JP6991755B2 - Manufacturing method of nozzle plate of steam turbine - Google Patents

Description

An embodiment of the present invention relates to a method for manufacturing a nozzle plate of a steam turbine.

In a steam turbine, the stationary blade row is composed of, for example, a nozzle diaphragm in which a plurality of nozzle plates (static blades) are arranged between the outer ring of the diaphragm and the inner ring of the diaphragm. In the nozzle diaphragm, the nozzle plate is fixed to each of the diaphragm outer ring and the diaphragm inner ring.

Patent No. 4040922 Patent No. 3106130 JP-A-2010-242221 Japanese Unexamined Patent Publication No. 2000-297606 Japanese Unexamined Patent Publication No. 5-125471 Japanese Unexamined Patent Publication No. 2007-0912212

Forming the nozzle plate of a steam turbine is generally performed by cutting a square lumber formed by forging or rolling. Therefore, it takes a lot of time to manufacture the nozzle plate as described above. In addition, the yield is low because the difference between the weight of the square lumber, which is the raw material, and the weight of the nozzle plate, which is the final product, is large. Due to such circumstances, the manufacturing efficiency of the nozzle plate is low, and it is not easy to reduce the cost. In other words, it is not rational from the viewpoint of economy.

Therefore, an object to be solved by the present invention is to provide a method for manufacturing a nozzle plate of a steam turbine, which has high manufacturing efficiency and can easily realize cost reduction.

The method for manufacturing a nozzle plate of a steam turbine according to an embodiment includes a preparation step and a casting step. In the preparatory step, the composition is C: 0.10 to 0.15, Si: 0.60 or less, Mn: 0.60 or less, Ni: 0.60 or less, Cr in mass% by the electroslag remelting method. Prepare a metallic material containing 12.0 to 14.0 and formed such that the balance consists of Fe and unavoidable impurities . In the casting process, the prepared metal material is melted again, and the composition is C: 0.10 to 0.15, Si: 0.60 or less, Mn: 0.60 or less, Ni: 0 in mass%. Dissolution is performed by adding a metal component so that it contains .60 or less, Cr: 12.0 to 14.0, N: 0.01 to 0.03, and the balance consists of Fe and unavoidable impurities. The molten metal is formed in the above-mentioned molten metal, and the nozzle plate of the steam turbine is cast using the molten metal.

FIG. 1 shows a diagram schematically showing a steam turbine including a stationary blade row composed of a nozzle plate (static blade) of the present embodiment.

First, the nozzle plates (M1) to (M5) of the embodiment will be described. The nozzle plates (M1) to (M5) of the embodiment are in the range shown below for each component.

The composition of the nozzle plate (M1) is, in mass%, C: 0.10 to 0.15, Si: 0.60 or less, Mn: 0.60 or less, Ni: 0.60 or less, Cr: 12.0 to It contains 14.0, N: 0.01 to 0.03, and the balance consists of Fe and unavoidable impurities.

The composition of the nozzle plate (M2) is C: 0.10 to 0.15, Si: 0.60 or less, Mn: 0.40 to 0.60, Ni: 0.60 or less, Cr: 10 in mass%. .0 to 11.5, Mo: 0.80 to 1.10, V: 0.15 to 0.25, Nb: 0.05 to 0.20, N: 0.01 to 0.03. The balance consists of Fe and unavoidable impurities.

The composition of the nozzle plate (M3) is C: 0.10 to 0.15, Si: 0.60 or less, Mn: 0.40 to 0.60, Ni: 0.60 or less, Cr: 9 in mass%. .2 to 10.2, Mo: 0.80 to 1.10, V: 0.15 to 0.25, W: 0.80 to 1.10, Nb: 0.05 to 0.10, N: 0 It contains 0.01-0.03 and the balance consists of Fe and unavoidable impurities.

The composition of the nozzle plate (M4) is C: 0.10 to 0.15, Si: 0.30 or less, Mn: 0.40 to 0.60, Ni: 0.30 or less, Cr: 9 in mass%. .0 to 10.5, Mo: 0.50 to 0.80, V: 0.15 to 0.25, W: 1.60 to 1.90, Nb: 0.015 to 0.025, Co: 1 It contains 0.0 to 3.0, N: 0.01 to 0.03, and the balance consists of Fe and unavoidable impurities.

The nozzle plate (M5) has C: 0.10 to 0.15, Si: 0.30 or less, Mn: 0.40 to 0.60, Ni: 0.30 or less, Cr: 9.0 to 10.5. , Mo: 0.50 to 0.80, V: 0.15 to 0.25, W: 1.60 to 1.90, Nb: 0.015 to 0.025, Co: 1.0 to 3.0 , B: 0.005 to 0.009, N: 0.01 to 0.03, the balance consisting of Fe and unavoidable impurities.

The nozzle plates (M1) to (M5) of the embodiment have almost no anisotropy, have uniform mechanical properties, and are excellent in economy. In the above, "C: 0.11 to 0.15" and the like indicate that the content of C element is 0.11% by mass or more and 0.15% by mass or less. Further, "Si: 0.60 or less" or the like indicates that the content of Si element is 0.60% by mass or less, and includes the case where the content of Si element is zero (the same applies hereinafter).

The reason why the ratio (content rate) contained in each component in the nozzle plates (M1) to (M5) of the embodiment is set in the above range will be described.

C (carbon) [(M1) to (M5) ... 0.10 to 0.15]
C is a component necessary for ensuring hardenability and hot water flowability during casting, and is an indispensable component as a constituent element of a carbide that contributes to precipitation strengthening. In the nozzle plates (M1) to (M5) of the embodiment, when the content of C is less than the lower limit of the above range, the above-mentioned actions and effects become small. When the C content exceeds the upper limit of the above range, the aggregation of carbides is promoted and the segregation tendency at the time of casting is increased, so that the weldability including repair is lowered. Therefore, in the nozzle plates (M1) to (M5) of the embodiment, the content rate of C is set in the above range.

-Si (silicon) [(M1), (M2), (M3) ... 0.60 or less, (M4), (M5) ... 0.30 or less]
Si is useful as a deoxidizing agent and is a component that improves the flowability of molten metal. In the nozzle plates (M1), (M2), and (M3) of the embodiment, when the Si content exceeds the upper limit of the above range, the decrease in toughness and embrittlement are significantly promoted. Further, since the nozzle plates (M4) and (M5) of the embodiment contain a large amount of ferrite forming elements, the structure can be stabilized by setting the Si content to the upper limit of the above range or less. Can be done. Therefore, in the nozzle plates (M1) to (M5) of the embodiment, the Si content is set in the above range.

Mn (manganese) [(M1) ... 0.60 or less, (M2) to (M5) ... 0.40 to 0.60]
Mn is a useful component as a desulfurizing agent. In the nozzle plates (M1) to (M5) of the embodiment, when the Mn content exceeds the upper limit of the above range, the creep strength is lowered. Since the nozzle plates (M2) to (M5) of the embodiment contain a ferrite forming element, the structure can be stabilized by setting the Mn content to the lower limit of the above range or more. When the Mn content is less than the lower limit of the above range, the desulfurization effect is not sufficiently exhibited. Therefore, in the nozzle plates (M1) to (M5) of the embodiment, the Mn content is set in the above range.

-Ni (nickel) [(M1), (M2), (M3) ... 0.60 or less, (M4), (M5) ... 0.30 or less]
Ni is a component that improves hardenability and toughness, and also has an effect of suppressing the formation of ferrite. In the nozzle plates (M1), (M2), and (M3) of the embodiment, when the Ni content exceeds the upper limit of the above range, the creep strength is lowered. The nozzle plates (M4) and (M5) of the embodiment contain a Co (cobalt) component, and by setting the Ni content to the lower limit of the above range or more, the decrease in creep strength is suppressed and the structure is reduced. It is possible to realize stabilization and excellent high temperature characteristics. Therefore, in the nozzle plates (M1) to (M5) of the embodiment, the Ni content is set in the above range.

Cr (chromium) [(M1) ... Cr: 12.0-14.0, (M2) ... Cr: 10.0 to 11.5, (M3) ... Cr: 9.2 to 10.2, (M4). ), (M5) ... Cr: 9.0 to 10.5]
Cr is an effective component for improving oxidation resistance and corrosion resistance, and is an indispensable component as a constituent element of carbonitride that contributes to precipitation strengthening. In the nozzle plates (M1) to (M5) of the embodiment, when the Cr content is less than the lower limit of the above range, the precipitate (carbonitride) that precipitates Cr as a constituent element in the heat treatment treatment is Since the number is reduced, high temperature stability may not be sufficiently ensured. When the Cr content exceeds the upper limit of the above range, the amount of delta ferrite produced increases. In the nozzle plates (M1) to (M5) of the embodiment, the balance of characteristics is adjusted by controlling the content ratio of Cr according to the content ratio of ferrite forming elements (Mo, W, Nb, V, etc.). is doing.

Mo (molybdenum) [(M1) ... 0, (M2), (M3) ... 0.80 to 1.10, (M4), (M5) ... 0.50 to 0.80]
Mo is a component that contributes to solid solution strengthening and is a constituent element of carbonitride that contributes to precipitation strengthening. Mo is a constituent element of the precipitate which is precipitated when the heat treatment is performed for a long time in a high temperature environment. In the nozzle plates (M2) to (M5) of the embodiment, when the Mo content is less than the lower limit of the above range, it becomes difficult to maintain a high amount of Mo that contributes to solid solution strengthening for a long period of time. .. When the Mo content exceeds the upper limit of the above range, the toughness is lowered and the formation of ferrite is promoted. Therefore, in the nozzle plates (M2) to (M5) of the embodiment, the Mo content is within the above range. Since the nozzle plates (M4) and (M5) of the embodiment have a large content ratio of the W (tungsten) component, the nozzle plates (M2) and (M2), ( The Mo content ratio is smaller than in the case of M3).

-V (vanadium) [(M1) ... 0, (M2) to (M5) ... 0.15 to 0.25]
V is a component that contributes to solid solution strengthening and a component that contributes to the formation of fine carbonitrides. In the nozzle plates (M2) to (M5) of the embodiment, when the content of V is less than the lower limit of the above range, the above-mentioned actions and effects are not sufficient. When the content of V exceeds the upper limit of the above range, a decrease in toughness occurs. Therefore, in the nozzle plates (M2) to (M5) of the embodiment, the V content is within the above range.

W (tungsten) [(M1), (M2) ... 0, (M3) ... 0.80 to 1.10, (M4), (M5) ... 1.60 to 1.90]
W is a component that contributes to solid solution strengthening and is a constituent element of carbonitride that contributes to precipitation strengthening. W can significantly enhance the high temperature stability of the precipitate, especially when added in combination with Mo. W becomes a constituent element of the precipitate when the heat treatment is performed for a long time in a high temperature environment. In the nozzle plates (M3), (M4), and (M5) of the embodiment, when the W content is less than the lower limit of the above range, the amount of W that contributes to solid solution strengthening is maintained high for a long period of time. Becomes difficult. When the W content exceeds the upper limit of the above range, the toughness is lowered and the formation of ferrite is promoted. Therefore, in the nozzle plates (M3), (M4), and (M5) of the embodiment, the W content is within the above range. In the nozzle plates (M4) and (M5), the W content ratio is larger than that in the case of the nozzle plate (M3), so that even better high temperature characteristics can be realized, as described above. In order to suppress the formation of ferrite, the Mo content ratio is smaller than that in the case of the nozzle plate (M3).

Nb (niobium) [(M1) ... 0, (M2) ... 0.05 to 0.20, (M3) ... 0.05 to 0.10, (M4), (M5) ... 0.015 to 0. 025]
Nb is a component that contributes to solid solution strengthening and also contributes to the formation of fine carbonitrides. In the nozzle plates (M2) to (M5) of the embodiment, when the content of Nb is less than the lower limit of the above range, the above-mentioned actions and effects are not sufficient. When the Nb content exceeds the upper limit of the above range, the amount of coarse Nb carbonitride produced increases. Therefore, in the nozzle plates (M2) to (M5) of the embodiment, the content rate of Nb is within the above range. In the nozzle plates (M4) and (M5), the W content is large and the amount of coarse Nb carbonitride produced tends to increase. Therefore, the Nb component is higher than in the nozzle plates (M2) and (M3). Content ratio is small.

-Co (cobalt) [(M1), (M2), (M3) ... 0, (M4), (M5) ... 1.0 to 3.0]
Co is a component that contributes to the effect of suppressing the formation of ferrite. In the nozzle plates (M4) and (M5) of the embodiment, when the Co content is less than the lower limit of the above range, the above-mentioned actions and effects are not sufficient. When the Co content exceeds the upper limit of the above range, the precipitation of the intermetallic compound is promoted and the creep strength is lowered. Therefore, in the nozzle plates (M4) and (M5) of the embodiment, the Co content is within the above range.

N (nitrogen) [(M1) to (M5) ... 0.01 to 0.03]
N is a component that contributes to precipitation strengthening by forming a nitride or a carbonitride. Furthermore, N remaining in the matrix also contributes to solid solution strengthening. N is dissolved and absorbed in the nozzle plate, for example, when casting is performed in the atmosphere. In the nozzle plates (M1) to (M5) of the embodiment, when the content of N is less than the lower limit of the above range, the amount of carbonitride produced by the heat treatment for tempering is small, which is sufficient. It disappears. When the N content exceeds the upper limit of the above range, the roughening of the nitride is promoted and the precipitation strengthening action is lowered. Therefore, in the nozzle plates (M1) to (M5) of the embodiment, the content of N is set within the above range.

B (boron) [(M1) to (M4) ... 0, (M5) ... 0.005 to 0.009]
B is a component that increases the deformation resistance near the grain boundaries and contributes to the improvement of the high temperature creep strength.
In the nozzle plate (M5) of the embodiment, when the content of B is less than the lower limit of the above range, the improvement of the high temperature creep strength is not sufficient. If the content of B exceeds the upper limit of the above range, cracks may occur during welding. Therefore, in the nozzle plate (M5) of the embodiment, the content of B is set within the above range.

Hereinafter, in the embodiment, a method for manufacturing the above nozzle plates (M1) to (M5) will be described.

In the present embodiment, first, a preparatory step for preparing a metal material formed by the electroslag redissolution method is performed. Here, the composition of the metal material formed by the electroslag remelting method is, in mass%, C: 0.10 to 0.15, Si: 0.60 or less, Mn: 0.60 or less, Ni: 0. It contains 60 or less, Cr: 12.0 to 14.0, and the balance consists of Fe and unavoidable impurities. In the electroslag remelting method, the consumable electrode is immersed in the molten slag and energized, the consumable electrode is redissolved by the Joule heat of the slag, and the droplets of molten steel that have passed through the molten slag are laminated in a water-cooled mold. The ingot, which is a metallic material, is obtained by solidifying the slag.

Next, a casting step of forming the nozzle plates (M1) to (M5) by casting is performed using the metal material prepared in the preparation step. Here, the metal material formed by the electroslag redissolving method is melted again. At this time, if necessary, a metal component is added so as to be each component of the nozzle plates (M1) to (M5) and melted to form a molten metal. Then, the nozzle plates (M1) to (M5) are formed by casting using the molten metal.

In the present embodiment, for example, the nozzle plates (M1) to (M5) are formed by casting in the atmosphere by a precision casting method. Specifically, a prototype is formed in the shape of the nozzle plate with wax. Next, a sand mold is produced by covering the periphery of the prototype with cast sand to harden it, and then dissolving and removing the wax. Next, the molten metal in which each component constituting the nozzle plate is melted is poured into a sand mold and then cooled to form nozzle plates (M1) to (M5) which are castings (cast steel).

After that, the nozzle plates (M1) to (M5) are subjected to a heat treatment for tempering. Here, as the tempering heat treatment, annealing, normalizing, quenching (cooling), and tempering are sequentially performed. Finally, the nozzle plates (M1) to (M5) are completed by performing a finishing process.

As described above, in the preparation step of the present embodiment, the metal material formed by the electroslag redissolving method is prepared. Therefore, the nozzle plates (M1) to (M5) have a small content of impurities and high homogeneity. That is, since scrap is not used in this embodiment, it is not necessary to analyze the content ratio of each component element and the content ratio of impurities contained in the scrap at the time of dissolution and adjust by refining or the like. Since the metal material manufactured by melting on a scale exceeding several tens of tons is used, the nozzle plates (M1) to (M5), which are cast products, are finally manufactured with stable quality. Further, in the present embodiment, since the composition of the metal material formed by the electroslag remelting method is the above-mentioned content ratio, the nozzle plates (M1) to (M5) can be efficiently manufactured. As described above, the nozzle plate manufacturing method according to the present embodiment has high manufacturing efficiency and can easily realize cost reduction. The reason why the composition of the metal material formed by the electroslag remelting method has the above-mentioned content ratio is that the metal material formed by the electroslag remelting method has the basic composition of the nozzle plates (M1) to (M5). Therefore, the nozzle plates (M1) to (M5) can be easily formed by adding reinforcing elements such as Mo, V, W, and Nb and diluting the amount of Cr. Because it will be possible to do it.

Further, as described above, in the casting process of the present embodiment, the nozzle plate is manufactured by the precision casting method, so that the manufacturing period can be shortened. For example, when a nozzle plate is manufactured by cutting a square lumber formed by forging or rolling, a manufacturing period of 7 to 9 months is required. On the other hand, when the nozzle plate is manufactured by the precision casting method, the manufacturing period is 2 to 3 months, and the manufacturing period can be effectively shortened.

Hereinafter, in the present embodiment, the steam turbine including the stationary blade row composed of the nozzle plate (static blade) will be described with reference to FIG. FIG. 1 shows a cross section along a vertical plane (yz plane).

As shown in FIG. 1, the steam turbine 1 is a rotary machine, and the turbine rotor 22 is configured to rotate by supplying steam as a working fluid. Here, the steam turbine 1 is an axial flow turbine, and steam flows with the horizontal direction y along the rotation axis AX of the turbine rotor 22 as the flow direction. The steam turbine 1 is a multi-stage type, and the turbine paragraphs composed of the moving blade 21 and the stationary blade 25 are arranged in a plurality of stages in the axial direction along the rotation axis AX, and steam is generated in each of the plurality of turbine paragraphs. Do the job. As a result, the turbine rotor 22 rotates in the steam turbine 1. The details of each part constituting the steam turbine 1 will be described below.

The casing 20 houses the turbine rotor 22 inside. One end of the turbine rotor 22 is connected to a generator (not shown), and the rotation of the turbine rotor 22 drives the generator (not shown) to generate electricity. The turbine rotor 22 is provided with a plurality of rotor disks 221 on the outer peripheral surface. A moving blade 21 is installed on the outer peripheral surface of the rotor disk 221 provided on the turbine rotor 22. A plurality of rotor blades 21 are arranged so as to surround the outer peripheral surface of the turbine rotor 22 so as to be spaced apart from each other in the circumferential direction R (rotational direction) of the turbine rotor 22 to form a rotor blade row. The moving blade row has a plurality of stages, and each of the plurality of stages of the moving blade row is arranged along the rotation axis AX of the turbine rotor 22.

A nozzle diaphragm 10 is installed inside the casing 20. The nozzle diaphragm 10 is composed of a diaphragm outer ring 23, a diaphragm inner ring 24, and a stationary blade 25. In the nozzle diaphragm 10, the diaphragm outer ring 23 is installed on the inner peripheral surface of the casing 20. The diaphragm inner ring 24 is installed inside the diaphragm outer ring 23 at a distance from the diaphragm outer ring 23. A plurality of stationary blades 25 are installed between the diaphragm outer ring 23 and the diaphragm inner ring 24.

Here, the plurality of stationary blades 25 are arranged at intervals in the circumferential direction R so as to surround the outer peripheral surface of the turbine rotor 22, and form a stationary blade row. Similar to the moving blade row, the stationary blade row is provided in a plurality of stages so that the stationary blade rows of the plurality of stages are arranged along the rotation axis AX of the turbine rotor 22.

In the steam turbine 1, a steam inlet pipe 28 penetrates the inlet of the casing 20, and steam is introduced into the casing 20 as a working fluid through the steam inlet pipe 28.

In the present embodiment, the stationary blade 25 is the nozzle plate described above, and is formed by using a nozzle plate corresponding to the operating temperature.

In addition to arranging the nozzle plates as the stationary blades 25 between the diaphragm outer ring 23 and the diaphragm inner ring 24, even if a plurality of nozzle plates are arranged as the stationary blades 25 in the casing 20 (turbine casing) in the circumferential direction R. good.

Hereinafter, the above-mentioned examples and comparative examples of the nozzle plate will be described with reference to Tables 1 to 4.

In Tables 1 to 4, P1 to P14 are examples, and C1 to C8 are comparative examples. Here, with respect to the nozzle plate (M1) whose composition does not contain a ferrite forming element other than the Cr element, the examples are P7 to P9, and the comparative examples are C1 and C2 (nozzle plate (M1). ) Consists of C, Si, Mn, Ni, Cr, N, Fe, and unavoidable impurities). Examples of the nozzle plate (M2) containing no W (tungsten) component in the composition are P4 to P6. A comparative example is C3 and C4 (the nozzle plate (M2) is composed of C, Si, Mn, Ni, Cr, Mo, V, Nb, N, Fe, and unavoidable impurities). Regarding the nozzle plate (M3) containing the (tungsten) component in the composition, Examples are P1 to P3, and Comparative Examples are C1 and C2 (the nozzle plate (M3) is C, Si, Mn, Ni, Cr, Mo, V, W, Nb, N, Fe, and unavoidable impurities). For the nozzle plate (M4) containing the Co (cobalt) component in the composition, Examples are P10 to P12. A comparative example is C7 (the nozzle plate (M4) is composed of C, Si, Mn, Ni, Cr, Mo, V, W, Nb, Co, N, Fe, and unavoidable impurities) Co (cobalt). ) And the boron (B) component in the composition of the nozzle plate (M5), Examples are P13 and P14, and Comparative Examples are C6 and C8 (Nozzle plate (M5) is C and Si. , Mn, Ni, Cr, Mo, V, W, Nb, Co, B, N, Fe, and unavoidable impurities).

[Making a nozzle plate]
First, in order to prepare the nozzle plate of each example, a metal material formed by the electroslag redissolving method was prepared. Here, a cylindrical round bar having the components shown in Table 1 and having a diameter of 100 mm was prepared as a metal material.

Next, using the prepared metal material, the nozzle plates of each example were formed by casting. Here, the metal material formed by the electroslag redissolving method was melted again. At this time, as shown in Table 2, a metal component was added and dissolved as necessary so as to be a component of the nozzle plate of each example. Then, by casting in the atmosphere, a nozzle plate-shaped casting was produced. In addition, in Table 2, the display of "<0.01" indicates that it is below the detection limit of the component analysis, and indicates that it exceeds 0.00% by mass and is less than 0.01% by mass. ..

Next, a tempering heat treatment was performed on the nozzle plate-shaped casting. Here, the nozzle plates of each example were produced by sequentially performing annealing, normalizing, quenching, and tempering as the tempering heat treatment. Annealing, normalizing, quenching, and tempering were performed under the conditions shown in Table 3. The nozzle plate of each example was manufactured so that the tensile strength at room temperature was about 700 MPa.

[test]
Table 4 shows the results of the tests performed on the nozzle plates of each example.

As shown in Table 4, the tensile strength at 500 ° C. (JIS Z 2241) and the creep rupture strength at 550 ° C. for 100,000 hours (JIS Z 2271) were determined for the nozzle plates of each example. Here, a tensile test was performed at 500 ° C. using a JIS No. 4 test piece. Thereby, the tensile strength at 500 ° C. was measured, and the "100,000-hour creep rupture strength at 550 ° C." was calculated from the measurement result of the creep rupture strength.

As shown in Table 4, the "welding work" test was performed on the nozzle plates of each example. The "welding work" test was carried out according to the following procedure. The tempered nozzle plate was processed into a flat plate having a plate thickness of 10 mm. Then, after preheating the flat plate to 250 ° C., a welding bead was applied to the flat plate using a 9% Cr welding rod in a gas shield environment in which Ar gas and CO ₂ gas were mixed. Then, it was confirmed whether or not cracks were generated in the vicinity of the welded portion of the flat plate. In Table 4, the case where cracks do not occur in the welded portion during welding is indicated by “◯”, and the case where cracks occur in the welded portion during welding is indicated by “x”.

Comparing the test results between P1 to P3 and C1 and C2, the "tensile strength at 500 ° C." is equivalent between the two. However, the "100,000-hour creep rupture strength" is higher in P1 to P3 than in C1. In the "welding work", P1 to P3 did not have cracks in the welded portion, but C2 had cracks in the welded portion. The content ratio of each component constituting P1 to P3 is different from the case of C1 and C2, and is within the range of the content ratio of each component constituting the nozzle plate (M3) described above. Therefore, P1 to P3 have excellent mechanical properties as described above.

Comparing the test results between P4 to P6 and C3 and C4, the "tensile strength at 500 ° C." is higher in P4 to P6 than in C3 and C4. Similarly, "100,000-hour creep rupture strength" is higher in P4 to P6 than in C3 and C4. In the "welding work", P4 to P6 had no cracks in the welded portion, but C3 had cracks in the welded portion. The content ratio of each component constituting P4 to P6 is different from the case of C3 and C4, and is within the range of the content ratio of each component constituting the nozzle plate (M2) described above. Therefore, P4 to P6 have excellent mechanical properties as described above.

Comparing the test results between P7 to P9 and C5, the "tensile strength at 500 ° C." is higher in P7 to P9 than in C5. Similarly, "100,000-hour creep rupture strength" is higher in P4 to P6 than in C5. In "welding work", P7 to P9 have no cracks in the welded portion. The content ratio of each component constituting P7 to P9 is within the range of the content ratio of each component constituting the nozzle plate (M1) described above, unlike the case of C5. Therefore, P7 to P9 have excellent mechanical properties as described above.

Comparing the test results between P10 to P12 and C7, the "tensile strength at 500 ° C." is similar to each other, but the "100,000-hour creep rupture strength" is higher for P10 to P12 than for C7. Is also expensive. In the "welding work", the welded portions of P10 to P12 are not cracked. The content ratio of each component constituting P10 to P12 is within the range of the content ratio of each component constituting the nozzle plate (M4) described above, unlike the case of C7. Therefore, P10 to P12 have excellent mechanical properties as described above.

Comparing the test results between P13 and P14 and C6 and C8, the "tensile strength at 500 ° C." and the "100,000-hour creep rupture strength" are similar to each other. However, in the "welding work", P13 and P14 have no cracks in the welded portion, but C6 and C8 have cracks in the welded portion. The content ratio of each component constituting P13 and P14 is different from the case of C6 and C8, and is within the range of the content ratio of each component constituting the nozzle plate (M5) described above. Therefore, P13 and P14 have excellent mechanical properties as described above.

From the above results, it can be seen that the nozzle plates (M1) to (M5) have excellent mechanical properties. That is, in the nozzle plates (M1) to (M5), the "tensile strength at 500 ° C." and the "100,000-hour creep rupture strength" are sufficiently high, and the welded portion does not crack in the "welding work". It turns out.

Although some 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 embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... steam turbine, 10 ... nozzle diaphragm, 20 ... casing, 21 ... moving blade, 22 ... turbine rotor, 221 ... rotor disk, 23 ... diaphragm outer ring, 24 ... diaphragm inner ring, 25 ... stationary blade (nozzle plate), 28 ... Steam inlet pipe, AX ... Rotating shaft

Claims (5)

By the electroslag redissolution method, the composition is by mass%.
C: 0.10 to 0.15,
Si: 0.60 or less,
Mn: 0.60 or less,
Ni: 0.60 or less,
Cr: 12.0-14.0
Contains,
A preparatory step to prepare a metallic material formed so that the balance consists of Fe and unavoidable impurities.
In the state where the prepared metal material was melted again, the composition was, by mass%.
C: 0.10 to 0.15,
Si: 0.60 or less,
Mn: 0.60 or less,
Ni: 0.60 or less,
Cr: 12.0 to 14.0,
N: 0.01-0.03
Contains,
It has a casting process in which a molten metal is formed by adding a metal component and melting so that the balance is composed of Fe and unavoidable impurities, and the nozzle plate of a steam turbine is cast using the molten metal .
How to manufacture a nozzle plate for a steam turbine. By the electroslag redissolution method, the composition is by mass%.
C: 0.10 to 0.15,
Si: 0.60 or less,
Mn: 0.60 or less,
Ni: 0.60 or less,
Cr: 12.0-14.0
Contains,
A preparatory step to prepare a metallic material formed so that the balance consists of Fe and unavoidable impurities.
In the state where the prepared metal material was melted again, the composition was, by mass%.
C: 0.10 to 0.15,
Si: 0.60 or less,
Mn: 0.40 to 0.60,
Ni: 0.60 or less,
Cr: 10.0 to 11.5,
Mo: 0.80 to 1.10,
V: 0.15 to 0.25,
Nb: 0.05 to 0.20
N: 0.01-0.03
Contains,
It has a casting process in which a molten metal is formed by adding a metal component and melting so that the balance is composed of Fe and unavoidable impurities, and the nozzle plate of a steam turbine is cast using the molten metal.
How to manufacture a nozzle plate for a steam turbine. By the electroslag redissolution method, the composition is by mass%.
C: 0.10 to 0.15,
Si: 0.60 or less,
Mn: 0.60 or less,
Ni: 0.60 or less,
Cr: 12.0-14.0
Contains,
A preparatory step to prepare a metallic material formed so that the balance consists of Fe and unavoidable impurities.
In the state where the prepared metal material was melted again, the composition was, by mass%.
C: 0.10 to 0.15,
Si: 0.60 or less,
Mn: 0.40 to 0.60,
Ni: 0.60 or less,
Cr: 9.2 to 10.2,
Mo: 0.80 to 1.10,
V: 0.15 to 0.25,
W: 0.80 to 1.10,
Nb: 0.05 to 0.10,
N: 0.01-0.03
Contains,
It has a casting process in which a molten metal is formed by adding a metal component and melting so that the balance is composed of Fe and unavoidable impurities, and the nozzle plate of a steam turbine is cast using the molten metal.
How to manufacture a nozzle plate for a steam turbine. By the electroslag redissolution method, the composition is by mass%.
C: 0.10 to 0.15,
Si: 0.60 or less,
Mn: 0.60 or less,
Ni: 0.60 or less,
Cr: 12.0-14.0
Contains,
A preparatory step to prepare a metallic material formed so that the balance consists of Fe and unavoidable impurities.
In the state where the prepared metal material was melted again, the composition was, by mass%.
C: 0.10 to 0.15,
Si: 0.30 or less,
Mn: 0.40 to 0.60,
Ni: 0.30 or less,
Cr: 9.0 to 10.5,
Mo: 0.50 to 0.80,
V: 0.15 to 0.25,
W: 1.60 to 1.90,
Nb: 0.015 to 0.025,
Co: 1.0-3.0,
N: 0.01-0.03
Contains,
It has a casting process in which a molten metal is formed by adding a metal component and melting so that the balance is composed of Fe and unavoidable impurities, and the nozzle plate of a steam turbine is cast using the molten metal.
How to manufacture a nozzle plate for a steam turbine. By the electroslag redissolution method, the composition is by mass%.
C: 0.10 to 0.15,
Si: 0.60 or less,
Mn: 0.60 or less,
Ni: 0.60 or less,
Cr: 12.0-14.0
Contains,
A preparatory step to prepare a metallic material formed so that the balance consists of Fe and unavoidable impurities.
In the state where the prepared metal material was melted again, the composition was, by mass%.
C: 0.10 to 0.15,
Si: 0.30 or less,
Mn: 0.40 to 0.60,
Ni: 0.30 or less,
Cr: 9.0 to 10.5,
Mo: 0.50 to 0.80,
V: 0.15 to 0.25,
W: 1.60 to 1.90,
Nb: 0.015 to 0.025,
Co: 1.0-3.0,
B: 0.005 to 0.009
N: 0.01-0.03
Contains,
It has a casting process in which a molten metal is formed by adding a metal component and melting so that the balance is composed of Fe and unavoidable impurities, and the nozzle plate of a steam turbine is cast using the molten metal.
How to manufacture a nozzle plate for a steam turbine.

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