JPH01107973A - How to make wings - Google Patents

Abstract

PURPOSE:To prevent a defect generated at welding time and to improve the performance of a product by monocrystalizing a blade, subjecting to a heat treatment after welding by dividing it and welding it by setting such welding conditions as causing no welding defect after welding in manufacturing the welding structural blade consisting of a Ni base alloy. CONSTITUTION:The core supporting hole 2 provided at the tip part of a blade is joined by sealing it in order to facilitate support and melt-through of the core of the blade of complicated cooling structure consisting of a Ni base alloy. Or after welding said blade tip part by dividing it in the state of like horizontally splitting it the cap of the blade tip is integrated by welding it to the blade. The material is of a monocrystal or similar to that and a filler rod of Fe or Ni is used and welded under inert atmosphere or vacuum to prevent the welding crack caused by a grain boundary. The split welding is thus enabled in case of welding the blade having a complicated cooling hole, the defect generated at welding time is prevented and the product performance can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a blade using a Ni-based superalloy heat-resistant material, and particularly relates to a method for manufacturing a blade using a heat-resistant Ni-based superalloy material, and in particular, a method for manufacturing a blade using a heat-resistant Ni-based superalloy material. , relates to a method of manufacturing a wing suitable for achieving a structure by welding.

[Conventional technology]

Traditionally, fusion welding of superalloy materials is associated with carbide precipitation;
This was not done at all because cracks frequently occurred in the weld heat-affected zone. Therefore, all turbine blades and the like are manufactured using the integral casting method.

However, in order to improve the performance of the product, it is necessary to provide a large number of cooling holes inside the blade and cool the blade while flowing cooling fluid, thereby improving the cooling performance. There is a limit to how many cooling holes (complex cooling holes) can be created. Therefore, it is necessary to create a large casting hole at the tip of the blade. In order to commercialize the product, it has been necessary to either close it up or make a cap by dividing the area around the tip of the wing and connect it to the main body. Arc welding is the most effective method for sealing and connecting the casting hole in terms of productivity, etc., but conventional methods cannot prevent cracks that occur in the weld heat-affected zone with melted materials. Therefore, brazing method or diffusion bonding method is generally applied.

However, it is inefficient in terms of productivity.

[Problem that the invention seeks to solve]

The blades manufactured using the conventional technology did not have any performance problems even if they did not have a complicated structure, so they could be manufactured by integral casting, and there was no need for connections. However, attempts were made to repair part of the damaged wing by welding, but the weld heat-affected zone suffered from frequent cracks, and it was considered impossible to apply the arc welding method.

Recently, there has also been a movement to improve the cooling performance of the blade by installing a large number of complex cooling holes inside the blade, thereby improving product performance. In that case, there are two methods: enlarging the casting hole, installing a closing plate in that part after melting, and sealing it by welding, or melting the vicinity of the tip of the blade into two parts and connecting them later. This connection method uses brazing.

Diffusion bonding methods and fusion welding methods can be considered, but brazing requires a long process time and is highly dependent on the brazing filler metal, and bonding performance varies widely depending on the quality of the setting, resulting in complex structures. There are problems such as difficulty in uniformly connecting parts. On the other hand, the diffusion bonding method requires high pressure to be applied during connection, which causes deformation after bonding, takes a long time to bond, and has problems such as poor productivity. In addition, in fusion welding, the material itself is made to precipitate carbides and intermetallic compounds to obtain high strength, so there are problems such as many hot cracks occurring in the weld heat affected zone after arc welding. Could not be applied.

The purpose of the present invention is to use an improved Ni-base superalloy to make welded structures possible due to frequent weld cracking, which made it impossible to apply arc welding, and at the same time to improve productivity. The object of the present invention is to provide a method to which the arc welding method, which is the most effective method, can be applied.

[Means for solving problems]

The main point of the present invention is that the weld cracks that occur when melt welding Ni-based superalloy heat-resistant materials are intergranular cracks, and that it is possible to prevent these to produce a welded structure blade.

Therefore, the above purpose is to make the wing into a single crystal or a crystal grain similar to it, heat treat it after welding the parts, and weld the blade under welding conditions such that no welding defects will occur after welding to form a welded structure. achieved.

[Effect]

In fusion welding of Ni-based superalloy heat-resistant materials, it has been considered impossible to fusion weld them because, as mentioned above, weld cracks occur from grain boundaries in the weld heat-affected zone. Therefore, it was not possible to structure the parts by welding and make them into wings.

The reason for this is that in this type of Ni-based superalloy, since the amount of alloying elements added is large, the alloying elements segregate at the grain boundaries either singly or in the form of a compound. That is, during welding, the grain boundaries are preferentially melted and embrittled by the welding heat, and then during cooling the large shrinkage stress concentrates on the grain boundaries, causing cracks.5 In the present invention, , From the above point of view, the blade components are made of single crystal or a material close to it, and welding is done with consideration given to minimizing the number of crystal grains in contact with the weld metal, and structures structured using this method are considered to be welded. A crack-free weld can be obtained. Welding is performed by tungsten inert gas arc welding in an inert or vacuum atmosphere, but the welding heat input, that is, welding current x welding time, is kept as low as possible (approximately 240 to 450 A).
-sac) The appropriate range of welding current is 30A to 50A, and when changing the welding current, it is necessary to adjust the welding time so that the welding heat input falls within the range of 240 to 450 Asee. be. If the welding heat input is less than 24OA・see, welding defects will occur due to poor fusion, whereas if the heat input is more than 450・sec, the distortion due to welding heat will increase, making it easier for cracks to occur, and at the same time the weld metal will be damaged. The amount of the components B and A11°Ti increases significantly, and not only the weld heat affected zone but also the weld metal becomes susceptible to cracking.

Next, during tungsten inert gas welding (TIG), a thin thorium-filled tungsten electrode is used, and during welding, 12 Q/l1in of argon gas is flowed as a shield gas, and at the same time, argon gas is flowed at about 3Q/min as an auxiliary gas. , it is necessary to prevent oxidation and nitridation of welded parts. In addition, it is appropriate to use a ductile Hastelloy or Inconel filler rod, and if a filler rod with the same composition as the blade material is used, component segregation will occur when the weld metal is used, resulting in severe cracking. 6. During welding work, it is necessary to heat all the objects to be welded (Figures 3 to 5) to 500 to 650'C before welding. If this temperature is lower than 500°C, a temperature difference will occur between the welded part and the unwelded part after welding, and cracks will occur due to thermal strain.

On the other hand, when heated to a temperature higher than 650° C., the ductility of the material decreases and cracks are more likely to occur.

Additionally, there is a large difference in the occurrence of weld cracking depending on whether or not heat treatment (thermal treatment) is performed before welding the Ni-based superalloy heat-resistant steel.
Welding cracks are less likely to occur when heat-treated materials are welded than as-made materials. Therefore, when welding a blade into a structure using the method of the present invention, it is necessary to heat-treat the material (1204° C. + 1093° C.) before welding.

Using this method, we attempted to weld the lids shown in Figures 3 and 4 as well as the cap including the closing plate, and microscopically examined the welded parts, as shown in Figures 6 and 7. It was found that a welded part without cracking could be obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to Table 1, Table 2, and FIGS. 1 to 7. Table 1 shows the chemical composition of the wing material and filler rod.

Table 1 Table 2 The blade material is a Ni-based super superalloy heat-resistant material whose strength is improved by precipitation of carbides and intermetallic compounds.

Regarding this material, the wing part including the base of the wing and the closing plate shown in Fig. 2 are melted separately and structured by welding, and the vicinity of the wing tip is melted in a horizontally split state. The wing tip caps are now welded to the wings. That is, in FIG. 3, a casting hole with a diameter of about 5+ m was made and melted, and then a lid made under the same conditions as the blade was installed and welded.

Fig. 4 shows a blade which was melted without the closing plate at the tip of the wing, and later the closing plate, which had been melted under the same conditions as the wing, was installed and welded. In addition, in Figures 3 and 5, if a closing cover is installed, as shown in Figure 6, 0.5XO, 5
■Protrusions of approximately 100 yen are provided to prevent the lid from falling off. In addition, FIG. 5 shows a structure in which the cap including the closing plate and the wing portion are separately melted and welded.

For welding, the heat input (welding current x welding time) is 240 to 450.
While adjusting the time so that it falls within the range of A-see and so that the amount of penetration during welding is from 1/2 to 273 of the thickness of the closed plate shown in Figure 6, A rod was inserted, 12 g/win of argon gas was flowed from a welding torch, and the entire blade was placed in a container filled with argon and welded.

Furthermore, before welding, the entire blade was uniformly heated to 600°C. After welding, the blades were heat treated as shown in Figure 7 to form wings.

As a result of examining the integrity of the blades through dyeing and flaw detection tests, no cracks were found. That is, in the present invention, no cracking is observed when the crystal is divided into single crystals or nearly so, and structured by welding. For the above reasons, weld cracking can be avoided by adjusting the crystal grains of Ni-based super superalloy heat-resistant materials that are prone to weld cracking, and making them as single as possible to prevent weld cracking caused by grain boundaries. High quality welds are obtained.

〔Effect of the invention〕

According to the present invention, when manufacturing a blade with complicated cooling holes,
Since split melting is possible, defects that occur during melting can be prevented and product performance can be improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of heat treatment according to an embodiment of the present invention, Fig. 2 is an overall structural diagram of a blade, Figs. The figure shows an installation method when the lid is temporarily closed in FIGS. 3 and 4, and FIG. 7 shows an example of heat treatment performed after welding is completed. DESCRIPTION OF SYMBOLS 1... Wing part, 2... Core support hole, 3... Base, 4
... Closing plate, 5... Closing plate channel cover, 6... Wing side plate. 8 No. Country 2nd Old No. 31! ] Figure 4 $ 5 b

Claims (1)

[Claims] 1. Supporting the core of a blade with a complex cooling structure made of a Ni-based superalloy, and sealing and joining of a support hole provided at the tip of the blade to facilitate elution; In the method in which the blade tip is melted separately from the main body and then integrated by joining, the material is a single crystal material or a similar material, and an Fe or Ni-based filler rod is used in an inert atmosphere or vacuum. A method for manufacturing a wing, characterized in that a welded structure is obtained by welding inside the blade to prevent the occurrence of weld cracks caused by grain boundaries. 2. In claim 1, the wing is a single crystal or adjusted to be similar to it at the time of melting, and its size is such that the number of crystals in contact with the weld metal after welding is as small as possible. A method for manufacturing wings characterized by the following. 3. In claim 1, split melting is performed separately for the wing portion including the base portion and the closing plate, and for the portion of the wing including the base portion and the blade tip portion, and the size of the crystal grains is A method for manufacturing a wing, characterized in that the method uses a single crystal or a material adjusted to be similar to the single crystal. 4. In claim 1, 2, or 3, welding is performed at 500 to 650°C in an inert gas or vacuum atmosphere.
1. A method of manufacturing a blade, which is characterized in that after preheating, the welding is performed with a low heat input that does not cause welding defects. 5. In claim 1, the welding structure of the blade includes partially or completely covering a hole provided at the tip of the blade with the closing plate, or connecting a part of the blade including the base with the blade. A method for manufacturing a blade, characterized by separately melting the tip of the blade, heat-treating it, and then forming a welded structure.