A method for producing a large-size single crystal turbine blade

Abstract

The application discloses a large-size single crystal turbine blade preparation method and relates to the technical field of precision casting of nickel-based single crystal high-temperature alloy, which comprises the following steps: step 1, establishing all or part of a casting simulation model of a single crystal gas turbine blade in modeling software; step 2, importing the casting simulation model established in step 1 into simulation software and performing mesh division on the casting simulation model; step 3, setting directional solidification process parameters of the single crystal gas turbine blade in the simulation software; step 4, performing temperature field simulation in the simulation software according to the directional solidification process parameters in step 3; and step 5, analyzing the simulation result in step 4, optimizing the pulling speed in the directional solidification process parameters, and repeating step 4 to complete process verification. Through simulation technology and simulation temperature field results, the application can determine the causes of heterogeneous crystal defects, provide accurate data support for the optimization of the pulling speed, and greatly shorten the research and development cycle.

Description

Technical Field

[0001] This invention relates to the field of precision casting technology for nickel-based single-crystal superalloys, and specifically to a method for preparing large-size single-crystal turbine blades. Background Technology

[0002] As a core hot-end component of heavy-duty gas turbines, single-crystal turbine rotor blades operate under complex conditions such as high temperature and high pressure for extended periods. With the continuous increase in power output of heavy-duty gas turbines to the 400MW class, turbine rotor blade sizes can reach 300-350mm. Due to temperature resistance constraints, the first-stage rotor blades for 400MW-class turbines must be manufactured using single-crystal technology. Casting cracks and impurity crystals are key bottlenecks restricting the engineering application of large-size single-crystal blades. Traditional investment casting is costly and time-consuming, severely hindering the iteration and development of domestically produced heavy-duty gas turbines.

[0003] Therefore, this application is based on the nickel-based single-crystal high-temperature alloy DD451 independently developed by the applicant's team. Based on solidification process simulation, parameter inversion optimization is used to reduce the formation of impurity crystal defects, aiming to improve the yield of single-crystal gas turbine blades. This has important engineering application value and practical significance for the rapid development of heavy-duty gas turbines.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing large-size single-crystal turbine blades to solve the problems existing in the prior art. By using simulation technology and combining the simulation temperature field results, the causes of impurity crystal defects are clarified, providing accurate data support for the optimization of the pulling speed and significantly shortening the research and development cycle.

[0006] To achieve the above objectives, the present invention provides the following solution: A method for fabricating large-size single-crystal turbine blades includes the following steps: Step 1: Create all or part of the casting simulation model of the single-crystal gas turbine blade in the modeling software; Step 2: Import the casting simulation model created in Step 1 into the simulation software, and mesh the casting simulation model; Step 3: Set the directional solidification process parameters for single-crystal gas turbine blades in the simulation software; Step 4: Perform temperature field simulation in simulation software based on the directional solidification process parameters in Step 3; Step 5: Analyze the simulation results from Step 4 and optimize the pulling speed in the directional solidification process parameters. Repeat Step 4 to complete the process verification.

[0007] As one implementation method, the casting simulation model in step 1 includes at least nine components: single-crystal gas turbine blades, simplified core, gating system, crystal guide bar, pouring cup, spiral crystal selector, copper cold plate, furnace body, and mold shell.

[0008] As one implementation method, in step 2, after the casting simulation model is imported into the simulation software, it is checked whether the casting simulation model has any intersections and whether it is assembled, so as to meet the requirements of mesh division.

[0009] As one implementation method, in step 2, when dividing the mesh, different sizes of meshes are used to divide different areas in the casting simulation model.

[0010] As one implementation method, in step 2, after the single-crystal gas turbine blade is successfully meshed, a mold shell in the casting simulation model is created, and a mesh is generated for the mold shell.

[0011] As one implementation method, step 3, setting the directional solidification process parameters for the single-crystal gas turbine blades includes: setting gravity for the casting simulation model; assigning material properties to each individual in the casting simulation model; setting the heat exchange interface between adjacent individuals and the heat transfer coefficient corresponding to each interface; and the pulling action during the directional solidification process is achieved by moving the furnace body upward.

[0012] As one implementation method, the modeling software used is UG.

[0013] As one implementation method, the simulation software uses ProCAST.

[0014] Compared with the prior art, the present invention has the following technical effects: 1. This invention precisely addresses the manufacturing limitations of DD451 large-size single-crystal gas turbine blades. Through simulation technology and combined with simulation temperature field results, it clarifies the causes of impurity crystal defects, providing precise data support for optimizing the pulling speed and significantly shortening the research and development cycle.

[0015] 2. This invention specifically optimizes the pulling speed, effectively improving the problem of uneven temperature field distribution during casting, reducing the generation of impurity crystal defects, significantly improving the preparation qualification rate and product quality of DD451 large-size single crystal gas turbine blades, reducing production costs, and adapting to the mass production needs of the aerospace field; at the same time, it clarifies the core reason for "optimizing only the pulling parameters", making the process optimization logic more rigorous and more targeted. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the 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.

[0017] Figure 1 A schematic diagram of the structure of a simulation model of a single-crystal gas turbine blade casting; Figure 2 A simplified schematic diagram of the internal structure of the core; Figure 3 This is a schematic diagram of the mold shell structure; Figure 4 Thermophysical parameters of the ceramic mold shell; Figure 5 Thermophysical parameters of DD451 alloy; Figure 6 These are the thermophysical parameters of the copper cold plate; Figure 7 The heat transfer coefficient between the alloy and the mold shell; Figure 8 The heat transfer coefficient between the alloy and copper cold plate; Figure 9 The heat transfer coefficient between the mold shell and the copper cold plate; Figure 10 The solidification temperature field of a single-crystal gas turbine blade model pulled at a uniform speed of 3 mm / min; Figure 11 To achieve a uniform drawing speed of 3mm / min for the actual casting of DD451 large-size single-crystal gas turbine blades; Figure 12 Solidification temperature field of a single-crystal gas turbine blade model optimized for pulling speed; Figure 13 After optimizing the drawing speed, the actual casting of DD451 large-size single-crystal turbine blades was carried out.

[0018] Figure label: 1. Single crystal gas turbine blade; 2. Simplified core; 3. Sprue; 4. Crystal guide bar; 5. Sprue cup; 6. Spiral crystal selector; 7. Copper cold plate; 8. Mold shell; 9. Furnace body. Detailed Implementation

[0019] 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.

[0020] The purpose of this invention is to provide a method for preparing large-size single-crystal turbine blades to solve the problems existing in the prior art. By using simulation technology and combining the simulation temperature field results, the causes of impurity crystal defects are clarified, providing accurate data support for the optimization of the pulling speed and significantly shortening the research and development cycle.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] This embodiment provides a method for fabricating large-size single-crystal turbine blades, including the following steps: Step 1: Create all or part of the individual casting simulation models of the single-crystal gas turbine blade 1 in the modeling software, such as... Figure 1 As shown, the casting simulation model includes a furnace body 9, a casting module, and a mold shell 8. The casting module was drawn at a 1:1 scale using UG software. The casting module includes two single-crystal gas turbine blades 1, a simplified core 2, a gating system 3, a crystal guide bar 4, a pouring cup 5, a spiral crystal selector 6, and a copper cold plate 7. The structural forms and connection relationships of the simplified core 2, gating system 3, crystal guide bar 4, pouring cup 5, spiral crystal selector 6, and copper cold plate 7 are well known to those skilled in the art, and the detailed structure and connection methods of each component are not described in detail in this embodiment.

[0023] Two single-crystal gas turbine blades 1 are symmetrically arranged and assembled with other components. During casting, molten alloy is poured in from the central pouring cup 5 and the sprue 3, and then poured into the mold shell 8 from the bottom sprue 3 supporting the bottom in a bottom-pouring manner.

[0024] Furthermore, furnace body 9 can also be modeled in UG. To reduce computational load, after the CAD model is built, half of the CAD model is exported in X_T mode. Using half of the CAD model in the simulation software is mainly to simplify calculations by leveraging symmetry, significantly reducing the computational resources and time required for simulation, while maintaining the accuracy of the results. When the casting geometry has symmetrical features, simulating only half of the model is sufficient to equivalently reproduce the overall physical process.

[0025] Step 2: After importing the casting simulation model created in Step 1 into the visual mesh module of the ProCAST simulation software, it is necessary to check whether the model has intersections, whether it is assembled, etc., to meet the requirements of the next step of mesh generation.

[0026] After the casting simulation model passes inspection, non-uniform mesh generation is performed. In critical areas with high heat flux density, high temperature gradient, abrupt geometric changes, and high defect risk (such as interfaces, sharp corners, thin walls, and solidification fronts), fine meshes (e.g., 0.5mm~1.5mm) are used; in other areas far from the core (such as the large gating system 3 and the furnace body 9 far from the single-crystal gas turbine blades 1), coarse meshes (e.g., 3mm~10mm) are used; a gradient transition is used between coarse and fine meshes. After mesh generation, the surface mesh is checked. If there are no problems, the next step is performed; if there are mesh problems, automatic repair is performed in the simulation software. If automatic repair fails, manual repair or modification of the CAD model in UG is required.

[0027] After the simulation model mesh is successfully generated, use the shelling command to create shell 8, as follows: Figure 3 As shown, a mesh is created for mold shell 8, and the mesh is checked and repaired until it passes inspection. Ceramic material is selected for mold shell 8.

[0028] Of course, the shell 8 can also be modeled in UG and then imported into simulation software to generate a mesh.

[0029] To generate a volume mesh for the finite element model, the ProCAST interface will contain 89 individual elements: single crystal gas turbine blade 1, simplified core 2, gating 3, crystal guide 4, pouring cup 5, spiral crystal selector 6, copper cold plate 7, furnace body 9, and mold shell 8.

[0030] Step 3: Set the directional solidification process parameters for the single-crystal gas turbine blade 1 in the simulation software. Setting the directional solidification process parameters includes: setting gravity for the casting simulation model, assigning material values ​​to each individual component, setting heat transfer interfaces, and calculating boundary conditions; the solidus and liquidus temperatures of the alloy are calculated using JMatPro (Journal of Materials Processing Technology, a professional software for calculating phase diagrams and simulating the properties of metallic materials), and other physical properties such as thermal conductivity, latent heat, density, and heat capacity are functions of temperature, as shown in Tables 1-1 and 1-2 below; the pulling action during the directional solidification process is achieved by moving the furnace body 9 upwards. Corresponding heat transfer coefficients are set for the heat transfer interfaces between different components to ensure simulation accuracy.

[0031] Table 1-1 Thermophysical parameters of materials used in simulation calculations

[0032] Table 1-2 Interfacial heat transfer coefficients of different materials

[0033] It is important to note that the casting temperature is set to 1520±10℃ based on the characteristics of DD451 alloy, and the preheating temperature of mold shell 8 is 1520℃, both of which are fixed values ​​(which can be fixed according to actual production). Because the size of the single crystal gas turbine blade 1 is too large, too high a casting temperature will cause the mold shell 8 to crack and the single crystal gas turbine blade 1 to develop cracks, while too low a temperature will cause insufficient alloy fluidity and shrinkage defects, leaving no room for optimization. The initial drawing speed is set to a uniform speed of 3mm / min, which will be used as a variable for subsequent optimization.

[0034] Step 4: Perform temperature field simulation in the simulation software according to the directional solidification process parameters in Step 3; the temperature field simulation focuses on simulating the temperature gradient and solidification rate distribution of each region of the blade body of the single crystal gas turbine blade 1 under a uniform pulling speed of 3 mm / min, and clarify the core mechanism of impurity crystal formation by combining the simulated temperature field data.

[0035] Step 5: Analyze the simulation results from Step 4 and optimize the pulling speed in the directional solidification process parameters. Repeat Step 4 to complete the process verification. This step only optimizes the pulling speed. Specifically, based on the analysis results of impurity crystal induction in Step 4, adjust the pulling speed at different positions of the single-crystal gas turbine blade 1: maintain 3 mm / min in the spiral crystal selection section, adjust to 2 mm / min in the process amplification section, maintain 3 mm / min in the blade body, and adjust to 2 mm / min in the blade crown and above. Re-perform temperature field simulation to verify the optimization results, and then complete the verification through actual casting tests to finally obtain a qualified single-crystal gas turbine blade 1.

[0036] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0037] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for fabricating large-size single-crystal turbine blades, characterized in that, Includes the following steps: Step 1: Create all or part of the casting simulation model of the single-crystal gas turbine blade in the modeling software; Step 2: Import the casting simulation model created in Step 1 into the simulation software, and mesh the casting simulation model; Step 3: Set the directional solidification process parameters for single-crystal gas turbine blades in the simulation software; Step 4: Perform temperature field simulation in simulation software based on the directional solidification process parameters in Step 3; Step 5: Analyze the simulation results from Step 4 and optimize the pulling speed in the directional solidification process parameters. Repeat Step 4 to complete the process verification.

2. The simulation and optimization method for the fabrication of single-crystal gas turbine blades according to claim 1, characterized in that, The casting simulation model in step 1 includes at least nine components: single-crystal gas turbine blades, simplified core, gating system, crystal guide bar, pouring cup, spiral crystal selector, copper cold plate, furnace body, and mold shell.

3. The simulation and optimization method for the fabrication of single-crystal gas turbine blades according to claim 1, characterized in that, In step 2, after the casting simulation model is imported into the simulation software, it is checked whether there are any intersections or whether the casting simulation model is assembled, so as to meet the requirements of mesh generation.

4. The simulation optimization method for the fabrication of single-crystal gas turbine blades according to claim 3, characterized in that, In step 2, when dividing the mesh, different sizes of meshes are used to divide different areas of the casting simulation model.

5. The simulation optimization method for the fabrication of single-crystal gas turbine blades according to claim 3, characterized in that, In step 2, after the single-crystal gas turbine blade is successfully meshed, the mold shell in the casting simulation model is created, and the mold shell is meshed.

6. The simulation optimization method for the fabrication of single-crystal gas turbine blades according to claim 1, characterized in that, In step 3, the directional solidification process parameters for the single-crystal gas turbine blades include: Gravity settings are applied to the casting simulation model; Assign material properties to each individual element in the casting simulation model; Set the heat exchange interface between adjacent individuals and the heat transfer coefficient corresponding to each interface; The pulling action during directional solidification is achieved by moving the furnace body upward.

7. The simulation optimization method for the fabrication of single-crystal gas turbine blades according to claim 1, characterized in that, The modeling software used is UG.

8. The simulation optimization method for the fabrication of single-crystal gas turbine blades according to claim 1, characterized in that, The simulation software used is ProCAST.

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