A method of seed preparation for single crystal superalloy blades

Abstract

The application provides a method for preparing a single-crystal high-temperature alloy blade by using a seed crystal, comprising the following steps: S1) preparing a shell mold set of the single-crystal high-temperature alloy blade, so that the seed crystal and the shell of the shell mold set are in gapless contact; S2) placing the shell mold set on a water-cooled crystallizer, and after the shell mold set is heated, pouring single-crystal high-temperature alloy liquid into a cavity through a transition runner cavity of a pouring system to reduce the speed of the single-crystal high-temperature alloy liquid entering the cavity, and obtaining the single-crystal high-temperature alloy blade after directional solidification. The method for preparing a single-crystal high-temperature alloy blade by using a seed crystal provided in the application eliminates the gap between the seed crystal and the shell, and introduces a transition runner cavity to control the alloy liquid filling process of the cavity, so that the seed crystal part of the remelted region tends to be static and stable, the grain proliferation caused by the fragmentation of the dendrites in the remelted region is reduced, and the success rate of single-crystal seeding is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of engine single-crystal superalloy blade preparation technology, and in particular to a method for preparing single-crystal superalloy blades using seed crystals. Background Technology

[0002] Aero-engine turbine blades operate in environments with high temperatures, complex stresses, and the harshest conditions. As one of the key components of an aero-engine, the quality and performance of turbine blades significantly affect the engine's performance.

[0003] Gas turbine engine blades are subjected to the combined effects of high temperatures, complex stresses, and corrosive atmospheres, and must also withstand the rapid changes during startup and braking. Grain boundaries in the turbine blade microstructure, especially the transverse grain boundaries perpendicular to the stress axis, are its weakest points. The absence of grain boundaries in single-crystal blades eliminates the risk of high-temperature grain boundary weakening, significantly reducing the tendency for fatigue cracking. Single-crystal superalloys, due to their excellent creep resistance, durability, high-temperature resistance, and thermomechanical fatigue resistance, are widely used in turbine engine blades. The single-crystal characteristic significantly increases the alloy's operating temperature, making it considered the optimal material for engine blades.

[0004] During the directional solidification of single-crystal superalloys, a phase transformation from liquid to solid occurs, which takes place through nucleation and growth. The directional solidification of single-crystal superalloys must avoid nucleation during solidification; solidification relies on growth from the already solidified solid phase. Therefore, the crystal orientation in the early stages of solidification determines the crystal orientation of the blade. In the fabrication of single-crystal superalloy blades, a seed crystal or spiral crystal selection process is used at the beginning of directional solidification, allowing only a single-oriented grain to enter the blade cavity. Directional solidification then proceeds based on this grain, resulting in a single-crystal casting with only one grain. Therefore, to obtain a single crystal, seed crystals or spiral structures can be used.

[0005] Using seed crystals allows for control over the three-dimensional spatial orientation of the blades, including primary and secondary orientations. However, using seed crystals presents several challenges. First, the orientation of the seed crystal must be strictly controlled during the preparation of the wax model for the single-crystal casting to ensure the desired orientation is achieved. Second, when obtaining a single crystal using seed crystals, a gap exists between the seed crystal and the shell after it has been placed inside the prepared shell. Numerous studies have shown that this gap is one of the main reasons for seed crystal introduction failure. Furthermore, since the seed crystal has already partially melted before the alloy liquid is poured, a transition region exists between the melted and unmelted portions, which is prone to crystal defects.

[0006] Therefore, eliminating the gap between the seed crystal and the shell and reducing crystal-driving defects is of great significance for the preparation of single-crystal high-temperature alloy blades. Summary of the Invention

[0007] The technical problem solved by this invention is to provide a method for preparing single-crystal high-temperature alloy blades using seed crystals, which can reduce the external force exerted by the alloy liquid on the dendrites in the remelting zone during the casting process, and realize the method of preparing single-crystal high-temperature alloy blades using seed crystals.

[0008] In view of this, this application also provides a method for preparing single-crystal superalloy blades using seed crystals, comprising the following steps:

[0009] S1) Prepare a shell module for a single crystal high-temperature alloy blade, so that the seed crystal and the shell of the shell module are in gapless contact;

[0010] S2) The shell module is placed on the water-cooled crystallizer. After the shell module is heated, the single crystal high-temperature alloy liquid is poured into the cavity through the transition gating channel of the gating system to reduce the speed at which the single crystal high-temperature alloy liquid enters the cavity. After directional solidification, a single crystal high-temperature alloy blade is obtained.

[0011] Preferably, the means to ensure that the seed crystal and the shell of the shell module are in gapless contact is as follows:

[0012] In the preparation of the wax model module, seed crystals are placed in the shell. The resulting wax model module is then coated, dewaxed, and sintered to obtain a shell wax model with seed crystals.

[0013] Preferably, the means to ensure that the seed crystal and the shell of the shell module are in gapless contact is as follows:

[0014] The seed crystal cavity of the wax mold module is set to a tapered shape with a larger bottom and a smaller top. Before pouring, a seed crystal matching the tapered shape is placed in the seed crystal cavity.

[0015] Preferably, the taper is 1° to 5°.

[0016] Preferably, the pouring method into the mold cavity is bottom pouring, and the outlet of the mold cavity entering from the transition runner cavity is located at the upper part of the transition runner cavity.

[0017] Preferably, the casting system includes a large cross-sectional area intermediate cavity, a first channel located at the lower part of the intermediate cavity and away from the mold cavity, and a second channel located at the upper part of the intermediate cavity and connected to the mold cavity. The cross-sectional areas of the first channel and the second channel are both smaller than the cross-sectional area of ​​the intermediate cavity, and the first channel, the intermediate cavity and the second channel are connected.

[0018] Preferably, the length of the seed crystal is 10mm to 20mm.

[0019] Preferably, the length of the seed crystal is 15-30 mm.

[0020] Preferably, the diameter of the intermediate cavity is 10-15 mm and the height is 10-20 mm, the diameter of the first cavity is 1-5 mm, and the diameter of the second cavity is 1-5 mm.

[0021] Preferably, the single-crystal high-temperature alloy blade is a DD3 alloy blade, a DD6 alloy blade, or a DD9 alloy blade.

[0022] This application provides a method for preparing single-crystal superalloy blades using seed crystals. First, a shell module for the single-crystal superalloy blade is prepared, ensuring a gapless contact between the seed crystal and the shell of the shell module. Then, the shell module is placed on a water-cooled crystallizer. After heating the shell module, molten single-crystal superalloy is poured into the mold cavity through a transition runner in the gating system to reduce the speed at which the molten single-crystal superalloy enters the mold cavity. After directional solidification, a single-crystal superalloy blade is obtained. During the preparation of the single-crystal superalloy blade using seed crystals, the gapless contact between the seed crystal and the shell module eliminates the void between them, avoiding crystal-attracting defects caused by such voids. Simultaneously, by introducing a transition runner, the disturbance of the partially melted, pasty region of the seed crystal by the molten single-crystal superalloy is significantly reduced, thereby avoiding dendrite breakage within the pasty region of the seed crystal caused by the momentum introduced during pouring. This significantly improves the seed crystal attraction success rate, reduces crystal-attracting defects, and increases the overall success rate of single-crystal superalloy blade preparation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the preparation of single-crystal blades by placing seed crystals into the wax mold module during the preparation of the coating in this invention;

[0024] Figure 2 This is a schematic diagram of the shell structure using a conical seed crystal cavity in this invention;

[0025] Figure 3 This is a schematic diagram illustrating the preparation of blades using the directional solidification of conical seed crystals in this invention.

[0026] Wherein, 1 is the gating system; 2 is the seed crystal; 3 is the shell; 4 is the cavity; 5 is the water-cooled crystallizer; 1-1 is the gating system; 1-2 is the first cavity; 1-3 is the intermediate cavity; and 1-4 is the second cavity. Detailed Implementation

[0027] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0028] In the fabrication of single-crystal blades, seed crystal processing is an important method for crystal growth. During directional solidification, at high temperatures, the seed crystal is partially melted back, while the portion surrounded by the mold shell remains unmelted due to the intense cooling effect of the water-cooled crystallizer. The unmelted portion of the seed crystal serves as the substrate, becoming the core for single-crystal growth. However, impurities are easily generated at the interface between the seed crystal and the mold shell, as well as in the mushy region between the melted and unmelted areas, leading to seed crystal growth failure. Breakage or deflection of dendrites in the partially melted mushy region of the seed crystal can also cause seed crystal growth failure. To address these issues, this application provides a method for preparing single-crystal superalloy blades using seed crystals. By introducing a gapless contact between the seed crystal and the mold shell module, the gap between the seed crystal and the mold shell is eliminated. Simultaneously, a transition gating cavity is introduced, reducing the external force exerted by the molten single-crystal superalloy on the dendrites in the melted region during casting. Therefore, this significantly improves the seed crystal growth success rate and reduces seed crystal defects and even blade scrap. This application provides a method for preparing single-crystal superalloy blades using seed crystals, comprising the following steps:

[0029] S1) Prepare a shell module for a single crystal high-temperature alloy blade, so that the seed crystal and the shell of the shell module are in gapless contact;

[0030] S2) The shell module is placed on the water-cooled crystallizer. After the shell module is heated, the single crystal high-temperature alloy liquid is poured into the cavity through the transition gating channel of the gating system to reduce the speed at which the single crystal high-temperature alloy liquid enters the cavity. After directional solidification, a single crystal high-temperature alloy blade is obtained.

[0031] Typically, when using the seed crystal method, a cylindrical seed crystal cavity is first prefabricated on the mold shell using a wax mold module. Then, before casting, the seed crystal is placed in the cavity to prepare the single-crystal blade. However, this method creates a gap between the seed crystal's side and the mold shell, which easily leads to crystal nucleation defects. The mold shell module for the single-crystal high-temperature alloy blade prepared in this application ensures a gapless contact between the seed crystal and the mold shell module. In this application, the gapless contact between the seed crystal and the mold shell module includes two methods: First, the seed crystal is placed in the mold shell during the preparation of the wax mold module. The resulting wax mold module is then coated, dewaxed, and sintered sequentially, ensuring no gap between the mold shell surrounding the seed crystal and the seed crystal during directional solidification. Second, the seed crystal cavity of the wax mold module is set with a tapered shape, wider at the bottom and narrower at the top. After coating, dewaxing, and sintering the wax mold mold, a matching seed crystal is placed in the cavity before casting. The taper is 1° to 5°, specifically 1° to 2°. In the first method described above, the length of the seed crystal is 10 to 20 mm, more specifically 12 to 15 mm, to ensure that the seed crystal surrounded by the mold shell does not remelt completely at the blade's directional solidification temperature, thus escaping the effect of the mold shell on the mushy region. Therefore, the mushy region enters the cavity, avoiding the appearance of a mushy region at the interface between the seed crystal and the mold shell. In the second method described above, the length of the seed crystal is 15 to 30 mm, more specifically 20 to 28 mm, to ensure that the upper part of the seed crystal completely remelts at the single-crystal blade mold shell insulation temperature.

[0032] The elimination of the gap between the seed crystal and the side of the shell avoids dendrite nucleation caused by the filling of molten alloy due to the presence of gaps in the prior art.

[0033] According to the present invention, the shell module is then placed on a water-cooled crystallizer. After the shell module is heated, the single-crystal high-temperature alloy liquid is poured into the mold cavity through the transition gating channel of the gating system. The heating is to heat the shell module to a temperature above the melting point of the alloy liquid before pouring the single-crystal high-temperature alloy liquid.

[0034] The lower part of the seed crystal, surrounded by the mold shell, is subjected to intense cooling by the water-cooled crystallizer and remains at a low temperature; while the upper part of the seed crystal is subjected to high temperature within the mold cavity and undergoes remelting. Inside the seed crystal, there is a temperature gradient from top to bottom. Single-crystal superalloys are multi-component alloys containing multiple alloying elements, and there is a melting range during solidification, which results in a mushy region in the seed crystal. Liquid and solid coexist in the mushy region, with some dendrite trunks being solid, surrounded by liquid alloy. This is equivalent to solid dendrite trunks standing upright in liquid alloy. When the liquid phase flows, it exerts a scouring force on the dendrite trunks. When this force exceeds a certain level, it causes the dendrite trunks to break. The broken dendrite trunks then become nuclei, which grow into impurities, leading to the failure of crystallization.

[0035] Therefore, in order to avoid dendrite fracture, the momentum of the molten metal poured into the mold cavity should be as small as possible. This application introduces a transition gating cavity into the gating system to reduce the external force of the molten alloy on the dendrites in the remelting zone during the pouring process. This minimizes the momentum of the molten alloy when it reaches the seed crystal, so that the scouring effect of the molten alloy on the seed crystal can be ignored. Under the action of small momentum, the dendrite trunk in the remelting paste-like zone of the seed crystal remains stable.

[0036] The transition gating cavity is filled with single-crystal high-temperature alloy liquid via bottom-pouring. The outlet from the transition gating cavity into the mold cavity is located at the top of the transition gating cavity. Furthermore, to minimize the amount of alloy liquid poured into the mold cavity, the transition gating cavity is configured as follows: Figure 1 , Figure 2 and Figure 3 As shown, a large-section intermediate cavity 1-3, a first channel 1-2 located below the intermediate cavity 1-3 and far from the cavity, and a second channel 1-4 located above the intermediate cavity 1-3 and connected to the cavity are introduced at the ingate entering the mold cavity. The cross-sectional areas of the first channel 1-2 and the second channel 1-4 are both smaller than the cross-sectional area of ​​the intermediate cavity 1-5. The momentum of the molten alloy entering the second channel 1-4 from the intermediate cavity 1-3 is dissipated, and the velocity becomes very small, thereby reducing the external force of the molten alloy on the dendrites in the remelting zone during the casting process. The diameter of the intermediate cavity is 10-15 mm and the height is 10-20 mm, the diameter of the first channel is 1-5 mm, and the diameter of the second channel is 1-5 mm; more specifically, the diameter of the intermediate cavity is 12-14 mm and the height is 15-18 mm, the diameter of the first channel is 3-5 mm, and the diameter of the second channel is 3.5-5 mm.

[0037] With the improvement of the above methods, during the directional solidification process, at the high temperature of directional solidification, part of the seed crystal 2 is melted back, while the seed crystal surrounded by the shell does not melt back at all due to the strong cooling effect of the water-cooled crystallizer, and is not disturbed by the pouring alloy liquid. The unmelted and melted seed crystal part serves as the substrate and becomes the core of single crystal growth, thus growing into a single crystal blade.

[0038] The method provided in this application is applicable to the preparation of single-crystal high-temperature alloy blades known to those skilled in the art. For example, the single-crystal high-temperature alloy blade is a DD3 alloy blade, a DD6 alloy blade, or a DD9 alloy blade.

[0039] To further understand the present invention, the method for preparing single-crystal high-temperature alloy blades using seed crystals provided by the present invention will be described in detail below with reference to embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0040] Example 1

[0041] A method for preparing single-crystal superalloy blades DD6 based on statically stable seed crystals:

[0042] Seed crystal 2 is placed in the wax mold assembly during preparation. Then, the single crystal wax mold assembly with seed crystal is coated, dewaxed and sintered to obtain shell 3 with seed crystal 2 embedded in it. The length of the seed crystal in the shell is 15mm.

[0043] A large-section intermediate cavity 1-3 is introduced into the ingate entering the mold cavity. 1-3 has a diameter of 12mm and a height of 15mm, dividing the ingate into two parts: a first cavity 1-2 and a second cavity 1-4. The first cavity 1-2 has a diameter of 3mm, and the second cavity 1-4 has a diameter of 3.5mm. The first cavity 1-2 is located at the lower part of the intermediate cavity 1-3, and the second cavity 1-4, connected to the mold cavity, is located at the upper part of the intermediate cavity 1-3. Figure 1 As shown; the DD3 alloy liquid enters the first cavity 1-2 from the 1-1 gating channel, and then enters the second cavity 1-4 from the intermediate cavity 1-3. The momentum of the molten metal in the intermediate cavity 1-3 is dissipated, and the velocity becomes very small. It then enters the mold cavity 4 for directional solidification.

[0044] During the directional solidification process, the directional solidification temperature is relatively low at 1500℃, which ensures that the seed crystal surrounded by the shell does not melt back at the directional solidification temperature of the blade, thus escaping the effect of the shell on the mushy region. As a result, the mushy region enters the cavity, avoiding the appearance of a mushy region at the interface between the seed crystal and the shell. After cooling, a single crystal high-temperature alloy blade DD6 is obtained.

[0045] Using the above-mentioned seed crystal extraction method, 200 blades were prepared, with a crystal extraction success rate of 96%.

[0046] Example 2

[0047] A method for preparing single-crystal superalloy blades DD6 based on statically stable seed crystals:

[0048] Seed crystal 2 is placed in the wax model assembly during preparation. Then, the single crystal wax model assembly with seed crystal is coated, dewaxed and sintered to obtain a shell 3 with seed crystal 2 embedded in it. The length of the seed crystal in the shell is 20mm.

[0049] A large-section intermediate cavity 1-3 is introduced into the ingate entering the mold cavity. 1-3 has a diameter of 12mm and a height of 15mm, dividing the ingate into two parts: a first cavity 1-2 and a second cavity 1-4. The first cavity 1-2 has a diameter of 3mm, and the second cavity 1-4 has a diameter of 3.5mm. The first cavity 1-2 is located at the lower part of the intermediate cavity 1-3, and the second cavity 1-4, connected to the mold cavity, is located at the upper part of the intermediate cavity 1-3. Figure 1As shown; DD6 alloy liquid enters the first cavity 1-2 from the 1-1 gating channel, and then enters the second cavity 1-4 from the intermediate cavity 1-3. The momentum of the molten metal in the intermediate cavity 1-3 is dissipated, and the velocity becomes very small. It then enters the mold cavity 4 for directional solidification.

[0050] During the directional solidification process, the directional solidification temperature is relatively low at 1540℃, which ensures that the seed crystal surrounded by the shell does not melt back at the directional solidification temperature of the blade, thus escaping the effect of the shell on the mushy region. As a result, the mushy region enters the cavity, avoiding the appearance of a mushy region at the interface between the seed crystal and the shell. After cooling, a single crystal high-temperature alloy blade DD6 is obtained.

[0051] Using the above-mentioned seed crystal extraction method, 120 blades were prepared, with a crystal extraction success rate of 93%.

[0052] Example 3

[0053] A method for preparing DD9 single-crystal superalloy blades based on statically stable seed crystals:

[0054] Seed crystal 2 is placed in the wax model assembly during preparation. Then, the single crystal wax model assembly with seed crystal is coated, dewaxed and sintered to obtain a shell 3 with seed crystal 2 embedded in it. The length of the seed crystal in the shell is 20mm.

[0055] A large-section intermediate cavity 1-3 is introduced into the ingate entering the mold cavity. 1-3 has a diameter of 12mm and a height of 15mm, dividing the ingate into two parts: a first cavity 1-2 and a second cavity 1-4. The first cavity 1-2 has a diameter of 3mm, and the second cavity 1-4 has a diameter of 3.5mm. The first cavity 1-2 is located at the lower part of the intermediate cavity 1-3, and the second cavity 1-4, connected to the mold cavity, is located at the upper part of the intermediate cavity 1-3. Figure 1 As shown; DD9 alloy liquid enters the first cavity 1-2 from the 1-1 gating channel, and then enters the second cavity 1-4 from the intermediate cavity 1-3. The momentum of the molten metal in the intermediate cavity 1-3 is dissipated, and the velocity becomes very small. It then enters the mold cavity 4 for directional solidification.

[0056] During the directional solidification process, the directional solidification temperature is relatively low at 1540℃, which ensures that the seed crystal surrounded by the shell does not melt back at the directional solidification temperature of the blade, thus escaping the effect of the shell on the mushy region. As a result, the mushy region enters the cavity, avoiding the appearance of a mushy region at the interface between the seed crystal and the shell. After cooling, a single crystal high-temperature alloy blade DD9 is obtained.

[0057] Using the above-mentioned seed crystal extraction method, 390 blades were prepared, with a crystal extraction success rate of 97%.

[0058] In Example 1, the blades prepared are second-generation single-crystal high-temperature alloy blades with low melting points. Furthermore, due to the thin core and other reasons, the directional solidification temperature of the blades is low at 1500°C. The length of the seed crystal inside the shell is 15 mm. During the directional solidification process, the seed crystal embedded in the shell does not remelt at all and remains in a solid state. In order to ensure a good crystal-leading effect, the upper part of the seed crystal needs to remelt, and the length of the seed crystal is 25 mm.

[0059] In Example 2, the blades prepared were third-generation single-crystal high-temperature alloy blades with high melting points. The blades had simple shapes. In order to obtain a high single-crystal yield, the directional solidification temperature of the blades reached 1600℃. The length of the seed crystal inside the shell was 10mm. During the directional solidification process, the seed crystal embedded in the shell did not remelt at all and remained in a solid state. In order to ensure a good crystal-leading effect, the upper part of the seed crystal needed to remelt. The length of the seed crystal was 20mm.

[0060] In Example 3, the prepared single crystal alloy has a high melting point and a complex blade shape. The directional solidification temperature of the blade reaches 1500℃. The length of the seed crystal inside the shell is 20mm. During the directional solidification process, the seed crystal embedded in the shell does not remelt at all and remains in a solid state. In order to ensure a good crystal pulling effect, the upper part of the seed crystal needs to remelt. The length of the seed crystal is 30mm.

[0061] Example 4

[0062] A method for preparing single-crystal superalloy blades DD6 based on statically stable seed crystals:

[0063] A wax strip with a 2° taper or a ceramic tube with a 2° taper and an internal cavity is prepared at the bottom of the blade wax model. Multiple wax models and a gating system are welded together to prepare a wax model assembly. The wax model assembly is then subjected to shell coating, dewaxing, and sintering. A seed crystal cavity with a 2° taper is formed in the lower part of the shell, with a lower diameter of 3 mm and a length of 20 mm. A seed crystal with a 2° taper, a large end diameter of 2.9 mm, and a length of 25 mm is placed into the lower part of the seed crystal cavity, ensuring that the taper side of the seed crystal fits tightly against the seed crystal cavity. Ceramic slurry is then used to fill the cross-section of the seed crystal cavity, firmly placing the seed crystal in the seed crystal cavity. The shell model assembly is then placed on a water-cooled crystallizer. After the shell model assembly is heated, single-crystal high-temperature alloy liquid is poured into the cavity through the transition gating channel of the gating system. The heating process raises the shell model assembly to above the melting point of the alloy liquid before the single-crystal high-temperature alloy liquid is poured.

[0064] A large-section intermediate cavity 1-3 is introduced into the ingate entering the mold cavity. 1-3 has a diameter of 12mm and a height of 15mm, dividing the ingate into two parts: a first cavity 1-2 and a second cavity 1-4. The first cavity 1-2 has a diameter of 3mm, and the second cavity 1-4 has a diameter of 3.5mm. The first cavity 1-2 is located at the lower part of the intermediate cavity 1-3, and the second cavity 1-4, connected to the mold cavity, is located at the upper part of the intermediate cavity 1-3. Figure 1 As shown; DD6 alloy liquid enters the first cavity 1-2 from the 1-1 gating channel, and then enters the second cavity 1-4 from the intermediate cavity 1-3. The momentum of the molten metal in the intermediate cavity 1-3 is dissipated, and the velocity becomes very small. It then enters the mold cavity 4 for directional solidification.

[0065] Due to the blade structure and other factors, the directional solidification temperature is relatively low at 1500℃. The length of the seed crystal inside the shell is 15mm. During the directional solidification process, the seed crystal embedded in the shell does not remelt at all and remains in a solid state. In order to ensure a good crystal-leading effect, the upper part of the seed crystal needs to remelt, and the length of the seed crystal is 25mm.

[0066] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0067] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a single crystal superalloy blade by using a seed crystal, comprising the following steps: S1) preparing a shell mold set for the single crystal superalloy blade, so that the seed crystal and the shell of the shell mold set are in contact without clearance; S2) placing the shell mold set on a water-cooled crystallizer, and after heating the shell mold set, pouring single crystal superalloy liquid into a mold cavity through a transition runner cavity of a gating system to reduce the speed of the single crystal superalloy liquid entering the mold cavity, and obtaining a single crystal superalloy blade after directional solidification; the means for making the seed crystal and the shell of the shell mold set in contact without clearance is: setting the seed crystal cavity of the wax mold set to a taper of large at the bottom and small at the top, and placing a seed crystal with a matching taper in the seed crystal cavity before pouring, the taper being 1° to 5°; the gating system comprises an intermediate cavity with a large cross-sectional area, a first cavity channel located at the lower part of the intermediate cavity and away from the mold cavity, and a second cavity channel located at the upper part of the intermediate cavity and connected to the mold cavity, the cross-sectional areas of the first cavity channel and the second cavity channel are smaller than the cross-sectional area of the intermediate cavity, and the first cavity channel, the intermediate cavity and the second cavity channel are in communication.

2. The method of claim 1, wherein, The pouring into the mold cavity is of a bottom pouring type, and the outlet of the transition runner cavity into the mold cavity is located at the upper part of the transition runner cavity.

3. The method of claim 1, wherein, The length of the seed crystal is 10 mm to 20 mm.

4. The method of claim 1, wherein, The length of the seed crystal is 15 to 30 mm.

5. The method of claim 1, wherein, The diameter of the intermediate cavity is 10 to 15 mm, and the height is 10 to 20 mm, the diameter of the first cavity channel is 1 to 5 mm, and the diameter of the second cavity channel is 1 to 5 mm.

6. The method according to any one of claims 1 to 5, characterized in that, The single crystal superalloy blade is a DD3 alloy blade, a DD6 alloy blade or a DD9 alloy blade.

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