EP3041966B1 - Copper alloy, which contains iron and phosphor - Google Patents

Description

The invention relates to a copper alloy having the features in the preamble of claim 1 and the use of such a copper alloy according to the features of claim 7 or 8.

As a per se, soft metal copper is appreciated in particular because of its good alloyability. Copper alloys with, for example, improved strength properties are also used where high demands are placed on current and / or thermal conductivity and corrosion resistance. Therefore, it is usually several requirements to meet simultaneously.

Since copper, with the exception of silver, has the lowest electrical resistance of all known metals, copper alloys are preferred and used for electrical contact components merely because of the frequency of copper and the associated price advantage over silver.

Such contact components include, for example, mechanically connectable and separable fasteners and crimp connections.

Copper alloys such as CuFe0.1P (C19210) and CuFe2P (C19400) are mainly used for plug-in contacts, as they have a high solid solution and medium relaxation resistance. In contrast, the aforementioned copper alloys have a poor machinability, so that they are not or only badly suitable for the production of contact components by machining.

In contrast, good machinability is achieved when using known copper alloys such as CuSP, CuTeP or CuSMn. Since these are non-hardenable alloys with very slight solid solution hardening, however, they have only a low relaxation resistance.

The alloys used in the prior art also sometimes contain components of lead (Pb) or beryllium (Be), so that these copper alloys can not be safely used for all applications due to the known toxicity of these alloying elements.

The following documents must be referred to the state of the art: JOON HWAN CHOI: "Aging Behavior and Precipitate Analysis of Copperich Cu-Fe-Mn-P alloy", MATERIALS SCIENCE AND ENGINEERING A, Vol. 550, 1 July 2012 (2012-07-01), pp. 183-190, ISSN: 0921 -5093, DOI: 10.1016 / j.msea.2012.04.055 and S RAMESH ET AL: "Corrosion inhibition of copper by new triazole phosphonate derivatives", APPLIED SURFACE SCIENCE, Vol. 229, No. 1-4, May 1, 2004 (2004-05-01), pages 214-225, ISSN: 0169-4332, DOI: 10.1016 / j.apsusc.2004.01.063 ,

In the first mentioned publication, a copper-Cu alloy is disclosed which contains 0.68% Fe and 0.38% Mn, 0.20% P, remainder copper. In the second publication, a Cu alloy is described which contains 0.021% P, 0.07% Fe, 0.0045% Ni, 1.59% Zn, 0.006% Cr, 0.003% As, 0.06% S and balance copper contains.

Against this background, the composition of copper alloys and their use in terms of their respective material properties still has room for improvement.

The invention has for its object to provide a both relaxation-resistant and machinable copper alloy available, which is free of the alloying elements beryllium and lead. Furthermore, the use of such a relaxation-resistant and machinable as well as lead and beryllium-free Copper alloy for non-cutting to produce semifinished products and resulting machined products are shown.

The solution of this problem consists according to the invention in a copper alloy with the features of claim 1 and their use with the features according to claim 7 or 8.

Unless otherwise stated below, all information on alloying elements is by weight.

A copper alloy is proposed, with proportions in weight% Iron (Fe) 0.07 - 4.00 Phosphorus (P) 0.015 - 0.50 Sulfur (S) 0.10 - 0.80

In order to achieve the required machinability, at least one element from the following group is furthermore contained for the formation of chip-breaking phases: Manganese (Mn) 0.01 - 0.80 Tellurium (Te) 0.10 - 1.00

The alloy is free of beryllium (Be) and lead (Pb) to avoid toxic properties.

Depending on the base used for the copper alloy, manganese (Mn) or tellurium (Te) may be contained alone or in combination within the specified limits.

Optionally, the copper alloy contains to improve the respective required properties: Aluminum (AI) Max. 0.50 Chrome (Cr) Max. 0.50 Magnesium (Mg) Max. 0.50 Zircon (Zr) Max. 0.50 Zinc (Zn) Max. 2.50 Tin (Sn) Max. 2.50 Boron (B) Max. 0.50 Silver (Ag) Max. 0.50

The aforementioned group are optional alloying elements. If necessary, they can be included individually or in combination within the specified limits.

The alloy contains copper (Cu) as the remainder and may contain common impurities caused by melting.

The copper alloy according to the invention combines good machinability and high relaxation resistance. Especially with respect to lead (Pb), it has been found that its addition of not more than 0.1% does not improve the machinability. In the case of lead addition, the hot cracking risk is predominated by lead smelting on the grain boundaries of the crystallites. This is remarkable because in the case of the copper materials known in the prior art, the improvement in machinability is generally attributable to the addition of lead (Pb) in metallic form.

Phosphorus (P) forms iron phosphide precipitates with iron (Fe). Iron (Fe) generally serves to increase the corrosion resistance of the copper alloy.

With the addition of sulfur and optionally manganese (Mn) and / or tellurium (Te) within the specified limits, the machinability of the alloy according to the invention is also improved without the addition of lead (Pb) by forming chip-breaking phases.

Manganese (Mn) acts as a hardening agent and serves as a deoxidizer within the copper alloy. Furthermore, by manganese (Mn), the grain of the copper alloy can be refined.

Sulfur (S) improves the machinability of the copper material. Manganese (Mn) prevents or reduces the phase formation of sulfur (S) with other alloying elements.

In addition to the improved machinability and relaxation resistance, the copper alloy according to the invention has good electrical conductivity, which, depending on the composition tested, reaches up to 52 MS / m for CuFe0.02PS.

Advantageous developments of the inventive concept are the subject of the dependent claims 2 to 6.

Hereinafter, the alloy components of the above group, if added, may be contained in a range of 0.01 - 2.50 wt% each with respect to zinc (Zn) and tin (Sn).

Further, amounts of aluminum (Al), boron (B), chromium (Cr), magnesium (Mg), silver (Ag), and zircon (Zr) may each be 0.01% - 0.5% by weight.

Phosphorus (P) and boron (B) have the property of counteracting hydrogen disease. The oxygen dissolved in the copper mixed crystal is bound to these alloying elements by the addition of phosphorus (P) and optionally boron (B). When hydrogen is absorbed in the material, no water vapor can form, which loosens up the microstructure. Phosphorus (P) and boron (B) act as deoxidizers.

Furthermore, the addition of phosphorus (P) prevents the oxidation of individual alloying elements. Moreover, the tile properties of the copper alloy during casting can be improved by adding phosphorus (P).

By the addition of aluminum (Al) according to the invention, the hardness of the copper material and its yield strength can be increased without reducing the toughness. Aluminum (Al) is an alloying element by which the strength, machinability and wear resistance of the copper alloy at high temperatures can be improved. Incidentally, this also applies to the improvement of the oxidation resistance of the copper alloy.

The addition of chromium (Cr) and magnesium (Mg) also serves to improve the oxidation resistance of the copper alloy at high temperatures. Particularly good results are observed in this context when chromium (Cr) and magnesium (Mg) are added in combination with aluminum (Al). In this way, an advantageous synergy effect of these components can be achieved.

Zircon (Zr) can improve the hot workability of the copper material according to the invention.

In particular, in the case of an at least partial tin-plating of the copper alloy, it is proposed to add in a proportion of zinc (Zn) in a range from 0.01 to 2.50%. Zinc (Zn) improves the adhesion of the tin-plating or improves the resistance to the peel-off behavior of peelings.

Tin (Sn) can further increase the solid solution hardening of the copper alloy according to the invention.

Sulfur (S) and tellurium (Te) as chip breakers may preferably be combined with manganese (Mn). Sulfur and manganese form manganese sulfides, which increase the machinability towards copper sulfides.

Hereinafter, particularly preferred compositions in relation to the alloying elements phosphorus (P), sulfur (S), manganese (Mn) and tellurium (Te) are given, wherein in addition the other alloying elements specified in claim 1 may be contained in the copper alloy. The remainder is formed by copper and impurities caused by melting:
A) Iron (Fe) 0.07 - 3.50 Phosphorus (P) 0.015 - 0.40 Sulfur (S) 0.15-0.70 and at least one element from the following group: Manganese (Mn) 0.03 - 0.75 Tellurium (Te) 0.05-0.90
B) Iron (Fe) 0.20 - 3.20 Phosphorus (P) 0.017 - 0.30 Sulfur (S) 0.20 - 0.62 and at least one element from the following group: Manganese (Mn) 0.05-0.70 Tellurium (Te) 0.20 - 0.80
C) Iron (Fe) 0.40 - 3.00 Phosphorus (P) 0.022 - 0.20 Sulfur (S) 0.25-0.57 and at least one element from the following group: Manganese (Mn) 0.08 - 0.55 Tellurium (Te) 0.30 - 0.70
D) Iron (Fe) 0.75 - 2.60 Phosphorus (P) 0.025 - 0.15 Sulfur (S) 0.30 - 0.50 and at least one element from the following group Manganese (Mn) 0.10 - 0.40 Tellurium (Te) 0.40 - 0.60

Figur 1

Stahl-Eisen-Prüfblatt (SEP) 1178-90 zur analogen Beurteilung der Spanformklasse der erfindungsgemäßen Kupferlegierung;

Figur 2

Untersuchungsergebnisse an den Kupferlegierungen CuSP, CuTeP und CuSMn mit Blick auf die Spanformklassen durch mechanische Bearbeitung in Form von Außenlängsdrehen bei Variation der Schnittgeschwindigkeit;

Figur 3

die Untersuchungsergebnisse an den Werkstoffen aus Figur 2 in Bezug auf die Spanformklassen bei Varianten der Schnitttiefe;

Figur 4

die Ergebnisse der Spanformklassen der Figuren 2 und 3 in Abhängigkeit von den jeweiligen Vorschub bei der mechanischen Bearbeitung;

Figur 5

eine tabellarische Übersicht der Werkstoffeigenschaften einzelner im Stand der Technik bekannter Kupferlegierungen mit einer erfindungsgemäßen Kupferlegierung;

Figur 6

ein Schliffbild durch die Gefügestruktur der im Stand der Technik bekannten Kupferlegierung CuSP;

Figur 7

ein Schliffbild durch die Gefügestruktur der im Stand der Technik bekannten Kupferlegierung CuTeP;

Figur 8

ein weiteres Schliffbild durch die Gefügestruktur der im Stand der Technik bekannten Kupferlegierung CuSMn;

Figur 9

ein Schliffbild durch die Gefügestruktur der im Stand der Technik bekannten Kupferlegierung CuFe0,1P;

Figur 10

eine Abbildung der sich bei der mechanischen Bearbeitung der im Stand der Technik bekannten Kupferlegierung aus Figur 9 ergebenden Spanausbildung;

Figur 11

ein Schliffbild durch die Gefügestruktur einer erfindungsgemäßen Kupferlegierung CuFe0,1PS;

Figur 12

eine Abbildung der sich bei der mechanischen Bearbeitung der erfindungsgemäßen Kupferlegierung aus Figur 11 ergebenden Spanausbildung;

Figur 13

Diagramm zur Variation des Fe- und P-Gehalts bei konstantem Gehalt der Spanbrecher S oder S + Mn und/oder Te und

Figur 14

Diagramm zur Variation der Gehalte der Spanbrecher S oder S + Mn und/oder Te bei konstantem Gehalt der Basiselemente Fe und P.

The present invention will be explained in more detail below with reference to figures and tables, in particular in distinction from the prior art. Show it:

FIG. 1

Steel Iron Test Sheet (SEP) 1178-90 for analogous evaluation of the chipforming class of the copper alloy according to the invention;

FIG. 2

Test results on the copper alloys CuSP, CuTeP and CuSMn with regard to the chip forming classes by mechanical machining in the form of external longitudinal turning with variation of the cutting speed;

FIG. 3

the examination results on the materials FIG. 2 in relation to the chipform classes in variants of the depth of cut;

FIG. 4

the results of the chipforming classes of Figures 2 and 3 depending on the respective feed in the mechanical processing;

FIG. 5

a tabular overview of the material properties of individual copper alloys known in the art with a copper alloy according to the invention;

FIG. 6

a microsection through the microstructure of the known in the prior art copper alloy CuSP;

FIG. 7

a microsection through the microstructure of the known in the prior art copper alloy CuTeP;

FIG. 8

a further microsection through the microstructure of the known in the prior art copper alloy CuSMn;

FIG. 9

a microsection through the microstructure of the known in the prior art copper alloy CuFe0,1P;

FIG. 10

a picture of itself in the mechanical processing of the known in the prior art copper alloy FIG. 9 resulting chip training;

FIG. 11

a microsection through the microstructure of a copper alloy according to the invention CuFe0.1PS;

FIG. 12

a picture of itself in the mechanical processing of the copper alloy according to the invention FIG. 11 resulting chip training;

FIG. 13

Diagram for the variation of the Fe and P contents at a constant content of the chipbreaker S or S + Mn and / or Te and

FIG. 14

Diagram for varying the contents of the chipbreaker S or S + Mn and / or Te at a constant content of the basic elements Fe and P.

In order to explain the positive properties and differences of the copper alloy according to the invention compared to the copper alloy known in the prior art, a group of the known copper alloys CuSP (CW114C), CuTeP (CW118C, C14500) and CuSMn (C14750) were first examined in more detail.

Out FIG. 1 A steel iron test sheet 1178-90 is given to refer to the resulting in the machining machining embodiments of the chips analogously to the group under investigation.

The resulting chip image was classified into one of eight chipforming classes (1 - 8), as can be seen in the first column, to the left of the chips shown schematically. The individual chip images are associated with appropriate terminology according to their design, ranging from "band chips" to "shavings".

In the column to the right of the chip forming classes, the chip space number R is listed, which indicates the relationship between the space requirement of a disordered chip quantity (V _span ) and the material volume of the same chip quantity (V). A small chip space number R suggests small chips, which require little space in their spatial design. Thus, these are much easier to handle compared to large chips. In contrast, a large number of chip spaces R makes it possible to close a large space requirement of the chips, so that their handling is made considerably more difficult due to the expanding volume.

The chipform classes and the respective chip space numbers R are in the far right column in FIG. 1 judging the chip forming classes 7 and 8 with their respective chip space R as "usable", while the chip forming classes 5 and 6 are judged in combination with their respective Spanraumzahlen R as "good". On the other hand, the remaining chip forming classes 1 to 4 in connection with their respective chip space number R are classified as "unfavorable", with a smooth transition to "good" occurring in chipform classes 3 and 4.

FIG. 2 Figure 3 shows the results of mechanical working of the examined group of known copper alloys with respect to the resulting chip forming classes in outboard turning of a workpiece thereof.

With FIG. 2 present results are based on a constant depth of cut a _p of 1.5 mm and a feed f of 0.2 mm. The respective cutting speed v _c was varied from 450 m / min (v _c1 ) to 150 m / min (v _c2 ). As can be seen, the respective chip form classes of the materials from the group (CuSP, CuTeP and CuSMn) are all between 3 and 5. The resulting chip images are also shown schematically in the present table. For better clarity, they are each assigned a single line for 20mm as a reference in order to be able to better estimate the results in the form of the chip sizes set during the examination.

FIG. 3 shows the results of further processing steps of the group FIG. 2 , At a constant cutting speed v _c of 450 m / min, the respective cutting depth a _{p was} varied from 1.5 mm (a _p1 ) to 0.75 mm (a _p2 ). As with the previous ones and in terms of their results in FIG. 2 In this case, a constant feed rate of f = 0.2 mm was observed.

Out FIG. 3 shows that the variation of the depth of cut (a _p ), in particular for the materials CuSP and CuTeP, leads to a change in the chipforming class, with an increase in the cutting depth a _p indicating a deterioration of the chipforming class. In contrast, the chipform class of CuSMn remains during the variation of the depth of cut a _p constant, as was the case with the variation of the cutting speed v _c (see FIG. 2 ).

As can be seen, the chip form class, in particular of the copper alloy CuSMn, thus remains constant both in the case of variation of the cutting speed and in the case of variation of the cutting depth in the respectively present areas.

Furthermore, the group of investigated copper alloys also moves with variation of the cutting depth a _p in a range of chipforming classes 3 to 5.

Out FIG. 4 the result of the variation of the feed f results in its effect on the chip forming class of the respective copper alloys from the group studied. As can be seen, the chipforming class of the group deteriorates with decreasing feed f as a whole. In the case of the Figures 2 and 3 resulting feed f of 0.2 mm, however, all three copper alloys of the test group are close to each other. Only the copper alloy CuSMn improves its chipbreaker class with increasing feed f, which was tested to 0.3 mm in the present case. The respective resulting chip forms also result from the diagrams shown schematically in combination with the present table.

The thus obtained and in the FIGS. 2 to 4 Composed results were then compared with the test results for the present copper alloy according to the invention.

The reference value used was the well-known copper alloy CuZn39Pb3, which is considered to be the main alloy for machining, especially in Germany. Said copper alloy is used everywhere, where it increasingly depends on a cutting and cutting shaping. In connection with the CuZn39Pb3 copper alloy used herein as reference, its machinability is assumed to be 100%.

In contrast, pure copper material achieves a stress index of 20% to a maximum of 30%. These types of copper are low alloyed and hardenable copper materials which do not contain chip-breaking elements such as sulfur (S), tellurium (Te) and sulfur (S) and manganese (Mn) and lead (Pb).

Between these two copper materials, the group investigated here is such that CuSP has a stress index of 70%, while CuTeP has a stress index of 80%. Finally, CuSMn achieves the highest stress index in the group of 90%.

FIG. 5 shows a tabular comparison of the materials contained therein in relation to their respective material properties.

In addition to the materials listed below each other in the left-hand column, their corresponding sizes can be found on the right next to each other, starting with the 0.2% proof stress R _p0.2 . Right next to it there is the tensile strength R _m and elongation at break A.

In the following right column, the respective Brinell hardness (HBW) is given and in the right following column, the conductivity of the individual materials. The last two columns on the far right show qualitatively the respective relaxation and the machinability in the form of the stress index in%.

The present table in FIG. 5 is constructed so that it reflects the approximate manufacturing cost of the individually listed materials, starting with the cheapest material above.

The table shows the copper alloy according to the invention with the orders of magnitude of its individual alloy components listed there, more specifically CuFe0.1PS0.35 and CuFe2PS0.35.

As can be seen, the copper alloy CuFe0.1PS0.35 in direct comparison with only chip-breaking alloyed materials (CuSP, CuTeP and CuSMn) has a somewhat lower 0.2% yield strength and tensile strength R _m . The elongation at break is 17% and the relaxation with "o" better than CuSP, CuTeP and CuSMn. The alloy CuFe2PS0,35 has higher mechanical properties Characteristics and a higher relaxation resistance, which is indicated in the table with "+", on.

The comparable with the invention materials CuFe0,1P and CuFe2P each have a similar good relaxation resistance, however, on the other hand, however, have a significantly poorer machinability of only 20 or 25% compared to the copper alloy according to the invention CuFe0.1PS and CuFe2PS.

It is striking that the materials listed in the first four lines have a similarly good and with 100% CuZn39Pb3 correspondingly higher cutting index, however, in their respective relaxation resistance of the copper alloy CuFePS0.35 of the invention clearly subject.

The values listed here for the respective stress index of the materials known in the prior art were taken in part from the information print i18 of the German copper institute "Guidelines for the Machining of Copper and Copper Alloys".

The determination of the mechanical characteristic values for the present table was carried out according to DIN ISO 6892-1. The respective sample shape corresponded to the form A according to DIN 50125. The respective conductivity was determined using a Sigmatester from Förster. The respective relaxation behavior was extrapolated on the basis of internal measurements on the related materials, which, however, compared to the copper alloy of the invention contained no chip-breaking elements according to the invention.

The FIGS. 6 to 9 each show a micrograph of the microstructures from the group of individual copper materials underlying the investigations.

FIG. 6 shows the material CuSP with its arrangement of the chip-breaking elements. Its microstructure shows in part closely spaced and each dark copper sulfides, which serve here as a chip breaker.

FIG. 7 shows in contrast the material CuTeP, which contains in its microstructure darkened Kupfertellurieden as a chip breaker. These are in their arrangement largely isolated and further apart.

Out FIG. 8 shows the microstructure of the material CuSMn, which contains manganese sulphides as a chipbreaker. As already from the in the FIGS. 2 to 4 and in line four of the table FIG. 5 As a result, CuSMn has a high chipping index with a mostly good chipforming class, due to the in FIG. 8 apparent uniform distribution of its chipbreaker is due.

FIG. 9 shows for comparison the etched microstructure of the standardized material CuFe0.1P (C19210) without chip breaking phases.

In addition to the copper mixed crystal, iron phosphors that are not visible under light microscopy are present. The iron phosphides have no chipbreaking effect. When machining the material unfavorably long chips ( Fig. 10 ) which can wrap around the cutting tools and cause the standstill of a lathe (parameters: v _C = 100 m / min, f = 0.1 mm, a _P = 1.0 mm).

Out FIG. 11 shows the microstructure of the material CuFe0,1PS0,35 invention. This also has copper chip sulphide as chipbreaker. As you can see, this one has the in FIG. 8 shown copper material CuSMn similarly good distribution of its chipbreaker, which manifests itself in a good machinability.

Its production was based on casting in continuous casting, with a diameter of 273 mm to a diameter of 28 mm. Furthermore, the production involved the drawing of diameter 28 mm to diameter 24 mm. Subsequently, recrystallization annealing was carried out at 540 ° C for 4 hours in ambient air and further deformation.

FIG. 12 shows the chip formation after the mechanical processing of the copper material according to the invention CuFe0,1PS0,35. Based on the structure of the FIG. 11 and the chipform class of the present Material CuFe0,1PS0,35 in comparison to the investigations on the previous materials CuSP, CuTeP and CuSMn can be concluded with a stress index of at least 70% (chip class 3 - 6 according to SED1178-90, at v _C = 100m / min, f = 0.1 mm, a _P = 1.0 mm).

Depending on the requirement profile, it is thus possible to select suitable combinations of properties from the machinable copper alloys according to the invention. A special feature of the copper alloy is that a processability with conventional manufacturing and processing machines is possible. Advantageously, the copper alloy according to the invention has both a sufficient cold workability and a very good hot workability.

In the present case, the invention is also directed to the use of such a copper alloy for the production of a product to be machined according to claim 7.

Furthermore, the invention is directed to the use of such a copper alloy for the production of a semi-finished to be produced according to claim 8. This may in particular be a rolled, pressed, drawn, forged or cast product. For example, rods and wires can be delivered from press and pull sequences as semi-finished products.

From the bars and wires, for example, the following products can be produced by machining: plug contacts, crimping sleeves, crimp connectors, drilled shaft nails, motor parts, screws, locating pins, clamps, welding nozzles, cutting torch nozzles, valves, fittings, nuts, fittings, contraelectrons, contact pins.

FIG. 13 shows a diagram for varying the Fe and P content at a constant content of the chip breaker S or S + Mn and / or Te and FIG. 14 shows a diagram for varying the contents of the chip breaker S or S + Mn and / or Te at a constant content of the basic elements Fe and P.

From this the mutual interactions of the alloying elements can be read off.

Claims (8)

1. Copper alloy, comprising, in proportions in % by weight: iron (Fe) 0.07 - 4.00 phosphorus (P) 0.015 - 0.50 sulphur (S) 0.10 - 0.80 wherein the alloy is free of beryllium (Be) and lead (Pb) and optionally contains: aluminium (Al) max. 0.50 chrome (Cr) max. 0.50 magnesium (Mg) max. 0.50 zirconium (Zr) max. 0.50 zinc (Zn) max. 2.50 tin (Sn) max. 2.50 boron (B) max. 0.50 silver (Ag) max. 0.50 manganese (Mn) 0.01 - 0.80 tellurium (Te) 0.10 - 1.00, the remainder being copper (Cu) and impurities caused by melting.
2. Copper alloy according to claim 1, characterised in that it optionally contains at least one of the following alloying elements with the following proportions in % by weight: aluminium (Al) 0.01 - 0.50 chromium (Cr) 0.01 - 0.50 magnesium (Mg) 0.01 - 0.50 zirconium (Zr) 0.01 - 0.50 zinc (Zn) 0.01 - 2.50 tin (Sn) 0.01 - 2.50 boron (B) 0.01 - 0.50 silver (Ag) 0.01 - 0.50
3. Copper alloy according to claim 1 or 2, characterised by the following proportions in % by weight: iron (Fe) 0.07 - 3.50 phosphorus (P) 0.015 - 0.40 sulphur (S) 0.15 - 0.70 and at least one element from the following group: manganese (Mn) 0.03 - 0.75 tellurium (Te) 0.05 - 0.90
4. Copper alloy according to claim 1 or 2, characterised by the following proportions in % by weight: iron (Fe) 0.20 - 3.20 phosphorus (P) 0.017 - 0.30 sulphur (S) 0.20 - 0.62 and at least one element from the following group: manganese (Mn) 0.05 - 0.70 tellurium (Te) 0.20 - 0.80
5. Copper alloy according to claim 1 or 2, characterised by the following proportions in % by weight: iron (Fe) 0.40 - 3.00 phosphorus (P) 0.022 - 0.20 sulphur (S) 0.25 - 0.57 and at least one element from the following group: manganese (Mn) 0.08 - 0.55 tellurium (Te) 0.30 - 0.70
6. Copper alloy according to claim 1 or 2, characterised by the following proportions in % by weight: iron (Fe) 0.75 - 2.60 phosphorus (P) 0.025 - 0.15 sulphur (S) 0.30 - 0.50 and at least one element from the following group: manganese (Mn) 0.10-0.40 tellurium (Te) 0.40-0.60
7. Use of a copper alloy according to any of the preceding claims 1 to 6 for the manufacture of a product to be machined.
8. Use of a copper alloy according to any of the preceding claims 1 to 6 for the manufacture of a semi-finished product that is not to be machined, in particular in the form of a rolled, pressed, drawn, forged or cast product.

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