Single-crystal high-temperature alloy casting prepared from reusable short seed crystals and preparation method of single-crystal high-temperature alloy casting

Abstract

The invention relates to the technical field of single-crystal high-temperature alloy castings, and particularly discloses a single-crystal high-temperature alloy casting prepared from reusable short seed crystals and a preparation method of the single-crystal high-temperature alloy casting, aiming at the problems that the service life of the seed crystals is short and the use cost is high in the process of preparing the single-crystal casting by adopting a seed crystal method at present, and the single-crystal high-temperature alloy casting prepared from the reusable short seed crystals and the preparation method of the single-crystal high-temperature alloy casting are disclosed. The single crystal seed crystal comprises a top inclined plane and a bottom plane, the included angle between the top inclined plane and the bottom plane is 10-40 degrees, and the height of the single crystal seed crystal from the bottom plane to the low point of the top inclined plane is 5-10 mm. By optimizing and improving the structure and position relation of the single crystal seed crystal and the wax mold module, according to the production process steps, the effects of avoiding mixed crystals formed due to factors such as dendritic crystal fracture and large supercooling degree in a single crystal seed crystal remelting area and ensuring the consistency of the crystal orientation of a casting and the crystal orientation of the seed crystal are achieved.

Description

Technical Field

[0001] This invention relates to the field of single-crystal superalloy casting technology, and more specifically, to a single-crystal superalloy casting prepared from reusable short seed crystals and its preparation method. Background Technology

[0002] Single-crystal superalloy castings typically require the angle between a certain characteristic direction of the casting and a certain crystallographic direction of the alloy to be within a certain range. This can usually be achieved using the seed crystal method or the selective crystal method. The selective crystal method is widely used in industrial production, but it has a certain probability of failure, mainly manifested as failure to select individual grains or grain orientation not meeting requirements; moreover, the selective crystal method struggles to precisely control the three-dimensional orientation of the blades. In contrast, the seed crystal method, if the process is properly controlled, can theoretically completely replicate the orientation of the seed crystal, forming a complete single crystal. This eliminates the risk of unqualified grains and orientations in single-crystal castings and allows for precise control of the three-dimensional orientation of the blades. Therefore, most single-crystal blade manufacturers are conducting technical research on the seed crystal method for producing single-crystal blades.

[0003] The seed crystal method for preparing single-crystal castings includes seed crystal preparation, installation, and directional solidification of the casting. The directional solidification process is consistent with the traditional selective crystal method for preparing single-crystal castings. However, when precise control of the three-dimensional orientation of the casting is required, the characteristic orientation of the seed crystal must be matched with the characteristic orientation of the casting during preparation and installation. For example, patent CN109513881A provides a method for casting single-crystal high-temperature alloy blades with precisely controllable three-dimensional crystal orientation.

[0004] However, in current industrial production, the seed crystal method for preparing single-crystal castings generally suffers from the following problems: (1) Oxidation of seed crystal surface: An oxide layer is easily formed on the surface of the seed crystal during storage or pretreatment, which makes it impossible for the casting to effectively replicate the orientation of the seed crystal. Although anti-oxidation improvement of seed crystal has been proposed, its production cost is too high. (2) Low seed crystal production efficiency: In order to ensure that the seed crystal can be fully remelted during directional solidification to achieve crystal orientation inheritance, the seed crystal length is usually designed to be 35~50mm in the existing technology. The longer size leads to a long seed crystal processing cycle, low material utilization, and limited production efficiency. (3) The seed crystal recycling process is complicated: During casting, the alloy liquid will fill the gap between the seed crystal and the shell, resulting in the formation of excess metal layer and fine equiaxed crystals on the surface of the seed crystal. During recycling, the entire surface of the seed crystal needs to be cut to remove excess metal and equiaxed crystal layer. The processing workload is large and time-consuming. After multiple processing, the size of the seed crystal is likely to exceed the tolerance range and cannot be reused.

[0005] Based on the above, there is an urgent need for a method for preparing single crystal castings that is based on the seed crystal preparation process, has good performance, and can effectively control production costs. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of short seed crystal lifespan and high cost in the current seed crystal method for preparing single crystal castings.

[0007] This invention is achieved through the following technical solution: This invention provides a method for preparing a single-crystal high-temperature alloy casting from a reusable short seed crystal. The single-crystal seed crystal includes a top inclined surface and a bottom plane. The angle between the top inclined surface and the bottom plane is 10-40°, and the height of the single-crystal seed crystal from the bottom plane to the lowest point of the top inclined surface is 5-10 mm.

[0008] Preferably, the wax model assembly for casting includes a seed crystal wax model, the shape and size of which are matched with the shape and size of the single crystal seed crystal, and the three-dimensional orientation relationship between the seed crystal wax model and the casting is established with the top inclined surface of the single crystal seed crystal as a reference.

[0009] Preferably, the wax model assembly further includes a casting wax model, an ingate, and a sprue, wherein the extension line of the ingate intersects the top inclined surface.

[0010] Preferably, the distance between the centerline of the ingate and the center of the top slope is less than or equal to 3 mm, and the angle between the centerline of the ingate and the top slope is 70-130°.

[0011] Preferably, the ratio of the diameter of the inner gate to the diameter of the seed crystal wax mold is 1:1.5~5, and the ratio of the diameter of the sprue to the diameter of the seed crystal wax mold is 1:2~6.

[0012] Preferably, the method comprises the following steps: S1 Preparation of single crystal seed crystal: Using the top inclined plane as the positioning surface, prepare a single crystal seed crystal; S2 Preparation of wax model module: Prepare a seed crystal wax model that matches the size of the single crystal seed crystal, and equip it with a casting wax model, an inner gate and a sprue; S3 Preparation of ceramic shells: Ceramic shells are prepared using processes such as slurry application, sand application, drying, dewaxing, and sintering. S4 Installing a single crystal seed: Installing a single crystal seed in the seed cavity of a ceramic shell; S5 Casting and Directional Solidification: The alloy liquid is poured into the wax mold of the casting, cast and solidified in a specific direction to obtain a single crystal high-temperature alloy casting. S6 Single Crystal Seed Recycling and Reprocessing: Recycle single crystal seeds and reprocess the top bevel of the single crystal seed.

[0013] Preferably, in step S2, the upper end of the inner gate of the seed crystal wax mold is directly connected to the casting wax mold, or it is connected to the crystal selection section and then connected to the casting wax mold.

[0014] Preferably, in step S4, when installing the single crystal seed, the top inclined surface of the single crystal seed contacts the inclined surface of the seed crystal cavity, and the bottom plane of the single crystal seed contacts the water cooling plate of the directional solidification furnace.

[0015] Preferably, in step S5, after directional solidification, the top slope of the single crystal seed crystal is not completely remelted, the bottom plane of the single crystal seed crystal and the side of the seed crystal do not remelt, the part of the top slope facing the ingate and the sprue remelts, and there is no excess metal on the side of the seed crystal.

[0016] The technical solution of the present invention has the following beneficial effects: This invention optimizes and improves the structure and positional relationship of the single crystal seed and the wax mold module. Based on its production process steps, it utilizes the rapid cooling effect of the water-cooling plate and the heating effect of the high-temperature alloy liquid flowing over the surface of the single crystal seed to achieve the effect of local remelting of the tilted surface of the single crystal seed only in the central part. This results in a high temperature gradient in the remelting zone of the tilted surface of the seed, which can avoid the formation of impurities in the remelting zone of the single crystal seed due to dendrite fracture, large undercooling, etc., and ensure the consistency of the crystal orientation of the casting with the crystal orientation of the seed.

[0017] The oxide layer on the seed crystal surface decomposes or breaks under the long-term action of flowing high-temperature molten metal, which does not affect the orientation of the seed crystal replicated in the casting. The inclined surface of the single crystal seed crystal is in complete contact with the inclined surface of the seed crystal assembled on the shell, and only the central part of the inclined surface of the seed crystal is partially remelted. No excess metal is generated on other surfaces of the seed crystal, which can reduce the amount of processing work when recycling the seed crystal and improve the production efficiency when reusing the single crystal seed crystal. Impurities are not easily generated in the remelted area of ​​the seed crystal, which is beneficial to improving the qualification rate of the casting and the recycling of the seed crystal. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the single-crystal seed crystal structure in this invention; Figure 2 This is a schematic diagram of the structure of the wax mold module in this invention; Figure 3 This is a schematic diagram of the installation of the single crystal seed in this invention.

[0019] Figure reference numerals: 1-Single crystal seed, 11-Top bevel, 12-Bottom plane, 13-Seed crystal side, 21-Seed crystal wax model, 22-Casting wax model, 23-Inner gate, 24-Straight sprue, 3-Ceramic shell, 31-Seed crystal cavity, 4-Water cooling plate. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are performed according to conventional conditions or conditions recommended by the manufacturer; where the manufacturers of the instruments, equipment, reagents, or raw materials used are not specified, they are all conventional products that can be purchased commercially.

[0021] This invention provides a single-crystal superalloy casting prepared from reusable short seed crystals, the preparation method of which includes the following steps: (1) Preparation of single crystal seed crystals: According to Figure 1 The schematic diagram of the single crystal seed structure shows that a single crystal seed 1 with a height H of 5~10mm and an angle of 10~40° between the top inclined surface 11 and the bottom plane 12 is prepared. During the processing of the single crystal seed 1, the top inclined surface 11 is used as the positioning surface to control the three-dimensional orientation of the single crystal seed 1.

[0022] The present invention sets the top of the single crystal seed crystal 1 as an inclined surface, which can control the incomplete remelting of the top surface of the seed crystal, facilitate the setting of the ingate and the preparation of the shell, prevent the shell from being too thin at the angle between the ingate and the seed crystal, thus preventing fire from breaking, and the inclined surface can be used as a positioning surface to control the three-dimensional orientation of the seed crystal.

[0023] (2) Preparation of wax model modules: A seed crystal wax model 21 with the same shape and size as the single crystal seed crystal is selected, and the three-dimensional orientation correspondence between the seed crystal wax model 21 and the casting is established with the top inclined surface 11 of the seed crystal as a reference, so as to control the three-dimensional orientation of the casting.

[0024] According to Figure 2 The schematic diagram of the wax mold assembly shows that the molten alloy flows into the casting wax mold 22 from the ingate 23. The extension line of the ingate 23 intersects with the top slope 11 of the seed crystal. The distance between the center line of the ingate 23 and the center of the top slope 11 of the seed crystal is no more than 3mm, and the angle between the center line of the ingate 23 and the top slope 11 of the seed crystal is 70~130°. The ratio of the diameter of the ingate 23 to the diameter of the seed crystal wax mold 21 is 1:1.5~5. The ratio of the diameter of the sprue 24 flowing into the casting wax mold 22 to the diameter of the seed crystal wax mold 21 is 1:2~6, ensuring that most of the molten alloy flowing into the casting wax mold 22 can flow through the surface of the single crystal seed crystal 1, so that the surface of the single crystal seed crystal 1 is remelted.

[0025] Among them, the upper end of the inner gate 23 of the seed crystal wax mold 21 can be directly connected to the casting wax mold, or connected to the crystal selection section and then connected to the casting wax mold.

[0026] (3) Preparation of ceramic shell: After the wax mold assembly is prepared, it is formed into a ceramic shell 3 through processes such as slurry application, sand application, drying, dewaxing, and sintering.

[0027] (4) Installing the single crystal seed crystal: The single crystal seed crystal 1 is installed in the seed crystal cavity 31 of the ceramic shell 3. During installation, the top inclined surface 11 of the seed crystal contacts the inclined surface of the seed crystal cavity 31 in the ceramic shell 3, and the bottom plane 12 of the single crystal seed crystal 1 directly contacts the water cooling plate 4 of the directional solidification furnace.

[0028] (5) Casting and directional solidification of castings: The alloy liquid is poured into the wax mold of the casting, and the casting is shaped and solidified in a specific direction. The top slope 11 of the single crystal seed crystal 1 is not completely remelted, the bottom plane 12 of the single crystal seed crystal and the side surface 13 of the seed crystal do not remelt, the top slope 11 is remelted in the part of the ingate 23 and the sprue, and there is no excess metal on the side surface 13 of the seed crystal.

[0029] (6) Recycling and reprocessing of single crystal seed crystals: The single crystal seed 1 is recycled, and only the top inclined surface 11 of the single crystal seed 1 needs to be reprocessed. After processing, the single crystal seed 1 is etched to observe the single crystal integrity of the single crystal seed 1 and remove the processing stress layer.

[0030] Example 1 This embodiment is based on the fabrication of turbine blades using DD6 single-crystal superalloy. The target casting is an aero-engine turbine blade with dimensions of 120mm blade length, 35mm maximum chord width, and 80mm blade height. The blade is fabricated using DD6 single-crystal superalloy (composition: Cr 9.5%, Co 8.0%, Mo 3.5%, Al 6.5%, Ti 2.0%, Ni balance, mass fraction). The specific steps are as follows: Step 1: Select 12mm DD6 single crystal high-temperature alloy rod and process the single crystal seed crystal using a five-axis CNC milling machine: the bottom plane is a circle with a diameter of 12mm, the angle between the top slope and the bottom plane is set to 30°, and the height H from the bottom plane to the lowest point of the top slope is 8mm; using the top slope as the positioning surface, use an X-ray crystal orientation analyzer to calibrate and ensure that the angle between the crystallographic direction of the seed crystal and the principal stress direction of the blade is ≤3°, thus completing the three-dimensional orientation control.

[0031] Step 2: Use injection molding to fabricate the seed crystal wax model and turbine blade wax model. The seed crystal wax model must be identical in shape and size to the single crystal seed crystal from Step 1. Assemble the wax models: Using the top slope of the seed crystal wax model as a reference, establish its three-dimensional orientation correspondence with the blade wax model using tooling fixtures, ensuring that the deviation between the blade chord direction and the seed crystal direction is ≤2°. Design the gating system: Set the ingate diameter to 6mm and the sprue diameter to 36mm; adjust the ingate position so that its extension line intersects the top slope of the seed crystal wax model, the distance between the ingate centerline and the center of the top slope is 2mm, and the angle between the ingate centerline and the top slope is 90°; connect a 50mm long, 8mm diameter crystal selection segment to the upper end of the ingate of the seed crystal wax model, and connect the upper end of the crystal selection segment to the blade wax model.

[0032] Step 3: Slurry Coating and Sanding: A silica sol-corundum sand system was used. After the first layer of slurry coating, 200-mesh fused alumina sand was applied; after the second layer of slurry coating, 100-mesh fused alumina sand was applied; and after the third layer of slurry coating, 80-mesh fused alumina sand was applied. Each layer of slurry coating was dried for 24 hours at 25℃ and 60% relative humidity. Dewaxing and Sintering: Dewaxing was performed using saturated steam at 120℃ for 2 hours to remove the wax mold; then, sintering was carried out in a high-temperature furnace at 1100℃ for 3 hours, followed by natural cooling to room temperature to obtain a dense ceramic shell 3. The overall thickness of the shell was measured to be approximately 8~10 mm, and the surface roughness of the seed crystal cavity Ra ≤ 1.6 μm.

[0033] Step 4: Place the single crystal seed crystal prepared in Step 1 into the seed crystal cavity of the ceramic shell. Use a feeler gauge to check the fit gap between the top bevel of the seed crystal and the inclined surface of the cavity, ensuring that the gap is ≤0.05mm. Place the ceramic shell containing the seed crystal into the directional solidification furnace, so that the bottom plane of the seed crystal is in direct contact with the water cooling plate of the furnace body. Adjust the position of the shell to ensure that the axis of the seed crystal coincides with the central axis of the furnace body.

[0034] Step 5: Alloy Melting: Melt DD6 alloy in a vacuum induction furnace, with the vacuum level controlled at 5×10⁻⁶. -3 Below Pa, heat to 1400℃ and hold for 10 minutes to ensure the alloy is completely melted and has a uniform composition. Casting and directional solidification: Pour the molten alloy into the ceramic mold at a speed of 150 mm / s. After casting, start the directional solidification system and control the cooling rate at 10℃ / min. After the casting has solidified for 2.5 hours until completely solidified, cool it in the furnace to below 500℃ before removing it from the furnace.

[0035] Step 6: Separation and Cleaning: Break the ceramic shell, remove the turbine blade casting and single crystal seed, and clean the remaining shell debris on the seed surface using a high-pressure water gun with a pressure of 0.8 MPa. Further Machining: Use a CNC milling machine to perform micro-machining on the top bevel of the seed crystal to remove the 0.2 mm thick remelted layer, ensuring that the deviation between the machined bevel dimension and the initial dimension is ≤0.03 mm.

[0036] Corrosion test: The processed single crystal seed crystal was placed in an 8% nitric acid alcohol solution for 4 minutes for corrosion. After being taken out, it was rinsed with clean water and dried. Observation confirmed that there were no impurities or grain boundaries, and the integrity of the single crystal seed crystal was qualified.

[0037] Example 2: This embodiment is based on the fabrication of guide vanes made of CMSX-4 single-crystal superalloy. The target casting is a gas turbine guide vane with dimensions of 80mm length, 40mm chord width, and 60mm blade height. It is fabricated using CMSX-4 single-crystal superalloy (composition: Cr 6.5%, Co 9.0%, Mo 0.6%, Al 5.6%, Ta 6.5%, Ni balance, mass fraction). The fabrication method is basically the same as in Example 1, with the key parameters adjusted as follows: Single crystal seed: The angle between the top bevel and the bottom plane is 25°, the height H=6mm, and the seed diameter is 10mm; Gating system: Ingate diameter 5mm, sprue diameter 30mm, distance between the center line of the ingate and the center of the top slope 1.5mm, angle 100°; Directional solidification: cooling rate 8℃ / min, alloy casting temperature 1380℃; Seed crystal reprocessing: The 0.15mm thick remelted layer is removed by processing. Corrosion testing is performed using a 10% nitric acid alcohol solution for 3 minutes.

[0038] Comparative Example 1 This comparative example uses a comparative experiment of the existing long seed crystal technology pointed out in the background art. To verify the improvement effect of the short seed crystal technology of the present invention, the turbine blade preparation of Example 1 is used as the benchmark, and the key parameters are as follows: Seed crystal design: A cylindrical seed crystal with a length of 40mm, a diameter of 12mm, and no top bevel, made of DD6 single crystal high-temperature alloy; Preparation process: The wax mold assembly has no special orientation positioning structure, and the inner gate is directly connected to the end face of the seed crystal wax mold; the directional solidification cooling rate and casting temperature are the same as in Example 1; Seed crystal recycling: After use, the surface of the seed crystal has an excess metal layer of 0.8~1.2mm thickness. The entire surface of the seed crystal needs to be cut to remove the surface layer with a thickness of 1.0mm.

[0039] Test case (1) Based on the preparation process of Example 1 and Comparative Example 1, the reusability of the single crystal seed crystal in the preparation process was measured, and the results are summarized in Table 1 below: Table 1. Results of reusability testing for different single-crystal seed crystals

[0040] As shown in Table 1 above, Example 1 is the single crystal seed proposed in this invention. Because the short seed only has partial remelting on the top bevel, only a small amount of bevel processing is required after each use, which is much less than the full surface processing of the existing long seed. Moreover, the overall size of the seed changes little, and it can be reused several times, significantly extending its service life. At the same time, the processing time is greatly shortened, reducing the seed recycling cost.

[0041] (2) Take the single crystal seed crystals of Examples 1-2 and Comparative Example 1, observe the remelting zone structure after use, and count the impurity rate, that is, the proportion of seed crystals containing impurities in the remelting zone. The impurity rate of the seed crystals in Examples 1 and 2 is 1.5%, while the impurity rate of the remelting zone of Comparative Example 1 is 60%.

[0042] Examples 1-2, through the design of the short seed crystal top slope and the optimization of the gating system, form a high temperature gradient of 22~25℃ / mm in the seed crystal remelting zone, which effectively suppresses dendrite fracture and the increase of undercooling, and significantly reduces the impurity rate, which is much lower than that of Comparative Example 1. This shows that the solution proposed in this invention can ensure the accurate maintenance of the crystal orientation of the casting.

[0043] (3) According to GB / T 4161-2007 "Test Method for Plane Strain Fracture Toughness of Metallic Materials (KIC)" and GB / T23802-2009 "Technical Conditions for High Temperature Alloy Castings", the mechanical properties of different castings in Examples 1-2 and Comparative Example 1 were determined, and the results are summarized in Table 2 below: Table 2. Test results of mechanical properties of different castings

[0044] As shown in Table 2 above, the castings prepared by the present invention in Examples 1-2 are free of impurity crystal defects and have precise crystal orientation. Their tensile strength, yield strength and creep strength at 1000℃ are all better than those of Comparative Example 1. At the same time, the casting qualification rate is significantly improved and is significantly higher than that of Comparative Example 1, which proves that the technical solution of the present invention can effectively improve the quality stability of castings.

[0045] (4) The single crystal seed crystal of Example 1 was pretreated by holding it at 800°C in air for 2 hours to form an oxide layer with a thickness of 5 μm. Then, a casting test was carried out according to the steps of Example 1 to test the orientation inheritance effect of the casting. The results are summarized in Table 3 below: Table 3. Experimental results on the influence of the oxide layer on the single crystal seed in Example 1.

[0046] As shown in Table 3 above, in this invention, the flowing high-temperature alloy liquid can decompose the oxide layer on the surface of the seed crystal. Even if the seed crystal has a 5μm oxide layer, the orientation deviation of the casting is only 2.5° and the content of oxide inclusions is low. In contrast, the oxide layer in the comparative example could not be effectively removed, resulting in an orientation deviation of 7.2° and a significant increase in the content of oxide inclusions. This proves that this invention can eliminate the influence of seed crystal oxidation on the quality of the casting.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of producing a single crystal superalloy casting from a reusable short seed, characterized in that, The single crystal seed crystal (1) is prepared, and the single crystal seed crystal (1) comprises a top inclined surface (11) and a bottom plane (12), the angle between the top inclined surface (11) and the bottom plane (12) is 10-40°, and the height of the single crystal seed crystal (1) from the bottom plane (12) to the lowest point of the top inclined surface (11) is 5-10 mm.

2. The method of producing a single crystal superalloy casting from a reusable short seed as recited in claim 1, wherein, The wax mold module for casting the casting comprises a seed crystal wax mold (21), the seed crystal wax mold (21) is matched with the shape and size of the single crystal seed crystal (1), and the three-dimensional orientation relationship between the seed crystal wax mold (21) and the casting is established with the top inclined surface (11) of the single crystal seed crystal (1) as the reference.

3. The method of producing a single crystal superalloy casting from a reusable short seed as recited in claim 2, wherein, The wax mold module further comprises a casting wax mold (22), an ingate (23) and a sprue (24), and the extension line of the ingate (23) intersects with the top inclined surface (11).

4. The method of producing a single crystal superalloy casting from a reusable short seed as recited in claim 3, wherein, The distance between the center line of the ingate (23) and the center of the top inclined surface (11) is less than or equal to 3 mm, and the angle between the center line of the ingate (23) and the top inclined surface (11) is 70-130°.

5. The method of producing a single crystal superalloy casting from a reusable short seed as recited in claim 3, wherein, The ratio of the diameter of the ingate (23) to the diameter of the seed crystal wax mold (21) is 1:1.5-5, and the ratio of the diameter of the sprue (24) to the diameter of the seed crystal wax mold (21) is 1:2-6.

6. The method of producing a single crystal superalloy casting from a reusable short seed according to any one of claims 3 to 5, characterized in that, The method comprises the following steps: S1, preparing a single crystal seed crystal: taking the top inclined surface as a positioning surface to prepare a single crystal seed crystal; S2, preparing a wax mold module: preparing a seed crystal wax mold matched with the size of the single crystal seed crystal, and providing a casting wax mold, an ingate and a sprue; S3, preparing a ceramic mold: adopting the processes of slurry hanging, sand spraying, drying, dewaxing and sintering to prepare a ceramic mold; S4, installing the single crystal seed crystal: installing the single crystal seed crystal in a seed crystal cavity of the ceramic mold; S5, casting forming and directional solidification: pouring an alloy liquid into the casting wax mold, and then performing casting forming and directional solidification to obtain a single crystal high-temperature alloy casting; S6, recycling and reprocessing the single crystal seed crystal: recycling the single crystal seed crystal, and reprocessing the top inclined surface of the single crystal seed crystal.

7. The method of producing a single crystal superalloy casting from a reusable short seed as defined in claim 6, characterized in that, In step S2, the upper end of the ingate of the seed crystal wax mold is directly connected with the casting wax mold, or is connected with a selected crystal section and then connected with the casting wax mold.

8. The method of producing a single crystal superalloy casting from a reusable short seed as recited in claim 6, wherein, In step S4, when the single crystal seed crystal is installed, the top inclined surface of the single crystal seed crystal is in contact with the inclined surface of the seed crystal cavity, and the bottom plane of the single crystal seed crystal is in contact with the water-cooled disc of the directional solidification furnace.

9. The method of producing a single crystal superalloy casting from a reusable short seed as recited in claim 6, wherein, In step S5, after directional solidification, the top inclined surface of the single crystal seed crystal is not completely remelted, the bottom plane and the seed crystal side surface of the single crystal seed crystal are not remelted, the part of the top inclined surface directly facing the ingate and the sprue is remelted, and the seed crystal side surface has no redundant metal.

10. A single crystal high-temperature alloy casting prepared by the preparation method in any one of claims 1 to 9.

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