JP3952606B2 - Oriented electrical steel sheet with excellent magnetic properties and coating properties and method for producing the same - Google Patents

Description

【００２９】
表１より、（ａ）の方向性電磁鋼板は、被膜外観、被膜密着性および鉄損値が他より優れていることがわかる。そこで、この理由を調査するため、各種方向性電磁鋼板の下地被膜の薄膜断面試料を電子顕微鏡で調査した。すなわち、鋼板（ａ）の下地被膜について、電子顕微鏡による写真およびμ−回折（マイクロデイフラクション）を図１に、その説明図を図２に、元素濃度分析図を図３に、それぞれ示すように、該下地被膜はフォルステライト粒子のみから構成され、かつフォルステライト粒子中に一部Ａｌを含有する領域がＦｅ低合金素地に接して存在していることがわかる。なお、図２において、符号１はフォルステライト（Ａｌ非含有部）、２はＡｌ含有部とＡｌ非含有部との境界、３はフォルステライト（Ａｌ含有部）、５は被膜固定用の樹脂、６は地鉄および７はフォルステライト上へのＦｅ合金の重なり部分である。
【００３０】
ここで、図２の１ｓ〜１ｆの領域について元素分析を行い、Ａｌのカウント数：Ｎａ，Ｍｇのカウント数：ＮｍおよびＳｉのカウント数：Ｎｓの値を、酸素のカウント数：Ｎｏの値でそれぞれ割った値：Ｎａ／Ｎｏ、Ｎｍ／ＮｏおよびＮｓ／Ｎｏについて、その被膜厚み方向における変化を図３に示した。この図３より、フォルステライト（Ｍｇ₂ ＳｉＯ₄ ）粒子中に一部Ａｌを含有する領域が存在し、かつＡｌを含有する領域は地鉄に接しており、さらに地鉄に向かってＡｌの濃度が増加していることがわかる。ちなみに、図１に示したμ−回折はＡｌを高濃度に含有する領域での回折パターンであるが、斜方晶であり、また、その格子定数からフォルステライトであることが、回折パターンの解析から確認された。
【００３１】
これに対して、特性の劣る鋼板（ｂ）、（ｃ）、（ｄ）および（ｅ）の下地被膜は、フォルステライト粒子のみからなっているがＡｌを含有していない。例えば鋼板（ｂ）のフォルステライト系被膜について、電子顕微鏡による写真およびμ−回折を図４に、その説明図を図５に、それぞれ示すように、フォルステライト粒子のみからなっており、しかもフォルステライト粒子は図６に示されるようにＡｌを含んでいない。
【００３２】
また、同じく特性の劣る鋼板（ｆ）や（ｇ）は従来技術に認められるものと同様、フォルステライト粒子とＡｌを含有するスピネル粒子の２種類の酸化物からなっている。例えば鋼板（ｇ）のフォルステライト系被膜について、その電子顕微鏡による写真およびμ−回折を図７に、その説明図を図８に示すように、下地被膜の構造として、地鉄６とフォルステライト粒子１との間にスピネル粒子５が存在しており、図９に示すように、フォルステライト粒子中にＡｌは含有されておらず、スピネル粒子中のＡｌの濃度は一定となっている。
【００３３】
以上で述べた、微視的な下地被膜の構造およびこの構造が下地被膜の性質に関わってくるという事実は、これまで知られてはおらず、この実験から得た新規な知見である。
【００３４】
次に、上記した微視的な被膜構造の変化が、如何なる機構によって鋼板の磁気特性に影響を及ぼすかについて考察した結果を述べる。
フォルステライト被膜は鋼板に対して張力を及ぼすと同時に、反作用として、鋼板から強い圧縮応力を受けている。ここで、フォルステライト粒子と鋼板との間にスピネルのようなヤング率が高く硬い物質が存在すると、鋼板への張力作用がより強く働くことが予想されるが、実際は、これとは逆に、このような硬い物質が存在することによって、セラミックスであるフォルステライト被膜の靱性が劣化し、被膜が破断されやすくなって、微視的な領域において被膜は剥落することになる。その結果、フォルステライト被膜は、鋼板へ張力を有効に作用させることができずに、被膜の張力作用は不均一なものとなり、渦電流損やヒステリシス損の増大により鉄損が増加して磁気特性が劣化する。
【００３５】
これに対し、フォルステライト粒子にＡｌを含有させた新しい被膜では、被膜の靱性は損なわれず、また地鉄に向かってＡｌ含有量が増加していくことによってフォルステライトの結晶の格子間隔も増加することが、電子線のμ−回折によって確認されており、こうした変化がより強い張力作用を地鉄に及ぼす結果になる。換言すると、上記した鋼板（ａ）の下地被膜は、一種の微視的な傾斜機能を有する被膜ということができる。以上、フオルステライト粒子がＡｌを含有し、かつＡｌ含有領域が地鉄と接する位置にあること、およびＡｌの濃度が地鉄に向かって増加していることが、鋼板（ａ）の製品の下地被膜の特徴であり、これが被膜の密着性を格段に向上させ、また磁気特性をも向上させた要因である。さらに、被膜と鋼板との密着性が強固なものになることによって、フォルステライトやその上に塗布された張力コーティングによる張力が鋼板に有効に伝達され、方向性電磁鋼板の鉄損が向上したものと推定される。
【００３６】
ちなみに、上記の鋼板（ａ）〜（ｇ）の下地被膜のフォルステライト粒子の平均粒径は、いずれも０．７μm 以下であり、鋼板（ａ）のものにおいて、とりわけ平均粒径が小さい傾向はなく、このことが被膜の密着性を向上させたわけではなかった。
【００３７】
次に、鋼板（ａ）のようなＡｌを含有するフォルステライト粒子を形成する手法について、詳しく説明する。
すなわち、この発明に従うフォルステライト系被膜を得るには、１次再結晶焼鈍後の鋼板表面層に生成する酸化物として、シリカ（ＳｉＯ₂ ）だけでなくファイヤライト（Ｆｅ₂ ＳｉＯ₄ ）を存在させること、および焼鈍分離剤中にＡｌを含有する物質を微量に含むことが重要である。このファイヤライトは被膜形成反応の過程においてＭｇＯと反応しオリビン｛（Ｆｅ，Ｍｇ）₂ ＳｉＯ₄ ｝となり、最終的にフォルステライト（Ｍｇ₂ ＳｉＯ₄ ）に変化していくが、この反応過程の制御が極めて重要であり、反応時期を正しく制御することによって、フォルステライト粒子中に焼鈍分離剤中の上記Ａｌ成分、同時に鋼板中に存在するＡｌをも、有効にフォルステライト粒子中に取り込むことができる。
【００３８】
この反応時期の制御のためには、反応物のＭｇＯを大量に含む焼鈍分離剤中にＡｌを含有させることが必要であり、その含有量はＡｌ₂ Ｏ₃ に換算して０．０１〜８．０％とする。
【００３９】
さらに、１次再結晶焼鈍と同様に最終仕上げ焼鈍における雰囲気ガスの制御も肝要となる。すなわち、第１に、１次再結晶焼鈍後の鋼板表面に適正な量のファイヤライトを生成させるためには、１次再結晶焼鈍を、５００℃以上の平均昇温速度を５℃／ｓ以上にて焼鈍温度を７００〜９５０℃の範囲に調整し、かつ少なくとも５００℃以上の温度域において、雰囲気のＰ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）を６０秒間以上にわたって０．１５〜０．７５として行うことが、肝要である。なお、ファイヤライトはシリカに比較し、より鋼板表面側に生成する酸化物であり、上記の雰囲気にて生成させたのち、例えば還元処理によってシリカになる場合もあるが、ファイヤライトが完全にシリカに還元されるのでなければ、この発明の技術は十分に適用でき、残存するファイヤライトによって目的は達成される。
【００４０】
特に、鋼板表面に存在するファイヤライトは、オリビン｛（Ｆｅ，Ｍｇ）₂ ＳｉＯ₄ ｝形成反応上重要であり、図１０に示す鋼板の赤外反射スペクトルにおけるファイヤライトのピーク位置（９８０ｃｍ^-1）とシリカのピーク位置（１２４０ｃｍ^-1）とから、図１１に示した計算法に基づいて算出した、ファイヤライトの吸光度：Ａｆとシリカの吸光度：Ａｓとの比：Ａｆ／Ａｓを、０．３〜５．０の範囲とすることによって、さらに一段と優れた下地被膜を得ることができる。
【００４１】
この発明の下地被膜を形成させる要件の第２として、１次再結晶焼鈍後に、純粋なＭｇＯを７０〜９７％で含有し、かつＡｌを含む物質またはマグネシア中にＡｌ₂ Ｏ₃ に換算して０．０１〜８．０％の量のＡｌを含有する焼鈍分離剤を塗布することである。これにより、良好なフォルステライト粒子が生成すると同時に、焼鈍分離剤や地鉄から供給されたＡｌがフォルステライト粒子中に取り込まれることになる。
【００４２】
さらに、第３の必須要件としては、最終仕上げ焼鈍を、４００〜１０００℃の昇温過程では、Ｎ₂ およびＡｒのいずれか一方の雰囲気または両者の混合雰囲気にて、１０００℃をこえる温度域ではＨ₂ 雰囲気またはＨ₂ を含有する雰囲気にて、１０００〜１２５０℃の温度域に保持して行うことである。すなわち、４００〜１０００℃の昇温過程では、Ｎ₂ およびＡｒのいずれか一方の雰囲気または両者の混合雰囲気とするのは、低温におけるファイヤライトの分解を抑制することで、高温におけるオリビン生成反応を進行させるためである。
【００４３】
また、１０００℃をこえる温度域ではＨ₂ 雰囲気またはＨ₂ を含有する雰囲気にて行うのは、高温でのＨ₂ 含有雰囲気が、フォルステライト被膜の形成反応を促進させるからであり、併せて、フォルステライト粒子に含有されるＡｌが地鉄との境界側に偏在するようになり、この発明の目的とする下地被膜が形成される。さらに、１０００〜１２５０℃の温度で焼鈍することは、フォルステライト被膜の形成反応を完了させるために必要である。
【００４４】
以下、この発明の方向性電磁鋼板およびその製造方法に関して、その各構成要件について詳述する。
まず、この発明の方向性電磁鋼板の成分組成について延べる。
Ｓｉ：１．５〜７．５％
Ｓｉは、電気抵抗を増加させ鋼板の渦電流損を低減するのに必要な成分であり、この目的のためには１．５％以上含有させる必要があるが、７．５％をこえると加工性が劣化することから、１．５〜７．５％の範囲とする。
【００４５】
Ｍｎ：０．０３〜３．５％
Ｍｎは、Ｓｉと同様に電気抵抗を高め、また製造時の熱間加工性を向上させる、重要な成分である。このためには０．０３％以上含有させることが必要であるが、３．５％をこえて含有させると、γ変態を誘起して磁気特性が劣化することから、０．０３〜３．５％の範囲とする。
【００４６】
また、不純物としては、Ｃを０．００５０％以下、Ｓを０．００２０％以下、Ｎを０．００２０％以下、Ｓｅを０．００２０％以下、Ｏを０．００２０％以下、Ｔｉを０．００３０％以下、Ｂを０．０００５％、Ｎｂを０．００２０％以下に、それぞれ制限することが好ましい。すなわち、これらの元素が鋼板中に含有されると、鋼中での存在形態によっては鋼板のヒステリシス損を増加し鉄損値を劣化させる可能性があるため、それぞれ上記範囲に制限することが好ましい。これらの元素の含有量を制限するには、溶鋼を高純度化することが有効であるが、他の方法として、焼鈍分離剤中のＣａやＳｒ等の含有量を増加させて、最終仕上げ焼鈍時の純化を強化することでも対処できる。
【００４７】
その他、必要により特性向上のための元素を含有させることができる。例えば、Ｓｂ，Ｓｎ，Ｃｕ，Ｃｒ，Ｎｉ，ＧｅおよびＢｉなどは、２次再結晶組織を改善するのに有効な添加成分であり、ヒステリシス損を低減し鉄損を改善する効果がある。これらの他にも公知の添加元素を含有させることが可能である。
【００４８】
さて、この発明で対象とする鋼板は、圧延方向に磁化容易軸＜００１＞を配向させた（１１０）＜００１＞方位や（１００）＜００１＞方位などを主方位とする方向性電磁鋼板であり、その表面には、最終仕上げ焼鈍時に生成されたフォルステライト系被膜からなる下地被膜を有する。このフォルステライト被膜は、鋼板表面層に存在するファイヤライト（Ｆｅ₂ ＳｉＯ₄ ）およびシリカ（ＳｉＯ₂ ）と、鋼板表面に塗布された焼鈍分離剤中のＭｇＯとが、最終仕上げ焼鈍中に次式（１）および（２）に従って反応したものである。
Ｆｅ₂ ＳｉＯ₄ ＋２ＭｇＯ→Ｍｇ₂ ＳｉＯ₄ ＋２ＦｅＯ----（１）
ＳｉＯ₂ ＋２ＭｇＯ→Ｍｇ₂ ＳｉＯ₄ ----（２）
【００４９】
そして、このフォルステライト系の下地被膜において、次の（イ）〜（ハ）が満たされることが、この発明の作用効果を得るために必要である。すなわち、
（イ）下地被膜は大部分がフォルステライト粒子から構成されていること、
（ロ）地鉄と接するフォルステライト粒子内にＡｌが固溶していること、
（ハ）地鉄と接するフォルステライト粒子内において、固溶Ａｌの濃度が地鉄側に向かって増加していること
が必須の構成要件となる。
【００５０】
なお、下地被膜には、２０％未満のＴｉＮ粒子やスピネル（ＭｇＡｌ₂ Ｏ₄ ）粒子を含有することが可能であるが、少なくとも７０％はフォルステライト粒子からなることが必要であり、これにより密着性と鉄損特性に優れた鋼板を得ることができる。
【００５１】
さらに、フォルステライト粒子は、平均結晶粒径が０．０５〜０．５μm であることが、下地被膜の密着性をさらに高めるのに有利である。なぜなら、フォルステライト粒子の平均結晶粒径が０．５μｍを超えると被膜の密着性が低下する傾向を有し、逆に０．０５μｍ未満の場合、結晶粒界密度が増加して、粒界拡散による鋼板の酸化、窒化が起こりやすくなり、いずれの場合も下地被膜の密着性の向上効果を低減する方向に作用するからである。
【００５２】
また、上記下地被膜の地鉄と接するフォルステライト粒子内にＡｌが固溶し、かつ固溶Ａｌの濃度が地鉄と接する側に向かって増加していることが、下地被膜の密着性を高め、鋼板への張力作用を高めるために必要である。これは、Ａｌを含有することによって、フォルステライト結晶粒の格子間隔を増加させ、下地被膜の靱性を損なわず張力作用を増進させることができるからである。
【００５３】
なお、Ａｌの濃度分布については、フォルステライト粒子内部について、電子顕微鏡を用いての微視的領域のＡｌ濃度分析を行うことで評価できる。さらに、Ａｌがフォルステライト粒子への固溶していることの確認は、Ａｌ含有域における電子顕微鏡を用いてのＭｇ，Ｏ，Ｓｉの分析によって成分を、また同じく電子顕微鏡を用いてμ−回折を測定してフォルステライトの結晶系である斜方晶の確認と格子定数とを知ることにて、行うことができる。
【００５４】
次に、このような下地被膜を有する方向性電磁鋼板を製造するための有利な手法について、詳しく説明する。
まず、出発素材の成分について述べる。
Ｃ：０．１０％以下、
Ｃは、含有量が０．１０％をこえると脱炭焼鈍工程において脱炭不良を招き、磁気特性が劣化するため、その含有量を０．１０％以下とする。
【００５５】
Ｓｉ：１．５〜７．５％
Ｓｉは、電気抵抗を増加させ鉄損を低減させるために必須の成分であり、このためには１．５％以上含有させることが必要であるが、７．５％を超えて含有させると加工性が劣化し製品の製造や製品の加工が極めて困難になる。従って、その含有量は１．５〜７．５％の範囲とする。
【００５６】
Ｍｎ：０．０３〜３．５％
Ｍｎは、Ｓｉと同様に電気抵抗を高め、また製造時の熱間加工性を向上させるのに重要な成分である。そのためには０．０３％以上の含有が必要であるが、３．５％をこえて含有するとγ変態を誘起して磁気特性が劣化する。従って、その含有量は０．０３〜３．５％の範囲とする。
【００５７】
鋼中にはこれらの成分の他に、２次再結晶を誘起させるためのインヒビターが必要である。インヒビター形成成分としては、Ａｌ，Ｂ，Ｎ，Ｓ，Ｓｅ，Ｓｂ，Ｓｎ，Ｃｕ，Ｃｒ，Ｎｉ，Ｇｅ，Ｂｉ，Ｔｅ，Ｐｂ，Ｚｎ，Ｉｎ，ＰおよびＶなどから選ばれる１種または２種以上を含有する必要がある。
【００５８】
これらのインヒビター形成成分は、熱延中の鋼中Ｍｎ化合物、Ｃｕ化合物もしくは窒化物として析出してインヒビターとして作用し、鋼板の１次再結晶粒の正常粒成長を抑制する。また、ＳｂやＳｎは、結晶粒界に偏析して上記１次再結晶粒の正常粒成長を抑制する。特に、Ｓ，Ｓｅ，Ａｌ，Ｓｂ，Ｓｎ，Ｃｕ，Ｃｒ，Ｎｉ，ＧｅおよびＢｉは、インヒビターとして良好な２次再結晶組織を得るのに有効であり、これらの中から１種もしくは２種以上を選び、Ｓｂ, Ｂｉにおいては０．０００５〜０．０８０％、Ｃｕ, Ｃｒ, Ｎｉ, ＳｎまたはＧｅにおいては０．００１０〜１．３０％、Ｓ，Ｓｅ，Ａｌにおいては０．０１０〜０．０３５％にて添加することが、高磁束密度かつ低鉄損の方向性電磁鋼板を得るのに好都合である。
【００５９】
上記成分組成に調整された方向性電磁鋼板用スラブは、従来の各種方法によってスラブとされる。すなわち、連続鋳造により通常は２００〜３００ｍｍ厚のスラブとされるが、３０〜１００ｍｍの薄スラブを用いても、この発明の効果に差異はない。薄スラブを用いる場合には、特に熱間圧延の粗圧延を省略することが可能となる。
【００６０】
このようなインヒビター成分を含有する鋼スラブを熱間圧延し、１回もしくは２回以上の冷間圧延で最終板厚とし、１次再結晶焼鈍を施し最終仕上げ焼鈍により磁気特性を得る一連の工程によって、この発明の方向性電磁鋼板が製造される。ここで、磁束密度の向上などの必要に応じて、熱延板焼鈍を施すことができる。
【００６１】
ここで、１次再結晶焼鈍工程において、まず５００℃以上の平均昇温速度を５℃／ｓ以上にて焼鈍温度を７００〜９５０℃の範囲に調整することが必要である。すなわち、５００℃以上の高温領域では鋼板の酸化が進行するが、平均昇温速度が５℃／ｓ未満の場合や焼鈍温度が７００℃未満の場合には、鋼板表面に緻密なシリカのスケールが生成し、その後の処理や雰囲気調整によっても、ファイヤライトが生成しづらく目的のフォルステライト系被膜の形成が不能となる。また、焼鈍温度が９５０℃を超えると、１次再結晶粒が粗大化し、良好な２次再結晶組織が得られなくなる。
【００６２】
さらに、５００℃以上の温度域において、雰囲気のＰ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）を６０秒間以上にわたって０．１５〜０．７５とすることが必要である。すなわち、上述のように５００℃以上の温度域において表面酸化は急激に進行するが、このときファイヤライトを効果的に生成するには、Ｐ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）を６０秒間以上にわたって０．１５〜０．７５とすることが必要である。この条件から外れた場合には、１次再結晶焼鈍板の表層部に十分なファイヤライトが含まれた内部酸化層を生成することができず、この発明の特徴である下地被膜を形成することができない。
【００６３】
ここで、１次再結晶焼鈍に引き続いて、鋼板表面のファイヤライトをシリカとの赤外反射スペクトルの吸光度比：Ａｆ／Ａｓで０．３〜５．０の範囲に分解処理することが、この発明の下地被膜のＡｌの分布をさらに適切にして、より優れた被膜の密着性と鉄損特性を得るために有効である。なお、分解処理には、Ｈ₂ 分圧比の高いガスでファイヤライトを高温で還元処理したり、乾燥中性ガス中で熱処理することによって、ファイヤライトをシリカヘと分解する方法などが用いられる。
【００６４】
また、１次再結晶焼鈍後に鋼板表面に塗布する焼鈍分離剤は、Ａｌ含有物質をＡｌ₂ Ｏ₃ 換算の当量で０．０１〜８．０mass％含有し、かつマグネシアをＭｇＯ換算の当量で７０mass％以上含有することが、肝要である。すなわち、焼鈍分離剤中にマグネシアをＭｇＯ換算の含有量として７０％以上含有させることが、フォルステライトを主成分とする下地被膜を形成させるために有利であり、７０％未満になると、良好なフォルステライトが生成されずに下地被膜の密着性と張力作用が劣化する。次に、Ａｌ含有物質の含有がＡｌ₂ Ｏ₃ 換算の当量で０．０１％未満では、地鉄からフォルステライト粒子へＡｌが侵入せずにスピネル等を生成したり、焼鈍分離剤からフォルステライト粒子へＡｌの侵入がなされず、この発明の目的の下地被膜が形成されない。一方、Ａｌ₂ Ｏ₃ 換算の当量が８．０％をこえると、上記した式（１）や（２）で表されるフォルステライト反応そのものが抑制されるようになり、良好なフォルステライト系下地被膜が形成されない。なお、焼鈍分離剤に含有されるＡｌの形態としては、マグネシア中に固溶するＡｌであっても、その作用に変わりがないことはいうまでもない。
【００６５】
さらに、最終仕上げ焼鈍を、４００〜１０００℃の昇温過程では、Ｎ₂ およびＡｒのいずれか一方の雰囲気または両者の混合雰囲気にて、１０００℃をこえる温度域ではＨ₂ 雰囲気またはＨ₂ を含有する雰囲気にて、１０００〜１２５０℃の温度域に保持して行う必要がある。
すなわち、最終仕上げ焼鈍の４００〜１０００℃の昇温過程は、Ｎ₂ およびＡｒのいずれか一方の雰囲気または両者の混合雰囲気とするのは、低温におけるファイヤライトの分解を抑制することで、高温におけるオリビン生成反応を進行させるためである。また、１０００℃をこえる温度域ではＨ₂ 雰囲気またはＨ₂ を含有する雰囲気とするのは、高温でのＨ₂ 含有雰囲気がフォルステライト被膜形成反応を促進させるからである。これにより、フォルステライト粒子に含有されるＡｌが地鉄との境界側に偏在するようになり、この発明で所期する下地被膜が形成される。また、１０００〜１２５０℃の温度で焼鈍する理由は、この温度域での焼鈍によりフォルステライト被膜形成反応が完了するからである。
【００６６】
上記した製造条件に加えて、１次再結晶焼鈍後かつ２次再結晶前に、鋼中にＮを上限５５０ppm で含有させる、窒化処理を施すことも、この発明の方向性電磁鋼板の特性をより向上させるのに効果的である。すなわち、この処理によって、鋼中のインヒビターの能力が高まり、より磁気特性に優れた方向性電磁綱板を得ることができる。ここで、窒化処理の方法としては、１次再結晶焼鈍に引き続いてアンモニア含有雰囲気中で熱処理を行ってもよいし、焼鈍分離剤としてＴｉＮ、ＦｅＮやＭｎＮなどの窒化物を焼鈍分離剤中に含有させてもよい。
【００６７】
同様に、最終冷間圧延後かつ最終仕上げ焼鈍前または後に、鋼板表面に複数の溝を形成するか、もしくは線状の局部歪を鋼板に導入し、鋼板の磁区を細分化して鉄損を低減する、磁区細分化処理を適用することも可能であり、この処理との併用により、格段に優れた鉄損値を得ることが可能となる。ここで、鋼板表面に線状の局部歪を導入する方法としては、プラズマジェットやレーザー照射を線状に施す方法が、有利に適合する。また、鋼板表面に溝を形成する方法としては、マスキングした状態でエッチング処理を行うことや、突起ロールによって線状の凹みを設けることが、有利に適合する。
【００６８】
最終仕上げ焼鈍後は、必要に応じて絶縁コーティングを塗布焼き付け、さらに平坦化焼鈍を施して製品とする。
【００６９】
【実施例】
実施例１
表２に示すスラブＡの成分組成の溶鋼を連続鋳造で鋳込んで厚み２５０mmのスラブをＡ−１〜Ａ−７まで７本作製し、１１８０℃の温度に３時間保持した後、スラブの幅を４０mm減少させる幅圧下を行い、さらに厚みを２００mmに減厚した後、誘導加熱炉に装入し３０分で１４１０℃まで昇温して１０分間均熱した後、熱間圧延を開始した。熱間圧延は粗圧延で３５ｍｍ厚とし、仕上げ圧延で１．８mmの厚さに仕上げた。
【００７０】
【表２】

【００７１】
その後、各コイルは１１００℃で４０秒間の熱延板焼鈍を施し、ミスト水で３５℃／ｓで冷却した。このときの焼鈍雰囲気は、露点５０℃のプロパン燃焼ガスとし、鋼板表層を脱炭して該表層のＣ含有量を０．００８％に低減した。その後、各コイルは酸洗し、ゼンジマー圧延機で各圧延パス出側温度が１７０〜２５０℃の温間圧延により、０．１９mmの最終板厚に圧延した。次いで、脱脂後、８５０℃で３分間の脱炭焼鈍を施した。その際、５００℃〜８５０℃の昇温速度を２０℃／ｓとした。
【００７２】
各鋼板を脱脂し、１分間の昇温と８５０℃で均熱３分間の脱炭焼鈍を施すに当たり、記号Ａ−１，Ａ−２，Ａ−３およびＡ−４はＰ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．５０の湿水素・窒素雰囲気で全処理を行い、Ａ−５とＡ−６はＰ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．５５の雰囲気で８５０℃昇温後２０秒間まで、その後はＰ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．０１の雰囲気で処理した。また、Ａ−７はＰ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．５０の湿水素・窒素雰囲気で２分間脱炭焼鈍した後、さらに引き続いてＰ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．００５の雰囲気で、１分間焼鈍した。これらの鋼板はいずれもＣ含有量を０．００２％以下まで脱炭し、酸素目付量を０．８〜１．１ｇ／ｍ² に調整した。
【００７３】
その後、マグネシアに５％のＴｉＯ₂ 、２％のＳｒ（０Ｈ）₂ および２％のＳｎＯ₂ を添加した焼鈍分離剤を、鋼板両面に１２ｇ／ｍ² 塗布し、コイル状に巻取ったのち、最終仕上げ焼鈍を施した。ここで、鋼板Ａ−１，Ａ−２，Ａ−３およびＡ−５には、ＡｌをＡｌ₂ Ｏ₃ 換算で０．１％含有するマグネシアを用い、Ａ−４，Ａ−６およびＡ−７には、従来例としてＡｌをＡｌ₂ Ｏ₃ 換算で０．００１％未満含有する純度９７％のマグネシアを用いた。
【００７４】
最終仕上げ焼鈍は、鋼板Ａ−１，Ａ−４，Ａ−５，Ａ−６およびＡ−７について、Ｎ₂ 単独の雰囲気下において３０℃／ｈの昇温速度で８５０℃まで昇温し、引き続き１５時間保持した後、２５％Ｎ₂ と７５％Ｈ₂ の混合雰囲気で１１００℃まで１２℃／ｈの昇温速度で昇温し、以後Ｈ₂ 単独雰囲気で１１５０℃まで昇温して５時間保持し冷却した。
【００７５】
また、鋼板Ａ−２は、８４０℃まで３０℃／ｈの昇温速度で昇温したが、Ｎ₂ 単独雰囲気下で３５０℃まで昇温し、その後１０％Ｈ₂ と９０％のＮ₂ の混合雰囲気で８５０℃まで昇温し、引き続き１５時間保持した後、２５％Ｎ₂ と７５％Ｈ₂ の混合雰囲気で１１００℃まで１２℃／ｈの昇温速度で昇温し、以後Ｈ₂ 単独雰囲気で１１５０℃まで昇温して５時間保持し冷却した。さらに、鋼板Ａ−３は、Ｎ₂ 単独の雰囲気下において３０℃／ｈの昇温速度で８５０℃まで昇温し、引き続き１５時間保持した後１１００℃まで１２℃／ｈの昇温速度で昇温し、以降２５％Ｎ₂ と７５％Ｈ₂ の混合雰囲気で１１５０℃まで昇温して、Ｈ₂ 単独雰囲気に切り替えて５時間保持して冷却した。
【００７６】
これら鋼板のコイルは、最終仕上げ焼鈍の冷却後、未反応分離剤を除去し、コロイダルシリカを含有するリン酸マグネシウムを主成分とする張力絶縁コーティングを塗布し８００℃で焼き付けた。
【００７７】
かくして得られた鋼板について、その被膜外観および鋼板を各種直径の丸棒に巻きつけ被膜が剥離しない丸棒の直径を求める方法で被膜の密着性を評価した。さらに、フォルステライト系被膜の薄膜断面をイオンミリングの技術を用いて準備し、透過電子顕微鏡での被膜粒子断面の観察および分析電子顕微鏡での成分調査を行った。これらの評価および調査結果を表３に示す。
【００７８】
さらに、これらの鋼板の表面にプラズマジェットを間隔５mmで線状に照射し製品とした。各製品より圧延方向に沿って幅１００mmおよび長さ４００mmのＳＳＴ（単板試験）の試験片を採取し、１．７Ｔの磁束密度における鉄損の値Ｗ_17/50 および磁束密度Ｂ₈ を測定した。これらの測定結果を、表３に併せて示す。
【００７９】
【表３】

【００８０】
表３に示すように、この発明に従う成分および下地被膜を有する方向性電磁鋼板の製品Ａ−１は、優れた密着性を示すとともに、極めて低鉄損の磁気特性が得られた。
【００８１】
実施例２
表２に示したスラブＢおよびＣの成分組成の溶鋼を、連続鋳造機で各１２本鋳込み、厚さ２２０mmのスラブとした。鋳込み後の各スラブは、ガス加熱炉に装入して１２００℃に加熱し、その後粗圧延で４５mmとし、仕上げ圧延で２．４mmの板厚まで熱間圧延した。
【００８２】
その後、各コイルは１０００℃まで１５℃／ｓの昇温速度で昇温した後、３０秒間保持しミスト水を噴射し急冷した。このとき、焼鈍雰囲気として空燃比０．９５で露点４５℃の燃焼ガスを用い、鋼板表層を脱炭焼鈍し、そのＣ含有量を０．０２０％に低減した。次いで、酸洗しタンデム圧延機によって最終圧延スタンド出側の板温として最高温度が２５０℃となる温間圧延を行い、最終板厚０．３４mmに仕上げた。
【００８３】
さらに、各鋼板を脱脂後、８２０℃で２分間の脱炭焼鈍を施した。その際、５００℃〜８２０℃の昇温速度は１４℃／ｓとした。焼鈍は、Ｐ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．５５の湿水素・窒素雰囲気とした。酸素目付量は、０．９８〜１．４５ｇ／ｍ² の範囲であり、Ｃ含有量はいずれも０．００２％以下に脱炭されていた。
【００８４】
脱炭焼鈍後、スラブＢの成分からなる鋼板は、４％のＴｉＯ₂ と２％の硫酸ストロンチウムを添加し、残部は純度９７〜９８％のマグネシアからなる焼鈍分離剤を鋼板表面に塗布（鋼板両面で１３ｇ／ｍ² ）して巻き取った。なお、ＭｇＯには、Ａｌ₂ Ｏ₃ に換算して０．００１％〜１５．５％のＡｌを含有する各種類のマグネシアをそれぞれ用いた。また、スラブＣの成分からなる鋼板は、焼鈍分離剤として、４％のＴｉＯ₂ と２％の硫酸ストロンチウムを含有し、マグネシアを５０％から９６％の範囲で含有し、残部をＣａＯとしたものを、各鋼板表面に塗布し巻きとった。ここで、マグネシアとしては、Ａｌ₂ Ｏ₃ に換算して０．２４％のＡｌを含有し、純度９５％のマグネシアを用いた。
【００８５】
その後、各鋼板には、昇温速度３０℃／ｈとし、昇温時８００℃までＮ₂ 単独の雰囲気、その後１０５０℃までは３０％Ｎ₂ と７０％Ｈ₂ の混合雰囲気、以後Ｈ₂ 単独雰囲気で１１８０℃まで昇温後５時間保持する、最終仕上げ焼鈍を施した後、未反応分離剤を除去した。これら鋼板のコイルには、さらに６０％のコロイダルシリカを含有するリン酸アルミニュウムを主成分とする絶縁コーティングを塗布し８００℃で焼き付け製品とした。
【００８６】
かくして得られた鋼板について、その被膜外観および鋼板を各種直径の丸棒に巻きつけ被膜が剥離しない丸棒の直径を求める方法で被膜の密着性を評価した。さらに、フォルステライト系被膜の薄膜断面をイオンミリングの技術を用いて準備し、透過電子顕微鏡での被膜粒子断面の観察および分析電子顕微鏡での成分調査を行った。これらの評価および測定結果の一部を表４に示す。
【００８７】
さらに、各製品より圧延方向に沿ってエプスタインサイズの試験片を切り出し、８００℃で３時間の歪取焼鈍を施した後、１．７Ｔの磁束密度における鉄損の値 W_17/50 および磁束密度Ｂ₈ を測定した。これらの測定結果の一部を、表４に併せて示す。
【００８８】
【表４】

【００８９】
また、焼鈍分離剤中のＡｌ₂ Ｏ₃ に換算したＡｌ含有量の鉄損に及ぼす影響を図１２に、焼鈍分離剤中の純ＭｇＯ換算含有量の鉄損に及ぼす影響を図１３に、それぞれ示す。
【００９０】
図１２および１３に示すように、焼鈍分離剤中のＡｌ₂ Ｏ₃ に換算したＡｌ含有量として０．０１〜８．０、そして焼鈍分離剤中のＭｇＯ換算含有量として７０％以上に規制するのが、鉄損特性の点で有利であることがわかる。
【００９１】
実施例３
表２のスラブＤ〜Ｋで示した成分を有する鋼を溶製し、厚み２２０mmの鋼スラブに連続鋳造で鋳込んだ。これらのスラブは、ガス燃焼炉で表面温度を１２００℃に昇温した後、炉から取り出し表面温度が１１５０℃になるまで冷却し、次に誘導加熱式の加熱炉に装入して１３８０℃に加熱後、粗圧延と仕上げ圧延機での熱間圧延により、２．４mmの熱延コイルとした。
【００９２】
これらのコイルは、２００℃に加熱した後酸洗し、タンデム圧延機によって、記号Ｄの鋼板は０．５５mm厚、その他の鋼板は１．８０mm厚まで冷間圧延した。その後、中間焼鈍として、記号Ｄの鋼板は９７０℃まで１２℃／ｓの速度で昇温し、さらに６０秒間保持した後ジェット水を噴射して３０秒間で冷却する熱処理を、その他の鋼板は１１００℃まで１０℃／ｓの速度で昇温し、さらに６０秒間保持した後ジェット水を噴射して３０秒間で冷却する熱処理を、それぞれ行った。次いで、各コイルは、ゼンジマー圧延機で最高板温度、２２０℃の温間圧延と１５０〜２００℃でのパス間時効を施し、５パスの圧延で０．２２mmの最終板厚に仕上げた。
【００９３】
その後、各コイルには、脱脂後に電解エッチングによって深さ２０μm 、幅１２０μm 、圧延直角方向に伸びた溝を、圧延方向への繰り返し間隔５mmでもって繰り返し形成した。そして、８５０℃で２分間、Ｐ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．５２の湿水素・窒素雰囲気での脱炭焼鈍を施したが、その際、各鋼板を２分割し、５００〜８５０℃での昇温速度を、一方の鋼板は４．０℃／ｓとし、他方の鋼板は１７℃／ｓとした。
【００９４】
その後、Ａｌ₂ Ｏ₃ に換算して０．００２％のＡｌと０．２４％のＣａおよび０．０８％のＢを含有する純度９８％のマグネシアに、７％のＴｉＯ₂ と２％の酸化錫を添加した焼鈍分離剤をコイル表面に塗布し、最終仕上げ焼鈍を施した。
【００９５】
最終仕上げ焼鈍は、昇温速度３５℃／ｈとし、昇温時７５０℃までＮ₂ 単独の雰囲気、その後１１８０℃までは３５％Ｎ₂ と６５％Ｈ₂ の混合雰囲気、以後１１８０℃でＨ₂ 単独雰囲気で５時間保持して行い、その後未反応分離剤を除去した。これらのコイルは、さらに６０％のコロイダルシリカを含有するリン酸マグネシウムを主成分とする絶縁コーティングを塗布し８００℃で焼き付け製品とした。
【００９６】
かくして得られた鋼板について、その被膜外観および鋼板を各種直径の丸棒に巻きつけ被膜が剥離しない丸棒の直径を求める方法で被膜の密着性を評価した。さらに、フォルステライト系被膜の薄膜断面をイオンミリングの技術を用いて準備し、透過電子顕微鏡での被膜粒子断面の観察および分析電顕での成分調査を行った。これらの評価および調査結果を表５に示す。さらに、各製品より圧延方向に沿ってエプスタインサイズの試験片を切り出し８００℃で３時間の歪取焼鈍を施した後、１．７Ｔの磁束密度における鉄損の値Ｗ_17/50 および磁束密度Ｂ₈ を測定した。これらの測定結果も表５に併せて示す。
【００９７】
【表５】

【００９８】
表５より、この発明の製造条件に従って得られた製品は、良好な被膜の密着性および鉄損特性が共に得られていることがわかる。
【００９９】
実施例４
表２のスラブＬ〜Ｎに示した成分を有する鋼を溶製し、厚み７０mmの鋼スラブに連続鋳造で鋳込んだ。これらのスラブは電気加熱式の加熱炉に装入し、記号Ｌのスラブは１３８０℃に、記号ＭおよびＮのスラブは１１８０℃に加熱後、仕上げ圧延機での熱間圧延により２．６mmの熱延コイルとした。
【０１００】
これらのコイルは、５００℃に焼鈍した後酸洗し、タンデム圧延機によって１．９０mmまで冷間圧延した。その後、中間焼鈍として、１０５０℃に加熱し６０秒間保持した後ジェット水を噴射して３０秒間で冷却する熱処理を行った。次いで、各コイルはタンデム圧延機によって０．３４mmの最終板厚まで冷間圧延した。
【０１０１】
各コイルには、脱脂後、８２０℃で２分間の脱炭焼鈍を施したが、その際、５００〜８２０℃の昇温速度を１７℃／ｓとした。焼鈍雰囲気は、Ｐ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．５６の湿水素・窒素雰囲気で行ったが、記号Ｌのコイルについては６分割し、脱炭焼鈍に引き続いて、８８０℃の温度でＰ（Ｈ₂ Ｏ）／Ｐ（Ｈ₂ ）が０．５０、０．２０、０．１０、０．０５、０．０１または０．００４の雰囲気下にて、ファイヤライト分解処理を施した。そして、ファイヤライト分解処理後の鋼板表面の赤外反射スペクトルを測定し、ファイヤライトとシリカとの赤外反射スペクトルの吸光度比：Ａｆ／Ａｓを求めた。これらの値を表６に示す。また、記号Ｍのコイルについては４分割し、脱炭焼鈍に引き続いて、８００℃で１０％のＮＨ₃ 、７０％のＮ₂ 、２０％のＨ₂ の雰囲気で２秒間、１０秒間、２５秒間、３５秒間の窒化処理により、脱炭焼鈍前の鋼中Ｎ含有量：４３ppm に対して、Ｎ含有量をそれぞれ、１４、６８、１８２、２５０ppm さらに増加させた。
【０１０２】
その後、Ａｌ₂ Ｏ₃ に換算して０．１２％のＡｌと０．３５％のＣａおよび０．０４％のＢを含有する純度９７％のマグネシアに、５％のＴｉＯ₂ と２％の酸化錫を添加した、焼鈍分離剤をコイル表面に塗布し、最終仕上げ焼鈍を施した。
【０１０３】
最終仕上げ焼鈍条件は、昇温速度３５℃／ｈとし、昇温時８００℃までＮ₂ 単独の雰囲気、その後１１００℃までは１５％Ｎ₂ と８５％Ｈ₂ の混合雰囲気、以後Ｈ₂ 単独雰囲気で１２００℃、５時間保持する最終仕上げ焼鈍を施し、その後未反応分離剤を除去した。これらのコイルは、さらに５０％のコロイダルシリカを含有するリン酸マグネシウムを主成分とする絶縁コーティングを塗布し、８００℃で焼き付け製品とした。
【０１０４】
かくして得られた鋼板について、その被膜外観および鋼板を各種直径の丸棒に巻きつけ被膜が剥離しない丸棒の直径を求める方法で被膜の密着性を評価した。さらに、フォルステライト系被膜の薄膜断面をイオンミリングの技術を用いて準備し、透過電子顕微鏡での被膜粒子断面の観察および分析電顕での成分調査を行った。これらの結果を表６に示す。また、各製品より圧延方向に沿ってエプスタインサイズの試験片を切り出し８００℃で３時間の歪取焼鈍を施した後、１．７Ｔの磁束密度における鉄損の値Ｗ_17/50 および磁束密度Ｂ₈ を測定した。これらの測定結果を表６に併せて示す。
【０１０５】
【表６】

【０１０６】
表６より、この発明の製造条件に従って得られた製品は、優れた被膜の密着性および鉄損特性が共に得られていることがわかる。
【０１０７】
【発明の効果】
以上詳述したように、この発明によれば、被膜の密着性と鉄損特性が共に優れた方向性電磁鋼板が得られる。
【図面の簡単な説明】
【図１】試料記号（ａ）の鋼板の下地被膜の薄膜断面の電子顕微鏡写真およびμ−回折結果である。
【図２】図１の下地被膜の構造を説明する図である。
【図３】図１の下地被膜の断面の図２に示された１ｓ〜１ｆ間において成分元素分析を行いＡｌの濃度変化をＡｌのカウント数と酸素のカウント数との比：Ｎａ／Ｎｏで表した図である。
【図４】試料記号（ｂ）の鋼板の下地被膜の薄膜断面の電子顕微鏡写真およびμ−回折結果である。
【図５】図４の下地被膜の構造を説明する図である。
【図６】図４の下地被膜の断面の図５に示された２ｓ〜２ｆ間において成分元素分析を行いＡｌの濃度変化をＡｌのカウント数と酸素のカウント数との比：Ｎａ／Ｎｏで表した図である。
【図７】試料記号（ｇ）の鋼板の下地被膜の薄膜断面の電子顕微鏡写真およびμ−回折結果である。
【図８】図７の下地被膜の構造を説明する図である。
【図９】図７の下地被膜の断面の図８に示された３ｓ〜３ｆ間において成分元素分析を行いＡｌの濃度変化をＡｌのカウント数と酸素のカウント数との比：Ｎａ／Ｎｏで表した図である。
【図１０】脱炭焼鈍後の鋼板表面の酸化物であるファイヤライトとシリカを赤外反射スペクトルで測定した結果を示す図である。
【図１１】赤外反射スペクトルから、ファイヤライトおよびシリカの吸光度を算出する方法を示した図である。
【図１２】焼鈍分離剤中のＡｌ₂ Ｏ₃ に換算したＡｌ含有量の鉄損に及ばす影響を示した図である。
【図１３】焼鈍分離剤中のマグネシア換算含有量の鉄損に及ぼす影響を示した図である。
【符号の説明】
１ フォルステライト（Ａｌ非含有部）
２ Ａｌの含有部と非含有部の境界線
３ フォルステライト（Ａｌ含有部）
４ スピネル
５ 樹脂
６ 地鉄
７ フォルステライト上へのＦｅ合金の重なり部分[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grain-oriented electrical steel sheet used for iron cores of transformers and generators, and more particularly to a grain-oriented electrical steel sheet having magnetic properties and film properties suitable for energy saving of a transformer, and a method for manufacturing the same.
[0002]
[Prior art]
A grain-oriented electrical steel sheet containing Si and having a crystal orientation oriented in the (110) [001] orientation or the (100) [001] orientation has excellent soft magnetic properties. Widely used as iron core material. As a characteristic required for this electrical steel sheet, in general, W is a loss when magnetized to 1.7 T at a frequency of 50 Hz._17/50It is particularly important that the iron loss expressed as (W / kg) is low.
[0003]
The grain-oriented electrical steel sheet contains a component called inhibitor in steel, heats the steel slab to dissolve the inhibitor, and then hot-rolls to finely precipitate the inhibitor, which is called secondary recrystallization. The manufacturing process for obtaining the above-mentioned crystal orientation using the above phenomenon is common, and a method using a precipitate such as AlN, MnS, MnSe, CuxS, or CuxSe as an inhibitor and a segregating element such as Sb, Sn, or Te are used. There is a method to use. Through the research of these inhibitors, a grain-oriented electrical steel sheet with better orientation has been developed to reduce iron loss.
[0004]
On the other hand, a technique for reducing the iron loss by applying tension to the steel sheet surface is also widely known. For example, in Japanese Patent Publication No. 56-52117, it is possible to use a tension coating by coating and baking a film having a smaller thermal expansion coefficient than that of a steel sheet. In Japanese Patent Publication No. 56-4150 and Japanese Patent Publication No. 63-35684, A method of smoothing the surface of a grain-oriented electrical steel sheet and depositing a tension coating by ion plating or the like is disclosed. However, the former method has a small effect on reducing iron loss, and the latter technique uses a vacuum and thus has a high cost and has not been industrialized.
[0005]
Further, as a method different from these techniques, a technique for imparting tension to a steel sheet is known, and forsterite (Mg) formed in final finish annealing.₂SiO_Four) Films are also being studied as a way to improve iron loss.
That is, the grain-oriented electrical steel sheet having the final thickness is subjected to primary recrystallization annealing accompanied with decarburization, and then applied and dried with a slurry containing MgO as an annealing separator, and then wound into a coil shape. Apply final finish annealing. At this time, the film formation reaction starts at about 850 ° C. and ends at about 1100 ° C. Originally, the final finish annealing is for the purpose of secondary recrystallization and purification of the steel plate. At this time, the surface layer SiO 2 formed by the primary recrystallization annealing is used.₂And MgO in the annealing separator undergo a solid phase reaction to produce forsterite (Mg₂SiO_Four), A dense film is formed on the surface of the steel sheet.
[0006]
The proper properties of the forsterite film thus formed have been studied for a long time. For example, in Japanese Patent Publication No. 57-34351, the average particle size of forsterite particles is set to 0.7 μm or less to obtain a good forsterite film. A technique for obtaining adhesion of a stellite film is disclosed.
[0007]
In general, in an annealing separator, not only MgO but also TiO is used to improve film properties and magnetic properties.₂, Al₂O_Three, Sb₂O_Three, SrSO_FourIn addition, since other oxides, sulfates, borates, and the like are contained, the formed film is not strictly forsterite. However, since the main part is forsterite, the film is called a forsterite film, a forsterite film or a forsterite-based film, and further, an overcoat is often applied on this film. Also called a coating.
[0008]
As a technique relating to this forsterite-based film, for example, Japanese Patent Laid-Open No. 6-179777 discloses a technique in which Ti or N is contained in the forsterite film, or only forsterite is disclosed in Japanese Patent Laid-Open No. 6-17261. An undercoat composed of oxides containing forsterite and Al (especially a spinel structure) or so-called plural types of oxides comprising forsterite and an oxide containing Al and Si. Techniques for forming are known.
[0009]
[Problems to be solved by the invention]
However, the technique disclosed in Japanese Patent Laid-Open No. Hei 6-179777 merely controls the ratio of Ti and N in the coating, thereby suppressing the penetration of Ti into the steel sheet and suppressing the deterioration of iron loss. It does not actively improve the iron loss characteristics.
[0010]
On the other hand, the undercoat disclosed in JP-A-6-17261 is particularly spinel (MgA1).₂O_Four) And forsterite, and is characterized in that the spinel is located on the Fe base side relative to the forsterite as detected by glow discharge spectroscopy (GDS). . However, when a tension coating is applied and baked on the steel sheet surface, the adhesion of the film is inferior, and in the microscopic area, the film peels off, often resulting in significant deterioration of iron loss characteristics. .
[0011]
Japanese Patent Application Laid-Open No. 10-121213 discloses that in a forsterite film, Al is contained in steel, a Ti compound and B are contained in an annealing separator, and an atmosphere of final finish annealing is adjusted. Has disclosed a technique in which an oxide or nitride of Al, Ti, and B is contained in this film. Even in this technique, the film is peeled off in a microscopic region, as in Japanese Patent Laid-Open No. 6-17261. It becomes a problem.
As described above, the conventional technique for improving the undercoat has not yet completed the production technology of the intended low iron loss grain-oriented electrical steel sheet.
[0012]
Therefore, the present invention solves the above-mentioned problems in the prior art, and develops a stable forsterite-based coating that has a strong tension-imparting action and good adhesion to the steel sheet, and the coating properties and iron loss. The purpose is to propose a grain-oriented electrical steel sheet with excellent characteristics and its manufacturing technology.
[0013]
[Means for Solving the Problems]
The inventors have studied in detail a forsterite-based film having good adhesion to a directional electromagnetic steel sheet and a strong tension imparting action, so that Al is dissolved in the crystal particles, and the amount of dissolved Al By increasing the amount of steel toward the steel plate base, it was found that the above problems could be advantageously solved, and the present invention was completed based on this finding.
[0014]
  That is, the gist of the present invention is as follows.
  (1) Si: 1.5 to 7.5 mass% and Mn: 0.03 to 3.5 mass%,Having a component composition of the balance Fe and inevitable impurities,Generated on the surface during final finish annealingAt least 70% composed of forsterite particlesIn the grain-oriented electrical steel sheet having an undercoat, the undercoat is,steelContact with the steel plateallA grain-oriented electrical steel sheet, characterized in that Al is dissolved in forsterite particles and the concentration of solid solution Al in the forsterite particles in contact with the ground iron increases toward the ground iron side.
[0015]
  (2) In (1) above,As a component, one or more selected from Sb, Sn, Cu, Cr, Ni, Ge and Bi are used, and 0.005 to 0.080 for Sb and Bi, respectively. mass %, Cu, Cr, Ni, Sn and Ge are 0.0010 to 1.30, respectively. mass A grain-oriented electrical steel sheet characterized by being contained in%.
  (3) the above (1) Or (2) InAbout the component of a steel plate, C: 0.0050 mass% or less, S: 0.0020 mass% or less, N: 0.0020 mass% or less, Se: 0.0020 mass% or less, O: 0.0020 mass% or less, Ti: 0.0030 mass % Or less, B: 0.0005 mass% and Nb: 0.0020 mass% or less.
[0016]
(Four)the above (1) , (2) Or (3) InThe grain oriented electrical steel sheet, wherein the forsterite particles have an average crystal grain size of 0.05 to 0.5 μm.
[0017]
(5) C: 0.10 mass% or less, Si: 1.5 to 7.5 mass% and Mn: 0.03 to 3.50 mass%, S, Se, Al, Sb, Sn, Cu, Cr, Ni, One or more selected from Ge and Bi,Sb and Bi are 0.0005 to 0.080. mass %, Cu, Cr, Ni, Sn and Ge are 0.0010 to 1.30. mass %, S, Se and Al are from 0.010 to 0.035. mass % Content, the composition of the remaining Fe and inevitable impuritiesThe steel slab is hot-rolled and the final thickness is obtained by one or more cold rollings. After the primary recrystallization annealing, an annealing separator is applied to the steel plate surface, and then the secondary recrystallization annealing and In producing a grain-oriented electrical steel sheet through a series of processes, the final finishing annealing consisting of purification annealing is performed.
  The primary recrystallization annealing is performed by adjusting the annealing temperature to a range of 700 to 950 ° C. at an average temperature increase rate of 500 ° C. or more at 5 ° C./s or more, and in the temperature range of 500 ° C. or more. Ratio of hydrogen partial pressure to pressure P (H₂ O) / P (H₂ ) At 0.15-0.75 over 60 seconds,
  Thereafter, the Al-containing material is changed to Al.₂ O_Three An annealing separator containing 0.01 to 8.0 mass% in terms of equivalent content in terms of conversion and containing 70 mass% or more in terms of equivalent content of magnesia in terms of MgO is applied to the steel sheet surface,
  Next, final finish annealing is performed at a temperature rising process of 400 to 1000 ° C.₂ In a temperature range exceeding 1000 ° C. in either one of Ar and Ar or a mixed atmosphere of both, H₂ Atmosphere or H₂ The65% or moreA method for producing a grain-oriented electrical steel sheet, which is carried out in a contained atmosphere in a temperature range of 1000 to 1250 ° C.
[0018]
(6) the above (Five) InFollowing the primary recrystallization annealing,H that can reduce firelite ₂ By reducing with a gas that has a partial pressure ratio and temperature, or by heat treatment in a dry neutral gas,A method for producing a grain-oriented electrical steel sheet, comprising subjecting the firelite on the steel sheet surface to decomposition treatment in a range of absorbance ratio Af / As: 0.3 to 5.0 of infrared reflection spectrum with silica.
[0020]
  (7) TopRecord (In 5) or (6), after the primary recrystallization annealing and before the secondary recrystallization annealing, N is added to the steel in an upper limit of 550 ppm, and the magnetic characteristics and film characteristics are characterized by performing nitriding treatment. An excellent method for producing grain-oriented electrical steel sheets.
[0021]
  (8) TopRecord (5) In (6) or (7), after the final cold rolling and before or after the final finish annealing, a plurality of grooves are formed on the steel plate surface, or linear local strain is introduced into the steel plate. A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Next, the experimental results that led to the present invention will be described in detail.
C: 0.075 mass% (hereinafter simply expressed as%), Si: 3.25%, Mn: 0.07%, Se: 0.015%, Sb: 0.025%, Al: 0.018% and A silicon steel slab having a thickness of 215 mm containing N: 0.0065% was finished into a hot-rolled sheet having a thickness of 2.2 mm by hot rolling.
[0023]
Next, the hot-rolled sheet was subjected to hot-rolled sheet annealing at 1000 ° C. for 1 minute, then rapidly cooled by spraying mist water, pickled, rolled to an intermediate thickness of 1.5 mm, and further to 1100 ° C., After intermediate annealing for 40 seconds, mist water was sprayed to quench the steel, and then a steel plate having a thickness of 0.22 mm was formed by cold rolling.
[0024]
When this steel sheet is degreased and subjected to decarburization annealing at 850 ° C. and soaking for 3 minutes at 850 ° C., the steel sheet is subjected to steel sheets (a), (b), (c), (d), (e) , (F) and (g), the steel plates (a), (b), (c) and (d) are the ratio of the hydrogen partial pressure to the water vapor partial pressure {hereinafter referred to simply as P (H₂O) / P (H₂)} Is 0.48 in a wet hydrogen / nitrogen atmosphere, and the steel plates (e) and (f) are P (H₂O) / P (H₂) Is 0.55, and then P (H₂O) / P (H₂) In an atmosphere of 0.01. The remaining steel plate (g) is P (H₂O) / P (H₂) Was decarburized and annealed in a wet hydrogen / nitrogen atmosphere of 0.48 for 2 minutes, followed by P (H₂O) / P (H₂): Annealed at 0.005 for 1 minute. All of these steel plates are decarburized to a C content of 0.002% or less, and the oxygen basis weight is 0.8 to 1.1 g / m.²Met.
[0025]
Then 5% TiO in magnesia₂And 2% Sr (OH)₂An annealing separator added with 20g / m on both sides of the steel plate²It was applied, wound into a coil shape, and subjected to final finish annealing. For steel plates (a), (b), (c) and (e), Al is Al.₂O_ThreeMagnesia containing 0.2% in terms of conversion is used, and steel plates (d), (f) and (g) are made of Al as a conventional method.₂O_ThreeMagnesia containing less than 0.001% in terms of conversion was used.
[0026]
Final finish annealing is performed for N (steel plates (a), (d), (e), (f) and (g)).₂In a single atmosphere, the temperature was raised to 840 ° C. at a rate of 30 ° C./h and held for 20 hours, and then 25% N₂And 75% H₂In a mixed atmosphere, the temperature was raised to 1050 ° C. at a rate of 12 ° C./h, and thereafter H₂The temperature was raised to 1200 ° C. in a single atmosphere, held for 5 hours, and then cooled. When the temperature of the steel plate (b) is increased to 840 ° C. at a temperature increase rate of 30 ° C./h, N₂Raise the temperature to 350 ° C in a single atmosphere, then 10% H₂And 90% N₂In a mixed atmosphere, the temperature was raised to 840 ° C. and held for 20 hours, and then 25% N₂And 75% H₂In a mixed atmosphere, the temperature was raised to 1050 ° C. at a rate of 12 ° C./h, and thereafter H₂The temperature was raised to 1200 ° C. in a single atmosphere, held for 5 hours, and then cooled. Furthermore, the steel plate (c) is N₂In a single atmosphere, the temperature was increased to 840 ° C. at a temperature increase rate of 30 ° C./h, then held for 20 hours, then increased to 1050 ° C. at a temperature increase rate of 12 ° C./h, and thereafter 25% N₂And 75% H₂The temperature was raised to 1200 ° C in a mixed atmosphere of₂After switching to a single atmosphere and holding for 5 hours, it was cooled.
[0027]
After cooling the final finish annealing, these steel plates (coiled) are removed from the unreacted separating agent, and after applying a tensile insulating coating mainly composed of magnesium phosphate containing silica and baking at 800 ° C., Its magnetic properties were measured. Further, the adhesion of the coating film was evaluated by a method of obtaining the coating film appearance of the steel sheet and the diameter of the round bar where the steel sheet was wound around a round bar of various diameters and the coating film was not peeled off. Furthermore, a thin film cross-section of the forsterite-based coating was prepared using an ion milling technique, and the cross-section of the coating particle was observed with a transmission electron microscope and the component was examined with an analytical electron microscope. Further, forsterite particles were observed from the surface of each undercoat film by the replica method, and the average particle diameter was determined. Table 1 shows the results of these investigations.
[0028]
[Table 1]

[0029]
From Table 1, it can be seen that the grain-oriented electrical steel sheet (a) is superior in coating appearance, coating adhesion and iron loss value. Therefore, in order to investigate this reason, thin film cross-section samples of the base coating of various grain-oriented electrical steel sheets were examined with an electron microscope. That is, as for the undercoat of the steel sheet (a), as shown in FIG. 1, an electron microscope photograph and μ-diffraction (microfraction) are shown in FIG. 2, an explanatory diagram thereof is shown in FIG. 2, and an element concentration analysis diagram is shown in FIG. It can be seen that the undercoat is composed only of forsterite particles, and a region containing a part of Al in the forsterite particles exists in contact with the Fe low alloy substrate. In FIG. 2, reference numeral 1 is forsterite (Al-free portion), 2 is a boundary between an Al-containing portion and an Al-free portion, 3 is forsterite (Al-containing portion), 5 is a resin for fixing a film, 6 is the ground iron, and 7 is the overlap portion of the Fe alloy on the forsterite.
[0030]
Here, the elemental analysis is performed on the region of 1s to 1f in FIG. 2, and the count number of Al: Na, Mg count number: Nm and Si count number: Ns is the oxygen count number: No. For each of the divided values: Na / No, Nm / No, and Ns / No, the change in the film thickness direction is shown in FIG. From FIG. 3, forsterite (Mg₂SiO_Four) It can be seen that there is a region containing a part of Al in the particles, the region containing Al is in contact with the ground iron, and the concentration of Al increases toward the ground iron. Incidentally, the μ-diffraction shown in FIG. 1 is a diffraction pattern in a region containing Al at a high concentration, but is orthorhombic, and it is forsterite from its lattice constant that the diffraction pattern is analyzed. It was confirmed from.
[0031]
On the other hand, the undercoats of the steel plates (b), (c), (d) and (e) having inferior properties are composed only of forsterite particles but do not contain Al. For example, a forsterite-based coating on a steel plate (b) is composed of only forsterite particles as shown in FIG. 4 and an explanatory view thereof in FIG. The particles do not contain Al as shown in FIG.
[0032]
The steel plates (f) and (g), which are similarly inferior in properties, are made of two types of oxides, forsterite particles and spinel particles containing Al, similar to those recognized in the prior art. For example, for a forsterite-based film of steel sheet (g), as shown in FIG. 7, a photograph and μ-diffraction of the steel microscope are shown in FIG. 7 and an explanatory diagram thereof is shown in FIG. As shown in FIG. 9, Al is not contained in the forsterite particles, and the concentration of Al in the spinel particles is constant.
[0033]
The above-described microscopic structure of the undercoating film and the fact that this structure is related to the properties of the undercoating film have not been known so far, and are new findings obtained from this experiment.
[0034]
Next, the results of examining the mechanism by which the above-described change in the microscopic film structure affects the magnetic properties of the steel sheet will be described.
The forsterite film exerts tension on the steel sheet and, at the same time, receives a strong compressive stress from the steel sheet as a reaction. Here, if there is a hard material with high Young's modulus such as spinel between the forsterite particles and the steel plate, it is expected that the tension action on the steel plate will work more strongly, but in fact, on the contrary, Due to the presence of such a hard substance, the toughness of the forsterite film, which is a ceramic, is deteriorated, the film is easily broken, and the film is peeled off in a microscopic region. As a result, the forsterite film cannot effectively apply tension to the steel sheet, and the tension action of the film becomes non-uniform, and iron loss increases due to increase in eddy current loss and hysteresis loss, resulting in magnetic properties. Deteriorates.
[0035]
On the other hand, in the new coating in which forsterite particles contain Al, the toughness of the coating is not impaired, and the lattice spacing of the forsterite crystals increases as the Al content increases toward the ground iron. This has been confirmed by electron beam μ-diffraction, and these changes result in a stronger tension effect on the steel. In other words, the undercoat of the steel sheet (a) can be said to be a film having a kind of microscopic tilt function. As described above, the fact that the forsterite particles contain Al and that the Al-containing region is in a position in contact with the base iron, and that the concentration of Al increases toward the base iron, the base of the product of the steel plate (a) This is a characteristic of the film, which is a factor that markedly improved the adhesion of the film and also improved the magnetic properties. Furthermore, because the adhesion between the coating and the steel sheet becomes strong, the tension of forsterite and the tension coating applied on it is effectively transmitted to the steel sheet, and the iron loss of the grain-oriented electrical steel sheet is improved. It is estimated to be.
[0036]
Incidentally, the average particle size of the forsterite particles of the undercoat of the steel plates (a) to (g) is 0.7 μm or less, and in the steel plate (a), the average particle size tends to be particularly small. This did not improve the adhesion of the coating.
[0037]
Next, a method for forming forsterite particles containing Al like the steel plate (a) will be described in detail.
That is, in order to obtain the forsterite-based film according to the present invention, silica (SiO 2) is used as an oxide generated in the steel sheet surface layer after the primary recrystallization annealing.₂) As well as firelite (Fe₂SiO_Four) And the presence of a trace amount of an Al-containing substance in the annealing separator. This firelite reacts with MgO in the course of the film formation reaction to react with olivine {(Fe, Mg)₂SiO_Four}, And finally forsterite (Mg₂SiO_FourHowever, the control of this reaction process is extremely important. By controlling the reaction time correctly, the Al component in the annealing separator and the Al present in the steel sheet are simultaneously contained in the forsterite particles. Can also be effectively incorporated into the forsterite particles.
[0038]
In order to control this reaction time, it is necessary to contain Al in the annealing separator containing a large amount of MgO as a reaction product, and the content is Al.₂O_ThreeConverted to 0.01 to 8.0%.
[0039]
Further, control of the atmospheric gas in the final finish annealing is important as in the primary recrystallization annealing. That is, first, in order to generate an appropriate amount of firelite on the surface of the steel sheet after the primary recrystallization annealing, the primary recrystallization annealing is performed at an average temperature increase rate of 500 ° C. or more at 5 ° C./s or more. The annealing temperature is adjusted in the range of 700 to 950 ° C. and at least in the temperature range of 500 ° C. or higher, the P (H₂O) / P (H₂) Is performed at 0.15 to 0.75 for 60 seconds or more. In addition, firelite is an oxide that is formed on the surface side of the steel sheet more than silica, and after it is formed in the above atmosphere, it may be converted to silica by, for example, reduction treatment. If not reduced, the technique of the present invention is fully applicable and the objective is achieved by the remaining firelite.
[0040]
In particular, the firelite present on the steel sheet surface is olivine {(Fe, Mg)₂SiO_Four} Important for the formation reaction, the peak position of firelite (980 cm) in the infrared reflection spectrum of the steel sheet shown in FIG.^-1) And silica peak position (1240cm^-1), And the ratio of the absorbance of firelite: Af and the absorbance of silica: As calculated from the calculation method shown in FIG. 11 is within the range of 0.3 to 5.0. By means of this, a further excellent undercoat can be obtained.
[0041]
As a second requirement for forming the undercoat of the present invention, after primary recrystallization annealing, pure MgO is contained at 70 to 97% and Al-containing material or magnesia contains Al.₂O_ThreeIt is to apply an annealing separator containing Al in an amount of 0.01 to 8.0% in terms of. As a result, good forsterite particles are generated, and at the same time, Al supplied from the annealing separator and the ground iron is taken into the forsterite particles.
[0042]
Furthermore, as the third essential requirement, final finish annealing is performed in the temperature raising process at 400 to 1000 ° C.₂In a temperature range exceeding 1000 ° C. in either one of Ar and Ar or a mixed atmosphere of both, H₂Atmosphere or H₂It is to carry out by maintaining in a temperature range of 1000 to 1250 ° C. in an atmosphere containing That is, in the temperature rising process of 400 to 1000 ° C., N₂The reason why the atmosphere of either one of Ar and Ar or a mixed atmosphere thereof is to promote the olivine production reaction at a high temperature by suppressing the decomposition of firelite at a low temperature.
[0043]
In the temperature range exceeding 1000 ° C, H₂Atmosphere or H₂Is carried out in an atmosphere containing hydrogen at high temperatures.₂This is because the contained atmosphere promotes the formation reaction of the forsterite coating, and at the same time, Al contained in the forsterite particles is unevenly distributed on the boundary side with the ground iron. Is formed. Furthermore, annealing at a temperature of 1000 to 1250 ° C. is necessary to complete the forsterite film formation reaction.
[0044]
Hereinafter, each component requirement is explained in full detail about the grain-oriented electrical steel sheet of this invention, and its manufacturing method.
First, it extends about the component composition of the grain-oriented electrical steel sheet of this invention.
Si: 1.5 to 7.5%
Si is a component necessary for increasing the electrical resistance and reducing the eddy current loss of the steel sheet. For this purpose, it is necessary to contain 1.5% or more, but if it exceeds 7.5%, it is processed. Since the property deteriorates, the range of 1.5 to 7.5% is set.
[0045]
Mn: 0.03 to 3.5%
Mn, like Si, is an important component that increases electrical resistance and improves hot workability during production. For this purpose, it is necessary to contain 0.03% or more. However, if more than 3.5% is contained, the gamma transformation is induced and the magnetic properties are deteriorated. % Range.
[0046]
As impurities, C is 0.0050% or less, S is 0.0020% or less, N is 0.0020% or less, Se is 0.0020% or less, O is 0.0020% or less, and Ti is 0.00. It is preferable to limit to 0030% or less, B to 0.0005%, and Nb to 0.0020% or less, respectively. That is, when these elements are contained in the steel sheet, depending on the form present in the steel, there is a possibility that the hysteresis loss of the steel sheet is increased and the iron loss value is deteriorated. . In order to limit the content of these elements, it is effective to refine the molten steel, but as another method, the final finish annealing is performed by increasing the content of Ca, Sr, etc. in the annealing separator. It can also be dealt with by strengthening the purification of time.
[0047]
In addition, if necessary, an element for improving characteristics can be contained. For example, Sb, Sn, Cu, Cr, Ni, Ge, Bi and the like are additive components effective for improving the secondary recrystallization structure, and have the effect of reducing hysteresis loss and improving iron loss. In addition to these, it is possible to contain known additive elements.
[0048]
The steel sheet that is the subject of the present invention is a grain-oriented electrical steel sheet having a main orientation of the (110) <001> orientation or the (100) <001> orientation with the easy magnetization axis <001> oriented in the rolling direction. On its surface, it has a base coating composed of a forsterite-based coating produced during final finish annealing. This forsterite film is made of firelite (Fe₂SiO_Four) And silica (SiO₂) And MgO in the annealing separator applied to the surface of the steel sheet react according to the following formulas (1) and (2) during the final finish annealing.
Fe₂SiO_Four+ 2MgO → Mg₂SiO_Four+ 2FeO ---- (1)
SiO₂+ 2MgO → Mg₂SiO_Four                ---- (2)
[0049]
In order to obtain the operational effects of the present invention, the forsterite-based undercoating must satisfy the following (A) to (C). That is,
(B) The undercoat is mostly composed of forsterite particles,
(B) Al is dissolved in forsterite particles in contact with the iron
(C) In the forsterite particles in contact with the steel, the concentration of solute Al increases toward the steel.
Is an essential component.
[0050]
The undercoating is less than 20% TiN particles and spinel (MgAl₂O_Four) Particles can be contained, but at least 70% of the particles must be made of forsterite particles, whereby a steel sheet having excellent adhesion and iron loss characteristics can be obtained.
[0051]
Further, the forsterite particles have an average crystal grain size of 0.05 to 0.5 μm, which is advantageous for further improving the adhesion of the undercoat. This is because when the average crystal grain size of the forsterite particles exceeds 0.5 μm, the adhesion of the coating tends to decrease, and conversely, when it is less than 0.05 μm, the grain boundary density increases and the grain boundary diffusion This is because oxidation and nitridation of the steel sheet are likely to occur due to the above, and in either case, the effect of improving the adhesion of the undercoat is reduced.
[0052]
In addition, Al is solid-solved in the forsterite particles in contact with the base iron of the base coat, and the concentration of the solid solution Al increases toward the side in contact with the base iron, which improves the adhesion of the base coat. It is necessary to increase the tension action on the steel sheet. This is because the inclusion of Al can increase the lattice spacing of forsterite crystal grains and enhance the tension action without impairing the toughness of the undercoat.
[0053]
The Al concentration distribution can be evaluated by performing Al concentration analysis in a microscopic region using an electron microscope inside the forsterite particles. Furthermore, it is confirmed that Al is dissolved in the forsterite particles by confirming the components by analyzing Mg, O, Si using an electron microscope in the Al-containing region, and also using the electron microscope. This can be done by measuring and measuring the orthorhombic crystal, which is a forsterite crystal system, and knowing the lattice constant.
[0054]
Next, an advantageous technique for producing a grain-oriented electrical steel sheet having such a base coating will be described in detail.
First, the components of the starting material will be described.
C: 0.10% or less,
If the content exceeds 0.10%, decarburization failure occurs in the decarburization annealing step and the magnetic properties deteriorate, so the content is made 0.10% or less.
[0055]
Si: 1.5 to 7.5%
Si is an essential component for increasing electrical resistance and reducing iron loss. For this purpose, it is necessary to contain 1.5% or more, but if it exceeds 7.5%, it is processed. As a result, the production and processing of the product become extremely difficult. Therefore, the content is in the range of 1.5 to 7.5%.
[0056]
Mn: 0.03 to 3.5%
Mn, like Si, is an important component for increasing electrical resistance and improving hot workability during production. For this purpose, a content of 0.03% or more is necessary. However, if the content exceeds 3.5%, the γ transformation is induced to deteriorate the magnetic properties. Therefore, the content is made 0.03 to 3.5% of range.
[0057]
In addition to these components, an inhibitor for inducing secondary recrystallization is necessary in steel. As the inhibitor forming component, one or two selected from Al, B, N, S, Se, Sb, Sn, Cu, Cr, Ni, Ge, Bi, Te, Pb, Zn, In, P, V, and the like. It is necessary to contain the above.
[0058]
These inhibitor-forming components precipitate as Mn compounds, Cu compounds or nitrides in hot rolled steel and act as inhibitors, thereby suppressing normal grain growth of primary recrystallized grains in the steel sheet. Moreover, Sb and Sn segregate at the crystal grain boundary and suppress the normal grain growth of the primary recrystallized grains. In particular, S, Se, Al, Sb, Sn, Cu, Cr, Ni, Ge, and Bi are effective for obtaining a good secondary recrystallized structure as an inhibitor, and one or more of these are effective. 0.005 to 0.080% for Sb and Bi, 0.0010 to 1.30% for Cu, Cr, Ni, Sn, and Ge, and 0.010 to 0. 0 for S, Se, and Al. Addition at 035% is advantageous for obtaining a grain-oriented electrical steel sheet having high magnetic flux density and low iron loss.
[0059]
The slab for grain-oriented electrical steel sheets adjusted to the above component composition is made into a slab by various conventional methods. In other words, the slab is usually 200 to 300 mm thick by continuous casting, but even if a thin slab of 30 to 100 mm is used, there is no difference in the effect of the present invention. When a thin slab is used, it is possible to omit the rough rolling of hot rolling.
[0060]
A series of steps in which a steel slab containing such an inhibitor component is hot-rolled, made into a final sheet thickness by one or more cold rollings, subjected to primary recrystallization annealing, and magnetic properties are obtained by final finishing annealing. Thus, the grain-oriented electrical steel sheet according to the present invention is manufactured. Here, hot-rolled sheet annealing can be performed as necessary, such as improvement of magnetic flux density.
[0061]
Here, in the primary recrystallization annealing step, it is necessary to first adjust the annealing temperature to a range of 700 to 950 ° C. at an average temperature rising rate of 500 ° C. or higher at 5 ° C./s or higher. That is, the oxidation of the steel sheet proceeds in a high temperature region of 500 ° C. or higher, but when the average heating rate is less than 5 ° C./s or when the annealing temperature is less than 700 ° C., a dense silica scale is formed on the steel plate surface. Even if it produces | generates and subsequent process and atmosphere adjustment, formation of the target forsterite type | system | group film | membrane which does not produce | generate a firelite easily becomes impossible. On the other hand, when the annealing temperature exceeds 950 ° C., the primary recrystallized grains are coarsened and a good secondary recrystallized structure cannot be obtained.
[0062]
Furthermore, in the temperature range of 500 ° C. or higher, the atmosphere P (H₂O) / P (H₂) Must be 0.15 to 0.75 for 60 seconds or more. That is, as described above, the surface oxidation proceeds rapidly in the temperature range of 500 ° C. or more. At this time, in order to effectively generate the firelite, P (H₂O) / P (H₂) Must be 0.15 to 0.75 for 60 seconds or more. If this condition is not met, an internal oxide layer containing sufficient firelite in the surface layer portion of the primary recrystallization annealed plate cannot be formed, and a base coating that is a feature of the present invention is formed. I can't.
[0063]
Here, following the primary recrystallization annealing, the firelite on the steel sheet surface is decomposed into a range of 0.3 to 5.0 at an absorbance ratio of Af / As of the infrared reflection spectrum with silica: This is effective for making the Al distribution of the undercoating of the present invention more appropriate and obtaining better coating adhesion and iron loss characteristics. In the decomposition process, H₂A method of decomposing firelite into silica by reducing the firelite with a gas having a high partial pressure ratio at a high temperature or heat-treating it in a dry neutral gas is used.
[0064]
In addition, the annealing separator applied to the steel sheet surface after the primary recrystallization annealing is an Al-containing substance.₂O_ThreeIt is important to contain 0.01 to 8.0 mass% in terms of equivalent and to contain 70 mass% or more of magnesia in terms of MgO equivalent. That is, it is advantageous to form magnesia in the annealing separator in an amount of 70% or more in terms of MgO in order to form a base film mainly composed of forsterite. Without the formation of stellite, the adhesion and tension action of the undercoat are deteriorated. Next, the content of Al-containing material is Al₂O_ThreeIf the equivalent in terms of less than 0.01%, Al does not enter the forsterite particles from the base iron, and spinel or the like is not generated, or Al does not enter the forsterite particles from the annealing separator. No undercoat is formed. On the other hand, Al₂O_ThreeWhen the equivalent equivalent exceeds 8.0%, the forsterite reaction itself represented by the above formulas (1) and (2) is suppressed, and a good forsterite-based undercoat is not formed. In addition, as a form of Al contained in the annealing separator, it is needless to say that even if it is Al dissolved in magnesia, its action is not changed.
[0065]
Furthermore, the final finish annealing is performed at a temperature rising process of 400 to 1000 ° C. with N₂In a temperature range exceeding 1000 ° C. in either one of Ar and Ar or a mixed atmosphere of both, H₂Atmosphere or H₂It is necessary to carry out by holding in a temperature range of 1000 to 1250 ° C. in an atmosphere containing
That is, the temperature raising process at 400 to 1000 ° C. in the final finish annealing is N₂The reason why the atmosphere of either one of Ar and Ar or a mixed atmosphere thereof is to promote the olivine production reaction at a high temperature by suppressing the decomposition of firelite at a low temperature. In the temperature range exceeding 1000 ° C, H₂Atmosphere or H₂The atmosphere containing H is H at a high temperature.₂This is because the contained atmosphere promotes the forsterite film formation reaction. As a result, Al contained in the forsterite particles is unevenly distributed on the boundary side with the base iron, and the base coating film expected in the present invention is formed. The reason for annealing at a temperature of 1000 to 1250 ° C. is that the forsterite film formation reaction is completed by annealing in this temperature range.
[0066]
In addition to the manufacturing conditions described above, after the primary recrystallization annealing and before the secondary recrystallization, a nitriding treatment in which N is contained in the steel at an upper limit of 550 ppm can also be performed. It is effective to improve. That is, by this treatment, the ability of the inhibitor in the steel is increased, and a directional electromagnetic steel sheet having more excellent magnetic properties can be obtained. Here, as a method of nitriding treatment, heat treatment may be performed in an ammonia-containing atmosphere subsequent to the primary recrystallization annealing, and nitrides such as TiN, FeN, and MnN are used as the annealing separator in the annealing separator. You may make it contain.
[0067]
Similarly, after final cold rolling and before or after final finish annealing, multiple grooves are formed on the steel sheet surface, or linear local strain is introduced into the steel sheet, and the magnetic domain of the steel sheet is subdivided to reduce iron loss. It is also possible to apply a magnetic domain subdivision process, and by using this process together, it is possible to obtain a significantly superior iron loss value. Here, as a method for introducing a linear local strain on the surface of the steel plate, a method in which a plasma jet or laser irradiation is linearly applied is advantageously suitable. Moreover, as a method of forming a groove on the surface of the steel plate, it is advantageous to perform an etching process in a masked state or to provide a linear recess by a protruding roll.
[0068]
After the final finish annealing, an insulating coating is applied and baked as necessary, and further flattened annealing is performed to obtain a product.
[0069]
【Example】
Example 1
The molten steel having the component composition of slab A shown in Table 2 was cast by continuous casting to prepare seven slabs having a thickness of 250 mm from A-1 to A-7, held at a temperature of 1180 ° C. for 3 hours, and then the width of the slab. The thickness was reduced to 40 mm, the thickness was further reduced to 200 mm, and then charged into an induction heating furnace, heated to 1410 ° C. in 30 minutes, soaked for 10 minutes, and then hot rolling was started. Hot rolling was rough rolling to a thickness of 35 mm, and finish rolling to a thickness of 1.8 mm.
[0070]
[Table 2]

[0071]
Thereafter, each coil was subjected to hot-rolled sheet annealing at 1100 ° C. for 40 seconds and cooled at 35 ° C./s with mist water. The annealing atmosphere at this time was propane combustion gas having a dew point of 50 ° C., and the steel sheet surface layer was decarburized to reduce the C content of the surface layer to 0.008%. Thereafter, each coil was pickled and rolled to a final thickness of 0.19 mm by warm rolling at a rolling pass outlet temperature of 170 to 250 ° C. using a Zenzimer rolling mill. Then, after degreasing, decarburization annealing was performed at 850 ° C. for 3 minutes. In that case, the temperature increase rate of 500 degreeC-850 degreeC was 20 degreeC / s.
[0072]
When each steel plate was degreased and subjected to decarburization annealing at 850 ° C. and soaking for 3 minutes at 850 ° C., the symbols A-1, A-2, A-3 and A-4 represent P (H₂O) / P (H₂) Is 0.50 in a wet hydrogen / nitrogen atmosphere, and A-5 and A-6 are P (H₂O) / P (H₂) In an atmosphere of 0.55 up to 20 seconds after heating at 850 ° C., then P (H₂O) / P (H₂) In an atmosphere of 0.01. A-7 is P (H₂O) / P (H₂) Was decarburized and annealed in a wet hydrogen / nitrogen atmosphere of 0.50 for 2 minutes, and then P (H₂O) / P (H₂) Was annealed for 1 minute in an atmosphere of 0.005. All of these steel plates are decarburized to a C content of 0.002% or less, and the oxygen basis weight is 0.8 to 1.1 g / m.²Adjusted.
[0073]
Then 5% TiO in magnesia₂2% Sr (0H)₂And 2% SnO₂An annealing separator added with 12g / m on both sides of the steel plate²After applying and winding in a coil shape, final finish annealing was performed. Here, the steel plates A-1, A-2, A-3 and A-5 are made of Al as Al.₂O_ThreeUsing magnesia containing 0.1% in terms of conversion, A-4, A-6 and A-7 have Al as Al as a conventional example.₂O_ThreeMagnesia with a purity of 97% and containing less than 0.001% in terms of conversion was used.
[0074]
Final finish annealing is performed for steel plates A-1, A-4, A-5, A-6, and A-7.₂In a single atmosphere, the temperature was increased to 850 ° C. at a temperature increase rate of 30 ° C./h, and then maintained for 15 hours.₂And 75% H₂In a mixed atmosphere at a heating rate of 12 ° C./h up to 1100 ° C.₂The temperature was raised to 1150 ° C. in a single atmosphere and held for 5 hours to cool.
[0075]
Steel sheet A-2 was heated to 840 ° C. at a rate of 30 ° C./h, but N₂Raise the temperature to 350 ° C in a single atmosphere, then 10% H₂And 90% N₂In a mixed atmosphere, the temperature was raised to 850 ° C. and kept for 15 hours, and then 25% N₂And 75% H₂In a mixed atmosphere at a heating rate of 12 ° C./h up to 1100 ° C.₂The temperature was raised to 1150 ° C. in a single atmosphere and held for 5 hours to cool. Furthermore, the steel sheet A-3 is N₂In a single atmosphere, the temperature was increased to 850 ° C. at a temperature increase rate of 30 ° C./h, and subsequently maintained for 15 hours, then increased to 1100 ° C. at a temperature increase rate of 12 ° C./h, and thereafter 25% N₂And 75% H₂The temperature is raised to 1150 ° C. in a mixed atmosphere of₂It switched to the single atmosphere and was hold | maintained for 5 hours and cooled.
[0076]
The coils of these steel plates were baked at 800 ° C. after removing the unreacted separating agent after applying the final finish annealing, applying a tensile insulating coating mainly composed of magnesium phosphate containing colloidal silica.
[0077]
With respect to the steel sheet thus obtained, the film appearance and the adhesion of the film were evaluated by a method in which the steel sheet was wound around a round bar of various diameters to determine the diameter of the round bar where the film did not peel off. Furthermore, a thin film cross-section of the forsterite-based coating was prepared using an ion milling technique, and the cross-section of the coating particle was observed with a transmission electron microscope and the component was examined with an analytical electron microscope. Table 3 shows these evaluations and survey results.
[0078]
Furthermore, the surface of these steel plates was irradiated with a plasma jet linearly at intervals of 5 mm to obtain products. An SST (single plate test) specimen having a width of 100 mm and a length of 400 mm along the rolling direction was taken from each product, and the iron loss value W at a magnetic flux density of 1.7 T was obtained._17/50And magnetic flux density B₈Was measured. These measurement results are also shown in Table 3.
[0079]
[Table 3]

[0080]
As shown in Table 3, the grain-oriented electrical steel sheet product A-1 having a component and an undercoat according to the present invention exhibited excellent adhesion and magnetic properties with extremely low iron loss.
[0081]
Example 2
The molten steel having the component composition of slabs B and C shown in Table 2 was cast by a continuous casting machine for 12 slabs each having a thickness of 220 mm. Each slab after casting was placed in a gas heating furnace and heated to 1200 ° C., then rough rolled to 45 mm and hot rolled to a thickness of 2.4 mm by finish rolling.
[0082]
Thereafter, each coil was heated up to 1000 ° C. at a rate of 15 ° C./s, held for 30 seconds, and then rapidly cooled by spraying mist water. At this time, a combustion gas having an air-fuel ratio of 0.95 and a dew point of 45 ° C. was used as the annealing atmosphere, and the steel sheet surface layer was decarburized and annealed, and its C content was reduced to 0.020%. Next, warm rolling was performed so that the maximum temperature as the sheet temperature on the final rolling stand exit side was 250 ° C. by a pickling tandem rolling mill, and the final sheet thickness was 0.34 mm.
[0083]
Furthermore, after degreasing each steel plate, decarburization annealing was performed at 820 ° C. for 2 minutes. At that time, the rate of temperature increase from 500 ° C. to 820 ° C. was set to 14 ° C./s. Annealing is P (H₂O) / P (H₂) Of 0.55 in a wet hydrogen / nitrogen atmosphere. The oxygen basis weight is 0.98 to 1.45 g / m.²The C content was decarburized to 0.002% or less.
[0084]
After decarburization annealing, the steel plate composed of slab B is 4% TiO.₂And 2% strontium sulfate, and the remainder is coated with an annealing separator made of magnesia having a purity of 97 to 98% on the steel sheet surface (13 g / m on both steel sheets)²) And wound up. For MgO, Al₂O_ThreeEach type of magnesia containing 0.001% to 15.5% Al in terms of was used. Moreover, the steel plate which consists of a component of slab C is 4% TiO as an annealing separator.₂And 2% strontium sulfate, magnesia in the range of 50% to 96%, and the remainder CaO were applied to each steel sheet surface and wound. Here, as magnesia, Al₂O_ThreeMagnesia containing 0.24% Al and having a purity of 95% was used.
[0085]
Thereafter, each steel plate was heated at a rate of 30 ° C / h, and N₂Single atmosphere, then 30% N up to 1050 ° C₂And 70% H₂Mixed atmosphere of H₂After performing the final finish annealing, which was raised to 1180 ° C. and held for 5 hours in a single atmosphere, the unreacted separating agent was removed. Further, an insulating coating mainly composed of aluminum phosphate containing 60% colloidal silica was applied to the coils of these steel plates, and the products were baked at 800 ° C.
[0086]
About the steel plate thus obtained, the coating appearance was evaluated by measuring the appearance of the coating and the diameter of the round bar where the coating was wound around a round bar of various diameters and the coating did not peel off. Furthermore, a thin film cross-section of the forsterite-based coating was prepared using an ion milling technique, and the cross-section of the coating particle was observed with a transmission electron microscope and the component was examined with an analytical electron microscope. Some of these evaluation and measurement results are shown in Table 4.
[0087]
Further, an Epstein-sized test piece was cut out from each product along the rolling direction, subjected to strain relief annealing at 800 ° C. for 3 hours, and then the iron loss value at a magnetic flux density of 1.7 T W_17/50And magnetic flux density B₈Was measured. Some of these measurement results are also shown in Table 4.
[0088]
[Table 4]

[0089]
In addition, Al in the annealing separator₂O_ThreeFIG. 12 shows the influence of the Al content converted to the iron loss on the iron loss, and FIG. 13 shows the influence of the pure MgO equivalent content in the annealing separator on the iron loss.
[0090]
As shown in FIGS. 12 and 13, Al in the annealing separator₂O_ThreeIt can be seen that it is advantageous in terms of iron loss characteristics to regulate the Al content in terms of to 0.01 to 8.0 and the MgO equivalent content in the annealing separator to 70% or more.
[0091]
Example 3
Steel having the components shown by slabs D to K in Table 2 was melted and cast into a steel slab having a thickness of 220 mm by continuous casting. These slabs were heated to 1200 ° C in the gas combustion furnace, then removed from the furnace, cooled until the surface temperature reached 1150 ° C, and then charged into an induction heating furnace to 1380 ° C. After heating, a hot rolled coil of 2.4 mm was obtained by rough rolling and hot rolling with a finish rolling mill.
[0092]
These coils were heated to 200 ° C. and pickled, and were cold-rolled to a thickness of 0.55 mm for the steel sheet of symbol D and 1.80 mm for the other steel sheets using a tandem rolling mill. Thereafter, as intermediate annealing, the steel sheet of symbol D was heated to 970 ° C. at a rate of 12 ° C./s, and further maintained for 60 seconds, and then jet water was injected and cooled in 30 seconds. The temperature was raised to 10 ° C. at a rate of 10 ° C./s, and further maintained for 60 seconds, then jetted with water and cooled for 30 seconds. Next, each coil was subjected to a maximum plate temperature of 220 ° C. and a aging between passes at 150 to 200 ° C. with a Zenzimer rolling mill, and finished to a final plate thickness of 0.22 mm by rolling of 5 passes.
[0093]
After that, each coil was repeatedly formed with grooves having a depth of 20 μm, a width of 120 μm, and extending in the direction perpendicular to the rolling by electrolytic etching after degreasing with a repetition interval of 5 mm in the rolling direction. Then, P (H₂O) / P (H₂) Was decarburized and annealed in a wet hydrogen / nitrogen atmosphere of 0.52, but at that time, each steel plate was divided into two, and the heating rate at 500 to 850 ° C. was 4.0 ° C. / S, and the other steel plate was 17 ° C./s.
[0094]
Then Al₂O_ThreeConverted to 98% pure magnesia containing 0.002% Al, 0.24% Ca and 0.08% B, 7% TiO₂And an annealing separator added with 2% tin oxide were applied to the coil surface and subjected to final finish annealing.
[0095]
Final finish annealing is performed at a rate of temperature rise of 35 ° C / h, up to 750 ° C at the time of temperature rise.₂Single atmosphere, then 35% N up to 1180 ° C₂And 65% H₂Mixed atmosphere, and then H at 1180 ° C₂This was carried out for 5 hours in a single atmosphere, and then the unreacted separating agent was removed. These coils were further baked at 800 ° C. by applying an insulating coating mainly composed of magnesium phosphate containing 60% colloidal silica.
[0096]
About the steel plate thus obtained, the coating appearance was evaluated by measuring the appearance of the coating and the diameter of the round bar where the coating was wound around a round bar of various diameters and the coating did not peel off. Furthermore, a thin film cross-section of the forsterite-based coating was prepared using an ion milling technique, and the cross-section of the coating particle was observed with a transmission electron microscope and the component was examined with an analytical electron microscope. These evaluations and survey results are shown in Table 5. Further, an Epstein-sized test piece was cut out from each product along the rolling direction and subjected to strain relief annealing at 800 ° C. for 3 hours, and then the iron loss value W at a magnetic flux density of 1.7 T._17/50And magnetic flux density B₈Was measured. These measurement results are also shown in Table 5.
[0097]
[Table 5]

[0098]
Table 5 shows that the product obtained according to the production conditions of the present invention has both good film adhesion and iron loss characteristics.
[0099]
Example 4
Steel having the components shown in slabs L to N in Table 2 was melted and cast into a steel slab having a thickness of 70 mm by continuous casting. These slabs were charged into an electric heating furnace, the slabs with the symbol L were heated to 1380 ° C., the slabs with the symbols M and N were heated to 1180 ° C., and then hot rolled in a finishing mill to 2.6 mm. A hot rolled coil was used.
[0100]
These coils were annealed to 500 ° C., pickled, and cold-rolled to 1.90 mm with a tandem rolling mill. Then, as intermediate annealing, heat treatment was performed by heating to 1050 ° C. and holding for 60 seconds, and then jetting jet water and cooling in 30 seconds. Each coil was then cold rolled by a tandem mill to a final thickness of 0.34 mm.
[0101]
Each coil was degreased and then decarburized and annealed at 820 ° C. for 2 minutes. At this time, the temperature increase rate from 500 to 820 ° C. was set to 17 ° C./s. The annealing atmosphere is P (H₂O) / P (H₂) Was performed in a wet hydrogen / nitrogen atmosphere of 0.56, but the coil of symbol L was divided into 6 parts, followed by decarburization annealing, followed by P (H₂O) / P (H₂) Was subjected to a firelite decomposition treatment in an atmosphere of 0.50, 0.20, 0.10, 0.05, 0.01, or 0.004. And the infrared reflection spectrum of the steel plate surface after a firelite decomposition process was measured, and the absorbance ratio: Af / As of the infrared reflection spectrum of a firelite and a silica was calculated | required. These values are shown in Table 6. Further, the coil of the symbol M is divided into four parts, followed by decarburization annealing, followed by 10% NH at 800 ° C._Three70% N₂20% H₂Nitriding treatment for 2 seconds, 10 seconds, 25 seconds, and 35 seconds in an atmosphere of N, the N content in the steel before decarburization annealing was increased to 14, 68, 182, and 250 ppm, respectively, compared to 43 ppm. I let you.
[0102]
Then Al₂O_ThreeTo 97% pure magnesia containing 0.12% Al, 0.35% Ca and 0.04% B in terms of 5% TiO₂An annealing separator containing 2% tin oxide was applied to the coil surface and subjected to final finish annealing.
[0103]
The final finish annealing conditions were a temperature increase rate of 35 ° C / h and N up to 800 ° C at the time of temperature increase.₂Single atmosphere, then 15% N up to 1100 ° C₂And 85% H₂Mixed atmosphere of H₂A final finish annealing was performed at 1200 ° C. for 5 hours in a single atmosphere, and then the unreacted separating agent was removed. These coils were further baked at 800 ° C. by applying an insulating coating composed mainly of magnesium phosphate containing 50% colloidal silica.
[0104]
About the steel plate thus obtained, the coating appearance was evaluated by measuring the appearance of the coating and the diameter of the round bar where the coating was wound around a round bar of various diameters and the coating did not peel off. Furthermore, a thin film cross-section of the forsterite-based coating was prepared using an ion milling technique, and the cross-section of the coating particle was observed with a transmission electron microscope and the component was examined with an analytical electron microscope. These results are shown in Table 6. In addition, an Epstein-sized test piece was cut out from each product along the rolling direction and subjected to stress relief annealing at 800 ° C. for 3 hours, and then the iron loss value W at a magnetic flux density of 1.7 T._17/50And magnetic flux density B₈Was measured. These measurement results are also shown in Table 6.
[0105]
[Table 6]

[0106]
Table 6 shows that the product obtained according to the production conditions of the present invention has both excellent film adhesion and iron loss characteristics.
[0107]
【The invention's effect】
As described in detail above, according to the present invention, a grain-oriented electrical steel sheet having excellent coating adhesion and iron loss characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is an electron micrograph and μ-diffraction result of a thin film cross section of an undercoat of a steel sheet of sample symbol (a).
FIG. 2 is a diagram illustrating the structure of the base coating film of FIG.
3 is a component element analysis between 1 s and 1f shown in FIG. 2 of the cross section of the undercoat film of FIG. 1, and the change in the Al concentration is expressed as a ratio of the Al count number to the oxygen count number: Na / No. FIG.
FIG. 4 is an electron micrograph and μ-diffraction result of a thin film cross section of an undercoat of a steel sheet of sample symbol (b).
5 is a diagram for explaining the structure of the undercoat film of FIG. 4;
6 is a component element analysis between 2 s and 2 f shown in FIG. 5 in the cross section of the undercoat film of FIG. 4, and the change in Al concentration is the ratio of the Al count number to the oxygen count number: Na / No FIG.
FIG. 7 is an electron micrograph and μ-diffraction result of a thin film cross section of an undercoat of a steel sheet of sample symbol (g).
8 is a diagram for explaining the structure of the undercoat film of FIG. 7;
FIG. 9 is a cross-sectional view of the undercoat of FIG. 7 and a component element analysis was performed between 3 s and 3 f shown in FIG. 8, and the Al concentration change was expressed as a ratio of the Al count number to the oxygen count number: Na / No. FIG.
FIG. 10 is a diagram showing the results of infrared reflection spectrum measurement of firelite and silica, which are oxides on the steel sheet surface after decarburization annealing.
FIG. 11 is a diagram showing a method for calculating the absorbance of firelite and silica from an infrared reflection spectrum.
FIG. 12 Al in annealing separator₂O_ThreeIt is the figure which showed the influence which it has on the iron loss of Al content converted into.
FIG. 13 is a view showing the influence of the magnesia equivalent content in the annealing separator on the iron loss.
[Explanation of symbols]
1 Forsterite (Al-free part)
2 Boundary line between Al-containing and non-containing parts
3 Forsterite (Al-containing part)
4 Spinel
5 Resin
6 Railway
7 Overlapping part of Fe alloy on forsterite

Claims (8)

Si: 1.5-7.5 mass% and Mn: 0.03-3.5 mass% , having a component composition of the balance Fe and inevitable impurities, and having at least 70 produced on the surface during final finish annealing % in the oriented electrical steel sheet having a base film made of forsterite particles, lower ground coating, forsterite particles Al is dissolved in the total forsterite particles in contact with the base iron of the steel plate, and contact with該地iron A grain-oriented electrical steel sheet characterized in that the concentration of solute Al in the inside increases toward the ground iron side. In Claim 1, as a component, 1 type (s) or 2 or more types chosen from Sb, Sn, Cu, Cr, Ni, Ge, and Bi, and 0.0005-0.080 in Sb and Bi, respectively. mass %, Cu, Cr, Ni, Sn and Ge are 0.0010 to 1.30, respectively. mass A grain-oriented electrical steel sheet characterized by being contained in%. In Claim 1 or 2, about the component of a steel plate, C: 0.0050 mass% or less, S: 0.0020 mass% or less, N: 0.0020 mass% or less, Se: 0.0020 mass% or less, O: 0.0020 mass% A grain-oriented electrical steel sheet characterized by being limited to Ti: 0.0030 mass% or less, B: 0.0005 mass%, and Nb: 0.0020 mass% or less. 4. The grain oriented electrical steel sheet according to claim 1, 2 or 3, wherein the average crystal grain size of the forsterite particles is 0.05 to 0.5 [mu] m. C: 0.10 mass% or less, Si: 1.5 to 7.5 mass%, and Mn: 0.03 to 3.50 mass%, S, Se, Al, Sb, Sn, Cu, Cr, Ni, Ge, Bi one or more selected from, Sb and Bi are 0.0005~0.080 mass%, Cu, Cr, Ni, Sn and Ge are 0.0010~1.30 mass%, S, Se and Al Is contained in the range of 0.010 to 0.035 mass %, and the steel slab having the balance Fe and inevitable impurity component composition is hot-rolled, and the final thickness is obtained by one or more cold rollings. Then, after applying the annealing separator on the steel sheet surface after the primary recrystallization annealing, and then applying the final finishing annealing consisting of the secondary recrystallization annealing and the purification annealing,
The primary recrystallization annealing is performed by adjusting the annealing temperature to a range of 700 to 950 ° C. at an average temperature increase rate of 500 ° C. or more at 5 ° C./s or more, and in the temperature range of 500 ° C. or more, The ratio of hydrogen partial pressure to pressure P (H ₂ O) / P (H ₂ ) is set to 0.15 to 0.75 over 60 seconds,
Thereafter, an Al-containing material Al containing 0.01～8.0Mass% in an equivalent amount of ₂ O ₃ in terms, and an annealing separator containing magnesia over 70 mass% in an equivalent amount of MgO in terms, on the surface of the steel sheet Apply,
Next, final finish annealing is performed in a temperature rising process of 400 to 1000 ° C., in an atmosphere of either N ₂ or Ar or a mixed atmosphere thereof, and in a temperature range exceeding 1000 ° C., the H ₂ atmosphere or H ₂ is 65%. A method for producing a grain-oriented electrical steel sheet, which is carried out in a temperature range of 1000 to 1250 ° C. in an atmosphere containing the above . 6. The steel sheet surface according to claim 5, wherein, following the primary recrystallization annealing, the firelite is reduced with a gas that can be reduced to a H ₂ partial pressure ratio and a temperature, or heat-treated in a dry neutral gas . A method for producing a grain-oriented electrical steel sheet, comprising subjecting firelite to decomposition treatment in the range of an absorbance ratio Af / As: 0.3 to 5.0 of an infrared reflection spectrum with silica.   The method for producing a grain-oriented electrical steel sheet according to claim 5 or 6, characterized in that after the primary recrystallization annealing and before the secondary recrystallization annealing, a nitriding treatment is performed in which N is contained in the steel at an upper limit of 550 ppm. .   The direction according to claim 5, 6 or 7, wherein a plurality of grooves are formed on the steel plate surface after the final cold rolling and before or after the final finish annealing, or linear local strain is introduced into the steel plate. Method for producing an electrical steel sheet.

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