EP1801250B1 - Parts made from copper alloy with low migration for conduits conveying fluids or drinking water - Google Patents

Description

The invention relates to a use of a component for media or drinking water leading trades.
Metallic materials for the production of components for media or drinking water leading trades, such as fittings, fittings, pipes, compression connectors, roof gutters or gutters are subject, especially if the trades are provided for the drinking water supply, special requirements. First, the corrosion resistance of the metallic material should be mentioned here, since the components in contact with drinking water, for example, should not corrode even after many years of use. At the same time, the metals used should show a low migration tendency of metal ions into the medium, ie the amount of metal ions released to the medium should be very low. In drinking water pipes, especially health-endangering metal ions, such as lead or nickel ions, are problematic.

With regard to a simple production method of corresponding components, the copper alloy used of the components should not only be easy and economical to cast, but the cast components should also be easily machined. Since the components are cast and then often machined mechanically machined, the components should in particular a good Have machinability. Furthermore, the manufactured components would have to withstand the usual mechanical stresses.

Typically, high-copper-containing non-ferrous metal alloys, such as bronze or gunmetal, are used today for producing the media-carrying components of, for example, gas or drinking water pipes. In a conventional gunmetal alloy main alloying components in addition to copper about 1.5 to 11 wt .-% tin and 1 to 9 wt .-% zinc. In addition, to improve the machinability, lead and nickel may also be contained in a gunmetal alloy. For example, the gunmetal alloy CuSn5Zn5Pb5 contains between 4 to 6 wt .-% tin, zinc and lead at a nickel content of up to 2.0 wt .-% and a phosphorus content of up to 0.1 wt .-% , Although this material is characterized by good castability and good corrosion resistance. However, the problem is that lead and nickel ions are released from the gunmetal alloy by migration into the medium, in particular into the drinking water. It is therefore to be expected that in the future lower limit values for the release of metal ions, in particular lead and nickel, to the drinking water can no longer be met by the previously commonly used gunmetal alloys.

From the European patent application EP-1 045 041 are already lead-free components of media, especially drinking water, leading trades known which consist of a copper alloy with up to 79 wt .-% copper, 2 to 4 wt .-% silicon and the remainder zinc. However, it has turned out that those from the mentioned European Patent application known components are in need of improvement in terms of their corrosion resistance.

The known components media leading trades consisting of a lead-free copper alloy and consisting of previously used gunmetal alloys also have the disadvantage that they are mechanically deformable only with great effort. For example, cold and / or hot forming are only very limited or not possible. Therefore, the components were usually cast and then machined to the final product mechanically. This results in relatively high costs for the production of corresponding components for media-leading trades, since on the one hand the yields are limited system-related in the casting process mostly used. On the other hand, the work steps used so far offer little potential for rationalization or automation.

From the Swiss patent CH 148195 is the use of a copper-silicon-zinc alloy known as a bearing metal, which can be subjected to cold or hot forming. The same applies to the German patent DE 721 917 ,

The German patent DE 103 08 778 B3 proposes a copper alloy which in addition to the main alloying constituents copper, zinc and silicon up to 2 wt .-% tin, 0.3 wt .-% iron, cobalt, nickel and manganese and up to 0.5 wt .-% silver, aluminum , Arsenic, antimony, magnesium, titanium and zirconium permits.

On this basis, the present invention, the object of the invention to propose the use of components for media or drinking water leading trades, which are more corrosion resistant, can be produced in a simple and economical manner and a low migration of metal ions in the medium, such as lead and nickel ions in the drinking water, exhibit.

$$1\%\le \mathrm{Zn}\le 17\%,$$

$$0,05\%\le \mathrm{Mn}\le 2\%,$$

unvermeidbare Begleitelemente in Summe max. 0,5 Gew.-%, vorzugsweise in Summe max. 0,3 Gew.-%, Rest Kupfer und
der Barren oder die Stange zur Herstellung des Bauteils mindestens einer Kalt- und/oder Warmumformung unterzogen wird.The above-mentioned object is achieved according to a first teaching of the present invention by the use of a component made by a process in which a billet or a rod of a copper alloy is continuously cast, the copper alloy having the following alloy constituents in wt .-% : $$2\%\le \mathrm{Si}\le 4.5\%.$$

$$1\%\le \mathrm{Zn}\le 17\%.$$

$$0.05\%\le \mathrm{Mn}\le 2\%.$$

unavoidable accompanying elements in total max. 0.5% by weight, preferably in total max. 0.3 wt .-%, balance copper and
the billet or bar is subjected to at least one cold and / or hot forming for the production of the component.

It has surprisingly been found that the components according to the invention not only have particularly good migration values and high corrosion resistance to drinking water, but also possess the required mechanical properties for their use in media leading trades. Due to the hot and cold forming, the microstructure of the components according to the invention is much denser than that of the previously cast and subsequently machined components. This additionally results in an improvement of the migration behavior and the corrosion resistance.

The manufacturing cost of the components for media or drinking water leading trades can also be effectively reduced with the method according to the invention, since the previously used methods, namely the casting and subsequent, machining, such as milling, drilling or turning, due to low automation possibilities and the higher reject rates during casting are significantly more cost-intensive. It is also conceivable, of course, instead of continuous casting to use other possible casting methods for the production of the billet or rod, the continuous casting is considered at high volumes as the more economical casting process.

On the one hand, the silicon content of 2% by weight to 4.5% by weight of the copper alloy used according to the invention ensures an overall very good migration behavior, in particular of any lead and nickel impurities present in the copper alloy in the drinking water. On the other hand, the Si content also affects the mechanical strength of the copper alloy. First, at an Si content of less than 2% by weight, the migration-inhibiting property of silicon is weakened. Although the strength of the copper alloy increases at silicon contents greater than 4.5% by weight, the ductility of the copper alloy is then too low, in particular with regard to the later mechanical formability.

In order to achieve the required corrosion resistance of the components, the zinc content is limited to a maximum of 15 wt .-%. On the other hand, a minimum content of 1% by weight of zinc guarantees a minimum of machinability of the components, as long as these have to be machined additionally.

A manganese content of at least 0.05% by weight improves the microstructure of the components according to the invention to a finer microstructure and positively influences the solidification behavior of the copper alloy during casting. The upper limit of 2 wt .-% manganese also takes into account that manganese in the drinking water migrated and permissible limits are not exceeded. The fine structure of the copper alloy of the components also causes an improved cold or hot workability of the cast ingots or bars.

With the restriction of the impurities to a total of no more than 0.5% by weight, it is achieved that the migration of unavoidable alloy components into the drinking water, for example, is restricted to the minimum necessary. A further improvement of the migration properties of the manufactured components with regard to unavoidable accompanying elements of the copper alloy used is achieved by limiting the proportions of the unavoidable accompanying elements to a total of at most 0.3% by weight.

With regard to the use of components for media or drinking water leading trades is also conceivable to add grain refining materials of the copper alloy used to improve by a finer structure, the forming properties during the manufacture of the components or to reduce variations in mechanical properties of the manufactured components , As grain refining material, for example, the addition of small amounts of boron, for example, 0.001 to 0.5 wt .-%, into consideration. However, other grain refining materials may be used to improve the microstructure.

According to a next advantageous embodiment, the copper alloy used additionally has the following content of the alloying constituent zinc in% by weight: $$5\%\le \mathrm{Zn}\le 15\%\mathrm{,}$$

Since the machinability decreases due to the reduction in the Zn content, but the formability of the components decreases with increasing Zn content, a good compromise between formability and machinability is achieved according to the invention with a Zn content of 5% by weight to 15% by weight achieved achieved components. The components according to the invention can therefore not only be subjected to cold and / or hot forming, but also be machined.

A compromise between good strength and at the same time sufficient elongation values in combination with good migration values of the manufactured components is, according to a next embodiment, achieved in that the copper alloy for silicon has the following alloy content in wt .-%: $$2.\mathrm{8th}\%\le \mathrm{Si}\le 4\%\mathrm{,}$$

According to a next advantageous embodiment, a compromise between fine structure and low migration of manganese constituents into the drinking water is achieved by the components according to the invention in that the alloying constituent Mn has the following fraction in% by weight: $$0.2\%\le \mathrm{Mn}\le 0.6\%\mathrm{,}$$

Finally, the migration of nickel and / or lead ions into the drinking water can be avoided by that the copper alloy used according to the invention contains no nickel and / or lead.

On the other hand, the corrosion resistance can be increased by the fact that the copper alloy used has a copper content of at least 80%.

If, in accordance with a next embodiment, a thick-walled tube or a solid rod is produced from the billet or bar using extrusion, semi-finished products for cold and / or hot forming can be provided in a simple manner.

Preferably, the thick-walled tube is then cold drawn, so that dimensionally stable tubes can be made available with a few process steps by this simple method. As already mentioned above, the tube produced in this way also has a higher structural density than, for example, cast and machined tubes, since cold forming, as well as hot forming, leads to significant densification of the structure and a reduction in the porosity of the continuously cast structure ,

Starting from these thick-walled pipes, according to another embodiment, it is advantageous if the cold-drawn pipe is formed by hydroforming (hydroforming). As a result, complex, low-migration fittings, such as tees, can be produced economically.

If the cold-drawn tube or the tube formed by the hydroforming process in at least one further forming step subjected to bending, expansion, reduction, rolling, thickening, crimping and / or further hydroforming steps with or without intermediate annealing between the individual forming steps, even more complex components with threads, flanges, etc. can be produced in a simple manner.

Finally, thicker-walled components for media or drinking water-carrying industries are easily produced by at least hot-pressing or drop-forging the produced thick-walled tubes or solid rods in several steps. In hot pressing, in contrast to drop forging, the component is hot-formed in one process step. In hot forging hot forging takes place in several individual process steps. Due to the good hot workability of the copper alloy used, in addition to the previous method, casting and subsequent machining, in addition, a significant increase in the yield of good parts in the production can be achieved.

According to the invention, the ingot is hot rolled and / or cold rolled after continuous casting for the production of sheets with or without intermediate annealing, and the sheets are subsequently subjected to at least one further cold or hot forming step. Thus, hot and / or cold-rolled sheets can be used as starting materials for the production of fittings, fittings, pipes, press connectors, roof gutters or gutters, so that a considerable rationalization potential in the manufacture of the components is opened. Again, conceivable is the continuous casting by other casting methods, For example, sand or chill casting, to replace a billet.

Preferably, a longitudinally welded tube is produced from the hot and / or cold-rolled sheet, which can be used either as a component directly or as a semi-finished product for further forming steps. The longitudinally welded pipe can be longitudinally welded with or without additional material and subjected to further mechanical forming processes, for example an IHU process, bending, expansion, reduction, rolling, thickening and / or crimping.

If the sheets or the longitudinally welded tube subjected to deep drawing, so for example end caps can be produced in a simple manner.

As already stated, components according to the invention have a very low migration of the problematic nickel and lead ions into the drinking water. Furthermore, they can be produced efficiently and economically, so that the production costs are considerably reduced. Finally, the components produced by the process according to the invention, which have undergone at least one hot and / or cold forming step, due to the cold and / or hot forming a much denser structure with a lower porosity. This results in comparison to the conventionally produced by casting and subsequent chip removal components improved corrosion resistance and tightness of the components. Improved corrosion resistance simultaneously improves migration values.

Fig. 1

in einem Diagramm einen Vergleich zwischen der in das Trinkwasser abgegebenen Menge an Blei-Ionen von Bauteilen hergestellt gemäß einem ersten Ausführungsbeispiel der vorliegenden Erfindung sowie eines konventionell hergestellten Bauteils aus einer Rotguss-Legierung,

Fig. 2

in einem Diagramm die Menge der in das Trinkwasser abgegebenen Nickel-Ionen der Bauteile des ersten Ausführungsbeispiels der vorliegenden Erfindung und der konventionellen Bauteile aus Fig. 1,

Fig. 3

in einem Diagramm die Menge der in das Trinkwasser abgegebenen Kupfer-Ionen des Bauteils des ersten Ausführungsbeispiels der vorliegenden Erfindung und des konventionellen Bauteils aus Fig. 1,

Fig. 4

in einem Diagramm die Menge der in das Trinkwasser abgegebenen Zink-Ionen des ersten Ausführungsbeispiels der vorliegenden Erfindung und des konventionellen Bauteils aus Fig. 1 und

Fig. 5a bis d

perspektivische Ansichten von vier weiteren Ausführungsbeispielen von erfindungsgemäßen Bauteilen Medien oder Trinkwasser führender Gewerke.

There are now a variety of ways to design the process of the invention for the production of components for media or drinking water leading trades or components of the invention for media or drinking water leading trades and develop. On the one hand, reference is made to the
Claims 1 and 14 subordinate claims and to the description of embodiments in conjunction with the drawings. The drawing shows

Fig. 1

1 is a diagram showing a comparison between the amount of lead ions of components emitted into the drinking water, produced according to a first exemplary embodiment of the present invention and of a conventionally produced component made of a gunmetal alloy,

Fig. 2

in a diagram, the amount of discharged into the drinking water nickel ions of the components of the first embodiment of the present invention and the conventional components Fig. 1 .

Fig. 3

in a diagram, the amount of copper ions emitted into the drinking water of the component of the first embodiment of the present invention and the conventional component Fig. 1 .

Fig. 4

in a diagram, the amount of zinc ions released into the drinking water of the first embodiment of the present invention and the conventional component from Fig. 1 and

Fig. 5a to d

perspective views of four other embodiments of components according to the invention media or drinking water leading trades.

In Fig. 1 is shown in a diagram, the amount of discharged into the drinking water lead and its time course. The measurement was carried out according to the DIN standard DIN 50931-1 over 26 weeks. The DIN standard specifies the test arrangement and test conditions, with the help of which the corrosion probability of materials for metallic components of a drinking water installation can be determined in the case of corrosion contamination by drinking water.

• Si: 3,5 %,
• Zn: 1,6 %,
• Mn: 0,5 %
• unvermeidbare Begleitelemente in Summe max. 0,5 %, Rest Kupfer.

Shown in the diagram is the time profile of the discharged amount of lead to the drinking water of components manufactured according to a first embodiment of the method according to the invention, wherein the copper alloy used had the following proportions of alloying components in wt .-%:

• Si: 3.5%,
• Zn: 1.6%,
• Mn: 0.5%
• unavoidable accompanying elements in total max. 0.5%, balance copper.

The components according to the invention used for the test, in the present case tubes, were produced according to the invention from an extruded thick-walled tube by cold drawing.

• Zn: 5,5 %,
• Sn: 4,5 %,
• Pb: 3 %,
• Ni: 0,5 %,
• Rest Kupfer.

In addition, the components according to the invention are referred to as components A. The migration values of the components A were compared with those of conventionally produced components made of a gunmetal alloy B, the conventional gunmetal alloy having the following proportions of alloy constituents in% by weight:

• Zn: 5.5%,
• Sn: 4.5%,
• Pb: 3%,
• Ni: 0.5%,
• Rest of copper.

In addition, in Fig. 1 nor the limit value according to the German Drinking Water Ordinance (TrinkwV) represented by a dashed line and to be observed in the migration tests parameter value W (15) as a solid line. The parameter value W (15) represents the measured value which must be observed in order to avoid exceeding the value of the TrinkwV when using the tested components. This parameter value W (15) results from the product of the limit value of the Drinking Water Ordinance with the ratio of the form factors A and B. According to DIN 50 931-1, the factor A results from the ratio of the water-contacted surface of the material to the surface of the water-contacting surface test track. Form factor B is a scaling factor according to DIN 50 930-6, which takes into account the type of components.

As can be seen, the lead release quantity of the red brass components B falls from a very high value greater than 50 μg / l almost exponentially within the first four weeks of testing to a value which is just above the limit of the German drinking water regulation of 10 μg / l settles after 12 to 26 weeks of experimentation. This marked excess of the permissible limit value is attributed to the fact that, at the beginning of the tests, lead that had been transferred to the surfaces of the tested pipelines migrated into the drinking water through processing. After the first few weeks, the near-surface lead has almost completely migrated into the drinking water and the amount of discharged lead remains approximately constant.

The component A according to the invention, however, gives to the drinking water as good as no lead. Also, an increased value at the beginning of the experiments is unacceptable. Since the measured values are at the limit of the resolution of the measurement analysis, the measurement fluctuations are attributed to the measurement accuracy of the measuring apparatus. Essentially, however, the measured values remain well below the limit value of the TrinkwV of 10 μg / l.

The same applies to the course of the nickel release, which also measured over 26 weeks in the diagram of Fig. 2 is shown. The time course of the nickel release quantities of conventional gunmetal components B shows a typical course. First, the amount of nickel released after about 9 weeks exceeds the limit of the German TrinkwV, after a maximum in the 18th week of testing again fall towards the limit value of TrinkwV. Although the increase in nickel concentrations in drinking water can be due to the gunmetal components B so far not be explained exactly. However, the increase is reproducible and exceeding the limit of about 20 μg / l of the German Drinking Water Ordinance, also shown as a dashed line, takes place reproducibly.

In comparison, the nickel-free, inventive component A no significant nickel ions from the drinking water. Here, too, the measured value of about 2 μg / l is in the range of the resolution of the measuring instruments used for the analysis.

In Fig. 3 in turn, the amount of copper released to the drinking water of the components A according to the invention and of the red brass components B is shown. Both components show an increase until the 18th week of testing. Thereafter, in both alloys, the measured amounts of copper discharged fall again. The drinking water limit value for copper is 2000 μg / l. The parameter value W (15) assigned to comply with the limit values of the drinking water supply is about 3000 μg / l. This limit value is likewise not exceeded by the conventional component B with a maximum value of 2600 μg / l, measured in the 18th week of the experiment, as in the component B according to the invention. In this case, the maximum value is about 2100 μg / l and is thus about 20 % lower than the maximum value of the gunmetal alloy B. After 26 weeks, the amount of copper released continues to decrease for both alloys. In comparison, however, it is striking that the components according to the invention deliver about 500 μg / l or about 20-25% less copper ions to the drinking water than conventional components.

Finally shows Fig. 4 the amount of zinc released by the components into the drinking water. For the release of zinc, there is currently no limit in the TrinkwV.

However, the component A according to the invention also differs significantly from the conventional gun component B in the migration of zinc. While the component A according to the invention emits a maximum of 100 μg / l zinc in the drinking water by migration, the zinc output of the conventional gun component B exceeds this Value in the maximum by more than 4 times.

As a result, the in Fig. 1 to 4 shown experimental measurements that the migration of unwanted ions into drinking water can be generally reduced by the components of the invention. The very good results are attributed in this case to a combination of the migration-inhibiting property of the copper alloy used, but in particular also to the production method of the components leading to a denser microstructure according to the invention. In particular, the low emission of lead ions and nickel ions to the drinking water ensures that the components according to the invention can also be used under tightened limit values with regard to the content of metal ions of the drinking water.

In Fig. 5a to d Now typical embodiments of the components for media or drinking water leading trades, fittings, fittings and pipes are shown. So shows Fig. 5a a valve housing made of a copper alloy according to the invention, which was prepared for example from a continuously cast bar by extrusion of a thick-walled tube or a solid bar with subsequent hot pressing or drop forging. Due to the good formability of the alloy according to the invention, even with correspondingly complex components, such as those in Fig. 5a valve housing shown, good yields in the Production achieved. The continued good machinability of the components ensures that the components produced by the aforementioned method can be easily reworked.

In Fig. 5b a simple end cap 2 is shown, which was previously made mostly of pure copper due to the necessary thermoforming process. With the method according to the invention, the end cap 2 made of a copper alloy as the other components media leading trades can be produced, since the end cap 2 can be made from hot and / or cold-rolled sheets according to the invention by deep drawing. Subsequently, by means of a further cold-forming step, for example a mechanical expansion, an O-ring groove 3 can be introduced into the end cap 2.

Fig. 5c shows a perspective view of a bent pipe 4 with an overbend 5 and two-sided connection ends 6. The illustrated tube 4 is made according to the invention made of a cold and / or hot-rolled sheet, longitudinally welded pipe or consisting of a cold drawn tube. By using cold and / or hot forming steps in the manufacture of the components, depending on the available starting material, for example, thick-walled tubes or sheets, the economically most cost-effective method for producing the tubes can be selected. The overbend 5 is then produced by bending the tube 4. The fittings 6 are preferably made prior to bending either by a simple upsetting and widening step or introduced into the tube 4 using an hydroforming process.

Another typical so far mostly made of a gunmetal alloy component for media or drinking water leading trades provides the Fig. 5d Also, the T-piece 7 has at its two ends of the crossbar of the T's connecting pieces with O-ring grooves 3, which are produced either by a subsequent expansion process or already in the production of the T-piece 7 by hydroforming , As a rule, a cold-drawn tube is cut to length and, after a possible intermediate annealing in a tool, formed by hydroforming. In the T-piece blank thus produced, the thread 8 can be introduced, for example, by rolling.

The roof gutters or gutters, not shown in the figures, are produced according to a next embodiment of the method according to the invention from hot and / or cold-rolled sheets consisting of the mentioned copper alloy by simple bending and / or flanging.

Due to the manufacturing process according to the invention, as already stated, the components, fittings, fittings, pipes, press connectors, roof gutters or gutters made of a low-migration copper alloy can be produced particularly cost-effectively and therefore economically.

Claims (14)

1. Use of a component for media or drinking-water carrying works, wherein the component is produced by a method, which is
   characterised in that
   an ingot or a rod is continuously cast from a copper alloy, wherein the copper alloy has the following alloying components in wt.%: $$2\%\le \mathrm{Si}\le 4.5\%,$$

   

   $$1\%\le \mathrm{Zn}\le 17\%,$$

   

   $$0.05\%\le \mathrm{Mn}\le 2\%,$$

   

   unavoidable accompanying elements in total max. 0.5 %, preferably in total max. 0.3 %,
   the remainder copper and
   the ingot or the rod for producing the component is subjected at least to one cold and/or hot forming process.
2. The use according to claim 1,
   characterised in that
   the alloying component Zn has the following fraction in wt.%: $$5\%\le \mathrm{Zn}\le 15\%\mathrm{.}$$

   
3. The use according to claim 1 or 2,
   characterised in that
   the alloying component Si has the following fraction in wt.%: $$2.8\%\le \mathrm{Si}\le 4\%\mathrm{.}$$

   
4. The use according to claim 1 to 3,
   characterised in that
   the alloying component Mn has the following fraction in wt.%: $$0.2\%\le \mathrm{Mn}\le 0.6\%\mathrm{.}$$

   
5. The use according to claim 1 to 4,
   characterised in that
   the copper alloy contains no nickel and/or lead.
6. The use according to claim 1 to 5,
   characterised in that
   the copper alloy has a copper content of at least 80 wt.%.
7. The use according to claim 1 to 6,
   characterised in that
   a thick-walled tube or a solid rod is produced from the ingot or the rod using extrusion.
8. The use according to claim 7,
   characterised in that
   the thick-walled tube is cold drawn.
9. The use according to claim 8,
   characterised in that
   the cold-drawn tube is formed by an internal high-pressure (IHU) method.
10. The use according to one of claims 8 or 9,
    characterised in that
    the cold-drawn tube or the IHU-formed tube is subjected in at least one further forming step to bending, expanding, reducing, rolling, thickening, flanging and/or further IHU forming steps with or without intermediate annealing between individual forming steps.
11. The use according to claim 7,
    characterised in that
    the thick-walled tube or the solid rod is at least hot-pressed or die-forged in a plurality of steps.
12. The use according to claim 6,
    characterised in that
    after the continuous casting, the ingot is hot- or cold-rolled to produce sheets with or without intermediate annealing and the components are produced from the sheets by further cold and/or hot forming.
13. The use according to claim 12,
    characterised in that
    a longitudinally seam-welded tube is produced from the cold-or hot-rolled sheets.
14. The use according to any one of claims 12 or 13,
    characterised in that
    the sheets or the longitudinally seam-welded tube is subjected to deep-drawing.

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