KR101895558B1 - Cu-Ti-based copper alloy sheet material and method of manufacturing same - Google Patents

Abstract

The present invention provides a Cu-Ti based copper alloy sheet material having both high strength, excellent bending workability and stress relaxation resistance, and improved spring back.

1.0% or less of Co, and 1.5% or less of Ni, or one or more of Sn, Zn, Mg, Zr, Al , Si, P, B, Cr, Mn, and V in an appropriate range and having the balance of Cu and inevitable impurities, satisfies the following expression (1) ) ≪ / RTI > of the copper alloy. The average crystal grain size is adjusted to 10 to 60 占 퐉.

I {420} / I ₀ {420} > 1.0 (1)

I {220} / I ₀ {220}? 3.0 (2)

Cu-Ti type copper alloy sheet material, average crystal grain size, crystal orientation

Description

[0001] The present invention relates to a Cu-Ti based copper alloy sheet material,

The present invention relates to a Cu-Ti-based copper alloy sheet material suitable for electrical and electronic parts such as connectors, lead frames, relays, switches, etc., and particularly relates to a copper alloy sheet material which exhibits excellent bending workability and stress- , And a production method thereof.

Materials used for parts such as connectors, lead frames, relays, switches, etc. constituting electrical and electronic parts are required to have high "strength" that can withstand the stress applied during assembly and operation of electric and electronic parts. In addition, since the electric / electronic parts are generally formed by bending, excellent "bending workability" is required. Further, in order to secure the contact reliability between the electric / electronic parts, it is also required to have excellent durability against the phenomenon (contact stress relaxation) that the contact pressure decreases with time, that is, "stress relaxation resistance".

Particularly in recent years, electrical and electronic parts tend to be highly integrated, miniaturized, and lightweight, and accordingly, there is a growing demand for thinner copper and copper alloys. For this reason, the level of " strength " required for the material becomes more severe. More specifically, a tensile strength of at least 800 MPa, preferably at least 900 MPa, more preferably at least 1000 MPa, is required.

In order to cope with the miniaturization of electrical and electronic parts and the complicated shape, it is strongly desired to improve the shape and dimensional accuracy of the bending workpiece. The demand for " bending workability " is important because not only the bending portion is not cracked, but also the shape and dimensional accuracy of the bending workpiece can be ensured. Springback is a troublesome problem that occurs more or less in the bending process. The springback is a phenomenon that the elastic deformation is recovered when the material is extracted from the mold after machining, so that it is inconsistent with the shape when the material is processed in the mold.

As the strength level required for the material becomes more stringent, the problem of springback becomes more susceptible to surface appearance. For example, in a connector terminal having a box-shaped bent portion, the shapes and dimensions of the terminals may differ depending on the spring back. Recently, there has been recently applied a notching process (notching process) to a portion to be subjected to a bending process of a workpiece, and thereafter applying a bending process according to the notch (hereinafter referred to as "bending process after notching") And more. However, in this processing method, work is hardened in the vicinity of the notched portion by notching, so that cracks tend to occur in the subsequent bending processing. Therefore, the " bending process after notching " can be said to be a bending process that is very strict in materials.

In addition, as the use of electric / electronic parts in harsh environments increases, the demand for " stress relaxation resistance " has also become stricter. For example, when used in an environment exposed to a high temperature such as an automotive connector, "stress relaxation resistance" becomes particularly important. Stress relaxation means that one kind of stress relaxation means that the contact pressure of the spring portion of the material constituting the electric / electronic part is lowered with time under a relatively high temperature (for example, 100 to 200 DEG C) It is a creep phenomenon. That is, in the state where stress is applied to the metal material, the potential shifts due to the self diffusion of the atoms constituting the matrix or the diffusion of the solid solution atoms, and plastic deformation is caused, whereby the applied stress is relaxed.

However, there is a trade-off relationship between "strength" and "bending workability" or "bending workability" and "stress relaxation resistance". Conventionally, such electrification parts are appropriately selected and used according to the application, that is, good materials of "strength", "bending workability" or "stress relaxation resistance".

The Cu-Ti-based copper alloy has a high strength following the Cu-Be-based alloy among the copper alloys and has stress relaxation resistance superior to that of the Cu-Be-based alloy. In addition, it is more advantageous than Cu-Be alloy at cost and environmental load. For this reason, the Cu-Ti-based copper alloy is a connector material or the like as a substitute for the Cu-Be-based alloy. However, it is generally known that a Cu-Ti-based alloy is an alloy system such as a Cu-Be-based alloy in which it is difficult to achieve both "strength" and "bending workability".

Therefore, the Cu-Ti alloy sheet material is shipped in a relatively soft state before the aging treatment, and is often subjected to aging treatment after bending, press forming, and curing. However, the method of aging treatment after bending and press molding tends to cause discoloration due to adhesion of oil, and often requires a dedicated heat treatment furnace, which is disadvantageous for improvement in productivity and cost reduction. For this reason, as a plate material of Cu-Ti-based copper alloy, there is an increasing demand for an aging treatment material (so-called mill hardend material) which does not require aging treatment after bending and press forming. This factory heat treatment material is a plate material subjected to an aging treatment at a level not reaching the maximum hardness. If this is used, there is an advantage in that aging treatment after part processing can be omitted in many applications which are not required up to the maximum strength level. However, although the aging treatment described above is relatively mild, it can not be denied that the moldability is lowered.

In order to improve the " bending workability ", generally, a method of refining the crystal grains is effective, and the same applies to Cu-Ti based copper alloys. However, the smaller the crystal grain size, the larger the area of the grain boundaries existing per unit volume. For this reason, grain refinement becomes a factor for promoting stress relaxation, which is a kind of creep phenomenon. In an application for use in a relatively high temperature environment, since the diffusion rate along the grain boundary of the atoms is significantly faster than that in the grain, a reduction in the "stress relaxation resistance" caused by grain refinement becomes a serious problem.

In the Cu-Ti-based copper alloy, the "precipitate" mainly exists in the form of a modulation structure (spinodal structure) in the crystal grain, and is a second phase particle having a function of pinning the growth of the recrystallized grains , And it is not easy to achieve finer crystal grains in the solution treatment process.

In recent years, it has been proposed that crystal grains are made finer and crystal orientation (texture) is controlled in improving the properties of Cu-Ti based alloys (Patent Documents 1 to 4).

[Patent Document 1] JP-A-2006-265611

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2006-241573

[Patent Document 3] JP-A-2006-274289

[Patent Document 4] Japanese Laid-Open Patent Publication No. 2006-249565

It is well known that fine grain refinement and control of crystal orientation (texture) are effective for improving the bending workability of a copper alloy sheet material. The X-ray diffraction pattern from the surface (rolled surface) of the plate is generally {111}, {200}, {200}, or the like when controlling the crystal orientation (aggregate structure) of the Cu- 220}, and {311}, and the X-ray diffraction intensity from the other crystal planes is very small as compared with those from these crystal planes. Generally, the diffraction intensity on the {200} plane and the {311} plane becomes larger after solution treatment (recrystallization) treatment. The subsequent cold rolling reduces the diffraction intensity of these surfaces and relatively increases the X-ray diffraction intensity of the {220} plane. The X-ray diffraction intensity of the {111} face does not usually change much by cold rolling.

In Patent Document 1, in order to make crystal grains finer, the cold rolling rate before the solution treatment is defined as 89% or more. The distortion introduced at such a high rolling rate serves as the nucleus of recrystallization, and fine grain size of about 2 to 10 mu m is obtained. However, such grain refinement often accompanies deterioration of " stress relaxation resistance ". Further, since the hot rolling temperature is as high as 850 캜, the inventors of the present invention can not sufficiently improve the bending workability.

In Patent Document 2, the X-ray diffraction intensity ratio of {220} plane and {111} plane is defined as I {220} / I {111}> 4 in order to improve strength and conductivity. Adjustment of such a {220} face to a texture having a kitchen top component is effective for improving strength and conductivity, but according to the study by the inventors, it is accompanied by a decrease in bending workability. In fact, Patent Document 2 does not mention bending workability.

In Patent Document 3, in order to improve the bending workability, in the four regions including {110} <115>, {110} <114>, and {110} And the maximum value of the diffraction intensity is from 5.0 to 15.0 (however, the ratio to the random orientation). In order to obtain such a texture, the cold rolling rate before the solution is specified to be 85 to 97%. (111) < 110} &lt; 100 &gt;) and the {111} positive electrode viscosity is similar to the {111} positive electrode viscosity of 70/30 brass (See "Metal Data Book", 3rd Edition, page 361). As described above, in the conventional method of adjusting the crystal orientation distribution based on the general texture, it is difficult to significantly improve the bending workability. Actually, the bending workability R / t in Patent Document 3 stays at 1.6.

Patent Document 4 proposes a texture that satisfies I {311} / I {111}? 0.5. However, according to the study by the inventors and the like, it is difficult to stably and remarkably improve the bending workability in such a group structure.

In addition, the use of the above-mentioned &quot; bending process after notching &quot; in the copper alloy sheet material is effective for improving the shape and dimensional accuracy of the bending process product. However, in the Cu-Ti-based alloys in which the texture is controlled as in Patent Documents 1 to 4, it is not considered to prevent the occurrence of cracks by the "bending process after notching". According to the inventors' study, it has been found that the bending workability after notching is not sufficiently improved.

The Cu-Ti alloy sheet material is often supplied as a factory heat treatment material, but there is a problem that it is difficult to ensure the shape and dimensional accuracy of the bending processed product by spring back as a factory heat treatment material. Although the above-mentioned "bending method after notching" is effective for reduction of the spring back, since this processing method is work-hardening in the vicinity of the notch portion by notching, cracks tend to occur in the subsequent bending processing. As for the heat-treated material of the Cu-Ti-based alloy, it is a phenomenon that does not reach industrially employing the "bending process after notching".

As described above, grain refinement is effective to some extent to improve bending workability, while it is a negative factor to overcome stress relaxation which is one kind of creep phenomenon. In view of this, even if only "bending workability" is observed, improvement of the "stress relaxation resistance" under the circumstances where the improvement of the height is difficult is not realized by using a known tissue control technique.

In the present invention, in this phenomenon, in the present invention, the "bending processability" as required in the "bending process after notching" while maintaining the "high strength" and the "bending processability" Stress relaxation property &quot; and a &quot; spring-back &quot; of the Cu-Ti-based copper alloy sheet material.

As a result of a detailed examination, the inventors of the present invention have found that when the direction perpendicular to the plate surface of the rolled plate is denoted by ND, the crystal orientation which is liable to be deformed by ND and which is easily deformed in two directions orthogonal to each other in the plate surface And the like. Then, an alloy composition range and a manufacturing condition capable of obtaining a texture obtained by mainly using crystal grains having such a specific bearing relationship have been specified. The present invention has been completed based on this view.

That is, in the present invention, it is preferable that the steel sheet contains 1.0 to 5.0% of Ti by mass% and at least one of Fe: not more than 0.5%, Co: not more than 1.0% and Ni: not more than 1.5% There is provided a copper alloy sheet material having a composition comprising Cu and inevitable impurities and satisfying the following formula (1), and preferably satisfying the following formula (2). The average crystal grain size is adjusted to 10 to 60 占 퐉, preferably 10 to 60 占 퐉.

I {420} / I ₀ {420} &gt; 1.0 (1)

I {220} / I ₀ {220}? 3.0 (2)

Herein, I {420} is the X-ray diffraction integral intensity of the {420} crystal plane in the plate surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction integral intensity of {420} crystal plane of the pure copper standard powder. Similarly, I {220} is the X-ray diffraction integral intensity of the {220} crystal plane of the copper alloy sheet, and I ₀ {220} is the X-ray diffraction integral intensity of the {220} crystal plane of the pure copper standard powder. I {420} and I ₀ {420} are measured under the same measurement conditions, and I {220} and I ₀ {220} are measured under the same measurement conditions. The average crystal grain size can be obtained by the cutting method of JIS H0501 by polishing the plate surface (rolled surface), etching the surface, and observing the surface with a microscope.

1.0% or less of Al, 1.0% or less of Si, 1.0% or less of Si, 0.1% or less of P, 0.1% or less of P, : Not more than 0.05%, not more than 1.0% of Cr, not more than 1.0% of Mn and not more than 1.0% of V in a total amount of not more than 3% by mass.

In particular, in the copper alloy sheet described above, the ratio R of the minimum bending radius R and the plate thickness t at which cracks do not occur in the 90 ° W bending test according to JIS H3110, in particular, in the LD (rolling direction) (in the central portion of the three portions) of the bending test piece when the value of R / t is 1.0 or less in both LD and TD (direction perpendicular to the rolling direction and the plate thickness direction) 90 占 representing the spring back amount is 3 占 or less in both of LD and TD when the actual bending deformation angle of? In the present specification, the bending workability evaluated by the 90 占 굴 bending test conforming to this JIS H3110 is called &quot; normal bending workability &quot;, and is distinguished from the later-described &quot; bending workability after notching &quot;.

As a process for producing the above-mentioned copper alloy sheet material, hot rolling at 950 to 500 占 폚, cold rolling at a rolling rate of 80% or more, solution treatment at 700 to 900 占 폚, finish cold rolling at a rolling rate of 0 to 65% The first rolling pass is performed in a temperature zone of 950 캜 to 700 캜 in the hot rolling step and a temperature of less than 700 캜 to 500 캜 There is provided a process for producing a copper alloy sheet material which is subjected to rolling at a rolling rate of 30% or more in a zone. In the tear rolling process, it is preferable that the rolling ratio in the temperature zone of 950 캜 to 700 캜 is 60% or more. In the solution treatment process, heat treatment is performed by setting the holding time and the reaching temperature in the region of 700 to 850 캜 such that the average crystal grain size after solution treatment is 10 to 60 탆, preferably 10 to 60 탆 desirable.

The &quot; rolling rate O% &quot; of the finish cold rolling means the case where the rolling is not performed. That is, cold rolling can be omitted. (%) In a certain temperature zone is t ₀ (mm), t ₀ (mm) is a thickness before provision of the first rolling pass, and t ₁ (mm), it is determined by the following equation (3).

_{ε = (t 0 -t 1)} / t 0 × 100 ······ (3)

Also, the maximum hardness achieved aging temperature in the alloy composition T _M (℃), in, aging processes when the maximum hardness H _M (HV), also in the range of 300 to 550 ℃ the aging temperature T _M ± 10 ° C and the aging time is set to a time at which the hardness after aging is in the range of 0.85H _M to 0.95H _M.

According to the present invention, it is possible to provide a plate material of Cu-Ti type copper alloy having basic characteristics necessary for electrical and electronic parts such as a connector, a lead frame, a relay, a switch and the like and having a tensile strength of 800 MPa or more, It has been provided that it has excellent moldability (in particular, bending workability) and stress relaxation resistance at the same time. It has been difficult to improve the bending workability and the stress relaxation resistance stably and remarkably while maintaining the high strength level by the conventional Cu-Ti-based copper alloy manufacturing technique. In addition, the "springback" at the time of machining was also remarkably reduced. Therefore, it is easy to improve the dimensional accuracy of the processed parts made of the Cu-Ti based copper alloy sheet material. The present invention is capable of responding to demands for downsizing and thinning of electric and electronic parts which are expected to progress gradually in the future.

In the present invention, by mainly controlling the texture state of the copper alloy sheet material with a texture having a certain crystal orientation, it is possible to simultaneously improve the "strength", the "bending workability" and the "stress relaxation resistance" . Hereinafter, matters for specifying the present invention will be described.

<< Organization >>

X-ray diffraction patterns from a plate surface (rolled surface) of a Cu-Ti-based copper alloy generally consist of diffraction peaks of four crystal planes of {111}, {200}, {220}, and {311} X-ray diffraction intensity from this crystal plane is extremely small as compared with that from this crystal plane. The diffraction intensity of the {420} plane is also weakened to an extent negligible in the plate material of the Cu-Ti-based copper alloy obtained in the ordinary manufacturing process. However, according to the detailed examination by the inventors and the like, it can be understood that a Cu-Ti-based copper alloy sheet material having an aggregate structure having {420} as a kitchen top component can be obtained according to the production conditions to be described later. The inventors have found that the more strongly this texture grows, the better the bending workability is improved. As to the mechanism of improvement in the bending workability, the following is considered at present.

There is a Schmid factor as an index indicating that plastic deformation (sliding) is likely to occur when an external force is applied to the crystal orientation. The angle formed by the direction of the external force applied to the crystal and the normal to the sliding surface is represented by phi and the angle formed by the sliding direction and the direction of the external force applied to the crystal is represented by cos φ · cosλ, The value is in the range of 0.5 or less. The higher the Schmid factor, the closer to 0.5 the shear stress in the sliding direction is. Therefore, when an external force is applied to a certain direction from a certain direction, the larger the Schmid factor (that is, closer to 0.5), the more easily the crystal is deformed. The crystal structure of the Cu-Ti-based copper alloy is the face-centered cubic (fcc). It is known that a sliding system of a face-centered cubic system is a sliding surface {111}, a sliding direction <110>, and the actual crystal is susceptible to deformation and work hardening as the Schmid factor increases.

Fig. 1 shows a standard inverse pole figure showing the distribution of the Schmid factor of face-centered cubic. The Schmid factor in the <120> direction is 0.490, which is close to 0.5. That is, when an external force is applied in the <120> direction, the face-centered cubic is likely to be very deformed. The Schmid factor in the other directions is 0.408 in the <100> direction, 0.445 in the <113> direction, 0.408 in the <110> direction, 0.408 in the <112> direction, and 0.272 in the <111> direction.

The texture of {420} as a component of the kitchen surface is a texture with {420} planes, ie, the {210} planes having a large proportion of crystals almost parallel to the plate surface (rolled surface). In the crystal having the {225} plane as the kitchen surface, since the direction ND perpendicular to the plate surface is the <120> direction and its Schmid factor is close to 0.5, deformation into ND is extremely easy and work hardening is also small. On the other hand, a general rolled texture of a Cu-Ti based alloy is {220} as a component of the kitchen stove. In this case, the presence of crystals that are substantially parallel to the {220} plane, There are a lot of ratios. Since crystals having a {110} plane as a kitchen surface have an ND in the <110> direction and a Schmid factor of about 0.4, the work hardening due to deformation to ND becomes larger than crystals having a kitchen surface of {210} plane. In addition, a general recrystallized texture structure of a Cu-Ti-based alloy is {311} as a kitchen top component. Since the crystals having the {30} plane of the kitchen surface have the ND direction and the Schmid factor thereof is about 0.45, the work hardening due to the deformation to the ND is larger than that of the crystals having the kitchen surface of {210} plane.

In the &quot; bending method after notching &quot;, the degree of work hardening at the time of deformation in the direction (ND) perpendicular to the sheet surface is extremely important. This is because the notching is a deformation to the ND and the degree of work hardening of the portion where the plate thickness is decreased by the notching largely dominates the bending workability in the case where it is bent along the notch. In the case of a texture having {420} satisfying the expression (1) as a kitchen top component, the work hardening by notching becomes smaller as compared with the rolled texture or recrystallized texture of a conventional Cu-Ti based alloy, It is considered that this is a factor that remarkably improves the bending workability in the &quot; bending process after notching &quot;.

In the case of a texture having {420} as the kitchen top component satisfying the expression (1), in the crystal having the kitchen top surface as the {210} plane, a separate <120> &Lt; 100 > directions, which are orthogonal to each other. In practice, it has become clear that the rolling direction LD is in the <100> direction and the direction TD perpendicular to the rolling direction is the <120> direction. For example, LD is in the [001] direction and TD is in the [-2, 1, 0] direction in the crystal having the (120) plane as the kitchen surface. The Schmid factor of such crystals is 0.408 for LD and 0.490 for TD. On the other hand, as the general rolled texture of the Cu-Ti alloy, the dish surface orientation is {110} plane, LD is in the <112> direction, TD is in the <111> direction, the Schmid factor in the plate surface is 0.408 in the LD, 0.272. In the general recrystallized texture structure of a Cu-Ti alloy, the LD is in the <112> direction, the TD is in the <110> direction, and the Schmid factor in the plate surface is 0.408 in the LD and 0.408 in the TD do. As described above, the Schmid parameters of LD and TD show that, in the case of a texture having {420} as a kitchen stomach component, it is compared with a rolling texture or a recrystallized texture of a conventional Cu-Ti alloy, It can be said that the deformation is easy. This viscosity is considered to be advantageous in preventing cracks in the bending process after notching.

In the bending process of the metal plate, since the crystal orientations of the respective crystal grains are different, not only all of them are deformed but also there are crystal grains which are easily deformed at the time of bending processing and crystal grains which are not easily deformed. As the degree of the bending process increases, the crystal grains which are liable to be deformed are gradually and more preferentially deformed, and micro concavity and convexity is generated on the surface of the bent portion of the plate due to deformation unevenness among the crystal grains, Cracks (fractures). As described above, as compared with the conventional metal plate, the metal plate having the texture that satisfies the expression (1) tends to be easily deformed into the ND and easily deformed into the plate surface. This is presumed to lead to remarkable improvement in the bending workability after notching and the normal bending workability even if the crystal grains are not particularly refined.

According to the inventors' study, such a crystal orientation can be specified by the following expression (1).

I {420} / I ₀ {420} &gt; 1.0 (1)

Herein, I {420} is the X-ray diffraction integral intensity of the {420} crystal plane in the plate surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction integral intensity of {420} crystal plane of the pure copper standard powder. In the X-ray diffraction peak of the face-centered cubic crystal, the {420} plane of reflection is generated but the {210} plane of the plane of the plane is not reflected, so that the crystal orientation of the {210} plane is evaluated by the reflection of the {420} plane. It is still more preferable that the following formula (1) is satisfied.

I {420} / I ₀ {420} &gt; 1.5 (1)

{420} is formed as a recrystallized texture structure by solution treatment which will be described later. However, in order to increase the strength of the copper alloy sheet material, cold rolling after the solution treatment is extremely effective. As this cold rolling rate increases, rolled aggregate with {220} as the kitchen top component develops. The {420} orientation density decreases with increasing {220} orientation density, but the rolling rate may be adjusted so that the above formula (1), preferably the formula (1), is retained. However, since an aggregate structure having too much {220} as a component on the kitchen top develops in some cases, it may cause a deterioration in workability. Therefore, it is preferable to satisfy the following expression (2). Further, in the sense of balancing both "strength" and "bending workability" at a high level, it is more preferable to satisfy the following formula (2) '.

I {220} / I ₀ {220}? 3.0 (2)

_{0.5≤I {220} / I 0 {} 220} ≤3.0 ······ (2) '

Here, I {220} is the X-ray diffraction integral intensity of the {220} crystal plane in the plate surface of the copper alloy sheet, and I ₀ {220} is the X-ray diffraction integral intensity of {220} crystal plane of the pure standard powder.

As disclosed in the examples described later, in the plate having such a peculiar crystal orientation, the "high strength" unique to the alloy is maintained. In addition, &quot; thermal deformation &quot; and &quot; springback &quot; are improved by such crystal orientation. Further, for the purpose of improving the bending workability, there is no need to finely grind the crystal grains, and it becomes possible to fully exert the effect of improving the "stress relaxation resistance" by adding Be or the like.

<< Average crystal grain size >>

As described above, the smaller the average crystal grain size is, the better the improvement in the bending workability. However, if the average crystal grain size is too small, the stress relaxation resistance tends to deteriorate. As a result of various investigations, if the average crystal grain size finally exceeds a value of 10 占 퐉 or more, preferably 10 占 퐉 or more, it is easy to ensure the stress relaxation resistance of a level that can be satisfied even for the purpose of the on-vehicle connector. And more preferably 15 mu m or more. However, if the average crystal grain size is excessively large, the roughness of the surface of the bent portion tends to easily occur and the bending workability may deteriorate. Therefore, the average grain size is preferably set to be not more than 60 탆, more preferably not more than 40 탆, Is more preferable. The final average crystal grain size is almost determined by the grain size at the stage after the solution treatment. Therefore, the average crystal grain size can be controlled by the solution treatment conditions to be described later.

<< Alloy composition >>

In the present invention, a Cu-Ti-based copper alloy containing Fe, Co, Ni or the like or other alloying elements as necessary is used for the binary basic component of Cu-Ti.

Ti is an element having a high age hardening action in a Cu matrix and contributes to an increase in strength and an improvement in stress relaxation resistance. In Cu-Ti based copper alloy to produce a supersaturated solid solution by solution treatment for, when the aging in a more low temperature, metastable merchant modulated structure (spinosyns month structure) when developed, and more continue to age not normal (TiCu ₃₎ Is generated. The modulation structure is formed by the continuous shaking of the solute atom concentration and does not require nucleation, unlike the precipitate formed by ordinary nucleation and growth, and is generated while maintaining complete coherency with the parent phase Structure. In the development stage, the material is remarkably hardened, and the loss of ductility is small. On the other hand, the steady state (TiCu ₃ ) is a precipitate dotted in grain boundaries and grain boundaries in general, and is easy to be coarsened, and the loss of ductility is large even though the curing function is small from the modulation structure which is a metastable phase.

Therefore, it is preferable to strengthen the Cu-Ti based copper alloy as much as possible and to suppress the generation of the steady state (TiCu ₃ ). When the Ti content is less than 1.0% by mass, it is difficult to sufficiently draw the strengthening action by the normal peaks. On the other hand, if the Ti content is excessive, stable (TiCu ₃ ) tends to be formed, and the temperature zone where the solution treatment can be performed narrows, making it difficult to draw good properties. As a result of various studies, it is necessary to set the Ti content to 1.0 to 5.0 mass% or less. Therefore, the Ti content is specified to be 1.0 to 5.0 mass%. The Ti content is more preferably from 2.0 to 4.0 mass%, and still more preferably from 2.5 to 3.5 mass%.

Fe, Co, and Ni are elements that form an intermetallic compound with Ti and contribute to the improvement of the strength, and one or more of them can be added as needed. Particularly, in the solution treatment of the Cu-Ti-based copper alloy, since this intermetallic compound suppresses the coarsening of the crystal grains, the solution treatment can be performed at a higher temperature, It becomes advantageous. However, if Fe, Co, and Ni are excessively contained, the amount of Ti consumed by the generation of these intermetallic compounds is increased, so that the amount of Ti to be dissolved is inevitably reduced. In this case, conversely, the strength is likely to be deteriorated. Therefore, Fe, Co, and Ni are added in the range of 0.5 mass% or less of Fe, 1.0 mass% or less of Co, and 1.5 mass% or less of Ni. It is effective to add at least one of them in a content range of 0.05 to 0.5 mass% of Fe, 0.05 to 1.0 mass% of Co, and 0.05 to 1.5 mass% of Ni in order to sufficiently exhibit the above action. More preferably 0.1 to 0.3 mass% of Fe, 0.1 to 0.5 mass% of Co, and 0.1 to 1.0 mass% of Ni.

Sn has an effect of strengthening solubility and improving stress relaxation resistance. In order to sufficiently exhibit this action, a Sn content of 0.1% by mass or more is preferable. However, when the Sn content exceeds 1.0% by mass, the castability and the conductivity are remarkably lowered. Therefore, in the case of containing Sn, it is necessary to set the content to 1.0% by mass or less. The Sn content is more preferably 0.1 to 1.0 mass%, and still more preferably 0.1 to 0.5 mass%.

Zn has an action of improving solderability and strength, and also has an effect of improving the casting property. It is also advantageous that a low-priced brass scrap can be used in the case of containing Zn. However, the Zn content exceeding 2.0% by mass tends to cause deterioration of electrical conductivity and stress corrosion cracking resistance. Therefore, in the case of containing Zn, the content is set to 2.0 mass% or less. In order to sufficiently attain the above-mentioned action, it is preferable to secure a Zn content of 0.1 mass% or more, more preferably to adjust the range of 0.3 to 1.0 mass%.

Mg has an effect of improving stress relaxation resistance and a de-S action. In order to sufficiently exhibit this action, it is desirable to secure a Mg content of 0.01 mass% or more. However, Mg is an element which is easily oxidized, and when it exceeds 1.0% by mass, the main composition is remarkably lowered. For this reason, in the case of containing Mg, the content should be 1.0 mass% or less. The Mg content is more preferably from 0.01 to 1.0% by mass, and still more preferably from 0.1 to 0.5% by mass.

1.0% or less of Si, 1.0% or less of Si, 0.1% or less of P, 0.05% or less of B, 1.0% or less of Cr, 1.0% or less of Mn, % Or less. For example, Zr and Al can form intermetallic compounds with Ti, and Si can form precipitates with Ti. Cr, Zr, Mn and V easily form a high melting point compound with S, Pb and the like existing as inevitable impurities. Cr, B, P and Zr have a minifying effect on the cast structure and contribute to improvement of hot workability .

When at least one of Zr, Al, Si, P, B, Cr, Mn and V is contained, it is effective that the total content thereof is 0.01 mass% or more in order to sufficiently obtain the action of each element. However, if it is contained in a large amount, the hot or cold workability is adversely affected, and the cost is also disadvantageous. Therefore, the total content of Sn, Zn, Mg and Zr, Al, Si, P, B, Cr, Mn and V is preferably controlled to 3 mass% or less, more preferably 2 mass% or less or 1 mass% , And may be regulated in a range of 0.5 mass% or less.

<< Characteristics >>

In order to further cope with miniaturization and thinning of electric / electronic parts using a Cu-Ti-based copper alloy, it is preferable to supply a plate material having a tensile strength of 800 MPa or more, preferably 900 MPa or more, more preferably 1000 MPa or more. It is possible to provide the strength characteristics by applying the manufacturing conditions described below to an alloy satisfying the above chemical composition.

Regarding "normal bending workability" (as described above), the ratio R / t of the minimum bending radius R to the plate thickness t in the LD and TD in the 90 ° W bending test is preferably 1.0 or less, Is more preferable. In addition, the shape and the dimensional accuracy of the bending workpiece are improved, and R / t is 0 for "bending workability after notching" described later. In other words, in the method of evaluating the notch bending workability of LD described later, It is desirable to have the characteristic that the film is not formed. The &quot; bending workability of LD &quot; means the bending workability (the same also in the bending workability after notching) evaluated by the bending test piece cut out so that the LD is in the longitudinal direction, and the bending axis in the test is TD. Likewise, &quot; bending workability of TD &quot; is bending workability evaluated by bending test specimens cut out so that TD is in the longitudinal direction, and the bending axis in the test is LD.

Since the value of TD is particularly important in the applications such as in-vehicle connectors, it is desirable to evaluate the stress relaxation resistance with the stress relaxation rate using the test piece having TD in the longitudinal direction. In the stress relaxation property evaluation method described later, the stress relaxation rate when maintained at 200 DEG C for 1000 hours is preferably 5% or less, more preferably 3% or less.

The "springback" at the time of bending processing becomes particularly important in the factory heat treatment material. Of the W bending test piece subjected to the evaluation test of the &quot; normal bending workability &quot;, the bending process portion ((b)) of the test piece having the R / t of 1.0 or less (specifically, the test piece obtained the minimum bending radius R at which cracking did not occur) 90 °, which represents the amount of spring back, is 3 ° or less in both of LD and TD, when the actual bending deformation angle of the center of gravity Quot; springback &quot; property. Further, with respect to the LD specimen subjected to the evaluation test of "notching bendability" described later, it is preferable that the value of? -90 degrees is within 2 占 as described above.

<< Recipe >>

The copper alloy sheet material of the present invention as described above can be produced, for example, by the following manufacturing process.

"Dissolution, Casting, Hot Rolling, Cold Rolling, Solution Treatment, Finish Cold Rolling, Aging Treatment"

However, it is important to devise manufacturing conditions in several processes as described later. Although not described in the above process, after hot rolling, the surface is subjected to machining as required. After each heat treatment, acid-washing, polishing or degreasing is carried out if necessary. Hereinafter, each step will be described.

[Dissolution and Casting]

Continuous casting, semi-continuous casting, or the like. In order to prevent the oxidation of Ti, it is preferable to carry out in an inert gas atmosphere or a vacuum melting furnace.

[Hot rolling]

Generally, hot rolling of a Cu-Ti based copper alloy is performed by a method of rolling at a high temperature of 700 ° C or higher or 750 ° C or higher and quenching after completion of rolling in order to prevent precipitates from being formed during rolling. However, it is difficult to manufacture a copper alloy sheet material having the specific aggregate structure of the present invention under such common hot rolling conditions. In other words, according to the investigation by the inventors and the like, when the hot rolling condition is employed, it is found that conditions for producing a copper alloy sheet having {420} in the upward direction of the kitchen can be produced with good reproducibility I could not. Therefore, the inventors et al. Conducted a more detailed examination. As a result, it was found that the first rolling pass was performed in the temperature zone of 950 캜 to 700 캜, and the hot rolling condition of rolling at a rolling rate of 30% or more in the temperature zone of less than 700 캜 to 500 캜 was found.

When the cast steel is subjected to the first rolling pass at a high temperature range of 700 DEG C or more at which the recrystallization is likely to occur during hot rolling, the cast structure is broken and the constitution of the component and the structure can be made uniform. However, when the temperature is higher than 950 占 폚, it is necessary to set the temperature zone where cracks do not occur in a place where the melting point is low, such as a segregation position of the alloy component. In order to ensure the occurrence of complete recrystallization in the hot rolling process, it is extremely effective to perform rolling at a rolling rate of 60% or more in a temperature zone of 950 캜 to 700 캜. This further promotes uniformity of the texture. However, since a large rolling load is required in order to obtain 60% in one pass, a rolling rate of 60% or more in total may be ensured by dividing it into multiple passes. Further, in the present invention, it is important to secure a rolling rate of 30% or more in a temperature zone of less than 700 ° C to 500 ° C which tends to cause rolling distortion. This makes it easy to form a recrystallized texture having {420} as the main component of strength by a combination of the "cold rolling + solution treatment" of the subsequent step and the formation of a part of the precipitate. At this time, rolling in multiple passes can be performed in a temperature zone of less than 700 ° C to 500 ° C. It is more preferable to set the rolling rate to 40% or more in this temperature zone. It is more effective to set the final pass temperature of the hot rolling to 600 DEG C or less. The total rolling ratio in the hot rolling may be approximately 80 to 97%.

Here, the rolling rate? (%) In each temperature zone is calculated by the equation (3).

_{ε = (t 0 -t 1)} / t 0 × 100 ······ (3)

For example, rolling is performed in a temperature zone of 120 mm or more in a temperature zone of 700 占 폚 or more provided on the first rolling pass, and the rolling is carried out at a temperature of 700 占 폚 or more And the final pass of the hot rolling was set in the range of less than 700 ° C to 400 ° C and finally a hot rolled material having a thickness of 10 mm was obtained do. In this case, the rolling rate of the rolling performed in the temperature zone of 700 ° C or higher is (120-30) / 120 x 100 = 75 (%) by the expression (3). Also, the rolling rate in the temperature range of less than 700 ° C to 400 ° C is (30-10) / 30x100 = 66.7 (%) by the equation (3).

[Cold rolling]

In the cold rolling performed prior to the solution treatment at the time of rolling the hot-rolled sheet, it is important that the rolling rate is 80% or more, more preferably 90% or more. By performing the solution treatment in the next step for the material processed at such a high rolling rate, it is possible to form a recrystallized texture structure having {420} as the kitchen top component. In particular, the recrystallized texture is highly dependent on the cold rolling rate before recrystallization. Concretely, crystal orientation with {420} as a component on the kitchen is hardly generated at a cold rolling rate of 60% or less, and gradually increases with an increase in cold rolling rate in a range of about 60 to 80% If the rate exceeds about 80%, it changes to a sudden increase. In order to obtain a crystal orientation in which the {420} orientation is sufficiently dominant, it is necessary to secure a cold rolling rate of 80% or more, and preferably 90% or more. Since the upper limit of the cold rolling rate is inevitably restricted by the mill power or the like, it is not necessary to specify the upper limit. However, from the viewpoint of preventing edge cracking or the like, good results are easily obtained at about 99% or less.

In the present invention, it is possible to employ a step of cold rolling one or more times during intermediate annealing before and after the hot rolling, but it is preferable that the cold rolling is performed at a temperature of 80% or more It is necessary to secure the rolling rate. When the cold rolling rate immediately before the solution treatment is less than 80%, the recrystallization texture with {420} formed by the solution treatment is markedly weakened.

[Solution treatment]

Conventional solution treatment processes are mainly directed to &quot; reuse in a matrix of a solute element &quot; and &quot; recrystallization &quot;, but in the present invention, &quot; formation of a recrystallized aggregate structure having {420} . The solution treatment is preferably carried out at a furnace temperature of 700 to 900 ° C. If the temperature is too low, the recrystallization is incomplete and the solubility of the solute element becomes insufficient. If the temperature is excessively high, the crystal grains become coarse. It becomes difficult to obtain a high strength material having excellent bending workability at the end.

In this solution treatment, the holding time and the reaching temperature in the 700 to 900 占 폚 region are set so that the average particle diameter of the recrystallized grains (the twin boundaries are not regarded as grain boundaries) is 10 to 60 占 퐉 or particularly 10 to 60 占 퐉 It is preferable to carry out the heat treatment, and it is more preferable to adjust it to be 15 to 40 mu m. When the recrystallized grain size becomes excessively fine, the recrystallized texture structure having {420} as the kitchen top component becomes weak. It is also disadvantageous for improving the stress relaxation resistance. If the recrystallized grain size is excessively coarsened, surface roughness of the bent portion tends to occur. The recrystallized grain size varies depending on the cold rolling rate and the chemical composition before the solution treatment, but the relation between the solution treatment heat pattern and the average crystal grain size is determined for each alloy by experiments beforehand, Time and reach temperature can be set. Concretely, in the case of the alloy having the chemical composition specified in the present invention, an appropriate condition can be set under the heating condition in which the temperature is maintained at 700 to 900 ° C for 10 seconds to 10 minutes.

[Finishing cold rolling]

Followed by finish cold rolling at a rolling rate of 65% or less. The cold rolling at this stage has an effect of promoting precipitation in the subsequent aging treatment, thereby lowering the aging temperature for reducing the required properties (conductivity and hardness), or shortening the aging time. This has the effect of reducing thermal deformation during the aging process.

The finishing cold rolling develops an aggregate structure of {220} as a sprue component. In the range of the cold rolling rate of 65% or less, however, grains parallel to the plane of the {420} plane still remain. The finish cold rolling at this stage is required to be carried out at a rolling rate of 65% or less, more preferably from 0 to 50%. If the rolling rate is excessively high, it is difficult to obtain an ideal crystal orientation satisfying the expression (1). When the rolling rate is zero, it means that the solution is subjected to direct aging treatment without cold rolling after the solution treatment. In the present invention, the finish cold rolling step may be omitted in order to improve the productivity.

[Aging treatment]

In the aging treatment, the temperature is not excessively raised in the conditions effective for improving the conductivity and strength of the alloy. When the aging treatment temperature is excessively high, the crystal orientation with {420} being the preferred orientation developed by the solution treatment is weakened, and as a result, sufficient bending workability improving effect may not be obtained. Concretely, it is preferably carried out at a temperature at which the material temperature is 300 to 550 占 폚, more preferably 350 to 500 占 폚. The aging treatment time can be set in a range of about 60 to 600 min. When the surface oxide film is suppressed as much as possible during the aging treatment, hydrogen, nitrogen or argon atmosphere can be used.

However, in the Cu-Ti-based copper alloy, it is important to avoid the above-mentioned generation of the stable phase as much as possible. For this purpose, assuming that the aging temperature at which the maximum hardness can be obtained in the alloy composition is T _M (° C) and the maximum hardness thereof is H _M (HV), the aging temperature is controlled within the range of 300 to 550 ° C. It is also effective to adopt a condition that the temperature is T _M ± 10 ° C. and the aging time is a time at which the hardness after aging is in the range of 0.85H _M to 0.95H _M. When the maximum hardness is obtained, the aging temperature T _M (° C) and its maximum hardness H _M (HV) can be grasped by a preliminary experiment. In the composition range defined in the present invention, the maximum temperature is reached within the range of the aging time within 24 hours.

Example

The copper alloy shown in Table 1 was used as a solvent and cast using a vertical semi-continuous casting machine. The obtained cast steel (thickness: 60 mm) was heated to 950 캜 and then extracted to start hot rolling. At this time, the pass schedules were set so that the rolling rate in the temperature zone of 700 ° C or higher was 60% or more, and rolling was performed in the temperature zone of less than 700 ° C, except for some comparative examples. The final pass temperature of the hot rolling is between 600 [deg.] C and 500 [deg.] C, except for some comparative examples. The overall hot rolling rate from the cast is about 95%. After the hot rolling, the oxide layer in the surface layer was removed (ground) by mechanical polishing. Then, cold rolling was carried out at various rolling ratios and then subjected to solution treatment. In the solution treatment, except for a part of the comparative example, the reaching temperature is set to be from 700 to 900 占 폚 according to the alloy composition so that the average crystal grain size after solution treatment (the twin crystal boundary is not regarded as a grain boundary) , And the holding time in the temperature zone of 700 to 900 占 폚 was adjusted to the range of 10 sec to 10 min. Subsequently, the solution subjected to the solution treatment was subjected to finish cold rolling at various rolling ratios of 0 to 70%. Further, if necessary, it was ground on the way, and the plate thickness was adjusted to 0.2 mm.

As a preliminary experiment, an aging treatment test was carried out in a temperature range of 300 to 550 ° C for a maximum of 24 hours to obtain an aging treatment condition (the aging temperature was T _M (° C), the aging time t _M (min), and the maximum hardness H _M (HV)). Then, the aging temperature is set to a temperature within a range of T _M ± 10 ° C., the aging time is set to a time shorter than t _M , and a hardness after aging is in a range of 0.85H _M to 0.95H _M , A 0.2 mm thick plate was subjected to an aging treatment to obtain a blank. However, for some comparative examples, an aging treatment condition in which the maximum hardness H _M was adopted.

Test specimens were taken from each of the specimens subjected to the aging treatment and the average grain size, aggregate structure, conductivity, tensile strength, stress relaxation characteristics, normal bending workability and notch bending workability were examined. The springback at the time of bending was also determined by measuring the shape of the test piece evaluated for the normal bending workability and the notched bending workability. In Table 1, no. 32 and No. 33, Cu-Ti-based copper alloys C199-1 / 2H and C199-EH (both factory heat treatment materials, plate thickness 0.2 mm) are commercially available.

The structure and characteristics were investigated as follows.

[Average crystal grain size]

The surface (rolled surface) of the sealing material was polished and etched, and its surface was observed with an optical microscope, and the average crystal grain size was measured by the cutting method of JIS H0501.

[Cluster organization]

A specimen in which the surface of the specimen (rolled surface) was polished with # 1500 paper was prepared and subjected to X-ray diffractometry using an X-ray diffractometer (XRD) under the conditions of Mo-K? Ray, tube voltage 20 kV, The intensity of the reflection diffraction surface on the {420} plane and the {220} plane was measured with respect to the polished finish surface. On the other hand, the X-ray diffraction intensities of the {420} plane and the {220} plane of the pure copper standard powder were measured using the X-ray diffraction apparatus as described above under the same measurement conditions. Using these measurements, the X-ray diffraction integral intensity ratio I {420} / I ₀ {420} shown in the formula (1) and the X-ray diffraction integral intensity ratio I {220} / I ₀ {220} was obtained.

[Conductivity]

The electrical conductivity of each sealing material was measured according to JIS H0505.

〔The tensile strength〕

A tensile test piece (JIS No. 5) of LD was taken from each of the specimens and subjected to a tensile test in accordance with JIS Z2241 at n = 3, and the tensile strength was determined by an average value of n = 3.

[Stress Relaxation Characteristics]

A TD bending test piece (width 10 mm) in the longitudinal direction was taken from each of the test specimens, and the test piece was fixed in an arch bending state so that the surface stress at the center portion in the longitudinal direction was 80% of the 0.2% proof stress. The surface stress is determined by the following equation.

Surface stress _{(MPa) = 6Etδ / L o} 2

only,

E: modulus of elasticity (MPa)

t: thickness of sample (mm)

?: bending height of specimen (mm)

The stress relaxation rate was calculated from the flexural properties of the specimen in this state after being held at a temperature of 200 캜 for 1000 hours in the atmosphere using the following equation.

Stress relaxation rate (%) = (L ₁ -L ₂ ) / (L ₁ -L ₀ ) × 100

only,

L ₀ is the length of the jig, that is, the horizontal distance (in mm)

L ₁ : Sample length at the start of test (mm)

L ₂ : Horizontal distance between sample ends after test (mm)

The stress relieving rate of 5% or less was evaluated to have high durability as a vehicle-use connector, and it was judged to be acceptable.

[General bending workability]

LD bending test pieces and TD bending test pieces (all 10 mm wide) in the longitudinal direction were taken from the plate of the test piece, and subjected to a 90 ° W bending test according to JIS H3110. With respect to the test piece after the test, the surface and the cross-section of the bending portion are observed with an optical microscope at a magnification of 100 times to find the minimum bending radius R at which cracks do not occur and are divided by the plate thickness t of the blank, / t. The LD / TD values of each specimen were set to n = 3, and the results of the test specimens having the worst results of n = 3 were employed to show R / t values.

[Flexural Workability after Notching]

(10 mm in width) having a small LD in the longitudinal direction was taken from the plate material of the publicly known material to obtain a notch-forming jig having a cross-sectional shape shown in Fig. 2 (the width of the flat surface at the convex portion was 0.1 mm, , A load of 20 kN was applied as shown in Fig. 3 to form a notch filled with the sample width. The direction of the notch (that is, the direction parallel to the groove) is perpendicular to the longitudinal direction of the sample. The notch depth of the bending test piece having the prepared notch was measured, and the notch depth delta shown schematically in FIG. 4 was about 1/4 to 1/6 of the plate thickness t.

The bending test piece having this notch was subjected to a bending test by a 90 占 굴 bending test conforming to JIS H3110. At this time, using a jig having a radius R of 0 mm at the front end of the center protrusion of the lower mold, the bending test piece having the notch was set so that the notched surface became downward and the tip of the central protrusion of the lower mold reached the notch, W bending test.

With respect to the test piece after the test, the surface and the cross section of the bending portion were observed with an optical microscope at a magnification of 100 times to determine whether or not cracks were present. Respectively. The fracture in the bending portion was indicated as &quot; fracture &quot;. The test results of "○", "×" and "failure" were evaluated by adopting the test results of n = 3 among n = 3 of the respective test specimens, .

[Springback]

A test piece subjected to a bending process by a "normal bending process" at a minimum bending radius and a test piece which was subjected to a bending process by a "bending process after the notching" and no cracks were recognized, A section perpendicular to the bending axis was observed with a digital microscope (VH-8000 type, manufactured by KEYENCE) with an optical microscope at a magnification of 150 times, and the bending angle? Was measured. Fig. 5 schematically shows the shape of a cross section perpendicular to the bending axis near the bending portion (central portion in the three portions) with respect to the test piece after subjected to the 90 占 굴 bending process. When the springback occurs, the bending angle [theta] becomes larger than 90 [deg.] (In Fig. 5, the magnitude of [theta] is exaggerated than in reality). The extent to which the actual bending angle &amp;thetas; is 90 DEG relative to the die (W bending test jig) is taken as an index of springback. That is, a value of "actual bending angle [theta]] - 90 [deg.] Was measured with n = 3 for each specimen, and the average value was defined as spring back.

The results are shown in Table 2. LD and TD shown in Table 2 mean the longitudinal direction of the test piece.

As can be seen from Table 2, the copper alloy sheet materials of the present invention all had crystal orientations satisfying the formula (1), and had excellent tensile strengths of 800 MPa or more and excellent R / t values of 1.0 or less for LD and TD And has processability. In addition, the bending workability after notching of a practically important LD did not cause cracking even though rigid bending was performed at R / t = 0 in a 90 ° W bending test. The springback at the time of processing is also small, and the stress relaxation ratio of TD, which becomes important in applications such as a connector for a vehicle, has excellent stress relaxation resistance of 5% or less.

On the other hand, 21 to 25 are examples of the present invention. (The hot-rolling finishing temperature is 700 ° C or higher, the hot-rolling annealing step is followed by the intermediate annealing step before the solution annealing step, the solution annealing step And a cold rolling rate of less than 80%. The X-ray diffraction intensity of the {420} crystal plane was weak in all of them, and a trade-off relationship was observed between the strength and the bending workability or between the bending workability and the stress relaxation resistance. In particular, it is impossible to bend after notching, and since the minimum bending radius can not be increased, the spring back also increases.

Comparative Example No. 1 26 and 27 are examples in which good characteristics can not be obtained because the content of Ti is outside the specified range. No. 26 has an extremely low Ti content, and thus has a low strength level even though it has undergone the aging treatment under the condition that the maximum hardness is obtained since precipitate formation is small. Even when the cold rolling rate before solvent application was increased to 95% or more, the crystal orientation with {420} as the component on the kitchen was weakened, and the bendability after the notching was not improved even though the strength level was low. No. 27 had an excessively high Ti content, the proper solution conditions could not be obtained, cracks were generated during the production, and an evaluable sheet material could not be produced.

Comparative Example No. 1 28 to 30 are examples in which favorable characteristics could not be obtained because the solution treatment conditions and the aging conditions were out of the specified range. No. 28, since the solution treatment temperature was too high at 970 캜, crystal grains coarsened and good bending workability could not be obtained. No. 29, conversely, the solubilization treatment temperature is too low at 650 ° C, so that the recrystallization itself does not sufficiently proceed and the mixed grain structure is formed, resulting in poor results in both tensile strength, bending workability and stress relaxation resistance. No. 31 is an example in which the aging treatment is performed at a time at which the aging treatment time becomes the maximum hardness in order to improve the strength. In this case, the tensile strength was improved by about 50 MPa, but the bending workability and the stress relaxation resistance were deteriorated because the steady state (TiCu ₃ ) was generated.

Comparative Example No. 1 31 exceeded the upper limit specified by the finish rolling rate, crystal orientation with {420} as a component on the kitchen was weakened, and the strength was high but the bending workability remarkably deteriorated.

Comparative Example No. 1 32 and 33 are commercial products of C199-1 / 2H and C199-EH, which represent Cu-Ti based copper alloys. All of these have weak crystal orientations with {420} as the ingredient on the kitchen sponge. 4, both of the bending workability and the stress relaxation resistance are reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a standard reverse pole diagram showing the distribution of the Schmid factor of face-centered cubic. FIG.

2 is a cross-sectional view of a notch-forming jig.

Fig. 3 schematically shows a method of notching. Fig.

4 is a view schematically showing a cross-sectional shape of a bending test piece having a notch in the vicinity of a notch forming portion;

Fig. 5 shows a cross-sectional shape perpendicular to the bending axis in the vicinity of the bending portion (central portion in the three portions) with respect to the test piece after subjected to the 90 deg. W bending process.

Claims (9)

Wherein the copper alloy has a composition containing 1.0 to 5.0% of Ti, the remainder of Cu and inevitable impurities, a crystal orientation satisfying the following formula (1), and an average crystal grain size of more than 10 占 퐉 to 60 占 퐉, Plate. I {420} / I ₀ {420} &gt; 1.0 (1) In this formula, I {420} is the X-ray diffraction integral intensity of the {420} crystal plane in the plate surface of the copper alloy sheet material, I ₀ {420} is the X-ray diffraction integral intensity of the {420} crystal plane of the pure copper standard powder. The copper alloy sheet according to claim 1, further comprising at least one of Fe: more than 0% and not more than 0.5%, Co: not less than 0% and not more than 1.0%, and Ni: not less than 0% and not more than 1.5%. The steel sheet according to any one of claims 1 to 3, further comprising at least one of Sn: more than 0% to 1.2%, Zn: more than 0% to 2.0% B: more than 0% to 0.05%, Cr: more than 0% to 1.0%, Mn: more than 0% to less than 1.0%, Si: more than 0% And V: not less than 0% and not more than 1.0% in a total amount of not less than 0% by mass and not more than 3% by mass in total. The copper alloy sheet according to any one of claims 1 to 3, further having a crystal orientation satisfying the following formula (2). I {220} / I ₀ {220}? 3.0 (2) In this formula, I {220} is the X-ray diffraction integral intensity of the {220} crystal plane in the plate surface of the copper alloy sheet material, I ₀ {220} is the X-ray diffraction integral intensity of the {220} crystal plane of the pure copper standard powder. The steel sheet according to claim 1 or 2, wherein the tensile strength of the LD (rolling direction) is 800 MPa or more, the ratio of the minimum bending radius R and the plate thickness t at which cracking does not occur in the 90 占 굴 bending test according to JIS H3110 The value of R / t is not more than 1.0 both in LD and TD (direction perpendicular to the rolling direction and the plate thickness direction), and the value of R / t is equal to or less than 1.0, ) Has a bending workability such that a value of? -90 degrees indicating a spring back amount is 3 DEG or less in both of LD and TD, when the actual bending strain angle of? A method for producing a copper alloy sheet material according to any one of claims 1 to 3, Hot rolling at 950 to 500 占 폚, cold rolling at a rolling rate of 80% or more, solution treatment at 700 to 900 占 폚, finish cold rolling at a rolling rate of 0 to 65%, and aging treatment at 300 to 550 占 폚 are successively carried out The first rolling pass is performed in a temperature zone of 950 DEG C to 700 DEG C in the hot rolling process and a rolling process of a rolling rate of 30% or more in a temperature zone of less than 700 DEG C to 500 DEG C Wherein the copper alloy sheet is a copper alloy sheet. The method for producing a copper alloy sheet material according to claim 6, wherein the rolling rate in a temperature zone of 950 캜 to 700 캜 is 60% or more in the hot rolling step. The method according to claim 6, wherein in the solution treatment step, the holding time and the reaching temperature in the 700 to 900 占 폚 region are set so that the average crystal grain size after the solution treatment exceeds 10 占 퐉 to 60 占 퐉, A method for manufacturing an alloy sheet material. 7. The method according to claim 6, wherein when the aging temperature at which the maximum hardness is obtained is T _M (° C) and the maximum hardness is H _M (HV), the aging temperature is in the range of 300 to 550 ° C in addition, T _M ± 10 ℃ temperature and a method of producing a hardness after the aging time for the aging to the time in the range of 0.85H to 0.95H _{M M,} a copper alloy plate of.

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