Copper-nickel-zinc alloy and use thereof

Abstract

A copper-nickel-zinc having the following composition in weight percentages: 46.0 to 51.0% Cu, 8.0 to 11.0% Ni, 0.2 to 0.6% Mn, 0.05 to 0.5% Si, up to 0.8% of each of Fe and/or Co, the sum of the Fe content and double the Co content equaling at least 0.1 wt. %, residual Zn, and unavoidable impurities, wherein nickel-, iron-, and manganese-containing and/or nickel-, cobalt-, and manganese-containing mixed silicides are embedded into a microstructure consisting of - and -phases as spherical or ellipsoidal particles and uses of such a copper-nickel-zinc alloy.

Claims

1. A copper-nickel-zinc alloy having the following composition, in % by weight: Cu from 46.0 to 51.0%, Ni from 8.0 to 11.0%, Mn from 0.2 to 0.6%, Si from 0.05 to 0.5%, Fe and/or Co in each case up to 0.8%, where the sum of Fe content and twice the Co content is at least 0.1%, the balance being Zn and unavoidable impurities, wherein nickel-, iron- and manganese-containing and/or nickel-, cobalt- and manganese-containing mixed silicides are embedded as spherical or ellipsoidal particles in a microstructure consisting of and phases.

2. The copper-nickel-zinc alloy as claimed in claim 1 having the following composition, in % by weight: Cu from 47.5 to 49.5%, Ni from 8.0 to 10.0%, Mn from 0.2 to 0.6%, Si from 0.05 to 0.4%, Fe from 0.2 to 0.8%, optionally up to 0.8% of Co, the balance being Zn and unavoidable impurities, wherein nickel-, iron- and manganese-containing mixed silicides are embedded as spherical or ellipsoidal particles in a microstructure consisting of and phases.

3. The copper-nickel-zinc alloy as claimed in claim 1 having the following composition, in % by weight: Cu from 47.5 to 49.5%, Ni from 8.0 to 10.0%, Mn from 0.2 to 0.6%, Si from 0.05 to 0.4%, Co from 0.1 to 0.8%, optionally up to 0.8% of Fe, the balance being Zn and unavoidable impurities, wherein nickel-, cobalt- and manganese-containing mixed silicides are embedded as spherical or ellipsoidal particles in a microstructure consisting of and phases.

4. A consumer good having a polished surface finish that is free of visible defects, wherein said consumer good is made of the copper-nickel-zinc alloy of claim 1.

5. A key, lock, plug connector or point for a ballpoint pen, wherein said key, lock, plug connector or point for a ballpoint pen is made of the copper-nickel-zinc alloy of claim 1.

Description

(1) The invention will be illustrated with the aid of a working example.

(2) A copper-nickel-zinc alloy according to the invention and three comparative alloys were melted and cast to form billets. Wires and rods having an external diameter of 4 mm were produced from the billets by means of hot pressing and cold forming. Table 1 shows the composition of the individual alloys in % by weight.

(3) TABLE-US-00001 TABLE 1 Composition of the individual alloys in % by weight Cu Ni Mn Si Fe Pb Zn Inventive 48.5 9.5 0.4 0.2 0.5 <0.05 Balance alloy Comparative 49.0 7.5 3.0 3.0 Balance specimen 1 Comparative 62.5 17.5 0.4 Balance specimen 2 Comparative 48.4 9.5 0.4 0.3 0.5 1.3 Balance specimen 3

(4) Roughness measurements were carried out on the drawn wires. The following properties were determined over a measurement length of 4 mm, in each case along and transverse to the drawing direction:

(5) Ra average roughness

(6) Rz averaged peak-to-valley height

(7) Rmax maximum peak-to-valley height

(8) Rt total height of the profile

(9) The values determined on the specimens are compared in table 2.

(10) TABLE-US-00002 TABLE 2 Measured roughness values, reported in m Compar- Compar- Compar- Measurement Inventive ative ative ative direction alloy specimen 1 specimen 2 specimen 3 Ra longitudinal 0.039 0.100 0.103 0.113 transverse 0.174 0.315 0.182 0.317 Rz longitudinal 0.36 1.48 0.76 1.56 transverse 0.99 1.81 1.47 1.91 Rmax longitudinal 0.49 2.03 1.15 2.16 transverse 1.28 2.29 1.92 2.42 Rt longitudinal 0.56 2.05 1.15 2.17 transverse 2.26 2.66 2.11 2.63

(11) The measured values documented in table 2 show that the surface of the alloy according to the invention has the lowest roughness or peak-to-valley height in the case of seven of eight measured values. The alloy according to the invention thus has the best surface quality in the drawn state. In particular, the measured values determined on the alloy according to the invention are always lower than the measured values determined on the lead-containing comparative specimens 1 and 3.

(12) Cutting machining tests were carried out on the four specimens. For this purpose, a central drilled hole running parallel to the axis and having an internal diameter of 2 mm was introduced into the wires. The alloy of the invention and also the two lead-containing comparative specimens 1 and 3 could be machined without problems. The drilling chips were fine. The lead-free comparative specimen 2 became very hot in the drilling experiment and the drill broke off during the experiment.

(13) The mechanical properties documented in table 3 were determined on specimens of an alloy according to the invention having a composition as shown in table 1:

(14) TABLE-US-00003 TABLE 3 Mechanical properties of an alloy according to the invention Tensile Yield Elongation strength point at break R.sub.m R.sub.p0.2 A.sub.10 Round rod, diameter 8 735 MPa 561 MPa 11% mm Round wire, diameter 835 MPa 619 MPa 12% 2.5 mm

(15) The experiments show that a copper-nickel-zinc alloy according to the invention advantageously combines properties as are not to be found in this combination in the case of alloys known from the prior art.