WO2017183063A1 - Turbine component, axial flow turbine, and method for manufacturing turbine component - Google Patents

Abstract

The turbine component according to an embodiment comprises a base material configured from an Fe-based alloy containing at least one element selected from the group consisting of Cr, Si, and Al. The base material has, from the interior of the base material toward the surface: a base material section; a composition section which is formed on the surface of the base material section, and which contains a crystal composition comprising crystal grain sizes of the Fe-based alloy that are smaller than the crystal grain sizes of the Fe-based alloy in the base material section; and a carburizing-resistant protective film section which is formed on the surface of the composition section, and which contains at least one element selected from the group consisting of Cr, Si, and Al.

Description

Turbine component, axial turbine, and method of manufacturing turbine component

Embodiments of the present invention relate to a turbine component, an axial turbine, and a method for manufacturing a turbine component.

Recently, a turbine using carbon dioxide as a working fluid has been developed. This turbine is driven by carbon dioxide generated by burning fuel such as natural gas mainly containing methane and coal gasification gas mainly containing carbon monoxide and hydrogen with oxygen. The carbon dioxide contained in the exhaust gas from the turbine is easily recovered by extraction. Since this turbine can realize power generation and carbon dioxide recovery at the same time, it has excellent environmental resistance such as suppression of global warming.

When the turbine using carbon dioxide as the working fluid is operating, the carbon dioxide in the turbine is in a supercritical state. Turbine components constituting the turbine are exposed to such a carburizing atmosphere for a long time. As a result, the turbine component may be carburized. When the turbine component is carburized, a carburized layer is formed on the surface of the turbine component, and the turbine component becomes brittle. As embrittlement progresses, the surface of the turbine component may crack.

By the way, it has been studied to suppress the carburization of the base material by forming a film such as Cr ₂ O ₃ or SiO _{2 on} the base material. For low alloy steels that have been pre-oxidized at 800 ° C. to 1200 ° C. and then carburized at 950 ° C., the lower alloy steels with higher Cr and Si additions are less carburized.

“Effect of oxide layer on gas carburization of case-hardened steel”, Electric Steel, Vol. 84, No. 1, 2013, p. 21-29

As described above, carburization of the base material can be suppressed by heat-treating the base material made of low alloy steel at a high temperature of about 1000 ° C. On the other hand, although the temperature at the time of use of the turbine component which comprises the turbine mentioned above changes with installation places, the temperature of the turbine rotor at the time of use is 500 degrees C or less, for example. For the turbine parts, low alloy steel with a low content of elements such as Cr and Si, which are components that form a film that suppresses carburization, is used. Therefore, in the temperature range of 500 ° C. or less, the diffusion rate of atoms in the turbine component is slow, and the amount of atoms diffusing on the surface of the turbine component is small. Therefore, it is difficult to uniformly form a coating for suppressing carburization on the surface of the turbine component in the temperature range when the turbine is used.

The problem to be solved by the present invention is to provide a turbine part, an axial turbine, and a method of manufacturing a turbine part that have a carburization-resistant protective coating portion formed in a use temperature range of the turbine and can suppress carburization. It is to be.

The turbine component of the embodiment is composed of a base material composed of an Fe-based alloy containing at least one element selected from the group consisting of Cr, Si, and Al. And the said base material is formed in the surface of the base material part and the said base material part toward the surface from the inside of the said base material, and is smaller than the crystal grain diameter of the said Fe-based alloy in the said base material part A structure part including a crystal structure composed of a crystal grain size of an Fe-based alloy, and a carburization-resistant protective film part formed on the surface of the structure part and including at least one element selected from the group consisting of Cr, Si, and Al And have.

It is possible to provide a turbine component, an axial turbine, and a method for manufacturing a turbine component that have a carburization-resistant protective coating portion formed in a use temperature range of the turbine and can suppress carburization.

It is a meridional sectional view schematically showing an axial flow turbine including the turbine component of the first embodiment. It is sectional drawing which shows typically the turbine component of 1st Embodiment. It is the schematic which shows an example of the method of forming a structure | tissue part in the base material which comprises the turbine components of 1st Embodiment. It is the schematic which shows the other example of the method of forming a structure | tissue part in the base material which comprises the turbine component of 1st Embodiment. It is the schematic which shows the other example of the method of forming a structure | tissue part in the base material which comprises the turbine component of 1st Embodiment. It is the schematic which shows the method of forming a structure | tissue part in the base material which comprises the turbine components of 2nd Embodiment.

Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a meridional sectional view schematically showing an axial-flow turbine 10 including the turbine component of the first embodiment. Examples of the axial turbine 10 shown in FIG. 1 include a gas turbine and a CO ₂ turbine. In the CO ₂ turbine, a part of carbon dioxide (CO ₂ ) generated by the combustor is pressurized to a supercritical fluid and circulated in the working fluid system, and the working fluid is carbon dioxide.

As shown in FIG. 1, the axial turbine 10 includes a double-structure casing that includes an outer casing 11 and an inner casing 12 provided inside the outer casing 11. The inner casing 12 constitutes, for example, inner casings 12a and 12b surrounding a turbine stage including the stationary blades 13 and the moving blades 14, and a part of the exhaust chamber 15 into which the working fluid that has passed through the final stage turbine stage flows. An inner casing 12c.

A tube-shaped portion 11a extending downward is provided on the lower half side of the outer casing 11 on the downstream side in order to discharge the working fluid.

In the inner casing 12, a turbine rotor 16 in which a moving blade 14 is implanted is provided. The turbine rotor 16 is rotatably supported by a rotor bearing (not shown).

The stationary blades 13 are arranged on the inner surfaces of the inner casings 12a and 12b so as to alternate with the moving blades 14 in the turbine rotor axial direction. The stationary blade 13 and the moving blade 14 immediately downstream of the stationary blade 13 constitute a turbine stage.

For example, an annular wall 12d is provided on the outer peripheral surface of the inner casing 12b adjacent to the inner casing 12c so as to protrude radially outward in the circumferential direction. The outer peripheral surface of this annular wall 12d is in contact with the inner periphery of the outer casing 11, for example. A space formed between the outer casing 11 and the inner casing 12 is partitioned by the annular wall 12d.

A seal portion 17 is provided between the turbine rotor 16 and the outer casing 11 and between the turbine rotor 16 and the inner casing 12a in order to prevent leakage of the working fluid to the outside.

An exhaust chamber 15 is provided downstream of the final stage turbine stage. The exhaust chamber 15 includes an annular inner casing 12c through which the working fluid that has passed through the final stage turbine stage flows, and a tube-shaped portion 18 provided on the lower half side of the inner casing 12c. An annular passage 19 is formed in the annular inner casing 12c.

The annular passage 19 is formed around the turbine rotor 16. The annular passage 19 guides the working fluid that has passed through the final stage turbine stage to the tube-shaped portion 18.

The tube-shaped portion 18 extends downward along the tube-shaped portion 11 a inside the tube-shaped portion 11 a of the outer casing 11. The working fluid that has passed through the tube-shaped portion 18 is discharged to the outside of the outer casing 11 through the tube-shaped portion 11a.

Also, the axial turbine 10 is provided with a transition piece 20 that discharges working fluid flowing from a combustor (not shown) to the first stage turbine stage. The working fluid discharged from the transition piece 20 to the turbine stage flows through the inner casings 12a and 12b while performing expansion work, and passes through the final stage turbine stage.

In the axial flow turbine 10, the turbine component of the first embodiment can be applied to the outer casing 11 and the turbine rotor 16. And the carburization-resistant protective film part is formed in at least one part of the surface of these turbine components. For example, when the turbine component according to the first embodiment is applied to the outer casing 11, a carburization-resistant protective coating portion is formed on the inner surface of the base material constituting the turbine component. When the turbine component is applied to the turbine rotor 16, a carburization-resistant protective coating portion is formed on the side surface of the base material constituting the turbine component.

Next, the turbine component of the first embodiment will be described in detail.

FIG. 2 is a cross-sectional view schematically showing the turbine component 1 according to the first embodiment. As shown in FIG. 2, the turbine component 1 includes a base material 2.

The substrate 2 is made of an Fe-based alloy containing at least one element selected from the group consisting of Cr, Si, and Al. The Fe-based alloy constituting the substrate 2 may contain Mo, V, etc. in addition to these elements. Examples of the Fe-based alloy include carbon steel, low alloy steel, special steel, and heat resistant steel. Among these, CrMo steels such as low alloy steel, 12Cr steel, CrMoV steel, 2.25Cr-1Mo and modified 9Cr-1Mo (9Cr-1Mo-Nb-V) are used because of their good strength and heat resistance. preferable.

In addition, the base material 2 includes a base material portion 3, a tissue portion 4 formed on the surface of the base material portion 3, and a carburization-resistant carburization formed on the surface of the tissue portion 4 from the inside of the base material 2 toward the surface. Protective film portion 5.

The base material part 3 constitutes the inside of the base material 2. That is, the base material portion 3 is made of an Fe-based alloy containing at least one element selected from the group consisting of Cr, Si, and Al.

The layered structure portion 4 formed on the surface of the base material portion 3 is made of an Fe-based alloy containing at least one element selected from the group consisting of Cr, Si, and Al, like the base material portion 3. In addition, the texture portion 4 includes a crystal structure composed of a crystal grain size of the Fe-based alloy smaller than the crystal grain size of the Fe-based alloy in the base material portion 3. In the structure part 4, the crystal grain size of the Fe-based alloy decreases from the interface between the base material part 3 and the structure part 4 toward the surface of the structure part 4, and the crystal structure of the Fe-based alloy becomes finer.

The layered carburization-resistant protective coating portion 5 formed on the surface of the tissue portion 4 contains at least one element selected from the group consisting of Cr, Si, and Al. In addition, the crystal phase constituting the structure of the carburization-resistant protective coating part 5 is different from that of the base material part 3 and the structure part 4. As will be described later, the carburization-resistant protective coating portion 5 is formed by heating the base material 2 having the tissue portion 4. Cr, Si, and Al contained in the carburization-resistant protective coating part 5 are not supplied from the outside of the base material 2, but Cr contained in the base material part 3 and the structure part 4 constituting the base material 2, Supplied by out diffusion of Si and Al. Therefore, the carburization-resistant protective coating portion 5 is not separately provided on the surface of the substrate 2 but is formed by modifying the surface of the substrate 2.

The carburization resistant protective coating 5 diffuses Cr, Si, and Al diffused from the inside of the base 3 and the tissue 4 to the surface of the tissue 4, oxygen in the air, and the surface of the tissue 4 to the inside. It is composed of oxides such as chromia, silica, and alumina generated by reaction with oxygen.

Moreover, the carburization-resistant protective coating 5 has excellent carburization resistance. Compared with the base material part 3 and the structure part 4, the diffusion rate of carbon diffusing in the carburization-resistant protective coating part 5 is slow. In a carburizing atmosphere such as carbon dioxide or carbon monoxide, the carburization-resistant protective coating portion 5 suppresses the intrusion of carbon into the structure portion 4 and the base material portion 3, thereby suppressing the formation of a carburized layer on the surface of the turbine component 1. Is done. Thus, the carburization-resistant protective coating portion 5 can suppress the carburization of the turbine component 1 when the axial flow turbine 10 is used. And embrittlement of the turbine component 1 in a carburizing atmosphere is suppressed.

In addition, the average crystal grain size of the Fe-based alloy in the structure part 4 is preferably 20 μm or less, and more preferably 10 μm or less. When the average crystal grain size of the Fe-based alloy in the texture portion 4 is within such a range, Cr, Si, and Al can diffuse in the texture portion 4 at a lower temperature. Therefore, the amount of these atoms that diffuse outward in the tissue portion 4 increases, and the formation rate of the carburization-resistant protective coating portion 5 increases.

The average crystal grain size of the Fe-based alloy is the median diameter. The average crystal grain size of the Fe-based alloy is measured by, for example, a laser diffraction scattering method.

Next, a method for manufacturing the turbine component 1 according to the first embodiment will be described. The manufacturing method of the turbine component 1 according to the first embodiment is based on the structure portion 4 including a crystal structure having a crystal grain size of an Fe-based alloy smaller than the crystal grain size of the Fe-based alloy inside the base material 2. 2 forming on the surface of 2 (hereinafter also referred to as a first forming step), and heating the base material 2 to protect the carburization resistance including at least one element selected from the group consisting of Cr, Si, and Al. And forming a film part 5 on the surface of the tissue part 4 (hereinafter also referred to as a second forming process).

In the first forming step, the layered structure portion 4 is formed on the surface of the base material 2 composed of an Fe-based alloy containing at least one element selected from the group consisting of Cr, Si, and Al. The crystal grain size of the Fe-based alloy in the texture portion 4 is smaller than the crystal grain size of the Fe-based alloy in the base material 2, that is, the base material portion 3. In the first forming step, residual stress is applied to the surface of the substrate 2 to form the tissue portion 4 on the surface of the substrate 2. In this way, the base material 2 has the base material part 3 and the structure | tissue part 4 uniformly formed in the surface of the base material part 3 from the inside of the base material 2 toward the surface.

FIG. 3 is a schematic view showing an example of a method of forming the tissue portion 4a on the base material 2 constituting the turbine component 1 of the first embodiment. As shown in FIG. 3, the surface of the substrate 2 is hit with the peening hammer 30 while moving the peening hammer 30 along the arrow A. In this way, hammer peening is applied to the surface of the substrate 2 to mechanically apply residual stress to the surface of the substrate 2. A tissue portion 4a is formed on the surface of the substrate 2 to which the residual stress is applied and in the vicinity of the surface. Thus, the base material 2 has the base material part 3 and the tissue part 4a formed uniformly on the surface of the base material part 3. The thickness of the textured portion 4a and the size of the crystal grain size of the Fe-based alloy in the textured portion 4a can be adjusted as appropriate according to the strength with which the surface of the substrate 2 is tapped and the tapping time.

FIG. 4 is a schematic view showing another example of a method for forming the tissue portion 4b on the base material 2 constituting the turbine component 1 of the first embodiment. As shown in FIG. 4, the particles 41 are sprayed onto the surface of the substrate 2 by the shot peening device 40 while moving the shot peening device 40 along the arrow A. In this way, shot peening is performed on the surface of the substrate 2 to mechanically apply residual stress to the surface of the substrate 2. A tissue portion 4b is formed on the surface of the base material 2 to which the residual stress is applied and in the vicinity of the surface. In this way, the base material 2 has the base material part 3 and the structure part 4b formed uniformly on the surface of the base material part 3. The thickness of the textured part 4b and the crystal grain size of the Fe-based alloy in the textured part 4b can be appropriately adjusted according to the type of the particles 41, the spraying speed and spraying time of the particles 41, and the like.

FIG. 5 is a schematic view showing another example of a method of forming the tissue portion 4c on the base material 2 constituting the turbine component 1 of the first embodiment. As shown in FIG. 5, the surface of the substrate 2 is cut with the cutting tool 50 while moving the cutting tool 50 along the arrow A. In this way, the surface of the substrate 2 is subjected to a machining process to mechanically apply a residual stress to the surface of the substrate 2. For example, when the base material 2 is processed using a lathe, the amount of driving in the final processing of the surface of the base material 2 is increased by 50% to 70% compared to the normal processing of the base material 2. Residual stress can be mechanically applied to the surface of the material 2. A tissue portion 4c is formed on the surface of the substrate 2 to which the residual stress is applied and in the vicinity of the surface. Thus, the base material 2 includes the base material part 3 and the tissue part 4 c that is uniformly formed on the surface of the base material part 3. The thickness of the textured part 4c and the crystal grain size of the Fe-based alloy in the textured part 4c can be adjusted as appropriate according to the depth of cutting.

In the second forming step, the base material 2 having the tissue portion 4 formed on the surface of the base material portion 3 is heated to thereby form a layered carburization-resistant protective coating portion 5 on the surface of the tissue portion 4 and in the vicinity of the surface. Form. Thus, the base material 2 is uniformly formed on the surface of the base material part 3, the tissue part 4 formed on the surface of the base material part 3, and the surface of the tissue part 4 from the inside of the base material 2 toward the surface. And a carburization-resistant protective coating portion 5.

The heating temperature of the substrate 2 in the second forming step is preferably 400 ° C. or more and 500 ° C. or less. This temperature range corresponds to the operating temperature range of the axial flow turbine 10.

It is considered that when the base material 2 having the tissue part 4 is heated, the carburization-resistant protective film part 5 is formed by the following reaction. When the base material 2 having the textured portion 4 is heated, at least one atom of Cr, Si, and Al in the Fe-based alloy constituting the textured portion 3 and the textured portion 4, mainly the textured portion 4, is 4 diffuses to the surface of the textured part 4 along the grain boundaries in the part 4. These atoms diffused outward on the surface of the tissue part 4 react with oxygen in the air and oxygen diffused inward from the surface of the tissue part 4 to produce oxides, which are thin and uneven carburizing resistance. A protective coating 5 is formed. Thereafter, from these atoms diffused outwardly from the inside of the tissue portion 4 to the interface between the tissue portion 4 and the carburization-resistant protective coating portion 5 and from the surface of the carburization-resistant protective coating portion 5, The carburization-resistant protective film portion having a predetermined thickness and uniform and excellent carburization resistance reacts with the oxygen diffused inward at the interface between the structure portion 4 and the carburization-resistant protective coating portion 5. 5 is formed.

Generally, the higher the heating temperature, the faster the diffusion rate of atoms in the material. Here, the crystal grain size of the Fe-based alloy in the textured portion 4 is smaller than that of the base material portion 3. In other words, the structure of the Fe-based alloy in the structure part 4 is finer than that of the base material part 3. Therefore, compared with the base material part 3, there are many crystal grain boundaries in the textured part 4. As the number of crystal grain boundaries increases, the amount of atoms diffusing through the crystal grain boundaries increases.

That is, in the structure part 4 in which the crystal grain size of the Fe-based alloy is small, the amount of atoms diffusing outward to the surface along the crystal grain boundary is larger than in the base material part 3. Since a large amount of atoms diffused on the surface of the tissue part 4 reacts with oxygen, the carburization-resistant protective coating part 5 is formed at a lower temperature in a shorter time. Thus, even if it is the use temperature range of the axial flow turbine 10 like 400 degreeC or more and 500 degrees C or less by the heating temperature lower than before by forming the structure | tissue part 4 on the surface of the base material part 3, for example. The carburization-resistant protective coating portion 5 can be uniformly formed on the surface of the substrate 2.

Thus, in the tissue part 4, the outwardly diffused Cr, Si, and Al react with the inwardly diffused oxygen, whereby the carburization-resistant protective coating part 5 is formed on the surface of the tissue part 4. That is, the base material portion 3 and the tissue portion 4 are mainly supplied from outside the base material portion 3 and the tissue portion 4, in other words, without supplying Cr, Si, and Al from the outside of the base material 2 to the surface of the tissue portion 4. As a result, Cr, Si, and Al contained in the structure part 4 diffuse into the surface of the structure part 4, thereby forming the carburization-resistant protective coating part 5. Thus, since the carburization-resistant protective coating 5 is formed by modifying the surface of the substrate 2, the adhesion between the tissue portion 4 and the carburizing-resistant protective coating 5 is very strong. Peeling of the carburization-resistant protective coating part 5 from is suppressed.

The thickness of the carburization-resistant protective coating part 5 is the thickness of the structure part 4, the crystal grain size of the Fe-based alloy in the structure part 4, the heating temperature and the heating time of the substrate 2 in the second forming step, etc. It can be appropriately adjusted according to the above.

Moreover, the manufacturing method of the turbine component 1 of 1st Embodiment heats the base material 2 at the temperature higher than the heating temperature of the base material 2 in a 2nd formation process before a 2nd formation process. And a step of phase transformation of the crystal of the Fe-based alloy (hereinafter also referred to as a phase transformation step). In the phase transformation step, the base 2 having the textured portion 4 is heated at a temperature higher than that in the second forming step, whereby the phase of the Fe-based alloy constituting the substrate 3 and the textured portion 4 is transformed into austenite. To do.

When the phase of the Fe-based alloy is transformed to austenite, recrystallization occurs in the base material portion 3 and the texture portion 4, so that the structure of the Fe alloy in the base material portion 3 and the texture portion 4 becomes finer. Further, more crystal grain boundaries are generated in the textured portion 4. Therefore, the carburization-resistant protective coating part 5 can be formed by lowering the heating temperature in the second forming step.

The heating temperature of the substrate 2 in the phase transformation step is preferably 800 ° C. or higher and 1100 ° C. or lower, and more preferably 900 ° C. or higher and 1000 ° C. or lower. When the base material 2 is heated in such a temperature range, the structure of the Fe alloy in the structure portion 4 is further refined.

As described above, according to the turbine component and the method of manufacturing a turbine component of the first embodiment, more atoms than the base material portion 3 are present in the structure portion 4 having more crystal grain boundaries than the base material portion 3. Diffuses outward. At this time, even if the heating temperature of the base material 2 is lower than the conventional temperature, a large amount of atoms diffuses in the tissue part 4. Therefore, it is possible to form the carburization-resistant protective coating portion 5 having a lower carburization resistance and a lower temperature than before. And since the carburizing of the turbine component 1 can be suppressed at the time of use of the axial flow turbine 10, the lifetime of the turbine component 1 can be improved.

(Second Embodiment)
FIG. 6 is a schematic diagram illustrating a method of forming the tissue portion 4d on the base material 2 constituting the turbine component of the second embodiment. In the following embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted or simplified.

The turbine component manufacturing method of the second embodiment is basically the same as the turbine component manufacturing method of the first embodiment, except that the method of forming the tissue portion 4d is different. Therefore, here, the different configuration will be mainly described.

In the turbine component manufacturing method of the second embodiment, in the first forming step, the surface of the base material 2 is melted to form the tissue portion 4d on the surface of the base material 2.

As shown in FIG. 6, the surface of the substrate 2 is melted by irradiating the surface of the substrate 2 with a laser beam 61 by the laser device 60 while moving the laser device 60 such as a semiconductor laser along the arrow A. A fine columnar cell structure is formed on the surface of the base material 2 that has been melted and cooled and in the vicinity of the surface. This columnar cell structure extends from the inside of the substrate 2 toward the surface. Then, by melting the base material 2 and forming a plurality of fine cell structures in layers on the surface of the base material 2, the tissue portion 4 d having a plurality of cell structures is formed on the surface of the base material 2 and in the vicinity of the surface. It is formed. Thus, the base material 2 has the base material part 3 and the tissue part 4d that is uniformly formed on the surface of the base material part 3. The thickness of the tissue portion 4d and the crystal grain size of the Fe-based alloy in the tissue portion 4d can be appropriately adjusted according to the irradiation intensity of the laser beam 61 and the irradiation time of the laser beam 61.

When the base material 2 having the texture portion 4d is heated, at least one atom of Cr, Si, and Al in the Fe-based alloy constituting the base material portion 3 and the texture portion 4d, mainly the texture portion 4d, It diffuses to the surface of the textured part 4d along the crystal grain boundaries formed between the fine cell textures in 4d. These atoms diffused outward to the surface of the tissue part 4d react with oxygen in the air and oxygen diffused inward from the surface of the tissue part 4d to form a non-uniform carburization-resistant protective coating part 5. Is done. After that, these atoms diffused outward from the inside of the tissue portion 4d to the interface between the tissue portion 4d and the carburization-resistant protective coating portion 5 and the surface of the carburization-resistant protective coating portion 5 from the surface of the carburizing-resistant protective coating portion 5 The carburization-resistant protective film portion having a predetermined thickness and uniform and excellent carburization resistance reacts with the oxygen diffused inward at the interface between the structure portion 4d and the carburization-resistant protective coating portion 5 5 is formed.

As described above, according to the turbine component and the turbine component manufacturing method of the second embodiment, the surface of the base material 2 is melted to form the tissue portion 4d having a fine cell structure. In the texture portion 4d, a large amount of atoms diffuse along the grain boundaries between the cell textures. Therefore, it is possible to form the carburization-resistant protective coating 5 having a low carburization resistance at a lower temperature than before, and the carburization of the turbine component 1 can be suppressed.

Hereinafter, a detailed description will be given with reference to examples. In addition, this invention is not limited at all by these Examples.

Example 1
As a substrate, Cr—Mo—V steel (1% Cr—1.5% Mo—0.3% V) was prepared. A hammer peening treatment was applied to the surface of the base material to form a tissue portion on the surface of the base material. Subsequently, the surface of the base material on which the tissue part was formed was heated to 900 ° C. with a burner, and then rapidly cooled, whereby the crystal structure of the tissue part was transformed and refined. Subsequently, the substrate was heated to 500 ° C. to form a carburization-resistant protective coating on the surface of the tissue part. In this way, a turbine component composed of a base material having a base material part, a structure part, and a carburization-resistant protective coating part from the inside to the surface of the base material was manufactured.

(Example 2)
In Example 1, a turbine component was manufactured in the same manner as in Example 1 except that the surface of the base material was subjected to shot peening treatment to form a textured portion on the surface of the base material.

(Example 3)
In Example 1, the surface of the base material was subjected to machining processing to form a tissue part on the surface of the base material, and the surface of the base material on which the tissue part was formed was heated to 900 ° C. with a high-frequency induction heating device Produced turbine parts in the same manner as in Example 1. In machining processing, residual stress is applied to the surface of the substrate by using a cutting tool and increasing the amount of driving in the final processing of the surface of the substrate by 50% to 70% compared to normal processing of the substrate. It was.

Example 4
As a base material, Cr—Mo—V steel was prepared. The surface of this base material was irradiated with laser light using a semiconductor laser, and the surface of the base material was melted to form a tissue part on the surface of the base material. Subsequently, the substrate was heated to 500 ° C. to form a carburization-resistant protective coating on the surface of the tissue part. Thus, a turbine component was manufactured.

(Comparative Example 1)
As a base material, Cr—Mo—V steel was prepared. Subsequently, the substrate was heated to 500 ° C. Thus, a turbine component was manufactured. The turbine part manufactured in Comparative Example 1 is not formed with a textured part and a carburization-resistant protective coating part.

The turbine parts manufactured in Examples 1 to 4 and Comparative Example 1 were evaluated for carburization resistance. The turbine parts produced in Examples 1 to 4 and Comparative Example 1 were heated at 500 ° C. for 100 hours in an atmosphere of carbon dioxide. And the cross section of the turbine component was observed.

A carburized layer was formed on the surface of the turbine part of Comparative Example 1. On the other hand, in the turbine parts of Examples 1 to 4, no carburized layer was formed, and a turbine part excellent in carburization resistance could be manufactured.

Embodiments 1 to 4 provide a turbine part, an axial turbine, and a method of manufacturing a turbine part that have a carburization-resistant protective coating portion formed in the operating temperature range of the turbine and can suppress carburization. be able to.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Turbine component, 2 ... Base material, 3 ... Base material part, 4, 4a, 4b, 4c, 4d ... Structure | tissue part, 5 ... Carburization-resistant protective coating part, 10 ... Axial flow turbine, 11 ... External casing, 11a ... Pipe-shaped part, 12, 12a, 12b, 12c ... Inner casing, 12d ... Annular wall, 13 ... Stator blade, 14 ... Moving blade, 15 ... Exhaust chamber, 16 ... Turbine rotor, 17 ... Seal part, 18 ... Pipe shape , 19 ... annular passage, 20 ... transition piece, 30 ... peening hammer, 40 ... shot peening device, 41 ... particles, 50 ... cutting tool, 60 ... laser device, 61 ... laser beam.

Claims (8)

A turbine component comprising a base material composed of an Fe-based alloy containing at least one element selected from the group consisting of Cr, Si, and Al,
The base material is directed from the inside to the surface of the base material.
A base material part;
A textured part formed on the surface of the base part and including a crystal structure composed of a crystal grain size of the Fe base alloy smaller than a crystal grain size of the Fe base alloy in the base part;
A turbine component comprising: a carburization-resistant protective coating portion formed on a surface of the tissue portion and containing at least one element selected from the group consisting of Cr, Si, and Al. An axial flow turbine comprising the turbine component according to claim 1, wherein the working fluid is carbon dioxide. A method for producing a turbine component comprising a base material composed of an Fe-based alloy containing at least one element selected from the group consisting of Cr, Si, and Al,
Forming a textured portion on the surface of the base material including a crystal structure composed of a crystal grain size of the Fe-based alloy smaller than a crystal grain size of the Fe-based alloy inside the base material;
Heating the base material, and forming a carburization-resistant protective coating portion containing at least one element selected from the group consisting of Cr, Si, and Al on the surface of the tissue portion. A method for manufacturing a turbine component. 4. The method of manufacturing a turbine component according to claim 3, wherein, in the step of forming the tissue part, residual stress is applied to the surface of the base material to form the tissue part on the surface of the base material. The method for manufacturing a turbine component according to claim 4, wherein the surface of the base material is subjected to a hammer peening process, a shot peening process, or a machining process to apply the residual stress to the surface of the base material. The method of manufacturing a turbine component according to claim 3, wherein, in the step of forming the tissue part, the surface of the base material is melted to form the tissue part on the surface of the base material. The method for manufacturing a turbine component according to claim 6, wherein the surface of the base material is irradiated with laser light to melt the surface of the base material. Before the step of forming the carburization-resistant protective coating portion, the substrate is heated at a temperature higher than the heating temperature in the step of forming the carburization-resistant protective coating portion, and the Fe-based alloy crystals are phased. The method for manufacturing a turbine component according to any one of claims 3 to 7, further comprising a step of transforming.

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