TW202407111A - Wrought copper-zinc alloy, semi-finished product made from a wrought copper-zinc alloy, and method for producing such a semi-finished product - Google Patents

Abstract

The invention relates to a wrought copper-zinc alloy for producing a wire-shaped, tubular or rod-shaped semi-finished product with the following composition in wt.%: Cu: 58.0 to 63.0%; Si: 0.04 to 0.32%; P: 0.05 to 0.20%; Sn: optionally up to 0.25%; Al: optionally up to 0.10%; Fe: optionally up to 0.30%; Ni: optionally up to 0.30%; Pb: optionally up to 0.25%; Te, Se, In: optionally up to 0.10% each; Bi: maximum 0.009%; and the remainder Zn and unavoidable impurities, wherein the proportion of unavoidable impurities is less than 0.2 wt.%. The ratio of the weight proportions of P and AI is at least 1.0. The alloy has a microstructure consisting of a globular [alpha] phase, a [beta] phase, and phosphide particles. The proportion of [beta] phase in relation to the total of [alpha] phase and [beta] phase is at least 20 vol.% and at most 70 vol.%. Si is present both in the [alpha] phase and in the [beta] phase. In an area of 21000 [mu]m2, there are 7 to 200 phosphide particles with an equivalent diameter of 0.5 to 1 [mu]m, 4 to 150 phosphide particles with an equivalent diameter of 1 to 2 [mu]m, and a maximum of 30 phosphide particles with an equivalent diameter of more than 2 [mu]m.

Description

Copper-zinc malleable alloy, semi-finished products composed of copper-zinc malleable alloy and methods of manufacturing such semi-finished products

The present invention relates to a copper-zinc wrought alloy for manufacturing wire-shaped, tubular or rod-shaped semi-finished products, a semi-finished product composed of copper-zinc wrought alloy, and a method for manufacturing such semi-finished products.

Copper-zinc alloys with 3 to 5 wt% lead have excellent machinability and excellent hot and cold forming properties. Therefore, lead-containing copper-zinc alloys are widely used, for example, in the automotive industry, construction technology, machinery manufacturing, electrical equipment and electronic components, connectors and components in telecommunications, and as accessories in aquatic facilities.

The positive role of lead in copper-zinc malleable alloys is based on the fact that lead is present in elemental form as particles in the structure, and these particles act as chip breakers. When performing cutting processing, lead exists in the liquid phase due to local severe deformation and local heating caused by the workpiece. Lead cannot absorb stress in the liquid state, so the stress is concentrated on the weakened matrix that transmits the load, making chip breakage more likely to occur. In addition, lead will be embedded in the wear layer between the material and the tool during cutting, thereby providing effective lubrication and reducing friction and wear. In addition, due to its low solubility, lead has almost no effect on electrical conductivity. This is particularly advantageous for materials used in electrical applications. Furthermore, lead is known to cause significant grain refinement in copper-zinc alloys. This helps achieve linearity and dimensional accuracy, especially for rod-shaped semi-finished products. High dimensional accuracy is also required when crimping electronic wires. Additionally, lead is cheap.

But lead is harmful to the environment. Lead can accumulate in the body after ingesting very small amounts and can cause damage to health. Therefore, the European Union, the United States, China and other countries continue to lower the limit values in copper alloys and seek to replace lead-containing brass with machinable copper alloys with less or no lead. Limit values are set within the framework of EU directives, such as RoHS (Directive 2011/65/EU), which stipulates that 1000 ppm (0.1%) Pb is the upper limit. In order to ensure that the material has good machinability even with such a low lead content, various alloying elements have been proposed as substitutes for lead.

Bismuth (Bi) is used as a substitute for lead in several publications to improve machinability. In order to alleviate the problem of Bi film formation along grain boundaries and the related problems of stress cracking and thermal cracking, it is proposed to add more alloying elements. In this regard, see in particular open cases KR 10 0 555 854 B1, KR 10 2006 096 877 A, JP 2005 290 475 A, JP 2014 122 427 A and JP 2006 083 443 A. Despite this, Bi is still not an ideal choice because it is a scarce metal that is difficult to obtain and can cause thermal brittleness during the material cycle of copper materials.

In addition, Publication EP 2 194 150 B1 discloses a copper-zinc alloy containing 0.1 to 1.5 wt% Si, 0.03 to 0.4 wt% Al, 0.01 to 0.36 wt% P, 0.05 to 0.5 wt% Sn and 0.001 to 0.05 wt% rare earth elements. These metals are easily machined due to their alpha, beta and possibly gamma structures. Aluminum phosphide is formed due to the Al ratio. Gamma phase and aluminum phosphide improve chip formation, but shorten tool life. In addition, the proportion of rare earth elements may cause structural embrittlement. These alloys are used in castings and hot pressed parts.

In addition, in the public case WO 2020/261 604 A1, for a product containing 58.5 to 63.5 wt% Cu, 0.4 to 1.0 wt% Si, 0.005 to 0.19 wt% P, 0.003 to 0.25 wt% Pb, and the remainder is zinc and other optional elements, describes the use of phosphorus in place of lead, which forms brittle phosphides in the alloy. In this case, an easy-to-machine material was created by adding 0.005 to 0.19 wt% P to form phosphide and 0.4 to 1.0 wt% Si to reinforce the α and β phases. However, due to the higher proportion of Si, the conductivity is reduced compared to lead-containing brass. On the one hand, this is disadvantageous for use as a component of electronic devices. On the other hand, the phosphide loses its brittleness and thus its chip-breaking function, especially at the higher temperatures that occur, for example, during drilling. The worse the thermal conductivity and electrical conductivity of the material, the more obvious this effect will be.

The object of the present invention is to provide a copper-zinc wrought alloy for the production of wire-shaped, tubular or rod-shaped semi-finished products, which has excellent machinability, especially in drilling, good electrical conductivity, and as little contamination as possible. Ecologically hazardous alloy components. In addition, this alloy is easy to process according to industry standards. This requires that the alloy can be well hot-formed, for example by extrusion, can be well cold-formed, for example by drawing or crimping, and that semi-finished products made from the alloy have excellent straightness and excellent dimensions. Accuracy. Another object of the present invention is to provide a method for manufacturing wire-shaped, tube-shaped or rod-shaped semi-finished products using the alloy.

The object of the present invention with respect to the copper-zinc wrought alloy is achieved by the features of claim 1, and the object with respect to the manufacturing method is achieved with the features of claim 16. Further back-referenced claims relate to advantageous constructions and improvements of the invention.

The invention relates to a copper-zinc malleable alloy used for manufacturing wire-shaped, tubular or rod-shaped semi-finished products, having the following composition (unit: wt%): Cu: 58.0 to 63.0%, Si: 0.04 to 0.32%, P: 0.05 to 0.20%, Sn: optionally up to 0.25%, Al: optionally up to 0.10%, preferably up to 0.05%, Fe: optionally up to 0.30%, preferably up to 0.10%, Ni: optional Ground at most 0.30%, Pb: optionally at most 0.25%, preferably at most 0.10%, Te, Se, and In optionally at most 0.10% each, Bi: maximum 0.009%, the rest is Zn and inevitable impurities, where The proportion of unavoidable impurities is less than 0.2 wt%. The weight proportion ratio of P to Al is at least 1.0. This alloy has a structure composed of spherical α phase, β phase and phosphide particles. The proportion of β phase in the sum of α phase and β phase is at least 20 vol%, preferably at least 30 vol%, and at most 70 vol%, preferably at most 50 vol%. Silicon exists in both the alpha and beta phases. The presence of 7 to 200 phosphide particles with an equivalent diameter of 0.5 to 1 µm, 4 to 150 phosphide particles with an equivalent diameter of 1 to 2 µm, and a maximum of 30 phosphide particles ^with an equivalent diameter greater than 2 in an area of 21000 µm µm phosphide particles.

The present invention is based on the following concept: reducing the proportion of Pb in the copper-zinc alloy as much as possible without affecting the machinability of the alloy. To this end, Si and P elements are added to the alloy in a targeted manner and the proportion of the β phase is adjusted to produce favorable cutting characteristics and high conductivity, especially in drilling, without compromising the hot forming and cold forming properties of the alloy. variation, as well as, resulting in superior linearity of semi-finished products made from this alloy. Furthermore, the process control, especially during casting and thermoforming, is selected in such a way that the desired properties are produced.

Prerequisites for good linearity and dimensional accuracy of spherical α-phase semi-finished products. The alpha phase is generated from the beta phase after thermoforming. Therefore, the β phase must be fine-grained in the casting state. The present invention has surprisingly found that uniformly finely distributed copper- and/or zinc-containing phosphides contribute to the fine-grained beta phase in the as-cast condition. During the primary crystallization process of β crystallites, the residual melt is rich in P, causing the subdivision of the β phase. During the solidification process, a eutectic of phosphide and β phase is formed. In addition to the grain refinement of the β phase basic matrix, grain refinement of the α crystallites was also observed. This grain refinement of the cast structure due to P contributes to thermoforming and is carried over into the structure after thermoforming, thereby causing grain refinement in the final state. In the case of a P proportion of at least 0.05 wt%, the phosphide particles are present in the beta phase in the final state. At P content above 0.20 wt%, the alloy is less ductile.

Furthermore, the higher P proportion together with Si adversely affects the electrical conductivity. Therefore, in a preferred embodiment of the invention, the sum of the proportions of Si and P is preferably at most 0.45 wt%.

Furthermore, it is necessary for the globular alpha phase to cool the material in a controlled manner after thermoforming. In the temperature range of 550°C to 350°C, the cooling rate must be at least 30°C per minute (30°C/min), preferably at least 40°C per minute, and at most 60°C per minute, preferably at most 30°C per minute. minutes 50°C. The uniformly finely distributed phosphide produced with the fine-grained beta phase in the as-cast state is dissolved in the matrix during thermoforming and is subsequently reformed during the cooling operation in thermoforming. In this way, the characteristic distribution of phosphides in the as-cast state is ultimately mapped to the structure in the final state. Therefore, the distribution of phosphide in the final state and the globular shape of the α phase are not only determined by the chemical composition of the alloy, but also by the process control during the casting process and hot forming process. Therefore, the characteristics of the phosphide in its final state are like the fingerprints left on the product by the special process controls. The distribution of phosphide in the ^final state can be characterized by the presence of 7 to 200 phosphide particles with an equivalent diameter of 0.5 to 1 µm and 4 to 150 phosphide particles with an equivalent diameter of 1 to 2 µm in an area of 21000 µm Phosphide particles, and a maximum of 30 phosphide particles with an equivalent diameter greater than 2 µm. The equivalent diameter of the phosphide particles refers to the diameter of a circle with the same area as the phosphide particles. The main part of the phosphide particles having an equivalent diameter of at least 0.5 µm has an equivalent diameter of at most 2 µm. Preferably, among all phosphide particles with an equivalent diameter of 0.5 μm, the proportion of phosphide particles with an equivalent diameter of 0.5 to 2 μm is at least 70%. Preferably, this ratio is at least 75%. Furthermore preferably, at least 30%, preferably at least 50%, of all phosphide particles with an equivalent diameter of at least 0.5 µm have an equivalent diameter of at most 1 µm. The presence of phosphides in the alloy with an equivalent diameter less than 0.5 µm is not excluded.

In order to achieve machinability of the alloy, it is preferable to use brittle structural components, which act as separation points during cutting and thus assist in chip breaking. The β phase is brittle and beneficial to machinability. By increasing the Zn content and/or by adding silicon, the proportion of β phase can be increased because silicon stabilizes the β phase. Furthermore, in order to achieve good machinability, it is better to reduce the ductility of the α phase. This is achieved by adding silicon and embedding the silicon into the alpha phase. Therefore, the Si proportion in the alloy must be at least 0.04 wt%. In the case where the Si proportion is higher than 0.32 wt%, the electrical conductivity is less than 12 MS/m and is insufficient. A P proportion of at least 0.05 wt% leads to favorable chips in drilling. Furthermore, smaller selectable proportions of Pb have a favorable effect on machinability.

The alloy has a Cu content of 58.0 to 63.0 wt%. In the case where the Cu proportion is less than 58.0 wt%, the ductility of the alloy is too small. When the Cu proportion is higher than 63.0 wt%, the zinc proportion in the alloy is too small to achieve good machinability.

The weight proportion ratio of P to Al is at least 1.0. Aluminum and phosphorus form aluminum phosphide. However, aluminum phosphide does not improve cutting characteristics and is therefore undesirable. In order to have a sufficient excess of P to form copper- and/or zinc-containing phosphides, the weight proportion ratio of P to Al in the alloy must be at least 1.0.

The optional elements Sn and Al assist in the formation of the beta phase. In the case where the Sn proportion is higher than 0.20 wt%, the cutting characteristics of the alloy deteriorate. However, up to a Sn proportion of 0.25 wt%, this deterioration can be compensated for by heat treatment. Preferably, the proportion of tin should be at most 0.20 wt%, especially at most 0.10 wt%.

Aluminum and phosphorus form aluminum phosphide. However, the formation of aluminum phosphide is undesirable, so the Al proportion should not exceed 0.10 wt%, preferably not more than 0.05 wt%.

Iron causes grain refinement of the structure. In addition, iron forms hard phosphides, which negatively affect the service life of the tool during cutting. Therefore, a permissible proportion of iron is at most 0.30 wt%, preferably at most 0.10 wt%.

Nickel assists in the formation of alpha phase, thereby improving cold forming properties. Furthermore, nickel forms phosphides which do not have any beneficial effect on machinability. Therefore, the permissible proportion of nickel is at most 0.30 wt%, preferably at most 0.10 wt%.

Bi element exists as an impurity in secondary raw materials such as scrap metal. This element can improve the machinability of the alloy. However, proportions above 0.009 wt% may negatively affect thermoforming properties. Therefore, up to 0.009 wt% Bi is allowed in this alloy.

The elements Te, Se and In can have a beneficial effect on the machinability of the alloy. In amounts not exceeding 0.1 wt% each, these elements have no negative effect on the alloy. Therefore, up to 0.1 wt% of Te, Se and In are each allowed in this alloy.

The remainder of the alloy composition consists of zinc and unavoidable impurities. In order to avoid uncontrollable effects of impurities on the properties of the alloy, the maximum proportion of such impurities is 0.2 wt%. Preferably, the proportions of Mn and Mg should in particular be at most 0.1 wt% each, more preferably at most 0.07 wt% each, since these elements may form phosphides that conflict with copper- and/or zinc-containing phosphides.

In a preferred technical solution of the present invention, the proportion of Pb in the alloy can be at least 0.02 wt%. Such a small proportion of Pb already improves the cutting characteristics and has a positive influence on grain refinement.

Preferably, the P proportion should be at most 0.15 wt%, especially at most 0.12 wt%. This has a beneficial impact on the hot forming properties of the alloy.

In an advantageous embodiment of the invention, the P/Fe ratio can be at least 1.0. Iron and phosphorus form hard iron phosphide. However, the formation of iron phosphide is undesirable because it shortens the service life of the tool. In order to have a sufficient excess of P in the alloy to form copper- and/or zinc-containing phosphides, the weight proportion ratio of P to Fe must be at least 1.0.

Within the scope of a preferred technical solution of the present invention, the Fe proportion may be less than 0.10 wt%, and the Ni proportion may be at most 0.07 wt%. Through this limitation, the formation of iron phosphide and nickel phosphide is hindered rather than the formation of copper-containing and/or zinc-containing phosphides that contribute to cutting. Particularly advantageous properties are achieved if the condition that the P/Fe ratio is at least 1.0 is simultaneously met. Furthermore, particularly preferably, the Fe proportion is at most 0.05 wt% and/or the Ni proportion is at most 0.04 wt%.

In an advantageous embodiment of the invention, the Si proportion can be at least 0.23 wt%. This contributes to the alloy's cutting properties. Furthermore, a Si proportion of at least 0.23 wt% has a beneficial effect on the surface quality of the product.

In an alternative embodiment of the invention, the Si proportion may be at most 0.15 wt%, preferably at most 0.12 wt%, especially at most 0.08 wt%. This restriction of the Si proportion has a beneficial effect on the electrical conductivity of the alloy.

In this alternative embodiment of the invention, the proportion of P may preferably be up to 0.10 wt%. This particularly contributes to the electrical conductivity of the alloy.

Furthermore, in this alternative embodiment of the invention, the Cu proportion may be up to 59.5 wt%. This upper limit for the proportion of Cu results in a particularly advantageous combination of conductivity, machinability, mechanical properties and processability.

In another embodiment of the invention, the sum of the proportions of the elements Cu, Zn, Si, P and Pb may be at least 99.75 wt%. This ensures that the properties of the alloy are generally determined by the alloying elements Cu, Zn, Si, P and Pb, while the influence of other elements only plays a very small role. Alternatively or additionally, the composition of the alloy can be selected such that the proportions of the elements Cu, Zn, Si, P, Sn and Pb add up to at least 99.85 wt%. Since tin phosphide is not formed, it is less critical as an alloy component than, for example, Fe, Ni or Al.

Preferably, the copper-zinc wrought alloy may have a hardness of at least 120 HV10, preferably at least 150 HV10.

Preferably, the copper-zinc wrought alloy may have a tensile strength R _m of at least 500 MPa, preferably at least 530 MPa.

Preferably, the copper-zinc wrought alloy may have an electrical conductivity of at least 12.5 Ms/m, preferably at least 12.7 MS/m, especially at least 13.0 MS/m.

The composition of alloys with a particularly advantageous combination of properties is as follows (in wt%): Cu: 58.5 to 59.0% Si: 0.04 to 0.09% P： 0.05 to 0.10% Pb: 0.04 to 0.08% Fe: optionally up to 0.10% Ni: Optionally up to 0.07% Sn: optionally up to 0.20% Al: optionally up to 0.05% The remainder is zinc and unavoidable impurities, of which the proportion of unavoidable impurities is less than 0.1 wt%. Through low proportions of alloying elements Si and P, an extremely high conductivity of at least 14 Ms/m, preferably at least 15 MS/m, is achieved. A Pb proportion of 0.04 to 0.08 wt% contributes to machinability.

The subject of the invention is also a wire-shaped, tubular or rod-shaped semi-finished product made of the aforementioned copper-zinc malleable alloy, and a component produced from such a semi-finished product by cutting and other optional processing steps.

Another aspect of the invention relates to a method of manufacturing a linear, tubular or rod-shaped semi-finished product. The method includes the following steps: a) Melt the copper alloy with the aforementioned composition, b) Continuously cast tubular or pin-shaped castings through water-cooled chilled molds, c) hot pressing the cast form at a temperature of 620 to 700°C and subsequent cooling at a cooling rate of 30 to 60°C per minute in a temperature range of 550 to 350°C, d) optionally, heat treatment in a temperature range of 525 to 625°C for 1 to 5 hours, followed by cooling in a temperature range of 500 to 350°C at a cooling rate of 20 to 40°C per minute, e) Optional cold forming.

To melt the alloy, Cu cathodes, Zn ingots, brass scrap, Cu-P master alloys and Cu-Si master alloys can be used. Melting is preferably carried out in an induction furnace. The melt is cast in a water-cooled chilled mold into a tubular or pin-shaped casting form.

Alternatively, the cast form can be milled and subsequently hot pressed at a temperature of 620 to 700°C. The hot-pressed intermediate product is then cooled at a cooling rate of 30 to 60°C per minute, preferably 40 to 50°C per minute, in a temperature range of 550 to 350°C. Through this defined cooling, a favorable proportion ratio of the α phase to the β phase and a favorable particle distribution of the copper- and/or zinc-containing phosphide are achieved. Prior to hot pressing, optionally, heat treatment may be performed to homogenize the cast product.

In a first manufacturing method, pickling can be carried out without further intermediate steps after hot pressing, and then cold forming can be carried out. In cold forming, the molding degree is preferably between 3 and 30%. Here, degree of molding refers to the relative reduction in the cross-sectional area of the product. There are no other working steps between hot pressing and cold forming except pickling operations, so the first manufacturing method is very convenient.

In the second manufacturing method, after hot pressing, heat treatment is performed at a temperature between 525 and 625°C, preferably between 550 and 600°C for 1 to 5 hours, and then at a temperature of 500 to 350°C. Cooling is performed within the temperature range at a cooling rate of 20 to 40°C per minute. By selecting the conditions of the heat treatment, in combination with a defined cooling after the heat treatment, a favorable proportion ratio of the α phase to the β phase and a favorable particle distribution of the copper- and/or zinc-containing phosphide can be achieved. If the purpose is to increase the proportion of β phase, heat treatment should be performed at about 600°C. If the purpose is to increase the proportion of α phase, heat treatment should be performed at about 550°C. Therefore, the proportion ratio of α phase to β phase and the particle distribution of phosphide can be adjusted and optimized through heat treatment. In particular, the ductility can be improved thereby. After the heat treatment, pickling and cold forming steps follow as in the first manufacturing method.

For other technical features and advantages of the method of the invention, reference is expressly made to the description made in connection with the copper-zinc wrought alloy of the invention and the embodiments.

The present invention will be described in detail with reference to examples.

Samples No. 1 to No. 44 were melted in an induction furnace and subsequently cast. The compositions of these samples are recorded in Tables 1 to 4. Sample No. 10 represents the lead-containing reference alloy CuZn39Pb3. The specimens were milled, homogenized for 1 hour, and then thermoformed. Samples No. 8 and 9 were thermoformed by pressing at 630°C, and the remaining samples were thermoformed by rolling at 650°C. During the cooling process after thermoforming, in the temperature range between 550 and 350°C, the cooling rate was approximately 40°C per minute for rolled specimens and about 40°C per minute for pressed specimens. About 30℃.

After hot forming, specimens No. 1 to No. 7 and No. 10 to No. 23 were milled and subsequently cold formed at a forming degree of 20%. After thermoforming, specimens No. 8 to No. 9 were pickled and subsequently cold formed at a molding degree of 7%.

After thermoforming, specimens No. 24 to No. 44 were annealed for 3 hours. For specimens No. 26, 27, and 38 to 41, the annealing temperature is approximately 550°C, while for specimens 24, 25, 28 to 37, and 42 to 44, the annealing temperature is approximately 550°C. The temperature is about 600°C. After annealing, cooling is performed at a cooling rate of approximately 25°C per minute in a temperature range between 500 and 350°C. Specimens No. 24 to No. 44 were subsequently milled and subsequently cold formed at a forming degree of 20%.

In the final state, the tensile strength R _m and the elongation at break A were measured based on the tensile test, and the hardness (Vickers hardness HV10) and electrical conductivity λ were measured. Longitudinal sections of the specimen were studied by optical microscopy. Based on this, the area fraction of the α phase and the β phase corresponding to the volume fraction and the α particle size are determined. To quantitatively determine the size distribution of phosphide particles, optical microscopy images of unetched specimens were used. Image segments with dimensions of 167 µm x 126 µm (corresponding to an area of 21000 µm ² ) were selected and evaluated with ImageJ at 1000x magnification. In this way, each particle can be detected and its equivalent diameter and its area can be determined. Phosphide particles are divided into categories based on their equivalent diameter: 0.5 to 1 µm, 1 to 2 µm, and greater than 2 µm.

The machinability is evaluated by drilling tests in the final state. Drilling tests are performed with an instrumented drill bit. Drilling tests were carried out with the following parameters: ● Auger drill, diameter 5 mm ● Speed 3200 rpm ● Feed rate 0.04 mm/rev ● Drill 5 holes for each specimen, using new drilling tools for each specimen ● Drilling depth 10 mm

Drill holes in the direction of the forming. Measure the torque and normal force acting on the cutting edge of the drilling tool. CuZn39Pb3 alloy in unannealed state is used as reference. The torque measured on each specimen is normalized by relating the torque measured on the reference alloy to the torque measured on each specimen. That is, the smaller the torque measured on the sample, the greater the normalized torque of the sample. Similarly, the measured normal force was normalized for each specimen. The arithmetic mean of these two quantities is calculated from the normalized torque M ^norm and the normalized normal force F _N ^norm . Specimens with an arithmetic mean value thus calculated below 0.75 do not meet the prerequisites for good machinability.

The chip shape is classified according to the information item i.18 of the document "Guidance Values for the Cutting of Copper and Copper Alloys (Richtwerte für die spanende Bearbeitung von Kupfer und Kupferlegierungen)" published by the German Copper Institute (Deutsches Kupferinstitut). Based on this, the chips were rated as good (2), medium (1), or poor (0). In this case, corrugated chips lead in particular to a negative evaluation.

The measured normalized torques and normal forces are listed in Tables 1 to 4, as well as the arithmetic mean calculated from them, called (M+F _N )/2 in the header, and are also listed Chip shape and characteristic values in tensile tests and hardness measurements. Sample number Cu Zn Si P Pb other elements α phase β phase alpha particle size Phosphide 0.5 - 1 µm Phosphide 1 - 2 µm Phosphide > 2 µm wt% wt% wt% wt% wt% wt% vol% vol% μm per 21000 µm ² per 21000 µm ² per 21000 µm ² 1 60.92 38.69 0.277 0.102 67 33 20 195 79 2 59.89 39.78 0.274 0.051 54 46 twenty four twenty one 10 3 59.98 39.61 0.298 0.102 62 38 18 45 37 1 4 59.68 39.79 0.272 0.133 0.118 61 39 15 102 41 1 5 59.82 39.59 0.284 0.104 Fe: 0.195 59 41 13 59 34 8 6 60.09 39.49 0.284 0.057 Mn: 0.068 62 38 20 55 12 7 60.59 38.85 0.269 0.154 0.125 67 33 twenty two 132 66 3 8 59.27 40.218 0.37 0.14 0.002 59 41 35 19 7 11 9 58.62 41.09 0.081 0.091 0.06 54 46 32 18 8 7 Table 1: Samples of the present invention, not annealed Sample number Cu Zn Si P Pb other elements hardness R _m A λ M ^{norm f} _N (M+F _N )/2 Chip shape wt% wt% wt% wt% wt% wt% HV10 MPa % MS/m - - - - 1 60.92 38.69 0.277 0.102 167 531 14.6 12.73 0.91 0.67 0.79 2 2 59.89 39.78 0.274 0.051 197 573 14 13.47 0.96 0.54 0.75 1 3 59.98 39.61 0.298 0.102 176 583 10.3 13.00 1.00 0.64 0.82 2 4 59.68 39.79 0.272 0.133 0.118 175 550 14.4 12.96 1.08 0.47 0.78 2 5 59.82 39.59 0.284 0.104 Fe: 0.195 174 561 14.9 13.62 0.91 0.65 0.78 1 6 60.09 39.49 0.284 0.057 Mn: 0.068 179 558 15.2 13.33 0.85 0.65 0.75 2 7 60.59 38.85 0.269 0.154 0.125 171 536 11.8 12.74 0.95 0.56 0.76 2 8 59.27 40.22 0.37 0.14 0.002 163 559 13.9 12.95 0.86 0.64 0.75 1-2 9 58.62 41.09 0.081 0.091 0.06 168 521 16.7 15.71 0.88 0.63 0.76 1-2 Table 1 (continued): Samples of the present invention, not annealed Sample number Cu Zn Si P Pb other elements α phase β phase alpha particle size Phosphide 0.5 - 1 µm Phosphide 1 - 2 µm Phosphide > 2 µm wt% wt% wt% wt% wt% wt% vol% vol% μm per 21000 µm ² per 21000 µm ² per 21000 µm ² 10 57.64 39.00 3.358 70 30 17 11 57.63 40.32 2.047 63 37 19 12 59.52 40.17 59 41 twenty one 13 60.85 38.87 0.269 65 35 twenty three 14 62.4 37.06 0.53 73 27 25 15 62.3 37.02 0.579 0.102 71 29 twenty two 94 103 2 16 58.96 41.03 62 38 16 17 59.85 39.87 0.272 60 40 17 18 59.98 39.36 0.269 0.383 63 35 12 128 103 47 19 58.75 41.13 0.109 63 37 25 76 82 2 20 61.33 38.03 0.552 0.075 62 38 twenty one 50 47 3 twenty one 59.93 39.53 0.272 0.056 Sn: 0.215 53 47 12 51 3 twenty two 58.79 40.91 0.294 73 27 11 33 27 6 twenty three 60.88 38.53 0.286 0.295 76 twenty four 15 385 74 3 Table 2: Comparative sample, not annealed Sample number Cu Zn Si P Pb other elements hardness R _m A λ M ^{norm f} _N (M+F _N )/2 Chip shape wt% wt% wt% wt% wt% wt% HV10 MPa % MS/m - - - - 10 57.64 39.00 3.358 161 489 15.8 16.29 1.00 1.00 1.00 2 11 57.63 40.32 2.047 155 501 21.8 16.9 1.14 0.61 0.88 2 12 59.52 40.17 156 492 22.3 16.78 0.34 0.54 0.44 0 13 60.85 38.87 0.269 173 525 20.4 13.58 0.95 0.62 0.79 0 14 62.4 37.06 0.53 174 538 16.2 11.4 0.83 0.44 0.64 0 15 62.3 37.02 0.579 0.102 174 560 10.6 10.7 0.91 0.62 0.77 1 16 58.96 41.03 161 515 25 17.28 0.77 0.37 0.57 0 17 59.85 39.87 0.272 179 556 twenty one 14 0.87 0.68 0.78 0 18 59.98 39.36 0.269 0.383 191 565 6.8 12.43 0.93 0.56 0.75 2 19 58.75 41.13 0.109 172 519 15.8 16.31 0.85 0.58 0.72 2 20 61.33 38.03 0.552 0.075 174 558 16.9 11.23 0.78 0.63 0.71 1-2 twenty one 59.93 39.53 0.272 0.056 Sn: 0.215 180 562 12 13.23 0.85 0.51 0.68 1 twenty two 58.79 40.91 0.294 174 527 12.1 15.74 0.85 0.37 0.61 1 twenty three 60.88 38.53 0.286 0.295 185 564 10.2 12.06 0.80 0.60 0.70 2 Table 2 (continued): Comparative sample, not annealed Sample number Cu Zn Si P Pb other elements α phase β phase alpha particle size Phosphide 0.5 - 1 µm Phosphide 1 - 2 µm Phosphide > 2 µm wt% wt% wt% wt% wt% wt% vol% vol% μm per 21000 µm ² per 21000 µm ² per 21000 µm ² twenty four 60.774 38.888 0.281 0.051 64 36 31 twenty two 15 0 25 60.922 38.69 0.277 0.102 69 31 39 twenty three 38 18 26 59.886 39.781 0.274 0.051 55 45 28 30 18 0 27 59.984 39.61 0.298 0.102 59 41 26 twenty three 32 15 28 59.684 39.787 0.272 0.133 0.118 62 38 33 48 30 18 29 59.82 39.59 0.284 0.104 Fe: 0.195 56 44 32 17 twenty one 9 30 60.09 39.49 0.284 0.057 Mn: 0.068 51 49 33 28 13 31 59.93 39.53 0.272 0.056 Sn: 0.215 54 46 32 38 17 Table 3: Samples of the present invention, annealed Sample number Cu Zn Si P Pb other elements hardness R _m A λ M ^{norm f} _N (M+F _N )/2 Chip shape wt% wt% wt% wt% wt% wt% HV10 MPa % MS/m - - - - twenty four 60.774 38.888 0.281 0.051 161 511 17.7 13.13 0.95 0.58 0.77 2 25 60.922 38.69 0.277 0.102 163 515 15.6 12.72 1.00 0.57 0.79 2 26 59.886 39.781 0.274 0.051 190 541 12.6 13.4 1.03 0.66 0.85 2 27 59.984 39.61 0.298 0.102 174 557 16.2 12.99 1.00 0.61 0.81 2 28 59.684 39.787 0.272 0.133 0.118 172 536 12.4 13.03 0.95 0.61 0.78 2 29 59.82 39.59 0.284 0.104 Fe: 0.195 170 551 18.1 13.66 0.79 0.71 0.75 1 30 60.09 39.49 0.284 0.057 Mn: 0.068 171 549 14.1 13.48 1.00 0.56 0.78 1 31 59.93 39.53 0.272 0.056 Sn: 0.215 163 551 11.6 13.2 0.93 0.62 0.78 2 Table 3 (continued): Samples of the present invention, annealed Sample number Cu Zn Si P Pb other elements α phase β phase alpha particle size Phosphide 0.5 - 1 µm Phosphide 1 - 2 µm Phosphide > 2 µm wt% wt% wt% wt% wt% wt% vol% vol% μm per 21000 µm ² per 21000 µm ² per 21000 µm ² 32 57.64 39.00 3.358 66 34 32 33 57.63 40.32 2.047 61 39 29 34 59.52 40.17 63 37 39 35 60.85 38.87 0.269 70 30 31 36 62.4 37.06 0.53 69 31 38 37 62.3 37.02 0.579 0.102 65 35 33 20 27 twenty four 38 58.96 41.03 66 34 19 39 59.85 39.87 0.272 59 41 twenty four 40 59.98 39.36 0.269 0.383 62 38 15 105 106 50 41 58.75 41.13 0.109 60 40 29 39 57 1 42 61.33 38.03 0.552 0.075 59 41 37 17 twenty four 7 43 58.79 40.91 0.294 63 37 twenty three 20 25 59 44 60.88 38.53 0.286 0.295 61 39 twenty one 73 47 48 Table 4: Comparative sample, annealed Sample number Cu Zn Si P Pb other elements hardness R _m A λ M ^{norm f} _N (M+F _N )/2 Chip shape wt% wt% wt% wt% wt% wt% HV10 MPa % MS/m - - - - 32 57.64 39.00 3.358 148 434 4.4 16.3 1.11 0.91 1.01 2 33 57.63 40.32 2.047 151 446 3.5 16.77 1.21 0.80 1.01 2 34 59.52 40.17 157 468 25.8 16.97 0.22 0.50 0.36 0 35 60.85 38.87 0.269 150 489 21.5 13.7 0.43 0.83 0.63 0 36 62.4 37.06 0.53 164 510 20.6 11.51 0.45 0.77 0.61 1 37 62.3 37.02 0.579 0.102 156 531 12.7 10.71 1.03 0.68 0.86 1 38 58.96 41.03 155 489 24.6 16.96 0.78 0.67 0.73 0 39 59.85 39.87 0.272 171 536 19 13.95 0.98 0.69 0.84 0 40 59.98 39.36 0.269 0.383 173 555 15 12.45 1.00 0.62 0.81 2 41 58.75 41.13 0.109 158 518 18 16.16 0.85 0.62 0.74 2 42 61.33 38.03 0.552 0.075 171 537 13.6 11.28 0.80 0.71 0.76 1 43 58.79 40.91 0.294 169 501 17.6 15.6 0.58 0.49 0.54 1 44 60.88 38.53 0.286 0.295 172 526 13.4 12.06 1.05 0.70 0.88 1-2 Table 4 (continued): Comparative sample, annealed

Samples No. 1 to No. 9 (Table 1) are samples of the present invention in an unannealed state. The volume fraction of the beta phase is at least 33% and at most 46%. The alpha particle size is a maximum of 24 µm for rolled specimens and a maximum of 35 µm for pressed specimens. The smaller α particle size of sample No. 5 can be attributed to the alloying element Fe. The hardness is at least 160 HV10 and the tensile strength R _m is at least 520 MPa. Elongation at break is at least 10%. The conductivity of all samples is at least 12.7 MS/m, and for several samples it is at least 13.0 MS/m. The conductivity of sample No. 9 is higher than 15.5 MS/m. The normalized torque is between 0.85 and 1.08. The normalized normal force is between 0.45 and 0.7. The arithmetic mean of the normalized torque and the normalized normal force is always at least 0.75. Chip shape was always rated as good (2) or fair (1).

Samples No. 10 to No. 23 (Table 2) are comparative samples in the unannealed state. Reference sample No. 10 contains 3.3 wt% lead and shows excellent cutting properties. Sample No. 11 containing 2.0 wt% lead also showed good cutting characteristics. Samples No. 12 and No. 16 show very poor cutting characteristics without the use of lead and other alloying elements.

In addition to Cu and Zn, samples No. 13 and No. 17 contain only 0.27 wt% Si.

The forces acting on the drill tool were within acceptable limits, but the chip shape was poor, which may be attributed to the lack of phosphide particles that act as chip breakers. Compared with sample No. 13, the Cu proportion and Si proportion of sample No. 14 have increased. The force acting on the drilling tool is not within the acceptable range, and the chip shape is poor. In addition, the electrical conductivity is lower.

Compared with sample No. 14, the Si proportion of sample No. 15 is slightly increased, and 0.1 wt% of P element is added. As a result, the forces acting on the drill tool are reduced and the chip shape is slightly improved. However, the elongation at break and electrical conductivity are low. Compared with sample No. 1, sample No. 15 has a higher Si proportion under similar P content and similar volume fraction of β phase. The force acting on the drill tool was equally good, but the chip shape of sample No. 15 was more unfavorable and less conductive.

The difference between sample No. 18 and sample No. 17 is 0.38 wt% P. This generally results in a significant improvement in chip shape. But the elongation at break is very low.

In addition to Cu and Zn, sample No. 19 contains only 0.11 wt% P. This helps with chip shape, but the force on the drill tool is unsatisfactory. Compared with sample No. 19, the P proportion of sample No. 22 increased to 0.29 wt%, causing the normal force to become worse.

The difference between sample No. 20 and sample No. 15 is generally the slightly reduced P ratio. This results in improved elongation at break. But the higher Si proportion makes the conductivity not at the desired level.

In addition to 0.27 wt% Si and 0.06 wt% P, sample No. 21 also contains 0.22 wt% Sn. Compared with the No. 2 sample that does not contain tin, the addition of tin element makes the force acting on the drilling tool worse. Almost exclusively phosphide particles with a diameter of 0.5 to 1 µm were observed. The conductivity is nearly unaffected by 0.22 wt% Sn.

Sample No. 23 contains 0.29 wt% Si and 0.30 wt% P. Although the chip shape was good as in specimen No. 18, the elongation at break, conductivity, and force acting during drilling were not satisfactory.

Samples No. 24 to No. 31 (Table 3) are samples of the present invention in an annealed state. Samples No. 26 and No. 27 were annealed at 550°C, while the other samples in Table 3 were annealed at 600°C. The volume fraction of the beta phase is at least 31% and at most 49%. The alpha particle size ranges between 25 and 40 µm, with samples No. 26 and No. 27 having the smallest particle sizes. The hardness is at least 160 HV10 and the tensile strength R _m is at least 510 MPa. Elongation at break is at least 11.5%. The conductivity of all samples is at least 12.7 MS/m, and for several samples it is at least 13.0 MS/m. The normalized torque is between 0.79 and 1.03. The normalized normal force is between 0.56 and 0.71. The arithmetic mean of the normalized torque and the normalized normal force is always at least 0.75. Chip shape was always rated as good (2) or fair (1). For specimen No. 31, which has the same composition as unannealed specimen No. 21, the forces acting during the drilling process and the chip shape can be significantly improved by annealing. In addition, it was found that annealing causes the center of gravity of the distribution of phosphide particles to shift toward larger particles.

Samples No. 32 to No. 44 (Table 4) are comparative samples in the annealed state. Lead-containing specimens No. 32 and No. 33 showed good cutting characteristics in the annealed state. Specimen No. 34 (annealed at 600°C) and Specimen No. 38 (annealed at 550°C) containing only Cu and Zn showed poor characteristics during drilling even in the annealed state.

Compared to the torque measured on the reference specimen No. 10, the silicon-containing but no phosphorus-free specimens No. 35 and No. 36 annealed at 600°C produced more than twice the torque. The larger Si proportion of sample No. 36 improves the chip shape but reduces the electrical conductivity. Compared with specimens No. 35 and 36, specimen No. 39 containing silicon but without phosphorus annealed at 550°C has a more favorable force during drilling. This can be attributed to the significantly improved proportion of β phase. But the chip shape is poor.

Sample No. 37 contained 0.58 wt% Si and 0.10 wt% P and was annealed at 600°C. During drilling, the properties of this sample were better than those of Sample No. 15 with the same composition in the unannealed state. More advantageous, but the larger Si proportion results in insufficient electrical conductivity.

For specimens No. 40 and 41, which are annealed at 550°C and have a composition equivalent to specimen No. 18 or 19, the forces acting on the drilling tool can be improved by annealing, and particularly in the case of specimen No. 40. Significantly improved ductility. However, the high proportion of Si and P makes the conductivity of sample No. 40 low. In the case of sample No. 41, the lack of Si cannot be compensated for by annealing to bring the forces during drilling to an acceptable level.

Sample No. 42, which contains a Si proportion of 0.55 wt% and a P proportion of 0.075 wt%, has an electrical conductivity that is too low due to this higher Si proportion.

For Samples No. 43 and No. 44, which are compositionally equivalent to the unannealed Samples No. 22 and No. 23, the ductility can be significantly improved by annealing at 600°C. After annealing, the cutting characteristics of specimen No. 43 were unsatisfactory. In the case of sample No. 44, the combination of a P proportion of 0.3 wt% and a Si proportion of 0.29 wt% resulted in low electrical conductivity.

Samples No. 1 to No. 44 show that through targeted selection of Si and P elements, alloys with a favorable combination of properties can be produced. Si reduces the force acting on the drilling tool and thereby improves the cutting characteristics. However, Si proportions higher than 0.32 wt% reduce the electrical conductivity. A P proportion of 0.05 to 0.2 wt% contributes to chip formation. The combination of higher proportions of P and Si results in poor ductility and conductivity. Alloys with a favorable combination of these properties can be produced without annealing. With certain element combinations, the cutting properties can subsequently be improved through targeted adjustment of the beta phase proportions and the phosphide particles through annealing, in particular at temperatures between 550° C. and 600° C.

Alloys with the aforementioned compositions can also be used as casting alloys for castings.

(without)

Claims (16)

A copper-zinc malleable alloy used for the manufacture of wire-shaped, tubular or rod-shaped semi-finished products, having the following composition in wt%: Cu: 58.0 to 63.0%, Si: 0.04 to 0.32%, P: 0.05 to 0.20%, Sn : optionally up to 0.25%, Al: optionally up to 0.10%, Fe: optionally up to 0.30%, Ni: optionally up to 0.30%, Pb: optionally up to 0.25%, Te, Se, In optionally 0.10% each, Bi: max. 0.009%, the balance is Zn and unavoidable impurities, where the proportion of unavoidable impurities is less than 0.2 wt%, where the weight ratio of P to Al is at least 1.0, where , the alloy has a structure composed of spherical α phase, β phase and phosphide particles, and the proportion of β phase in the sum of α phase and β phase is at least 20 vol% and at most 70 vol%, wherein Si Present in both ^the α and β phases, where there are 7 to 200 phosphide particles with an equivalent diameter of 0.5 to 1 µm and 4 to 150 phosphide particles with an equivalent diameter of 1 to 2 µm in an area of 21000 µm of phosphide particles, and a maximum of 30 phosphide particles with an equivalent diameter greater than 2 µm. The copper-zinc wrought alloy of claim 1 is characterized in that the proportion of Pb is at least 0.02 wt%. The copper-zinc wrought alloy according to one of claims 1 to 2, characterized in that the P proportion is at most 0.15 wt%. The copper-zinc wrought alloy according to one of claims 1 to 3, characterized in that the P/Fe ratio is at least 1.0. The copper-zinc wrought alloy of one of claims 1 to 4, characterized in that the Fe proportion is less than 0.10 wt% and the Ni proportion is at most 0.07 wt%. The copper-zinc wrought alloy according to one of claims 1 to 5, characterized in that the Si proportion is at least 0.23 wt%. The copper-zinc wrought alloy according to one of claims 1 to 5, characterized in that the Si proportion is at most 0.15 wt%. The copper-zinc wrought alloy of claim 7 is characterized in that the proportion of P is at most 0.10 wt%. The copper-zinc wrought alloy of claim 7 or 8 is characterized in that the Cu proportion is at most 59.5 wt%. The copper-zinc wrought alloy according to one of the preceding claims, characterized in that the sum of the proportions of the elements Cu, Zn, Si, P and Pb is at least 99.75 wt%. The copper-zinc wrought alloy according to one of the preceding claims, characterized in that the alloy has a hardness of at least 120 HV10, preferably at least 150 HV10. The copper-zinc wrought alloy according to one of the preceding claims, characterized in that the alloy has a tensile strength R _m of at least 500 MPa, preferably at least 530 MPa. The copper-zinc wrought alloy according to one of the preceding claims, characterized in that the alloy has an electrical conductivity of at least 12.5 MS/m. A wire-shaped, tubular or rod-shaped semi-finished product composed of a copper-zinc malleable alloy according to one of the preceding claims. A component made from the semi-finished product of claim 14 by cutting and optionally other processing steps. A method of manufacturing a linear, tubular or rod-shaped semi-finished product as claimed in claim 14, wherein the method includes the following steps: a) Melting a copper alloy having the composition of one of claims 1 to 10, b) Continuously cast tubular or pin-shaped castings through water-cooled chilled molds, c) hot pressing the cast form at a temperature of 620 to 700°C and subsequent cooling at a cooling rate of 30 to 60°C per minute in a temperature range of 550 to 350°C, d) optionally, heat treatment in a temperature range of 525 to 625°C for 1 to 5 hours, followed by cooling in a temperature range of 500 to 350°C at a cooling rate of 20 to 40°C per minute, e) Optional cold forming.