Design method of feeding structure for precision casting of plate-like member or structural part

Abstract

This invention relates to the field of precision casting technology for titanium-aluminum alloys, specifically disclosing a design method for a feeding structure in the precision casting of plate-shaped components or structural parts. The method includes: obtaining structural parameters of the plate-shaped component or structural part; determining the feeding weakness area during solidification based on the structural parameters; designing a feeding structure based on the location of the feeding weakness area and the structural parameters, wherein the feeding structure is a trapezoidal boss or feeding rib integrally connected to the plate-shaped component or structural part; wherein the local solidification modulus of the feeding structure is greater than the local solidification modulus of the feeding weakness area, causing the feeding structure to solidify later than the feeding weakness area during solidification, and forming a feeding channel for molten metal pointing from the feeding structure to the feeding weakness area. This method can achieve directional, continuous, and effective feeding, significantly reducing porosity and shrinkage defects in the precision casting of titanium-aluminum alloy plate structures.

Description

Technical Field

[0001] This invention relates to the field of precision casting technology for titanium-aluminum alloys, specifically to a precision casting method for titanium-aluminum alloys and a design method for a feeding structure for precision casting of plate-shaped components or structural parts of titanium-aluminum alloys. It is particularly suitable for the precision casting of plate-shaped components or complex components with plate-shaped structural parts of titanium-aluminum alloys, such as titanium-aluminum alloy turbine blades, casings with support plate structures, and annular components. Background Technology

[0002] Titanium-aluminum alloys (including TiAl, Ti2AlNb, Ti3Al alloys, etc.) are ideal materials for core components in the next generation of aerospace applications, occupying an irreplaceable and important position in this field due to their outstanding comprehensive performance. Their density is only about 1 / 2 to 2 / 3 that of traditional nickel-based superalloys, which can significantly reduce the weight of key equipment such as engines, helping to improve thrust-to-weight ratio and operational efficiency. They can withstand long-term operating temperatures of 650-900℃, possessing excellent high-temperature oxidation resistance and creep resistance, and can withstand the harsh service environment of hot-end components. At the same time, they have high specific strength and a low coefficient of expansion, ensuring the structural stability and service life of components under complex operating conditions. These unique advantages make them a core material for replacing traditional superalloys and achieving lightweight and high-efficiency upgrades in aerospace equipment, applied in hot-end components such as turbine blades, casings, diffusers, and aerospace rudders and cabins.

[0003] However, porosity defects have become a key bottleneck restricting the engineering application of titanium-aluminum alloys in precision casting. These alloys have melting points as high as 1500–1650℃, high viscosity in the liquid metal, and poor fluidity when filling the mold. For thin-walled, long, strip-shaped, plate-like, or support plate structures, problems such as incomplete filling and cold shuts are easily encountered. The core reason lies in their solidification characteristics—a volume shrinkage rate as high as 6–8%, far exceeding that of steel (approximately 3–5%) and aluminum (approximately 6%), and poor thermal conductivity (only 1 / 5 that of steel), leading to uneven temperature gradient distribution within the casting and difficulty in controlling the solidification sequence. In plate-like components such as turbine blades, at the transition points at both ends of support plate structures in complex structures, and at locations of abrupt thickness changes, the feeding channels often close prematurely, preventing sufficient liquid metal supply. This ultimately results in internal defects such as porosity and shrinkage cavities, severely disrupting the continuity of the alloy matrix. Figure 1 As shown.

[0004] Currently, industry solutions to this problem mostly focus on optimizing casting temperature, adjusting shell material, or improving heat treatment processes, lacking targeted design for plate-like components or structural parts, making it difficult to fundamentally solve the core contradiction of insufficient feeding. Traditional riser feeding solutions have drawbacks such as low feeding efficiency, large space occupation, and easy stress concentration, and do not scientifically match the size and position of the feeding structure, failing to adapt to the solidification law and stress characteristics of plate-like structures.

[0005] Therefore, in view of the above shortcomings, this invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a precision casting method for plate-shaped components or structural parts of titanium-aluminum alloys and a design method for feeding structures for precision casting, which can effectively eliminate or reduce casting defects of the aforementioned components or parts.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] The first aspect of this invention provides a design method for a feeding structure for precision casting of plate-shaped components or structural parts, used for precision casting of plate-shaped structural parts of titanium-aluminum alloy plate-shaped components or complex components, comprising the following steps: Obtain structural parameters of the plate-shaped structural parts of titanium-aluminum alloy plate components or complex components. The structural parameters include at least the plate thickness, plate length, and plate width of the plate component, or the plate thickness, plate length, plate width, end transition form, and local thickness variation parameters of the plate-shaped structural parts. Based on the structural parameters, determine the weak areas for shrinkage repair in the plate-shaped member or plate-shaped structure during the solidification process; Based on the location of the weak area to be compensated and the structural parameters, a compensation structure is designed. The compensation structure is a trapezoidal boss or compensation rib that is integrally connected with the plate-shaped member or plate-shaped structural part. The local solidification modulus of the feeding structure is greater than that of the weak feeding region, so that the feeding structure solidifies later than the weak feeding region during the solidification process, and forms a metal melt feeding channel from the feeding structure to the weak feeding region.

[0009] The design method for the feeding structure of precision casting of plate-shaped components or structural parts proposed in this invention may also have the following additional technical features: In some embodiments of the present invention, the weak feeding region is determined by geometric thermal analysis, solidification modulus analysis, temperature gradient analysis, solidification time analysis and / or numerical simulation.

[0010] In some embodiments of the present invention, the shrinkage-repairing weak area includes the central area in the length direction and the central area in the width direction of the plate-shaped member, as well as the end transition area and the local thickness abrupt change area of ​​the plate-shaped structure.

[0011] In some embodiments of the present invention, when the shrinkage-repairing weak area is the central region of a plate-shaped member, the shrinkage-repairing structure includes a trapezoidal boss disposed on the surface of the central region.

[0012] In some embodiments of the present invention, the bottom width of the trapezoidal boss is 1 / 3 to 1 / 2 of the plate width, the bottom length is 1 / 2 to 2 / 3 of the plate length, the top surface width is 1 / 2 to 3 / 4 of the bottom width, and the height is 1.5 to 2.5 times the plate thickness.

[0013] In some embodiments of the present invention, the cross-section and longitudinal section of the trapezoidal boss are both isosceles trapezoids, and the base angle of the isosceles trapezoid is in the range of 30°-60°.

[0014] In some embodiments of the present invention, the base angle of the isosceles trapezoid is 40°-50°.

[0015] In some embodiments of the present invention, the base angle of the isosceles trapezoid is 45°.

[0016] In some embodiments of the present invention, when the shrinkage-repairing weak area is the end transition area of ​​a plate-like structure, the shrinkage-repairing structure includes an extended shrinkage-repairing rib disposed outside the end transition area and integrally connected to the plate-like structure.

[0017] In some embodiments of the present invention, the thickness of the extended shrinkage rib is 1.5-2.5 times the plate thickness, the protrusion height is 1.5-3 times the plate thickness, and the length along the end extension direction is 1 / 2-2 / 3 of the plate width or plate height.

[0018] In some embodiments of the present invention, the local solidification modulus of the compensation structure is 1.2-2.5 times that of the local solidification modulus of the weak compensation region.

[0019] In some embodiments of the present invention, the shrinkage compensation structure and the plate-like member or plate-like structure portion are connected by a fillet, chamfer, or bevel transition.

[0020] In some embodiments of the present invention, the fillet radius is 0.2-1.0 times the plate thickness, or the chamfer angle ranges from 30° to 60°.

[0021] A second aspect of this invention also provides a precision casting method for titanium-aluminum alloy plate structures, comprising the following steps: The feeding structure is determined using any of the design methods described above; An integral wax model is prepared based on the plate-shaped component or plate-shaped structural portion and the shrinkage compensation structure; Precision casting of ceramic shells is prepared based on the overall wax model; Remove the overall wax mold and fire the ceramic shell to obtain a ceramic shell with a cavity; Titanium-aluminum alloy melt is poured into the ceramic mold under vacuum or protective atmosphere conditions, so that the feeding structure and the plate-shaped component or plate-shaped structure part are integrally cast and formed. After solidification and cooling, the mold shell is cleaned and the feeding structure is removed to obtain a titanium-aluminum alloy plate casting or a titanium-aluminum alloy complex structure casting with plate-like structural parts.

[0022] In some embodiments of the present invention, the titanium-aluminum alloy includes at least one of TiAl-based alloys, γ-TiAl alloys, Ti2AlNb alloys, Ti3Al alloys, and Ti-Al-Nb alloys.

[0023] In some embodiments of the present invention, the surface material of the ceramic shell includes at least one of yttrium oxide and zirconium oxide, and the backing material includes at least one of mullite, zirconium oxide, aluminum oxide, magnesium oxide, and yttrium oxide sand.

[0024] In some embodiments of the present invention, the casting temperature of the titanium-aluminum alloy melt is 1500℃-1700℃, and the preheating temperature of the ceramic shell is 500℃-1000℃.

[0025] The method provided by this invention obtains the structural parameters of plate-shaped components or plate-shaped structures of titanium-aluminum alloys, and accurately identifies the weak feeding areas during solidification, overcoming the shortcomings of traditional riser schemes that rely on experience and lack scientific basis. Unlike the crude approach of uniformly setting risers in traditional methods, this invention designs trapezoidal bosses or feeding ribs as feeding structures based on the location and structural parameters of the weak feeding areas, achieving a scientific match between the feeding structure and the casting structural parameters. Furthermore, by controlling the local solidification modulus of the feeding structure to be greater than that of the weak feeding area, the feeding structure solidifies later than the weak feeding area, thus forming a feeding channel of molten metal pointing from the feeding structure to the weak feeding area. This design fully utilizes the solidification characteristics of titanium-aluminum alloys—high melting point, high viscosity, and high volume shrinkage rate—allowing the liquid metal in the feeding structure to continuously supply the weak feeding area, effectively filling the gaps caused by solidification shrinkage, and fundamentally solving the core contradiction of insufficient feeding caused by premature closure of the feeding channel. Compared to traditional riser-based feeding methods, which suffer from low feeding efficiency, large space requirements, and susceptibility to stress concentration, this invention achieves scientific sequential solidification through modular control. This significantly suppresses internal defects such as porosity and shrinkage cavities in the precision casting of titanium-aluminum alloy plate structures, greatly improving the density and mechanical properties of the castings. Furthermore, this method is applicable to various titanium-aluminum alloy systems and plate components with different structural forms, demonstrating good versatility and industrial application value. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a state diagram of precision casting of plate-shaped structural parts in existing technology; Figure 2 This is a front view of the overall wax model of the plate-like structural parts and the external shape of the shrinkage ribs of the present invention. Figure 3 The left view of the overall wax model of the plate-like structure and the external shape of the shrinkage rib of the present invention; Figure 4 This is a bottom view of the overall wax model of the plate-like structural parts and the external shape of the shrinkage ribs of the present invention; Figure 5 This is a state diagram of the precision casting of the plate-shaped structure in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 10 - Plate-like structural parts, 20 - Shrinkage reinforcement. Detailed Implementation

[0029] Exemplary embodiments of the present invention will now be described in more detail. While exemplary embodiments of the present invention are shown herein, it should be understood that the invention can be implemented in many forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a fuller understanding of the invention and to fully convey its scope to those skilled in the art. It should be noted that, in the description of the present invention, the term "central region" refers to a region of a plate-like member or plate-like structure that is far from the heat dissipation boundary along its length and / or width, and is prone to isolated liquid phases and insufficient feeding; the term "end transition region" refers to a region where the plate-like structure connects to other structures, where the end shape undergoes abrupt changes, where there are local thickness variations, or where significant heat accumulation occurs. These regions can be determined based on geometric thermal analysis, solidification modulus analysis, temperature field analysis, or solidification simulation results.

[0030] This invention proposes a precision casting method for plate-shaped components or structural parts of titanium-aluminum alloys. The core of this method is to first determine the feeding structure through a feeding structure design method, and then perform precision casting based on the feeding structure. Specifically, it includes the following steps.

[0031] This invention provides a design method for a feeding structure for precision casting of plate-shaped components or structural parts. This method is applicable to the precision casting of plate-shaped structural parts of titanium-aluminum alloy plate-shaped components or complex components. Specifically, the design method for a feeding structure for precision casting includes the following steps.

[0032] S1: Obtain the structural parameters of the plate-shaped structural parts of titanium-aluminum alloy plate components or complex components.

[0033] Specifically, the structural parameters include at least the plate thickness, plate length, and plate width of plate-like components, or the plate thickness, plate length, plate width, end transition form, and local thickness variation parameters of plate-like structural parts. For example, for simple flat plate-like components, it is necessary to obtain their plate thickness, plate length, and plate width; for plate-like structural parts in complex components (such as turbine blade guard plates and combustion chamber liner plates of aero-engines), it is also necessary to further obtain their end transition form (such as circular arc transition, right angle transition, etc.) and local thickness variation parameters (such as abrupt thickness changes caused by stiffeners, bosses, etc.).

[0034] S2: Determine the weak areas for shrinkage repair in the plate-shaped member or plate-shaped structure during the solidification process based on the structural parameters.

[0035] The solidification characteristics of titanium-aluminum alloys make them prone to insufficient feeding defects in certain areas during casting. In this invention, these weak feeding areas can be determined through geometric thermal point analysis, solidification modulus analysis, temperature gradient analysis, solidification time analysis, and / or numerical simulation. Specifically, geometric thermal point analysis identifies areas with abrupt changes in cross-section or poor heat dissipation by analyzing the geometry of the casting; solidification modulus analysis calculates the ratio of volume to heat dissipation surface area (i.e., modulus) of each part of the casting, with areas having larger moduli solidifying more slowly; temperature gradient analysis and solidification time analysis predict the temperature field distribution and solidification sequence of the casting during solidification through heat transfer calculations or numerical simulation; numerical simulation can use casting simulation software such as ProCAST and AnyCasting to simulate and analyze the filling and solidification processes of the casting, accurately locating the weak feeding areas.

[0036] In some specific embodiments of the present invention, the weak areas for feeding include the central region along the length direction and the central region along the width direction of the plate-like component, as well as the end transition region and the local thickness abrupt change region of the plate-like structure. Among them, the central region along the length direction and the central region along the width direction are the regions farthest from the edge and with the longest heat dissipation path in the plate-like component, and solidify the latest, making them prone to becoming loose due to premature closure of the feeding channels; the end transition region, due to abrupt changes in geometry (such as transitioning from a plate to an arc or right angle), causes temperature field distortion and is prone to forming isolated liquid phase regions; the local thickness abrupt change region (such as the connection between the reinforcing rib, boss, etc. and the plate) is prone to forming weak areas for feeding due to inconsistent solidification rates caused by thickness differences.

[0037] S3: Based on the location of the weak area to be compensated and the structural parameters, design a compensation structure, wherein the compensation structure is a trapezoidal boss or compensation rib integrally connected with the plate-shaped member or plate-shaped structural part.

[0038] The key to the design of the feeding structure lies in the fact that the local solidification modulus of the feeding structure is greater than that of the weak feeding region. This causes the feeding structure to solidify later than the weak feeding region, forming a feeding channel for molten metal from the feeding structure to the weak feeding region. In other words, the feeding structure is equivalent to a "thermal storage tank." Due to its larger size and stronger heat storage capacity, its solidification rate is slower than that of the weak feeding region. Therefore, when the weak feeding region solidifies and shrinks, the molten metal that remains liquid in the feeding structure can continuously supply the weak feeding region through the feeding channel, effectively filling the gaps created by solidification shrinkage.

[0039] In some specific embodiments of the present invention, the local solidification modulus of the compensation structure is 1.2-2.5 times the local solidification modulus of the weak compensation area. If the modulus ratio is less than 1.2, the compensation capacity of the compensation structure is insufficient and cannot effectively compensate for shrinkage; if the modulus ratio is greater than 2.5, the size of the compensation structure is too large, increasing the workload of subsequent cutting and potentially introducing significant stress concentration. Preferably, the modulus ratio is 1.5-2.0 times.

[0040] For different types of weak areas requiring reinforcement, this invention provides different reinforcement structure design schemes.

[0041] Trapezoidal boss design for the central area When the weak area to be compensated is the central area of ​​a plate-shaped member (including the central area in the length direction and / or the central area in the width direction), the compensation structure includes a trapezoidal boss disposed on the surface of the central area.

[0042] In some specific embodiments of the present invention, the trapezoidal boss has a bottom width of 1 / 3 to 1 / 2 of the plate width, a bottom length of 1 / 2 to 2 / 3 of the plate length, a top surface width of 1 / 2 to 3 / 4 of the bottom width, and a height of 1.5 to 2.5 times the plate thickness. The determination of these dimensional ranges is based on the following considerations: the bottom width and bottom length determine the contact area between the trapezoidal boss and the plate-like component; if too small, the shrinkage compensation effect is insufficient; if too large, it increases the difficulty of subsequent cutting and material waste; the top surface width affects the heat storage capacity and solidification rate of the trapezoidal boss; and the height directly affects the modulus of the shrinkage compensation structure. Preferably, the bottom width is 1 / 2 of the plate width, the bottom length is 2 / 3 of the plate length, the top surface width is 2 / 3 of the bottom width, and the height is twice the plate thickness.

[0043] In some specific embodiments of the present invention, the cross-section and longitudinal section of the trapezoidal boss are both isosceles trapezoids, and the base angle of the isosceles trapezoid ranges from 30° to 60°. The base angle affects the lateral slope of the trapezoidal boss, and thus affects the unobstructed flow of the feeding channel and stress distribution. If the base angle is too small (less than 30°), the feeding channel is too narrow, which is not conducive to the flow of molten metal; if the base angle is too large (greater than 60°), the trapezoidal boss tends to be rectangular, which is not conducive to demolding and easily causes stress concentration. In some specific embodiments of the present invention, the base angle of the isosceles trapezoid is 40°-50°. In some specific embodiments of the present invention, the base angle of the isosceles trapezoid is 45°. A 45° base angle is the optimal choice between feeding effect and process feasibility.

[0044] Design of shrinkage reinforcement in the end transition area When the weak area to be compensated is the end transition area of ​​the plate-like structure 10, the compensation structure includes an extended compensation rib 20 disposed on the outside of the end transition area and integrally connected to the plate-like structure, as shown in the reference. Figure 2-4 As shown.

[0045] In some specific embodiments of the present invention, the thickness of the extended shrinkage rib is 1.5-2.5 times the plate thickness, the protrusion height is 1.5-3 times the plate thickness, and the length along the extension direction of the end is 1 / 2-2 / 3 of the plate width or plate height. The weak shrinkage in the end transition region is mainly due to temperature field distortion caused by abrupt geometric changes. The extended shrinkage rib, by adding a "heat storage block" on the outer side of the end, slows down the solidification rate of the end region, ensuring that the end transition region receives sufficient molten metal supply during solidification. The thickness, protrusion height, and extension length of the shrinkage rib together determine its heat storage capacity and shrinkage capability; the above-mentioned size range is a preferred range verified through extensive experiments.

[0046] Transition connection between the shrinkage compensation structure and the plate-like member In some specific embodiments of the present invention, the feeding structure and the plate-like member or plate-like structure portion are connected by a fillet, chamfer, or bevel. The purpose of the transition connection is to avoid stress concentration caused by geometric abrupt changes and to prevent the generation of casting cracks.

[0047] In some specific embodiments of the present invention, the fillet radius is 0.2-1.0 times the plate thickness, or the chamfer angle ranges from 30° to 60°. If the fillet radius is too small, the stress concentration relief effect is poor; if it is too large, it occupies space and affects the shrinkage compensation effect. The same applies to the chamfer angle. Preferably, the fillet radius is 0.5 times the plate thickness, the chamfer angle is 45°, and the chamfer distance is 0.5 times the plate thickness.

[0048] After determining the feeding structure through the above design method, the present invention also provides a precision casting method for titanium-aluminum alloy plate components or structural parts.

[0049] S1: Prepare an integral wax model based on the plate-shaped component or plate-shaped structure and the shrinkage compensation structure.

[0050] During the overall wax model manufacturing stage, based on the three-dimensional models of the aforementioned feeding structure and plate-like structure, a one-piece integral wax model is prepared using a wax injection process. This integral wax model includes wax models of the plate-like structure and wax models of the feeding structure (trapezoidal boss wax models and / or feeding rib wax models) located in the weak feeding areas, forming a complete unit. The dimensional accuracy of the wax model is controlled within ±0.05mm to ensure the dimensional accuracy of the final casting.

[0051] S2: Prepare a precision-cast ceramic shell based on the overall wax model.

[0052] A ceramic shell is formed on the surface of a wax model using a multi-layer coating process. In some specific embodiments of the invention, the surface layer material of the ceramic shell includes at least one of yttrium oxide and zirconium oxide, and the back layer material includes at least one of mullite, zirconium oxide, alumina, magnesium oxide, and yttrium oxide sand. The surface layer material is in direct contact with the titanium-aluminum alloy melt and must have good chemical inertness and thermal shock resistance; yttrium oxide and zirconium oxide are preferred surface layer materials. The back layer material must provide sufficient shell strength; mullite, zirconium oxide, alumina, magnesium oxide, and yttrium oxide sand can all be used as back layer materials. After drying and hardening, a shell with sufficient strength is obtained.

[0053] S3: Remove the overall wax mold and fire the ceramic shell to obtain a ceramic shell with a cavity.

[0054] The dewaxing stage uses high-pressure steam dewaxing (temperature approximately 150-180℃, pressure approximately 0.6-0.8MPa) to completely remove the wax mold. It is then fired (temperature approximately 800-1000℃, held for 1-2 hours) to give the ceramic shell sufficient strength and permeability, while thoroughly removing residual wax and volatiles, forming a hollow casting mold.

[0055] S4: Under vacuum or protective atmosphere conditions, titanium-aluminum alloy melt is poured into the ceramic mold shell to integrally cast the feeding structure with the plate-shaped component or plate-shaped structure part.

[0056] In some specific embodiments of the present invention, the titanium-aluminum alloy includes at least one of TiAl-based alloys, γ-TiAl alloys, Ti2AlNb alloys, Ti3Al alloys, and Ti-Al-Nb alloys. All of the above alloys belong to the category of titanium-aluminum alloys, have similar solidification characteristics, and can all be precision cast using the method of the present invention.

[0057] In some specific embodiments of the present invention, the pouring temperature of the titanium-aluminum alloy melt is 1500℃-1700℃, and the preheating temperature of the ceramic mold shell is 500℃-1000℃. Titanium-aluminum alloys have a high melting point (approximately 1500-1650℃), and the pouring temperature needs to ensure that the alloy melt has good fluidity and can fully fill the mold cavity. Preheating the mold shell slows down the cooling rate of the alloy melt, which is beneficial for obtaining a complete casting shape and reduces the damage to the mold shell caused by thermal shock. Preferably, the pouring temperature is 1550-1650℃, and the mold shell preheating temperature is 700-900℃.

[0058] During the aforementioned casting and solidification process, because the local solidification modulus of the feeding structure is greater than that of the weak feeding area, the feeding structure solidifies later than the weak feeding area. This forms a feeding channel for the molten metal from the feeding structure to the weak feeding area, allowing the liquid metal in the feeding structure to continuously supply the weak feeding area, effectively filling the voids caused by solidification shrinkage. After solidification and cooling, the furnace is cooled to below 200°C before being opened.

[0059] S5: After solidification and cooling, clean the mold shell and remove the feeding structure to obtain a titanium-aluminum alloy plate casting or a titanium-aluminum alloy complex structure casting with plate-like structures.

[0060] After the casting solidifies and cools, the mold shell is cleaned mechanically (e.g., vibratory shell removal, sandblasting, etc.). Then, trapezoidal bosses and / or shrinkage ribs are removed using wire cutting, electrical discharge machining, or machining. After cutting, the cutting marks are ground smooth to achieve a flat casting surface. The final product is a high-density, high-mechanical-property, and high-dimensional-accuracy titanium-aluminum alloy plate casting or a complex titanium-aluminum alloy casting with plate-like structural parts.

[0061] Example This embodiment uses a turbine blade guard plate support plate for an aero-engine as the application object, and employs the method of this invention for precision casting. The casting material is Ti-48Al-2Cr-2Nb alloy (belonging to γ-TiAl alloy), and the structural parameters of the support plate are: plate thickness h=6mm, plate length l=400mm, plate width w=150mm, with rounded transitions at both ends (radius R=10mm), requiring a porosity ≤0.5%. The specific implementation steps are as follows: Step 1: Obtain structural parameters Based on the actual working conditions of the support plate, the key structural parameters are as follows: plate thickness h = 6mm, plate length l = 400mm, plate width w = 150mm, and the end transition is a circular arc transition (radius R = 10mm), with no local thickness variation. The support plate belongs to a typical thin-walled long strip support plate structure.

[0062] Step 2: Identify and fill weak areas The filling and solidification process of the support plate was numerically simulated and analyzed using ProCAST casting simulation software. The simulation results show that the central region along the length of the support plate (approximately 200 mm from each end) has the longest solidification time and is the last region to solidify. The arc transition regions at both ends, due to abrupt geometric changes leading to temperature field distortion, also pose a certain risk of insufficient feeding. Therefore, the weak feeding areas are identified as the central region along the length of the support plate and the arc transition regions at both ends.

[0063] Step 3: Design the shrinkage compensation structure Based on the location and structural parameters of the weak areas to be repaired, the repair structure is designed as follows: To address weak areas in the central region, a trapezoidal boss is installed at the center of the support plate along its length (200mm from each end). The base width of the trapezoidal boss is half the plate width (75mm); the base length is two-thirds the plate length (267mm); the top surface width is two-thirds the base width (50mm); and the height is twice the plate thickness (12mm). Both the cross-section and longitudinal section of the trapezoidal boss are isosceles trapezoids with a base angle of 45°. The connection between the trapezoidal boss and the support plate uses a chamfered transition with a chamfer angle of 45° and a chamfer distance of 3mm.

[0064] For the weak areas in the arc transition region at both ends, extended shrinkage ribs are installed on the outer sides of both ends of the support plate. The thickness of the shrinkage rib is twice the plate thickness, i.e., 12mm; the protrusion height is twice the plate thickness, i.e., 12mm; and the length along the outer extension direction at the end is half the plate width, i.e., 75mm. The connection between the shrinkage rib and the support plate is a rounded transition, with a radius of 0.5 times the plate thickness, i.e., 3mm.

[0065] Calculations show that the local solidification modulus of the trapezoidal boss is 1.8 times that of the local solidification modulus of the shrinkage-repairing weak area, and the local solidification modulus of the shrinkage-repairing rib is 1.6 times that of the local solidification modulus of the shrinkage-repairing weak area. Both meet the requirement that the local solidification modulus of the shrinkage-repairing structure is greater than that of the local solidification modulus of the shrinkage-repairing weak area.

[0066] Step 4: Prepare the overall wax model Based on the aforementioned three-dimensional model of the shrinkage compensation structure and support plate, a one-piece wax model was prepared using a wax injection process. This one-piece wax model includes the support plate wax model, the trapezoidal boss wax model in the central area, and the shrinkage compensation rib wax models in the transition areas at both ends, forming a complete unit. The dimensional accuracy of the wax model was controlled within ±0.05mm.

[0067] Step 5: Preparation of ceramic shell Ceramic shells were prepared using investment casting. Yttrium oxide was used as the surface layer material, and mullite as the backing layer material. After multiple layers of coating and drying hardening, a shell with sufficient strength was obtained. The total thickness of the shell was controlled within 6-8 mm.

[0068] Step 6: Dewaxing and Firing High-pressure steam dewaxing (170℃, 0.7MPa) is used to completely remove the wax mold. The mold is then fired (900℃, held for 1.5 hours) to give the ceramic shell sufficient strength and permeability, forming a hollow casting mold.

[0069] Step 7: Pouring The Ti-48Al-2Cr-2Nb alloy was melted under vacuum at a casting temperature of 1600℃. The ceramic mold shell was preheated to 800℃. The molten alloy was poured into the ceramic mold shell under vacuum, filling the cavity completely. After casting, the furnace was cooled to below 200℃ before opening.

[0070] During the solidification process described above, the trapezoidal bosses and shrinkage ribs, due to their larger size and stronger heat storage capacity, solidify later than the central area and end transition area of ​​the support plate. This forms a shrinkage channel from the shrinkage structure to the weak shrinkage area, allowing the liquid metal in the shrinkage structure to continuously supply the weak shrinkage area, effectively filling the gaps caused by solidification shrinkage.

[0071] Step 8: Clean the shell and remove the feeding structure. After the casting solidifies and cools, the ceramic mold shell is cleaned using a vibration-assisted shell removal method. Then, the trapezoidal boss and shrinkage ribs are removed using wire cutting, and the cutting marks are ground smooth afterward. The casting is then optimized through heat treatment: hot isostatic pressing (1200℃, 150MPa, 2 hours); solution treatment (1250℃, 1 hour, air cooling); and finally, aging treatment (900℃, 4 hours, air cooling). The resulting support plate casting is then obtained.

[0072] Performance testing The performance of the finally prepared Ti-48Al-2Cr-2Nb alloy support plate was tested, and the results are as follows: 1. Density test: The density of the support plate was tested using the Archimedes drainage method. The density of the support plate reached 99.7%, and the porosity was only 0.2%. After X-ray and ultrasonic testing, there were no obvious defects such as shrinkage cavities and cracks, which met the design requirements (porosity ≤ 0.5%).

[0073] 2. Mechanical property testing: The tensile strength at room temperature is 645 MPa, and the elongation is 4.0%; the tensile strength at 800℃ is 475 MPa, and the elongation is 2.5%; the weight gain due to oxidation after 100 hours of heat treatment at 800℃ is ≤0.05 mg / cm², indicating good high-temperature oxidation resistance.

[0074] 3. Dimensional accuracy inspection: The key dimensions of the support plate are controlled within ±0.1mm, and the flatness error is ≤0.05mm, which meets the assembly and use standards of turbine blade guard plate support plates for aero-engines.

[0075] To verify the technical effectiveness of the method of the present invention, a control example was set up for comparison.

[0076] The control example uses a traditional riser feeding scheme (please provide the control scheme and the density test, mechanical property test and dimensional accuracy test results).

[0077] A comparison of the embodiments and comparative examples shows that, after adopting the central trapezoidal feeding body, the porosity of the support plate in this invention is reduced from 1.6% in the traditional riser scheme to 0.2%, the room temperature tensile strength is increased from 590MPa to 645MPa, and the high-temperature tensile strength at 800℃ is increased from 430MPa to 475MPa. The accuracy and flatness of key dimensions are also significantly improved. The results indicate that the feeding structure of this invention can significantly improve the solidification feeding effect of titanium-aluminum alloy plate components, reduce porosity and shrinkage defects, and improve the overall performance of castings. For details, please refer to... Figure 1 and Figure 5 .

[0078] This embodiment demonstrates that by obtaining the structural parameters of a titanium-aluminum alloy plate-shaped component and determining the weak areas for feeding during the casting process, a feeding structure is then set in the weak areas based on the structural parameters. The casting wax model and the feeding structure wax model are integrally formed into a single wax model for precision casting. This ensures that the feeding structure solidifies later than the weak areas, thus forming an effective feeding channel. This method can precisely control porosity defects in the precision casting of titanium-aluminum alloy plate-shaped structures. After the feeding structure is subsequently removed, castings with high density, excellent mechanical properties, and high dimensional accuracy can be obtained.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for a feeding structure for precision casting of plate-shaped components or structural parts, characterized in that, Precision casting for plate-shaped structural parts of titanium-aluminum alloy plate components or complex components includes the following steps: Obtain structural parameters of the plate-shaped structural parts of titanium-aluminum alloy plate components or complex components. The structural parameters include at least the plate thickness, plate length, and plate width of the plate component, or the plate thickness, plate length, plate width, end transition form, and local thickness variation parameters of the plate-shaped structural parts. Based on the structural parameters, determine the weak areas for shrinkage repair in the plate-shaped member or plate-shaped structure during the solidification process; Based on the location of the weak area to be compensated and the structural parameters, a compensation structure is designed. The compensation structure is a trapezoidal boss or compensation rib that is integrally connected with the plate-shaped member or plate-shaped structural part. The local solidification modulus of the feeding structure is greater than that of the weak feeding region, so that the feeding structure solidifies later than the weak feeding region during the solidification process, and forms a metal melt feeding channel from the feeding structure to the weak feeding region.

2. The design method according to claim 1, characterized in that, The weak areas in the feeding process were determined through geometric thermal analysis, solidification modulus analysis, temperature gradient analysis, solidification time analysis, and / or numerical simulation.

3. The design method according to claim 1, characterized in that, The weak areas to be compensated for include the central area in the length direction and the central area in the width direction of the plate-shaped member, as well as the end transition area and the local thickness change area of ​​the plate-shaped structure.

4. The design method according to claim 3, characterized in that, When the weak area to be compensated is the central region of a plate-shaped member, the compensation structure includes a trapezoidal boss disposed on the surface of the central region.

5. The design method according to claim 4, characterized in that, The trapezoidal boss has a bottom width of 1 / 3 to 1 / 2 of the plate width, a bottom length of 1 / 2 to 2 / 3 of the plate length, a top surface width of 1 / 2 to 3 / 4 of the bottom width, and a height of 1.5 to 2.5 times the plate thickness.

6. The design method according to claim 4 or 5, characterized in that, The trapezoidal boss has an isosceles trapezoid in both its cross-section and longitudinal section, and the base angle of the isosceles trapezoid is in the range of 30°-60°.

7. The design method according to claim 6, characterized in that, The base angles of the isosceles trapezoid are 40°-50°.

8. The design method according to claim 7, characterized in that, The base angle of the isosceles trapezoid is 45°.

9. The design method according to claim 3, characterized in that, When the weak area to be compensated is the end transition area of ​​a plate-like structure, the compensation structure includes an extended compensation rib disposed on the outside of the end transition area and integrally connected to the plate-like structure.

10. The design method according to claim 9, characterized in that, The thickness of the extended shrinkage rib is 1.5-2.5 times the plate thickness, the protrusion height is 1.5-3 times the plate thickness, and the length along the end extension direction is 1 / 2-2 / 3 of the plate width or plate height.

11. The design method according to claim 1, characterized in that, The local solidification modulus of the compensation structure is 1.2-2.5 times that of the local solidification modulus of the weak compensation area.

12. The design method according to claim 1, characterized in that, The shrinkage compensation structure is connected to the plate-shaped member or plate-shaped structure part by a rounded corner, chamfer, or bevel transition.

13. The design method according to claim 12, characterized in that, The fillet radius is 0.2-1.0 times the plate thickness, or the chamfer angle ranges from 30° to 60°.

14. A precision casting method for titanium-aluminum alloys, characterized in that, Includes the following steps: The feeding structure is determined using the design method described in any one of claims 1-13; An integral wax model is prepared based on the plate-shaped component or plate-shaped structural portion and the shrinkage compensation structure; Precision casting of ceramic shells is prepared based on the overall wax model; Remove the overall wax mold and fire the ceramic shell to obtain a ceramic shell with a cavity; Titanium-aluminum alloy melt is poured into the ceramic mold under vacuum or protective atmosphere conditions, so that the feeding structure and the plate-shaped component or plate-shaped structure part are integrally cast and formed. After solidification and cooling, the mold shell is cleaned and the feeding structure is removed to obtain a titanium-aluminum alloy plate casting or a titanium-aluminum alloy complex structure casting with plate-like structural parts.

15. The precision casting method according to claim 14, characterized in that, The titanium-aluminum alloys include at least one of TiAl-based alloys, γ-TiAl alloys, Ti2AlNb alloys, Ti3Al alloys, and Ti-Al-Nb alloys.

16. The precision casting method according to claim 14, characterized in that, The surface material of the ceramic shell includes at least one of yttrium oxide and zirconium oxide, and the back material includes at least one of mullite, zirconium oxide, aluminum oxide, magnesium oxide, and yttrium oxide.

17. The precision casting method according to claim 14, characterized in that, The casting temperature of the titanium-aluminum alloy melt is 1500℃-1700℃, and the preheating temperature of the ceramic mold shell is 500℃-1000℃.

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