JP4296344B2

JP4296344B2 - Copper alloy material

Info

Publication number: JP4296344B2
Application number: JP2003081460A
Authority: JP
Inventors: 敏洋佐藤; 康雄猪鼻
Original assignee: Dowa Metaltech Co Ltd
Current assignee: Dowa Metaltech Co Ltd
Priority date: 2003-03-24
Filing date: 2003-03-24
Publication date: 2009-07-15
Anticipated expiration: 2023-03-24
Also published as: JP2004285449A

Description

【０００１】
【発明の属する技術分野】
本発明は、コネクタ等の電気・電子部品用材料として使用される銅合金材に関し、更に詳しくは、優れたプレス成形性、強度、弾性、導電性に加えて特に曲げ加工性に優れた低廉な電気・電子部品用銅合金材およびその製造方法に関する。
【０００２】
【従来の技術】
近年、エレクトロニクスの発達により、種々の機械の電気配線は複雑化、高集積化し、それに伴いコネクタ等の電気・電子部品製造用材料として使用される伸銅品材料の需要が増加している。
【０００３】
また、コネクタ等の電気・電子部品は、軽量性、高信頼性、低コスト性が要求されている。よって、これらの要求を満たすために、コネクタ等の電気・電子部品用銅合金材料は薄肉化され、端子幅も狭くなり、また複雑な形状にプレスするため、プレス成形性、強度、弾性及び導電性が良好でなければならない。
【０００４】
従来、黄銅やりん青銅等が、コネクタ材として一般に使用されてきた。黄銅は低コストの材料として使用されているが、引張強さは質別がＥＨでも６００Ｎ／mm² を越えず、また耐食性、耐応力腐食割れ性で劣っている。また、質別ＳＨ・ＥＳＨにおいては６００Ｎ／mm²以上の高い強度を有するものの、曲げ加工性が劣り、複雑な加工に対応できない。りん青銅は強度、耐食性、耐応力腐食割れ性のバランスに優れているが、導電率が例えばばね用りん青銅で１２％ＩＡＣＳと小さく、かつコスト的にも不利である。
【０００５】
よって、黄銅に近い価格で優れたプレス成形性、強度、弾性及び導電性を有する材料が求められている。具体的には、引張強さ６００Ｎ／mm² 以上、ばね限界値４５０Ｎ／mm²以上、導電率が２０％ＩＡＣＳ以上を有していることが必要となる。
【０００６】
このような状況に鑑み、特許文献１ではＣｕ−Ｚｎ系材料にＳｎを添加した合金を提案している。
【０００７】
しかしながら、端子の小型化に伴い、曲げ加工時のスプリングバックを抑え寸法精度を向上させるため、プレス曲げ加工部の曲げ部半径（Ｒ）は小さくなってきている。さらに、設計上、１８０°密着曲げを施し、見かけの板厚を増やす加工方法が採用される場合も多く、ますます複雑な加工へ対応する必要が出てきている。このため、従来の９０°曲げよりも厳しい１８０°曲げでの加工性が求められている。
【０００８】
また、狭ピッチコネクタの場合、端子の打ち抜きを連続して行うため、一般に曲げ加工性の良くない、板の展伸方向と直角方向の曲げ加工を施した場合の曲げ部表面が良好であることが要求される。
【０００９】
具体的には、先に示した数値範囲の引張強さ、ばね限界値、導電率を有し、さらに、板の展伸方向と直角方向の１８０°曲げ加工において、曲げ部分に割れを生じることなく加工可能な、曲げ部半径（Ｒ）と板厚（ｔ）の比Ｒ/ｔが１．０以下、好ましくはＲ/ｔが０．５以下となる条件を満足する曲げ加工性を持つ材料が望まれている。
【００１０】
【特許文献１】
特開２００１−２９４９５７（特願2000-113520）
【特許文献２】
特開２０００−８０４２８（特願平10-245192）
【特許文献３】
特開２０００−３２８１５７（特願平11-133385）
【００１１】
【発明が解決しようとする課題】
本発明は、コネクタ等の電気・電子部品用材料に要求される高い強度を有しながら曲げ加工性に優れたコネクタ等の電気・電子部品用銅合金材とその製造方法を提供するものである。
【００１２】
【課題を解決するための手段】
本発明は、コネクタ等の電気・電子部品用銅合金について、組成および材料の材料表面における特定結晶面集積度を制御することにより、即ち具体的には圧延板材の表面（以下ＮＤ面という）におけるすべり系の活動効果に着目して材料表面のＸ線回折を行い、特定方向の回折強度が所定の条件を満たすように結晶構造を制御することによって、コネクタ等の電気・電子部品用材料に要求される曲げ加工性を向上させたコネクタ等の電気・電子部品用銅合金を提供するものである。なおここでX線回折強度とは、例えばX線回折法で測定される材料の結晶方位の積分強度を意味するものである。
曲げ加工性を向上させるため、結晶面集積度を制御する手法は特許文献２，３にも示されている。しかしながら、本発明と基本組成が異なり（具体的にはＺｎ、Ｓｎの含有量が多い）、このため上記文献に記載されている最終板材表面の結晶面を制御するのみでは本発明で要求されている黄銅に近い価格で優れた曲げ加工性、強度、弾性及び導電性を有することは困難であった。
本発明では、当該組成材料の冷間加工率を変化させた際に急激に変化する｛111｝面の集積度に着目し、更に最終板材表面だけでなく中間加工材段階においても板材表面の結晶方位制御を行うことにより、安価に高強度を達成しつつ、曲げ加工性を向上させることを可能とした。この結果、本発明で要求される価格、曲げ加工性、強度、弾性及び導電性を有した材料を製造することが出来た。
【００１３】
即ち本発明は第一の態様として、Ｚｎ：１５〜４５wt％とＳｎ：０．１〜４．５wt％とを含み、残部がＣｕおよび不可避不純物からなる組成の銅基合金を被加工材として用い、冷間圧延と焼鈍とを繰り返して所定板厚の板材に加工した銅合金材であって、最終冷間加工後の材料表面のX線回折強度に基づいて下記（１）式により算定するパラメータ：
S(ND) = (I/Cu{311}+Ｉ/Cu{200}) ÷ (I/Cu{220}+I/Cu{111}) …（１）［ただし、式中の I/Cu{abc}は測定試料の{abc}面回折強度Ｉ_{abc}と標準銅試料の{abc}面回折強度Ｃｕ_{abc}の比Ｉ_{abc}/Ｃｕ_{abc}の略記である］が下記（２）式：
0.3 ≦ S(ND) ≦0.5 …（２）
を満たすようなすべり系の材料表面集積特性を有し、かつ、該板材をその展伸方向と直角方向に180°曲げ加工したときの加工可能な最小曲げ半径Ｒとその時の板材厚さｔとの比 R/t が下記（３）式：
R/t ≦ １．０ … （３）
を満たすような曲げ加工特性を有することを特徴とする主としてコネクタ等の電気・電子部品用材料として好適な銅合金材を提供するものである。ただし上記説明中、標準銅試料とは、銅粉末試料あるいはランダムな結晶方位を有する銅板を意味し、「加工可能な」とは、曲げ部表面に割れが発生しない、という意味であり（但し、「割れ」とは、割れの底が真上から観察できない、せん断帯に沿って割れた状態をいう。：日本伸銅協会技術標準ＪＢＭＡＴ３０７：１９９９参照）、曲げ半径Ｒは、曲がり部の湾曲の曲率半径であり、曲がりの内側の表面で測定した値である。「所定の板厚」とは客先の要求に対応した最終製品の形状によるものであるため数値的限定はしないが当業者には自明のことである。
本発明は第二の態様として、Ｚｎ：１５〜４５wt％とＳｎ：０．１〜４．５wt％とを必須成分として含み、更にＦe：０．０１〜３ｗｔ％、Ｎi：０．０１〜５ｗｔ％、Ｃo：０．０１〜３ｗｔ％、Ｔi：０．０１〜３ｗｔ％、Ｍg：０．０１〜２ｗｔ％、Ｚr：０．０１〜２ｗｔ％、Ｃa：０．０１〜１ｗｔ％、Ｓi：０．０１〜３ｗｔ％、Ｍn：０．０１〜１０ｗｔ％、Ｃd：０．０１〜３ｗｔ％、Ａl：０．０１〜５ｗｔ％、Ｐb：０．０１〜３ｗｔ％、Ｂi：０．０１〜３ｗｔ％、Ｂe：０．０１〜３ｗｔ％、Ｔe：０．０１〜１ｗｔ％、Ｙ：０．０１〜３ｗｔ％、Ｌa：０．０１〜３ｗｔ％、Ｃr：０．０１〜３ｗｔ％、Ｃe：０．０１〜３ｗｔ％、Ａu：０．０１〜５ｗｔ％、Ａg：０．０１〜５ｗｔ％、Ｐ：０．００５〜０．５ｗｔ％およびB：０．００１〜０．５ｗｔ％からなる群より選ばれる少なくとも１種の元素を随意的付加成分として、その総量で０．００１〜５ｗｔ％含み、残部がＣｕおよび不可避不純物からなる組成の銅基合金を被加工材として用い、冷間圧延と焼鈍とを繰り返して所定板厚の板材に加工した銅合金材であって、最終冷間加工後の材料表面のX線回折強度に基づいて下記（１）式により算定するパラメータ：
S(ND) = (I/Cu{311}+I/Cu{200}) ÷ (I/Cu{220}+I/Cu{111}) …（１）［ただし、式中の I/Cu{abc}は測定試料の{abc}面回折強度Ｉ_{abc}と標準銅試料の{abc}面回折強度Ｃｕ_{abc}の比Ｉ_{abc}/Ｃｕ_{abc}の略記である］が下記（２）式：
0.3 ≦ S(ND) ≦ 0.5 …（２）
を満たし、かつ、該板材をその展伸方向と直角方向に180°曲げ加工したときの加工可能な最小曲げ半径Ｒと板材厚さｔとの比、R/tが下記（３）式：
R/t ≦ 1.0 … （３）
を満たすことによって示される高度な曲げ加工性を有することを特徴とする主としてコネクタ等の電氣・電子部品用材料として好適な銅基合金を提供するものである。
本発明は第三の態様として、Ｚｎ：１５〜４５wt％とＳｎ：０．１〜４．５wt％とを含み、残部がＣｕおよび不可避不純物からなる組成の銅合金材、またはＺｎ：１５〜４５wt％とＳｎ：０．１〜４．５wt％とを含み、更にＦe：０．０１〜３ｗｔ％、Ｎi：０．０１〜５ｗｔ％、Ｃo：０．０１〜３ｗｔ％、Ｔi：０．０１〜３ｗｔ％、Ｍg：０．０１〜２ｗｔ％、Ｚr：０．０１〜２ｗｔ％、Ｃa：０．０１〜１ｗｔ％、Ｓi：０．０１〜３ｗｔ％、Ｍn：０．０１〜１０ｗｔ％、Ｃd：０．０１〜３ｗｔ％、Ａl：０．０１〜５ｗｔ％、Ｐb：０．０１〜３ｗｔ％、Ｂi：０．０１〜３ｗｔ％、Ｂe：０．０１〜３ｗｔ％、Ｔe：０．０１〜１ｗｔ％、Ｙ：０．０１〜３ｗｔ％、Ｌa：０．０１〜３ｗｔ％、Ｃr：０．０１〜３ｗｔ％、Ｃe：０．０１〜３ｗｔ％、Ａu：０．０１〜５ｗｔ％、Ａg：０．０１〜５ｗｔ％、Ｐ：０．００５〜０．５ｗｔ％および B：０．００１〜０．５ｗｔ％からなる群より選ばれる少なくとも１種の元素を、その総量で０．００１〜５ｗｔ％含み、残部がＣｕおよび不可避不純物からなる組成の銅合金材を被加工材として用い、冷間圧延と焼鈍とを繰り返して所定板厚の板材に加工する銅合金材の製造方法であって、その製造工程において最終冷間加工前の圧延加工である中延加工の実施後、板材表面のX線回折強度を測定し、その強度に基づいて下記（１）式により算定するパラメータ：
S(ND) = (I/Cu{311}+I/Cu{200}) ÷ (I/Cu{220}+I/Cu{111}) …（１）［ただし、式中の I/Cu{abc}は測定試料の{abc}面回折強度Ｉ_{abc}と標準銅試料の{abc}面回折強度Ｃｕ_{abc}の比：Ｉ_{abc}/Ｃｕ_{abc}の略記である］の値を検定して、S(ND)が下記（４）式：
S(ND) ≦ 0.3 …（４）
を満たすように冷間圧延と焼鈍とが行われたことを確認し、次いで最終冷間加工を行い、かつ該最終冷間加工後の材料表面のX線回折強度により算定する上記（１）式のパラメータS(ND)が下記（２）式：
0.3 ≦ S(ND) ≦ 0.5 …（２）
を満たしていることを確認して最終冷間加工を終結し最終製品板材を得ることからなる主としてコネクタ等の電氣・電子部品用材料として好適な銅合金材の製造方法を提供するものである。
本発明は第四に、最終冷間加工前の圧延加工である中延圧延終了後の材料表面のX線回折強度を測定し、そのＸ線回折強度に基づいて（１）式により算定するパラメータ：
S(ND) = (I/Cu{311}+I/Cu{200}) ÷ (I/Cu{220}+I/Cu{111}) …（１）［ただし、式中の I/Cu{abc}は測定試料の{abc}面回折強度Ｉ_{abc}と標準銅試料の{abc}面回折強度Ｃｕ_{abc}の比：Ｉ_{abc}/Ｃｕ_{abc}の略記である］が下記（５）式：
S(ND) ≦ 0.3 …（５）
を満たすことを確認して中延圧延を終結する工程に加えて、最終冷間加工前の焼鈍である中延焼鈍実施後の材料表面のX線回折強度を測定し、そのX線回折強度に基づいて上記（１）式により算定するパラメータS(ND)が下記（４）式：
S(ND) ≦ 0.8 …（４）
を満たすことを確認して中延焼鈍を終結する工程を更に含む前記第三の態様に記載の主としてコネクタ等の電氣・電子部品用材料として好適な銅合金材の製造方法を提供するものである。
本発明は第五の態様として、最終冷間加工後の圧延合金の結晶粒径が５μｍ以下となるように中延圧延、中延焼鈍および最終冷間加工の処理条件を制御することをも重要な製造条件の一つとして含むことを特徴とする前記第三または第四の態様に記載の主としてコネクタ等の電氣・電子部品用材料として好適な銅合金材の製造方法を提供するものである。
本発明は第六の態様として、最終冷間加工後の圧延合金をばね限界値がピークになる熱処理温度よりも高い温度で熱処理する工程をさらに含むことを特徴とする前記第三乃至第五の態様として記載のコネクタ等電氣・電子部品用材料として好適な銅合金材の製造方法を提供するものである。ここに、ばね限界値がピークになる熱処理温度とは、最終冷間加工後の材料を低温焼鈍した後に測定したばね限界値の値が最大となるような低温焼鈍の温度を意味する。熱処理温度については、最終圧延加工条件によって最適な熱処理温度は変動するが当業者は目的に応じ適宜決定できる。例えば、２００〜６００℃（時間：５秒〜１８０分）が通常行っている低温焼鈍条件になる。
【００１４】
【発明の実施の形態】
以下、本発明の内容をさらに具体的に説明する。そこでまず、本発明銅合金材における合金成分元素の含有量限定理由につき説明する。
【００１５】
Ｚｎ：Ｚｎの添加により強度、ばね性が向上し、かつＣｕより安価であるため多量に添加することが望ましいが、４５wt％を越えると曲げ加工性、耐食性、耐応力腐食割れ性、めっき性、はんだ付性が低下する。また、製造工程中においてβ相の形成量が多くなり、冷間加工性が低下することに加え、途中の圧延・焼鈍工程での結晶方位・結晶粒径の制御が困難になる。また、１５wt％より少ないと強度、ばね性が不足し、安価なＺｎが少なくコスト的にも不利になる。したがって、Ｚｎは、１５〜４５wt％の範囲であれば良い。好ましい範囲としては２０〜３５wt％である。更に好ましい範囲としては、２３〜３０wt％である。この範囲であると、溶解鋳造時の凝固組織と熱間圧延との兼ね合いで生じる熱間割れを抑制できる。
【００１６】
Ｓｎ：ＳｎはＺｎの共存下で微量であっても強度，弾性をはじめとした機械的特性を向上させる効果がある。さらにＳｎめっき等、Ｓｎを表面処理した材料の再利用の点からも添加元素として含有するのが好ましい。しかし、Ｓｎ含有量が増すと導電率が急激に低下し、また熱間加工性も低下する。このため、４．５wt％を越えない範囲でなければならない。また、０．１ wt％より少ないと機械的特性を向上させる効果が望めない。したがって、Ｓｎは、０．１〜４．５wt％の範囲であれば良い。好ましい範囲としては、０．３〜３．０wt％である。更に好ましい範囲としては０．４〜２．０wt％である。この範囲であると、溶解鋳造時の凝固組織と熱間圧延との兼ね合いで生じる熱間割れを抑制できる。
また、後述する材料表面の結晶方位についても、Ｚｎが１５％〜４５wt％、Ｓｎが０．１％〜４．５wt％の範囲であれば、曲げに対して割れの生じ難い方位である｛100｝面が多く材料表面に集積し易く、曲げ加工性が向上する。Ｚｎ量、Ｓｎ量が上記範囲より少ないと、｛100｝面の集積度が少なくなり、曲げ加工性が低下しやすい。また、上記の範囲より多い場合でも、マトリクス中に冷間加工性に乏しいβ相が発生し易くなるため、曲げ加工性は低下する。
【００１７】
さらに、第３添加元素として、Ｆe：０．０１〜３ｗｔ％、Ｎi：０．０１〜５ｗｔ％、Ｃo：０．０１〜３ｗｔ％、Ｔi：０．０１〜３ｗｔ％、Ｍg：０．０１〜２ｗｔ％、Ｚr：０．０１〜２ｗｔ％、Ｃa：０．０１〜１ｗｔ％、Ｓi：０．０１〜３ｗｔ％、Ｍn：０．０１〜１０ｗｔ％、Ｃd：０．０１〜３ｗｔ％、Ａl：０．０１〜５ｗｔ％、Ｐb：０．０１〜３ｗｔ％、Ｂi：０．０１〜３ｗｔ％、Ｂe：０．０１〜３ｗｔ％、Ｔe：０．０１〜１ｗｔ％、Ｙ：０．０１〜３ｗｔ％、Ｌa：０．０１〜３ｗｔ％、Ｃr：０．０１〜３ｗｔ％、Ｃe：０．０１〜３ｗｔ％、Ａu：０．０１〜５ｗｔ％、Ａg：０．０１〜５ｗｔ％、Ｐ：０．００５〜０．５ｗｔ％、B：０．００１〜０．５ｗｔ％のうち少なくとも１種以上の元素をその総量が０．００１〜５ｗｔ％となる範囲で含んでも良い。
【００１８】
これらは、Cuマトリックス中に固溶または析出して化合物を形成することで、曲げ加工性に影響を与えずに強度、導電率、熱間加工性を向上させる効果を有している。ただし、各元素の含有範囲からはずれると所望とする効果が得られないか、曲げ加工性を劣化させる。または、熱間加工性、導電率、コスト面等で不利となる。
【００１９】
次に、本発明銅合金材における結晶方位制御理由につき説明する。
曲げ加工に際して、材料の曲げ変形時に生じる表面の肉引け、破断を抑えるためには、曲げ加工時に材料表面で働くすべり系の多い結晶面を板材表面に優先的に発生させ、局部的なくびれの発生を抑制することが重要である。
【００２０】
FCC（面心立方格子）の結晶構造を持つＣｕ系の多結晶材料は、すべり面｛111｝とすべり方向＜110＞の組み合わせ、即ち、１２個のすべり系｛111｝＜110＞を有し、変形に際し１個以上のすべり系が活動する（ここで、｛｝は等価な面を一括して表したもの、＜＞は等価な方向（方位）を一括して表したものである）。曲げ加工変形の場合、すべり系が多く活動すれば肉引け、クラックの発生を抑制することができる。
【００２１】
板材表面をND面として、４種類の面、｛110｝面，｛111｝面，｛311｝面，｛100｝面に注目すると、曲げ加工変形に際し、12個のすべり系のうち8個のすべり系が活動可能な｛100｝面を多く表面に集積させることで最も曲げ加工性を向上させ得る。次いで｛311｝面、｛111｝面，逆に曲げ加工変形に際して活動可能なすべり系個数の少ない｛110｝面が多く集積した場合、曲げ加工性が劣化する。
【００２２】
具体的には、曲げ加工の際、曲げ部表面のしわに対して応力が集中し、肉引けが大きくなり、クラックに至る。
【００２３】
ここで、銅基合金のようにFCC（面心立方格子）の結晶構造を有する金属の場合、Ｘ線回折では｛110｝面、｛111｝面、｛311｝面、｛100｝面の回折強度は各々Ｉ_｛ ₂₂₀ _｝、Ｉ_｛ ₁₁₁ _｝，Ｉ_｛ ₃₁₁ _｝，Ｉ_｛ ₂₀₀ _｝として生じる。
【００２４】
以上を考慮した上で、従来の問題を解決すべく鋭意研究した結果、｛220｝面の回折強度Ｉ_｛ ₂₂₀ _｝，｛111｝面の回折強度Ｉ_｛ ₁₁₁ _｝，｛311｝面の回折強度Ｉ_｛ ₃₁₁ _｝，｛200｝面の回折強度Ｉ_｛ ₂₀₀ _｝を測定し、
S(ND)=(I/Cu{311}+I/Cu{200})÷(I/Cu{220}+I/Cu{111})・・・（１）
I/Cu{abc}：［測定試料の{abc}面回折強度Ｉ_{abc}と標準銅試料の{abc}面回折強度Ｃｕ_{abc}の比：Ｉ_{abc}/Ｃｕ_{abc}を意味する。］なるパラメータS(ND)を指標に組織制御する。具体的には工程における焼鈍・圧延条件を決定することで曲げ加工性の向上を成し得た。
【００２５】
すなわち最終冷間加工後の板材表面のS(ND)を（１）式により求め、S(ND) ≧ 0.3の条件が満たされるような焼鈍・圧延処理を行ったときは、R/t = 1.0以下で180°曲げ加工を施した後の曲げ部表面にクラックが無く、良好な曲げ部表面を得ることができた。一方、S(ND) ＜ 0.3のときは、曲げ部にクラックが発生した。S(ND) ＞ 0.5の場合、曲げ加工性は満足できるが、引張強さをはじめとする他の特性を満足することができないことがわかった。
【００２６】
次に、本発明に係る製造条件の限定理由につき説明する。
最終冷間加工後板材において曲げ加工性を向上するために必要な、結晶粒径が小さく均一な組織を有する中延焼鈍後材を得るためには、中延圧延後の材料表面において（１）式によるパラメータS(ND)が0.30以下となるような圧延加工を行うことが好ましい。S(ND)が0.30を越えると、中延焼鈍において前述の組織を得ることが出来る温度領域が狭くなり、結晶粒径の制御が難しい。
【００２７】
さらに、中延焼鈍後の材料表面において（１）式によるパラメータS(ND)を0.80以下、結晶粒径を５μmとなるように中延焼鈍条件を制御すれば最終冷間加工後板材において高い強度を有しつつ、曲げ加工性を向上できる。S(ND)が0.80を越えるか、あるいは結晶粒径が５μｍを越えると、必要な強度特性を得るための最終冷間圧延加工率が大きくなり、X線回折強度によって決定される（１）式に示すパラメータが（２）式に示す範囲を下回る。このため、最終冷間加工後板材の曲げ加工性が低下する上、経済的に不利になる。
【００２８】
この後、最終冷間加工後材料において（１）式によるパラメータS(ND)が、0.3≦ S(ND) ≦ 0.5を満たすように冷間加工率を制御すれば高い強度を有しつつ、曲げ加工性に優れた材料を製造することができる。
【００２９】
さらに、２００〜６００℃の温度で５秒〜１８０分間熱処理する。この熱処理により材料の曲げ加工性を向上させ、さらにばね限界値、耐応力腐食割れ性、導電率を向上させることができる。２００℃未満の温度ではこのような効果が充分でなく、６００℃を超える温度では急速に強度が低下することに加え、材料表面の結晶回折強度の変化、結晶粒の粗大化が生じる。また時間については、５秒間〜１８０分間が好ましい。処理時間が短すぎると上記の効果が十分でなく、長すぎると経済的に不利になる。
【００３０】
また、ばね限界値がピークになる熱処理温度よりも高い温度で熱処理することで曲げ加工性、耐応力腐食割れ性をさらに向上させることができる。ただし、熱処理温度が高すぎると引張強さ、ばね限界値が急激に低下するため、ばね限界値がピーク値の７０から１００％の間となるような熱処理条件が望ましい。
【００３１】
以上のようにして成分の範囲、板材表面の結晶方位、製造条件を限定することで曲げ加工性（Ｒ/ｔ≦1.0 の１８０°曲げにもクラック発生無し）を満足しつつ、さらにコネクタ材として必要な諸特性、具体的には引張強さ６００Ｎ／mm² 以上、導電率が２０％ＩＡＣＳ以上を満足するコネクタ用銅基合金を製造できる。
【００３２】
次に本発明の実施の形態を実施例により説明する。
【００３３】
【実施例】
［実施例１］
表１に化学成分（wt％）を示す銅合金Ｎｏ．１〜１８を高周波誘導溶解炉を用いて溶製し、４０×４０×１５０（mm）の鋳塊に鋳造した。ただし、溶解鋳造時の雰囲気はＡｒガス雰囲気とし、鋳造後直ちに水冷した。
【００３４】
その後、各鋳塊を熱間圧延後、冷間圧延と焼鈍を繰り返し、板材表面の式（１）に示すS(ND)が0.2＜S(ND)＜0.35となるような中延圧延（最終冷間加工前の圧延加工）を行った。
【００３５】
上記のようにして得られたNo.１８までの板材について300〜550℃×1時間の熱処理を実施した。なお、熱処理後の板材の結晶粒径は5〜15μmであり、板材表面（ND面）についてX線回折を行い、式（１）に示すS(ND)を測定した結果、0.55＜S(ND)＜0.85であった。上記のように得られた熱処理材を厚さ0.25 mmまで冷間圧延した後、各温度条件で３０分間の焼鈍を行い、酸洗を施したものを試験材とした。
【００３６】
ここで、Ｘ線回折強度の測定条件は以下の通りである。
管球：Mo（Ｃｕ）、管電圧：40ｋＶ、管電流：30ｍＡ、サンプリング幅：0.020°、モノクロメーター使用、試料ホルダー：Ａｌ
なお、Ｘ線回折測定条件は、上記条件に限定されるものでなく、試料の種類によって適宜変更される。
【００３７】
このとき得られた試験材のうち、代表としてCu‐25.21wt%Zn‐0.78wt%Sn の中延圧延後のS(ND)が0.30、中延焼鈍後のS(ND)が0.72、結晶粒径が5μmの材料について最終冷間加工率を変更し、得られた試験材と標準CuサンプルのX線回折強度の積分強度比、S(ND)を測定した例を図１に示す。図１の例では、冷間加工率の増加と共に、｛220｝面の集積度は増加、｛311｝面，｛200｝面の集積度は減少している。
【００３８】
このように材料表面における各結晶面の集積度判定基準となるS(ND)に基づいて冷間加工率を決定することで、曲げ加工性に優れ、かつ高強度の材料を安定かつ確実に製造することができる。
【００３９】
以上のようにして得られた試験材を用いてビッカース硬さ、引張強さ、ヤング率、ばね限界値および導電率を測定すると共に、曲げ加工性を調査した。ビッカース硬さ、引張強さ、ヤング率、ばね限界値および導電率の測定は、それぞれＪＩＳ−Ｚ―２２４４、ＪＩＳ−Ｚ―２２４１、ＪＩＳ−Ｈ―３１３０、ＪＩＳ−Ｈ―０５０５に従った。
【００４０】
曲げ加工性は、展伸方向と直角方向に採取した試料について１８０゜曲げ試験（ＪＩＳＺ２２４１、Ｒ＝0.25 mm 、Ｗ＝2.0 mm）を行い、内曲げ半径Rと板厚tの比をＲ/ｔとして、中央部の山表面で割れの発生しなかった最小のＲ/ｔで評価した。
【００４１】
【表１】

【００４２】
表１に示した結果から、本発明に係るＮｏ．１〜８の銅合金は、曲げ加工性が良好であり、なおかつ引張強さ、導電率のバランスに優れている。したがって、コネクタ等の電気・電子部品用材料として非常に優れた特性を有する銅合金である。
また、第３元素を添加した本発明合金Ｎｏ．６〜８は、強度あるいは導電率の向上が確認されている。
【００４３】
これに対して、Ｚｎ、Ｓｎ各含有量が本発明で規定するより少ない比較合金Ｎｏ．９，Ｎｏ．１０は、曲げ加工性・引張強さに劣り、Ｚｎ、Ｓｎ各含有量が本発明で規定するより多い比較合金Ｎｏ．１１，Ｎｏ．１２は曲げ加工性に劣っている。
【００４４】
また、最終冷間加工後の材料表面の結晶方位パラメータS(ND)が（２）式で規定するより小さい比較合金Ｎｏ.１３は引張強さ、ばね限界値は本発明合金と同等だが、曲げ加工性に劣り、S(ND)が（２）式で規定するより大きい比較合金Ｎｏ．１４は曲げ加工性が劣っている上、引張強さ、ばね限界値が低下している。
【００４５】
中延焼鈍前、中延圧延後の結晶方位パラメータS(ND)が（５）式で規定するより大きい値を示す試料である比較合金Ｎｏ．１５、中延焼鈍後の結晶方位パラメータS(ND)が（４）式で規定するより大きく、結晶粒径が１０μｍである比較合金Ｎｏ．１６はいずれも曲げ加工性に劣っている。
【００４６】
比較合金Ｎｏ．１７は冷間加工後、熱処理を行わなかった試料であるが、曲げ加工性・ばね限界値が大きく劣っている。
【００４７】
比較合金Ｎｏ．１８，Ｎｏ．１９は市販の黄銅１種（Ｃ２６００−ＥＨ）、りん青銅２種（Ｃ５１９１−ＥＨ）についてビッカース硬さ、引張強さ、ヤング率、ばね限界値、導電率および曲げ加工性を調査した結果である。
【００４８】
本発明の銅合金は、従来の代表的なコネクタ等の電気・電子部品用材料である黄銅一種に比較して曲げ加工性、強度が向上していることがわかる。りん青銅に比較しても、曲げ加工性，強度，導電率に優れている。さらにコスト面でも成分と製造工程から優れているといえる。したがって、本発明合金は従来の黄銅、りん青銅に比較しても十分に優れているといえる。
【００４９】
【発明の効果】
以上の実施例から明らかなように、本発明に係る銅基合金または本発明方法によって得られた銅合金材料は、従来の黄銅やりん青銅等に比較して、成形加工性が良好でありかつ強度，導電率のバランスをはじめ耐環境性，耐熱性等に優れるため、安価なコネクタ等の電気・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】 Cu-25.21wt%Zn-0.78wt%Snの組成をもつ被加工材であって中延圧延後のS(ND)が0.30、中延焼鈍後のS(ND)が0.72、結晶粒径が５μｍの材料について最終冷間加工率を変更して得られた試験材と標準CuサンプルのＸ線回折強度の積分強度比およびS(ND)の測定結果を示す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a copper alloy material used as a material for electrical and electronic parts such as connectors. More specifically, in addition to excellent press formability, strength, elasticity, and conductivity, it is particularly inexpensive and excellent in bending workability. The present invention relates to a copper alloy material for electric / electronic parts and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, with the development of electronics, the electrical wiring of various machines has become complicated and highly integrated, and accordingly, the demand for copper products used as materials for manufacturing electrical and electronic parts such as connectors has increased.
[0003]
In addition, electrical and electronic parts such as connectors are required to have light weight, high reliability, and low cost. Therefore, in order to meet these requirements, copper alloy materials for electrical and electronic parts such as connectors are thinned, the terminal width is narrowed, and they are pressed into a complicated shape, so that press formability, strength, elasticity and conductivity are reduced. Must be good.
[0004]
Conventionally, brass, phosphor bronze, and the like have been generally used as connector materials. Brass is used as a low-cost material, but the tensile strength is 600 N / mm even if the quality is EH.² In addition, it is inferior in corrosion resistance and stress corrosion cracking resistance. Also, 600N / mm for quality SH / ESH²Although it has the above high strength, bending workability is inferior and it cannot cope with complicated processing. Phosphor bronze has an excellent balance of strength, corrosion resistance, and stress corrosion cracking resistance, but its conductivity is small, for example, 12% IACS for spring bronze, and is disadvantageous in terms of cost.
[0005]
Therefore, a material having excellent press formability, strength, elasticity and conductivity at a price close to that of brass is required. Specifically, tensile strength 600N / mm² Above, spring limit value 450N / mm²As described above, the conductivity needs to be 20% IACS or more.
[0006]
In view of such a situation, Patent Document 1 proposes an alloy in which Sn is added to a Cu—Zn-based material.
[0007]
However, with the miniaturization of the terminals, the radius (R) of the bending portion of the press bending portion has been reduced in order to suppress the spring back during bending and improve the dimensional accuracy. In addition, there are many cases where a machining method is employed in which 180 ° contact bending is applied to increase the apparent plate thickness, and it is necessary to cope with increasingly complicated machining. For this reason, the workability in 180 degree | times bending severer than the conventional 90 degree bending is calculated | required.
[0008]
Also, in the case of narrow pitch connectors, since the terminal is continuously punched, generally the bending workability is not good, and the surface of the bent part is good when bending in the direction perpendicular to the extending direction of the plate is performed. Is required.
[0009]
Specifically, it has the tensile strength, spring limit value, and electrical conductivity within the numerical ranges shown above, and also causes cracks in the bent portion in 180 ° bending processing in the direction perpendicular to the plate extending direction. A material having bending workability that satisfies the condition that the ratio R / t of the bending portion radius (R) to the plate thickness (t) is 1.0 or less, preferably R / t is 0.5 or less. Is desired.
[0010]
[Patent Document 1]
JP 2001-294957 (Japanese Patent Application No. 2000-113520)
[Patent Document 2]
JP 2000-80428 (Japanese Patent Application No. 10-245192)
[Patent Document 3]
JP 2000-328157 (Japanese Patent Application No. 11-133385)
[0011]
[Problems to be solved by the invention]
The present invention provides a copper alloy material for electrical and electronic parts such as connectors and the like, which has high strength required for materials for electrical and electronic parts such as connectors and has excellent bending workability, and a method for producing the same. .
[0012]
[Means for Solving the Problems]
The present invention relates to a copper alloy for electrical and electronic parts such as connectors by controlling the specific crystal plane integration degree on the material surface of the composition and material, that is, specifically on the surface of the rolled plate (hereinafter referred to as ND plane). Demand for materials for electrical and electronic parts such as connectors by performing X-ray diffraction on the surface of materials focusing on the activity effect of the slip system and controlling the crystal structure so that the diffraction intensity in a specific direction satisfies a specified condition The present invention provides a copper alloy for electrical and electronic parts such as a connector with improved bending workability. Here, the X-ray diffraction intensity means, for example, the integrated intensity of the crystal orientation of the material measured by the X-ray diffraction method.
Methods for controlling the degree of crystal plane integration in order to improve bending workability are also disclosed in

Patent Documents

2 and 3. However, the basic composition is different from that of the present invention (specifically, the Zn and Sn contents are large). Therefore, it is required in the present invention only to control the crystal plane of the surface of the final plate described in the above document. It was difficult to have excellent bending workability, strength, elasticity and conductivity at a price close to that of brass.
In the present invention, attention is paid to the degree of integration of {111} faces that change rapidly when the cold working rate of the composition material is changed, and further, the crystal on the surface of the plate material is not only at the final plate surface but also at the intermediate work material stage. By performing orientation control, it was possible to improve bending workability while achieving high strength at a low cost. As a result, a material having the price, bending workability, strength, elasticity and conductivity required in the present invention could be manufactured.
[0013]
That is, the present invention uses, as a first embodiment, a copper-based alloy containing Zn: 15 to 45 wt% and Sn: 0.1 to 4.5 wt%, with the balance being Cu and inevitable impurities as the work material. A copper alloy material that has been processed into a plate material having a predetermined thickness by repeatedly performing cold rolling and annealing, and is calculated by the following equation (1) based on the X-ray diffraction intensity of the material surface after the final cold processing :
S (ND) = (I / Cu {311} + I / Cu {200}) ÷ (I / Cu {220} + I / Cu {111}) (1) [where I / Cu { abc} is the {abc} plane diffraction intensity I of the measurement sample_{abc}And {abc} plane diffraction intensity Cu of standard copper samples_{abc}Ratio I_{abc}/ Cu_{abc}Is an abbreviation of the following formula (2):
0.3 ≤ S (ND) ≤ 0.5 (2)
The minimum bend radius R that can be machined when the plate material is bent 180 ° in the direction perpendicular to the extending direction, and the thickness t of the plate material at that time. The ratio R / t of the following equation (3):
R / t ≦ 1.0 (3)
The present invention provides a copper alloy material suitable as a material for electrical and electronic parts such as connectors, which is characterized by having a bending property satisfying the above. However, in the above description, the standard copper sample means a copper powder sample or a copper plate having a random crystal orientation, and “processable” means that cracks do not occur on the surface of the bent portion (however, “Crack” means a state in which the bottom of the crack cannot be observed from directly above and is broken along a shear band .: Refer to Japan Copper and Brass Association Technical Standard JBMA T307: 1999), bending radius R is the curvature of the bent portion It is a value measured on the inner surface of the bend. The “predetermined plate thickness” is based on the shape of the final product corresponding to the customer's request, and is not limited numerically, but is obvious to those skilled in the art.
As a second aspect of the present invention, Zn: 15 to 45 wt% and Sn: 0.1 to 4.5 wt% are included as essential components, Fe: 0.01 to 3 wt%, Ni: 0.01 to 5 wt% %, Co: 0.01 to 3 wt%, Ti: 0.01 to 3 wt%, Mg: 0.01 to 2 wt%, Zr: 0.01 to 2 wt%, Ca: 0.01 to 1 wt%, Si: 0 0.01 to 3 wt%, Mn: 0.01 to 10 wt%, Cd: 0.01 to 3 wt%, Al: 0.01 to 5 wt%, Pb: 0.01 to 3 wt%, Bi: 0.01 to 3 wt% , Be: 0.01-3 wt%, Te: 0.01-1 wt%, Y: 0.01-3 wt%, La: 0.01-3 wt%, Cr: 0.01-3 wt%, Ce: 0. 01-3 wt%, Au: 0.01-5 wt%, Ag: 0.01-5 wt%, P: 0.005-0.5 wt% and B: 0.00 A copper-based alloy having a composition containing at least one element selected from the group consisting of ˜0.5 wt% as an optional additional component and a total amount of 0.001 to 5 wt%, with the balance being Cu and inevitable impurities. A copper alloy material used as a material and processed into a plate material having a predetermined plate thickness by repeatedly performing cold rolling and annealing, and based on the X-ray diffraction intensity of the material surface after the final cold processing, according to the following formula (1) Parameters to calculate:
S (ND) = (I / Cu {311} + I / Cu {200}) ÷ (I / Cu {220} + I / Cu {111}) (1) [where I / Cu { abc} is the {abc} plane diffraction intensity I of the measurement sample_{abc}And {abc} plane diffraction intensity Cu of standard copper samples_{abc}Ratio I_{abc}/ Cu_{abc}Is an abbreviation of the following formula (2):
0.3 ≦ S (ND) ≦ 0.5 (2)
And the ratio of the minimum bending radius R that can be processed and the thickness t of the plate when the plate is bent 180 ° in a direction perpendicular to the extending direction, R / t is the following formula (3):
R / t ≦ 1.0 (3)
The present invention provides a copper-based alloy suitable mainly as a material for electrical appliances and electronic parts such as connectors, characterized by having a high degree of bending workability shown by satisfying the above.
As a third aspect of the present invention, a copper alloy material having a composition containing Zn: 15 to 45 wt% and Sn: 0.1 to 4.5 wt%, with the balance being Cu and inevitable impurities, or Zn: 15 to 45 wt% And Sn: 0.1 to 4.5 wt%, Fe: 0.01 to 3 wt%, Ni: 0.01 to 5 wt%, Co: 0.01 to 3 wt%, Ti: 0.01 to 3 wt%, Mg: 0.01-2 wt%, Zr: 0.01-2 wt%, Ca: 0.01-1 wt%, Si: 0.01-3 wt%, Mn: 0.01-10 wt%, Cd: 0.01 to 3 wt%, Al: 0.01 to 5 wt%, Pb: 0.01 to 3 wt%, Bi: 0.01 to 3 wt%, Be: 0.01 to 3 wt%, Te: 0.01 to 1 wt% %, Y: 0.01 to 3 wt%, La: 0.01 to 3 wt%, Cr: 0.01 to 3 wt%, Ce: 0.01 to 3 wt% At least one element selected from the group consisting of Au: 0.01-5 wt%, Ag: 0.01-5 wt%, P: 0.005-0.5 wt%, and B: 0.001-0.5 wt% Is processed into a plate material having a predetermined thickness by repeatedly performing cold rolling and annealing using a copper alloy material having a composition of 0.001 to 5 wt% in total and the balance being Cu and inevitable impurities. A method for producing a copper alloy material, in which the X-ray diffraction intensity on the surface of the plate material is measured after performing the rolling process, which is a rolling process before the final cold working, and the following (1) Parameters calculated by the formula:
S (ND) = (I / Cu {311} + I / Cu {200}) ÷ (I / Cu {220} + I / Cu {111}) (1) [where I / Cu { abc} is the {abc} plane diffraction intensity I of the measurement sample_{abc}And {abc} plane diffraction intensity Cu of standard copper samples_{abc}Ratio: I_{abc}/ Cu_{abc}Is abbreviated to], and S (ND) is the following formula (4):
S (ND) ≤ 0.3 (4)
(1) The above formula (1) is used to confirm that cold rolling and annealing have been performed so as to satisfy the condition, and then the final cold working is performed, and the material surface after the final cold working is calculated based on the X-ray diffraction intensity Parameter S (ND) of the following equation (2):
0.3 ≦ S (ND) ≦ 0.5 (2)
The present invention provides a method for producing a copper alloy material that is suitable mainly as a material for electrical appliances and electronic parts such as connectors and the like.
Fourthly, the present invention measures the X-ray diffraction intensity of the surface of the material after completion of the intermediate rolling, which is a rolling process before the final cold working, and a parameter calculated by the formula (1) based on the X-ray diffraction intensity:
S (ND) = (I / Cu {311} + I / Cu {200}) ÷ (I / Cu {220} + I / Cu {111}) (1) [where I / Cu { abc} is the {abc} plane diffraction intensity I of the measurement sample_{abc}And {abc} plane diffraction intensity Cu of standard copper samples_{abc}Ratio: I_{abc}/ Cu_{abc}Is an abbreviation of the following formula (5):
S (ND) ≤ 0.3 (5)
In addition to the process of confirming that the intermediate rolling is completed and measuring the X-ray diffraction intensity of the material surface after the intermediate rolling annealing, which is the annealing before the final cold working, based on the X-ray diffraction intensity The parameter S (ND) calculated by the above equation (1) is the following equation (4):
S (ND) ≦ 0.8 (4)
The present invention provides a method for producing a copper alloy material suitable mainly as a material for electrical appliances and electronic parts such as connectors as described in the third aspect, which further includes a step of confirming that the intermediate annealing is terminated and further terminating the intermediate annealing.
In the fifth aspect of the present invention, it is also important to control the processing conditions of intermediate rolling, intermediate annealing and final cold working so that the grain size of the rolled alloy after final cold working is 5 μm or less. The present invention provides a method for producing a copper alloy material suitable mainly as a material for electrical appliances and electronic parts such as connectors as described in the third or fourth aspect, which is included as one of the conditions.
The present invention, as a sixth aspect, further includes the step of heat-treating the rolled alloy after the final cold working at a temperature higher than the heat treatment temperature at which the spring limit value reaches a peak. The present invention provides a method for producing a copper alloy material suitable as a material for electrical appliances and electronic parts such as a connector described as an aspect. Here, the heat treatment temperature at which the spring limit value reaches a peak means a low temperature annealing temperature at which the value of the spring limit value measured after low-temperature annealing of the material after the final cold working is maximized. Regarding the heat treatment temperature, the optimum heat treatment temperature varies depending on the final rolling process conditions, but those skilled in the art can appropriately determine the heat treatment temperature according to the purpose. For example, 200 to 600 ° C. (time: 5 seconds to 180 minutes) is a normal low temperature annealing condition.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the content of the present invention will be described more specifically. First, the reason for limiting the content of alloy component elements in the copper alloy material of the present invention will be described.
[0015]
Zn: Addition of Zn improves strength and springiness and is cheaper than Cu, so it is desirable to add a large amount, but if it exceeds 45 wt%, bending workability, corrosion resistance, stress corrosion cracking resistance, plating property, Solderability decreases. In addition, the amount of β phase formed during the manufacturing process is increased, and cold workability is lowered. In addition, it becomes difficult to control the crystal orientation and the crystal grain size during the rolling / annealing process. On the other hand, if it is less than 15 wt%, the strength and springiness are insufficient, and there is little inexpensive Zn, which is disadvantageous in terms of cost. Therefore, Zn should just be the range of 15-45 wt%. A preferred range is 20 to 35 wt%. A more preferable range is 23 to 30 wt%. Within this range, it is possible to suppress hot cracking that occurs due to the balance between the solidification structure during hot casting and hot rolling.
[0016]
Sn: Sn has an effect of improving mechanical properties such as strength and elasticity even in a small amount in the presence of Zn. Furthermore, it is preferable to contain it as an additional element also from the point of reuse of the material which surface-treated Sn, such as Sn plating. However, when the Sn content is increased, the conductivity is drastically lowered and the hot workability is also lowered. For this reason, it must be in a range not exceeding 4.5 wt%. On the other hand, if it is less than 0.1 wt%, the effect of improving the mechanical properties cannot be expected. Therefore, Sn should just be the range of 0.1-4.5 wt%. A preferable range is 0.3 to 3.0 wt%. A more preferable range is 0.4 to 2.0 wt%. Within this range, it is possible to suppress hot cracking that occurs due to the balance between the solidification structure during hot casting and hot rolling.
Also, the crystal orientation of the material surface, which will be described later, is an orientation in which cracking hardly occurs with respect to bending if Zn is in the range of 15% to 45 wt% and Sn is in the range of 0.1% to 4.5 wt% {100 } There are many surfaces and it is easy to accumulate on the surface of the material, so that bending workability is improved. When the amount of Zn and the amount of Sn are less than the above ranges, the degree of integration of {100} faces decreases, and the bending workability tends to be lowered. Even when the amount is larger than the above range, a β phase having poor cold workability is likely to be generated in the matrix, so that the bending workability is lowered.
[0017]
Further, Fe: 0.01-3 wt%, Ni: 0.01-5 wt%, Co: 0.01-3 wt%, Ti: 0.01-3 wt%, Mg: 0.01- 2 wt%, Zr: 0.01-2 wt%, Ca: 0.01-1 wt%, Si: 0.01-3 wt%, Mn: 0.01-10 wt%, Cd: 0.01-3 wt%, Al: 0.01-5 wt%, Pb: 0.01-3 wt%, Bi: 0.01-3 wt%, Be: 0.01-3 wt%, Te: 0.01-1 wt%, Y: 0.01-3 wt% %, La: 0.01-3 wt%, Cr: 0.01-3 wt%, Ce: 0.01-3 wt%, Au: 0.01-5 wt%, Ag: 0.01-5 wt%, P: 0 0.005 to 0.5 wt%, B: 0.001 to 5 wt% of at least one element of 0.001 to 0.5 wt% It may include in the range of.
[0018]
These have the effect of improving strength, electrical conductivity, and hot workability without affecting bending workability by forming a compound by solid solution or precipitation in a Cu matrix. However, if it deviates from the content range of each element, a desired effect cannot be obtained or bending workability is deteriorated. Or, it is disadvantageous in hot workability, conductivity, cost, and the like.
[0019]
Next, the reason for controlling the crystal orientation in the copper alloy material of the present invention will be described.
In order to suppress the shrinkage and breakage of the surface that occurs during bending deformation of the material during bending, a crystal surface with many slip systems that acts on the surface of the material during bending is preferentially generated on the surface of the plate material, and local necking is prevented. It is important to suppress the occurrence.
[0020]
A Cu-based polycrystalline material having a FCC (face-centered cubic lattice) crystal structure has a combination of a slip surface {111} and a slip direction <110>, that is, 12 slip systems {111} <110>. At the time of deformation, one or more slip systems are active (where {} represents an equivalent surface in a lump, and <> represents an equivalent direction (orientation) in a lump). In the case of bending deformation, if a lot of slip system is active, it is possible to suppress the occurrence of cracking and cracking.
[0021]
Focusing on the four types of surfaces, {110} surface, {111} surface, {311} surface, and {100} surface, with the surface of the plate material as the ND surface, 8 out of 12 slip systems are subjected to bending deformation. Bending workability can be improved most by accumulating a large number of {100} surfaces on which a slip system can be active. Next, when a large amount of {311} planes, {111} planes, and conversely {110} planes with a small number of slip systems that can be active during bending deformation, bending workability deteriorates.
[0022]
Specifically, during bending, stress concentrates on the wrinkles on the surface of the bent part, resulting in increased shrinkage and cracks.
[0023]
Here, in the case of a metal having an FCC (face-centered cubic lattice) crystal structure, such as a copper-based alloy, the diffraction of {110} plane, {111} plane, {311} plane, and {100} plane by X-ray diffraction Intensity is I_{ ₂₂₀ _}, I_{ ₁₁₁ _}, I_{ ₃₁₁ _}, I_{ ₂₀₀ _}Arises as
[0024]
Considering the above, as a result of earnest research to solve the conventional problems, the diffraction intensity I of the {220} plane_{ ₂₂₀ _}, {111} plane diffraction intensity I_{ ₁₁₁ _}, {311} plane diffraction intensity I_{ ₃₁₁ _}, {200} plane diffraction intensity I_{ ₂₀₀ _}Measure and
S (ND) = (I / Cu {311} + I / Cu {200}) ÷ (I / Cu {220} + I / Cu {111}) (1)
I / Cu {abc}: [{abc} plane diffraction intensity I of the measurement sample_{abc}And {abc} plane diffraction intensity Cu of standard copper samples_{abc}Ratio: I_{abc}/ Cu_{abc}Means. The organization is controlled using the parameter S (ND) as an index. Specifically, the bending workability could be improved by determining the annealing and rolling conditions in the process.
[0025]
In other words, the S (ND) on the surface of the plate after the final cold working is obtained by the equation (1), and when annealing / rolling processing that satisfies the condition of S (ND) ≧ 0.3 is performed, R / t = 1.0 In the following, there was no crack on the surface of the bent portion after the 180 ° bending process, and a good bent portion surface could be obtained. On the other hand, when S (ND) <0.3, a crack occurred in the bent portion. It was found that when S (ND)> 0.5, the bending workability is satisfactory, but other properties such as tensile strength cannot be satisfied.
[0026]
Next, the reasons for limiting the manufacturing conditions according to the present invention will be described.
In order to obtain a post-intermediate annealed material having a uniform structure with a small crystal grain size, which is necessary for improving the bending workability in the plate material after the final cold work, on the material surface after the intermediate roll rolling, the formula (1) is used. It is preferable to perform rolling so that the parameter S (ND) is 0.30 or less. When S (ND) exceeds 0.30, the temperature range in which the above-mentioned structure can be obtained in the intermediate annealing is narrowed, and it is difficult to control the crystal grain size.
[0027]
Furthermore, if the intermediate-annealing conditions are controlled so that the parameter S (ND) according to equation (1) is 0.80 or less and the crystal grain size is 5 μm on the surface of the material after intermediate-rolling annealing, the sheet material after the final cold working has high strength. However, bending workability can be improved. If S (ND) exceeds 0.80 or the crystal grain size exceeds 5 μm, the final cold rolling ratio for obtaining the required strength characteristics increases, and is determined by the X-ray diffraction intensity (1) Is less than the range shown in equation (2). For this reason, the bending workability of the plate material after the final cold working is lowered, and it is economically disadvantageous.
[0028]
After this, if the cold working rate is controlled so that the parameter S (ND) according to the formula (1) satisfies 0.3 ≦ S (ND) ≦ 0.5 in the material after the final cold working, the bending strength is increased. A material excellent in workability can be produced.
[0029]
Further, heat treatment is performed at a temperature of 200 to 600 ° C. for 5 seconds to 180 minutes. This heat treatment can improve the bending workability of the material, and further improve the spring limit value, stress corrosion cracking resistance, and conductivity. Such effects are not sufficient when the temperature is lower than 200 ° C., and when the temperature exceeds 600 ° C., the strength rapidly decreases, and the crystal diffraction intensity on the material surface changes and the crystal grains become coarse. The time is preferably 5 seconds to 180 minutes. If the treatment time is too short, the above effect is not sufficient, and if it is too long, it is economically disadvantageous.
[0030]
Moreover, bending workability and stress corrosion cracking resistance can be further improved by heat treatment at a temperature higher than the heat treatment temperature at which the spring limit value reaches a peak. However, if the heat treatment temperature is too high, the tensile strength and the spring limit value are sharply lowered. Therefore, it is desirable that the heat treatment conditions be such that the spring limit value is between 70 and 100% of the peak value.
[0031]
By limiting the range of components, the crystal orientation of the surface of the plate, and the manufacturing conditions as described above, while satisfying bending workability (no cracking even at 180 ° bending of R / t ≦ 1.0), it is further used as a connector material. Necessary properties, specifically tensile strength 600N / mm² As described above, a copper-based alloy for connectors satisfying an electrical conductivity of 20% IACS or more can be produced.
[0032]
Next, embodiments of the present invention will be described by way of examples.
[0033]
【Example】
[Example 1]
Table 1 shows the chemical composition (wt%) of copper alloy No. 1-18 were melted using a high frequency induction melting furnace and cast into a 40 × 40 × 150 (mm) ingot. However, the atmosphere during melting and casting was an Ar gas atmosphere, and water cooling was performed immediately after casting.
[0034]
After that, after each ingot is hot-rolled, cold rolling and annealing are repeated, so that the intermediate surface rolling (final cold rolling) such that S (ND) shown in Formula (1) on the surface of the plate material becomes 0.2 <S (ND) <0.35 The rolling process before the intermediate process) was performed.
[0035]
The plate materials up to No. 18 obtained as described above were heat-treated at 300 to 550 ° C. for 1 hour. The crystal grain size of the plate after heat treatment is 5 to 15 μm. X-ray diffraction was performed on the plate surface (ND surface), and S (ND) shown in Formula (1) was measured. As a result, 0.55 <S (ND ) <0.85. The heat-treated material obtained as described above was cold-rolled to a thickness of 0.25 mm, annealed for 30 minutes at each temperature condition, and subjected to pickling as a test material.
[0036]
Here, the measurement conditions of the X-ray diffraction intensity are as follows.
Tube: Mo (Cu), tube voltage: 40 kV, tube current: 30 mA, sampling width: 0.020 °, monochromator used, sample holder: Al
Note that the X-ray diffraction measurement conditions are not limited to the above conditions, and are appropriately changed depending on the type of the sample.
[0037]
Of the test materials obtained at this time, as a representative, Cu-25.21wt% Zn-0.78wt% Sn after rolling of intermediate rolling was 0.30, S (ND) after annealing was 0.72, and the crystal grain size was FIG. 1 shows an example in which the final cold working rate was changed for a 5 μm material, and the X-ray diffraction intensity integrated intensity ratio, S (ND), of the obtained test material and standard Cu sample was measured. In the example of FIG. 1, as the cold working rate increases, the integration degree of {220} planes increases, and the integration degree of {311} planes and {200} planes decreases.
[0038]
In this way, by determining the cold working rate based on S (ND), which is the criterion for determining the degree of integration of each crystal plane on the material surface, it is possible to stably and reliably produce a material with excellent bending workability and high strength can do.
[0039]
Using the test material obtained as described above, Vickers hardness, tensile strength, Young's modulus, spring limit value and conductivity were measured, and bending workability was investigated. Vickers hardness, tensile strength, Young's modulus, spring limit value, and conductivity were measured in accordance with JIS-Z-2244, JIS-Z-2241, JIS-H-3130, and JIS-H-0505, respectively.
[0040]
For bending workability, a 180 ° bending test (JIS Z 2241, R = 0.25 mm, W = 2.0 mm) was performed on a sample collected in a direction perpendicular to the extending direction, and the ratio of the inner bending radius R to the sheet thickness t was determined as R. As / t, the evaluation was performed with the minimum R / t at which no crack occurred on the surface of the mountain in the center.
[0041]
[Table 1]

[0042]
From the results shown in Table 1, No. 1 according to the present invention. The copper alloys 1 to 8 have good bending workability and are excellent in balance between tensile strength and electrical conductivity. Therefore, it is a copper alloy having very excellent characteristics as a material for electrical and electronic parts such as connectors.
In addition, the alloy No. 1 of the present invention added with the third element. As for 6-8, the improvement of intensity | strength or electrical conductivity is confirmed.
[0043]
On the other hand, comparative alloy No. with less contents of Zn and Sn than specified in the present invention. 9, no. No. 10 is inferior in bending workability and tensile strength, and the comparative alloy No. 10 has more Zn and Sn contents than those defined in the present invention. 11, no. No. 12 is inferior in bending workability.
[0044]
In addition, comparative alloy No. 13 whose crystal orientation parameter S (ND) on the surface of the material after the final cold working is smaller than that defined by the equation (2) is the same as the alloy of the present invention in terms of tensile strength and spring limit, but bending The comparative alloy No. is inferior in workability and has a larger S (ND) than specified by the formula (2). No. 14 is inferior in bending workability, and has a reduced tensile strength and spring limit value.
[0045]
Comparative alloy No. 1 is a sample in which the crystal orientation parameter S (ND) after the intermediate rolling annealing and after the middle rolling shows a larger value specified by the equation (5). No. 15, comparative alloy No. having a crystal orientation parameter S (ND) after the intermediate annealing is larger than that defined by the formula (4) and the crystal grain size is 10 μm. No. 16 is inferior in bending workability.
[0046]
Comparative Alloy No. Reference numeral 17 is a sample that was not heat-treated after cold working, but the bending workability / spring limit value was greatly inferior.
[0047]
Comparative Alloy No. 18, no. 19 is the result of investigating Vickers hardness, tensile strength, Young's modulus, spring limit value, electrical conductivity, and bending workability for commercially available brass type 1 (C2600-EH) and phosphor bronze type 2 (C5191-EH). .
[0048]
It can be seen that the copper alloy of the present invention has improved bending workability and strength as compared with one kind of brass, which is a conventional material for electrical and electronic parts such as connectors. Compared to phosphor bronze, it excels in bending workability, strength, and conductivity. Furthermore, it can be said that it is excellent also in terms of cost from a component and a manufacturing process. Therefore, it can be said that the alloy of the present invention is sufficiently superior to conventional brass and phosphor bronze.
[0049]
【The invention's effect】
As is clear from the above examples, the copper-based alloy according to the present invention or the copper alloy material obtained by the method of the present invention has good processability as compared with conventional brass, phosphor bronze and the like. It is ideal as a material for electrical and electronic parts such as inexpensive connectors because it is excellent in environmental resistance and heat resistance as well as in balance of strength and conductivity.
[Brief description of the drawings]
[Fig.1] Work material with the composition of Cu-25.21wt% Zn-0.78wt% Sn, S (ND) after middle rolling is 0.30, S (ND) after middle annealing is 0.72, crystal grain size Shows the measurement results of the integrated intensity ratio and S (ND) of the X-ray diffraction intensity of the test material obtained by changing the final cold working rate for the material of 5 μm and the standard Cu sample.

Claims

From the X-ray diffraction intensity of the material surface of the plate material, which is a copper alloy material containing Zn: 15 to 45% by mass and Sn: 0.1 to 4.5% by mass with the balance being Cu and inevitable impurities Parameters determined by the following equation (1):
S (ND) = (I / Cu {311} + I / Cu {200}) / (I / Cu {220} + I / Cu {111}) (1)
The ratio of [where in the formula I / Cu {abc} is {abc} plane diffraction intensity I of the measurement sample _{abc} and standard copper specimen {abc} plane diffraction intensity _{_{Cu {abc}: I {abc}} } / Cu _{ represents _{abc} ] is the following formula (2):
0.3 ≦ S (ND) ≦ 0.5 (2)
And the ratio R / t of the minimum bending radius R that can be processed and the thickness t of the plate when the plate is bent by 180 ° in the direction perpendicular to the extending direction is the following formula (3):
R / t ≦ 1.0 (3)
A copper alloy material characterized by satisfying

Zn: 15 to 45% by mass and Sn: 0.1 to 4.5% by mass, Ni: 0.01 to 5% by mass, Mg: 0.01 to 2% by mass, Si: 0.01 to A copper alloy material containing at least one element selected from the group consisting of 3% by mass in a total amount of 0.01 to 5% by mass, the balance being Cu and inevitable impurities, the surface of the plate material Parameters determined by the following equation (1) from the X-ray diffraction intensity:
S (ND) = (I / Cu {311} + I / Cu {200}) / (I / Cu {220} + I / Cu {111}) (1)
The ratio of [where in the formula I / Cu {abc} is {abc} plane diffraction intensity I of the measurement sample _{abc} and standard copper specimen {abc} plane diffraction intensity _{_{Cu {abc}: I {abc}} } / Cu _{ represents _{abc} ] is the following formula (2):
0.3 ≦ S (ND) ≦ 0.5 (2)
And the ratio of the minimum bending radius R that can be processed and the thickness t of the plate when the plate is bent by 180 ° in the direction perpendicular to the extending direction, R / t is the following formula (3):
R / t ≦ 1.0 (3)
A copper alloy material characterized by satisfying

The copper alloy material according to claim 1, wherein the copper alloy material is a material for electric / electronic parts.

The copper alloy material according to claim 3, wherein the electrical / electronic component is a connector.