JP2012246530A - Copper alloy wrought material - Google Patents

Abstract

The present invention provides a new wrought copper alloy material having characteristics equal to or better than beryllium copper and having sufficient machinability and high strength and conductivity.
A copper alloy containing 1.5 to 7.0 mass% of Ni, 0.3 to 2.3 mass% of Si, and 0.3 to 3.0 mass% of Pb, the balance being Cu and inevitable impurities. A wrought copper alloy wrought material having a tensile strength of 500 MPa or more and a conductivity of 25% IACS or more.
[Selection figure] None

Description

  The present invention relates to a copper alloy wrought material suitable for metal parts used in electronic equipment, precision machines, automobiles, etc., particularly copper alloy parts produced by cutting.

  Cutting methods such as turning and drilling are methods for producing metal parts. Cutting is an effective processing method particularly for manufacturing parts having complicated shapes and parts requiring high dimensional accuracy. When cutting, machinability is often a problem. The machinability includes items such as cutting waste treatment, tool life, cutting resistance, and cutting surface roughness, and the material has been improved to improve them.

  Copper alloys are used in many metal parts for reasons such as high strength, excellent electrical conductivity and thermal conductivity, excellent corrosion resistance, and excellent color tone. There are also many cutting processes, such as taps, valves, gears, ornaments, etc., brass (Cu-Zn), bronze (Cu-Sn), aluminum bronze (Cu-Al). ), An alloy in which lead is added to the white (Cu—Zn—Ni series) to improve machinability. These are all applications that do not require high strength or high conductivity.

  For applications that require high strength or high conductivity, such as pin materials for coaxial connectors, etc., free-cutting beryllium copper (see Patent Document 1), free-cutting phosphor bronze in which lead is added to beryllium copper or phosphor bronze (See Patent Document 2). These are cut by a precision machine tool such as an NC lathe and used for highly reliable parts such as electronic devices.

Since beryllium copper is expensive, there is a demand for an alternative material for electronic devices. On the other hand, free-cutting phosphor bronze is less expensive but less in strength and conductivity than beryllium copper.
The technique described in Patent Document 1 adds lead as an additive element for improving the machinability as described above, and improves the machinability by using a composite addition of subcomponents. The method has not been studied. In the technique described in Patent Document 2, as described above, the machinability is improved by using a combined addition of lead and subcomponents as an additive element for improving the machinability. Improvement has not been studied and is not suitable as an alternative to beryllium copper.
Moreover, although the technique of patent document 3 is examining the improvement of bending workability by adding the several component containing Sn and Pb as a subcomponent to Cu-Ni-Si type copper alloy, As an effect, the addition of 0.05 mass% of Ag and 0.01 mass% of Pb was studied, and it was added for the purpose of improving strength and spring characteristics, and machinability was not studied at all. . In addition, regarding the total specified amount of the subcomponents, sufficient studies have not been made with the component amounts within the specified range, and there is no description about the relationship between the subcomponent components, amount and action.

Similarly, in the technique of Patent Document 4, a plurality of components containing Zn, P, and Pb as subcomponents are added to a Cu—Ni—Si based copper alloy, and studies are being made to improve strength and conductivity. However, 0.2 mass% of Pb is added, and the effect of Pb is to improve corrosion resistance, heat resistance, and punchability, and machinability is not described. In addition, as in Patent Document 3, a sufficient amount of the component amounts within the specified range has not been sufficiently studied for the total specified amount of the subcomponents, and the relationship between the components of the subcomponents, the amount and the action is described. There is no.
The technique described in Patent Document 5 does not include Pb in a Cu—Ni—Si based alloy, and Co, Zr, Ti, Fe, Mn, Cr, Sn, Al, Mg, V, P, and Zn are added. -A compound composed of Si and an additive element is formed to improve machinability. However, cutting for precision machining is inferior in the cutting property of cutting waste.
As a copper alloy wrought material that does not use Pb, the present inventors have proposed a material in which a sulfide having an average diameter of 0.1 to 10 μm is dispersed to improve cutting workability (Patent Document 6). The technique described in Patent Document 6 is limited to a copper alloy wrought material in which sulfide is dispersed.

Japanese Patent Laid-Open No. 51-62129 Japanese Patent Laid-Open No. 50-066423 Japanese Patent Laid-Open No. 3-188247 JP-A-10-152737 JP 2010-106363 A Japanese Patent No. 4630387

  Accordingly, the present invention provides a new copper alloy wrought material having characteristics equal to or better than beryllium copper, high machinability as well as sufficient machinability, and a copper alloy part manufactured by cutting the copper alloy component. The purpose is to provide.

  As a result of intensive studies, the present inventors have developed a copper alloy material capable of precise cutting in an aging precipitation type copper alloy obtained by adding Pb to a Cu—Ni—Si based copper alloy. It has been found that a copper alloy wrought material having excellent conductivity can be obtained. The present invention has been made based on this finding.

That is, the present invention provides the following solutions.
(1) A copper alloy exhibit containing 1.5 to 7.0 mass% of Ni, 0.3 to 2.3 mass% of Si, 0.3 to 3.0 mass% of Pb, and the balance of Cu and inevitable impurities A copper alloy wrought material characterized by being a wrought material, having a tensile strength of 500 MPa or more, and an electrical conductivity of 25% IACS or more.
(2) Containing 1.5 to 7.0 mass% of Ni, 0.3 to 2.3 mass% of Si, and 0.3 to 3.0 mass% of Pb, and Sn, Ag, Mn, Fe, Cr, A copper alloy wrought material containing 0.05 to 2.0 mass% of the total amount of at least one selected from the group consisting of Co, Zn, and Mg, with the balance being Cu and inevitable impurities, and tensile strength A copper alloy wrought material having a thickness of 500 MPa or more and an electrical conductivity of 25% IACS or more.
(3) A copper alloy part formed by cutting the copper alloy wrought material according to (1) or (2).
(4) The copper alloy part according to (3), which is used for an electronic device part, a structural part, or an element part.

  The copper alloy wrought material of the present invention is suitable for precision cutting with excellent strength and conductivity. For example, in order to prevent a decrease in the insertion / removal force required for the connector pin material, a decrease in the insertion / extraction force can be suppressed by having a tensile strength as high as that of beryllium copper. In the present invention, the tensile strength is 500 MPa or more, and it is equivalent to beryllium copper. In addition, parts such as electronic devices that do not require tensile strength or conductivity are more excellent in conductivity than beryllium copper because they have a conductivity of 25% IACS or more. Moreover, the copper alloy wrought material of the present invention is suitable as a material for parts such as electronic equipment manufactured by cutting. The copper alloy part of the present invention can be manufactured with high precision by cutting, and has sufficient characteristics required for parts such as electronic equipment.

It is a front view which shows typically the shape of the connector pin produced in order to test the insertion / extraction property in Example-2.

A preferred embodiment of the copper alloy wrought material of the present invention will be described in detail.
<Ni, Si>
Nickel (Ni) and silicon (Si) in a preferred embodiment of the copper alloy wrought material according to the present embodiment are controlled by controlling the content ratio of Ni and Si to form a Ni-Si compound (Ni ₂ Si) is formed to enhance precipitation, and is added to improve the strength and conductivity of the copper alloy wrought material. This Ni—Si compound (Ni ₂ Si: precipitate for strengthening precipitation) does not contribute much to the improvement of machinability.

  In a preferred embodiment of the copper alloy wrought material of the present embodiment, the addition of Pb disperses the Pb particles in the matrix and contributes to improved machinability. The Pb particles act as a starting point for cutting waste when the cutting is performed, so that the cutting waste is easily finely divided and machinability is improved.

  The copper alloy wrought material in the present embodiment is hot or cold worked in a state where nickel (Ni) and silicon (Si) are in solid solution, or in a state where Ni-Si precipitates are formed. In any state, the stretch workability is generally poor, and cracking or breakage is likely to occur during the processing. If Pb particles are present in the copper alloy, the stretchability is further deteriorated and the processing becomes difficult. In order to achieve both the stretchability and the machinability, the added amount of Pb has an effect. From this, in this embodiment, the addition amount of Ni and Si is prescribed | regulated, and the addition amount of Pb is prescribed | regulated. As a result, in the Cu—Ni—Si based copper alloy wrought material, it becomes possible to simultaneously improve the stretch workability and the precision cutting workability which are difficult to achieve at the same time. Good stretchability means that a copper alloy is melted and the resulting ingot (billet or cake) can be processed without cracking or breakage when hot-working or cold-working. Good precision machinability means that, for example, when a round bar is stepped using a general-purpose lathe, the chips generated in the cutting process are finely divided to 2 mm or less, and the workpiece is healthy. That means. The “stretched material” in the present invention is an alloy material obtained by hot-working an ingot obtained with a prescribed alloy component and immediately water-cooling the hot-stretched material, and further by cold working. Say. (Thus, the material obtained by casting is not included in the wrought material.)

  The content of Ni is 1.5 to 7.0 mass% (mass%), and preferably 1.7 to 6.5 mass%. If the amount of Ni is too small, the amount of precipitation hardening due to Ni-Si precipitates is small and the strength is insufficient. If the amount of Ni is too large, not only does the amount of Ni-Si precipitates contributing to strength improvement increase, but also a large amount of Ni-Si precipitates are formed during melt casting, resulting in hot workability and cold work. This is not preferable because it deteriorates the property (ie, extensibility).

When the Si content is calculated by mass% in the formation of Ni-Si precipitates (Ni ₂ Si), an amount of about 1/5 to 1/3 of the Ni content is required. From this, in this embodiment, content of Si is 0.3-2.3 mass%, and it is preferable that it is 0.34-2.2 mass%.

  In the copper alloy wrought material of this embodiment, it is necessary to disperse Pb particles in the matrix. The content of Pb is 0.3 to 3.0 mass%, preferably 0.5 to 3.0 mass%. If the amount is too small, the cutting property of cutting chips is inferior, and sufficient cutting material cutting properties cannot be obtained. When there is too much content of Pb, hot workability and cold workability will deteriorate.

  Further, the copper alloy wrought material of this embodiment includes tin (Sn), silver (Ag), manganese (Mn), iron (Fe), chromium (Cr), cobalt (Co), zinc (Zn), magnesium You may contain 1 type, or 2 or more types of (Mg). These elements improve the strength of the Cu—Ni—Si alloy and improve the bendability and stress relaxation resistance by forming a solid solution or a precipitate. When contained, 0.05 to 2.0 mass%, preferably 0.2 to 1 or more selected from Sn, Ag, Mn, Fe, Cr, Co, Zn, and Mg in total amount It is made to contain 2.0mass%. When the content is less than 0.05 mass%, the effects of strength improvement, bendability, and stress relaxation resistance are the same as when these elements are not contained. Moreover, when there is more content than 2.0 mass%, since the effect of an intensity | strength improvement is saturated, and electrical conductivity falls, it is not a policy.

<Mechanical properties and manufacturing conditions>
Next, the mechanical properties of the copper alloy wrought material in a preferred embodiment of the embodiment will be described.
The copper alloy wrought material in the present embodiment is a copper alloy for substitution of free-cutting phosphor bronze and free-cutting beryllium copper, and precision cutting of a Cu-Ni-Si-based copper alloy material. Equivalent strength is required. Therefore, the strength and conductivity that do not cause a problem in practical use are required to be a tensile strength of 500 MPa or more and an electrical conductivity of 25% IACS or more by IACS (International Annealed Copper Standard). The copper alloy wrought material in the present embodiment is an aging precipitation type, and the strength and conductivity are improved by forming Ni ₂ Si as described above. For this reason, Ni is 1.5 to 7.0 mass. %, Si must be contained in an amount of 0.3 to 2.3 mass%.

  In this embodiment, the copper alloy wrought material manufacturing method is an aging precipitation type copper alloy material, and therefore the aging heat treatment step is essential after the copper alloy raw material melting and casting step. However, the solution treatment process, the hot working process, the cold working process, and the annealing process are performed as necessary to obtain a copper alloy wrought material. For example, regarding the hot working process, the copper alloy wrought material of this embodiment can be manufactured by any of manufacturing methods such as hot extrusion of billets, hot forging of ingots, or continuous casting. Moreover, there is no restriction | limiting in particular in the shape of a product, It is preferable to set it as the shape which is easy to obtain the copper alloy component which is a last form by the cutting process which is a post process. That is, it can be manufactured as a copper alloy wrought material having a predetermined shape such as a wire, a bar, a strip, a plate, or a tube depending on the use of the copper alloy component. For example, when the copper alloy part in the final form is a screw or a rivet, the shape of the copper alloy wrought material is preferably a round bar shape.

  Copper alloy parts include male connector and male pins for coaxial connectors that currently use lead-containing phosphor bronze and beryllium copper, as well as probe barrels and plunger materials used in IC sockets and battery terminal connectors, and audio cable components. Strength, electrical conduction, such as electronic parts such as connector terminals, structural parts such as antenna hinges, fasteners, bearings, guide rails, resistance welders, watches, and parts such as gears, bearings, and eject pins of molds Parts that require heat resistance, heat conductivity, and wear resistance, and are manufactured in a complicated shape mainly by cutting. The “copper alloy part” in the present embodiment may include a copper alloy part manufactured by cutting.

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

Example-1
A copper alloy having a composition (unit: mass%, the balance being copper and inevitable impurities) shown in Table 1 was melted in a high-frequency melting furnace to produce a billet having a diameter of 200 mm. The billet was hot extruded at a temperature of 950 ° C. and immediately quenched in water to obtain a round bar with a diameter of 25 mm. Next, the round bar was cold-rolled to produce a round bar having a diameter of 20 mm, and further subjected to aging heat treatment at a temperature of 450 ° C. for 2 hours.

[1] Tensile strength, [2] Electrical conductivity, and [3] Machinability of each of the copper alloy wrought materials (round bars) obtained in this manner were examined by the following methods. The measurement method for each evaluation item is as follows.
[1] Tensile strength Three were measured according to JIS Z 2241 and the average value (MPa) was shown.
[2] Conductivity Using a four-terminal method, two samples were measured for each sample in a thermostatic chamber controlled at 20 ° C. (± 1 ° C.), and the average value (% IACS) was shown.
[3] Machinability Using a general-purpose lathe, stepped cutting of the outer diameter of a round bar to produce a rivet having a diameter of 18 mm for a large diameter portion and a diameter of 16 mm for a small diameter portion. Observed. It is best if the cutting waste is divided into lengths of 2 mm or less, good if the cutting waste is divided into lengths of 4 mm or less, cutting waste is divided, but the length is 4 mm or more and 10 mm or less. Those that are spirally connected are considered defective. It is good that there is no practical problem for precision machining, and the best is desirable when more cutting waste separation is required. The cutting conditions were the same and the cutting oil was not used.

  Table 1 shows the results. In inventive examples 1 to 20, the components are within the scope of the present invention, and all satisfy the tensile strength of 500 MPa or more and the electrical conductivity of 25% IACS or more. Further, the Pb amount was also within a specified range, there were no cracks during material processing, and machinability was also good.

In Comparative Example 1, the Ni concentration and the Si concentration are low, and the tensile strength is inferior. In comparison 2, the Ni concentration and the Si concentration are high, and the conductivity is inferior. In Comparative Example 7, the total amount of Sn, Ag, Mn, Fe, Zn, and Mg exceeded 2.0 mass%, and the conductivity was inferior. In Comparative Example 8, the Ni concentration and the Si concentration were high, and cracks occurred in the cold rolling process. In Comparative Example 9, the amount of Pb added was larger than specified, and cracking occurred during cold working. In Comparative Example 10, the amount of Pb was larger than that in Comparative Example 9, and cracking occurred during hot working. In Comparative Example 11, the amount of Pb was lower than specified, and the cutting property of the cutting waste was inferior. In Comparative Example 12, since the amount of Pb was lower than that in Comparative Example 11, the cutting waste was not divided.
In Comparative Examples 13 and 14, materials were produced by the production method of the present example based on the composition examples of Patent Examples 3 and 4.
In Comparative Example 13, since the addition amount of Pb was lower than the range of the present invention, the cutting waste was not divided. In Comparative Example 14, since the amount of Pb added was lower than the range of the present invention, the cutting waste was divided, but the cutting property was inferior.
Conventional Example 1 is free-cutting phosphor bronze, and the tensile strength and conductivity of the present invention are not satisfied. Conventional Example 2 is free-cutting beryllium copper and does not satisfy the conductivity of the present invention.

Example-2
Using the alloy components of Invention Example 7 and Invention Example 13 in Table 1 and a round bar with a diameter of 20 mm obtained by the method of Example-1, a round bar with a diameter of 2 mm was produced. About these round bars, the insertability which is required as a characteristic of pin material was evaluated about the connector pin of the shape typically shown by a front view in FIG. 1 using NC lathe. The evaluation method is to insert a φ0.92 mm pin gauge into the processed pin and measure the insertion / extraction force (initial value T0), and after repeating the same pin repeatedly 500 times, measure the insertion / extraction force again ( T1), the ratio T1 / T0 with respect to the initial value was obtained. The larger T1 / T0 is, the smaller the drop in insertion / extraction force is, and it can be said that the performance as a connector pin is good. Evaluation was performed on five pins, and an average value was obtained. For comparison, the materials of Conventional Examples 1 and 2 in Table 1 were also evaluated. The results are shown in Table 2.
From Table 2, it can be seen that the present invention example is an excellent connector pin, showing the same insertability as the free-cutting beryllium copper of Conventional Example 2. The insertability of the free-cutting phosphor bronze of Conventional Example 1 was inferior to that of the present invention example, and there was concern about poor contact during long-term use.

Claims (4)

  A copper alloy wrought material containing 1.5 to 7.0 mass% of Ni, 0.3 to 2.3 mass% of Si, 0.3 to 3.0 mass% of Pb, and the balance of Cu and inevitable impurities. A copper alloy wrought material having a tensile strength of 500 MPa or more and an electrical conductivity of 25% IACS or more.   Ni 1.5-7.0 mass%, Si 0.3-2.3 mass%, Pb 0.3-3.0 mass%, Sn, Ag, Mn, Fe, Cr, Co, Zn And at least one selected from the group consisting of Mg in a total amount of 0.05 to 2.0 mass%, the balance being a copper alloy wrought material consisting of Cu and inevitable impurities, and a tensile strength of 500 MPa As described above, a copper alloy wrought material having a conductivity of 25% IACS or more.   A copper alloy part formed by cutting the copper alloy according to claim 1.   The copper alloy part according to claim 3, which is used for an electronic device part, a structural part, or an element part.

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