Single crystal guide vane and precision casting method thereof

Abstract

The application discloses a single crystal guide vane and a precision casting method thereof, and aims to prepare a single crystal guide vane with the vane axial direction consistent with the single crystal direction 【001】 and without rim plate porosity. To this end, the single crystal guide vane precision casting method provided by the embodiment of the application has the following steps: the chilling plate of a directional solidification furnace is designed to be tiltable, a spiral selector wax mold is connected to the corner of the lower rim plate of a vane wax mold and the axial directions of the two are kept parallel, the crystal growth end of the spiral selector is vertically installed on the chilling plate during directional solidification, the spiral selector vertically grows the single crystal parallel to the vane axial direction along with the continuous horizontal descent of the chilling plate in the cold chamber of the directional solidification furnace, when the single crystal grows to the connecting transition section between the spiral selector and the lower rim plate of the vane, the chilling plate and the vane mold shell are slowly tilted, and then the descending speed is kept, so that the sequential solidification of the vane rim plate is ensured, and the generation of mixed crystals at the corner of the rim plate and the porosity on the surface of the rim plate are avoided.

Description

Technical Field

[0001] This invention belongs to the field of single-crystal high-temperature alloy preparation technology, and particularly relates to a single-crystal guide vane and its precision casting method. Background Technology

[0002] High-temperature alloy single-crystal guide vanes used in heavy-duty gas turbines are very difficult to manufacture as single-crystal castings due to their large size. Single-crystal blades generally require the crystal's

[001] orientation (dendritic axis) to be aligned with the blade's axis, which can be achieved by assembling the blades vertically. Figure 1 A crystal selector aligned with the axial direction is bonded to the lower end of the blade, and then the crystal selector is vertically mounted on a horizontal planar quench plate. Molten metal is poured into the inlet cup and flows through the runner into the mold shell, where it contacts the planar quench plate via the crystal selector. The heat flow from the crystal-forming section of the crystal selector enters the quench plate vertically downwards, while grains with the

[001] crystal orientation as their preferred direction grow upwards in the opposite direction to the heat flow. In other words, the single crystals grown in the crystal selector have a vertical

[001] crystal orientation and extend to the entire blade, making the blade axis aligned with the

[001] crystal orientation. This method is generally suitable for the production of single-crystal rotor blades with narrow blades and narrow rim plates. However, for guide blades, due to the two sudden expansions of the blade's outer contour in the directional solidification direction (from the crystal selector to the lower rim plate and from the blade body to the upper rim plate), the outwardly protruding rim plate edges are prone to supercooling during directional solidification, resulting in impurities. In addition, the upper surface of a wide, horizontally positioned flange will develop severe surface porosity because it will not receive proper shrinkage compensation.

[0003] To address the aforementioned issues of single-crystal integrity and porous edge surface in the guide vanes, the guide vanes can be tilted. Figure 2 This method ensures that the outer contour of the blade does not suddenly expand in the direction of directional solidification, allowing both the blade body and the edge plate to solidify sequentially in an upward oblique direction. This facilitates the expansion of single crystal growth throughout the blade, effectively eliminates impurities on the edge plate, and significantly reduces edge plate porosity. However, since the crystal selector under the blade is still installed vertically, the vertically growing dendrites grow into the obliquely placed blade, and the blade axis is no longer aligned with the dendrite axis, and therefore no longer aligned with the

[001] crystal orientation of the single crystal. This greatly affects the performance of the single crystal blade.

[0004] It should be noted that the guide vane's edge plate has a certain curvature, but it is generally regarded as a flat plate. Figure 1 and Figure 2 When placing the guide vanes at an angle, the tilt angle α of the rim plate should be large enough, generally α > 30°. Figure 2 Otherwise, if the edge plate is too flat, there is still a risk of impurities caused by overcooling of the molten metal. However, α cannot be too large either; generally, α < 60°, otherwise the tilt angle β of the blade or the crystal guide strip will be too small. Figure 2If β < 30°, there is a risk of impurities appearing on the crystal-guiding strips and blades.

[0005] To address the aforementioned issues, patent application number 202210652031.X discloses a method for precision casting of single-crystal guide vanes using a convex quench plate instead of a conventional planar quench plate, and employing an inclined mold assembly structure for the vanes. This not only ensures the sequential solidification of the guide vanes, avoiding impurities at the edge corners of the rim plate and porosity on the rim plate surface, but also guarantees that the vane axis aligns with the single-crystal

[001] crystal orientation, satisfying the requirement for the primary crystal orientation of single-crystal vanes. However, due to the temperature gradient within the cooling zone of the directional solidification furnace, the aforementioned patent still cannot guarantee that the vane axis aligns with the single-crystal

[001] crystal orientation, and the wax mold assembly is also very inconvenient. Summary of the Invention

[0006] The main objective of this invention is to provide a single-crystal guide blade and its precision casting method, which aims to produce a single-crystal guide blade with the blade axis aligned with the single-crystal

[001] crystal orientation and without loose rim plates.

[0007] To address this, one aspect of the present invention provides a precision casting method for single-crystal guide blades. The quench plate of the directional solidification furnace is designed to be tiltable. When the blade wax mold and the spiral crystal selector wax mold are combined, the spiral crystal selector wax mold is connected to the corner of the lower edge plate of the blade wax mold, maintaining their axial parallelism. The corresponding corners of the upper and lower edge plates of the blade wax mold are connected by crystal guide strips. During directional solidification, the crystal-starting end of the spiral crystal selector is vertically mounted on the quench plate. As the quench plate descends horizontally within the cold chamber of the directional solidification furnace, single crystals parallel to the blade axial direction grow vertically within the spiral crystal selector. When the single crystal grows to the transition section connecting the spiral crystal selector and the lower edge plate of the blade, the quench plate and the blade mold shell are slowly adjusted to tilt and then descended at the designed speed. This ensures the sequential solidification of the blade edge plates, preventing the formation of impurities at the edge plates and porosity on the edge plate surface.

[0008] Specifically, when the blade edge plate is a flat plate, after tilting the quench plate, keep the tilt angle θ of the quench plate unchanged, and continue to lower the blade mold shell until the blade casting is completely solidified; wherein, the tilt angle θ of the quench plate is controlled within the range of 30-60°.

[0009] Specifically, when the blade edge plate is an arc-shaped plate, the tilt angle θ of the quench plate needs to be dynamically adjusted according to the positional changes of the solidification interface;

[0010] During the process of the solidification interface moving from the transition section connecting the spiral crystal selector and the lower edge plate of the blade to the lower end of the upper edge plate of the blade, the tilt angle θ of the quench plate is continuously adjusted to keep the tilt angle α1 of the tangent of the lower edge plate of the blade ≥ 30°, while ensuring that the tilt angle β of the crystal guide strip below the blade edge plate is ≥ 30°.

[0011] During the process of the solidification interface moving from the lower end of the upper edge plate of the blade to the upper end of the lower edge plate of the blade, the tilt angle θ of the quench plate is continuously adjusted to keep the tilt angle α1 of the tangent of the lower edge plate of the blade ≥ 30°, while ensuring that the tilt angle α2 of the tangent of the upper edge plate of the blade ≥ 30°.

[0012] During the solidification process from the upper edge of the blade's lower edge plate to the completion of the entire blade's solidification, the tilt angle θ of the quench plate is continuously adjusted to maintain the tilt angle α2 of the upper edge plate's tangent at ≥30°.

[0013] Specifically, the directional solidification process includes:

[0014] The blade mold shell is placed on the quench plate of the directional solidification furnace;

[0015] The blade mold shell is raised into the hot chamber of the directional solidification furnace, the furnace door is closed and a vacuum is drawn, and the blade mold shell is preheated by turning on the power.

[0016] The high-temperature alloy ingot in the crucible above the hot chamber is induction melted and superheated, and then poured into the pouring cup of the blade mold shell. The molten metal enters the inner cavity of the mold shell and comes into contact with the upper surface of the chill plate through the spiral crystal selector, generating a chilled solidification layer that grows upward.

[0017] As the quench plate slowly descends horizontally, the blade mold shell enters the cold chamber, and the heat flow Q in the molten metal enters the quench plate vertically. The grains with the

[001] crystal orientation as the preferred direction grow vertically upward in the opposite direction to the heat flow Q. The single grains are selected by the spiral crystal selector and continue to grow to the transition section connecting the spiral crystal selector and the blade edge plate.

[0018] The cooling plate and mold shell are slowly adjusted to an inclined state by the drive system, and the descent speed is adjusted at the same time so that the solidification interface slowly enters the edge plate.

[0019] As the blade mold shell continues to descend, the solidification of the single crystal extends to the entire blade. At this point, although the macroscopic solidification direction of the molten metal is no longer parallel to the blade axis, the crystal orientation of the grown single crystal remains unchanged, that is, the axis of the single crystal blade remains parallel to the

[001] crystal orientation of the single crystal.

[0020] Specifically, the cooling plate is a copper water-cooled plate.

[0021] Another aspect of the present invention provides a single-crystal guide vane manufactured using the above-described precision casting method.

[0022] Compared with the prior art, at least one embodiment of the present invention has the following beneficial effects: The present invention first obtains a single crystal

[001] orientation consistent with the blade axis through vertical solidification, which satisfies the requirement for the primary crystal orientation of the single crystal blade; then, by using a cooling plate to drive the mold shell to tilt, the sequential solidification of the blade edge plate is ensured, avoiding the generation of impurities at the edge corners of the edge plate and the generation of porosity on the edge plate surface. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of an existing vertical single-crystal blade assembly tree;

[0025] Figure 2 This is a schematic diagram of an existing tilted single-crystal blade assembly tree;

[0026] Figure 3 This is a schematic diagram of the solidification interface in an embodiment of the present invention, before the quench plate is adjusted, when the solidification interface is located in the connection transition section.

[0027] Figure 4 This is a schematic diagram of the quench plate after tilting adjustment when the solidification interface is located in the connection transition section according to an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the quench plate adjustment when the solidification interface passes through the upper and lower edge plates of the blade simultaneously, according to an embodiment of the present invention.

[0029] Figure 6 This is a schematic diagram of the adjustment of the quench plate at the end of solidification of the lower edge plate of the blade according to an embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of the adjustment of the quench plate when the upper edge plate of the blade is solidified at the end of the embodiment of the present invention;

[0031] Figure 8 This is a schematic diagram of the blade casting after all solidification and quenching plates have been reset, according to an embodiment of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] The single-crystal guide blade precision casting method provided in this embodiment designs the quench plate of the directional solidification furnace to be tiltable. When the blade wax model and the spiral crystal selector wax model are combined, the spiral crystal selector wax model is connected to the corner of the lower edge plate of the blade wax model, and the axes of the two are kept parallel. The corresponding corners of the upper and lower edge plates of the blade wax model are connected by crystal guide strips. During directional solidification, the crystal-starting end of the spiral crystal selector is vertically installed on the quench plate. As the quench plate descends horizontally in the cold chamber of the directional solidification furnace, a single crystal grows vertically in the spiral crystal selector, parallel to the blade axis. When the single crystal grows to the transition section connecting the spiral crystal selector and the lower edge plate of the blade, the quench plate and the blade mold shell are adjusted to a tilted state, and then descended at the designed speed until the entire blade is solidified. This ensures the sequential solidification of the blade edge plate and avoids the generation of impurities at the edge plate corners and the porosity of the edge plate surface.

[0036] In this embodiment, the starting end of the spiral crystal selector is vertically mounted on the quench plate, allowing the heat flow Q in the molten metal to enter the quench plate vertically. Since the quench plate is horizontally set in the cold chamber of the directional solidification furnace, the heat flow Q in the molten metal is parallel to the temperature change direction in the cold chamber. This allows the molten metal to first solidify vertically, with the

[001] crystal orientation as the preferred direction, and the grains grow vertically upward in the opposite direction to the heat flow Q. Then, the quench plate drives the blade mold shell to tilt. As the quench plate continues to descend, the solidification of the single crystal extends to the entire blade. At this point, although the macroscopic solidification direction of the molten metal is no longer parallel to the blade axis, the crystal orientation of the grown single crystal remains unchanged. That is, the axis of the single crystal blade remains parallel to the

[001] crystal orientation of the single crystal. In addition, the tilting of the mold shell ensures the sequential solidification of the blade edge plates, avoiding the generation of impurities at the edge plate corners and the formation of porosity on the edge plate surface.

[0037] The blade to be prepared in this embodiment is a multi-unit integral casting guide blade with a large arc edge plate. For this guide blade, since the edge plate is not only wider, but also has a significantly larger arc, in order to ensure that no impurities appear during solidification, the tilt angle θ of the quench plate must be continuously and dynamically adjusted according to the position of the solidification interface. This results in the continuous adjustment of the tilt angles α1 and α2 of the tangents of the upper and lower edge plates and the tilt angle β of the crystal guide strip. In this way, the purpose of obtaining a single-crystal guide casting with crystal orientation parallel to the blade main axis and no impurities and loose edge plate is achieved.

[0038] The specific process of dynamically adjusting the tilt angle θ of the chiller plate is as follows;

[0039] During the process of the solidification interface moving from the transition section connecting the spiral crystal selector and the lower edge plate of the blade to the lower end of the upper edge plate of the blade, the quench plate tilt angle θ is continuously adjusted by the drive system of the directional solidification furnace to keep the tilt angle α1 of the tangent of the lower edge plate of the blade ≥ 30°, while ensuring that the tilt angle β of the crystal guide strip below the blade edge plate is ≥ 30°.

[0040] During the process of the solidification interface moving from the lower end of the upper edge plate of the blade to the upper end of the lower edge plate of the blade, the tilt angle θ of the quench plate is continuously adjusted to keep the tilt angle α1 of the tangent of the lower edge plate of the blade ≥ 30°, while ensuring that the tilt angle α2 of the tangent of the upper edge plate of the blade ≥ 30°.

[0041] During the solidification process from the upper edge of the blade's lower edge plate to the completion of the entire blade's solidification, the tilt angle θ of the quench plate is continuously adjusted to maintain the tilt angle α2 of the upper edge plate's tangent at ≥30°.

[0042] The specific process of the above-mentioned precision casting method for single-crystal guide vanes is as follows:

[0043] During production, the blade wax mold and the spiral crystal selector wax mold are first pressed out. The spiral crystal selector is then bonded to one corner of the blade wax mold edge plate, and the axis of the crystal selector is kept parallel to the axis of the blade body. The blade wax mold and the pouring cup wax mold are then connected to form a wax tree.

[0044] In the wax tree, thin wax strips are used to connect the corresponding corners of the upper and lower edge plates as crystal guides and shrinkage compensation strips. This serves to guide the single crystal growth of the lower edge plate to the upper edge plate, prevent the formation of impurities at the corners of the upper edge plate due to overcooling, and compensate for the shrinkage at the corners of the lower edge plate during solidification, preventing porosity defects. Additionally, ceramic rods are used to connect the cantilevered ends of the edge plates to the base plate to form support pillars.

[0045] The assembled wax mold is repeatedly dipped in slurry and sanded, and finally dewaxed and sintered to produce the corresponding blade mold shell.

[0046] The blade mold is vertically installed on the tiltable quench plate on the lifting platform of the directional solidification furnace. The blade mold is then raised to the hot chamber of the directional solidification furnace. The furnace door is closed and a vacuum is drawn. Power is then applied to preheat the blade mold.

[0047] The high-temperature alloy ingot in the crucible above the hot chamber is induction melted and superheated, then poured into the pouring cup of the blade mold shell. The molten metal enters the inner cavity of the mold shell and comes into contact with the upper surface of the chiller plate through the spiral crystal selector, generating a chilled solidification layer that grows upwards (e.g., Figure 3 (As shown).

[0048] As the quench plate slowly descends horizontally, the blade mold shell enters the cold chamber of the directional solidification furnace. The heat flow Q in the molten metal enters the quench plate vertically. Grains with the

[001] crystal orientation as their preferred direction grow vertically upward in the opposite direction to the heat flow Q. Individual grains are selected by the crystal selector and continue to grow to the transition section connecting the crystal selector and the lower edge plate of the blade (e.g., Figure 3 As shown in the figure, the solidification interface is located in the transition section connecting the spiral crystal selector and the lower edge plate of the blade. At this time, the

[001] crystal orientation in the crystal is vertical and parallel to the main axis of the blade.

[0049] Before reaching the lower edge plate of the blade, but before entering the transition section connecting the spiral crystal selector at the solidification front, the tiltable quench plate is slowly tilted (tilt angle θ) by the drive system, so that the tilt angle α1 of the bottom tangent of the lower edge plate increases from α0 to α1≥30°. Figure 4 At the same time, ensure that the tilt angle β of the crystal guide strip below the edge plate is ≥30°.

[0050] As the mold shell descends, the solidification interface enters the lower edge plate and continues to solidify obliquely upwards. θ is continuously adjusted to maintain α1 ≥ 30°, while ensuring the tilt angle β of the crystal guide strip below the edge plate is ≥ 30°, until the solidification interface enters the lower end of the upper edge plate. The mold shell continues to descend, and the solidification interface simultaneously enters the upper edge plate and continues to solidify obliquely upwards. Figure 5 ), continuously adjust θ, keeping α1 ≥ 30°, until the lower edge plate has solidified. Figure 6 During this process, it is important to maintain the tilt angle α2 of the upper edge plate tangent ≥ 30°. Generally, as long as the tilt angle α1 of the lower edge plate tangent is controlled to be > 30°, the tilt angle of the upper edge plate tangent will naturally satisfy the condition α2 > 30°. In this stage, because the crystal guide strip and adjacent blades have already solidified, although the tilt angle β decreases and does not satisfy β ≥ 30°, no more impurities will appear.

[0051] Continue lowering the shell while adjusting the θ angle to maintain α2 ≥ 30° until the upper edge plate has solidified. Figure 7 Adjust the θ angle back to 0, the mold shell returns to a vertical position and is completely lowered into the cold chamber, and the casting is completely solidified. Figure 8This process yields a single-crystal guide casting with crystal orientation parallel to the blade's main axis, and free of impurities and with a porous rim.

[0052] In this embodiment, during the solidification process of the blade casting (including upper and lower edge plates and blade body) Figures 4 to 7 Although the macroscopic solidification direction of the molten metal is no longer parallel to the main axis of the blade, the crystal orientation of the grown single crystal remains unchanged and is always consistent with the crystal orientation of the connecting transition section. That is, the axis of the single crystal blade remains parallel to the

[001] crystal orientation of the single crystal. During the single crystal solidification process of the blade, the single crystal growth starts from the oblique lower corner of the blade's lower edge plate. A portion continues to grow along the lower edge plate and sequentially grows into each blade body, while another portion grows into the upper edge plate along the crystal guide strip. The solidification process of the two edge plates and each blade body is always obliquely upward. Because it is constantly fed by liquid from the oblique upper side, the surface and interior of the two edge plates and each blade body will not produce severe porosity.

[0053] It should be explained that the control of α1 and finally α2 throughout the process is achieved through the adjustment of θ, which is automatically controlled by computer programming. The relationship between the position of the solidification interface within the casting and the shell-lowering distance is determined beforehand based on computer simulations and experimental measurements. The required inclination angles α1 and α2 of the edge plate tangent at that time are calculated based on the casting shape and incorporated into the control program. During production, as the shell-lowering distance changes, the tilt angle θ of the base plate is automatically adjusted to meet the process conditions of α1 ≥ 30° and α2 ≥ 30°. After the entire blade has solidified, the tilted quench plate tilts back to its original position, facilitating the removal of the mold shell for subsequent shell cleaning and other operations.

[0054] It is understandable that if the blade edge plate to be prepared is a flat plate structure, the quench plate only needs to be adjusted once, without dynamic adjustment based on the positional changes of the solidification interface. Specifically, when the single crystal grows to the transition section connecting the spiral crystal selector and the lower edge plate of the blade, the quench plate is tilted and the tilt angle θ of the quench plate is kept constant. The blade mold shell is then lowered until the entire blade casting is solidified. The tilt angle of the quench plate after tilting is preferably 45°, and can be adjusted within the range of 30° to 60°. Too high a tilt angle may pose a risk of collision between the mold shell and the inner wall of the directional solidification furnace. Too low a tilt angle will result in the upper surface of the wide edge plate not being compensated for shrinkage, leading to surface porosity.

[0055] Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0056] Furthermore, if the present invention discloses or relates to mutually fixedly connected components or structural parts, then unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured using a casting process) (except where it is obviously impossible to use an integral molding process).

[0057] Furthermore, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in this invention include states or shapes that are similar to, analogous to, or close to those states or shapes. Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured using a one-piece molding process.

[0058] The above embodiments are merely illustrative examples to clearly illustrate the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method of precision casting a single crystal guide vane, the method comprising: The quench plate of the directional solidification furnace is designed to be tiltable. When the blade wax model and the spiral crystal selector wax model are combined, the spiral crystal selector wax model is connected to the corner of the lower edge plate of the blade wax model, and the axes of the two are kept parallel. The corresponding corners of the upper and lower edge plates of the blade wax model are connected by crystal guide strips. During directional solidification, the crystal-starting end of the spiral crystal selector is vertically installed on the quench plate. As the quench plate descends horizontally in the cold chamber of the directional solidification furnace, single crystals parallel to the blade axis grow vertically in the spiral crystal selector. When the single crystal grows to the transition section connecting the spiral crystal selector and the lower edge plate of the blade, the quench plate and the blade mold shell are slowly adjusted to tilt and then descended at the designed speed to ensure the sequential solidification of the blade edge plates and avoid the generation of impurities at the edge plate corners and the porosity of the edge plate surface. ​ 2. The precision investment casting method of single crystal directing vanes as claimed in claim 1, characterized in that: When the blade edge plate is an arc-shaped plate, the tilt angle θ of the quench plate needs to be dynamically adjusted according to the positional change of the solidification interface, where; During the process of the solidification interface moving from the transition section connecting the spiral crystal selector and the lower edge plate of the blade to the lower end of the upper edge plate of the blade, the tilt angle θ of the quench plate is continuously adjusted to keep the tilt angle α1 of the tangent of the lower edge plate of the blade ≥ 30°, while ensuring that the tilt angle β of the crystal guide strip below the blade edge plate is ≥ 30°. During the process of the solidification interface moving from the lower end of the upper edge plate of the blade to the upper end of the lower edge plate of the blade, the tilt angle θ of the quench plate is continuously adjusted to keep the tilt angle α1 of the tangent of the lower edge plate of the blade ≥ 30°, while ensuring that the tilt angle α2 of the tangent of the upper edge plate of the blade ≥ 30°. During the solidification process from the upper edge of the blade's lower edge plate to the completion of the entire blade's solidification, the tilt angle θ of the quench plate is continuously adjusted to maintain the tilt angle α2 of the upper edge plate's tangent at ≥30°.

3. The precision investment casting method of single crystal directing struts as claimed in claim 1, wherein: When the blade edge plate is a flat plate, after tilting the quench plate, keep the tilt angle θ of the quench plate unchanged, and continue to lower the blade mold shell until the blade casting is completely solidified; the tilt angle θ of the quench plate is controlled within the range of 30-60°.

4. The precision casting method of single crystal directing vanes according to any one of claims 1 to 3, characterized in that: The blade wax model and the pouring cup wax model are connected to form a wax tree. In the wax tree, the corresponding corners of the upper and lower edge plates of the blade wax model are connected with crystal guide strips. Refractory coating is applied to the wax tree layer by layer. After drying and hardening, the wax is dewaxed and fired to obtain the blade mold shell.

5. The precision casting method of a single-crystal guide vane according to claim 4, characterized in that, directional The solidification process specifically includes: The blade mold shell is placed on the quench plate of the directional solidification furnace; The blade mold shell is raised into the hot chamber of the directional solidification furnace, the furnace door is closed and a vacuum is drawn, and the blade mold shell is preheated by turning on the power. The high-temperature alloy ingot in the crucible above the hot chamber is induction melted and superheated, and then poured into the pouring cup of the blade mold shell. The molten metal enters the inner cavity of the mold shell and comes into contact with the upper surface of the chill plate through the spiral crystal selector, generating a chilled solidification layer that grows upward. As the quench plate slowly descends horizontally, the blade mold shell enters the cold chamber, and the heat flow Q in the molten metal enters the quench plate vertically. The grains with the [001] crystal orientation as the preferred direction grow vertically upward in the opposite direction to the heat flow Q. The single grains are selected by the spiral crystal selector and continue to grow to the transition section connecting the spiral crystal selector and the blade edge plate. The cooling plate and mold shell are slowly adjusted to an inclined state by the drive system, and the descent speed is adjusted at the same time so that the solidification interface slowly enters the edge plate. As the blade mold shell continues to descend, the solidification of the single crystal extends to the entire blade. At this point, although the macroscopic solidification direction of the molten metal is no longer parallel to the blade axis, the crystal orientation of the grown single crystal remains unchanged, that is, the axis of the single crystal blade remains parallel to the [001] crystal orientation of the single crystal.

6. The precision investment casting method of single crystal directing struts as claimed in claim 4, characterized in that: The cooling plate is a copper water-cooled plate.

7. A single crystal guide vane characterized by: The single-crystal guide vane was prepared by the precision casting method according to any one of claims 1-6.

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