JP5619391B2 - Copper alloy material and method for producing the same - Google Patents

Description

The present invention relates to a copper alloy material excellent in strength and conductivity suitable for electronic parts such as terminals and connectors, and a method for producing the same.

In recent years, electronic devices that carry a large current have been reduced in size and weight, and electronic component materials are strongly required to have high conductivity and excellent strength. A Cu—Co—Si based copper alloy containing cobalt (Co) and silicon (Si) as main additive elements has excellent mechanical strength and electrical conductivity, and is therefore suitable for the electronic component. Is done.

In order to improve the characteristics of this Cu—Co—Si based copper alloy material, various techniques have been studied. For example, an additive element is added, and there are techniques for improving castability and hot workability and techniques for enhancing solid solution (see Patent Documents 1 to 8).

JP-A-61-87838 JP-A 63-307232 Japanese Patent Laid-Open No. 02-129326 Japanese Patent Laid-Open No. 02-277735 JP 2008-88512 A JP 2008-55977 A Japanese Patent No. 3408021 International Publication No. 2009/096546

By the way, the copper alloy material which made Co and Si the main addition element proposed by patent documents 1-8 is obtained by trying optimization of an addition element, and optimization of a one part process. However, regarding the copper alloy materials described in these documents, the inventor considered that there is a possibility that the characteristics of the copper alloy raw material cannot be sufficiently extracted, and there is a possibility of further improvement of the characteristics.
Accordingly, the present invention provides a Cu-Co-Si-based alloy having a strength and conductivity required for electronic parts such as connector terminals, and a copper alloy material in which the characteristics of the copper alloy raw material are sufficiently extracted and It aims at providing the manufacturing method.

The above problems are solved by the following invention.
(1) Cobalt (Co) is contained in an amount of 0.7 to 2.5% by mass, silicon (Si) is contained so that the Co / Si content ratio Co / Si is in the range of 3 to 5, and the balance After the copper alloy raw material consisting of Cu and inevitable impurities is melted and cast to obtain a copper alloy ingot, the heat treatment before recrystallization heat treatment is performed.
The heat treatment process is performed only once before hot rolling, and the heat treatment process is performed at a temperature of 980 ° C. or more and less than 1050 ° C.
For 30 minutes or more, and the temperature at the end of the hot rolling is 800 ° C. or more,
The subsequent cooling is performed at a cooling rate of 30 ° C./second or more until the temperature becomes 250 ° C. or less.
A method for producing a copper alloy material.
(2) The copper alloy raw material further contains one or more additive elements selected from the group consisting of Cr, Fe, Ni, Al, Nb, Ti, V, Mn and Zr in a total of 0.01 to 0 .5m
ass% including manufacturing method of the copper alloy material according to claim 1.
(3) said copper alloy material further Sn, 0~1mass% including a total of one or two or more additive element selected from the group consisting of Mg and Zn, copper alloy according to claim 1 or 2
A method of manufacturing the material.
(4) A copper alloy material manufactured by the method according to any one of claims 1 to 3,
The number of precipitates with a diameter of 200 nm or more after the heat treatment step before the recrystallization heat treatment is 10 ⁶ /
Copper alloy material characterized by being ² mm or less.

In the copper alloy material of the present invention, the number of precipitates having a diameter of 200 nm or more is set to 10 ⁶ pieces / mm ² or less until the heat treatment step is performed only once before the recrystallization heat treatment, and thereafter the copper alloy material is obtained. It is what. Therefore, it is possible to obtain a copper alloy material having strength and conductivity required for electronic parts such as connector terminals and sufficiently extracting the characteristics of the copper alloy raw material. In addition, the number of heat treatment steps can be minimized, and the energy at the time of manufacturing the copper alloy material can be greatly reduced.

It is explanatory drawing which shows an example of the test piece of a Charpy test.

In the following, preferred embodiments of the present invention are described. In the present invention, the copper alloy material means a copper alloy processed into a specific shape such as a plate material, a strip material, or a foil by a rolling process.
In the embodiment of the present invention, Co, Si and other additive elements (Cr, Fe, Ni
, Al, Nb, Ti, V, Sn, Mg, Zn, Mn, and Zr), and the balance contains Cu and inevitable impurities.

In the copper alloy material of the present embodiment, the Co content is 0.7 to 2.5 mass%. The reason for this is to ensure sufficient strength as a product. If it is less than 0.7 mass%, Si
The strength obtained by the precipitation becomes insufficient. Further, if it exceeds 2.5 mass%, it cannot be completely dissolved and does not contribute to strengthening of the alloy. Preferably 0.9-2.0m
ass%.

The Si content is set so that the Co / Si ratio Co / Si is in the range of 3-5. The reason for this ratio is to ensure sufficient strength as a product and to facilitate the precipitation of the Co ₂ Si compound that contributes most to strengthening of the alloy and restoring electrical conductivity during aging heat treatment. If the value of Co / Si is less than 3, the strength obtained by precipitation with Co becomes insufficient, and the conductivity tends to decrease due to solid solution. On the other hand, if the value of Co / Si exceeds 5, the strength obtained by precipitation with Co becomes insufficient.

The copper alloy material of this embodiment may further contain at least one selected from the group consisting of Sn, Zn, and Mg in addition to Co and Si. The total amount of these elements added is 1 mas
s% or less, preferably 0.05 to 0.7 mass%, more preferably 0.1 to 0.00%.
5 mass%. By adding these elements, effects of solid solution strengthening of the base material and an increase in work hardening amount during rolling can be obtained. In this embodiment, when the effect of increasing the solid solution strengthening of the base material and the work hardening amount at the time of rolling can be obtained without adding an element selected from the group consisting of Sn, Zn and Mg, It is not necessary to add these elements.

In the copper alloy material of this embodiment, a copper alloy material having a good balance between conductivity and strength can be easily obtained by setting the number of compounds having a diameter of 200 nm or more (preferably 10 μm or less) to 10 ⁶ pieces / mm ^2. be able to. In particular, the number of precipitates having a diameter of 200 nm or more that does not contribute to the improvement in properties such as strength and conductivity of the copper alloy material after the heat treatment step is performed only once before the hot rolling and after the heat treatment step. Maintaining the state of ⁶ pieces / mm ² or less is important in terms of extracting the characteristics of the copper alloy raw material. In addition, the diameter is only 2 in the heat treatment process before hot rolling.
By controlling the number of precipitates of 00 nm or more, it is possible to minimize the number of heat treatment steps, greatly reduce the energy at the time of producing the copper alloy material, and to provide an industrially excellent method for producing a copper alloy material. Can be provided.

In the copper alloy material of the present embodiment, Cr, Fe, Ni, Al, Nb, Ti, V, M
It may contain at least one additional element selected from the group consisting of n and Zr.
These elements are precipitated as compounds together with Co and Si. The total content of the elements is 0
. 01-0.5 mass%. If it is less than 0.01 mass%, the effect of adding the element is not exhibited, and therefore, the characteristics are almost the same as those in the case where the element is not added. Moreover, when it exceeds 0.5 mass%, most of Co and Si are crystallized substances that do not contribute to the improvement of the material strength, so that the material strength is lower than the required strength. The addition amount of these elements is preferably 0.05 to 0.2 mass%.

In the present embodiment, the copper alloy contains one or both of Co and Si and other additive elements (Cr, Fe, Ni, Al, Nb, Ti, V, Zr) and has a diameter of 200 n.
The number of precipitates of m or more (preferably 10 μm or less) is 10 ⁶ / mm ² or less. And this precipitate, in particular, _{Co 2-x} to other _{Co 2 Si Cr x Si, Co} 2-x Fe x Si
Etc.
The diameter and density of the precipitate are obtained by taking a photograph of a cross section in the rolling parallel direction with a scanning electron microscope and measuring the particle size and density of the precipitate on the photograph.

The reason why the number of precipitates having a diameter of 200 nm or more (preferably 10 μm or less) is 10 ⁶ / mm ² or less is to improve the balance between the conductivity and strength of the material. If the number of precipitates exceeds 10 ⁶ / mm ² after the heat treatment step under the condition that the heat treatment step before the recrystallization heat treatment is performed only once before the hot rolling, the characteristics are deteriorated. Preferably, it is 10 ⁵ pieces / mm ² or less.

In the manufacturing method of the copper alloy material of the embodiment of the present invention, when paying attention to the process related to the heat treatment, (A) the copper alloy raw material is melted and cast in the order applied to the copper alloy material to obtain a copper alloy ingot. Process, (
B) Heat treatment step before hot rolling (step of heating to hot-roll the copper alloy ingot), (C)
Hot rolling and cooling process after the completion, (D) Recrystallization heat treatment process (also called solution heat treatment process), (E) Aging heat treatment process, (F) Necessary for releasing processing strain of copper alloy material There is a low-temperature annealing process, etc. performed in response, and generally between (C) process and (D) process, (D
) Process and (E) process, and between (E) process and (F) process, cold rolling is performed and it becomes a copper alloy material of predetermined thickness. Here, it was found that the step that greatly affects the number of precipitates having a diameter of 200 nm or more is the step (B), and the step (B) was optimized.

In the method for producing a copper alloy material according to the embodiment of the present invention, the conditions of the step (B) are optimized, and the heat treatment step before the step (D) is performed only once in the step (B). This is important from the viewpoint of minimizing the number of heat treatment steps and greatly reducing the energy when producing the copper alloy material. The preferable conditions of the said (B) process are 30 minutes or more (preferably within 10 hours) at the temperature of 980 degreeC or more and less than 1050 degreeC. Moreover, the preferable conditions of the said (C) process are the temperature at the time of completion | finish of hot rolling being 800 degreeC or more, and immediately after that, until it becomes temperature 250 degrees C or less 30
It is to be cooled at a cooling rate of ° C / second or more. These conditions are such that the number of precipitates having a diameter of 200 nm or more (preferably 10 μm or less) is 10 ⁶ / mm in the copper alloy material of the present embodiment.
This is a preferable condition to make it ² or less.

When the temperature of this heat treatment step is lower than 980 ° C., the crystallized product formed at the time of casting remains without being dissolved, and this state may be maintained until the final step. The amount may be reduced, which may cause a final deterioration in strength characteristics (such as tensile strength). Moreover, when the temperature of the heat treatment step is 1050 ° C. or higher, the alloy may be embrittled and may break when the heated ingot is rolled.

In addition, when the temperature at the end of hot rolling is lower than 800 ° C, coarse precipitates may grow during the rolling, and when cooling after the hot rolling is finished, the cooling is performed in a state where the temperature is higher than 250 ° C. If the speed is lower than 30 ° C./second, unnecessary precipitation may occur during cooling. For this reason, it is preferable that the cooling rate is 30 ° C./second or more until the temperature is 250 ° C. or lower, and the cooling is performed without any change in the structure.
The temperature at the end of hot rolling is preferably 850 ° C. or higher, more preferably 900 ° C. or higher. The cooling rate until the temperature reaches 250 ° C. or lower is preferably 50 ° C./second or more, and more preferably 80 ° C./second or more.

Although the copper alloy material of this invention is not specifically limited, For example, it can use suitably for electronic electrical equipment components, such as a connector, a terminal, a relay, a switch, and also a lead frame.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

The copper alloy material shown in Table 1 was produced as follows. The amount of Co and Si described in Table 1 and other additive elements and the balance of Cu and an alloy composed of inevitable impurities are melted in a high-frequency melting furnace,
The molten metal was cast into a mold having a size cast to a width of 160 mm, a thickness of 30 mm, and a height of 180 mm.

Next, this ingot was hot-rolled immediately after being subjected to a heat treatment that was heated at a temperature listed in Table 1 for 1 hour, was terminated at a temperature listed in Table 1, and was immediately cooled with water. The cooling rate during water cooling was about 50 ° C./second on average until the temperature reached about 200 ° C. The reheat temperature was measured by attaching a thermocouple to the substance, and the temperature after hot rolling was measured with a radiation thermometer.

After that, it processed along the manufacturing process of the general precipitation type copper alloy. After the water cooling after the hot rolling was finished, both sides were each 1 mm chamfered to remove the oxide film. Next, cold rolling was performed, and a solution heat treatment was performed at 800 to 1025 ° C. for 30 seconds to 2 hours in an inert gas atmosphere, followed by water cooling. After water cooling, the material was subjected to aging heat treatment at 300 to 600 ° C. for 1 to 10 hours. After this aging heat treatment, 0-30% cold rolling was added, and further low temperature heat treatment was performed at 200-450 ° C. for 0.5-5 hours.

The following characteristic investigation was performed by using each plate material thus obtained as a test material. The results are shown in Table 1. In addition, the measuring method of each evaluation item is as follows.

A. Charpy test The Charpy test was conducted in accordance with Japanese Industrial Standard (JIS Z 2242).
Each sample was subjected to the Charpy test under the two temperature conditions of “reheating temperature shown in Table 1” and “temperature 980 ° C.”. After each sample was heated in an Ar pot in an Ar atmosphere, when the sample surface temperature reached each temperature, it was immediately removed from the Ele pot and tested within 5 seconds. Absorbed energy was obtained for each temperature test in accordance with the above JIS standard, and was treated as a parameter related to ingot cracking by quantifying with the formula (value at reheating temperature / value at 980 ° C. in Table 1). . When this threshold value was set to 0.4, it was determined that ingot cracking was caused in order to show embrittlement at a lower value.
B. Ingot cracking Judgment was made from the ingot state after hot rolling (30 mm → 14 mm). Ingots that were judged to be unable to maintain the shape of the product during the flow of subsequent processes, such as those in which cracks were detected by visual inspection of the ingot surface, were marked as “ingot cracks”.
C. Tensile strength (TS)
JIS Z2201-13B test piece cut out from the rolling parallel direction of the test piece
Three samples were measured according to 2241, and the average value is shown in Table 1.
D. Conductivity (EC)
Using a four-terminal method, conductivity (EC) was measured for two of each test piece in a thermostat controlled at 20 ° C. (± 1 ° C.), and the average value (% IACS) is shown in Table 1. Indicated. At this time, the distance between terminals was set to 100 mm.
E. Diameter and density of precipitates A cross section in the rolling parallel direction was photographed with a scanning electron microscope, and the diameter was 200 n on the photograph.
The particle size and density of precipitates greater than or equal to m were measured. Here, the number of precipitates having a diameter of 200 nm or more is 10 ⁶ / mm ² or less is “small”, and the number of precipitates is more than 10 ⁶ / mm ^2.
"Large".

<Grouping of each sample>
Group having a Co content of about 0.8% by mass:
The ultimate target was a tensile strength of 520 MPa or more and a conductivity of 65% IACS or more. This is a group with a little emphasis on conductivity. Sample No. of Invention Example 1-4, sample No. of the comparative example of a composition. 103 (example with too much Cr content), sample No. 201-2
02 corresponds.
Group having a Co content of about 1.2% by mass:
The ultimate target was a tensile strength of 600 MPa or more and an electrical conductivity of 60% IACS or more. This is a group considering the balance between strength and conductivity. Sample No. of Invention Example 5-9, sample No. 203-204 corresponds.
Group having a Co content of about 1.4% by mass:
The ultimate target was a tensile strength of 620 MPa or more and a conductivity of 60% IACS or more. This is a group with a little emphasis on strength. Sample No. of Invention Example 10-11, sample No. 205-206 corresponds.
In addition, the sample whose Co content is not in the range of 0.7 to 2.5% by mass is referred to as Sample No. of Comparative Example of the composition. 101-102.

As shown in Table 1, Sample No. 1 to 11 all satisfy the target characteristics, and it was found that the characteristics of the copper alloy raw material were sufficiently drawn.
On the other hand, about each sample of the comparative example, it became what a crack generate | occur | produces in an ingot, or a thing with low intensity | strength and electrical conductivity.
Sample No. which is a comparative example of the composition. About 101, since the density | concentration of Co was too low, intensity | strength fell. Sample No. About 102, since the density | concentration of Co was too high, the electrical conductivity fell. Sample No. About 103, the intensity | strength fell because the density | concentration of elemental components (Cr) other than Co and Si was too high.
Sample No. which is a comparative example of the production method. 201 and no. About 204, the temperature at the time of heat processing before hot rolling was too high, and the embrittlement crack of the ingot occurred. Sample No. 202-203
And Sample No. For 205 to 206, the temperature at the end of hot rolling was low, precipitation occurred during hot rolling or subsequent cooling, and the number of precipitates having a diameter of 200 nm or more exceeded 10 ⁶ / mm ^2. Decreased.

Claims (4)

Cobalt (Co) is contained in an amount of 0.7 to 2.5% by mass, silicon (Si) is contained so that the ratio of Co and Si content Co / Si is in the range of 3 to 5, and the balance is Cu and After melting and casting the copper alloy raw material consisting of inevitable impurities to obtain a copper alloy ingot,
The heat treatment process before recrystallization heat treatment is performed only once before hot rolling,
The heat treatment step is performed at a temperature of 980 ° C. or more and less than 1050 ° C. for 30 minutes or more,
The temperature at the end of the hot rolling is 800 ° C. or higher, and cooling immediately after that is performed at a temperature of 250 ° C. or lower.
A method for producing a copper alloy material, characterized in that a cooling rate of 30 ° C./second or more is employed until the temperature falls below. The copper alloy raw material further includes Cr, Fe, Ni, Al, Nb, Ti, V, Mn and Zr.
0.01 to 0.5 mas in total of one or more additive elements selected from the group consisting of
s% including manufacturing method of the copper alloy material according to claim 1. The copper alloy raw material further contains an additive element selected from the group consisting of Sn, Mg and Zn.
0～1Mass% including species or two or more in total, the copper alloy material according to claim 1 or 2
Production method. It is the copper alloy material manufactured by the method of any one of Claims 1-3,
  The number of precipitates having a diameter of 200 nm or more after the heat treatment step before the recrystallization heat treatment is 10 ⁶ Pieces
/ Mm ² A copper alloy material characterized by:

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