JP2003311404A - Sealing welding method for turbine blade core support hole and turbine blade - Google Patents

Abstract

(57) An object of the present invention is to prevent welding defects caused by fluctuations in blade wall thickness when sealing and welding a core support hole formed in a turbine blade made of a nickel-base heat-resistant alloy. In a sealing welding method for a core support hole of a turbine blade formed of a nickel-base heat-resistant alloy, the core support portion is removed before the core elution step of the precisely cast turbine blade. And, after the hole is sealed with a weld metal, pattern processing is performed to transfer a predetermined overlay shape to the weld metal. Sealing welding is performed by supplying a filler material made of a nickel-based alloy. [Effect] Turbine blade manufacturing yield and blade reliability are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine blade formed of a nickel-base heat-resistant alloy, and more particularly to a core support portion remaining on the surface of the turbine blade when the turbine blade is manufactured by precision casting using a core. A method for sealing and welding.
The present invention relates to a method for sealing and welding a gas turbine blade core supporting hole, which is suitable for suppressing high temperature cracking due to welding and suppressing strain age cracking in a heat treatment process after welding and has a high yield.

[0002]

2. Description of the Related Art A gas turbine blade used in a high temperature environment is generally manufactured by precision casting using a nickel-base heat resistant alloy. At this time, a method of providing a complicated cooling passage for cooling with a refrigerant such as air is used inside the blade. This cooling passage is formed by using a core during casting. The core is eluted and removed by the chemicals after casting, but since the support portion of the core remains in the cast blade as a support hole, it is necessary to seal this support hole to obtain a product.

An arc welding method using a filler material is used as a method for sealing the core support hole, but the nickel-base heat-resistant alloy forming the turbine blade is added with Al.
Due to the influence of strengthening elements such as Ti and Ti, cracks are likely to occur during welding due to the decrease in the strength of the crystal grain boundaries. For this reason, a welding method for suppressing this welding crack is described in JP-A-1-107973. In this method, by using a nickel-based or iron-based alloy, which is more ductile than the wing material, as the filler metal for sealing welding, the composition of the weld metal is adjusted and the effect of the strengthening elements contained in the wing material is adjusted. It was suppressed to make cracks less likely to occur.

However, in the arc welding method described in the above publication, since the heat input during welding is large, the volume of the weld metal formed tends to become larger than necessary relative to the core supporting hole to be sealed. is there. Since the weld metal is adjusted in composition by the filler metal, cracks during welding are less likely to occur, but since the characteristics such as high temperature strength are inferior to the blade material, excessive weld metal causes deterioration of turbine blade performance. .

In addition, when there is a heat treatment process such as an aging heat treatment after the sealing welding, even in the weld metal which did not crack during welding, due to the lack of ductility of the weld metal in the process of relaxing the strain caused by welding. This may cause cracking, which is a factor that reduces the yield of products.
The cracks generated during this heat treatment are also considered to be due to the strengthening elements such as Al and Ti dissolved in the weld metal from the blade material, and in order to suppress the cracks, the proportion of the blade material component contained in the weld metal is reduced. That is, it is necessary to reduce the melting amount of the blade material during welding.

As a method for solving this problem, a filler material formed into a predetermined shape is arranged in advance so as to close the core support hole, and a laser or an arc is focused on the filler material to preferentially heat the filler material. A welding method that seals the support holes while suppressing the melting amount of the blade material by melting is effective. According to this method, not only the low-strength weld metal that reduces blade performance can be reduced, but also cracks during welding and cracks during aging heat treatment can be significantly suppressed.

[0007]

SUMMARY OF THE INVENTION In the above prior art,
It is necessary to select appropriate welding conditions and perform the construction depending on the wall thickness of the blade around the core support hole where the sealing welding is performed.
If the welding is carried out under welding conditions out of the proper range, excessive melting may cause dripping of the weld metal, or conversely, insufficient welding or insufficient welding such as undercut. Turbine blades manufactured by casting have different wall thicknesses for each blade due to variations in the core position and for each core support hole position. It is necessary to measure the wall thickness of the hole and change the welding conditions, which causes a decrease in construction efficiency.

The present invention has been made in view of the above circumstances. After the precision casting, the core supporting portion is bored before the core is eluted from the roughened turbine blade. ,
While removing the core support part and shaping the side surface of the support hole, a hollow pattern is formed on the core of the bottom part of the support hole to transfer the desired shape to the extra metal of the weld metal. By performing the sealing welding used, it is possible to prevent the weld metal from dripping so that a predetermined extra-height shape can always be obtained. An object of the present invention is to provide a method for sealing and welding a blade core support hole, and a turbine blade using this method.

[0009]

The present invention has the following features to attain the object mentioned above.

That is, in the first method of sealing welding of the core support hole of the turbine blade, the portion supporting the core is removed before the core is eluted from the precision cast turbine blade. Performing hole processing, further removing the surface of the core located in the lower portion of the hole, to form a pattern for transferring a predetermined swelling shape to the weld metal that seals the hole, then,
A filler material made of a nickel-based alloy is supplied to the hole and sealing welding is performed.

In the second method, there is a core support portion at the top of the turbine blade, and in the method of sealing welding of the hole of the turbine blade, the core support portion remains as a hole, the core is removed from the turbine blade. Prior to elution and removal, a hole is formed by removing the core support part to form a hole, and a predetermined extra-height shape is transferred to the weld metal that seals the hole in the core located below the hole. A pattern for forming the pattern is formed, and then a filler material made of a nickel-based alloy is supplied to the hole to perform sealing welding.

In the first and second methods, the weld metal surplus shape transferred by the pattern processed on the core located at the lower portion of the hole has a ratio of the surplus height to the diameter of the surplus metal. It is desirable that the spherical shape is 1/10 to 1/2.

In the sealing welding method of the present invention, a sealing member as the filler material is arranged in the support hole before welding.

As a concrete method of the sealing welding, a method of sealing by laser welding while suppressing the oxidation of the welding portion by an inert gas, and a sealing by TIG welding while suppressing the oxidation of the welding portion by an inert gas. The method of sealing, the method of sealing by plasma welding while suppressing the oxidation of the welded portion by an inert gas, or the method of sealing by electron beam welding is preferable.

According to the turbine blade of the present invention, in a turbine blade in which a core support portion formed during precision casting remains as a hole, the hole is sealed by welding, and the welded metal blade seals the hole. It is characterized in that it has a bulge on the inner surface side, and the bulge is formed by transferring the pattern formed on the core remaining inside the blade after precision casting. It is preferable that the extra reinforcement has a spherical shape, and the ratio of the extra elevation to the diameter of the extra protrusion is 1/10 to 1/2.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] A first embodiment of a core support hole sealing welding method for a turbine blade according to the present invention will be described with reference to FIG.
From now on, description will be made with reference to FIG. 7.

As shown in FIGS. 1 to 4, the method of sealing welding of the turbine blade core support hole of the present embodiment is arranged on the blade top portion 10 of the turbine blade 1 formed of a nickel-base heat-resistant alloy. A sealing member 3 formed of a nickel-based alloy having a ductility superior to that of the nickel-based heat-resistant alloy is arranged in the child support hole 2, and the surface of the sealing member 3 is irradiated with a laser beam for sealing. The member 3 and the blade material around the core support hole 2 are melted and sealed and welded, and the process is roughly completed through the following steps.

First, as a first step, a core support hole 2 arranged at a blade top 10 is provided for a turbine blade 1 which has been formed by precision casting, then rough-processed and optionally heat-treated. It is shaped as shown in FIG. This core support hole was used as a core support portion before drilling. The ceramic that has formed the core support portion is removed to form the core support hole 2, and a part of the surface of the core 4 at the bottom of the core support hole 2 is removed. The removed portion becomes extra when the core support hole 2 is sealed with weld metal. The shape of the weld metal swell is preferably spherical, and therefore it is desirable to provide the spherical swell pattern 5 when removing the surface of the core 4. In this embodiment, the ratio of the height h of the extra deposit to the diameter d of the extra deposit is about 1 /.
The shape of the pattern 5 was controlled so as to be 6. It is desirable that the shaping process of the core support hole 2 and the process of giving the extra pattern 5 to the core 4 be performed at the same time by one processing tool, but after the core support hole 2 is processed, another process is performed. The extra pattern 5 may be processed by the above-mentioned processing tool. Further, in this embodiment, as shown in FIG. 2, the core support hole 2 is formed in a tapered shape, but it may be formed in a straight hole shape.

In the second step, as shown in FIG. 3, the sealing member 3 is arranged in the core supporting hole 2 shaped in the first step, and if necessary, temporary attachment is performed by percussion welding or the like. It is desirable that the volume of the sealing member 3 be 1.5 to 3 times as large as the volume of the core supporting hole 2 to be sealed on the design value. By changing the volume of the sealing member 3, it is possible to adjust the amount of excess metal on the surface side of the weld metal. In this embodiment, the sealing member 3 having a volume 1.8 times as large as the design value of the core support hole 2 was used. If the shape of the sealing member 3 is shaped so as to fit with the core support hole 2, the arrangement becomes easy.

Next, in the third step, as shown in FIG. 3, the laser 6 is sealed by the inert gas flow 8 ejected from the laser torch 14 while the sealing weld is shielded from the outer surface of the blade. Sealing and welding is performed by irradiating and melting the wing material around the core support hole 2 at the same time by heat conduction. By performing a down-slope process that gradually reduces the laser output at the end of welding, it is possible to suppress the shrinkage 9 that occurs in the extra metal on the outer surface side of the blade of the weld metal 7 shown in FIG. If the shrinkage 9 is not sufficiently suppressed even if the downslope treatment is performed, the shrinkage 9 can be reduced by remelting only the upper portion of the weld metal 7 with a smaller heat input than that in the sealing welding. It is valid.
Although the YAG laser is used as the laser in this embodiment, similar welding can be performed by using a semiconductor laser or a CO ₂ laser.

In the fourth step, after inspecting the seal welding portion from the outer surface of the blade, heat treatment is applied to the turbine blade if necessary.

In the final fifth step, after the core inside the turbine blade is eluted, the sealing welds are inspected from the blade outer surface and inner surface side to confirm that there is no problem.

In this embodiment, the material of the turbine blade 1 is carbon (C) 0.07, chromium (Cr) 7.1, cobalt (Co) 1.0, molybdenum (Mo) 0.8, in weight%. Tungsten (W) 8.8, Niobium (Nb) 0.8, Aluminum (Al) 5.1, Boron (B) 0.02, Tantalum (Ta) 8.9, Hafnium (Hf) 0.25, Rhenium ( Re) 3.0, nickel-based heat-resistant alloy single crystal material having the composition of the balance nickel (Ni), and the material of the sealing member 3 is carbon (C) 0.05, manganese (M) in% by weight.
n) 0.25, iron (Fe) 2.5, silicon (Si) 0.2.
25, chromium (Cr) 21.5, molybdenum (Mo) 9.
0, aluminum (Al) 0.2, titanium (Ti) 0.
2. The total of niobium (Nb) and tantalum (Ta) is 3.6.
5, nickel (Ni) 61.0, and the balance unavoidable impurities, a nickel-based alloy having the composition shown in Table 1
By using the condition selected from the welding condition range shown in, the wall thickness of the blade tip 10 of the turbine blade 1 is 1.2 to 1.8.
Even if there are variations in the range of mm, it is possible to carry out the work under constant welding conditions, the outer and inner surfaces of the sealing welded part have a good bulge shape, and there is a sound seal with no weld cracks or heat treatment cracks. Stop welding was realized.

[0024]

[Table 1]

In this embodiment, from the viewpoint of preventing weld cracking and heat treatment cracking, a laser having excellent convergence and controllability was used as a heat source for welding in order to suppress the amount of melting of the blade material in the sealing welding. Seal welding can be similarly performed even for electron beams having similar heat source characteristics.

[Second Embodiment] As shown in FIGS. 1 and 5 to 7, a turbine blade core support hole sealing welding method according to a second embodiment is a turbine formed of a nickel-base heat-resistant alloy. In the core support hole 2 arranged on the wing top portion 10 of the wing 1,
A sealing member 3 formed of a nickel-based alloy having a higher ductility than the nickel-based heat-resistant alloy is arranged, and the sealing member 3 and the wing material around the core support hole 2 are melted and sealed by TIG welding. Welding is performed, and the process is roughly completed through the following steps.

First, as a first step, a core support hole 2 arranged at a blade top portion 10 is provided for a turbine blade 1 which has been formed by precision casting, then rough-processed, and optionally heat-treated. It is shaped as shown in FIG. At this time, as in the first embodiment, the core support portion is removed during shaping of the core support hole 2, and a predetermined amount of extra weld metal is provided on the core 4 at the bottom of the core support hole 2. A spherical extra pattern 5 for transferring the shape is applied. In the present embodiment, the shape of the extra pattern 5 was controlled so that the ratio of the extra height h to the extra diameter d was about 1/5. The shaping process of the core support hole 2 and the process of giving the extra pattern 5 to the core 4 are
It was performed at the same time as the shaping of the core support hole 2 with one processing tool. Further, in this embodiment, as shown in FIG. 5, the core support hole 2 was shaped into a straight hole shape. Of course, the core support hole 2 may have a taper as in the first embodiment.

In the second step, as shown in FIG. 6, a cylindrical sealing member 3 was placed in the core supporting hole so as to fit into the core supporting hole 2 shaped in the first step. Further, in this embodiment, the volume of the sealing member 3 is twice as large as the volume of the core supporting hole 2 to be sealed in terms of the designed value.

Next, in the third step, as shown in FIG.
While shielding the sealed weld from the outer surface of the blade by the inert gas flow 8 ejected from the G torch 15, the arc 11
Is generated between the welding electrode 12 and the sealing member 3, the sealing member 3 is melted, and the core supporting hole 2 is formed by heat conduction.
Sealing welding is performed by simultaneously melting the surrounding area.

In the present embodiment, the energy from the arc is selectively applied to the sealing member 3 to suppress the amount of melting of the blade material. Therefore, as shown in FIG. The disk-shaped arc mask 13 with holes is used as the core support hole 2
The upper surface of the blade around the support hole was masked. Alumina is used for the arc mask 13, but other heat-resistant non-conductors may be used, or the heat-resistant non-conductor and the high melting point metal may be laminated or stacked. The diameter of the hole provided in the center of the arc mask 13 is preferably larger than the diameter of the core support hole 2 on the outer surface side of the blade by about 0.5 to 2.0 mm.

Further, by performing the down-slope treatment for gradually reducing the welding output at the end of welding, it is possible to suppress the shrinkage 9 that occurs in the excess on the outer surface side of the blade of the weld metal 7 shown in FIG. . Even if downslope processing is performed, it is closed.
Is not sufficiently suppressed, it is also effective to reduce the shrinkage 9 by remelting only the upper portion of the weld metal 7 with a smaller heat input than in the sealing welding.

In the fourth step and the fifth step, as in the first embodiment, the inspection and heat treatment of the sealing weld are carried out.

In this embodiment, the turbine blade 1 is made of carbon (C) 0.07, chromium (Cr) 6.0, cobalt (Co) 9.0, molybdenum (Mo) 0.5, in weight%. Tungsten (W) 8.0, Aluminum (Al) 5.7,
Nickel having a composition of titanium (Ti) 0.7, boron (B) 0.015, tantalum (Ta) 3.0, hafnium (Hf) 1.4, rhenium (Re) 3.0, and the balance nickel (Ni). The base heat-resistant alloy is a unidirectionally solidified material, and the material of the sealing member 3 is carbon (C) of 0.
05, manganese (Mn) 0.25, iron (Fe) 2.5, silicon (Si) 0.25, chromium (Cr) 21.5, molybdenum (Mo) 9.0, aluminum (Al) 0.2. Titanium (Ti) 0.2, Niobium (Nb) and Tantalum (T
In the case of a nickel-based alloy having a composition of a) total of 3.65, nickel (Ni) 61.0, and the balance unavoidable impurities, use the conditions selected from the welding condition range shown in Table 2. Therefore, even if the thickness of the blade tip portion 10 of the turbine blade 1 varies in the range of 1.2 to 1.8 mm, it is possible to carry out the construction under constant welding conditions, and The surplus shape was good, and sound sealing welding without welding cracks or heat treatment cracks was realized.

[0034]

[Table 2]

In the present embodiment, from the viewpoint of preventing weld cracking and heat treatment cracking, in order to suppress the melting amount of the blade material in the sealing welding, the sealing welding was performed by combining TIG welding and an arc mask. Even when plasma is used as the heat source, good sealing welding can be similarly performed by combining with the arc mask.

In the above two examples, the sealing welding method of the core supporting hole of the turbine blade blade top formed by the nickel-base heat-resistant alloy single crystal material and the unidirectionally solidified material was shown. It may be applied to the sealing of core support holes, cooling holes, etc. formed in the part. Further, the method for sealing and welding the turbine blade core support hole according to the present invention is a turbine formed of a nickel-base heat-resistant alloy single crystal material or a unidirectionally solidified material other than the nickel-base heat-resistant alloy described in the present embodiment. It is also suitable for sealing welding of blade core support holes.

[0037]

According to the present invention, a filler metal is used in sealing welding of a core supporting hole of a turbine blade formed of a nickel-base heat-resistant alloy, particularly a core supporting hole arranged at the top of the blade. When sealing and welding the core support hole, by transferring the extra-height pattern previously formed on the core inside the blade,
The extra-height shape of the weld metal on the inner surface side of the blade can be made substantially constant, and it is possible to reduce welding defects due to variations in the wall thickness of the blade.

Further, the extra-height shape of the weld metal on the inner surface side of the blade is
By controlling the ratio of the height of the extra deposit to the diameter of the extra deposit to be in the range of 1/10 to 1/2, residual stress generated by welding is dispersed, and welding cracks and heat treatment that are likely to occur in the extra portion. It is possible to reduce cracking.

As the filler material used for the sealing welding,
Place the sealing member in the core support hole in advance,
By performing the sealing welding, the proportion of the blade material melted by the welding can be reduced, and cracking of the weld metal caused by the strengthening element contained in the blade material can be suppressed.

A laser is used as a welding heat source for the sealing welding.
By using arc, plasma or electron beam to preferentially input energy to the filler metal, the ratio of the blade material melted by welding can be reduced, cracks of the weld metal can be suppressed, and the weld metal can be suppressed. Since the size of the gas turbine blade is suppressed to be small, the decrease in strength of the gas turbine blade due to the sealed weld is suppressed.

Due to these effects, the yield at the time of manufacturing the turbine blade is improved, the deterioration of the blade performance due to welding is suppressed, and the blade life can be extended.

[Brief description of drawings]

FIG. 1 is a perspective view of a turbine blade having a core support hole at a blade top.

FIG. 2 is a diagram illustrating an embodiment of a method for sealing and welding a turbine blade core support hole according to the present invention, in which a core support portion is removed and a core support hole and a core that have been subjected to a tapered shaping process are provided. FIG. 6 is a cross-sectional view showing the shape of the formed extra-height pattern in the vicinity of the blade top core support hole.

FIG. 3 shows a schematic configuration in the case where a sealing member is arranged in a core support hole and sealing is performed by laser welding in an embodiment of a method for sealing and welding a turbine blade core support hole according to the present invention. FIG. 3 is a cross-sectional view of the vicinity of a blade top core support hole.

FIG. 4 shows a state after a sealing member is arranged in the core support hole and sealing is performed by laser welding in the embodiment of the method for sealing and welding the turbine blade core support hole according to the present invention. FIG. 3 is a cross-sectional view of the vicinity of a blade top core support hole.

FIG. 5 is a diagram illustrating an embodiment of a method for sealing and welding a turbine blade core support hole according to the present invention, in which a core support portion is removed, and a core support hole that has been subjected to shaping processing and a margin formed in the core. FIG. 6 is a cross-sectional view showing the shape of a pattern of a mound in the vicinity of a blade top core support hole.

FIG. 6 shows a schematic configuration in the case where a sealing member is arranged in the core support hole and sealing is performed by TIG welding in the embodiment of the method for sealing and welding the turbine blade core support hole according to the present invention. FIG. 3 is a cross-sectional view of the vicinity of a blade top core support hole.

FIG. 7 is a cross-sectional view in the vicinity of a blade top core support hole showing a state after performing sealing by TIG welding in an embodiment of a method for sealing and welding a turbine blade core support hole according to the present invention. .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Turbine blade, 2 ... Core support hole, 3 ... Sealing member, 4
... core, 5 ... extra pattern, 6 ... laser, 7 ... weld metal, 8 ... inert gas flow, 9 ... shrinkage, 10 ... blade top, 11
... arc, 12 ... welding electrode, 13 ... arc mask, 14
… Laser torch, 15… TIG torch.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B23K 103: 08 B23K 103: 08 F term (reference) 4E001 BB07 BB11 CB03 CC04 DC04 DD01 DG01 4E066 CA18 CB06 4E068 BA06 CH08 CJ01 DB02 4E081 AA05 BA08 DA13 YG03

Claims (10)

[Claims] 1. A method for sealing and welding a core support hole of a turbine blade, which is made of a nickel-base heat-resistant alloy and is precision-cast,
Before the core is eluted from the turbine blade, the core support is removed to make a hole, and a part of the core located at the lower part of the hole is removed to seal the hole with a predetermined metal. Sealing welding of a turbine blade core support hole, characterized in that a pattern for transferring the extra-height shape is formed, and then a filler material made of a nickel-based alloy is supplied to the hole to perform sealing welding. Method. 2. A method of sealing and welding a core support hole of a precision-cast turbine blade, which is made of a nickel-base heat-resistant alloy, in which a core used during precision casting of the turbine blade is eluted and removed. Before removing the core, a portion supporting the core is removed to make a hole, and a part of the surface of the core located at the lower portion of the hole is removed to remove a predetermined amount from the weld metal for sealing the hole. Sealing welding of a turbine blade core support hole, characterized in that a pattern for transferring the extra-height shape is formed, and then a filler material made of a nickel-based alloy is supplied to the hole to perform sealing welding. Method. 3. The reinforcement shape of the weld metal transferred by the pattern machined to the core located in the lower portion of the hole according to claim 1 or 2, wherein the ratio of the height of the reinforcement to the diameter of the reinforcement is A sealing welding method for a turbine blade core support hole, which has a spherical shape of 1/10 to 1/2. 4. The method for sealing and welding a turbine blade core supporting hole according to claim 1, wherein the filler material is a sealing member arranged in the hole before welding. 5. The method according to any one of claims 1 to 4,
The sealing welding of a turbine blade core support hole is characterized in that the sealing welding is performed by laser welding while suppressing oxidation of the welded portion by an inert gas. 6. The turbine blade core support hole according to any one of claims 1 to 4, wherein the sealing welding is performed by TIG welding while suppressing oxidation of the welded portion by an inert gas. Sealing welding method. 7. The turbine blade core support hole according to any one of claims 1 to 4, wherein the sealing welding is performed by plasma welding while suppressing oxidation of the welded portion by an inert gas. Sealing welding method. 8. The method according to any one of claims 1 to 4,
A sealing welding method for a turbine blade core support hole, wherein the sealing welding is performed by electron beam welding. 9. A turbine blade made of a nickel-base heat-resistant alloy in which a core supporting portion formed during precision casting remains, and a hole formed by removing the core supporting portion is sealed by welding. The weld metal that seals the hole has a bulge on the inner surface side of the blade, and the bulge is formed by transferring the pattern formed on the core remaining inside the blade after precision casting. Turbine blade characterized by that. 10. The ridge according to claim 9, wherein the sphere has a spherical shape, and the ratio of the height of the sphere to the diameter of the sphere is 1/10 to 10.
Turbine blade characterized by being 1/2.