Dampling alloy, process for producing the same, and damping part or vibration-proof product comprising or employing the same

Abstract

A manganese-based damping alloy having stable damping properties; a process by which the damping alloy can be obtained without fail; and a damping part or vibration-proof product comprising or employing the damping alloy. A damping alloy made up of from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, 0.05 wt% or less carbon, 0.06 wt% or less oxygen, 0.06 wt% or less nitrogen, and manganese and unavoidable impurities as the remainder. Due to this constitution, nonmetallic inclusions such as carbides generate in a reduced amount and the manganese-based alloy can be pure. Consequently, the formation of a twin-crystal structure during heat treatment is accelerated and factors which inhibit the twin-crystal structure from moving upon stress imposition are diminished, whereby damping properties can be improved.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a manganese-based damping alloy having stable damping properties, a process for producing the same, and a damping part or vibration-proof product which comprises or employs the alloy.

BACKGROUND OF THE INVENTION

[0002] Manganese-based damping alloys of the twin crystal type are known, which are excellent in processability, formability, and other properties and effective in diminishing vibrations and noises (see, Japanese Patent 2,849,698).

[0003] The manganese-based damping alloys contain from 61 to 80 wt% manganese, which has a low melting point (1,244° C.) and a high vapor pressure, in contrast to iron-based alloys.

[0004] Because of this, when the melting method ordinarily used for iron-based alloys is used for melting the manganese-based damping alloys, the following problems arise.

[0005] (1) In the case where the atmosphere used for melting has a high partial oxygen pressure (PO2), an oxide (MnO) is yielded in a large amount through an oxidation reaction (Mn+O→MnO) because manganese has a high affinity for oxygen. Since this oxide inhibits the growth of a twin-crystal structure in the manganese-based damping alloys, the resultant damping alloys have reduced damping properties.

[0006] (2) In the case where the atmosphere used for melting has a low pressure (i.e., a high vacuum), the amount of manganese which vaporizes during the melting increases due to the high vapor pressure of manganese. This makes it difficult to stably obtain a manganese content in a given range.

[0007] (3) In case where the manganese-based alloys are melted at a temperature of 1,500° C. or higher, manganese vaporizes in a larger amount due to the high vapor pressure of manganese. Consequently, this case also results in unstable manganese contents.

[0008] (4) The oxide (MnO) yielded during melting is apt to form a low-melting eutectic structure. There is hence a possibility that the oxide might damage the refractory constituting the melting vessel to thereby considerably shorten its life or arouse a melt leakage trouble due to a local damage by fusion.

SUMMARY OF THE INVENTION

[0009] An object of the present invention is to eliminate the problems of related-art techniques described above and to provide a manganese-based damping alloy having stable damping properties. Another object of the present invention is to provide a process by which the damping alloy can be obtained without fail. Still another object of the present invention is to provide a damping part or vibration-proof product comprising or employing the damping alloy.

[0010] As a result of intensive investigations and researches made by the present inventors, the present invention has been achieved, which overcomes the problems described above, based on the idea that various conditions for melting should be fixed and impurities which come into manganese-based damping alloys should be diminished.

[0011] The present invention provides a damping alloy which comprises from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, 0.05 wt% or less carbon, 0.06 wt% or less oxygen, 0.06 wt% or less nitrogen, and manganese and unavoidable impurities as the remainder.

[0012] Due to the constitution described above, in which the contents of copper, nickel, and iron have been regulated within the given ranges and the carbon, oxygen, and nitrogen contents have been limited, not only manganese vaporization can be prevented from resulting in an increase in the relative concentration of carbon, oxygen, or nitrogen, but also it is possible to prevent an increase in oxygen content due to oxygen contamination, etc. As a result, the amount of nonmetallic inclusions (carbides, oxides, and nitrides) which are generated in the alloy is reduced and the alloy composition can be pure, whereby the formation of a twin-crystal structure during heat treatment is accelerated and factors which inhibit twin crystals from moving upon stress imposition are diminished. Thus, damping properties can be improved.

[0013] Consequently, the damping alloy can exhibit its damping properties even in a large-strain region and has stable mechanical strength. Therefore, a damping part which is nonmagnetic and excellent in formability/processability and in weldability or a vibration-proof product employing the damping part can be easily provided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] By way of example and to make the description more clear, reference is made to the accompanying drawing in which:

[0015] FIG. 1 is a diagrammatic view illustrating the melting step in the production process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Unless otherwise indicated, the content of the element is % by weight based on the total weight of the damping alloy (referred to as “wt%” hereinafter).

[0017] An explanation is given below on the range of the content of each component of the damping alloy.

[0018] Copper is contained in an amount of from 16.9 to 27.7 wt%. This is because copper contents lower than 16.9 wt% do not result in the formation of twin crystals, while copper contents exceeding 27.7 wt% result in a higher degree of copper segregation, making it impossible to attain desired damping properties. The more preferred range of copper content is from 19.7 to 25.0 wt%, and further preferably from 20.8 to 23.8 wt%.

[0019] Nickel is contained in an amount of from 2.1 to 8.2 wt%, the reasons for which are as follows. Addition of nickel as the third element in addition to manganese and copper gives desired damping properties. However, nickel contents lower than 2.1 wt% do not contribute to the formation of twin crystals. On the other hand, even when the nickel content is increased beyond 8.2 wt%, the effect of facilitating twin-crystal formation is not heightened any more.

[0020] Iron is contained in an amount of from 1.0 to 2.9 wt%, the reasons for which are as follows. Addition of iron as the fourth element in addition to manganese, copper, and nickel enables desired damping properties to be obtained. However, iron contents lower than 1.0 wt% do not contribute to the formation of twin crystals. On the other hand, even when the iron content is increased beyond 2.9 wt%, the effect of facilitating twin-crystal formation is not heightened any more.

[0021] The contents of carbon and nitrogen have been regulated to 0.05 wt% or lower and 0.06 wt% or lower, respectively. The reasons for this are as follows. In case where the content of carbon or nitrogen is higher than the upper limit, manganese vaporization results in an increase in the relative concentration of carbon or nitrogen, making it impossible to attain desired damping properties.

[0022] The content of oxygen has been regulated to 0.06 wt% or lower. This is because when the content of oxygen is higher than the upper limit, the damping alloy has increased MnO and oxygen contents due to oxygen contamination.

[0023] The present invention further provides a process for producing a damping alloy which includes a melting step in which a raw damping-alloy material comprising from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, and manganese and unavoidable impurities as the remainder is melted at a temperature in the range of from the temperature higher by 50° C. than the melting point of the alloy (from 960 to 1,140° C.) to 1,480° C. in an inert atmosphere having a partial oxygen pressure of 1,013.25 Pa (0.01 atm) or lower and a total pressure of 66,661 Pa or higher.

[0024] In this process, the formation of an oxide (MnO) can be inhibited because of the reduced partial oxygen pressure of the melting atmosphere and, hence, the growth of a twin-crystal structure can be accelerated. In addition, since the pressure of the inert gas constituting this atmosphere is regulated to a value within that range, manganese vaporization can be prevented and the content of this component can be stably regulated so as to be within the range specified above. Furthermore, since the heating temperature for melting is in the range of from the temperature higher by 50° C. than the melting point of the damping alloy to 1,480° C., manganese vaporization can be prevented and the content of this component can be stably regulated so as to be within the range specified above. Consequently, the damping alloy described above, which has reduced carbon, oxygen, and nitrogen contents, can be produced through melting without fail. The content of Mn is preferably from 63.5 to 77.5 wt%, more preferably 66.5 to 74.5 wt%.

[0025] Examples of the inert gas include argon, nitrogen, and mixtures of these. The degree of vacuum of 66,661 Pa corresponds to 500 Torr. The reason why the lower limit of the melting temperature is higher by 50° C. than the melting point of the alloy (from 960 to 1,140° C.) is that this lower limit enables the melting of alloys having the composition described above to be carried out at temperatures higher than the melting points thereof.

[0026] On the other hand, the upper limit of the melting temperature is 1,480° C. so as to inhibit manganese vaporization and prevent the formation of a eutectic of MnO with Al2O3. The more preferred range of the melting temperature is from 1,200 to 1,300° C. The process described above can include various steps to be conducted after the melting step. For example, the melting step may be followed by hot or cold forging, rolling, machining, and then heat treatment.

[0027] In the process of the present invention for producing a damping alloy, the melting step preferably comprises charging the raw damping-alloy material into a vessel comprising MgO—Al2O3 as a refractory and melting the raw material therein. In this process, since a vessel comprising a refractory (MgO—Al2O3), which is a spinel (AB2O4) type material less reactive with MnO, chemically stable, and excellent in thermal shock resistance and corrosion resistance, is used, the vessel is prevented from suffering a damage, wearing, or local damage by fusion and a stable melting operation can be conducted without fail.

[0028] The present invention furthermore provides a damping part or vibration-proof product which comprises or employs a damping alloy comprising from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, 0.05 wt% or less carbon, 0.06 wt% or less oxygen, 0.06 wt% or less nitrogen, and manganese and unavoidable impurities as the remainder, the alloy having been formed into a necessary shape. In this part or product, the damping alloy described above has been applied to a vibrating part. Accordingly, the part or product has a reduced frequency dependence and can exhibit damping properties even in a large-strain region. The alloy of the present invention preferably shows a logarithmic decrement of larger than 0.2 (exclusive).

[0029] For forming the damping alloy into a necessary shape, use may be made of, for example, a known metal working process in which the damping alloy produced through melting is subjected to casting, hot forging, or hot rolling and further to cold forging, cold rolling, pressing, cutting, etc. A combination of two or more of such forming steps may also be used. It is desirable to conduct heat treatment after these forming steps. For example, as the heat treatment, the alloy is maintained at &ggr; (austenite) range for several hours (2 to 3 hours) and then cooled at the cooling rate of 150° C./hr or less.

[0030] Embodiments of the damping part of the present invention described above include machine elements, tools for machining, bases or casings of metal working apparatus, spacers, liners, pipes, radiating plates, valves, engine parts, electronic parts, parts of sports goods, and fasteners for ducts or pipings.

[0031] Thus, damping parts capable of exhibiting the damping properties can be provided without fail.

[0032] Examples of the machine elements include bolts, nuts, screws, washers, bearings, springs, rotating shafts, and chains. Examples of the tools for machining include cutters, turning tools, shanks, and hammers. Examples of the metal working apparatus include lathes, milling machines, drilling machines, NC machines, and machining centers. Examples of the electronic parts include printed wiring boards, capacitors, transistors, IC chips, transformers, and motor parts. Examples of the engine parts include piston rings, piston rods, and fuel valves. Examples of the parts of sports goods include golf club heads, putter heads, and the frames of tennis or badminton rackets.

[0033] Embodiments of the vibration-proof product of the present invention described above include conveying apparatus, audio/video appliances (including appliances comprising at least either of an audio appliance and a video appliance), medical machines or apparatus, precision measuring instruments, sensors, transportation machines or apparatus, domestic electrical appliances, industrial machines or apparatus, air-conditioning machines or apparatus, computers, printers, copiers, building materials for openings, opening/closing devices, sports goods, and writing materials. Thus, vibration-proof products capable of exhibiting the damping properties can be provided without fail.

[0034] Examples of the conveying apparatus include various conveyors, escalators, elevators, hoists, and cranes. Examples of the audio/video appliances include amplifiers, tuners, various players for phonograph records, DVDs, or MDs, audio decks, video decks, speakers, microphones, headphones, various TVs, video cameras, digital cameras, and mobile telephones.

[0035] Examples of the medical machines or apparatus include various examination apparatus, various operation-supporting instruments, and dental remedial machines or apparatus. Examples of the transportation machines or apparatus include vehicles such as motor vehicles and electric railcars, ships, aircraft, and products to be disposed around the engines or driving units of these machines or apparatus (e.g., power steerings, column units, fuel injection control units, and cylinder blocks). Examples of the domestic electrical appliances include washing machines, refrigerators, electronic ovens, ovens, vacuum cleaners, dish washers, electric fans, and garbage-treating machines.

[0036] Examples of the industrial machines or apparatus include various pumps, motors, compressors, forklifts and fingers thereof, and chain saws. Examples of the air-conditioning machines or apparatus include air conditioners, outdoor heat exchangers, and heat medium ducts. Examples of the computers include various drives for hard disks or the like. Examples of the building materials for openings include automatic doors and revolving doors. Examples of the opening/closing devices include curtain-drawing devices for indoor use or for vehicles. Examples of the sports goods include baseball bats, tennis or badminton rackets, hockey sticks, oars for boats, ski poles, and goal posts and crossbars for soccer or hockey.

[0037] Preferred modes for carrying out the present invention will be explained below together with the drawing.

[0038] FIG. 1 illustrates the melting step in a production process for obtaining the damping alloy of the present invention.

[0039] A raw material for the damping alloy is prepared beforehand. This raw material comprises from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, and manganese and unavoidable impurities as the remainder.

[0040] On the other hand, a melting apparatus (induction heating vacuum furnace) 1 such as that shown in FIG. 1 is prepared. As shown in the figure, the melting apparatus 1 comprises: a metallic main body 2 which is airtight and has a nearly elliptic vertical section; a lid 3 placed on the main body 2; and a vessel 6 placed in the main body 2. A gas supply/exhaust pipe 5 connected to a vacuum pump or the like (not shown) is connected to the top of the lid 3. The vessel 6 has a cylindrical container part 7 which is circular when viewed from the top side thereof, as shown in FIG. 1. At least a surface layer of the container part 7 of this vessel 6 is made of a refractory comprising a spinel (AB2O4) type refractory (MgO—Al2O3) . A high-frequency induction coil 8 has been helically wound around the outer periphery of the vessel 6 at a given distance. This coil 8 has been connected to a high-frequency power source (not shown).

[0041] First, the raw material is charged into the container part 7 of the vessel 6. Thereafter, the lid 3 is placed on the top of the main body 2 to tightly close the inside 4 of the melting apparatus 1. After the apparatus 1 is evacuated, argon gas or the like is introduced into the inside 4 to regulate the inside 4 so as to constitute an inert atmosphere having a partial oxygen pressure of 1,013.25 Pa (0.01 atm) or lower and a total pressure of 66,661 Pa (corresponding to 500 Torr). Subsequently, a given high-frequency current is caused to flow through the high-frequency induction coil 8 to inductively heat the raw material in the container part 7. Thus, the raw material is heated beyond the melting point thereof and is melted to give a melt M. The melt M is kept in this molten state at a temperature in the range of from the temperature higher by 50° C. than the melting point of the alloy (from 960 to 1,140° C.) to 1,480° C. for a given time period.

[0042] During this heating period, the inside 4 of the melting apparatus 1, which contains the vessel 6, is maintained so as to be an inert atmosphere having a partial oxygen pressure of 1,013.25 Pa or lower and a total pressure of 66,661 Pa or higher. Because of this, the generation of a manganese oxide (MnO) is inhibited and manganese vaporization can be inhibited. Furthermore, since the temperature used for the melting is regulated so as to be in the range of from the temperature higher by 50° C. than the melting point of the damping alloy (from 960 to 1,140° C.) to 1,480° C., the formation of an MnO/Al2O3 eutectic structure, which may occur at around 1,500° C., can be prevented. Moreover, since that surface layer of the container part 7 in the vessel 6 which is in contact with the melt is made of a spinel refractory (MgO—Al2O3), the container part 7 is less apt to react with MnO. Consequently, the surface of the container part 7 is prevented from being rapidly damaged or worn or arousing a melt leakage trouble due to a local damage by fusion, whereby stable melting can be conducted.

[0043] Through the melting step described above, a nonmagnetic damping alloy of the present invention is obtained which comprises from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, 0.05 wt% or less carbon, 0.06 wt% or less oxygen, 0.06 wt% or less nitrogen, and manganese and unavoidable impurities as the remainder. This damping alloy not only exhibits damping properties even in a large-strain region because a twin-crystal structure is apt to generate, but also has improved mechanical strength and, hence, excellent formability/processability and excellent weldability. This damping alloy may be formed in an ordinary manner. Specifically, a melt of the alloy is cast with a given mold to obtain an ingot, which is subjected to hot forging or hot rolling and then to cold forging, cold rolling, pressing, extrusion forming, or the like. The resultant shape may be subjected to cutting, bending, drawing, compression, or the like according to need. Thus, the various damping parts mentioned above which each have a necessary shape and size and the various vibration-proof products mentioned above can be obtained.

[0044] Examples of the present invention will be explained below together with Comparative Examples for the purpose of comparison.

[0045] A raw manganese-based-alloy material was prepared which consisted of 22.4 wt% copper, 5.2 wt% nickel, 2.0 wt% iron, and manganese and unavoidable impurities as the remainder. Five-kilogram portions of this raw material were separately melted using the melting apparatus 1 described above and argon gas under the melting conditions shown in Table 1 to thereby obtain damping alloys of Examples 1 to 4.

[0046] Furthermore, the same raw material as that described above was melted in portions of the same weight for almost the same time period using the melting apparatus 1, etc. under the conditions shown in Table 1 to thereby obtain damping alloys of Comparative Examples 1 to 5. The contents of carbon, oxygen, and nitrogen in the damping alloy of each of the Examples and Comparative Examples produced through melting are also shown in Table 1. 1 TABLE 1 Melting conditions Partial Impurity con- oxygen Melting tents of Mn—Cu— Mn pres- Pres- temper- Ni—Fe alloy con- sure sure ature (wt %) tent (Pa) (Pa) (° C.) Refractory C O N (wt %) Ex. 1 510 66700 1200 MgO—Al2O3 0.02 0.01 0.01 69.4 Ex. 2 1010 106700 1300 MgO—Al2O3 0.03 0.03 0.03 70.5 Ex. 3 1010 66700 1300 MgO—Al2O3 0.02 0.05 0.05 69.5 Ex. 4 1010 66700 1450 MgO—Al2O3 0.03 0.06 0.06 69.0 Comp. Ex. 1 10130 66700 1300 MgO—Al2O3 0.05 0.45 0.01 69.2 Comp. Ex. 2 1010 13300 1300 MgO—Al2O3 0.13 0.21 0.14 65.4 Comp. Ex. 3 1010 66700 1600 MgO—Al2O3 0.15 0.18 0.12 66.3 Comp. Ex. 4 1010 66700 1300 MgO 0.01 0.31 0.01 67.9 Comp. Ex. 5 1010 66700 1300 Al2O3 0.01 0.26 0.01 68.1

[0047] The damping alloy ingots of the respective Examples and Comparative Examples were separately subjected to forging, rolling, machining, and then heat treatment to obtain tensile test pieces having a shape as provided for in JIS. These test pieces were separately subjected to a tensile test in accordance with JIS Z 2241.

[0048] With respect to damping properties (vibration damping capacity), sheet samples having a thickness of 1 mm, width of 10 mm, and length of 160 mm were produced for the respective Examples and Comparative Examples separately from the test pieces described above and were examined for logarithmic decrement (&dgr;), which is a measure of damping properties, by the center vibration method at room temperature.

[0049] In Table 2 are shown the found values of tensile strength (&sgr;B/MPa) obtained in the tensile test for each of the Examples and Comparative Examples and the found values of logarithmic decrement (&dgr;) determined by the center vibration method.

[0050] The values of logarithmic decrement were obtained when the amplitude distortion was 5×10−4. 2 TABLE 2 Tensile Damping property Evalu- strength Evalu- (logarithmic decrement) ation (MPa) ation Example 1 0.27 ◯ 540 ◯ Example 2 0.26 ◯ 525 ◯ Example 3 0.25 ◯ 510 ◯ Example 4 0.22 ◯ 505 ◯ Comparative 0.20 &Dgr; 295 X Example 1 Comparative 0.15 X 310 X Example 2 Comparative 0.12 X 325 X Example 3 Comparative 0.18 &Dgr; 300 X Example 4 Comparative 0.19 &Dgr; 315 X Example 5

[0051] Table 2 shows that the damping alloys of Examples 1 to 4 had excellent damping properties and a tensile strength as high as 500 MPa or above.

[0052] In Comparative Example 1, on the other hand, MnO generated in a large amount because of the high partial oxygen pressure during melting. In addition, the alloy had an increased oxygen content due to oxygen contamination. As a result, the alloy of Comparative Example 1 had slightly reduced damping properties and a reduced tensile strength. In Comparative Example 2, manganese vaporization occurred in an increased amount because the melting was conducted at a low pressure (at a high vacuum), resulting in increased carbon, oxygen, and nitrogen contents. As a result, the alloy of Comparative Example 2 was reduced in both damping properties and tensile strength.

[0053] In Comparative Example 3, manganese vaporization occurred in an increased amount because of the too high melting temperature, resulting in increased carbon, oxygen, and nitrogen contents. Because of this, Comparative Example 3 gave the same results as in Comparative Example 2.

[0054] Furthermore, in Comparative Examples 4 and 5, the refractory constituting the vessel 6 in the melting apparatus 1 consisted only of magnesia (MgO) or alumina (Al2O3) , respectively. Because of this, these refractories were damaged by fusion. As a result, oxygen in each refractory and manganese formed an oxide to cause oxygen contamination, resulting in an increased oxygen content. Consequently, the alloys of Comparative Examples 4 and 5 had slightly reduced damping properties and a reduced tensile strength.

[0055] The effects of those damping alloys according to the present invention and of the process for producing these through a melting step were ascertained from the results given above, and the advantages thereof were demonstrated.

[0056] The present invention should not be construed as being limited to the modes and the Examples described above.

[0057] When the damping alloy of the present invention is subjected to heat treatment after the forming step described above, a damping part or vibration-proof product in which excellent damping properties have been actualized can be obtained.

[0058] The damping part of the present invention, which has been obtained by imparting a necessary shape to the damping alloy of the present invention, is nonmagnetic. Because of this, even when an electronic control circuit or magnetic sensor is used around the damping part, the part neither adversely influences the circuit or sensor nor brings about an operation error.

[0059] In the production process of the present invention, the apparatus to be used for the melting is not limited to the melting apparatus (induction heating vacuum furnace) 1 described above. It is possible to conduct the melting step using a vacuum (reduced-pressure) arc heating furnace, a vacuum (reduced-pressure) floatation melting furnace in which the melt does not come into contact with the refractory, or a vacuum (reduced-pressure) semi-floatation melting furnace.

[0060] Furthermore, examples of the writing materials as an embodiment of the vibration-proof product include a mechanical pencil or ball-point pen which employs the damping alloy as the case or as an inner component, and further include a fountain pen employing the damping alloy also as the nib.

[0061] The present invention can be suitably modified as long as this is not counter to the spirit of the present invention.

[0062] As described above, the damping alloy of the present invention has the following advantages. Since the contents of copper, nickel, and iron have been regulated so as to be within the given ranges and the carbon, oxygen, and nitrogen contents have been limited, manganese vaporization can be prevented from resulting in an increase in the relative concentration of carbon, oxygen, or nitrogen or from causing oxygen contamination. Consequently, the amount of nonmetallic inclusions (carbides, oxides, and nitrides) which generate in the alloy is reduced and the alloy composition can be pure. As a result, the formation of a twin-crystal structure during heat treatment can be accelerated and factors which inhibit twin crystals from moving upon stress imposition can be diminished. Thus, damping properties can be improved. Therefore, various kinds of vibrations can be damped without fail.

[0063] On the other hand, the process of the present invention for producing a damping alloy has the following advantages. The formation of an oxide can be inhibited because of the reduced partial oxygen pressure of the melting atmosphere and, hence, the growth of a twin-crystal structure can be accelerated. In addition, since the pressure of the inert gas constituting this atmosphere is regulated to a value within the range specified above, manganese vaporization can be prevented and the content of this component can be stably regulated so as to be within the range specified above. Furthermore, since the heating temperature for melting is regulated so as to be in the range specified above, manganese vaporization can be prevented and the content of this component can be stably regulated so as to be within the range specified above. Consequently, a damping alloy which has reduced carbon, oxygen, and nitrogen contents and has excellent damping properties can be produced through melting without fail.

[0064] According to the preferred embodiment of the process of the present invention for producing a damping alloy, since a vessel comprising a refractory (MgO—Al2O3), which is a spinel type material less reactive with MnO, chemically stable, and excellent in thermal shock resistance and corrosion resistance, is used, the vessel is prevented from suffering a damage, wearing, or local damage by fusion and a stable melting operation can be conducted without fail.

[0065] Furthermore, the damping part and vibration-proof product of the present invention, in which the damping alloy has been applied to a vibrating part, can exhibit damping properties even in a large-strain region due to the movement of a twin-crystal structure.

[0066] While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the scope thereof.

[0067] This application is based on Japanese patent application No. 2002-057084 filed Mar. 4, 2002, the entire contents thereof being hereby incorporated by reference.

Claims

1. A damping alloy which comprises from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, 0.05 wt% or less carbon, 0.06 wt% or less oxygen, 0.06 wt% or less nitrogen, and manganese and unavoidable impurities as the remainder.

2. A process for producing a damping alloy which comprises a step by melting a raw damping-alloy material comprising from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, and manganese and unavoidable impurities as the remainder at a temperature in the range of from the temperature higher by 50° C. than the melting point of the alloy to 1,480° C.

in an inert atmosphere having a partial oxygen pressure of 1,013.25 Pa or lower and a total pressure of 66,661 Pa or higher.

3. The process for producing a damping alloy of claim 2, wherein in the melting step, the raw damping-alloy material is charged into a vessel comprising MgO—Al2O3 as a refractory and is melted therein.

4. A damping part or vibration-proof product which comprises a damping alloy comprising from 16.9 to 27.7 wt% copper, from 2.1 to 8.2 wt% nickel, from 1.0 to 2.9 wt% iron, 0.05 wt% or less carbon, 0.06 wt% or less oxygen, 0.06 wt% or less nitrogen, and manganese and unavoidable impurities as the remainder, said alloy having been formed into a necessary shape.

5. The damping part of claim 4, which is one member selected from the group consisting of machine elements, tools for machining, bases or casings of metal working apparatus, spacers, liners, pipes, radiating plates, valves, engine parts, electronic parts, parts of sports goods, and fasteners for ducts or pipings.

6. The vibration-proof product of claim 4, which is one member selected from the group consisting of conveying apparatus, audio/video appliances, medical machines or apparatus, precision measuring instruments, sensors, transportation machines or apparatus, domestic electrical appliances, industrial machines or apparatus, air-conditioning machines or apparatus, computers, printers, copiers, building materials for openings, opening/closing devices, sports goods, and writing materials.