JP3754158B2 - Method for producing grain-oriented electrical steel sheet - Google Patents

Description

【００１９】
図４に示したとおり、追加酸化量が低い供試材はNo.4〜６であり、それ以外の供試材では追加酸化量が多いことがわかる。追加酸化量の増加は、フォルステライトの生成挙動に悪影響を及ぼすと共に、インヒビターの酸化・分解につながることから、磁気特性の劣化を招き易い。この酸化の受け易さは、炭炭・１次再結晶焼鈍により生成するサブスケールの品質に左右される。
供試材No.1〜３は、サブスケールの酸素目付け量が低いために、追加酸化量が増大している。
また、供試材No.7〜９は、電解電着量が高いだけでなく、サブスケールの酸素目付け量も非常に高い。しかも、サブスケールの酸素目付け量は高いものの、サブスケールの耐追加酸化性は低いことから、追加酸化量も増大している。
【００２０】
そこで、発明者らは、次に、脱炭・１次再結晶焼鈍後のサブスケール品質および仕上げ焼鈍中の追加酸量が変化する要因について調査した。
その結果、供試材No.1〜３では中間焼鈍板の脱Si層が増加していること、また供試材No.7〜９では中間焼鈍後に表層酸化物が多量に残存していることが判明し、これらが製品品質の劣化原因であることが判明した。
このことは中間焼鈍板のグロー放電分光分析により求められるSi, Ｏの表面と地鉄の積算強度比により評価することができる。
なお、供試材No.7〜９は、サブスケールの酸素目付け量が非常に高いため、グラス被膜の欠陥も生じ易い不利がある。
【００２１】
上述したとおり、中間焼鈍板の表面酸化層の残存量が増加すると脱炭・１次再結晶焼鈍前の鋼板表面の性状が劣化する。すなわち、中間焼鈍板の表面酸化層が厚いまま圧延されるために鋼板表面が荒れ、また汚れが付着するだけでなく電解脱脂時に電解電着されるSi化合物量が増加するため、サブスケールの酸素目付け量が増加し易い。このような酸素目付け量の増加またはコイル長手・幅方向での不均一な増加は、仕上げ焼鈍中におけるフォルステライト質グラス被膜の生成挙動に悪影響を及ぼし、点状に局所的に被膜が欠落する被膜欠陥の発生頻度が増加する。
【００２２】
このように中間焼鈍板の表面性状が次工程の品質に影響を及ぼすため、中間焼鈍板の表面性状を管理することは重要である。本発明で利用するグロー放電分光法は、簡便でしかも迅速性に富むことから、ラインの条件変動や鋼板の表面状態をすばやくチェックする上で極めて有効である。
【００２３】
ここに、均熱時における焼鈍雰囲気および焼鈍温度がSiO₂が生成する条件で中間焼鈍を施した場合には、中間焼鈍板の表面酸化層中におけるSiおよびＯ量は、グロー放電分光法で測定した積算強度比で、それぞれ 1.1〜2.3 の範囲に制御する必要がある。
というのは、前掲図３に示したように、積算強度比がそれぞれ 1.1に満たない場合には磁気特性の劣化を招き、一方 2.3を超える場合にはグラス被膜品質の劣化を招くからである。
【００２４】
次に、中間焼鈍の均熱時における焼鈍雰囲気および均熱温度が、Fe₂SiO₄ 生成域以上の酸化性である場合について説明する。なお、インヒビターの主成分としてはAlＮを用いた。
中間焼鈍板のSiおよびＯの元素プロファイルをグロー放電分光法により求め、換算深さ２μm に相当する間隔で表面近傍と地鉄部分についてSiおよびＯの積算強度ひいては積算強度比をそれぞれ求め、得られた積算強度比を用いて規格化した結果を、図５に示す。
なお、中間焼鈍後、二次冷間圧延前の鋼板の表面酸化層中のSi，Ｏは、冷却後のブラシロールおよび研削弾性ロール等の機械的な研磨および酸洗条件の組み合わせにより表面酸化層を除去することによって、種々に変化させた。
【００２５】
また、図６は、図５中に示された材料の製品品質についての調査結果を付加して示したものである。
同図より、中間焼鈍板の表面Si, Ｏ濃度には、製品品質を良好なものにする好適範囲があることが判る。
そこで次に、中間焼鈍板の表面性状が製品の磁気特性およびグラス被膜に及ぼす影響について調査した。
SiおよびＯがそれぞれ、表２に示す積算強度比になる９個の中間焼鈍板（板厚：1.5 mm、インヒビター主成分：AlＮ, Sb）を供試材として、冷間圧延により最終板厚：0.22mmに仕上げた後、市販のアルカリ脱脂浴剤を用いた脱脂浴で浸漬脱脂を行い、ついで均熱温度：840 ℃、均熱時間：120 秒、昇熱から均熱入りまでの酸化性（Ｐ(H₂O)/Ｐ(H₂)）＝0.38、均熱時の酸化性（Ｐ(H₂O)/Ｐ(H₂)）＝0.42の条件下で脱炭・１次再結晶焼鈍を実施した。この脱炭焼鈍板を、濃度：５％、液温：60℃の塩酸溶液に60秒浸漬し、浸漬前後の試料重量から酸溶解減量を求めた。
得られた結果を酸素目付け量と共に図７に示す。
【００２６】
【表２】

【００２７】
図７に示したとおり、酸溶解減量が低い供試材はNo.14 〜16であり、それ以外の供試材では酸溶解減量が多いことが判る。酸溶解減量の増加は、フォルステライトの生成挙動に悪影響を及ぼすと共にインヒビターの酸化・分解や仕上げ焼鈍途中での過窒化につながることから、磁気特性の劣化を招き易い。この酸溶解減量の大小は脱炭・１次再結晶焼鈍により生成するサブスケール品質の物性に左右される。
そこで、次に、脱炭焼鈍板の酸溶解量が増大する原因について調査した結果、供試材No.11 〜13では中間焼鈍板の脱Si層が増大していること、供試材No.17 〜19では中間焼鈍後の表層酸化物が多量に残存していることが品質劣化の原因であることが判明した。
【００２８】
このように、脱Si層が増大したり、表層酸化物の残存量が増大すると、仕上げ焼鈍中におけるフォルステライト質グラス被膜の生成挙動が悪化することは前述したとおりである。
従って、かような弊害が生じないように、中間焼鈍板の表面性状を管理する必要がある。
ここに、均熱時における焼鈍雰囲気および焼鈍温度が Fe₂SiO₄生成域以上の酸化性である場合には、中間焼鈍板の表面酸化層中におけるSiおよびＯ量は、グロー放電分光法で測定した積算強度比で、それぞれ 0.7〜1.2 ，0.95〜1.12の範囲に制御する必要がある。
というのは、前掲図６に示したように、Si，Ｏの積算強度比がそれぞれ 0.7, 0.95に満たなかったり、 1.2, 1.12を超えた場合には、グラス被膜の劣化のみならず、磁気特性の劣化を招くからである。
【００２９】
なお、グロー放電分光により得られたSi, Ｏプロファイルから、表面近傍および地鉄の積算強度をそれぞれ求める際の換算深さは、中間焼鈍の均熱時における雰囲気および温度に応じて調整する必要がある。
すなわち、中間焼鈍の均熱時における雰囲気および温度がSiO₂生成域内の酸化性である場合には、図１に示したように、最表面からの換算深さが０〜0.5 μmまでを表面近傍、また 1.0〜1.5 μm までを地鉄部として、地鉄部に対する表面近傍のSi, Ｏの強度比を所定の範囲内に制御することが好ましい。
一方、中間焼鈍の均熱時における雰囲気および温度が Fe₂SiO₄生成域以上の酸化性である場合には、最表面からの換算深さが０〜２μm までを表面近傍、また４〜６μm までを地鉄部として、地鉄部に対する表面近傍のSi, Ｏの強度比を所定の範囲内に制御することが好ましい。
ここで、換算深さとは、一定時間スパッタしたのちに粗度計によりスパッタした深さを測定し、この値から単位時間当たりスパッタした深さを算出し、この値にスパッタ時間をかけた値のことである。
【００３０】
次に、この発明で対象とする電磁鋼板用素材の成分組成の好適範囲について説明する。
Ｃ：0.02〜0.10wt％
Ｃは、組織改善に有効な元素であるが、上記の範囲を外れると良好な集合組織を得ることが困難となる。
【００３１】
Si：2.0 〜4.5 wt％
Si量が、2.0 wt％に満たないと渦電流損の低減効果が減少し、一方4.5 wt％を超えると冷間圧延性が損なわれる。
【００３２】
これらの成分の他にインヒビター形成成分を含有する。
インヒビターとしてMnＳおよび／またはMnSeを用いる場合は、Mn：0.03〜0.1 wt％、Ｓ＋Se：0.01〜0.03wt％にする。
一方、AlＮをインヒビターとして用いる場合は、Al：0.01〜0.04wt％、Ｎ：0.0050〜0.0120wt％とする。
というのは、上記の範囲よりも低い含有量ではインヒビターとしての効果が不十分であり、一方高いと２次再結晶が不安定になるからである。
また、これらの他に、Cu, Sn, Sb, Ge, Mo, Te, Bi, Ｐ，ＶおよびNbなども適用することができ、さらに各インヒビターは単独使用、複数使用のいずれも可能である。
【００３３】
【実施例】
実施例１
インヒビターがMnSe, Sb系である方向性電磁鋼板用素材（Ｃ：0.039 wt％、Si：3.4 wt％、Mn：0.07wt％、Se：0.020 wt％、Sb：0.024 wt％、Ｓ：0.002 wt％）を、2.0 mmに熱間圧延し、1000℃, 30秒の均一化焼鈍後、１次冷延により板厚：0.6 mmに圧延したのち、950 ℃, 60秒の中間焼鈍（SiO₂生成条件）を施した。中間焼鈍時に鋼板表面に形成される酸化層を、酸洗、酸洗＋ブラシロール研磨、酸洗＋弾性ロール研磨の各条件で除去した。
なお、表面除去量は、酸洗濃度・温度、ブラシロール研磨および弾性ロール研磨の砥粒番定や回転速度などを変更させることによって変化させた。
ついで、グロー放電分光法により、中間焼鈍板のSi, Ｏプロファイルを測定し、換算深さ：0.5 μm に相当する間隔で表面近傍と地鉄部分について測定元素の積算強度をそれぞれ求めた。
【００３４】
次に、２次冷延により板厚：0.22mmの最終板厚に仕上げたのち、湿水素雰囲気中にて 830℃, 120 秒の脱炭・１次再結晶焼鈍を施した。その後、MgＯ：100 重量部に対しTiO₂：２重量部、 SrSO₄：1.5 重量部を添加した焼鈍分離剤を塗布してから、 845℃, 50時間の２次再結晶焼鈍引き続き1180℃, ５時間の純化焼鈍を施した。
かくして得られた鋼板のグラス被膜密着性・均一性および磁気特性（Ｗ_17/50 、Ｂ₈)について調べた結果を、表３に示す。
なお、グラス被膜の密着性は鋼板を種々の直径を持つ丸棒に巻き付け、被膜剥離が起こらない最小の丸棒の直径で示した。
【００３５】
【表３】

【００３６】
同表より明らかなように、中間焼鈍板のグロー放電分光分析により求められるSi, Ｏの積算強度比を、この発明の適正範囲内に制御することによって、グラス被膜および磁気特性とも極めて良好な結果を得ることができた。
なお、中間焼鈍の表面酸化層の除去方法が、酸洗、酸洗＋砥粒入りブラシロール研磨、酸洗＋砥粒入り弾性ロールおよびディスクによる機械研磨などの手段に係わらず、グロー放電分光分析により求められるSi, Ｏの積算強度比が、所定の範囲にあれば良好な結果が得られることが判る。
【００３７】
実施例２
インヒビターがAlＮ, Sb系である方向性電磁鋼板用素材（Ｃ：0.070 wt％、Si：3.3 wt％、Mn：0.07wt％、Se：0.023 wt％、Sb：0.024 wt％、Ｓ：0.002 wt％、sol.Al：0.023 wt％、Ｎ：0.0083wt％）を、2.4 mmに熱間圧延し、1000℃, 30秒の均一化焼鈍後、１次冷延により板厚：1.5mm に圧延したのち、1100℃, 90秒の中間焼鈍を施した。中間焼鈍の均熱帯の酸化性を Fe₂SiO₄またはFeO が生成する範囲とし、中間焼鈍時に鋼板表面に形成される酸化層を、酸洗、酸洗＋ブラシロール研磨、酸洗＋弾性ロール研磨の各条件で除去した。
なお、表面除去量は、酸洗濃度・温度、ブラシロール研磨および弾性ロール研磨の砥粒番定や回転速度などを変更させることで変化させた。
ついで、グロー放電分光法により、中間焼鈍板のSi, Ｏプロファイルを測定し、換算深さ：2.0 μm に相当する間隔で表面近傍と地鉄部分について測定元素の積算強度をそれぞれ求めた。
【００３８】
次に、２次冷延により板厚：0.22mmの最終板厚に仕上げたのち、湿水素雰囲気中にて 840℃, 120 秒の脱炭・１次再結晶焼鈍を施した。その後、MgＯ：100 重量部に対しTiO₂：10重量部、 Sr(OH)₂：３重量部を添加した焼鈍分離剤を塗布してから、 850℃, 15時間の１次保定焼鈍し、ついで 850℃〜1150℃まで窒素＋水素の混合雰囲気中で昇熱速度：12.5℃／ｈで昇熱し、引き続き水素雰囲気中にて1180℃, ５時間の純化焼鈍を施した。
かくして得られた鋼板のグラス被膜密着性・均一性および磁気特性（Ｗ_17/50 、Ｂ₈)について調べた結果を、表４に示す。
なお、グラス被膜の密着性は鋼板を種々の直径を持つ丸棒に巻き付け、被膜剥離が起こらない最小の丸棒の直径で示した。
【００３９】
【表４】

【００４０】
同表より明らかなように、中間焼鈍板のグロー放電分光分析により求められるSi, Ｏの積算強度比が、この発明の適正範囲を満足する場合には、優れたグラス被膜および磁気特性を得ることができた。
【００４１】
【発明の効果】
かくして、この発明に従い、中間焼鈍板の表面酸化層中におけるSiおよびＯ量を所定の範囲に制御することによって、グラス被膜特性および磁気特性に優れた方向性電磁鋼板を安定して得ることができる。
【図面の簡単な説明】
【図１】グロー放電分光法により得られる中間焼鈍板のSi，Ｏプロファイルと測定元素の表面および地鉄の積算強度の求め方を示す図である。
【図２】工場ラインより採取した中間焼鈍板のグロー放電分光法により求められるSi，Ｏの表面と地鉄の積算強度比を示す図である。
【図３】図２に示した中間焼鈍板の製品特性を示す図である。
【図４】供試材の電解脱脂後のSi化合物電着量、脱炭・１次再結晶焼鈍後の酸素目付け量および仕上げ焼鈍途中での追加酸化量を示す図である。
【図５】工場ラインより採取した中間焼鈍板のグロー放電分光法により求められるSi，Ｏの表面と地鉄の積算強度比を示す図である。
【図６】図５に示した中間焼鈍板の製品特性を示す図である。
【図７】供試材の脱炭・１次再結晶焼鈍後の酸素目付け量および酸溶解減量を示す図である。[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for producing a grain-oriented electrical steel sheet, and in particular, the Si and O amounts in the surface oxide layer of a steel sheet after intermediate annealing and before secondary cold rolling (hereinafter simply referred to as intermediate annealed sheet) within an appropriate range. By controlling, it is intended to advantageously improve the magnetic properties and glass coating properties of the product plate.
[0002]
[Prior art]
The grain-oriented electrical steel sheet is used as a soft magnetic material mainly as an iron core material such as a transformer or a rotary machine, and is required to have high magnetic flux density and small iron loss and magnetostriction as magnetic characteristics.
Except for special cases, a forsterite (Mg ₂ SiO ₄ ) glassy glass film is generally formed on the surface of such grain oriented electrical steel sheet. This coating contributes not only to the electrical insulation of the surface but also to the improvement of iron loss and magnetostriction by applying tensile tension due to its low thermal expansibility to the steel sheet.
[0003]
The glass coating described above is formed by finish annealing, but its formation behavior affects the behavior of inhibitors such as MnS, MnSe, and AlN in steel. It also affects secondary recrystallization itself, which is an essential process.
Further, the formed glass film has a function of sucking up the inhibitor component that is no longer necessary after the completion of the secondary recrystallization into the glass film, thereby purifying the steel, and helps to reduce the hysteresis loss of the steel sheet.
Therefore, uniform formation of the glass coating is one of the important points that affects the product quality of the grain-oriented electrical steel sheet.
[0004]
The formed glass film must be uniform and free of defects, and should have excellent adhesion to withstand shearing, punching and bending.
It must also be smooth and have a high occupancy when laminated on an iron core.
[0005]
In order to form a glass coating on the surface of grain-oriented electrical steel sheets, cold rolling to the desired final thickness, followed by decarburization and primary recrystallization annealing, that is, continuous at 700-900 ° C in wet hydrogen By annealing, the structure after cold rolling is recrystallized first, C causing magnetic aftereffect is reduced as much as possible, and at the same time, a subscale mainly composed of silica is formed on the steel sheet surface by oxidation, After that, after applying an annealing separator mainly composed of MgO on the steel sheet, it is wound on a coil and subjected to high-temperature finish annealing at a temperature of about 1000 ° C. to 1200 ° C. in a reducing or non-oxidizing atmosphere. Is done.
Thus, a glassy insulating film called forsterite represented by the following formula is formed.
2MgO + SiO ₂ → Mg ₂ SiO ₄
This glass coating is a ceramic coating in which fine crystals of about 1 micron are densely integrated.
[0006]
As described above, the forsterite glass coating is produced using an oxide called a sub-scale generated on the steel sheet surface layer in decarburization and primary recrystallization annealing as a raw material. And the like not only affect the nucleation and grain growth behavior of forsterite, but also affect the mechanical strength of the glass coating, and thus greatly affect the coating quality after finish annealing.
[0007]
In addition, the annealing separator mainly composed of MgO, which is the other raw material of the glass coating, is generally applied to the steel sheet as a slurry suspended in water. Therefore, even after drying, in addition to holding H ₂ O physically adsorbed on the surface, part of it hydrates and changes to Mg (OH) ₂ . Since these H ₂ Os continue to be released in a small amount up to around 800 ° C during finish annealing, the steel plate surface is oxidized.
Such an oxidation phenomenon is called additional oxidation, which affects the forsterite formation behavior and leads to oxidation / decomposition of the inhibitor. The susceptibility to this oxidation depends on the quality (physical properties) of the subscale produced by decarburization and primary recrystallization annealing.
[0008]
In order to improve the quality of such subscales, several methods have been proposed so far.
For example, Japanese Patent Application Laid-Open No. 50-71526 discloses that the surface of the final cold rolled sheet before decarburization and primary recrystallization annealing is pickled at 3 g / m ² or more to remove surface deposits, A method for forming a uniform glass film and improving adhesion is described.
JP-A-57-101673 discloses that the surface of the final cold rolling before decarburization and primary recrystallization is removed by 0.025 to 0.5 g / m ² grinding or pickling. And a method for obtaining a film having excellent adhesion is described.
Furthermore, in JP-A-7-54154, after the intermediate annealing in the cold rolling process, before the deoxidation / primary recrystallization annealing, the surface layer of the amount represented by the following formula is removed,
A ≧ (0.65 × B-543) × C
Where A: surface layer to be removed (g / m ² )
B: Intermediate annealing temperature (° C)
C: Thickness before removal of surface layer (mm)
A method for obtaining a uniform forsterite coating is disclosed.
[0009]
[Problems to be solved by the invention]
However, even with these methods, the quality of the subscale formed after decarburization and primary recrystallization annealing still varies, and as a result, the magnetic properties and glass coating quality may not be stable, and improvements are desired. It was.
The present invention advantageously responds to the above requirements, and by stabilizing the amount of Si and O in the intermediate annealing before decarburization and primary recrystallization, it stabilizes the film quality and magnetic properties of the product. It is an object of the present invention to propose an advantageous method for producing a grain-oriented electrical steel sheet.
[0010]
[Means for Solving the Problems]
Now, in order to achieve the above object, the inventors have not only the quality of the subscale formed after decarburization / primary recrystallization and the quality of the glass coating formed after finish annealing, but also the decarburization / primary. A thorough examination was conducted on the surface state of the steel sheet in each step before recrystallization.
As a result, it was found that the surface oxide layer after the intermediate annealing (that is, the surface oxide layer before the final cold rolling) has a strong correlation with the product quality.
Therefore, as a result of intensive studies on a method capable of quickly and accurately evaluating the surface oxide layer state, the inventors have come up with the idea of using glow discharge spectroscopy. Using this glow discharge spectroscopy, the amounts of Si and O after intermediate annealing are considered. It was found that the desired object can be effectively achieved by accurately controlling the value within a predetermined range.
The present invention is based on the above findings.
[0012]
That is, the gist configuration of the present invention is as follows.
1. Hot-roll silicon-containing steel, then cold-roll twice with intermediate annealing to finish to the final thickness, then decarburize and anneal in wet hydrogen, then apply annealing separator Then, in producing grain-oriented electrical steel sheets by a series of processes that perform finish annealing,
When the atmosphere and temperature during soaking of the intermediate annealing are within the SiO ₂ generation region, the Si and O amounts in the surface oxide layer of the steel sheet after the intermediate annealing and before the secondary cold rolling are determined according to the grinding conditions after the intermediate annealing and By removing the surface oxide layer under at least one of the pickling conditions, the integrated intensity ratio in the vicinity of the surface with respect to the iron and steel portion of Si and O measured by glow discharge spectroscopy is in the range of 1.1 to 2.3, respectively. A method for producing a grain-oriented electrical steel sheet, characterized in that the control is carried out.
Here, the ground iron part refers to a range of 1.0 to 1.5 μm in conversion depth from the surface, and the vicinity of the surface refers to a range of 0 to 0.5 μm in conversion depth from the surface.
[0013]
2. Hot-roll silicon-containing steel, then cold-roll twice with intermediate annealing to finish to the final thickness, then decarburize and anneal in wet hydrogen, then apply annealing separator Then, in producing grain-oriented electrical steel sheets by a series of processes that perform finish annealing,
If the atmosphere and temperature at the time of soaking of the intermediate annealing is Fe ₂ SiO ₄ generation region more oxidizing, after intermediate annealing, Si and O content in the surface oxide layer of the secondary cold rolling before the steel plate, the intermediate By removing the surface oxide layer according to at least one of the grinding conditions and the pickling conditions after annealing, the integrated intensity ratio in the vicinity of the surface with respect to the iron and steel portion of Si and O measured by glow discharge spectroscopy, A method for producing grain-oriented electrical steel sheets, characterized in that each is controlled in the range of 0.7 to 1.2 and 0.95 to 1.12.
Here, the ground iron part means a range of 4 to 6 μm in converted depth from the surface, and the vicinity of the surface means a range of 0 to 2 μm in converted depth from the surface.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on the experimental results leading to the present invention.
According to glow discharge spectroscopy, the concentration profile of Si and O can be obtained quickly.
An example of obtaining the Si and O profiles on the surface of the intermediate annealed plate using this glow discharge spectroscopy is shown in FIG.
As shown in the figure, in the glow discharge spectroscopy, the element concentration in the ground iron and the element concentration in the vicinity of the surface can be obtained by one measurement.
This figure shows the depth converted from the sputtering rate and the strength of the measured element, and the integrated strength of Si and O was obtained for the surface vicinity and the base iron part at intervals equivalent to the converted depth of 0.5 μm. .
[0015]
Next, FIG. 2 shows the result of normalization using a so-called integrated intensity ratio obtained by dividing the integrated intensity of the surface of each measurement element by the integrated intensity of the ground iron. The test material used for the measurement was an intermediate annealing plate of a factory line. These steel sheets are steel types containing MnSe and Sb as inhibitor components.
Note that the annealing atmosphere and annealing temperature at the time of intermediate annealing soaking is a condition range where SiO ₂ is produced, the surface by a combination of mechanical polishing and pickling conditions of the brush roll and grinding the elastic roll or the like of the cold却後By removing the oxide layer, the amount of Si and O in the surface oxide layer of the steel sheet after the intermediate annealing and before the secondary cold rolling was changed.
[0016]
FIG. 3 shows the result of a survey on the product quality of the material shown in FIG.
From the figure, it can be seen that the product quality changes according to the surface Si, O concentration of the intermediate annealed plate, and it is necessary to control the Si and O concentrations within a predetermined range in order to obtain good product quality.
[0017]
Next, the effect of the surface properties of the intermediate annealed plate on the magnetic properties of the product and the glass coating was investigated.
Nine intermediate annealed plates (sheet thickness: 0.6 mm, inhibitor components: MnSe, Sb) with Si and O having the integrated strength ratio (surface integrated strength / base iron integrated strength) shown in Table 1 were tested. After finishing to a final thickness of 0.22 mm by cold rolling as a material, immersion degreasing is performed in a degreasing bath using a commercially available alkaline degreasing bath agent, followed by electrolytic degreasing in a 3% sodium orthosilicate aqueous solution. Then, a Si compound was adhered to the steel plate surface. The adhesion amount of the Si compound at this time was determined for each test material as Si.
Next, soaking temperature: 820 ° C, soaking time: 120 seconds, atmosphere oxidation from heating to soaking (P (H ₂ O) / P (H ₂ )) = 0.34, atmosphere oxidation during soaking Decarburization and primary recrystallization annealing were performed under the condition of property = 0.46, and the sub-scale oxygen weight per unit area was determined. Next, as an annealing separator, a slurry containing TiO ₂ : 1.5 parts by weight and SrSO ₄ : 1.5 parts by weight with respect to 100 parts by weight of MgO was applied, dried, and then maintained in dry nitrogen at 850 ° C. for 40 hours. It annealed and calculated | required the additional oxidation amount at this time.
The obtained results are shown in FIG.
[0018]
[Table 1]

[0019]
As shown in FIG. 4, the test materials having a low additional oxidation amount are Nos. 4 to 6, and the other test materials have a large additional oxidation amount. An increase in the amount of additional oxidation adversely affects the forsterite generation behavior and leads to oxidation / decomposition of the inhibitor. The susceptibility to this oxidation depends on the quality of the subscale produced by the charcoal / primary recrystallization annealing.
Since the test materials No. 1 to No. 3 have a low sub-scale oxygen basis weight, the amount of additional oxidation is increased.
In addition, the test materials No. 7 to 9 have not only a high electrolytic electrodeposition amount, but also a very high amount of oxygen on the subscale. Moreover, although the sub-scale oxygen basis weight is high, the additional oxidation amount is also increased because the sub-scale has low resistance to additional oxidation.
[0020]
Therefore, the inventors next investigated factors that change the subscale quality after decarburization and primary recrystallization annealing and the amount of additional acid during finish annealing.
As a result, in the test materials No. 1 to 3, the de-Si layer of the intermediate annealing plate is increased, and in the test materials No. 7 to 9, a large amount of surface layer oxide remains after the intermediate annealing. It became clear that these were the causes of product quality degradation.
This can be evaluated by the integrated strength ratio between the surface of Si and O and the base iron obtained by glow discharge spectroscopic analysis of the intermediate annealing plate.
In addition, since the test materials No. 7 to 9 have a very high amount of oxygen in the subscale, there is a disadvantage that glass coating defects are likely to occur.
[0021]
As described above, when the remaining amount of the surface oxide layer of the intermediate annealing plate increases, the properties of the steel plate surface before decarburization and primary recrystallization annealing deteriorate. That is, since the surface oxide layer of the intermediate annealing plate is rolled while being thick, the steel plate surface is roughened, and not only dirt is adhered, but also the amount of Si compound that is electrodeposited during electrolytic degreasing increases, so subscale oxygen The basis weight is likely to increase. Such an increase in the amount of oxygen or a non-uniform increase in the coil length / width direction adversely affects the formation behavior of forsterite glass coating during finish annealing, and the coating is locally missing in the form of dots. The frequency of occurrence of defects increases.
[0022]
Thus, since the surface texture of the intermediate annealing plate affects the quality of the next process, it is important to manage the surface texture of the intermediate annealing plate. Since the glow discharge spectroscopy used in the present invention is simple and rich in speed, it is extremely effective for quickly checking the line condition fluctuation and the surface condition of the steel sheet.
[0023]
Here, if the annealing atmosphere and annealing temperature at the soaking time is subjected to intermediate annealing under the conditions in which the SiO ₂ generated by, Si and O content in the surface oxide layer of the intermediate annealed sheet is measured by glow discharge spectroscopy It is necessary to control each within the range of 1.1 to 2.3 with the integrated intensity ratio.
This is because, as shown in FIG. 3, when the integrated intensity ratio is less than 1.1, the magnetic characteristics are deteriorated, and when it exceeds 2.3, the glass film quality is deteriorated.
[0024]
Next, the case where the annealing atmosphere and the soaking temperature during soaking in the intermediate annealing are oxidizing in the Fe ₂ SiO ₄ generation region or more will be described. AlN was used as the main component of the inhibitor.
The elemental profiles of Si and O in the intermediate annealed plate are obtained by glow discharge spectroscopy, and the Si and O integrated intensities and the integrated intensity ratios are obtained for the vicinity of the surface and the base iron at intervals equivalent to a converted depth of 2 μm. The result of normalization using the integrated intensity ratio is shown in FIG.
Note that after intermediate annealing, Si in the surface oxide layer of the secondary cold rolling before the steel plate, O is the surface oxide by a combination of mechanical polishing and pickling conditions of the brush roll and grinding the elastic roll or the like of the cold却後Various changes were made by removing the layer .
[0025]
In addition, FIG. 6 shows the results of the investigation on the product quality of the materials shown in FIG.
From the figure, it can be seen that the surface Si, O concentration of the intermediate annealing plate has a suitable range for improving the product quality.
Next, the effect of the surface properties of the intermediate annealed plate on the magnetic properties of the product and the glass coating was investigated.
Nine intermediate annealed sheets (sheet thickness: 1.5 mm, inhibitor main components: AlN, Sb) with Si and O each having the integrated strength ratio shown in Table 2 were used as test materials, and the final sheet thickness was obtained by cold rolling: After finishing to 0.22 mm, dip degreasing in a degreasing bath using a commercially available alkaline degreasing bath agent, followed by soaking temperature: 840 ° C, soaking time: 120 seconds, oxidation from heating to soaking ( Decarburization and primary recrystallization annealing under the conditions of P (H ₂ O) / P (H ₂ )) = 0.38 and oxidation during soaking (P (H ₂ O) / P (H ₂ )) = 0.42 Carried out. This decarburized and annealed plate was immersed in a hydrochloric acid solution having a concentration of 5% and a liquid temperature of 60 ° C. for 60 seconds, and the acid dissolution loss was determined from the sample weight before and after the immersion.
The obtained results are shown in FIG. 7 together with the oxygen basis weight.
[0026]
[Table 2]

[0027]
As shown in FIG. 7, the test materials with low acid dissolution weight loss are Nos. 14 to 16, and the other test materials have a large acid dissolution weight loss. An increase in acid dissolution weight loss adversely affects the forsterite formation behavior and leads to oxidation / decomposition of the inhibitor and pernitriding in the course of finish annealing, which tends to cause deterioration of magnetic properties. The amount of acid dissolution loss depends on the physical properties of subscale quality generated by decarburization and primary recrystallization annealing.
Then, next, as a result of investigating the cause of the increase in the acid dissolution amount of the decarburized annealing plate, in the test material No. 11-13, the de-Si layer of the intermediate annealing plate is increased, the test material No. From 17 to 19, it was found that a large amount of surface layer oxide after the intermediate annealing was the cause of quality deterioration.
[0028]
As described above, as the de-Si layer increases or the residual amount of the surface layer oxide increases, the forsterite glass film formation behavior during finish annealing deteriorates as described above.
Therefore, it is necessary to manage the surface properties of the intermediate annealing plate so that such harmful effects do not occur.
Here, when the annealing atmosphere and annealing temperature during soaking are oxidizing above the Fe ₂ SiO ₄ generation region, the Si and O contents in the surface oxide layer of the intermediate annealing plate are measured by glow discharge spectroscopy. It is necessary to control within the range of 0.7 to 1.2 and 0.95 to 1.12.
As shown in Fig. 6 above, when the integrated strength ratio of Si and O is less than 0.7 and 0.95 or exceeds 1.2 and 1.12 respectively, not only the deterioration of the glass coating but also the magnetic properties This is because it causes deterioration.
[0029]
It should be noted that the conversion depth when obtaining the near surface and the integrated strength of the iron from the Si and O profiles obtained by glow discharge spectroscopy must be adjusted according to the atmosphere and temperature during soaking of the intermediate annealing. is there.
That is, when the atmosphere and temperature during soaking in intermediate annealing are oxidizable in the SiO ₂ generation region, the converted depth from the outermost surface is 0 to 0.5 μm as shown in FIG. Further, it is preferable that the strength ratio of Si and O in the vicinity of the surface with respect to the base iron portion is controlled within a predetermined range with 1.0 to 1.5 μm as the base iron portion.
On the other hand, if the atmosphere and temperature during soaking in intermediate annealing is oxidizing above the Fe ₂ SiO ₄ generation region, the converted depth from the outermost surface is 0-2 μm, near the surface, and 4-6 μm. It is preferable that the strength ratio of Si and O in the vicinity of the surface with respect to the ground iron part is controlled within a predetermined range.
Here, the converted depth is a value obtained by measuring the depth sputtered by a roughness meter after sputtering for a certain time, calculating the sputter depth per unit time from this value, and multiplying this value by the sputter time. That is.
[0030]
Next, the suitable range of the component composition of the electrical steel sheet material that is the subject of this invention will be described.
C: 0.02-0.10wt%
C is an element effective for improving the structure, but if it is out of the above range, it is difficult to obtain a good texture.
[0031]
Si: 2.0 to 4.5 wt%
If the Si content is less than 2.0 wt%, the effect of reducing eddy current loss is reduced, while if it exceeds 4.5 wt%, the cold rolling property is impaired.
[0032]
In addition to these components, an inhibitor-forming component is contained.
When MnS and / or MnSe is used as an inhibitor, Mn: 0.03-0.1 wt%, S + Se: 0.01-0.03 wt%.
On the other hand, when AlN is used as an inhibitor, Al: 0.01 to 0.04 wt%, N: 0.0050 to 0.0120 wt%.
This is because if the content is lower than the above range, the effect as an inhibitor is insufficient, while if the content is higher, secondary recrystallization becomes unstable.
In addition to these, Cu, Sn, Sb, Ge, Mo, Te, Bi, P, V, Nb, and the like can also be applied, and each inhibitor can be used alone or in combination.
[0033]
【Example】
Example 1
Material for grain-oriented electrical steel sheets with inhibitors MnSe and Sb (C: 0.039 wt%, Si: 3.4 wt%, Mn: 0.07 wt%, Se: 0.020 wt%, Sb: 0.024 wt%, S: 0.002 wt% ) Hot rolled to 2.0 mm, homogenized annealing at 1000 ° C. for 30 seconds, and then rolled to a thickness of 0.6 mm by primary cold rolling, followed by intermediate annealing at 950 ° C. for 60 seconds (SiO ₂ generation conditions) ). The oxide layer formed on the steel sheet surface during the intermediate annealing was removed under each condition of pickling, pickling + brush roll polishing, pickling + elastic roll polishing.
The surface removal amount was changed by changing the pickling concentration / temperature, the abrasive grain number and the rotational speed of brush roll polishing and elastic roll polishing.
Subsequently, the Si and O profiles of the intermediate annealed plate were measured by glow discharge spectroscopy, and the integrated strengths of the measured elements were determined for the surface vicinity and the iron core portion at intervals corresponding to the converted depth: 0.5 μm.
[0034]
Next, after finishing to a final thickness of 0.22 mm by secondary cold rolling, decarburization and primary recrystallization annealing were performed in a wet hydrogen atmosphere at 830 ° C. for 120 seconds. Then, after applying an annealing separator added with 2 parts by weight of TiO _{2 and} 1.5 parts by weight of SrSO ₄ with respect to 100 parts by weight of MgO, secondary recrystallization annealing at 845 ° C. for 50 hours, followed by 1180 ° C., 5 Time-purified annealing was applied.
Table 3 shows the results of examining the glass coating adhesion / uniformity and magnetic properties (W _17/50 , B ₈ ) of the steel sheet thus obtained.
The adhesion of the glass coating was indicated by the diameter of the smallest round bar in which the steel plate was wound around round bars having various diameters and no coating peeling occurred.
[0035]
[Table 3]

[0036]
As is clear from the table, by controlling the integrated intensity ratio of Si and O obtained by glow discharge spectroscopic analysis of the intermediate annealed plate within the appropriate range of the present invention, extremely good results for both the glass coating and the magnetic properties are obtained. Could get.
The glow discharge spectroscopic analysis is applicable regardless of the method of removing the surface oxidation layer of the intermediate annealing, such as pickling, pickling + brush roll polishing with abrasive grains, pickling + elastic roll with abrasive grains, and mechanical polishing with a disk. It can be seen that good results can be obtained if the integrated intensity ratio of Si and O obtained by the above is within a predetermined range.
[0037]
Example 2
Material for grain-oriented electrical steel sheets with inhibitors of AlN and Sb (C: 0.070 wt%, Si: 3.3 wt%, Mn: 0.07 wt%, Se: 0.023 wt%, Sb: 0.024 wt%, S: 0.002 wt% Sol.Al: 0.023 wt%, N: 0.0083 wt%), hot rolled to 2.4 mm, homogenized annealing at 1000 ° C for 30 seconds, and then rolled to a thickness of 1.5 mm by primary cold rolling , Intermediate annealing at 1100 ° C for 90 seconds was performed. The intermediate-soaking oxidizability of intermediate annealing is within the range where Fe ₂ SiO ₄ or FeO is generated, and the oxide layer formed on the steel sheet surface during intermediate annealing is pickled, pickled + brush roll polished, pickled + elastic roll polished It was removed under each condition.
The amount of surface removal was changed by changing the pickling concentration / temperature, the abrasive grain number and the rotational speed of brush roll polishing and elastic roll polishing.
Next, the Si and O profiles of the intermediate annealed plate were measured by glow discharge spectroscopy, and the integrated strength of the measured elements was determined for the surface vicinity and the steel part at intervals equivalent to the converted depth: 2.0 μm.
[0038]
Next, after finishing to a final thickness of 0.22 mm by secondary cold rolling, decarburization and primary recrystallization annealing were performed in a wet hydrogen atmosphere at 840 ° C. for 120 seconds. Then, after applying an annealing separator added with 10 parts by weight of TiO _{2 and} 3 parts by weight of Sr (OH) ₂ to 100 parts by weight of MgO, primary holding annealing at 850 ° C. for 15 hours, followed by The temperature was increased from 850 ° C. to 1150 ° C. in a mixed atmosphere of nitrogen and hydrogen at a heating rate of 12.5 ° C./h, followed by purification annealing at 1180 ° C. for 5 hours in a hydrogen atmosphere.
Table 4 shows the results of examining the glass coating adhesion / uniformity and magnetic properties (W _17/50 , B ₈ ) of the steel sheet thus obtained.
The adhesion of the glass coating was indicated by the diameter of the smallest round bar in which the steel plate was wound around round bars having various diameters and no coating peeling occurred.
[0039]
[Table 4]

[0040]
As is clear from the table, when the integrated intensity ratio of Si and O obtained by glow discharge spectroscopic analysis of the intermediate annealed plate satisfies the appropriate range of the present invention, excellent glass coating and magnetic properties should be obtained. I was able to.
[0041]
【The invention's effect】
Thus, according to the present invention, by controlling the amounts of Si and O in the surface oxide layer of the intermediate annealing plate within a predetermined range, it is possible to stably obtain a grain-oriented electrical steel sheet having excellent glass coating properties and magnetic properties. .
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing how to obtain Si and O profiles of an intermediate annealed plate obtained by glow discharge spectroscopy, the surface of a measurement element, and the integrated strength of ground iron.
FIG. 2 is a graph showing the integrated strength ratio of the surface of Si, O and the ground iron obtained by glow discharge spectroscopy of an intermediate annealed plate taken from a factory line.
FIG. 3 is a view showing product characteristics of the intermediate annealed plate shown in FIG. 2;
FIG. 4 is a diagram showing the amount of electrodeposited Si compound after electrolytic degreasing of the test material, the amount of oxygen after decarburization and primary recrystallization annealing, and the amount of additional oxidation during finish annealing.
FIG. 5 is a graph showing the integrated strength ratio of the surface of Si, O and the base iron obtained by glow discharge spectroscopy of an intermediate annealed plate taken from a factory line.
6 is a view showing product characteristics of the intermediate annealed plate shown in FIG.
FIG. 7 is a diagram showing the oxygen basis weight and acid dissolution loss after decarburization and primary recrystallization annealing of the test material.

Claims (2)

Hot-roll silicon-containing steel, then cold-roll twice with intermediate annealing to finish to the final thickness, then decarburize and anneal in wet hydrogen, then apply annealing separator Then, in producing grain-oriented electrical steel sheets by a series of processes that perform finish annealing,
When the atmosphere and temperature during soaking of the intermediate annealing are within the SiO ₂ generation region, the Si and O amounts in the surface oxide layer of the steel sheet after the intermediate annealing and before the secondary cold rolling are determined according to the grinding conditions after the intermediate annealing and By removing the surface oxide layer under at least one of the pickling conditions, the integrated intensity ratio in the vicinity of the surface with respect to the iron and steel portion of Si and O measured by glow discharge spectroscopy is in the range of 1.1 to 2.3, respectively. A method for producing a grain-oriented electrical steel sheet, characterized in that the control is carried out.
Here, the ground iron part refers to a range of 1.0 to 1.5 μm in conversion depth from the surface, and the vicinity of the surface refers to a range of 0 to 0.5 μm in conversion depth from the surface. Hot-roll silicon-containing steel, then cold-roll twice with intermediate annealing to finish to the final thickness, then decarburize and anneal in wet hydrogen, then apply annealing separator Then, in producing grain-oriented electrical steel sheets by a series of processes that perform finish annealing,
If the atmosphere and temperature at the time of soaking of the intermediate annealing is Fe ₂ SiO ₄ generation region more oxidizing, after intermediate annealing, Si and O content in the surface oxide layer of the secondary cold rolling before the steel plate, the intermediate By removing the surface oxide layer according to at least one of the grinding conditions and the pickling conditions after annealing, the integrated intensity ratio in the vicinity of the surface with respect to the iron and steel portion of Si and O measured by glow discharge spectroscopy, A method for producing grain-oriented electrical steel sheets, characterized in that each is controlled in the range of 0.7 to 1.2 and 0.95 to 1.12.
Here, the ground iron part means a range of 4 to 6 μm in converted depth from the surface, and the vicinity of the surface means a range of 0 to 2 μm in converted depth from the surface.

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