JPS6253578B2 - - Google Patents
Info
- Publication number
- JPS6253578B2 JPS6253578B2 JP59077806A JP7780684A JPS6253578B2 JP S6253578 B2 JPS6253578 B2 JP S6253578B2 JP 59077806 A JP59077806 A JP 59077806A JP 7780684 A JP7780684 A JP 7780684A JP S6253578 B2 JPS6253578 B2 JP S6253578B2
- Authority
- JP
- Japan
- Prior art keywords
- coil
- annealing
- temperature
- atmospheric gas
- heating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000137 annealing Methods 0.000 claims description 61
- 238000010438 heat treatment Methods 0.000 claims description 29
- 229910000976 Electrical steel Inorganic materials 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 17
- 239000011248 coating agent Substances 0.000 claims description 12
- 238000000576 coating method Methods 0.000 claims description 12
- 230000003647 oxidation Effects 0.000 claims description 12
- 238000007254 oxidation reaction Methods 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 3
- 239000011810 insulating material Substances 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 102100021102 Hyaluronidase PH-20 Human genes 0.000 claims 1
- 101150055528 SPAM1 gene Proteins 0.000 claims 1
- 239000007789 gas Substances 0.000 description 29
- 229910052839 forsterite Inorganic materials 0.000 description 22
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 22
- 229910000831 Steel Inorganic materials 0.000 description 19
- 239000010959 steel Substances 0.000 description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 14
- 238000004804 winding Methods 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 8
- 238000001816 cooling Methods 0.000 description 7
- 229910052742 iron Inorganic materials 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 239000003112 inhibitor Substances 0.000 description 5
- 238000009413 insulation Methods 0.000 description 5
- 239000010410 layer Substances 0.000 description 5
- 229910004298 SiO 2 Inorganic materials 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
- 229910019440 Mg(OH) Inorganic materials 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 3
- 239000000347 magnesium hydroxide Substances 0.000 description 3
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 3
- 239000000395 magnesium oxide Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 150000003568 thioethers Chemical class 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004660 morphological change Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/76—Adjusting the composition of the atmosphere
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electromagnetism (AREA)
- Manufacturing & Machinery (AREA)
- Manufacturing Of Steel Electrode Plates (AREA)
Description
（産業上の利用分野）
本発明は一方向性珪素鋼板の仕上焼鈍方法に係
わり、被焼鈍一方向性珪素鋼コイルの全長、全幅
にわたつて磁気特性が優れ、良好なフオルステラ
イト絶縁被膜および形状が形成される仕上焼鈍方
法に関するものである。
一方向性珪素鋼板の製造において最終仕上焼鈍
はコイル状で高温、長時間行なわれる。この仕上
焼鈍の目的は、(1)二次再結晶を発現せしめ
（110）〔001〕方位を持つ結晶粒を板面に平行でか
つ圧延方向に揃えること、(2)鋼板表面にSiO2を
主成分とする酸化層とマグネシア（MgO）を主
成分とする焼鈍分離剤との反応により、フオルス
テライト絶縁被膜を形成すること、(3)鋼中の不純
物を主に雰囲気ガスとの反応により除去するこ
と、(4)コイル状の焼鈍において形状を損わない加
熱、均熱、冷却を行なうことにある。
仕上焼鈍は脱炭焼鈍後の一方向性珪素鋼板表面
にスラリー状焼鈍分離剤を塗布乾燥後、コイル状
に捲かれ仕上焼鈍炉にて900℃以上の高温で長時
間焼鈍された後、500℃以下迄炉中冷却される。
ところで該コイル状で行なわれる仕上焼鈍にお
いて加熱、冷却時には次のような状況となる。
焼鈍炉内に被焼鈍コイルは中心の中空部を垂直
方向に向けて、一段又は多段に置かれ、マツフル
をかぶせられ、加熱装置例えば電気ヒーター、バ
ーナ等により加熱され、冷却時には例えば炉中の
自然冷却、冷風をマツフルに吹付ける等により冷
却される。
この加熱作用又は冷却作用を受ける時、その伝
熱は大部分がコイル−マツフル間の輻射であり、
コイル内外側周面を通してのコイル厚さ方向（コ
イル半径方向）の熱流成分が圧倒的に多くコイル
上下端面を通してのコイル幅方向の熱流成分は少
ない。
一方コイル厚さ方向（コイル半径方向）の熱伝
導は焼鈍分離剤を介しての伝導であるために遅
く、コイル幅方向の熱伝導は一方向珪素鋼板内の
伝導であるために速い。この結果、被焼鈍コイル
加熱、冷却時にはそれぞれコイル外捲部、内捲部
と中間部とで温度偏差が生じる。
また前述の如く鋼板には焼鈍分離剤が塗布され
ているがこの中には不可避的に水酸化マグネシウ
ム（Mg（OH）2）が含まれる。この水酸化マグネ
シウム（Mg（OH）2）は仕上焼鈍の加熱時に熱分
解し水蒸気を放出するのであるが、被焼鈍コイル
は前述の如く温度偏差を持つので水蒸気の放散程
度はコイル内の位置により差異を生じる。鋼板表
面に形成されるフオルステライト絶縁被膜はこの
影響を受けコイル全長もしくはコイル全幅にわた
つて良好なフオルステライト被膜を形成すること
が難しくなつている。
又前記温度偏差や焼鈍雰囲気のコイル位置によ
る差異などに起因して磁気特性にバラツキが生じ
る。
さらに、コイルには中膨れ等の形状不良が生じ
商品価値を下げ、歩留を低下させる。
（従来技術）
これらの問題に対する従来の対策としては、例
えば経験的に仕上焼鈍の加熱時、加熱途中の中間
温度で所定時間保定する方法があり、該中間温度
での保定でコイル内の温度偏差を減少し、次いで
所定温度に加熱し焼鈍するのである。これによる
とそれなりの効果はあるが、どちらかと言えば消
極的な対策であり焼鈍に要する時間が長くなる事
は否めない。
焼鈍における加熱を速めかつ温度偏差を減少さ
せるために、低炭素冷延鋼板のコイル焼鈍に適用
されている例えば特公昭57−26330号公報に示さ
れるような循環用フアンで強制的に循環する方法
を用いることも考えられるが、一方向性珪素鋼板
の仕上焼鈍は前述の如くより高温で行なわれるた
め、仮に単に循環用フアンによる雰囲気ガス循環
を用いたとしても加熱時コイルへの伝熱は大部分
がマツフルからの輻射でありコイル外捲部、内捲
部が中間部にくらべて高温であることは変りはな
くコイル内の温度偏差は依然として残る。
また他の方法として特開昭55−158229号公報に
て、コイル焼鈍炉内におかれたコイルの外捲面
を、鉄板製円筒体で隙間を設けて囲んで雰囲気ガ
ス滞留層を形成し、コイルの外捲面からの伝熱量
を抑えるコイル均一加熱方法が提案されている。
これは雰囲気ガス滞留層をコイルの外捲面の外側
に形成する一方、雰囲気ガスをベースフアンにて
循環させ、前記鉄板製円筒体の外側を通つてコイ
ルの中心の中空部に通して加熱するのである。こ
の方法では、雰囲気ガスは前記中空部を通り循環
されることから、コイルの内捲面はより加熱さ
れ、コイル内の温度偏差を十分に少なくするには
難点がある。
一方フオルステライト絶縁被膜の形成に対する
仕上焼鈍の検討もなされている。例えば特公昭57
−34351号公報では、フオルステライト絶縁被膜
を構成するフオルステライト粒子の平均粒径を
0.7μｍ以下の微細構造にするため仕上焼鈍にお
いて、800〜920℃の温度範囲で定温保定が終了し
雰囲気ガスを中性ガスから水素ガスに切替えた
後、1150〜1250℃まで加熱する温度域での鋼帯に
接する雰囲気の平均露点を−20℃〜＋20℃とし、
1150〜1250℃での焼鈍全期間に鋼帯に接する雰囲
気の平均露点を＋10℃以下で＋10℃より高い露点
での焼鈍期間を５時間以内にすることが提案され
ている。
これによると密着性と層間抵抗の良いフオルス
テライト絶縁被膜が形成されるとのことである。
しかし、実操業においては、仕上焼鈍の加熱時
におけるコイル内の温度偏差と、該温度偏差によ
る雰囲気ガスとの反応の差およびマツフル内の雰
囲気の酸化ポテンシヤルの違いが、フオルステラ
イト絶縁被膜の形成に影響を及ぼし、十分に満足
できるフオルステライト絶縁被膜がコイル全長、
全幅にわたつて形成されるまでに到つていない。
（発明の目的）
本発明は一方向性珪素鋼板コイルの全幅、全長
にわたつて磁気特性、フオルステライト絶縁被膜
とも良好で、かつ形状不良が発生しない一方向性
珪素鋼板の仕上焼鈍方法を提供することを目的と
し、その要旨は一方向性珪素鋼板をコイル状で仕
上焼鈍するにあたり、コイル外側面、コイル内側
面への熱流を抑制して加熱し、600〜1250℃の温
度域における雰囲気ガスの酸化ポテンシヤルＰH2
Ｏ／ＰH2を、温度との関係にて制御することを特
徴とする一方向性珪素鋼板の仕上焼鈍方法にあ
る。
（発明の構成・作用）
次に、本発明を詳細に説明する。
本発明者達は一方向性珪素鋼板の仕上焼鈍にお
ける磁気特性のバラツキや、フオルステライト絶
縁被膜の不良、あるいはコイルの中膨れ等の形状
不良の防止を図るべく、種々の実験を行ない検討
した。その結果、仕上焼鈍における温度偏差は、
(1)加熱時コイル内捲部に発生する圧縮力によるコ
イル内捲部の圧縮歪、(2)冷却時コイル外捲部に発
生する引張り力によるコイル外捲部の引張歪の原
因となるばかりでなく、特に加熱から均熱（例え
ば、1200℃）においてコイル厚さ方向（コイル半
径方向）の中心から外捲部は、外側へ行く程温度
が高く、従つてコイルがルーズ捲となり雰囲気ガ
スとの反応が活発となり、一方内捲部は内側へ行
く程温度が高く従つてコイルがタイト捲となり雰
囲気ガスとの反応が抑制されること、即ちコイル
厚さ方向（コイル半径方向）に被膜形成の不均一
を生ずる原因となることが究明された。
さらに水酸化マグネシウム（Mg（OH）2）の熱
分解による水蒸気の放出も終了している600℃以
上から鋼中の成分、とくにSiの拡散が生じ鋼板表
面のSi濃度が増え鋼板表面と雰囲気ガスとの反応
が非常に重要であること、および良好なフオルス
テライト絶縁被膜を形成するには鋼板中のSiを酸
化しSiO2とするに十分な酸素を雰囲気ガスから
供給してやる必要があるが、過度に酸化力が強く
なるとインヒビター例えばAlN，MnSの分散状態
や大きさが変化して二次再結晶に影響すると同時
に通常シモフリと呼ばれる斑点状フオルステライ
ト被膜欠陥が生じやすくなることが究明された。
さらに検討したところ、一方向性珪素鋼板の仕
上焼鈍においてコイル内周面を通しての熱流を抑
制し、コイル上下端面を通しての熱流を増やして
加熱するとともに、600〜1250℃における雰囲気
ガスの酸化ポテンシヤルＰH2O／ＰH2を温度との
関係で下記式で示される範囲に制御すると、磁気
特性、被膜特性、形状ともコイル全長、全幅にわ
たつて優れた一方向性珪素鋼板を製造できること
を見出した。
−１９００／Ｔ＋0.13＞log（ＰＨ２Ｏ／ＰＨ２）＞
−１９００／Ｔ−1.25
ここでＴは温度（単位：〓）
ＰH2Oは水蒸気分圧（単位：気圧）
ＰH2は水素分圧 （単位：気圧）
以下に実験結果を参照して詳述する。
仕上焼鈍される一方向性珪素鋼板は、Ｃ：0.02
〜0.08％，Si：2.5〜4.0％，Mn：0.03〜0.50％、
さらに一次再結晶粒の成長を抑制するインヒビタ
ー、例えばAlN，MnS，MnSe，BN等の窒化物や
硫化物を形成する成分を含み、熱間圧延後１回ま
たは中間焼鈍をはさんで２回以上の冷間圧延、あ
るいは最終冷間圧延前に前記窒化物や硫化物の析
出焼鈍が施されたもので、その鋼板表面には
MgOを主成分とする焼鈍分離剤が塗布されてい
る。
この一方向性珪素鋼板コイル（以下コイルとい
う）は、本発明の実施の態様を表わす第１図に示
すように、焼鈍炉１のベースプレート２上に置か
れる。コイル３の置き方は、この図に示すように
１段でもよいし、多段であつてもよい。
該コイル３の内側面４と外側面５には断熱材、
例えば断熱コイルリング６を設け、該内側面４、
外側面５を通しての熱流を少なくする。前記内側
面４を通しての熱流低下については、断熱コイル
リング６の他に、コイル３の中空部に断熱帽子７
を設け雰囲気ガスの中空部の流通を防ぐ方法等の
手段も用いられうる。
コイル３の上端面８、下端面９を通り該コイル
幅方向に流通する熱流を主として加熱するよう
に、コイル３の上方と下方に空間１０を形成す
る。さらにマツフル１１内の雰囲気ガスをベース
フアン１２等の循環装置で循環せしめると前記熱
流が促進される。
このようにコイル３の内側面４、外側面５を通
してのコイル３への熱流を抑制し、上端面８、下
端面９を通しての熱流を主として加熱すると、コ
イル３内の温度偏差が小さくなる。さらにコイル
３内の温度分布が変る。即ち従来法では、コイル
３の中間部は内捲部、外捲部にくらべて昇温が遅
れ低温であつたが、本発明によると中間部は内捲
部より昇温が速くなり、内捲部から中間部、外捲
部へと向かうに従つてほぼ直線状に高温となる温
度分布を呈する。
加熱時のコイル内の温度分布を測定した結果を
第３図に示す。この図は焼鈍温度1200℃に20℃／
hrの加熱速度で加熱したさい、加熱途中の炉温が
1000℃のときのコイル３内の温度分布であり、実
線ａは本発明法で、破線ｂは従来法である。なお
従来法はコイル内側面、外側面に断熱コイルリン
グを設けないほかは本発明と同じ焼鈍条件で加熱
した。
仕上焼鈍においては鋼板表面のSiO2を主成分
とする酸化層と鋼板表面に塗布されたマグネシア
（MgO）を主成分とする焼鈍分離剤の反応により
フオルステライト絶縁被膜（2MgO・SiO2）が形
成される。この被膜の形成と二次再結晶はほぼ近
い温度域で起るがいずれもマツフル内の雰囲気ガ
スと鋼板表面との反応がその成否を大きく左右す
る。とくに、焼鈍の進行により加熱温度が高くな
つて、600℃以上から鋼板表面のSiの濃度が第４
図に示す如く増えることが見出され、このSiの鋼
板表面の富化は雰囲気ガスと反応しSiO2を形成
する機会が大となることに他ならず、フオルステ
ライト絶縁被膜の形成に大きな影響を及ぼす。
従来においては、800℃以上での雰囲気ガスの
状態がフオルステライト絶縁被膜の良否に影響す
るといわれていたが、これでは不十分である。フ
オルステライト絶縁被膜形成の初期段階の600℃
超えた比較的低温から雰囲気ガスの酸化ポテンシ
ヤルＰH2O／ＰH2を温度との関係で制御すること
が良好なフオルステライト絶縁被膜をコイル全
長、全幅にわたつて形成するために必要であるの
が実験より見出された。
即ち、通常の方法で熱間圧延、焼鈍、冷間圧延
及び脱炭焼鈍された後、表面にMgOを主成分と
する焼鈍分離剤を塗布された一方向性珪素鋼板を
コイル状で仕上焼鈍した。その焼鈍サイクルは加
熱速度20℃／hrで焼鈍温度1200℃に加熱し、25時
間（hr）保定し、次いで冷却することからなる。
雰囲気ガスの酸化ポテンシヤルＰH2O／ＰH2を600
〜1250℃の温度域で温度により変えて焼鈍した。
その雰囲気ガスはアンモニヤ分解ガス（AX）で
H2とN2よりなり必要に応じてH2Oを含ませて酸
化ポテンシヤルＰH2O／ＰH2を制御した。またこ
の焼鈍ではいずれもコイル３の内側面４、外側面
５に断熱コイルリング６を設けて、これらの面か
らの熱流を抑制し、上端面８、下端面９より熱流
を与えて行つた。
仕上焼鈍の後、フオルステライト絶縁被膜の密
着性と鉄損Ｗ17/50を調査し、その結果を、温度
により変えた雰囲気ガスの酸化ポテンシヤルＰH2
Ｏ／ＰH2の条件とともに第５図及び第１表に示
す。
(Industrial Application Field) The present invention relates to a method for finish annealing a unidirectional silicon steel plate, and the unidirectional silicon steel coil to be annealed has excellent magnetic properties over the entire length and width, and has a good forsterite insulating coating and shape. The present invention relates to a finish annealing method in which . In the production of unidirectional silicon steel sheets, the final finish annealing is performed in the form of a coil at high temperatures and for a long period of time. The purposes of this final annealing are (1) to induce secondary recrystallization to align crystal grains with (110) [001] orientation parallel to the sheet surface and in the rolling direction, and (2) to form SiO 2 on the steel sheet surface. A forsterite insulating film is formed by the reaction between the oxide layer, which is the main component, and an annealing separator, which is mainly composed of magnesia (MgO), and (3) impurities in the steel are removed mainly by reaction with atmospheric gas. and (4) performing heating, soaking, and cooling without damaging the shape during annealing of the coil. For final annealing, a slurry annealing separator is applied to the surface of the unidirectional silicon steel sheet after decarburization annealing, and after drying, it is wound into a coil shape and annealed for a long time at a high temperature of 900℃ or higher in a final annealing furnace, followed by 500℃. Cooled in the furnace until below. By the way, during the final annealing performed in the coiled shape, the following situation occurs during heating and cooling. The coils to be annealed are placed in one or more stages in the annealing furnace with the hollow part of the center facing vertically, covered with matsufuru, and heated by a heating device such as an electric heater or a burner. Cooling is achieved by blowing cold air onto the matsufuru. When subjected to this heating or cooling action, most of the heat transfer is radiation between the coil and the matsufuru,
The heat flow component in the coil thickness direction (coil radial direction) through the inner and outer circumferential surfaces of the coil is overwhelmingly large, and the heat flow component in the coil width direction through the upper and lower end surfaces of the coil is small. On the other hand, heat conduction in the coil thickness direction (coil radial direction) is slow because it is conducted through the annealing separator, and heat conduction in the coil width direction is fast because it is conducted within the unidirectional silicon steel plate. As a result, during heating and cooling of the coil to be annealed, temperature deviations occur between the outer winding part, the inner winding part, and the middle part of the coil, respectively. Further, as mentioned above, the steel sheet is coated with an annealing separator, which inevitably contains magnesium hydroxide (Mg(OH) 2 ). This magnesium hydroxide (Mg(OH) 2 ) thermally decomposes and releases water vapor when heated for finish annealing, but as the coil to be annealed has temperature deviations as mentioned above, the degree of vapor release depends on the position within the coil. make a difference The forsterite insulating coating formed on the surface of the steel sheet is affected by this, making it difficult to form a good forsterite coating over the entire length or width of the coil. Furthermore, variations in magnetic properties occur due to the temperature deviation and the difference in annealing atmosphere depending on the coil position. Furthermore, the coils suffer from shape defects such as bulges, lowering the commercial value and lowering the yield. (Prior art) As a conventional countermeasure for these problems, for example, there is a method based on experience that during heating for finish annealing, the heating is held at an intermediate temperature for a predetermined period of time. The material is then heated to a predetermined temperature and annealed. Although this has some effect, it is a rather passive measure and it cannot be denied that the time required for annealing becomes longer. In order to speed up heating and reduce temperature deviation during annealing, a method of forced circulation using a circulation fan, such as the one shown in Japanese Patent Publication No. 57-26330, which is applied to coil annealing of low carbon cold rolled steel sheets. However, as mentioned above, finish annealing of unidirectional silicon steel sheets is carried out at a higher temperature, so even if atmospheric gas is circulated using a circulation fan, heat transfer to the coil during heating will be significant. The outer and inner winding parts of the coil are still higher in temperature than the middle part because of the radiation from the matsufuru, and the temperature deviation within the coil still remains. Another method is disclosed in Japanese Unexamined Patent Publication No. 158229/1983, in which the outer winding surface of a coil placed in a coil annealing furnace is surrounded with a cylindrical body made of iron plate with a gap provided to form an atmospheric gas retention layer. A coil uniform heating method has been proposed that suppresses the amount of heat transferred from the outer wound surface of the coil.
In this method, an atmospheric gas retention layer is formed on the outside of the outer wound surface of the coil, while the atmospheric gas is circulated by a base fan, passed through the outside of the iron plate cylinder, and passed through the hollow part at the center of the coil to heat it. It is. In this method, since the atmospheric gas is circulated through the hollow portion, the inner winding surface of the coil is heated more, and it is difficult to sufficiently reduce the temperature deviation within the coil. On the other hand, finishing annealing for forming a forsterite insulating film has also been studied. For example, special public service in Showa 57
-34351 publication, the average particle size of forsterite particles constituting the forsterite insulation coating is
In order to obtain a microstructure of 0.7μm or less, during final annealing, after constant temperature holding is completed in the temperature range of 800 to 920℃ and the atmospheric gas is switched from neutral gas to hydrogen gas, heating is performed in the temperature range of 1150 to 1250℃. The average dew point of the atmosphere in contact with the steel strip is -20℃ to +20℃,
It is proposed that the average dew point of the atmosphere in contact with the steel strip be below +10°C during the entire annealing period at 1150-1250°C, and that the annealing period at a dew point higher than +10°C be within 5 hours. According to this, a forsterite insulating film with good adhesion and interlayer resistance is formed. However, in actual operation, the temperature deviation inside the coil during heating for final annealing, the difference in the reaction with the atmospheric gas due to this temperature deviation, and the difference in the oxidation potential of the atmosphere inside the Matsufuru, affect the formation of the forsterite insulating film. The full length of the coil is covered by a fully satisfactory forstellite insulation coating.
It has not yet reached the point where it is formed over the entire width. (Object of the Invention) The present invention provides a method for finish annealing a unidirectional silicon steel sheet, which has good magnetic properties and a forsterite insulating coating over the entire width and length of the unidirectional silicon steel sheet coil, and does not cause shape defects. The purpose is to heat the unidirectional silicon steel sheet in a coiled form by suppressing the heat flow to the outer surface and inner surface of the coil, and to suppress the flow of atmospheric gas in the temperature range of 600 to 1250℃. Oxidation potential P H2
A method for finish annealing a grain-oriented silicon steel sheet, characterized by controlling O 2 /P H2 in relation to temperature. (Structure and operation of the invention) Next, the present invention will be explained in detail. The present inventors conducted various experiments and investigated ways to prevent variations in magnetic properties during finish annealing of unidirectional silicon steel sheets, defects in the forsterite insulation coating, and defects in shape such as bulges in the coil. As a result, the temperature deviation during final annealing is
(1) Compressive strain of the inner winding of the coil due to compressive force generated in the inner winding of the coil during heating; (2) Tensile strain of the outer winding of the coil due to tensile force generated on the outer winding of the coil during cooling. However, especially during heating and soaking (for example, 1200℃), the temperature from the center to the outer winding in the coil thickness direction (coil radial direction) is higher as it goes outward, so the coil winds loosely and is exposed to atmospheric gas. On the other hand, the temperature of the inner wound part is higher as it goes inward, so the coil is wound tightly and the reaction with the atmospheric gas is suppressed.In other words, the formation of a film in the coil thickness direction (coil radial direction) is suppressed. It was determined that this was the cause of non-uniformity. Furthermore, at temperatures above 600°C, when the release of water vapor due to the thermal decomposition of magnesium hydroxide (Mg(OH) 2 ) has finished, components in the steel, especially Si, begin to diffuse, increasing the Si concentration on the steel plate surface and the atmospheric gas. It is important to note that the reaction with It has been found that when the oxidizing power becomes stronger, the dispersion state and size of inhibitors such as AlN and MnS change, affecting secondary recrystallization, and at the same time, it becomes easier to produce spotty forsterite coating defects commonly called shimofuri. Further investigation revealed that during finish annealing of unidirectional silicon steel sheets, the heat flow through the inner peripheral surface of the coil is suppressed, the heat flow through the upper and lower end surfaces of the coil is increased, and the oxidation potential of the atmospheric gas P H2O at 600 to 1250°C is It has been found that by controlling /P H2 in the range shown by the following formula in relation to temperature, it is possible to produce a unidirectional silicon steel sheet with excellent magnetic properties, coating properties, and shape over the entire length and width of the coil. -1900/T+0.13>log( PH2O / PH2 )>
-1900/T-1.25 Here, T is temperature (unit: 〓) P H2O is water vapor partial pressure (unit: atmospheric pressure) P H2 is hydrogen partial pressure (unit: atmospheric pressure) A detailed explanation will be given below with reference to experimental results. The unidirectional silicon steel plate to be finish annealed has a C: 0.02
~0.08%, Si: 2.5~4.0%, Mn: 0.03~0.50%,
Furthermore, it contains inhibitors that suppress the growth of primary recrystallized grains, such as components that form nitrides and sulfides such as AlN, MnS, MnSe, and BN, once after hot rolling or twice or more with intermediate annealing in between. The steel sheet surface is cold-rolled or subjected to precipitation annealing of the nitrides and sulfides before the final cold rolling.
An annealing separator mainly composed of MgO is applied. This unidirectional silicon steel sheet coil (hereinafter referred to as a coil) is placed on a base plate 2 of an annealing furnace 1, as shown in FIG. 1, which shows an embodiment of the present invention. The coil 3 may be placed in one stage as shown in this figure, or in multiple stages. A heat insulating material is provided on the inner surface 4 and outer surface 5 of the coil 3,
For example, a heat insulating coil ring 6 is provided, and the inner surface 4,
The heat flow through the outer surface 5 is reduced. Regarding the reduction in heat flow through the inner surface 4, in addition to the heat insulating coil ring 6, a heat insulating cap 7 is placed in the hollow part of the coil 3.
It is also possible to use methods such as providing a method to prevent atmospheric gas from flowing through the hollow part. Spaces 10 are formed above and below the coil 3 so as to mainly heat the heat flow passing through the upper end surface 8 and lower end surface 9 of the coil 3 and flowing in the width direction of the coil. Furthermore, the heat flow is promoted by circulating the atmospheric gas within the Matsufuru 11 using a circulation device such as the base fan 12. In this way, by suppressing the heat flow to the coil 3 through the inner surface 4 and outer surface 5 of the coil 3 and heating mainly through the heat flow through the upper end surface 8 and lower end surface 9, the temperature deviation within the coil 3 becomes smaller. Furthermore, the temperature distribution within the coil 3 changes. That is, in the conventional method, the temperature of the middle part of the coil 3 was lower than that of the inner and outer wound parts, and the temperature rose slower than that of the inner and outer parts. The temperature distribution exhibits a temperature distribution in which the temperature increases almost linearly from the middle portion to the outer wrapping portion. Figure 3 shows the results of measuring the temperature distribution inside the coil during heating. This figure shows annealing temperature of 1200℃ and 20℃/
When heating at a heating rate of hr, the furnace temperature during heating is
This is the temperature distribution inside the coil 3 at 1000° C., where the solid line a is the method of the present invention and the broken line b is the conventional method. In addition, in the conventional method, heating was performed under the same annealing conditions as in the present invention except that no insulating coil rings were provided on the inner and outer surfaces of the coil. During final annealing, a forsterite insulating film (2MgO・SiO 2 ) is formed by the reaction between the oxide layer on the steel sheet surface whose main component is SiO 2 and the annealing separator whose main component is magnesia (MgO) applied to the steel sheet surface. be done. Although the formation of this film and the secondary recrystallization occur in almost similar temperature ranges, the success or failure of both is largely determined by the reaction between the atmospheric gas inside the Matsufuru and the surface of the steel sheet. In particular, as the heating temperature increases as annealing progresses, the Si concentration on the steel plate surface reaches the fourth level from 600℃ or higher.
As shown in the figure, it was found that this enrichment of Si on the steel plate surface increases the chance of reacting with atmospheric gas and forming SiO 2 , which has a large effect on the formation of the forsterite insulating film. effect. Conventionally, it has been said that the condition of the atmospheric gas at temperatures above 800°C affects the quality of the forstellite insulating film, but this is not sufficient. 600℃ during the initial stage of forsterite insulation film formation
It is necessary to control the oxidation potential P H2O /P H2 of the atmospheric gas in relation to temperature from a relatively low temperature that exceeds the temperature limit in order to form a good forsterite insulating film over the entire length and width of the coil. It was discovered more. That is, after being hot rolled, annealed, cold rolled, and decarburized annealed in the usual manner, a unidirectional silicon steel sheet whose surface was coated with an annealing separator mainly composed of MgO was finished annealed in a coil shape. . The annealing cycle consisted of heating to an annealing temperature of 1200°C at a heating rate of 20°C/hr, holding for 25 hours (hr), and then cooling.
Oxidation potential of atmospheric gas P H2O /P H2 is 600
Annealing was performed in the temperature range of ~1250°C with varying temperatures.
The atmospheric gas is ammonia decomposition gas (AX).
It was composed of H 2 and N 2 and contained H 2 O as necessary to control the oxidation potential P H2O /P H2 . Further, in this annealing, a heat insulating coil ring 6 was provided on the inner surface 4 and outer surface 5 of the coil 3 to suppress heat flow from these surfaces, and heat flow was applied from the upper end surface 8 and the lower end surface 9. After final annealing, the adhesion and iron loss W 17/50 of the forsterite insulating film were investigated, and the results were compared to the oxidation potential P H2 of the atmospheric gas, which was changed depending on the temperature.
The conditions of O 2 /P H2 are shown in FIG. 5 and Table 1.
【表】
これより、600〜1250℃における雰囲気ガスの
酸化ポテンシヤルＰH2O／ＰH2をlog値で−１９００／Ｔ
＋
0.13以下で−１９００／Ｔ−1.25以上にすると、密着性
、
外観ともすぐれたフオルステライト絶縁被膜が形
成されることがわかる。また鉄損もすぐれてい
る。従つて本発明では一方向性珪素鋼板を仕上焼
鈍するさい600〜1250℃の温度域での雰囲気ガス
の酸化ポテンシヤルＰH2O／ＰH2を−１９００／Ｔ＋0.1
3
＞log（ＰＨ２Ｏ／ＰＨ２）＞−１９００／Ｔ−1.25と
する。
このようにして仕上焼鈍するとフオルステライ
ト絶縁被膜と鉄損ともすぐれるのは、Si等の過酸
化が防がれて前工程の脱炭焼鈍で形成された鋼板
表面の酸化層が変質せず焼鈍分離剤との反応が適
正化するためと推察される。またフオルステライ
ト絶縁被膜を通しての雰囲気ガスと鋼中のインヒ
ビターとの反応が防がれ、例えば脱Ｓによるイン
ヒビターMnSの分解や、N2吸収によるインヒビ
ターAlNの形態変化が起らず、二次再結晶の発現
が安定化し磁気特性も向上すると推察される。
（実施例）
次に実施例について述べる。
Ｃ：0.060％、Si：3.10％を含む珪素鋼を公知
の方法で熱延し、熱延板焼鈍し、冷延して0.30mm
板厚とし、次いで脱炭焼鈍し、鋼板表面にMgO
を主成分とする焼鈍分離剤を塗布し、コイル状で
仕上焼鈍した。その焼鈍温度は1200℃、保定時間
は25時間、加熱速度は20℃／hrである。600〜
1200℃間の加熱時における雰囲気ガスの酸化ポテ
ンシヤルＰH2O／ＰH2と加熱条件を第２表に示す
通りで行つた。仕上焼鈍の後、磁性（鉄損値Ｗ17
／５０）とフオルステライト絶縁被膜の密着性、層
間抵抗、外観を調査し、その結果を前記第２表に
あわせて示す。[Table] From this, the oxidation potential P H2O /P H2 of the atmospheric gas at 600 to 1250℃ is -1900/T in log value.
It can be seen that when the value is less than +0.13 and more than -1900/T-1.25, a forsterite insulating film with excellent adhesion and appearance is formed. It also has excellent iron loss. Therefore, in the present invention, when finish annealing a grain-oriented silicon steel sheet, the oxidation potential P H2O /P H2 of the atmospheric gas in the temperature range of 600 to 1250°C is -1900/T+0.1.
3>log( PH2O / PH2 )>-1900/T-1.25. Finish annealing in this way produces an excellent forsterite insulating coating and iron loss, because overoxidation of Si, etc. is prevented, and the oxidized layer on the surface of the steel plate formed in the decarburization annealing process in the previous process does not change in quality. It is presumed that this is because the reaction with the separating agent is optimized. In addition, the reaction between the atmospheric gas and the inhibitor in the steel through the forsterite insulating film is prevented, and, for example, the decomposition of the inhibitor MnS due to S removal and the morphological change of the inhibitor AlN due to N 2 absorption do not occur, and secondary recrystallization does not occur. It is inferred that the expression of is stabilized and the magnetic properties are improved. (Example) Next, an example will be described. Silicon steel containing C: 0.060% and Si: 3.10% is hot rolled by a known method, hot rolled sheet annealed, and cold rolled to 0.30mm.
The steel plate is thickened, then decarburized and annealed, and MgO is applied to the steel plate surface.
An annealing separator mainly composed of was applied and final annealing was performed in a coil shape. Its annealing temperature is 1200°C, holding time is 25 hours, and heating rate is 20°C/hr. 600〜
The oxidation potential P H2O /P H2 of the atmospheric gas during heating to 1200° C. and the heating conditions were as shown in Table 2. After finishing annealing, magnetic (iron loss value W 17
/50 ) and the forsterite insulating coating, the adhesion, interlayer resistance, and appearance were investigated, and the results are shown in Table 2 above.
第１図は本発明の一実施例における仕上焼鈍の
実施態様を示す図、第２図はコイルの断熱状況を
示す他の例の説明図、第３図は仕上焼鈍の加熱時
におけるコイル内の温度分布を示す図、第４図は
加熱温度による鋼板表面でのSi濃度の変化を示す
図、第５図は雰囲気ガスの酸化ポテンシヤルＰH2
Ｏ／ＰH2を温度により変えた場合の鉄損とフオル
ステライト被膜の密着性に及ぼす影響を示す図で
ある。
１……焼鈍炉、２……ベースプレート、３……
コイル、４……内側面、５……外側面、６……断
熱コイルリング、７……断熱帽子、８……上端
面、９……下端面、１０……空間。
Fig. 1 is a diagram showing an embodiment of finish annealing in one embodiment of the present invention, Fig. 2 is an explanatory diagram of another example showing the insulation condition of the coil, and Fig. 3 is a diagram showing the state of the coil inside the coil during heating for finish annealing. Figure 4 shows the temperature distribution. Figure 4 shows the change in Si concentration on the steel sheet surface depending on the heating temperature. Figure 5 shows the oxidation potential of the atmospheric gas P H2.
FIG. 3 is a diagram showing the effect on iron loss and adhesion of a forsterite film when O 2 /P H2 is changed depending on temperature. 1...Annealing furnace, 2...Base plate, 3...
Coil, 4... Inner surface, 5... Outer surface, 6... Insulating coil ring, 7... Insulating cap, 8... Upper end surface, 9... Lower end surface, 10... Space.
Claims (1)
にあたり、コイル内側面とコイル外側面に断熱材
を設けるか、またはコイルの中空部に断熱材帽子
を設け、コイルの内側面と外側面を通してのコイ
ル内への熱流を抑制して加熱するとともに、温度
が600℃〜1250℃の範囲内にあるとき、焼鈍雰囲
気の酸化ポテンシヤルＰH20／ＰH2と温度の関係
を下記の式で示される範囲にすることを特徴とす
る磁気特性、被膜特性の優れた一方向性珪素鋼板
の仕上焼鈍方法。 −１９００／Ｔ＋0.13 ＞log（ＰＨ２０／ＰＨ２）＞−１９００／Ｔ−1.2
5 ここでＴは温度（単位：〓） ＰH20は水蒸気分圧（単位：気圧） ＰH2は水素分圧（単位：気圧）[Claims] 1. When finishing annealing a unidirectional silicon steel plate in a coil shape, a heat insulating material is provided on the inner surface of the coil and an outer surface of the coil, or a heat insulating material cap is provided in the hollow part of the coil. When heating is performed by suppressing the heat flow into the coil through the side and outer surfaces, and when the temperature is within the range of 600℃ to 1250℃, the relationship between the oxidation potential P H20 /P H2 of the annealing atmosphere and temperature is as follows. A method for finish annealing a unidirectional silicon steel sheet with excellent magnetic properties and coating properties, which is characterized in that the annealing is performed within the range shown by the formula. -1900/T+0.13 >log( PH20 / PH2 )>-1900/T-1.2
5 Here, T is temperature (unit:〓) P H20 is water vapor partial pressure (unit: atmospheric pressure) P H2 is hydrogen partial pressure (unit: atmospheric pressure)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7780684A JPS60221522A (en) | 1984-04-18 | 1984-04-18 | Method for finish-annealing grain-oriented silicon steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7780684A JPS60221522A (en) | 1984-04-18 | 1984-04-18 | Method for finish-annealing grain-oriented silicon steel sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60221522A JPS60221522A (en) | 1985-11-06 |
| JPS6253578B2 true JPS6253578B2 (en) | 1987-11-11 |
Family
ID=13644255
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7780684A Granted JPS60221522A (en) | 1984-04-18 | 1984-04-18 | Method for finish-annealing grain-oriented silicon steel sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60221522A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013133503A (en) * | 2011-12-27 | 2013-07-08 | Jfe Steel Corp | Method of producing grain-oriented electromagnetic steel sheet |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3415379B2 (en) * | 1996-11-21 | 2003-06-09 | Ｊｆｅスチール株式会社 | Insulating coating on grain-oriented silicon steel sheet and method of forming the same |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5419850A (en) * | 1977-07-13 | 1979-02-14 | Sharp Kk | Electronic type sewing machine |
| JPS55158229A (en) * | 1979-05-28 | 1980-12-09 | Kawasaki Steel Corp | Unformly heating method of coil in batch type tight coil annealing furnace |
-
1984
- 1984-04-18 JP JP7780684A patent/JPS60221522A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5419850A (en) * | 1977-07-13 | 1979-02-14 | Sharp Kk | Electronic type sewing machine |
| JPS55158229A (en) * | 1979-05-28 | 1980-12-09 | Kawasaki Steel Corp | Unformly heating method of coil in batch type tight coil annealing furnace |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013133503A (en) * | 2011-12-27 | 2013-07-08 | Jfe Steel Corp | Method of producing grain-oriented electromagnetic steel sheet |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60221522A (en) | 1985-11-06 |
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