JP2004084053A

JP2004084053A - Electromagnetic steel sheet having remarkably superior magnetic property, and manufacturing method therefor

Info

Publication number: JP2004084053A
Application number: JP2002345999A
Authority: JP
Inventors: Hidekuni Murakami; 村上　英邦
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2002-06-26
Filing date: 2002-11-28
Publication date: 2004-03-18

Abstract

<P>PROBLEM TO BE SOLVED: To stably manufacture a high-strength non-grain-oriented electromagnetic steel sheet which has a high tensile strength TS of 60 kg/mm<SP>2</SP>or higher, abrasion resistance and a superior magnetic property of a magnetic flux density B50 of 1.60 T or higher, by the use of on-line production system with the same easiness as in the manufacture of an ordinary electromagnetic steel sheet, for instance, in cold rolling. <P>SOLUTION: This electromagnetic steel sheet includes, by mass%, 0.0040% or less C, 0.2-3.5% Si, 0.05-3.0% Mn, 0.30% or less P, 0.0040% or less S, 2.50% or less Al, 0.6-8.0% Cu, 0.0040% or less N, and a metallic phase consisting of Cu with diameters of 1.0 μm or less in the steel material. The manufacturing method is characterized by a heat treatment of holding it at a temperature of 450 to 720°C for 30 seconds or longer. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、高強度電磁鋼板、特に高強度無方向性電磁鋼板に係わり、高速回転機用の低鉄損、かつ高磁束密度で強度の高い磁性材料および電磁開閉器用の耐摩耗性に優れた磁性材料とその製造方法に関する。
【０００２】
【従来の技術】
従来、回転機器に要求されていた回転数は、高々１０万ｒｐｍ　程度であり、ローター（回転子）用材料には積層された電磁鋼板が用いられてきた。最近、２０〜３０万ｒｐｍ　もの超高速回転が要求されるようになり、ローターに加わる遠心力が、電磁鋼板の強度を上回る可能性が出てきた。さらにローターに磁石を組み込む構造のモーターも多くなっており、ローターの回転中にローター材料自身に加わる荷重は大きなものとなっており、疲労強度の面でも材料の強さが問題となることが多くなっている。
【０００３】
また、電磁開閉器はその用途上、使用するにつれて接触面が摩耗するため、電磁特性だけでなく耐摩耗性の優れた磁性材料が望まれる。
【０００４】
このようなニーズに対応して、最近では強度が高い無方向性電磁鋼板について検討され、いくつか提案されている。例えば、特許文献１や特許文献２では、Ｓｉ含有量を高め、さらにＭｎ，Ｎｉ，Ｍｏ，Ｃｒなどの固溶体強化成分の１種または２種以上を含有させたスラブを素材とすることが提案されているが、圧延時に板破断の発生が頻発する恐れがあり、生産性の低下、歩留りの低下をもたらすなど改善の余地があり、しかもＮｉやＭｏ，Ｃｒを多量に含有しているために極めて高価な材料となる。
【０００５】
さらに、特許文献３では、２．５％以上のＳｉを含有する溶鋼から、急冷凝固法により高強度無方向性鋼板を製造することを開示している。また、特許文献４では、２．５％以上の高Ｓｉ鋼を２．０％以下の低Ｓｉ鋼で包むことにより圧延性の改善を図ることを開示している。これらの提案は何れもプロセスが特殊であるために、通常の電磁鋼板の製造設備では製造できず、工業的に生産することが難しいと考えられる。
【０００６】
以上のような固溶元素による強化を活用するものでは、磁気特性の面からは本質的に飽和磁束密度が低下してしまうため製品板の磁束密度も低くならざるを得ない。また、結晶組織の面からも本質的に組織を微細化してしまうため、高強度化の点では好ましい反面、鉄損が上昇してしまうという問題がある。
【０００７】
また、材料の強度を高めるには析出物を活用することも考えられるが、析出物も析出物自身の影響や結晶組織の微細化を介して磁束密度や鉄損の観点からは磁気特性を劣化させてしまう。このように、高強度電磁鋼板では本来必要とされるはずの磁気特性が顕著に劣化してしまうことが本質的な問題となっている。
【０００８】
特に、結晶組織の微細化や析出物により強化した材料では、モーターなどの電気部材として加工する際に鋼板に導入される加工歪を除去するための歪取り焼鈍（ＳＲＡ）工程で、その高温保持中に起きる結晶組織の粗大化や、析出物の粗大化を避けることができず、強度の低下が起きてしまう。また、高強度材の使用は電気部材への加工時、特に剪断工程において金型の磨耗を早めることにもなるため、電気部材の製造コストを上昇させる要因にもなる。
【０００９】
【特許文献１】
特開平１−１６２７４８号公報
【特許文献２】
特開昭６１−８４３６０号公報
【特許文献３】
特開昭６１−８７８４８号公報
【特許文献４】
特開平８−４１６０１号公報
【００１０】
【発明が解決しようとする課題】
このように、高強度の電磁鋼板について多くの提案がなされているが、必要な磁気特性を確保しつつ、通常の電磁鋼板製造設備を用いて、工業的に安定して製造するまでに到っていないというのが実情である。また、電気部材への加工後に行なわれる歪取り焼鈍工程での軟質化や、電気部材への加工時の金型の磨耗などの残された課題も多い。
【００１１】
本発明は、抗張力（ＴＳ）が６０ｋｇ／ｍｍ^２　以上の高強度で、耐摩耗性を有するとともに、磁束密度（Ｂ５０）が１．６０Ｔ以上の優れた磁気特性を兼ね備えた高強度無方向性電磁鋼板、例えば冷間圧延性など通常の電磁鋼板と変わることなく、安定してオンラインで製造することを目的とする。
【００１２】
また同様に、電気部材の加工が完了するまでは比較的軟質で、電気部材への加工後の熱処理により硬質化し、電気部材として使用する際には高強度および耐摩耗性などの特性をもつとともに、良好な磁気特性を兼ね備えた電磁鋼板を製造することを目的とする。
【００１３】
【課題を解決するための手段】
本発明は上記課題を解決するためになされたものであり、その要旨は以下のとおりである。
【００１４】
（１）質量％で、Ｃ：０．００４０％以下、Ｓｉ：０．２〜３．５％、Ｍｎ：０．０５〜３．０％、Ｐ：０．３０％以下、Ｓ：０．００４０％以下、Ａｌ：２．５０％以下、Ｃｕ：０．６〜８．０％、Ｎ：０．００４０％以下を含有し、残部Ｆｅおよび不可避的不純物からなり、かつ、鋼材内部に直径１．０μｍ以下のＣｕからなる金属相を含有することを特徴とする磁気特性の著しく優れた電磁鋼板。
【００１５】
（２）質量％で、さらに、Ｎｂ：０．０２％以下、Ｔｉ：０．０１０％以下、Ｂ：０．０１０％以下、Ｎｉ：２．５％以下、Ｃｒ：１０．０％以下の１種または２種以上を含有することを特徴とする（１）に記載の磁気特性の著しく優れた電磁鋼板。
【００１６】
（３）質量％で、さらに、Ｍｏ，Ｗ，Ｓｎ，Ｓｂ，Ｍｇ，Ｃａ，Ｃｅ，Ｃｏの１種または２種以上を合計で０．５％以下含有することを特徴とする（１）または（２）記載の磁気特性の著しく優れた電磁鋼板。
【００１７】
（４）前記鋼材内部に存在するＣｕからなる金属相の数密度が０．２個／μｍ^３　以上である（１）〜（３）のいずれかの項に記載の磁気特性の著しく優れた電磁鋼板。
【００１８】
（５）前記鋼板の結晶粒の平均直径が３０〜３００μｍである（１）〜（４）のいずれかの項に記載の磁気特性の著しく優れた電磁鋼板。
【００１９】
（６）（１）〜（３）のいずれかの項に記載の成分からなる鋼材から製品板を製造する過程において、４５０℃〜７２０℃の温度域で３０秒以上保持する熱処理を行うことを特徴とする磁気特性の著しく優れた電磁鋼板の製造方法。
【００２０】
（７）前記熱処理として、最終熱処理工程の７５０℃以上の温度域からの冷却過程において４５０℃〜７２０℃の温度域で３０秒以上保持することを特徴とする（６）記載の磁気特性の著しく優れた電磁鋼板の製造方法。
【００２１】
（８）（６）または（７）記載の熱処理の後、８００℃を超える温度域に２０秒以上保持しないことを特徴とする磁気特性の著しく優れた電磁鋼板の製造方法。
【００２２】
（９）電気部品に加工後の熱処理により硬質化熱処理後に該鋼材内部に存在する主としてＣｕからなる金属相の数密度が０．２個／μｍ^３　以上であることを特徴とする（１）〜（３）のいずれかの項に記載の磁気特性の著しく優れた電磁鋼板。
【００２３】
（１０）電気部品に加工後の熱処理により硬質化熱処理後に該鋼材内部に存在する主としてＣｕからなる金属相の平均直径０．２０μｍ以下であることを特徴とする（１）〜（３），（９）のいずれかの項に記載の磁気特性の著しく優れた電磁鋼板。
【００２４】
（１１）電気部品に加工後の熱処理により硬質化熱処理後に結晶粒の平均直径が３０〜３００μｍであることを特徴とする（１）〜（３），（９），（１０）のいずれかの項に記載の磁気特性の著しく優れた電磁鋼板。
【００２５】
（１２）電気部品に加工後の熱処理により硬質化熱処理前後により鋼材内部の直径０．１０μｍ以下の主としてＣｕからなる金属相の数密度が１０倍以上に増加することを特徴とする（１）〜（３），（９）〜（１１）のいずれかの項に記載の磁気特性の著しく優れた電磁鋼板。
【００２６】
（１３）電気部品に加工後の熱処理により硬質化熱処理により引張強度が３０ＭＰａ　以上上昇することを特徴とする（１）〜（３），（９）〜（１２）のいずれかの項に記載の磁気特性の著しく優れた電磁鋼板。
【００２７】
（１４）電気部品に加工後の熱処理により硬質化熱処理により鋼材の硬度が１．１倍以上に増加することを特徴とする（１）〜（３），（９）〜（１３）のいずれかの項に記載の磁気特性の著しく優れた電磁鋼板。
【００２８】
（１５）（１）〜（３）のいずれかの項に記載の成分からなる鋼材から製品板を製造する過程において、冷延前の熱延工程で仕上圧延後の７５０℃以上の温度域からの冷却過程において４５０℃〜７００℃の温度域での滞留時間を３００秒以下とし、その後７５０℃を超える温度域に保持することなく冷延することにより電気部品に加工後の熱処理により硬質化することを特徴とする磁気特性の著しく優れた電磁鋼板の製造方法。
【００２９】
（１６）熱延、冷延の後の最終熱処理工程で７５０℃以上に２０秒以上保持し、その後７５０℃以上の温度域からの冷却過程において４５０℃〜７００℃の温度域での滞留時間を６０秒以下とし、その後７５０℃を超える温度域に保持しないことにより電気部品に加工後の熱処理により硬質化することを特徴とする（１５）記載の磁気特性の著しく優れた電磁鋼板の製造方法。
【００３０】
（１７）（１）〜（３），（９）〜（１４）のいずれかに記載の電磁鋼板を、もしくは（１５），（１６）のいずれかに記載の方法により製造された電磁鋼板を４５０℃〜７００℃の温度域で３０秒以上保持し、その後７００℃を超える温度域に２０秒以上保持しない工程をへて電気部品とすることにより電気部品に加工後の熱処理により硬質化することを特徴とする磁気特性の著しく優れた電磁鋼板の製造方法。
【００３１】
（１８）前記熱処理方法として、鋼板の電気部品への加工後の熱処理における熱処理温度から７００℃までの冷却過程の平均冷却速度を１０℃／秒以上とし、４５０℃〜７００℃の温度域で３０秒以上保持し、その後７００℃を超える温度域に２０秒以上保持しない工程をへて電気部品とすることにより電気部品に加工後の熱処理により硬質化することを特徴とする（１７）記載の磁気特性の著しく優れた電磁鋼板の製造方法。
【００３２】
【発明の実施の形態】
本発明者らは、前記目的を達成すべく種々実験し検討を重ねてきた。即ち本発明は、Ｃ：０．００４０％以下、Ｓｉ：０．５〜３．５％、Ｍｎ：０．０５〜３．０％、Ｐ：０．３０％以下、Ｓ：０．００４０％以下、Ａｌ：２．５０％以下、Ｃｕ：０．６〜８．０％、Ｎ：０．００４０％以下を含有する鋼材であって、結晶組織を微細化させないような製造工程条件を経て微細なＣｕからなる金属相を電磁鋼板内に生成させることにより、板破断などのトラブルを起こすことなく安定した製造方法により高強度でかつ磁気特性のすぐれた電磁鋼板を得るものである。
【００３３】
また、本発明は、結晶組織を微細化させずかつ板破断などのトラブルを生じない安定した工程条件を経て、電磁鋼板の製造過程では微細な主としてＣｕからなる金属相を鋼板内にほとんど生成させず、電気部品への加工後の熱処理過程で微細な主としてＣｕからなる金属相を電磁鋼板内に生成させることにより、電気部品への加工時に良好な加工性を有し、かつ電気部品としての使用時に硬質かつ磁気特性が良好となる電磁鋼板を得るものである。
【００３４】
先ず、本発明による高強度電磁鋼板の成分組成について説明する。
【００３５】
Ｃは磁気特性を劣化させるので０．００４０％以下とする。スラブの段階までは脱酸効率の観点からより高いＣを含有させておき、コイルとした後の脱炭焼鈍により０．００４０％以下までＣを減じることも可能である。製造コストの観点からは溶鋼段階で脱ガス設備によりＣ量を低減しておくことが有利で、０．００２０％以下とすれば鉄損低減の効果が著しく、高強度化のために炭化物等の非金属析出物を用いない本発明鋼においては０．００１５％とすることがさらに好ましい。
【００３６】
Ｓｉは鋼の固有抵抗を高めて渦電流を減らし、鉄損を低下せしめるとともに、抗張力を高めるが、添加量が０．２％未満ではその効果が小さい。低Ｓｉ鋼では鋼の脆化もほとんどなく、Ｓｉ含有量を増大させれば磁気特性を劣化させず、特に鉄損を低減しつつ強度を高めることが可能であるため本発明を適用するメリットは小さいため、好ましくは１．０％以上、さらに好ましくは２．０％以上Ｓｉを含有する鋼を対象とする。また３．５％を超えると鋼を脆化させ、さらに製品の磁束密度を低下させるため３．５％以下とする。
【００３７】
Ｍｎは鋼の強度を高めるため積極的に添加してもよいが、高強度化の主たる手段として微細金属相を活用する本発明鋼ではこの目的のためには特に必要としない。固有抵抗を高めまたは硫化物を粗大化させ結晶粒成長を促進することで鉄損を低減させる目的で添加するが過剰な添加は磁束密度を低下させるので、０．０５〜３．０％とする。好ましくは０．５％〜１．２％である。
【００３８】
Ｐは抗張力を高める効果の著しい元素であるが、上記のＭｎと同様、本発明鋼ではあえて添加する必要はない。０．３％を超えると脆化が激しく、工業的規模での熱延、冷延等の処理が困難になるため、上限を０．３０％とする。
【００３９】
Ｓは本発明鋼で必須の元素であるＣｕと結合し易くＣｕ硫化物を形成し本発明で重要となるＣｕを主体とする金属相の形成挙動に影響を及ぼし強化効率を低下させる場合がある。また生成された硫化物は磁気特性、特に鉄損を劣化させる場合があるので、Ｓの含有量はできるだけ低いことが好ましく、０．００４０％以下と限定する。好ましくは０．００２０％以下、さらに好ましくは０．００１０％以下である。
【００４０】
Ａｌは通常、脱酸剤として添加されるが、Ａｌの添加を抑えＳｉにより脱酸を図ることも可能である。Ａｌ量が０．００５％程度以下のＳｉ脱酸鋼ではＡｌＮが生成しないため鉄損を低減する効果もある。逆に積極的に添加しＡｌＮの粗大化を促進するとともに固有抵抗増加により鉄損を低減させることもできるが、２．５０％を超えると脆化が問題になるため、２．５０％以下とする。
【００４１】
Ｃｕは本発明では必須の元素である。鋼板中にＣｕを主体とする金属相を形成させ磁気特性に悪影響を及ぼさない範囲で高強度化を図るための範囲として０．６〜８．０％に限定する。好ましくは０．８〜４．０％である。Ｃｕの含有量が低いと高強度化効果が小さくなるとともに高強度化効果を得るための熱処理条件が狭い範囲に限定され、製造条件の管理、生産調整の自由度が小さくなる。また、Ｃｕの含有量が高いと磁気特性への影響が大きくなり特に鉄損の上昇が著しくなる。特に鋼への固溶限を超えた分のＣｕは固溶Ｃｕとして高強度化に寄与するものの本発明での主目的であるＣｕ金属相に比較して効率が悪く、また磁気特性劣化への影響も大きくなる。また、過剰なＣｕは熱履歴によっては望まない工程において鋼中に金属相を形成し、例えば、熱延中などに高温で比較的粗大なＣｕ金属相を形成するため、その後の微細な金属相の形成に好ましくない働きをしたり、磁気特性に悪影響を及ぼす場合もある。特に好ましい範囲は１．０〜２．８％である。
【００４２】
ＮはＣと同様に磁気特性を劣化させるので０．００４０％以下に限定する。窒化物による強度上昇を期待しない本発明鋼では低いほど好ましく、０．００２７％以下とすれば磁気特性は特に良好となる。
【００４３】
これまでの高強度電磁鋼板で高強度化のために利用されている殆どの元素は添加コストが問題視されるだけではなく磁気特性に少なからず悪影響を及ぼすため、本発明では高強度化の目的のためにあえて添加する必要はない。あえて強化元素として添加する場合にはコスト上昇と磁気特性劣化との兼ね合いからＮｂ，Ｔｉ，Ｂ，Ｎｉ，Ｃｒの１種または２種以上を添加するが、その添加量は、Ｎｂ：０．０２％以下、Ｔｉ：０．０１０％以下、Ｂ：０．０１０％以下、Ｎｉ：２．５％以下、Ｃｒ：１０．０％以下程度とする。特に、Ｎｉは本発明鋼で必須元素であるＣｕによる熱延時の表面荒れ（Ｃｕヘゲ）の防止に有効であることが知られており、この目的を兼ねて積極的に添加することもできる。
【００４４】
Ｂは結晶粒界に偏折し、Ｐの粒界偏折による脆化を抑制する効果があるが、本発明鋼では従来の固溶強化主体の高強度電磁鋼板のように脆化が特に問題とはならないことからこの目的での添加は重要ではない。むしろ固溶Ｂによる集合組織への影響により磁束密度を向上させる目的で添加する。０．０１０％を超えると著しく脆化するため、上限を０．０１０％とする。
【００４５】
ＮｂおよびＴｉは鋼板中で炭化物、窒化物または硫化物等の微細な析出物を形成し、高強度化に有効な元素ではあるが同時に磁気特性、特に鉄損を顕著に劣化させる。高強度化の主たる手段として微細な炭、窒化物等を利用しない本発明鋼ではむしろ有害な元素となる。このため上限をそれぞれ０．０１０％とする。好ましくは０．００５０％以下、さらに好ましくは０．００３０％以下で、良好な鉄損を得ることが可能となる。
【００４６】
Ｎｉは本発明鋼で必須元素であるＣｕによる熱延時の表面荒れ（Ｃｕヘゲ）の防止に有効であることが知られており、この目的を兼ねて積極的に添加することもできる。また、磁気特性への悪影響が比較的小さく、かつ高強度化にも効果が認められるため高強度電磁鋼板では使用されることが多い元素である。また、耐食性の向上にも有効であるが、添加コストや磁気特性への悪影響を考え上限を２．５％とすることが好ましい。
【００４７】
Ｃｒは耐食性の向上や、高周波域での磁気特性向上のため添加される元素であるが、やはり添加コストや磁気特性への悪影響を考え上限を１０．０％とすることが好ましい。
【００４８】
また、その他の微量元素については、鉱石やスクラップなどから不可避的に含まれる程度の量に加え、様々な目的で添加しても本発明の効果は何ら損なわれるものではない。これらの微量元素についての不可避的な含有量は通常、各元素とも０．００５％以下程度であるが、様々な目的で０．０１％程度以上に添加することが可能である。この場合もコストや磁気特性の兼ね合いからＭｏ，Ｗ，Ｓｎ，Ｓｂ，Ｍｇ，Ｃａ，Ｃｅ，Ｃｏの１種または２種以上を合計で０．５％以下含有することができる。
【００４９】
前記成分を含む鋼は、通常の電磁鋼板と同様に転炉で溶製され、連続鋳造でスラブとされ、ついで熱間圧延、熱延板焼鈍、冷間圧延、仕上焼鈍などの工程で製造される。これらの工程に加え絶縁皮膜の形成や脱炭工程などを経ることも本発明の効果を何ら損なうものではない。また、通常の工程ではなく急冷凝固法による薄帯の製造や熱延工程を省略する薄スラブ、連続鋳造法などの工程によって製造しても問題ない。
【００５０】
本発明で特徴的な特異な金属相を鋼板内に形成するには以下のような熱履歴を経ることが重要である。それは、製品板を製造する過程において、４５０℃〜７２０℃の温度域で３０秒以上保持することにある。さらに、その後８００℃を超える温度域に２０秒以上保持しない工程を経ることが好ましい。
【００５１】
以上のような工程を経ることで成分、サイズおよび数密度において特徴的なＣｕ金属相が効率的に形成され磁気特性を殆ど損なわず高強度化を図ることができる。一方、このような金属相の生成を意識しない通常の熱処理条件を経た場合、添加したＣｕの大半は強化能が低く磁気特性劣化効果が大きい固溶ＣｕまたはＣｕ硫化物として存在することになる。
【００５２】
この熱処理工程を経た後は鋼材が高強度化するので、この熱処理工程は圧延工程の後に行なわれ、かつ再結晶焼鈍など他の目的で必要とされる熱処理と同時に行なわれることが生産性の観点からは有利である。すなわち、冷延電磁鋼板であれば冷間圧延後の最終熱処理工程、熱延電磁鋼板であれば熱間圧延後の最終熱処理工程での７５０℃以上の温度域からの冷却過程において４５０℃〜７２０℃の温度域で３０秒以上保持することが好ましい。
【００５３】
また、目的とする特性などによってはさらに熱処理を加えることがあるが、その場合、８００℃を超える温度域に２０秒以上保持しないようにすることが好ましい。温度もしくは時間がこれを超えるような熱処理を行うと、形成されたＣｕ金属相が再固溶するか、逆に終結して粗大な金属相になる場合がある。
【００５４】
本発明は結晶組織微細化による強化を利用していないので、鋼板を打ち抜き、モーター部品に加工する際に材料に導入される歪を回復させ、結晶粒を成長させることで磁性の回復・向上を図るためのＳＲＡ（歪取り焼鈍）を施しても強度の劣化が小さい。
【００５５】
また、本発明で特徴とする特異な金属相を電磁鋼板を電気部品に加工した後の鋼板内に形成するには以下のような熱履歴を経ることが重要である。それは製品板を製造する過程および電気部品に加工した後の熱処理過程において、４５０℃〜７００℃の温度域での保持時間およびその後の熱履歴を制御することである。
【００５６】
すなわち、最終的な加工工程である、電磁鋼板を電気部品として利用するための打ち抜き・組み立てを行なうまでに主として鋼板に付与される熱処理として、熱延時の仕上圧延後冷延前の熱履歴および冷延後の焼鈍工程での各々の熱履歴について、７５０℃以上の温度域からの冷却過程における４５０℃〜７００℃の温度域での滞留時間を各々３００秒または６０秒以下とし、その後７５０℃を超える温度域に保持しないようにすることが好ましい。
【００５７】
そして硬質化は、電磁鋼板についての最終的な加工工程である、電磁鋼板を電気部品として利用するための打ち抜き・組み立てされた後に行なわれ、４５０℃〜７００℃の温度域で３０秒以上保持し、その後７００℃を超える温度域に保持しないような熱処理を行なうことで達成できる。この熱処理がより高温での熱処理に引き続き冷却過程で行なわれる場合には４５０℃〜７００℃の温度域での保持に至る前の７００℃までの冷却過程の平均冷却速度を１０℃／秒以上とすることが好ましく、さらに好ましくは５００℃〜６５０℃の温度域での保持に至る前の６５０℃までの冷却過程の平均冷却速度を１０℃／秒以上とする。この熱処理は加工時に材料内に意図に反して導入された歪を除去する目的で行なわれるいわゆる歪取り焼鈍工程の冷却過程でなされることが生産性の観点からは好ましく、４５０℃〜７００℃の温度域での保持に至る前の７００℃以上の最高到達温度およびその温度域での保持時間は歪の除去および結晶粒の成長という観点からのみ決定することができ、本発明の効果に関し何ら影響を及ぼすものではない。
【００５８】
この工程を経ることで好ましい工程で成分、サイズおよび数密度において特徴的な金属相が効率的に形成され磁気特性をほとんど損なわず硬質化を図ることができる。本発明鋼は硬質化のための熱処理により引張強度が３０ＭＰａ　以上上昇または硬度が１．１倍以上増加するものを対象とする。強度または硬度上昇がこれ以下のものは熱処理前にすでに硬質化されているまたは熱処理による強化能がもともと具備されていないことが考えられる。熱処理前にすでに硬質化されている場合にはモーター部品への打抜き加工が硬い材料に対して行なわれることになるため金型の磨耗の点で好ましくない。また熱処理をしても硬質化しない場合はその後のモーターとしての使用中の強度が不足することとなり本発明の目的が達成されない。より好ましい効果を得るには熱処理による引張強度の上昇で６０ＭＰａ　以上、硬度増加で１．２倍以上、さらに好ましくは引張強度の上昇で１００ＭＰａ　以上、硬度増加で１．３倍以上とする。
【００５９】
一方、本発明で制御している金属相の生成を意識しない通常の熱処理条件を経た場合、鋼成分によっては効果を検知できるだけの金属相の生成が起きる場合もあるが、添加したＣｕの大半は強化能が低く磁気特性の劣化効果が大きい固溶ＣｕまたはＣｕ硫化物または直径０．２μｍ以上の粗大な金属相として存在することになる。
【００６０】
以上のように形成される金属相は主としてＣｕからなる。これは電子顕微鏡などの回折パターンや付設されたＸ線分析機器などで同定が可能である。もちろん化学分析などこれ以外の方法によっても同定が可能なものである。本発明ではこのＣｕを主体とする金属相の直径は１．０μｍ以下とする。これ以上では高強度化の効率が著しく低下し、多量の金属相が必要となるため磁気特性への悪影響が大きくなる。高強度化効率と磁気特性の観点から、この直径は０．５０μｍ以下とすることが好ましく、さらに好ましくは０．２０μｍ以下であるが、あまりに微細であると磁気特性への悪影響が大きくなることから好ましくは０．０１μｍ以上、さらに好ましくは０．０５μｍ以上とする。
【００６１】
Ｃｕ金属相の数密度はＣｕ含有量と金属相のサイズとの関係で取りうる範囲に制限はあるが、０．２個／μｍ^３　以上とすることが好ましく、さらに好ましくは１．０個／μｍ^３　以上であり、５．０個／μｍ^３　以上とすれば高強度化の点で非常に有効となる。これらの直径および数密度は例えば電子顕微鏡観察で定量が可能である。
【００６２】
この金属相サイズと数密度の制御は、高強度化と磁気特性保持を両立する観点から非常に重要である。その理由は、これらが強度および磁気特性にそれぞれ影響するのみならず、これらを変化させたときの強度または磁気特性が変化する挙動が異なるためである。すなわち、強度上昇効果が高く、磁気特性劣化効率の低い領域に制御する必要がある。このためには前述の４５０〜６５０℃の温度範囲で温度と時間およびこの温度域に入る直前の冷却速度などを適切に制御することが有効であり、この影響は通常の条件であれば一般の析出物形成と同様に、高冷速、低温であるほど金属相サイズは微細かつ高密度となり、長時間化によりサイズは粗大化する。
【００６３】
また、本発明では高強度化の主要な手段として結晶組織の微細化を利用しないため、結晶粒径は磁気特性の観点から最適な範囲に調整が可能である。高強度化に寄与するＣｕを主体とする金属相のサイズや密度は成分のみならず、主として前述の６００℃以下での熱処理により制御が可能であるため結晶粒径はこの熱処理以前の、例えば再結晶焼鈍の最高到達温度およびその温度域での保持時間により強度とは独立に制御が可能となる。通常は８００〜１１００℃程度で２０秒〜５分程度の熱処理により３０〜３００μｍに制御される。さらに好ましくは８０〜２００μｍである。
【００６４】
本発明は電磁鋼板で従来開発されてきた材料とは全く異なる特性を有するものとなる。図１および図２は電磁鋼板について成分、強度および磁気特性の観点から本発明の特徴を示したものである。図１に示すように通常、電磁鋼板は主としてＳｉ含有量により磁気特性を造り分けている。磁気特性の観点からはＳｉは材料の電気抵抗を増大させ鉄損を低減するために添加されるが、同時に大きな固溶強化能を有するため高Ｓｉである高級グレード材では強度も高くなっている。しかし、３％を超えるＳｉ量、またはＳｉ，Ａｌ，Ｍｎなどの強化元素を合わせても６％を超えるようになると圧延性が顕著に劣化するため、通常の製造工程では鋼板の製造が困難となる。
【００６５】
圧延を回避する手段として急冷凝固で溶融状態の鋼から直接、薄膜を得る方法も考案されているが、コストや特性の点で実用化には限界がある。このため３％Ｓｉ鋼相当以上の高強度材はＮｂなどの添加に伴う炭窒化物を主とする析出物および低温焼鈍も合わせた結晶組織の微細化により高強度化を図っている。しかし、このような炭窒化物や微細な結晶組織は磁気特性、特に鉄損の点からは好ましいものではなく、図２のように鉄損の大幅な上昇は避けられない。
【００６６】
本発明は、従来高強度鋼とは異なる金属相を鋼板内に分散させることで高強度化を図るものである。この金属相は結晶粒径とは独立に制御が可能であるため、言い換えれば結晶粒成長が起こる通常７５０℃以上の温度域とは異なる、より低温域である６００℃程度で形成を制御できるため、強度と磁気特性の各々の制御という観点からの自由度が大きく、図２のように磁気特性をそれほど劣化させずに高強度化が可能となる。
【００６７】
また、図１に示すように低Ｓｉ鋼に本技術を適用することで、従来鋼より磁束密度の高い材料を得ることも可能となる。これは通常使用されるＳｉ，Ａｌ，Ｍｎなどの殆どの固溶強化元素が、鋼の飽和磁束密度を低下させるなどのため、特定磁場での磁束密度の低下が避けられないのに対し、本発明で高強度化のために利用するＣｕ金属相は飽和磁束密度の低下への効果が非常に小さいことによると思われる。また、Ｃｕ金属相は炭窒化物などの析出物に比較し磁壁移動の障害となりにくいことも原因と思われる。これは特に低磁場での磁気特性向上に有効である。
【００６８】
なお、本発明の効果は通常電磁鋼板の表面に形成されている表面皮膜の有無および種類によらず、さらに製造工程にはよらないため無方向性または方向性の電磁鋼板に適用できる。
【００６９】
用途も特に限定されるものではなく、家電または自動車等で用いられるモーターのローター用途の他、強度と磁気特性が求められる全ての用途に適用される。
【００７０】
【実施例】
（実施例１）
表１に成分を示す鋼を２５０ｍｍ厚のスラブとし以下の工程を基本的なものとし製品板を製造した。基本工程条件は、スラブ加熱温度：１１００℃、仕上板厚：２．０ｍｍ、巻取り温度：５００℃の熱延工程、仕上板厚：０．５ｍｍの冷間圧延工程、再結晶温度以上での再結晶焼鈍工程である。一部のものは途中で５００℃付近での保持による金属相析出工程を入れた。製品板についてＪＩＳ５号試験片により機械的特性、および５５ｍｍ角のＳＳＴ試験により鉄損Ｗ_{１０／４００}と磁束密度Ｂ_１０を測定した。機械的特性および磁気特性ともコイルの圧延方向およびその直角方向についての平均値を求めた。結果を表２（表１のつづき）に示す。
【００７１】
表２に示された結果から明らかなように、本発明の条件にて製造した試料は冷間圧延工程での圧延性が良好で、硬質で、さらに磁気特性も優れている。
【００７２】
【表１】

【００７３】
【表２】

【００７４】
（実施例２）
表３に成分を示す鋼を２５０ｍｍ厚のスラブとし以下の工程を基本的なものとし製品板を製造した。基本工程条件は、スラブ加熱温度：１１００℃、仕上板厚：２．０ｍｍ、巻取り温度：７００℃の熱延工程、９８０℃の温度で３０秒の熱延板焼鈍工程、仕上板厚：０．２ｍｍの冷間圧延工程、再結晶温度以上での再結晶焼鈍工程である。一部のものは途中で５００℃付近での保持による金属相析出工程を入れた。製品板についてＪＩＳ５号試験片により機械的性質、および５５ｍｍ角のＳＳＴ試験により鉄損Ｗ_{１５／５０}　と磁束密度Ｂ_５０を測定した。機械的特性および磁気特性ともコイルの圧延方向およびその直角方向についての平均値を求めた。結果を表４（表３のつづき）に示す。
【００７５】
表４に示された結果から明らかなように、本発明の条件にて製造した試料は冷間圧延工程での圧延性が良好で、硬質で、さらに磁気特性も優れている。
【００７６】
【表３】

【００７７】
【表４】

【００７８】
（実施例３）
表５に成分を示す鋼を２５０ｍｍ厚のスラブとし以下の工程を基本的なものとし製品板を製造した。基本工程条件は、スラブ加熱温度１１００℃、仕上板厚２．０ｍｍ、巻取り温度３００℃以下の熱延工程、仕上板厚０．２ｍｍの冷間圧延工程、再結晶温度以上での再結晶焼鈍工程である。その後、打ち抜き加工後の析出熱処理のシミュレーションとして７５０℃付近での熱処理による組織調整および金属相析出制御を行なった。歪取り焼鈍を兼ねる場合は７５０℃２時間の熱処理後の冷却過程で析出熱処理を行なった。熱処理前後の板についてＪＩＳ５号試験片により機械的特性、および５５ｍｍ角のＳＳＴ試験により鉄損Ｗ１０／４００と磁束密度Ｂ１０を測定した。機械的特性および磁気特性ともコイルの圧延方向およびその直角方向についての平均値を求めた。また、打抜き金型の磨耗については新しく製造した打抜き金型で鋼板を打抜き、打抜き回数に応じて鋼板に発生するカエリの大きさの変化から評価した。金型の磨耗が大きいものは比較的少ない打抜き回数で鋼板のカエリが大きくなる。結果を表６（表５のつづき）に示す。
【００７９】
表６に示された結果から明らかなように、本発明の条件にて製造した試料析出熱処理前は軟質であるため冷間圧延工程での圧延性が良好かつ打抜き金型の磨耗が小さく、析出処理後に硬質となりかつ磁気特性も優れている。
【００８０】
【表５】

【００８１】
【表６】

【００８２】
（実施例４）
表７に成分を示す鋼を２５０ｍｍ厚のスラブとし以下の工程を基本的なものとし製品板を製造した。基本工程条件は、スラブ加熱温度１１００℃、仕上板厚２．０ｍｍ、巻取り温度３００℃以下の熱延工程、９８０℃×３０秒の熱延板焼鈍工程、仕上板厚０．３５ｍｍの冷間圧延工程、再結晶温度以上での再結晶焼鈍工程である。その後、打ち抜き加工後の析出熱処理のシミュレーションとして７５０℃付近での熱処理による組織調整および金属相析出制御を行なった。歪取り焼鈍を兼ねる場合は７５０℃２時間の熱処理後の冷却過程で析出熱処理を行なった。熱処理前後の板についてＪＩＳ５号試験片により機械的性質、および５５ｍｍ角のＳＳＴ試験により鉄損Ｗ１５／５０と磁束密度Ｂ５０を測定した。機械的特性および磁気特性ともコイルの圧延方向およびその直角方向についての平均値を求めた。また、打抜き金型の磨耗については新しく製造した打抜き金型で鋼板を打抜き、打抜き回数に応じて鋼板に発生するカエリの大きさの変化から評価した。金型の磨耗が大きいものは比較的少ない打抜き回数で鋼板のカエリが大きくなる。結果を表８（表７のつづき）に示す。
【００８３】
表８に示された結果から明らかなように、本発明の条件にて製造した試料析出熱処理前は軟質であるため冷間圧延工程での圧延性が良好かつ打抜き金型の磨耗が小さく、析出処理後に硬質となりかつ磁気特性も優れている。
【００８４】
【表７】

【００８５】
【表８】

【００８６】
【発明の効果】
以上説明したように、本発明は硬質で磁気特性のすぐれた高強度電磁鋼板を安定して製造することができる。これにより磁気特性を劣化させず、強度、疲労強度、耐磨耗性の確保が可能となるため超高速回転モーターやローターに磁石を組み込んだモーターおよび電磁開閉器用材料の高効率化、小型化、超寿命化などが達成される。
【図面の簡単な説明】
【図１】本発明鋼板のＳｉ含有量と引っ張り強度の関係を示す概念図。
【図２】本発明鋼板の引っ張り強度と鉄損の関係を示す概念図。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-strength electrical steel sheet, particularly to a high-strength non-oriented electrical steel sheet, and has a low iron loss for a high-speed rotating machine, and a magnetic material having a high strength with a high magnetic flux density and excellent wear resistance for an electromagnetic switch. The present invention relates to a magnetic material and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, the number of rotations required for rotating equipment is at most about 100,000 rpm, and laminated electromagnetic steel sheets have been used as a material for a rotor (rotor). Recently, ultra high speed rotation of 20 to 300,000 rpm has been required, and there is a possibility that the centrifugal force applied to the rotor may exceed the strength of the magnetic steel sheet. In addition, many motors have a structure that incorporates a magnet in the rotor.The load applied to the rotor material itself during rotation of the rotor is large, and the strength of the material often poses a problem in terms of fatigue strength. Has become.
[0003]
In addition, since the contact surface of the electromagnetic switch wears as it is used, a magnetic material having not only electromagnetic characteristics but also excellent wear resistance is desired.
[0004]
In response to such needs, recently, non-oriented electrical steel sheets having high strength have been studied and some proposals have been made. For example, Patent Literature 1 and Patent Literature 2 propose that a slab containing Si or one or more solid solution strengthening components such as Mn, Ni, Mo, and Cr be used as a raw material. However, there is a possibility that sheet breakage may occur frequently during rolling, and there is room for improvement such as a decrease in productivity and a decrease in yield. Further, since Ni, Mo and Cr are contained in a large amount, they are extremely high. It becomes an expensive material.
[0005]
Further, Patent Document 3 discloses that a high-strength non-oriented steel sheet is manufactured from a molten steel containing 2.5% or more of Si by a rapid solidification method. Patent Document 4 discloses that the rollability is improved by wrapping a high Si steel of 2.5% or more with a low Si steel of 2.0% or less. Since any of these proposals has a special process, it cannot be manufactured with ordinary magnetic steel sheet manufacturing equipment, and it is considered that industrial production is difficult.
[0006]
In the case of utilizing the strengthening by the solid solution element as described above, the saturation magnetic flux density is essentially reduced from the viewpoint of magnetic properties, so that the magnetic flux density of the product plate must be reduced. Further, since the structure is essentially refined from the viewpoint of the crystal structure, it is preferable in terms of increasing the strength, but there is a problem that the iron loss increases.
[0007]
In order to increase the strength of the material, it is conceivable to use precipitates, but the precipitates also deteriorate magnetic properties from the viewpoint of magnetic flux density and iron loss through the influence of the precipitates themselves and the refinement of the crystal structure. Let me do it. As described above, it is an essential problem that magnetic properties that are originally required in a high-strength electrical steel sheet are significantly deteriorated.
[0008]
In particular, in the case of a material reinforced by refinement of a crystal structure or a precipitate, the material is maintained at a high temperature in a strain relief annealing (SRA) process for removing a work strain introduced into a steel plate when working as an electric member such as a motor. The coarsening of the crystal structure and the coarsening of precipitates occurring inevitably cannot be avoided, resulting in a decrease in strength. In addition, the use of a high-strength material accelerates the wear of a mold during processing into an electric member, particularly in a shearing step, and thus also increases the manufacturing cost of the electric member.
[0009]
[Patent Document 1]
JP-A-1-162748
[Patent Document 2]
JP-A-61-84360
[Patent Document 3]
JP-A-61-87848
[Patent Document 4]
JP-A-8-41601
[0010]
[Problems to be solved by the invention]
As described above, many proposals have been made for high-strength electrical steel sheets. However, while securing the necessary magnetic properties, the production has become industrially stable using ordinary electrical steel sheet manufacturing equipment. The fact is that they are not. In addition, there are many remaining problems such as softening in a strain relief annealing process performed after processing into an electric member and wear of a mold during processing into an electric member.
[0011]
The present invention has a tensile strength (TS) of 60 kg / mm. ² A high-strength non-oriented electrical steel sheet having the above-mentioned high strength, wear resistance, and excellent magnetic properties with a magnetic flux density (B50) of 1.60 T or more, such as a normal electrical steel sheet such as a cold-rollable steel sheet. The aim is to manufacture online without change.
[0012]
Also, similarly, it is relatively soft until the processing of the electric member is completed, becomes hard by heat treatment after processing into the electric member, and has properties such as high strength and wear resistance when used as an electric member. It is an object of the present invention to manufacture an electromagnetic steel sheet having good magnetic properties.
[0013]
[Means for Solving the Problems]
The present invention has been made to solve the above problems, and the gist thereof is as follows.
[0014]
(1) In mass%, C: 0.0040% or less, Si: 0.2 to 3.5%, Mn: 0.05 to 3.0%, P: 0.30% or less, S: 0.0040 % Or less, Al: 2.50% or less, Cu: 0.6 to 8.0%, N: 0.0040% or less, the balance being Fe and unavoidable impurities, and having a diameter of 1. An electromagnetic steel sheet having extremely excellent magnetic properties, characterized by containing a metal phase composed of Cu of 0 μm or less.
[0015]
(2) In mass%, Nb: 0.02% or less, Ti: 0.010% or less, B: 0.010% or less, Ni: 2.5% or less, Cr: 10.0% or less. (1) The magnetic steel sheet according to (1), which has excellent magnetic properties.
[0016]
(3) It is characterized in that it further contains one or more of Mo, W, Sn, Sb, Mg, Ca, Ce, and Co in a mass% of 0.5% or less in total (1) or (2) An electrical steel sheet having remarkably excellent magnetic properties as described in (2).
[0017]
(4) The number density of the metal phase composed of Cu existing inside the steel material is 0.2 / μm. ³ The magnetic steel sheet according to any one of the above (1) to (3), which has excellent magnetic properties.
[0018]
(5) The electrical steel sheet according to any one of (1) to (4), wherein the average diameter of crystal grains of the steel sheet is 30 to 300 μm.
[0019]
(6) In the process of manufacturing a product sheet from a steel material comprising the components described in any one of the above items (1) to (3), performing a heat treatment of maintaining the temperature in a temperature range of 450 ° C to 720 ° C for 30 seconds or more. A method for producing an electrical steel sheet having remarkably excellent magnetic properties.
[0020]
(7) The magnetic properties according to (6), wherein the heat treatment is performed by maintaining the magnetic properties in a temperature range of 450 ° C. to 720 ° C. for 30 seconds or more in a cooling process from a temperature range of 750 ° C. or more in the final heat treatment step. Excellent manufacturing method of electrical steel sheet.
[0021]
(8) A method for producing a magnetic steel sheet having extremely excellent magnetic properties, wherein the magnetic steel sheet is not kept in a temperature range exceeding 800 ° C. for 20 seconds or more after the heat treatment according to (6) or (7).
[0022]
(9) The number density of the metal phase mainly composed of Cu existing inside the steel material after the heat treatment for hardening by the heat treatment after processing the electric component is 0.2 / μm. ³ The magnetic steel sheet according to any one of (1) to (3), which has excellent magnetic properties.
[0023]
(10) An average diameter of a metal phase mainly composed of Cu existing in the steel material after heat treatment for hardening by heat treatment after processing into an electric component is 0.20 μm or less (1) to (3), ( The magnetic steel sheet according to any one of 9), which is excellent in magnetic properties.
[0024]
(11) Any one of (1) to (3), (9) and (10), wherein the average diameter of the crystal grains after heat treatment for hardening by heat treatment after processing the electric component is 30 to 300 μm. An electrical steel sheet having remarkably excellent magnetic properties as described in the item.
[0025]
(12) The number density of a metal phase mainly composed of Cu having a diameter of 0.10 μm or less inside the steel material increases by 10 times or more before and after the hardening heat treatment by heat treatment after processing into an electric component. (3) The electrical steel sheet according to any one of (9) to (11), which is excellent in magnetic properties.
[0026]
(13) The method according to any one of (1) to (3), (9) to (12), wherein the tensile strength increases by 30 MPa or more by the heat treatment for hardening due to the heat treatment after processing the electric component. Electrical steel sheet with remarkably excellent magnetic properties.
[0027]
(14) Any one of (1) to (3) and (9) to (13), wherein the hardness of the steel material is increased to 1.1 times or more by the heat treatment for hardening due to the heat treatment after processing the electric component. The magnetic steel sheet having remarkably excellent magnetic properties according to the item.
[0028]
(15) In the process of manufacturing a product sheet from a steel material comprising the components described in any one of (1) to (3), from a temperature range of 750 ° C. or more after finish rolling in a hot rolling step before cold rolling. In the cooling process, the residence time in the temperature range of 450 ° C. to 700 ° C. is set to 300 seconds or less, and thereafter, the steel is cold-rolled without being maintained in a temperature range exceeding 750 ° C., thereby being hardened by heat treatment after processing into an electric component. A method for producing an electrical steel sheet having remarkably excellent magnetic properties.
[0029]
(16) In the final heat treatment step after hot rolling and cold rolling, the temperature is kept at 750 ° C. or more for 20 seconds or more, and then, in the cooling process from the temperature range of 750 ° C. or more, the residence time in the temperature range of 450 ° C. to 700 ° C. (15) The method for producing an electrical steel sheet having extremely excellent magnetic properties according to (15), wherein the electrical component is hardened by heat treatment after processing by keeping it at a temperature of not more than 750 ° C. for not more than 60 seconds.
[0030]
(17) An electromagnetic steel sheet according to any one of (1) to (3) and (9) to (14), or an electromagnetic steel sheet manufactured by the method according to any of (15) and (16). The electric component is hardened by heat treatment after processing into an electric component by performing a process of maintaining the device in a temperature range of 450 ° C. to 700 ° C. for 30 seconds or more and thereafter not maintaining the temperature in a temperature range exceeding 700 ° C. for 20 seconds or more. A method for producing an electrical steel sheet having remarkably excellent magnetic properties, characterized by:
[0031]
(18) As the heat treatment method, the average cooling rate in the cooling process from the heat treatment temperature to 700 ° C. in the heat treatment after the processing of the steel sheet into the electric part is set to 10 ° C./sec or more, and the average cooling rate is 30 ° C. in the temperature range of 450 ° C. to 700 ° C. (17) The magnetic material according to (17), wherein the electric component is hardened by heat treatment after processing into an electric component by performing a process in which the electric component is held for not less than 700 ° C. for at least 20 seconds and then not held for more than 20 seconds in a temperature range exceeding 700 ° C. A method for manufacturing electrical steel sheets with remarkably excellent characteristics.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have conducted various experiments and studies to achieve the above object. That is, in the present invention, C: 0.0040% or less, Si: 0.5 to 3.5%, Mn: 0.05 to 3.0%, P: 0.30% or less, S: 0.0040% or less. , Al: 2.50% or less, Cu: 0.6 to 8.0%, N: 0.0040% or less, which is fine through a manufacturing process condition that does not refine the crystal structure. By producing a metallic phase made of Cu in an electromagnetic steel sheet, an electromagnetic steel sheet having high strength and excellent magnetic properties can be obtained by a stable manufacturing method without causing troubles such as sheet breakage.
[0033]
In addition, the present invention, through a stable process conditions that do not cause troubles such as breakage of the sheet and does not refine the crystal structure, in the manufacturing process of the electromagnetic steel sheet, to generate almost fine metal phase mainly composed of Cu in the steel sheet In addition, by producing a fine metal phase mainly composed of Cu in the electrical steel sheet during the heat treatment process after processing into electrical parts, it has good workability at the time of processing into electrical parts and is used as an electrical part It is intended to obtain an electromagnetic steel sheet which is sometimes hard and has good magnetic properties.
[0034]
First, the component composition of the high-strength electrical steel sheet according to the present invention will be described.
[0035]
Since C deteriorates magnetic properties, it is set to 0.0040% or less. Up to the slab stage, higher C may be contained from the viewpoint of deoxidation efficiency, and C may be reduced to 0.0040% or less by decarburizing annealing after forming the coil. From the viewpoint of manufacturing cost, it is advantageous to reduce the amount of C by degassing equipment in the molten steel stage. If the content is 0.0020% or less, the effect of reducing iron loss is remarkable, and carbides and the like are required for high strength. In the steel of the present invention in which nonmetallic precipitates are not used, the content is more preferably 0.0015%.
[0036]
Si increases the specific resistance of the steel to reduce eddy currents, thereby reducing iron loss and increasing the tensile strength. However, the effect is small when the addition amount is less than 0.2%. With low Si steel, there is almost no embrittlement of the steel, and if the Si content is increased, the magnetic properties are not degraded. In particular, it is possible to increase the strength while reducing iron loss. Since it is small, it is preferably steel containing 1.0% or more, more preferably 2.0% or more of Si. If it exceeds 3.5%, the steel is embrittled and the magnetic flux density of the product is further reduced, so that the content is set to 3.5% or less.
[0037]
Mn may be positively added to increase the strength of the steel, but is not particularly required for this purpose in the steel of the present invention that utilizes a fine metal phase as a main means of increasing the strength. It is added for the purpose of reducing iron loss by increasing the specific resistance or coarsening the sulfide to promote the crystal grain growth, but excessive addition lowers the magnetic flux density. Therefore, it is 0.05 to 3.0%. . Preferably it is 0.5% to 1.2%.
[0038]
P is an element having a remarkable effect of increasing tensile strength, but like the above-mentioned Mn, the steel of the present invention does not need to be added. If it exceeds 0.3%, embrittlement will be severe, and it will be difficult to perform treatments such as hot rolling and cold rolling on an industrial scale, so the upper limit is made 0.30%.
[0039]
S is likely to combine with Cu, which is an essential element in the steel of the present invention, to form Cu sulfide, which may affect the formation behavior of a Cu-based metal phase which is important in the present invention, and reduce the strengthening efficiency. . Further, since the generated sulfide may deteriorate magnetic properties, particularly iron loss, the S content is preferably as low as possible, and is limited to 0.0040% or less. Preferably it is 0.0020% or less, more preferably 0.0010% or less.
[0040]
Al is usually added as a deoxidizing agent, but it is also possible to suppress the addition of Al and deoxidize with Si. Si deoxidized steel having an Al content of about 0.005% or less does not generate AlN, and thus has an effect of reducing iron loss. Conversely, it can be positively added to promote coarsening of AlN and reduce iron loss by increasing specific resistance. However, if it exceeds 2.50%, embrittlement becomes a problem. I do.
[0041]
Cu is an essential element in the present invention. The range is set to 0.6 to 8.0% as a range for increasing the strength within a range in which a metal phase mainly composed of Cu is formed in the steel sheet and magnetic properties are not adversely affected. Preferably it is 0.8 to 4.0%. When the Cu content is low, the effect of increasing the strength is reduced, and the heat treatment conditions for obtaining the effect of increasing the strength are limited to a narrow range, and the degree of freedom in managing the manufacturing conditions and adjusting the production is reduced. Further, when the content of Cu is high, the influence on the magnetic properties becomes large, and the iron loss particularly increases remarkably. In particular, the amount of Cu exceeding the solid solubility limit in steel contributes to high strength as solid solution Cu, but the efficiency is lower than that of the Cu metal phase which is the main object of the present invention, and the magnetic properties deteriorate. The effect is greater. In addition, excessive Cu forms a metal phase in the steel in an undesired process depending on the heat history. For example, a relatively coarse Cu metal phase is formed at a high temperature during hot rolling or the like. In some cases, it may have an unfavorable effect on the formation of a magnetic layer or adversely affect magnetic properties. A particularly preferred range is 1.0 to 2.8%.
[0042]
N degrades magnetic properties like C, so it is limited to 0.0040% or less. In the steel of the present invention in which the increase in strength due to nitrides is not expected, the lower the better, the more preferable it is.
[0043]
Most of the elements used to increase the strength of conventional high-strength electrical steel sheets not only have an added cost problem but also have a considerable adverse effect on magnetic properties. It is not necessary to add it for the purpose. When it is added as a strengthening element, one or two or more of Nb, Ti, B, Ni, and Cr are added in view of a balance between cost increase and deterioration of magnetic properties. %, Ti: 0.010% or less, B: 0.010% or less, Ni: 2.5% or less, Cr: 10.0% or less. In particular, Ni is known to be effective in preventing surface roughness (Cu scab) during hot rolling due to Cu, which is an essential element in the steel of the present invention, and can also be positively added for this purpose. .
[0044]
B is deflected to the grain boundaries, and has the effect of suppressing embrittlement due to the grain boundary deflection of P. However, in the steel of the present invention, embrittlement is a particular problem as in the conventional high-strength electromagnetic steel sheets mainly made of solid solution strengthening. The addition for this purpose is not important, since it does not result in the addition. Rather, it is added for the purpose of improving the magnetic flux density due to the influence of solid solution B on the texture. If it exceeds 0.010%, the material becomes extremely brittle, so the upper limit is made 0.010%.
[0045]
Nb and Ti form fine precipitates such as carbides, nitrides or sulfides in the steel sheet, and are effective elements for increasing the strength, but at the same time, remarkably deteriorate magnetic properties, particularly iron loss. In the steel of the present invention which does not use fine carbon, nitride, or the like as a main means of increasing the strength, the steel is rather a harmful element. Therefore, the upper limits are each set to 0.010%. When the content is preferably 0.0050% or less, more preferably 0.0030% or less, a good iron loss can be obtained.
[0046]
It is known that Ni is effective in preventing surface roughness (Cu scab) during hot rolling due to Cu, which is an essential element in the steel of the present invention, and can be positively added for the purpose. In addition, it is an element that is often used in high-strength electrical steel sheets because it has a relatively small adverse effect on magnetic properties and is effective in increasing strength. It is also effective in improving corrosion resistance, but the upper limit is preferably set to 2.5% in view of the cost of addition and adverse effects on magnetic properties.
[0047]
Cr is an element added for improving corrosion resistance and improving magnetic properties in a high frequency range. However, considering the cost of addition and adverse effects on magnetic properties, the upper limit is preferably set to 10.0%.
[0048]
In addition, the effects of the present invention are not impaired at all even if other trace elements are added for various purposes in addition to the amounts inevitably contained in ores and scraps. The unavoidable content of these trace elements is usually about 0.005% or less for each element, but can be added to about 0.01% or more for various purposes. In this case, too, one or more of Mo, W, Sn, Sb, Mg, Ca, Ce, and Co can be contained in a total amount of 0.5% or less from the viewpoint of cost and magnetic properties.
[0049]
The steel containing the above components is melted in a converter like a normal electromagnetic steel sheet, turned into a slab by continuous casting, and then manufactured by processes such as hot rolling, hot-rolled sheet annealing, cold rolling, and finish annealing. You. In addition to these steps, the formation of an insulating film and the decarburization step do not impair the effects of the present invention. In addition, there is no problem in manufacturing a thin strip by a rapid solidification method, a thin slab which omits a hot rolling step, a continuous casting method, or the like instead of a normal step.
[0050]
In order to form a unique metal phase characteristic of the present invention in a steel sheet, it is important to go through the following heat history. That is, in the process of manufacturing the product plate, the temperature is maintained at 450 ° C. to 720 ° C. for 30 seconds or more. Further, it is preferable to go through a step of not maintaining the temperature in a temperature range exceeding 800 ° C. for 20 seconds or more.
[0051]
Through the above-described steps, a Cu metal phase characteristic of components, sizes and number densities is efficiently formed, and high strength can be achieved without substantially impairing magnetic properties. On the other hand, under normal heat treatment conditions that are not aware of the formation of such a metal phase, most of the added Cu is present as solid solution Cu or Cu sulfide having a low strengthening ability and a large magnetic property deterioration effect.
[0052]
From the viewpoint of productivity, this heat treatment step is performed after the rolling step, and at the same time as heat treatment required for other purposes such as recrystallization annealing, since the steel material becomes stronger after this heat treatment step. Is advantageous. That is, in the case of a cold-rolled magnetic steel sheet, the final heat treatment step after cold rolling is performed. It is preferable to maintain the temperature in the temperature range of 30 ° C. for 30 seconds or more.
[0053]
Further, heat treatment may be further applied depending on the intended characteristics. In such a case, it is preferable not to keep the temperature in a temperature range exceeding 800 ° C. for 20 seconds or more. If the heat treatment is performed such that the temperature or the time exceeds this, the formed Cu metal phase may be re-dissolved or may be terminated and become a coarse metal phase.
[0054]
Since the present invention does not utilize the strengthening due to the refinement of the crystal structure, the steel plate is punched out, and the strain introduced into the material when processing into a motor part is recovered, and the recovery and improvement of the magnetism is achieved by growing the crystal grains. Even if SRA (strain relief annealing) is performed for the purpose, deterioration in strength is small.
[0055]
Further, in order to form a unique metal phase, which is a feature of the present invention, in a steel sheet after an electromagnetic steel sheet is processed into an electrical component, it is important to pass through the following heat history. It is to control the holding time in the temperature range of 450 ° C. to 700 ° C. and the subsequent heat history in the process of manufacturing a product plate and the heat treatment process after processing into an electric component.
[0056]
That is, as a final processing step, heat treatment mainly applied to the steel sheet until punching and assembling for using the electromagnetic steel sheet as an electrical component, heat history and cold history after finish rolling during hot rolling and before cold rolling. For each heat history in the annealing process after the elongation, the residence time in the temperature range of 450 ° C. to 700 ° C. in the cooling process from the temperature range of 750 ° C. or more is set to 300 seconds or 60 seconds or less, and then 750 ° C. It is preferable not to keep the temperature in a range exceeding the temperature.
[0057]
Hardening is performed after punching and assembling the electromagnetic steel sheet as an electrical component, which is a final processing step for the electromagnetic steel sheet, and is performed in a temperature range of 450 ° C. to 700 ° C. for 30 seconds or more. Thereafter, heat treatment is performed so as not to maintain the temperature in a temperature range exceeding 700 ° C. When this heat treatment is performed in the cooling process following the heat treatment at a higher temperature, the average cooling rate in the cooling process up to 700 ° C. before holding in the temperature range of 450 ° C. to 700 ° C. is 10 ° C./sec or more. Preferably, the average cooling rate in the cooling process to 650 ° C. before holding in the temperature range of 500 ° C. to 650 ° C. is 10 ° C./sec or more. This heat treatment is preferably performed in a cooling process of a so-called strain relief annealing process performed for the purpose of removing unintended strain introduced into the material at the time of processing, from the viewpoint of productivity, and is performed at 450 ° C. to 700 ° C. The maximum attainment temperature of 700 ° C. or more before holding in the temperature range and the holding time in that temperature range can be determined only from the viewpoint of strain removal and crystal grain growth, and have no influence on the effects of the present invention. It does not affect.
[0058]
Through this step, a metal phase characteristic of components, sizes and number densities is efficiently formed in a preferable step, and hardening can be achieved without substantially impairing magnetic properties. The steel of the present invention is intended for steel whose tensile strength is increased by 30 MPa or more or hardness is increased by 1.1 times or more by heat treatment for hardening. If the strength or hardness is less than this, it is considered that the material has already been hardened before the heat treatment or has no strengthening ability by the heat treatment. If the hardened material is already hardened before the heat treatment, punching of the motor component is performed on a hard material, which is not preferable in terms of mold wear. In addition, if the steel does not harden even after the heat treatment, the strength during the subsequent use of the motor will be insufficient, and the object of the present invention will not be achieved. In order to obtain more preferable effects, the tensile strength is increased to 60 MPa or more by heat treatment, the hardness is increased to 1.2 times or more, more preferably the tensile strength is increased to 100 MPa or more, and the hardness is increased to 1.3 times or more.
[0059]
On the other hand, under normal heat treatment conditions that are not aware of the formation of the metal phase controlled by the present invention, depending on the steel composition, the formation of a metal phase that can detect the effect may occur, but most of the added Cu It exists as solid solution Cu or Cu sulfide or a coarse metal phase having a diameter of 0.2 μm or more, which has a low strengthening ability and a large effect of deteriorating magnetic properties.
[0060]
The metal phase formed as described above mainly consists of Cu. This can be identified by a diffraction pattern such as an electron microscope or an attached X-ray analyzer. Of course, identification can be performed by other methods such as chemical analysis. In the present invention, the diameter of the metal phase mainly composed of Cu is 1.0 μm or less. Above this level, the efficiency of increasing the strength is significantly reduced, and a large amount of metal phase is required, so that the adverse effect on magnetic properties is increased. From the viewpoints of high strength efficiency and magnetic properties, the diameter is preferably 0.50 μm or less, and more preferably 0.20 μm or less. However, if the diameter is too small, the adverse effect on the magnetic properties increases. It is preferably at least 0.01 μm, more preferably at least 0.05 μm.
[0061]
The number density of the Cu metal phase is limited to a range that can be taken depending on the relationship between the Cu content and the size of the metal phase. ³ More preferably, the number is more preferably 1.0 pieces / μm. ³ Above, 5.0 pieces / μm ³ This is very effective in increasing the strength. These diameters and number densities can be quantified, for example, by observation with an electron microscope.
[0062]
The control of the metal phase size and the number density is very important from the viewpoint of achieving both high strength and retention of magnetic properties. The reason for this is that not only do they affect the strength and the magnetic properties, but also when they are changed, the behavior in which the strength or the magnetic properties change is different. That is, it is necessary to control the region to have a high strength increasing effect and a low magnetic characteristic deterioration efficiency. For this purpose, it is effective to appropriately control the temperature and time in the above-mentioned temperature range of 450 to 650 ° C. and the cooling rate immediately before entering this temperature range. Similar to the formation of precipitates, the higher the cooling rate and the lower the temperature, the finer and denser the metal phase size becomes, and the longer the length, the larger the size becomes.
[0063]
Further, in the present invention, since the refinement of the crystal structure is not used as a main means for increasing the strength, the crystal grain size can be adjusted to an optimum range from the viewpoint of magnetic properties. The size and density of the metal phase mainly composed of Cu contributing to the increase in strength can be controlled not only by the components but also mainly by the above-mentioned heat treatment at 600 ° C. or lower. The strength can be controlled independently of the strength by the maximum attained temperature of the crystal annealing and the holding time in the temperature range. Usually, it is controlled to 30 to 300 μm by heat treatment at about 800 to 1100 ° C. for about 20 seconds to 5 minutes. More preferably, it is 80 to 200 μm.
[0064]
The present invention has characteristics completely different from those of materials conventionally developed for magnetic steel sheets. 1 and 2 show the characteristics of the present invention in terms of components, strength and magnetic properties of an electromagnetic steel sheet. As shown in FIG. 1, the magnetic properties of an electromagnetic steel sheet are usually determined mainly by the Si content. From the viewpoint of magnetic properties, Si is added to increase the electric resistance of the material and reduce iron loss, but at the same time, has high solid solution strengthening ability, so that high grade materials having high Si have high strength. . However, if the amount of Si exceeds 3% or the total amount of reinforcing elements such as Si, Al, and Mn exceeds 6%, the rollability is significantly deteriorated. Become.
[0065]
As a means of avoiding rolling, a method of obtaining a thin film directly from steel in a molten state by rapid solidification has been devised, but there is a limit to practical use in terms of cost and characteristics. For this reason, a high-strength material equivalent to or more than 3% Si steel achieves high strength by refinement of a crystal structure including precipitation mainly composed of carbonitride accompanying addition of Nb or the like and low-temperature annealing. However, such carbonitrides and fine crystal structures are not preferable from the viewpoint of magnetic properties, particularly iron loss, and a significant increase in iron loss as shown in FIG. 2 cannot be avoided.
[0066]
The present invention achieves high strength by dispersing a metal phase different from that of conventional high-strength steel in a steel sheet. Since this metal phase can be controlled independently of the crystal grain size, in other words, the formation can be controlled at a lower temperature range of about 600 ° C., which is different from the temperature range of 750 ° C. or higher where crystal grain growth usually occurs. Therefore, the degree of freedom from the viewpoint of controlling the strength and the magnetic characteristics is large, and the strength can be increased without significantly deteriorating the magnetic characteristics as shown in FIG.
[0067]
Further, by applying the present technology to low Si steel as shown in FIG. 1, it is possible to obtain a material having a higher magnetic flux density than conventional steel. This is because most of the commonly used solid solution strengthening elements such as Si, Al, and Mn decrease the saturation magnetic flux density of steel, so that the magnetic flux density at a specific magnetic field cannot be reduced. It is considered that the Cu metal phase used for increasing the strength in the invention has a very small effect on lowering the saturation magnetic flux density. It is also considered that the Cu metal phase is less likely to hinder domain wall movement than precipitates such as carbonitrides. This is particularly effective for improving magnetic properties in a low magnetic field.
[0068]
The effects of the present invention can be applied to non-oriented or oriented magnetic steel sheets, since they usually do not depend on the presence or absence and type of surface film formed on the surface of the magnetic steel sheets and do not depend on the manufacturing process.
[0069]
The use is not particularly limited, and is applied to all uses requiring strength and magnetic properties, in addition to rotor use for motors used in home appliances or automobiles.
[0070]
【Example】
(Example 1)
A steel plate whose components are shown in Table 1 was made into a slab having a thickness of 250 mm, and a product plate was manufactured based on the following steps. The basic process conditions are as follows: slab heating temperature: 1100 ° C., finish plate thickness: 2.0 mm, winding temperature: 500 ° C., hot rolling process, finish plate thickness: 0.5 mm, cold rolling process, recrystallization temperature or higher. This is a recrystallization annealing step. For some of them, a metal phase precipitation step by holding at about 500 ° C. was provided on the way. The mechanical properties of the product plate were determined by JIS No. 5 test piece, and the iron loss W was determined by 55 mm square SST test. _10/400 And magnetic flux density B ₁₀ Was measured. The average value of the mechanical properties and the magnetic properties in the rolling direction of the coil and the direction perpendicular thereto was determined. The results are shown in Table 2 (continued from Table 1).
[0071]
As is clear from the results shown in Table 2, the samples manufactured under the conditions of the present invention have good rollability in the cold rolling step, are hard, and have excellent magnetic properties.
[0072]
[Table 1]

[0073]
[Table 2]

[0074]
(Example 2)
A steel plate whose components are shown in Table 3 was made into a slab having a thickness of 250 mm, and a product plate was manufactured based on the following steps. The basic process conditions are as follows: slab heating temperature: 1100 ° C., finished plate thickness: 2.0 mm, winding temperature: hot rolling process at 700 ° C., hot rolling plate annealing process at 980 ° C. for 30 seconds, finished plate thickness: 0 2 mm cold rolling step and recrystallization annealing step at a recrystallization temperature or higher. For some of them, a metal phase precipitation step by holding at about 500 ° C. was provided on the way. Regarding the product plate, mechanical properties were determined by JIS No. 5 test piece, and iron loss W was determined by 55 mm square SST test. _15/50 And magnetic flux density B ₅₀ Was measured. The average value of the mechanical properties and the magnetic properties in the rolling direction of the coil and the direction perpendicular thereto was determined. The results are shown in Table 4 (continued from Table 3).
[0075]
As is clear from the results shown in Table 4, the samples manufactured under the conditions of the present invention have good rollability in the cold rolling step, are hard, and have excellent magnetic properties.
[0076]
[Table 3]

[0077]
[Table 4]

[0078]
(Example 3)
A steel plate whose components are shown in Table 5 was made into a slab having a thickness of 250 mm, and a product plate was manufactured based on the following steps. The basic process conditions are a slab heating temperature of 1100 ° C., a finish plate thickness of 2.0 mm, a hot rolling step at a winding temperature of 300 ° C. or less, a cold rolling step of a finish plate thickness of 0.2 mm, and a recrystallization annealing at a recrystallization temperature or higher. It is a process. After that, as a simulation of the precipitation heat treatment after the punching, the structure adjustment and the metal phase precipitation control by the heat treatment at around 750 ° C. were performed. When the strain relief annealing was also performed, the precipitation heat treatment was performed in the cooling process after the heat treatment at 750 ° C. for 2 hours. The mechanical properties of the plates before and after the heat treatment were measured by JIS No. 5 test pieces, and the iron loss W10 / 400 and the magnetic flux density B10 were measured by a 55 mm square SST test. The average value of the mechanical properties and the magnetic properties in the rolling direction of the coil and the direction perpendicular thereto was determined. The wear of the punching die was evaluated by punching a steel plate with a newly manufactured punching die and the change in the size of burrs generated on the steel plate according to the number of times of punching. In the case of a mold having large wear, the burrs of the steel sheet increase with a relatively small number of times of punching. The results are shown in Table 6 (continued from Table 5).
[0079]
As is clear from the results shown in Table 6, the sample produced under the conditions of the present invention was soft before the heat treatment for precipitation, so that the rollability in the cold rolling process was good and the abrasion of the punching die was small. It becomes hard after the treatment and has excellent magnetic properties.
[0080]
[Table 5]

[0081]
[Table 6]

[0082]
(Example 4)
A steel plate whose components are shown in Table 7 was made into a slab having a thickness of 250 mm, and a product plate was manufactured based on the following steps. The basic process conditions are a slab heating temperature of 1100 ° C., a finished plate thickness of 2.0 mm, a hot rolling process at a winding temperature of 300 ° C. or less, a hot rolled sheet annealing process of 980 ° C. × 30 seconds, and a cold rolling process of a finished plate thickness of 0.35 mm. A rolling step and a recrystallization annealing step at a recrystallization temperature or higher. After that, as a simulation of the precipitation heat treatment after the punching, the structure adjustment and the metal phase precipitation control by the heat treatment at around 750 ° C. were performed. When the strain relief annealing was also performed, the precipitation heat treatment was performed in the cooling process after the heat treatment at 750 ° C. for 2 hours. The mechanical properties of the plates before and after the heat treatment were measured by JIS No. 5 test pieces, and the iron loss W15 / 50 and the magnetic flux density B50 were measured by a 55 mm square SST test. The average value of the mechanical properties and the magnetic properties in the rolling direction of the coil and the direction perpendicular thereto was determined. The wear of the punching die was evaluated by punching a steel plate with a newly manufactured punching die and the change in the size of burrs generated on the steel plate according to the number of times of punching. In the case of a mold having large wear, the burrs of the steel sheet increase with a relatively small number of times of punching. The results are shown in Table 8 (continued from Table 7).
[0083]
As is clear from the results shown in Table 8, the sample manufactured under the conditions of the present invention was soft before the heat treatment for precipitation, so that the rollability in the cold rolling process was good and the abrasion of the punching die was small. It becomes hard after the treatment and has excellent magnetic properties.
[0084]
[Table 7]

[0085]
[Table 8]

[0086]
【The invention's effect】
As described above, the present invention can stably produce a high-strength electrical steel sheet that is hard and has excellent magnetic properties. This makes it possible to ensure strength, fatigue strength, and abrasion resistance without deteriorating magnetic properties, so that ultra-high-speed rotating motors, motors with built-in magnets in rotors, and materials for electromagnetic switches with higher efficiency, smaller size, Long life is achieved.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing the relationship between the Si content and the tensile strength of the steel sheet of the present invention.
FIG. 2 is a conceptual diagram showing the relationship between tensile strength and iron loss of the steel sheet of the present invention.

Claims

In mass%, C: 0.0040% or less, Si: 0.2 to 3.5%, Mn: 0.05 to 3.0%, P: 0.30% or less, S: 0.0040% or less, Al: 2.50% or less, Cu: 0.6 to 8.0%, N: 0.0040% or less, the balance being Fe and unavoidable impurities, and having a diameter of 1.0 μm or less inside the steel material. An electromagnetic steel sheet having a remarkably excellent magnetic property, characterized by containing a metal phase composed of Cu.

In mass%, one or two of Nb: 0.02% or less, Ti: 0.010% or less, B: 0.010% or less, Ni: 2.5% or less, Cr: 10.0% or less. 2. The electrical steel sheet according to claim 1, wherein the electrical steel sheet contains at least one species.

3. The method according to claim 1, wherein one or more of Mo, W, Sn, Sb, Mg, Ca, Ce, and Co are contained in a total of 0.5% or less by mass%. 4. Electrical steel sheet with remarkably excellent magnetic properties.

The electrical steel sheet according to any one of claims 1 to 3, wherein the number density of the metal phase made of Cu present in the steel material is 0.2 / μm ³ or more.

The magnetic steel sheet according to any one of claims 1 to 4, wherein the steel sheet has an average diameter of crystal grains of 30 to 300 µm.

4. A magnetic property characterized by performing a heat treatment of maintaining the steel sheet made of the component according to claim 1 in a temperature range of 450 ° C. to 720 ° C. for 30 seconds or more. Method of manufacturing electrical steel sheet with remarkably excellent performance.

The electromagnetic treatment according to claim 6, wherein the heat treatment is performed by cooling at a temperature range of 450 ° C. to 720 ° C. for 30 seconds or more in a cooling process from a temperature range of 750 ° C. or more in a final heat treatment step. Steel plate manufacturing method.

A method for producing a magnetic steel sheet having extremely excellent magnetic properties, wherein the heat treatment is not carried out in a temperature range exceeding 800 ° C. for 20 seconds or more after the heat treatment according to claim 6 or 7.

The number density of the metal phase mainly consisting of Cu which exists in the said steel material after heat treatment after hardening by heat treatment after processing into an electric component is 0.2 pieces / micrometer ³ or more, any one of Claims 1-3 characterized by the above-mentioned. An electrical steel sheet having remarkably excellent magnetic properties according to any of the above items.

The average diameter of a metal phase mainly composed of Cu existing inside the steel material after heat treatment for hardening by heat treatment after processing the electric component is 0.20 μm or less, wherein the average diameter is 0.20 μm or less. An electrical steel sheet having remarkably excellent magnetic properties described in 1.

11. The magnetic component according to claim 1, wherein an average diameter of crystal grains after heat treatment for hardening by heat treatment after processing the electric component is 30 to 300 [mu] m. Electrical steel sheet.

10. The number density of a metal phase mainly composed of Cu having a diameter of 0.10 [mu] m or less inside a steel material increases by 10 times or more before and after hardening heat treatment by heat treatment after processing into an electric component. The magnetic steel sheet according to any one of Items 1 to 11, which is excellent in magnetic properties.

The magnetic steel sheet according to any one of claims 1 to 3, wherein the tensile strength is increased by 30 MPa or more by heat treatment after hardening by heat treatment after processing the electric part.

The magnetic property according to any one of claims 1 to 3, 9 to 13, wherein the hardness of the steel material is increased by 1.1 times or more by the heat treatment for hardening due to the heat treatment after processing the electric component. Excellent electrical steel sheet.

In a process of manufacturing a product sheet from a steel material comprising the component according to any one of claims 1 to 3, a hot rolling process before cold rolling is performed in a cooling process from a temperature range of 750 ° C or more after finish rolling in a hot rolling process. It is characterized in that the residence time in a temperature range of from 700 ° C. to 700 ° C. is 300 seconds or less, and thereafter, it is hardened by heat treatment after processing into an electric component by cold rolling without maintaining the temperature in a range exceeding 750 ° C. A method for manufacturing electrical steel sheets with remarkably excellent magnetic properties.

In the final heat treatment step after hot rolling and cold rolling, the temperature is kept at 750 ° C. or more for 20 seconds or more, and then, in the cooling process from the temperature range of 750 ° C. or more, the residence time in the temperature range of 450 ° C. to 700 ° C. is 60 seconds or less. 16. The method for producing an electrical steel sheet according to claim 15, wherein the electrical component is hardened by heat treatment after processing by not maintaining the temperature in a temperature range exceeding 750 ° C. thereafter.

The electrical steel sheet according to any one of claims 1 to 3, 9 to 14, or the electrical steel sheet manufactured by the method according to any one of claims 15 and 16 for 30 seconds in a temperature range of 450 ° C to 700 ° C. An electromagnetic component having a remarkably excellent magnetic property, characterized in that the electrical component is hardened by heat treatment after processing into an electrical component by performing a process of maintaining the above, and thereafter not maintaining the temperature in a temperature range exceeding 700 ° C. for 20 seconds or more. Steel plate manufacturing method.

As the heat treatment method, the average cooling rate in the cooling process from the heat treatment temperature to 700 ° C. in the heat treatment after the processing of the steel sheet into the electric component is set to 10 ° C./sec or more, and maintained for 30 seconds or more in a temperature range of 450 ° C. to 700 ° C. 18. The magnetic property according to claim 17, wherein the electric component is hardened by a heat treatment after processing into an electric component by passing through a step of not maintaining the temperature in a temperature range exceeding 700 ° C. for 20 seconds or more. Excellent manufacturing method of electrical steel sheet.