JP2004225060A

JP2004225060A - Copper alloy and method for producing the same

Info

Publication number: JP2004225060A
Application number: JP2002374080A
Authority: JP
Inventors: Irin Ko; 維林高; Akira Sugawara; 章菅原
Original assignee: Dowa Mining Co Ltd
Current assignee: Dowa Holdings Co Ltd
Priority date: 2002-11-25
Filing date: 2002-12-25
Publication date: 2004-08-12
Anticipated expiration: 2022-12-25
Also published as: JP4787986B2

Abstract

【課題】コネクタなどの電気電子部品用材料に要求される諸特性を兼備した銅合金、すなわち強度、導電性、耐応力緩和特性、ヤング率、プレス成形性、熱間加工性およびコストに優れた銅合金およびその製造方法を提供する。
【解決手段】２０〜４６重量％のＺｎと０．１〜５．０重量％のＳｎと０．００１〜０．５重量％のＢとを含有し、残部がＣｕおよび不可避的不純物からなる銅合金材料に粒径５μｍ以下のＢ酸化物を含有させることによって、鋳造結晶粒微細化と動的再結晶促進効果による熱間加工性に優れ、また、展伸方向の０．２％耐力が６００Ｎ／ｍｍ^２以上、引張強さが６５０Ｎ／ｍｍ^２以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、導電率が２０％ＩＡＣＳ以上、応力緩和率が２０％以下であり、展伸方向に対して直角方向の０．２％耐力が６５０Ｎ／ｍｍ^２以上、引張強さが７００Ｎ／ｍｍ^２以上、ヤング率が１３０ｋＮ／ｍｍ^２以下であるコネクタ用銅合金を得る。
【選択図】なしAn object of the present invention is to provide a copper alloy having various characteristics required for materials for electric and electronic parts such as connectors, that is, excellent in strength, conductivity, stress relaxation resistance, Young's modulus, press formability, hot workability and cost. A copper alloy and a method for producing the same are provided.
A copper containing 20 to 46% by weight of Zn, 0.1 to 5.0% by weight of Sn, and 0.001 to 0.5% by weight of B, with the balance being Cu and unavoidable impurities By containing a B oxide having a particle size of 5 μm or less in the alloy material, it is excellent in hot workability due to the effect of refining cast grains and promoting dynamic recrystallization, and has a 0.2% proof stress of 600 N in the elongation direction. / Mm ² or more, tensile strength of 650 N / mm ² or more, Young's modulus of 120 kN / mm ² or less, conductivity of 20% IACS or more, and stress relaxation rate of 20% or less, in a direction perpendicular to the stretching direction. 0.2% proof stress 650 N / mm ² or more, tensile strength of 700 N / mm ² or more, a Young's modulus to obtain a connector for copper alloy is 130 kN / mm ² or less.
[Selection diagram] None

Description

【０００１】
【発明の属する技術分野】
本発明は、コネクタなどの電気電子部品用材料として好適な強度、導電性、耐応力緩和特性などを有し、さらに熱間加工性やコストに優れた銅合金およびその製造方法に関する。
【０００２】
【従来の技術】
近年のエレクトロニクスの発達により、種々の機械の電気配線の複雑化や高集積化が進み、それに伴ってコネクタなどの電気電子部品用の伸銅品材料の使用量が増加している。また、コネクタなどの電気電子部品では、軽量化、高信頼性化および低コスト化が要求されている。これらの要求を満たすために、コネクタ用銅合金材料は、薄肉化され、また、複雑な形状にプレスされるので、強度、弾性、導電性およびプレス成形性が良好でなければならない。
【０００３】
具体的には、コネクタ用銅合金材料では、端子の挿抜や曲げに対して座屈や変形しない強度、電線の加締めや嵌合保持に対する強度として、０．２％耐力が６００Ｎ／ｍｍ^２以上、好ましくは６５０Ｎ／ｍｍ^２以上、さらに好ましくは７００Ｎ／ｍｍ^２以上であり、引張強さが６５０Ｎ／ｍｍ^２以上、好ましくは７００Ｎ／ｍｍ^２以上、さらに好ましくは７５０Ｎ／ｍｍ^２以上であることが要求されている。また、端子をプレスする際に、連鎖方向の関係から、圧延などにおける展伸方向に対して直角方向の強度が所定の強度であることが要求されており、この直角方向の強度として、０．２％耐力が６５０Ｎ／ｍｍ^２以上、好ましくは７００Ｎ／ｍｍ^２以上、さらに好ましくは７５０Ｎ／ｍｍ^２以上であることが要求され、引張強さが７００Ｎ／ｍｍ^２以上、好ましくは７５０Ｎ／ｍｍ^２以上、さらに好ましくは８００Ｎ／ｍｍ^２以上であることが要求されている。また、通電によるジュ−ル熱の発生を抑えるために、導電率が２０％ＩＡＣＳ以上であることが好ましい。
【０００４】
さらに、コネクタ用銅合金材料では、耐食性や耐応力腐食割れ性に優れていることが必要であり、メス端子の場合には、熱的負荷が加わるため、耐応力緩和特性にも優れていなければならない。具体的には、応力腐食割れ寿命が従来の黄銅一種の３倍以上であり、応力緩和率が１５０℃において黄銅一種の半分以下、好ましくは２５％以下、さらに好ましくは２０％以下であることが必要である。
【０００５】
従来、コネクタ材として一般に黄銅やりん青銅などが使用されていた。黄銅は低コストの材料として使用されているが、０．２％耐力および引張強さは、質別がＨ０８（ばね材用）でもそれぞれ５７０Ｎ／ｍｍ^２および６４０Ｎ／ｍｍ^２程度であり、０．２％耐力が６００Ｎ／ｍｍ^２以上で引張強さが６５０Ｎ／ｍｍ^２以上というコネクタ材としての要求を満足できない。また、黄銅は、耐食性、耐応力腐食割れ性および耐応力緩和特性にも劣っている。一方、りん青銅は、強度、耐食性、耐応力腐食割れ性および耐応力緩和特性のバランスに優れているが、例えば、ばね用りん青銅の場合、導電率が１２％ＩＡＣＳと小さく、且つ熱間加工することができず、コスト的にも不利である。
【０００６】
ここで、黄銅およびりん青銅のヤング率は、いずれも展伸方向において１１０〜１２０ｋＮ／ｍｍ^２、直角方向において１１５〜１３０ｋＮ／ｍｍ^２であり、このように小さいヤング率は、コネクタ材としての要求に合致し、最近、これらの材料が見直されている。したがって、黄銅とりん青銅の特長を兼備し、黄銅に近い価格で、展伸方向の０．２％耐力が６００Ｎ／ｍｍ^２以上、引張強さが６５０Ｎ／ｍｍ^２以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、導電率が２０％ＩＡＣＳ以上、応力緩和率が２０％以下であり、展伸方向に対して直角方向の０．２％耐力が６５０Ｎ／ｍｍ^２以上、引張強さが７００Ｎ／ｍｍ^２以上、ヤング率が１３０ｋＮ／ｍｍ^２以下である材料が望まれている。
【０００７】
また、コネクタ用の材料は、Ｓｎめっきされる機会が多くなり、合金にＳｎを含んでいる方が原料としての利用度が高まる。さらに、黄銅に代表されるように、Ｚｎを含むと、強度、加工性およびコストのバランスに優れた合金が得られ易い。このような見地から、Ｃｕ−Ｚｎ−Ｓｎ合金は注目に値する合金系である。
【０００８】
例えば、ＣＤＡ規格のＣ４２５００は、Ｃｕ−９．５Ｚｎ−２．０Ｓｎ−０．２Ｐ合金であり、コネクタ用の材料として良く知られている。また、Ｃ４３４００は、Ｃｕ−１４Ｚｎ−０．７Ｓｎ合金であり、少量ではあるがスイッチ、リレ−、端子用として使用されている。しかしながら、これよりＺｎ量が多いＣｕ−Ｚｎ−Ｓｎ合金は、コネクタ用の材料としてほとんど使用されていない。Ｚｎ量とＳｎ量が増加すると熱間加工性が低下するためである。例えば、Ｃ４２５００よりＺｎ量が多い銅合金として、Ｃ４３５００（Ｃｕ−１８Ｚｎ−０．９Ｓｎ）、Ｃ４４５００（Ｃｕ−２８Ｚｎ−１Ｓｎ−０．０５Ｐ）、Ｃ４６７００（Ｃｕ−３９Ｚｎ−０．８Ｓｎ−０．０５Ｐ）などが挙げられるが、楽器用、船舶用、雑貨品用などの用途としての板、棒、管などの製品があるだけであり、コネクタ用の展伸材料、特に条材としては利用されていない。また、これらの材料の特性についても、展伸方向の０．２％耐力が６００Ｎ／ｍｍ^２以上、引張強さが６５０Ｎ／ｍｍ^２以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、導電率が２０％ＩＡＣＳ以上、応力緩和率が２０％以下であり、展伸方向に対して直角方向の０．２％耐力が６５０Ｎ／ｍｍ^２以上、引張強さが７００Ｎ／ｍｍ^２以上、ヤング率が１３０ｋＮ／ｍｍ^２以下であり、且つプレス性や耐応力腐食割れ性などのコネクタ材に必要な特性の全てを満たすことはできない。特に、上記の諸特性を維持するためには、一定量以上のＺｎとＳｎを含有する必要がある。しかし、Ｚｎ量とＳｎ量が増加すると、熱間割れを生じ易く、歩留まりの低下によるコストアップの問題がある。
【０００９】
このような現状に鑑み、適量のＺｎとＳｎを含有させ、あるいはさらにＳｉなどを含有させ、適切な製造方法を採ることにより、優れた特性を有する銅合金を得ることが提案されている（例えば、特許文献１、特許文献２参照）。
【００１０】
【特許文献１】
特開２００１−２９４９５７号公報（段落番号００１４）
【特許文献２】
特開２００２−８８４２８号公報（段落番号００１４）
【００１１】
【発明が解決しようとする課題】
しかし、これらの従来の方法では、熱間圧延条件の制御が非常に厳しく、また、微細なひび割れによる歩留まりの低下を生じる場合があるため、熱間圧延性にも優れた銅合金を提供することが望まれている。
【００１２】
したがって、本発明は、このような従来の問題点に鑑み、エレクトロニクスの発達に伴ってコネクタなどの電気電子部品用材料に要求される上記のような諸特性を兼備した銅合金、すなわち、０．２％耐力、引張強さ、導電率、ヤング率、耐応力緩和特性、プレス性、熱間加工性およびコストに優れた銅合金およびその製造方法を提供することを目的とする。
【００１３】
【課題を解決するための手段】
本発明者らは、上記課題を解決するために鋭意研究した結果、２０〜４６重量％のＺｎと、０．１〜５．０重量％のＳｎと、０．００１〜０．５重量％のＢとを含有し、残部がＣｕおよび不可避的不純物からなる銅合金材料に、粒径５μｍ以下のＢ酸化物を含有させることによって、鋳造結晶粒微細化と動的再結晶促進効果による熱間加工性に優れ、展伸方向の０．２％耐力が６００Ｎ／ｍｍ^２以上、引張強さが６５０Ｎ／ｍｍ^２以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、導電率が２０％ＩＡＣＳ以上、応力緩和率が２０％以下であり、展伸方向に対して直角方向の０．２％耐力が６５０Ｎ／ｍｍ^２以上、引張強さが７００Ｎ／ｍｍ^２以上、ヤング率が１３０ｋＮ／ｍｍ^２以下である銅合金を得ることができることを見出し、本発明を完成するに至った。
【００１４】
すなわち、本発明による銅合金は、２０〜４６重量％のＺｎと、０．１〜５．０重量％のＳｎと、０．００１〜０．５重量％のＢとを含有し、残部がＣｕおよび不可避的不純物からなり、粒径５μｍ以下のＢ酸化物を含有することまたはＢ酸化物を含有し且つＢ酸化物の粒径が５μｍ以下であることを特徴とする。
【００１５】
この銅合金において、粒径１μｍ未満のＢ酸化物を含有し且つ粒径１〜５μｍのＢ酸化物を含有するのが好ましい。また、展伸方向の０．２％耐力が６００Ｎ／ｍｍ^２以上、引張強さが６５０Ｎ／ｍｍ^２以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、導電率が２０％ＩＡＣＳ以上、応力緩和率が２０％以下であり、展伸方向に対して直角方向の０．２％耐力が６５０Ｎ／ｍｍ^２以上、引張強さが７００Ｎ／ｍｍ^２以上、ヤング率が１３０ｋＮ／ｍｍ^２以下であるのが好ましい。また、この銅合金が、さらに０．０１〜３重量％のＦｅと、０．０１〜５重量％のＮｉと、０．０１〜３重量％のＣｏと、０．０１〜３重量％のＴｉと、０．０１〜２重量％のＭｇと、０．０１〜２重量％のＺｒと、０．０１〜１重量％のＣａと、０．０１〜３重量％のＳｉと、０．０１〜１０重量％のＭｎと、０．０１〜３重量％のＣｄと、０．０１〜５重量％のＡｌと、０．０１〜３重量％のＰｂと、０．０１〜３重量％のＢｉと、０．０１〜３重量％のＢｅと、０．０１〜１重量％のＴｅと、０．０１〜３重量％のＹと、０．０１〜３重量％のＬａと、０．０１〜３重量％のＣｒと、０．０１〜３重量％のＣｅと、０．０１〜１重量％のＶと、０．０１〜１重量％のＢａと、０．０１〜５重量％のＡｕと、０．０１〜５重量％のＡｇと、０．００５〜０．５重量％のＰのうち少なくとも１種以上の元素を、その総量が０．０１〜５重量％になるように含んでもよい。
【００１６】
また、本発明による銅合金の製造方法は、２０〜４６重量％のＺｎと、０．１〜５．０重量％のＳｎと、０．００１〜０．５重量％のＢとを含有し、残部がＣｕおよび不可避的不純物からなる銅合金の製造方法において、銅合金の原料を溶解し、液相線温度から６００℃までの温度域において５０℃／分以上の冷却速度で冷却して鋳塊を得た後、９００℃以下の温度で熱間圧延を行い、次いで冷間圧延と３００〜６５０℃の温度域における焼鈍を繰り返すことによって焼鈍後の結晶粒径を２５μｍ以下にし、次いで３０％以上の加工率の冷間圧延と４５０℃以下の低温焼鈍を行うことを特徴とする。
【００１７】
この銅合金の製造方法において、熱間圧延に際して、１パス目の熱間圧延における圧下率を５〜３０％とし、次のパスの熱間圧延における圧下率を５〜４０％とし、最終パス目の熱間圧延における圧下率を２５％以上とするのが好ましく、１パス目の熱間圧延における圧下率を１０〜２０％とするのがさらに好ましい。また、焼鈍後の結晶粒径を１５μｍ以下とするのが好ましく、３０％以上の加工率の冷間圧延の加工率を６０％以上とするのが好ましい。また、銅合金が、粒径５μｍ以下のＢ酸化物を含有するのが好ましく、展伸方向の０．２％耐力が６００Ｎ／ｍｍ^２以上、引張強さが６５０Ｎ／ｍｍ^２以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、導電率が２０％ＩＡＣＳ以上、応力緩和率が２０％以下であり、展伸方向に対して直角方向の０．２％耐力が６５０Ｎ／ｍｍ^２以上、引張強さが７００Ｎ／ｍｍ^２以上、ヤング率が１３０ｋＮ／ｍｍ^２以下であるのが好ましい。
【００１８】
この銅合金の製造方法によれば、銅より安価な成分を添加することにより低コスト化を図りつつ、コネクタなどの電気電子部品用材料に要求される諸特性を兼備した銅合金、すなわち、０．２％耐力、引張強さ、導電率、ヤング率、耐応力緩和特性、プレス性、熱間加工性およびコストなどに優れたコネクタ用銅合金を提供することができる。
【００１９】
【発明の実施の形態】
本発明による銅合金の実施の形態は、２０〜４６重量％のＺｎと、０．１〜５．０重量％のＳｎと、０．００１〜０．５重量％のＢとを含有し、残部がＣｕおよび不可避的不純物からなり、粒径５μｍ以下のＢ酸化物を含有することを特徴とする。このように銅合金の成分の量の限定した理由は以下の通りである。
【００２０】
銅合金にＺｎを添加すると、銅合金の強度やばね性が向上し、また、ＺｎはＣｕより安価であるため、Ｚｎを多量に添加することが望ましい。しかし、Ｚｎ量が４６重量％を超えると、Ｓｎとの共存下で粒界偏析が激しくなり、銅合金の熱間加工性が著しく低下する。また、銅合金の冷間加工性、耐食性および耐応力腐食割れ性も低下する。さらに、湿気や加熱によるめっき性やはんだ付け性も低下する。一方、Ｚｎ量が２０重量％より少ないと、銅合金の０．２％耐力や引張強さなどの強度やばね性が不足し、ヤング率が大きくなり、さらに、Ｓｎを表面処理したスクラップを原料とする場合には、銅合金の溶解時の水素ガス吸蔵が多くなり、インゴットのブロ−ホ−ルが発生し易くなる。また、安価なＺｎの量が少なく、経済的にも不利になる。したがって、Ｚｎ量は、好ましくは２０〜４６重量％の範囲、さらに好ましくは２４〜３７重量％の範囲である。
【００２１】
Ｓｎは、微量でも銅合金のヤング率を大きくすることなく０．２％耐力や引張強さなどの強度や弾性などの機械的特性を向上させる効果を有する。また、ＳｎめっきなどのＳｎで表面処理した材料の再利用の点からも、銅合金が添加元素としてＳｎを含有するのが好ましい。しかし、Ｓｎ含有量が増加すると、銅合金の導電率が急激に低下し、また、Ｚｎとの共存下で粒界偏析が激しくなり、熱間加工性が著しく低下する。熱間加工性を確保するためには、Ｓｎ含有量は５．０重量％を超えない範囲でなければならない。一方、Ｓｎ含有量が０．１重量％より少ないと、銅合金の機械的特性の向上の効果が少なく、また、Ｓｎめっきなどを施したプレスくずなどを原料として利用し難くなる。したがって、Ｓｎ含有量は、好ましくは０．１〜５．０重量％の範囲、さらに好ましくは０．５〜１．８重量％の範囲である。
【００２２】
Ｂは、本発明による銅合金の主成分であるＣｕ、ＺｎおよびＳｎよりも酸素との親和力が大きいため、Ｃｕ、ＺｎおよびＳｎの酸化防止効果を有する。
【００２３】
また、Ｂは、ＣａやＭｇなどの強脱酸剤ではなく、添加過程中のロスが少なく、生成される酸化物がクラスタ化し難い。
【００２４】
さらに、Ｂは、溶湯または凝固過程で酸素と反応させることができ、粒径が数十ｎｍから数μｍの粒状酸化物を得ることができる。この酸化物は、結晶粒の核として鋳造結晶粒を微細化し、また、粒成長を阻止する効果を有する。特に、約１〜５μｍの粒状酸化物が動的再結晶を促進して、さらに１μｍ以下の酸化物が再結晶粒成長を阻止することより、動的再結晶による熱間加工性の向上と再結晶粒微細化とを両立させることができる。これらの相乗効果により、熱間加工性を大幅に向上させることができる。Ｂ酸化物の粒径が５μｍより大きい場合には、圧延中に粒子付近の応力集中によって割れが発生し易くなる。一方、粒径が１μｍ未満のＢ酸化物は、動的再結晶の発生と再結晶粒成長の両方を抑制する効果を有し、約１〜５μｍの粒状酸化物は、動的再結晶の発生を促進する効果を有する。したがって、動的再結晶の発生を促進すると同時に再結晶粒成長を抑制するためには、粒径５μｍ以下の（すなわち、最大粒径が５μｍで微細粒も含む）Ｂ酸化物を含有することが必要であり、粒径１μｍ未満のＢ酸化物を含有し且つ粒径１〜５μｍのＢ酸化物を含有するのが好ましい。なお、Ｂ酸化物の同定は電子プローブマイクロアナライザ（ＥＰＭＡ）によって行い、その粒径は走査電子顕微鏡（ＳＥＭ）によって確認することができる。但し、簡易的には、光学顕微鏡などによってＢ酸化物のおおよその粒径を知ることができ、参考にすることができる。
【００２５】
また、Ｂは、分散強化効果を有するので、最終製品の軟化温度および耐応力緩和特性を向上させる効果も有する。
【００２６】
Ｂの量が０．００１重量％より少ないと、上記のような熱間加工性の向上効果がなくなる。一方、Ｂの量が０．５重量％を超えると、生成される第２相のサイズが大きくなり、逆に熱間加工性を著しく低下させ、コスト面でも不利となる。したがって、Ｂの量は、好ましくは０．００１〜０．５重量％の範囲、さらに好ましくは０．００２〜０．０５重量％の範囲である。
【００２７】
また、以上のように限定された成分であれば、鋳造や熱間圧延などの高温時に粒界に析出するＳｎ酸化物の形成を抑制することができ、展伸方向の０．２％耐力が６００Ｎ／ｍｍ^２以上、引張強さが６５０Ｎ／ｍｍ^２以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、導電率が２０％ＩＡＣＳ以上、応力緩和率が２０％以下であり、展伸方向に対して直角方向の０．２％耐力が６５０Ｎ／ｍｍ^２以上、引張強さが７００Ｎ／ｍｍ^２以上、ヤング率が１３０ｋＮ／ｍｍ^２以下であり、さらにコネクタ材として必要な諸特性、具体的には、耐食性、耐応力腐食割れ性（アンモニア蒸気中での割れ寿命が黄銅一種の３倍以上）、耐応力緩和特性（１５０℃における緩和率が黄銅一種の半分以下でりん青銅並）、プレス打ち抜き性などを満足する銅合金を作成することができる。
【００２８】
さらに、銅合金が、第３添加元素として、０．０１〜３重量％のＦｅと、０．０１〜５重量％のＮｉと、０．０１〜３重量％のＣｏと、０．０１〜３重量％のＴｉと、０．０１〜２重量％のＭｇと、０．０１〜２重量％のＺｒと、０．０１〜１重量％のＣａと、０．０１〜３重量％のＳｉと、０．０１〜１０重量％のＭｎと、０．０１〜３重量％のＣｄと、０．０１〜５重量％のＡｌと、０．０１〜３重量％のＰｂと、０．０１〜３重量％のＢｉと、０．０１〜３重量％のＢｅと、０．０１〜１重量％のＴｅと、０．０１〜３重量％のＹと、０．０１〜３重量％のＬａと、０．０１〜３重量％のＣｒと、０．０１〜３重量％のＣｅと、０．０１〜１重量％のＶと、０．０１〜１重量％のＢａと、０．０１〜５重量％のＡｕと、０．０１〜５重量％のＡｇと、０．００５〜０．５重量％のＰのうち少なくとも１種以上の元素を、その総量が０．０１〜５重量％になるように含んでも良い。
【００２９】
これらの元素は、導電率、ヤング率および成形加工性を大きく損なうことなく、強度を向上させることができる。また、各元素の含有範囲からはずれると、所望の効果を得られないか、熱間加工性、冷間加工性、プレス性、導電率、ヤング率およびコスト面などにおいて不利になる。
【００３０】
次に、本発明による銅合金の製造方法の実施の形態を説明する。
【００３１】
まず最初に、本発明による銅合金の原料を溶解して鋳造する。原料を溶解するに際して、Ｂ粉末またはＣｕ−Ｂ、Ｎｉ−ＢあるいはＦｅ−Ｂなどの母合金により、Ｂを添加することができる。ただし、原料の半分程度が溶解したときにＢを投入するのが望ましい。Ｂの投入時期が早すぎると、Ｂの酸化によるロスが多い。また、雰囲気は大気雰囲気で十分であるが、不活性ガスでシ−ルした方が酸化防止の面から好ましい。ただし、還元ガス雰囲気では、高温になると水分の分解による水素の吸収や拡散によって不利になる。
【００３２】
次に、原料の溶解後、インゴットを連続鋳造によって鋳造するのが望ましい。この連続鋳造は、縦型と横型のいずれでも構わない。ただし、液相線温度から６００℃まで温度域において５０℃／分以上の冷却速度で冷却する。冷却速度が５０℃／分未満では、粒界にＳｎの偏析が生じ、Ｂ酸化粒子がクラスタ（凝集）し易く、その後の熱間加工性を悪化させ、歩留まりの低下を引き起こす。冷却速度を規定する温度域は、液相線温度から６００℃までの温度域で良い。液相線以上の温度域を規定しても効果がなく、一方、６００℃以下では、鋳造時の冷却工程の時間程度では粒界へのＳｎの過度な偏析を生じないので、冷却速度を規定する温度域は、液相線温度から６００℃までの温度域とする。
【００３３】
溶解鋳造後に熱間圧延を行う。熱間圧延の加熱温度は９００℃以下とする。９００℃を超える温度では、Ｓｎの粒界への偏析による熱間割れが生じ、歩留まりが低下する。９００℃以下の温度で１パス目の熱間圧延を行う際の圧下率を５〜３０％とする。圧下率が３０％を超えると、鋳造結晶粒界に沿って割れが発生し易い。一方、圧下率が５％未満であると、動的再結晶またはパス間の静的再結晶が発生し難く、２パス目の圧延時に熱間割れが発生する場合もある。また、圧延パス回数が多くなり、効率的ではない。２〜３パス後に動的再結晶することによって、鋳造時のミクロな偏析および鋳造組織の消失により、本発明による銅合金の組成のＺｎ量およびＳｎ量を含んでも、組織的に均質な材料を得ることができる。さらに好ましくは１パス目の圧下率を１０〜２０％とする。次のパスでは、圧下率が５〜４０％で良く、熱間割れの発生を防止し、続いて効率良く圧延することができる。さらに、最終パス目の圧下率が出来るだけ大きくなることが好ましく、具体的には圧下率２５％以上が好ましい。これにより、熱間圧延後の結晶粒径を３５μｍ以下、好ましくは１５μｍ以下に制御することができる。熱間圧延後の結晶粒径が３５μｍを越えると、その後の冷間加工率や焼鈍条件の管理幅が狭く、少しでも逸脱すると、結晶粒が混粒になり易く、特性が劣化する。
【００３４】
熱間圧延後に必要に応じて表面を面削する。その後、冷間圧延と３００〜６５０℃の温度域における焼鈍を繰り返し、焼鈍後の結晶粒径を２５μｍ以下とする。３００℃未満の温度では、結晶粒の制御に要する時間が長くなって不経済であり、６５０℃を越えると、短時間で結晶粒が粗大化する。焼鈍後の結晶粒径が２５μｍを越えると、０．２％耐力などの機械特性や加工性が低下する。焼鈍後の結晶粒径は、好ましくは１５μｍ以下、さらに好ましくは１０μｍ以下である。
【００３５】
このようにして得られた焼鈍材を、３０％以上の加工率による冷間圧延と４５０℃以下の低温焼鈍によって、展伸方向の０．２％耐力が６００Ｎ／ｍｍ^２以上、引張強さが６５０Ｎ／ｍｍ^２以上、ヤング率が１２０ｋＮ／ｍｍ^２以下、導電率が２０％ＩＡＣＳ以上、応力緩和率が２０％以下であり、展伸方向に対して直角方向の０．２％耐力が６５０Ｎ／ｍｍ^２以上、引張強さが７００Ｎ／ｍｍ^２以上、ヤング率が１３０ｋＮ／ｍｍ^２以下である銅合金とする。冷間加工率が３０％未満では、加工硬化による強度の向上が不十分であり、機械特性の向上が不十分である。さらに好ましくは６０％以上の加工率とする。低温焼鈍は、０．２％耐力、引張強さ、ばね限界値および耐応力緩和特性をさらに向上させるために必要である。４５０℃を越える温度では、与える熱容量が大き過ぎて短時間で軟化し、また、バッチ式と連続式のいずれの場合でもワ−ク内における特性ばらつきが発生し易くなる。したがって、低温焼鈍の温度条件を４５０℃以下とする。
【００３６】
このようにして得られた材料を端子にプレスした後に、１００〜２８０℃の温度で１〜１８０分間熱処理しても良い。この熱処理によって、プレス加工によって低下したばね限界値や耐応力緩和特性が改善され、さらに、ウイスカ対策を実現することができる。１００℃未満の温度では、このような効果が十分でなく、２８０℃を超えると、拡散や酸化により、接触抵抗、はんだ付け性および加工性が低下する。また、熱処理時間が１分未満では、効果が十分でなく、１８０分を超えると、拡散や酸化による前述の特性の低下が起こり、また経済的でもない。
【００３７】
【実施例】
以下、本発明による銅合金およびその製造方法の実施例について詳細に説明する。
【００３８】
［実施例１〜６、比較例１〜６］
表１に化学成分（重量％）を示す各銅合金を、液相線温度より７０℃高い温度で溶解した後、縦型の小型連続鋳造機を用いて、３０×７０×１０００（ｍｍ）の鋳塊に鋳造した。ただし、鋳型による一次冷却と水シャワ−による二次冷却を調整することにより、液相線から６００℃までの冷却速度は５０℃／分を大きく上回る条件であった。
【００３９】
また、Ｂを含有する実施例１〜６および比較例２の銅合金について、電子プローブマイクロアナライザ（ＥＰＭＡ）によってＢ酸化物を同定し、走査型電子顕微鏡（ＳＥＭ）によってＢ酸化物の粒径を確認したところ、実施例１〜６の銅合金には粒径０．０２〜１μｍのＢ酸化物と粒径１〜３μｍのＢ酸化物が分布していたが、比較例２の銅合金には粒径が５μｍより大きいＢ酸化物が確認された。
【００４０】
その後、各鋳塊を８００〜８４０℃に加熱した後、厚さ５ｍｍまで熱間圧延し、表面やエッジの割れによって熱間加工性を評価した。但し、熱間圧延は１０パス行い、１パス当たりの圧下率を１５％として、最終パスの圧下率を２５％とした。酸洗後に５０倍の光学顕微鏡により割れが全く確認されないものを◎、割れ深さが０．３ｍｍ以下（すなわち、片面０．３ｍｍで面削またはミ−リングした後に割れが全く確認されない）のものを○、割れ深さが０．３ｍｍ以上のものを×とした。さらに、熱間圧延終了温度を約６００℃とし、熱間圧延後の急冷によって結晶粒径が約２０μｍになるように制御した。
【００４１】
次に、冷間圧延によって厚さ１ｍｍまで圧延し、４５０〜５２０℃の温度で熱処理し、結晶粒径が約１０μｍになるように調整した。酸洗後に、厚さ０．２５ｍｍまで冷間圧延し、最終工程で２３０℃の低温焼鈍を施した。このようにして得られた条材から試験片を採取した。
【００４２】
以上のようにして得られた条材を用いて、０．２％耐力、引張強さ、ヤング率、導電率、応力緩和率および応力腐食割れ寿命の測定を行った。０．２％耐力、引張強さおよびヤング率の測定はＪＩＳ−Ｚ−２２４１、導電率はＪＩＳ−Ｈ−０５０５に従って行った。ただし、圧延方向に対して直角方向の０．２％耐力、引張強さおよびヤング率は、長さ７０ｍｍの小型の試験片を用いて測定した。応力緩和試験は、試料表面に０．２％耐力の８０％に当たる曲げ応力を加え、１５０℃で５００時間保持し、曲げぐせを測定することによって行った。また、応力緩和率は下記の式によって計算した。
【００４３】
応力緩和率（％）＝［（Ｌ１−Ｌ２）／（Ｌ１−Ｌ０）］×１００
［Ｌ０：治具の長さ（ｍｍ）、Ｌ１：開始時の試料の長さ（ｍｍ）、Ｌ２：処理後の試料端間の水平距離（ｍｍ）］
【００４４】
応力腐食割れ試験は、０．２％耐力の８０％に当たる曲げ応力を加え、１２．５％のアンモニア水を入れたデシケ−タ内に保持することによって行った。暴露時間は、１０分単位とし、１５０分まで試験した。暴露後に各時間の試験片を取り出し、必要に応じて皮膜を酸洗除去し、光学顕微鏡で１００倍の倍率で割れを観察した。そして、割れを確認した１０分前の時間を応力腐食割れ寿命とした。
【００４５】
これらの結果を表１に示す。
【００４６】
【表１】

【００４７】
表１に示す結果から、実施例１〜６の銅合金は、熱間加工性に優れ、製造面でも有利であり、且つ０．２％耐力、引張強さ、ヤング率および導電率のバランスに優れ、また、耐応力緩和特性および耐応力腐食割れ性も良好である。したがって、実施例１〜６の銅合金は、コネクタなどの電気電子用材料として極めて優れた特性を有する銅合金である。
【００４８】
これに対して、Ｂを添加しない比較例１の銅合金およびＢの添加量が多い比較例２の銅合金は、実施例１の銅合金とほぼ同等の量のＺｎとＳｎを含有して同等の特性を有するが、熱間加工性に劣っており、歩留まり低下によるコストアップの問題がある。
【００４９】
また、Ｓｎ含有量が少ない比較例３の銅合金およびＺｎ含有量が少ない比較例４の銅合金は、熱間加工性に特に劣っていないが、０．２％耐力、引張強さおよび耐応力緩和特性に劣っている。また、比較例３の銅合金はヤング率も劣っている。
【００５０】
さらに、Ｂを添加せずにＣａまたはＭｇを単独で添加した比較例５および６の銅合金は、熱間圧延の途中で割れが入り、その後の冷間加工との兼ね合いで最終板厚まで歩留まり良く製造することができなかった。
【００５１】
［実施例７、比較例７、８］
表１に示す実施例１の銅合金と同じ銅合金（実施例７）と、市販の黄銅１種（Ｃ２６０００−Ｈ０８）（比較例７）と、ばね用りん青銅（Ｃ５２１００−Ｈ０８）（比較例８）について、実施例１〜６と同様の方法により、０．２％耐力、引張強さ、ヤング率、導電率、応力緩和率および応力腐食割れ寿命を測定した。これらの結果を表２に示す。なお、これらの市販の材料は、質別がＨ０８（ばね材用）であり、同一成分の中でも高強度な質別である。
【００５２】
【表２】

【００５３】
表２に示す結果から、実施例７の銅合金は、従来の代表的なコネクタなどの電気電子用材料である黄銅（比較例７）と比較して、０．２％耐力、引張強さ、耐応力緩和特性、耐応力腐食割れ性などが向上していることがわかる。また、ばね用りん青銅（比較例８）と比較しても、ヤング率および導電率に優れている。また、ばね用りん青銅は、高価なＳｎを８％も含有し、原料費が高騰し易く、且つ熱間圧延できないため、製法が限定され、製造費を含めたト−タルコスト面で劣っている。したがって、実施例７の銅合金は、従来の黄銅やりん青銅と比較して十分に優れているといえる。
【００５４】
［実施例８、比較例９］
表１に示す実施例１の銅合金を、一次と二次の冷却条件と引き抜き速度を変えることによって、冷却速度を変化させて連続鋳造した。冷却速度は、熱電対を一緒に鋳込みながら測定した。この銅合金の液相線は約９５０℃であり、この温度から６００℃までの平均冷却速度を求めた。
【００５５】
その後、８４０℃に加熱して、１パス当たり約１５％の圧下率で熱間圧延を１０パス行い、表面とエッジの割れを観察した。この結果、５０℃／分以上の平均冷却速度で鋳造した鋳片（実施例８）には、熱間割れが全く生じなかった。特に、８０℃／分以上の平均冷却速度の鋳片は、熱間圧延温度をさらに上げても、圧下率を上げても対応することができ、条件範囲に余裕がある。これに対し、５０℃／分未満の冷却速度（比較例９）では、熱間割れが発生し、適切な成分範囲であっても、鋳造時の平均冷却速度によっては熱間割れを生じることがあり、歩留まり低下をもたらす場合があることがわかった。
【００５６】
［実施例９、比較例１０、１１］
表１に示す実施例１と同じ組成の銅合金を８４０℃に加熱し、熱間圧延を２パス行った。各パスの圧延直後に水冷したサンプルをリン酸と蒸留水（１：１）の溶液中で電解研磨して腐食させた後、光学顕微鏡により３００倍の倍率で結晶粒組織を観察した。但し、１パス目の圧下率をそれぞれ１５％（実施例９）、５％（比較例９）、３５％（比較例１０）として、２パス目の圧下率をいずれも２５％とした。
【００５７】
実施例９の銅合金の組織では、１パス目の圧延後にすべての結晶粒界に沿って動的再結晶粒が生じ、２パス目の圧延後にほぼ全域にわたって動的再結晶粒組織が観察された。これに対し、比較例９の組織では、１パス目の圧延後に動的再結晶粒がほとんど観察されず、２パス目の圧延後に一部の結晶粒界に沿ってクラックが観察された。また、比較例１０の組織では、１パス目の圧延後に動的再結晶粒が不均一に分布して、一部の結晶粒界に沿ってクラックが観察され、２パス目の圧延後にこれらのクラックがさらに拡大した。したがって、１パス目の圧下率によっては熱延割れを生じることがあり、歩留まり低下をもたらす場合があることがわかった。
【００５８】
［実施例１０〜１１、比較例１２〜１３］
表１に示す実施例１および比較例１と同じ組成の銅合金の鋳塊の断面中央部の鋳造組織（実施例１０および比較例１２）と、これらの銅合金を８４０℃に加熱して圧下率１５％で熱間圧延を１パス行った後に水冷したサンプルの断面中央部の組織（実施例１１および比較例１３）を、リン酸と蒸留水（１：１）の溶液中で電解研磨して腐食させた後、光学顕微鏡により３００倍の倍率で結晶粒組織を観察した。これらの光学顕微鏡写真をそれぞれ図１〜図４に示す。
【００５９】
図１に示すように、実施例１０の銅合金の鋳造組織では、結晶粒界と粒内のいずれにおいても第２相粒子が観察された（この第２相粒子は、ＥＰＭＡとＳＩＭＳで同定した結果、Ｂの酸化物であると判定された）。また、粒子の結晶粒成長に対する阻止効果による粒界が凹凸化していることがわかる。これに対し、図２に示すように、比較例１２の銅合金の鋳造組織では、第２相粒子がほとんど観察されず、結晶粒界が滑らかで、粒径も大きくなっている。
【００６０】
また、図３に示すように、実施例１１の銅合金の組織では、結晶粒界だけではなく、粒内においても第２相粒子のまわりに動的再結晶粒が観察された。これに対し、図４に示すように、比較例１３の銅合金の組織では、動的再結晶粒がほとんど観察されず、一部の結晶粒界に沿ってクラックが観察された。
【００６１】
したがって、本発明による銅合金は、Ｂ酸化物の鋳造組織の微細化および動的再結晶促進効果により、熱間加工性を向上することがわかった。
【００６２】
【発明の効果】
上述したように、本発明による銅合金は、従来の黄銅やりん青銅などと比較して、０．２％耐力、引張強さ、導電率およびヤング率のバランスや、耐応力緩和率特性、耐応力腐食割れ性およびプレス性などに優れ、さらに熱間加工性が良く、安価に製造できるため、黄銅やりん青銅に代わるコネクタなどの電気電子部品用材料として最適なものである。
【図面の簡単な説明】
【図１】実施例１０の銅合金の鋳造組織の光学顕微鏡写真。
【図２】比較例１２の銅合金の鋳造組織の光学顕微鏡写真。
【図３】実施例１１の銅合金の鋳造組織の光学顕微鏡写真。
【図４】比較例１３の銅合金の鋳造組織の光学顕微鏡写真。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a copper alloy having strength, conductivity, resistance to stress relaxation and the like suitable as a material for electric and electronic parts such as connectors, and further having excellent hot workability and cost, and a method for producing the same.
[0002]
[Prior art]
With the development of electronics in recent years, electrical wiring of various machines has become complicated and highly integrated, and accordingly, the amount of copper-clad products used for electrical and electronic parts such as connectors has been increasing. Also, electrical and electronic components such as connectors are required to be lightweight, highly reliable, and low in cost. In order to satisfy these demands, the copper alloy material for connectors is required to have good strength, elasticity, conductivity and press formability since it is thinned and pressed into a complicated shape.
[0003]
Specifically, the copper alloy material for connectors has a 0.2% proof stress of 600 N / mm as a strength not to buckle or deform when inserting or removing or bending a terminal, and a strength against crimping or holding a wire. ² Above, preferably 650 N / mm ² Above, more preferably 700 N / mm ² And the tensile strength is 650 N / mm ² Above, preferably 700 N / mm ² Above, more preferably 750 N / mm ² That is required. When the terminals are pressed, the strength in the direction perpendicular to the direction of the elongation in rolling or the like is required to be a predetermined strength because of the relationship in the chain direction. 2% yield strength is 650N / mm ² Above, preferably 700 N / mm ² Above, more preferably 750 N / mm ² And a tensile strength of 700 N / mm ² Above, preferably 750 N / mm ² Above, more preferably 800 N / mm ² That is required. Further, in order to suppress the generation of Joule heat due to energization, it is preferable that the conductivity is 20% IACS or more.
[0004]
Furthermore, copper alloy materials for connectors need to have excellent corrosion resistance and stress corrosion cracking resistance.In the case of female terminals, thermal loads are applied. No. Specifically, the stress corrosion cracking life is at least three times that of conventional brass, and the stress relaxation rate at 150 ° C. is less than half, preferably 25% or less, more preferably 20% or less of brass. is necessary.
[0005]
Conventionally, brass, phosphor bronze, and the like have been generally used as connector materials. Although brass is used as a low-cost material, its 0.2% proof stress and tensile strength are each 570 N / mm even when the temper is H08 (for spring material). ² And 640 N / mm ² And the 0.2% proof stress is 600 N / mm ² With the above, the tensile strength is 650 N / mm ² The above requirements for a connector material cannot be satisfied. Brass is also inferior in corrosion resistance, stress corrosion cracking resistance and stress relaxation resistance. On the other hand, phosphor bronze has an excellent balance of strength, corrosion resistance, stress corrosion cracking resistance and stress relaxation resistance. For example, in the case of phosphor bronze for springs, the electrical conductivity is as small as 12% IACS and hot working is performed. And it is disadvantageous in terms of cost.
[0006]
Here, the Young's modulus of brass and phosphor bronze are both 110 to 120 kN / mm in the stretching direction. ² 115 to 130 kN / mm in the perpendicular direction ² Such a small Young's modulus meets the requirements as a connector material, and these materials have recently been reviewed. Therefore, it combines the features of brass and phosphor bronze, and has a 0.2% proof stress of 600 N / mm in the elongation direction at a price close to brass. ² As described above, the tensile strength is 650 N / mm ² As described above, the Young's modulus is 120 kN / mm ² Hereinafter, the conductivity is 20% IACS or more, the stress relaxation rate is 20% or less, and the 0.2% proof stress in the direction perpendicular to the stretching direction is 650 N / mm. ² As described above, the tensile strength is 700 N / mm ² As described above, the Young's modulus is 130 kN / mm ² The following materials are desired:
[0007]
Further, the material for the connector is often plated with Sn, and the use of Sn as an alloy increases as a material containing Sn. Furthermore, when Zn is contained, as represented by brass, an alloy excellent in balance of strength, workability and cost is easily obtained. From such a viewpoint, the Cu-Zn-Sn alloy is a remarkable alloy system.
[0008]
For example, CDA standard C42500 is a Cu-9.5Zn-2.0Sn-0.2P alloy, which is well known as a material for connectors. C43400 is a Cu-14Zn-0.7Sn alloy, which is used for switches, relays and terminals, albeit in small quantities. However, Cu-Zn-Sn alloys having a higher Zn content are hardly used as connector materials. This is because the hot workability decreases as the Zn content and the Sn content increase. For example, as a copper alloy having a larger amount of Zn than C42500, C43500 (Cu-18Zn-0.9Sn), C44500 (Cu-28Zn-1Sn-0.05P), and C46700 (Cu-39Zn-0.8Sn-0.05P) There are only products such as plates, rods and tubes for musical instruments, ships, miscellaneous goods, etc., and are not used as wrought materials for connectors, especially as strips . Also, regarding the properties of these materials, the 0.2% proof stress in the stretching direction is 600 N / mm. ² As described above, the tensile strength is 650 N / mm ² As described above, the Young's modulus is 120 kN / mm ² Hereinafter, the conductivity is 20% IACS or more, the stress relaxation rate is 20% or less, and the 0.2% proof stress in the direction perpendicular to the stretching direction is 650 N / mm. ² As described above, the tensile strength is 700 N / mm ² As described above, the Young's modulus is 130 kN / mm ² In addition, it is not possible to satisfy all the properties required for the connector material such as pressability and stress corrosion cracking resistance. In particular, in order to maintain the above-mentioned various properties, it is necessary to contain Zn and Sn in a certain amount or more. However, when the amount of Zn and the amount of Sn increase, hot cracking is likely to occur, and there is a problem of an increase in cost due to a decrease in yield.
[0009]
In view of such a current situation, it has been proposed to obtain a copper alloy having excellent properties by containing an appropriate amount of Zn and Sn or further containing Si or the like and adopting an appropriate manufacturing method (for example, , Patent Documents 1 and 2).
[0010]
[Patent Document 1]
JP 2001-294957 A (Paragraph No. 0014)
[Patent Document 2]
JP-A-2002-88428 (paragraph number 0014)
[0011]
[Problems to be solved by the invention]
However, in these conventional methods, the control of hot rolling conditions is very strict, and the yield may be reduced due to fine cracks, so that a copper alloy excellent in hot rollability should be provided. Is desired.
[0012]
Therefore, in view of such conventional problems, the present invention provides a copper alloy having the above-mentioned various characteristics required for materials for electrical and electronic components such as connectors with the development of electronics, namely, a copper alloy having a capacity of 0.1 mm. An object of the present invention is to provide a copper alloy excellent in 2% proof stress, tensile strength, electrical conductivity, Young's modulus, stress relaxation resistance, pressability, hot workability and cost, and a method for producing the same.
[0013]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, 20 to 46% by weight of Zn, 0.1 to 5.0% by weight of Sn, and 0.001 to 0.5% by weight of By adding B oxide having a particle size of 5 μm or less to a copper alloy material containing B and the balance consisting of Cu and unavoidable impurities, hot working by the effect of refining cast crystal grains and promoting dynamic recrystallization Excellent in stretchability and 0.2% proof stress in the stretching direction is 600 N / mm ² As described above, the tensile strength is 650 N / mm ² As described above, the Young's modulus is 120 kN / mm ² Hereinafter, the conductivity is 20% IACS or more, the stress relaxation rate is 20% or less, and the 0.2% proof stress in the direction perpendicular to the stretching direction is 650 N / mm. ² As described above, the tensile strength is 700 N / mm ² As described above, the Young's modulus is 130 kN / mm ² The inventors have found that the following copper alloy can be obtained, and have completed the present invention.
[0014]
That is, the copper alloy according to the present invention contains 20 to 46% by weight of Zn, 0.1 to 5.0% by weight of Sn, and 0.001 to 0.5% by weight of B, with the balance being Cu And B oxide having a particle size of 5 μm or less, or containing B oxide and having a particle size of 5 μm or less.
[0015]
This copper alloy preferably contains B oxide having a particle size of less than 1 μm and contains B oxide having a particle size of 1 to 5 μm. Also, the 0.2% proof stress in the elongation direction is 600 N / mm. ² As described above, the tensile strength is 650 N / mm ² As described above, the Young's modulus is 120 kN / mm ² Hereinafter, the conductivity is 20% IACS or more, the stress relaxation rate is 20% or less, and the 0.2% proof stress in the direction perpendicular to the stretching direction is 650 N / mm. ² As described above, the tensile strength is 700 N / mm ² As described above, the Young's modulus is 130 kN / mm ² It is preferred that: The copper alloy further comprises 0.01 to 3% by weight of Fe, 0.01 to 5% by weight of Ni, 0.01 to 3% by weight of Co, and 0.01 to 3% by weight of Ti. And 0.01 to 2% by weight of Mg, 0.01 to 2% by weight of Zr, 0.01 to 1% by weight of Ca, 0.01 to 3% by weight of Si, and 0.01 to 2% by weight. 10% by weight of Mn, 0.01 to 3% by weight of Cd, 0.01 to 5% by weight of Al, 0.01 to 3% by weight of Pb, and 0.01 to 3% by weight of Bi , 0.01 to 3% by weight of Be, 0.01 to 1% by weight of Te, 0.01 to 3% by weight of Y, 0.01 to 3% by weight of La, and 0.01 to 3% by weight. Weight% Cr, 0.01 to 3 weight% Ce, 0.01 to 1 weight% V, 0.01 to 1 weight% Ba, 0.01 to 5 weight% Au, 0.01 to 5% by weight of Ag 0.005-0.5 at least one element of the weight% of P, may comprise as the total amount thereof is 0.01 to 5 wt%.
[0016]
Further, the method for producing a copper alloy according to the present invention contains 20 to 46% by weight of Zn, 0.1 to 5.0% by weight of Sn, and 0.001 to 0.5% by weight of B, In the method for producing a copper alloy in which the balance consists of Cu and unavoidable impurities, the raw material of the copper alloy is melted and cooled at a cooling rate of 50 ° C./min or more in a temperature range from a liquidus temperature to 600 ° C. After hot rolling, hot rolling is performed at a temperature of 900 ° C. or less, then cold rolling and annealing in a temperature range of 300 to 650 ° C. are repeated to reduce the crystal grain size after the annealing to 25 μm or less, and then 30% or more. Cold rolling at a working ratio of 450 ° C. and low-temperature annealing at 450 ° C. or less.
[0017]
In this method for producing a copper alloy, in hot rolling, the rolling reduction in the first pass hot rolling is 5 to 30%, and the rolling reduction in the next pass hot rolling is 5 to 40%. Is preferably 25% or more in hot rolling, and more preferably 10 to 20% in the first pass hot rolling. Further, the crystal grain size after annealing is preferably 15 μm or less, and the working ratio of cold rolling at a working ratio of 30% or more is preferably 60% or more. Further, the copper alloy preferably contains B oxide having a particle size of 5 μm or less, and the 0.2% proof stress in the elongation direction is 600 N / mm. ² As described above, the tensile strength is 650 N / mm ² As described above, the Young's modulus is 120 kN / mm ² Hereinafter, the conductivity is 20% IACS or more, the stress relaxation rate is 20% or less, and the 0.2% proof stress in the direction perpendicular to the stretching direction is 650 N / mm. ² As described above, the tensile strength is 700 N / mm ² As described above, the Young's modulus is 130 kN / mm ² It is preferred that:
[0018]
According to this method for producing a copper alloy, a copper alloy having various characteristics required for a material for electric and electronic parts such as a connector while reducing cost by adding a component cheaper than copper, namely, 0 It is possible to provide a copper alloy for connectors excellent in 2% proof stress, tensile strength, electrical conductivity, Young's modulus, stress relaxation resistance, pressability, hot workability, cost, and the like.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the copper alloy according to the invention contains 20 to 46% by weight of Zn, 0.1 to 5.0% by weight of Sn and 0.001 to 0.5% by weight of B, with the balance being Is composed of Cu and unavoidable impurities, and contains B oxide having a particle size of 5 μm or less. The reasons for limiting the amounts of the components of the copper alloy as described above are as follows.
[0020]
When Zn is added to a copper alloy, the strength and resilience of the copper alloy are improved, and since Zn is less expensive than Cu, it is desirable to add a large amount of Zn. However, when the Zn content exceeds 46% by weight, segregation at the grain boundaries becomes severe in the presence of Sn, and the hot workability of the copper alloy is significantly reduced. Further, the cold workability, corrosion resistance, and stress corrosion cracking resistance of the copper alloy are also reduced. Further, the plating property and the solderability due to moisture and heating are also reduced. On the other hand, if the Zn content is less than 20% by weight, the strength and spring property such as 0.2% proof stress and tensile strength of the copper alloy are insufficient, the Young's modulus becomes large, and the scrap obtained by surface treatment with Sn is used as a raw material. In this case, hydrogen gas occlusion during melting of the copper alloy increases, and blowholes of the ingot are easily generated. Further, the amount of inexpensive Zn is small, which is economically disadvantageous. Therefore, the amount of Zn is preferably in the range of 20 to 46% by weight, and more preferably in the range of 24 to 37% by weight.
[0021]
Sn has the effect of improving mechanical properties such as strength and elasticity such as 0.2% proof stress and tensile strength without increasing the Young's modulus of the copper alloy even in a trace amount. Further, it is preferable that the copper alloy contains Sn as an additional element also from the viewpoint of reusing a material surface-treated with Sn such as Sn plating. However, when the Sn content increases, the electrical conductivity of the copper alloy sharply decreases, and in the coexistence with Zn, the grain boundary segregation becomes severe, and the hot workability remarkably decreases. In order to ensure hot workability, the Sn content must be in a range not exceeding 5.0% by weight. On the other hand, if the Sn content is less than 0.1% by weight, the effect of improving the mechanical properties of the copper alloy is small, and it becomes difficult to use press waste or the like that has been subjected to Sn plating or the like as a raw material. Therefore, the Sn content is preferably in the range of 0.1 to 5.0% by weight, and more preferably in the range of 0.5 to 1.8% by weight.
[0022]
B has a higher affinity for oxygen than Cu, Zn and Sn, which are the main components of the copper alloy according to the present invention, and thus has an effect of preventing oxidation of Cu, Zn and Sn.
[0023]
Further, B is not a strong deoxidizing agent such as Ca and Mg, has little loss during the addition process, and the generated oxide is hard to be clustered.
[0024]
Further, B can react with oxygen in the process of melting or solidifying, and a particulate oxide having a particle size of several tens nm to several μm can be obtained. This oxide has the effect of refining the cast crystal grains as nuclei of the crystal grains and inhibiting the grain growth. Particularly, the granular oxide of about 1 to 5 μm promotes dynamic recrystallization, and the oxide of 1 μm or less inhibits the growth of recrystallized grains. It is possible to achieve both refinement of crystal grains. Due to these synergistic effects, hot workability can be significantly improved. When the particle size of the B oxide is larger than 5 μm, cracks tend to occur due to stress concentration near the particles during rolling. On the other hand, a B oxide having a particle size of less than 1 μm has an effect of suppressing both the occurrence of dynamic recrystallization and the growth of recrystallized grains, and a granular oxide having a particle size of about 1 to 5 μm Has the effect of promoting. Therefore, in order to promote the generation of dynamic recrystallization and suppress the growth of recrystallized grains at the same time, it is necessary to contain a B oxide having a particle size of 5 μm or less (that is, a maximum particle size of 5 μm and including fine particles). It is necessary and preferably contains B oxide having a particle size of less than 1 μm and contains B oxide having a particle size of 1 to 5 μm. The B oxide is identified by an electron probe microanalyzer (EPMA), and its particle size can be confirmed by a scanning electron microscope (SEM). However, simply, the approximate particle size of the B oxide can be known by an optical microscope or the like, and can be referred to.
[0025]
Further, since B has a dispersion strengthening effect, it also has the effect of improving the softening temperature and stress relaxation resistance of the final product.
[0026]
When the amount of B is less than 0.001% by weight, the effect of improving hot workability as described above is lost. On the other hand, if the amount of B exceeds 0.5% by weight, the size of the generated second phase becomes large, and conversely, the hot workability is significantly reduced, and the cost is disadvantageous. Therefore, the amount of B is preferably in the range of 0.001 to 0.5% by weight, more preferably in the range of 0.002 to 0.05% by weight.
[0027]
In addition, if the components are limited as described above, it is possible to suppress the formation of Sn oxide which precipitates at the grain boundary at a high temperature such as casting or hot rolling, and the 0.2% proof stress in the elongation direction is reduced. 600 N / mm ² As described above, the tensile strength is 650 N / mm ² As described above, the Young's modulus is 120 kN / mm ² Hereinafter, the conductivity is 20% IACS or more, the stress relaxation rate is 20% or less, and the 0.2% proof stress in the direction perpendicular to the stretching direction is 650 N / mm. ² As described above, the tensile strength is 700 N / mm ² As described above, the Young's modulus is 130 kN / mm ² In addition, various characteristics required as a connector material, specifically, corrosion resistance, stress corrosion cracking resistance (crack life in ammonia vapor is three times or more than that of brass), stress relaxation resistance (at 150 ° C.) A copper alloy having a relaxation rate equal to or less than half that of one kind of brass and comparable to phosphor bronze) and a press punching property can be produced.
[0028]
Further, the copper alloy contains 0.01 to 3% by weight of Fe, 0.01 to 5% by weight of Ni, 0.01 to 3% by weight of Co, Weight% Ti, 0.01 to 2 weight% Mg, 0.01 to 2 weight% Zr, 0.01 to 1 weight% Ca, 0.01 to 3 weight% Si, 0.01 to 10 wt% Mn, 0.01 to 3 wt% Cd, 0.01 to 5 wt% Al, 0.01 to 3 wt% Pb, and 0.01 to 3 wt% % Bi, 0.01 to 3% by weight of Be, 0.01 to 1% by weight of Te, 0.01 to 3% by weight of Y, 0.01 to 3% by weight of La, 0.01 to 3% by weight of Cr, 0.01 to 3% by weight of Ce, 0.01 to 1% by weight of V, 0.01 to 1% by weight of Ba, and 0.01 to 5% by weight. Au and 0.01 to 5 layers % And Ag, and at least one element of 0.005-0.5 wt% of P, the total amount thereof may include such that 0.01 to 5 wt%.
[0029]
These elements can improve strength without significantly impairing conductivity, Young's modulus, and moldability. If the content is out of the range of the content of each element, a desired effect cannot be obtained or disadvantages are caused in hot workability, cold workability, pressability, conductivity, Young's modulus, cost, and the like.
[0030]
Next, an embodiment of a method for producing a copper alloy according to the present invention will be described.
[0031]
First, the raw material of the copper alloy according to the present invention is melted and cast. When dissolving the raw material, B can be added by B powder or a mother alloy such as Cu-B, Ni-B or Fe-B. However, it is desirable to introduce B when about half of the raw material is dissolved. If the charging time of B is too early, loss due to oxidation of B is large. The atmosphere may be an air atmosphere, but it is preferable to seal with an inert gas from the viewpoint of preventing oxidation. However, in a reducing gas atmosphere, high temperatures are disadvantageous due to absorption and diffusion of hydrogen due to decomposition of moisture.
[0032]
Next, after melting the raw materials, it is desirable to cast the ingot by continuous casting. This continuous casting may be either vertical or horizontal. However, cooling is performed at a cooling rate of 50 ° C./min or more in the temperature range from the liquidus temperature to 600 ° C. When the cooling rate is less than 50 ° C./min, segregation of Sn occurs at the grain boundary, and the B oxide particles easily cluster (aggregate), thereby deteriorating the hot workability and lowering the yield. The temperature range defining the cooling rate may be a temperature range from the liquidus temperature to 600 ° C. Even if the temperature range above the liquidus line is defined, there is no effect. On the other hand, if the temperature range is 600 ° C. or less, excessive segregation of Sn at the grain boundaries does not occur in the cooling step time during casting, so the cooling rate is specified. The temperature range to be used is a temperature range from the liquidus temperature to 600 ° C.
[0033]
Hot rolling is performed after melting and casting. The heating temperature for hot rolling is 900 ° C. or less. At a temperature exceeding 900 ° C., hot cracks occur due to segregation of Sn at the grain boundaries, and the yield decreases. The rolling reduction at the time of the first pass hot rolling at a temperature of 900 ° C. or less is set to 5 to 30%. If the rolling reduction exceeds 30%, cracks tend to occur along the cast crystal grain boundaries. On the other hand, if the rolling reduction is less than 5%, dynamic recrystallization or static recrystallization between passes is difficult to occur, and hot cracking may occur during rolling in the second pass. Further, the number of rolling passes increases, which is not efficient. By dynamically recrystallizing after 2-3 passes, micro segregation during casting and disappearance of the cast structure, a material which is structurally homogenous even if it contains Zn and Sn in the composition of the copper alloy according to the present invention. Obtainable. More preferably, the rolling reduction in the first pass is set to 10 to 20%. In the next pass, the rolling reduction may be 5 to 40%, and the occurrence of hot cracking can be prevented, and subsequently, rolling can be performed efficiently. Further, it is preferable that the rolling reduction in the final pass is as large as possible, and specifically, it is preferable that the rolling reduction is 25% or more. Thus, the crystal grain size after hot rolling can be controlled to 35 μm or less, preferably 15 μm or less. If the crystal grain size after hot rolling exceeds 35 μm, the control range of the subsequent cold working rate and annealing conditions is narrow, and if it deviates even a little, the crystal grains are liable to be mixed grains, and the properties are deteriorated.
[0034]
After hot rolling, the surface is chamfered as necessary. Thereafter, cold rolling and annealing in a temperature range of 300 to 650 ° C. are repeated to reduce the crystal grain size after annealing to 25 μm or less. If the temperature is lower than 300 ° C., the time required for controlling the crystal grains becomes long, which is uneconomical. If the temperature exceeds 650 ° C., the crystal grains become coarse in a short time. If the crystal grain size after annealing exceeds 25 μm, mechanical properties such as 0.2% proof stress and workability deteriorate. The grain size after annealing is preferably 15 μm or less, more preferably 10 μm or less.
[0035]
The annealed material thus obtained is subjected to cold rolling at a working ratio of 30% or more and low-temperature annealing at 450 ° C. or less, so that the 0.2% proof stress in the elongation direction is 600 N / mm. ² As described above, the tensile strength is 650 N / mm ² As described above, the Young's modulus is 120 kN / mm ² Hereinafter, the conductivity is 20% IACS or more, the stress relaxation rate is 20% or less, and the 0.2% proof stress in the direction perpendicular to the stretching direction is 650 N / mm. ² As described above, the tensile strength is 700 N / mm ² As described above, the Young's modulus is 130 kN / mm ² The following copper alloy is used. If the cold working ratio is less than 30%, the improvement in strength due to work hardening is insufficient, and the improvement in mechanical properties is insufficient. More preferably, the working ratio is 60% or more. Low temperature annealing is necessary to further improve 0.2% proof stress, tensile strength, spring threshold and stress relaxation resistance. At a temperature exceeding 450 ° C., the applied heat capacity is too large to soften in a short period of time, and in both the batch type and the continuous type, characteristic variations easily occur in the work. Therefore, the temperature condition of the low-temperature annealing is set to 450 ° C. or less.
[0036]
After the material thus obtained is pressed into terminals, heat treatment may be performed at a temperature of 100 to 280 ° C. for 1 to 180 minutes. By this heat treatment, the spring limit value and the stress relaxation resistance lowered by the press working are improved, and further, whisker countermeasures can be realized. If the temperature is lower than 100 ° C., such an effect is not sufficient. If the temperature is higher than 280 ° C., contact resistance, solderability and workability are reduced due to diffusion and oxidation. If the heat treatment time is less than 1 minute, the effect is not sufficient. If the heat treatment time is more than 180 minutes, the above-described characteristics are deteriorated due to diffusion and oxidation, and it is not economical.
[0037]
【Example】
Hereinafter, examples of the copper alloy and the method for producing the same according to the present invention will be described in detail.
[0038]
[Examples 1 to 6, Comparative Examples 1 to 6]
After melting each copper alloy having a chemical component (% by weight) shown in Table 1 at a temperature 70 ° C. higher than the liquidus temperature, using a small vertical continuous casting machine, a 30 × 70 × 1000 (mm). It was cast into an ingot. However, by adjusting the primary cooling by the mold and the secondary cooling by the water shower, the cooling rate from the liquidus line to 600 ° C. was much higher than 50 ° C./min.
[0039]
Further, for the copper alloys of Examples 1 to 6 and Comparative Example 2 containing B, the B oxide was identified by an electron probe microanalyzer (EPMA), and the particle size of the B oxide was determined by a scanning electron microscope (SEM). It was confirmed that the copper alloys of Examples 1 to 6 had a distribution of B oxide having a particle size of 0.02 to 1 μm and a B oxide having a particle size of 1 to 3 μm. B oxide having a particle size larger than 5 μm was confirmed.
[0040]
Thereafter, each ingot was heated to 800 to 840 ° C., then hot-rolled to a thickness of 5 mm, and hot workability was evaluated by cracks on the surface and edges. However, hot rolling was performed 10 passes, and the rolling reduction per pass was 15%, and the rolling reduction in the final pass was 25%. A: No crack was observed at all by an optical microscope at a magnification of 50 after pickling. A: 0.3 mm or less in crack depth (that is, no crack was observed after face milling or milling with 0.3 mm on one side). , And those having a crack depth of 0.3 mm or more were rated x. Further, the hot rolling end temperature was set to about 600 ° C., and the crystal grain size was controlled to about 20 μm by quenching after hot rolling.
[0041]
Next, it was rolled to a thickness of 1 mm by cold rolling and heat-treated at a temperature of 450 to 520 ° C. to adjust the crystal grain size to about 10 μm. After pickling, it was cold-rolled to a thickness of 0.25 mm and subjected to low-temperature annealing at 230 ° C. in the final step. A test piece was collected from the strip obtained in this manner.
[0042]
Using the strip obtained as described above, 0.2% proof stress, tensile strength, Young's modulus, conductivity, stress relaxation rate, and stress corrosion cracking life were measured. The 0.2% proof stress, tensile strength and Young's modulus were measured according to JIS-Z-2241, and the electrical conductivity was measured according to JIS-H-0505. However, the 0.2% proof stress, tensile strength and Young's modulus in the direction perpendicular to the rolling direction were measured using a small test piece having a length of 70 mm. The stress relaxation test was performed by applying a bending stress corresponding to 80% of the 0.2% proof stress to the sample surface, maintaining the sample at 150 ° C. for 500 hours, and measuring the bending. The stress relaxation rate was calculated by the following equation.
[0043]
Stress relaxation rate (%) = [(L1-L2) / (L1-L0)] × 100
[L0: length of jig (mm), L1: length of sample at start (mm), L2: horizontal distance between sample ends after treatment (mm)]
[0044]
The stress corrosion cracking test was performed by applying a bending stress corresponding to 80% of the 0.2% proof stress and holding the sample in a desiccator containing 12.5% aqueous ammonia. The exposure time was in units of 10 minutes and tested up to 150 minutes. After the exposure, the test piece was taken out at each time, the coating was removed by pickling as needed, and cracks were observed at a magnification of 100 times with an optical microscope. The time 10 minutes before the crack was confirmed was defined as the stress corrosion cracking life.
[0045]
Table 1 shows the results.
[0046]
[Table 1]

[0047]
From the results shown in Table 1, the copper alloys of Examples 1 to 6 are excellent in hot workability, advantageous in terms of production, and have a balance of 0.2% proof stress, tensile strength, Young's modulus and conductivity. It is excellent and has good stress relaxation resistance and stress corrosion cracking resistance. Therefore, the copper alloys of Examples 1 to 6 are copper alloys having extremely excellent properties as electrical and electronic materials such as connectors.
[0048]
On the other hand, the copper alloy of Comparative Example 1 in which B was not added and the copper alloy of Comparative Example 2 in which the amount of B added was large contained Zn and Sn in almost the same amount as the copper alloy of Example 1 and were equivalent. However, the hot workability is inferior, and there is a problem that the cost is increased due to a decrease in yield.
[0049]
The copper alloy of Comparative Example 3 having a small Sn content and the copper alloy of Comparative Example 4 having a small Zn content are not particularly inferior in hot workability, but have 0.2% proof stress, tensile strength and stress resistance. Poor relaxation properties. Further, the copper alloy of Comparative Example 3 is also inferior in Young's modulus.
[0050]
Further, the copper alloys of Comparative Examples 5 and 6, in which Ca or Mg was added alone without adding B, cracked in the middle of hot rolling, and the yield was reduced to the final sheet thickness in view of the subsequent cold working. Could not be manufactured well.
[0051]
[Example 7, Comparative Examples 7, 8]
The same copper alloy as Example 1 shown in Table 1 (Example 7), commercially available brass Class 1 (C26000-H08) (Comparative Example 7), and phosphor bronze for springs (C52100-H08) (Comparative Example) For 8), 0.2% proof stress, tensile strength, Young's modulus, conductivity, stress relaxation rate, and stress corrosion cracking life were measured in the same manner as in Examples 1 to 6. Table 2 shows the results. In addition, these commercially available materials have a temper of H08 (for spring materials), and have the highest strength among the same components.
[0052]
[Table 2]

[0053]
From the results shown in Table 2, the copper alloy of Example 7 has a 0.2% proof stress, a tensile strength, as compared with brass (Comparative Example 7) which is a conventional electrical and electronic material such as a connector. It can be seen that stress relaxation resistance, stress corrosion cracking resistance, and the like are improved. Also, it is excellent in Young's modulus and conductivity as compared with phosphor bronze for spring (Comparative Example 8). Further, the phosphor bronze for spring contains as much as 8% of expensive Sn, so that the raw material cost is apt to soar and cannot be hot rolled, so that the manufacturing method is limited and the total cost including the manufacturing cost is inferior. . Therefore, it can be said that the copper alloy of Example 7 is sufficiently superior to conventional brass and phosphor bronze.
[0054]
[Example 8, Comparative Example 9]
The copper alloy of Example 1 shown in Table 1 was continuously cast while changing the cooling rate by changing the primary and secondary cooling conditions and the drawing speed. The cooling rate was measured while casting the thermocouples together. The liquidus of this copper alloy was about 950 ° C., and the average cooling rate from this temperature to 600 ° C. was determined.
[0055]
Then, it heated at 840 degreeC and performed hot rolling 10 passes at a rolling reduction of about 15% per pass, and observed the crack of the surface and the edge. As a result, no hot tearing occurred in the slab (Example 8) cast at an average cooling rate of 50 ° C./min or more. In particular, a slab having an average cooling rate of 80 ° C./min or more can cope with an increase in the hot rolling temperature or an increase in the rolling reduction, and the condition range has room. On the other hand, at a cooling rate of less than 50 ° C./min (Comparative Example 9), hot cracking occurs, and even in an appropriate component range, hot cracking may occur depending on the average cooling rate during casting. Yes, it was found that the yield could be reduced.
[0056]
[Example 9, Comparative Examples 10, 11]
A copper alloy having the same composition as in Example 1 shown in Table 1 was heated to 840 ° C., and hot rolling was performed in two passes. Immediately after rolling in each pass, the water-cooled sample was electrolytically polished and corroded in a solution of phosphoric acid and distilled water (1: 1), and then the grain structure was observed with an optical microscope at a magnification of 300 times. However, the rolling reduction in the first pass was 15% (Example 9), 5% (Comparative Example 9), and 35% (Comparative Example 10), and the rolling reduction in the second pass was 25%.
[0057]
In the structure of the copper alloy of Example 9, dynamic recrystallized grains were generated along all crystal grain boundaries after rolling in the first pass, and a dynamic recrystallized grain structure was observed over almost the entire area after rolling in the second pass. Was. On the other hand, in the structure of Comparative Example 9, almost no dynamic recrystallized grains were observed after rolling in the first pass, and cracks were observed along some crystal grain boundaries after rolling in the second pass. In the structure of Comparative Example 10, the dynamic recrystallized grains were unevenly distributed after the rolling in the first pass, and cracks were observed along some of the grain boundaries. Cracks have further expanded. Therefore, it was found that depending on the rolling reduction in the first pass, hot-rolling cracks may occur, and the yield may be reduced.
[0058]
[Examples 10 to 11, Comparative Examples 12 to 13]
The casting structure (Example 10 and Comparative Example 12) in the center of the cross section of the copper alloy ingot having the same composition as Example 1 and Comparative Example 1 shown in Table 1 and these copper alloys were heated to 840 ° C. and reduced. The structure (Example 11 and Comparative Example 13) at the center of the cross section of the sample which had been subjected to one pass of hot rolling at a rate of 15% and then water-cooled was electropolished in a solution of phosphoric acid and distilled water (1: 1). After corrosion, the grain structure was observed with an optical microscope at a magnification of 300 times. These optical micrographs are shown in FIGS.
[0059]
As shown in FIG. 1, in the cast structure of the copper alloy of Example 10, second phase particles were observed both at the grain boundaries and within the grains (the second phase particles were identified by EPMA and SIMS). As a result, it was determined to be an oxide of B). Further, it can be seen that the grain boundaries due to the effect of inhibiting the growth of the crystal grains of the grains are uneven. On the other hand, as shown in FIG. 2, in the copper alloy casting structure of Comparative Example 12, the second phase particles were hardly observed, and the crystal grain boundaries were smooth and the particle size was large.
[0060]
Further, as shown in FIG. 3, in the structure of the copper alloy of Example 11, dynamic recrystallized grains were observed around the second phase particles not only at the grain boundaries but also within the grains. On the other hand, as shown in FIG. 4, in the structure of the copper alloy of Comparative Example 13, almost no dynamic recrystallized grains were observed, and cracks were observed along some crystal grain boundaries.
[0061]
Therefore, it was found that the copper alloy according to the present invention improves hot workability due to the effect of miniaturizing the cast structure of B oxide and promoting dynamic recrystallization.
[0062]
【The invention's effect】
As described above, the copper alloy according to the present invention has a 0.2% proof stress, a balance of tensile strength, conductivity and Young's modulus, a stress relaxation rate characteristic, and a resistance to stress, as compared with conventional brass and phosphor bronze. It is excellent in stress corrosion cracking properties, pressability, etc., has good hot workability, and can be manufactured at low cost. Therefore, it is most suitable as a material for electrical and electronic parts such as connectors replacing brass and phosphor bronze.
[Brief description of the drawings]
FIG. 1 is an optical micrograph of a cast structure of a copper alloy of Example 10.
FIG. 2 is an optical micrograph of a cast structure of a copper alloy of Comparative Example 12.
FIG. 3 is an optical micrograph of a cast structure of a copper alloy of Example 11.
FIG. 4 is an optical micrograph of a cast structure of a copper alloy of Comparative Example 13.

Claims

It contains 20 to 46% by weight of Zn, 0.1 to 5.0% by weight of Sn, and 0.001 to 0.5% by weight of B, with the balance being Cu and unavoidable impurities. A copper alloy containing a B oxide of 5 μm or less.

It contains 20 to 46% by weight of Zn, 0.1 to 5.0% by weight of Sn and 0.001 to 0.5% by weight of B, with the balance being Cu and unavoidable impurities, A copper alloy, characterized in that it contains a substance and has a B oxide particle size of 5 μm or less.

The copper alloy according to claim 1, comprising a B oxide having a particle size of less than 1 μm and a B oxide having a particle size of 1 to 5 μm.

0.2% proof stress wrought direction 600N / mm ² or more and a tensile strength of 650 N / mm ² or more, a Young's modulus of 120 kN / mm ² or less, conductivity is 20% IACS or more, the stress relaxation rate more than 20% and a 0.2% yield strength of the direction perpendicular to the wrought direction 650 N / mm ² or more, a tensile strength of 700 N / mm ² or more, the Young's modulus is equal to or is 130 kN / mm ² or less, The copper alloy according to claim 1.

The copper alloy further comprises 0.01 to 3% by weight of Fe, 0.01 to 5% by weight of Ni, 0.01 to 3% by weight of Co, and 0.01 to 3% by weight of Ti; 0.01 to 2 wt% Mg, 0.01 to 2 wt% Zr, 0.01 to 1 wt% Ca, 0.01 to 3 wt% Si, and 0.01 to 10 wt% % Of Mn, 0.01 to 3% by weight of Cd, 0.01 to 5% by weight of Al, 0.01 to 3% by weight of Pb, 0.01 to 3% by weight of Bi, 0.01 to 3% by weight of Be, 0.01 to 1% by weight of Te, 0.01 to 3% by weight of Y, 0.01 to 3% by weight of La, and 0.01 to 3% by weight. Cr, 0.01 to 3% by weight of Ce, 0.01 to 1% by weight of V, 0.01 to 1% by weight of Ba, 0.01 to 5% by weight of Au, From 0.1 to 5% by weight of Ag; 5. The method according to claim 1, wherein at least one element of P is contained in an amount of 0.01 to 5% by weight. Copper alloy.

A copper alloy containing 20 to 46% by weight of Zn, 0.1 to 5.0% by weight of Sn, and 0.001 to 0.5% by weight of B, with the balance being Cu and unavoidable impurities. In the production method, the raw material of the copper alloy is melted, cooled at a cooling rate of 50 ° C./min or more in a temperature range from the liquidus temperature to 600 ° C. to obtain an ingot, and then heated at a temperature of 900 ° C. or less. Cold rolling and then cold rolling and annealing in a temperature range of 300 to 650 ° C. are repeated to reduce the crystal grain size after annealing to 25 μm or less. A method for producing a copper alloy, comprising performing low-temperature annealing.

In the hot rolling, the rolling reduction in the hot rolling in the first pass is 5 to 30%, the rolling reduction in the hot rolling in the next pass is 5 to 40%, and the rolling reduction in the hot rolling in the final pass is The method for producing a copper alloy according to claim 6, wherein the content is set to 25% or more.

The method for producing a copper alloy according to claim 7, wherein a reduction ratio in the first pass hot rolling is set to 10 to 20%.

The method for producing a copper alloy according to claim 6, wherein a crystal grain size after the annealing is set to 15 μm or less.

The method for producing a copper alloy according to any one of claims 6 to 9, wherein a working ratio of the cold rolling at a working ratio of 30% or more is set to 60% or more.

The method for producing a copper alloy according to any one of claims 6 to 10, wherein the copper alloy contains a B oxide having a particle size of 5 µm or less.

It said copper alloy, 0.2% yield strength of wrought direction 600N / mm ² or more and a tensile strength of 650 N / mm ² or more, a Young's modulus of 120 kN / mm ² or less, conductivity is 20% IACS or more, the stress relaxation rate is 20% or less, 0.2% proof stress of a direction perpendicular to the wrought direction 650 N / mm ² or more, a tensile strength of 700 N / mm ² or more, a Young's modulus is 130 kN / mm ² or less The method for producing a copper alloy according to any one of claims 6 to 11, wherein: