JPH0699768B2 - Ni-base alloy and manufacturing method thereof, and Ni-base alloy rotating electric machine damper and retaining ring - Google Patents

Description

The present invention relates to a non-magnetic, low electric resistance, high strength, high toughness Ni-base alloy and a method for producing the same, and is formed by this Ni-base alloy. The present invention relates to a damper and a retaining ring of a rotating electric machine (generator, motor, etc.).

[Conventional technology]

Conventionally, dampers and retaining rings for rotating electrical machines such as generators and electric motors require materials that have a good balance of magnetism, electric resistance, strength, and toughness.
An Al-based alloy was used. However, since this alloy is a Ni-based alloy containing Cu, it is difficult to weld this to an Fe alloy member, and steelmakers do not like melting the alloy containing Cu from the viewpoint of furnace contamination. Therefore, it is the current situation to search for alloys with the required properties from alloy systems that do not contain Cu.

Therefore, there are the following patents for Ni-based alloys that do not contain Cu. For example, in JP-A-60-89537, "Metal member having excellent erosion resistance", Ni and or Co, Cr: 0.1 ~
6%, Al: 0.1-5%, Ti: 0.1-6%, Si: 0.5-6%, Zr: 0.1
~ 6%, Hf: 0.1 ~ 6% (both by weight) 1 of the group
A Ni-based alloy containing at least one species is disclosed, which is an Ni-based alloy in which an oxide is dispersed and precipitated by an internal oxidation treatment to impart erosion resistance. Further, in JP-A-58-96845, "Nickel-based alloy sheet and method for producing the same", Ni: Al: 2-9
%, Ti: 0 to 6%, Mo: 0 to 16%, Ta: 0 to 12%, W: 0 to 12%, Nb: 0
~ 4%, Cr: 0 ~ 20%, Co: 0 ~ 20%, C: 0 ~ 0.3%, Y: 0 ~ 1%,
A Ni-based alloy containing B: 0 to 0.3%, Zr: 0 to 0.3%, V: 0 to 2%, and Re: 0 to 5% is disclosed. After hot working under specific conditions, cold working is performed. It is a Ni-based alloy sheet having a fibrous structure with a large number of (110) <112> crystals by performing cross rolling.
However, although there are Ni-based alloys that do not contain Cu as described above, no consideration was given to magnetism and electric resistance in the prior art. Among conventional Ni-based alloys, A2
Although alloys such as 8b and Inconel 706 are non-magnetic and have high strength, they have a problem that their electric resistance is too high.

[Problems to be solved by the invention]

In the conventional technology, each component of the Ni-based alloy containing no Cu is magnetic,
No consideration is given to the effect on electric resistance. Therefore, it cannot be applied to the members such as dampers and retaining rings of rotating electric machines (generators, motors, etc.) that require materials with well-balanced properties of non-magnetic, low electrical resistance, high strength and high toughness. There was a problem.

Therefore, an object of the present invention is to provide a Ni-based alloy having a well-balanced non-magnetic property, low electric resistance, high strength, and high toughness, which is suitable as a material for a damper and a retaining ring of a rotating electric machine (generator, electric motor, etc.). To do.

[Means for solving problems]

In order to achieve the above object, it is necessary to first clarify the relationship between each characteristic and the alloy component, and then it is necessary to optimize the amount of the alloy component so as to satisfy the target of each characteristic. is necessary. Without optimization, one property of the alloy, for example a specific resistance, can be obtained at a sufficiently low value, while another property, for example, the Curie point, becomes too high. In the case of materials used for dampers and retaining rings of rotating electrical machines (generators, motors, etc.), optimizing the alloying components is an alloy that has well-balanced properties of magnetism, electrical resistance, strength, and toughness. This means selecting the components, and the following Ni-based alloys are suitable. That is,
The Ni-based alloy of the present invention contains Cr: 1 to 5%, Al: 3 to 7% by weight,
Ti: 0.2 to 1.0%, C: 0.05 to 0.3%, Si or Mn alone or in combination: 0.
01-1.0% and at least one of Mg, Zr, and B: 0.005-0.05%, the balance is Ni, is an alloy with γ-prime phase, the Curie point is 0 ° C or less, and the specific resistance is 70 μΩcm or less, 0.
2% proof stress is 60kgf / mm ² or more, and absorbed energy is 5kgf ・
It is an alloy of m or more.

In addition, the manufacturing method of the above Ni-based alloy is such that the alloy of the above components is melted and manufactured (melted), then forged, and then the temperature is set to 800 ° C.
This is a manufacturing method in which the solution treatment is performed, and then the aging treatment is performed at a temperature in the range of 450 to 650 ° C. to precipitate the γ-prime phase.

Further, the Ni-based alloy is used for a damper of a rotating electric machine (generator, electric motor, etc.) and a member such as a retaining ring.

Hereinafter, the Ni-based alloy will be further described in detail. A method of alloy design combining experimental and mathematical methods is used to determine the amount of each component. That is, the contents of Cr, Al, Ti, C, Si, and Mn are systematically changed to experimentally produce a Ni-based alloy,
Obtain 30 kinds of 4kg vacuum melting ingots and perform predetermined processing and heat treatment. That is, after forging at 1100 to 800 ° C, water-cooled solution treatment at 950 ° C for 1 hr, followed by two-step aging treatment, 550 ° C, 30
Each Ni-based alloy is obtained by carrying out hr and 500 ° C for 30 hr.

The basic data is created by measuring the magnetic properties, electrical resistance, strength, and toughness of each Ni-based alloy. From the basic data, the relationship between each property and alloy composition is calculated by the statistical method of regression analysis, and empirical formulas for magnetism, electric resistance, strength and toughness are obtained. The present inventors obtained the following four formulas I-IV as the result of the experiment.

Curie point (℃) = 353-46 (Cr) -57 (Al) + 5 (T
i) +80 (C) -77 (Si) -13 (Mn) ...... (I) Specific resistance (μΩcm) = 6.8 + 6.2 (Cr) +6.3 (Al) +4 (T
i) +15 (C) +8 (Si) +2 (Mn) ...... (II) 0.2% proof stress (kgf / mm ² ) = 22-2 (Cr) +6 (Al) +30
(Ti) +100 (C) +1 (Si) +1 (Mn) (III) Absorbed energy (kgf ・ m) = 90-1.5 (Cr) -6 (Al)-
20 (Ti) -200 (C) -5 (Si) -5 (Mn) ... (IV) However, (Cr), (Al), (Ti), (C), (Si), (M
n) and the like are weight% of each element.

Next, set a target value for each of I to IV, that is, the Curie point is 0 ° C or less, the specific resistance is 70 μΩcm or less, the 0.2% proof stress is 60 kgf / mm ² or more, and the absorbed energy is 5 kgf · m or more. The equation was used and the solution was obtained. Then, after selecting some alloy components that satisfy the solution and experimentally producing the alloy (that is, the alloy described later in the example) and confirming that the target characteristics can be obtained, finally the optimum The following range was obtained as the range of alloyed alloy components.

(Cr): 1 to 5% by weight (Al): 3 to 7% by weight (Ti): 0.2 to 1.0% by weight (C): 0.05 to 0.3% by weight (Si + Mn): 0.01 to 1.0% by weight The relation with each characteristic value is described. Figure 1 shows Si
= 0.2%, Mn = 0.2%, C = 0.15%, Ti = 0.4% (all are wt%), the range of Cr and Al component amounts (wt%) satisfying the respective characteristics is shown by diagonal lines. The straight line 1 indicates the Curie point 0 ° C., the upper part of this line is the Curie point 0 ° C. or lower, the straight line 2 indicates the specific resistance of 70 μΩcm, and the lower part of the straight line indicates the specific resistance of 70 ° C.
μΩcm or less, the straight line 3 shows 0.2% proof stress 60 kgf / mm ² , and the line above this line is 0.2% proof stress 60 kgf / mm ² or more,
The straight line 4 shows the absorbed energy of 5 kgf · m, and below the straight line is the absorbed energy of 5 kgf · m or more. Therefore each straight line
The composition of components in the shaded area surrounded by 1,2,3,4 satisfies each characteristic. The numbers in the circles represent the trial numbers in Table 1 described later. Similarly, FIG. 2 shows that Si = 0.2%, Mn = 0.2%, C = 0.05%,
C that satisfies each characteristic when Ti = 1.0% (all are weight%)
The range of the component amounts (% by weight) of r and Al is indicated by diagonal lines. Straight line 1,2,
The numbers in 3, 4, and ○ are the same as in FIG. As can be seen from these figures, the characteristics of the resistivity and the Curie point
The proper composition range of Cr and Al is largely restricted.

[Action]

As described above, the present inventors have found that Ni--Cr--Al--Ti--C--Si.
In the -Mn alloy system, the effects (effects) of the constituent elements on the Curie point, the specific resistance, the 0.2% proof stress, and the absorbed energy for each property of magnetism, electric resistance, strength, and toughness were investigated. The effect of each element on the properties is clear from equations I-IV.

Cr reduces the Curie point, 0.2% proof stress, absorbed energy, and increases the specific resistance. Therefore, Cr is an element that works effectively only in terms of magnetism. Moreover, Cr is 1% (weight%,
The same applies hereinafter), the Curie point decreases to 0 ° C. or lower and exhibits ferromagnetism at room temperature, and if it exceeds 5%, 0.2% proof stress and absorbed energy decrease and the mechanical strength decreases. A range of 5% is suitable.

Al lowers the Curie point and absorbed energy to increase the specific resistance and 0.2% proof stress. Therefore, Al is an element that works effectively for magnetism and strength. Al enhances the strength because the aging treatment forms a γ-prime phase (Ni ₃ Al). The γ-prime phase consists of about 100Å fine particles that can be observed with a transmission electron microscope, and contributes to high strength. Further, if Al is less than 3%, 0.2% proof stress is reduced and the Curie point is not lowered, and if it is more than 7%, absorbed energy is lowered, so that the range of 1 to 7% is suitable.

Ti increases the Curie point, the specific resistance and the 0.2% proof stress, and reduces the absorbed energy. Therefore, Ti is an element that works effectively only in terms of strength. If Ti is less than 0.2%, 0.2% proof stress will be small, and if it is more than 1.0%, the Curie point will not be lowered, absorbed energy will be reduced, and specific resistance will be large, so the range of 0.2 to 1.0% is suitable. .

C, like Ti, has higher Kuriy point, specific resistance and 0.2% proof stress.
Reduces absorbed energy. Therefore, C is an element that works effectively only in terms of strength. When C is less than 0.05%, 0.2% proof stress is reduced, and when it is more than 0.3%, the Curie point is not lowered, absorbed energy is lowered, and specific resistance is increased, so that the range of 0.05 to 0.3% is suitable. .

Similar to Al, Si and Mn lower the Curie point and absorbed energy, and increase the specific resistance and 0.2% proof stress. Therefore, Si and Mn play an effective role in magnetism and strength, and contribute to the deoxidizing effect during the melt production of the alloy. 0.01 with Si and Mn alone or in combination
If it is less than 1.0%, the Curie point will not be lowered, and the deoxidizing effect will not be sufficient, and if it is more than 1.0%, the specific resistance will be high and the absorbed energy will be lowered, so the range of 0.01 to 1.0% is suitable.

In order to improve the hot workability of the alloy, one or more grain boundary strengthening elements such as Mg, Zr, and B are added, but if it is less than 0.005%, it does not contribute to the hot workability and 0.05%. The range of 0.005 to 0.05% is suitable because the effect is not increased so much even if it is increased.

Further, since the added amounts of these elements are very small, their influences on the properties of magnetism, electric resistance, strength and toughness are neglected.

As described above, the Ni-based alloy of the present invention is easy to forge-mold, and has non-magnetism, low electric resistance, high strength, and high toughness. Therefore, the damper of the rotor of the rotating electric machine, particularly the superconducting generator and the retaining ring of the electric motor. It is suitable as a member.

In the case of a damper, the Ni-based alloy damper of the present invention is non-magnetic, has good electrical conductivity, and has high strength even if the electric power system causes an accident and the current in the armature winding fluctuates. It is possible to prevent the fluctuation of the child magnetic flux from interlinking with the field winding and prevent the rotor from being damaged by the electromagnetic force. The same effect can be obtained in the case of a retaining ring.

〔Example〕

Example 1 As shown in trial numbers 1 to 10 in Table 1, Ni, Cr, Al, Ti, C, Si, M
An alloy of each composition containing n and each of Mg, B, and Zr was melted in a vacuum of 4 kg. Next, after forging at 1100 ~ 800 ℃, 950 ℃, 1 hour water-cooled solution treatment, 550 ℃, 3
Two-step aging treatment at 0 ° C for 30 minutes at 500 ° C followed by γ-
A Ni-based alloy was obtained by generating a prime phase.

The Kuriy point, the specific resistance, the 0.2% proof stress, and the absorbed energy of each of the obtained Ni-based alloys of the sample numbers were measured, and the respective characteristic values are shown in Table 2. Also, as a comparison, A2 of conventional alloy A
86, each component composition of Inconel 706 of Conventional Alloy B is shown in Table 1, and each characteristic value is shown in Table 2. From Table 2, the Ni-based alloy of the present invention has lower specific resistance and higher absorbed energy than the conventional alloy. From this, it can be seen that the Ni-based alloy of the present invention is excellent in good conductivity and toughness, and also has sufficient non-magnetism and strength.

Also, the numbers of the trial numbers in Tables 1 and 2 are the same as those in Figures 1 and 2
Corresponds to the circled numbers in the diagonal lines surrounded by curves 1, 2, 3, and 4 in the figure. From FIGS. 1 and 2, it can be seen that the Ni-based alloy of the present invention satisfies all the characteristic values.

Example 2 An example of obtaining a damper for a rotor of a superconducting generator using the Ni-based alloy of the present invention will be shown. FIG. 3 is a sectional view showing the structure of the rotor of the superconducting generator. This is in a rotating field type superconducting generator. The rotor has a multi-concentric hollow cylindrical structure, and a damper 11, a heat radiation shield 9 (about 50 ° C. higher than the liquefaction temperature of liquid helium) from the outside, a superconducting coil cover 8, a superconducting coil bind 7, a superconducting coil. 2. A torque tube 6 for accommodating the superconducting coil 2, a cooling helium flow path 5, a shaft 10, a current lead wire 1, a liquid helium 4, and a liquid helium introducing pipe 3. The liquid helium is pressed against the wall of the torque tube 6 by the centrifugal force of rotation and becomes a cylindrical shape as shown in the figure. Both the heat radiation shield 9 and the damper 11 are evacuated.

In a large-capacity generator, the current in the armature winding fluctuates during a power system failure. If the damper 11 is not provided at this time, the braking force is exerted by the interaction between the magnetic flux generated by the armature winding and the field current, so that the rotor is attenuated and out of synchronization.
Out of synchronization, the armature current fluctuates more significantly, and excessive thrust and braking force are alternately generated in the rotor, resulting in fatal damage to the power system and the generator.

Thus, the damper 11 is provided to prevent the rotor from being out of synchronization. In other words, the damper 11 is for preventing the fluctuation of the armature magnetic flux from interlinking with the field winding, and is for passing an eddy current in the conductor to attenuate the magnetic flux density. 120H for armature flux
There is a z component and a low frequency component of 0.5 to 2 Hz that accompanies the vibration of the rotor. The former is shielded by a damper and the latter is shielded by a heat radiation shield. At this time, due to the interaction between the armature magnetic flux and the eddy current of the damper, a rotational vibration braking force and a strong electromagnetic force are generated in the damper 11.

Therefore, the material used for the damper must have good conductivity and high strength. Further, it is required to be non-magnetic for the following reasons. That is, the magnetic flux density of the superconducting coil is extremely high, but if a ferromagnetic substance is present between the superconducting coil and the armature winding, the magnetic saturation phenomenon of the magnetic substance reduces the effectively usable magnetic flux.

As mentioned above, the damper generates rotational vibration braking force and strong electromagnetic force, but it is non-magnetic and has a specific resistance below the Curie point 0 ° C.
Since the damper is made of a Ni-based alloy with good conductivity of 70 μΩcm or less, high strength of 0.2% proof stress of 60 kgf / mm ² or more, and high toughness of absorbed energy of 5 kgf · m or more, electromagnetic waves entering the superconducting coil from the outside are completely shielded. Also, it can endure the strength enough to enhance the safety of the rotor. Moreover, this Ni-based alloy is easy to forge, and a long hollow cylinder can be formed by forging.

Example 3 An example in which a retaining ring for a rotor of a conventional electric motor was obtained from the Ni-based alloy of the present invention will be shown. FIG. 4 is a plan view of a schematic structure of a conventional electric motor. The electric motor comprises a stator core 21 in which thin iron plates are laminated and a rotor 22 provided on the inner diameter side thereof with a gap therebetween. FIG. 5 is an enlarged view of part A of FIG.
Fig. 6 shows a partial cross section near the end of the rotor 22, and Fig. 6 shows the rotor.
22 shows a perspective view of FIG. The rotor 22 is mainly composed of an iron core portion 22a and a field winding 26, and the iron core portion 22a is provided with a groove in the axial direction and a part of the field winding 26 is inserted. The damper winding 25 is inserted on the field winding 26,
The field winding straight portion 26a, that is, the portion housed in the groove of the iron core, is fixed and held by the wedge 24. Also, the end of the field winding
26b, that is, the portion protruding from the iron core is fixedly held by the retaining ring 23. This retaining
The ring has the non-magnetic property, low resistivity, high strength and high toughness of the present invention.
Made of Ni-based alloy. Therefore, the safety of the rotor can be enhanced as in the case of the second embodiment.

〔The invention's effect〕

According to the present invention, Ni in the specific component amount of Cr, Al, as described above,
Ni-based alloys are manufactured by adding Ti, C, Si, Mn and, if necessary, Mg, Zr, B, so that Ni-based alloys with well-balanced properties, that is, non-magnetic with a Kurye point below 0 ° C Resistivity is 70μΩ
Good conductivity of cm or less 0.2% High strength of 0.2% proof stress of 60 kgf / mm ² or more,
An excellent Ni-based alloy having high toughness with absorbed energy of 5 kgf · m or more can be obtained. Further, the damper and the retaining ring of the rotary electric machine (generator, electric motor, etc.) made of the Ni-based alloy of the present invention can withstand severe electrical and mechanical conditions, and can keep the rotary electric machine safe.

[Brief description of drawings]

Fig. 1 shows the composition of Cr and Al that satisfy the target values of the Curie point, resistivity, 0.2% proof stress, and absorbed energy when Si = 0.2%, Mn = 0.2%, C = 0.15%, Ti = 0.4%. A graph showing the range.
Fig. 2 shows the composition of Cr and Al that satisfy the target values of the Curie point, resistivity, 0.2% proof stress and absorbed energy when Si = 0.2%, Mn = 0.2%, C = 0.05% and Ti = 1.0%. A graph showing the range.
FIG. 3 is a cross-sectional view of the rotor of the superconducting generator, FIG. 4 is a plan view of the schematic structure of a conventional electric motor, and FIG. 5 is an enlarged view of part A of FIG. 6 and 6 are perspective views of the rotor shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Current lead wire, 2 ... Superconducting coil, 3 ... Liquid helium introducing tube, 4 ... Liquid helium, 5 ... Cooling helium channel, 6 ... Torque tube, 7 ... Superconducting coil bind,
8 ... Superconducting coil cover, 9 ... Heat radiation shield, 10 ... Shaft, 11 ... Damper, 21 ... Stator core, 22 ... Rotor,
22a ... iron core, 23 ... retaining ring, 24 ... wedge, 25
… Damper winding, 26… Field winding.

Claims (4)

[Claims] 1. A Ni-based alloy, Cr: 1-5% by weight, Al: 3-
7%, Ti: 0.2 to 1.0%, C: 0.05 to 0.3%, single or composite of Si and Mn: 0.01 to 1.0%, and one or more of Mg, Zr and B: 0.005 to 0.05
%, With the balance being Ni, having a γ-prime phase, a Curie point of 0 ° C. or less, a specific resistance of 70 μΩcm or less, a 0.2% proof stress of 60 kgf / mm ² or more, and an absorbed energy of
A Ni-based alloy characterized by having a weight of 5 kgf · m or more. 2. By weight%, Cr: 1-5%, Al: 3-7%, Ti: 0.2-
1.0%, C: 0.05 to 0.3%, Si or Mn single or composite: 0.01 to 1.0
%, And one or more of Mg, Zr, and B: 0.005 to 0.05%, the balance is Ni, the alloy having the composition of Ni is melted, and then forged.
After that, solution heat treatment at a temperature of 800 ℃ or more, then temperature 450
A method for producing a Ni-based alloy, characterized by precipitating a γ-prime phase by aging treatment in the range of up to 650 ° C. 3. A rotary electric machine damper comprising the Ni-based alloy according to claim 1. 4. A rotating electrical machine retaining ring comprising the Ni-based alloy according to claim 1.