JPH11124644A - Nickel-free white copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an alloy excellent in strength, hardness, ductility, workability and corrosion resistance, furthermore causing no problems in allergies and high in whiteness by adding specified amounts of manganese, aluminum and/or tin to a copper-zinc alloy and forming it into an alloy of the α single phase at room temp. SOLUTION: The compsn. of an alloy is made the one shown by the general formula of Cuw Znx Mny (Al and/or Sn)z . Furthermore, as for (w), (x), (y) and (z) in the formula, by weight%, 70<=w<=85, 5<=x<=22, 7<y<=15 and 0<z<=4 are satisfied, and, inevitable elements may be contained in the alloy. This alloy shows a structure of the α single phase in room temp. state, and, based on the L*, a* and b* color specification system chromaticity diagram prescribed by JIS-Z 8729, the color tone lies in the ranges of 0<a*<2 and 7<b*<16. Moreover, since this alloy does not contain Ni in the compsn., there is no fear of causing nickel allergies. It is suitable for personal ornaments.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to strength, hardness, ductility, workability, and the like suitable for clothing such as elements of slide fasteners, sliders, fasteners, metal buttons, and fasteners for clothing. The present invention relates to a nickel-free white copper alloy having excellent corrosion resistance and allergy-free and high whiteness.

[0002]

2. Description of the Related Art Conventional copper alloys for fasteners include, for example, copper-nickel-zinc alloys such as nickel-white, which have a white alloy hue, and copper-zinc alloys typified by copper and brass. Has been used. However, since nickel silver contains nickel as an alloy element, it has excellent corrosion resistance,
For example, when this is applied for a slide fastener, the fastener often comes into contact with the skin, and thus has a problem of nickel allergy. Further, copper-zinc alloys represented by copper and brass do not contain nickel, so that there is no problem of nickel allergy, but the hue becomes yellow, and a white alloy cannot be obtained.

[0003]

Therefore, the present invention is excellent in workability, corrosion resistance and whiteness by adding ductility, and is excellent in workability, corrosion resistance and whiteness. An object of the present invention is to provide a white copper alloy having no problem.

[0004]

According to the present invention, there is provided a compound represented by the general formula: Cu
_w Zn _x Mn _y (Al and / or Sn) _z, however, w,
x, y, z are% by weight, 70 ≦ w ≦ 85, 5 ≦ x ≦ 2
It is a nickel-free white copper alloy characterized by being able to contain an unavoidable element when 2,7 <y ≦ 15,0 <z ≦ 4. The above alloy is a single α phase at room temperature, and the a * value and b * value indicating the color tone are 0 <a * <2, 7 <b * <16.

[0005] In the composition of the present invention, Zn has the effect of improving the mechanical properties of the alloy by solid solution strengthening and lowering the price of the alloy. If it is less than 5%, the price of the alloy is insufficiently reduced, and the amount of reinforcement is insufficient. Also, 22%
If it is larger, the season cracking resistance is deteriorated, and the crystal structure becomes an α + β phase, so that sufficient cold workability cannot be secured.

Mn has the effect of improving the mechanical properties of the alloy by solid solution strengthening and lowering the price of the alloy.
In addition, by adding in place of zinc, there is an effect of improving the season cracking resistance and an effect of suppressing the color tone of the copper alloy from becoming too yellow. Further, it has the effect of lowering the melting point, improves the castability, and has the function of suppressing the evaporation of zinc from the molten metal. If it is less than 7%, the color tone becomes yellow. Conversely, if it is more than 15%, the crystal structure becomes an α + β phase, and sufficient cold workability cannot be secured. Al and S
When only Al is selected from n, the upper limit of Mn is 10%.
Is preferred.

[0007] Al and / or Sn have the effect of improving the season cracking resistance by forming a stable oxide film on the alloy surface. In addition, the solid solution strengthening has the effect of improving the mechanical properties of the alloy and reducing the price of the alloy. The lower limit may be an amount exceeding 0%. However, if the amount is too small, the alloy is insufficient in the time cracking resistance and the reinforcing amount is insufficient. Therefore, the lower limit is more preferably 0.2%.
On the other hand, if it exceeds 4%, the crystal structure becomes an α + β phase, and sufficient cold workability cannot be secured. The alloy of the present invention is an α-phase single phase, and can secure sufficient cold workability. If the composition is out of the range of the present invention, the crystal structure tends to be in the α + β phase, and the workability is reduced.

Further, the alloy of the present invention has a value of 0 <based on the chromaticity diagram of L *, a *, b * color system specified in JIS Z8729.
a * <2, 7 <b * <16. The chromaticity referred to in the present specification is a lightness index L * (lightness: Elster) and a chromaticity index a * (greenish to reddish: expressed in the object color display method defined in JIS Z8729).
Aster) and b * (blue-yellow: bee star). In particular, in order to be white which is a feature of the present invention, it is better that the color is close to an achromatic color, and is defined by the chromaticity indices a * and b * as described above.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Pure Cu (99.9%), Pure Zn
(99.9-99.99%), pure Mn (99.9%),
A predetermined composition was weighed (200 cm ³ ) using pure Al (99.99%) and pure Sn (99.95%). These were melted at a high frequency in an Ar atmosphere (10 cmHg), held for 4 minutes, and then poured into a copper mold (φ40 × 28). The obtained ingot (200 m ³ ) was cut into a length of about 70 mm to obtain an extruded billet. Extrusion was performed at a billet temperature of 800 ° C and a container temperature of 600 ° C. The obtained extruded material (φ8 ×
(1300) was subjected to a heat treatment of 800 ° C. × 1 h + furnace cooling (hereinafter referred to as heat treatment). The extruded material (wire) subjected to this heat treatment was used as a base material for the test.

In the compression test, a column (φ5 × 7.5) was cut out from the heat-treated extruded material by lathe processing to obtain a compression test piece. Crosshead speed 0.0 at room temperature
016 mm / min (strain rate 0.4 × 10 ⁻⁷ / s)
The test was performed so that the compression direction coincided with the longitudinal direction of the test piece.
A lubricant was applied to the compression surface of the test piece to eliminate friction with the compression jig.

A method of evaluating the resistance to seasonal cracking is to cut a column (φ7 × 12 mm) from the extruded material by lathing, cold-roll it, and process it into a Y bar (a linear material that is the basis of a slide fastener element). A plate having a thickness of 1.2 mm was introduced by introducing the same strain as the required processing strain (80%), and this was machined into a tensile test piece as shown in FIG.

The elongation was measured using the tensile test piece.
On the other hand, using a 12.5% ammonia solution, after performing ammonia exposure according to the Japan Copper and Brass Association Technical Standard JBMA-T301, a tensile test was performed to measure elongation. From these elongation values, the seasonal cracking resistance elongation reduction rate was calculated.

Table 1 shows alloy types and test results of the examples and comparative examples.

[0014]

[Table 1]

[0015]

Industrial Applicability The present invention provides Ni having excellent strength and hardness equivalent to that of nickel silver, further having ductility, excellent workability and corrosion resistance.
It is a white copper alloy that does not contain, and is Ni-free even when it comes into contact with the skin when used for fastener elements, sliders, fasteners, etc. Therefore, there is no worry of allergies, and the beautiful white color is maintained, so the decorative value is high.

[Brief description of the drawings]

FIG. 1 is a view showing a shape of a test piece used for a tensile test of the present invention.

Claims (3)

[Claims] 1. A general _{formula: Cu w Zn x Mn y (} Al and /
Or Sn) _z where w, x, y, and z are% by weight, and 70 ≦ w ≦ 85,
A nickel-free white copper alloy, wherein 5 ≦ x ≦ 22, 7 <y ≦ 15, and 0 <z ≦ 4, which may contain an unavoidable element. 2. The nickel-free white copper alloy according to claim 1, which is an α-phase single phase at room temperature. 3. The a * value and b * value of a color tone of an alloy indicating a color tone defined by JIS Z8729 are 0 <a * <2.7.
3. The nickel-free white copper alloy according to claim 1, wherein <b * <16.