Material made of a copper-zinc-silicon alloy and method for manufacturing a component

Abstract

The invention relates to a material made of a copper-zinc-silicon alloy with the following composition: The remaining Zn and unavoidable impurities, wherein the material has a microstructure consisting essentially of α-phase, optional β-phase, optional γ-phase and phosphide particles embedded in the phases, and wherein the proportions of the β-phase and the γ-phase as well as the proportions of Si and P are chosen such that the material meets the condition 185.092 − 5.72328 ⋅ ( [ Beta ] + [ Gamma ] ) − 89.087 ⋅ [ Si ] − 354.137 ⋅ [ P ] + 2.8045 ⋅ ( [ Beta ] + [ Gamma ] ) ⋅ [ Si ] + 236.598 ⋅ [ Si ] ⋅ [ P ] < 60 The invention fulfills the requirements, where [Beta] denotes the proportion of the β-phase in vol.%, [Gamma] the proportion of the γ-phase in vol.%, [Si] the proportion of silicon in wt.%, and [P] the proportion of phosphorus in wt.%. The invention further relates to a method for manufacturing a component from a copper-zinc-silicon alloy.

Description

[0001] The invention relates to a material made of a copper-zinc-silicon alloy for the production of media-carrying components and to a method for the production of a media-carrying component made of a material made of a copper-zinc-silicon alloy.

[0002] Components carrying media, such as fittings, screw connections, and valves, are frequently manufactured from brass semi-finished products using machining processes. To produce these semi-finished products, the alloy is cast, the casting is hot-pressed, and then cold-formed. In the past, the machinability of the resulting material was ensured by adding approximately 2 to 4 wt% lead to the alloy. CuZn36Pb2As is one example of such a material. Lead acts as a grain refiner, reduces ductility, breaks chips, and improves lubrication by forming thin parting lines. CuZn36Pb2As is dezincification-resistant according to ISO 6509. This good dezincification resistance is attributed to the fact that the α-phase of the material is inhibited by arsenic, while the dezincification-prone β-phase is removed by appropriate heat treatment (annealing) during the manufacturing process.

[0003] Lead (Pb) is harmful to health and the environment. Therefore, many countries have continuously reduced the limits for lead in copper alloys, and the replacement of lead-containing brass with lead-free, machinable copper alloys is being pursued. Limits are specified within the framework of EU directives, such as RoHS (Directive 2011 / 65 / EU), which sets an upper limit of 1000 ppm (0.1 wt%) of Pb. Due to such regulatory requirements, there is a need for dezincification-resistant and easily machinable copper alloys with reduced lead content for components that carry media, especially drinking water.

[0004] As a lead-reduced, dezincification-resistant alternative, CuZn38As (CW511L) already exists with a lead content of up to 0.2 wt.%. Due to the low lead content, the alloy is difficult to machine. Corrosion tests also show that the lead leachability of CuZn38As in drinking water only remains below the limit of 5 µg / l if the lead content of the alloy is less than 0.10 wt.%.

[0005] To ensure good machinability of the material even with lead contents of less than 0.1 wt.%, various alloying elements are proposed as an alternative to lead.

[0006] Numerous publications describe the use of bismuth (Bi) as an alternative to lead to improve machinability. To mitigate the problem of Bi film formation along grain boundaries and the associated susceptibility to stress and hot cracking, the addition of other elements is proposed. In this regard, particular reference is made to publications KR 10 0 555 854 B1, KR 10 2006 096 877 A, and JP 2005 290 475 A.

[0007] References are made to JP 2014 122 427 A and JP 2006 083 443 A. Nevertheless, bi is undesirable because, firstly, it is a metal that is only available in limited quantities and, secondly, it leads to hot brittleness within the material cycles of copper alloys.

[0008] US patent 9,951,400 B1 discloses a copper-zinc-silicon alloy with 66 to 69 wt.% Cu, 1.53 to 2.0 wt.% Si, and the balance zinc. The alloy may also contain small amounts of Pb, P, Fe, Sn, Al, Ni, Co, As, Sb, Bi, Se, and S. The alloy typically contains at least 3 vol.% of non-α-phase components. This results in good machinability. Conversely, alloy compositions with a very low non-α-phase content exhibit poor machinability. The high ductility of the α-phase prevents chip breakage, leading to undesirably long chips. Satisfactory machinability can only be achieved with alloy compositions containing a significant volume fraction of non-α-phase components. However, due to the significant volume fraction of non-α-phase, such alloy examples exhibit suboptimal resistance to dezincification.Patent US 9,951,400 B1 does not provide any teaching on how to provide an alloy that exhibits both excellent resistance to dezincification and excellent machinability.

[0009] Some copper-zinc-silicon alloys exhibit corrosion when exposed to warm water with a high bicarbonate concentration. Therefore, a test with circulating warm water is performed on copper-zinc-silicon alloys used in the manufacture of components that carry fluids, as an additional criterion for corrosion resistance. This test uses water with a high Ks4.3 value, i.e., a high bicarbonate concentration.

[0010] The invention is therefore based on the objective of providing a material that exhibits both excellent resistance to dezincification and corrosion in circulating hot water with a high bicarbonate concentration, as well as excellent machinability despite a lead content limited to a maximum of 0.10 wt.%. The material is considered dezincification-resistant if, in a dezincification test according to DIN EN ISO 6509-1, it suffers a dezincification attack of less than 100 µm depth, preferably less than 50 µm depth. Furthermore, the material must be readily cold-formable and, at least in an intermediate state, also readily hot-formable. The invention is also based on the objective of providing a method for manufacturing a dezincification- and corrosion-resistant component.

[0011] The invention is described with respect to a material by the features of claim 1 and with respect to a manufacturing process by the features of claim 10. The further referenced claims relate to advantageous embodiments and further developments of the invention.

[0012] A first aspect of the invention relates to a material made of a copper-zinc-silicon alloy with the following composition: Cu: 67.0 to 72.0 wt.%, Yes: 1.20 to 1.80 wt.%, Sn: 0.08 to 0.40 wt.%, P: 0.05 to 0.30 wt.%, Pb: optionally up to 0.10 wt.%, Fe: optionally up to 0.20 wt.%, Al: optionally up to 0.10 wt.%, Sb: optionally up to 0.10 wt.%, As: optionally up to 0.10 wt.%,

[0013] The remaining Zn and unavoidable impurities. The material has a microstructure consisting essentially of an α-phase, an optional β-phase, an optional γ-phase, and phosphide particles embedded in the phases. Within the scope of the invention, the fact that the microstructure "consists essentially of an α-phase, an optional β-phase, an optional γ-phase, and phosphide particles embedded in the phases" means that, in addition to the aforementioned components, the microstructure may contain further components that have formed due to unavoidable impurities or due to optional elements. Preferably, the proportion of these further components is less than 1 vol.%, more preferably less than 0.5 vol.%, and particularly less than 0.3 vol.% of the microstructure. The proportions of the β-phase and the γ-phase, as well as the proportions of Si and P, are selected such that the material meets condition (H). 185.092−5.72328⋅([Beta]+[Gamma])−89.087⋅[Si]−354.137⋅[P]+2.8045⋅([Beta]+[Gamma])⋅[Si]+236.598⋅[Si]⋅[P]<60 fulfilled, where [Beta] denotes the proportion of the β-phase in vol.%, [Gamma] the proportion of the γ-phase in vol.%, [Si] the proportion of silicon in wt.% and [P] the proportion of phosphorus in wt.%.

[0014] In light of the problem at hand, the invention is based on the premise that while an increasing volume fraction of the α-phase improves the dezincification resistance of the material, it also impairs its machinability. Phases that improve machinability in copper-zinc alloys, such as the β-phase or the γ-phase, increase the risk of dezincification and corrosion. Therefore, the lead used to improve machinability cannot simply be compensated for by increasing the proportions of the β-phase and γ-phase.

[0015] The invention proposes the targeted addition of silicon (Si) and phosphorus (P). Silicon strengthens the α-phase. This improves machinability by reducing the cold-forming capacity of the α-phase. Surprisingly, with increasing Si content, the proportions of β-phase or γ-phase can be compensated for, so that even with very low proportions of β-phase or γ-phase, sufficiently good machinability is achieved. Phosphorus improves dezincification resistance and forms phosphides with copper (and also with zinc), which promote chip breakage. The phosphides are particles that act as interfaces during machining, thus promoting chip breakage. Si facilitates the formation of shear bands. This is advantageous for machining, as these enable the formation of shear chips. Silicon and phosphorus thus condition the ductile and therefore unfavorable α-phase in such a way that it is readily machinable. If the phosphorus content is below 0.05 wt.If the phosphorus content is below -%, not enough phosphides are formed. A phosphorus content above 0.30 wt% leads to cracking during hot forming.

[0016] The machinability of the material is determined by the combined selection of the parameters β-phase, γ-phase, Si, and P. For good machinability, the volume fractions of the β-phase ([Beta]) and the γ-phase ([Gamma]], as well as the weight fractions of Si ([Si]) and P ([P]), are chosen such that the alloy fulfills the condition H < 60, where the value H is defined as follows: H=185.092−5.72328⋅([Beta]+[Gamma])−89.087⋅[Si]−354.137⋅[P]+2.8045⋅([Beta]+[Gamma])⋅[Si]+236.598⋅[Si]⋅[P]

[0017] This relationship quantitatively describes the influence of the parameters β-phase, γ-phase, silicon content, and phosphorus content on the machinability of the material, as well as the interaction of these parameters with each other. For example, a low volume fraction of β-phase and γ-phase can be compensated for by a higher weight fraction of silicon within the specification of the alloy composition, and vice versa.

[0018] Furthermore, the presence of no or only small proportions of β- and γ-phases is beneficial for the ductility of the material.

[0019] Furthermore, it is shown that materials made of CuZnSiP alloys with a Cu content of at least 67.0 wt.%, a Si content of at least 1.20 wt.%, and a P content of at least 0.05 wt.% are dezincification-resistant according to DIN EN 1264, even in the presence of β- or γ-phases, with a maximum dezincification depth of 100 µm, which is determined according to EN ISO 6509-1. Thus, within the scope of the first aspect of the invention, the dezincification resistance of the proposed material is ensured by its composition, namely by the minimum amounts of Cu, Si, and P.

[0020] Tin improves the corrosion resistance of materials in circulating hot water. The addition of tin (Sn) forms a better, and especially denser, protective layer on the material's surface. Tin has the property of accumulating on the surface, where it exists as an oxide. Generally, an alloying element leads to a compact oxide layer if the Pilling-Bedworth criterion is met, namely, "the density of the element's oxide is less than the density of the element, and the oxide is not porous." Tin fulfills this criterion. Silicon also fulfills the Pilling-Bedworth criterion and can form a dense silicate protective layer. However, silicate is attacked by carbonic acid. Tin oxide improves the compactness of the protective layer and thus prevents corrosion by carbonic acid. This improves corrosion resistance in hot water with a high bicarbonate concentration.At a tin content of less than 0.08 wt.%, the inhibitory effect is too weak. At a tin content of more than 0.40 wt.%, further phases form in the microstructure, which can adversely affect dezincification resistance.

[0021] The alloy contains up to 0.10 wt% lead. Lead has a positive effect on machinability, but its proportion in the alloy is limited by regulations.

[0022] The optional presence of iron in the alloy results in a finer grain structure in the as-cast condition. This improves hot formability. The grain refinement is also present in the final state of the material, which has a positive effect on dezincification resistance. Preferably, at least 0.05 wt.% iron can be present in the alloy. If the amount of iron is too high, iron phosphides are formed, resulting in a lack of phosphorus, which acts as a dezincification inhibitor and is necessary for the formation of chip-breaking (Cu,Zn) phosphides. Fe-P compounds are less machinable than the (Cu,Zn)-P compounds that would otherwise form. Therefore, the proportion of iron is limited to 0.20 wt.%, preferably to 0.12 wt.%.

[0023] The alloy may optionally contain up to 0.10 wt% aluminum, preferably up to 0.05 wt% aluminum. Aluminum forms aluminum phosphides with phosphorus, which are undesirable. Therefore, the proportion of aluminum must not exceed 0.10 wt%, preferably not more than 0.05 wt%.

[0024] The alloy can optionally contain up to 0.10 wt% antimony and up to 0.10 wt% arsenic. The antimony and arsenic further improve dezincification resistance. Thus, the dezincification-inhibiting effect of phosphorus can be enhanced by arsenic and antimony.

[0025] The material can be in the form of a wrought material or a cast material.

[0026] The advantage of the proposed material lies in its ability to solve all three problems of the given task: The material is in a state where it exhibits (i) excellent resistance to dezincification due to its minimum Cu, Si, and P content, (ii) very good resistance to corrosion in circulating, hydrogen carbonate-containing warm water due to its Sn content, and (iii) excellent machinability despite a Pb content limited to a maximum of 0.10 wt.% due to the "H < 60" criterion. This combination of properties is achieved through the precise selection of the elements Cu, Si, P, and Sn, as well as through the specifically tailored microstructure. The material requires no further treatment to meet the requirements for use in components carrying fluids.

[0027] In one embodiment of the invention, the proportion of the γ-phase in the microstructure of the material can be at most 5 vol.%, preferably at most 2 vol.%. Limiting the proportion of the γ-phase improves corrosion resistance in circulating hot water, especially in hard hot water, i.e., water with a high concentration of bicarbonate.

[0028] In a further embodiment of the invention, the copper content can be at least 68.0 wt.%, preferably at least 69.5 wt.%, and at most 71.5 wt.%, preferably at most 71.0 wt.%. With a copper content of at least 68.0 wt.%, the material is particularly resistant to dezincification. Limiting the copper content to a maximum of 71.5% results in an alloy that is particularly easy to machine.

[0029] In a further embodiment of the invention, the silicon content can be at least 1.30 wt.%, preferably at least 1.40 wt.%, and at most 1.70 wt.%, preferably at most 1.60 wt.%. With a silicon content of at least 1.30 wt.%, the material is particularly resistant to dezincification. With a silicon content of at least 1.40 wt.%, neither a β-phase nor a γ-phase is required to achieve sufficiently good machinability.

[0030] In a further embodiment of the invention, the tin content can be at least 0.15 wt.%, preferably at least 0.20 wt.%, and at most 0.35 wt.%, preferably at most 0.30 wt.%. With a tin content of at least 0.15 wt.%, corrosion resistance in circulating hot water is achieved particularly reliably. Limiting the tin content to a maximum of 0.35 wt.% inhibits the formation of undesirable phases in the microstructure of the material.

[0031] In a further embodiment of the invention, the phosphorus content can be at least 0.07 wt.%, preferably at least 0.10 wt.%, and at most 0.25 wt.%, preferably at most 0.20 wt.%, and particularly preferably at most 0.15 wt.%. With a phosphorus content of at least 0.07 wt.%, the alloy is highly resistant to dezincification even without arsenic and antimony. With a phosphorus content of at most 0.20 wt.%, the alloy can be hot-formed without difficulty. Particularly preferably, the phosphorus content is at least 0.10 wt.% and at most 0.14 wt.%.

[0032] In a further advantageous embodiment of the invention, the lead content can be at least 0.03 wt.%. Even a lead content of 0.03 wt.% improves the machinability of the material.

[0033] The material described above can be supplied as a wrought material in the form of wire, tube, rod, or profile semi-finished products. To produce such a semi-finished product, the copper-zinc-silicon alloy is melted and, preferably by continuous casting, cast into a finished product. After casting, heat treatment can optionally be carried out to homogenize the material. The cast product is then hot-formed, for example, by extrusion. After hot-forming, a heat treatment at 400 °C to 580 °C for 1 to 10 hours can optionally be performed. Cold forming steps, particularly drawing processes, bring the material to its final dimensions in the desired semi-finished product shape.

[0034] The material described above can be used to manufacture a fluid-carrying component by machining. In particular, the material can be used in the form of a semi-finished product as described above. Alternatively, the material can be used in its as-cast state, resulting in a cast component. Due to its special chemical composition, the material is resistant to dezincification and corrosion in circulating hot water even without further treatment, especially without subsequent heat treatment.

[0035] Regarding further technical features and advantages of the material according to the invention, explicit reference is hereby made to the explanations in connection with the exemplary embodiments and comparative examples.

[0036] Another aspect of the invention relates to a method for manufacturing a component from a copper-zinc-silicon alloy. The method comprises the following steps: a) Melting a copper-zinc-silicon alloy and casting a cast product from a copper-zinc-silicon alloy with the following composition: Cu: 64.0 to 72.0 wt.%, Yes: 0.40 to 1.80 wt.%, Sn: 0.08 to 0.40 wt.%, P: 0.05 to 0.30 wt.%, Pb: optionally up to 0.10 wt.%, Fe: optionally up to 0.20 wt.%, Al: optionally up to 0.10 wt.%, preferably up to 0.05 wt.%, Sb: optionally up to 0.10 wt.%, As: optionally up to 0.10 wt.%, Residual Zn and unavoidable impurities, b) optional heat treatment of the cast product, c) optional hot forming of the cast product and optional further forming steps, d) obtaining a material having a microstructure consisting essentially of α-phase, optional β-phase, optional γ-phase and phosphide particles embedded in the phases, wherein the proportions of the β-phase and the γ-phase and the proportions of Si and P are chosen such that the material satisfies condition (H) 185.092−5.72328⋅([Beta]+[Gamma])−89.087⋅[Si]−354.137⋅[P]+2.8045⋅([Beta]+[Gamma])⋅[Si]+236.598⋅[Si]⋅[P]<60 fulfilled, where [Beta] denotes the proportion of the β-phase in vol.%, [Gamma] the proportion of the γ-phase in vol.%, [Si] the proportion of silicon in wt.% and [P] the proportion of phosphorus in wt.%, e) Machining of the material to obtain a component, f) Heat treatment of the component so that the proportion of the β-phase in the microstructure of the material is at most 4 vol.% and the proportion of the γ-phase in the microstructure of the material is at most 5 vol.%.

[0037] Within the scope of the invention, the fact that the microstructure of the material "consists essentially of an α-phase, an optional β-phase, an optional γ-phase, and phosphide particles embedded in the phases" means that, in addition to the aforementioned components, the microstructure may contain further components that form due to unavoidable impurities or due to optional elements. Preferably, the proportion of these further components is less than 1 vol.%, more preferably less than 0.5 vol.%, and particularly less than 0.3 vol.% of the microstructure.

[0038] The material can be in the form of a wrought material or a cast material in step e).

[0039] As described above in connection with the material according to the invention, the machinability of the material is ensured in the proposed method by selecting the proportions of the β-phase and the γ-phase as well as the proportions of Si and P such that the material immediately before process step e) fulfills the condition “H < 60”, where the value H is defined as follows: H=185.092−5.72328⋅([Beta]+[Gamma])−89.087⋅[Si]−354.137⋅[P]+2.8045⋅([Beta]+[Gamma])⋅[Si]+236.598⋅[Si]⋅[P]

[0040] This relationship quantitatively describes the influence of the parameters β-phase, γ-phase, silicon content, and phosphorus content on the machinability of the material, as well as the interaction of these parameters with each other. For example, a low proportion of β-phase and γ-phase can be compensated for by a higher proportion of silicon within the specification of the alloy composition, and vice versa.

[0041] Within the scope of this further aspect of the invention, the dezincification resistance of the material in its final state, and thus the dezincification resistance of the component, is ensured by the heat treatment of the component in step f). The heat treatment converts the β-phase into the dezincification-resistant α-phase. The heat treatment is carried out such that the proportion of the β-phase in the microstructure of the material is at most 4 vol.%, preferably at most 2 vol.%. The heat treatment is preferably carried out in a temperature range between 350 °C and 500 °C for a duration of 1 to 12 hours, particularly preferably between 420 °C and 480 °C for a duration of 3 to 12 hours.

[0042] Corrosion resistance in circulating hot water is achieved by a tin content of at least 0.08 wt.% and by limiting the proportion of the γ-phase in the microstructure to a maximum of 5 vol.%. Preferably, the proportion of the γ-phase in the microstructure is a maximum of 4 vol.%, and particularly preferably a maximum of 2 vol.%.

[0043] The advantage of the proposed manufacturing process is that the material's dezincification resistance is adjusted only after machining. Therefore, the material used for machining in step e) does not necessarily need to be in a dezincification-resistant state, while the material in the final state, i.e., after step f), no longer needs to be easily machinable. This subsequent adjustment of the dezincification resistance thus allows the alloy composition and the microstructure constituents to be selected within a very wide range before machining. More degrees of freedom are available than in the first aspect of the invention described above. In particular, these parameters can be adjusted so that the material exhibits optimal machinability at low metal costs.The proportions of copper and silicon can be selected within a wider range than in the material according to the first aspect of the invention.

[0044] Preferably, within the scope of this further aspect of the invention, the Cu content of the copper-zinc-silicon alloy can be at least 64.5 wt.%, particularly preferably at least 65.0 wt.% and at most 69.0 wt.%, particularly preferably at most 68.5 wt.%.

[0045] Furthermore, within the scope of this further aspect of the invention, the Si content of the copper-zinc-silicon alloy can preferably be at least 0.50 wt.%, particularly preferably at least 0.55 wt.%, and at most 0.95 wt.%, particularly preferably at most 0.90 wt.%.

[0046] Preferably, the material meets the condition 0.36<([Zn]+10⋅[Si]+2.3⋅[Sn]) / ([Cu]+[Zn]+10⋅[Si]+2.3⋅[Sn])<0.39 where [Cu] denotes the proportion of Cu in wt.%, [Zn] the proportion of Zn in wt.%, [Si] the proportion of silicon in wt.%, [Sn] the proportion of Sn in wt.%. The term ([Zn]+10·[Si]+2.3·[Sn]) / ([Cu]+[Zn]+10·[Si]+2.3·[Sn]) is referred to in this invention as the zinc equivalent Zn eq This is indicated if the zinc equivalent is 0.36 or less, then the material is not sufficiently machinable.

[0047] If the zinc equivalent is 0.39 or greater, then the desired upper limit of the β-phase cannot be reliably maintained during the heat treatment in step f). In other words, the material cannot then be annealed to be "β-free".

[0048] In one embodiment of the invention, the copper content of the copper-zinc-silicon alloy can be at least 64.5 wt.%, preferably at least 65.0 wt.% and at most 66.5 wt.%, preferably at most 66.0 wt.%, and the silicon content can be at least 0.50 wt.%, preferably at least 0.55 wt.% and at most 0.70 wt.%, preferably at most 0.65 wt.%. This ensures that the maximum value of the β-phase is reliably achieved in step f) while simultaneously providing very favorable machining properties in step e).

[0049] In an alternative embodiment of the invention, the copper content of the copper-zinc-silicon alloy can be at least 67.0 wt.%, preferably at least 67.5 wt.% and at most 69.0 wt.%, preferably at most 68.5 wt.%, and the silicon content can be at least 0.75 wt.%, preferably at least 0.80 wt.% and at most 0.95 wt.%, preferably at most 0.90 wt.%. This ensures that the maximum value of the β-phase is reliably achieved in step f) while simultaneously providing very favorable machining properties in step e).

[0050] In a further embodiment of the invention, the tin content can be at least 0.15 wt.%, preferably at least 0.20 wt.%, and at most 0.35 wt.%, preferably at most 0.30 wt.%. With a tin content of at least 0.15 wt.%, corrosion resistance in circulating hot water is achieved particularly reliably. Limiting the tin content to a maximum of 0.35 wt.% inhibits the formation of undesirable phases in the microstructure of the material.

[0051] In a further embodiment of the invention, the phosphorus content can be at least 0.07 wt.%, preferably at least 0.10 wt.%, and at most 0.25 wt.%, preferably at most 0.20 wt.%, and particularly preferably at most 0.15 wt.%. With a phosphorus content of at least 0.07 wt.%, the alloy is highly resistant to dezincification even without arsenic and antimony. With a phosphorus content of at most 0.25 wt.%, the alloy can be hot-formed without difficulty. Particularly preferably, the phosphorus content is at least 0.10 wt.% and at most 0.14 wt.%.

[0052] In a further advantageous embodiment of the invention, the lead content can be at least 0.03 wt.%. A lead content of at least 0.03 wt.% improves the machinability of the alloy.

[0053] With regard to the optional alloying elements Fe, Al, Sb, and As and their technical effects, explicit reference is made hereto to the explanations relating to the copper-zinc-silicon alloy material described above, as described in the first aspect of the invention. The statements made therein can be applied to the copper-zinc-silicon alloy used in the aforementioned process for manufacturing a component according to the further aspect of the invention.

[0054] Regarding further technical features and advantages of the manufacturing process according to the invention, explicit reference is hereby made to the explanations in connection with the exemplary embodiments and comparative examples.

[0055] The invention is explained in more detail using exemplary embodiments and comparative examples.

[0056] Samples 1 to 31 were melted in an induction furnace and then cast. The composition of the samples is documented in Tables 1 and 2. Sample 30 represents the lead-containing reference alloy CuZn36Pb2As. Sample 31 represents the lead-reduced alloy CuZn38As (CW511L) with a lead content of 0.2 wt.%. The remaining samples each have a lead content of less than 0.1 wt.%.

[0057] Samples No. 1 to No. 10 and No. 19 to No. 31 were milled after casting, homogenized for 1 hour, and then hot-rolled at 800 °C. After hot-rolling, samples No. 10, No. 10, and No. 31 were milled and then cold-formed with a degree of deformation of 20%. Sample No. 2, which is identical in composition to Sample No. 1, as well as Samples No. 10, No. 30, and No. 31, were annealed at 550 °C for 8 hours after hot-forming and before cold-forming. Samples No. 11 to No. 16 were hot-formed by extrusion at 690 °C to 730 °C. After hot-forming, Samples No. 11 to No. 16 were annealed at 520 °C for 4 hours. Samples 11 to 16 were then pickled and subsequently cold-formed with a degree of deformation of 8%. Sample 16 was then annealed at 750 °C for 2 hours.

[0058] Samples No. 3 to No. 9 were divided after cold forming, and a portion of the samples were additionally annealed at 450 °C for 8 hours – in accordance with process step f) of the manufacturing process described above – to reduce the proportion of the β-phase. These samples in the "post-annealed" state are documented in Table 2 as samples No. 19 to No. 25 (in the same order as samples No. 3 to No. 9).

[0059] At the final state, the yield strength R was determined in each case. p0.2 , the tensile strength R m The elongation at break was determined from the tensile test, as was the electrical conductivity. Longitudinal sections of the samples were examined using light microscopy. The surface area fractions of the α-phase, β-phase, γ-phase, and phosphide particles corresponding to their volume fractions, as well as the grain size of the α-phase, were then determined.

[0060] The dezincification resistance of the samples was determined according to EN ISO 6509-1. The maximum depth of dezincification attack is given as a measure of dezincification resistance.

[0061] Machinability was determined by a planing test. An indexable insert with a contour that promotes chip breakage was used. The depth of cut was 125 µm and the planing speed was 35 m / min. Ten planing operations were performed. During the planing operations, the bending moment acting on the tool was measured, and the mean bending moment was calculated. The resulting chips were visually assessed and categorized according to their chip shape. A chip shape number was assigned to each chip shape according to the following list: Chip form number Chip form 0 Tear chip, spiral chip 0,5 Rolled chip with 1 to 2 turns 0,75 Rolled chip with an arc that includes an angle of 270° to 360° 1 Rolled chip with an arc that includes an angle of 180° to 270° 1,25 Rolled chip with an arc that encloses an angle of less than 180°

[0062] The corrosion susceptibility of the samples in circulating hot water was investigated in a test rig. For this purpose, hollow test specimens were turned and drilled from the samples to be tested in their final state. The test specimens were continuously subjected to a flow of 60 °C hot water at flow velocities of 0.5 m / s and 2.5 m / s in the test rig. The local drinking water used for testing was analyzed on December 20, 2023, and contained the following water constituents: Bicarbonate: 352 mg / l (5.68 mmol / l) Chloride: 25.8 mg / l Sulfate: 17.3 mg / l

[0063] The test specimens were removed after four weeks of flow exposure, and metallographic sections were prepared through the inner surface. The microstructure on the inner surface of the test specimens was examined using a light microscope, and the maximum corrosion attack was determined.

[0064] The results of the investigations are documented in Tables 1 and 2. Samples Nos. 2, 11, 12, and 14 (Table 1) and Nos. 19, 20, and 25 (Table 2) are samples according to the invention. Samples Nos. 1, 3 to 10, 13, 15, and 16 (Table 1) and Nos. 21 to 24, 30, and 31 (Table 2) are reference samples and are marked with an asterisk (*).

[0065] To assess the machinability of the samples, the bending moment determined during planing and the shape of the chips were used. A mean bending moment of no more than 60 Nm was considered very favorable. The tables also show the value H for each sample, which is calculated according to the formula described above from the proportions of Si and P in wt.% and the proportions of β-phase and γ-phase in vol.%. A qualitative correlation between the measured bending moment during the planing test and the value of H can be observed. Table 1 Sample No. Cu Zn Si P Pb Fe Sn As α-phase β-phase γ-phase Phosphide particles α-grain size % by weight % by weight % by weight % by weight % by weight % by weight % by weight % by weight Vol. Vol. Vol. Vol. µm 1 (*) 70,622 27,615 1,441 0,090 0,000 0,004 0,226 92 1 6 1 58 2 70,622 27,615 1,441 0,090 0,000 0,004 0,226 95 0 3 2 51 3 (*) 67,773 31,018 0,858 0,124 0,001 0,213 88 6 4 2 31 4 (*) 65,648 33,431 0,571 0,132 0 0,211 86 12 0 2 25 5 (*) 66,904 31,635 1,075 0,086 0,096 0,197 88 10 0 2 24 6 (*) 63,648 35,462 0,563 0,106 0,002 0,215 82 16 0 2 17 7 (*) 66,051 33,357 0,280 0,096 0,002 0,211 93 6 0 1 33 8 (*) 63,339 36,341 0,000 0,098 0,002 0,216 86 12 0 2 30 9 (*) 65,419 33,538 0,564 0,240 0,0008 0,235 86 11 0 3 22 10 (*) 70,262 28,046 1,566 0,109 0,000 0,004 0,010 99 0 0 1 47 11 70,08 27,928 1,56 0,110 0,058 0,004 0,26 97 0 2 1 33 12 70,97 27,086 1,45 0,099 0,060 0,065 0,27 99 0 0 1 32 13 (*) 70,75 27,673 1,29 0,120 0,067 0,098 0,002 99 0 0 1 18 14 70,76 27,131 1,55 0,110 0,067 0,092 0,29 95 0 4 1 26 15 (*) 69,72 28,525 1,5 0,100 0,068 0,086 0,001 98 0 0 2 30 16 (*) 70,1 28,003 1,47 0,110 0,062 0,005 0,25 88 1 10 <1 45 Sample No. longitudinal dezincification Dezincification across Rp 0.2 R m Elongation at break electrical conductivity Bending moment Chip form number H µm µm MPa MPa % MS / m Nm - - 1 (*) 20 14 420 488 13,4 6,77 35,8 1,25 43,8 2 26 17 390 494 38,5 6,86 44,0 0,5 50,5 3 (*) 282 286 391 476 18 8,32 41,1 1 56,7 4 (*) 246 217 393 484 24 9,74 58,6 0,75 55,8 5 (*) 260 449 394 491 23 10 40,6 0,75 53,7 6 (*) 261 510 411 506 16 10,1 39,3 0,75 45,2 7 (*) 302 248 344 431 32 11,3 109,6 0 102,9 8 (*) 320 287 363 443 23 14 104,8 0 81,7 9 (*) 274 231 400 486 19 9,22 42,0 1 36,3 10 (*) 31 15 408 509 36,2 6,71 45,1 0,75 47,4 11 56 52 234 412 46,5 6,83 50,9 1,15 45,1 12 64 28 238 429 57,9 6,99 54,2 1 54,8 13 (*) 30 25 273 462 50,9 7,45 105,1 0 64,3 14 74 43 220 405 50,9 6,83 48,2 0,5 42,9 15 (*) 92 31 247 445 52,2 7,02 49,2 0,5 51,5 16 (*) 46 59 148 379 33,4 6,81 38,5 1,25 35,8 Table 2 Sample No. Cu Zn Si P Pb Fe Sn As α-phase β-phase γ-phase Phosphide particles α-grain size % by weight % by weight % by weight % by weight % by weight % by weight % by weight % by weight Vol. Vol. Vol. Vol. µm 19 67,773 31,018 0,858 0,124 0,0011 0,213 94 0 4 2 24 20 65,648 33,431 0,571 0,132 0 0,211 94 4 1 1 22 21 (*) 66,904 31,635 1,075 0,086 0,096 0,197 90 8 1 1 23 22 (*) 63,648 35,462 0,563 0,106 0,00193 0,215 88 11 0 1 22 23 (*) 66,051 33,357 0,280 0,096 0,00172 0,211 94 3 2 1 25 24 (*) 63,339 36,341 0,000 0,098 0,00248 0,216 94 5 0 1 26 25 65,419 33,538 0,564 0,240 0,00081 0,235 96 0 1 3 16 30 (*) 62,889 35,465 0,0014 <0,0005 1,509 0,07 0,0005 0,062 > 99 < 1 0 31 (*) 62,786 36,866 0,0011 <0,0005 0,201 0,072 0,0007 0,067 93 7 0 54 Sample No. longitudinal dezincification Dezincification across R p0.2 R m Elongation at break electrical conductivity Bending moment Chip form number H µm µm MPa MPa % MS / m Nm - 19 52 36 204 423 38 8,96 80,2 1 76,6 20 97 126 188 406 39 10,3 70,5 1,25 84,7 21 (*) 230 203 196 414 43 10,4 40,3 1,25 56,4 22 (*) 379 278 200 428 42 10,7 46,3 0,75 65,9 23 (*) 63 44 184 377 42 11,9 121,4 0 107,8 24 (*) 75 90 178 367 40 14,2 119,8 0 121,8 25 44 53 213 419 37 10,4 80,5 1,25 77,7 30 (*) 86 69 21,3 0,5 - 31 (*) 109 94 347 397 20,6 13,7 70,8 0 -

[0066] Specimen No. 1 is a reference specimen in the unannealed condition. With a β-phase volume fraction of 1%, a γ-phase volume fraction of 6%, a silicon content of 1.44 wt.%, and a phosphorus content of 0.090 wt.%, the specimen exhibits a hardness value (H) of 43.8, thus fulfilling the condition H < 60. The average bending moment during planing was determined to be 35.8 Nm, and the chip shape was rated at 1.25. This specimen is therefore exceptionally machinable. The specimen's composition of 70.62 wt.% Cu, 1.44 wt.% Si, and 0.090 wt.% P results in excellent dezincification resistance. The dezincification attack is only 20 µm longitudinally and 14 µm transversely. Therefore, the specimen is dezincification-resistant according to EN ISO 6509-1. However, a volume fraction of the γ-phase of 6% does not guarantee resistance to corrosion in circulating hot water.

[0067] Specimen No. 2 is a specimen according to the invention, which was annealed after hot forming. With a volume fraction of 0% for the β-phase, 3% for the γ-phase, a Si content of 1.44 wt.%, and a P content of 0.090 wt.%, the specimen exhibits a value H of 50.5 and thus fulfills the condition H < 60. The average bending moment during planing was determined to be 44.0 Nm, and the chip shape was rated at 0.5. This specimen is therefore readily machinable. The absence of the β-phase is noticeable in the chip shape. The composition of the specimen, with 70.62 wt.% Cu, 1.44 wt.% Si, and 0.090 wt.% P, ensures, as with specimen No. 1, excellent dezincification resistance. The dezincification attack is only 26 µm longitudinally and 17 µm transversely. This means the sample is dezincification resistant according to EN ISO 6509-1. The Sn content of 0.226 wt.%, together with a volume fraction of the γ-phase of only 3%, makes the sample resistant to corrosion in circulating hot water.

[0068] Samples No. 3 to No. 9 each have a silicon content of less than 1.1 wt.% and a copper content of 63 to 68 wt.%. Due to the low silicon content combined with a β-phase volume fraction of more than 4%, the samples exhibit dezincification depths of more than 200 µm according to EN ISO 6509-1. They are therefore not dezincification-resistant. Large bending moments were measured during planing of samples No. 7 and No. 8. In sample No. 7, this is due to the low silicon content combined with the low β-phase content of only 6 vol.%, while in sample No. 8, the complete absence of silicon cannot be compensated for by the high β-phase content of 12 vol.%. The H value is significantly above 60 for both samples.

[0069] Specimen No. 10 is a reference sample that was annealed after hot forming. The sample contains neither β-phase nor γ-phase, but due to its silicon content of 1.57 wt.% in combination with a phosphorus content of 0.11 wt.%, it is readily machinable: The h-value is 47.4, and the sample exhibits a low bending moment of 45.1 Nm when planed. Specimen No. 10 thus demonstrates that by selectively alloying silicon and phosphorus with even nearly 100 vol% α-phase, a material with very good machinability can be obtained. The absence of β-phase results in very good dezincification resistance. The maximum attack depth is 31 µm. The tin content of the sample is only 0.01 wt.%, so the material is subject to significant corrosion when exposed to hot water circulation.

[0070] Samples No. 11, No. 12, and No. 14 are samples according to the invention, which were annealed after hot pressing. With regard to their composition, they are similar to sample No. 10, but have a tin content of 0.25 to 0.30 wt.%. All three samples are free of β-phase. The volume fraction of the γ-phase is 0% (in No. 12), 2% (in No. 11), and 4% (in No. 14), with a silicon content of approximately 1.5 wt.% and phosphorus contents of 0.099 to 0.110 wt.%. For all three samples, the H value lies between 42 and 55, thus fulfilling the condition H < 60. The average bending moment during planing was determined to be 50.9 Nm (No. 11), 54.2 Nm (No. 12), and 48.2 Nm (No. 14). The chip shape was rated at 0.5 (No. 14), 1 (No. 12), and 1.15 (No. 11). Therefore, these samples are machinable to very well. In particular, sample No. 12 demonstrates that, through targeted alloying of Si and P, a material with good machinability can be obtained even with 99 vol% α-phase.Due to their composition, the samples are highly resistant to dezincification and corrosion. The maximum depth of dezincification attack for these samples is 74 µm, thus meeting the dezincification resistance standard EN ISO 6509-1. After four weeks of operation, the maximum attack depth in the corrosion test rig was determined to be 26 µm (No. 11), 8 µm (No. 12), and 22 µm (No. 14) at a flow rate of 0.5 m / s, and 0 µm for all three samples at a flow rate of 2.5 m / s. The samples therefore demonstrate excellent corrosion resistance when circulating warm water with a high bicarbonate concentration.

[0071] Specimen No. 13 is a reference sample that was annealed after hot pressing. Due to its composition, the sample is very resistant to dezincification: the attack depth is 30 µm longitudinally and 25 µm transversely. The volume fraction of the β-phase is 0%, which promotes dezincification resistance. On the other hand, with regard to machinability, the silicon content of 1.29 wt% is too low to compensate for the lack of β- and γ-phases: the H value is 64.3, which is above the limit of 60. The average bending moment during planing was determined to be 105.1, and the chip shape was rated as 0. Therefore, this sample is difficult to machine. Furthermore, the absence of tin makes the sample susceptible to corrosion in circulating warm water: After four weeks of use in the corrosion test rig, the maximum attack depth was determined to be 79 µm for 0.5 m / s flow velocity and 90 µm for 2.5 m / s flow velocity.This results in a significantly stronger attack on the sample than on samples No. 11, No. 12 and No. 14 according to the invention.

[0072] Specimen No. 15 is a reference sample that was annealed after hot pressing. Due to its composition, the sample is resistant to dezincification: the attack depth is 92 µm longitudinally and 31 µm transversely. The volume fraction of the β-phase is 0%, which promotes dezincification resistance. The higher silicon content of 1.5 wt.% compared to sample No. 13, in combination with a phosphorus content of 0.10 wt.%, compensates for the absence of the β- and γ-phases with regard to machinability: the H value is 51.5, thus fulfilling the criterion H < 60. The average bending moment during planing was determined to be 49.2, and the chip shape was rated at 0.5. Therefore, this sample is readily machinable. Samples No. 13 and No. 15 thus demonstrate that the material's machinability is highly sensitive to the silicon content. The absence of tin makes sample No.15. Susceptible to corrosion in circulating hot water: The maximum attack depth was determined to be 69 µm at a flow rate of 0.5 m / s and 144 µm at a flow rate of 2.5 m / s after 4 weeks of use in the corrosion test rig. This means that the sample is significantly more susceptible to corrosion than the samples according to the invention.

[0073] Specimen No. 16 is a reference specimen that was annealed in its final state, i.e., after the last cold forming operation, at 750 °C for 2 hours. After annealing, the specimen exhibits a β-phase volume fraction of 1% and a γ-phase volume fraction of 10%, with a silicon content of 1.47 wt.% and a phosphorus content of 0.110 wt.%. The H-value is 35.8, thus fulfilling the criterion H < 60. The average bending moment during planing was determined to be 38.5 Nm, and the chip shape was rated at 1.25. Therefore, this specimen is very easy to machine. However, the high proportion of γ-phase leads to increased susceptibility to corrosion in the hot water test rig: Despite a Sn content of 0.25 wt.%, a maximum attack depth of 91 µm for 0.5 m / s flow velocity and of 64 µm for 2.5 m / s flow velocity was determined after 4 weeks of use in the corrosion test rig.

[0074] Sample No. 19 is a sample according to the invention in the post-annealed state. Its composition, which is identical to sample No. 3, with 67.77 wt.% Cu, 0.858 wt.% Si and 0.213 wt.% Sn, yields a zinc equivalent of 0.3717. The condition 0.36 < Zn eqThe requirement of < 0.39 is therefore met. Thus, sample no. 19 is multiphase after hot forming (like sample no. 3) and can be annealed for dezincification resistance. In the final state after annealing at 450 °C / 8 hours, the sample exhibits a volume fraction of 0% for the β-phase and 4% for the γ-phase. Testing for dezincification resistance according to EN ISO 6509-1 yields attack depths of 52 µm longitudinally and 36 µm transversely. Therefore, the sample is dezincification resistant. Machinability in the post-annealed state is not optimal, with an average bending moment of 80.2 Nm and a chip shape of 1. However, if the sample is planed in the pre-annealing state, i.e., after hot forming and cold forming (corresponding to sample no. 3), the average bending moment is significantly reduced to 41.1 Nm with a chip shape of 1. The sample is therefore very easy to machine in this intermediate state.With a β-phase volume fraction of 6% and a γ-phase volume fraction of 4%, a Si content of 0.858 wt.% and a P content of 0.124 wt.%, the condition H < 60 is met for sample no. 3 (and thus also for sample no. 19 before final annealing) with H = 41.1. Subsequent annealing transforms the very machinable, but not dezincification-resistant, sample no. 3 into the very dezincification-resistant state of sample no. 19.

[0075] Sample No. 20 is a sample according to the invention in the post-annealed state. Its composition, which is identical to that of sample No. 4, with 65.65 wt.% Cu, 0.571 wt.% Si and 0.211 wt.% Sn, yields a zinc equivalent of 0.3764. The condition 0.36 < Zn eqThe requirement of < 0.39 is therefore met. Consequently, sample no. 20 is multiphase after hot forming (like sample no. 4) and can be annealed for dezincification resistance in the final state. After annealing at 450 °C for 8 hours, the sample exhibits a volume fraction of 4% of the β-phase and 1% of the γ-phase. Testing for dezincification resistance according to EN ISO 6509-1 yields attack depths of 97 µm longitudinally and 126 µm transversely. Thus, the sample is just barely considered dezincification-resistant. Machinability in the post-annealed state is not optimal, with an average bending moment of 70.5 Nm and a chip shape of 1.25. However, if the specimen is planed in the pre-annealing state, i.e., after hot forming and cold forming (corresponding to specimen no. 4), the average bending moment is significantly reduced to 58.6 Nm with a chip thickness of 0.75. The specimen is therefore easier to machine in this intermediate state.With a β-phase volume fraction of 12% and a γ-phase volume fraction of 0%, a Si content of 0.571 wt.% and a P content of 0.132 wt.%, the condition H < 60 is met for sample no. 4 (and thus also for sample no. 20 before final annealing) with H = 55.8. Subsequent annealing transforms the readily machinable but not dezincification-resistant sample no. 4 into the dezincification-resistant state of sample no. 20.

[0076] Sample No. 25 is a sample according to the invention in the post-annealed state. Its composition, which is identical to that of sample No. 9, with 65.42 wt.% Cu, 0.564 wt.% Si and 0.235 wt.% Sn, yields a zinc equivalent of 0.3778. The condition 0.36 < Zn eqThe value < 0.39 is therefore met. Thus, sample no. 25 is multiphase after hot forming (like sample no. 9) and can be annealed for dezincification resistance in its final state. After annealing at 450 °C for 8 hours, the sample exhibits a volume fraction of 0% for the β-phase and 1% for the γ-phase. Testing for dezincification resistance according to EN ISO 6509-1 yields attack depths of 44 µm longitudinally and 53 µm transversely. Therefore, the sample is dezincification resistant. Machinability in the post-annealed state is not optimal, with an average bending moment of 80.5 Nm and a chip shape of 1.25. However, if the specimen is planed in the pre-annealing state, i.e., after hot forming and cold forming (corresponding to specimen no. 9), the average bending moment is significantly reduced to 42.0 Nm with a chip shape of 1. The specimen is therefore excellently machinable in this intermediate state.With a β-phase volume fraction of 11% and a γ-phase volume fraction of 0%, a Si content of 0.564 wt.%, and a P content of 0.240 wt.%, the condition H < 60 is met for sample no. 9 (and thus also for sample no. 25 before final annealing) with H = 36.3. Subsequent annealing transforms the readily machinable but not dezincification-resistant sample no. 9 into the dezincification-resistant state of sample no. 25.

[0077] Samples No. 21 and No. 22 are reference samples in the post-annealed state. Their respective compositions, identical to those of sample No. 5 and sample No. 6 respectively, yield a zinc equivalent of more than 0.39 for both samples. The condition Zn eqThe requirement of < 0.39 is therefore not met, meaning the samples cannot be converted to a dezincification-resistant state by annealing. In the final state after annealing at 450 °C / 8 hours, the samples exhibit a volume fraction of the β-phase of 8% (No. 21) and 11% (No. 22), respectively, and a volume fraction of the γ-phase of 1% (No. 21) and 0% (No. 22). Testing for dezincification resistance according to EN ISO 6509-1 yielded attack depths of 230 µm longitudinally / 203 µm transversely on sample No. 21 and 379 µm longitudinally / 278 µm on sample No. 22.

[0078] Specimen No. 23 is a reference specimen in the post-annealed state. Its composition, identical to that of Specimen No. 7, results in a zinc equivalent of less than 0.36. Therefore, the specimen is not sufficiently multiphase after hot forming. Machinability in the post-annealed state is very poor, with an average bending moment of 121.4 Nm and a chip formation of 0. If the specimen is planed in the pre-annealed state, i.e., after hot and cold forming (corresponding to Specimen No. 7), the average bending moment is also very high at 109.6 Nm, with a chip formation of 0. Thus, the specimen is very difficult to machine in both states. With a volume fraction of the β-phase of 6% (unannealed) or 3% (post-annealed) and a volume fraction of the γ-phase of 0% (unannealed) or 2% (post-annealed) at a Si content of 0.280 wt.% and a P content of 0.096 wt.%, the condition H < 60 is not met by sample no.23 with H = 107.8 still fulfilled by sample no. 7 with H = 102.9.

[0079] Specimen No. 24 is a reference specimen in the post-annealed condition, with a composition identical to that of Specimen No. 8. While Specimen No. 24 is dezincification resistant with a maximum dezincification depth of 75 µm longitudinally and 90 µm transversely, it does not meet the condition H < 60 in either the post-annealed or the unannealed intermediate state. Machinability in the post-annealed state is very poor, with an average bending moment of 119.8 Nm and a chip formation of 0. If the specimen is planed in the pre-annealed state, i.e., after hot forming and cold forming (corresponding to Specimen No. 8), the average bending moment is also very high at 104.8 Nm with a chip formation of 0. Thus, the specimen is very difficult to machine in both states. With a volume fraction of the β-phase of 12% (unannealed) or 5% (post-annealed) and a volume fraction of the γ-phase of 0% (unannealed) or 0% (post-annealed) at a Si content of 0.000 wt.-% and a P content of 0.098 wt%, the condition H < 60 is not met by either sample no. 24 with H = 121.8 or by sample no. 8 with H = 81.7.

[0080] Specimen No. 30 represents the lead-containing reference alloy CuZn36Pb2As in the annealed condition. With dezincification depths of 86 µm longitudinally and 69 µm transversely, the specimen is dezincification-resistant according to EN ISO 6509-1. The Pb content of 1.5 wt.% makes the material readily machinable. The bending moment determined in the planing test is 21.3 Nm with a chip shape weighted as 0.5.

[0081] Specimen No. 31 represents the lead-reduced alloy CuZn38As with a lead content of 0.2 wt.% in the annealed condition. With dezincification depths of 109 µm longitudinally and 94 µm transversely, the specimen is still dezincification-resistant according to EN ISO 6509-1. Due to the low lead content, the specimen is more difficult to machine than specimen No. 30. The bending moment determined in the planing test is 70.8 Nm with a chip shape rated as 0. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] KR 10 0 555 854 B1

[0006] KR 10 2006 096 877 A

[0006] JP 2005 290 475 A

[0006] JP 2014 122 427 A

[0007] JP 2006 083 443 A

[0007] US 9 951 400 B1

[0008] Cited non-patent literature

[0000] RoHS (Directive 2011 / 65 / EU

[0003]

Claims

[1] Material made of a copper-zinc-silicon alloy with the following composition: Cu: 67.0 to 72.0 wt.%, Yes: 1.20 to 1.80 wt.%, Sn: 0.08 to 0.40 wt.%, P: 0.05 to 0.30 wt.%, Pb: optionally up to 0.10 wt.%, Fe: optionally up to 0.20 wt.%, Al: optionally up to 0.10 wt.%, Sb: optionally up to 0.10 wt.%, As: optionally up to 0.10 wt.%, Residual Zn and unavoidable impurities, wherein the material has a microstructure consisting essentially of α-phase, optional β-phase, optional γ-phase and phosphide particles embedded in the phases, and wherein the proportions of The β-phase and the γ-phase, as well as the proportions of Si and P, are chosen such that the material meets the condition (H) 185.092−5.72328⋅([Beta]+[Gamma])−89.087⋅[Si]−354.137⋅[P]+2.8045⋅([Beta]+[Gamma])⋅[Si]+236.598⋅[Si]⋅[P]<60 fulfilled, where [Beta] denotes the proportion of the β-phase in vol.%, [Gamma] the proportion of the γ-phase in vol.%, [Si] the proportion of silicon in wt.% and [P] the proportion of phosphorus in wt.%. [2] Material according to claim 1, characterized by , that the proportion of the γ-phase in the microstructure of the material is at most 5 vol.%. [3] Material according to claim 1 or 2, characterized by that the Cu content is at least 68.0 wt.% and at most 71.5 wt.%. [4] Material according to any one of claims 1 to 3, characterized by that the Si content is at least 1.30 wt.% and at most 1.70 wt.%. [5] Material according to any of the preceding claims, characterized by that the Sn content is at least 0.15 wt.% and at most 0.35 wt.%. [6] Material according to any of the preceding claims, characterized by that the P content is at least 0.07 wt.% and at most 0.25 wt.%. [7] Material according to any of the preceding claims, characterized by that the Pb content is at least 0.03 wt.%. [8] Wire, tube, rod or profile-shaped semi-finished products made of a material according to any of the preceding claims. [9] Media-carrying component made of a material according to any one of claims 1 to 7. [10] Method for manufacturing a component from a copper-zinc-silicon alloy material, the method comprising the following steps: a) Melting and casting of a cast product made of a copper-zinc-silicon alloy with the following composition: Cu: 64.0 to 72.0 wt.%, Yes: 0.40 to 1.80 wt.%, Sn: 0.08 to 0.40 wt.%, P: 0.05 to 0.30 wt.%, Pb: optionally up to 0.10 wt.%, Fe: optionally up to 0.20 wt.%, Al: optionally up to 0.10 wt.%, Sb: optionally up to 0.10 wt.%, As: optionally up to 0.10 wt.%, Residual Zn and unavoidable impurities, b) optional heat treatment of the cast product, c) optional hot forming of the cast product and optional further forming steps, d) obtaining a material having a microstructure consisting essentially of α-phase, optional β-phase, optional γ-phase and phosphide particles embedded in the phases, wherein the proportions of the β-phase and the γ-phase and the proportions of Si and P are chosen such that the material satisfies condition (H) 185.092−5.72328⋅([Beta]+[Gamma])−89.087⋅[Si]−354.137⋅[P]+2.8045⋅([Beta]+[Gamma])⋅[Si]+236.598⋅[Si]⋅[P]<60 fulfilled, where [Beta] denotes the proportion of the β-phase in vol.%, [Gamma] the proportion of the γ-phase in vol.%, [Si] the proportion of silicon in wt.% and [P] the proportion of phosphorus in wt.%, e) Machining of the material to obtain a component, f) Heat treatment of the component so that the proportion of the β-phase in the microstructure of the material is at most 4 vol.% and the proportion of the γ-phase in the microstructure of the material is at most 5 vol.%. [11] Method according to claim 10, characterized by that the material meets the condition 0.36<([Zn]+10⋅[Si]+2.3⋅[Sn]) / ([Cu]+[Zn]+10⋅[Si]+2.3⋅[Sn])<0.39 fulfilled, where [Cu] denotes the proportion of Cu in wt.%, [Zn] the proportion of Zn in wt.%, [Si] the proportion of silicon in wt.%, [Sn] the proportion of Sn in wt.%. [12] Method according to claim 10 or 11, characterized by, that the Cu content of the copper-zinc-silicon alloy is at least 64.5 wt.% and at most 66.5 wt.% and the Si content of the copper-zinc-silicon alloy is at least 0.50 wt.% and at most 0.70 wt.%. [13] Method according to claim 10 or 11, characterized by , that the Cu content of the copper-zinc-silicon alloy is at least 67.0 wt.% and at most 69.5 wt.% and the Si content of the copper-zinc-silicon alloy is at least 0.75 wt.% and at most 0.95 wt.%. [14] Method according to any one of claims 10 to 13, characterized by that the Sn content of the copper-zinc-silicon alloy is at least 0.15 wt.% and at most 0.35 wt.%. [15] Method according to any one of claims 10 to 14, characterized by that the phosphorus content of the copper-zinc-silicon alloy is at least 0.07 wt.% and at most 0.25 wt.%. [16] Method according to any one of claims 10 to 15, characterized bythat the Pb content of the copper-zinc-silicon alloy is at least 0.03 wt.%.