KR20100033421A - Rotor for low pressure turbine - Google Patents

Abstract

It is an object of the present invention to provide a rotor for a low pressure turbine that can maintain mechanical strength characteristics even when the steam temperature introduced into the low pressure turbine becomes a high temperature, and does not increase the manufacturing cost, the number of production days, and has no problem in terms of quality. A low pressure turbine rotor for use in a steam turbine installation having a high pressure turbine, a medium pressure turbine and a low pressure turbine, comprising: a member formed of 1CrMoV steel, 2.25CrMoV steel, or 10CrMoV steel disposed on the steam inlet side, and a steam outlet side. A member formed of 3.5Ni steel to be joined is formed by welding. Alternatively, the members disposed on the vapor inlet side formed of all 3.5 Ni steel and the member disposed on the vapor outlet side are formed by welding, and the members disposed on the vapor inlet side are in weight%, Si: 0.1%. Mn: 0.1% or less, unavoidable impurities in weight%, 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: 0.02% Hereinafter, it is set as the low impurity 3.5Ni steel containing Cu: 0.1% or less.

Description

ROTOR FOR LOW PRESSURE TURBINE

TECHNICAL FIELD The present invention relates to a rotor for a low pressure turbine for use in a steam turbine installation having a high pressure turbine, a medium pressure turbine and a low pressure turbine, in particular for a low pressure turbine suitable for use in a steam turbine installation having a high steam inlet temperature of 380 ° C or higher. It's about the rotor.

Currently, three main methods of nuclear power, thermal power, and hydropower are used as the main power generation methods, and it is expected that the three power generation methods will be used as main power generation methods from the viewpoint of resource amount and energy density. In particular, thermal power generation is expected to continue to play an important role in the power generation field due to its high value of use as a power generation method that is safe and capable of responding to load fluctuations.

In the steam turbine installation used for coal-fired power generation including a steam turbine, generally, the high pressure turbine, the medium pressure turbine, and the low pressure turbine are equipped, and 600 degreeC steam is used. In such a steam turbine facility, the steam of 600 ° C supplied from the boiler is introduced into the high pressure turbine, and the expansion work is performed by rotating the high pressure turbine with a high pressure blade stage consisting of a moving blade and a stator vane. The exhaust gas is discharged from the high pressure turbine and introduced into the medium pressure turbine, and in the same manner as the high pressure turbine, the intermediate pressure turbine is rotated to perform the expansion work.

The rotor for low pressure turbine in such a steam turbine installation is generally formed with 3.5Ni steel (for example, 3.5NiCrMoV steel, etc.), and the low pressure turbine inlet steam temperature is 3.5Ni steel for mechanical strength characteristics and toughness. It was set to 380 degrees C or less which is maintainable temperature.

In the steam turbine plant as described above, the CO ₂ emissions reduction and recently, a technique employed to improve the thermal efficiency of the gailcheung, more than 630 ℃ steam condition is required.

When a steam of 630 ° C. or higher is introduced into the high pressure turbine as a high pressure turbine, and the same high pressure turbine and the medium pressure turbine as in the case of using the 600 ° C. class steam are used, the low pressure turbine inlet steam temperature is about 400 to 430 ° C. higher than before. Therefore, there is a possibility that the rotor of the 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 reheating pressure in the second stage is lowered, so that the low-pressure turbine inlet steam temperature rises higher than the first-stage reheating and becomes more stringent as a design condition.

In order to maintain the mechanical strength characteristics and toughness of the rotor of the low pressure turbine formed of 3.5Ni steel using steam of 630 ° C. or higher, the amount of expansion work in the high pressure turbine and the medium pressure turbine is increased than before, and the low pressure turbine inlet It is contemplated to lower the steam temperature up to 380 ° C. However, for this purpose, it is necessary to increase the number of blade stages of a high pressure turbine and a medium pressure turbine, and there exists a problem that the whole turbine increases.

Therefore, in Patent Document 1, by reducing the impurity content contained in the 3.5Ni steel constituting the low pressure turbine rotor and limiting it to a very small amount, the metal structure phase causing aging brittleness such as grain boundary segregation of impurity elements due to heating. A low pressure turbine rotor is disclosed that can suppress the change and operate stably even when steam of 380 ° C or higher is introduced.

In the technique disclosed in Patent Document 1, more precise impurity management is required than in the prior art. However, in particular, since the rotor for low pressure turbines is large, in the technique disclosed in Patent Document 1, when manufacturing an integrated low pressure turbine rotor, the cost increases, or the number of days of manufacture increases, so that the delivery time is delayed, for example, a deviation. There arises a problem that anxiety remains in the reliability of the turbine rotor manufactured, such that the impurity content is likely to exceed the reference value.

[Patent Document 1] Japanese Patent Application Publication No. 2006-170006

Therefore, in view of the problems of the prior art, the present invention can maintain the mechanical strength characteristics even when the steam temperature introduced into the low pressure turbine becomes a high temperature, and also in terms of quality without increasing manufacturing cost and manufacturing days. An object of the present invention is to provide a rotor for a low pressure turbine without problems.

In order to solve the above problems, in the present invention,

In a low pressure turbine rotor used in a steam turbine installation having a high pressure turbine, a medium pressure turbine and a low pressure turbine, 1CrMoV steel (hereinafter referred to as 1Cr steel), 2.25CrMoV steel (hereinafter referred to as 2.25Cr steel) disposed on the steam inlet side, or A member formed of 10CrMoV steel (hereinafter referred to as 10Cr steel) and a member formed of 3.5Ni steel arranged on the vapor outlet side are joined to each other by welding.

Since 1Cr steel, 2.25Cr steel, and 10Cr steel are materials conventionally used in the high pressure turbine rotor and the medium pressure turbine rotor, the material management method is established and it is easy to obtain. Moreover, it is excellent in high temperature resistance compared with 3.5Ni steel.

In addition, 3.5Ni steel is less susceptible to stress corrosion cracking (SCC) than 1Cr steel and 2.25Cr steel. In addition, 10Cr steel is more expensive than 3.5Ni steel.

Therefore, the steam inlet side into which the hot steam is introduced is composed of a member formed of 1Cr steel, 2.25Cr steel, or 10Cr steel, and the flow path (blade length) is widened, and the steam outlet side requiring higher strength is 3.5Ni steel. By constructing the structured member, a rotor for a low pressure turbine excellent in high temperature and stress corrosion cracking is formed, and mechanical strength characteristics and toughness can be maintained even when hot steam is introduced.

In addition, from the viewpoint of embrittlement, 3.5Ni steel and 1Cr steel are substantially equivalent, but 2.25Cr steel and 10Cr steel are superior to 3.5Ni steel. Therefore, if a member composed of 1Cr steel on the steam inlet side is used, the embrittlement susceptibility of the entire low pressure turbine rotor is approximately equal to that of a conventional low pressure turbine rotor composed of 3.5Ni steel as a whole, but the steam inlet side is 2.25Cr steel or When the member composed of 10Cr steel is used, the embrittlement susceptibility of the whole rotor for low pressure turbine is superior to the conventional low pressure turbine rotor which comprised the whole rotor from 3.5Ni steel. Therefore, it is more preferable that the member on the vapor inlet side is formed of 2.25Cr steel or 10Cr steel.

Moreover, in the low pressure turbine rotor used in the steam turbine installation provided with the high pressure turbine, the medium pressure turbine, and the low pressure turbine, the member arrange | positioned by the steam inlet side and the member arrange | positioned by the steam outlet side are comprised by welding. At the same time, both members are formed of 3.5Ni steel, and the member disposed on the vapor inlet side is formed of 3.5Ni steel of low impurity.

The low impurity 3.5Ni steel disposed on the vapor inlet side is, in weight%, Si: 0.1% or less, Mn: 0.1% or less, unavoidable impurities in weight%, 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: 0.02% or less, Cu: 0.1% or less.

By using a member made of 3.5Ni steel with a limited amount of impurities on the steam inlet side where high temperature steam is introduced, a change in the metal structure causing aging, such as grain boundary segregation of impurity elements due to heating, can be achieved. It can suppress and operate stably even if the steam of 380 degreeC or more is introduce | transduced.

In addition, by making the member made of 3.5Ni steel having the reduced impurity content only at the steam inlet side through which high-temperature steam is introduced, not at the entire rotor, the increase in manufacturing cost and the number of days can be suppressed to a small degree, resulting in unstable reliability in terms of quality. It is possible to manufacture small and low pressure rotors.

In addition, the inlet steam temperature of the low pressure turbine is used in a steam turbine installation of 380 ℃ or more,

A region in which the steam temperature flowing in the low pressure turbine becomes 380 ° C. or more is constituted by a member disposed on the steam inlet side, and a region in which the steam temperature flowing in the low pressure turbine becomes less than 380 ° C. is in the steam outlet side. It is characterized by comprising a member disposed in the.

Normal 3.5Ni steel is likely to cause aging brittleness such as grain boundary segregation of impurity elements when the vapor temperature is 380 ° C or higher. Therefore, by constructing a region where the steam temperature is 380 ° C or higher by the member disposed on the steam inlet side, and configuring a region where the steam temperature is less than 380 ° C by the member disposed on the steam outlet side, the ordinary 3.5Ni steel No contact with steam of 380 ° C. or higher can be prevented, and it becomes possible to suppress embrittlement of a member formed of 3.5Ni steel disposed on the steam outlet side.

At least one of the inlet steam temperature of the high-pressure turbine and the medium-pressure turbine is characterized in that it is used in a steam turbine installation of 630 ℃ or more.

As a result, without a high-pressure turbine and the intermediate pressure turbine anger increase and it is possible to reduce the CO ₂ emissions from the steam-turbine plant, it is possible to improve the thermal efficiency of the steam turbine plant.

As described above, according to the present invention, even in the case where the steam temperature introduced into the low pressure turbine becomes a high temperature, the mechanical strength characteristics can be maintained, and the low pressure without any problems in terms of quality without increasing the manufacturing cost and manufacturing days. A rotor for a turbine can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the steam turbine power generation facility in 1st Example.
FIG. 2: is a top view which shows typically the structure of the low pressure turbine rotor in Example 1. FIG.
3 is a plan view schematically showing the configuration of a low pressure turbine rotor in the second embodiment.
4 is a graph showing the embrittlement coefficients 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 exhaust, and the like of the component parts described in the present embodiment are not merely intended to limit the scope of the present invention thereto unless otherwise specified, and are merely illustrative examples. .

(First embodiment)

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the steam turbine power generation facility in 1st Example.

With reference to FIG. 1, the power generation installation comprised by the steam turbine installation using the low pressure turbine rotor of this invention is demonstrated. In addition, FIG. 1 is an example of 1st stage reheating, This invention is applied even if implementation of 2nd stage reheating and reheating only by high temperature (630 degreeC or more) is not specifically limited.

The steam turbine power generation equipment 10 shown in FIG. 1 is mainly composed of a high pressure turbine 14, a medium pressure turbine 12, a low pressure turbine 16, a generator 18, a condenser 20, and a boiler 24. Steam is boiler 24, main engine 26, high pressure turbine 14, low temperature reheating tube 28, boiler 24, high temperature reheating tube 30, medium pressure turbine 12, crossover tube 32 The low pressure turbine 16, the condenser 20, the feed water pump 22, and the boiler 24 are circulated in this order.

Steam superheated above 630 ° C. in the boiler 24 is introduced into the high pressure turbine 14 through the main steam engine 26. The steam introduced into the high pressure turbine 14 is exhausted after the expansion work and is returned to the boiler 24 through the low temperature reheat tube 28. The steam returned to the boiler 24 is reheated in the boiler 24 to become steam of 630 ° C. or higher, and is sent to the medium pressure turbine 12 through the high temperature reheating tube 30. The steam introduced into the medium pressure turbine 12 is exhausted after the expansion work, and becomes steam of about 400 to 430 ° C. and is sent to the low pressure turbine 16 through the crossover pipe 32. The steam introduced into the low pressure turbine 16 is exhausted after the expansion work and sent to the condenser 20. The steam sent to the condenser 20 is condensed in the condenser 20, boosted by the feed water pump 22, and returned to the boiler 24. The generator 18 is rotationally driven by the expansion day of each turbine to generate power.

FIG. 2: is a top view which shows typically the structure of the rotor used for the low pressure turbine 16 in 1st Example.

A rotor for a low pressure turbine used in the steam turbine power generation facility as described above will be described with reference to FIG. 2.

(Configuration)

First, the structure of the rotor used for the low pressure turbine 16 into which the steam of about 400-430 degreeC which concerns on a present Example is introduce | transduced using FIG. 2 is demonstrated.

As shown in Fig. 2, the low-pressure turbine rotor 16A includes one member (hereinafter referred to as chrome steel portion) 16a composed of 1Cr steel, 2.25Cr steel, or 10Cr steel, and two composed of 3.5Ni steel. It consists of members (hereinafter usually 3.5Ni steel part) 16b, 16c.

The chrome steel portions 16a are joined to the 3.5 Ni steel portions 16b and 16c by welding, respectively, at both ends thereof, and the order of the 3.5 Ni steel portions 16b, the chrome steel portions 16a, and the Ni steel portions 16c from one end is normally. 16A of low-pressure turbines integrated with the shaft are formed.

Further, the chrome steel portions 16a are disposed at positions exposed to steam at 380 ° C. or higher, and the 3.5Ni steel portions 16b, 16c are disposed at positions exposed to steam at less than 380 degrees Celsius.

(material)

Next, the material of the chrome steel part 16a and the 3.5Ni steel parts 16b and 16c which comprise the low pressure turbine rotor 16A is demonstrated.

(A) Chrome steel part

The chromium steel is formed of 1Cr steel, 2.25Cr or 10Cr steel, which has excellent high temperature resistance and is easily available.

As 1Cr steel, by weight%, C: 0.2-0.4%, Si: 0.35% or less, Mn: 1.5% or less, Ni: 2.0% or less, Cr: 0.5-1.5%, Mo: 0.5-1.5%, V: 0.2 It is mentioned as an example the material of the composition which consists of -0.3% and remainder is Fe and an unavoidable impurity.

As 2.25Cr steel, by weight%, C: 0.2-0.35%, Si: 0.35% or less, Mn: 1.5% or less, Ni: 0.2-2.0%, Cr: 1.5-3.0%, Mo: 0.9-1.5%, V : The material of the composition which consists of 0.2 to 0.3% and remainder is Fe and an unavoidable impurity is mentioned as an example.

As 10Cr steel by weight%, C: 0.05-0.4%, Si: 0.35% or less, Mn: 2.0% or less, Ni: 3.0% or less, Cr: 7-13%, Mo: 0.1-3.0%, V: 0.01 A material having a composition containing from 0.5% to 0.5%, N from 0.01% to 0.1%, and Nb from 0.01% to 0.2%, with the balance being made of Fe and unavoidable impurities, is mentioned as an example.

As another example of 10Cr steel, by weight%, C: 0.05 to 0.4%, Si: 0.35% or less, Mn: 2.0% or less, Ni: 7.0% or less, Cr: 8-15%, Mo: 0.1-3.0%, V: The material of the composition containing 0.01 to 0.5%, N: 0.01 to 0.1%, and Nb: 0.2% or less, and remainder consists of Fe and an unavoidable impurity is mentioned as an example.

4 is a graph showing the embrittlement coefficients of 1Cr steel, 2.25Cr steel, 10Cr steel, and 3.5Ni steel. The vertical axis is the embrittlement coefficient (ΔFATT), which is an index of ease of embrittlement, and the higher the numerical value is, the easier the embrittlement becomes. The abscissa indicates the impurity concentration in J-Factor. As is apparent from FIG. 4, all materials are more likely to embrittle as the impurity concentration is higher. Further, the 1Cr steel and the 3.5Ni steel have roughly equivalent embrittlement coefficients, the embrittlement coefficient of 2.25Cr steel is lower than that, and the embrittlement coefficient of 10Cr steel is even lower.

Therefore, when the chromium steel part 16a uses the member which consists of 1Cr steel, the embrittlement susceptibility of the whole low pressure turbine rotor can be said to be substantially equivalent to the conventional low pressure turbine rotor which comprised the whole rotor from 3.5Ni steel. However, when the chrome steel portions 16b and 16c are made of a member composed of 2.25Cr steel or 10Cr steel, the embrittlement susceptibility of the entire low pressure turbine rotor is lower than that of the conventional low pressure turbine rotor composed of 3.5Ni steel as a whole. It can be said that it is difficult to embrittle. Therefore, it is more preferable to form the chromium steel part 16a from 2.25Cr steel or 10Cr steel.

(B) 3.5Ni steel part

As 3.5Ni steel, C: 0.4% or less, Si: 0.35% or less, Mn: 1.0% or less, Cr: 1.0-2.5%, V: 0.01-0.3%, Mo: 0.1-1.5%, Ni: 3.0 by weight% It contains-4.5%, and remainder is mentioned as an example of the material which consists of Fe and an unavoidable impurity.

(Production method)

Joining is performed by welding in the welded portion between the chrome steel portions 16a and the 3.5Ni steel portions 16b and 16c.

The welding method is not particularly limited as long as the welded portion can withstand the operating state of the low-pressure turbine. Examples of the welding method include a general melting method of supplying a welding wire as a solvent to an arc by a welding torch.

For example, as a shape of a weld part, a narrow gap weld joint etc. are employ | adopted, and at the time of welding, the solvent supply | supplied as a welding wire by lamination | stacking by an arc is laminated | stacked every 1 pass, and the inside of the said narrow improvement melt joint is laminated | stacked. It is filled with a solvent and the chrome steel part 16a and the 3.5Ni steel parts 16b and 16c are joined. As said solvent, 3.5Ni steel which is the same material as a 3.5Ni steel part is used normally.

By using the low-pressure turbine rotor as described above, the following effects are obtained.

Since 1Cr steel, 2.25Cr steel, and 10Cr steel are materials conventionally used in the high pressure turbine rotor and the medium pressure turbine rotor, the material management method is established and it is easy to obtain. Moreover, it is excellent in high temperature resistance compared with 3.5Ni steel. In addition, 3.5Ni steel has lower stress corrosion cracking (SCC) sensitivity than 1Cr steel, 2.25Cr steel, and 10Cr steel. Therefore, the steam inlet side into which the hot steam is introduced is composed of a member formed of 1Cr steel, 2.25Cr steel, or 10Cr steel, and the 3.5Ni steel steam outlet side of which the flow path diameter (blade diameter) becomes wider and higher strength is required. By constructing a member composed of a low pressure turbine rotor that is excellent in high temperature and stress corrosion cracking, mechanical strength characteristics can be maintained even when high temperature steam is introduced.

In addition, when the normal 3.5Ni steel has a vapor temperature of 380 ° C. or higher, there is a high possibility of causing aging brittleness such as grain boundary segregation of impurity elements. Therefore, by constructing a region where the steam temperature is 380 ° C or higher by the member disposed on the steam inlet side, and configuring a region where the steam temperature is less than 380 ° C by the member disposed on the steam outlet side, the ordinary 3.5Ni steel No contact with steam of 380 ° C. or higher can be prevented, and it becomes possible to suppress embrittlement of a member formed of 3.5Ni steel disposed on the steam outlet side.

Moreover, even if the inlet steam temperature of the low pressure turbine is higher than before, the mechanical strength characteristics of the low pressure turbine rotor can be maintained, so that steam of 630 ° C. or higher can be used without increasing the high pressure turbine and the medium pressure turbine. By reducing the CO ₂ displacement, the thermal efficiency of the steam turbine installation can be improved.

(2nd Example)

(Configuration)

In the second embodiment, another type of low pressure turbine rotor 16B will be described.

In the second embodiment, as shown in Fig. 3, the low pressure turbine rotor 16B includes one member (hereinafter referred to as low impurity 3.5Ni steel portion) 16d composed of low impurity 3.5Ni steel having a low impurity content. It is usually composed of 3.5Ni steel portions 16b and 16c.

That is, the second embodiment adopts the low impurity 3.5Ni steel portion 16d instead of the chrome steel portion 16a of the low pressure turbine rotor of the first embodiment shown in FIG. Hereinafter, since it is the same as that of 1st Example except the low impurity 3.5Ni steel part 16d, description is abbreviate | omitted.

In addition, the low impurity 3.5Ni steel portion 16d is disposed at a position exposed to steam of 380 ° C or higher, and normally the 3.5Ni steel portions 16b, 16c are disposed at a position exposed to steam of less than 380 ° C.

(material)

The material of the low impurity 3.5Ni steel part 16d is demonstrated.

The low impurity 3.5Ni steel portion 16d is formed of a 3.5Ni steel portion with a low impurity content. As the low impurity 3.5Ni steel portion 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 to 0.3%, Mo: 0.1 to 1.5%, Ni: 3.0 to 4.5%, the remainder being made of Fe and unavoidable impurities, wherein the unavoidable impurities are, by weight%, P: 0.02% or less, S: 0.02% or less, Sn: 0.02% Hereinafter, as an example, the material of the composition which is As: 0.02% or less, Sb: 0.02% or less, Al: 0.02% or less, Cu: 0.1% or less is mentioned.

(Production method)

The low impurity 3.5Ni steel portions 16d and the 3.5Ni steel portions 16b and 16c are welded at each welded portion.

As shown in FIG. 4, the 3.5Ni steel has a low brittle susceptibility and is less likely to be brittle as the impurity concentration is lower.

Therefore, by using the member 16d made of low impurity 3.5Ni steel in which the impurity content is reduced and limited to a small amount on the steam inlet side through which hot steam is introduced, aging brittleness such as grain boundary segregation of impurity elements due to heating can be achieved. By suppressing the change in the induced metal structure, it is possible to operate stably even when steam of 380 ° C or higher is introduced.

In addition, by making the member made of 3.5Ni steel having the reduced impurity content only at the steam inlet side through which high-temperature steam is introduced, not at the entire rotor, the increase in manufacturing cost and the number of days can be suppressed to be small, and the reliability of reliability in terms of quality is reduced. It is possible to create a small low pressure turbine rotor.

In addition, when the normal 3.5Ni steel has a vapor temperature of 380 ° C. or higher, there is a high possibility of causing aging brittleness such as grain boundary segregation of impurity elements. Therefore, by constructing a region where the steam temperature is 380 ° C or higher by the member disposed on the steam inlet side, and configuring a region where the steam temperature is less than 380 ° C by the member disposed on the steam outlet side, the ordinary 3.5Ni steel No contact with steam of 380 ° C. or higher can be prevented, and embrittlement of the member formed of 3.5Ni steel disposed on the vapor outlet side can be suppressed.

Moreover, even if the inlet steam temperature of the low pressure turbine is higher than before, the mechanical strength characteristics of the low pressure turbine rotor can be maintained, so that steam of 630 ° C. or higher can be used without increasing the high pressure turbine and the medium pressure turbine. The CO ₂ emissions can be reduced to improve the thermal efficiency of the steam turbine plant.

Even when the steam temperature introduced into the low pressure turbine becomes high temperature, the mechanical strength characteristics can be maintained, and it can be used as a rotor for a low pressure turbine without any problems in terms of quality without increasing manufacturing cost and manufacturing days.

Claims (5)

A low pressure turbine rotor for use in a steam turbine installation having a high pressure turbine, a medium pressure turbine and a low pressure turbine,
A member formed of 1CrMoV steel, 2.25CrMoV steel or 10CrMoV steel disposed on the vapor inlet side,
A low pressure turbine rotor, characterized in that a member formed of 3.5Ni steel disposed on the vapor outlet side is joined to each other by welding. A low pressure turbine rotor for use in a steam turbine installation having a high pressure turbine, a medium pressure turbine and a low pressure turbine,
The member disposed on the steam inlet side and the member disposed on the steam outlet side are joined by welding, and both members are formed of 3.5Ni steel, and the member disposed on the steam inlet side is 3.5Ni of low impurity. A low pressure turbine rotor, characterized by being formed of steel. The low impurity 3.5Ni steel disposed at the vapor inlet side is in weight%, Si: 0.1% or less, Mn: 0.1% or less, unavoidable impurities in weight%, P: 0.02% or less, S A low pressure turbine rotor comprising: 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 steam turbine installation according to claim 1 or 2, wherein the inlet steam temperature of the low pressure turbine is 380 ° C or higher,
A region in which the steam temperature flowing in the low pressure turbine becomes 380 ° C. or more is constituted by a member disposed on the steam inlet side,
The rotor for low pressure turbines characterized by comprising the member arrange | positioned at the said steam outlet side in the area | region where the steam temperature which flows through the said low pressure turbine becomes less than 380 degreeC. The low pressure turbine rotor according to any one of claims 1 to 4, wherein the inlet steam temperature of at least one of the high pressure turbine and the medium pressure turbine is used at a steam turbine facility of 630 ° C or more.

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