COPPER ALLOY MATERIAL

Abstract

A copper alloy material having a composition contains, Mg in a range of 0.15 mass % or more and 0.50 mass % or less, Cr in a range of 0.20 mass % or more and 0.90 mass % or less, and a balance consisting of Cu and inevitable impurities. Tensile strength is 600 MPa or more, and elongation is 3% or more. Electric conductivity is preferably 60% TACS or more.

Claims

1. A copper alloy material having a composition comprising: Mg in a range of 0.15 mass % or more and 0.50 mass % or less; Cr in a range of 0.20 mass % or more and 0.90 mass % or less; and a balance consisting of Cu and inevitable impurities, wherein tensile strength is 600 MPa or more, and elongation is 3% or more.

2. The copper alloy material according to claim 1, wherein electric conductivity is 60% IACS or more.

3. The copper alloy material according to claim 1, wherein the copper alloy material is provided as a wire material, and a cross-sectional area perpendicular to a longitudinal direction is in a range of 0.0003 mm.sup.2 or more and 0.2 mm.sup.2 or less.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0034] FIG. 1 is a flowchart showing a method of producing a copper alloy material according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

[0035] Hereinafter, a copper alloy material according to an embodiment of the present invention will be described.

[0036] A copper alloy material according to this embodiment is used as, for example, a wire of an insulated wire constituting a wire harness which is used for wiring of a vehicle or the like.

[0037] The copper alloy material according to this embodiment has a shape corresponding to a working method during component molding, and constitutes, for example, a plate strip material, a wire rod material, or a tubular material. In this embodiment, the copper alloy material is provided as a wire material.

[0038] A composition of the copper alloy material according to this embodiment contains Mg in a range of 0.15 mass % or more and 0.50 mass % or less, Cr in a range of 0.20 mass % or more and 0.90 mass % or less, and the balance consisting of Cu and inevitable impurities.

[0039] In the copper alloy material according to this embodiment, the tensile strength is 600 MPa or more, and the elongation is 3% or more.

[0040] The copper alloy material according to this embodiment preferably has electric conductivity of 60% IACS or more.

[0041] In the copper alloy material according to this embodiment, a cross-sectional area perpendicular to a longitudinal direction is preferably in a range of 0.0003 mm.sup.2 or more and 0.2 mm.sup.2 or less.

[0042] The reasons why the component composition, the various characteristics, and the cross-sectional area of the copper alloy material according to this embodiment are regulated as described above will be described below.

(Mg: 0.15 Mass % or More and 0.50 Mass % or Less)

[0043] Mg is an element which acts to sufficiently improve strength by being solid-dissolved in a parent phase of a copper alloy.

[0044] In a case where the Mg content is less than 0.15 mass %, the action and effect may not be sufficiently exhibited. In contrast, in a case where the Mg content is more than 0.50 mass %, the electric conductivity may be significantly reduced, the viscosity of the molten copper alloy may be increased, and the castability may be reduced. In addition, a coarse Mg compound may be generated, and defects such as cracks may occur during working.

[0045] From the above, in this embodiment, the Mg content is set in a range of 0.15 mass % or more and 0.50 mass % or less.

[0046] In order to further improve the strength, the lower limit of the Mg content is preferably 0.16 mass % or more, and more preferably 0.17 mass % or more. In order to securely suppress a reduction in the electric conductivity, castability, and workability, the upper limit of the Mg content is preferably 0.48 mass % or less, and more preferably 0.46 mass % or less.

(Cr: 0.20 Mass % or More and 0.90 Mass % or Less)

[0047] Cr is an element which has an effect on improvement of strength and electric conductivity as well as elongation by precipitating fine Cr-based precipitates (for example, Cu—Cr) in crystal grains of the parent phase by an aging treatment.

[0048] In a case where the Cr content is less than 0.20 mass %, the precipitation amount is not sufficient in the aging treatment, and the improvement of the strength, electric conductivity, and elongation may not be sufficiently achieved. In addition, in a case where the Cr content is more than 0.90 mass %, relatively coarse Cr crystallized products may be generated, which may cause defects.

[0049] From the above, in this embodiment, the Cr content is set in a range of 0.20 mass % or more and 0.90 mass % or less.

[0050] In order to securely exhibit the above-described action and effect, the lower limit of the Cr content is preferably 0.22 mass % or more, and more preferably 0.24 mass % or more. In order to further suppress the generation of relatively coarse Cr crystallized products and further suppress the occurrence of defects, the upper limit of the Cr content is preferably 0.85 mass % or less, and more preferably 0.80 mass % or less.

(Other Inevitable Impurities)

[0051] Examples of inevitable impurities other than Mg and Cr described above include Al, Fe, Ni, Zn, Mn, Co, Ti, B, Ag, Ca, Si, Te, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Re, Ru, Os, Se, Rh, Ir, Pd, Pt, Au, Cd, Ga, In, Li, Ge, As, Sb, Tl, Pb, Be, N, H, Hg, Tc, Na, K, Rb, Cs, Po, Bi, lanthanoid, O, S, C, and P. Since the inevitable impurities may reduce conductive property (heat conductive property), the total amount thereof is preferably 0.05 mass % or less.

(Tensile Strength: 600 MPa or More)

[0052] In the copper alloy material according to this embodiment, in a case where the tensile strength is less than 600 MPa, the strength is not sufficient, and breakage may occur during handling. In particular, the strength is likely to be insufficient in a case where the copper alloy material is used after a reduction in the cross-sectional area.

[0053] Accordingly, in the copper alloy material according to this embodiment, the tensile strength is set to 600 MPa or more.

[0054] The tensile strength of the copper alloy material according to this embodiment is preferably 620 MPa or more, and more preferably 640 MPa or more. The upper limit of the tensile strength of the copper alloy material according to this embodiment is not particularly limited, but is practically 1,200 MPa or less.

(Elongation: 3% or More)

[0055] In the copper alloy material according to this embodiment, in a case where the elongation is less than 3%, the elongation is not sufficient, and spattering or entanglement may occur during handling. Accordingly, it is difficult to assemble a wire harness or the like.

[0056] Therefore, in the copper alloy material according to this embodiment, the elongation is set to 3% or more.

[0057] The elongation of the copper alloy material according to this embodiment is preferably 4% or more, and more preferably 5% or more. The upper limit of the elongation of the copper alloy material according to this embodiment is not particularly limited, but is practically 30% or less.

(Electric Conductivity: 60% IACS or More)

[0058] In the copper alloy material according to this embodiment, in a case where the electric conductivity is 60% IACS or more, the Cr-based precipitates are sufficiently dispersed. Accordingly, the copper alloy material is excellent in strength, elongation, and conductive property (heat conductive property).

[0059] From the above, in the copper alloy material according to this embodiment, the electric conductivity is preferably 60% IACS or more.

[0060] The electric conductivity of the copper alloy material according to this embodiment is more preferably 62% IACS or more, and even more preferably 64% IACS or more. The upper limit of the electric conductivity of the copper alloy material according to this embodiment is not particularly limited, but is practically 90% IACS or less.

(Cross-Sectional Area Perpendicular to Longitudinal Direction: 0.0003 mm.sup.2 or More and 0.2 mm.sup.2 or Less)

[0061] The copper alloy material according to this embodiment constitutes a wire material. In a case where a cross-sectional area of the wire material perpendicular to a longitudinal direction is 0.0003 mm.sup.2 or more, the strength of the copper alloy material is secured, and thus it is possible to sufficiently suppress the occurrence of disconnection during handling. In a case where the cross-sectional area perpendicular to the longitudinal direction is 0.2 mm.sup.2 or less, the cross-sectional area is sufficiently reduced, and various components made of the copper alloy member can be further reduced in size and weight.

[0062] From the above, in the copper alloy material according to this embodiment, the cross-sectional area perpendicular to the longitudinal direction is preferably in a range of 0.0003 mm.sup.2 or more and 0.2 mm.sup.2 or less.

[0063] The lower limit of the cross-sectional area perpendicular to the longitudinal direction of the copper alloy material according to this embodiment is more preferably 0.001 mm.sup.2 or more, and even more preferably 0.005 mm.sup.2 or more. The upper limit of the cross-sectional area perpendicular to the longitudinal direction is more preferably 0.16 mm.sup.2 or less, and even more preferably 0.13 mm.sup.2 or less.

[0064] Next, a method of producing the copper alloy material according to an embodiment of the present invention will be described with reference to the flowchart of FIG. 1.

(Melting and Casting Step S01)

[0065] First, a copper raw material formed of oxygen-free copper having a copper purity of 99.99 mass % or more is put into a carbon crucible and melted using a vacuum melting furnace to obtain molten copper. Next, Mg and Cr are added to the obtained molten metal so as to obtain a predetermined concentration, and thus the components are adjusted and a molten copper alloy is obtained.

[0066] Regarding raw materials of Mg and Cr, for example, a material having a purity of 99.9 mass % or more is preferably used as the raw material of Mg, and a material having a purity of 99.9 mass % or more is preferably used as the raw material of Cr. A Cu-Mg mother alloy or a Cu—Cr mother alloy may be used.

[0067] The molten copper alloy whose components have been adjusted is poured into a mold to obtain a copper alloy ingot.

(Hot Working Step S02)

[0068] Next, the copper alloy ingot is subjected to hot working. Preferable conditions for the hot working are as follows: temperature: 600° C. or higher and 1,050° C. or lower, working rate: 50% or more and 99.5% or less. After the hot working, the ingot is immediately cooled by water cooling.

[0069] The working method in the hot working step S02 is not particularly limited, but in a case where the final shape is a plate or a strip, rolling may be applied. In a case where the final shape is a line or a rod, extrusion or groove rolling may be applied. In a case where the final shape is a bulk shape, forging or pressing may be applied.

(First Cold Working Step S03)

[0070] Next, the hot worked material which has undergone the hot working step S02 is subjected to cold working. In the first cold working step S03, the working rate is preferably in a range of 50% or more and 99.5% or less.

[0071] The working method in the first cold working step S03 is not particularly limited, but in a case where the final shape is a plate or a strip, rolling may be applied. In a case where the final shape is a line or a rod, extrusion or groove rolling may be applied. In a case where the final shape is a bulk shape, forging or pressing may be applied.

(Aging Treatment Step S04)

[0072] Next, the cold worked material obtained in the first cold working step S03 is subjected to an aging treatment to precipitate fine precipitates such as Cr-based precipitates.

[0073] Preferable conditions for the aging treatment are as follows: holding temperature: 350° C. or higher and 550° C. or lower, holding time at holding temperature: 0.5 hours or longer and 6 hours or shorter.

[0074] The heat treatment method during the aging treatment is not particularly limited, but the treatment is preferably performed in an inert gas atmosphere. The cooling method after the heating is not particularly limited, but water cooling is preferably performed for rapid cooling.

(Second Cold Working Step S05)

[0075] Next, the aging-treated material which has undergone the aging treatment step S04 is subjected to cold working. In the second cold working step S05, the working rate is preferably in a range of 90% or more and 99.99% or less.

[0076] The working method in the second cold working step S05 is not particularly limited, but in a case where the final shape is a plate or a strip, rolling may be applied. In a case where the final shape is a line or a rod, extrusion or groove rolling may be applied. In a case where the final shape is a bulk shape, forging or pressing may be applied.

[0077] In this embodiment, due to the second cold working step S05, the cross-sectional area perpendicular to the longitudinal direction is in a range of 0.0003 mm.sup.2 or more and 0.2 mm.sup.2 or less.

(Tempering Treatment Step S06)

[0078] Next, the cold worked material obtained in the second cold working step S05 is subjected to a tempering treatment to improve its elongation.

[0079] Preferable conditions for the tempering treatment are as follows: holding temperature: 350° C. or higher and 550° C. or lower, holding time at holding temperature: 0.5 hours or longer and 6 hours or shorter.

[0080] The method for the tempering treatment is not particularly limited, but the treatment is preferably performed in an inert gas atmosphere. The cooling method after the heating is not particularly limited, but water cooling is preferably performed for rapid cooling.

[0081] By the above steps, the copper alloy material according to this embodiment is produced.

[0082] According to the copper alloy material according to this embodiment having the above-described configuration, Mg is contained in a range of 0.15 mass % or more and 0.50 mass % or less, and thus the strength can be sufficiently improved by solid solution hardening.

[0083] Furthermore, since Cr is contained in a range of 0.20 mass % or more and 0.90 mass % or less, the temperature range during the heat treatment for dispersing the Cr-based precipitates is wide, and thus control is relatively easily performed, and it is possible to improve the strength and the elongation.

[0084] In addition, the copper alloy material according to this embodiment has tensile strength of 600 MPa or more and elongation of 3% or more. Accordingly, even in a case where the copper alloy material has a small cross-sectional area, it is possible to suppress the occurrence of disconnection or the like during handling, and stable handling is possible.

[0085] In this embodiment, since the electric conductivity is 60% IACS or more, the Cr-based precipitates are sufficiently precipitated and dispersed, and it is possible to sufficiently improve the strength and the elongation. In addition, the copper alloy material is particularly suitable for use requiring conductive property (heat conductive property).

[0086] In this embodiment, the copper alloy material is provided as a wire material, and a cross-sectional area perpendicular to a longitudinal direction is in a range of 0.0003 mm.sup.2 or more and 0.2 mm.sup.2 or less. Accordingly, the copper alloy material is excellent in strength and elongation and has a sufficiently small cross-sectional area, and various components using the copper alloy material can be reduced in size and weight.

[0087] The embodiments of the present invention have been described as above, but the present invention is not limited thereto, and can be appropriately changed without departing from the technical ideas of the present invention.

[0088] For example, the method of producing the copper alloy material is not limited to this embodiment, and the copper alloy material may be produced by another producing method. For example, a continuous casting device may be used in the melting and casting step.

Examples

[0089] Hereinafter, results of confirmation experiments performed to confirm the effects of the present invention will be described.

[0090] A copper raw material formed of oxygen-free copper having a purity of 99.99 mass % or more was prepared, put into a carbon crucible, and melted in a vacuum melting furnace (degree of vacuum: 10.sup.−2 Pa or less) to obtain molten copper. Mg and Cr were added to the obtained molten copper to adjust a component composition shown in Table 1, and after holding for 5 minutes, the molten copper alloy was poured into a cast iron mold to obtain a copper alloy ingot. Regarding the cross-sectional dimensions of the copper alloy ingot, the ingot was about 60 mm in width and about 100 mm in thickness. As a raw material of Mg as an additional element, a material having a purity of 99.9 mass % or more was used, and as a raw material of Cr, a material having a purity of 99.99 mass % or more was used.

[0091] Next, the obtained copper alloy ingot was cut into a predetermined size, and then subjected to hot working (hot rolling) under conditions shown in Table 1 to obtain a hot rolled material.

[0092] The hot worked material was subjected to first cold working (drawing) under conditions shown in Table 1, and a first cold worked material was obtained.

[0093] The first cold worked material was heated and held in an atmospheric furnace under conditions shown in Table 1, and then water-cooled and subjected to an aging treatment.

[0094] The obtained aging-treated material was subjected to second cold working (drawing) so as to obtain a cross-sectional area shown in Table 1, and a second cold worked material was obtained.

[0095] The second cold worked material was subjected to a tempering treatment under conditions shown in Table 1, and various copper alloy materials were obtained.

[0096] The component composition, workability, tensile strength, elongation, and electric conductivity of each copper alloy material obtained were evaluated.

(Component Composition)

[0097] The component composition of the obtained copper alloy material was measured by ICP-MS analysis. As a result, a composition shown in Table 1 was confirmed.

(Workability)

[0098] Those whose production was discontinued due to defects occurring during the manufacturing process were evaluated as “C”, those whose production was possible even in a case where defects occurred were evaluated as “B”, and those in which no defects were found were evaluated as “A”. The evaluation results are shown in Table 1.

(Tensile Strength and Elongation)

[0099] After setting a gauge length to 250 mm, a tensile test was performed twice or more at a crosshead speed of 100 mm/min using AG-X 250 kN manufactured by Shimadzu Corporation, and the measured values were averaged. The evaluation results are shown in Table 1.

(Electric Conductivity)

[0100] Using SIGMA TEST D2.068 (probe diameter: φ6 mm) manufactured by FOERSTER JAPAN Limited, a central part of the cross section of a sample of 10×15 mm was measured three times, and the measured values were averaged. The evaluation results are shown in Table 1.

TABLE-US-00001 TABLE 1 Manufacturing Process Second Cold First Cold Working Hot Working Working Cross- Working Working Aging Treatment sectional Composition (mass %) Temperature Rate Rate Temperature Hour area Mg Cr Cu (° C.) (%) (%) (° C.) (h) (mm.sup.2) Invention 1 0.15 0.78 Balance 950 69 60 350 2 0.0005 Examples 2 0.50 0.38 Balance 910 71 80 450 4 0.01 3 0.26 0.20 Balance 750 56 90 550 3 0.005 4 0.43 0.90 Balance 880 88 85 400 1 0.1 5 0.34 0.36 Balance 610 99 65 365 0.5 0.2 Comparative 1 0.08 0.65 Balance 950 75 75 600 8 0.06 Examples 2 0.60 0.41 Balance 800 61 60 330 3 0.001 3 0.39 0.12 Balance 600 48 99 500 1 0.2 4 0.31 1.50 Balance 700 81 10 450 4 0.0003 Manufacturing Process Tempering Evaluation Treatment Tensile Electric Temperature Hour Strength Elongation Conductivity (° C.) (h) Workability (MPa) (%) (% IACS) Invention 1 350 2 A 800 3 64 Examples 2 450 4 A 700 3 65 3 550 3 A 640 4 68 4 400 1 A 650 4 70 5 365 0.5 A 620 3 67 Comparative 1 600 8 B 550 7 78 Examples 2 330 1 B 700 2 57 3 540 1 A 510 5 67 4 — — C — — —

[0101] In Comparative Example 1 in which the Mg content was 0.08 mass %, which was less than the range of the present invention, the tensile strength was as low as 550 MPa. In addition, defects occurred during the manufacturing process, and the workability was not sufficient.

[0102] In Comparative Example 2 in which the Mg content was 0.60 mass %, which was more than the range of the present invention, the electric conductivity was as low as 57% IACS. In addition, the elongation was as low as 2%. Moreover, defects occurred during the manufacturing process, and the workability was not sufficient.

[0103] In Comparative Example 3 in which the Cr content was 0.12 mass %, which was less than the range of the present invention, the tensile strength was as low as 510 MPa.

[0104] In Comparative Example 4 in which the Cr content was 1.50 mass %, which was more than the range of the present invention, disconnection occurred during the working in which the cross-sectional area was reduced to 0.0003 mm.sup.2 in the second cold working, and thus it was not possible to produce the copper alloy wire. Accordingly, the subsequent evaluation was stopped.

[0105] In contrast, in Invention Examples 1 to 5 containing, as a composition, Mg in a range of 0.15 mass % or more and 0.50 mass % or less, Cr in a range of 0.20 mass % or more and 0.90 mass % or less, and a balance consisting of Cu and inevitable impurities, in which tensile strength was 600 MPa or more, and an elongation was 3% or more, the workability was excellent, and the electric conductivity could also be secured.

[0106] From the above, it was confirmed that according to the invention examples, it is possible to provide a copper alloy material which is sufficiently excellent in strength and elongation and can be handled well even in a case where a cross-sectional area is reduced.

INDUSTRIAL APPLICABILITY

[0107] According to the present invention, it is possible to provide a copper alloy material which is sufficiently excellent in strength and elongation and can be handled well even in a case where a cross-sectional area is reduced.