JPWO2010018773A1 - Rotor for low pressure turbine - Google Patents

Abstract

Providing a rotor for low-pressure turbines that can maintain its mechanical strength characteristics even when the temperature of the steam introduced into the low-pressure turbine is high, and that does not increase production costs and production days, and that does not have any quality problems. In a rotor for a low-pressure turbine used in a steam turbine facility equipped with a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine The formed member and the member formed of 3.5Ni steel arranged on the steam outlet side are joined and configured by welding. Alternatively, the members arranged on the steam inlet side formed of 3.5Ni steel and the members arranged on the steam outlet side are joined by welding, and the members arranged on the steam inlet side In wt%, Si: 0.1% or less, Mn: 0.1% or less, unavoidable impurities are wt%, P: 0.02% or less, S: 0.02% or less, Sn: 0.02% Hereinafter, a low-impurity 3.5Ni steel containing As: 0.02% or less, Sb: 0.02% or less, Al: 0.02% or less, and Cu: 0.1% or less.

Description

  The present invention relates to a rotor for a low pressure turbine used in a steam turbine facility including a high pressure turbine, an intermediate pressure turbine, and a low pressure turbine, and is particularly used in a steam turbine facility in which a steam inlet temperature is a high temperature of 380 ° C. or higher. And a preferred low-pressure turbine rotor.

Currently, three methods of nuclear power, thermal power, and hydropower are used as main power generation methods, and it is expected that the three power generation methods will continue to be used as main power generation methods from the viewpoint of the amount of resources and energy density. Is done. Above all, thermal power generation has a high utility value as a power generation method that is safe and capable of handling load fluctuations, and is expected to continue to play an important role in the power generation field.
A steam turbine facility used for coal-fired thermal power generation including a steam turbine generally includes a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, and 600 ° C. class steam is used. In such a steam turbine facility, the 600 ° C. class steam supplied from the boiler is introduced into the high pressure turbine, and the expansion work is performed by rotating the high pressure turbine in a high pressure blade stage composed of moving blades and stationary blades. It is exhausted from the high-pressure turbine and introduced into the intermediate-pressure turbine. Like the high-pressure turbine, the intermediate-pressure turbine is rotated to perform expansion work, and further introduced into the low-pressure turbine to perform expansion work, and then exhausted to the condenser to be recovered. Watered.
The low-pressure turbine rotor in such a steam turbine facility is generally made of 3.5Ni steel (for example, 3.5NiCrMoV steel), and the low-pressure turbine inlet steam temperature is 3.5Ni steel with mechanical strength characteristics and toughness. The temperature was set to 380 ° C. or lower, which is a temperature capable of maintaining the temperature.
In the steam turbine equipment as described above, in recent years, a technique that employs steam conditions of 630 ° C. or higher has been demanded in order to reduce CO ₂ displacement and further improve thermal efficiency.
When steam at 630 ° C or higher is introduced into the high-pressure turbine and the same high-pressure turbine and medium-pressure turbine as those conventionally used for the 600 ° C-class steam are used, the low-pressure turbine inlet steam temperature is about 400 to 430 ° C. There is a possibility that the rotor of a low-pressure turbine cannot maintain mechanical strength characteristics and toughness due to the increase in temperature.
In particular, in the case of two-stage reheating, the reheat pressure in the second stage is lowered, so that the steam temperature at the low-pressure turbine inlet rises more than that in the first stage, and the design conditions become more severe.
In order to maintain the mechanical strength characteristics and toughness of the rotor of the low pressure turbine using steam of 630 ° C. or higher and formed of 3.5Ni steel, the work of expansion in the high pressure turbine and the intermediate pressure turbine is increased as compared with the prior art. Thus, it is conceivable to reduce the steam temperature at the low-pressure turbine inlet to 380 ° C. or lower. However, for that purpose, it is necessary to increase the number of blade stages of the high-pressure turbine and the intermediate-pressure turbine, and there is a problem that the entire turbine increases.
Therefore, in Patent Document 1, the impurity content contained in the 3.5Ni steel constituting the rotor for a low-pressure turbine is reduced and limited to a very small amount so that secular boundary embrittlement such as grain boundary segregation of impurity elements due to heating occurs. There is disclosed a rotor for a low-pressure turbine that suppresses changes in the metal structure that induces crystallization and can be stably operated even when steam of 380 ° C. or higher is introduced.
The technique disclosed in Patent Document 1 requires stricter impurity management than ever before. However, since the rotor for the low-pressure turbine is particularly large, when the integrated low-pressure turbine rotor is manufactured in the technique disclosed in Patent Document 1, the cost increases, the number of manufacturing days increases, and the delivery time is delayed. For example, there is a problem that the reliability in the quality of the turbine rotor to be manufactured remains uneasy, for example, the impurity content is likely to exceed the reference value due to variation.

JP 2006-170006 A

Therefore, in view of the problems of the prior art, the present invention can maintain the mechanical strength characteristics even when the temperature of the steam introduced into the low-pressure turbine is high, and further increases the manufacturing cost and the number of manufacturing days. An object of the present invention is to provide a rotor for a low-pressure turbine that has no problem in terms of quality.
In order to solve the above problems, in the present invention,
1CrMoV steel (hereinafter referred to as 1Cr steel), 2.25CrMoV steel (hereinafter referred to as 2.25Cr steel) disposed on the steam inlet side in a rotor for a low pressure turbine used in a steam turbine facility including a high pressure turbine, an intermediate pressure turbine, and a low pressure turbine ) Or a member formed of 10CrMoV steel (hereinafter referred to as 10Cr steel) and a member formed of 3.5Ni steel arranged on the steam outlet side are joined to each other by welding.
Since 1Cr steel, 2.25Cr steel, and 10Cr steel are materials conventionally used in high-pressure turbine rotors and medium-pressure turbine rotors, a material management method has been established and is easily available. Furthermore, it is superior in high temperature resistance than 3.5Ni steel.
Moreover, 3.5Ni steel is less susceptible to stress corrosion cracking (SCC) than 1Cr steel and 2.25Cr steel. Also, 10Cr steel is more expensive than 3.5Ni steel.
Therefore, the steam inlet side into which high-temperature steam is introduced is composed of a member formed of 1Cr steel, 2.25Cr steel, or 10Cr steel, and the steam outlet side where the flow path (blade length) is widened and higher strength is required. By constituting with a member made of 3.5Ni steel, a rotor for a low pressure turbine excellent against high temperature and stress corrosion cracking is formed, and mechanical strength characteristics and toughness are maintained even when high temperature steam is introduced. be able to.
Furthermore, from the viewpoint of embrittlement, 3.5Ni steel and 1Cr steel are almost equivalent, but 2.25Cr steel and 10Cr steel are superior to 3.5Ni steel. Therefore, when a member made of 1Cr steel is used on the steam inlet side, the embrittlement susceptibility of the entire low-pressure turbine rotor is almost the same as that of a conventional low-pressure turbine rotor in which the entire rotor is made of 3.5Ni steel. When a member made of 2.25Cr steel or 10Cr steel is used on the steam inlet side, the embrittlement susceptibility of the entire low-pressure turbine rotor is superior to that of a conventional low-pressure turbine rotor in which the entire rotor is made of 3.5Ni steel. ing. Therefore, the member on the steam inlet side is more preferably formed of 2.25Cr steel or 10Cr steel.
Further, in a rotor for a low pressure turbine used in a steam turbine facility including a high pressure turbine, an intermediate pressure turbine, and a low pressure turbine, a member disposed on the steam inlet side and a member disposed on the steam outlet side are joined by welding. Both members are formed of 3.5Ni steel, and the member disposed on the steam inlet side is formed of low-impurity 3.5Ni steel.
The low-impurity 3.5Ni steel disposed on the vapor inlet side is, by weight, Si: 0.1% or less, Mn: 0.1% or less, unavoidable impurities are wt%, and P: 0.0. 02% or less, S: 0.02% or less, Sn: 0.02% or less, As: 0.02% or less, Sb: 0.02% or less, Al: 0.02% or less, Cu: 0.1% It contains the following.
By using a member made of 3.5Ni steel with a reduced impurity content and limited to a small amount on the steam inlet side where high-temperature steam is introduced, secular boundary embrittlement such as grain boundary segregation of impurity elements due to heating It is possible to suppress the change in the metal structure that induces the phenomenon and to operate stably even when steam at 380 ° C. or higher is introduced.
In addition, since the member made of 3.5Ni steel with a reduced impurity content is not the entire rotor but only the steam inlet side where high-temperature steam is introduced, the increase in production cost and days can be kept small, and the quality side Therefore, it is possible to manufacture a rotor for a low-pressure turbine.
In addition, the low pressure turbine is used in steam turbine equipment having an inlet steam temperature of 380 ° C. or higher,
A region where the steam temperature flowing through the low-pressure turbine is 380 ° C. or higher is configured by a member disposed on the steam inlet side, and a region where the steam temperature flowing through the low-pressure turbine is less than 380 ° C. is the steam outlet It comprises the member arrange | positioned at the side, It is characterized by the above-mentioned.
Normal 3.5Ni steel has a high possibility of inducing embrittlement over time such as grain boundary segregation of impurity elements when the vapor temperature is 380 ° C. or higher. Therefore, a region where the steam temperature is 380 ° C. or more is configured with a member disposed on the steam inlet side, and a region where the steam temperature is less than 380 ° C. is configured with a member disposed on the steam outlet side, The 3.5Ni steel does not come into contact with the steam at 380 ° C. or higher, and it becomes possible to suppress embrittlement of the member formed of the 3.5Ni steel disposed on the steam outlet side.
It is used in steam turbine equipment in which the inlet steam temperature of at least one of the high-pressure turbine and the intermediate-pressure turbine is 630 ° C. or higher.
Thereby, without increasing the high-pressure turbine and the intermediate-pressure turbine, the CO ₂ exhaust amount from the steam turbine equipment can be reduced, and the thermal efficiency of the steam turbine equipment can be improved.
As described above, according to the present invention, even when the temperature of the steam introduced into the low-pressure turbine is high, the mechanical strength characteristics can be maintained, and further, the quality can be improved without increasing the manufacturing cost and the number of production days. However, it is possible to provide a rotor for a low-pressure turbine that has no problem.

It is a figure which shows the structure of the steam turbine power generation equipment in Example 1. FIG. 1 is a plan view schematically showing a configuration of a low-pressure turbine rotor in Embodiment 1. FIG. 6 is a plan view schematically showing a configuration of a low-pressure turbine rotor in Embodiment 2. FIG. It is a graph which shows the embrittlement coefficient of 1Cr steel, 2.25Cr steel, 10Cr steel, and 3.5Ni steel.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

FIG. 1 is a diagram illustrating a configuration of a steam turbine power generation facility in the first embodiment.
With reference to FIG. 1, the power generation equipment comprised by the steam turbine equipment using the rotor for low pressure turbines of this invention is demonstrated. Note that FIG. 1 is an example of one-stage reheating, and the present invention is also applicable to implementation in the case where only two-stage reheating and reheating are performed at a high temperature (630 ° C. or higher), and are not particularly limited.
The steam turbine power generation facility 10 shown in FIG. 1 mainly includes a high pressure turbine 14, an intermediate pressure turbine 12, a low pressure turbine 16, a generator 18, a condenser 20, and a boiler 24. Steam includes a boiler 24, a main steam pipe 26, a high-pressure turbine 14, a low-temperature reheat pipe 28, a boiler 24, a high-temperature reheat pipe 30, a medium-pressure turbine 12, a crossover pipe 32, a low-pressure turbine 16, a condenser 20, and a feed water pump 22. Circulate in the order of the boiler 24.
The steam superheated to 630 ° C. or higher in the boiler 24 is introduced into the high-pressure turbine 14 through the main steam pipe 26. The steam introduced into the high-pressure turbine 14 is exhausted after performing expansion work, and returned to the boiler 24 through the low-temperature reheat pipe 28. The steam returned to the boiler 24 is reheated by the boiler 24 to become steam at 630 ° C. or higher, and is sent to the intermediate pressure turbine 12 through the high-temperature reheat pipe 30. The steam introduced into the intermediate pressure turbine 12 is exhausted after performing expansion work, and is sent to the low pressure turbine 16 through the crossover pipe 32 as steam at about 400 to 430 ° C. The steam introduced into the low-pressure turbine 16 is exhausted after performing expansion work and sent to the condenser 20. The steam sent to the condenser 20 is condensed by the condenser 20, boosted by the water supply pump 22, and returned to the boiler 24. The generator 18 is rotationally driven by the expansion work of each turbine and generates electricity.
FIG. 2 is a plan view schematically showing the configuration of the rotor used in the low-pressure turbine 16 in the first embodiment.
A low-pressure turbine rotor used in the steam turbine power generation facility as described above will be described with reference to FIG.
(Constitution)
First, the configuration of the rotor used in the low-pressure turbine 16 into which steam of about 400 to 430 ° C. according to the present embodiment is introduced will be described with reference to FIG.
As shown in FIG. 2, the low-pressure turbine rotor 16A includes one member (hereinafter referred to as a chrome steel portion) 16a made of 1Cr steel, 2.25Cr steel, or 10Cr steel, and two pieces made of 3.5Ni steel. It consists of members (hereinafter usually 3.5Ni steel parts) 16b and 16c.
The chrome steel portion 16a is joined to the normal 3.5Ni steel portions 16b and 16c by welding at both ends, respectively, and the normal 3.5Ni steel portion 16b, the chrome steel portion 16a and the Ni steel portion 16c are integrated in order from one end portion. The low-pressure turbine rotor 16A is formed.
Moreover, the chromium steel part 16a is arrange | positioned in the position exposed to the vapor | steam of 380 degreeC or more, and 3.5Ni steel parts 16b and 16c are normally arrange | positioned in the position exposed to the vapor | steam below 380 degreeC.
(material)
Next, materials of the chromium steel portion 16a and the 3.5Ni steel portions 16b and 16c constituting the low pressure turbine rotor 16A will be described.
(A) Chrome steel part The chromium steel part is made of 1Cr steel, 2.25Cr or 10Cr steel, which is excellent in high temperature resistance and easily available.
As 1Cr steel, C: 0.2-0.4%, Si: 0.35% or less, Mn: 1.5% or less, Ni: 2.0% or less, Cr: 0.5- An example is a material having a composition of 1.5%, Mo: 0.5 to 1.5%, V: 0.2 to 0.3%, and the balance consisting of Fe and inevitable impurities.
As the 2.25Cr steel, by weight, C: 0.2 to 0.35%, Si: 0.35% or less, Mn: 1.5% or less, Ni: 0.2 to 2.0%, Cr : 1.5-3.0%, Mo: 0.9-1.5%, V: 0.2-0.3%, the material of which the balance consists of Fe and inevitable impurities may be mentioned as an example. it can.
As 10Cr steel, C: 0.05-0.4% by weight, Si: 0.35% or less, Mn: 2.0% or less, Ni: 3.0% or less, Cr: 7-13%, Mo: 0.1 to 3.0%, V: 0.01 to 0.5%, N: 0.01 to 0.1%, Nb: 0.01 to 0.2%, the balance being Fe As an example, a material having a composition comprising inevitable impurities can be given.
As another example of 10Cr steel, C: 0.05 to 0.4% by weight, Si: 0.35% or less, Mn: 2.0% or less, Ni: 7.0% or less, Cr: 8 to 15%, Mo: 0.1-3.0%, V: 0.01-0.5%, N: 0.01-0.1%, Nb: 0.2% or less, with the balance being Fe As an example, a material having a composition comprising inevitable impurities can be given.
FIG. 4 is a graph showing embrittlement coefficients of 1Cr steel, 2.25Cr steel, 10Cr steel, and 3.5Ni steel. The vertical axis represents the embrittlement coefficient (ΔFATT), which is a value indicating the degree of embrittlement. The higher this value, the higher the embrittlement susceptibility and the more easily embrittlement occurs. The horizontal axis is J-Factor, which is a value serving as an index of impurity concentration. As is clear from FIG. 4, any material is more likely to become brittle as the impurity concentration is higher. Further, 1Cr steel and 3.5Ni steel have substantially the same embrittlement coefficient, and 2.25Cr steel has a lower embrittlement coefficient than that, and 10Cr steel has a further lower embrittlement coefficient.
Therefore, when a member composed of 1Cr steel is used for the chrome steel portion 16a, the embrittlement susceptibility of the entire low-pressure turbine rotor is substantially equal to that of a conventional low-pressure turbine rotor composed of 3.5Ni steel. I can say that. However, when members made of 2.25Cr steel or 10Cr steel are used for the chrome steel parts 16b and 16c, the embrittlement susceptibility of the entire rotor for low-pressure turbines is the conventional low-pressure turbine in which the entire rotor is composed of 3.5Ni steel. It can be said that it is lower than the rotor for use, that is, it is difficult to become brittle. Therefore, it is more preferable that the chrome steel portion 16a is formed of 2.25Cr steel or 10Cr steel.
(B) Normal 3.5Ni steel part As 3.5Ni steel, C: 0.4% or less, Si: 0.35% or less, Mn: 1.0% or less, Cr: 1.0-2 in weight%. .5%, V: 0.01 to 0.3%, Mo: 0.1 to 1.5%, Ni: 3.0 to 4.5%, the balance being Fe and inevitable impurities Can be cited as an example.
(Production method)
It joins by welding in the welding part between the chromium steel part 16a and the 3.5Ni steel parts 16b and 16c normally.
The welding method is not particularly limited as long as the welded part can withstand the operation state of the low-pressure turbine. As an example, a general melting method for supplying a welding wire as a filler to an arc by a welding torch is given. be able to.
For example, a narrow groove welded joint or the like is adopted as the shape of the welded portion. During welding, a filler supplied as a welding wire is laminated by arc melting for each pass, and the inside of the narrow groove melted joint is laminated. Is filled with a filler, and the chromium steel portion 16a and the normal 3.5Ni steel portions 16b and 16c are joined. As the filler, 3.5Ni steel, which is usually the same material as the 3.5Ni steel part, is used.
By using the low-pressure turbine rotor as described above, the following effects can be obtained.
Since 1Cr steel, 2.25Cr steel, and 10Cr steel are materials conventionally used in high-pressure turbine rotors and medium-pressure turbine rotors, a material management method has been established and is easily available. Furthermore, it is superior in high temperature resistance than 3.5Ni steel. Moreover, 3.5Ni steel is less susceptible to stress corrosion cracking (SCC) than 1Cr steel, 2.25Cr steel, and 10Cr steel. Therefore, the steam inlet side into which high-temperature steam is introduced is composed of a member formed of 1Cr steel, 2.25Cr steel, or 10Cr steel, and the steam outlet side where the flow path diameter (blade diameter) is widened and higher strength is required. By using a member made of 3.5Ni steel, a rotor for low-pressure turbines excellent against high temperature and stress corrosion cracking is formed, and mechanical strength characteristics can be maintained even when high temperature steam is introduced. it can.
Further, when the vapor temperature of ordinary 3.5Ni steel is 380 ° C. or higher, there is a high possibility of inducing embrittlement over time such as grain boundary segregation of impurity elements. Therefore, a region where the steam temperature is 380 ° C. or more is configured with a member disposed on the steam inlet side, and a region where the steam temperature is less than 380 ° C. is configured with a member disposed on the steam outlet side, The 3.5Ni steel does not come into contact with the steam at 380 ° C. or higher, and it becomes possible to suppress embrittlement of the member formed of the 3.5Ni steel disposed on the steam outlet side.
Furthermore, since the mechanical strength characteristics of the rotor for the low-pressure turbine can be maintained even if the inlet steam temperature of the low-pressure turbine is higher than before, the steam at 630 ° C. or higher can be maintained without increasing the high-pressure turbine and the intermediate-pressure turbine. Can be used, the amount of CO ₂ exhaust from the steam turbine equipment can be reduced, and the thermal efficiency of the steam turbine equipment can be improved.

(Constitution)
Another embodiment of the low-pressure turbine rotor 16B will be described in the second embodiment.
In the second embodiment, as shown in FIG. 3, the low pressure turbine rotor 16B includes one member (hereinafter referred to as a low impurity 3.5Ni steel part) 16d composed of a low impurity 3.5Ni steel with a low impurity content. It is usually composed of 3.5Ni steel parts 16b and 16c.
That is, Example 2 is a form which employ | adopted the low impurity 3.5Ni steel part 16d instead of the chromium steel part 16a of the rotor for low pressure turbines of the form of Example 1 shown in FIG. Hereinafter, since it is the same as that of Example 1 except the low impurity 3.5Ni steel part 16d, description is abbreviate | omitted.
The low-impurity 3.5Ni steel part 16d is disposed at a position exposed to steam of 380 ° C. or higher, and the normal 3.5Ni steel parts 16b and 16c are disposed at positions exposed to steam lower than 380 ° C.
(material)
The material of the low impurity 3.5Ni steel part 16d will be described.
The low impurity 3.5Ni steel part 16d is formed of a 3.5Ni steel part having a small impurity content. As the low impurity 3.5Ni steel part 16d, by weight, C: 0.4% or less, Si: 0.1% or less, Mn: 0.1% or less, Cr: 1.0 to 2.5%, V: 0.01-0.3%, Mo: 0.1-1.5%, Ni: 3.0-4.5%, the balance consists of Fe and unavoidable impurities, the unavoidable impurities However, by weight percent, P: 0.02% or less, S: 0.02% or less, Sn: 0.02% or less, As: 0.02% or less, Sb: 0.02% or less, Al: 0. A material having a composition of 02% or less and Cu: 0.1% or less can be given as an example.
(Production method)
It joins by welding in the welding part between the low impurity 3.5Ni steel part 16d and the normal 3.5Ni steel parts 16b and 16c.
As shown in FIG. 4, the 3.5Ni steel has a lower brittleness sensitivity and lower embrittlement as the impurity concentration is lower.
Therefore, by using the member 16d made of low-impurity 3.5Ni steel with a reduced impurity content and limited to a very small amount on the steam inlet side where high-temperature steam is introduced, grain boundary segregation of impurity elements due to heating, etc. A change in the metal structure that induces aging embrittlement is suppressed, and stable operation is possible even when steam at 380 ° C. or higher is introduced.
In addition, since the member made of 3.5Ni steel with a reduced impurity content is not the entire rotor but only the steam inlet side where high-temperature steam is introduced, the increase in production cost and days can be kept small, and the quality side Therefore, it is possible to create a rotor for a low-pressure turbine.
Further, when the vapor temperature of ordinary 3.5Ni steel is 380 ° C. or higher, there is a high possibility of inducing embrittlement over time such as grain boundary segregation of impurity elements. Therefore, a region where the steam temperature is 380 ° C. or more is configured with a member disposed on the steam inlet side, and a region where the steam temperature is less than 380 ° C. is configured with a member disposed on the steam outlet side, The 3.5Ni steel does not come into contact with the steam at 380 ° C. or higher, and it becomes possible to suppress embrittlement of the member formed of the 3.5Ni steel disposed on the steam outlet side.
Furthermore, since the mechanical strength characteristics of the rotor for the low-pressure turbine can be maintained even if the inlet steam temperature of the low-pressure turbine is higher than before, the steam at 630 ° C. or higher can be maintained without increasing the high-pressure turbine and the intermediate-pressure turbine. Can be used, the amount of CO ₂ exhaust from the steam turbine equipment can be reduced, and the thermal efficiency of the steam turbine equipment can be improved.

  Even when the temperature of the steam introduced into the low-pressure turbine is high, the mechanical strength characteristics can be maintained, and it can be used as a rotor for low-pressure turbines with no problems in quality without increasing manufacturing costs and production days. can do.

Claims (5)

In a rotor for a low-pressure turbine used in a steam turbine facility including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine,
A member formed of 1CrMoV steel, 2.25CrMoV steel or 10CrMoV steel disposed on the steam inlet side;
A rotor for a low-pressure turbine, characterized in that a member formed of 3.5Ni steel disposed on the steam outlet side is joined by welding. In a rotor for a low-pressure turbine used in a steam turbine facility including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine,
A member disposed on the steam inlet side and a member disposed on the steam outlet side are joined and configured by welding, and both members are formed of 3.5Ni steel, and the member disposed on the steam inlet side A low-pressure turbine rotor characterized by being made of low-impurity 3.5Ni steel.   The low-impurity 3.5Ni steel disposed on the steam inlet side is, by weight%, Si: 0.1% or less, Mn: 0.1% or less, unavoidable impurities are weight%, P: 0.02% Hereinafter, S: 0.02% or less, Sn: 0.02% or less, As: 0.02% or less, Sb: 0.02% or less, Al: 0.02% or less, Cu: 0.1% or less The low-pressure turbine rotor according to claim 2, wherein the rotor is contained. Used in steam turbine equipment where the steam temperature at the inlet of the low-pressure turbine is 380 ° C. or higher;
A region in which the steam temperature circulating in the low-pressure turbine is 380 ° C. or higher is configured with a member disposed on the steam inlet side,
The rotor for a low-pressure turbine according to claim 1 or 2, wherein a region in which a steam temperature flowing through the low-pressure turbine is less than 380 ° C is configured by a member disposed on the steam outlet side.   The rotor for a low-pressure turbine according to any one of claims 1 to 4, wherein the rotor is used in a steam turbine facility in which an inlet steam temperature of at least one of the high-pressure turbine and the intermediate-pressure turbine is 630 ° C or higher. .

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