JP2011208240A - Titanium copper and method of producing the same - Google Patents
Titanium copper and method of producing the same Download PDFInfo
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本発明は、例えばコネクタ等の電子部品用部材に好適なチタン銅及びその製造方法に関する。 The present invention relates to titanium copper suitable for electronic component members such as connectors, and a method for manufacturing the same.
近年では携帯端末などに代表される電子機器の小型化が益々進み、従ってそれに使用されるコネクタは狭ピッチ化及び低背化の傾向が著しい。小型のコネクタほどピン幅が狭く、小さく折り畳んだ加工形状となるため、使用する部材には、必要なバネ性を得るための高い強度と、過酷な曲げ加工に耐えることのできる、優れた曲げ加工性が求められる。この点、チタンを含有する銅合金（以下、「チタン銅」と称する。）は、比較的強度が高く、応力緩和特性にあっては銅合金中最も優れているため、特に強度が要求される信号系端子用部材として古くから使用されてきた。 In recent years, electronic devices typified by portable terminals and the like have been increasingly miniaturized, and accordingly, connectors used for such devices tend to have a narrow pitch and a low profile. The smaller the connector, the narrower the pin width and the smaller the folded shape, so the members used will have high strength to obtain the necessary spring properties and excellent bending that can withstand severe bending. Sex is required. In this regard, a titanium-containing copper alloy (hereinafter referred to as “titanium copper”) has a relatively high strength and is most excellent in the copper alloy in terms of stress relaxation characteristics. It has been used for a long time as a signal system terminal member.
チタン銅は時効硬化型の銅合金である。具体的には、溶体化処理によって溶質原子であるＴｉの過飽和固溶体を形成させ、その状態から低温で比較的長時間の熱処理を施すと、スピノーダル分解によって母相中にＴｉ濃度の周期的変動である変調構造が発達し、強度が向上する。かかる強化機構を基本としてチタン銅の更なる特性向上を目指して種々の手法が研究されている。 Titanium copper is an age-hardening type copper alloy. Specifically, when a supersaturated solid solution of Ti, which is a solute atom, is formed by solution treatment, and heat treatment is performed at a low temperature for a relatively long time from that state, periodic fluctuations in Ti concentration in the parent phase occur due to spinodal decomposition. A certain modulation structure develops and the strength improves. Based on this strengthening mechanism, various methods have been studied with the aim of further improving the properties of titanium copper.
この際、問題となるのは、強度と曲げ加工性が相反する特性である点である。すなわち、強度を向上させると曲げ加工性が損なわれ、逆に、曲げ加工性を重視すると所望の強度が得られないということである。そこで、Ｆｅ、Ｃｏ、Ｎｉ、Ｓｉなどの第三元素を添加する（特許文献１）、母相中に固溶する不純物元素群の濃度を規制し、これらを第二相粒子（Ｃｕ−Ｔｉ−Ｘ系粒子）として所定の分布形態で析出させて変調構造の規則性を高くする（特許文献２）、結晶粒を微細化させるのに有効な微量添加元素と第二相粒子の密度を規定する（特許文献３）、などの観点から、チタン銅の強度と曲げ加工性の両立を図ろうとする研究開発が従来なされてきた。 At this time, the problem is that the strength and the bending workability are contradictory. That is, if the strength is improved, the bending workability is impaired, and conversely, if the bending workability is emphasized, a desired strength cannot be obtained. Therefore, a third element such as Fe, Co, Ni, Si or the like is added (Patent Document 1), the concentration of the impurity element group that dissolves in the matrix phase is regulated, and these elements are added to the second phase particles (Cu-Ti- X-type particles) are precipitated in a predetermined distribution form to increase the regularity of the modulation structure (Patent Document 2), and the density of the trace additive elements and second-phase particles effective to refine the crystal grains is specified. From the viewpoints of (Patent Document 3), etc., research and development have been made in order to achieve both the strength and bending workability of titanium copper.
一般に、チタン銅の製造過程において第二相粒子が粗大化しすぎると、曲げ加工性が損なわれる傾向にあることが知られている。そのため、従来の最終溶体化処理においては、材料を所定の温度に加熱した後、水冷等によりできるだけ速い冷却速度で材料の冷却を行い、冷却過程での第二相粒子の析出を抑える手法が行われている。例えば特開２００１−３０３２２２号公報（特許文献４）では、特性のばらつきを抑制するために、材料の熱処理後に２００℃／ｓ以上の冷却速度で速やかに冷却する例が開示されている。 In general, it is known that bending workability tends to be impaired when the second phase particles are excessively coarsened in the production process of titanium copper. For this reason, in the conventional final solution treatment, after the material is heated to a predetermined temperature, the material is cooled at a cooling rate as fast as possible by water cooling or the like to suppress precipitation of second phase particles during the cooling process. It has been broken. For example, Japanese Patent Laid-Open No. 2001-303222 (Patent Document 4) discloses an example in which cooling is rapidly performed at a cooling rate of 200 ° C./s or higher after heat treatment of a material in order to suppress variation in characteristics.
このように、従来のチタン銅の製造方法は、最終の溶体化処理によってチタンを母相に十分に固溶させた後、固溶させたチタンの安定相を第二相粒子を析出させない条件で速やかに冷却し、その後冷間圧延を行って強度を上昇させ、最後に時効処理でスピノーダル分解を起こして高強度チタン銅を得るというものであった。そのため、最終の溶体化処理の冷却過程においてはできるだけ速やかに冷却することが好ましいとされており、チタン銅の強度及び曲げ加工性のバランス向上を考慮した溶体化処理の冷却過程についてはまだ十分な検討がなされていなかった。
そこで、本発明は、溶体化処理の冷却過程の更なる改善を図り、強度及び曲げ加工性のバランスに優れたチタン銅及びその製造方法を提供することを課題とする。
As described above, the conventional method for producing titanium copper is such that after the final solution treatment, titanium is sufficiently dissolved in the mother phase, and then the stable phase of the dissolved titanium is not deposited on the second phase particles. It was quickly cooled, then cold rolled to increase the strength, and finally subjected to spinodal decomposition by aging treatment to obtain high strength titanium copper. Therefore, it is said that it is preferable to cool as quickly as possible in the cooling process of the final solution treatment, and the cooling process of the solution treatment considering the improvement of the balance of strength and bending workability of titanium copper is still sufficient. There was no consideration.
Therefore, an object of the present invention is to further improve the cooling process of the solution treatment and to provide titanium copper excellent in the balance between strength and bending workability and a method for producing the same.
本発明者は、上記課題を解決するために、最終の溶体化処理後の冷却過程における第二相粒子の析出温度領域と特性の関係について鋭意検討したところ、溶体化処理後の冷却速度は従来のようにただ速くすればよいのではなく、冷却速度を適正な条件に制御し、粗大な第二相粒子の析出を抑制しながら、冷間圧延前の冷却過程において予めスピノーダル分解を発生させることにより、強度及び曲げ加工性のバランスに優れたチタン銅が得られることを見出した。更に、本発明者は得られたチタン銅の特性について調べたところ、第二相粒子の面積率とその析出状態及び所定の熱処理を施した後の強度特性に特徴点を見出した。 In order to solve the above problems, the present inventor has intensively studied the relationship between the precipitation temperature region of the second phase particles and the characteristics in the cooling process after the final solution treatment, and the cooling rate after the solution treatment has been conventionally The spinodal decomposition should be generated in the cooling process before cold rolling while controlling the cooling rate to an appropriate condition and suppressing the precipitation of coarse second-phase particles. Thus, it was found that titanium copper having an excellent balance between strength and bending workability can be obtained. Furthermore, when the present inventors investigated the characteristics of the obtained titanium copper, the inventors found characteristic points in the area ratio of the second phase particles, the precipitation state thereof, and the strength characteristics after performing a predetermined heat treatment.
上記知見を基礎として完成した本発明は一側面において、Ｔｉを２．０〜４．０質量％含有し、第３元素としてＭｎ、Ｆｅ、Ｍｇ、Ｃｏ、Ｎｉ、Ｃｒ、Ｖ、Ｎｂ、Ｍｏ、Ｚｒ、Ｓｉ、Ｂ及びＰの中から１種以上を合計で０〜０．５質量％含有し、残部銅及び不可避的不純物からなるチタン銅であって、圧延方向に平行な断面の組織観察において、１０００μｍ2の観察視野あたりに含まれる粒径０．０１μｍ以上の第二相粒子の面積率（Ｘ）が３．３〜７．０％であり、１０００μｍ2の観察視野あたりに含まれる第二相粒子のアスペクト比をａ／ｂ（ａは長径、ｂは短径）とした場合に、ａ≧０．５μｍかつａ／ｂ≧１．５を満たす第二相粒子の個数密度（Ｙ）が、１０〜９０個であり、かつ材料温度７５０℃で５分間の熱処理を加えたときの０．２％耐力（ＹＳ）が６５０ＭＰａ以上低下するチタン銅である。 The present invention completed on the basis of the above knowledge includes, in one aspect, 2.0 to 4.0% by mass of Ti, and the third element is Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, In the observation of the structure of the cross section parallel to the rolling direction, which is titanium copper containing 0 to 0.5 mass% in total of one or more of Zr, Si, B and P, and the balance copper and unavoidable impurities The area ratio (X) of the second phase particles having a particle diameter of 0.01 μm or more included per 1000 μm 2 observation field is 3.3 to 7.0%, and the second phase particles included per 1000 μm 2 observation field. When the aspect ratio of the phase particles is a / b (a is the major axis and b is the minor axis), the number density (Y) of the second phase particles satisfying a ≧ 0.5 μm and a / b ≧ 1.5 is obtained. 10 to 90, and when a heat treatment for 5 minutes is applied at a material temperature of 750 ° C. .2% yield strength (YS) is a titanium copper falls by more than 650 MPa.
本発明に係るチタン銅の一実施態様では、面積率（Ｘ）が３．５〜５．４％であり、個数密度（Ｙ）が１３〜７９である。 In one embodiment of the titanium copper according to the present invention, the area ratio (X) is 3.5 to 5.4%, and the number density (Y) is 13 to 79.
本発明に係るチタン銅の一実施態様では、圧延平行方向の０．２％耐力が９５０ＭＰａ以上であり、ＢａｄｗａｙのＷ曲げ試験を行い、割れが発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比が０．７〜１．４である。 In one embodiment of the titanium copper according to the present invention, the 0.2% proof stress in the rolling parallel direction is 950 MPa or more, a Badway W bending test is performed, and the thickness (t) of the minimum radius (MBR) at which cracks do not occur. The ratio to is 0.7 to 1.4.
本発明に係るチタン銅の一実施態様では、圧延平行方向の０．２％耐力が１０００ＭＰａ以上であり、ＢａｄｗａｙのＷ曲げ試験を行い、割れが発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比が１．４〜１．８である。 In one embodiment of titanium copper according to the present invention, the 0.2% proof stress in the rolling parallel direction is 1000 MPa or more, a Badway W bending test is performed, and the minimum radius (MBR) thickness (t) at which cracks do not occur. The ratio is 1.4 to 1.8.
本発明に係るチタン銅の一実施態様では、圧延平行方向の０．２％耐力が１０４０ＭＰａ以上であり、ＢａｄｗａｙのＷ曲げ試験を行い、割れが発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比が１．８〜２．２である。 In one embodiment of titanium copper according to the present invention, the 0.2% proof stress in the rolling parallel direction is 1040 MPa or more, a Badway W-bending test is performed, and the thickness (t) of the minimum radius (MBR) at which cracks do not occur. The ratio to is 1.8 to 2.2.
本発明は別の一側面において、上記チタン銅からなる伸銅品である。 In another aspect, the present invention is a copper-drawn product made of the above titanium copper.
本発明は更に別の一側面において、上記チタン銅からなる電子部品である。 In still another aspect, the present invention is an electronic component made of the above titanium copper.
本発明は更に別の一側面において、上記チタン銅を備えたコネクタである。 In another aspect of the present invention, the connector includes the titanium copper.
本発明は更に別の一側面において、Ｔｉを２．０〜４．０質量％含有し、第３元素としてＭｎ、Ｆｅ、Ｍｇ、Ｃｏ、Ｎｉ、Ｃｒ、Ｖ、Ｎｂ、Ｍｏ、Ｚｒ、Ｓｉ、Ｂ及びＰの中から１種以上を合計で０〜０．５質量％含有し、残部銅及び不可避的不純物からなるチタン銅の製造方法であって、７３０〜８８０℃のＴｉの固溶限が添加量と同じになる温度以上に材料を加熱し、加熱後に、材料温度が４００℃になるまで、冷却速度５〜３０℃／ｓで材料を冷却する最終の溶体化処理を行い、溶体化処理後に冷間圧延を行い、冷間圧延後に材料温度２５０〜４５０℃で０．５〜２４時間、材料を加熱する時効処理を行うチタン銅の製造方法である。 In yet another aspect of the present invention, Ti is contained in an amount of 2.0 to 4.0% by mass, and the third element is Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, It is a method for producing titanium copper containing 0 to 0.5% by mass in total of one or more of B and P, the balance being copper and unavoidable impurities, and the solid solubility limit of Ti at 730 to 880 ° C. The material is heated to a temperature equal to or higher than the amount added, and after the heating, the material is subjected to a final solution treatment for cooling the material at a cooling rate of 5 to 30 ° C./s until the material temperature reaches 400 ° C. This is a titanium copper production method in which cold rolling is performed later, and after cold rolling, an aging treatment is performed in which the material is heated at a material temperature of 250 to 450 ° C. for 0.5 to 24 hours.
本発明によれば、従来に比べて強度及び曲げ加工性のバランスに優れたチタン銅及びその製造方法が得られる。 According to the present invention, titanium copper excellent in the balance of strength and bending workability as compared with the prior art and a method for producing the same can be obtained.
＜Ｔｉ含有量＞
Ｔｉが２．０質量％未満ではチタン銅本来の変調構造の形成による強化機構を充分に得ることができないことから十分な強度が得られず、逆に４．０質量％を超えると粗大なＴｉＣｕ3が析出し易くなり、強度及び曲げ加工性が劣化する傾向にある。従って、本発明の実施の形態に係る銅合金中のＴｉの含有量は、２．０〜４．０質量％であり、好ましくは２．７〜３．５質量％である。このようにＴｉの含有量を適正化することで、電子部品用に適した強度及び曲げ加工性を共に実現することができる。
<Ti content>
If Ti is less than 2.0% by mass, a sufficient strengthening mechanism cannot be obtained due to the formation of the original modulation structure of titanium copper, so that sufficient strength cannot be obtained. Conversely, if Ti exceeds 4.0% by mass, coarse TiCu 3 tends to precipitate, and the strength and bending workability tend to deteriorate. Therefore, the content of Ti in the copper alloy according to the embodiment of the present invention is 2.0 to 4.0 mass%, preferably 2.7 to 3.5 mass%. Thus, by optimizing the Ti content, both strength and bending workability suitable for electronic components can be realized.
＜第３元素＞
第３元素をチタン銅に添加すると、Ｔｉが十分に固溶する高い温度で溶体化処理をしても結晶粒が容易に微細化し、強度を向上させる効果がある。また、所定の第３元素は変調構造の形成を促進し、ＴｉＣｕ3等の析出を抑制する効果もある。このため、第３元素を添加することによりチタン銅本来の時効硬化能が得られるようになる。
<Third element>
When the third element is added to titanium copper, there is an effect that the crystal grains are easily refined and the strength is improved even if solution treatment is performed at a high temperature at which Ti is sufficiently dissolved. Further, the predetermined third element has an effect of promoting the formation of the modulation structure and suppressing the precipitation of TiCu 3 or the like. For this reason, the original age hardening ability of titanium copper can be obtained by adding the third element.
第３元素としては、Ｍｎ、Ｆｅ、Ｍｇ、Ｃｏ、Ｎｉ、Ｃｒ、Ｖ、Ｎｂ、Ｍｏ、Ｚｒ、Ｓｉ、Ｂ及びＰを単独で添加するか、又は２種以上を複合添加してもよい。 As the third element, Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B and P may be added alone, or two or more may be added in combination.
これらの添加元素は、合計で０．０５質量％以上含有するとその効果が現れだすが、合計で０．５質量％を超えると、Ｔｉの固溶限を狭くして粗大な第二相粒子を析出し易くなり、強度は若干向上するが曲げ加工性が劣化する。同時に、粗大な第二相粒子は、曲げ部の肌荒れを助長し、プレス加工での金型磨耗を促進させる。従って、第３元素としてＭｎ、Ｆｅ、Ｍｇ、Ｃｏ、Ｎｉ、Ｃｒ、Ｖ、Ｎｂ、Ｍｏ、Ｚｒ、Ｓｉ、Ｂ及びＰよりなる群から選択される１種又は２種以上を、合計で０〜０．５質量％含有することができ、合計で０．０５〜０．５質量％含有するのが好ましい。 When these additive elements are contained in a total amount of 0.05% by mass or more, the effect thereof appears. However, when the total amount exceeds 0.5% by mass, the solid solubility limit of Ti is narrowed and coarse second-phase particles are formed. Precipitation tends to occur and the strength is slightly improved, but bending workability is deteriorated. At the same time, the coarse second-phase particles promote roughening of the bent portion and promote die wear during press working. Therefore, one or more selected from the group consisting of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P as the third element, It can contain 0.5 mass%, and it is preferable to contain 0.05-0.5 mass% in total.
＜第二相粒子＞
本実施形態において「第二相粒子」とは、母相の成分組成とは異なる組成の粒子を指す。第二相粒子は、種々の熱処理中に析出して母相と境界を形成するＣｕとＴｉを主成分とした粒子であり、具体的にはＴｉＣｕ3粒子又は第３元素群の構成要素Ｘ（具体的にはＭｎ、Ｆｅ、Ｍｇ、Ｃｏ、Ｎｉ、Ｃｒ、Ｖ、Ｎｂ、Ｍｏ、Ｚｒ、Ｓｉ、Ｂ及びＰの何れか）を含むＣｕ−Ｔｉ−Ｘ系粒子として現れる。
<Second phase particles>
In the present embodiment, the “second phase particle” refers to a particle having a composition different from the component composition of the parent phase. The second-phase particles are particles mainly composed of Cu and Ti that precipitate during various heat treatments to form a boundary with the parent phase. Specifically, TiCu 3 particles or a constituent element X (third element group X ( Specifically, it appears as Cu—Ti—X-based particles containing Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P).
第二相粒子の析出状態を観察することにより、スピノーダル分解による材料強化の度合いを間接的に評価することができる。即ち、従来のように最終の溶体化処理における冷却速度が速い場合はスピノーダル分解が殆ど起こらず、粗大な第二相粒子は殆ど析出されない。逆に、冷却速度を遅くしすぎると、粗大な第二相粒子を多く析出させるスピノーダル分解が起こり、後の時効処理により第二相粒子が粗大化する。その結果、曲げ性及び強度のバランスが低下する。本実施形態においては、最終の溶体化処理においてその中間の冷却速度で冷却することにより、粗大な第二相粒子の発生を抑制しつつ、スピノーダル分解を生じさせて母相中の変調構造を発達させ、良好な曲げ性を維持したまま強度をより向上させたチタン銅を得る。 By observing the precipitation state of the second phase particles, the degree of material strengthening by spinodal decomposition can be indirectly evaluated. That is, when the cooling rate in the final solution treatment is high as in the prior art, spinodal decomposition hardly occurs and coarse second-phase particles are hardly precipitated. Conversely, if the cooling rate is too low, spinodal decomposition that precipitates a large amount of coarse second-phase particles occurs, and the second-phase particles become coarse due to subsequent aging treatment. As a result, the balance between bendability and strength decreases. In this embodiment, by cooling at the intermediate cooling rate in the final solution treatment, the generation of coarse second-phase particles is suppressed, and spinodal decomposition is caused to develop the modulation structure in the parent phase. Thus, titanium copper with improved strength is obtained while maintaining good bendability.
本実施形態では、第二相粒子を（１）粒径０．０１μｍ以上の第二相粒子の面積率（Ｘ）及び（２）第二相粒子のアスペクト比をａ／ｂ（ａは長径、ｂは短径）とした場合に、ａ≧０．５μｍかつａ／ｂ≧１．５を満たす第二相粒子の個数密度（Ｙ）の２種類により規定する。面積率（Ｘ）の罫線において第二相粒子の粒径の下限を０．０１μｍ以上としたのは、あまりにも微細な第二相粒子はカウントするのが困難なためである。 In the present embodiment, the second phase particles are represented by (1) the area ratio (X) of the second phase particles having a particle size of 0.01 μm or more, and (2) the aspect ratio of the second phase particles a / b (a is the major axis, When b is a minor axis), the number density (Y) of the second phase particles satisfying a ≧ 0.5 μm and a / b ≧ 1.5 is defined. The reason why the lower limit of the particle size of the second phase particles is set to 0.01 μm or more in the ruled line of the area ratio (X) is that it is difficult to count the very fine second phase particles.
本実施形態に係るチタン銅では、圧延方向に平行な断面の検鏡により、１０００μｍ2の観察視野あたりに含まれる粒径０．０１μｍ以上の第二相粒子の面積率（Ｘ）を３．３〜７．０％、更には３．５〜５．４％に制御することが、スピノーダル分解による変調構造を適切に発達させて強度及び曲げ加工性の良好なバランスを得る上で適切であり、より好ましくは３．３〜４．５％、更に好ましくは３．７〜４．２％である。 In the titanium copper according to the present embodiment, the area ratio (X) of the second phase particles having a particle diameter of 0.01 μm or more included in the observation field of 1000 μm 2 is 3.3 by a microscopic observation of a cross section parallel to the rolling direction. It is appropriate to control to ~ 7.0%, further 3.5 to 5.4%, in order to appropriately develop a modulation structure by spinodal decomposition and obtain a good balance between strength and bending workability, More preferably, it is 3.3-4.5%, More preferably, it is 3.7-4.2%.
また、本実施形態に係るチタン銅では、圧延方向に平行な断面の検鏡により、１０００μｍ2の観察視野あたりに含まれる第二相粒子のアスペクト比をａ／ｂ（ａは長径、ｂは短径）とした場合に、ａ≧０．５μｍかつａ／ｂ≧１．５を満たす第二相粒子の個数密度（Ｙ）が、１０〜９０個、更には１３〜７９であるのが好ましく、より好ましくは２０〜６０個、更に好ましくは３０〜５０個である。 Further, in the titanium copper according to the present embodiment, the aspect ratio of the second phase particles included in the observation field of 1000 μm 2 is a / b (a is the major axis, and b is the minor axis) by a microscopic examination of a cross section parallel to the rolling direction. The number density (Y) of the second phase particles satisfying a ≧ 0.5 μm and a / b ≧ 1.5 is preferably 10 to 90, more preferably 13 to 79, More preferably, it is 20-60, More preferably, it is 30-50.
ここで、ａ≧０．５μｍかつａ／ｂ≧１．５を満たす第二相粒子の個数密度が適当な個数密度であるとスピノーダル分解による変調構造の発達の程度が適切であり、曲げ性を劣化せずに強度を向上させることができる。しかし、長径ａが０．５μｍ以上の第二相粒子が多く存在しすぎると個々の第二相粒子が凝集し、粗大化している可能性が高まる。また、アスペクト比ａ／ｂが１．５以上の第二相粒子は複数の第二相粒子が凝集していることを示す。そして、第二相粒子の凝集等によりａ≧０．５μｍかつａ／ｂ≧１．５を満たす第二相粒子が多く存在すると曲げ性が劣化する。一方、アスペクト比ａ／ｂが１．５より小さい粒子しか存在しない（ａ≧０．５μｍかつａ／ｂ≧１．５を満たす第二相粒子の個数密度が低い）場合には、曲げ性に影響を与える第二相粒子の凝集が少ないものの、スピノーダル分解による変調構造が未発達であるため、強度を向上させることは望めない。 Here, if the number density of the second phase particles satisfying a ≧ 0.5 μm and a / b ≧ 1.5 is an appropriate number density, the degree of development of the modulation structure by spinodal decomposition is appropriate, and the bendability is improved. The strength can be improved without deterioration. However, if there are too many second phase particles having a major axis a of 0.5 μm or more, the possibility that the individual second phase particles are aggregated and coarsened increases. The second phase particles having an aspect ratio a / b of 1.5 or more indicate that a plurality of second phase particles are aggregated. And if there are many second phase particles satisfying a ≧ 0.5 μm and a / b ≧ 1.5 due to aggregation of the second phase particles, the bendability deteriorates. On the other hand, when there are only particles having an aspect ratio a / b smaller than 1.5 (the number density of the second phase particles satisfying a ≧ 0.5 μm and a / b ≧ 1.5 is low), the bendability is improved. Although there is little aggregation of the influencing second phase particles, the modulation structure by spinodal decomposition has not been developed, so that it is not possible to improve the strength.
本発明においては、第二相粒子の粒径は、顕微鏡によって観察したときに、第二相粒子を取り囲む最小円の直径として定義する。また、本発明においては、顕微鏡によって観察したときに、観察視野中の第二相粒子の外周を取り囲む円を規定し、円の直径を長径ａとする。また、顕微鏡によって観察したときに観察視野中の第二相粒子に内接する円を規定しこの円の直径を短径ｂとして定義する。 In the present invention, the particle diameter of the second phase particles is defined as the diameter of the smallest circle surrounding the second phase particles when observed with a microscope. In the present invention, when observed with a microscope, a circle surrounding the outer periphery of the second phase particles in the observation field is defined, and the diameter of the circle is defined as the major axis a. Further, a circle inscribed in the second phase particles in the observation field when observed with a microscope is defined, and the diameter of this circle is defined as the minor axis b.
＜熱処理による強度低下特性＞
本実施形態に係るチタン銅の興味深い特性の一つとして、所定の熱処理を施した後の強度低下が、従来のチタン銅と比較して大きいということが挙げられる。これは、前述したように最終溶体化後の冷却工程において、予めスピノーダル分解を起こすことのできる条件とすることで、従来のチタン銅よりも高い強度が得られることに起因する。同一組成のチタン銅であれば、両者に対して所定の熱処理を加えると強度が降下して同程度のボトム強度（第二相粒子が母相に固溶しているときの強度）となる。このため、本発明に係るチタン銅は従来のチタン銅に比べて強度の低下が大きくなる。
<Strength reduction characteristics by heat treatment>
One of the interesting characteristics of titanium copper according to the present embodiment is that the strength reduction after performing a predetermined heat treatment is larger than that of conventional titanium copper. As described above, this is because the strength higher than that of conventional titanium copper can be obtained by setting the conditions in which spinodal decomposition can be caused in advance in the cooling step after the final solution treatment. In the case of titanium copper having the same composition, when a predetermined heat treatment is applied to both, the strength is lowered to the same bottom strength (strength when the second phase particles are dissolved in the matrix). For this reason, the strength of titanium copper according to the present invention is significantly lower than that of conventional titanium copper.
具体的には、本発明に係るチタン銅は、材料温度を７５０℃として５時間加熱したときに０．２％耐力（ＹＳ）が６５０ＭＰａ以上低下し、好ましくは６６０ＭＰａ以上低下し、より好ましくは７１０Ｐａ以上低下し、例えば７１０〜７４０ＭＰａ低下する。 Specifically, the titanium copper according to the present invention has a 0.2% yield strength (YS) reduced by 650 MPa or more, preferably 660 MPa or more, and more preferably 710 Pa when heated at a material temperature of 750 ° C. for 5 hours. For example, it decreases by 710 to 740 MPa.
＜結晶粒径＞
チタン銅の強度及び曲げ加工性を向上させるためには、結晶粒が小さいほどよい。そこで、好ましい平均結晶粒径は３０μｍ以下、より好ましくは２０μｍ以下、更により好ましくは１０μｍ以下である。下限については特に制限はないが、未再結晶領域がなく均一に再結晶するためには、３μｍ以上が好ましい。本発明において、平均結晶粒径は光学顕微鏡又は電子顕微鏡による観察で圧延方向に平行な断面の組織観察における円相当径で計算する。
<Crystal grain size>
In order to improve the strength and bending workability of titanium copper, the smaller the crystal grains, the better. Therefore, the preferable average crystal grain size is 30 μm or less, more preferably 20 μm or less, and still more preferably 10 μm or less. Although there is no restriction | limiting in particular about a minimum, In order to recrystallize uniformly without an unrecrystallized area | region, 3 micrometers or more are preferable. In the present invention, the average crystal grain size is calculated by the equivalent circle diameter in the structure observation of the cross section parallel to the rolling direction by observation with an optical microscope or electron microscope.
＜本発明に係る銅合金の特性＞
本実施形態に係る銅合金は一実施形態において、以下の特性を兼備することができる。
（Ａ）圧延平行方向の０．２％耐力が９５０ＭＰａ以上１０００ＭＰａ未満
（Ｂ）ＢａｄｗａｙのＷ曲げ試験を行って割れの発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比であるＭＢＲ／ｔ値が０．７〜１．４
<Characteristics of copper alloy according to the present invention>
The copper alloy which concerns on this embodiment can have the following characteristics in one Embodiment.
(A) The 0.2% proof stress in the rolling parallel direction is 950 MPa or more and less than 1000 MPa. (B) MBR / t, which is the ratio of the minimum radius (MBR) to the thickness (t) at which cracks do not occur in the Badway W bending test. Value 0.7-1.4
本発明に係る銅合金は別の一実施形態において、以下の特性を兼備することができる。
（Ａ）圧延平行方向の０．２％耐力が１０００ＭＰａ以上１０４０ＭＰａ未満
（Ｂ）ＢａｄｗａｙのＷ曲げ試験を行って割れの発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比であるＭＢＲ／ｔ値が１．４〜１．８
In another embodiment, the copper alloy according to the present invention can have the following characteristics.
(A) The 0.2% proof stress in the rolling parallel direction is 1000 MPa or more and less than 1040 MPa. (B) MBR / t, which is the ratio of the minimum radius (MBR) to the thickness (t) at which cracks do not occur in the Badway W bending test. Values 1.4-1.8
本発明に係る銅合金は更に別の一実施形態において、以下の特性を兼備することができる。
（Ａ）圧延平行方向の０．２％耐力が１０４０ＭＰａ以上１０８０ＭＰａ以下
（Ｂ）ＢａｄｗａｙのＷ曲げ試験を行って割れの発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比であるＭＢＲ／ｔ値が１．８〜２．２
In yet another embodiment, the copper alloy according to the present invention can have the following characteristics.
(A) The 0.2% proof stress in the rolling parallel direction is 1040 MPa or more and 1080 MPa or less. (B) MBR / t, which is the ratio of the minimum radius (MBR) to the plate thickness (t) where cracks do not occur by performing a Badway W bending test. Values 1.8-2.2
−用途−
本実施形態に係るチタン銅は種々の伸銅品、例えば板、条、管、棒及び線として提供されることができる。本実施形態に係るチタン銅は、限定的ではないが、スイッチ、コネクタ、ジャック、端子、リレー等の電子部品の材料として好適に使用することができる。
-Application-
Titanium copper according to this embodiment can be provided as various copper products, such as plates, strips, tubes, bars and wires. Although titanium copper which concerns on this embodiment is not limited, it can be used conveniently as a material of electronic components, such as a switch, a connector, a jack, a terminal, and a relay.
−チタン銅の製造方法−
本実施形態に係るチタン銅は、特に最終の溶体化処理及びそれ以降の工程で適切な熱処理及び冷間圧延を実施することにより製造可能である。以下に、好適な製造例を工程毎に順次説明する。
-Manufacturing method of titanium copper-
Titanium copper according to the present embodiment can be manufactured by performing appropriate heat treatment and cold rolling particularly in the final solution treatment and the subsequent steps. Below, a suitable manufacture example is demonstrated one by one for every process.
１）インゴット製造
溶解及び鋳造によるインゴットの製造は、基本的に真空中又は不活性ガス雰囲気中で行う。溶解において添加元素の溶け残りがあると、強度の向上に対して有効に作用しない。よって、溶け残りをなくすため、ＦｅやＣｒ等の高融点の第３元素は、添加してから十分に攪拌したうえで、一定時間保持する必要がある。一方、ＴｉはＣｕ中に比較的溶け易いので第３元素の溶解後に添加すればよい。従って、Ｃｕに、第３元素としてＭｎ、Ｆｅ、Ｍｇ、Ｃｏ、Ｎｉ、Ｃｒ、Ｖ、Ｎｂ、Ｍｏ、Ｚｒ、Ｓｉ、Ｂ及びＰよりなる群から選択される１種又は２種以上を合計で０〜０．５０質量％含有するように添加し、次いで第２元素としてＴｉを２．０〜４．０質量％含有するように添加してインゴットを製造することが望ましい。
1) Ingot production Ingot production by melting and casting is basically performed in a vacuum or in an inert gas atmosphere. If the additive element remains undissolved during melting, it does not effectively act on strength improvement. Therefore, in order to eliminate undissolved residue, it is necessary to add a high melting point third element such as Fe or Cr, and after sufficiently stirring, hold for a certain period of time. On the other hand, since Ti is relatively easily dissolved in Cu, it may be added after the third element is dissolved. Therefore, Cu includes a total of one or more selected from the group consisting of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P as the third element. It is desirable to add in an amount of 0 to 0.50% by mass, and then to add 2.0 to 4.0% by mass of Ti as the second element to produce an ingot.
２）均質化焼鈍及び熱間圧延
インゴット製造時に生じた凝固偏析や晶出物は粗大なので均質化焼鈍でできるだけ母相に固溶させて小さくし、可能な限り無くすことが望ましい。これは曲げ割れの防止に効果があるからである。具体的には、インゴット製造工程後には、９００〜９７０℃に加熱して３〜２４時間均質化焼鈍を行った後に、熱間圧延を実施するのが好ましい。液体金属脆性を防止するために、熱延前及び熱延中は９６０℃以下とするのが好ましい。
2) Homogenization annealing and hot rolling Solidification segregation and crystallized material generated during ingot production are coarse, so it is desirable to make it as small as possible by dissolving it in the parent phase as much as possible by homogenization annealing. This is because it is effective in preventing bending cracks. Specifically, after the ingot manufacturing process, it is preferable to perform hot rolling after heating to 900 to 970 ° C. and performing homogenization annealing for 3 to 24 hours. In order to prevent liquid metal embrittlement, the temperature is preferably 960 ° C. or less before and during hot rolling.
３）第一溶体化処理
その後、冷延と焼鈍を適宜繰り返してから溶体化処理を行うのが好ましい。ここで予め溶体化を行っておく理由は、最終の溶体化処理での負担を軽減させるためである。すなわち、最終の溶体化処理では、第二相粒子を固溶させるための熱処理ではなく、既に溶体化されてあるのだから、その状態を維持しつつ再結晶のみ起こさせればよいので、軽めの熱処理で済む。具体的には、第一溶体化処理は加熱温度を８５０〜９００℃とし、２〜１０分間行えばよい。そのときの昇温速度及び冷却速度においても極力速くし、ここでは第二相粒子が析出しないようにするのが好ましい。
3) First solution treatment It is then preferable to perform the solution treatment after appropriately repeating cold rolling and annealing. The reason why the solution treatment is performed in advance is to reduce the burden in the final solution treatment. That is, in the final solution treatment, it is not a heat treatment for dissolving the second phase particles, but is already in solution, so it is only necessary to cause recrystallization while maintaining that state. Just heat treatment. Specifically, the first solution treatment may be performed at a heating temperature of 850 to 900 ° C. for 2 to 10 minutes. In this case, it is preferable to increase the heating rate and the cooling rate as much as possible so that the second phase particles do not precipitate.
４）中間圧延
最終の溶体化処理前の中間圧延における圧下率を高くするほど、最終の溶体化処理における再結晶粒を均一かつ微細に制御できる。従って、中間圧延の圧下率は好ましくは７０〜９９％ある。圧下率は｛（（圧延前の厚み−圧延後の厚み）／圧延前の厚み）×１００％｝で定義される。
4) Intermediate rolling As the rolling reduction in the intermediate rolling before the final solution treatment is increased, the recrystallized grains in the final solution treatment can be controlled more uniformly and finely. Therefore, the rolling reduction of the intermediate rolling is preferably 70 to 99%. The rolling reduction is defined by {((thickness before rolling−thickness after rolling) / thickness before rolling) × 100%}.
５）最終の溶体化処理
最終の溶体化処理では、析出物を完全に固溶させることが望ましいが、完全に無くすまで高温に加熱すると、結晶粒が粗大化しやすいので、加熱温度は第二相粒子組成の固溶限付近の温度とする（Ｔｉの添加量が２．０〜４．０質量％の範囲でＴｉの固溶限が添加量と等しくなる温度は７３０〜８４０℃程度であり、例えばＴｉの添加量が３．２質量％では８００℃程度）。典型的には、７３０〜８８０℃のＴｉの固溶限が添加量と同じになる温度以上に加熱し、より典型的には７３０〜８８０℃のＴｉの固溶限が添加量と同じになる温度に比べて０〜２０℃高い温度、好ましくは０〜１０℃高い温度に加熱する。
5) Final solution treatment In the final solution treatment, it is desirable to completely dissolve the precipitates, but if heated to a high temperature until it completely disappears, the crystal grains tend to coarsen, so the heating temperature is the second phase. The temperature is around the solid solubility limit of the particle composition (the temperature at which the solid solubility limit of Ti becomes equal to the addition amount in the range where the addition amount of Ti is 2.0 to 4.0% by mass is about 730 to 840 ° C, For example, when the added amount of Ti is 3.2 mass%, it is about 800 ° C.). Typically, heating is performed at a temperature above which the solid solubility limit of Ti at 730 to 880 ° C. is equal to the addition amount, and more typically, the solid solubility limit of Ti at 730 to 880 ° C. is equal to the addition amount. Heating is performed at a temperature 0 to 20 ° C higher than the temperature, preferably 0 to 10 ° C higher.
最終の溶体化処理での加熱時間は短いほうが結晶粒の粗大化を抑制できる。加熱時間は例えば０．５〜３分とすることができ、典型的には０．５〜１．５分とすることができる。この時点で第２相粒子が発生しても微細かつ均一に分散していれば、強度と曲げ加工性に対してほとんど無害である。しかし粗大なものは最終の時効処理で更に成長する傾向にあるので、この時点での第２相粒子は生成してもなるべく少なく、小さくする。 A shorter heating time in the final solution treatment can suppress the coarsening of crystal grains. The heating time can be, for example, 0.5 to 3 minutes, and typically 0.5 to 1.5 minutes. Even if the second phase particles are generated at this point, if they are finely and uniformly dispersed, they are almost harmless to strength and bending workability. However, since coarse particles tend to grow further in the final aging treatment, the second-phase particles at this point are made as small as possible even if they are produced.
最終の溶体化処理時における冷却速度は、速くすることにより第二相粒子の析出を抑えることはできるが、速すぎるとスピノーダル分解が殆ど起こらない。本発明者らは、ビッカース硬さ（Ｈｖ）及び導電率（ＥＣ）の観点から、第二相粒子の析出温度領域について鋭意検討したところ、８００〜６００℃で第二相粒子が析出し始め、６００〜４００℃で第二相粒子の増加・成長が起き、４００〜１００℃では変化が見られないことがわかった。このため、材料温度が４００℃まで冷却される間の冷却速度を適正な条件とすることにより、第二相粒子の析出を制御するとともに、スピノーダル分解を生じさせて、強度及び曲げ性を制御する。 Although the precipitation rate of the second phase particles can be suppressed by increasing the cooling rate during the final solution treatment, spinodal decomposition hardly occurs if the cooling rate is too high. From the viewpoint of Vickers hardness (Hv) and electrical conductivity (EC), the present inventors have intensively studied the precipitation temperature region of the second phase particles, and the second phase particles begin to precipitate at 800 to 600 ° C. It was found that the increase and growth of the second phase particles occurred at 600 to 400 ° C., and no change was observed at 400 to 100 ° C. For this reason, by setting the cooling rate while the material temperature is cooled to 400 ° C. to an appropriate condition, the precipitation of the second phase particles is controlled and the spinodal decomposition is caused to control the strength and bendability. .
冷却速度は、従来のように速くしすぎると、時効工程において強加工を加えても０．２％耐力（ＹＳ）が１０００ＭＰａ程度で飽和し、それ以上のＹＳを得ることが難しい。また、材料に強加工を加えることにより、曲げ加工性が低下する場合があるため、強度と曲げ加工性のバランスをとることが難しい。一方、冷却速度を遅くしすぎると、上述したように第二相粒子の析出数が増加するとともに第二相粒子が粗大化し、曲げ加工性に影響を及ぼす。このため、本実施形態においては、材料温度が４００℃になるまでは、冷却速度５〜３０℃／ｓ、より好ましくは５〜２０℃／ｓ、更に好ましくは１０〜１７℃／ｓで冷却するのが好ましい。 If the cooling rate is too high as in the prior art, the 0.2% proof stress (YS) will be saturated at about 1000 MPa even if strong processing is applied in the aging process, and it will be difficult to obtain more YS. In addition, since the bending workability may be reduced by applying strong processing to the material, it is difficult to balance strength and bending workability. On the other hand, if the cooling rate is too low, the number of second-phase particles is increased as described above, and the second-phase particles are coarsened, affecting the bending workability. For this reason, in this embodiment, until the material temperature reaches 400 ° C., the cooling rate is 5 to 30 ° C./s, more preferably 5 to 20 ° C./s, and further preferably 10 to 17 ° C./s. Is preferred.
６）最終の冷間圧延
上記溶体化処理後、最終の冷間圧延を行う。最終の冷間加工によってチタン銅の強度を高めることができる。具体的には圧下率を５％以上、好ましくは１０％以上、より好ましくは１５％以上とする。但し、圧下率が高くなると強度は上昇するものの曲げ性が劣化することから、圧下率を４０％以下、好ましくは３０％以下、より好ましくは２５％以下とする。
6) Final cold rolling After the solution treatment, final cold rolling is performed. The strength of titanium copper can be increased by the final cold working. Specifically, the rolling reduction is 5% or more, preferably 10% or more, more preferably 15% or more. However, as the rolling reduction increases, the strength increases but the bendability deteriorates. Therefore, the rolling reduction is set to 40% or less, preferably 30% or less, more preferably 25% or less.
７）時効処理
最終の冷間圧延の後、時効処理を行う。時効処理の条件は慣用の条件でよいが、時効処理を従来に比べて軽めに行うと、強度と曲げ加工性のバランスが更に向上する。時効処理の具体的な条件としては、材料温度２５０℃以上４５０℃以下で０．５〜２４時間加熱することが好ましく、５〜１２時間加熱することがより好ましい。材料温度と加熱時間の関係をより詳細に説明すると、材料温度２５０℃以上３５０℃未満の場合は５〜２４時間加熱することが好ましく、７〜１５時間加熱することがより好ましい。材料温度３５０℃以上４５０℃以下の場合は０．５〜１５時間加熱することが好ましく、４〜１２時間加熱することがより好ましい。
7) Aging treatment An aging treatment is performed after the final cold rolling. The conditions for the aging treatment may be conventional conditions, but if the aging treatment is performed lighter than the conventional one, the balance between strength and bending workability is further improved. As specific conditions for the aging treatment, heating is preferably performed at a material temperature of 250 ° C. or higher and 450 ° C. or lower for 0.5 to 24 hours, and more preferably 5 to 12 hours. The relationship between the material temperature and the heating time will be described in more detail. When the material temperature is 250 ° C. or higher and lower than 350 ° C., it is preferably heated for 5 to 24 hours, more preferably 7 to 15 hours. When the material temperature is 350 ° C. or higher and 450 ° C. or lower, heating is preferably performed for 0.5 to 15 hours, more preferably 4 to 12 hours.
なお、当業者であれば、上記各工程の合間に適宜、表面の酸化スケール除去のための研削、研磨、ショットブラスト酸洗等の工程を行なうことができることは理解できるだろう。 A person skilled in the art will understand that steps such as grinding, polishing, and shot blast pickling for removing oxide scale on the surface can be appropriately performed between the above steps.
以下に本発明の実施例を比較例と共に示すが、これらの実施例は本発明及びその利点をよりよく理解するために提供するものであり、発明が限定されることを意図するものではない。 Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.
実施例の銅合金を製造するに際しては、活性金属であるＴｉが第２成分として添加されるから、溶製には真空溶解炉を用いた。また、本発明で規定した元素以外の不純物元素の混入による予想外の副作用が生じることを未然に防ぐため、原料は比較的純度の高いものを厳選して使用した。 When manufacturing the copper alloy of the example, Ti, which is an active metal, is added as the second component, so a vacuum melting furnace was used for melting. In addition, in order to prevent unexpected side effects due to mixing of impurity elements other than the elements defined in the present invention, raw materials having a relatively high purity were carefully selected and used.
表１に記載の濃度のＴｉを添加し、場合により第３元素を更に添加して、残部銅及び不可避的不純物の組成を有するインゴットに対して９５０℃で３時間加熱する均質化焼鈍の後、９００〜９５０℃で熱間圧延を行い、板厚１０ｍｍの熱延板を得た。なお、表１中に示される各成分の数字は質量％を示す。面削による脱スケール後、冷間圧延して素条の板厚（２．０ｍｍ）とし、素条での第１次溶体化処理を行った。第１次溶体化処理の条件は８５０℃で１０分間加熱とした。次いで、中間の冷間圧延では最終板厚が０．１０ｍｍとなるように中間の板厚を調整して冷間圧延した。 After homogenization annealing in which Ti of the concentration shown in Table 1 is added, optionally a third element is added, and the ingot having the composition of the remaining copper and inevitable impurities is heated at 950 ° C. for 3 hours, Hot rolling was performed at 900 to 950 ° C. to obtain a hot rolled sheet having a thickness of 10 mm. In addition, the number of each component shown in Table 1 shows the mass%. After descaling by chamfering, cold rolling was performed to obtain a strip thickness (2.0 mm), and a primary solution treatment was performed on the strip. The conditions for the primary solution treatment were heating at 850 ° C. for 10 minutes. Next, in the intermediate cold rolling, the intermediate plate thickness was adjusted so that the final plate thickness was 0.10 mm, and cold rolling was performed.
次いで、急速加熱が可能な焼鈍炉に挿入して材料温度がＴｉの固溶限が添加量と同じになる温度（Ｔｉ濃度１．５質量％で約６８０℃、Ｔｉ濃度２．０質量％で約７３０℃、Ｔｉ濃度３．０質量％及び３．２質量％で約８００℃、Ｔｉ濃度４．０質量％で約８４０℃）に加熱した。その後、表１に記載の溶体化冷却速度で材料を冷却し、酸洗による脱スケール後、冷間圧延により板厚０．０７５ｍｍまで圧延して試験片とした。冷間圧延後、表１の条件で時効処理を行った。時効処理は不活性ガス（Ａｒ）雰囲気中で行い、その他の熱処理は空気中で行った。 Next, the material temperature is inserted into an annealing furnace capable of rapid heating, and the temperature at which the solid solubility limit of Ti becomes the same as the addition amount (Ti concentration of 1.5% by mass is about 680 ° C., Ti concentration is 2.0% by mass) About 730 ° C., Ti concentration of 3.0% by mass and 3.2% by mass at about 800 ° C., Ti concentration of 4.0% by mass at about 840 ° C.). Thereafter, the material was cooled at a solution cooling rate shown in Table 1, and after descaling by pickling, it was rolled to a thickness of 0.075 mm by cold rolling to obtain a test piece. After cold rolling, an aging treatment was performed under the conditions shown in Table 1. The aging treatment was performed in an inert gas (Ar) atmosphere, and the other heat treatment was performed in air.
得られた各試験片について以下の条件で特性評価を行った。
＜強度＞
引張方向が圧延方向と平行になるように、プレス機を用いてＪＩＳ１３Ｂ号試験片を作製した。ＪＩＳ−Ｚ２２４１に従ってこの試験片の引張試験を行ない、圧延平行方向の０．２％耐力（ＹＳ）を測定した。
＜曲げ加工性＞
ＪＩＳ Ｈ ３１３０に従って、Ｂａｄｗａｙ（曲げ軸が圧延方向と同一方向）のＷ曲げ試験を行って割れの発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比であるＭＢＲ／ｔ値を測定した。
＜熱処理による強度低下特性＞
得られた試験片に対して、材料温度を７５０℃として５時間加熱する熱処理を行った後に上述した手順で０．２％耐力（ＹＳ）を測定し、熱処理前後のＹＳの低下度合いを求めた。
＜析出物の面積率＞
圧延方向に平行な断面をＦＩＢにて切断することで、断面を露出した後、断面をＳＥＭ観察し、析出物（第二相粒子）の面積率（Ｘ）をカウントした。具体的には、１００μｍ×１００μｍの観察視野に存在する第二相粒子をマークし、これが占める面積を画像解析装置により求め、５視野の平均値を算出した。なお、枠を横切っている結晶粒については、すべて１／２個としてカウントした。画像解析は、０．０１μｍ以上の第二相粒子のみを白色とし、それ以外の領域を黒色にして二値化することで行った。
＜第二相粒子の個数密度＞
圧延方向に平行な断面をＦＩＢにて切断することで、断面を露出した後、断面をＳＥＭ観察し、１００μｍ×１００μｍの観察視野に存在する第二相粒子をマークして、個々の第二相粒子について、第二相粒子を取り囲む円を定義し、円の直径長径ａとし第２相粒子に内接する小円を定義し、その円の直径を短径ｂとし、アスペクト比ａ／ｂを計算した。なお、枠を横切っている結晶粒については、すべて１／２個としてカウントした。結果を表１に示す。
Characteristic evaluation was performed on the obtained test pieces under the following conditions.
<Strength>
A JIS No. 13B specimen was prepared using a press so that the tensile direction was parallel to the rolling direction. The specimen was subjected to a tensile test according to JIS-Z2241, and the 0.2% proof stress (YS) in the rolling parallel direction was measured.
<Bending workability>
In accordance with JIS H 3130, a W-bending test of Badway (the bending axis is the same direction as the rolling direction) was performed to measure the MBR / t value, which is the ratio of the minimum radius (MBR) at which cracks do not occur to the plate thickness (t).
<Strength reduction characteristics by heat treatment>
The obtained test piece was subjected to a heat treatment of heating at a material temperature of 750 ° C. for 5 hours, and then the 0.2% proof stress (YS) was measured by the procedure described above to determine the degree of decrease in YS before and after the heat treatment. .
<Area ratio of precipitate>
By cutting the cross section parallel to the rolling direction with FIB, the cross section was exposed, and then the cross section was observed with an SEM, and the area ratio (X) of precipitates (second phase particles) was counted. Specifically, the second phase particles present in the observation field of 100 μm × 100 μm were marked, the area occupied by this was determined by an image analyzer, and the average value of the five fields of view was calculated. Note that all the crystal grains crossing the frame were counted as ½. Image analysis was performed by binarizing only the second phase particles of 0.01 μm or more in white and the other areas in black.
<Number density of second phase particles>
By cutting the cross section parallel to the rolling direction with FIB, the cross section is exposed, and then the cross section is observed with SEM, and the second phase particles present in the observation field of 100 μm × 100 μm are marked, and the individual second phases For a particle, a circle surrounding the second phase particle is defined, a circle having a major diameter a is defined as a small circle inscribed in the second phase particle, a diameter of the circle is defined as a minor axis b, and an aspect ratio a / b is calculated. did. Note that all the crystal grains crossing the frame were counted as ½. The results are shown in Table 1.
＜考察＞
実施例１〜１１と比較例１〜１０に関し、強度と曲げ性との関係を表すグラフを図１に示す。図１に示すように、実施例１〜１１に係るチタン銅によれば、比較例１〜１０に比べて強度及び曲げ性のバランスにおいて優れた特性を有していることが分かる。
また、表１に示すように、実施例１〜３と４〜６はそれぞれ同一成分であるが、溶体化冷却速度と時効処理条件が相違する。溶体化冷却速度が遅いほど、冷却過程でのスピノーダル分解により変調構造が発達するため、時効処理温度を低くしたとしても、いずれも優れた強度−曲げバランスが得られたことが分かる。
実施例７〜１１は組成を変えた例であるが、規定範囲内で組成を変化させても本発明が意図する効果が得られていることが分かる。
比較例１及び５は従来例であるが、溶体化処理の冷却速度を高くし、冷却過程でスピノーダル分解が殆ど起きていないために第二相粒子の面積率は低く、ａ≧０．５μｍかつａ／ｂ≧１．５を満たす第二相粒子の個数密度が低く、強度も低かった。また、ボトム強度（第二相粒子を母相に固溶させたときの強度）は同じだが、製造条件の差によって強度が低いため、熱処理によるＹＳ低下量が小さかった。
比較例２及び６は、比較例１及び５よりも第二相粒子の面積率を高くすべく時効処理を比較例１及び５よりも高温で実施したところ過時効となってしまった。そのためＹＳの値および熱処理によるＹＳ低下量は更に小さくなった。
比較例３及び７は、比較例１、２、５及び６に比べて冷却速度を遅くしたが、実施例１〜１１と比べると冷却速度は速く、冷却過程でのスピノーダル分解が充分に起きなかったために第二相粒子の面積率は低く、ａ≧０．５μｍかつａ／ｂ≧１．５を満たす第二相粒子の個数密度が低く、強度も低くなり、熱処理によるＹＳの低下量が小さかった。
比較例４及び８は比較例３及び７に比べて更に冷却速度を遅くしたが、実施例１〜１１と比べても冷却速度は更に遅く、冷却過程で第二相粒子が過度に析出・凝集したために、面積率や個数密度が高くなり、曲げ性が大きく劣化した。
比較例９及び１０はＴｉ濃度が規定範囲外の組成であるために本発明が意図する効果は得られなかった。
<Discussion>
A graph showing the relationship between strength and bendability for Examples 1 to 11 and Comparative Examples 1 to 10 is shown in FIG. As shown in FIG. 1, according to the titanium copper which concerns on Examples 1-11, it turns out that it has the characteristic excellent in the balance of intensity | strength and bendability compared with Comparative Examples 1-10.
Moreover, as shown in Table 1, Examples 1-3 and 4-6 are the same components, respectively, but the solution cooling rate and aging treatment conditions are different. It can be seen that, as the solution cooling rate is lower, the modulation structure develops due to spinodal decomposition during the cooling process, and therefore, even if the aging treatment temperature is lowered, an excellent strength-bending balance is obtained.
Examples 7 to 11 are examples in which the composition was changed, but it can be seen that the intended effect of the present invention was obtained even if the composition was changed within the specified range.
Although Comparative Examples 1 and 5 are conventional examples, the cooling rate of the solution treatment is increased, and the spinodal decomposition hardly occurs in the cooling process, so the area ratio of the second phase particles is low, and a ≧ 0.5 μm and The number density of the second phase particles satisfying a / b ≧ 1.5 was low and the strength was low. Further, the bottom strength (strength when the second phase particles were dissolved in the matrix) was the same, but the strength was low due to the difference in production conditions, so the amount of YS reduction due to heat treatment was small.
In Comparative Examples 2 and 6, when the aging treatment was carried out at a higher temperature than Comparative Examples 1 and 5 in order to increase the area ratio of the second phase particles as compared with Comparative Examples 1 and 5, it was over-aged. Therefore, the value of YS and the amount of YS reduction due to heat treatment were further reduced.
In Comparative Examples 3 and 7, the cooling rate was slow compared to Comparative Examples 1, 2, 5 and 6, but the cooling rate was faster than in Examples 1 to 11, and spinodal decomposition did not occur sufficiently in the cooling process. Therefore, the area ratio of the second phase particles is low, the number density of the second phase particles satisfying a ≧ 0.5 μm and a / b ≧ 1.5 is low, the strength is low, and the amount of decrease in YS by heat treatment is small. It was.
In Comparative Examples 4 and 8, the cooling rate was further reduced as compared with Comparative Examples 3 and 7, but the cooling rate was further slower than in Examples 1 to 11, and the second phase particles were excessively precipitated and aggregated during the cooling process. As a result, the area ratio and number density increased, and the bendability deteriorated significantly.
In Comparative Examples 9 and 10, the Ti concentration was outside the specified range, so the effect intended by the present invention was not obtained.
Claims (9)
圧延方向に平行な断面の組織観察において、
１０００μｍ2の観察視野あたりに含まれる粒径０．０１μｍ以上の第二相粒子の面積率（Ｘ）が３．３〜７．０％であり、
１０００μｍ2の観察視野あたりに含まれる前記第二相粒子のアスペクト比をａ／ｂ（ａは長径、ｂは短径）とした場合に、ａ≧０．５μｍかつａ／ｂ≧１．５を満たす前記第二相粒子の個数密度（Ｙ）が、１０〜９０個であり、かつ
材料温度７５０℃で５分間の熱処理を加えたときの０．２％耐力（ＹＳ）が６５０ＭＰａ以上低下する
ことを特徴とするチタン銅。 Ti is contained in an amount of 2.0 to 4.0% by mass, and one or more of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P are used as the third element. Titanium copper containing 0 to 0.5% by mass in total, consisting of the remaining copper and inevitable impurities,
In observing the structure of the cross section parallel to the rolling direction,
The area ratio (X) of the second phase particles having a particle diameter of 0.01 μm or more included per 1000 μm 2 observation field is 3.3 to 7.0%,
When the aspect ratio of the second phase particles included in the observation field of 1000 μm 2 is a / b (a is a major axis and b is a minor axis), a ≧ 0.5 μm and a / b ≧ 1.5 The number density (Y) of the second phase particles to be filled is 10 to 90, and the 0.2% proof stress (YS) is lowered by 650 MPa or more when heat treatment is performed at a material temperature of 750 ° C. for 5 minutes. Titanium copper characterized by
ＢａｄｗａｙのＷ曲げ試験を行い、割れが発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比が０．７〜１．４である請求項１又は２のチタン銅。 0.2% proof stress in the rolling parallel direction is 950 MPa or more,
The titanium-copper according to claim 1 or 2, wherein the ratio of the minimum radius (MBR) at which no crack is generated to the plate thickness (t) is 0.7 to 1.4 by performing a Badway W bending test.
ＢａｄｗａｙのＷ曲げ試験を行い、割れが発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比が１．４〜１．８である請求項１又は２のチタン銅。 0.2% proof stress in the rolling parallel direction is 1000 MPa or more,
The titanium-copper according to claim 1 or 2, wherein the ratio of the minimum radius (MBR) at which no crack is generated to the plate thickness (t) is 1.4 to 1.8 by performing a Badway W bending test.
ＢａｄｗａｙのＷ曲げ試験を行い、割れが発生しない最小半径（ＭＢＲ）の板厚（ｔ）に対する比が１．８〜２．２である請求項１又は２のチタン銅。 0.2% proof stress in the rolling parallel direction is 1040 MPa or more,
The titanium-copper according to claim 1 or 2, wherein the ratio of the minimum radius (MBR) at which cracks do not occur to the plate thickness (t) is 1.8 to 2.2 by performing a Badway W bending test.
７３０〜８８０℃のＴｉの固溶限が添加量と同じになる温度以上に材料を加熱し、加熱後に、材料温度が４００℃になるまで、冷却速度５〜３０℃／ｓで前記材料を冷却する最終の溶体化処理を行い、
前記溶体化処理後に冷間圧延を行い、
前記冷間圧延後に材料温度２５０〜４５０℃で０．５〜２４時間、前記材料を加熱する時効処理を行うこと
を含むチタン銅の製造方法。 Ti is contained in an amount of 2.0 to 4.0% by mass, and one or more of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P are used as the third element. It is a manufacturing method of titanium copper containing 0 to 0.5% by mass in total, consisting of remaining copper and inevitable impurities,
The material is heated to a temperature at which the solid solubility limit of Ti at 730 to 880 ° C. is equal to the addition amount, and after heating, the material is cooled at a cooling rate of 5 to 30 ° C./s until the material temperature reaches 400 ° C. Perform the final solution treatment,
Cold rolling after the solution treatment,
A method for producing titanium copper, comprising: performing an aging treatment for heating the material at a material temperature of 250 to 450 ° C. for 0.5 to 24 hours after the cold rolling.
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| JP2015127438A (en) * | 2013-12-27 | 2015-07-09 | Jx日鉱日石金属株式会社 | Titanium copper for electronic component |
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