TW201819644A - Copper alloy plate and method for producing same - Google Patents

Abstract

There are provided an inexpensive copper alloy plate having an excellent bending workability and an excellent stress corrosion cracking resistance while maintaining a high strength, and a method for producing the same. The copper alloy plate is produced by a method comprising the steps of: melting and casting raw materials of a copper alloy, the copper alloy having a chemical composition which contains 17 to 32 wt% of zinc, 0.1 to 4.5 wt% of tin, 0.01 to 2.0 wt% of silicon, 0.01 to 5.0 wt% of nickel, and the balance being copper and unavoidable impurities; hot-rolling the cast copper alloy in a temperature range of from 900 DEG C to 400 DEG C; cooling the hot-rolled copper alloy at a cooling rate of 1 to 15 DEG C/min. from 400 DEG C to 300 DEG C; cold-rolling the cooled copper alloy; recrystallization-annealing the cold-rolled copper alloy at a temperature of 300 to 800 DEG C; and then, ageing annealing the recrystallization-annealed copper alloy at a temperature of 300 to 600 DEG C.

Description

Copper alloy plate and manufacturing method thereof

Field of invention

The invention relates to a copper alloy plate and a manufacturing method thereof, in particular to a Cu-Zn-Sn series copper alloy plate used for electrical electronic parts such as connectors, lead frames, relays, switches, and the like, and a manufacturing method thereof. .

Background of the invention

The materials used for electrical electronic components such as connectors, lead frames, relays, switches, etc., are required to be able to withstand the occurrence of Joule heat caused by electricity, as well as being able to withstand the assembly or operation of electrical electronic equipment. The stress applied is so high. Furthermore, electrical electronic components such as connectors are generally formed by bending, and therefore, they are also required to have excellent bending workability. Furthermore, in order to ensure contact reliability between electrical electronic components such as connectors, it is required to have excellent stress relaxation resistance, that is, durability against a phenomenon that the contact pressure decreases with time (stress relaxation).

In recent years, electrical electronic components such as connectors have tended to become more compact, miniaturized, and lighter. With this, the requirements for thinning of copper or copper alloy materials as materials have continued to increase. Therefore, the strength level required for the material becomes more severe. In addition, it is necessary to cope with the miniaturization or complication of the shape of electrical electronic components such as connectors, and it is required to improve the shape or dimensional accuracy of a bent product. In addition, in recent years, there is a tendency to reduce environmental load, save resources, and save energy. As a result, the cost of raw materials or manufacturing costs of copper or copper alloy plates as materials has decreased, and the recycling of products has been reduced. The requirements are even higher.

However, due to the trade-off relationship between sheet strength and electrical conductivity, strength and bending workability, bending workability and stress relaxation resistance, they have previously been used as electrical components of such connectors and the like. According to the application, the sheet of flexible electronic parts is suitably selected to have a good conductivity and strength, bending workability or stress relaxation resistance, and a lower cost.

In addition, brass, phosphor bronze, and the like have conventionally been used as general-purpose materials for electrical electronic components such as connectors. Phosphor bronze has an excellent balance of strength, corrosion resistance, stress corrosion cracking resistance, and stress relaxation resistance. For example, in the case of two phosphor bronzes (C5191), hot working cannot be performed, and high-priced Sn contains about 6% is also disadvantageous in terms of cost.

On the other hand, brass (Cu-Zn-based copper alloy) is widely used as a raw material, has a low manufacturing cost, and is excellent in recyclability of products. However, the strength of brass is lower than that of phosphor bronze. The highest strength of brass is EH (H06). For example, for a slat product of brass 1 (C2600-SH), the tensile strength is generally around 550 MPa. This tensile strength is equivalent to the tensile strength of the two kinds of phosphor bronze, the refining degree H (H04). In addition, the slat products of one brass type (C2600-SH) are not good in stress corrosion cracking resistance.

In addition, in order to increase the strength of brass, it is necessary to increase the finishing rolling rate (increasing the degree of refining). With this, the bending workability in a direction perpendicular to the rolling direction (that is, the bending axis is relatively The bending workability in the direction parallel to the rolling direction) is significantly deteriorated. Therefore, even a brass having a high strength grade may not be processed into electrical electronic components such as connectors. For example, once the precision rolling rate of brass is increased and the tensile strength is set to be higher than 570 MPa, it becomes difficult to press-mold to form a small component.

In particular, in a simple alloy brass composed of Cu and Zn, it is not easy to improve bending workability while maintaining strength. As a result, some people took the time to add various elements to brass to increase the strength level. For example, a Cu-Zn-based copper alloy to which a third element such as Sn, Si, and Ni is added has been proposed (for example, refer to Patent Documents 1 to 3). Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2001-164328 (paragraph number 0013) Patent Document 2: Japanese Patent Laid-open No. 2002-88428 (paragraph number 0014) Patent Literature 3: Japanese Patent Laid-open No. 2009-62610 (paragraph number 0019) )

Summary of the Invention Problems to be Solved by the Invention

However, even if Sn, Si, Ni, etc. are added to brass (Cu-Zn-based copper alloy), the bending workability may not be sufficiently improved.

Therefore, in view of such a conventional problem, an object of the present invention is to provide a low-cost copper alloy plate material and a manufacturing method thereof, which maintain high strength while being excellent in bending workability and stress corrosion cracking resistance. Means to solve the problem

The inventors of the present case made intensive research in order to solve the above-mentioned problems, and as a result, it was found that by performing the following, a copper alloy sheet having excellent bending workability, excellent stress corrosion cracking resistance, and low cost can be manufactured while maintaining high strength, Finally, the present invention is completed: the raw materials of the copper alloy are melted, cast, and hot rolled in a temperature range of 900 ° C to 400 ° C, and then cooled to 400 ° C to 300 ° C at a cooling rate of 1 to 15 ° C / minute, and then, After cold rolling, recrystallization annealing is performed at 300 to 800 ° C, and then aging annealing is performed at 300 to 600 ° C. The raw materials of the aforementioned copper alloy have the following composition: 17 to 32% by mass of Zn, 0.1 to 4.5 mass% of Sn, 0.01 to 2.0 mass% of Si, and 0.01 to 5.0 mass% of Ni, and the remainder is Cu and unavoidable impurities.

That is, the method for manufacturing a copper alloy sheet according to the present invention is characterized in that a copper alloy sheet is produced by melting and casting a raw material of a copper alloy, and performing hot rolling in a temperature range of 900 ° C to 400 ° C. Cool to 400 ° C to 300 ° C at a cooling rate of 1 to 15 ° C / min, and then perform recrystallization annealing at 300 to 800 ° C after cold rolling, followed by aging annealing at 300 to 600 ° C; The raw material of the copper alloy has the following composition: contains 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass of Ni, and the remainder is Cu and unavoidable Impure.

In the manufacturing method of the copper alloy sheet material, it is preferable to perform cold-rolling finishing after aging annealing, and then perform low-temperature annealing at a temperature below 450 ° C. Alternatively, cold rolling may be performed after recrystallization annealing and before aging annealing. In addition, the raw material of the copper alloy may have a composition selected from the group consisting of Fe, Co, Cr, Mg, Al, B, P, Zr, Ti, Mn, Au, and Ag in a total content of 3% by mass or less. , Pb, Cd, and Be more than one element in the group.

In addition, the copper alloy sheet material of the present invention is characterized by having the following composition: 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass of Ni And the remainder is Cu and unavoidable impurities; and after applying a bending stress equivalent to 80% of the 0.2% off-position and falling strength of the copper alloy sheet, the copper alloy sheet is kept in a The time until a crack is observed in a copper alloy sheet in a desiccator is 10 times or more compared to a sheet of brass 1 (C2600-SH). The number of coarse precipitates with a particle size of 1 μm or more per unit area on the surface of the copper alloy sheet material is preferably 15000 pieces / mm ² or less.

Furthermore, the copper alloy sheet material of the present invention is characterized by having the following composition: 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass of Si. Ni, and the remaining portion is Cu and unavoidable impurities; and the number of coarse precipitates with a particle size of 1 μm or more per unit area on the surface of the copper alloy sheet is 15000 pieces / mm ² or less.

In the above-mentioned copper alloy sheet, the tensile strength should be above 550 MPa, and the 0.2% off-position and falling-off strength should be above 500 MPa. The conductivity is preferably 10% IACS or more. In addition, the copper alloy sheet material may have a composition selected from the group consisting of Fe, Co, Cr, Mg, Al, B, P, Zr, Ti, Mn, Au, Ag, and One or more elements in the group consisting of Pb, Cd, and Be. The average crystal grain size on the surface of the copper alloy sheet material is preferably 10 μm or less.

Furthermore, the connector terminal of the present invention is characterized by using the above-mentioned copper alloy plate material as a material. Invention effect

According to the present invention, a low-cost copper alloy sheet having excellent bending workability and excellent stress corrosion crack resistance while maintaining high strength can be manufactured.

Forms used to implement the invention

An embodiment of the method for manufacturing a copper alloy sheet of the present invention includes the following steps: melting, casting, and melting steps of a copper alloy raw material; after the melting and casting steps, in a temperature range of 900 ° C to 400 ° C After the hot rolling, a hot rolling step of cooling to 400 ° C. to 300 ° C. at a cooling rate of 1 to 15 ° C./min; a cold rolling step of cold rolling after the hot rolling step; After the step, a recrystallization annealing step of recrystallization annealing is performed at 300 to 800 ° C; after the recrystallization annealing step, an aging annealing step of annealing is performed at 300 to 600 ° C; if necessary, a finishing cold is performed after the aging annealing step. Rolled finishing cold rolling step; a low temperature annealing step of performing low temperature annealing at a temperature of 450 ° C. or lower after the finishing cold rolling step; the raw material of the copper alloy has the following composition: containing 17 to 32% by mass Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass of Ni, and the remaining portion is Cu and unavoidable impurities. These steps are described in detail below. In addition, after hot rolling, veneering can be performed according to demand; after each heat treatment, pickling, grinding, and degreasing can also be performed according to demand.

(Melting and Casting Step) After melting the raw material of the copper alloy by the same method as the general brass melting method, a cast piece is produced by continuous casting, semi-continuous casting, or the like. In addition, the gas environment when melting the raw materials may be an atmospheric gas environment.

(Hot-rolling step) Generally, in the hot-rolling of Cu-Zn-based copper alloys, rolling is performed in a high-temperature region of 650 ° C or higher and 700 ° C or higher, and recrystallization is performed during and between rolling passes. In order to destroy the casting structure and soften the material. However, if rolling is performed at a high temperature exceeding 900 ° C., cracks may occur due to the segregation portion of the alloy composition and the like, and the melting point may decrease, which is not suitable. Therefore, when hot rolling at 900 ° C to 400 ° C and then cooling to room temperature, the average cooling rate up to 400 ° C to 300 ° C is set to 1 to 15 ° C / min.

(Cold-rolling step) In this cold-rolling step, it is preferable to set the working ratio to 50% or more, more preferably 80% or more, and most preferably 90% or more. In addition, the cold rolling may be repeated by inserting an intermediate annealing performed at 300 to 650 ° C.

(Recrystallization Annealing Step) In this recrystallization annealing step, annealing is performed at 300 to 800 ° C. In addition, in this intermediate annealing step, in order to make the average crystal grain size after annealing to be 10 μm or less (preferably 9 μm or less), it is preferable to set a holding time and an arrival temperature at 300 to 800 ° C. and perform heat treatment. In addition, although the grain size of the recrystallized grains obtained by this annealing varies depending on the cold rolling process ratio or chemical composition before annealing, if the annealing temperature curve and average value of each alloy are obtained in advance through experiments, The relationship between the crystal grain size can be set at a holding time of 300 to 800 ° C and an arrival temperature. Specifically, in terms of the chemical composition of the copper alloy sheet of the present invention, it can be held at 300 to 800 ° C (preferably 450 to 800 ° C, more preferably 500 to 800 ° C, and most preferably 575 to 800 ° C) for a few seconds ~ Set appropriate conditions among the heating conditions for several hours.

(Aging annealing step) In this aging annealing step, annealing is performed at 300 to 600 ° C (preferably 350 to 550 ° C). The aging annealing temperature is preferably lower than the recrystallization annealing temperature. In addition, cold rolling may be performed after recrystallization annealing and before aging annealing, and in this case, cold rolling and low temperature annealing may not be performed.

(Finished Cold Rolling Step) Finished cold rolling is performed to increase the strength level. Although the processing rate of finishing cold rolling is too low, the strength will be low, but the processing rate of finishing cold rolling is too high, and the improved crystal orientation of both strength and bending workability will become impossible. Therefore, in this finishing cold step, the processing rate should be set to 1 to 40%, and more preferably 3 to 35%.

(Low temperature annealing step) After finishing cold rolling, in order to improve the stress corrosion cracking resistance or bending workability by reducing the residual stress of the copper alloy sheet, and to improve the resistance by reducing the difference in voids or sliding surfaces Stress relaxation characteristics can also be low temperature annealing. By the low temperature annealing, the strength, the stress corrosion crack resistance, the bending workability, and the stress relaxation resistance can be simultaneously improved, and the conductivity can be improved. Once this heating temperature is too high, it will soften in a short time, and whether it is batch or continuous, it will become easy to produce characteristic deviation. Therefore, in this low temperature annealing step, annealing is performed at a temperature of 450 ° C or lower (preferably 300 to 450 ° C).

According to the embodiment of the manufacturing method of the copper alloy plate, the embodiment of the copper alloy plate of the present invention can be manufactured.

An embodiment of the copper alloy sheet material of the present invention has the following composition: 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass of Ni, and the remainder Part is Cu and unavoidable impurities; after applying a bending stress equivalent to 80% of the 0.2% off-position and falling strength of the copper alloy sheet, the copper alloy sheet is kept at 25 ° C in a dry state containing 3% by mass ammonia water. The time until the crack was observed in the copper alloy sheet material was 10 times or more compared with the brass one type (C2600-SH) sheet material.

The embodiment of the copper alloy sheet of the present invention is a sheet made of a Cu-Zn-Sn-Si-Ni alloy, and it is added to a Cu-Zn-based alloy containing Cu and Zn with Sn, Si, and Ni added. .

Zn has the effect of improving the strength or spring property of a copper alloy sheet. Since Zn is cheaper than Cu, it is advisable to add a large amount of Zn. However, once the Zn content exceeds 32% by mass, the cold workability of copper alloy plates will be significantly reduced and the resistance to stress corrosion cracking will be reduced due to the formation of β phase. In addition, the plateability or weldability when subjected to moisture or heat will decrease. Solderability will also decrease. On the other hand, once the Zn content is less than 17% by mass, the 0.2% off-position yield strength or tensile strength of copper alloy sheet material may be insufficient, or the elasticity may be insufficient, and the Young's modulus will increase; furthermore, When the copper alloy sheet is melted, the amount of hydrogen adsorption will increase, and the blowholes of the ingot will become easy to produce; moreover, the low-priced amount of Zn will be disadvantageous on an economic level. Accordingly, the Zn content is preferably 17 to 32% by mass, and more preferably 18 to 31% by mass.

Sn has the effect of improving the strength, stress relaxation resistance and stress corrosion cracking resistance of copper alloy sheet. In order to use Sn as a surface treatment material such as Sn plating again, the copper alloy sheet material should preferably contain Sn. However, if the Sn content exceeds 4.5% by mass, the electrical conductivity of the copper alloy sheet will decrease sharply, and grain boundary segregation will become intense under the coexistence with Zn, and the hot workability will be significantly reduced. On the other hand, if the content of Sn is less than 0.1% by mass, the effect of improving the mechanical properties of the copper alloy sheet becomes low, and further, it is difficult to use pressed chips such as Sn plating as a raw material. Accordingly, when the copper alloy sheet contains Sn, the Sn content is preferably 0.1 to 4.5% by mass, and more preferably 0.2 to 2.5% by mass.

Even a small amount of Si has the effect of improving the stress corrosion cracking resistance of the copper alloy sheet. In order to fully obtain this effect, the Si content is preferably 0.01% by mass or more. However, once the Si content exceeds 2.0% by mass, the electrical conductivity is liable to decrease; and since Si is an element which is easily oxidized and the castability is easily reduced, the Si content is preferably not excessive. Accordingly, when the copper alloy sheet contains Si, the Si content is preferably 0.01 to 2.0% by mass, and more preferably 0.1 to 1.5% by mass. In addition, by forming a compound with Ni and dispersing and precipitating Si, the conductivity, strength, elastic limit value, and stress relaxation resistance of the copper alloy sheet can be improved.

Ni has the effect of improving the solid solution strengthening effect and stress relaxation resistance of the copper alloy sheet. In particular, the zinc equivalent of Ni is a negative value, and by suppressing the formation of β phase, it has the effect of suppressing the deviation of characteristics during mass production. In order to fully exert these effects, the Ni content is preferably 0.01% by mass or more. On the other hand, if the Ni content exceeds 5.0% by mass, the electrical conductivity is significantly reduced. Accordingly, when the copper alloy sheet contains Ni, the Ni content is preferably 0.01 to 5.0% by mass, and more preferably 0.1 to 4.5% by mass.

In addition, the copper alloy sheet material may further have a composition of 3% by mass or less (preferably 1% by mass or less, and more preferably 0.5% by mass or less). , Al, B, P, Zr, Ti, Mn, Au, Ag, Pb, Cd and Be in the group of one or more elements.

Since the average crystal grain size of the copper alloy sheet is smaller, it is more advantageous for improving the bending workability, so it is preferably 10 μm or less, more preferably 1 μm to 9 μm or less, and even more preferably 2 to 8 μm.

In order to reduce the size and thickness of electrical electronic components such as connectors, the tensile strength of the copper alloy sheet should be 550 MPa or more, more preferably 600 MPa or more, and most preferably 640 or more. In addition, the 0.2% off-position yielding strength of the copper alloy sheet should preferably be 500 MPa or more, more preferably 550 MPa or more, and most preferably 580 MPa or more.

With the increase in the accumulation of electrical electronic components such as connectors, in order to suppress the Joule heat generated by energization, the conductivity of the copper alloy sheet should be 10% IACS or more, and more preferably 15% IACS or more.

The evaluation of the stress corrosion crack resistance of the copper alloy sheet is to cut out a test piece from the copper alloy sheet and apply a bending stress equivalent to 80% of the 0.2% off-position yield strength to the test piece, and keep the test piece at 25 ° C. In a desiccator containing 3% by mass of ammonia water, take out the test piece every 1 hour and observe the test piece under the crack at 100 times magnification through an optical microscope. The time until the crack is observed should be more than 50 hours. , More preferably 60 hours or more. In addition, compared with a commercially available brass (C2600-SH) sheet, the time is preferably 10 times or more, and more preferably 12 times or more.

In addition, the evaluation of the bending workability of the copper alloy sheet material was performed by cutting the bending test piece from the copper alloy sheet material so that the length direction was TD (the direction perpendicular to the rolling direction and the thickness direction), and using When LD (rolling direction) is a bending axis and a 90 ° W bending test is performed, the ratio R / t of the minimum bending radius R to the plate thickness t in the 90 ° W bending test is preferably 1.0 or less, more preferably 0.7 or less, The most preferable value is 0.6 or less.

In addition, the number of coarse precipitates per unit area of the surface of the copper alloy sheet (with a particle diameter of 1 μm or more) is preferably 15,000 pieces / mm ² or less, and more preferably 12,000 pieces / mm ² or less. By suppressing the formation of coarse precipitates of Ni or Si and finely depositing Ni or Si as described above, a copper alloy having excellent bending workability and excellent stress corrosion cracking resistance while maintaining high strength can be manufactured. Plate. [Example]

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 16 and Comparative Examples 1 to 8] Ingots were prepared by melting and casting the following copper alloys, respectively, and 40 mm × 40 mm × 20 mm ingots were cut from the ingots respectively: containing 19.7% by mass Zn, 0.77% by mass of Sn, 1.05% by mass of Si, 3.85% by mass of Ni, and the remaining portion made of Cu (Example 1); Cu containing 20.9% by mass of Zn, 0.79% by mass of Sn, 0.95 Copper alloy (Example 2) composed of Si by mass%, 2.81% by mass of Ni, and the remainder being made of Cu; 20.5% by mass of Zn, 0.71% by mass of Sn, 0.98% by mass of Si, and 1.24% by mass of Ni And a copper alloy (Example 3) composed of Cu; and 22.1% by mass of Zn, 0.79% by mass of Sn, 0.47% by mass of Si, and 2.63% by mass of Ni, and the remaining portion of Cu is composed of Cu (Example 4) A copper alloy (Example 5) containing 19.9% by mass of Zn, 0.76% by mass of Sn, 0.46% by mass of Si, and 1.67% by mass of Ni, and the remainder being composed of Cu (Example 5); Zn, 0.77% by mass of Sn, 0.46% by mass of Si, 0.96% by mass of Ni, and the remainder of Cu is a copper alloy (Example 6); contains 19.8% by mass of Zn, 0.75% by mass of Sn Copper alloy of 0.49% by mass of Si, 0.45% by mass of Ni, and the remainder made of Cu (Example 7); containing 19.8% by mass of Zn, 0.25% by mass of Sn, 1.01% by mass of Si, and 3.82% by mass of Copper alloy containing Ni and the remainder of Cu (Example 8); copper containing 21.1% by mass of Zn, 2.08% by mass of Sn, 0.50% by mass of Si, and 1.89% by mass of Ni, and the remainder of Cu consisting of Cu Alloy (Example 9); a copper alloy containing 30.1% by mass of Zn, 0.75% by mass of Sn, 0.50% by mass of Si, 1.78% by mass of Ni, and the remainder being made of Cu (Example 10); containing 20.0% by mass % Zn, 0.77% by mass of Sn, 1.00% by mass of Si, 3.75% by mass of Ni, and the remaining portion is made of Cu (Example 11); Cu contains 20.1% by mass of Zn, 0.72% by mass of Sn, 1.00% by mass of Si, 3.91% by mass of Ni, and the remaining portion made of Cu (Example 12); Cu containing 22.0% by mass of Zn, 0.77% by mass of Sn, 0.49% by mass of Si, and 2.00% by mass of Ni, 0.15% by mass of Fe, 0.08% by mass of Co, 0.07% by mass of Cr, and the remainder of Cu is a copper alloy (Example 13); contains 23.2% by mass of Zn, 0.78% by mass Sn, 0.50% by mass of Si, 2.01% by mass of Ni, 0.08% by mass of Mg, 0.08% by mass of Al, 0.10% by mass of Zr, 0.10 of Ti, and a copper alloy composed of Cu in the remainder (Example 14) ; Contains 22.5 mass% of Zn, 0.80 mass% of Sn, 0.49 mass% of Si, 1.90 mass% of Ni, 0.05 mass% of B, 0.05 mass% of P, 0.08 mass% of Mn, and 0.10 mass% of Be, And the remaining portion is a copper alloy made of Cu (Example 15); containing 21.5 mass% Zn, 0.78 mass% Sn, 0.50 mass% Si, 1.85 mass% Ni, 0.05 mass% Au, 0.08 mass% Copper alloy with Ag, 0.08 mass% Pb, 0.07 mass% Cd, and the remainder consisting of Cu (Example 16); copper containing 24.5 mass% Zn, 0.77 mass% Sn, and the remainder consisting of Cu Alloy (Comparative Examples 1 to 2); a copper alloy containing 24.5% by mass of Zn, 0.77% by mass of Sn, 0.50% by mass of Si, and 1.99% by mass of Ni, and the remainder being made of Cu (Comparative Examples 3 to 4) ; A copper alloy containing 24.5% by mass of Zn, 0.77% by mass of Sn, 1.89% by mass of Ni, and 0.02% by mass of P, and the remainder being made of Cu (Comparative Example 5); 24.0% by mass of Zn, 0.77% by mass % S n, 1.97 mass% of Ni and a copper alloy composed of Cu (Comparative Example 6); 19.8% by mass of Zn, 0.75% by mass of Sn, 0.49% by mass of Si, 0.45% by mass of Ni, and the remainder A copper alloy partially composed of Cu (Comparative Examples 7 to 8).

Each cast piece was heated at 800 ° C for 30 minutes, and then hot-rolled in a temperature range of 800 ° C to 400 ° C to make a thickness of 10 mm (processing rate 50%), and then cooled from 400 ° C to room temperature. In this cooling, the cooling between 400 ° C and 300 ° C was performed at an average cooling rate of 5 ° C / min in Examples 1 to 12 (Examples 1, 3, 4, 6, 7, 9 ~ 13, 15, 16, Comparative Examples 5 to 6), 10 ° C / min (Example 2), 2 ° C / min (Examples 5, 8, 14), 20 ° C / min (Comparative Examples 4, 8); and Comparative Examples 1 to 3 and 7 were performed by quenching with water.

Then, cold rolling was performed to a thickness of 0.26 mm (Examples 1, 2, 9, and Comparative Example 3), 0.28 mm (Examples 3 to 5, 8, 10, 13 to 16, Comparative Example 4), and 0.4 mm. (Examples 6 to 7, Comparative Examples 7 to 8), 0.38 mm (Example 11, Comparative Examples 1, 2, 5, 6), and 0.30 mm (Example 12). In Comparative Examples 1, 5, and 6, cold rolling was performed twice by inserting intermediate annealing at 550 ° C, holding at 625 ° C, and holding at 550 ° C for 1 hour.

Thereafter, the temperature was maintained at 800 ° C for 10 minutes (Examples 1, 11, 12), 750 ° C for 10 minutes (Examples 2 to 5, 10, 13 to 16, Comparative Examples 3 to 4), and 600 ° C for 10 minutes (implementation). Examples 6-7, Comparative Examples 7-8), 700 ° C for 30 minutes (Examples 8 and 9), 550 ° C for 30 minutes (Comparative Examples 1, 6), 525 ° C for 30 minutes (Comparative Example 2), 600 ° C for 30 minutes (Comparative Example 5) Intermediate annealing (recrystallization annealing). Subsequently, in Examples 6 to 7 and Comparative Examples 7 to 8, cold rolling was performed until the thickness was 0.25 mm.

Then, in Examples 1 to 16, and Comparative Examples 3 to 4, and 7 to 8, they were maintained at 425 ° C for 3 hours (Examples 1 to 5, 10 to 11, 13 to 16, and Comparative Examples 3 to 4). ), 450 ° C for 30 minutes (Examples 6 to 7, Comparative Examples 7 to 8), 500 ° C for 3 hours (Example 8), 350 ° C for 3 hours (Example 9), 550 ° C for 3 hours (Example 12) Aging annealing.

Then, in Examples 1 to 5, 8 to 16, and Comparative Examples 1 to 6, the processing rates were 5% (Examples 1, 2, 9, and Comparative Example 3) and 11% (Examples 3 to 5, and 8, 10, 13-16, Comparative Example 4), 33% (Example 11, Comparative Examples 1-2, 5-6), and 16% (Example 12) After finishing cold-rolling, each Low temperature annealing at 350 ° C for 30 minutes (Examples 1 to 5, 8 to 16, Comparative Examples 3 to 5) and 300 ° C for 30 minutes (Comparative Examples 1 to 2, 6).

The copper alloy sheets of Examples 1 to 16 and Comparative Examples 1 to 8 were obtained through the above, and samples were taken from them, and the average crystal grain size, electrical conductivity, tensile strength, stress corrosion cracking resistance, and bending processing of the crystal grain structure were obtained. The sex survey is as follows.

The average crystal grain size of the crystal grain structure is measured by grinding a plate surface (rolled surface) of a copper alloy sheet, etching it, observing the surface with an optical microscope, and following the cutting method of JIS H0501. Determination. As a result, the average crystal grain size was 5 μm (Examples 1, 3 to 5, 7, 12 and Comparative Examples 1 to 2, 7 to 8) and 4 μm (Examples 2, 10, 11, 13 to 16, and comparison). Examples 3 to 6), 6 μm (Example 6), 3 μm (Examples 8 and 9).

The electrical conductivity of a copper alloy sheet is measured in accordance with the electrical conductivity measurement method of JIS H0505. As a result, the electrical conductivity was 21.7% IACS (Example 1), 20.6% IACS (Example 2), 16.4% IACS (Example 3), 23.9% IACS (Example 4), and 23.6% IACS (Example). 5), 20.6% IACS (Example 6), 19.5% IACS (Example 7), 27.9% IACS (Example 8), 18.5% IACS (Example 9), 19.2% IACS (Example 10), 22.0% IACS (Example 11), 21.7% IACS (Example 12), 23.4% IACS (Example 13), 23.5% IACS (Example 14), 24.0% IACS (Example 15), 22.1% IACS (Example 16) ), 25.3% IACS (Comparative Example 1), 24.8% IACS (Comparative Example 2), 19.5% IACS (Comparative Example 3), 21.6% IACS (Comparative Example 4), 18.2% IACS (Comparative Example 5), 16.2% IACS (Comparative Example 6), 19.5% IACS (Comparative Example 7), 19.5% IACS (Comparative Example 8).

As the tensile strength of the mechanical properties of the copper alloy plate, three test pieces (JISLDZ2201 No. 5 test piece) for LD (rolling direction) tensile test of the copper alloy plate were used. The tensile test of JIS Z2241, and the 0.2% eccentric dropout strength and tensile strength of LD were obtained from the average value. As a result, the 0.2% eccentric drop-out strength and tensile strength of LD were 589 MPa and 677 MPa (Example 1), 554 MPa and 637 MPa (Example 2), 587 MPa and 652 MPa (Example 3), 587 MPa and 676 MPa (implementation). Example 4), 601 MPa and 664 MPa (Example 5), 633 MPa and 682 MPa (Example 6), 630 MPa and 680 MPa (Example 7), 590 MPa and 655 MPa (Example 8), 590 MPa and 685 MPa (Example 9), 585 MPa And 644MPa (Example 10), 660MPa and 735MPa (Example 11), 583MPa and 677MPa (Example 12), 601MPa and 651MPa (Example 13), 598MPa and 655MPa (Example 14), 600MPa and 653MPa (Example 15), 595 MPa and 658 MPa (Example 16), 593 MPa and 659 MPa (Comparative Example 1), 589 MPa and 660 MPa (Comparative Example 2), 583 MPa and 650 MPa (Comparative Example 3), 583 MPa and 650 MPa (Comparative Example 4), 596 MPa and 652 MPa (Comparative Example 5), 584 MPa and 642 MPa (Comparative Example 6), 625 MPa and 675 MPa (Comparative Example 7), 623 MPa and 678 MPa (Comparative Example 8).

The stress corrosion crack resistance of the copper alloy sheet is obtained by bending a test piece with a width of 10 mm from the copper alloy sheet, and making the surface stress in the central part of the length direction of the test piece to be 0.2% and 80% of the deviating strength. The test piece was arched, and in this state, the test piece was kept at 25 ° C. in a desiccator containing 3% by mass of ammonia water, and a test piece with a width of 10 mm was taken out every one hour and passed through an optical microscope at a magnification of 100 times. The test piece was observed under the cracks at 75 hours (Example 1), 76 hours (Example 2), 89 hours (Example 3), 64 hours (Example 4), 67 hours (Example 5), 80 Hours (Example 6), 75 hours (Example 7), 75 hours (Example 8), 128 hours (Example 9), 87 hours (Example 10), 65 hours (Example 11), 66 hours ( Example 12), 75 hours (Example 13), 74 hours (Example 14), 72 hours (Example 15), 75 hours (Example 16), 24 hours (Comparative Example 1), 25 hours (Comparative Example) 2), 39 hours (Comparative Example 3), 37 hours (Comparative Example 4), 30 hours (Comparative Example 5), 25 hours (Comparative Example 6), 30 hours (Comparative Example 7), 24 hours (Comparative Example 8) After the crack was observed In addition, compared with a commercially available brass (C2600-SH) sheet, the time until cracks were observed was 15 times (Example 1), 15 times (Example 2), and 18 times, respectively. (Example 3), 13 times (Example 4), 13 times (Example 5), 16 times (Example 6), 15 times (Example 7), 15 times (Example 8), 26 times (Implementation) Example 9), 17 times (Example 10), 13 times (Example 11), 13 times (Example 12), 15 times (Example 13), 15 times (Example 14), 14 times (Example 15) ), 15 times (Example 16), 5 times (Comparative Example 1), 5 times (Comparative Example 2), 8 times (Comparative Example 3), 7 times (Comparative Example 4), 6 times (Comparative Example 5), 5 times (Comparative Example 6), 6 times (Comparative Example 7), 5 times (Comparative Example 8).

In order to evaluate the bending workability of the copper alloy sheet, a bending test piece (width 10 mm) was cut from the copper alloy sheet so that the length direction was TD (the direction perpendicular to the rolling direction and the thickness direction), and LD ( The rolling direction was set as a bending axis (Bad Way bending; BW bending), and a 90 ° W bending test according to JIS H3110 was performed. With respect to the test piece after the test, the surface and cross section of the bent portion were observed with an optical microscope at a magnification of 100 times, and the minimum bending radius R without cracks was obtained, and the minimum bending radius R was divided by the copper alloy. The plate thickness t of the plate is used to obtain the respective R / t values. As a result, R / t was 0.4 (Examples 1, 2, 6 to 8), 0.6 (Examples 3 to 5, 9 to 16), and 0.8 (Comparative Examples 1 to 8).

In addition, samples were taken from the copper alloy sheets of Examples 1 to 16 and Comparative Examples 3 to 4 and 7 to 8, and the surface (particle diameter (the diameter of the smallest circle of the circle-enclosed precipitate) of 1 μm or more) was coarsely precipitated. The number of objects (per unit area). The number of coarse precipitates on the surface of the copper alloy sheet was obtained by taking a sample from a copper alloy sheet as an anode and a stainless steel plate as a cathode, and energizing it with a voltage of 15 V in 20% by mass of phosphoric acid for 30 seconds. After electrolytic polishing, a scanning electron microscope was used to observe the secondary electron image of the precipitates on the surface of the sample at a magnification of 3000 times, and the coarse precipitates were counted to obtain it. As a result, the number of coarse precipitates on the surface of the copper alloy sheet material was 7700 pieces / mm ² (Example 1), 5000 pieces / mm ² (Example 2), 2100 pieces / mm ² (Example 3), and 7800 pieces. / mm ² (Example 4), 8800 pieces / mm ² (Example 5), 600 pieces / mm ² (Example 6), 600 pieces / mm ² (Example 7), 7500 pieces / mm ² (Example 8), 7000 pieces / mm ² (Example 9), 7600 pieces / mm ² (Example 10), 7700 pieces / mm ² (Example 11), 11,000 pieces / mm ² (Example 12), 7200 pieces / mm ² (Example 13), 6900 pieces / mm ² (Example 14), 8000 pieces / mm ² (Example 15), 7800 pieces / mm ² (Example 16), 20600 pieces / mm ² (Comparative Example 3) ), 21,000 pieces / mm ² (Comparative Example 4), 16,000 pieces / mm ² (Comparative Example 7), and 17,800 pieces / mm ² (Comparative Example 8).

The manufacturing conditions and characteristics of these examples and comparative examples are shown in Tables 1 to 3.

[Table 1]

[Table 2]

[table 3]

Claims (13)

A method for manufacturing a copper alloy plate, which is characterized in that the copper alloy plate is manufactured by melting, casting, and hot-rolling a copper alloy at a temperature range of 900 ° C to 400 ° C at a cooling rate of 1 ~ 15 ° C / min, cooling to 400 ° C ~ 300 ° C, followed by cold rolling and recrystallization annealing at 300 ~ 800 ° C, and then aging annealing at 300 ~ 600 ° C; the raw materials of the aforementioned copper alloy It has the following composition: it contains 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass of Ni, and the remainder is Cu and unavoidable impurities. For example, the method for manufacturing a copper alloy sheet material according to claim 1, after performing the aforementioned aging annealing, finishing cold rolling, and then performing low temperature annealing at a temperature below 450 ° C. For example, the method for manufacturing a copper alloy sheet material according to claim 1, which comprises performing cold rolling after performing the aforementioned recrystallization annealing and before performing the aforementioned aging annealing. The method for manufacturing a copper alloy sheet material according to claim 1, wherein the raw material of the copper alloy has the following composition: further contained in a range of 3 mass% or less in total selected from the group consisting of Fe, Co, Cr, Mg, Al, B, One or more elements in the group consisting of P, Zr, Ti, Mn, Au, Ag, Pb, Cd, and Be. A copper alloy plate having the following composition: 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass of Ni, and the remainder Cu and unavoidable impurities; and after applying a bending stress equivalent to 80% of the 0.2% deflection strength of the copper alloy sheet, the copper alloy sheet was kept at 25 ° C in a dry state containing 3% by mass of ammonia water. The time until the crack was observed in the copper alloy sheet material was 10 times or more compared with the brass one type (C2600-SH) sheet material. The copper alloy sheet material according to claim 5, wherein the number of coarse precipitates having a particle diameter of 1 μm or more per unit area on the surface of the copper alloy sheet material is 15,000 pieces / mm ² or less. A copper alloy plate having the following composition: 17 to 32% by mass of Zn, 0.1 to 4.5% by mass of Sn, 0.01 to 2.0% by mass of Si, and 0.01 to 5.0% by mass of Ni, and the remainder Cu and unavoidable impurities; and the number of coarse precipitates having a particle diameter of 1 μm or more per unit area on the surface of the copper alloy sheet is 15,000 pieces / mm ² or less. The copper alloy sheet material according to any one of claims 5 to 7, wherein the tensile strength of the copper alloy sheet material is 550 MPa or more. The copper alloy sheet material according to any one of claims 5 to 7, wherein the 0.2% deviation yield strength of the aforementioned copper alloy sheet material is 500 MPa or more. The copper alloy sheet according to any one of claims 5 to 7, wherein the electrical conductivity of the aforementioned copper alloy sheet is 10% IACS or more. The copper alloy sheet material according to any one of claims 5 to 7, wherein the copper alloy sheet material has a composition further selected from the group consisting of Fe, Co, Cr, Mg, Al, and One or more elements in the group consisting of B, P, Zr, Ti, Mn, Au, Ag, Pb, Cd, and Be. The copper alloy sheet material according to any one of claims 5 to 7, wherein the average crystal grain size on the surface of the copper alloy sheet material is 10 μm or less. A connector terminal characterized in that a copper alloy plate material as in any one of claims 5 to 7 is used as a material.