表１から解るように、前記▲２▼の試料の鉄損、磁歪が、他の試料に較べて優れていることが解る。これら試料の二次再結晶組織を図１に示す。図１のａ）は本発明例▲２▼の二次再結晶組織の模式図、ｂ）は比較例▲１▼の二次再結晶組織の模式図、ｃ）は本発明例▲２▼の二次再結晶組織写真である。
このように、▲１▼、▲３▼の試料の結晶粒界が溝の位置となんら関係がないのに対し、▲２▼の試料ではかなりの部分で溝の下部と二次再結晶粒界の位置が一致していることが解る。また、本発明例では溝を横切る二次再結晶粒界が溝により分断されていることが解る。
【００１４】
本発明者等はさらに詳細な実験を施し、以下の関係を見いだした。
すなわち図２に示すように、導入した溝の全長に対して、溝下部に二次再結晶粒界の存在する溝の長さの比率が１５％以上で９０％以下の時に優れた鉄損を持つ。この一連の実験では、３．１％ＳｉとＡｌＮとＭｎＳを含む方向性電磁鋼板の冷延板を、通電加熱により３００℃／sec の加熱速度で８００℃まで加熱した後、歯車で圧延直角方向から１０゜の方向に機械的に溝を加工し、その後上記の実験と同じ処理を施して二次再結晶させた。
【００１５】
以上に述べた優れた鉄損値が得られる理由としては、線状の溝による磁区制御効果と、規則的に導入した二次再結晶粒界による磁区制御効果の複合効果であると推定される。この複合効果による鉄損向上は、導入される粒界が少なすぎると小さく、また多すぎてもかえって小さくなると考えられる。
【００１６】
また、線状の溝部と二次再結晶粒界を適当量導入することにより磁歪が小さくなる理由としては、二次再結晶粒の結晶方位が理想的なゴス方位よりずれることにより生ずる、
ランセットと呼ばれる表面補助磁区（例えば Alex Hubertet.al.Z.Angew.Phys.,19,521-529,(1965)）により励磁されたときに方向性電磁鋼板が縮む効果と、溝部あるいは二次再結晶粒界に生ずる補助磁区により励磁されたときに方向性電磁鋼板が伸びる効果が補償し合って生じていると推定される。
また、本発明では溝を横切る二次再結晶粒界が溝により分断されていることも、上記の理由の一つとして推定される。
【００１７】
以下、本発明の実施の形態について説明する。
本発明の方向性電磁鋼板の成分としては、従来公知のいずれの成分組成も適合するが、代表組成をあげると以下の様になる。
Ｓｉは、添加量を多くすると電気抵抗が高くなり、鉄損特性が改善される。しかし４．８％を超えると、圧延時に割れやすくなってしまう。また０．８％より少ないと、仕上げ焼鈍時にγ変態が生じ結晶方位が損なわれてしまう。
【００１８】
Ｃは、一次再結晶組織を制御するうえで有効な元素であるが、磁気特性に悪影響を及ぼすので、仕上げ焼鈍前に脱炭する必要がある。Ｃが０．０８５％より多いと、脱炭焼鈍時間が長くなり生産性が損なわれてしまう。
【００１９】
二次再結晶を生じさせるために必要ないわゆるインヒビターとしては、ＡｌＮ系、ＭｎＳ系、ＭｎＳｅ系いずれでも本発明の意図を損なうものではないが、より低鉄損を得るためにはＡｌＮ系が最も好適である。その場合、酸可溶性Ａｌは二次再結晶が安定する０．０１〜０．０６５％が好ましい。
【００２０】
Ｎは、０．０１２％を超えると冷延時にブリスターとよばれる鋼板中の空孔を生じるので、それ以下に抑えることが望ましい。
この他、微量のＣｕ，Ｓｂ，Ｍｏ，Ｂｉ，Ｔｉ等を鋼中に含有することは、本発明の主旨を損なうものではない。
【００２１】
こうして得られた鋼スラブを加熱後、熱間圧延し、必要に応じて熱延板焼鈍を施した後に、１回ないし中間焼鈍を挟んだ２回の冷間圧延を行い最終板厚とした後、必要に応じて湿水素中で脱炭焼鈍を行い、ＭｇＯを主体とする焼鈍分離剤を表面に塗布して、二次再結晶を目的とする最終仕上げ焼鈍を行う。
【００２２】
以上の工程において、冷間圧延後、一次再結晶させた鋼板に機械的に線状あるいは不連続な溝加工を施した後に二次再結晶させることが本発明の特徴である。このプロセスにより溝下部の大部分に二次再結晶粒界が形成され、優れた鉄損特性および磁歪特性を示すこととなる。
【００２３】
機械的に溝加工を形成する方法については、特公昭６２−５３５７９号公報に開示された歯車型ロールによる方法、特公平０６−６３０３７号公報に開示されたプレスによる方法等いずれを用いてもよい。
形成する溝の形状は、ほぼ圧延方向に直角な連続ないし不連続な直線状の溝、特に連続的な直線状の溝が望ましい。圧延直角方向の場合に最も効果が大きいが、直角方向より３０゜以内であればその効果は大きくは変わらない。また直線状が工具の加工上望ましいが、曲線の溝にしてもその効果を失うものではない。曲線の場合には、中心線の方向が圧延直角方向より３０゜以内になるようにすればよい。
【００２４】
線状溝の幅は１０〜３００μｍ、深さは５〜５０μｍ、溝間隔は圧延方向に１〜２０mmが好ましいが、この範囲を外れても本発明の効果が発現しないわけではない。また溝加工は片面のみで十分に効果があるが、両面に施しても本発明の思想に反するものではない。
【００２５】
一次再結晶は、断面の金属組織で観察した再結晶比率で５０％以上を、より望ましくは９０％以上を完了させることが好ましいが、必ずしも本発明の条件を限定するものではない。再結晶温度としては、再結晶比率５０％では６００℃以上、９０％では６５０℃以上が望ましい。
一次再結晶させる方法としては、一般的な焼鈍炉による方法、通電加熱による方法、誘導加熱による方法と何れの方法を用いても本発明の思想を損なうものではないが、設備のコンパクト化の観点から通電加熱あるいは誘導加熱による方法が好ましい。
【００２６】
こうして得られた表面に溝加工を施した鋼板に、必要に応じて湿水素中で脱炭と一次再結晶粒成長を目的とする焼鈍を施すが、磁気時効を起こさない程度にしか鋼成分にＣを含まない場合には、以下に記述する二次再結晶焼鈍の前半部分で該焼鈍の効果を兼用しても構わない。
【００２７】
この後、鋼板表面にＭｇＯを主体とする焼鈍分離剤を塗布し、高温の二次再結晶焼鈍に供する。この際、Ａｌ2 Ｏ3 を主体とした焼鈍分離剤を用いて、Ｍｇ2 ＳｉＯ4 からなるセラミック被膜を形成させない工程をとることも可能である。この二次再結晶焼鈍に際して、必要に応じて特開平２−７７５２５号公報にあるようなＮＨ3 ガス等を用いて上記の湿水素焼鈍後、二次再結晶焼鈍前にＮＨ3 等の雰囲気ガスからの窒化によるＡｌＮのインヒビターの補強を行うこと、または二次再結晶焼鈍の前段で、Ｎ2 雰囲気より窒化によるＡｌＮ系のインヒビターの補強を行うことも、本発明の効果を損なうものではない。
また、磁気時効を起こさない程度にしかＣを含まない場合には、二次再結晶焼鈍の前半で一次再結晶粒成長を行わせ、前述の湿水素中での脱炭と一次再結晶粒成長を目的とする焼鈍を省略することも可能である。
【００２８】
【実施例】
以下、本発明を実施例に基づいてさらに説明する。
（実施例１）
質量で３．３％ＳｉとＭｎＳｅとＡｌＮ、Ｓｂのインヒビター成分（質量にしてＭｎ：０．０７％、Ｓｅ：０．０２％、酸可溶Ａｌ：０．０２５％、Ｎ：０．００８％、Ｓｂ：０．０４％）を含む０．２３mm厚の冷延板を、焼鈍炉で７００℃まで３０℃／sec で加熱し１００％再結晶させた後、（Ａ）歯車型ロールを用いて線状溝を形成した試料Ａ、（Ｂ）グラビア印刷で溝パターンを転写後、電解エッチングで溝加工をした試料Ｂに、それぞれ８５０℃で１００sec の湿水素中焼鈍を行い、ＭｇＯを主体とする焼鈍分離剤を鋼板表面に塗布後、１２００℃で１７hrの二次再結晶焼鈍を施した。Ａ，Ｂともに溝形状は直線状で、角度は圧延直角方向から１２゜、溝間隔３mm、溝幅１００μｍ、溝深さ２０μｍであった。それぞれの鉄損値を表２に示す。
溝下部粒界比率が本発明範囲である材料Ａの鉄損が、材料Ｂに較べ低い鉄損を持つことがわかる。
【００２９】
【表２】
（実施例２）
本発明の方向性電磁鋼板の製造において、線状の溝を形成する場合の好適な装置例を図３に示す。すなわち、方向性電磁鋼板のコイルに巻かれた冷延板１は、巻きほぐされて加熱装置２に通り、再結晶温度もしくはそれ以上の温度に加熱されて鋼板を再結晶させる。加熱手段は通電加熱或いは誘導加熱のいずれでもよい。次いで溝形成装置３に導入し、機械加工して鋼板表面に線状もしくは不連続線状の溝を形成した後に、脱炭を目的とした焼鈍を焼鈍装置４で施し、ＭｇＯを主体とする焼鈍分離剤をコーター５で鋼板表面に塗布し、コイラー６に巻取るまでの工程を示す。
図３では、加熱装置２、溝形成装置３、焼鈍装置４の一連の工程を示したが、加熱装置と溝形成装置を脱炭を目的とする焼鈍装置に組み込んでもよい。
【００３１】
【発明の効果】
以上説明した本発明によって、鉄損と磁歪を低減した方向性電磁鋼板を製造することができる。
【図面の簡単な説明】
【図１】溝と二次再結晶粒界の位置関係を示す鋼板表面の図。点線で溝の位置、実線で二次再結晶粒界の位置を示す。太い実線は二次再結晶粒界が溝の下にある部分を示す。ａ）は本発明例、ｂ）は比較例。ｃ）は本発明例での鋼板表面での金属組織写真である。
【図２】線状溝の溝下部分の板厚を貫通する二次再結晶粒界の、溝総延長に対する存在比率と鉄損Ｗ17/50 との関係を表す図。
【図３】方向性電磁鋼板の冷延板を加熱後、圧延方向とほぼ直角方向にほぼ線状の溝を機械加工によって形成し、さらに焼鈍する装置に一例を示す図。
【符号の説明】
１：冷延板
２：加熱装置
３：溝形成装置
４：焼鈍装置
５：コータ
６：コイラー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel sheet with reduced iron loss in a grain-oriented electrical steel sheet used for a static inductor such as a transformer, a manufacturing method thereof, and a manufacturing apparatus.
[0002]
[Prior art]
The grain-oriented electrical steel sheet is mainly used for a static inductor represented by a transformer. The characteristics to be satisfied are as follows: (1) Energy loss, ie, iron loss, is small when excited with AC, (2) High permeability in the excitation range of equipment, and easy excitation, (3) Cause of noise For example, the magnetostriction is small. In particular, for (1), T. is an index representing the value of the transformer because it is continuously energized over a long period of time from when the transformer is installed until it is discarded and energy loss continues to be generated. O. C. This is the main parameter that determines (Total Owning Cost).
[0003]
Many developments have been made so far in order to reduce the iron loss of the grain-oriented electrical steel sheet. (1) Increasing the accumulation in the (110) [001] orientation, called the Goss orientation, (2) Increasing the content of a solid solution element such as Si that increases the electrical resistance, (3) Decreasing the thickness of the steel sheet These include thinning, (4) applying a ceramic coating or insulating coating that imparts surface tension to the steel sheet, and (5) reducing the size of crystal grains.
However, there is a limit to iron loss improvement by these metallurgical methods, and reduction of iron loss by other methods has been demanded.
[0004]
In response to this problem, A. Fiedler and W. Pepperhof have proposed a method of reducing iron loss by changing the magnetic domain structure by grooving the surface of a grain-oriented electrical steel sheet with a cutter or the like (USP 3,646, US Pat. 575). A grain-oriented electrical steel sheet generally has a magnetic domain structure in which slab-like magnetic domains having magnetization components in opposite directions are alternately arranged, and magnetization is performed by expanding / reducing these magnetic domains under an external magnetic field. Therefore, when the grain-oriented electrical steel sheet is magnetized, the magnetization change occurs only at the boundary (domain wall) between adjacent magnetic domains. With this change in magnetization, eddy current flows in the steel sheet, accounting for 60 to 70% of the cause of the iron loss described above (eddy current loss). The eddy current loss is proportional to the square of the eddy current, and the eddy current is proportional to the moving speed of the domain wall. When the magnetic domain width is narrowed, more eddy currents are generated, but the domain wall moving speed decreases in inverse proportion to the magnetic domain width. As a result, the eddy current loss decreases approximately in proportion to the magnetic domain width.
[0005]
Various proposals have been made to make this magnetic domain subdivision technique industrially applicable. For example, as disclosed in Japanese Examined Patent Publication No. 58-5968, a method of introducing a strain without scratching the surface by rotating a small sphere having a diameter of 0.2 to 10 mm against a steel plate surface, Japanese Patent Publication No. 57-2252 As disclosed in Japanese Laid-Open Patent Publication No. 62-96617, a method of applying a small plastic strain by irradiating a laser beam in a direction substantially perpendicular to the rolling direction. There is a method to radiate to.
All of these are technologies that introduce a small plastic strain into a steel sheet and subdivide the magnetic domain using magnetic domains having a magnetization component perpendicular to the rolling direction, which is stabilized by the inverse effect of magnetostriction. The effect was lost by the strain relief annealing at the time of manufacturing.
[0006]
Furthermore, for these magnetic domain subdivision methods, a heat-resistant magnetic domain subdivision method that does not lose its effect even by strain relief annealing has been studied. For example, as disclosed in Japanese Patent Publication No. 63-44804, a steel plate after finish annealing is used. A method of generating fine crystal grains by a heat treatment at 750 ° C. or higher, which is performed by a heat treatment at 750 ° C. or higher, or a photoetching as disclosed in Japanese Patent Publication No. 5-69284. A method for forming a groove on the surface of a steel sheet, a method for baking a resist film by gravure printing, and a method for forming a groove by electrolytic corrosion as disclosed in Japanese Patent Publication No. 8-6140 have been proposed.
The basic principle of these methods is to compensate for the increase in magnetostatic energy due to the magnetic poles generated in the grooves / fine crystal grains by narrowing the width of the slab-like magnetic domain, and the effect is lost by strain relief annealing. It will never be.
[0007]
[Problems to be solved by the invention]
In this way, the iron loss of grain-oriented electrical steel sheets has been remarkably improved, but energy consumption has increased due to civilization and industrialization, and there are concerns about depletion of fossil energy resources, CO 2. Due to the demand for global warming due to, further reduction of iron loss is required. In addition, substation facilities have been built in urban areas, and it has been required to reduce noise generated by transformers.
[0008]
[Means for Solving the Problems]
As a result of diligent research on low iron loss-oriented electrical steel sheets using groove formation on the steel sheet surface, the inventors have found that extremely low iron loss can be achieved by selectively forming secondary recrystallized grain boundaries under the grooves. In addition, it has been found that a low-noise grain-oriented electrical steel sheet is manufactured.
That is, the gist of the present invention has the following configuration.
[0009]
(1) It has a linear groove within 30 ° from a right angle to the rolling direction, and a secondary recrystallized grain boundary exists in a portion of 15% or more and 90% or less as a length of the lower part of the groove. Oriented electrical steel sheet.
(2) In the method for producing a grain-oriented electrical steel sheet, after the final cold rolling, the steel is heated to the recrystallization temperature, and the recrystallization ratio observed in the metal structure of the cross section is 90% or more, and then 30 ° from the right angle to the rolling direction After forming a linear groove by machining, decarburization is performed by annealing in wet hydrogen, followed by secondary recrystallization annealing, so that the length of the linear groove lower portion is 15% or more 90% A method for producing a grain-oriented electrical steel sheet, wherein a secondary recrystallized grain boundary is present in a portion of less than 1%.
( 3 ) The method for producing a grain-oriented electrical steel sheet according to ( 2 ), wherein the heating method up to the recrystallization temperature is electric heating or induction heating.
( 4 ) In the grain-oriented electrical steel sheet manufacturing process, a heating device that heats the cold-rolled sheet to the recrystallization temperature after the final cold-rolling, and a linear or discontinuous linear groove within 30 ° from the direction perpendicular to the rolling direction are machined. An apparatus for producing grain-oriented electrical steel sheets, incorporating a groove forming device formed by machining.
( 5 ) The apparatus for producing a grain-oriented electrical steel sheet according to ( 4 ), wherein the heating by the heating device is energization heating or induction heating.
( 6 ) The grain-oriented electrical steel sheet manufacturing apparatus as described in ( 4 ) above, wherein the heating to the recrystallization temperature is electric heating or induction heating.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
From the cold rolled sheet (thickness 0.23 mm) of grain oriented electrical steel sheet containing 3.2% Si by mass and MnS and AlN as inhibitor components, the present inventors (1) on one side of the steel sheet surface A sample in which linear grooves are mechanically machined in a direction substantially perpendicular to the rolling direction and then heated to 650 ° C. to recrystallize 90% or more of the steel plate. (2) 90% or more of the steel plate heated to 650 ° C. After recrystallizing the sample, a sample in which a linear groove was mechanically machined in a direction substantially perpendicular to the rolling direction on one side of the steel plate, and (3) heated to 650 ° C. without machining, and 90% or more of the steel plate was regenerated. A crystallized sample was prepared.
[0011]
These samples were annealed in wet hydrogen at a soaking temperature of 850 ° C. for 2 minutes for the purpose of decarburization, and an MgO annealing separator was applied to the steel sheet surface, followed by secondary recrystallization at 1200 ° C. for 20 hours. Annealing for the purpose was performed. After the secondary recrystallization annealing, linear grooves were mechanically machined in the steel sheet of (3) in the direction substantially perpendicular to the rolling on one side of the steel sheet, as in (1) and (2). The interval between the linear grooves was 5 mm, and the groove depth was 16 μm.
Single-plate magnetic measurement samples were cut out from these samples and subjected to strain relief annealing at 800 ° C. for 3 hours. Table 1 shows the magnetic measurement results of each sample. Iron loss, magnetic flux density, and magnetostriction are values measured under magnetic flux sine wave conditions without applying stress to the steel sheet.
[0012]
[Table 1]
As can be seen from Table 1, it can be seen that the iron loss and magnetostriction of the sample (2) are superior to those of the other samples. The secondary recrystallization structure of these samples is shown in FIG. FIG. 1 a) is a schematic diagram of the secondary recrystallized structure of the present invention example (2), b) is a schematic diagram of the secondary recrystallized structure of the comparative example (1), and c) is the example of the present invention example (2). It is a secondary recrystallization structure photograph.
Thus, while the grain boundaries of the samples (1) and (3) have nothing to do with the position of the groove, the lower part of the groove and the secondary recrystallized grain boundary in the part (2) It can be seen that the positions of match. Moreover, in the example of this invention, it turns out that the secondary recrystallization grain boundary crossing a groove | channel is divided | segmented by the groove | channel.
[0014]
The present inventors conducted further detailed experiments and found the following relationship.
That is, as shown in FIG. 2, the iron loss is excellent when the ratio of the length of the groove where the secondary recrystallized grain boundary exists in the lower part of the groove is 15% or more and 90% or less with respect to the entire length of the introduced groove. Have. In this series of experiments, a cold-rolled sheet of grain-oriented electrical steel sheet containing 3.1% Si, AlN, and MnS was heated to 800 ° C. at a heating rate of 300 ° C./sec by energization heating, and then rolled in the direction perpendicular to the rolling direction. Grooves were mechanically machined in the direction of 10 ° from the above, and then subjected to the same treatment as in the above experiment for secondary recrystallization.
[0015]
The reason why the above-described excellent iron loss value can be obtained is presumed to be a combined effect of the magnetic domain control effect by the linear groove and the magnetic domain control effect by the regularly introduced secondary recrystallized grain boundary. . The iron loss improvement due to this combined effect is considered to be small if too few grain boundaries are introduced, and small if too much.
[0016]
The reason why magnetostriction is reduced by introducing an appropriate amount of linear grooves and secondary recrystallized grain boundaries is that the crystal orientation of the secondary recrystallized grains deviates from the ideal Goss orientation,
Surface auxiliary magnetic domains, called a lancet (e.g., Alex Hubertet.al.Z.Angew.Phys., 19,521-529, (1965 )) and effects of grain-oriented electrical steel sheet shrinks when it is excited by, the groove or the secondary re It is presumed that the effect of extending the grain-oriented electrical steel sheet when compensated by the auxiliary magnetic domain generated at the grain boundary compensates for each other.
In the present invention, it is also presumed as one of the above-mentioned reasons that the secondary recrystallized grain boundary crossing the groove is divided by the groove.
[0017]
Embodiments of the present invention will be described below.
As a component of the grain-oriented electrical steel sheet of the present invention, any conventionally known component composition is suitable, but the typical composition is as follows.
When Si is added in an increased amount, the electrical resistance increases and the iron loss characteristics are improved. However, if it exceeds 4.8%, it tends to break during rolling. On the other hand, if it is less than 0.8%, the γ transformation occurs during finish annealing and the crystal orientation is impaired.
[0018]
C is an effective element for controlling the primary recrystallization structure, but it adversely affects the magnetic properties, so it is necessary to decarburize before finish annealing. When C is more than 0.085%, the decarburization annealing time becomes long and the productivity is impaired.
[0019]
As the so-called inhibitor necessary for causing secondary recrystallization, the AlN system, MnS system, and MnSe system do not impair the intention of the present invention, but in order to obtain a lower iron loss, the AlN system is the most. Is preferred. In that case, the acid-soluble Al is preferably 0.01 to 0.065% at which secondary recrystallization is stabilized.
[0020]
If N exceeds 0.012%, voids in the steel plate called blisters are produced during cold rolling, so it is desirable to keep N below that.
In addition, the inclusion of a small amount of Cu, Sb, Mo, Bi, Ti or the like in the steel does not impair the gist of the present invention.
[0021]
After heating the steel slab obtained in this way, hot-rolling, hot-rolled sheet annealing as necessary, and then cold rolling twice or two times with intermediate annealing to the final sheet thickness If necessary, decarburization annealing is performed in wet hydrogen, an annealing separator mainly composed of MgO is applied to the surface, and final finishing annealing for the purpose of secondary recrystallization is performed.
[0022]
In the above steps, it is a feature of the present invention that after cold rolling, the primary recrystallized steel sheet is mechanically subjected to linear or discontinuous grooving and then secondary recrystallized. By this process, secondary recrystallized grain boundaries are formed in most of the lower portion of the groove, and excellent iron loss characteristics and magnetostriction characteristics are exhibited.
[0023]
As a method for mechanically forming grooves, any of a method using a gear-type roll disclosed in Japanese Patent Publication No. 62-53579 and a method using a press disclosed in Japanese Patent Publication No. 06-63037 may be used. .
The shape of the groove to be formed is preferably a continuous or discontinuous linear groove substantially perpendicular to the rolling direction, particularly a continuous linear groove. The effect is greatest in the case of the direction perpendicular to the rolling, but the effect is not greatly changed if it is within 30 ° from the direction perpendicular to the rolling. In addition, a straight line shape is desirable for machining the tool, but the effect is not lost even if the groove is curved. In the case of a curve, the direction of the center line may be within 30 ° from the direction perpendicular to the rolling.
[0024]
The width of the linear groove is preferably 10 to 300 μm, the depth is 5 to 50 μm, and the groove interval is preferably 1 to 20 mm in the rolling direction. However, the effect of the present invention is not manifested even if it is outside this range. Further, the groove processing is sufficiently effective only on one side, but even if it is applied on both sides, it does not violate the idea of the present invention.
[0025]
In the primary recrystallization, it is preferable to complete 50% or more, more desirably 90% or more, in the recrystallization ratio observed in the metal structure of the cross section, but the conditions of the present invention are not necessarily limited. The recrystallization temperature is preferably 600 ° C. or higher at a recrystallization ratio of 50% and 650 ° C. or higher at 90%.
As a method for primary recrystallization, any method such as a general annealing furnace method, a method using electric heating, a method using induction heating and the like will not impair the idea of the present invention. From the above, a method by electric heating or induction heating is preferable.
[0026]
The steel sheet obtained by grooving the surface thus obtained is subjected to annealing for decarburization and primary recrystallized grain growth in wet hydrogen as necessary, but only to the extent that magnetic aging does not occur. When C is not included, the effect of the annealing may be used in the first half of the secondary recrystallization annealing described below.
[0027]
Thereafter, an annealing separator mainly composed of MgO is applied to the surface of the steel sheet and subjected to high temperature secondary recrystallization annealing. At this time, it is also possible to take a step of not forming a ceramic coating made of Mg 2 SiO 4 using an annealing separator mainly composed of Al 2 O 3 . At the time of this secondary recrystallization annealing, an atmospheric gas such as NH 3 after the above-described wet hydrogen annealing and before the secondary recrystallization annealing using NH 3 gas as disclosed in Japanese Patent Laid-Open No. 2-77525 as necessary. The effect of the present invention is not impaired by reinforcing the inhibitor of AlN by nitriding from or by reinforcing the inhibitor of AlN by nitriding from the N 2 atmosphere before the secondary recrystallization annealing.
When C is contained only to the extent that magnetic aging does not occur, primary recrystallized grain growth is performed in the first half of secondary recrystallization annealing, and decarburization and primary recrystallized grain growth in the above-mentioned wet hydrogen are performed. It is also possible to omit the annealing for the purpose.
[0028]
【Example】
Hereinafter, the present invention will be further described based on examples.
Example 1
Inhibitor component of 3.3% Si, MnSe, AlN, Sb by mass (Mn: 0.07%, Se: 0.02%, acid-soluble Al: 0.025%, N: 0.008% by mass) , Sb: 0.04%), a 0.23 mm thick cold-rolled sheet was heated to 700 ° C at 30 ° C / sec in an annealing furnace and recrystallized 100%, and then (A) using a gear-type roll Sample A in which linear grooves are formed, (B) After transferring the groove pattern by gravure printing, sample B which has been groove processed by electrolytic etching is annealed in wet hydrogen at 850 ° C. for 100 seconds, and is mainly composed of MgO. After applying the annealing separator to the steel sheet surface, secondary recrystallization annealing was performed at 1200 ° C. for 17 hours. In both A and B, the groove shape was linear, the angle was 12 ° from the direction perpendicular to the rolling, the groove interval was 3 mm, the groove width was 100 μm, and the groove depth was 20 μm. Table 2 shows the respective iron loss values.
It can be seen that the iron loss of the material A having a groove lower grain boundary ratio within the range of the present invention is lower than that of the material B.
[0029]
[Table 2]
(Example 2)
In the production of the grain-oriented electrical steel sheet according to the present invention, FIG. 3 shows a preferred apparatus example for forming a linear groove. That is, the cold-rolled sheet 1 wound around the coil of the grain-oriented electrical steel sheet is unwound and passes through the heating device 2, and is heated to a recrystallization temperature or higher to recrystallize the steel sheet. The heating means may be either energization heating or induction heating. Then introduced into the
Although FIG. 3 shows a series of steps of the heating device 2, the
[0031]
【The invention's effect】
With the present invention described above, a grain-oriented electrical steel sheet with reduced iron loss and magnetostriction can be produced.
[Brief description of the drawings]
FIG. 1 is a diagram of a steel sheet surface showing the positional relationship between grooves and secondary recrystallization grain boundaries. The dotted line indicates the groove position, and the solid line indicates the secondary recrystallization grain boundary position. The thick solid line indicates the portion where the secondary recrystallization grain boundary is under the groove. a) is an example of the present invention, and b) is a comparative example. c) is a metallographic photograph on the surface of the steel sheet in the present invention example.
FIG. 2 is a diagram showing the relationship between the abundance ratio of the secondary recrystallized grain boundary penetrating the plate thickness of the lower part of the linear groove with respect to the total groove extension and the iron loss W 17/50 .
FIG. 3 is a diagram showing an example of an apparatus that heats a cold-rolled sheet of grain-oriented electrical steel sheet, forms a substantially linear groove in a direction substantially perpendicular to the rolling direction by machining, and further anneals the apparatus.
[Explanation of symbols]
1: Cold-rolled plate 2: Heating device 3: Groove forming device 4: Annealing device 5: Coater 6: Coiler
Claims (6)
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| JP5302878B2 (en) * | 2009-12-28 | 2013-10-02 | 株式会社日立産機システム | Groove processing apparatus and method for electromagnetic steel sheet |
| JP5600991B2 (en) * | 2010-03-29 | 2014-10-08 | 新日鐵住金株式会社 | Method for producing grain-oriented electrical steel sheet |
| EP2615184B1 (en) | 2010-09-09 | 2015-08-05 | Nippon Steel & Sumitomo Metal Corporation | Oriented electromagnetic steel sheet and process for production thereof |
| RU2509164C1 (en) * | 2010-09-10 | 2014-03-10 | ДжФЕ СТИЛ КОРПОРЕЙШН | Texture electric steel sheet and method of its production |
| US9704626B2 (en) * | 2012-04-26 | 2017-07-11 | Jfe Steel Corporation | Grain-oriented electrical steel sheet and method of manufacturing same |
| JP6003341B2 (en) * | 2012-07-27 | 2016-10-05 | Ｊｆｅスチール株式会社 | Steel plate processing state evaluation method and steel plate processing state evaluation apparatus |
| JP7372520B2 (en) | 2019-08-01 | 2023-11-01 | 日本製鉄株式会社 | Grain-oriented electrical steel sheet, wound iron core, method for producing grain-oriented electrical steel sheet, and method for manufacturing wound iron core |
| JP7277755B2 (en) * | 2019-08-01 | 2023-05-19 | 日本製鉄株式会社 | Grain-oriented electrical steel sheet, wound iron core, method for producing grain-oriented electrical steel sheet, and method for producing wound iron core |
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| KR20180000435A (en) * | 2016-06-23 | 2018-01-03 | 주식회사 포스코 | Wound core and method for manufacturing wound core |
| KR101908042B1 (en) * | 2016-06-23 | 2018-10-15 | 주식회사 포스코 | Wound core and method for manufacturing wound core |
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