JP3551849B2 - Primary recrystallization annealed sheet for unidirectional electrical steel sheet - Google Patents

Description

【００３０】
同表に示したとおり、（０ １５ ０）から１０°以内と（５ ２０ ７０）から１０°以内のどちらか一方または両方に極大方位が存在する場合には、製品の磁気特性Ｂ_８ は１．８５Ｔ以上の良好な値を示した。
しかしながら、（０ １５ ０）から１０°以内と（５ ２０ ７０）から１０°以内のどちらにも極大方位が存在しない場合には、磁気特性Ｂ_８ は１．８５Ｔ未満であった。
【００３１】
中心層の集合組織
次に、製品の磁気特性Ｂ_８ が１．８５Ｔ以上であった試料について、さらに一次再結晶後の試料の中心層における集合組織を測定し、製品の磁気特性との関係を調査したところ、表２に示す結果を得た。
【００３２】
【表２】

【００３３】
同表に示したとおり、中心層の集合組織において、（９０ ６０ ４５）から５°以内に極大方位が存在する場合には、製品の磁気特性Ｂ_８ は特に良好で１．８８Ｔ以上になるのに対し、（９０ ６０ ４５）から５°以内に極大方位が存在しない場合は、１．８５〜１．８８Ｔであった。
【００３４】
一次再結晶後の中心層において、（９０ ６０ ４５）から５°以内に極大方位が存在しない場合の特徴として、集合組織では｛４１１｝＜１４８＞方位（ Ｂｕｎｇｅのオイラー角表示でφ_１ ＝２０°、Φ＝２０°、φ_２ ＝４５°。以後（２０ ２０ ４５）と略す）が強く、中心付近の一次粒径は粗大化している傾向にあった。
また、製品においては、ところどころ二次粒が板厚方向に貫通できていない部分があった。
【００３５】
上記の実験結果を考察すると、集合組織制御について次のように考えられる。
（１） 一次再結晶集合組織においては、まず表層近傍の集合組織制御が肝要である。というのは、二次再結晶粒は比較的表層近傍から発生・成長し易く、この領域の集合組織が良好な二次再結晶を生じさせるために非常に重要だからである。
表層近傍の集合組織によって、粒成長開始直後にゴス方位が周囲に比べてサイズ効果を持つまでに成長できるか、逆に周囲に蚕食されてしまうかが決まってくる。
最終仕上焼鈍時にゴス方位の成長をし易くするためには、ゴス方位から３０°程度の方位差の粒の頻度が高ければよい。ここに、ゴス方位から３０°程度の方位差であり、一次再結晶焼鈍後に表層近傍に頻繁に現れる方位としては（０ １５ ０）、（５ ２０ ７０）および（９０ ６０ ４５）の３つの方位が挙げられる。
【００３６】
（０ 15 ０）方位は、最終冷延圧下率が低い場合に発達し易い。この方位は、上述したとおり、ゴス方位からの方位差が30 °であり、ゴス方位の成長には最適である。さらに、この方位は、ゴス方位に蚕食されずに残ったとしても、磁化容易軸＜００１＞が圧延方向を向いているため、磁気特性の劣化を引き起こさない方位である。
従って、最終冷延圧下率が低い場合には、（０ 15 ０）近傍に極大方位が存在するように、一次再結晶集合組織を制御すべきである。
【００３７】
（５ ２０ ７０）方位は、最終冷延圧下率が比較的高い場合に発達し易い。この方位は、ゴス方位からの方位差が３０°であり、ゴス方位の成長には最適である。従って、ゴス方位に蚕食されずに残る確率は小さい。また、ゴス方位に蚕食されずに残ったとしても、磁化容易軸＜００１＞と圧延方向とのずれは１４°しかないため、磁気特性の劣化をあまり生じない。さらに、この方位は、ＮＤ回りの方位分散が小さいことから、ジャストゴス方位粒の成長に最適であり、またゴス方位からずれた粒（特に磁気特性を劣化させるゴス方位からＮＤ回りにずれた粒）が成長しにくいという利点がある。
従って、最終冷延圧下率が高い場合には、（５ ２０ ７０）近傍に極大方位が存在するように、一次再結晶集合組織を制御すべきである。
【００３８】
（９０ ６０ ４５）方位は、表層近傍では一般に極大方位になり易いので、本発明では特に制御の対象とはしない。ただし、この方位の強度が強すぎると、相対的に（０ １５ ０）方位または（５ ２０ ７０）方位への集積が弱まり、（０ １５ ０）近傍や（５ ２０ ７０）近傍に極大方位が存在しなくなる。また、（９０ ６０ ４５）方位は、ゴス方位からの方位差が３０°であり、ゴス方位の成長には最適であるが、ＮＤ回りの方位分散が大きいことから、ゴス方位からずれた粒（特に磁気特性を劣化させるゴス方位からＮＤ回りにずれた粒）も成長し易いという欠点を持つ。
従って、（９０ ６０ ４５）方位が表層で極端に多くなることは好ましくない。
【００３９】
（２） 表層の一次再結晶粒集合組織を、上記したように制御すれば、最終仕上焼鈍時にジャストゴス方位のみが二次再結晶し、製品の磁気特性は良好となるが、さらに安定して良好な磁気特性を得るには、中心層の集合組織制御が重要となる。中心層の集合組織は、表層で発生し、成長し始めた二次粒が板厚方向の中心部で止められることなく貫通できるかどうかを支配する。
【００４０】
中心層の一次再結晶粒集合組織において、発達し易い方位は（９０ ６０ ４５）方位と（２０ ２０ ４５）方位である。（９０ ６０ ４５）方位は、ゴス方位からの方位差が３０°であり、しかも一次粒径が均一になり易いため、表層で発生したゴス方位の二次粒が成長するには最適である。しかしながら、中心層において、（９０ ６０ ４５）付近の極大方位は、製造条件によってシフトし易く、（９０ ６０ ４５）から大きくずれてしまい易い。
（９０ ６０ ４５）への集積が弱まると、相対的に（２０ ２０ ４５）方位が増大する。この（２０ ２０ ４５）方位は、ゴス方位との方位差が３９°であり、最適値３０°よりも大きい。また、（２０ ２０ ４５）方位は、周囲の一次粒よりも粗大になり易いため、表層で発生した二次粒が板厚中心部で止められてしまう。
従って、中心層では（９０ ６０ ４５）近傍に極大方位が存在するように、一次再結晶集合組織を制御すべきである。
【００４１】
以上、説明したとおり、一次再結晶集合組織は、表層と中心層に分けて制御すべきであり、表層では（０ １５ ０）方位と（５ ２０ ７０）方位に、一方中心層では（９０ ６０ ４５）方位に着目すべきことが判明した。
従来から注目されてきた｛１１１｝＜１１２＞（（９０ ５４．７ ４５）方位）と｛４１１｝＜１４８＞（（２０ ２０ ４５）方位）はいずれも、ゴス方位とΣ９の対応方位関係の範囲内（Ｂｒａｎｄｏｎの条件）であるが、本発明で対象とする（０ １５ ０）、（５ ２０ ７０）および（９０ ６０ ４５）はゴス方位とΣ９の対応方位関係の範囲ではない。
【００４２】
（９０ ６０ ４５）は、ミラー指数表示では｛５５４｝＜２２５＞に近く、ＢＣＣ金属多結晶材の一次再結晶集合組織としては比較的頻繁に発生する方位として知られている（鉄鋼薄板の再結晶及び集合組織；昭和４９年鉄鋼基礎共同研究会再結晶部会）が、一方向性電磁鋼板の一次再結晶集合組織としては、これまでゴス方位との対応方位関係という観点から｛１１１｝＜１１２＞により注目が集められてきた。
しかしながら、本発明により、ゴス方位の二次再結晶と対応方位関係とは無関係であることが明らかになった。
なお、本発明では、表層では（０ １５ ０）方位または（５ ２０ ７０）方位が、一方中心層では（９０ ６０ ４５）方位が、それぞれ極大方位であるか否かが重要であり、その集積度は特に限定しないし、また他に強いピークが存在するか否かについても限定しない。
【００４３】
次に、一次再結晶焼鈍板の集合組織を制御する方法としては、材料成分、スラブ加熱条件、熱間圧延条件、熱延板焼鈍条件、中間焼鈍条件、冷間圧延条件（特に圧下率と圧延温度および時効処理条件）および一次再結晶焼鈍条件等の調整が挙げられる。
表層で（０ １５ ０）または（５ ２０ ７０）に、中心層で（９０ ６０ ４５）に強く集積させる方法としては、例えば以下のような方法がある。
【００４４】
方法１：スラブに含有させるインヒビター成分を従来レベルよりも大幅に低減することによって、最終冷延前における鋼板表層部の粒径を大きくし、粒内からの再結晶を促進させる方法。
表層部で粒内からの再結晶を促進させることにより、（０ １５ ０）方位や（５２０ ７０）方位の一次再結晶が頻繁になる。
【００４５】
方法２：圧延温度を上げること（温間圧延）により、＜１１０＞方向が圧延方向に揃ったバンド組織からの（０ １５ ０）方位や（５ ２０ ７０）方位の再結晶を促進させる方法。
温間圧延による集合組織変化は、表層近傍で顕著に起こるので、本発明の集合組織制御には有効である。特に、タンデム圧延機での温間圧延は、表層近傍では剪断変形を起こし（０ １５ ０）方位や（５ ２０ ７０）方位の一次再結晶を促進する一方、中心層では均一変形を起こし（９０ ６０ ４５）方位の一次再結晶を促進するので、極めて効果的である。
【００４６】
方法３：素材成分（特にインヒビター成分）に応じて最終冷延圧下率を調整する方法。
これは、素材成分が異なると一次再結晶集合組織の集積のピークがシフトする性質と、圧下率が異なると一次再結晶集合組織の集積のピークがシフトする性質を組み合わせて利用する方法である。
【００４７】
本発明では、上記したように、一次再結晶焼鈍板の集合組織を制御することが重要である。制御する方法は特に限定されるものではないが、一般には、以下の製造条件に従うことが望ましい。
【００４８】
まず、素材の成分組成範囲について説明する。
Ｃ：０．００５ ｗｔ％以上、０．０８ｗｔ％以下
Ｃは、組織を改善し、二次再結晶を安定化させるために必要な元素で、そのためには ０．００５ｗｔ％以上含有させることが好ましい。しかしながら、０．０８ｗｔ％を超えると冷延時の破断が増加するだけでなく、脱炭に要する焼鈍時間が長くなり生産性の低下を招くので、０．０８ｗｔ％以下とすることが好ましい。
【００４９】
Ｓｉ：２．０ ｗｔ％以上、４．５ ｗｔ％以下
Ｓｉは、電気抵抗を増加させ鉄損を低減するために不可欠の元素であり、このためには ２．０ｗｔ％以上含有させる必要があるが、４．５ ｗｔ％を超えると加工性が劣化し、製造や製品の加工が極めて困難になるので、２．０ ｗｔ％以上、４．５ ｗｔ％以下の範囲で含有させることが好ましい。
【００５０】
Ｍｎ：０．０３ｗｔ％以上、２．５ ｗｔ％以下
Ｍｎも、同じく電気抵抗を高め、また製造時の熱間加工性を向上させるのに有用な元素である。この目的のためには、０．０３ｗｔ％以上の含有が必要であるが、２．５ ｗｔ％を超えて含有した場合、 γ変態を誘起して磁気特性が劣化するので、０．０３ｗｔｗｔ％以上、２．５ ｗｔ％以下の範囲とすることが好ましい。
【００５１】
インヒビター成分
Ａｌ， Ｓｅ， Ｓ， ＳｂおよびＳｎ等を必要に応じて添加し、インヒビターとして機能させる。その場合におけるこれらの元素の添加量はそれぞれ Ａｌ：０．００３ 〜０．０５０ ｗｔ％， Ｓｅ：０．００３ 〜０．０５０ ｗｔ％，Ｓ：０．００３ 〜０．０５０ ｗｔ％，Ｓｂ：０．００１ 〜０．３ ｗｔ％，Ｓｎ：０．００１ 〜０．３ ｗｔ％程度とすることが好ましい。
【００５２】
Ａｌは、Ｎと結びついてＡｌＮとしてインヒビターの役割を果たす。インヒビターとして有効に機能させるためには、熱延前のスラブ加熱時に固溶させ、後の工程で微細に析出させる必要があるが、含有量が０．０５０ｗｔ％を超えるとスラブ加熱時の固溶が不完全になり、一方 ０．００３ｗｔ％未満ではインヒビターの量が不足しその効果を発揮できないので、 ０．００３〜０．０５０ ｗｔ％の範囲で含有させることが好ましい。
【００５３】
Ｓｅ、Ｓは、Ｍｎと結びついてＭｎＳｅ、 ＭｎＳとしてインヒビターの役割を果たす。インヒビターとして有効に機能させるためには、Ａｌと同様、熱延前のスラブ加熱時に固溶させ、後の工程で微細に析出させる必要があるが、含有量が ０．０５０ｗｔ％を超えるとスラブ加熱時の固溶が不完全になり、一方 ０．００３ｗｔ％未満ではインヒビターの量が不足しその効果が発揮できないので、 ０．００３〜０．０５０ ｗｔ％の範囲で含有させることが好ましい。
【００５４】
Ｓｂ、Ｓｎは、粒界に偏析してインヒビターとして機能する。インヒビターとして十分機能させるためには、０．００１ ｗｔ％以上の含有が必要であるが、０．３ ｗｔ％を超えると製品のベンド特性等の機械的特性が劣化するので、 ０．００１〜０．３ ｗｔ％の範囲で含有させることが好ましい。
【００５５】
インヒビターとしては、上記元素の他に、Ｃｒ， Ｃｕ， Ｎｂ， Ｂ等を添加することもできる。添加量は、インヒビター機能を十分発揮でき、かつ製品のベンド特性等の機械的特性を劣化させない範囲内とすべきであり、それぞれＣｒ：０．００１ 〜０．３ ｗｔ％， Ｃｕ：０．００５ 〜０．５ ｗｔ％， Ｎｂ：０．００ｌ 〜０．３ ｗｔ％， Ｂ：０．０００１〜０．０５ｗｔ％程度とすることが好ましい。
なお、最近、インヒビター元素を特に添加しなくても、粒界移動度の方位差依存性を利用して二次再結晶を生じさせる技術が報告されているが、この技術は、本発明にも適応できる技術である。
【００５６】
次に、製造工程について説明する。
熱間圧延工程
上記の成分組成に調整されたスラブは、通常の方法に従い、スラブ加熱に供した後、熱間圧延により熱延コイルとする。
なお、近年、スラブ加熱を行わず、連続鋳造後、直接熱間圧延を行う方法が提案されているが、この方法は本発明にも適用することができる。
【００５７】
熱延板焼鈍工程
熱延コイルに、必要に応じて、組織の均一化とインヒビターの微細析出のために、 ８００〜１１５０℃の温度範囲で熱延板焼鈍を施す。
【００５８】
冷間圧延・中間焼鈍工程
熱延コイルあるいは熱延板焼鈍後の鋼板に、１回または中間焼鈍を挟む２回以上の冷間圧延を施して製品板厚とする。冷間圧延は、タンデム圧延機で行ってもゼンジミア圧延機で行ってもよい。また、圧延は常温で行っても良いし、必要に応じて常温よりも高い温度とし、圧延中の動的歪時効やパス間の静的歪み時効を利用して集合組織を制御することも可能である。
【００５９】
脱炭および一次再結晶焼鈍工程
製品板厚に圧延された鋼板に、脱炭と一次再結晶を目的とした焼鈍を施す。
【００６０】
かくして得られる一次再結晶焼鈍板は、一方向性電磁鋼板を製造するための中間材として用いられる。
その後、一般的には、焼鈍分離剤を塗布してから、仕上焼鈍を施し、ついで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すことによって製品とする。
【００６１】
【実施例】
実施例１
Ｃ：０．０３５ ｗｔ％、Ｓｉ：２．９０ｗｔ％、Ｍｎ：０．０８ｗｔ％、Ａｌ：０．００３ ｗｔ％、Ｎ：０．００３ ｗｔ％、Ｓ：０．００１ ｗｔ％、Ｓｅ：０．０２０ ｗｔ％、Ｃｕ：０．０１ｗｔ％およびＳｂ：０．０２０ ｗｔ％を含有し、残部はＦｅおよび不可避不純物からなるスラブを複数用意し、１２５０℃に加熱後、熱間圧延して ３．０ｍｍ厚の熱延コイルとした。ついで、酸洗後、タンデム圧延機により第１回目の冷間圧延を施した。第１回目の冷間圧延後の板厚は０．５０〜２．０ ｍｍの範囲で変化させた。次に、 ９００〜１１００℃の温度で中間焼鈍後、再び酸洗したのち、ゼンジミア圧延機で第２回目の冷間圧延を施し、０．２２ｍｍの最終板厚に仕上げた。第２回目の冷間圧延では、圧延温度を８０℃から ３００℃までの範囲で変化させた。
その後、脱脂処理を行い、 ８００〜８８０ ℃で １２０秒間の脱炭を兼ねた一次再結晶焼鈍を施した。
かくして、表３に記号あ〜なで示すような、集合組織を大きく変化させた一次再結晶焼鈍板が得られた。
これらの一次再結晶焼鈍板の一部を採取し、表層近傍の集合組織の測定を行った。集合組織は、Ｘ線極点図により測定し、測定データから３次元集合組織を計算により求めた。なお、３次元集合組織はφ_１ 、Φ、φ_２ いずれも５°刻みで求めた。
【００６２】
ついで、これらの一次再結晶焼鈍板に、焼鈍分離剤を塗布してから、最終仕上焼鈍を施した。最終仕上焼鈍後、未反応の分離剤を除去したのち、コロイタ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 ℃で焼き付けて製品とした。
各製品から、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、磁束密度Ｂ_８ を測定した。
表３に、一次再結晶焼鈍板の表層近傍における集合組織の極大方位と製品の磁束密度Ｂ_８ を示す。
【００６３】
【表３】

【００６４】
同表に示したとおり、本発明に従い、表層の集合組織が（０ １５ ０）［または（５ ２０ ７０）］から１０°以内に極大方位を有する一次再結晶焼鈍板を用いることにより、製品の磁束密度Ｂ_８ が１．８５Ｔ以上の良好な製品を得ることができた。
【００６５】
ついで、製品の磁気特性Ｂ_８ が１．８５Ｔ以上であった試料について、さらに一次再結晶後の試料の中心層における集合組織を測定し、製品の磁気特性との関係について調べた。
表４に、中心層の集合組織における極大方位と製品の磁気特性Ｂ_８ との関係を示す。
【００６６】
【表４】

【００６７】
同表に示したとおり、中心層の集合組織が（９０ ６０ ４５）から５°以内に極大方位を有する場合には、さらに磁気特性Ｂ_８ が安定し、１．８８Ｔ以上の良好な値が得られた。
【００６８】
実施例２
Ｃ：０．０４５ ｗｔ％、Ｓｉ：３．２５ｗｔ％、Ｍｎ：０．０８ｗｔ％、Ａｌ：０．００７ ｗｔ％、Ｎ：０．００４ ｗｔ％、Ｓ：０．００２ ｗｔ％、Ｓｅ：０．００１ ｗｔ％、Ｃｕ：０．０１ｗｔ％、Ｓｂ：０．０１０ ｗｔ％およびＳｎ：０．０５ｗｔ％を含有し、残部はＦｅおよび不可避不純物からなるスラブを複数用意し、１２００℃に加熱後、熱間圧延して ２．５ｍｍ厚の熱延コイルとした。ついで、熱延板焼鈍後、酸洗してから、０．３４ｍｍの厚みまでタンデム圧延機により１回で冷間圧廷した。この際、熱延板焼鈍温度を ８００〜１１５０℃の範囲で、また冷間圧延温度を８０〜３００ ℃の範囲で変化させた。
その後、脱脂処理を行い、 ８００〜８８０ ℃で１２０ 秒間の脱炭を兼ねた一次再結晶焼鈍を施した。
かくして、表５に番号１〜２０で示すような、集合組織を大きく変化させた一次再結晶焼鈍板が得られた。
これらの一次再結晶焼鈍板の一部を採取し、表層近傍の集合組織の測定を行った。集合組織は、Ｘ線極点図により測定し、測定データから３次元集合組織を計算により求めた。なお、３次元集合組織はφ_１ 、Φ、φ_２ いずれも５°刻みで求めた。
【００６９】
ついで、これらの一次再結晶焼鈍板に、焼鈍分離剤を塗布してから、最終仕上焼鈍を施した。最終仕上焼鈍後、未反応の分離剤を除去したのち、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 ℃で焼き付けて製品とした。
各製品から、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、磁束密度Ｂ_８ を測定した。
表５に、一次再結晶焼鈍板の表層近傍における集合組織の極大方位と製品の磁束密度Ｂ_８ を示す。
【００７０】
【表５】

【００７１】
同表に示したとおり、本発明に従い、表層の集合組織が（０ １５ ０）［または（５ ２０ ７０）］から１０°以内に極大方位を有する一次再結晶焼鈍板を用いることにより、製品の磁束密度Ｂ_８ が１．８５Ｔ以上の良好な製品を得ることができた。
【００７２】
ついで、製品の磁気特性Ｂ_８ が１．８５Ｔ以上であった試料について、さらに一次再結晶後の試料の中心層における集合組織を測定し、製品の磁気特性との関係について調べた。
表６に、中心層の集合組織における極大方位と製品の磁気特性Ｂ_８ との関係を示す。
【００７３】
【表６】

【００７４】
同表に示したとおり、中心層の集合組織が（９０ ６０ ４５）から５°以内に極大方位を有する場合には、さらに磁気特性Ｂ_８ が安定し、１．８８Ｔ以上の良好な値が得られた。
【００７５】
実施例３
Ｃ：０．０６０ ｗｔ％、Ｓｉ：３．２５ｗｔ％、Ｍｎ：０．０９ｗｔ％、Ａｌ：０．０２７ ｗｔ％、Ｎ：０．００９ ｗｔ％、Ｓ：０．００２ ｗｔ％、Ｓｅ：０．０２０ ｗｔ％、Ｃｕ：０．１０ｗｔ％およびＳｂ：０．０２５ ｗｔ％を含有し、残部はＦｅおよび不可避不純物からなるスラブを複数用意し、１４００℃に加熱後、熱間圧延して ２．５ｍｍ厚の熱延コイルとした。引き続き ８００〜１１５０℃で６０秒間保持する熱延板焼鈍を施したのち、酸洗し、１．７ ｍｍの厚みまでタンデム圧延機により常温で第１回目の冷間圧延を施し、ついで ９５０℃の温度で中間焼鈍を施したのち、再び酸洗し、ゼンジミア圧延機により０．２２ｍｍの厚みまでの第２回目の冷間圧延を施した。第２回目の冷間圧延では、圧延温度を８０〜３００ ℃の範囲で変化させた。その後、脱脂処理を行い、 ８００〜８８０ ℃で１２０ 秒間の脱炭を兼ねた一次再結晶焼鈍を施した。
かくして、表７に記号ア〜ヌで示すような、集合組織を大きく変化させた一次再結晶焼鈍板が得られた。
これらの一次再結晶焼鈍板の一部を採取し、表層近傍の集合組織の測定を行った。集合組織は、Ｘ線極点図により測定し、測定データから３次元集合組織を計算により求めた。なお、３次元集合組織はφ_１ 、Φ、φ_２ いずれも５°刻みで求めた。
【００７６】
ついで、これらの一次再結晶焼鈍板に、焼鈍分離剤を塗布してから、最終仕上焼鈍を施した。最終仕上焼鈍後、未反応の分離剤を除去したのち、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。
各製品から、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、磁束密度Ｂ_８ を測定した。
表７に、一次再結晶焼鈍板の表層近傍における集合組織の極大方位と製品の磁束密度Ｂ_８ を示す。
【００７７】
【表７】

【００７８】
同表に示したとおり、本発明の要件を満足する一次再結晶焼鈍板を用いることにより、良好な磁束密度の製品が得られた。
【００７９】
ついで、製品の磁気特性Ｂ_８ が１．８５Ｔ以上であった試料について、さらに一次再結晶後の試料の中心層における集合組織を測定し、製品の磁気特性との関係について調べた。
表８に、中心層の集合組織における極大方位と製品の磁気特性Ｂ_８ との関係を示す。
【００８０】
【表８】

【００８１】
同表に示したとおり、中心層の集合組織が（９０ ６０ ４５）から５°以内に極大方位を有する場合には、さらに磁気特性Ｂ_８ が安定し、１．８８Ｔ以上の良好な値が得られている。
【００８２】
【発明の効果】
かくして、この発明に従い、一次再結晶焼鈍板の集合組織を的確に制御することにより、磁気特性を良好に保った方向性電磁鋼板を安定して製造することが可能となった。[0001]
[Industrial applications]
The present invention relates to a primary recrystallization-annealed sheet as an intermediate material that is advantageous for stably producing a grain-oriented electrical steel sheet having good magnetic properties.
[0002]
[Prior art]
Grain-oriented silicon steel sheets are mainly used as iron core materials for transformers and other electric equipment, and it is basically important that they have excellent magnetic properties such as magnetic flux density and iron loss value. Therefore, a slab having a thickness of 100 to 300 mm is heated to a high temperature and then hot-rolled, and then the hot-rolled sheet is subjected to one or two or more cold-rollings with intermediate annealing to obtain a final thickness. After that, a complicated process of performing primary recrystallization annealing also serving as decarburization, applying an annealing separating agent, and then performing final finish annealing for the purpose of secondary recrystallization and purification is employed.
In order to enhance the magnetic properties, the secondary recrystallization in the final finish annealing step grows crystal grains of the {110} <001> orientation, the so-called goss orientation, in which the <001> axis, which is the axis of easy magnetization, is aligned with the rolling direction. It is important that
[0003]
In order to effectively develop secondary recrystallization accumulated in the {110} <001> orientation by finish annealing, it is extremely important to properly control the state of the steel sheet before the stage, that is, after decarburizing annealing. In particular, the following three points need to be controlled.
[0004]
The first is to disperse a dispersed phase called an inhibitor that suppresses grain growth into a uniform and appropriate size.
By the action of the inhibitor, the growth of primary recrystallized grains is suppressed during final finish annealing, but only the grains having the {110} <001> orientation, which has the highest dominance of grain growth, erode other orientations. The inhibitory force of the inhibitor must be controlled so that only the grains of the {110} <001> orientation can grow and the growth of other grains can be prevented.
Typical examples of such inhibitors are sulfides such as MnS, MnSe, AlN and VN, Se compounds and nitrides, which have extremely low solubility in steel, and are used before hot rolling. In this method, the inhibitor is once completely dissolved in the slab at the time of heating the slab, and then finely precipitated in a subsequent step to control the inhibitory force.
[0005]
The second is to appropriately control the grain size distribution after the primary recrystallization.
Research has been conducted on the crystal grain size of the primary recrystallization structure from the viewpoint of controlling the driving force of the secondary recrystallization. For example, Japanese Patent Application Laid-Open No. 2-182866 discloses a primary recrystallized structure in which the average diameter of primary recrystallized grains is 15 μm or more and the coefficient of variation (standard deviation of the particle size distribution normalized by the average diameter) is 0.6 or less. It is disclosed that it is important to have Japanese Patent Application Laid-Open No. Hei 4-337029 discloses that the amount of N in steel in an annealing process before final cold rolling is detected, and a primary recrystallized grain within a range of 15 to 25 μm is obtained based on the result. A technique for changing a set temperature in recrystallization annealing is disclosed. Further, JP-A-6-33141 discloses that the average diameter of primary recrystallized grains after decarburization annealing is 6 to 11 μm and the coefficient of variation is 0.5 or less, and until just before the start of secondary recrystallization in final finish annealing. Discloses a technique for increasing the average diameter of primary recrystallized grains by 5 to 30%.
[0006]
As described above, there are various opinions on the optimal primary recrystallization particle size. This means that in order to cause secondary recrystallization, it is important to finely control the balance between the driving force for grain growth and the inhibitory force of the inhibitor that suppresses it, and the inhibitory force of the inhibitor depends on the chemical composition of the steel sheet and the process conditions. When the suppressing force changes, the optimum driving force, that is, the optimum primary recrystallized grain size also changes.
[0007]
Third, proper control of the primary recrystallization texture.
Good secondary recrystallization does not occur only by controlling the inhibitor suppressing force and the grain growth driving force, and the texture before the final finish annealing changes the secondary grain growth and orientation ({110} <001> (The strength of accumulation).
[0008]
The present invention relates to such primary recrystallization texture control, and proposes a primary recrystallization annealed sheet having a texture advantageous for good secondary recrystallization, based on a new discovery that overturns the conventional wisdom. It is.
[0009]
Conventionally, regarding the texture before final finish annealing, the main orientation strongly accumulates in the {111} <112> orientation, and the highly sharp {110} <001> orientation which serves as a nucleus of secondary recrystallization therein. Has been considered important. Such a concept is based on the theory that grain boundaries having a # 9 correspondence are easy to move, as disclosed in JP-A-5-171371 and JP-B-7-26155.
When the crystal lattices on both sides of a grain boundary are extended and overlapped, and parallelly moved to match a pair of lattice points, 1 / Σ of the lattice points match the adjacent lattice points. Strictly speaking, in the case of the Σ9 correspondence relationship, it means that the grains on both sides sandwiching the grain boundary are in a rotation relationship of 38.9 ° around the <110> axis. Is within the range of 38.9 ± 5.0 ° can be regarded as a 対 応 9 correspondence (Brandon's condition: 15 ° / Σ from a strict correspondence).^1/2  If it is within, it can be regarded as a correspondence relationship).
[0010]
{110} <001> and {111} <112> are in a rotation relationship of 35.3 ° around the <110> axis, and thus fall within a range that can be regarded as the relationship of {9}.
Therefore, in the primary recrystallized texture, a state in which {110} <001> having high sharpness is scattered in a matrix strongly integrated in {111} <112> becomes a state of {110} <001> orientation. It has been considered advantageous for secondary recrystallization.
[0011]
Recently, it has been disclosed that the orientation of the matrix of the primary recrystallization annealed plate is not necessarily in the vicinity of {111} <112>, and that attention should be paid to the sub orientation. For example, JP-A-9-296219 and JP-A-9-256051 disclose that it is important to control the intensity of the {411} <148> azimuth which is the sub azimuth. {110} <001> and {411} <148> have a substantially $ 9 correspondence, and here too, the basis is that the grain boundaries in the $ 9 correspondence are easy to move.
[0012]
[Problems to be solved by the invention]
However, even with an ideal texture in view of such a correspondence, secondary recrystallization failure occurs, or secondary recrystallization occurs, but many orientations deviating from {110} <001> appear. Therefore, there are often cases where the magnetic properties of products deteriorate, so it is urgently necessary to develop a primary recrystallization-annealed sheet as an intermediate material that can stably produce grain-oriented electrical steel sheets with good magnetic properties. It has become.
[0013]
The present invention advantageously satisfies the above-mentioned requirements, and has an object to propose a primary recrystallization-annealed sheet as an intermediate material capable of stably producing a grain-oriented electrical steel sheet having good magnetic properties.
[0014]
[Means for Solving the Problems]
By analyzing the orientation distribution of crystal grains in the middle of the secondary recrystallization, the inventors found that the Goss orientation is not related to the secondary recrystallization and the Σ9 correspondence. Was. In Japanese Unexamined Patent Publication No. Hei 10-140297, the fact that a large number of orientation grains having an azimuth difference of 20 to 40 ° from the Goss orientation after the primary recrystallization are present in the matrix causes favorable secondary recrystallization. It is important to disclose.
This is considered to be because when the crystal grains on both sides of the grain boundary have an azimuth difference of 20 to 40 °, the grain boundary energy increases and the grain boundary moving speed increases.
Therefore, the inventors have further studied diligently, and as a result, even within the range of 20 ° to 40 ° of the misorientation, it has been found that the grain boundary having the 30 ° misorientation has the highest grain boundary energy and is easy to move. Was. Here, the azimuth difference between the two directions is the minimum rotation angle for overlapping the two directions.
[0015]
Therefore, at the stage before the finish annealing, it is important to have many orientations having an orientation difference of about 30 ° from the Goss orientation, but any orientation having an orientation difference of about 30 ° from the Goss orientation is important. It cannot be freely increased or decreased, and in the primary recrystallized texture obtained as a result of rolling and annealing, the orientations that are likely to appear are limited to some.
Therefore, it is not enough to analyze the primary recrystallized texture in a three-dimensional azimuth space, pay attention to several azimuth peaks that are strongly integrated, and control the center of these peaks to be about 30 ° from the Goss azimuth. I hypothesized that.
Then, based on this hypothesis, as a result of repeated experiments and studies, the present invention was completed.
[0016]
That is, according to the present invention, the texture in the vicinity of the surface layer of the steel sheet is represented by Bunge's Euler angle, φ₁  = 0 °, Φ = 15 °, φ₂  A primary recrystallization-annealed sheet for a grain-oriented electrical steel sheet, which has a maximum orientation within 10 ° from an orientation of = 0 °.
[0017]
Further, according to the present invention, the texture in the vicinity of the surface layer of the steel sheet is represented by Bunge's Euler angle expression of φ₁  = 0 °, Φ = 15 °, φ₂  = 0 ° or less from 10 ° or φ₁  = 5 °, Φ = 20 °, φ₂  = 10 ° from the orientation of 70 °, and the texture of the central layer of the steel sheet is also φ in Bunge's Euler angle notation.₁  = 90 °, Φ = 60 °, φ₂  A primary recrystallization annealed sheet for a grain-oriented electrical steel sheet, which has a maximum orientation within 5 ° from an orientation of = 45 °.
[0018]
Further, the present invention provides
C: 0.005 to 0.08 wt%,
Si: 2.0 to 4.5 wt%,
Mn: 0.03 to 2.5 wt%
Containing, and
Al: 0.003 to 0.050 wt%,
Se: 0.003 to 0.050 wt%,
S: 0.003 to 0.050 wt%,
Sb: 0.001 to 0.3 wt%,
Sn: 0.001 to 0.3 wt%
After hot-rolling a silicon steel slab having a composition containing one or more selected from among them, subjecting it to hot-rolled sheet annealing as necessary, cooling once or twice or more with intermediate annealing This is a primary recrystallization-annealed sheet for a grain-oriented electrical steel sheet, which is obtained by performing a final recrystallization annealing to a final thickness by cold rolling and then performing a primary recrystallization annealing.
[0019]
Regarding the display of the crystal orientation by the Euler angle, the Roe's notation (indicated by ψ, θ, φ) and the Bunge's notation (φ₁  , Φ, φ₂  Display).
[0020]
First, the method of displaying Roe will be described.
The orthogonal coordinate system fixed to space is X, Y, Z (X is RD direction, Y is TD direction, Z is ND direction), and the orthogonal coordinate system fixed to crystal is x, y, z (x is The [100] direction, y is the [010] direction, and z is the [001] direction. From the state where (X, Y, Z) and (x, y, z) match, the crystal is rotated φ around the Z axis (ND), then θ around the Y axis (TD), and finally again. The azimuth rotated by ψ around the Z axis (ND) is the (ψ, θ, φ) azimuth according to the Roe representation method.
[0021]
The definition of variables in Bunge's notation is slightly different, but has the following relationship with Roe's notation.
φ₁(Bunge) = ψ (Roe) + 90 °
Φ (Bunge) = θ (Roe)
φ₂(Bunge) = φ (Roe) −90 °
Recently, since the Bunge's notation is more commonly used, the present invention also uses the Bunge's notation to express the crystal orientation.
[0022]
The maximum orientation is defined as follows.
That is, in Bunge's Euler angle display, φ₁  , Φ, φ₂  F (φ₁  , Φ, φ₂  ) And φ₁  = X, Φ = y, φ₂  The azimuth where = z is the maximum azimuth is defined as that all of the following (1), (2), and (3) hold.
(1) For all positive and negative h values whose absolute values are small enough,
f (x + h, y, z) -f (x, y, z) <0
(2) For all positive and negative k values whose absolute values are small enough,
f (x, y + k, z) -f (x, y, z) <0
(3) For all positive and negative 1 values whose absolute values are small enough,
f (x, y, z + 1) -f (x, y, z) <0
In addition, the random intensity ratio represents the existence ratio of a specific direction,
(Existence ratio of a portion having a specific orientation in a measurement site) ÷ (Existence ratio of a portion having that orientation in a virtual case where there is no orientation at all)
Is defined.
[0023]
For the texture, a pole figure is measured from the diffraction intensity of X-rays, and a three-dimensional intensity distribution can be calculated from the result by an azimuth distribution function (ODF). The intensity distribution can also be obtained by directly measuring the orientation of each crystal grain using an Electron Back Scattering Pattern (EBSP), an Electron Channeling Pattern (ECP), or the like.
[0024]
Generally, the texture changes in the thickness direction of the plate.
Therefore, in the present invention, the textures are measured in the vicinity of the surface layer of the sample (the portion where the subscale is removed from the sample surface and within 50 μm in the thickness direction) and the center layer (the position where the sample is bisected in the thickness direction). It shall be.
The reason for paying attention to the vicinity of the surface layer is that the secondary recrystallized grains are relatively easy to be generated and grown from the vicinity of the surface layer, and the texture at this position is extremely important for producing a good secondary recrystallization. Further, whether secondary recrystallized grains generated near the surface layer can grow in the thickness direction depends on the texture of the central layer. Therefore, the present invention also focuses on the texture of the central layer.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the experimental results on which the present invention is based will be described.
C: 0.050 wt%, Si: 3.00 wt%, Mn: 0.08 wt%, Al: 0.010 wt%, N: 0.005 wt%, S: 0.001 wt%, Se: 0. A plurality of slabs containing 005 wt%, Cu: 0.10 wt%, and Sb: 0.020 wt%, and the balance being Fe and unavoidable impurities were prepared, heated to 1250 ° C., and then hot-rolled to 3.0. It was a hot-rolled coil having a thickness of mm. Next, a part of the hot-rolled coil was collected, subjected to hot-rolled sheet annealing in a laboratory, pickled, and then subjected to a first cold rolling. The thickness of the sheet after the first cold rolling was changed in the range of 0.60 to 2.0 mm. Next, after intermediate annealing at a temperature of 900 to 1100 ° C., after pickling again, a second cold rolling was performed to finish to a final thickness of 0.22 mm. In the second cold rolling, the rolling temperature was changed in a range from normal temperature to 350 ° C.
Thereafter, these rolled sheets were subjected to degreasing treatment, subjected to primary recrystallization annealing also serving as decarburization at 850 ° C. for 120 seconds, applied an annealing separating agent, and then subjected to final finish annealing.
[0026]
After the primary recrystallization annealing, a part of the sample was collected, and the texture near the surface layer and the central layer was measured. By changing the rolling distribution, the intermediate annealing temperature, and the cold rolling temperature in the cold rolling, 22 samples having the primary recrystallization texture changed were prepared. The texture was measured by an X-ray pole figure, and a three-dimensional texture was calculated from the measured data. The three-dimensional texture is φ₁  , Φ, φ₂  In each case, the angle was obtained at 5 ° intervals.
[0027]
After the final finish annealing, the unreacted separating agent was removed, an insulating coating mainly composed of magnesium phosphate containing colloidal silica was applied, and baked at 800 ° C. to obtain a product.
From each product, a test piece of Epstein size was cut out along the rolling direction, and the magnetic flux density B₈  Was measured.
[0028]
Surface texture
From the analysis of the texture of the primary recrystallized annealed sheet, the surface layer (subscale was removed from the sample surface within 50 μm in the thickness direction by rolling and recrystallization in an orientation having an orientation difference of about 30 ° from the Goss orientation. Azimuth that can appear frequently in the part where it enters)₁  = 0 °, Φ = 15 °, φ₂  = 0 ° (hereinafter abbreviated as (0150)) and φ₁  = 5 °, Φ = 20 °, φ₂  = 70 ° (hereinafter abbreviated as (5 20 70)) and φ₁  = 90 °, Φ = 60 °, φ₂  = 45 ° (hereinafter abbreviated as (90 60 45)). However, (0 150), (5 20 70) and (90 60 45) are not always the maximum orientations, and especially the maximum orientations near (0 150) and (520 70) are considerably shifted depending on the process conditions. It turned out to be.
Therefore, the orientation having the maximum near (0150) and (52070) and the magnetic property B of the product₈  When the relationship with (T) was investigated, the results shown in Table 1 were obtained.
[0029]
[Table 1]

[0030]
As shown in the table, when the maximum orientation exists within one or both of 10 ° from (0150) and 10 ° from (5 20 70), the magnetic property B of the product₈  Showed a good value of 1.85 T or more.
However, when no local maximum orientation exists within 10 ° from (0 150) and within 10 ° from (5 20 70), the magnetic characteristic B₈  Was less than 1.85T.
[0031]
Central layer texture
Next, the magnetic properties B of the product₈  Was 1.85 T or more, the texture in the center layer of the sample after the primary recrystallization was further measured, and the relationship with the magnetic properties of the product was investigated. The results shown in Table 2 were obtained.
[0032]
[Table 2]

[0033]
As shown in the table, when the maximum orientation exists within 5 ° from (90 60 45) in the texture of the central layer, the magnetic properties B of the product₈  Is particularly good and is 1.88 T or more, whereas when no local maximum orientation exists within 5 ° from (90 60 45), it was 1.85 to 1.88 T.
[0034]
In the central layer after the primary recrystallization, as a feature in the case where the maximum orientation does not exist within 5 ° from (90 60 45), the texture has a {411} <148> orientation (φ in Bunge's Euler angle display).₁  = 20 °, Φ = 20 °, φ₂  = 45 °. (Hereinafter abbreviated as 20 20 45)), and the primary particle size near the center tended to be coarse.
Further, in the product, there were portions where the secondary grains could not penetrate in the thickness direction.
[0035]
Considering the above experimental results, the texture control can be considered as follows.
(1) In the primary recrystallization texture, it is important to control the texture near the surface layer. This is because secondary recrystallized grains are relatively easy to be generated and grown from near the surface layer, and the texture in this region is very important for producing good secondary recrystallization.
The texture in the vicinity of the surface layer determines whether the Goss orientation can grow to have a size effect compared to the surroundings immediately after the start of grain growth, or conversely, will be eaten by the surroundings.
In order to facilitate the growth of the Goss orientation during the final finish annealing, the frequency of grains having a misorientation of about 30 ° from the Goss orientation should be high. Here, the direction difference is about 30 ° from the Goss direction, and three directions of (0150), (52070) and (906045) frequently appear near the surface layer after the primary recrystallization annealing. Is mentioned.
[0036]
The (0150) orientation tends to develop when the final cold rolling reduction is low. This bearing isAs mentioned above,Heading difference from Goss heading30 °, which is optimal for growing Goss orientation. In addition, this bearingEven if the goth orientation is left without being eaten by the silkworm, the easy magnetization axis <001> is oriented in the rolling direction, so that the magnetic characteristics are not degraded.
Therefore, when the final cold rolling reduction is low, the primary recrystallization texture should be controlled so that the maximum orientation exists near (0150).
[0037]
The (5 20 70) orientation tends to develop when the final cold rolling reduction is relatively high. This azimuth has an azimuth difference of 30 ° from the Goss azimuth, and is optimal for growing the Goss azimuth. Therefore, the probability of remaining in the goth orientation without being eaten by the silkworm is small. Even if the goth orientation remains without being eaten by the silkworm, the deviation between the easy magnetization axis <001> and the rolling direction is only 14 °, so that the magnetic characteristics are not significantly deteriorated. Further, since this orientation has a small orientation dispersion around ND, it is most suitable for growth of just Goss orientation grains, and grains deviated from Goss orientation (particularly grains deviated from Goss orientation which degrades magnetic properties around ND). Has the advantage that it is difficult to grow.
Therefore, when the final cold rolling reduction is high, the primary recrystallization texture should be controlled so that the maximum orientation exists near (5 20 70).
[0038]
The (90 60 45) azimuth generally tends to be the maximum azimuth in the vicinity of the surface layer, and is not particularly controlled in the present invention. However, if the intensity of this direction is too strong, the accumulation in the (0150) direction or (52070) direction relatively weakens, and the local maximum direction near (0150) or (52070). No longer exists. Also, the (90 60 45) orientation has an azimuth difference of 30 ° from the Goss orientation, and is optimal for the growth of the Goss orientation. However, since the azimuth dispersion around ND is large, the grains deviated from the Goss orientation ( In particular, there is a disadvantage that grains which are deviated from the Goss orientation which degrades the magnetic properties around the ND) are also likely to grow.
Therefore, it is not preferable that the (90 60 45) direction becomes extremely large in the surface layer.
[0039]
(2) If the primary recrystallized grain texture of the surface layer is controlled as described above, only the just goth orientation is secondary recrystallized at the time of the final finish annealing, and the magnetic properties of the product are good, but the product is more stable. In order to obtain good magnetic properties, it is important to control the texture of the central layer. The texture of the central layer controls whether or not the secondary grains generated and growing in the surface layer can penetrate without stopping at the center in the thickness direction.
[0040]
In the primary recrystallized grain texture of the central layer, the orientations that are likely to develop are the (90 60 45) orientation and the (20 20 45) orientation. The (90 60 45) orientation has an azimuth difference of 30 ° from the Goss orientation, and the primary particle size tends to be uniform, so that the secondary grains having the Goss orientation generated in the surface layer are optimal for growing. However, in the center layer, the local maximum orientation near (90 60 45) is likely to shift depending on the manufacturing conditions, and is likely to be greatly deviated from (90 60 45).
When the accumulation at (90 60 45) is weakened, the (20 20 45) orientation relatively increases. The (20 20 45) direction has a direction difference of 39 ° from the Goss direction, which is larger than the optimum value of 30 °. In addition, since the (20 20 45) orientation tends to be coarser than the surrounding primary grains, the secondary grains generated in the surface layer are stopped at the center of the sheet thickness.
Therefore, the primary recrystallization texture should be controlled so that the maximum orientation exists near (90 60 45) in the central layer.
[0041]
As described above, the primary recrystallized texture should be controlled separately for the surface layer and the central layer, and the (0150) and (5 20 70) directions in the surface layer, and the (90 60) direction in the central layer. 45) It turned out that attention should be paid to the azimuth.
Both {111} <112> ((90 54.745) direction) and {411} <148> ((20 20 45) direction), which have been noticed in the past, are both the Goss direction and the corresponding direction relationship of {9}. Within the range (Brandon's condition), (0150), (52070), and (906045), which are the objects of the present invention, are not in the range of the corresponding azimuth relationship between the Goss azimuth and Σ9.
[0042]
(90 60 45) is close to {554} <225> in Miller index notation, and is known as an orientation that occurs relatively frequently as the primary recrystallization texture of the BCC metal polycrystalline material (reforming of steel sheet). Crystals and textures: The recrystallization subcommittee of the Iron and Steel Fundamental Research Group in 1974) reported that the primary recrystallization texture of a grain-oriented electrical steel sheet was {111} <112 from the viewpoint of the corresponding orientation relationship with the Goss orientation. > Has attracted attention.
However, the present invention has revealed that the secondary recrystallization of the Goss orientation is independent of the corresponding orientation relationship.
In the present invention, it is important to determine whether the (0150) orientation or the (52070) orientation is the maximum orientation in the surface layer, or whether the (906045) orientation is the maximum orientation in the central layer. The degree is not particularly limited, and it is not limited whether or not there is another strong peak.
[0043]
Next, as a method of controlling the texture of the primary recrystallization annealed sheet, the material components, slab heating conditions, hot rolling conditions, hot rolled sheet annealing conditions, intermediate annealing conditions, and cold rolling conditions (particularly, rolling reduction and rolling Temperature and aging conditions) and primary recrystallization annealing conditions.
As a method of strongly integrating (0150) or (52070) in the surface layer and (906045) in the center layer, for example, the following method is available.
[0044]
Method 1: A method in which the inhibitor component contained in the slab is significantly reduced from the conventional level to increase the grain size of the surface layer portion of the steel sheet before final cold rolling, thereby promoting recrystallization from within the grain.
By promoting recrystallization from within the grains in the surface layer, primary recrystallization of the (0150) orientation or the (52070) orientation becomes frequent.
[0045]
Method 2: A method of increasing the rolling temperature (warm rolling) to promote the recrystallization of the (0150) or (52070) orientation from the band structure in which the <110> direction is aligned with the rolling direction.
The texture change due to warm rolling occurs remarkably in the vicinity of the surface layer, and thus is effective for the texture control of the present invention. In particular, warm rolling in a tandem rolling mill causes shear deformation near the surface layer to promote primary recrystallization in the (0150) orientation and (5 20 70) orientation, while causing uniform deformation in the central layer (90 60 45) It is very effective because it promotes primary recrystallization in the orientation.
[0046]
Method 3: A method of adjusting the final cold rolling reduction according to the material components (particularly the inhibitor components).
This is a method utilizing a combination of the property that the peak of the accumulation of the primary recrystallized texture shifts when the material components are different and the property that the peak of the accumulation of the primary recrystallized texture shifts when the rolling reduction differs.
[0047]
In the present invention, as described above, it is important to control the texture of the primary recrystallization annealed sheet. The control method is not particularly limited, but generally, it is desirable to follow the following manufacturing conditions.
[0048]
First, the component composition range of the material will be described.
C: 0.005 wt% or more and 0.08 wt% or less
C is an element necessary for improving the structure and stabilizing the secondary recrystallization. For this purpose, C is preferably contained in an amount of 0.005 wt% or more. However, if the content exceeds 0.08 wt%, not only breakage during cold rolling increases, but also the annealing time required for decarburization becomes longer and productivity is reduced, so it is preferable to set the content to 0.08 wt% or less.
[0049]
Si: 2.0 wt% or more and 4.5 wt% or less
Si is an indispensable element for increasing electric resistance and reducing iron loss. For this purpose, it is necessary to contain Si in an amount of 2.0 wt% or more, but if it exceeds 4.5 wt%, workability deteriorates. Since it becomes extremely difficult to manufacture and process the product, it is preferable that the content is in the range of 2.0 wt% or more and 4.5 wt% or less.
[0050]
Mn: 0.03 wt% or more and 2.5 wt% or less
Mn is also an element useful for increasing electric resistance and improving hot workability at the time of production. For this purpose, a content of 0.03 wt% or more is necessary. However, if the content exceeds 2.5 wt%, γ transformation is induced to deteriorate magnetic properties. , 2.5 wt% or less.
[0051]
Inhibitor component
Al, Se, S, Sb, Sn and the like are added as necessary to function as an inhibitor. In this case, the addition amounts of these elements are as follows: Al: 0.003 to 0.050 wt%, Se: 0.003 to 0.050 wt%, S: 0.003 to 0.050 wt%, Sb: 0. 0.001 to 0.3 wt%, and Sn: preferably about 0.001 to 0.3 wt%.
[0052]
Al acts as an inhibitor in combination with N as AlN. In order to function effectively as an inhibitor, it is necessary to form a solid solution at the time of slab heating before hot rolling and to precipitate finely in a subsequent step, but if the content exceeds 0.050 wt%, a solid solution at the time of slab heating is required. However, if the content is less than 0.003 wt%, the amount of the inhibitor is insufficient and the effect cannot be exhibited. Therefore, it is preferable to contain the inhibitor in the range of 0.003 to 0.050 wt%.
[0053]
Se and S are combined with Mn to play an inhibitor role as MnSe and MnS. In order to function effectively as an inhibitor, as in the case of Al, it is necessary to form a solid solution during slab heating before hot rolling and to precipitate finely in a subsequent step. When the solid solution is insufficient, the amount of the inhibitor is insufficient if the amount is less than 0.003 wt%, so that the effect cannot be exhibited.
[0054]
Sb and Sn segregate at the grain boundaries and function as inhibitors. In order to function sufficiently as an inhibitor, the content must be 0.001% by weight or more. However, if it exceeds 0.3% by weight, mechanical properties such as bend characteristics of a product are deteriorated. It is preferable that the content be contained in the range of 0.3 wt%.
[0055]
As an inhibitor, Cr, Cu, Nb, B or the like can be added in addition to the above elements. The amount of addition should be within a range where the inhibitor function can be sufficiently exhibited and the mechanical properties such as bend properties of the product are not deteriorated. Cr: 0.001 to 0.3 wt%, Cu: 0.005, respectively. ０．５0.5 wt%, Nb: 0.001 -0.3 wt%, B: 0.0001-0.05 wt%.
Recently, a technique for causing secondary recrystallization by utilizing the orientation difference dependence of grain boundary mobility without particularly adding an inhibitor element has been reported. It is a technology that can be adapted.
[0056]
Next, the manufacturing process will be described.
Hot rolling process
The slab adjusted to the above component composition is subjected to slab heating according to an ordinary method, and then hot-rolled into a hot-rolled coil.
In recent years, a method has been proposed in which hot rolling is performed directly after continuous casting without performing slab heating, but this method can also be applied to the present invention.
[0057]
Hot rolled sheet annealing process
The hot-rolled coil is subjected to hot-rolled sheet annealing at a temperature in the range of 800 to 1150 ° C., if necessary, for homogenization of the structure and fine precipitation of the inhibitor.
[0058]
Cold rolling / intermediate annealing process
The hot-rolled coil or the steel sheet after the hot-rolled sheet annealing is subjected to cold rolling once or twice or more with intermediate annealing to obtain a product sheet thickness. The cold rolling may be performed by a tandem rolling mill or a Sendzimir rolling mill. Rolling may be performed at room temperature, or, if necessary, at a temperature higher than room temperature, and the texture can be controlled using dynamic strain aging during rolling or static strain aging between passes. It is.
[0059]
Decarburization and primary recrystallization annealing process
The steel sheet rolled to the product thickness is annealed for decarburization and primary recrystallization.
[0060]
The primary recrystallized annealed sheet thus obtained is used as an intermediate material for producing a grain-oriented electrical steel sheet.
Thereafter, generally, an annealing separating agent is applied, finish annealing is performed, and then, if necessary, an insulating coating is applied and baked, and further flattening annealing is performed to obtain a product.
[0061]
【Example】
Example 1
C: 0.035 wt%, Si: 2.90 wt%, Mn: 0.08 wt%, Al: 0.003 wt%, N: 0.003 wt%, S: 0.001 wt%, Se: 0. A plurality of slabs each containing 020 wt%, Cu: 0.01 wt% and Sb: 0.020 wt%, and the balance being Fe and unavoidable impurities were prepared, heated to 1250 ° C., and then hot-rolled to 3.0 mm A thick hot-rolled coil was used. Next, after pickling, the first cold rolling was performed by a tandem rolling mill. The thickness of the sheet after the first cold rolling was changed in the range of 0.50 to 2.0 mm. Next, after intermediate annealing at a temperature of 900 to 1100 ° C., after pickling again, a second cold rolling was performed with a Sendzimir rolling mill to finish to a final sheet thickness of 0.22 mm. In the second cold rolling, the rolling temperature was changed in a range from 80 ° C to 300 ° C.
Thereafter, a degreasing treatment was performed, and a primary recrystallization annealing serving also as decarburization at 800 to 880 ° C. for 120 seconds was performed.
Thus, a primary recrystallization annealed sheet having a significantly changed texture was obtained as shown by the symbols A to in Table 3.
A part of these primary recrystallization annealed sheets was sampled, and the texture near the surface layer was measured. The texture was measured by an X-ray pole figure, and a three-dimensional texture was calculated from the measured data. The three-dimensional texture is φ₁  , Φ, φ₂  In each case, the angle was obtained at 5 ° intervals.
[0062]
Next, an annealing separator was applied to these primary recrystallization annealed plates, and then a final finish annealing was performed. After the final finish annealing, after removing the unreacted separating agent, an insulating coating mainly composed of magnesium phosphate containing colloidal silica was applied and baked at 800 ° C. to obtain a product.
From each product, a test piece of Epstein size was cut out along the rolling direction, and the magnetic flux density B₈  Was measured.
Table 3 shows the maximum orientation of the texture in the vicinity of the surface layer of the primary recrystallization annealed sheet and the magnetic flux density B of the product.₈  Is shown.
[0063]
[Table 3]

[0064]
As shown in the table, according to the present invention, by using a primary recrystallization annealed plate having a surface layer having a maximum orientation within 10 ° from (0150) [or (5 20 70)], Magnetic flux density B₈  Was 1.85T or more.
[0065]
Next, the magnetic properties B of the product₈  Was 1.85 T or more, the texture in the center layer of the sample after the primary recrystallization was further measured, and the relationship with the magnetic properties of the product was examined.
Table 4 shows the maximum orientation in the texture of the central layer and the magnetic properties B of the product.₈  Shows the relationship with
[0066]
[Table 4]

[0067]
As shown in the table, when the texture of the central layer has the maximum orientation within 5 ° from (90 60 45), the magnetic property B₈  Was stabilized, and a good value of 1.88 T or more was obtained.
[0068]
Example 2
C: 0.045 wt%, Si: 3.25 wt%, Mn: 0.08 wt%, Al: 0.007 wt%, N: 0.004 wt%, S: 0.002 wt%, Se: 0. A plurality of slabs containing 001 wt%, Cu: 0.01 wt%, Sb: 0.010 wt% and Sn: 0.05 wt% are prepared, and the remainder is made up of a plurality of slabs composed of Fe and unavoidable impurities. Rolling was performed to form a 2.5 mm thick hot-rolled coil. Then, after annealing of the hot-rolled sheet, the sheet was pickled and then cold pressed once by a tandem rolling mill to a thickness of 0.34 mm. At this time, the hot-rolled sheet annealing temperature was changed in the range of 800 to 1150 ° C, and the cold rolling temperature was changed in the range of 80 to 300 ° C.
Thereafter, a degreasing treatment was performed, and a primary recrystallization annealing serving also as decarburization at 800 to 880 ° C. for 120 seconds was performed.
Thus, a primary recrystallization annealed sheet having a significantly changed texture as shown in Table 5 by numbers 1 to 20 was obtained.
A part of these primary recrystallization annealed sheets was sampled, and the texture near the surface layer was measured. The texture was measured by an X-ray pole figure, and a three-dimensional texture was calculated from the measured data. The three-dimensional texture is φ₁  , Φ, φ₂  In each case, the angle was obtained at 5 ° intervals.
[0069]
Next, an annealing separator was applied to these primary recrystallization annealed plates, and then a final finish annealing was performed. After the final finish annealing, the unreacted separating agent was removed, and then an insulating coating mainly composed of magnesium phosphate containing colloidal silica was applied and baked at 800 ° C. to obtain a product.
From each product, a test piece of Epstein size was cut out along the rolling direction, and the magnetic flux density B₈  Was measured.
Table 5 shows the maximum orientation of the texture near the surface layer of the primary recrystallization annealed sheet and the magnetic flux density B of the product.₈  Is shown.
[0070]
[Table 5]

[0071]
As shown in the table, according to the present invention, by using a primary recrystallization annealed plate having a surface layer having a maximum orientation within 10 ° from (0150) [or (5 20 70)], Magnetic flux density B₈  Was 1.85T or more.
[0072]
Next, the magnetic properties B of the product₈  Was 1.85 T or more, the texture in the center layer of the sample after the primary recrystallization was further measured, and the relationship with the magnetic properties of the product was examined.
Table 6 shows the maximum orientation in the texture of the central layer and the magnetic properties B of the product.₈  Shows the relationship with
[0073]
[Table 6]

[0074]
As shown in the table, when the texture of the central layer has the maximum orientation within 5 ° from (90 60 45), the magnetic property B₈  Was stabilized, and a good value of 1.88 T or more was obtained.
[0075]
Example 3
C: 0.060 wt%, Si: 3.25 wt%, Mn: 0.09 wt%, Al: 0.027 wt%, N: 0.009 wt%, S: 0.002 wt%, Se: 0. A plurality of slabs containing 020 wt%, Cu: 0.10 wt% and Sb: 0.025 wt%, the remainder being Fe and unavoidable impurities were prepared, heated to 1400 ° C., and then hot-rolled to 2.5 mm A thick hot-rolled coil was used. Subsequently, after performing hot-rolled sheet annealing maintained at 800 to 1150 ° C. for 60 seconds, pickling, first cold rolling at room temperature to a thickness of 1.7 mm by a tandem rolling mill, and then 950 ° C. After the intermediate annealing at the temperature, pickling was performed again, and the second cold rolling was performed to a thickness of 0.22 mm by a Sendzimir rolling mill. In the second cold rolling, the rolling temperature was changed in the range of 80 to 300 ° C. Thereafter, a degreasing treatment was performed, and a primary recrystallization annealing serving also as decarburization at 800 to 880 ° C. for 120 seconds was performed.
Thus, a primary recrystallization annealed sheet whose texture was greatly changed, as shown by symbols A to N in Table 7, was obtained.
A part of these primary recrystallization annealed sheets was sampled, and the texture near the surface layer was measured. The texture was measured by an X-ray pole figure, and a three-dimensional texture was calculated from the measured data. The three-dimensional texture is φ₁  , Φ, φ₂  In each case, the angle was obtained at 5 ° intervals.
[0076]
Next, an annealing separator was applied to these primary recrystallization annealed plates, and then a final finish annealing was performed. After the final finish annealing, the unreacted separating agent was removed, and then an insulating coating mainly composed of magnesium phosphate containing colloidal silica was applied, and baked at 800 ° C. to obtain a product.
From each product, a test piece of Epstein size was cut out along the rolling direction, and the magnetic flux density B₈  Was measured.
Table 7 shows the maximum orientation of the texture near the surface layer of the primary recrystallization annealed sheet and the magnetic flux density B of the product.₈  Is shown.
[0077]
[Table 7]

[0078]
As shown in the table, a product having a good magnetic flux density was obtained by using the primary recrystallization annealed plate satisfying the requirements of the present invention.
[0079]
Next, the magnetic properties B of the product₈  Was 1.85 T or more, the texture in the center layer of the sample after the primary recrystallization was further measured, and the relationship with the magnetic properties of the product was examined.
Table 8 shows the maximum orientation in the texture of the central layer and the magnetic properties B of the product.₈  Shows the relationship with
[0080]
[Table 8]

[0081]
As shown in the table, when the texture of the central layer has the maximum orientation within 5 ° from (90 60 45), the magnetic property B₈  Is stable, and a good value of 1.88 T or more is obtained.
[0082]
【The invention's effect】
Thus, according to the present invention, by appropriately controlling the texture of the primary recrystallization annealed sheet, it has become possible to stably produce a grain-oriented electrical steel sheet having good magnetic properties.

Claims (3)

One direction characterized in that the texture in the vicinity of the surface layer of the steel sheet has a local maximum orientation within 10 ° from the orientation of φ ₁ = 0 °, φ = 15 °, φ ₂ = 0 ° in Bunge's Euler angle notation. Primary recrystallization annealed sheet for conductive electrical steel sheets. The texture near the surface layer of the steel sheet is within 10 ° from the orientation of φ ₁ = 0 °, φ = 15 °, φ ₂ = 0 °, or φ ₁ = 5 °, φ = 20 ° in Bunge's Euler angle notation. , Φ ₂ = 70 °, has a local maximum orientation within 10 °, and the texture of the central layer of the steel sheet is also φ ₁ = 90 °, φ = 60 °, φ _{2 in} Bunge's Euler angle representation. A primary recrystallization-annealed sheet for a grain-oriented electrical steel sheet, having a maximum orientation within 5 ° from an orientation of = 45 °. C: 0.005 to 0.08 wt%,
Si: 2.0 to 4.5 wt%,
Mn: 0.03 to 2.5 wt%
And Al: 0.003 to 0.050 wt%,
Se: 0.003 to 0.050 wt%,
S: 0.003 to 0.050 wt%,
Sb: 0.001 to 0.3 wt%,
Sn: 0.001 to 0.3 wt%
After hot-rolling a silicon steel slab having a composition containing one or more selected from among them, subjecting it to hot-rolled sheet annealing as necessary, cooling it once or two or more times with intermediate annealing The primary recrystallized and annealed sheet for a grain-oriented electrical steel sheet according to claim 1 or 2, which is obtained by subjecting the sheet to a final thickness by cold rolling and then performing primary recrystallization annealing.