KR101365380B1 - Copper alloy and wrought article, electric parts, and connector - Google Patents

Abstract

(Problem) The present invention provides a new copper alloy, a new product, an electronic component, and a connector that can improve the properties of titanium copper.
(Measures) Ti is contained 2.0-4.0 mass%, and as a 3rd element, 1 or more types are summed in total among Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, P. In the copper alloy containing 0-0.5 mass% and consisting of remainder copper and an unavoidable impurity, in the structure observation by the electron microscope of the surface after electropolishing of a rolling surface, the number density of the 2nd phase particle | grains of particle diameter 0.5 micrometer or more (X ) Is 0.11 to 0.04 pieces / μm 2, and the number ratio (Y) in which the second phase particles having a particle size of 0.5 μm or more are precipitated along the grain boundaries is 45 to 80%.

Description

Copper Alloys, New Products, Electronic Components & Connectors {COPPER ALLOY AND WROUGHT ARTICLE, ELECTRIC PARTS, AND CONNECTOR}

TECHNICAL FIELD This invention relates to a copper alloy, a new product, an electronic component, and a connector.

In recent years, the miniaturization of electronic devices such as portable terminals and the like has progressed, and therefore, the connectors used therein tend to have narrow pitches and low magnifications. The smaller the connector, the narrower the pin width and the smaller the folded work shape. Therefore, the material to be used is required to have high strength for obtaining necessary spring property and excellent bending workability that can withstand severe bending.

In this regard, a copper alloy containing titanium (hereinafter referred to as "titanium copper") has a relatively high strength and is the most excellent among copper alloys in stress relaxation characteristics, and thus is particularly suitable for signal terminal terminals. It has been used for a long time. Titanium copper is an aging hardening copper alloy. Specifically, when a supersaturated solid solution of Ti, which is a solute atom, is formed by the solution treatment, and a heat treatment for a relatively long time at low temperature in that state, a modulation structure that is a periodic variation of the Ti concentration in the mother phase is developed by spinodal decomposition. This improves the strength. Based on these reinforcing mechanisms, various methods have been studied aiming at further improving the properties of titanium copper.

At this time, a problem is that the strength and the bending workability are opposite to each other. In other words, if the strength is improved, bending workability is impaired. On the contrary, if emphasis is placed on bending workability, desired strength cannot be obtained. Then, 3rd elements, such as Fe, Co, Ni, and Si, are added (patent document 1), the density | concentration of the impurity element group dissolved in a mother phase is regulated, and these are 2nd phase particle | grains (Cu-Ti-X type particle | grains). In order to increase the regularity of the modulation structure by depositing it in a predetermined distribution form (Patent Document 2), and from the viewpoint of defining the density of trace additive elements and second phase particles effective for miniaturizing crystal grains (Patent Document 3), etc. In order to achieve both strength and bending workability of titanium copper, research and development have been made.

In Patent Literature 1, a titanium copper having a maximum yield of 888 MPa of 0.2% yields a maximum, and describes that MBR / t at this time was 0.7 (Example No. 10). In Patent Literature 2, a titanium copper having a maximum yield of 839 MPa of 0.2% yield was obtained, and it was described that the MBR / t at this time was 1.7 (Example No. 10). In patent document 3, it is described that titanium copper whose 0.2% yield strength is 888 MPa maximum is obtained, and MBR / t at this time was 0.5 (Example No. 10).

In addition, in Patent Document 4, in the case of titanium, copper, a poor consistency β for the parent phase of α (TiCu ₃₎ and, consistent with good β 'phase (TiCu ₄₎ is present, and an adverse effect on the β phase bending On the other hand, since the uniformly and finely disperse | distributing (beta) 'phase contributes to the coexistence of strength and bending workability, the titanium copper which finely disperse | distributed the β' phase while suppressing the (beta) phase is disclosed. In Patent Literature 4, a titanium copper having a maximum yield of 1019 MPa of 0.2% yield was obtained, and it was described that MBR / t at this time was 2 (Example No. 4).

In addition, these documents describe the production of titanium copper in the order of melt casting → homogenization annealing → hot rolling → (repeat of annealing and cold rolling) → final solution treatment → cold rolling → aging treatment of ingots. In particular, in the final solution treatment, it has become important to suppress precipitation of the second phase particles which are incompatible with the stable phase TiCu ₃ or the mother phase.

Japanese Laid-Open Patent Publication 2004-231985 Japanese Laid-Open Patent Publication 2004-176163 Japanese Laid-Open Patent Publication 2005-97638 Japanese Laid-Open Patent Publication No. 2006-283142

As described above, titanium copper is generally manufactured in the order of melt casting → homogenization annealing → hot rolling → (repeat of annealing and cold rolling) → final solution treatment → cold rolling → aging treatment. Basically, the characteristics have been improved. However, it is thought that it is useful to find a new manufacturing method that is not bound to the off-the-shelf concept in obtaining titanium copper with better characteristics.

Therefore, a main object of the present invention is to provide a new copper alloy, a new product, an electronic component, and a connector capable of improving the properties of titanium copper.

In the conventional method for producing titanium copper, after sufficiently solidifying titanium in the form of a matrix by the final solution treatment, cold rolling is performed to increase the strength to a certain degree, and finally, spinodal decomposition is caused by aging treatment to produce high strength titanium copper. It was to get. Therefore, it was unthinkable to perform the heat processing before cold rolling which might hardly precipitate the stable phase of solid solution solid titanium.

However, as a result of earnest research, the present inventors found that if the metastable phase or the stable phase of titanium is not produced or partially produced, the spinodal decomposition is caused to some extent before the cold rolling, and then the cold rolling and aging treatment is performed. It was found that the strength of the finally obtained titanium copper was significantly improved. That is, in the manufacturing method of the titanium copper of this invention, after the final solution treatment, the conventional aging treatment is carried out in the manufacturing method of the titanium copper of this invention, compared with the conventional manufacturing method of the titanium copper which performed the heat processing process which causes spinodal decomposition. After the heat treatment is performed in a shorter time and under the conditions of subaging, cold rolling is carried out, and after cold rolling, a two-stage aging treatment is performed, which is lighter than the conventional method. Different.

Moreover, it can also be seen that by adding a heat treatment step and then performing an aging treatment at a lower temperature side than in the related art, titanium copper can be improved remarkably improved in balance between strength and bending workability.

The reason why the properties of titanium copper is improved by employing the above manufacturing process is not fully understood. Although the present invention is not intended to be limited by theory, this is inferred as follows. In titanium copper, as the modulation structure of titanium develops in the aging treatment, the amplitude (light) of the concentration change of the titanium increases. It changes into a stable β phase and further β phase. That is, by adding heat treatment thereafter, the titanium solid-dissolved by the solution treatment gradually develops a modulation structure, which is a periodic variation in the Ti concentration, which changes to a metastable β ＇phase and finally It changes to the β phase which is a stable phase. By the way, after the final solution treatment and before the cold rolling, a predetermined heat treatment capable of causing spinodal decomposition, the β ＇phase does not precipitate well even when the β＇ phase normally reaches an amplitude to be precipitated during the aging treatment. It is thought to have grown to a modulation structure having a larger amplitude. And it is thought that such a large modulation structure gave the titanium copper viscosity. However, it is technically difficult to measure the amplitude of titanium concentration, and the detail of the mechanism of a characteristic improvement is not clear. In any case, by adopting the production method of the present invention, it becomes possible to obtain titanium copper having high strength as compared with the conventional production method in which only one step of spinodal decomposition was performed.

Based on the above, this invention completed 2.0-4.0 mass% of Ti in one aspect, and contains Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B as a 3rd element. , A copper alloy composed of 0 to 0.5% by mass in total of at least one of P, and consisting of residual copper and unavoidable impurities, in the structure observation by electron microscopy of the surface after electropolishing of the rolled surface, the particle diameter of 0.5 μm or more It is a copper alloy whose number density (X) of a 2nd phase particle is 0.04-0.11 piece / microm <2>, and the number ratio (Y) which the 2nd phase particle of 0.5 micrometer or more of particle diameters precipitates along a grain boundary is 45 to 80%.

The copper alloy which concerns on this invention heats and quenchs by heating until it becomes 0-20 degreeC high temperature with respect to the solid solution temperature which the solid solution of Ti becomes equal to the addition amount in 550-1000 degreeC. In the case where the titanium concentration (mass%) is set to [Ti] after the solution treatment, the increase value C (% IACS) of the conductivity is expressed by the following relational expression: 0.5 ≦ C ≦ (-0.50 [Ti] ² − It is manufactured by performing a heat treatment to increase the electrical conductivity so as to satisfy 0.50 [Ti] +14), followed by the final cold rolling followed by the heat treatment, and the aging treatment subsequent to the final cold rolling.

In another aspect, the present invention is a flexible product using the copper alloy.

In another aspect, the present invention is an electronic component produced using the copper alloy.

In another aspect, the present invention is a connector manufactured using the copper alloy.

According to the present invention, the strength of titanium copper can be improved. Moreover, in the preferable embodiment of this invention, the titanium copper which can achieve strength and bending workability in high dimension is obtained.

FIG.1 (a) and FIG.1 (b) are schematic which demonstrates the measuring method of the 2nd phase particle which appears in the rolling surface after the electrolytic polishing of the titanium copper which concerns on embodiment of this invention.

Ti  content

If Ti is less than 2% by mass, sufficient strength cannot be obtained in that a strengthening mechanism due to the formation of titanium copper's original modulation structure cannot be sufficiently obtained. On the contrary, when Ti is more than 4% by mass, coarse TiCu ₃ easily precipitates. There is a tendency for strength and bending workability to deteriorate. Therefore, the content of Ti in the copper alloy according to the present invention is 2.0 to 4.0 mass%, preferably 2.7 to 3.5 mass%. By optimizing the content of Ti in this manner, strength and bending workability suitable for an electronic component can be realized together.

Third element

The third element may add a predetermined third element in order to contribute to the refinement of the crystal grains. Specifically, even when the solution is subjected to a solution treatment at a high temperature at which Ti is sufficiently dissolved, crystal grains are easily refined, and strength is easily improved. In addition, the third element promotes formation of a modulation structure. Moreover, it also has the effect of suppressing precipitation of TiCu ₃ . Therefore, the original hardening ability of titanium copper is obtained.

In titanium copper, the highest effect is Fe. And the effect according to Fe can be expected also in Mn, Mg, Co, Ni, Si, Cr, V, Nb, Mo, Zr, B, and P, Although the effect shows even if it is added alone, the compound addition of 2 or more types is carried out You may also

When these elements contain 0.05 mass% or more in total, the effect starts to appear, but when it exceeds 0.5 mass% in total, the solid solution of Ti is narrowed and it becomes easy to precipitate coarse 2nd phase particle, and intensity improves slightly. However, bending workability deteriorates. At the same time, the coarse second phase particles promote surface roughness of the bent portion to promote mold wear in press work. As the third element group, one or more elements selected from the group consisting of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, By mass, and preferably 0.05 to 0.5% by mass in total.

The more preferable ranges of these 3rd elements are 0.17-0.23 mass% in Fe, 0.15-0.25 mass% in Co, Mg, Ni, Cr, Si, V, Nb, Mn, Mo, Zr, B, P In 0.05-0.1 mass%.

Second phase particles

In the present invention, "second phase particles" refers to particles having a composition different from that of the parent phase. The second phase particles are particles mainly composed of Cu and Ti which precipitate during various heat treatments and form boundaries with the mother phase, and specifically, TiCu ₃ particles or component X of the third element group (specifically, Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B and P)) as a Cu-Ti-X-based particles containing.

By observing the precipitation state of the second phase particles, the degree of material reinforcement by spinodal decomposition can be indirectly evaluated. In this embodiment, in the structure observation by the electron microscope of the surface after electropolishing of a rolled surface, it is spinoidal decomposition that the number density (X) of the 2nd phase particle | grains of particle diameter 0.5 micrometer or more is 0.04-0.11 piece / micrometer <2>. Is appropriate for properly developing a modulation structure and obtaining a good balance in strength and bending workability, more preferably 0.04 to 0.10 pieces / μm 2, still more preferably 0.05 to 0.09 pieces / μm 2. If the number density X is less than 0.04 pieces / μm 2, the strength YS may be insufficient. If the number density X is more than 0.11 pieces / μm 2, the bending workability may be deteriorated. Compatibility of workability may not be attained.

Moreover, in the titanium copper which concerns on this embodiment, it is appropriate that the number ratio (Y) of the grain boundary precipitation of the 2nd phase particle of a particle size of 0.5 micrometer or more is 45 to 80%, More preferably, it is 50 to 78%, More preferably, Is 59 to 71%. If the number ratio (Y) is lower than 45%, the strength (YS) may be insufficient. If the number ratio (Y) is higher than 80%, the bending workability (MBR / t) may deteriorate. Therefore, the strength and bending workability May not be compatible.

In this embodiment, when the particle diameter of a 2nd phase particle is observed with the electron microscope of the surface after electrolytic polishing of a rolling surface, it defines as the diameter of the largest circle inscribed in a 2nd phase particle (refer FIG. 1 (a)). I shall do it. That is, the "second phase particle of particle size 0.5 micrometer or more" refers to the particle | grains whose diameter (refer FIG. 1 (a)) of the largest circle inscribed in a 2nd phase particle is 0.5 micrometer or more. Moreover, the following calculation method is employ | adopted about the calculation method of the number of particle at the time of evaluating number density (X). That is, in the second phase particles having a particle size of 0.5 μm or more dispersed in the observation field of view,

(A) For the second phase particles having a particle diameter of 0.5 μm or more and less than 1.0 μ

(a) Particle whose diameter of the minimum circle circumscribed to 2nd phase particle | grains (refer FIG. 1 (a)) is 0.5 micrometer or more and less than 1.0 micrometer: "1 piece"

(b) Particles having a diameter of the minimum circle circumscribed to the second phase particles (see FIG. 1 (a)) of 1.0 µm or more: count as "two",

(B) About the second phase particles having a particle diameter of 1.0 μm or more

In the case where a mesh having a 0.5 μm interval is attached to the observation field of view, “1” means a portion of the particle enclosed in 0.5 μm squares, and “1/2” a portion of the particle protrudes outward of 0.5 μm square beyond the mesh. (Refer to FIG. 1 (b)).

Regarding "number ratio (Y) of grain boundary precipitation of particle | grains of 0.5 micrometer or more of particle diameters", it exists along the crystal grain boundary among 2 phase particle of 0.5 micrometers or more of particle diameters disperse | distributed to the observation visual field counted in the above-mentioned procedure. The number of particles to calculate was calculated. The crystal grain boundary was defined by the interface which differs in contrast using the reflected electron image obtained by SEM observation, and the calculation method of the number of particle | grains was the same as the calculation method of number density (X).

The manufacturing method of the copper alloy which concerns on this invention

The copper alloy which concerns on this invention can be manufactured by adding predetermined modification to the manufacturing method of the well-known titanium copper as described in patent documents 1-4 mentioned above. In other words, after the final solution treatment, before the cold rolling, a heat treatment capable of causing spinodal decomposition is performed.

In the conventional method for producing titanium copper, after sufficiently solidifying titanium in the form of a matrix by the final solution treatment, cold rolling is performed to increase the strength to a certain degree, and finally, spinodal decomposition is caused by aging treatment to produce high strength titanium copper. To get. In this case, the final aging treatment is important, and the final solution treatment has been made to sufficiently dissolve titanium in the form of a matrix to cause maximum spinodal decomposition at an appropriate temperature and time in the aging treatment. If the temperature is too low and the time is too short, the development of the modulation structure caused by spinodal decomposition is likely to be insufficient in aging treatment, and the bending structure is formed by growing the modulation structure caused by spinodal decomposition by increasing the time and increasing the temperature. While maintaining the intensity goes up. However, when the temperature of the material is high and the time is too long, the beta phase which does not contribute to the strength or the beta phase which worsens the bendability easily becomes easy to bend, and the bending workability is maintained in the state where the strength is not increased or the strength is decreased. This gets worse.

On the other hand, in the present invention, the heat treatment is added after the final solution treatment, and spinoidal decomposition is caused in advance, and then, after performing cold rolling at a conventional level, aging at a conventional level, or aging at a lower temperature and shorter time, the titanium copper To increase the strength. That is, here, according to the alloy composition of titanium copper, heat processing is not performed to the processing conditions in which the hardness reaches the peak vicinity, but heat processing is complete | finished in the preceding stage (on the conditions which become an ageing). When the titanium copper after the solution treatment is heat treated, the conductivity increases with the progress of spinodal decomposition. Therefore, in the present invention, the degree of proper heat treatment is defined as a change in the conductivity before and after the heat treatment as an index. According to the research of the present inventors, it is preferable to perform heat processing on the conditions by which electric conductivity rises 0.5 to 8% of IACS. Further, the β 'phase and the β phase are not a problem as long as they are precipitated in a small amount, but when precipitated in a large amount, the strength-improving effect intended by the present invention is not obtained, or the bending workability is significantly deteriorated even if the strength is high, more preferably 1 It is preferable to carry out on the conditions to raise -4% IACS. Specific heating conditions corresponding to such an increase in electrical conductivity are conditions for heating the material temperature to 300 to 700 ° C for 0.001 to 12 hours.

The degree of increase of the appropriate electrical conductivity by aging is prescribed | regulated as follows. That is, in the heat treatment which concerns on this embodiment, when titanium concentration (mass%) is set to [Ti], the raise value C (% IACS) of electrical conductivity can satisfy the following relational expression (1).

0.5? C? (-0.50 [Ti] ² -0.50 [Ti] +14)... (One)

According to the above formula (1), for example, in the case of a Ti concentration of 2.0% by mass, it is preferable to carry out under conditions that increase the conductivity of 0.5 to 11% IACS, and in the case of a Ti concentration of 3.0% by mass, the conductivity is 0.5. It is preferable to carry out on the conditions which raise ~ 8% IACS, and, in the case of 4.0 mass% of Ti concentration, it is preferable to carry out on the conditions which raise 0.5-4% IACS of electrical conductivity.

More preferably, in the heat treatment according to the present embodiment, when the titanium concentration (mass%) is set to [Ti], the increase value C (% IACS) of the conductivity satisfies the following relational expression (2).

1.0? C? (0.25 [Ti] ² -3.75 [Ti] + 13)... (2)

According to said Formula (2), for example, in the case of Ti concentration of 2.0 mass%, it is preferable to carry out on the conditions which raise an electrical conductivity 1.0-6.5% IACS, and in the case of Ti concentration 3.0 mass%, a conductivity is 1.0. It is preferable to carry out on the conditions which raise ~ 4% IACS, and, in the case of 4.0 mass% of Ti concentration, it is preferable to carry out on the conditions which raise 1.0-2% IACS of electrical conductivity.

In addition, when the hardening of the copper alloy becomes the peak in the heat treatment after the final solution treatment, the difference in electrical conductivity is 10% IACS, Ti at 3.0% of Ti concentration of 13% IACS, and of 3.0% of Ti concentration, for example. It will increase about 5% IACS in concentration 4.0%. That is, in the heat treatment after the final solution treatment according to the present embodiment, the amount of heat applied to the copper alloy is much smaller than the aging at which the hardness becomes the peak. In the heat processing which concerns on this embodiment, high strength titanium copper can be manufactured by heat processing at high temperature (for example, 400 degreeC or more) for a short time (0.5 hours or less).

Therefore, it is preferable to perform heat processing on any of the following conditions.

Material temperature 300 degreeC or more and less than 400 degreeC heating for 0.5 to 12 hours

Material temperature 400 degreeC or more and less than 500 degreeC heating for 0.01 to 0.5 hours

0.005 to 0.01 hours heating at a material temperature of 500 ° C. or higher and less than 600 ° C.

Material temperature 600 degreeC or more and less than 700 degreeC, 0.001-0.005 hours of heating

As for heat processing, it is more preferable to carry out on any of the following conditions.

Material temperature 400 degreeC or more and less than 450 degreeC heating for 0.25 to 0.5 hours

0.01 to 0.25 hours heating at a material temperature of 450 ° C. or higher and less than 500 ° C.

0.0075 to 0.01 hour heating at a material temperature of 500 ° C. or higher and less than 550 ° C.

Material temperature 550 degreeC or more and less than 600 degreeC heating for 0.005 to 0.0075 hours

Material temperature 600 degreeC or more and less than 650 degreeC, 0.0025 to 0.005 hours of heating

Hereinafter, preferred embodiment is described for every process.

1) Ingot Manufacturing Process

The ingot is produced by melting and casting basically in a vacuum or in an inert gas atmosphere. In the case of dissolution, if the additional element has a dissolution residue, it does not act effectively on the improvement of strength. Therefore, in order to remove melt | dissolution residues, it is necessary to hold | maintain for a predetermined time after addition of high-melting-point addition elements, such as Fe and Cr, after fully stirring. In addition, since Ti melt | dissolves in Cu relatively well, what is necessary is just to add after melt | dissolution of a 3rd element group. Therefore, 0 to 0.50 mass% in total of 1 type, or 2 or more types chosen from the group which consists of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P to Cu It adds so that it may contain, and then adds Ti so that it may contain 2.0-4.0 mass%, and an ingot is manufactured.

2) Homogenization annealing and hot rolling

Here, it is preferable to remove as much of the crystallized water generated during solidification segregation and casting as possible. In the subsequent solution treatment, it is for dispersing the precipitate of the second phase particles finely and uniformly, because it is effective in preventing the mixing.

After the ingot production step, 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 brittleness, it is preferable that the pass before hot rolling and during hot rolling be 960 degrees C or less, and the pass whose original workability from the original thickness to 90% is 900 degrees C or more. And in order to produce suitable recrystallization for every pass and to reduce segregation of Ti effectively, you may implement the reduction amount for every pass in 10-20 mm.

3) second solution treatment

After that, it is preferable to perform the solution treatment after appropriately repeating cold rolling and annealing. The reason why the solution is performed in advance is that the burden in the final solution treatment is reduced. In other words, in the final solution treatment, since the solution is already solutioned, not the heat treatment for dissolving the second phase particles, only a recrystallization may be performed while maintaining the state, so that light heat treatment is sufficient. Specifically, the first solution treatment may be performed at a heating temperature of 850 to 900 占 폚 for 2 to 10 minutes. It is preferable to make it as fast as possible also in the temperature increase rate and cooling rate at that time, and to prevent a 2nd phase particle from precipitating.

4) intermediate rolling

The higher the degree of workability in the intermediate rolling before the final solution treatment, the more uniformly and finely the second phase particles in the final solution treatment are obtained. However, when the final solution treatment is performed at an excessively high workability, recrystallized texture may develop, and plastic anisotropy may occur, thereby degrading press forming. Therefore, the workability of intermediate rolling becomes like this. Preferably it is 70 to 99%. The workability is defined as ｛(thickness before rolling-thickness after rolling) / thickness before rolling) × 100%.

5) Final solution treatment

In the final solution treatment, it is preferable to completely solidify the precipitate, but when heated to a high temperature until completely removed, the grains coarsen, so the heating temperature is a temperature near the solid solution of the second phase particle composition ( The temperature (employed temperature) in which the solid solution of Ti is the same as the addition amount in the range of 2.0 to 4.0 mass% of Ti addition amount is about 730-840 degreeC, for example, about 800 degreeC when the addition amount of Ti is 3.0 mass%) . The rapid heating up to this temperature and the rapid cooling rate also suppress generation of coarse second phase particles. Although not limited to the following conditions, typically, the copper alloy material before the solution is 0-20 degreeC high temperature compared with the solid solution temperature of Ti which is 550-1000 degreeC, Preferably the temperature which is 0-10 degreeC high is Can be heated until The shorter the heating time at the solid solution temperature, the finer the grains. Therefore, it is preferable to water-cool after material heats 0.5 to 3 minutes at the temperature which the solid solution of Ti of 550-1000 degreeC becomes larger than the addition amount.

6) heat treatment

After the final solution treatment, heat treatment is performed. The conditions of the heat treatment are as described above.

7) Final cold rolling

After the heat treatment, final cold rolling is performed. The final cold working can increase the strength of the titanium copper. At this time, since a sufficient effect is not acquired at workability less than 10%, it is preferable to make workability into 10% or more. However, the higher the workability, the more easily grain boundary precipitation occurs in the next aging treatment, so the workability is 50% or less, more preferably 25% or less.

8) Aging Treatment

After the final cold rolling, an aging treatment is performed. The conditions for the aging treatment may be any conventional conditions. When the aging treatment is carried out lightly, the balance between the strength and the bendability is further improved. Specifically, the aging treatment is preferably performed under the conditions of heating at a material temperature of 290 to 400 ° C for 3 to 12 hours. When aging is not performed, when the aging treatment time is short (less than 2 hours), or when the aging treatment temperature is low (less than 290 ° C.), the strength and the electrical conductivity may decrease. Moreover, when an aging time is long (13 hours or more) or when an aging temperature is high (450 degreeC or more), although electrical conductivity becomes high, strength may fall.

As for an aging treatment, it is more preferable to carry out on any of the following conditions.

Material temperature 290 degreeC or more and below 320 degreeC heating for 7 to 12 hours.

Material temperature 320 degreeC or more and less than 340 degreeC, It heats for 6 to 11 hours.

Material temperature 340 degreeC or more and less than 360 degreeC heating for 5 to 8 hours.

Material temperature 360 degreeC or more and less than 400 degreeC heating for 2 to 7 hours.

It is still more preferable to perform the aging treatment under any of the following conditions.

8 to 11 hours heating at a material temperature of 290 ° C. or higher and lower than 320 ° C.

Material temperature 320 degreeC or more and less than 340 degreeC, heating for 7 to 10 hours.

Material temperature 340 degreeC or more and less than 360 degreeC, heating for 6 to 7 hours.

Material temperature 360 degreeC or more and less than 400 degreeC heating for 3 to 7 hours.

It will be understood by those skilled in the art that processes such as grinding, polishing, and shot blast pickling for surface oxidation scale removal can be appropriately performed between the respective steps.

Characteristics of the Copper Alloy According to the Present Invention

In one embodiment, the copper alloy obtained by the manufacturing method which concerns on this invention can have the following characteristics.

(A) 0.2% yield strength of rolling parallel direction 900-1250 MPa

(B) The MBR / t value, which is the ratio to the plate thickness t of the minimum radius (MBR) where cracking does not occur by performing the W bending test of the badway, is 0.5 to 2.5.

The copper alloy obtained by the manufacturing method which concerns on this invention can have the following characteristics in one preferable embodiment.

(A) 0.2% yield strength of rolling parallel direction 900-1050 MPa

(B) The MBR / t value, which is the ratio to the plate thickness t of the minimum radius (MBR) where cracking does not occur by performing the W bending test of the badway, is 0.5 to 2.0.

In another preferable embodiment, the copper alloy obtained by the manufacturing method which concerns on this invention can have the following characteristics.

(A) 0.2% yield strength of rolling parallel direction is 1050-1250 MPa

(B) The MBR / t value is 1.5 to 2.5, which is the ratio to the plate thickness t of the minimum radius (MBR) where cracking does not occur by performing the W bending test of the badway.

Generally the copper alloy obtained by the manufacturing method which concerns on this invention is 9-18% IACS, and is 10-15% IACS typically.

Use of the copper alloy according to the present invention

The copper alloy which concerns on this invention can be processed into the new products of various plate thickness, and is useful as a material of various electronic components. The copper alloy according to the present invention is particularly excellent as a small spring material which requires high dimensional accuracy and is not limited, but can be preferably used as a material for switches, connectors, jacks, terminals, relays, and the like.

Example

Examples of the present invention will be described below with reference to comparative examples. However, these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

Example 1 (Influence of Manufacturing Process on Properties of Titanium Copper)

In the production of the copper alloy of the present invention, since a Ti which is an active metal is added as a second component, a vacuum melting furnace is used as a solvent. In addition, in order to prevent the occurrence of unexpected side effects by the incorporation of impurity elements other than the elements specified in the present invention, raw materials were carefully selected and used.

First, Mn, Fe, Mg, Co, Ni, Cr, Mo, V, Nb, Zr, Si, B, and P are added to Cu in the compositions shown in Table 1, and then Ti of the compositions shown in the same table is added. Each added. After sufficiently considering the holding time after addition so that the additional elements did not have dissolved residues, they were injected into the mold in an Ar atmosphere to prepare about 2 kg of ingots, respectively.

After homogenization annealing which heated at 950 degreeC for 3 hours with respect to the said ingot, it hot-rolled at 900-950 degreeC, and obtained the hot rolled sheet of 10 mm of plate | board thickness. After descaling by face-cutting, it was cold rolled to a plate thickness (1.5 mm) of the casting, and the first solution treatment in the casting was performed. The conditions of the 1st solution treatment were heated at 850 degreeC for 7.5 minutes. Subsequently, after cold rolling to intermediate plate thickness (0.10 mm), it inserted into the annealing furnace which can be rapidly heated, and performed the final solution treatment. Heating conditions at this time were made into about 1 minute at about 820 degreeC. Next, heat treatment was performed under the conditions shown in Table 2. After descaling by pickling, it was cold rolled to a plate thickness of 0.075 mm, aged in an inert gas atmosphere, and used as test specimens of the invention examples and comparative examples. The conditions of the heat treatment and the aging treatment are shown in Table 2.

About each test piece obtained, the characteristic evaluation was performed on condition of the following. The results are shown in Table 2.

<Intensity>

JIS 13B test piece was produced using the press machine so that the tension direction may become parallel to a rolling direction. The tensile test of this test piece was implemented according to JIS-Z 2241, and the 0.2% yield strength (YS) of the rolling parallel direction was measured.

&Lt; Bending workability &

According to JIS H 3130, the W bending test of the badway (the bending axis is the same direction as the rolling direction) was carried out to measure the MBR / t value, which is the ratio to the plate thickness t of the minimum radius MBR where no cracking occurs. .

<Conductivity>

In accordance with JIS H 0505, the electrical conductivity (% IACS) was measured by the four-terminal method.

<Number density (X)>

About each obtained test piece, the number density (X) of the precipitate and the number ratio (Y) of grain boundary precipitation were calculated | required under the following conditions. The structure appeared by electrolytically polishing the rolled surface to the solution of 67% phosphoric acid + 10% sulfuric acid + water on condition of 15V60 second, and it washed with water and used for observation. The BSE image of the tissue was observed using an FE-SEM (electrolytic radial scanning electron microscope, manufactured by Philips, XL30SFEG) at an acceleration voltage of 15 kV, a spot diameter of 4.0 µm, and WD = 6.0 mm, and the precipitate (second phase particles) was observed. The number density (X) was counted. Specifically, marks the second phase particles containing Ti-Cu-based precipitates (grain-bound reaction phase) of complex shape which precipitate along the grain boundaries as grain-bound reaction particles present in the observation field of 100 µm x 100 µm. And the number density was counted by making one particle | grains whose diameter (refer FIG. 1 (a)) of the largest circle inscribed in the 2nd particle | grains marked with 0.5 micrometer or more was made into one.

<Number ratio (Y)>

The ratio of the number of precipitates with a particle size of 0.5 µm or more present at the grain boundary to the total number of second phase particles having a particle size of 0.5 µm or more in the observation field among the second phase particles dispersed in the observation field counted in the order described above. (Y) was measured. The grain boundary was defined as the interface with contrast contrast using the reflected electron image obtained by SEM observation. Regarding "number ratio (Y) of grain boundary precipitation of particle | grains of 0.5 micrometer or more of particle diameters", (A) particle | grains of 0.5 micrometer or more and less than 1.0 micrometer among particle | grains of 0.5 micrometer or more of particle diameters disperse | distributed to an observation visual field. About the two-phase particle | grains, (a) The particle | grains of the minimum circle which circumscribes a 2nd phase particle (refer FIG. 1 (a)) are 0.5 micrometer or more and less than 1.0 micrometer: "1 piece", (b) 2nd phase particle Particles having a diameter of the smallest circle to be circumscribed (see Fig. 1 (a)) of 1.0 µm or more: count as "two" and (B) meshes of 0.5 µm interval in the observation field of view for the second phase particles having a particle diameter of 1.0 µm or more. In the case of the application, a portion surrounded by 0.5 µm square is "one", and a portion that protrudes outside the 0.5 µm square beyond the mesh is "1/2" (see Fig. 1 (b)). It was.

No. 1 is a conventional example. In No. 1, the heat treatment (annealing) after the solution was not performed, and since the final aging temperature was lower, the number density was small and the number ratio of grain boundary precipitation was also small, resulting in insufficient strength. On the other hand, in the case of No. 2 to which the heat treatment was applied, it turns out that intensity improves.

No. 3 is a comparative example in which aging was performed at low temperature without heat treatment. In No. 3, the annealing after the solution was not performed, and thus the final aging temperature was lower. Therefore, the number density was small and the number ratio of grain boundary precipitation was small, so that the strength was insufficient. On the other hand, in the case of No. 4 subjected to the heat treatment, the strength is improved, and in addition, No. 4 performs the aging treatment at a low temperature, and therefore, both the strength and the bending workability are compatible.

Although No. 5 is an invention example, it is an example which made the temperature of an aging process low. No. 6 is the invention example which made the heating temperature at the time of heat processing as high as possible. No. 7 is the invention example which made the heating temperature at the time of heat processing as low as possible.

No. 8 is a comparative example where the heating temperature of the heat treatment is too high, and No. 9 is a comparative example where the heating temperature of the heat treatment is too low. Since No. 8 was overannealed, the number density became high and the strength was insufficient. Due to the annealing shortage, No. 9 reduced the number density and the precipitation at grain boundaries. Moreover, since there was little precipitation amount, intensity | strength was insufficient.

No. 10 is the invention example which enlarged the grade of the electrical conductivity by heat processing. Nos. 11 and 12 are comparative examples in which the degree of increase in electrical conductivity by heat treatment is too large. In No. 11, since the electrical conductivity was excessively increased by annealing after solutionization, the second phase particles were increased, and after that, the second phase particles were further increased after the rolling and aging processes, and the number density was high. In No. 11, the strength increased, but the bending workability deteriorated. Since the number density of No. 12 increased more than No. 11, the ratio of grain boundary precipitation also increased, the intensity | strength fell rather than No. 11, and bending workability further deteriorated.

No. 13 is a conventional example. Since the annealing after the solution was not performed and the final aging temperature was further lower, the number density was small, and the number ratio of grain boundary precipitation was also small, resulting in insufficient strength.

Nos. 14 and 16 show the effects of the present invention when a third element is added.

No. 15 and 17 are conventional examples. In No, 15, since the annealing after solution-solving was not performed and the final aging temperature was further lower, the number density was small and the number ratio of grain boundary precipitation was also small, so that the strength was insufficient. In No. 17, since the annealing after the solution was not performed, the number density was small, and the ratio of grain boundary precipitation was also small, so that the strength was insufficient.

No. 18-20 shows the example which performed the annealing after solution formation for a long time. In Comparative Examples 18-20, since the annealing time after solution formation was long, the number density increased, the strength fell, and the bending workability deteriorated.

Example 2 (Influence of Composition on Properties of Titanium Copper)

The test piece was manufactured on the same manufacturing conditions as the test piece of No. 4 except having changed the composition of the titanium copper as Table 3. The result of the characteristic evaluation of each obtained test piece is shown in Table 4.

No. 21 is a comparative example where the titanium concentration is too low, and No. 24 is an example where the titanium concentration is too high. In NO.21, since titanium concentration was low, the number of 2nd phase particle | grains was small, the number ratio which precipitates in a grain boundary was also low, and the intensity | strength was insufficient. Since No. 24 had a high titanium concentration, grain boundary precipitation first occurred, the number ratio became high, and bending workability deteriorated.

Claims (5)

It contains 2.0-4.0 mass% of Ti, and as a 3rd element, one or more among Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, P total 0 or more in 0.5 mass As a copper alloy containing less than% and consists of remainder copper and an unavoidable impurity,
In the structure observation by the electron microscope of the surface after electropolishing of the rolled surface, the number density (X) of the 2nd phase particle | grains of particle size 0.5 micrometer or more is 0.04-0.11 piece / microm <2>,
The number alloy (Y) in which the 2nd phase particle of 0.5 micrometers or more of particle diameters precipitates along a grain boundary is 45 to 80%, The copper alloy characterized by the above-mentioned. The method of claim 1,
The copper alloy,
In 550-1000 degreeC, the solution solution which heats and quenchs is heated until it becomes 0-20 degreeC high temperature compared with the solid solution temperature which solid solution of Ti becomes equal to the addition amount,
Subsequent to the solution treatment, when titanium concentration (mass%) is set to [Ti], the increase value C (% IACS) of the electrical conductivity is as follows.
0.5 ≤ C ≤ (-0.50 [Ti] ² -0.50 [Ti] +14)
Heat treatment to increase the electrical conductivity is carried out under the conditions of heating at 0.001 to 12 hours at a material temperature of 300 to 700 ° C,
Heat treatment followed by final cold rolling,
A copper alloy produced by performing final cold rolling followed by aging treatment. The new product using the copper alloy of Claim 1 or 2. The electronic component produced using the copper alloy of Claim 1 or 2. The connector produced using the copper alloy of Claim 1 or 2.

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