JPH05112847A - Rotor shaft for rotary electric machine, its manufacture and rotary electric machine using the above - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a rotor shaft for a rotary electric machine having high strength, high toughness, and high magnetic characteristics, a manufacturing method thereof, and a large-capacity rotary electric machine using the same. is there. [Structure] The present invention is, by weight, C 0.15 to 0.30%, S
i 0.1% or less, Mn 1% or less, Ni 3.0 to 5.0%, C
r2.0-3.0%, Mo0.1-1.0%, V0.03-
A rotor shaft for a rotary electric machine, characterized in that 0.35% and the balance being substantially Fe. Furthermore, Al0.
01% or less, the total amount of P, S, Sn, Sb, As is 0.0
The content of the group IIa element and the group IIIa element may be 0.1% or less, and the group IVa element, Nb, Ta and W may be 0.2% or less. As a result, a large-capacity generator having a capacity of 900 MVA or more and an electric motor having a rotation speed of 5000 rpm or more are manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel rotor shaft for a rotary electric machine, a manufacturing method thereof, a rotary electric machine using the same, and a low alloy steel.

[0002]

2. Description of the Related Art As a rotor shaft material of a turbine generator having a capacity of up to 800 MVA, ASTM standard material Ni-Cr-
Mo steel (A469-88, Class 6-8) is used. In recent years, from the viewpoint of energy diversification, there is a tendency for turbine generators to have large capacities due to the demand for switching to coal-fired power, which is an alternative energy for petroleum, and effective utilization of power source site area.

With the increase in capacity of turbine generators, the operating conditions of the rotor shaft become stricter, and the above-mentioned AST in operation is used.
The strength of the M standard material has become insufficient.

Generally, as the strength increases, the toughness tends to decrease. Therefore, it is desired to develop a rotor shaft material having higher strength and higher toughness than the current material.

ASTM standard class 6-8 is C0.28%
Below, Mn 0.60% or less, P 0.015% or less, S0.01
5% or less, Si 0.15 to 0.30%, Ni 3.25 to 4.
00%, Cr 1.25 to 2.00%, Mo 0.30 to 0.6
0%, V0.05-0.15%, the balance consisting essentially of Fe, Class 8 has the highest strength, tensile strength 84kg / mm ² or more, 0.02% proof strength 70.4kg / mm ² or more, elongation rate 16% or more, drawing rate 45% or more, 50% fracture surface transition temperature 4 ° C or less are specified.

Japanese Patent Publication No. 47-25248 discloses C0.14.
~ 0.20%, Si0.05-0.4%, Mn0.1-0.1.
6%, Ni 1.5 to 2.8%, Cr 0.75 to 1.8%, M
o 0.1 to 0.5%, V 0.01 to 0.12% and balance Fe
A low alloy steel for a generator rotor shaft is shown.

Japanese Patent Publication No. 60-230965 discloses C0.13.
-0.30%, Si 0.10% or less, Mn 0.60-2.
00%, P0.010% or less, Cr 0.40 to 2.00
%, Ni 0.20 to 2.50%, Mo 0.10 to 0.50
%, V 0.05 to 0.15%, Al 0.005 to 0.04
%, N 0.0050 to 0.0150%, Ni + 2 Mn + 2
A low alloy steel for a turbine generator shaft is shown, in which Cr is 4 to 8% and the balance is Fe.

[0008]

A rotor shaft material for a generator having a capacity of 900 MVA or more has a tensile strength of 93 kg.
/ Mm ² or more, 0.02% Proof strength 74 kg / mm ² or more, Fracture transition temperature (hereinafter abbreviated as FATT) Mechanical property of 0 ° C or less and magnetic property of magnetizing force of 990 AT / cm or less at 21,000 gauss are required. It

Further, as a rotor shaft material of a 1200 MVA class generator, a tensile strength of 100 kg / mm ² or more 130
As a rotor shaft material for a 0MVA class generator, a tensile strength of 104 kg / mm ² or more is required.

In the ASTM standard material (A469-Class 8) and those disclosed in the prior art, the tensile strength is ≧ 84.1k.
g / mm ² , 0.02% yield strength ≧ 70.4 kg / mm ² , FATT ≦
The temperature is 4 ° C., and the strength and toughness of the rotor shaft material for a generator having 900 MVA or more are insufficient, and safety against fracture cannot be secured.

Further, if the conventional strength is increased, the toughness decreases,
No material satisfying both strength and toughness was obtained.

An object of the present invention is to provide a rotor shaft for a rotary electric machine having high strength, high toughness and high magnetic characteristics, a method for manufacturing the rotor shaft, and a large-capacity rotary electric machine using the same.

[0013]

The present invention is based on C by weight.
0.15 to 0.30%, Si 0.1% or less, Mn 1% or less,
Ni3.0-5.0%, Cr2.0-3.0%, Mo0.1
.About.1.0%, V0.03 to 0.35%, and the balance being substantially Fe.

The present invention, by weight, has a C of 0.15 to 0.35.
%, Si 0.1% or less, Mn 1% or less, Ni 3.0 to 5.0
%, Cr 1.5-3.5%, Mo 0.1-1.0%, V0.
In the rotor shaft for a rotary electric machine, the content is 03 to 0.35% and the balance is substantially Fe, and the (Ni / Cr) ratio is 1.2 to 2.0.

The present invention, by weight, has a C of 0.15 to 0.30.
%, Si 0.3% or less, Mn 1% or less, Ni 3.0 to 5.0
%, Cr 2.05-3.0%, Mo 0.1-1.0%, V
A rotor shaft for a rotary electric machine is characterized in that it is 0.03 to 0.35%, A 10.06% or less and the balance is substantially Fe.

The present invention is based on the above-mentioned Ni-Cr-Mo-V.
A rotor shaft for a rotary electric machine, characterized in that the steel has a tensile strength at room temperature of 93 kg / mm ² or more, a 50% fracture surface transition temperature of 0 ° C. or less, and a tempered bainite structure.

The present invention is based on the above-mentioned steels containing the Group IIa elements and III.
It contains at least one of Group a elements in an amount of 0.001 to 0.1%.

In addition to the above-mentioned steel, the present invention further comprises a Group IVa element, N
It contains at least one element of b, Ta and W in an amount of 0.2% or less.

The present invention has a magnetic susceptibility of 990 at 21 kG.
Ni-C having AT / cm or less and tempered bainite structure
It is made of r-Mo-V alloy steel.

The present invention, by weight, has a C of 0.15 to 0.30.
%, Si 0.1-0.3% or less, Mn 0.5% or less, Ni
3.25-4.5%, Cr2.05-2.60%, Mo0.
25-0.60%, V0.05-0.20%, Al0.0
A rotor shaft for a rotary electric machine is characterized in that 1% or less and the balance are substantially Fe, and have a tempered bainite structure.

The present invention, by weight, has a C of 0.15 to 0.30.
%, Si 0.3% or less, Mn 1% or less, Ni 3.0 to 5.0%
, Cr 2.0-3.0%, Mo 0.1-1.0% and V0.
After melting alloy steel containing 03 to 0.35% in the atmosphere, ladle refining, vacuum degassing, etc. are performed, and then the molten metal is poured into a mold to form electro-slag after ingot casting or further melting in air. After melting and ingoting, hot forging, 800-9
A method for manufacturing a rotor shaft for a rotary electric machine is characterized by performing a tempering treatment in which the material is hardened at 00 ° C. and then held at 550 to 650 ° C. for 10 hours or more.

According to the present invention, there is provided a rotor shaft for a rotary electric machine comprising a body having a slot for embedding a coil in the axial direction, a flange portion for transmitting and receiving power transmission, and a bearing portion, the shaft having a room temperature tensile strength of 93 kg / mm ² or more, 50% fracture surface transition temperature 0 ° C or less, and magnetizing force at 21 kG is 990
Magnetization force below AT / cm and at 20kG is 400AT
/ Cm or less low alloy steel, the diameter of the body is 1m
The above and the length of the body are 5.5 to 6.5 times the diameter of the body.

In the present invention, the shaft is made of high strength Ni-Cr-Mo-V alloy steel having a body diameter of 1 m or more and a body length of 5.5 to 6.5 times the body diameter. , The body diameter D (mm) is 0.2 mm per 1 MVA of electric machine capacity.
It is characterized in that it is not more than a value obtained by adding 000 mm and not less than a value obtained by adding 900 mm to 0.2 mm per 1 MVA of the generator capacity.

According to the present invention, in the shaft described above, the body diameter D (mm) is 1 m or more, and the body length is 5.5 of the body diameter.
It is made of high strength Ni-Cr-Mo-V alloy steel which is up to 6.5 times, and the value of (D ² × R ² ) obtained from the relationship with the rotation speed R (rpm) of the shaft is 1.0 × 10 ^7. ~ 3.0 x 10 ⁷
The body diameter is set with respect to the rotational speed so that

The present invention, by weight, has a C of 0.15 to 0.30.
%, Si 0.3% or less, Mn 0.5% or less, Ni 3.0 to
5.0%, Cr 2.0-3.5%, Mo 0.1-1.0%,
V0.03 to 0.35%, Al 0.006% or less, P, S, S
The total amount of n, Sb and As is 0.025% or less, the above (Ni / C
r) A rotor shaft for a rotary electric machine, characterized by being made of a low alloy steel having a ratio of 2.1 or less.

According to the present invention, the room temperature tensile strength is 93 kg / mm ² or more, the 50% fracture surface transition temperature is 0 ° C. or less, the magnetizing force at 21 kG is 990 AT / cm or less, and the magnetizing force at 20 kG is 4.
High strength and high toughness Ni-Cr-M having 00 AT / cm or less
A rotor shaft for a rotary electric machine, characterized in that it is constituted by an integral solid shaft made of o-V alloy steel.

The present invention, by weight, has a C of 0.15 to 0.30.
%, Si 0.01 to 0.05%, Mn 0.05 to 0.5%,
Ni3.0-5.0%, Cr2.0-3.5%, Mo0.1
~ 1.0%, V0.03 ~ 0.35%, Al0.0005 ~
0.006%, total amount of P, S, Sn, Sb and As 0.0
A rotor shaft for a rotary electric machine is characterized in that the balance is 01 to 0.025% and the balance is substantially Fe.

The present invention is a large-capacity rotating electric machine having a capacity of 900 MVA or more, comprising a stator composed of a laminated iron core in which a coil is embedded, and a rotor rotating in the stator, wherein the rotor has a high strength Ni. A coil is embedded in a shaft body made of -Cr-Mo-V low alloy steel, and the body diameter is 1 m or more;
The body length is 5.5 to 6.5 times the body diameter, and 3000rp
It is preferable that the floor area of the rotary electric machine is 0.08 to 0.12 m ² per 1 MVA of the electric machine capacity when it is rotated by m or 360 rpm.

In the present invention, the electric machine capacity is 900 MVA or more, and the stator current is 19.0 to 24 per 1 MVA of the electric machine capacity.
A, the stator is directly water-cooled, the rotor has an electric capacity of 1 MVA
Characterized in that it is made of high-strength Ni-Cr-Mo-V alloy steel that is cooled at a hydrogen pressure of 0.003 to 0.006 kg / cm ^{2 and} the diameter of the body of the rotor shaft is 1.0 m or more. It is in a large-capacity rotating electric machine.

In the present invention, in the rated capacity of 1,120,000 KVA, the stator is directly water-cooled, the rotor is hydrogen-cooled, the rotor body diameter is 1.15 to 1.35 m, and the body length is 5 times the body diameter. It is 0.5 to 6.5 times, and is characterized by being rotated at 3600 rpm. In particular, the machine size is preferably 9-10 m ³ .

The present invention, by weight, has a C of 0.15 to 0.30.
%, Si 0.3% or less, Mn 0.5% or less, Ni 3.0 to
5.0%, Cr 2.0-3.5%, Mo 0.1-1.0%,
V0.03 to 0.35%, Al 0.010% or less, P, S, S
The total amount of n, Sb and As is 0.025% or less, the above (Ni / C
r) A rotor shaft for a rotary electric machine, characterized by being made of a low alloy steel having a ratio of 2.3 or less.

[0032]

[Function] C is indispensable for improving strength. Therefore, if it is less than 0.15%, sufficient hardenability cannot be obtained, and a soft ferrite structure is generated in the center of the rotor, resulting in sufficient tensile strength and proof stress. Can't get Further, if the content is 0.3% or more, the toughness decreases, so the range of C is 0.15 to 0.3.
Limited to%. If the (Ni / Cr) ratio is 1.2 to 2.0, it can be set to 0.15 to 0.35. Particularly, C is preferably in the range of 0.20 to 0.28%.

Conventionally, Si and Mn have been added as deoxidizing agents, but by the steelmaking technology such as C deoxidizing method by vacuum ladle refining and electroslag remelting method, a healthy rotor can be melted without any addition. It can be manufactured. From the viewpoint of preventing temper embrittlement, Si and Mn should be made lower, and are limited to 0.1% and 1.0% or less, respectively.
From 0.05% and Mn ≦ 0.25%, 0.20% or less is preferable. Even if Si is not added, 0.019 as an impurity
~ 0.1% contained. It is preferable to add a small amount of Mn, and the Mn content should be 0.05% or more, and more preferably 0.1% or more.

Ni is an essential element for improving hardenability and toughness. If it is less than 3.0%, the toughness improving effect is not sufficient. Further, when a large amount exceeding 5% is added, a harmful residual austenite structure appears, and a uniform tempered bainite structure cannot be obtained. Particularly, a range of 3.25% or more, more preferably more than 3.5% and up to 4.5% is preferable.

Cr has the effect of improving hardenability and significantly improving toughness. It also has the effect of improving corrosion resistance. Below 1.5%, these effects are not sufficient,
Addition of a large amount exceeding 3.0% produces a harmful residual austenite structure and a uniform tempered bainite structure cannot be obtained. Particularly, the range of 2.05 to 2.60% is preferable.
Mo precipitates fine carbides in the crystal grains during the tempering treatment, and has a carbide dispersion strengthening action, which results in tensile strength and 0.02.
% Has the effect of increasing yield strength. Further, it has an effect of suppressing segregation of the impurity element at the grain boundaries during tempering, and therefore has an effect of preventing temper embrittlement. If it is less than 0.1%, these effects are not sufficient, and if added in excess of 1.0%, the effects tend to be saturated. Especially, 0.25-0.
6%, more preferably 0.35 to 0.45%.

V has the effect of precipitating fine carbides at the grain boundaries during the tempering treatment and increasing the tensile strength and 0.02% proof stress by the carbide dispersion strengthening action. If it is less than 0.03%, these effects are not sufficient, and if added in excess of 0.35%, the effects tend to be saturated. Especially, 0.05-0.2
%, More preferably 0.10 to 0.15%.

Since Al deteriorates toughness and magnetic properties,
Should be low. Reduction of Al has a large effect of improving toughness and magnetic properties. In particular, Al is 0.1 in terms of ensuring toughness.
The upper limit is 01%. Particularly, 0.005% or less is preferable. On the other hand, if Al is completely eliminated, the strength will be lowered. Therefore, it is preferable to set it to 0.0005% or more, especially 0.001% or more from the viewpoint of steelmaking limit.

Further, there are impurities such as P, S, Sn, Sb and As, and these reduce the toughness and magnetic properties, so these elements must be lowered. In particular, these elements have a correlation with Si, and the value obtained by multiplying the amount of Si and the total sum of these elements is preferably 30 × 10 ⁻⁴ or less. Particularly, 15 × 10 ⁻⁴ or less is preferable. In addition, the total amount of these elements except Si is 0.030% or less, and more than 0.03%.
It is preferably 025% or less. It is difficult to eliminate all these impurities, especially as a lower limit of 0.001
%, And more preferably 0.010%.

The (Ni / Cr) ratio is related to the tensile strength, and by setting the value to 2.1 or less, high strength can be obtained. When the values are the same, the strength is higher as the Ni content is higher, and the higher strength is obtained when the Ni content exceeds 3%.
In particular, it is preferable that the (Ni / Cr) ratio is 1.2 to 2.0, and more preferably 1.4 to 1.9 for a Ni content of 3% or more.

Group IIa elements (Be, Mg, Ca), IIIa
At least one of the group elements (Sc, Y, lanthanoid elements)
0.1% or less of one kind or two or more kinds. These elements act as a strong deoxidizing agent and have a remarkable effect in improving toughness and magnetic properties. In particular, 0.001-0.0
It is preferably 5%. These are non-radioactive elements, and radioactive elements are not preferable in handling.

Group IVa elements (Ti, Zr, Hf), Nb,
At least one of the carbide-forming elements of Ta and W is 0.2%
By containing the following, the strength is increased without lowering the toughness. In particular, 0.02 to 0.1% is preferable. W is Mo
Since it has the same effect as, it is possible to replace part of Mo with W. Therefore, it is preferable that the amount of Mo + W is 0.1 to 1.0%, the upper limit of the amount of W is 0.5%, and half or less of the amount of Mo.

The low alloy steel according to the present invention has a tempered bainite structure and can contain 5% or less of ferrite, but the whole bainite structure is preferable in terms of strength and toughness.

The low alloy steel according to the present invention is capable of enhancing strength and toughness as well as magnetic properties by remarkably reducing Si impurities. Therefore, after melting in air, electroslag remelting or melting in air is performed. After that, the molten metal is formed by refining the vacuum ladle. The molten metal is cast in a mold and formed into a predetermined shape by hot forging. Then, quenching is performed at 800 to 900 ° C, and then tempering is performed at 550 to 650 ° C for 10 hours or more.
The quenching temperature is 30 to 70 ° C. higher than the Ac ₃ point of the steel, and it is particularly preferable that the quenching temperature be 50 ° C. higher than Ac ₃ . Tempering enhances toughness, and is 550-650 ° C.
In particular, the temperature is preferably 560 to 600 ° C., and it is preferably held for 10 to 60 hours. Although the final shape is obtained by cutting after tempering, internal stress is generated by the cutting, so stress relief tempering is performed at a temperature lower than the tempering temperature.
In addition, after forging, homogenized quenching is performed, and it is about 50
It is carried out at a high temperature of ℃ and is cooled. The cooling rate during quenching is preferably 50 to 150 ° C./h at the center of the shaft. This gives a bainite structure, in particular a whole bainite structure.

The Si content is 0.01% of the above Al content.
It can be made 0.1 to 0.3% by the following, and the amount of P, S, Sn, Sb and As is 0.025%.
With the following, good characteristics can be obtained even with high Si.

By using the above-mentioned alloy steel, the rotor shaft for a rotary electric machine has a diameter of the body portion in which the coil is embedded of 1
By setting the length to be m or more and the body length being 5.5 to 6.5 times the diameter, the entire device can be made compact. A ratio of less than 5.5 and more than 6.5 is not preferable because of the vibration sensitivity of the rotor. Particularly, 5.6 to 6.0 is preferable.

The diameter of the body must be increased according to the generator capacity, but it is 100 for 0.2 mm per 1 MVA of capacity.
0 mm is less than or equal to the added value, and 0.2 mm per MVA is 90.
It is necessary to make it more than the value which added 0 mm.

Further, the body diameter D (m) should be set also by the number of rotations R (rpm) of the rotor, and (D ² ×
The value of R ² ) should be set to be 1.0 × 10 ⁷ or more. In particular, the upper limit is preferably set to 3.0 × 10 ⁷ . Particularly, 1.5 to 2.2 × 10 ⁷ is preferable, and 1.8 to 2.
0 × 10 ⁷ is good.

Although the generator and the electric motor become large in size due to the increase in capacity, a compact device can be made by using high-strength alloy steel as described above. Particularly, the floor area is 0.08 to 0 per 1 MVA in capacity. It can be .12 m ² . And since the energy loss can be reduced, the efficiency is further enhanced. Since the stator current can also be reduced per capacity, motor / generator capacity per MVA of 19.
It can be set to 0 to 24 A, and the current per unit capacity can be reduced particularly as the capacity increases. 2000 MVA capacity
Can be about 19.0 to 20.0 A. Although the rotor at that time is cooled by hydrogen, it is necessary to increase the hydrogen pressure according to the generator output.
The amount can be 0.003 to 0.006 kg / cm ² · g. Particularly, 0.004 to 0.005 kg / cm ² · g is preferable.

The present invention is applied to a generator and an electric motor, and examples of the electric motor include a synchronous motor, a synchronous generator motor, and an induction synchronous motor. The structure of the electric motor and the generator is almost the same. Especially as an electric motor 5000-6000rp
It is preferable in a high-speed rotation motor having a rotation speed of m 3.

The tensile strength of the rotor shaft in the present invention is preferably 93 kg / mm ² or more, more preferably 100 kg / mm ² or more, and particularly preferably adjusted to obtain 104 kg / mm ² or more. At the same time, the 50% fracture surface transition temperature is set to 0 ° C or lower, more preferably -50 ° C or lower. The crystal grain size is preferably 4 or more in terms of ASTM grain size number. Furthermore, the magnetic characteristic is a magnetic flux density of 21 kG.
Magnetizing force at 990 AT / cm or less, 20
The magnetizing force in kG is preferably 400 AT / cm or less, and particularly preferably 500 AT / cm or less in the former case.

[0051]

【Example】

Example 1 Table 1 shows the chemical structure of the test steel. 20 kg of each sample was cast in a high-frequency melting furnace at a temperature of 850 to 1150 ° C and a thickness of 30 mm,
Hot forged to a width of 90 mm. Sample Nos. 2 to 6 and 15 are materials of the present invention. Sample No. 1 was melted for comparison with the invention material. No. 1 is a material corresponding to ASTM standard A469-88 class 8 of the generator rotor shaft material, and No. 5 is high Al steel. These samples were subjected to heat treatment simulating the conditions of the central part of the large rotor shaft of the large capacity generator. First, it was heated to 840 ° C., austenitized, and then cooled and quenched at a rate of 100 ° C./h. Then, after heating and holding at 575 to 590 ° C. for 32 hours, it was cooled at a rate of 15 ° C./h. The tempering treatment was performed by selecting a temperature at which the tensile strength falls within the range of 100 to 105 kg / mm ² for each sample.

Nos. 7 to 12 are comparative steels, which are 1 at 820.degree.
After heating and holding for 6 to 34 hours, quenching was also performed at a rate of 100 ° C./h, and after heating and holding at 625 to 635 ° C. for 40 to 50 hours, tempering treatment was performed by furnace cooling at a rate of 15 ° C./h.

Nos. 13 and 14 are comparative steels, 900 ° C.
After heating for 2 hours at room temperature, the furnace is cooled and homogenized, then 850
Quenching was performed at a rate of 120 ° C./h after heating at 0 ° C. for 2 hours, and tempering was performed at a rate of 40 ° C./h after heating and holding at 575 ° C. for 60 hours.

[0054]

[Table 1]

N of the Ni-Cr-Mo-V steel according to the present invention
Nos. 2 to 6 and 15 did not contain proeutectoid ferrite and had a uniform tempered bainite structure. The former austenite grain size numbers were all 7.
The other alloys Nos. 1, 5 and 14 also had a uniform tempered bainite structure. No. 13 has about 5% proeutectoid ferrite.

Table 2 shows the results of the tensile test, impact test, magnetic property and electric property. In the table, the magnetizing force is 20 kG
And at 21 kG. Those listed in the table are at 21 kG.

[0057]

[Table 2]

As shown in the table, the low alloy steel N according to the present invention
o.2 to 6 and 15 have a tensile strength of 100 kg / mm ² or more,
0.02% proof stress is 78kg / mm ² or more, and 50 ℃
It can be seen that the fracture surface transition temperature is -50 ° C or lower, which is much lower than 0 ° C or lower, and both strength and toughness are high. Furthermore, the magnetizing force is 990 AT / cm as the magnetizing force at 21 kG required for a rotor shaft for generators of 900 MVA or more.
The following values are sufficiently satisfied, and those of the present invention having a high Cr content also have a high value of 30 μΩcm or more, and are extremely useful as a large-capacity generator rotor shaft material of 900 MVA or more.

FIG. 2 is a diagram showing the effect of Cr content on tensile strength. As shown in the figure, the Ni content is 2.60-4.
At 15%, the tensile strength increases with increasing Cr content. In particular, when the amount of Cr exceeds 1.4%, it rapidly increases and the effect of Cr is great. If it exceeds 2.0%, a high tensile strength of 100 kg / mm ² or more can be obtained.

Similarly, FIG. 3 is a diagram showing the relationship with the (Ni / Cr) ratio. As shown in the figure, the higher the (Ni / Cr) ratio, the lower the tensile strength. In particular, (Ni / C
When the r) ratio is 2.1 or less, high strength can be obtained. There is also a relationship with the amount of Ni, and by setting high Ni to 3.50% or more, a high strength of 100 kg / mm ² or more can be obtained. For the target tensile strength of 93 kg / mm ² or more, the (Ni / Cr) ratio should be 2.3 or less, and Ni should be 3.5%.
It is obtained by the following. If less than 3% Ni, it is difficult to obtain.

FIG. 4 also shows the relationship with the amount of Si, and it can be seen that the strength is increased by increasing the amount of Si. If the amount of Si is 0.17% or more, 93 kg / mm ² or more can be obtained with Cr 1.3 to 1.8% and Ni 2.6 to 3.5%.
If the content of Cr exceeds 2%, the low Si content of 0.1% or less is 93.
kg / mm ² or more, particularly 100 kg / mm ² or more can be obtained.

FIG. 5 is a diagram showing the effect of the amount of Ni or Cr on the 50% fracture surface transition temperature. Ni as shown
Both FAT and Cr increase the content of FATT.
In particular, when the Si content is 0.1% or less and the Cr content is 0.5% or more, a FATT of 0 ° C. or less can be obtained. In particular, if the Si amount exceeds 0.1%, it is difficult to obtain a FATT at 0 ° C. or lower even if Ni and Cr are increased.

FIG. 6 is a diagram showing the effect of the amount of Si on FATT. As shown in the figure, by decreasing the amount of Si, FATT is lowered and high toughness is obtained. Particularly, in the vicinity of Ni 2.5 to 3.0% and Cr 1.3 to 1.8%, the Si content is 0.08% or less, Ni 3.5 to 4.0% and C.
In the vicinity of r1.5 to 2.2%, the temperature can be kept at 0 ° C or lower by setting it to 0.13% or lower. If Cr exceeds 2.2% and Ni is 3.5% or more, 0.20% or less, 0 ° C
It can be:

FIG. 7 is a diagram showing the relationship between FATT and Al content. Since the content of Al is also an element which enhances FATT, it is 0.014% or less in the vicinity of Cr 0.055 to 2.2% and Ni 3 to 4%, Cr 2.2 to 2.5% and Ni 3.5 to 5.
In the vicinity of 4.5%, 0.018% or less and 0 ° C or less can be achieved. In the vicinity of 1.65% Cr, it is difficult to obtain 0 ° C or lower even if the Ni content is as high as 3.5% and the Al content is reduced.

FIG. 8 shows the relationship between the magnetizing force and the amount of Si. As shown in the figure, an increase in the amount of Si enhances the magnetizing force, so a lower amount is preferable. In particular, Cr 1.5-2.5% and N
When i is in the vicinity of 2.5 to 4.5%, the magnetizing force at 21 kG can be set to 900 AT / cm or less by setting the Si amount to 0.18% or less. In particular, when the Si content is 0.1% or less, a magnetizing force of 700 AT / cm or less is obtained.

Similarly, FIG. 9 shows the magnetizing force and P, S, Sn, S.
It is a diagram which shows the relationship with the total amount of b and As. These impurities are not preferable because they increase the magnetizing force.
It should be 0.040% or less to be less than cm. In particular, 0.03% or less is preferable to achieve 700 AT / cm or less.

FIG. 10 also shows the relationship between the magnetizing force and the amount of Al. As shown in the figure, Al is not preferable because it enhances the magnetizing force. When the amount of Cr, Ni and Si is less than 0.1%, the amount of Al should be 0.025% or less in order to obtain a magnetizing force of 990 AT / cm or less, and particularly 0.015% in order to reduce it to 700 AT / cm or less. The following are preferred. If the Si content exceeds 0.1%, the Al content should be 0.01% or less.

FIG. 11 also shows the effect of the value obtained by multiplying Si by the total amount of P, S, Sn, Sb, and As, which affects the magnetizing force. The higher the value, the higher the magnetizing force. 990AT if the value is 70 × 10 ^-4 or less
/ Cm or less.

Example 2 Table 3 shows a tensile test, an impact test and a magnetic property test of the samples of the present invention steel Nos. 2 to 4 and 6 having high strength (tempering temperature was lowered by 5 ° C. lower than in Example 1). The results are shown.

As is apparent from the table, the material of the present invention has a tensile strength of 105 kg / mm ² or more, a 0.02% proof stress of 82 kg / mm ² or more, a FATT-44 ° C. or less, a magnetizing force of 400 AT / cm or less, and a 1200 MVA grade. And 1300 MVA class generator rotor shaft material sufficiently satisfies the mechanical and magnetic properties. Therefore, it can be said that the material of the present invention is extremely useful as a rotor shaft for a large capacity generator of 1200 MVA or more.

[0071]

[Table 3]

Example 3 An AC turbine generator driven by thermal power or nuclear power is usually a two-pole or four-pole cylindrical rotary field synchronous generator.

Most of the turbine generators for thermal power are two-pole high-speed generators, and the rotation speed is 50 Hz, 3,000 rpm, 6 rpm.
It becomes 3,600 rpm at 0 Hz. This is because the turbine is more efficient and smaller at higher speeds. Most of the tandem compound types output one axis, but for large capacity machines, the cross compound type that outputs two axes is also used.

A nuclear turbine generator is usually 4 poles, 1,
Used at 500 rpm or 1800 rpm. This is because the steam generated in the reactor is large in amount, low temperature, and low pressure compared to thermal power, and the turbine has long blades and low rotation speed.

As a cooling system for the turbine generator, there are an indirect cooling system and a direct cooling system, and air, hydrogen and water are mainly used as a cooling medium.

Hydrogen cooling is used with a large capacity, and there are both indirect and direct types, and all of them have an explosion-proof sealed structure in which a gas cooler is incorporated in the generator body. Further, in the case of water cooling, a direct cooling method is used, and in a large capacity machine, both the stator and the rotor may be water cooling methods.

FIG. 12 shows an example of a stator coil direct water cooling type turbine generator according to the present invention.

(Stator) The stator frame is made of a welded structure steel plate or the like to form a ventilation path, supports the iron core, and is strong so as to prevent vibration. The magnetic attraction causes the iron core to deform into an ellipse, and the double frequency vibration is generated as the rotor rotates. Since this vibration becomes larger in larger machines, an elastic support structure is used in which the iron core and the stator frame are attached via springs.

The stator core 2 has 0.35 or 0.5 mm.
Thick silicon steel plates are used, and grain-oriented silicon steel plates are used. The iron cores are laminated in the axial direction by 50 to 60 mm each,
I-shaped steel spacer pieces are inserted so as to form a ventilation duct therebetween.

The stator winding 7 is usually a two-layer winding, but in the case of a two-pole machine, the winding end portion is particularly long and must be held firmly. Non-magnetic material is used for the end structure because stray load loss is large.

(Rotor) A major feature of the turbine generator is that it rotates at a high speed, and since the centrifugal force becomes large, the rotor diameter is limited. The rotor structural material is mechanically forged while being integrally forged in order to avoid a dangerous speed and suppress vibration, and the slot 16 shown in FIG. 14 is processed, and the field winding is housed therein. The shape of the rotor 1 is shown in FIG.

The main shaft material is Ni-Cr-M according to the present invention.
It consists of o-V steel. Although not shown in the drawing, a ring 17 for mounting the fan 20 is provided between the flange 15 and the center ring 18.

The field winding 3 is formed by flatly winding a copper band and distributedly wound in the rotor core slots formed between the teeth 12, and the interlayer insulation is injected for each turn of the conductor. The ends of the winding are held by a retaining ring 9. Instead of ordinary copper, silver-filled copper with good creep characteristics is used for the coil.

The retaining ring 9 is made of non-magnetic stainless steel containing C 0.1% or less, N 0.4% or more, 10 to 25% Mn, and 15 to 20% Cr. After the winding 3 is embedded in the slot 16, it is fixed by fitting a wedge 13 made of a super duralumin alloy into the widest portion of the slot 16. An end or full length damper is used for the end damper ring 14, and an end Al alloy and a body silver-copper alloy are used. 8 is a shaft, 11 is a magnetic pole, and 15 is a coupling.

(Ventilation system) In a large machine of 1000 MVA class or more, it is difficult to uniformly cool when the iron core length becomes long, so a double ventilation system is adopted.

In this system, several sections of the air supply chambers and the exhaust chambers are alternately arranged in the axial direction in the stator frame behind the iron core, and the cooling air flows from the both ends of the generator to the wind tunnel inside the stator frame. After that, they are collected in each air supply chamber, cool the stator core from this, and flow to the outer diameter side with the gas that has cooled the inside of the rotor,
Circulates through the cooler to the intake side of the fan.

The gas pressure for hydrogen cooling is 2 at with an indirect hydrogen cooling machine.
g, 2-5 atg used in direct hydrogen chiller. When the hydrogen gas pressure is increased, the heat transfer coefficient is improved and the heat capacity of the gas is increased in proportion to the density. Therefore, the temperature rise of the gas itself is decreased in inverse proportion to the absolute pressure of the gas, and the cooling effect is increased. To do. The output of a machine of the same size is 11 at 1 atg when the output for an indirect cooling type at 0.05 atg is 100.
It becomes 125 outputs at 5 and 2 atg.

The hydrogen cooling system becomes explosive when the volume of hydrogen is in the range of 10 to 70% when mixed with air. In order to prevent this, the hydrogen purity is automatically maintained at about 90% or more. For this reason, a sealing device with an oil film is installed inside the bearing to prevent hydrogen gas inside the machine from leaking out of the machine along the shaft. ing. By flowing oil with a pressure higher than that of hydrogen gas inside the machine in the narrow gap of the shaft, gas leakage from the inside of the machine is prevented.

In the hydrogen-cooled turbine generator, even when the stator is indirectly cooled, the rotor is often directly cooled.

(Direct Cooling) When the maximum temperature of the conductor of the generator coil limits the output, the conductor is directly cooled by a cooling medium in order to eliminate the temperature difference in the insulator which accounts for a large proportion during the temperature rise. ..

As the cooling medium, there are liquids such as hydrogen gas and oil / water. Water has a heat transfer capacity about 50 times that of air, and is an excellent cooling medium.

(1) Hydrogen gas direct cooling An example of a stator coil is shown, in which gas is passed through a rectangular vent tube sandwiched between the wires to directly cool the conductor. A part of the heat generated by the conductor is transmitted to the iron core through the main insulation with high thermal resistance and is cooled, but most of it is carried away by the hydrogen gas through the cooling pipe with low thermal resistance.

Pure water having a large specific heat and a very large heat transfer coefficient by convection is used for cooling the liquid.

Stainless steel is used for the pipes serving as the liquid passages, and oxygen-free copper or deoxidized copper is used for the coils and clips at the ends of the coils. A Teflon tube with high mechanical strength, high flexibility, and good insulation is usually used for the insulation connection tube. In the cross section of the stator coil, the element wire is hollow, and the liquid is allowed to flow in this.

(2) Hydrogen gas or water is used as the cooling medium of the rotor, and there are the following methods.

In the end feed system, the hydrogen gas pushed into the rotor coil from the rotor end is released into the air gap through the hole formed in the center of the rotor. Also,
A method in which the coil copper strip enters from one end of the rotor and exits from the other end is also preferable.

The cross-sectional shape of the rotor coil may be either a bypass type or a hollow copper band type. When this method is adopted, gas direct cooling is also adopted for the stator coil, and a high-pressure blower is attached to one end of the rotor.

In the air gap pickup system, the inlet and outlet holes are alternately provided on the rotor surface, and the hydrogen gas in the air gap portion is sucked from the coil wedge surface by utilizing the wind velocity due to the rotation, and the coil copper strip is used. There is a method of passing a certain distance through the inside to remove the generated heat and discharging the generated heat to the air gap portion through an exhaust hole, or a method of passing water through a rotating body in the water cooling technology of the rotor.

The water cooling method is disadvantageous in reliability because it has a complicated structure as compared with the hydrogen gas cooling method.
The weight of the generator is reduced by about 15 to 25%, and the efficiency under partial load can be improved.

In the figure, 15 is a flange coupled to the turbine, 20 is a fan, 21 is a stator coil, 22 is a brush, and 23 is a slip ring.

FIG. 1 shows a turbine output 1000 according to the present invention.
It is a perspective view of the rotor shaft for large turbine generators of MW class (generator capacity 1120 MVA class) or higher. The rotor shaft according to the present invention was manufactured as follows.

Approximately 1 was produced by vacuum ladle refining after melting in the air, aiming at the same composition as No. 2 described in Example 1.
50t of molten metal was cast into a mold. Next, hot forging was carried out by a press, and forging (forging ratio 3S) was performed after upsetting (forging ratio 1 / 2U). Further, after homogenizing and refining at 900 ° C and cutting into a predetermined shape, the whole is 2 at 840 ° C.
After heating and holding in a vertical furnace for 0 hour, quenching was carried out by cooling with a water spray at the central hole at a cooling rate of 100 ° C./h. Then, a tempering treatment was performed in which the material was heated and held at 580 ° C. for 60 hours and then cooled at a rate of 15 ° C./h. Then, the final shape shown in FIG. 1 was cut. This embodiment is for two poles, 11 is a magnetic pole, 12 is a tooth, 17 is a fan mounting ring, 18
Is a centering ring for mounting a retaining ring, 1
9 is a central hole. At this point, samples were taken to inspect the mechanical, electrical and magnetic properties of the material.
The centering ring 18 is integrated when the shaft is formed, but after being cut into a ring shape, the retaining ring is shrink-fitted.

In this embodiment, the total length is about 15 m and the teeth 12 are
The diameter of the body is 1.2 m and the length of the body is about 7 m.
And the diameter of the body is about 5.7 times. This machine has a machine size of about 10 m ³ , and by doing so, the vibration sensitivity of the rotor can be lowered, the in-phase unbalance sensitivity can be suppressed low, and the flexibility of the shaft is reduced and the bearing stability is high. Is obtained.

The machine size is represented by (outer diameter of rotor body) ² × (rotor body length).

The relationship between the machine size of the rotor shaft and the generator capacity (MVA) in the present invention is expressed by the following equations (1) and (2).
The range of is preferable.

Machine size (m ³ ) = 4.7 + 3.2 × 10 ^-3 × generator capacity (MVA) (1) Machine size (m ³ ) = 4.5 + 5.7 × 10 ^-3 × generator capacity (MVA) (2) The mechanical properties, magnetic properties, and electrical properties of this example were equivalent to those of the No. 2 alloy of Example 1.

The specifications in this embodiment are as follows.

Generator capacity: 1120 MVA, stator current: 22 A per generator capacity 1 MVA, power factor: 0.9, rotation speed 3600 rpm, frequency 60 Hz, stator: direct water cooling, rotor: direct hydrogen cooling (generator Capacity: 0.0047 kg / cm ² · g per MVA, casing material: SM41
Steel, iron core material: grain oriented silicon steel plate, coil: electrolytic copper, insulating material, epoxy resin and mica, body length / body diameter of coil embedding part / 5.83, retaining material: C0.1% or less, N0.7 Above, Si 1% or less 18% Mn-18%
Cr steel, full length damper, rotor coil: silver-filled copper, bearing: carbon steel cast steel, overall dimensions: length 16 m, width 6 m, floor area 96
m ² .

With the above structure, 1000M
Generator capacity 1120 MVA for W class turbine output
And the floor area of the generator per MVA is 0.086.
m ² and the floor area per MVA of the conventional 700 MW class generator (capacity 800 MVA) is 0.098 m ²
More compact about 13%. This floor area can be 0.08 to 0.09 m ² per 1 MVA of generator capacity.

Further, according to the low alloy steel of the present invention, the upper limit and the lower limit of the body diameter are values obtained from the above machine size values, and further the upper limit diameter D (mm) is obtained by the following formula 3. It is preferable that the value and the lower limit diameter are the values obtained by the equation 4. The body length is 5.5 of its diameter
It is preferably up to 6.5 times.

Body diameter D (mm) = 0.2 × generator capacity (MVA) +1000 (3) Body diameter D (mm) = 0.2 × generator capacity (MVA) +900 (4) or more With this structure, the vibration sensitivity of the rotor is low, and the generator as a whole can be made compact.

[0112]

According to the present invention, the room temperature tensile strength is 93 kg /
mm ² or more, 50% fracture transition temperature 0 ° C or less, magnetizing force at 21 kG of 990 AT / cm or less, and a large-capacity generator with a generator capacity of 900 MVA or more or rotation speed 5
A synchronous motor of 000 rpm or more can be manufactured compactly. As a result, the installation area can be effectively utilized, and particularly in power generation, it can contribute to diversification of energy of oil, coal, and nuclear power.

[Brief description of drawings]

FIG. 1 is a perspective view of a rotor shaft for a rotary electric machine according to the present invention.

FIG. 2 is a diagram showing the relationship between tensile strength and Cr.

FIG. 3 is a graph showing the relationship between tensile strength and (Ni / Cr) ratio.

FIG. 4 is a diagram showing the relationship between tensile strength and Si.

FIG. 5 is a diagram showing a relationship between FATT and Ni or Cr.

FIG. 6 is a diagram showing a relationship between FATT and Si.

FIG. 7 is a diagram showing a relationship between FATT and Al.

FIG. 8 is a diagram showing a relationship between a magnetizing force and Si.

FIG. 9 is a diagram showing a relationship between a magnetizing force and P + S + Sn + Sb + As.

FIG. 10 is a diagram showing a relationship between magnetizing force and Al.

FIG. 11: Magnetizing force and Si × (P + S + Sn + Sb + A)
The figure which shows the relationship with s).

FIG. 12 is a sectional view of a turbine generator.

FIG. 13 is a perspective view of a rotor for a turbine generator.

FIG. 14 is a sectional view of a slot of a rotor.

[Explanation of symbols]

1 ... Rotor, 2 ... Stator, 3 ... Field winding, 4 ... Bearing bracket, 5 ... Stator frame, 6 ... Bearing, 8 ... Shaft, 9 ... Retaining ring, 10 ... Cross slot, 11 ... Magnetic poles, 12 ... Teeth, 13 ... Wedges, 1
4 ... End tampering, 15 ... Coupling, 16 ...
Slots, 17 ... Fan mounting ring, 18 ... Centering ring, 19 ... Center hole, 20 ... Fan, 21 ... Stator coil, 22 ... Brush (graphite), 23 ... Slip ring.

Front page continuation (72) Inventor Hiroshi Fukui 4026 Kujimachi, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. Factory Hitachi Factory

Claims (19)

[Claims] 1. C. 0.15 to 0.30% by weight and Si 0.30 by weight.
1% or less, Mn 1% or less, Ni 3.0 to 5.0%, Cr
More than 2.0% and less than 3.0, Mo 0.1-1.0%, V0.
A rotor shaft for a rotary electric machine, characterized in that the balance is 03 to 0.35% and the balance is substantially Fe. 2. By weight, C 0.15 to 0.35% and Si 0.30.
1% or less, Mn 1% or less, Ni 3.0 to 5.0%, Cr
1.5-3.5%, Mo 0.1-1.0%, V 0.03-0.0%.
35% and the balance being substantially Fe, the above (Ni / C
r) The ratio is 1.2 to 2.0, a rotor shaft for a rotary electric machine. 3. By weight, C 0.15 to 0.30% and Si 0.30.
3% or less, Mn 1% or less, Ni 3.0 to 5.0%, Cr
2.05-3.0%, Mo0.1-1.0%, V0.03-
A rotor shaft for a rotary electric machine, which is characterized in that 0.35%, A 10.06% or less and the balance substantially Fe. 4. By weight, C 0.15 to 0.30% and Si 0.30.
2% or less, Mn 1% or less, Ni 3.0 to 5.0%, Cr
2.0-3.0%, Mo 0.1-1.0%, V 0.03-0.0%.
A rotor shaft for a rotary electric machine, characterized in that 35% and the balance are substantially Fe, have a tensile strength at room temperature of 93 kg / mm ² or more, a fracture surface transition temperature of 0% or less at 50%, and a tempered bainite structure. .. 5. By weight, C 0.15 to 0.30% and Si 0.30.
1% or less, Mn 1% or less, Ni 3.0 to 5.0%, Cr
2.0-3.0%, Mo 0.1-1.0%, V 0.03-0.0%.
A rotor shaft for a rotating electric machine, comprising: 35%, 0.001 to 0.1% of at least one element of group IIa and group IIIa, and the balance being substantially Fe. 6. By weight, C 0.15 to 0.30% and Si 0.30.
1% or less, Mn 1% or less, Ni 3.0 to 5.0%, Cr
2.0-3.0%, Mo 0.1-1.0%, V 0.03-0.0%.
A rotor shaft for a rotary electric machine, comprising 35% and the balance being substantially Fe, having a magnetic susceptibility at 21 kG of 990 AT / cm or less and having a tempered bainite structure. 7. By weight, C 0.15 to 0.30% and Si 0.30.
1% or less, Mn 1% or less, Ni 3.0 to 5.0%, Cr
2.0-3.0%, Mo 0.1-1.0%, V 0.03-0.0%.
35%, at least 1 of IVa group element, Nb, Ta and W
A rotor shaft for a rotary electric machine, wherein one element is 0.2% or less and the balance is substantially Fe. 8. By weight, C 0.15 to 0.30% and Si 0.30.
1-0.3%, Mn 0.5% or less, Ni 3.25-4.5
%, Cr 2.05 to 2.60%, Mo 0.25 to 0.60
%, V0.05-0.20%, Al 0.01% or less, and the balance being substantially Fe, and having a tempered bainite structure. 9. A rotor shaft for a rotary electric machine, comprising a barrel portion having a slot for embedding a coil in the axial direction, a flange portion for transmitting and receiving power transmission, and a bearing portion, the shaft having a room temperature tensile strength of 93 kg / mm ² Above, 50% fracture transition temperature 0
It consists of low alloy steel having a magnetizing force of 990 AT / cm or less at 20 ° C or less and 400 AT / cm or less at 20 kG, and the body diameter is 1 m or more and the body length is 5. A rotor shaft for a rotary electric machine, which has a ratio of 5 to 6.5 times. 10. A rotor shaft for a rotary electric machine, comprising: a body having a slot for embedding a coil in an axial direction, a flange portion for transmitting and receiving power transmission, and a bearing portion, wherein the shaft has a body diameter of 1 m or more, The body length is made of high-strength Ni-Cr-Mo-V alloy steel having a body diameter of 5.5 to 6.5 times, and the body diameter D (mm) is a generator capacity of 1 MV.
A rotor shaft for a rotary electric machine, which has a value equal to or smaller than a value obtained by adding 1000 mm to 0.2 mm per A and a value obtained by adding 900 mm to 0.2 mm per 1 MVA of the generator capacity. 11. A rotor shaft for a rotary electric machine, comprising a body having a slot for embedding a coil in an axial direction, a flange portion for transmitting and receiving power transmission, and a bearing portion, wherein the shaft has a diameter D (mm) of the body. Of 1 m or more and the length of the body is 5.5 to 6.5 times the diameter of the body, high-strength Ni-Cr-Mo
Made of -V alloy steel, the value of (D ² × R ² ) obtained from the relationship with the rotational speed R (rpm) of the shaft is 1.0 to 3.0 ×
A rotor shaft for a rotating electric machine, wherein the body diameter is set with respect to the rotational speed so as to be 10 ⁷ . 12. C0.15-0.30% by weight, Si
0.3% or less, Mn 0.5% or less, Ni 3.0 to 5.0%,
Cr1.5-3.5%, Mo0.1-1.0%, V0.03
~ 0.35%, Al 0.01% or less, the total amount of P, S, Sn, Sb and As 0.03% or less, the (Ni / Cr) ratio 2.
A rotor shaft for a rotary electric machine, which is made of a low alloy steel of 1 or less. 13. Room temperature tensile strength of 93 kg / mm ² or more, 50%
Fracture surface transition temperature 0 ° C or less and magnetizing force at 21 kG is 9
Magnetization force of 400 AT at 20 kG, 90 AT / cm or less
A rotor shaft for a rotary electric machine, characterized by being constituted by an integral solid shaft made of a high-strength and high-toughness Ni-Cr-Mo-V alloy steel having a hardness of 1 / cm or less. 14. C0.15-0.30% by weight, Si
0.01-0.30%, Mn 0.05-0.5%, Ni 3.0
~ 5.0%, Cr 2.0-3.5%, Mo 0.1-1.0
%, V 0.03 to 0.35%, Al 0.0005 to 0.006
%, P, S, Sn, Sb and As total 0.001 to 0.00.
A rotor shaft for a rotating electric machine, characterized in that 025% and the balance substantially consist of Fe. 15. C0.15-0.30% by weight, Si
0.3% or less, Mn 1% or less, Ni 3.0 to 5.0%, C
r2.0-3.0%, Mo0.1-1.0% and V0.03
After melting alloy steel containing .about.0.35% in air, ladle refining vacuum degassing, etc. is performed, and then the molten metal is poured into a mold for ingot formation or after in-air dissolution and electroslag melting A method for manufacturing a rotor shaft for a rotary electric machine, comprising performing post-hot forging, quenching at 800 to 900 ° C., and then tempering at 550 to 650 ° C. for 10 hours or more. 16. A large-capacity rotating electric machine having a capacity of 900 MVA or more, comprising a stator composed of a laminated iron core in which a coil is embedded, and a rotor rotating in the stator and having a conductor coil embedded therein. The rotor is made of high strength Ni-Cr-Mo-V low alloy steel, the body diameter is 1.15 m or more, the body length is 5.5 to 6.5 times the body diameter, and 360 rpm. Large-capacity rotating electric machine characterized by receiving rotation of 17. A generator capacity of 900 MVA or more, a stator current of 19 to 24 A per the rotary electric machine capacity of 1 MVA, a direct water cooling of the stator, and a rotor of 0.00 per capacity of 1 MVA.
Cooled with hydrogen pressure of ^{3 to} 0.006 kg / cm ² · g,
A large-capacity rotating electric machine comprising a high-strength Ni-Cr-Mo-V alloy steel having a body diameter of the rotor shaft of 1.0 m or more. 18. A generator having a generator rated capacity of 1,120,000 KVA, a stator and a rotor rotating in the stator and having a conductor coil embedded therein, wherein the stator is directly Water cooled, the rotor was hydrogen gas cooled, and the rotor body diameter was 1.15 to 1.35 m and ((body diameter) ² ×
The machine size required by (body length) is 9 to 1
0 m ³ , a large-capacity generator characterized in that the rotor receives rotation of 3600 rpm. 19. By weight, C 0.15 to 0.30%, Si
0.3% or less, Mn 1.0% or less, Ni 3.0 to 5.0%,
Cr 2.0-3.5%, Mo 0.1-1.0% and V 0.0
3 to 0.35%, Al 0.010% or less, P, S, Sn,
The total amount of Sb and As is 0.025% or less and the balance is substantially F
and a (Ni / Cr) ratio of 2.3 or less, a high strength low alloy steel.