JP2002339036A - Integrated turbine rotor for high-low pressure and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an integrated turbine rotor for a high-low pressure which gives excellent high temperature strength and no creep embrittlement as a high pressure part and as a low pressure part excellent toughness, and a production method therefor. SOLUTION: The integrated turbine rotor for the high-low pressure in which high creep strength is realized without generating creep embrittlement by forming a structure of the high pressure part of CrMoV heat resistant steel containing tungsten into the martensitic one where a pro-eutectoid ferritic phase of >10% to <=40% is contained in a bainitic phase is adopted. Alternatively, the integrated turbine rotor for the high-low pressure which has increased smooth creep strength by adding elements such as Co, Nb, Ta, N and B to the steel is provided. Further, the method for producing the high-low integrated type turbine rotor using the steel having the above composition is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine rotor and a method of manufacturing the same, and more particularly, to a high-low pressure integrated turbine rotor used for a steam turbine used in thermal power generation and the like, and a method of manufacturing the same. .

[0002]

2. Description of the Related Art Conventionally, as one of turbine rotors for a steam turbine for thermal power generation, a high / low pressure integrated turbine rotor using a material integrated from a high pressure portion to a low pressure portion is known. Although the steam turbine is exposed to high-temperature and high-pressure steam at the steam inlet side, the temperature and pressure of the steam decrease as approaching the terminal end, and the steam is exposed to the steam which has significantly expanded in volume. Therefore, in the high pressure part, the length of the turbine blade is short, and the stress applied to the turbine rotor is relatively small. Therefore, the diameter of the turbine rotor may be small. On the other hand, in the low-pressure section, the length of the turbine blade must be increased to receive a large amount of steam force, and the diameter of the turbine rotor must be increased, so that the stress applied to the turbine rotor becomes large. Therefore, as the characteristics required for the high-low pressure integrated turbine rotor, high-pressure parts require high-temperature strength, particularly excellent creep strength, while low-pressure parts require mechanical strength at room temperature and excellent toughness.

Conventionally, examples of heat-resistant steels used in high-low pressure integrated turbine rotors include low-alloy CrMoV steel and high-Cr 12Cr steel (Japanese Patent Application Laid-Open No. 60-165359;
JP-A-62-103345) has been exclusively used. A method has been proposed in which a CrMoV-based steel type is used to process a turbine rotor material, and the turbine rotor is divided into a high-pressure portion and a low-pressure portion and subjected to heat treatment under different conditions to obtain a turbine rotor having both creep characteristics and toughness. ing. For example, Japanese Unexamined Patent Publication No. Hei. 5-195068 discloses that a high-pressure portion of the turbine rotor material is heated to a temperature higher than that of a low-pressure portion and then quenched, and then the entire turbine rotor material is tempered at a predetermined temperature to obtain an excellent high-temperature portion. A method for obtaining a high-low pressure integrated turbine rotor having both creep strength and toughness is disclosed.

Japanese Patent Laid-Open Publication No. Hei 8-176671 discloses that a turbine rotor material is normalized at 1000 to 1150 ° C., then transformed into pearlite, further normalized at 920 to 950 ° C., and then a high pressure part and a low pressure part are treated at different temperatures. There is disclosed a method of quenching and thereafter tempering the entire turbine rotor material to obtain a high-low pressure integrated turbine rotor having both excellent high-temperature creep characteristics and toughness.

[0005] However, in recent years, further improvement in energy efficiency has been desired, and the temperature of steam introduced into the turbine tends to be higher and the amount of generated steam tends to increase accordingly. Therefore, the characteristics required for the turbine rotor have become more severe.
For this reason, conventional low-alloy steel turbine rotors are insufficient in high-temperature mechanical properties in the high-pressure part, particularly in creep strength, and it is necessary to develop a material that can withstand use at higher steam temperatures. .

[0006] In the low-pressure portion of the turbine rotor, a material which withstands a larger stress and has high toughness has been required. The use of 12Cr steel as a high-grade material can solve these material problems. However, since the production of the material requires a long period of time, it cannot meet the urgent needs, and has the drawback of increasing the cost. .

[0007] Therefore, in order to produce a low-cost, high-performance, high-low pressure integrated turbine in a short delivery time, an inexpensive low-alloy steel is used, and a high-low pressure integrated turbine excellent in high-temperature mechanical properties in a high-pressure part, particularly excellent in creep strength. Development of a turbine rotor is desired. However, a high-low pressure integrated turbine rotor made of low alloy steel having the above characteristics has not been obtained.

Hitherto, CrMoV steel, which is a low alloy steel, has been used after being quenched from a temperature of about 950 ° C. Increasing the quenching temperature suppresses the precipitation of the soft pro-eutectoid ferrite phase and promotes solid solution of the strengthening element, increasing the material strength.However, there is a problem that creep embrittlement occurs. Could not. Also,
Attempts have been made to suppress embrittlement by adding various alloying elements and devising a heat treatment method, but no satisfactory one has been obtained.

Further, when the quenching temperature is increased, the crystal grains become coarser and the toughness of the material deteriorates. From this point, the quenching temperature cannot be increased to 1,000 ° C. or higher. As described above, the high-temperature strength and brittleness of the CrMoV steel include difficulty in manufacturing due to the conflicting heat treatment conditions.

[0010]

Accordingly, the present invention is to optimize the material components and raise the quenching temperature of the high pressure section,
In a smooth creep test, a material with higher creep rupture characteristics than the high-pressure part of the conventional high-low pressure integrated rotor material, less likely to cause creep embrittlement, and high toughness equivalent to or higher than the conventional material in both the high-pressure part and the low-pressure part The present invention seeks to provide a turbine rotor made of this novel heat-resistant steel.

The inventors of the present invention have already optimized the material components and increased the quenching temperature in the high-pressure part as the main improvements, so that the smooth creep test has a higher creep than that of the conventional high-low pressure integrated rotor material. A low-alloy heat-resistant steel having fracture characteristics, hardly causing creep embrittlement, and having high toughness equivalent to or higher than conventional materials in both high-pressure and low-pressure parts has been proposed. (Japanese Patent Application 2000-031002)

In the previous proposal, it was found that the high temperature properties, particularly the creep embrittlement properties, were greatly affected by impurities, and not only were the prescribed alloys blended, but also phosphorus, sulfur, copper, aluminum, arsenic, tin, antimony. By suppressing harmful trace impurity elements as low as possible, it enables quenching from a high temperature of 980 ° C or higher, has high toughness, has excellent high temperature properties, and is especially suitable for low alloy heat-resistant steel that is unlikely to cause creep embrittlement. The manufacturing method and the turbine rotor made of the low alloy heat resistant steel were proposed.

In addition, the present inventors have found that in low-alloy heat-resistant steel mainly intended for use as a material for a high-pressure turbine rotor, it has been found that creep embrittlement has a close relationship with crystal grain size, It was shown that creep embrittlement can be avoided by controlling the diameter within an appropriate range. (Japanese Patent Application No. 2001-61842)

By the way, in order to refine the crystal grains to a grain size within an appropriate range, it is common to take measures such as performing strong forging, rapid heating treatment, or repeatedly performing heat treatment. It is relatively easy to maintain the target crystal grains because relatively small members can be strongly forged and rapidly heated, but for large members such as turbine rotors, forging and upsetting in the material forging process. There is no other method than repeating the heat treatment or repeating the heat treatment, and the process takes a long time, so that the cost is greatly increased and it is practically difficult to adopt the method.

The present invention has been made in view of the above circumstances, and has been made in consideration of, for example, the toughness of a high-pressure part and the strength characteristics and toughness of a low-pressure part.
After securing the characteristics required for a high-low pressure integrated rotor,
It is an object of the present invention to obtain a high-strength member having excellent high-temperature characteristics, particularly high creep embrittlement resistance, which is uniform in the surface layer and the center of a high-pressure part even in a large-sized material.

[0016]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems, and as a result, have conventionally been considered to be factors causing a decrease in strength and toughness, and can be prevented from being contained in a metal structure. Focusing on the pro-eutectoid ferrite phase, it has been found that creep embrittlement can be avoided while ensuring strength and toughness by actively using the pro-eutectoid ferrite phase in a specific component system.

However, in the case of a large member such as a turbine rotor, the cooling conditions are different between the surface layer and the central portion. There was a problem that an unnecessarily large amount of proeutectoid ferrite was deposited. Further, particularly in a material in which the quenching temperature is increased in order to increase the strength by dissolving the matrix strengthening element as a solid solution, the crystal grains are likely to become coarse, so that there is a possibility that creep embrittlement may be caused.

Therefore, in the process of heat treatment of a material having a predetermined alloy component, the high pressure portion is quenched from a higher temperature region while controlling the cooling rate to precipitate a predetermined amount of a pro-eutectoid ferrite phase, and the low pressure portion is formed by a conventional method. After heating to a temperature equal to or higher than that, by cooling with a method with a large cooling effect, it has excellent creep strength at high pressure parts,
In particular, they have found that it is possible to obtain a high-low pressure integrated turbine rotor that does not cause creep embrittlement and has high toughness in a low-pressure portion, and completed the present invention.

In the high / low pressure integrated turbine rotor of the present invention, the portion used for high pressure steam (high pressure portion) is 600 ° C.
It has excellent high-temperature properties in which the creep rupture time in a smooth creep rupture test under the condition of a stress of 176 MPa is 2,500 hours or more, and the creep rupture time in the notch creep rupture test under the same conditions is 5,000 hours or more. Things.

The part (low-pressure part) used for low-pressure steam of the high-low pressure integrated turbine rotor of the present invention is 0.2%
It has excellent toughness with a proof stress of 686 MPa or more and a Charpy impact absorption energy of 98 J or more.

As described above, the high / low pressure integrated turbine rotor of the present invention has excellent creep characteristics in the high pressure portion and excellent toughness in the low pressure portion.
The inventor has verified the above-mentioned characteristics in Examples described later. This test method and test results will be described in detail in (Example).

According to the method of manufacturing a high-low pressure integrated turbine rotor of the present invention, a turbine rotor material made of an alloy steel having a specific composition is subjected to different heat treatments in a portion corresponding to a high pressure portion and a portion corresponding to a low pressure portion. How to That is, the portion corresponding to the high-pressure portion of the turbine rotor material is heated to 980 ° C. or more and 1100 ° C. or less, and the portion corresponding to the low-pressure portion of the turbine rotor material is heated to 850 ° C. or more.
After heating to less than 0 ° C., the portion corresponding to the high pressure portion of the turbine rotor material is cooled to a predetermined temperature of 900 ° C. to 700 ° C. by using one or more of fountain cooling or blast cooling, and then After air cooling for 5 minutes to 5 hours, 300
One of fountain cooling, blast cooling or oil cooling down to ℃
Cooling is performed using more than one method, and the portion corresponding to the low-pressure portion of the turbine rotor material is cooled by a method capable of obtaining a speed higher than that of oil quenching.

In other words, according to the method for manufacturing a turbine rotor of the present invention, a portion corresponding to a high pressure portion of a turbine rotor material is quenched from a high temperature and tempered at a high temperature, while a portion corresponding to a low pressure portion is compared with a high pressure portion. It employs a method of quenching at a relatively low temperature and tempering at a relatively low temperature.

By applying different heat treatments to the high pressure portion and the low pressure portion, the portion corresponding to the high pressure portion has a creep rupture time in a smooth creep rupture test at 600 ° C. and a stress of 176 MPa. Is 2,500 hours or more, and has excellent high-temperature characteristics in which the creep rupture time in the notch creep rupture test is 5,000 hours or more under the same conditions.
It can have excellent toughness with a 2% proof stress of 686 MPa or more and a Charpy impact absorption energy of 98 J or more.

Here, the notch creep rupture strength among the high temperature characteristics will be described. Normally, when stress is applied to a steel material, even at a relatively low stress, at a high temperature, plastic deformation occurs very gradually, and elongation is exhibited, and then elongation progresses rapidly, causing constriction and breakage. This phenomenon is a creep phenomenon (creep rupture phenomenon). This creep phenomenon is considered to be due to the viscous flow at the grain boundaries and the movement of dislocations in the crystal. In the high-temperature creep rupture test, a material is subjected to a constant static load for a long time at a high temperature to measure the time until rupture. As the test piece, a round bar having a constant cross-sectional area is used, and the measuring method is specified in JIS Z-2272. What is specified in JIS is a smooth creep rupture test, and a test piece which is finished by smooth cutting between the reference points of the measurement portion of the test piece is used.

On the other hand, in the notch creep rupture test,
Use a test piece with a notch between scores. The stress is determined in the same manner as in the case of the smooth creep rupture test with respect to the cross-sectional area (cross-sectional area of the notch bottom) of the measurement portion to be pulled.
The diameter of the parallel portion of the test piece (corresponding to the score of the test piece used in the above-mentioned smoothing test) was 1.2 times the diameter of the notch bottom, the notch was opened at an angle of 60 °, and the radius of curvature of the notch bottom was 0.1 mm.
It is 13 mm and is cut perpendicular to the pulling direction. In the above-mentioned smooth creep rupture test, when tensile stress is applied, the gap between the gauge points gradually expands, the gap between the gauge points narrows, and eventually breaks. On the other hand, in the notch creep rupture test in which a notch is provided in the test piece, when the test piece is pulled, the stress that does not deform the notch acts to surround the notch (so-called multiaxial stress), and It breaks without exhibiting the elongation phenomenon.

In general, in a material with high ductility, the time required to break due to the restraint of deformation by the notch is longer than that in the smooth creep rupture test. However, depending on the type of steel, the material gradually becomes brittle during the creep rupture test. The phenomenon in which cracks are generated due to the generation of voids and their connection is accelerated, and some creep ruptures appear. In this case, the test piece breaks faster in the notch creep rupture test than in the smooth creep rupture test. Such a phenomenon is called notch weakening and can be used as an index indicating creep embrittlement. That is, a smooth creep rupture test and a notch creep rupture test are performed under the same stress and temperature conditions, and by comparing the creep rupture times of the two, it is possible to clearly indicate the degree of creep embrittlement.

During operation, the turbine rotor is exposed to a high temperature for a long time under a stress, so that the material strength is degraded with time. Conventionally, the quality of a material used for a turbine rotor has been evaluated only by a smooth high-temperature creep rupture test specified in JIS. In particular, a means for evaluating creep embrittlement properties has been found. By this means, with respect to the turbine rotor material of a predetermined component, a comparative evaluation of a metal structure of a high pressure part having a single structure of bainite as in the conventional material and a structure having a composite structure in which a bainite phase is mixed with a proeutectoid ferrite phase is performed. It was clarified that creep embrittlement was suppressed in those containing a pro-eutectoid ferrite phase of more than 10% and not more than 40% by volume%.

However, when cooling by the conventional method is employed during the heat treatment of the high-pressure section, a predetermined amount of a pro-eutectoid ferrite phase is precipitated at the center (diameter-center) of the turbine rotor material where the cooling rate is slow. However, the proeutectoid ferrite phase hardly precipitates at the surface layer because the cooling rate is high. Therefore, the present inventor has conducted intensive studies to solve this problem, and as a result, when cooling the high-pressure part,
Cool down to a predetermined temperature of 900 ° C. to 700 ° C. using fountain cooling and / or blast cooling as a cooling means, then air-cool for 5 minutes to 5 hours, and then fountain cooling or blast cooling or oil to 300 ° C. By cooling using one or more types of cooling means, an appropriate amount of pro-eutectoid ferrite phase is precipitated at each position (excluding the surface layer that is finally cut) in the high-pressure part of a large turbine rotor material. It was made possible.

In a part of the component system of the present invention, since the diameter of the turbine rotor is large, the cooling speed is particularly low as compared with the high pressure part. In some cases, 30% or less of a ferrite phase was precipitated. However, if both the 0.2% proof stress and the impact characteristics exceed the target values as a turbine rotor and the ferrite phase is 30% or less by volume%,
It has also been found that there is substantially no problem as a material constituting the low-pressure portion of the turbine rotor.

Based on the above research, the present invention has adopted the following constitution.

That is, the first aspect of the present invention is a high-low pressure integrated turbine rotor in which a high-pressure portion and a low-pressure portion are integrally formed, wherein carbon is 0.20 to 0.35% by weight.
%, Silicon: 0.15% or less, manganese: 0.05-1.
0%, nickel: 0.3-2.5%, chromium: 1.0-
3.0%, molybdenum: 0.5 to 1.5%, tungsten: 0.1 to 3.0%, vanadium: 0.1 to 0.3%
Phosphorus: 0.012% or less, Sulfur: 0.005% or less, Copper: 0.15% or less, Aluminum: 0.01% or less, Arsenic: 0.01% or less, Tin: 0.01% or less , Antimony: 0.003% or less, the balance being composed of iron containing unavoidable impurities, wherein the metal structure of the high-pressure portion is more than 10% by volume and more than 40% or less pro-eutectoid ferrite phase And a balance of the bainite phase.

The alloy used in the high / low pressure turbine rotor of the present invention is intended to improve the high temperature strength of the high pressure portion by adding W to the conventional low alloy heat resistant steel for the high / low pressure integrated rotor.
Here, when importance is placed on the improvement of the creep strength in the high-temperature part, the content of tungsten is increased. When importance is placed on the improvement of the toughness in the low-temperature part, the content of tungsten is preferably reduced. And the metal structure of the high pressure part is
, And is controlled to be composed of a pro-eutectoid ferrite phase of more than 10% and 40% or less and a remaining bainite phase, thereby avoiding creep embrittlement of the high-pressure part.

Next, a second aspect of the present invention is a high-low pressure integrated turbine rotor in which a high-pressure portion and a low-pressure portion are integrally formed, wherein carbon: 0.20 to 0.35% by weight. , Silicon: 0.15% or less, manganese: 0.05 to 1.0%,
Nickel: 0.05-2.5%, chromium: 1.0-3.
0%, molybdenum: 0.5 to 1.5%, tungsten:
0.1-3.0%, vanadium: 0.1-0.3%, cobalt: 0.1-3.0%, phosphorus: 0.012% or less, sulfur: 0.005% or less, copper : 0.15% or less, aluminum: 0.01% or less, arsenic: 0.01% or less,
Tin: 0.01% or less, antimony: 0.003% or less, with the balance being iron containing unavoidable impurities, and the metal structure of the high-pressure part is more than 10% by volume and exceeds 40%. % Of the pro-eutectoid ferrite phase and the rest of the bainite phase.

The alloy used in the turbine rotor according to the second aspect is obtained by increasing the high-temperature strength and toughness by adding cobalt to the alloy according to the first aspect. When emphasizing the creep strength of the high-pressure part, it is good to reduce the amount of nickel or manganese, but by adding cobalt accordingly, the balance of heat treatment characteristics and material characteristics can be maintained. This alloy is also controlled so that the metal structure in the high-pressure part is composed of a pro-eutectoid ferrite phase of more than 10% and 40% or less by volume and the remaining bainite phase, thereby avoiding creep embrittlement in the high-pressure part. .

A third aspect of the present invention is a high-low pressure integrated turbine rotor in which a high-pressure portion and a low-pressure portion are integrally formed, wherein carbon: 0.20 to 0.35% by weight. , Silicon: 0.15% or less, manganese: 0.05 to 1.0%,
Nickel: 0.3-2.5%, chromium: 1.0-3.0
%, Molybdenum: 0.5 to 1.5%, tungsten:
0.1-3.0%, vanadium: 0.1-0.3%, niobium: 0.01-0.15%, tantalum:
0.01-0.15%, nitrogen: 0.001-0.05
%, Boron: at least one selected from 0.001 to 0.015%, phosphorus: 0.012% or less, sulfur: 0.005% or less, copper: 0.15% or less, aluminum : 0.01% or less, arsenic: 0.01% or less, tin:
0.01% or less, antimony: 0.003% or less, with the balance being composed of iron containing unavoidable impurities, and the metal structure of the high-pressure part is more than 10% by volume and exceeds 4%.
A high / low pressure integrated turbine rotor comprising a 0% or less pro-eutectoid ferrite phase and the balance of a bainite phase.

The alloy used in the turbine rotor according to the third aspect aims at improving the creep strength in a high-temperature portion. Niobium, tantalum and nitrogen are further added to the alloy used in the turbine rotor according to the first aspect. , Or at least one of boron, to further improve the smooth creep characteristics, and to increase the metal structure of the high-pressure part by more than 10% by volume to 40% or less of the pro-eutectoid ferrite phase and the balance. To control creep embrittlement.

Next, a fourth aspect of the present invention is a high-low pressure integrated turbine rotor in which a high-pressure portion and a low-pressure portion are integrally formed, wherein carbon: 0.20 to 0.35% by weight. , Silicon: 0.15% or less, manganese: 0.05 to 1.0%,
Nickel: 0.05-2.5%, chromium: 1.0-3.
0%, molybdenum: 0.5 to 1.5%, tungsten:
0.1 to 3.0%, vanadium: 0.1 to 0.3%, cobalt: 0.1 to 3.0%, and niobium: 0.1 to 3.0%.
01-0.15%, tantalum: 0.01-0.15%,
Nitrogen: 0.001 to 0.05%, boron: 0.001 to
Containing at least one selected from 0.015%, phosphorus: 0.012% or less, sulfur: 0.005% or less,
Copper: 0.15% or less, Aluminum: 0.01% or less,
Arsenic: 0.01% or less, Tin: 0.01% or less, Antimony: 0.003% or less, the balance being iron containing unavoidable impurities, and the metal structure of the high-pressure part is: A high / low pressure integrated turbine rotor comprising a pro-eutectoid ferrite phase of more than 10% and 40% or less by volume% and a balance of a bainite phase.

The alloy used for the turbine rotor according to claim 4 is obtained by further adding at least one trace element of niobium, tantalum, nitrogen, or boron to the alloy of the turbine rotor according to claim 2. The creep strength of the high-temperature portion is improved. In particular, the smooth creep characteristics are further improved, and the metal structure of the high-pressure portion is more than 10% by volume% and 40% or less of the proeutectoid ferrite phase and the remaining bainite. It is controlled to be composed of phases to avoid creep embrittlement.

Next, the invention described in claim 5 of the present invention is as follows.
5. The high-low pressure integrated turbine rotor according to claim 1, wherein carbon / nitride having an average particle size of 0.5 μm or less is finely dispersed in the pro-eutectoid ferrite phase. 6. Is what you do.

Next, the invention described in claim 6 of the present invention is:
The high-low pressure integrated turbine rotor according to any one of claims 1 to 5, wherein a crystal grain size number of a metal structure of the high-pressure portion is 3 or more and 6 or less.

The high-pressure portion of the high-low pressure integrated turbine rotor of the present invention has both high-temperature creep characteristics, especially excellent notch creep characteristics, and excellent toughness. That is, the creep rupture time in the smooth creep rupture test at 600 ° C. and the stress of 176 MPa is 2,500 hours or more (conventional material: 2,000 hours or less), and the creep in the notch creep rupture test under the same conditions. It has excellent high temperature properties with a rupture time of 5,000 hours or more.

Further, the high-temperature creep property is a material determined using the ratio of the creep rupture time to prevent the creep embrittlement in addition to the length of the smooth creep rupture time. That is, the creep rupture time ratio as indicated by the ratio of the creep rupture time in the notch creep rupture test to the creep rupture time in the smooth creep rupture test is at least 2.0 or more, preferably 2.5 or more in the high-pressure part, More preferably, it is 3.0 or more.

The part used for low-pressure steam of the high-low pressure integrated turbine rotor of the present invention has a 0.2% proof stress of 68%.
It has an excellent toughness of 6 MPa or more and a Charpy impact absorption energy of 98 J or more.

As described above, a high-low pressure integrated turbine rotor having both excellent creep strength and toughness is:
This is the first one brought about by the present invention.

Next, the invention according to claim 7 of the present invention is:
A method for manufacturing a high / low pressure integrated turbine rotor in which a high pressure portion and a low pressure portion are integrally formed, wherein a portion corresponding to a high pressure portion of a turbine rotor material having a predetermined composition is heated to 980 ° C or more and 1100 ° C or less. After heating the portion corresponding to the low-pressure portion of the turbine rotor material to 850 ° C. or more and less than 980 ° C., the portion corresponding to the high-pressure portion of the turbine rotor material cools the fountain to a predetermined temperature of 900 ° C. to 700 ° C. Alternatively, cooling by one or more cooling means of blast cooling, and then air cooling for 5 minutes to 5 hours, and then cooling to 300 ° C by one or more cooling means of fountain cooling or blast cooling or oil cooling; A portion corresponding to the low pressure portion of the turbine rotor material is cooled by cooling means capable of obtaining a speed higher than oil quenching, It is a method of manufacture.

Next, the invention according to claim 8 of the present invention provides:
The method for manufacturing a high / low pressure integrated turbine rotor according to claim 7, wherein the turbine rotor material is 0.20 to 0.35% by weight of carbon, 0.15% or less of silicon, and 0.05% of manganese by weight%. 1.0%, nickel: 0.3-2.
5%, chromium: 1.0 to 3.0%, molybdenum: 0.5
1.5 to 1.5%, tungsten: 0.1 to 3.0%, vanadium: 0.1 to 0.3%, phosphorus: 0.012% or less, sulfur: 0.005% or less, copper: 0.1 to 0.3%. 15% or less, aluminum: 0.01% or less, arsenic: 0.01% or less,
A method for manufacturing a high-low pressure integrated turbine rotor, comprising: an alloy steel having a composition of iron containing not more than 0.01% of tin and not more than 0.003% of antimony, and the balance being iron containing unavoidable impurities. It is.

Next, the invention according to claim 9 of the present invention provides
The method for manufacturing a high / low pressure integrated turbine rotor according to claim 7, wherein the turbine rotor material is 0.20 to 0.35% by weight of carbon, 0.15% or less of silicon, and 0.05% of manganese by weight%. ~ 1.0%, nickel: 0.05 ~
2.5%, chromium: 1.0 to 3.0%, molybdenum:
0.5-1.5%, tungsten: 0.1-3.0%,
Vanadium: 0.1-0.3%, Cobalt: 0.1-
3.0%, phosphorus: 0.012% or less, sulfur: 0.0
05% or less, copper: 0.15% or less, aluminum: 0.
01% or less, arsenic: 0.01% or less, tin: 0.01% or less, antimony: 0.003% or less, the balance being an alloy steel having a composition of iron containing unavoidable impurities. A method for manufacturing a high-low pressure integrated turbine rotor characterized by the following.

According to a tenth aspect of the present invention, there is provided a method for manufacturing a high / low pressure integrated turbine rotor according to the seventh aspect, wherein the turbine rotor material is 0.20 to 0.20% by weight of carbon. 0.35%, silicon: 0.15% or less,
Manganese: 0.05-1.0%, Nickel: 0.3-
2.5%, chromium: 1.0 to 3.0%, molybdenum:
0.5-1.5%, tungsten: 0.1-3.0%,
Vanadium: containing 0.1-0.3%, and further niobium:
0.01 to 0.15%, tantalum: 0.01 to 0.15
%, Nitrogen: 0.001 to 0.05%, boron: 0.001
-0.015% or less, phosphorus: 0.012% or less, sulfur: 0.005% or less, copper: 0.15% or less, aluminum: 0.01% or less, An alloy steel having a composition of arsenic: 0.01% or less, tin: 0.01% or less, antimony: 0.003% or less, and the balance being iron containing unavoidable impurities. Item 8. A method for manufacturing a high-low pressure integrated turbine rotor according to Item 7.

Next, according to an eleventh aspect of the present invention, in the method for manufacturing a high / low pressure integrated turbine rotor according to the seventh aspect, the turbine rotor material is prepared by mixing carbon: 0.35%, silicon: 0.15% or less,
Manganese: 0.05-1.0%, Nickel: 0.05-
2.5%, chromium: 1.0 to 3.0%, molybdenum:
0.5-1.5%, tungsten: 0.1-3.0%,
Vanadium: 0.1-0.3%, Cobalt: 0.1-
3.0%, and niobium: 0.01-0.15
%, Tantalum: 0.01 to 0.15%, nitrogen: 0.00
1 to 0.05%, boron: at least one selected from 0.001 to 0.015%, phosphorus: 0.01
2% or less, sulfur: 0.005% or less, copper: 0.15% or less, aluminum: 0.01% or less, arsenic: 0.01%
Below, tin: 0.01% or less, antimony: 0.003%
The method of manufacturing a high-low pressure integrated turbine rotor according to claim 7, wherein the remainder is an alloy steel having a composition consisting of iron containing unavoidable impurities.

The portion corresponding to the high-pressure portion of the turbine rotor is heated to a high temperature in order to sufficiently dissolve the alloying elements. On the other hand, the reason why the low-pressure portion of the turbine rotor is heated to a temperature lower than that of the high-pressure portion is to make the crystal grains fine and increase the toughness.

According to the method of manufacturing the high / low pressure integrated turbine rotor, by cooling the raw material of the turbine rotor as described above, a portion corresponding to the high pressure portion of the raw material of the turbine rotor is reduced by 10% by volume to the bainite phase. Metal structure containing a pro-eutectoid ferrite phase controlled by a metal structure containing a pro-eutectoid ferrite phase of not more than 40% and a portion corresponding to a low-pressure portion of a turbine rotor material being 30% or less by volume% of a bainite single phase or a bainite phase Is controlled. After cooling, the material was reheated and held (tempering) at a predetermined temperature set for each of the portion corresponding to the high-pressure portion and the portion corresponding to the low-pressure portion, and adjusted to obtain predetermined material characteristics. Thereafter, it is provided as a material for a high-pressure integrated turbine rotor.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. First, the reasons for limiting the range of each component in the alloy used in the present invention will be described.

Carbon (C): Carbon has the effect of securing hardenability during heat treatment and increasing the material strength. Further, it forms carbides and / or carbonitrides and contributes to improvement in creep rupture strength at high temperatures. In the present alloy system, if the content is less than 0.20%, the material strength is not sufficient, so the lower limit is set to 0.20%. On the other hand, if the content of carbon is too large, toughness is reduced, and carbides and / or carbonitrides are agglomerated and coarsened during use at a high temperature, causing a reduction in creep rupture strength and creep embrittlement. Therefore, the upper limit of the carbon content is set to 0.35%. A particularly preferred range for combining material strength and toughness is 0.22 to 0.22.
0.30%.

Silicon (Si): While silicon has an effect as a deoxidizing material, it makes the base of the material brittle. Silicon comes from steelmaking raw materials, and in order to reduce silicon extremely, it is necessary to carefully select raw materials, resulting in high costs.
Content up to 0.15% is acceptable. The preferred range is 0.
10% or less.

Manganese (Mn): Manganese acts as a deoxidizing material and has an effect of preventing hot cracking during forging. It also has the effect of increasing the hardenability during heat treatment.
However, as the manganese content increases, the creep rupture strength deteriorates, so the maximum amount was set to 1.0%. However, in order to reduce the manganese content to less than 0.05%, strict selection of raw materials and an excessive refining process are required, which leads to an increase in cost. Therefore, the range of the manganese content is 0.05 to 1.0%, preferably 0.1 to 1.0%.
5 to 0.9%.

Nickel (Ni): Nickel enhances hardenability during heat treatment, improves tensile strength and proof stress,
In particular, it has the effect of increasing toughness. If the content is less than 0.3%, no effect is recognized. However, on the other hand, the long-term creep rupture strength decreases with the addition of nickel. The alloy used for the turbine rotor of the present invention does not expect much improvement in hardenability and toughness due to the addition of nickel. Conversely, in order to eliminate the adverse effect of nickel on long-term creep rupture strength, the upper limit of the nickel content is set to 2%. 0.5% or less. On the other hand, by replacing nickel with cobalt described below, it is possible to increase tensile strength and proof toughness without reducing creep strength. Therefore, regarding the component system containing cobalt, the lower limit of nickel is set to 0.1.
It is allowed to lower to 05%. The lower limit is set to 0.05% because lowering the lower limit requires careful selection of raw materials and the like, which increases the cost.

Chromium (Cr): Chromium enhances hardenability during heat treatment, forms carbides and / or carbonitrides, contributes to improvement in creep rupture strength, and dissolves in the matrix to improve oxidation resistance. I do. It also has the effect of strengthening the matrix itself and improving the creep rupture strength. If the chromium content is less than 1.0%, the effect is not sufficient, and if the chromium content exceeds 3.0%, the creep rupture strength is rather reduced. Therefore, the range of the chromium content is 1.0 to 3.0%, preferably 2.0 to 2.5%.
%.

Molybdenum (Mo): Molybdenum has the effect of improving hardenability during heat treatment and improving the creep rupture strength by forming a solid solution in a matrix or in a carbide and / or carbonitride. If the content is less than 0.5%, the effect is not sufficiently recognized, and even if added over 1.5%, the toughness is rather lowered and the cost is increased. Therefore, the content of molybdenum is set to 0.5 to 1.5%, preferably 0.9 to 1.3%.

Vanadium (V): Vanadium has the effect of improving the hardenability during heat treatment and improving the creep rupture strength by becoming carbide and / or carbonitride.
If the content is less than 0.1%, a sufficient effect cannot be obtained. When the content exceeds 0.3%, the creep rupture strength is rather lowered. Therefore, the content of vanadium is set to 0.1 to 0.3%, preferably 0.21 to 0.28%.

Tungsten (W): Tungsten has the effect of improving the creep rupture strength by forming a solid solution in a matrix or carbide. If the content is less than 0.1%, a sufficient effect cannot be obtained. If the content exceeds 3.0%, segregation may occur, and a ferrite phase is likely to appear and the strength is reduced. Therefore, when tungsten is used, its content is suitably from 0.1 to 3.0%.

Cobalt (Co): Like nickel, cobalt enhances the hardenability during heat treatment, improves the tensile strength and proof stress, and particularly has the effect of increasing the toughness. Also, unlike nickel, addition of 3.0% or less does not adversely affect the creep strength characteristics. Therefore, it is effective in balancing mechanical strength, creep strength and toughness. If the addition amount of cobalt is less than 0.1%, no effect is exhibited, and if it exceeds 3.0%, the precipitation of carbides is promoted and the creep characteristics are deteriorated. Therefore, the allowable range of cobalt content is 0.1% to 3.0%. More preferably, it is 0.5 to 2.2%.

Niobium (Nb): Niobium enhances hardenability and forms carbide and / or carbonitride to improve creep rupture strength. Further, it has the effect of suppressing the growth of crystal grains during high-temperature heating and contributing to homogenization of the structure. If the addition amount is less than 0.01%, the effect is not recognized, and if it exceeds 0.15%, remarkable segregation occurs at the time of solidification of the steel ingot or remarkable decrease in toughness. Therefore, the allowable amount of niobium is set to 0.01% to 0.15%. Preferably, it is in the range of 0.05 to 0.10%.

Tantalum (Ta): Tantalum, like niobium, has the effect of improving hardenability and forming carbides and / or carbonitrides to improve creep rupture strength. If the addition amount is less than 0.01%, the above effect is not recognized, and if it exceeds 0.15%, remarkable segregation occurs at the time of solidification of the steel ingot or remarkable decrease in toughness. Therefore, the allowable content of tantalum is 0.01% to 0.15%.
And Preferably, it is in the range of 0.05 to 0.1%.

Nitrogen (N): Nitrogen combines with carbon with an alloying element to form a carbonitride and has an effect of contributing to an improvement in creep rupture strength. 0.001
If it is less than 0.05%, a carbonitride cannot be formed, and the above effect is not recognized. If it exceeds 0.05%, a sufficient creep strength can be obtained since the carbonitride is aggregated and coarsened for a long time. Absent. Therefore, the allowable amount of nitrogen is 0.00
1% to 0.05%. Preferably 0.005-0.
It is in the range of 01%.

Boron (B): Boron has the effect of improving the hardenability and increasing the grain boundary strength to contribute to the improvement of the creep rupture strength. If the addition amount is less than 0.001%, the above effect is not recognized, and if it exceeds 0.015%, the hardenability is rather deteriorated. Therefore, the allowable amount of boron is set to 0.001% to 0.015%. Preferably it is in the range of 0.003 to 0.010%.

Next, harmful impurities such as phosphorus, sulfur, copper,
Aluminum, arsenic, tin, and antimony will be described. It goes without saying that the lower these impurities are preferable for the mechanical properties of the steel material. However, generally, only phosphorus and sulfur that are necessarily brought in from steelmaking raw materials have standardized allowable contents as impurities in steel materials. Phosphorus and sulfur make the material of the steel brittle, so the allowable amount is generally determined for each steel type, but is set to a considerably high level due to the difficulty of refining.

The present inventors have developed a CrMo for turbine rotor.
As a result of intensive studies aimed at improving the high-temperature properties of V steel, especially the notch creep rupture strength, it was found that trace impurities had a significant effect on the notch creep rupture strength. Further, it has been found that not only phosphorus and sulfur but also copper, aluminum, arsenic, tin, antimony, and the like as the trace impurities have an adverse effect. Until now, it has been vaguely recognized that the lower the amount of impurities, the better, and the specific allowable amount has not been clarified. However, the present inventors have examined these impurities in detail, Stress 178MPa
Rupture time in notch creep rupture test under the conditions of
For the purpose of 000 hours or more, the allowable amounts of these contents are specifically shown.

Phosphorus (P), Sulfur (S): Phosphorus and sulfur are both impurities introduced from steelmaking raw materials, and are harmful impurities that form phosphides and sulfides in the steel and significantly lower the toughness of the steel. It is. Our studies have shown that high temperature properties are also adversely affected. Phosphorus is easily segregated, and secondary segregation of carbon is also caused, thus embrittle the material. In particular, it has been found that when a high stress is applied for a long time at a high temperature, the embrittlement is greatly affected.

The extreme reduction of the phosphorus and sulfur contents increases the burden on the steelmaking process. Therefore, the breaking time of the notch creep rupture test at a temperature of 600 ° C. and a stress of 178 MPa should be about 5,000 hours or more. As a result of finding the upper limit, the upper limit of the content of phosphorus was set to 0.012%, and the upper limit of sulfur was set to 0.005%. More preferably, the content of phosphorus is 0.010% or less, and the content of sulfur is 0.002% or less.

Copper (Cu): Copper diffuses along the crystal grain boundaries in a steel material to embrittle the material. In particular, it degrades high temperature characteristics. From the results of the notch creep rupture test, the upper limit of the copper content was set to 0.15%. More preferably, it is 0.04% or less.

Aluminum (Al): Aluminum is mainly derived from the deoxidizing material in the steel making process, and forms oxide-based inclusions in the steel material to embrittle the material. From the results of the notch creep rupture test, the upper limit of the aluminum content was set to 0.01%. More preferably, it is 0.005% or less.

Arsenic (As), Tin (Sn), Antimony (Sb): Arsenic, tin, and antimony are often mixed from steelmaking raw materials, and both precipitate along the crystal grain boundaries to lower the toughness of the material. Things. In particular, when these elements are heated to a high temperature, aggregation at crystal grain boundaries becomes remarkable, and the alloy rapidly becomes brittle. From the results of the notch creep rupture test, the upper limits of the contents of these impurities were 0.01% for arsenic and 0.1% for tin.
01% and 0.003% of antimony. More preferably, arsenic is 0.007% or less, tin is 0.007% or less,
Antimony is 0.0015% or less.

(Method of Manufacturing High-Low Pressure Integrated Turbine Rotor) Next, a method of manufacturing the high-low pressure integrated turbine rotor of the present invention will be described.

In the method of manufacturing a high / low pressure integrated turbine rotor according to the present invention, as described above, first, a base material is melted to have a predetermined alloy composition. Here, the method for reducing the trace impurities is not particularly limited, and any known refining method can be used, including careful selection of raw materials.

Next, a molten alloy melted to a predetermined composition is cast into a steel ingot by a known method, and is subjected to predetermined forging and forming to obtain a turbine rotor material.

Next, the turbine rotor material is heat-treated in two sections: a portion corresponding to the high-pressure portion and a portion corresponding to the low-pressure portion of the turbine rotor. In order to perform the heat treatment separately in the two sections, a heat-resistant partition is provided between the spaces in which the respective parts of the heat treatment furnace are accommodated, and the inside of the heat treatment furnace is divided into two chambers and the respective chambers are independently temperature-controlled. This can be achieved by controlling.

The turbine rotor material is accommodated in the heat treatment furnace configured as described above, and the portion corresponding to the high-pressure section is 9 parts.
Heat to a temperature of 80 ° C or higher and 1100 ° C or lower. Further, the portion corresponding to the low pressure portion is heated to a temperature of 850 ° C. or more and less than 980 ° C. If the high-pressure part is not heated to 980 ° C. or higher, the high-temperature creep strength will be insufficient, and if it exceeds 1100 ° C., equipment restrictions will be large, cost will be increased and toughness will be reduced. The heating temperature range of the portion to be heated was 980 ° C. or higher and 1100 ° C. or lower. Unless heated to 850 ° C. or higher, the solid solution of the carbide does not progress unless heated to 850 ° C. or more, whereby the strength and toughness become insufficient. If heated to 980 ° C. or higher, the crystal grains become coarse and the toughness is reduced. The heating temperature range of the part is 850 ° C or more and 980
° C or less.

Next, the portion corresponding to the high-pressure portion of the turbine rotor material heated to the above temperature range is from 900 ° C. to 7 ° C.
Cool down to a predetermined temperature of 00 ° C. using one or more cooling means of fountain cooling or blast cooling, then air-cool for 5 minutes to 5 hours, and then fountain cooling or blast cooling to 300 ° C. Oil cooling is performed using one or more types of cooling means, and a portion corresponding to the low-pressure portion of the turbine rotor material is cooled by a cooling means capable of obtaining a speed higher than oil quenching. The cooling means capable of cooling at a speed higher than the oil quenching includes oil cooling, water cooling, fountain cooling, and the like.

The temperature control in the heat treatment method of the present invention is performed at a position corresponding to the outermost layer in the product shape of the final product. Since the turbine rotor material at the time of heat treatment is provided with a surplus of approximately 30 to 200 mm, the temperature is controlled at the position of the outermost layer of the product excluding the surplus. In the temperature management, a method of directly measuring the temperature at the management position, a method of previously managing the correspondence between the different positions of the turbine rotor material and the management position, and a method of managing the temperature at another position, and acquiring the temperature in advance. Based on the data and the heat calculation simulation, a method of managing the amount, speed and time of release of the cooling medium can be freely selected.

Controlling the cooling pattern in this way is as follows.
This is for precipitating a pro-eutectoid ferrite phase in an appropriate range. Depending on the amount of various alloy components and the size of the turbine rotor material within the scope of the present invention, the temperature at which air cooling is started, the time of air cooling, and the cooling rates before and after that are appropriately combined within the range specified in the present invention. Thereby, a desired amount of pro-eutectoid ferrite phase can be obtained.

The quenched rotor material is subjected to tempering to adjust the crystal structure and adjust its mechanical properties. In this tempering treatment, the value of 0.2% proof stress is 58% in the portion corresponding to the high pressure portion.
The aim is to obtain a characteristic of 8 to 686 MPa, and the 0.2% proof stress value of the portion corresponding to the low pressure portion is 686 to 686 MPa.
The goal is to obtain a property of 784 MPa. Specifically, for the portion corresponding to the high pressure portion,
Tempering is performed at a temperature of 550C, and a portion corresponding to the low pressure part is preferably tempered at a temperature of 550C to 700C.

The tempering process is not limited to one time,
It may be repeated more than once. By performing such a series of heat treatments, it is possible to obtain a high-low pressure integrated turbine rotor in which portions corresponding to the high-pressure portion and the low-pressure portion have predetermined mechanical characteristics.

Next, the microstructure of the high / low pressure integrated turbine rotor of the present invention will be described with reference to FIG. FIG.
FIG. 3 is a diagram showing a microscope image of a high-pressure portion of the turbine rotor according to the present invention.

The microstructure of the high-low pressure integrated turbine rotor of the present invention subjected to the heat treatment as described above is such that the high-pressure portion has a bainite phase containing more than 10% by volume and not more than 40% of a pro-eutectoid ferrite phase. The low-pressure part is controlled to a bainite single phase or a bainite phase containing a pro-eutectoid ferrite phase of 30% or less by volume. Moreover, since the alloy of the present invention has good hardenability, the pro-eutectoid ferrite phase precipitates at a lower temperature than ordinary steel, and is more finely dispersed than the ordinary eutectoid ferrite phase.

Further, since a large amount of carbon / nitride forming elements such as tungsten and molybdenum are contained, tempering of the proeutectoid ferrite phase results in an average grain size of 0.5 μm or less as shown in FIG. Fine carbon / nitride precipitates finely in the pro-eutectoid ferrite phase. Generally, the pro-eutectoid ferrite phase is soft, and when precipitated in a large amount, the 0.2% proof stress and the creep rupture strength decrease. However, since the carbon / nitride is finely dispersed in the pro-eutectoid ferrite phase, the turbine rotor according to the present invention has strength characteristics not inferior to those of the bainite phase. This is a major feature of the turbine rotor according to the present invention. In addition,
The proportion occupied by the ferrite phase in the microstructure can be determined by a commonly used image analyzer.

On the other hand, due to the precipitation of the pro-eutectoid ferrite phase, the crystal structure of the metal structure of the turbine rotor is refined as compared with the original austenite crystal grain size, which is a major factor for suppressing creep embrittlement. It has become. In the present invention, the crystal grains are finer than the original austenite crystal grains, and the pro-eutectoid ferrite grains and the bainite grains (the sizes correspond to the size of the austenite grains at the time when the pro-eutectoid ferrite is completely precipitated) ) Is preferably 3 to 6 in terms of crystal grain size number on average. If the grain size number is less than 3, there is a possibility that creep embrittlement may occur due to excessively coarse grains. On the other hand, when the crystal grain size number exceeds 6, the fine particles may be too fine and the high-temperature strength may be reduced. Therefore, a suitable crystal grain size is in the range of 3 to 6, more preferably 3.2 to 4.5, in terms of crystal grain size number.

Here, the crystal grains are defined as a boundary between a bainite phase and a pro-eutectoid ferrite phase, a boundary between pro-eutectoid ferrite phases, and a boundary between old austenite grains transformed into a bainite phase as crystal grain boundaries. Is a portion surrounded by the crystal grain boundaries.

Here, a method of measuring the crystal grain size of the crystal grains will be described. Please refer to JI
SG 0551 (1998) defines “Austenitic grain size test method for steel”, and JIS G 0552 (1998) defines “Ferrite grain size test method for steel”. The low-alloy heat-resistant steel of the present invention is quenched from a high temperature in an austenite stable region to precipitate a pro-eutectoid ferrite phase and exhibit a metal structure in which a ferrite phase and a bainite phase are mixed. Therefore, in the present invention, it is reasonable to define the crystal grain size for the composite structure in which the ferrite phase and the bainite phase are mixed. As defined above, the boundary between the bainite phase and the pro-eutectoid ferrite phase, the boundary between the pro-eutectoid ferrite phases,
The boundary between the prior austenite grains transformed into the bainite phase is defined as a crystal grain boundary, and the size of the portion surrounded by these crystal grain boundaries is defined as the crystal grain size. JIS G 05
52 (1998) “Steel ferrite grain size test method”, in accordance with the “mixed grain” measurement method. That is, the crystal grains appearing on the corroded surface of the test piece are photographed in a microscopic photograph, and are determined by using a judgment method based on the crossing line (particle size). The smaller the crystal grain size number, the larger the crystal grain size.

[0090]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the following examples do not limit the contents of the present invention.

Example 1 In order to examine the effects of heat treatment conditions, the amount of proeutectoid ferrite phase, and the crystal grain size on the material characteristics of the turbine rotor high-pressure section, an alloy material having an alloy number 1 shown in Table 1 was used. Various heat treatments are performed.
2% proof stress, Charpy impact absorption energy and 600 ° C
The creep rupture time at -176 MPa was measured for the smooth sample and the notched sample, and the creep rupture time ratio was calculated based on the measured values.

Table 2 shows the quenching temperature and cooling method for each sample. Table 3 shows the results of the above measurements.
In each of the tests of this example, a turbine rotor material having a body diameter of 1200 mm (corresponding to a high-pressure portion) is assumed, and the heat treatment is performed in the center portion (diameter direction) of the turbine rotor high-pressure portion when each cooling is performed. (The center part of) was simulated.

As shown in Tables 2 and 3, a comparison of Sample No. 1A (comparative material), Sample No. 1B, and Sample No. 1D in which heat treatment conditions other than the quenching temperature were prepared, showed that the quenching temperature was 95%.
The sample at 0 ° C. (Sample No. 1A) did not satisfy the target values in both the smooth creep strength and the notch creep strength, whereas the sample with the quenching temperature raised to 980 ° C. or higher (Sample No. 1B,
Sample No. 1D) shows that both the smooth creep strength and the notch creep strength exceeded the target values, and that the 0.2% proof stress, the impact absorption energy, and the creep rupture time ratio also exceeded the target values.

Note that these target values are set at a stress of 1 at 600 ° C.
The creep rupture time in the smooth creep rupture test under the conditions of 76 MPa is 2,500 hours or more, and the creep rupture time in the notch creep rupture test under the same conditions is 5,000 hours or more. In addition, the 0.2% proof stress is 686 MPa or more, the Charpy impact absorption energy is 98 J or more, and the creep rupture time ratio is at least 2.0, preferably 2.5 or more, more preferably 3. 0 or more.

Next, when the quenching temperature was kept constant at 1050 ° C., the samples of Sample No. 1C (Comparative Material), Sample No. 1D, Sample No. 1E, Sample No. 1F, and Sample No. 1G (Comparative Material) were compared. The effects of the ferrite phase content and the crystal grain size on the material properties become clear. That is, the sample of sample No. 1C having a metal structure containing no pro-eutectoid ferrite phase and having a grain size number smaller than 3.0 (indicating that the sample is coarse) has a smooth creep rupture time longer than that of the other samples. Although excellent, the notch creep rupture time is short, and the creep rupture time ratio is significantly lower than 2.0, which indicates that the material is likely to cause creep embrittlement. Sample No. 1G in which the amount of proeutectoid ferrite phase exceeds 40%
In the sample No., the 0.2% proof stress could not be secured, and the smooth creep rupture time did not reach the target value. On the other hand, Sample No. 1D, Sample No. 1E, and Sample No. 1 in which the amount of pro-eutectoid ferrite phase is in the range of more than 10% by volume and 40% or less.
In the sample of F, all the material properties exceeded the target value as the alloy material used for the high-pressure part of the turbine rotor.

From the above, in order to satisfy the target value of the excellent material characteristics aimed at by the present invention as an alloy material for use in the high pressure portion of the high / low pressure integrated turbine rotor, the quenching temperature is set to 980 ° C. or higher. This indicates that the amount of the proeutectoid ferrite phase needs to be more than 10% and not more than 40% by volume.

(Example 2) The materials (alloy numbers 1 to 3) and comparative materials (alloy numbers 4 to 5) used in Example 2 are shown in Table 1.
Shows the chemical composition of Further, assuming a turbine rotor material having a body diameter of 1200 mm (corresponding to a high-pressure portion) and a turbine rotor material having a body diameter of 2000 mm (corresponding to a low-pressure portion), the center of the turbine rotor (the center in the diametric direction) when each cooling is performed. ) And the surface layer were simulated and heat-treated to produce a sample. Table 4 shows the quenching temperature and cooling method for each sample.

Next, for each of the above samples, the results of measurement of the amount of proeutectoid ferrite phase, crystal grain size number, 0.2% proof stress, Charpy impact absorption energy and creep rupture time at 600 ° C.-176 MPa (smooth sample and notched sample)
Table 5 shows the creep rupture time ratios calculated based on the creep rupture times of the smooth sample and the notched sample.

As shown in Table 5, by subjecting a sample using an alloy having the component range specified by the present invention to an appropriate heat treatment within the range specified by the present invention, the high-pressure part was formed at the center of the turbine rotor material and The volume of both surface layers exceeds 10% by volume 40
% Or less of the proeutectoid ferrite phase, and as a result, the crystal grain size number is controlled to 3.5 or more. Also, 0.2
% Proof stress, Charpy impact absorption energy and 600 ° C-
The creep rupture time at 176 MPa (smooth sample and notched sample) and the creep rupture time ratio all exceeded the target values for the high-pressure part, indicating that the material has unprecedented superior material properties.

On the other hand, in the sample prepared assuming the low-pressure part, there was no pro-eutectoid ferrite phase in the surface layer, and in some samples, 30% or less by volume of the pro-eutectoid ferrite phase precipitated in the center. ing. However, irrespective of the presence or absence of the pro-eutectoid ferrite phase, the 0.2% proof stress and the Charpy impact absorption energy are the target values (0.2% proof stress: 686 MPa or more, necessary for the low-pressure part of the turbine rotor; 98J or more).

On the other hand, in the sample using the alloy of alloy No. 4 in which the amount of carbon and the amount of vanadium are below the component ranges specified by the present invention, a large amount of pro-eutectoid ferrite phase was precipitated in both the high-pressure part and the low-pressure part, % Proof stress, impact absorption energy, and creep strength (smoothness test and notch test) are below target values. In the sample using alloy No. 5 in which the carbon content, silicon content, manganese content, chromium content, and tungsten content exceed the component range, the high-pressure part and the low-pressure part cannot reach the target value of the impact absorption energy, and This indicates that the creep rupture time ratio of the high-pressure part is significantly lower than the target value of 2.0, and that creep embrittlement occurs.

As described above, the high-low pressure integrated turbine rotor having the alloy composition and the metal structure satisfying the requirements of the present invention has excellent high-temperature creep strength in the high-pressure portion, does not cause creep embrittlement, and has a low pressure. It was confirmed that the part had both excellent strength and toughness.

Example 3 Next, Table 6 shows the chemical compositions of the alloys (alloy numbers 6, 7) used in Example 3. In Example 3, an alloy obtained by further adding cobalt based on the alloy No. 2 of Example 2 was used.

The alloy of alloy No. 6 aims at further improving the high temperature creep strength in the high pressure part of the turbine rotor,
In this alloy, the amount of nickel and the amount of manganese of the alloy No. 2 are reduced, and cobalt is added instead. The alloy of Sample No. 7 is based on the alloy of Sample No. 2 described above, with the aim of improving the toughness of the high and low pressure parts of the turbine rotor material while maintaining the high temperature creep strength of the high pressure part to some extent. A slight increase and the addition of cobalt were performed.

A sample using the above alloy was provided with a body diameter of 1200.
mm rotor material (equivalent to high pressure part) and body diameter 2000
Assuming a rotor material of mm (corresponding to a low-pressure part), heat treatment was performed by simulating the center of the rotor (the center in the diameter direction) and the position of the surface layer when each cooling was performed. Table 7 shows the respective quenching temperatures and cooling methods.

Next, the results of measurement of the amount of proeutectoid ferrite phase, crystal grain size number, 0.2% proof stress, Charpy impact absorption energy and creep rupture time at 600 ° C. and 176 MPa (smooth sample and notched sample), and Table 8 shows the creep rupture time ratio calculated based on the creep rupture time of the smooth sample and the notched sample.

As shown in Table 8, by subjecting a sample using an alloy having the component range specified by the present invention to an appropriate heat treatment within the range specified by the present invention, the high-pressure part was formed in the central part and the surface layer part of the material. In both cases, a pro-eutectoid ferrite phase of more than 10% and not more than 40% by volume% was obtained, and as a result, the crystal grain size number was also 3.
It turns out that it is controlled to 5 or more.

In the present invention material shown in Table 8, 0.2%
Strength, Charpy impact absorption energy and 600 ° C-1
The creep rupture time at 76 MPa (smooth sample and notched sample) and the creep rupture time ratio all exceeded the target values for the high-pressure portion, indicating that the material has unprecedented superior material properties. In particular, the sample symbols 2A, 2
Compared with B, the creep rupture times of Samples 6A and 6B using Alloy No. 6 were longer in both the smoothness test and the notch test, and the change of the components, mainly the addition of cobalt, was effective in improving the creep characteristics. Suggests that

On the other hand, the sample manufactured assuming the low pressure part
There is no pro-eutectoid ferrite phase and 0.2% proof stress, and the Charpy impact absorption energy is the target value (0.2%
Proof stress: 686 MPa or more, Charpy impact absorption energy: 98 J or more). In particular, when compared with the sample symbols 2A, 2B, 2C, and 2D shown in Table 5 above, the impact absorption energies of the samples 7A, 7B, 7C, and 7D using the alloy No. 7 show large values in any portions. It suggests that the change of the components, mainly the addition of cobalt, is effective in improving the toughness.

As described above, the high-low pressure integrated turbine rotor having the alloy composition satisfying the requirements of the present invention has excellent high-temperature creep strength in the high-pressure portion, does not cause creep embrittlement, and has excellent strength in the low-pressure portion. And toughness were confirmed. Also, it was confirmed that the addition of cobalt can improve the creep characteristics in the high-pressure part and improve the toughness in the low-pressure part.

Example 4 Next, Table 9 shows the chemical composition of the alloy used in Example 4. In Example 4, an alloy was used in which one or more of niobium, tantalum, nitrogen, and boron were appropriately added based on the alloy number 1 of Example 2 shown in Table 1.

The alloy of alloy No. 8 is obtained by adding niobium and nitrogen to the alloy of alloy No. 1 in order to further improve the high temperature creep strength of the high pressure part. The alloy of sample No. 9 is obtained by adding niobium, tantalum and nitrogen to the alloy of alloy No. 1 in order to further improve the high-temperature creep strength of the high-pressure portion. The alloy of Sample No. 10 is obtained by adding niobium and boron to the alloy of Alloy No. 1 in order to further improve the high-temperature creep strength of the high-pressure portion. The alloy of Sample No. 11 is obtained by adding tantalum and boron to the alloy of Alloy No. 1 in order to further improve the high-temperature creep strength of the high-pressure portion.

A turbine rotor material (corresponding to a high pressure part) having a body diameter of 1200 mm and a body diameter of 200 mm
Assuming a turbine rotor material of 0 mm (corresponding to a low-pressure portion), heat treatment was performed by simulating the center portion (diameter center portion) and surface portion position of the rotor when each cooling was performed.
Table 10 shows the quenching temperature and cooling method for each sample.

Next, the results of measurement of the amount of proeutectoid ferrite phase, crystal grain size number, 0.2% proof stress, Charpy impact absorption energy and creep rupture time at 600 ° C.-176 MPa (smooth sample and notched sample), and Table 11 shows the creep rupture time ratio calculated based on the creep rupture time of the notched sample.

As shown in Table 11, by subjecting a sample having the component range specified by the present invention to an appropriate heat treatment within the range specified by the present invention, the volume of both the central portion and the surface portion of the turbine rotor in the high-pressure portion was increased. %, A proeutectoid ferrite phase of more than 10% and not more than 40% is obtained, and as a result, it can be seen that the crystal grain size number is controlled to 3.5 or more.

Further, the 0.2% proof stress, the Charpy impact absorption energy, the creep rupture time at 600 ° C. and 176 MPa (smooth sample and notched sample), and the creep rupture time ratio all exceeded the target values of the high pressure part. It can be seen that it has excellent material properties.

In particular, the sample symbols 1A and 1B in Table 3 shown above were used.
8A and 8B using alloy No. 8, sample Nos. 9A and 9B using alloy No. 9 and sample No. 10A using alloy No. 10 The creep rupture times of the sample of No. 10B and the samples of Sample Nos. 11A and 11B using the alloy of Alloy No. 11 were long in both the smoothness test and the notch test,
This indicates that the addition of any one or more of tantalum, nitrogen, and boron is effective in improving the creep characteristics.

On the other hand, in the sample prepared assuming the low-pressure part, there was no pro-eutectoid ferrite phase and the 0.2% proof stress, and the Charpy impact absorption energy required the target value (0.
2% proof stress: 686 MPa or more, Charpy impact absorption energy: 98 J or more).

As described above, the high-low pressure integrated turbine rotor satisfying the requirements of the present invention has excellent high-temperature creep strength in the high-pressure portion, does not cause creep embrittlement, and has excellent strength and toughness in the low-pressure portion. It was confirmed that it had both. In addition, it was confirmed that by adding at least one of niobium, tantalum, nitrogen, and boron, in the turbine rotor of the present invention, the effect of improving the creep characteristics in the high-pressure portion can be obtained.

Example 5 Next, Table 12 shows the chemical composition of the alloy used in Example 5. In Example 5, an alloy obtained by adding one or more of niobium, tantalum, nitrogen, and boron as appropriate based on the alloy of Alloy No. 6 of Example 3 shown in Table 6 was used.

The alloy of alloy No. 12 is obtained by adding niobium, tantalum and nitrogen to the alloy of alloy No. 6 in order to further improve the high-temperature creep strength of the high-pressure portion.
The alloy No. 13 is obtained by adding tantalum and boron to the alloy No. 6 in order to further improve the high-temperature creep strength of the high-pressure portion. The alloy of alloy number 14 aims to further improve the high temperature creep strength of the high pressure part,
This is obtained by adding niobium, tantalum and boron to the alloy of alloy number 6 above.

Using each of the above alloys, assuming a rotor material having a body diameter of 1200 mm (corresponding to a high pressure portion) and a rotor material having a body diameter of 2000 mm (corresponding to a low pressure portion), the center of the rotor (diameter direction) when each cooling is performed. At the center) and at the surface layer position. Table 13 shows the quenching temperature and cooling method for each sample.

The amount of the proeutectoid ferrite phase in each of the above samples was
Creep calculated based on crystal grain size number, 0.2% proof stress, Charpy impact absorption energy, creep rupture time at 600 ° C-176 MPa (smooth sample and notched sample), and creep rupture time of smooth sample and notched sample Table 14 shows the breaking time ratio.

As shown in Table 14, a sample having an alloy composition within the range specified by the present invention was subjected to an appropriate heat treatment within the range specified by the present invention, so that in the high-pressure part, the center portion and the surface layer of the turbine rotor material were formed. In each part, a pro-eutectoid ferrite phase of more than 10% and not more than 40% by volume% was obtained, and as a result, it was confirmed that the crystal grain size number was controlled to 3.5 or more.

In the samples prepared assuming the high pressure portion, the 0.2% proof stress, the Charpy impact absorption energy, the creep rupture time at 600 ° C. and 176 MPa (smooth sample and notched sample), and the creep rupture time ratio were all high pressure. The value exceeds the target value of the portion, and it can be seen that the material has excellent material characteristics that have not been achieved in the past.

In particular, sample symbols 6A and 6B in Table 8 shown above were used.
In comparison with the sample of No. 12, the alloys of Sample Nos. 12A and 12B using the alloy of Alloy No. 12, the samples No. 13A and 13B using the alloy of No. 13 and the sample No. 14A using the alloy of No. 14 The creep rupture time of the 14B sample was longer in both the smoothness test and the notch test, indicating that the addition of any one or more of niobium, tantalum, nitrogen, and boron was effective in improving the creep properties. ing.

On the other hand, in a sample manufactured assuming a low pressure part,
There is no proeutectoid ferrite phase, 0.2% proof stress, Charpy impact absorption energy is the target value (0.2
% Yield strength: 686 MPa or more, Charpy impact absorption energy: 98 J or more).

As described above, the high-low pressure integrated turbine rotor of the present invention has excellent high-temperature creep strength in a high-pressure portion,
In addition, no creep embrittlement occurred, and it was confirmed that the low-pressure portion had both excellent strength and toughness. In addition, it was confirmed that by further adding one or more of niobium, tantalum, nitrogen, and boron to the alloy to which cobalt was added, a further effect of improving the creep characteristics could be obtained.

[0129]

As described above in detail, the high-low pressure integrated turbine rotor of the present invention has a carbon content of 0.20% by weight.
0.35%, silicon: 0.15% or less, manganese: 0.1% or less.
05-1.0%, nickel: 0.3-2.5%, chromium: 1.0-3.0%, molybdenum: 0.5-1.5
%, Tungsten: 0.1 to 3.0%, vanadium:
0.1 to 0.3%, phosphorus: 0.012% or less, sulfur: 0.005% or less, copper: 0.15% or less, aluminum: 0.01% or less, arsenic: 0.01% or less ,tin:
0.01% or less, antimony: 0.003% or less, with the balance being composed of iron containing unavoidable impurities, and the metal structure of the high-pressure part is more than 10% by volume and exceeds 4%.
A turbine rotor having excellent strength and high-temperature creep characteristics in a high-pressure part and having excellent strength and toughness in a low-pressure part because it is constituted by a pro-eutectoid ferrite phase of 0% or less and a residual bainite phase. Therefore, it can be used in a high-temperature, large-capacity steam turbine, and a power plant with high energy efficiency can be realized, which is extremely useful.

Next, if the alloy added with 0.1 to 3.0% by weight of cobalt is employed in the high / low pressure integrated turbine rotor of the present invention, the creep characteristics are improved in the high pressure portion and the toughness is reduced in the low pressure portion. The effect of improvement can be obtained.

Next, in the high / low pressure integrated turbine rotor of the present invention, niobium: 0.01 to 0.15%, tantalum: 0.01 to 0.15%, nitrogen: 0.001 to 0.05%
If an alloy containing any one or more selected from 5% and boron: 0.001 to 0.015% is adopted, the effect of improving the creep characteristics in the high pressure part can be obtained.

Next, in the high / low pressure integrated turbine rotor of the present invention, 0.1 to 3.0% by weight of cobalt, 0.01 to 0.15% of niobium, and 0.01 to 0.1% of tantalum.
15%, nitrogen: 0.001 to 0.05%, boron: 0.0
If an alloy containing at least one selected from 01 to 0.015% is employed, the effect of improving the toughness in the low-pressure part and the effect of further improving the creep characteristics in the high-pressure part can be obtained. .

Further, according to the method for manufacturing a high / low pressure integrated turbine rotor of the present invention, the portion corresponding to the high pressure portion of the turbine rotor material having a predetermined composition is heated to 980 ° C. or higher and 1100 ° C.
° C or less, and a portion corresponding to a low-pressure portion of the turbine rotor material is heated to 850 ° C or more and less than 980 ° C.
Cooling to a predetermined temperature of 0 ° C. to 700 ° C. by one or more of fountain cooling or blast cooling, then air cooling for 5 minutes to 5 hours, and then fountain cooling or blast cooling or oil to 300 ° C. Cooling is performed by one or more types of cooling means, and a portion corresponding to a low-pressure portion of the turbine rotor material is cooled by a cooling device capable of obtaining a speed higher than oil quenching. A high / low pressure integrated turbine rotor that does not cause creep embrittlement even when quenched from a high temperature region of 1100 ° C. or less can be easily manufactured.

Further, a high / low pressure integrated turbine rotor having a low pressure portion excellent in 0.2% proof stress, high Charpy impact value and excellent toughness can be easily obtained.

[0135]

[Table 1]

[0136]

[Table 2]

[0137]

[Table 3]

[0138]

[Table 4]

[0139]

[Table 5]

[0140]

[Table 6]

[0141]

[Table 7]

[0142]

[Table 8]

[0143]

[Table 9]

[0144]

[Table 10]

[0145]

[Table 11]

[0146]

[Table 12]

[0147]

[Table 13]

[0148]

[Table 14]

[Brief description of the drawings]

FIG. 1 is a micrograph of a high / low pressure integrated turbine rotor material according to the present invention.

[Description of Signs] 1 Proeutectoid ferrite phase 2 Bainite phase 3 Grain boundary 4 Carbon / nitride

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F01D 5/28 F01D 5/28 (72) Inventor Ryo Yamaguchi 5-717-1, Fukahori-cho, Nagasaki City, Nagasaki Prefecture Rishi Engineering Co., Ltd. F-term (reference) 3G002 AA07 AA11 AA13 AB08 4K042 AA14 BA02 BA14 CA02 CA04 CA06 CA08 CA09 CA10 CA13 DA01 DC02 DD03 DD04 DD05 DE02 DE03 DE06

Claims (11)

[Claims] 1. A high-low pressure integrated turbine rotor in which a high-pressure part and a low-pressure part are integrally formed, wherein 0.20 to 0.35% by weight of carbon and 0.15% by weight of carbon.
% Or less, manganese: 0.05 to 1.0%, nickel:
0.3-2.5%, chromium: 1.0-3.0%, molybdenum: 0.5-1.5%, tungsten: 0.1-3.
0%, vanadium: 0.1-0.3%, phosphorus: 0.
012% or less, sulfur: 0.005% or less, copper: 0.15
% Or less, aluminum: 0.01% or less, arsenic: 0.0
1% or less, tin: 0.01% or less, antimony: 0.00
3% or less, and the balance has a composition composed of iron containing unavoidable impurities, and the metal structure of the high-pressure part is more than 10% by volume and more than 40%.
A high-low pressure integrated turbine rotor comprising the following pro-eutectoid ferrite phase and the remaining bainite phase. 2. A high-low pressure integrated turbine rotor in which a high-pressure part and a low-pressure part are integrally formed, wherein carbon: 0.20 to 0.35% and silicon: 0.15% by weight.
% Or less, manganese: 0.05 to 1.0%, nickel:
0.05-2.5%, chromium: 1.0-3.0%, molybdenum: 0.5-1.5%, tungsten: 0.1-
3.0%, vanadium: 0.1-0.3%, cobalt:
0.1 to 3.0%, phosphorus: 0.012% or less, sulfur: 0.005% or less, copper: 0.15% or less, aluminum: 0.01% or less, arsenic: 0.01% or less ,tin:
0.01% or less, antimony: 0.003% or less, and the balance has a composition composed of iron containing unavoidable impurities, and the metal structure of the high-pressure part is more than 10% by volume and more than 40%.
A high-low pressure integrated turbine rotor comprising the following pro-eutectoid ferrite phase and the remaining bainite phase. 3. A high-low pressure integrated turbine rotor in which a high-pressure part and a low-pressure part are integrally formed, wherein 0.20 to 0.35% by weight of carbon and 0.15% by weight of carbon.
% Or less, manganese: 0.05 to 1.0%, nickel:
0.3-2.5%, chromium: 1.0-3.0%, molybdenum: 0.5-1.5%, tungsten: 0.1-3.
0%, vanadium: 0.1-0.3%, niobium: 0.01-0.15%, tantalum: 0.01-
0.15%, nitrogen: 0.001 to 0.05%, boron:
At least one selected from 0.001 to 0.015%, phosphorus: 0.012% or less, sulfur: 0.0
05% or less, copper: 0.15% or less, aluminum: 0.
01% or less, arsenic: 0.01% or less, tin: 0.01% or less, antimony: 0.003% or less, with the balance being composed of iron containing unavoidable impurities. Metal structure is more than 10% by volume% and 40%
A high-low pressure integrated turbine rotor comprising the following pro-eutectoid ferrite phase and the remaining bainite phase. 4. A high-low pressure integrated turbine rotor in which a high-pressure part and a low-pressure part are integrally formed, wherein carbon: 0.20 to 0.35% and silicon: 0.15% by weight.
% Or less, manganese: 0.05 to 1.0%, nickel:
0.05-2.5%, chromium: 1.0-3.0%, molybdenum: 0.5-1.5%, tungsten: 0.1-
3.0%, vanadium: 0.1-0.3%, cobalt:
0.1-3.0%, and niobium: 0.01-
0.15%, tantalum: 0.01 to 0.15%, nitrogen:
0.001 to 0.05%, boron: 0.001 to 0.01
Containing at least one selected from 5%, and phosphorus:
0.012% or less, sulfur: 0.005% or less, copper: 0.1% or less.
15% or less, aluminum: 0.01% or less, arsenic:
0.01% or less, tin: 0.01% or less, antimony:
0.003% or less, with the balance having a composition consisting of iron containing unavoidable impurities, and the metal structure of the high-pressure part is more than 10% by volume and more than 40%
A high-low pressure integrated turbine rotor comprising the following pro-eutectoid ferrite phase and the remaining bainite phase. 5. An average particle size of 0.5 in said pro-eutectoid ferrite phase.
The high / low pressure integrated turbine rotor according to any one of claims 1 to 4, wherein carbon / nitride having a diameter of 5 µm or less is finely dispersed. 6. The high / low pressure integrated turbine rotor according to claim 1, wherein a crystal grain size number of a metal structure of the high pressure portion is 3 or more and 6 or less. 7. A method for manufacturing a high / low pressure integrated turbine rotor in which a high pressure portion and a low pressure portion are integrally formed, wherein a portion corresponding to the high pressure portion of a turbine rotor material having a predetermined composition is heated to 980 ° C. C. or less, and a portion corresponding to a low pressure portion of the turbine rotor material is heated to 850 ° C. or more and less than 980 ° C., and a portion corresponding to a high pressure portion of the turbine rotor material is
Cool down to a predetermined temperature from 00 ° C to 700 ° C by one or more cooling means of fountain cooling or blast cooling, then air-cool for 5 minutes to 5 hours, then fountain cooling or blast cooling or oil to 300 ° C A high-low pressure integrated turbine rotor characterized in that a portion corresponding to a low-pressure portion of the turbine rotor material is cooled by a cooling device capable of obtaining a speed higher than oil quenching. Manufacturing method. 8. The turbine rotor material is, by weight percent, carbon: 0.20 to 0.35%, silicon: 0.15% or less, manganese: 0.05 to 1.0%, nickel: 0.3 to 0.3%. 2.
5%, chromium: 1.0 to 3.0%, molybdenum: 0.5
1.5 to 1.5%, tungsten: 0.1 to 3.0%, vanadium: 0.1 to 0.3%, phosphorus: 0.012% or less, sulfur: 0.005% or less, copper: 0.1 to 0.3%. 15% or less, aluminum: 0.01% or less, arsenic: 0.01% or less,
8. The high-low pressure steel according to claim 7, wherein the alloy steel has a composition of tin: 0.01% or less, antimony: 0.003% or less, and the balance being iron containing unavoidable impurities. A method for manufacturing a body type turbine rotor. 9. The turbine rotor material is, by weight%, 0.20 to 0.35% carbon, 0.15% or less silicon, 0.05 to 1.0% manganese, 0.05 to 0.05% nickel.
2.5%, chromium: 1.0 to 3.0%, molybdenum:
0.5-1.5%, tungsten: 0.1-3.0%,
Vanadium: 0.1-0.3%, Cobalt: 0.1-
3.0%, phosphorus: 0.012% or less, sulfur: 0.0
05% or less, copper: 0.15% or less, aluminum: 0.
01% or less, arsenic: 0.01% or less, tin: 0.01% or less, antimony: 0.003% or less, the balance being an alloy steel having a composition of iron containing unavoidable impurities. The method for manufacturing a high / low pressure integrated turbine rotor according to claim 7, wherein: 10. The turbine rotor material is, by weight%, carbon: 0.20 to 0.35%, silicon: 0.15% or less,
Manganese: 0.05-1.0%, Nickel: 0.3-
2.5%, chromium: 1.0 to 3.0%, molybdenum:
0.5-1.5%, tungsten: 0.1-3.0%,
Vanadium: containing 0.1-0.3%, and further niobium:
0.01 to 0.15%, tantalum: 0.01 to 0.15
%, Nitrogen: 0.001 to 0.05%, boron: 0.001
-0.015% or less, phosphorus: 0.012% or less, sulfur: 0.005% or less, copper: 0.15% or less, aluminum: 0.01% or less, An alloy steel having a composition of arsenic: 0.01% or less, tin: 0.01% or less, antimony: 0.003% or less, and the balance being iron containing unavoidable impurities. Item 8. A method for manufacturing a high-low pressure integrated turbine rotor according to Item 7. 11. The turbine rotor material is, by weight percent, 0.20 to 0.35% carbon, 0.15% or less silicon,
Manganese: 0.05-1.0%, Nickel: 0.05-
2.5%, chromium: 1.0 to 3.0%, molybdenum:
0.5-1.5%, tungsten: 0.1-3.0%,
Vanadium: 0.1-0.3%, Cobalt: 0.1-
3.0%, and niobium: 0.01-0.15
%, Tantalum: 0.01 to 0.15%, nitrogen: 0.00
1 to 0.05%, boron: at least one selected from 0.001 to 0.015%, phosphorus: 0.01
2% or less, sulfur: 0.005% or less, copper: 0.15% or less, aluminum: 0.01% or less, arsenic: 0.01%
Below, tin: 0.01% or less, antimony: 0.003%
The method for manufacturing a high-low pressure integrated turbine rotor according to claim 7, wherein the alloy steel is a steel alloy having the following composition, the balance being iron containing unavoidable impurities.