JP2012162776A - Copper alloy plate and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Cu-Cr-Zr based copper alloy plate having high strength, high conductivity and satisfactory bending performance, and a method for manufacturing the Cu-Cr-Zr based copper alloy plate.SOLUTION: In a method for manufacturing a copper alloy plate, a cast piece obtained by dissolving a raw copper alloy which has a composition including 0.25-1.5 mass% of Zr, 0.01-1.0 mass% of Cr and Cu and inevitable impurities in a remaining part to be casted is subjected to the hot rolling of 5-10 paths at a rolling rate in the final path of 20% or more after heated up to 900-1,080°C, quenched by water cooling after the completion of the hot rolling while the end temperature of the hot rolling is set at 700-800°C, thereafter subjected to aging treatment while being maintained at 350-450°C for 1-20 hours after subjected to cold rolling at a rolling rate of 80% or more, and then subjected to finish cold rolling at a rolling rate of 0-40%.

Description

  The present invention relates to a copper alloy sheet and a method for manufacturing the same, and more particularly to a Cu—Cr—Zr-based copper alloy sheet suitable for current-carrying parts of electrical and electronic equipment such as bus bars, lead frames, and terminals, and a method for manufacturing the same.

  Materials used for current-carrying parts of electrical and electronic equipment such as bus bars, lead frames, and terminals are required to have good conductivity in order to suppress the generation of Joule heat due to current conduction. It is required to have a high strength that can withstand the stress applied during assembly and operation. In addition, since these current-carrying parts are generally produced by a forming process such as a bending process of a plate material, it is also required to have excellent workability.

In particular, in recent years, with the spread of electric vehicles and hybrid cars (so-called EV and HEV), the current-carrying parts of electric and electronic devices are highly integrated in order to cope with the improvement of fuel economy and the increase in functions of sensors, etc. There is a tendency for miniaturization and weight reduction, and accordingly, there is an increasing demand for thinning of copper and copper alloy plate materials which are materials of current-carrying parts. When the material is made thinner due to such a requirement, the current density flowing through the material is increased and the generated heat is dissipated, so that higher conductivity is required than before. Further, when the material is made thinner, the strength level required for the material becomes more severe. Furthermore, in order to cope with the complicated shape of the current-carrying parts, it is required to improve the accuracy of the shape and dimensions by forming such as bending of the plate material. Specifically, a material having a good bending workability with a tensile strength of 600 N / mm ² or more and an electrical conductivity of 75% IACS or more is desired.

Cu—Cr—Zr containing 0.1 to 0.4 mass% Cr and 0.1 to 0.4 mass% Zr as a material having relatively high strength and conductivity, with the balance being Cu and inevitable impurities Based alloys are known. A Cu—Cr—Zr alloy is a precipitation hardening type alloy in which Cr or Zr, which is an alloy component, is precipitated alone or in the form of a compound in a Cu phase as a parent phase, and has a conductivity of 70% IACS or higher. A plate material having a strength of 500 N / mm ² or more can be obtained.

However, the Cu—Cr—Zr-based alloy cannot be expected to have a significant increase in strength due to precipitation hardening as compared with other precipitation hardening type alloys typified by Cu—Ni—Si based alloys. Therefore, in Cu-Cr-Zr alloys, the strength is improved by work hardening. However, the strain accumulated excessively by the strong processing significantly deteriorates the bending workability, so that the bending workability is high and good. Is difficult to achieve, and particularly when the tensile strength exceeds 600 N / mm ² , the bending workability is significantly deteriorated.

  In order to improve the deterioration of bending workability due to work hardening of cold rolling of a Cu-Cr-Zr alloy, 0.1 to 0.4 mass% Cr and 0.02 to 0.2 mass% Zr are added. A copper alloy material containing Cu and the inevitable impurities contained therein, and after hot rolling, cold rolling with a workability of 20 to 60% and precipitation hardening treatment heating at 350 to 600 ° C. for 10 to 600 seconds; A method of increasing the strength while suppressing deterioration of the ductility of the Cu-Cr-Zr-based alloy material and preventing the deterioration of the bending workability by performing the rolling / precipitation hardening process combined with three or more times has been proposed ( For example, see Patent Document 1).

However, in this method, the strength to be increased while preventing the bending workability of the Cu—Cr—Zr alloy material from being deteriorated is about 580 to 600 N / mm ² in tensile strength. When work hardening is performed, bending workability deteriorates rapidly.

  Generally, in order to improve the bending workability of a copper alloy sheet, it is effective to make crystal grains fine. Therefore, in order to prevent the crystal grains of the copper alloy sheet from becoming coarse, it is desirable to perform the solution treatment at a relatively low temperature range. However, when the solution treatment of the Cu—Cr—Zr-based copper alloy sheet material is performed in a low temperature region, it is not a high temperature region in which all precipitates are dissolved, so even if the crystal grains can be refined, Cr The amount of solid solution of Zr is reduced, and the strength cannot be improved by the subsequent aging treatment.

Further, since the solid solubility of Zr in Cu is very small, the Cu—Zr alloy forms a two-phase structure of a Cu parent phase and a eutectic phase composed of a Cu parent phase and Cu ₉ Zr ₂ . The copper alloy has both high strength and high conductivity. As such a Cu—Zr alloy, in a simple alloy composition comprising a Cu—Zr binary system or a Cu—Zr—B ternary system, a Cu matrix, a Cu matrix and a Cu—Zr, or a Cu—Zr— A copper alloy has been proposed which is composed of a structure in which the eutectic phase with one or both of the compounds between B is layered with each other, and has a two-phase structure in which adjacent crystal grains of the Cu matrix are intermittently in contact with each other. (For example, refer to Patent Document 2).

JP 2009-19239 A (paragraph number 0008-0010) Japanese Patent Laying-Open No. 2005-281757 (paragraph numbers 0010-0011)

However, in the method for producing a copper alloy of Patent Document 2, a copper alloy having a tensile strength of 600 N / mm ² or more and a conductivity of 75% IACS or more cannot be produced, and Zr is added excessively. When the proportion of the eutectic phase increases, coarse precipitates remain, and the precipitates become starting points of cracking, leading to deterioration of bending workability.

  Accordingly, in view of the above-described conventional problems, the present invention aims to provide a Cu—Cr—Zr-based copper alloy sheet material having high strength, high conductivity, and good bending workability, and a method for producing the same. And

  As a result of intensive studies to solve the above problems, the inventors of the present invention contain 0.25 to 1.5% by mass of Zr and 0.01 to 1.0% by mass of Cr, with the balance being Cu and inevitable impurities. After heating the cast slab obtained by melting and casting the raw material of the copper alloy having the composition consisting of 900 to 1080 ° C., hot rolling is performed with the rolling rate of the final pass being 20% or more, After performing cold rolling at a rolling rate of 80% or more, holding at 350 to 450 ° C., performing aging treatment, and then performing finish cold rolling at a rolling rate of 0 to 40%, high strength and high conductivity The present inventors have found that a Cu—Cr—Zr-based copper alloy sheet having good bending workability at a high rate can be produced, and the present invention has been completed.

  That is, the method for producing a copper alloy sheet according to the present invention has a composition containing 0.25 to 1.5% by mass of Zr and 0.01 to 1.0% by mass of Cr, with the balance being Cu and inevitable impurities. After the cast slab obtained by melting and casting the raw material of the copper alloy is heated to 900 to 1080 ° C., hot rolling is performed with the rolling rate of the final pass being 20% or more, and then the rolling rate is 80% or more. After the cold rolling, the aging treatment is performed by holding at 350 to 450 ° C., and then the finish cold rolling is performed at a rolling rate of 0 to 40%.

  In this copper alloy sheet manufacturing method, the composition of the raw material of the copper alloy is a total of 0.3% by mass of a rare earth metal containing Ce and one or more elements selected from the group consisting of Si, Sn, Mg, B and P. You may further include in the following ranges. Moreover, it is preferable that the retention time of an aging treatment is 1 to 20 hours. Moreover, it is preferable to set the end temperature of hot rolling to 700-800 degreeC, and to cool rapidly after completion | finish of hot rolling, and it is preferable that this rapid cooling is performed by water cooling. Moreover, when performing finish cold rolling, it is preferable to perform finish cold rolling at a rolling rate of 10 to 30%, and then it is preferable to perform low temperature annealing at 350 to 425 ° C.

The copper alloy sheet according to the present invention contains 0.25 to 1.5% by mass of Zr and 0.01 to 1.0% by mass of Cr, and the balance is composed of Cu and inevitable impurities. A bending test piece having a strength of 600 N / mm ² or more, an electrical conductivity of 75% IACS or more, and a longitudinal direction of TD (direction perpendicular to the rolling direction and the plate thickness direction) is 90 ° in accordance with JIS H3110. The ratio R / t between the minimum bending radius R at which no cracks occur after the W bending test is performed and the thickness t of the copper alloy sheet is less than 1.0.

In this copper alloy sheet, the composition of the copper alloy further includes a rare earth metal containing Ce and one or more elements selected from the group consisting of Si, Sn, Mg, B, and P in a total range of 0.3% by mass or less. May be included. Moreover, it is preferable that a copper alloy has a two-phase structure which consists of Cu mother phase and a 2nd phase, and it is preferable that the average crystal grain diameter of Cu mother phase is 5-20 micrometers. Moreover, it is preferable that the ratio of the area of the eutectic phase existing on the surface of the copper alloy sheet is 4 to 25%, and the ratio of the area of the fine eutectic phase of 1 μm ² or less existing on the surface of the copper alloy sheet is the same. It is preferably 40% or more of the total area of the crystal phase. Further, the second phase includes a eutectic phase of a Cu matrix and at least one compound of Cu—Zr and Cu—Cr—Zr, and Cr, Zr, Cr—Zr, Cr—Cu precipitated in the Cu matrix. ,
It is preferably composed of a compound containing at least one of Zr—Cu and Cr—Zr—Cu.

According to the present invention, it is possible to produce a Cu—Cr—Zr-based copper alloy sheet having high strength and high electrical conductivity and good bending workability. In particular, a bending test piece having a tensile strength of 600 N / mm ² or more, an electrical conductivity of 75% IACS or more, and a longitudinal direction of TD (direction perpendicular to the rolling direction and the plate thickness direction) conforms to JIS H3110. The ratio (R / t) between the minimum bending radius R at which cracking does not occur and the thickness t of the copper alloy sheet after the 90 ° W bending test is less than 1.0 has good (BadWay) bending workability A Cu—Cr—Zr-based copper alloy sheet can be produced.

  In the embodiment of the method for producing a copper alloy sheet according to the present invention, a rare earth metal containing 0.25 to 1.5% by mass of Zr and 0.01 to 1.0% by mass of Cr, and optionally containing Ce. And a raw material of a copper alloy having a composition of one or more elements selected from the group consisting of Si, Sn, Mg, B, and P in a total amount of 0.3% by mass or less, with the balance being Cu and inevitable impurities The process of obtaining a slab by melting and casting (melting / casting process), and heating the obtained slab to 900 to 1080 ° C., then the heat of 5 to 10 passes at a rolling rate of 20% or more in the final pass A step of performing cold rolling (hot rolling step), a step of performing cold rolling at a rolling rate of 80% or more after the hot rolling (cold rolling step), and 350 to 450 ° C. after the cold rolling at 1 to 350 ° C. A process of performing an aging treatment for 20 hours (aging process); After this aging treatment, there is provided a step (finishing cold rolling step) of performing finish cold rolling at a rolling rate of 0 to 40% ("rolling rate 0%" means not performing finish cold rolling). . In addition, when performing finish cold rolling, it is preferable to perform finish cold rolling at a rolling rate of 10 to 30%, and thereafter includes a step of performing low temperature annealing at 350 to 425 ° C. (low temperature annealing step). Is preferred. Further, before and after hot rolling, chamfering may be performed as necessary, and after heat treatment, pickling, polishing, and degreasing may be performed as necessary.

In the embodiment of the method for producing a copper alloy sheet according to the present invention, even if the Cu—Cr—Zr-based copper alloy contains an excessive amount of Zr than in the prior art, a strong eutectic phase composed of Cu ₉ Zr _2, etc. The precipitate can be finely dispersed without being coarsened, and the crystal grains of the Cu matrix can be refined. Therefore, in the embodiment of the method for producing a copper alloy sheet according to the present invention, the strength improvement by the two-phase structure of the Cu parent phase and the eutectic phase is combined with the strength improvement by precipitation hardening, thereby providing high strength and high conductivity. Cu-Cr-Zr-based copper alloy sheets having good bending workability at a high rate can be produced.

  Hereinafter, each process of embodiment of the manufacturing method of the copper alloy board | plate material by this invention is demonstrated in detail.

(Alloy composition)
As a raw material of the copper alloy sheet, 0.25 to 1.5% by mass, preferably 0.3 to 1.2% by mass of Zr, 0.01 to 1.0% by mass, preferably 0.01 to 0. A copper alloy raw material containing 5% by mass of Cr and having the balance of Cu and inevitable impurities is used. Further, in order to increase the strength of the copper alloy sheet, the total amount of Ce-containing rare earth metal and one or more elements selected from the group consisting of Si, Sn, Mg, B and P is 0.3% by mass or less, preferably 0 It may further be included in the range of 0.01 to 0.3% by mass. Thus, the strength of the copper alloy sheet can be improved by precipitation of a small amount of additive elements such as Zr and Cr in the Cu matrix.

  The reason why Zr is added as a raw material for the copper alloy is to improve the strength by the two-phase structure of the Cu parent phase and the eutectic phase, and the Zr content is set to 0.25 to 1.5 mass%. If the amount is less than 0.25% by mass, the proportion of the eutectic phase becomes low, and the strength cannot be sufficiently improved by the two-phase structure. If the amount exceeds 1.5% by mass, the coarse eutectic phase This is because excessively present causes a marked deterioration in bending workability.

  The reason why Cr is added as a raw material for the copper alloy is to improve the strength by precipitation hardening. The reason why the Cr content is 0.01 to 1.0% by mass is from 0.01% by mass. If the amount is too small, sufficient precipitation hardening cannot be obtained, so that the strength cannot be improved by precipitation hardening. If the amount exceeds 1.0% by mass, the Cr precipitate is coarsened and tends to be the starting point of cracking. is there. Further, even if the Cr content is more than 0.5% by mass, the strength cannot be further improved, so the Cr content is preferably in the range of 0.01 to 0.5% by mass.

  Furthermore, the addition of one or more elements selected from the group consisting of rare earth metals containing Ce and Si, Sn, Mg, B, and P as raw materials for copper alloys is due to precipitation hardening by these precipitation strengthening elements. This is to improve the strength. If the content is less than 0.01% by mass, the strength cannot be further improved by precipitation hardening. If the content exceeds 0.3% by mass, coarse precipitation that does not contribute to the improvement in strength. This is because the number of objects increases and bending workability deteriorates.

(Melting and casting process)
A slab is manufactured after melt | dissolving the raw material of the copper alloy of said composition using a high frequency vacuum melting furnace.

(Hot rolling process)
The obtained slab is heated for 30 minutes to 1 hour in a furnace set at 900 to 1080 ° C. By this heating, additive elements such as coarse Zr and Cr deposited during casting can be forcibly solid-solved in the Cu matrix once to obtain a solution effect. The appropriate temperature for this heating is preferably around 980 ° C., which is the eutectic temperature, but it is more preferably in the range of 930-960 ° C. because the crystal grains of the copper alloy become coarse. Thus, after heating in a temperature range of 900 to 1080 ° C., hot rolling is performed for a plurality of passes, preferably about 5 to 10 passes. The final pass of this hot rolling is performed at a rolling rate of 20% or more in a temperature range of 700 to 800 ° C. The reason why the rolling rate of the final pass is set to 20% or more is to obtain an effect of forming a large strain and suppressing the growth of crystal grains to refine the crystal grains. It is preferable to keep the temperature immediately after the end of this hot rolling at the recrystallization temperature of 700 to 800 ° C. and then perform rapid cooling by water cooling.

(Cold rolling process)
Cold rolling is performed at a rolling rate of 80% or more after hot rolling. By this cold rolling, the effect of uniformly dispersing the eutectic phase segregated at the grain boundaries of the Cu matrix and the compound containing any of the additive elements such as Cr and Zr dissolved in the Cu matrix is efficiently obtained. The effect of precipitating can be obtained. In order to further disperse the eutectic phase, the rolling rate of cold rolling is preferably 90% or more, and more preferably 95% or more.

(Aging process)
After cold rolling, an aging treatment is performed at 350 to 450 ° C. for 1 to 20 hours. By this aging treatment, a compound containing a single element or any of additive elements such as Cr and Zr dissolved in the Cu matrix can be precipitated, and the strength and conductivity can be improved. In order to improve these characteristics, it is preferable to perform an aging treatment at 350 to 450 ° C. When the temperature is lower than 350 ° C., the time required for precipitation becomes extremely long. When the temperature is higher than 450 ° C., the precipitate becomes coarse. As a result, the strength decreases and bending workability deteriorates. Moreover, in order to precipitate efficiently and prevent the coarsening of a crystal grain and to obtain the copper alloy board | plate material which has favorable bending workability with high intensity | strength and high electrical conductivity, it is preferable to perform an aging treatment at 375-425 degreeC. .

(Finish cold rolling process)
In order to further improve the strength after the aging treatment, finish cold rolling is performed at a rolling rate of 0 to 40%, preferably 10 to 30%. Note that bending workability deteriorates due to dislocations accumulated around the precipitates as the rolling rate of cold rolling increases, so it is difficult to achieve both high strength and good bending workability. In order to prevent extreme deterioration in workability, it is preferable to set the rolling rate of finish cold rolling to 30% or less.

(Low temperature annealing process)
When performing finish cold rolling, you may perform low temperature annealing at 350-425 degreeC after finish cold rolling. By this low-temperature annealing, the bending workability due to the reduction of residual stress can be improved and the electrical conductivity can be increased without substantially reducing the strength of the copper alloy sheet. If the temperature of this low-temperature annealing is too high, it will soften in a short time and tend to cause variations in characteristics, and if it is too low, the effect of improving these characteristics cannot be obtained sufficiently.

According to the embodiment of the method for producing a copper alloy sheet described above, a composition containing 0.25 to 1.5 mass% of Zr and 0.01 to 1.0 mass% of Cr, with the balance being Cu and inevitable impurities. It has a tensile strength of 600N / mm ² or more (preferably 610N / mm ² or more, more preferably 620N / mm ² or higher), and a conductivity of 75% IACS or more, longitudinally TD (rolling direction and the plate The ratio of the minimum bending radius R at which cracking does not occur and the thickness t of the copper alloy sheet material R / after bending the 90 ° W bending test in accordance with JIS H3110 with respect to the bending test piece in the direction perpendicular to the thickness direction R / A copper alloy sheet having a t of less than 1.0 can be produced. The copper alloy composition of the copper alloy sheet further includes a rare earth metal containing Ce and one or more elements selected from the group consisting of Si, Sn, Mg, B, and P in a range of 0.3 mass% or less in total. But you can. Moreover, the copper alloy of this copper alloy plate material can have a two-phase structure composed of a Cu matrix and a second phase, and the average crystal grain size of the Cu matrix can be 5 to 20 μm.

From the Cu-Zr binary phase diagram and the Cu-Cr-Zr ternary phase diagram, it contains 0.172-12.27 mass% Zr and 0.01-0.5 mass% Cr, and the balance In the copper alloy in which Cu is made of Cu, the second phase of the two-phase structure may be composed of a eutectic phase of a Cu parent phase and at least one compound of Cu—Zr (Cu ₉ Zr ₂ ) and Cu—Cr—Zr. Guessed. In addition, since a small amount of Cr and Zr are dissolved in Cu, at least one compound of Cr, Zr, Cr—Zr, Cr—Cu, Zr—Cu, and Cr—Zr—Cu is precipitated in the Cu matrix. It is speculated that these are also included in the second phase.

  Hereinafter, examples of the copper alloy sheet material and the manufacturing method thereof according to the present invention will be described in detail.

[Examples 1 to 11]
A copper alloy (Example 1) containing 0.53% by mass of Zr and 0.86% by mass of Cr, with the balance being Cu and inevitable impurities, 1.05% by mass of Zr and 0.31% by mass of Cr A copper alloy (Example 2) containing Cu and unavoidable impurities in the balance, and a copper alloy containing 1.38% by mass of Zr and 0.02% by mass of Cr and the balance consisting of Cu and unavoidable impurities (Example 3) ), A copper alloy containing 0.45% by mass of Zr, 0.11% by mass of Cr and 0.18% by mass of Si, the balance being Cu and inevitable impurities (Example 4), 0.40% by mass of A copper alloy (Example 5) containing Zr, 0.09 mass% Cr and 0.14 mass% Sn with the balance being Cu and inevitable impurities, 0.39 mass% Zr and 0.14 mass% Contains Cr and 0.04 mass% Mg, with the balance being Cu and impossibility Copper alloy consisting of impurities (Example 6), copper alloy containing 0.46% by mass of Zr, 0.13% by mass of Cr and 0.05% by mass of B, with the balance being Cu and inevitable impurities (Example) 7), a copper alloy containing 0.34% by mass of Zr, 0.10% by mass of Cr and 0.03% by mass of P, with the balance being Cu and inevitable impurities (Example 8), 0.41% by mass Of Zr, 0.08% by mass of Cr and 0.08% by mass of Ce, with the balance being Cu and inevitable impurities (Example 9), 0.28% by mass of Zr and 0.51% by mass Copper alloy containing 0.22% by mass of Cr and 0.22% by mass of Si, the balance being Cu and inevitable impurities (Example 10), 0.37% by mass of Zr, 0.49% by mass of Cr and 0.17% by mass A copper alloy containing Si and the balance consisting of Cu and inevitable impurities The raw material of 11) were melted respectively, were cut slab from the resulting ingot by casting using a high frequency vacuum melting furnace.

  Subsequently, each slab was 950 ° C. (Examples 1, 2, 7 to 11), 900 ° C. (Example 3), 970 ° C. (Example 4), 1000 ° C. (Example 5), and 925 ° C. (implemented). After heating for 30 minutes in the furnace set in Example 6), hot rolling was performed for 8 passes with each heating and holding temperature as the starting temperature. In addition, the final pass of each hot rolling is a rolling rate of 25% (Example 1) at 731 ° C., a rolling rate of 25% (Example 2) at 722 ° C., and a rolling rate of 30% at 713 ° C. (Example 3). The rolling rate is 25% at 728 ° C (Example 4), the rolling rate is 25% at 715 ° C (Example 5), the rolling rate is 25% at 710 ° C (Example 6), and the rolling rate is 20% at 724 ° C (Example). 7), rolling rate 30% at 730 ° C. (Example 8), rolling rate 35% at 721 ° C. (Example 9), rolling rate 25% at 762 ° C. (Example 10), rolling rate 25% at 746 ° C. ( Example 11) was performed. Thereafter, each was quenched by water cooling.

  Next, cold rolling was performed at a rolling rate of 97.1% (Examples 1 to 3), 90.0% (Examples 4 to 7, 9), and 95.0% (Examples 8, 10, and 11), respectively. It was.

  Then, 400 ° C for 5 hours (Examples 1, 2, 4, 5), 425 ° C for 11 hours (Example 3), 350 ° C for 20 hours (Example 6), and 425 ° C for 3 hours (Example) 7, 10) 17 hours (Example 8) at 375 ° C., 2 hours at 450 ° C. (Example 9), and 8 hours (Example 11) at 375 ° C. for aging treatment.

  In Examples 10 and 11, finish rolling was performed at a rolling rate of 30% after the aging treatment, and then kept at 400 ° C. for 30 minutes (Example 10) and 350 ° C. for 1 hour (Example 11), respectively. Annealing was performed.

  Samples were taken from the 0.2 mm thick copper alloy sheets obtained in these examples, and the grain structure, average crystal grain size, eutectic phase ratio, fine eutectic phase ratio, tensile strength, conductivity The rate and bending workability were evaluated as follows.

  First, after polishing the surface (rolled surface) of the sample of the obtained copper alloy sheet material, the surface was etched, the crystal grain structure was observed with an optical microscope, and the average grain size was determined by the cutting method of JIS H0501. It was. As a result, the sample of the copper alloy sheet has a two-phase structure composed of a Cu matrix and a second phase, and the average crystal grain sizes of the Cu matrix are 6 μm (Example 1) and 9 μm (Example 2), respectively. 4, 9), 8 μm (Example 3), 11 μm (Examples 5 to 7), 12 μm (Example 8), 13 μm (Example 10), and 16 μm (Example 11).

Moreover, after grind | polishing after etching the surface (rolling surface) of the sample of the obtained copper alloy board | plate material, the electron probe microanalysis was performed about the measurement area | region of 100 micrometers x 50 micrometers of the surface. In this electron probe microanalysis, a measurement area of 100 μm × 50 μm is divided into 5000 square areas of 1 μm × 1 μm, and an electron probe microanalyzer (EPMA) is used to accelerate voltage 15 kV, irradiation current 300 nA, integration speed Under the conditions of 30 ms and a probe diameter of 1 μm, an electron beam with a probe diameter of 1 μm was irradiated to the center of each minute region, and the integrated intensity of each Zr element was measured. Using the micro area where the Zr element is detected by the microanalysis of the electron probe as the micro area where the eutectic phase is present, the total number of micro areas where the Zr element is detected is obtained, and the total number is calculated as the micro area within the measurement area. The value divided by the number of (5000) was the ratio of the eutectic phase (the ratio of the area occupied by the eutectic phase to the total area of the measurement region). Further, the Zr element is detected in a certain minute region (one minute region), and the Zr element is detected in eight minute regions surrounding the minute region (four minute regions on the upper, lower, left, and right sides and four minute regions existing diagonally). If not detected, as its Zr elements are present 1 [mu] m ² or less fine eutectic phase to the detected small area, the total number of micro-regions such 1 [mu] m ² or less fine eutectic phase is present The ratio of the fine eutectic phase of 1 μm ² or less α / X (α is the area occupied by the fine eutectic phase of 1 μm ² or less, X is the eutectic phase (Total area occupied). As a result, the ratio of the eutectic phase was 4.8% (Example 1), 16.9% (Example 2), 21.3% (Example 3), and 4.1% (Example 4), respectively. 5.3% (Example 5), 4.3% (Example 6), 8.5% (Example 7), 5.1% (Example 8), 6.7% (Example 9) 10.3% (Example 10) and 12.7% (Example 11), and the proportion of the eutectic phase (α / X) was 71% (Example 1) and 66% (Example), respectively. 2), 51% (Example 3), 53% (Example 4), 50% (Example 5), 55% (Example 6), 54% (Example 7), 47% (Example 8) 60% (Example 9), 65% (Example 10), and 68% (Example 11).

Also, as the tensile strength of the copper alloy sheet, three specimens for tensile testing (JIS Z2241 No. 5 specimen) each having a longitudinal direction in the rolling direction (LD) were taken from the obtained copper alloy sheet sample. Then, a tensile test based on JIS Z2241 was performed, and the tensile strength was obtained by an average value. As a result, the tensile strengths were 622 N / mm ² (Example 1), 620 N / mm ² (Example 2), 617 N / mm ² (Example 3), 613 N / mm ² (Example 4), and 621 N, respectively. / Mm ² (Example 5), 618 N / mm ² (Example 6), 628 N / mm ² (Example 7), 620 N / mm ² (Example 8), 633 N / mm ² (Example 9), 618 N / Mm ² (Example 10) and 631 N / mm ² (Example 11).

  Moreover, the electrical conductivity of the sample of the copper alloy sheet was measured according to the electrical conductivity measurement method of JIS H0505. As a result, the electrical conductivity was 76.3% IACS (Example 1), 75.2% IACS (Example 2), 77.1% IACS (Example 3), and 78.2% IACS (Example 4), respectively. ), 75.1% IACS (Example 5), 76.1% IACS (Example 6), 75.5% IACS (Example 7), 77.5% IACS (Example 8), 75.3% IACS (Example 9), 77.6% IACS (Example 10), and 76.1% IACS (Example 11).

  Further, in order to evaluate the bending workability of the copper alloy sheet, three bending test pieces (width 10 mm) each having a longitudinal direction TD (direction perpendicular to the rolling direction and the plate thickness direction) from the copper alloy sheet The samples were collected and subjected to a 90 ° W bending test in accordance with JIS H3110 for each test piece. For each of the test specimens after these tests, the surface and cross section of the bent portion were observed with an optical microscope at a magnification of 20 times and 50 times, respectively, to obtain a minimum bending radius R at which no cracks occurred, and this minimum bending radius. The R / t value of TD was determined by dividing R by the plate thickness t of the copper alloy sheet. Of the three test pieces, the result of the worst test piece was adopted as the R / t value. As a result, in Examples 1, 2, and 4 to 9, R / t = 0.0, and excellent bending workability was obtained. In Example 10, R / t = 0.5, and in Examples 3 and 11, R / t = 0.6.

[Comparative Examples 1 to 11]
A copper alloy (Comparative Example 1) containing 0.21% by mass of Zr and 0.14% by mass of Cr, with the balance being Cu and inevitable impurities, 1.65% by mass of Zr and 0.43% by mass of Cr. A copper alloy (comparative example 2) containing Cu and inevitable impurities, and a copper alloy containing 0.48% by mass of Zr and 1.25% by mass of Cr with the balance being Cu and inevitable impurities (comparative example 3) ), A copper alloy containing 1.05 mass% Zr and 0.31 mass% Cr with the balance being Cu and inevitable impurities (Comparative Examples 4 to 8), 0.40 mass% Zr and 0.13 mass % Copper and 0.44% by mass of Si, with the balance being Cu and inevitable impurities (Comparative Example 9), 0.28% by mass of Zr, 0.15% by mass of Cr and 0.22% by mass % Copper with the balance being Cu and inevitable impurities A copper alloy (Comparative Example 11) containing gold (Comparative Example 10), 0.11% by mass of Zr and 0.23% by mass of Cr, and the balance of Cu and inevitable impurities was respectively melted, and a high-frequency vacuum melting furnace A slab was cut out from an ingot obtained by casting using the above.

  Subsequently, each slab was heated for 30 minutes in a furnace set at 950 ° C. (Comparative Examples 1, 3-6, 8-11), 900 ° C. (Comparative Example 2), and 850 ° C. (Comparative Example 7), respectively. After that, hot rolling was performed for 8 passes with each heating temperature as a starting temperature. The final pass of each hot rolling was 712 ° C. with a rolling rate of 25% (Comparative Example 1), 705 ° C. with a rolling rate of 30% (Comparative Example 2), and 742 ° C. with a rolling rate of 25% (Comparative Example 3). The rolling rate is 25% at 735 ° C (Comparative Example 4), the rolling rate is 25% at 718 ° C (Comparative Example 5), the rolling rate is 25% at 718 ° C (Comparative Example 6), and the rolling rate is 25% at 718 ° C (Comparative Example). 7) Rolling rate 15% at 745 ° C. (Comparative Example 8), rolling rate 25% at 733 ° C. (Comparative Example 9), rolling rate 25% at 738 ° C. (Comparative Example 10), rolling rate 25% at 727 ° C. Comparative Example 11) was performed. Thereafter, each was quenched by water cooling.

  Next, the rolling ratio was 90.5% (Comparative Example 1), 99.2% (Comparative Example 2), 83.0% (Comparative Example 3), 62.5% (Comparative Example 4), 97.1% ( Cold rolling was performed at Comparative Examples 5 to 8), 90.0% (Comparative Example 9), and 95.0% (Comparative Examples 10 and 11).

  Next, 15 hours at 375 ° C. (Comparative Example 1), 3 hours at 450 ° C. (Comparative Example 2), 5 hours at 400 ° C. (Comparative Examples 3, 7-9), 3 hours at 400 ° C. (Comparative Example 4) Aging at 475 ° C. for 1 hour (Comparative Example 5), 325 ° C. for 20 hours (Comparative Example 6), 425 ° C. for 3 hours (Comparative Example 10), and 400 ° C. for 2 hours (Comparative Example 11) went.

  In Comparative Example 10, finish cold rolling was performed at a rolling rate of 50% after the aging treatment, and thereafter, low temperature annealing was performed by holding at 400 ° C. for 1 hour.

  Samples were taken from the 0.2 mm-thick copper alloy sheets obtained in these comparative examples, and crystal grain structure, average crystal grain size, eutectic phase ratio, fine coexistence were obtained in the same manner as in Examples 1-11. The ratio of crystal phase, tensile strength, electrical conductivity, and bending workability were evaluated.

  As a result, the sample of the copper alloy sheet has a two-phase structure composed of a Cu matrix and a second phase, and the average crystal grain sizes of the Cu matrix are 8 μm (Comparative Example 1) and 24 μm (Comparative Example 2), respectively. ), 31 μm (Comparative Example 3), 20 μm (Comparative Example 4), 29 μm (Comparative Example 5), 8 μm (Comparative Example 1), 10 μm (Comparative Example 7), 35 μm (Comparative Example 8), 30 μm (Comparative Example 9) 18 μm (Comparative Example 10) and 11 μm (Comparative Example 11).

  Moreover, the ratio of the eutectic phase of the copper alloy sheet was 2.5% (Comparative Example 1), 28.3% (Comparative Example 2), 5.9% (Comparative Example 3), and 13.1% (Comparative), respectively. Example 4), 14.3% (Comparative Example 5), 12.0% (Comparative Example 6), 15.3% (Comparative Example 7), 11.9% (Comparative Example 8), 4.3% (Comparative) Example 9) is 2.7% (Comparative Example 10), and the proportion of the fine eutectic phase (α / X) is 45% (Comparative Example 1), 24% (Comparative Example 2), and 45% (Comparative), respectively. Example 3), 15% (Comparative Example 4), 68% (Comparative Example 5), 62% (Comparative Example 6), 50% (Comparative Example 7), 41% (Comparative Example 8), 51% (Comparative Example 9) ), 61% (Comparative Example 10).

The tensile strengths of the copper alloy sheets were 557 N / mm ² (Comparative Example 1), 660 N / mm ² (Comparative Example 2), 608 N / mm ² (Comparative Example 3), 564 N / mm ² (Comparative Example 4), respectively. ), 603 N / mm ² (Comparative Example 5), 521 N / mm ² (Comparative Example 6), 561 N / mm ² (Comparative Example 7), 615 N / mm ² (Comparative Example 8), 611 N / mm ² (Comparative Example 9) ), 641 N / mm ² (Comparative Example 10), and 565 N / mm ² (Comparative Example 11).

  Moreover, the electrical conductivity of the sample of a copper alloy board | plate material is 82.5% IACS (comparative example 1), 71.5% IACS (comparative example 2), 80.9% IACS (comparative example 3), and 82.1%, respectively. IACS (Comparative Example 4), 80.1% IACS (Comparative Example 5), 71.1% IACS (Comparative Example 6), 81.5% IACS (Comparative Example 7), 76.5% IACS (Comparative Example 8) 76.0% IACS (Comparative Example 9), 76.2% IACS (Comparative Example 10), and 80.5% IACS (Comparative Example 11).

  The R / t of the copper alloy plate material was R / t = 0.0 in Comparative Examples 1, 6, 7 and 11, and had excellent bending workability. t = 0.6, R / t = 1.2 in Comparative Example 9, R / t = 1.5 in Comparative Examples 3, 5 and 8, and R / t = 2.0 in Comparative Examples 2 and 10 .

  The compositions of the copper alloys of these examples and comparative examples are shown in Table 1, the production conditions of the copper alloy sheet are shown in Table 2, and the results on the structure and properties of the copper alloy sheet are shown in Table 3.

In addition, regarding the tensile strength, electrical conductivity, and bending workability of the copper alloy sheet materials obtained in Examples and Comparative Examples, ◎ when the tensile strength is 620 N / mm ² or more, and 600 to less than 620 N / mm ² ○, when X is lower than 600 N / mm ² , ◎ when the conductivity is 80% IACS or more, ○ when the conductivity is less than 75-80% IACS, X when it is lower than 75% IACS, R / t Table 4 shows ◎ when 0 is greater, ◯ when greater than 0 and 1 or less, and x when greater than 1 and shown in Table 4.

As shown in Tables 3 and 4, in Examples 1, ² , 5, 7 and 9, the proportion of the fine eutectic phase (α / X) of 1 μm ² or less is 50% or more, and the conductivity is 75%. It had a very good bending workability of IACS or more, tensile strength of 620 N / mm ² or more, and R / t = 0. In Example 8, the ratio (α / X) of the fine eutectic phase of 1 μm ² or less is 45% or more, the conductivity is 75% IACS or more, the tensile strength is 620 N / mm ² or more, and R / t = 0. It had a very good bending workability. In Examples 4 and 6, the ratio (α / X) of the fine eutectic phase of 1 μm ² or less is 50% or more, the conductivity is 75% IACS or more, the tensile strength is 600 N / mm ² or more, R / t It had a very good bending workability of = 0. In Examples 3 and 10, the ratio (α / X) of the fine eutectic phase of 1 μm ² or less is 50% or more, the conductivity is 75% IACS or more, the tensile strength is 600 N / mm ² or more, R / t = Good bending workability of 0.5 to 0.6. In Example 11, the ratio (α / X) of the fine eutectic phase of 1 μm ² or less is 50% or more, the conductivity is 75% IACS or more, the tensile strength is 620 N / mm ² or more, and R / t = 0. .6 good bending workability.

In Comparative Example 1, since the Zr content was as low as 0.21% by mass, the proportion of the fine eutectic phase of 1 μm ² or less was as high as 45%, but the proportion of the eutectic phase was as low as 2.5%. Although the effect of improving the strength due to the two-phase structure of the Cu matrix and the eutectic phase was not sufficiently obtained, the electrical conductivity was as high as 82.5% IACS and the bending workability was very good, but the tensile strength Was as low as 557 N / mm ² .

In Comparative Example 2, since the Zr content was as large as 1.65% by mass, the average crystal grain size was coarsened to 24 μm, the ratio of the eutectic phase was as high as 28.3%, and the fine eutectic phase of 1 μm ² or less. Therefore, the coarse eutectic phase that remained without being dispersed became the starting point of cracking, and R / t = 2 and bending workability deteriorated. Moreover, although the tensile strength was as high as 660 N / mm ² , the conductivity was as low as 71.5% IACS.

In Comparative Example 3, since the Cr content was as large as 1.25% by mass, the average crystal grain size was coarsened to 31 μm, and excess Cr that did not contribute to the improvement in strength was coarsened, so the tensile strength was 608 N / mm. ^Although it was as high as ² and the conductivity was as high as 80.9% IACS, the bending workability deteriorated as R / t = 1.5.

In Comparative Example 4, the rolling ratio of cold rolling was as low as 62.5%, so the conductivity was as high as 82.1% IACS and R / t = 0.6 and the bending workability was good. Since the ratio of the fine eutectic phase of 1 μm ² or less was as low as 15%, the eutectic phase was not sufficiently dispersed, and the tensile strength was as low as 564 N / mm ² .

In Comparative Example 5, since the aging treatment temperature was as high as 475 ° C., the average crystal grain size was increased to 29 μm, so the tensile strength was as high as 603 N / mm ² and the conductivity was as high as 80.1% IACS. R / t = 1.5 and bending workability deteriorated.

In Comparative Example 6, since the aging treatment temperature was as low as 325 ° C., Cr and Zr dissolved in the Cu matrix were not completely precipitated, so the bending workability was extremely good at R / t = 0.0. However, the tensile strength was as low as 521 N / mm ² and the conductivity was as low as 71.1% IACS.

In Comparative Example 7, since the start temperature during hot rolling was as low as 850 ° C., the amount of Cr and Zr dissolved in the Cu matrix during solution treatment was reduced, and therefore the conductivity was 81.5% IACS. Although the bending workability was very good with R / t = 0.0, the improvement in strength after aging treatment was small and the tensile strength was as low as 561 N / mm ² .

In Comparative Example 8, since the rolling rate of the final pass of the hot rolling was as low as 15%, the average crystal grain size was increased to 35 μm, so that the tensile strength was as high as 615 N / mm ² and the conductivity was 76.5. Although it was high with% IACS, the bending workability deteriorated with R / t = 1.5.

In Comparative Example 9, since the Si content was as large as 0.44% by mass, the average crystal grain size was coarsened to 30 μm, and excessive Si precipitates that did not contribute to the improvement in strength were coarsened, so that the tensile strength was 611N. / Mm ² and the conductivity was as high as 76.0% IACS, but the bending workability deteriorated with R / t = 1.2.

In Comparative Example 10, since the rolling rate of finish cold rolling was as high as 50%, the tensile strength was as high as 641 N / mm ² and the conductivity was as high as 76.2% IACS, but R / t = 2. 0 and bending workability deteriorated.

Comparative Example 11 is an example in which a conventional Cu—Cr—Zr alloy was used. However, since the Zr content was as low as 0.11% by mass, the conductivity was as high as 80.5% IACS and R / t = The bending workability was extremely good at 0.0, but the tensile strength was as low as 565 N / mm ² .

Claims (13)

Obtained by melting and casting a raw material of a copper alloy containing 0.25 to 1.5% by mass of Zr and 0.01 to 1.0% by mass of Cr, with the balance consisting of Cu and inevitable impurities After heating the obtained slab to 900 to 1080 ° C., hot rolling is performed with the rolling rate of the final pass being 20% or more, and then cold rolling is performed at a rolling rate of 80% or more, and then 350 to 450 ° C. A method for producing a copper alloy sheet material, characterized in that the aging treatment is carried out by holding, followed by finish cold rolling at a rolling rate of 0 to 40%. The composition of the raw material of the copper alloy further includes a rare earth metal containing Ce and one or more elements selected from the group consisting of Si, Sn, Mg, B and P in a total range of 0.3% by mass or less. The method for producing a copper alloy sheet according to claim 1, wherein The method for producing a copper alloy sheet according to claim 1 or 2, wherein the retention time of the aging treatment is 1 to 20 hours. The method for producing a copper alloy sheet according to any one of claims 1 to 3, wherein an end temperature of the hot rolling is set to 700 to 800 ° C, and rapid cooling is performed after the hot rolling is finished. The said rapid cooling is performed by water cooling, The manufacturing method of the copper alloy board | plate material of Claim 4 characterized by the above-mentioned. The copper alloy sheet according to any one of claims 1 to 5, wherein after the aging treatment, finish cold rolling is performed at a rolling rate of 10 to 30%, and then low temperature annealing is performed at 350 to 425 ° C. Production method. It contains 0.25 to 1.5% by mass of Zr and 0.01 to 1.0% by mass of Cr, with the balance being composed of Cu and inevitable impurities, with a tensile strength of 600 N / mm ² or more, conductive Cracks occurred after a 90 ° W bending test was performed on a bending test piece having a rate of 75% IACS or more and a longitudinal direction of TD (direction perpendicular to the rolling direction and the plate thickness direction) in accordance with JIS H3110. A copper alloy sheet, wherein a ratio R / t between the minimum bending radius R and the thickness t of the copper alloy sheet is less than 1.0. The composition of the copper alloy further includes a rare earth metal containing Ce and one or more elements selected from the group consisting of Si, Sn, Mg, B and P in a total range of 0.3% by mass or less. The copper alloy sheet material according to claim 7. The copper alloy sheet according to claim 7 or 8, wherein the copper alloy has a two-phase structure composed of a Cu matrix and a second phase. The copper alloy sheet according to claim 9, wherein an average crystal grain size of the Cu matrix is 5 to 20 μm. 11. The copper alloy sheet according to claim 9, wherein a ratio of the area of the eutectic phase existing on the surface of the copper alloy sheet is 4 to 25%. The ratio of the area of the fine eutectic phase of 1 µm ² or less existing on the surface of the copper alloy sheet is 40% or more of the total area of the eutectic phase, according to any one of claims 9 to 11. Copper alloy sheet material. The second phase includes a eutectic phase of a Cu matrix and at least one compound of Cu-Zr and Cu-Cr-Zr, and Cr, Zr, Cr-Zr, Cr-Cu precipitated in the Cu matrix. ,
The copper alloy sheet according to any one of claims 9 to 12, wherein the copper alloy sheet is composed of a compound containing at least one of Zr-Cu and Cr-Zr-Cu.