Large-module casting simulation method for polycrystalline high-temperature alloy blade

Abstract

The invention relates to the field of polycrystalline high-temperature alloy blade investment casting simulation, in particular to a polycrystalline high-temperature alloy blade large-module casting simulation method. The method comprises the following steps: constructing a blade model, a pouring cup model, an upper cross gate model, a lower cross gate model and a middle connecting part model, assembling the models into a large-module casting, importing the large-module casting into analogue simulation software, and performing grid division; setting physical property parameters and heat transfer coefficients of the large-module casting and nucleation parameters of the blade at the research part; a temperature field distribution diagram, a temperature gradient distribution diagram, a shrinkage porosity and cavity defect diagram and a grain morphology diagram of the blade are obtained through simulation. According to the method, the integral casting process of the large-module process can be effectively simulated, the experiment time and cost are greatly saved, the large-module process parameters are optimized and designed in advance, and the method has important significance on batch application of the large-module casting technology.

Description

Technical Field

[0001] The invention relates to the field of polycrystalline high-temperature alloy blade investment casting simulation, and in particular to a large-module casting simulation method for polycrystalline high-temperature alloy blades. Background Art

[0002] Nickel-based polycrystalline high-temperature alloys, due to their simple smelting process and low preparation cost, do not even require heat treatment and can be used in some hot-end components that do not have stringent performance requirements. Compared with single-crystal high-temperature alloys with complex preparation processes, low yields and high raw material costs, they have great commercial competitiveness.

[0003] Aero-engine technology is a complex and advanced field, integrating multiple disciplines such as electronics, information, materials, structures, thermal energy, machinery, manufacturing and industrial control applications. The development level of this technology can reflect a country's scientific and technological strength and comprehensive national strength. At present, China's aero-engine manufacturing has developed from the initial imitation stage to having independent technology, forming a series of relatively mature aero-engine technology systems. However, the manufacture of high-temperature alloy turbine blades is an important factor restricting the development of China's aero-engine technology and is also one of the key technologies. The use of investment casting technology is one of the key technical methods for manufacturing high-temperature alloy blades with complex shapes.

[0004] Investment casting is an important industrial technology. Due to its advantages of high precision, high shape complexity, and good adaptability to various alloys, it has been widely used in various manufacturing fields. Investment casting technology first prepares a wax mold with a smooth surface and high dimensional accuracy according to the shape of the casting product, and then injects the liquid wax material into the mold to obtain the required wax mold. Then, the wax molds of individual parts are assembled into a module according to the design plan. Usually, the module needs to include a pouring cup, a runner, a support, an exhaust duct, etc. Subsequently, the surface of the module is coated with a special high-temperature resistant material for multiple times. This process forms a casting shell after drying. The casting shell is then subjected to high-temperature baking and dewaxing treatment to obtain the desired casting shell. The process parameters such as the casting shell preheating temperature and the alloy melt casting temperature are set according to the actual situation. After the alloy liquid is completely solidified in the shell, the casting is removed from the casting shell by vibration shelling. The casting is then further processed by sand blowing and polishing to obtain an ideal casting blank sample.

[0005] The large-module casting technology for polycrystalline blades is an iteration based on the investment casting technology for turbine blades. The large-module casting technology can produce 20 to 40 turbine blades in a single casting, greatly improving production efficiency while ensuring production quality.

[0006] Due to the improvement of production capacity and efficiency of large-module technology, the time and cost of single experiment and single production are relatively high. Therefore, it is very important to use simulation technology to optimize and design process parameters in advance. An appropriate large-module casting simulation method is of great significance for the mass application of large-module casting technology. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a large-module casting simulation method for polycrystalline high-temperature alloy blades, which uses simulation methods to determine appropriate process parameters in advance and effectively predict the temperature field, grain morphology, stress, etc. during the production process.

[0008] In order to achieve the above object, the technical solution of the present invention is:

[0009] A large-module casting simulation method for polycrystalline high-temperature alloy blades, including large-module model construction of polycrystalline high-temperature alloy blades, large-module casting mesh division, and large-module casting simulation physical property parameters, heat transfer coefficient, and nucleation parameter setting. The temperature field distribution map, temperature gradient distribution map, shrinkage and shrinkage defect map, and grain morphology map analysis of the large-module blades are obtained through simulation.

[0010] When constructing a large module model of a polycrystalline high-temperature alloy blade, the module includes a pouring cup, a cross runner, an intermediate support, and a blade model. All of the above components are established in the modeling software and are connected in an assembly manner. The overall module adopts a double-layer structure, and the two adjacent cross runners are arranged relatively parallel to each other and connected by an intermediate support. A pouring cup is provided in the middle of the top of the topmost cross runner. Each cross runner part is composed of six branches, and each cross runner branch is a gradient structure. The height is higher on the side close to the pouring cup and lower on the side away from the pouring cup. Each cross runner branch is placed with two parallel blades.

[0011] The large-module casting simulation method for polycrystalline high-temperature alloy blades, when constructing a large-module model of a polycrystalline high-temperature alloy blade, has the following dimensions: the large-module model height is 300-400 mm, the maximum diameter is 200-300 mm, and the number of turbine blades produced in a single group is 20-40 pieces; the pouring cup: the upper end diameter is 100 mm, the lower end diameter is 50 mm, and the height is 100 mm; the intermediate support: the intermediate support is a cylindrical connection, the cylinder height is 100 mm, and the cylinder diameter is 40 mm.

[0012] The large-module casting simulation method for polycrystalline high-temperature alloy blades, when performing mesh division of large-module castings, uses the mesh module in the simulation software to establish two-dimensional meshes for the large-module castings and mold shells, and after checking that they are correct, establishes three-dimensional meshes for the above two.

[0013] The large-module casting simulation method for polycrystalline high-temperature alloy blades, in the process of establishing and checking two-dimensional grids for large-module castings and mold shells, firstly unifies the large-module castings into the same group of materials, and performs corresponding grid division according to the complexity of different models, wherein: the blade part focuses on refinement, and the grid size is selected as 1-2 mm; the runner, gate cup, and connection are relatively refined, and the grid size is selected as 2 mm; the grid size of the furnace model is set to be larger, and the grid size is selected as 20-40 mm; after the two-dimensional grid is established, the grid needs to be checked, and the overlap value and the minimum side length during the inspection need to be adjusted according to the accuracy of the simulation experiment, and the default value is used when there are no special requirements; after the grid inspection, if there is an error in the grid of the casting part, it is necessary to use a manual repair tool to repair it or readjust the grid size for re-inspection. If there is an error in the grid of the mold shell part and there are less than 10 problems, use the automatic correction tool to modify it. In the actual production process, the mold shell thickness cannot be guaranteed to be completely uniform, and the use of the automatic correction tool to modify it will not cause the conditions in the simulation experiment to be different from those in the actual production process on site.

[0014] The large-module casting simulation method for polycrystalline high-temperature alloy blades uses a casting module in the simulation software to set parameters for the large-module casting and the mold shell when setting the physical property parameters, heat transfer coefficient, and nucleation parameters of the large-module casting simulation.

[0015] In the large-module casting simulation method for polycrystalline high-temperature alloy blades, during the simulation of physical property parameters, the alloy of the casting is K418B, the material performance simulation software data or actual measurement data is brought into the simulation software and into the large-module casting model, and the mold shell material uses the corresponding material in the software material library.

[0016] The large-module casting simulation method for polycrystalline high-temperature alloy blades, in the process of simulating nucleation parameters, when setting the body nucleation parameters, the average undercooling is selected as 10-20k, and when setting the surface nucleation parameters, the Gaussian mode is selected, and the average undercooling is set to 5-10k. In the actual production process, a grain refiner is added to the mold shell surface layer to reduce the average undercooling of the surface nucleation and thereby achieve a simulation effect close to the actual production; when selecting the Cafe calculation model, the CAFE2G model in the Post-processing mode is selected, and the blade that needs to be analyzed for grain structure is selected in the Calculation zone part.

[0017] The large-module casting simulation method for polycrystalline high-temperature alloy blades uses an analysis module in the simulation software to analyze the large-module casting blades when analyzing the temperature field distribution diagram, temperature gradient distribution diagram, shrinkage and shrinkage defect diagram and grain morphology diagram of the large-module blades.

[0018] The design idea of ​​the present invention is:

[0019] Build a large module model, import it into casting simulation software for assembly, perform mesh division and check for errors, build a mold shell, generate and check the body mesh, set physical properties, heat transfer parameters, and nucleation parameters and perform simulation, obtain simulation results and compare and analyze them with actual production results.

[0020] First, use modeling software to model the blades, gate cups, upper and lower runners, and middle connecting parts, and use the assembly function to assemble the above parts. After the modeling is completed, export it in igs format.

[0021] Bring the igs format file into the simulation software and enter the mesh module. After the file is brought into the software, it will be displayed as several parts. Select all parts for assembly and eliminate overlapping surfaces.

[0022] Then, all parts are divided into two-dimensional grids, and the corresponding grid division is carried out according to the complexity of different models. After division, the grid is checked to ensure that there are no errors before proceeding to the next simulation step.

[0023] After the 2D mesh division is correct, the 2D shelling step is performed to build the mold shell. The gate cup is selected and no shelling is performed. The remaining parts generate a mold shell with a thickness of 4 to 6 mm. After production is completed, the mesh is also checked. After ensuring that there are no errors, the next simulation step is performed.

[0024] Use the Basic shapes function to build the furnace environment. After building it, divide the mesh. This part of the mesh does not need to be very detailed. After building the mesh, convert it into an Enclosure.

[0025] After completing the above steps, the three-dimensional mesh is constructed, and after the construction, the mesh is checked to enter the casting module after ensuring that there are no errors.

[0026] In the casting module, select the pre-entered material property parameters and select the appropriate heat transfer coefficient. Select the blade to be studied for surface nucleation and body nucleation and select the pre-entered nucleation parameters. When selecting the Cafe calculation model, select the CAFE2G model in the Post-processing mode. In the Calculation zone section, select the blade that needs to be analyzed for grain structure. After the data is checked, you can perform simulation.

[0027] Based on the above technical solution, it can be seen that the large-module casting simulation method of a polycrystalline high-temperature alloy blade provided by the present invention has at least one of the following beneficial effects:

[0028] 1. The large-module casting simulation method of a polycrystalline high-temperature alloy blade of the present invention can perform full-process simulation on different module shapes of large-module casting technology, and obtain the temperature field, solidification time and sequence, defect analysis and grain morphology analysis of the blade part during the casting process, and pre-optimize and design the process parameters in the casting process based on this, so as to avoid a series of problems in the actual production process.

[0029] 2. The present invention can flexibly adjust the geometric model of the large-module casting process. By using the assembly function in the modeling software, the geometric shape of the module can be efficiently adjusted, and a casting simulation experiment can be carried out. The casting conditions under different process parameters can also be tested, saving a lot of experimental time and cost.

[0030] 3. The present invention can check the cooling curves, cooling rates and temperature gradients of blades at different positions under the large module casting process. Compared with the cumbersome multi-point temperature measurement experiment, the present invention has higher efficiency. After completing the simulation, you can set and check it in the analysis module in the simulation software, and then analyze in advance the blade positions that may have defects or abnormalities in the module.

[0031] 4. The present invention adopts the CAFE2G model, which can effectively predict the grain morphology of the blade under the specified process parameters after determining the parameters, and predict the abnormal grains that may be produced in the key parts, so as to adjust the process parameters in advance to avoid the blade microstructure not meeting the standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a simulation model of the large die casting of the present invention;

[0033] Figure 2 It is a simulation model of the large module shell of the present invention;

[0034] Figure 3 It is the grid diagram of the large mold casting and mold shell of the present invention;

[0035] Figure 4 It is the temperature field distribution diagram of the large die casting of the present invention;

[0036] Figure 5 It is the temperature gradient distribution diagram of the large die casting of the present invention;

[0037] Figure 6 This is a shrinkage and porosity defect diagram of a large die casting of the present invention;

[0038] Figure 7 This is a grain morphology diagram of blades with different thicknesses according to the present invention;

[0039] Figure 8 This is a large module shell diagram for field experiments of the present invention;

[0040] Fig. 9 This is a comparison diagram of the experimental morphology (left) and simulated grain morphology (right) of the present invention.

[0041] Figure 1 Middle: 1. pouring cup; 2. upper horizontal runner; 3. lower horizontal runner; 4. middle support. DETAILED DESCRIPTION

[0042] In the specific implementation process, the present invention adopts a polycrystalline nickel-based high-temperature alloy, the alloy grade is K418B, and the chemical composition of the polycrystalline nickel-based high-temperature alloy is as follows by weight percentage:

[0043] C: 0.04~0.07wt%

[0044] Mg: 0~0.005wt%

[0045] Mn: 0~0.25wt%

[0046] Si: 0~0.5wt%

[0047] P: 0~0.015wt%

[0048] Cr: 11~13wt%

[0049] Mo: 3.8~5.2wt%

[0050] Nb: 1.5~2.5wt%

[0051] Ti: 0.4~1wt%

[0052] B: 0.005~0.015wt%

[0053] Al: 5.5~6.5wt%

[0054] Zr: 0.05~0.15wt%

[0055] Fe: 0~0.5wt%

[0056] Cu: 0~0.5wt%

[0057] Co: 0~1wt%

[0058] S: 0~0.015wt%

[0059] The remainder is Ni.

[0060] like Figure 1-Figure 8 As shown, a large-module casting simulation method for a polycrystalline high-temperature alloy blade comprises the following steps:

[0061] like Figure 1As shown, the modeling software is used to model according to the actual production size. The large module casting simulation model consists of a pouring cup 1, a runner (upper runner 2, lower runner 3), an intermediate support 4, and a blade connection. The upper runner 2 and the lower runner 3 are arranged relatively parallel to each other up and down, and are connected by the intermediate support 4. A pouring cup 1 is provided in the middle of the top of the upper runner 2, and a blade is provided at the bottom of each runner (upper runner 2, lower runner 3).

[0062] Large module model size: The large module model height is 300-400mm, the maximum diameter is 200-300mm, and the number of turbine blades produced in a single group is 20-40;

[0063] Pouring cup 1: The upper diameter is 100mm, the lower diameter is 50mm, and the height is 100mm;

[0064] Runner: The upper runner 2 and the lower runner 3 are each composed of six branches, each of which is a gradient structure, with a higher height near the pouring cup and a lower height away from the pouring cup. Each runner branch is equipped with two parallel blades, with a moderate distance between them, and the blades are placed tilted, with the tenon part of the blade facing upward and the crown part of the blade facing downward.

[0065] Intermediate support 4: The intermediate support is a cylindrical connection with a cylinder height of 100 mm and a cylinder diameter of 40 mm.

[0066] After establishing each part, use the assembly function of the modeling software to assemble the parts. After assembly, save the file in igs format and open it in the simulation software.

[0067] After entering the mesh module in the simulation software, a geometric check is performed to ensure that the model has no missing faces or CAD drawings. Because large mold castings are composed of multiple blades and runners, there will be many overlapping faces. Therefore, after the geometric check, all parts need to be assembled to eliminate overlapping faces, thereby avoiding errors in the subsequent 2D mesh creation process.

[0068] After the assembly is completed, the surface mesh of the large module casting is established. After selecting the form of displaying boundary points in the visual perspective, the surface mesh of the casting is established. The mesh size is selected to be 1-2mm. The blade part can be refined, the runner, gate cup, and connection can be relatively refined, and the mesh size is selected to be 2mm. The mesh size of the furnace model can also be larger, and the mesh size is selected to be 20-40mm. After the two-dimensional mesh is established, the mesh needs to be checked. According to the accuracy of the simulation experiment, the overlap value and the minimum side length during the inspection need to be adjusted. The default value can be used if there are no special requirements. After the mesh inspection, if there is an error in the mesh of the casting part, it needs to be repaired with a manual repair tool or the mesh size needs to be readjusted and re-checked. The automatic correction tool cannot be used for modification, because this may change the geometric dimensions of the casting and affect the accuracy of the simulation experiment.

[0069] After successfully establishing the two-dimensional grid, use the shelling function in the 2D grid function to prepare the shell for the large mold casting. Select the top surface of the pouring cup as the symmetry surface in the shelling function, and use the rest of the shell to produce the shell. The shell thickness is set based on the actual production situation. If there are no special requirements, it can be set to 4-6mm. After successful establishment, the two-dimensional grid of the shell also needs to be checked. According to the accuracy of the simulation experiment, the overlap value and the minimum side length during the inspection need to be adjusted. If there are no special requirements, the default value can be used. After the grid inspection, if there are less than 10 problems in the shell part, the automatic correction tool can be used to modify it. Because the shell thickness cannot be guaranteed to be completely uniform during the actual production process, the use of the automatic correction tool to modify it will not cause the conditions of the simulation experiment to be different from those of the actual production process on site. The shell after establishment is seen Figure 2 .

[0070] After completing the 2D mesh creation, you need to select all the bodies to proceed to the next step of 3D mesh creation. Depending on the number of 2D meshes, the time to create the 3D mesh is also different. After the 3D mesh is created, you need to use the 3D mesh check tool to check it. If there are many errors, you need to readjust the 2D mesh size and then generate and check the 3D mesh. After the 3D mesh is created, see Figure 3 .

[0071] After completing the above steps, you can enter the casting module to set the physical parameters, heat transfer coefficient, and nucleation parameters. The alloy of the casting is K418B. The material performance simulation software data or actual measurement data can be brought into the simulation software and into the large module casting model. The shell material can use the material provided in the software material library. After the physical parameters are set, the heat transfer coefficient needs to be set. Since the large module contains a large number of blades, the blades and runner system are grouped together to consider the heat transfer situation. After setting the heat transfer coefficient, it is also necessary to set the surface nucleation and body nucleation of the furnace body radiation heat transfer and the blade part.

[0072] When setting the body core parameters, the average undercooling is selected as 10-20k. When setting the surface core parameters, select the Gaussian mode and set the average undercooling to 5-10k. Because grain refiners are added to the shell surface during the actual production process, the average undercooling of the surface core is reduced to achieve a simulation effect close to the actual production. When selecting the Cafe calculation model, select the CAFE2G model in the Post-processing mode. In the Calculation zone section, select the blade that needs to be analyzed for grain structure.

[0073] Finally, set a series of operating parameters. First, select precision investment casting, and then adjust the operating time, end temperature, time step, etc. It is worth noting that the CAFE2G function needs to be turned on in advance, otherwise the system will use the CAFE model by default. After the settings are completed, the data detection link is carried out. After the detection is correct, the casting simulation and subsequent data analysis can be carried out. Through simulation, the temperature field, solidification process, cooling rate, loose shrinkage distribution map, grain morphology, etc. of the blade can be obtained.

[0074] After the simulation is completed, enter the analysis module to analyze the results. Figure 4 As shown in the figure, the schematic diagram of the temperature field of the large module blade obtained by simulation, in which the liquidus temperature and solidus temperature of the K418B alloy used in the present invention can be seen, and the specific solidification time and solidification sequence of the blades at different positions of the large module can be obtained. The data obtained from the temperature field can be used to further calculate the temperature gradient of the blades at different positions of the large module using the metallurgical tool function in Results. Figure 5 As shown in the temperature gradient distribution diagram, the temperature gradient of some blades can reach 100k / cm, and the temperature gradient of the rest is in the range of 10 to 50k / cm.

[0075] like Figure 6 As shown in Figure 1, the porosity criterion Niyama criterion for large module blades is derived from the ratio of the temperature gradient to the square root of the cooling rate. In the region where the criterion value Ny is below a certain threshold, shrinkage pores are expected to form.

[0076] like Figure 7 As shown in the figure, the grain morphology of the blade part of the large module casting is calculated using the CAFE2G function. Since the cooling rates at different positions in the large module casting are not only the same, the grain size and dendrite spacing of the blades at different positions are also different. The use of simulation methods can predict the grain morphology of the casting at a specific position under the characteristic process parameters in advance, and select suitable microstructures for the actual process in advance.

[0077] Below, the present invention is further described in detail by examples.

[0078] Example 1

[0079] This embodiment adopts a combination of simulation and experiment to verify the feasibility of a large-module casting simulation method of a polycrystalline high-temperature alloy blade of the present invention, and successfully predicts the grain morphology of the large-module blade. The specific implementation method is as follows:

[0080] Simulation method:

[0081] Modeling software (such as SolidWorks software, etc.) is used to build models of blades, pouring cups, upper and lower runners, and middle connecting parts, and the assembly function is used to form a large module casting, which is exported in igs format to simulation software (such as Procast software, etc.), and assembled to eliminate overlapping surfaces.

[0082] Enter the mesh module to mesh the large module casting as a whole, with a mesh size of 1mm. Mesh the furnace body with a mesh size of 30mm. After completion, convert the furnace body mesh to Enclosure. Check the mesh and the result shows no errors. Use the shelling function in the 2D mesh function to prepare the mold shell for the large module casting. Select the top of the pouring cup without forming a mold shell, and the rest of the shell forms a mold shell with a thickness of 4. Check the mesh of the mold shell part, and the result shows that there are 3 errors. The cause of the error is that the acute angle of the mesh triangle is too small. After using the automatic correction function, the result shows no errors. After completing the above steps, establish a three-dimensional mesh and check the mesh. The result shows no errors.

[0083] Enter the casting module to define the gravity direction of the large module casting, and select the -Z direction. Use the Virtual Mold function to create a sand box. The upper edge of the sand box is flush with the upper edge of the mold shell, and the depth of the sand box is greater than the mold shell by 40mm. Define the material properties, the alloy is selected as K418B, and the alloy properties are from the material performance simulation software (such as: Jmat-pro software, etc.). The mold shell and sand box materials are selected as the corresponding materials in the Mold material library. Set the heat transfer coefficient between the large module casting, sand box, and furnace body, and set the corresponding parameters in the process condition management section. Select the upper part of the blade of the large module as the Calculation zone, set the average supercooling of the body nucleus to 10k, select each surface of the blade in the Calculation zone for surface nucleation, set the average supercooling to 5k, and select the CAFE2G model in the Post-processing mode for calculation. After completion, check the data, the result shows no error, and select the maximum value of the processor for simulation.

[0084] Experimental methods:

[0085] This embodiment uses a large-module casting method for polycrystalline high-temperature alloy blades to prepare a batch of polycrystalline high-temperature alloy blades, which are delivered in a cast state and have an alloy grade of K418B. The composition of the polycrystalline high-temperature alloy blades is shown in Table 1, and mainly includes the following steps:

[0086] Table 1 Composition of polycrystalline high temperature alloy blades (wt%)

[0087] B C Al Si S Ti Cr Fe Co Cu Zr Nb Mo Ni Example 1 0.009 0.065 5.79 0.05 0.001 0.66 11.51 0.02 0.32 0.02 0.10 2.10 3.98 margin

[0088] Step 1: Figure 8 As shown, put the cleaned large module shell into the sand box and fill it with corundum sand of moderate particle size. During the filling process, the shell pouring cup part should be covered with a dust cover. When the sand box is half filled with corundum sand, it should be slightly shaken to ensure that the corundum sand is in full contact with the shell without a large gap in the middle. After filling, cover the pouring cup with 20mm thick insulation cotton. After completing the above steps, put the sand box with the shell and corundum sand into a box furnace and keep it warm at 1080℃ for 4 hours.

[0089] Step 2: Place the master alloy into the melting crucible of the vacuum induction melting furnace, where the master alloy mass is 9.6kg, place the pre-burned sand box and shell into the vacuum induction melting furnace, melt the master alloy after the vacuum pressure is ≤0.1Pa, adjust the heating power, insert the temperature measuring thermocouple into the molten alloy to measure the temperature, refine at the refining temperature for a certain time, lower the temperature slightly after refining, remove the temperature measuring thermocouple, and then cast, quickly complete the casting, and the casting position is the center of the pouring cup. After the casting is completed, let it stand and then move the sand box out of the vacuum induction melting furnace, cool it at room temperature for one day, and then shell the casting.

[0090] Step 3: Cut, sandblast, and mechanically polish the shelled casting to obtain a blade blank sample.

[0091] Step 4: Take the upper blades of the experimental large module casting and process them into plate samples for the next experiment. Use 20g CuSO4+100ml H2O+50ml HCl mixed solution to corrode the plate samples and observe their grain morphology. Use software to mark the grain boundaries, select the simulated grain morphology map at the corresponding position and splice it with the experimental grain morphology map, see Fig. 9 .

[0092] The implementation results show that the present invention can effectively simulate the overall casting process of the large module process, greatly save experimental time and cost, and optimize and design the large module process parameters in advance. The simulation method of the present invention can predict the grain morphology of the casting at a specific position under the characteristic process parameters in advance. The grain morphology of the simulation results corresponds to the grain morphology of the experimental results to a high degree, and suitable microstructures can be screened for the actual process in advance, which is of great significance for the batch application of large module casting technology.

Claims

1. A large-module casting simulation method for polycrystalline high-temperature alloy blades, characterized in that: It includes the construction of large module model of polycrystalline high-temperature alloy blades, mesh division of large module castings, and simulation of physical parameters, heat transfer coefficient, and nucleation parameter settings of large module castings. Through simulation, the temperature field distribution map, temperature gradient distribution map, shrinkage and shrinkage defect map of large module blades and grain morphology map analysis of blades are obtained; When constructing a large module model of a polycrystalline high-temperature alloy blade, the module includes a pouring cup, a cross runner, an intermediate support, and a blade model. All of the above components are established in the modeling software and are connected in an assembly manner. The overall module adopts a double-layer structure, and the two adjacent cross runners are arranged relatively parallel to each other and connected by an intermediate support. A pouring cup is provided in the middle of the top of the topmost cross runner. Each cross runner part is composed of six branches, and each cross runner branch is a gradient structure. The height is higher on the side close to the pouring cup and lower on the side away from the pouring cup. Each cross runner branch is placed with two parallel blades.

2. The large-module casting simulation method for polycrystalline high-temperature alloy blades according to claim 1 is characterized in that: When constructing the large module model of polycrystalline high-temperature alloy blades, the dimensions of the large module model are: the height of the large module model is 300-400mm, the maximum diameter is 200-300mm, and the number of turbine blades produced in a single group is 20-40 pieces; the pouring cup: the upper diameter is 100mm, the lower diameter is 50mm, and the height is 100mm; the intermediate support: the intermediate support is a cylindrical connection, the cylinder height is 100mm, and the cylinder diameter is 40mm.

3. The large-module casting simulation method for polycrystalline high-temperature alloy blades according to claim 1 is characterized in that: When meshing large mold castings, use the mesh module in the simulation software to create two-dimensional meshes for the large mold castings and mold shells, and after checking that they are correct, create three-dimensional meshes for the above two.

4. The large-module casting simulation method for polycrystalline high-temperature alloy blades according to claim 3 is characterized in that: In the process of establishing and checking the two-dimensional grids of large-module castings and mold shells, the large-module castings are first unified into the same group of materials, and the corresponding grid division is performed according to the complexity of different models, among which: the blade part is focused on refinement, and the grid size is selected as 1-2mm; the runner, gate cup, and connection are relatively refined, and the grid size is selected as 2mm; the grid size of the furnace model is set to be larger, and the grid size is selected as 20-40mm; after the two-dimensional grid is established, the grid needs to be checked, and the overlap value and the minimum side length during the inspection need to be adjusted according to the accuracy of the simulation experiment. The default value is used when there are no special requirements; after the grid inspection, if there are errors in the grid of the casting part, it is necessary to use manual repair tools to repair it or readjust the grid size to re-check it. If there are errors in the grid of the mold shell part and there are less than 10 problems, use the automatic correction tool to modify it. In the actual production process, the mold shell thickness cannot be guaranteed to be completely uniform. The use of automatic correction tools to modify will not cause the conditions in the simulation experiment to be different from those in the actual production process on site.

5. The large-module casting simulation method for polycrystalline high-temperature alloy blades according to claim 1 is characterized in that: When simulating the physical properties, heat transfer coefficient, and nucleation parameters of large-module castings, the casting module in the simulation software is used to set the parameters of large-module castings and mold shells.

6. The large-module casting simulation method for polycrystalline high-temperature alloy blades according to claim 5 is characterized in that: In the process of simulating physical property parameters, the alloy of the casting is K418B. The material performance simulation software data or actual measurement data is brought into the simulation software and into the large-module casting model. The mold shell material uses the corresponding material in the software material library.

7. The large-module casting simulation method for polycrystalline high-temperature alloy blades according to claim 5 is characterized in that: During the simulation of nucleation parameters, when setting the body nucleation parameters, the average undercooling is selected as 10-20k, and when setting the surface nucleation parameters, the Gaussian mode is selected, and the average undercooling is set to 5-10k. In the actual production process, grain refiners will be added to the shell surface layer to reduce the average undercooling of the surface nucleation and achieve a simulation effect close to the actual production. When selecting the Cafe calculation model, select the CAFE2G model in the Post-processing mode, and select the blade that needs to be analyzed for grain structure in the Calculation zone.

8. The large-module casting simulation method for polycrystalline high-temperature alloy blades according to claim 1 is characterized in that: When analyzing the temperature field distribution diagram, temperature gradient distribution diagram, shrinkage defect diagram and grain morphology diagram of large module blades, the analysis module in the simulation software is used to analyze the large module casting blades.

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