WO2007012320A2

WO2007012320A2 - Method for producing a copper alloy having a high damping capacity

Info

Publication number: WO2007012320A2
Application number: PCT/DE2006/001305
Authority: WO
Inventors: Hennadiy Zak; Sönke VOGELGESANG; Agniezka Mielczarek; Babette Tonn; Werner Riehemann
Original assignee: Technische Universität Clausthal
Priority date: 2005-07-27
Filing date: 2006-07-27
Publication date: 2007-02-01
Also published as: EP1910582A2; DE112006002577A5; WO2007012320A3; US20080298999A1; DE102005035709A1; EP1910582B1; JP2009503250A

Abstract

The invention relates to a copper alloy which is used for mechanically stressed components which, during operation, are subjected to vibrations and/or impacts or produce the same, and have particularly good mechanical damping properties. The composition of said copper alloy depends upon the utilisation temperature or working temperature of the component. Said copper alloy consists of 2 - 12 wt.- % manganese, 5 - 14 wt.- % aluminium and individually or in total 0 - 18 wt.- % of one or several elements, nickel, iron, cobalt, zinc, silicon, vanadium, niobium, molybdenum, chromium, tungsten, beryllium, lithium, yttrium, cerium, scandium, calcium, titanium, phosphorous, zirconium, boron, nitrogen, carbon, whereby each element does not contain more that 6 % and 100 wt.- % copper. The alloy is obtained by adapting the martensite-austenitic conversion temperatures or the associated intervals MS - MF and/or AS - AF to a predetermined utilisation temperature or working temperature of the component by varying the weight proportion of the above-mentioned alloy component during melting thereof. The damping can reach above 70 %.

Description

Description:

Process for producing a copper alloy with high damping capacity

The invention relates to a method for producing a copper alloy, which is particularly suitable for mechanical, for example, by vibration, impact or shock loaded components, adjusted to the application of the components alloy properties and specifically with targeted improved, or optimally adjusted mechanical damping. Furthermore, the invention relates to such an alloy of particular composition and possible uses for the alloys obtained by the process.

Metallic materials or alloys with high damping capacity are known in principle and are also referred to as HIDAMETs (High Damping METaIs).

For example, high mechanical damping capacity is desirable for reducing vibration and noise reduction. Such alloys are therefore particularly suitable for the manufacture of marine propellers and pump housings, as well as for use in vibrating machines and for preventing vibration disturbances in various precision apparatuses and electronic instruments. At the same time high wear resistance, the alloys are also suitable for use in various tools that are exposed to vibrations and / or shocks during operation, such as punches or dies in sheet metal forming or in lathes and milling machines.

There are a variety of HIDAMETs known for noise reduction and for

Absorption of vibrations are used. However, the fields of application of a majority of these materials, in particular of magnesium and magnesium alloys, are greatly limited by their insufficient mechanical and corrosion properties. HIDAMETs with martensitic phase transformations are of particular importance in the art for achieving high attenuation properties. Alloys with martensitic phase transformations have a different atomic arrangement in the solid state at high temperatures than at low temperatures. The high temperature phase is referred to as "austenite" and the low temperature phase as "martensite". The transformation of austenite into martensite takes place from the austenitic state when the material cools down and starts at the martensite start temperature Ms. The martensitic transformation is completed when the martensite finish temperature M _{F is reached} . The transformation of martensite into austenite takes place when the material heats up from the martensitic state, starts at the austenite start temperature As and is completed when the austenite finish temperature A _{F is reached} . In general, the attenuation in the martensite range (T <M _F ) is higher than in the austenite range (T> A _F ) because of the much higher defect density.

The best known alloys of the type mentioned are Ni-Ti alloy ("Nitinol"), Cu-Zn-Al alloys ("Proteus") and Mn-Cu alloys ("Sonoston"). However, these three types of alloys have disadvantages that significantly limit their applications. Ni-Ti alloys must be produced consuming under vacuum and are also very expensive due to the alloying elements involved. In comparison with nitinol, Cu-Zn-Al alloys are much cheaper. The limited corrosion resistance and the tendency to brittle fracture behavior are significant disadvantages of these alloys. In addition, they are extremely severe in both the austenitic and the martensitic state to aging. The widely used Mn-Cu alloys have been specially developed for the manufacture of ship propellers. Due to the relatively wide solidification interval of about 130 ^° C., these alloys are prone to hot cracking. In addition, aging effects also occur here, so that a significant decrease in the damping effect occurs already at room temperature after storage for about 1000 hours. US Pat. No. 3,868,279 discloses high-attenuation Cu-Mn-Al alloys and a way of improving their damping properties by heat treatment. These ternary alloys contain 32-42% by weight of Mn, 2-4% by weight of Al and the remainder Cu, the Mn content preferably being 40% and the Al content preferably being 2-3%. These alloys are cold rolled and subjected to a heat treatment at temperatures between 649 ⁰ C and 760 ⁰ C, quenched in water, then aged at 204 ° C to 482 ⁰ C for 1, 5 to 24 hours and cooled in air. It is described a significant improvement in damping properties with less brittleness compared to the prior art Heusler alloys.

A technically interesting material alternative to the HIDAMETs described above are Cu-Al-Mn shape memory alloys. These materials also exhibit a thermoelastic martensite transformation. US Pat. No. 4,146,392 describes Cu-Al-Mn shape memory alloys containing, in addition to the main constituent copper, as alloy constituents 4.6 to 13% by weight of manganese and 8.6 to 12.8% by weight of aluminum, and good resistance to Have aging. These are alloys whose austenite-martensite transformation takes place at temperatures below 0 ^° C. and whose shape memory effect is exploited, for example to produce pipe connection elements.

From DE 2055755 a method for the production of articles of copper-base alloys is known, which are able to change their shape as the temperature changes. The alloys proposed for this purpose contain, in addition to copper and aluminum, for example, an element from the group of zinc, silicon, manganese and iron.

Despite the very favorable combination of mechanical properties and achievable martensitic transformation temperatures, the use of Cu-Al-Mn shape memory alloys for noise and vibration damping

Materials have not been considered so far, since the mechanical damping properties could not previously be targeted and possibly even varied greatly from batch to batch. The invention therefore an object of the invention to provide heavy-duty and corrosion-resistant HIDAMETs with a precisely adjustable even in the decisive for the intended application temperature range high damping capacity and a method for their production.

The object of the invention is achieved by a method for producing a copper alloy with specifically improved mechanical damping, in particular for mechanically loaded components, which is characterized by the following steps: a) a composition for the alloy is selected and the

B) during this melting, at least one of the martensitic and austenitic transformation temperatures Ms, M _F , A _S and A _{F is determined} on a sample taken from the melt, c) these transformation temperatures are determined with respect to a previously known

Use or working temperature of the component by targeted addition of at least one alloying ingredient increased or decreased and thus adapted d) the newly set transition temperatures and any intervals are checked by means of another sample and e) the alloy is poured into the desired shape.

Steps c) and d) may be repeated as many times as necessary until the desired adaptation of the transformation temperatures or intervals is achieved.

The composition for the alloy is selected from the components:

2 to 12% by weight of manganese, 5 to 14% by weight of aluminum and, individually or in total, 0 to 18% by weight of one or more of the elements nickel, iron, cobalt, zinc,

Silicon, vanadium, niobium, molybdenum, chromium, tungsten, beryllium, lithium, yttrium, cerium, scandium, calcium, titanium, phosphorus, zirconium, boron, nitrogen, carbon, however, per element not more than 6% and ad 100% by weight of copper.

The alloys obtained by the process according to the invention are otherwise produced by conventional melting and casting processes. Except as

Cast alloy, the alloy can also be used as wrought alloy. The

Alloy can be cold or hot form. The alloys described herein are particularly advantageous for all applications where a high mechanical damping capacity is required, i. especially for mechanically loaded components, devices or housings that are subject to vibrations, impacts or shocks.

The alloys differ from Sonoston in significantly higher aluminum and significantly lower manganese contents. The high aluminum content improves the strength of the material according to the invention and at the same time increases its resistance to abrasion, erosion and cavitation. The reduced manganese concentration has a positive effect on the cast-technological properties of the alloy due to the reduction in the solidification interval. Thus, dense, oxide and warm crack-free casts can be produced with unit weights of several tons without quality problems.

In order to obtain the optimum properties for a desired application, the proportions of the alloy components are usually varied, for. B. as described in more detail below. It has been found that the mechanical damping capacity, which frequently fluctuates greatly with variation of the composition, can be optimized and set to higher values by means of a targeted fine tuning of the contents of the individual alloy components than if only the martensitic region were preferred for better reproducible damping properties. as is usual in the prior art.

For the targeted improvement of the mechanical damping, the martensit austenitic transformation temperatures or the associated intervals Ms to MF and / or As adjusted to AF to a predetermined service or working temperature, which will occur in the intended use of the alloy in a "component". As a result, a high internal friction is set at the same time. The term "component" is intended to cover all conceivable practical applications and include both individual parts, such as more complex composite components, housings, machines and the like. Both the operating temperature and the working temperature can be medium temperatures, ie average values from a working or application area. Optionally, both transition temperature intervals, the martensitic and the austenitic, may be used to set to one or more different operating temperature ranges. The adjustment is made by varying the weight proportions of the above alloying ingredients during the melting of the alloy.

With the help of the elements nickel, iron, cobalt, zinc, silicon, vanadium, niobium, molybdenum, chromium, tungsten, beryllium, lithium, yttrium, cerium, scandium, calcium, titanium, phosphorus, zirconium, boron, nitrogen, carbon it is possible to specially adapt the properties of the alloy obtained by the process to the particular application. For example, addition of nickel or silicon increases corrosion resistance and strength properties. The

Elements iron, vanadium, niobium, molybdenum, chromium, tungsten, yttrium, cerium, scandium, calcium, titanium, zirconium, boron are important for achieving grain refinement. Nitrogen and carbon together with transition elements improve the mechanical properties of the alloy obtained according to the invention. The aging resistance of the alloy in both austenitic and martensitic states is increased by the addition of cobalt. Beryllium and phosphorus protect the melt from oxidation. By various combinations of the alloying elements, an influence of varying influence on the transformation temperatures of the alloy according to the invention can furthermore be taken in order to optimally fulfill the requirement profile for a specific application.

The alloy therefore preferably contains between 1 and 4% by weight of nickel. A preferred embodiment of the alloy contains between 11.6 and 12 wt .-%, preferably about 11, 8 wt .-% aluminum. Furthermore, manganese contents between 8 and 10 wt .-% are preferred in the alloy. The alloy may further preferably contain between 0.01 and 1% by weight of cobalt.

The texture of the cast alloy is characterized by relatively large cast grains and is preferably grain-fined to achieve optimum mechanical properties. Boron additions between 0.001 and 0.05% by weight and / or chromium additions between 0.01 and 0.8% by weight and / or iron additions of 2 to 4% by weight are particularly effective for this purpose. In addition, the refinement can be carried out by adding rare earths up to 0.3% by weight.

The alloy may further contain between 2 and 6% zinc.

The alloys may preferably have Ms temperatures> 0 ⁰ C, without the invention being limited thereto.

The invention provides a significant improvement in the damping properties, since only by the invention, the optimal adjustment of these properties while taking into account other desired properties is possible. The inventive method allows the transformation temperatures in

Adapt the material to the respective conditions of use so that the specific damping capacity of the alloys according to the invention reaches up to 80% and more at the intended application temperature.

The invention further comprises a particularly composed copper alloy containing as alloy constituents more than 4% by weight of manganese, more than 10% by weight of aluminum, 0.01 to 0.8% by weight of chromium and singly or in total

0 to 18% by weight of one or more of the elements nickel, iron, cobalt, zinc, silicon, vanadium, niobium, molybdenum, chromium, tungsten, beryllium, lithium, yttrium, cerium, scandium, calcium, titanium, phosphorus, zirconium, Boron, nitrogen, Carbon, but each element contains not more than 6% and ad 100 wt .-% copper.

Incidentally, this new alloy for mechanically loaded components may have the further specifications as stated above and is also available by adjusting the martensite-austenitic transformation temperatures or the associated intervals Ms to Mp and / or As to AF to a predetermined service temperature of the component , as described above.

For existing HIDAMETs with martensitic phase transformations, it has been described in the prior art that the maximum attenuation on cooling from the austenite state occurs near the Ms temperature and when heated from the martensite state in the As temperature range. These attenuation maxima are not used in the art because the transformation temperatures of the material with the existing methods are poorly reproducible. Apparently small changes in the chemical composition by oxidation or burning of the alloying elements cause shifts in the transformation temperatures, which may be more than 100 ⁰ C. Therefore, it is also very precise and careful charge Charger melt flow has not been possible to adjust the Ms and A _S temperature in the range ± 10 ⁰ C reproducible. In the

Production of conventional HIDAMETs is therefore deliberately omitted to achieve the maximum attenuation in favor of smaller but better reproducible attenuation values in the purely martensitic state. This disadvantage is overcome by the invention.

Experiments by the inventors show that addition of copper raises the transformation temperatures. Additions of other alloying elements reduce the transformation temperatures. A particularly strong influence on the martensitic transformation temperatures can be achieved by adding aluminum and manganese. In a preferred embodiment, therefore, the correction of the transformation temperatures during melting by additions of copper or aluminum is achieved. Due to the high melting point of manganese and the high Affinity to oxygen is preferable to adding aluminum to lower the transition temperatures to an addition of manganese.

The maximum values for the specific damping capacity occur in the alloy according to the invention during cooling from the austenite state in the range between Ms and MF and when heating from the martensite state between As and AF.

Therefore, the temperature in the middle of the martensitic or austenitic phase transition interval should be as close as possible to the operating temperature of components made from the alloy of the invention. It is therefore possible with the invention to produce alloys for specific predetermined service or operating temperatures or temperature ranges, which are then particularly suitable for certain applications and components.

The exact adjustment of the transformation temperatures is made with a sample taken during the melting process which allows an express control of the transformation temperatures for the liquid alloy. As a sample for the express control, it is preferable to use a cast wire drawn from the melt by means of a quartz tube in which a negative pressure is generated. The determination of the transformation temperatures can be carried out on this sample, depending on the expected application either in the casting state or after the heat treatment by known experimental methods for the detection of phase transitions.

Preferably, the transformation temperature on the sample may be by calorimetry, dilatometry, electrical conductivity measurement, light microscopy, or acoustic emission measurement.

Based on the results of the examination of the Express sample, an immediate correction of the chemical composition of the melt, as described above, preferably with copper or aluminum. With the method according to the invention it is thus possible, the transformation temperatures in the material so adjust the alloy to the maximum possible damping capacity at the intended application temperature. This ensures an efficient adaptation of the material to the respective conditions of use.

The martensitic transformation can also be initiated in a defined temperature range via externally applied voltages. In this case, the transformation temperatures in the material increase linearly with the load. This increase in the transformation temperatures must already be considered in the production of components made from the alloy according to the invention, if mechanical stresses are to be expected there.

In addition to the influencing factors already mentioned, the damping maximum is also considerably influenced by the microstructure of the alloy, with larger grains leading to better damping properties. By appropriate alloying measures, the grain size of the alloy can be adjusted so that for each specific application, an optimal compromise between the damping capacity and the mechanical properties is achieved.

It has also been found that an improvement of the damping properties can be achieved by a heat treatment. As particularly effective has an annealing at temperatures of 650 ⁰ C to 950 ⁰ C followed by cooling or quenching (quenching) in liquid or gaseous media such. As air, liquid nitrogen, water, salt bath or oil proved. The temperature of the quenching medium should preferably be above the M _s temperature in order to avoid uncontrollable shifts in the transformation temperatures in the material. The aging sensitivity of the transition temperatures can be reduced according to the invention by an additional aging of the quenched alloy at a temperature of 150 ⁰ C to 250 ⁰ C. Expediently, such outsourcing takes 5 to 120 minutes. On large and solid castings of the alloy according to the invention, which can not be subjected to heat treatment and quenching, a martensitic structure can be produced in the surface layer according to a further feature of the invention by laser remelting. In this case, the 5 edge layer takes over the damping roll, without the entire component having to undergo a cost-intensive heat treatment. In the production of such castings, the transformation temperatures of the alloy during melting by the express control are adjusted so that, taking into account the cooling conditions during laser remelting, the transformation temperatures in the surface layer correspond to the application temperature of the component.

The alloys obtained by the process according to the invention can be used particularly advantageously for reducing vibrations for noise damping on mechanically loaded components, in particular in the case of

Ship propellers, machine housings, in particular pump housings,

Generator housings, vibrating machines, precision equipment, electronic

Instruments, tools which are exposed to or produce vibrations and / or impacts during operation, in particular stamps, dies,

Machine hammers, turning and milling tools.

The invention is explained in more detail below with reference to an embodiment.

> 5 example

To produce noise-damping compressor housings or various hydraulic components, it is possible to use an alloy which unfolds its maximum damping properties at a temperature of approximately 120 ^° C.

.0

For this purpose, the following alloy was produced in an induction furnace in air: Basic composition: 84% by weight copper 12% by weight aluminum 4% by weight manganese

Express-sampling:

For the express control of the transformation temperatures, the following procedure was developed: The sample is a cast wire having a length of 10 to 150 mm (preferably 15 to 100 mm) and a cross-sectional area of 0.2 to 7 mm ² , preferably 0.7 to 3.2 mm ² . This is pulled out of the melt with the help of a quartz tube, in which a negative pressure is generated. This sample can be used directly and very quickly with known detection methods. In a preferred method also used here, the acoustic emission is tracked over a temperature profile.

The first sample for express control of melt transformation temperatures with the base composition provided AF = 100 ^° C; A _s = 52 ⁰ C; Ms = 68 ⁰ C and M _F = 15 ⁰ C.

By adding copper, the transformation temperatures of this melt were corrected to higher values. A _F = 145 ⁰ C were subsequently performed on the Express-sample A _s = 74 ° C; M _s = 102 ⁰ C and M _F = 43 ⁰ C determined. These transformation temperatures are well suited for achieving maximum attenuation values at 120 ^° C. The melt was poured into a preheated to 300 ⁰ C mold. Samples for the damping measurement were worked out from the castings obtained. To characterize the damping behavior, the specific damping capacity was used. The internal friction was measured at a bending vibration frequency of 0.1 Hz under a constant heating and cooling rate (1 K / s). For these purposes, the 2980 DTMA V1.7B was used by TA Instruments. The internal friction is parameterized in terms of the phase angle between stress and strain. To characterize the damping behavior was a specific damping capacity, by the formula Spec. Damping capacity = 2π tanφ

is reproduced.

The damping behavior of the alloy produced in this way is shown in FIG.

Fig. 1: Formation of the specific damping capacity of the alloy of the example taken for a heating and cooling cycle

FIG. 1 shows a measurement diagram which was taken for the example described above. The specific damping capacity is plotted in% above the temperature in ° C. The temperatures were run in a heating and cooling cycle from below zero to 200 ⁰ C and back. As can be seen, in the exemplary alloy in the austenitic interval much higher attenuation can be achieved than in the martensitic, so that the frequently occurring in the art restriction to martensitic structures must lead to significant disadvantages for the alloy properties.

The example alloy reaches its maximum damping properties at a temperature of 120 ⁰ C and thus successfully fulfills the task. The achievable damping is over 70%.

Claims

Claims:

1. A process for the production of a copper alloy with specifically improved mechanical damping for mechanically loaded components used as alloying components

2 to 12 wt .-% manganese, 5 to 14 wt .-% aluminum and individually or in total

0 to 18% by weight of one or more of the elements nickel, iron, cobalt, zinc, silicon, vanadium, niobium, molybdenum, chromium, tungsten, beryllium, lithium, yttrium, cerium, scandium, calcium, titanium, phosphorus, zirconium, Boron, nitrogen, carbon, but each element contains not more than 6% and ad 100 wt .-% copper, characterized in that a) a composition selected for the alloy and the components are melted at a suitable temperature in a conventional manner, b) during this melting at least one of the martensitic and austenitic transformation temperatures Ms, MF, AS and AF are determined on a sample taken from the melt, c) these transformation temperatures with respect to a known operating or operating temperature of the component by targeted addition of at least one

Increasing or decreasing the alloying constituent and thus adapting it, d) checking the newly set transformation temperatures and, if necessary, intervals using a further sample and e) casting the alloy into the desired shape.

2. The method according to claim 1, characterized in that the steps c) and d) are repeated as often required.

3. The method according to claim 1 or 2, characterized in that a correction of the transformation temperatures during melting by

Additions of copper or aluminum takes place.

4. The method according to any one of claims 1 to 3, characterized in that the transformation temperatures are adjusted so that the temperatures in the middle of the martensitic or austenitic interval of the phase transformation are as close as possible to the predetermined operating or operating temperature.

5. The method according to any one of claims 1 to 4, characterized in that the alloy in the form of a primary obtained by casting or kneading and optionally forming a shaped part of an annealing at temperatures of 650 ⁰ C to 950 ⁰ C and then cooling or

Quenching in liquid or gaseous media, in particular air, liquid nitrogen, water, salt bath or oil is subjected.

6. The method according to claim 5, characterized in that the temperature of the quenching medium is selected above the Ms temperature of the alloy.

7. The method according to any one of claims 1 to 6, characterized in that the alloy in the form of a primary product obtained by casting or kneading and optionally forming molding at a temperature of

100 to 300 ⁰ C outsourced / aged for about 5 to 120 minutes.

8. The method according to any one of claims 1 to 7, characterized in that the alloy is exposed to one or more thermal cycles between austenitic and martensitic Zusatand and vice versa.

9. The method according to any one of claims 1 to 8, characterized in that a heat treatment in the surface layer of a molding obtained by casting or kneading and optionally forming from the alloy molding takes place by means of laser remelting of the edge zone.

10. The method according to any one of claims 1 to 9, characterized in that the sample for rapid control of the transformation temperatures by means of a quartz tube, in which a negative pressure is generated, is removed.

11. The method according to any one of claims 1 to 10, characterized in that the determination of the transformation temperatures on the sample by calorimetry, dilatometry, measurement of the electrical conductivity, light microscopy or measurement of the acoustic emission takes place.

12. The method according to any one of claims 1 to 11, characterized in that the Dämfpungsverhalten is additionally influenced by targeted change in grain size.

13. Copper alloy, especially for mechanically loaded components with specifically improved mechanical damping, as alloying components

> 4 to 12% by weight of manganese,

> 10 to 14 wt .-% aluminum, 0.01 to 0.8 wt .-% chromium and individually or in total 0 to 18 wt .-% of one or more of the elements nickel, iron, cobalt,

Zinc, silicon, vanadium, niobium, molybdenum, chromium, tungsten, beryllium, lithium, yttrium, cerium, scandium, calcium, titanium, phosphorus, zirconium, boron, nitrogen, carbon, but each element not more than 6% and ad 100 wt .-% copper.

14. Copper alloy according to claim 13, characterized in that the alloy contains between 1 and 4 wt .-% nickel.

15. Copper alloy according to claim 13 or 14, characterized in that the alloy between 11, 6 and 12 wt .-%, preferably about 11, 8 wt.

Contains% aluminum.

16. Copper alloy according to one of claims 13 to 15, characterized in that the alloy contains between 8 and 10 wt .-% manganese.

17. Copper alloy according to one of claims 13 to 16, characterized in that the alloy contains between 2 and 4 wt .-% iron and / or between 0.001 and 0.05 wt .-% boron.

18. Copper alloy according to one of claims 13 to 17, characterized in that the alloy contains between 0.01 and 1 wt .-% cobalt.

19. Copper alloy according to one of claims 13 to 18, characterized in that the alloy contains between 0.01 and 0.3 wt .-% rare earths.

20. Copper alloy according to one of claims 13 to 19, characterized in that the alloy contains between 2 and 6 wt .-% zinc.

21. Use of the obtained with a method according to any one of claims 1 to 12 copper alloy for reducing vibration and noise attenuation of mechanically loaded components.

22. Use according to claim 21 in ship propellers, machine housings, in particular pump housings, generator housings, vibrating

Machines, precision equipment, electronic instruments, tools subjected to or producing vibrations and / or impacts during operation, in particular stamps, dies, machine hammers, lathe and milling tools.