Method for adjusting directional solidification parameters of large module nickel-based single crystal blade

Abstract

The application discloses a kind of big module nickel-based single crystal blade directional solidification parameter adjustment methods, comprising the following steps: preparation big module nickel-based single crystal blade wax mould module, and bury ceramic tube on the nickel-based single crystal blade wax mould of specific position;Preparation big module nickel-based single crystal blade ceramic shell, hot thermocouple is inserted in ceramic tube;Big module nickel-based single crystal blade ceramic shell and parent alloy ingot are placed in the heater and crucible of vacuum induction melting furnace respectively, and directional solidification test is carried out to determine the temperature field distribution of edge plate adapter site along chord length direction;Design adjusted heater temperature and big module nickel-based single crystal blade ceramic shell pulling rate;Reproduce big module nickel-based single crystal blade ceramic shell, no longer bury ceramic tube, and directional solidification is carried out using adjusted process parameters.The application can reduce the defects such as heterocrystal and low-angle grain boundary of edge plate adapter site, improve the uniformity and consistency of big module single crystal blade.

Description

Technical Field

[0001] This invention belongs to the field of directional solidification technology for nickel-based single-crystal blades, specifically relating to a method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades. Background Technology

[0002] As is well known, nickel-based single-crystal superalloys are the preferred material for aero-engine turbine blades. The casting yield and microstructural stability of single-crystal blades are key factors affecting the development cost of aero-engines. Traditional single-crystal blade fabrication uses a small-module method, with a limited number of blades that can be produced per module. This leads to a significant waste of master alloys and auxiliary materials, limiting the efficiency of the single-crystal blade fabrication process and increasing the development cost and cycle time. In recent years, the use of large-module fabrication for single-crystal blades has attracted increasing attention in the field of nickel-based superalloys. The large-module method can significantly improve the fabrication efficiency of single-crystal blades, save raw materials and auxiliary materials, and effectively reduce the manufacturing cost of single-crystal blades after improving the yield rate.

[0003] However, the large-module method for preparing single-crystal blades has problems such as uneven temperature field caused by the module structure and excessively high isotherm slopes in key areas such as the rim plate transition area. Using constant process parameters such as heater temperature and pulling rate will easily lead to defects such as impurities and small-angle grain boundaries in single-crystal blades at the transition area and other locations, thereby reducing the single-crystal integrity of the single-crystal blades and limiting the improvement of the yield of large-module single-crystal blades. Therefore, it is urgent to develop a method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades. By measuring the temperature field distribution at locations such as the rim plate transition area through experimental temperature measurement, the directional solidification parameters of single-crystal blades can be controlled to achieve the goal of consistent microstructure and single-crystal integrity of nickel-based single-crystal superalloys.

[0004] The invention patent with publication number CN103752808A discloses a method for achieving variable pulling rate of the mold in directional solidification casting. This method first uses an infrared thermometer to measure the time-temperature curve of the high-temperature alloy casting in directional solidification casting, thereby obtaining the instantaneous growth rate of the high-temperature alloy casting in the directional crystal growth direction. Then, based on the relationship between the pulling rate and the instantaneous growth rate, the required pulling rate of the high-temperature alloy casting at a certain coordinate in the directional crystal growth direction is obtained. Finally, based on the obtained pulling rate of the high-temperature alloy casting at a certain coordinate in the directional crystal growth direction, the pulling rate of the mold is adjusted in real time. This technical solution uses infrared thermometry for temperature measurement, which has significant limitations. Furthermore, due to the complex structure and module layout of large-module single-crystal blades, it is difficult to use infrared thermometry to measure the alloy temperature at specific key locations, and therefore it cannot be used to adjust the pulling rate of large-module single-crystal blades and the heater temperature. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades. The adjustment method includes the following steps in sequence:

[0006] Step 1: Press several nickel-based single-crystal blade wax molds according to the design requirements, and assemble the pouring cup, runner, nickel-based single-crystal blade wax mold, seed crystal and base plate from top to bottom to form a nickel-based single-crystal blade wax mold module. This wax mold module consists of several layers of longitudinally arranged nickel-based single-crystal blade wax molds and several layers of radially arranged nickel-based single-crystal blade wax molds, which is the large module nickel-based single-crystal blade wax mold module. In the large module nickel-based single-crystal blade wax mold module, ceramic tubes are embedded in the bottommost layer of nickel-based single-crystal blade wax molds located on the same radius.

[0007] Step 2: Seal the opening of the ceramic tube with a rubber stopper, then coat the outer surface of the large module nickel-based single crystal blade wax mold with several layers of shell and one layer of sealing slurry. After each layer is coated, dry it, then dewax and fire the shell to obtain the ceramic shell of the large module nickel-based single crystal blade.

[0008] Step 3: Remove the rubber stopper from the opening of the ceramic tube, then insert the thermocouple into the opening of the ceramic tube, and seal the opening of the ceramic tube with refractory slurry to fix the thermocouple in the ceramic tube.

[0009] Step 4: Place the large-module nickel-based single-crystal blade ceramic shell and the master alloy ingot into the heater and crucible of the vacuum induction melting furnace, respectively. Evacuate the vacuum induction melting furnace to a certain vacuum level. Heat the heater to the holding temperature of the large-module nickel-based single-crystal blade ceramic shell. Heat the crucible to make the master alloy ingot go through the melting, smelting and refining process in sequence. Then cool the master alloy liquid to the casting temperature. The casting temperature of the master alloy liquid is the holding temperature of the large-module nickel-based single-crystal blade ceramic shell.

[0010] Step 5: Pour the master alloy liquid into the ceramic shell of the large module nickel-based single crystal blade. After standing for a certain period of time, pull the ceramic shell of the large module nickel-based single crystal blade downwards at a certain pulling speed. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to be flush with the lower surface of the baffle below the heater, stop pulling and let it stand for a certain period of time. At this time, record the temperature values ​​measured by each thermocouple. Keep the heater temperature and pulling speed constant, and continue to pull the ceramic shell of the large module nickel-based single crystal blade downwards. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to a certain distance from the lower surface of the baffle below the heater, stop pulling and let it stand for a certain period of time. At this time, record the temperature values ​​measured by each thermocouple.

[0011] Step 6: Adjust the heater temperature and pulling rate according to the temperature values ​​measured by each thermocouple, and calculate the adjusted heater temperature, the temperature parameters of the nickel-based single crystal blade, the adjusted pulling rate of the nickel-based single crystal blade, and the adjusted pulling rate of the ceramic shell of the large module nickel-based single crystal blade.

[0012] Step 7: Re-prepare the ceramic shell of the large module nickel-based single crystal blade according to the operations of Step 1 to Step 3, but no longer embed ceramic tubes on the nickel-based single crystal blade wax model; heat the re-prepare ceramic shell of the large module nickel-based single crystal blade and the master alloy ingot according to the operation of Step 4, at which time the heater temperature is the original heater temperature;

[0013] Step 8: Pour the master alloy liquid into the newly prepared large-module nickel-based single-crystal blade ceramic shell. After standing for a certain period of time, pull the large-module nickel-based single-crystal blade ceramic shell downwards at the original pulling rate. When the upper surface of the edge plate of the bottommost nickel-based single-crystal blade is pulled to be flush with the lower surface of the baffle below the heater, change the original heater temperature to the adjusted heater temperature and the original pulling rate to the adjusted pulling rate. Continue to pull at a uniform speed with the adjusted heater temperature and the adjusted pulling rate. When the upper surface of the edge plate of the bottommost nickel-based single-crystal blade is pulled to a certain distance from the lower surface of the baffle below the heater, change the adjusted heater temperature to the original heater temperature and the adjusted pulling rate to the original pulling rate. The heater temperature adjustment process and pulling rate adjustment process of the other layers of the large-module nickel-based single-crystal blade ceramic shell are the same as those of the bottommost layer until the pulling is completed. Take out the large-module nickel-based single-crystal blade ceramic shell, knock off the shell, and you will get the large-module nickel-based single-crystal blade.

[0014] Preferably, in step one, there are at least two layers of longitudinally arranged nickel-based single-crystal blade wax molds and at least two layers of radially arranged nickel-based single-crystal blade wax molds; three ceramic tubes are embedded on the nickel-based single-crystal blade wax molds, and the three ceramic tubes are equally spaced at the transition part between the blade body and the edge plate of the nickel-based single-crystal blade, with the ceramic tubes forming a 45° angle with the upper surface of the edge plate of the nickel-based single-crystal blade.

[0015] In any of the above schemes, it is preferred that, in step two, the shell is coated with corundum powder slurry and corundum sand alternately, and the sealing layer is coated with corundum powder slurry, with a total of 6.5-8.5 layers.

[0016] In any of the above schemes, it is preferred that, in step four, the vacuum degree in the vacuum induction melting furnace is 4-6 Pa and the heater temperature is 1520-1540℃.

[0017] In any of the above schemes, preferably, in step five, the master alloy liquid is poured into the ceramic shell of the large module nickel-based single crystal blade. After standing for 1-2 minutes, the ceramic shell of the large module nickel-based single crystal blade is pulled downwards at a pulling speed of 2.5-5 mm / s. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to be flush with the lower surface of the baffle below the heater, the pulling is stopped and the shell is left to stand for 10-15 seconds. At this time, the temperature values ​​measured by each thermocouple are recorded. If the nickel-based single crystal blades are numbered 1#, 2#, ..., n# from the inner layer to the outer layer, then the temperature value measured by each thermocouple is T. 1a T 1b T 1c T 2a T 2b T 2c ......T na T nb T nc .

[0018] In any of the above schemes, preferably, in step five, the heater temperature is maintained at 1520-1540℃ and the pulling speed is 2.5-5mm / s, and the large module nickel-based single crystal blade ceramic shell is pulled downwards. When the upper surface of the edge plate of the lowest nickel-based single crystal blade is pulled to 5-8mm from the lower surface of the baffle below the heater, the pulling is stopped and the shell is left to stand for 10-15s. At this time, the temperature values ​​measured by each thermocouple are recorded as T. 1a '、T 1b '、T 1c '、T 2a '、T 2b '、T 2c '.......T na '、T nb '、T nc '.

[0019] In any of the above schemes, it is preferred that, in step six, the adjusted heater temperature is... In the formula: T1 is the original heater temperature, °C; T2 is the adjusted heater temperature, °C;

[0020] The temperature parameters of nickel-based single crystal blades are Where: M i Let be the temperature parameter of the i-th nickel-based single crystal blade, also known as the intermediate parameter, in °C;

[0021] The adjusted pulling rate of the nickel-based single crystal blade is V i2 =V1*(T ia '-T ic ') / M i In the formula: V1 is the original pulling speed, mm / s; V i2M represents the adjusted pulling rate of the i-th nickel-based single crystal blade, in mm / s; i Let be the temperature parameter of the i-th nickel-based single crystal blade, also known as the intermediate parameter, in °C;

[0022] The adjusted pulling rate of the large module nickel-based single crystal blade ceramic shell is: Where: V2 is the adjusted pulling speed, mm / s; V i2 is the adjusted pulling speed of the i-th nickel-based single crystal blade, in mm / s; n is a natural number.

[0023] In any of the above schemes, it is preferred that, in step eight, the master alloy liquid is poured into the newly prepared large module nickel-based single crystal blade ceramic shell and left to stand for 1-2 minutes; when the upper surface of the edge plate of the lowest nickel-based single crystal blade is pulled to 5-8 mm from the lower surface of the baffle below the heater, the adjusted heater temperature is changed back to the original heater temperature, and the adjusted pulling rate is adjusted back to the original pulling rate.

[0024] In this invention, the pressing of the nickel-based single-crystal blade wax mold, the preparation of the nickel-based single-crystal blade ceramic shell (including slurry preparation, drying process, dewaxing process, calcination process, etc.), the smelting and refining of the master alloy ingot, and the directional solidification process can all be carried out using traditional techniques, and no special requirements are placed on the process parameters. The casting temperature, shell temperature, and other parameters of the alloy are selected according to the solidus and liquidus temperatures of the nickel-based single-crystal alloy used.

[0025] The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades of the present invention is applicable to the directional solidification process of nickel-based single-crystal superalloy blades prepared using the large-module method. It measures the temperature field distribution along the chord length at the edge transition area of ​​each single-crystal blade in the large module through directional solidification experiments, obtaining the temperature field change of the blade edge when it is pulled to the vicinity of the single-crystal furnace baffle, and then adjusting the pulling rate and heater temperature at this location. This method allows for detailed control of the directional solidification process of large-module single-crystal blades, reducing the probability of defects such as impurities and small-angle grain boundaries caused by temperature inhomogeneity at the edge transition area, improving the casting yield and stability of large-module single-crystal blades, enhancing the uniformity and consistency of the microstructure, and ultimately reducing the preparation cost of single-crystal blades. The present invention uses a pre-embedded thermocouple method to measure the temperature field distribution during the directional solidification process of large-module single-crystal alloy blades, and adjusts the pulling rate and heater temperature accordingly to improve the temperature field uniformity of the single-crystal alloy prepared by the large module and suppress defect generation. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a wax mold module for a large-module nickel-based single-crystal blade according to a preferred embodiment of the method for adjusting the directional solidification parameters of a large-module nickel-based single-crystal blade according to the present invention.

[0027] Figure 2 for Figure 1 A schematic diagram showing the embedding position of the ceramic tube on the wax mold of the nickel-based single crystal blade in the embodiment shown.

[0028] Figure 3 for Figure 1 The microscopic morphology photographs of the transition portion of the flange in the illustrated embodiment are shown in the following: (a) is a eutectic morphology photograph of the transition portion before the directional solidification parameters are adjusted, and (b) is a eutectic morphology photograph of the transition portion after the directional solidification parameters are adjusted.

[0029] Figure 4 for Figure 1 The images shown in the embodiment depict defects at the transition area of ​​the flange, wherein: (a) is a photograph of the transition area with impurities before the directional solidification parameters are adjusted, and (b) is a photograph of the transition area without impurities after the directional solidification parameters are adjusted.

[0030] The diagram is labeled as follows: 1-pouring cup, 2-sprue, 3-nickel-based single crystal blade wax model, 4-seed crystal, 5-base plate, 6-ceramic tube, 301-blade body, 302-edge plate, 303-tenon, 304-transfer part. Detailed Implementation

[0031] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0032] Example 1:

[0033] According to a preferred embodiment of the method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades of the present invention, the adjustment method includes the following steps in sequence:

[0034] Step 1: Press several nickel-based single-crystal blade wax molds according to the design requirements, and assemble the pouring cup 1, runner 2, nickel-based single-crystal blade wax mold 3, seed crystal 4, and base 5 from top to bottom to form a nickel-based single-crystal blade wax mold module. This wax mold module consists of several layers of longitudinally arranged nickel-based single-crystal blade wax molds 3 and several layers of radially arranged nickel-based single-crystal blade wax molds 3, which is the large module nickel-based single-crystal blade wax mold module. In the large module nickel-based single-crystal blade wax mold module, ceramic tubes 6 are embedded in the bottommost layer of nickel-based single-crystal blade wax molds located on the same radius. The specific structure is as follows. Figure 1 As shown;

[0035] Step 2: Seal the opening of the ceramic tube with a rubber stopper, then coat the outer surface of the large module nickel-based single crystal blade wax mold with several layers of shell and one layer of sealing slurry. After each layer is coated, dry it, then dewax and fire the shell to obtain the ceramic shell of the large module nickel-based single crystal blade.

[0036] Step 3: Remove the rubber stopper from the opening of the ceramic tube, then insert the thermocouple into the opening of the ceramic tube, and seal the opening of the ceramic tube with refractory slurry to fix the thermocouple in the ceramic tube.

[0037] Step 4: Place the large-module nickel-based single-crystal blade ceramic shell and the master alloy ingot into the heater and crucible of the vacuum induction melting furnace, respectively. Evacuate the vacuum induction melting furnace to a certain vacuum level. Heat the heater to the holding temperature of the large-module nickel-based single-crystal blade ceramic shell. Heat the crucible to make the master alloy ingot go through the melting, smelting and refining process in sequence. Then cool the master alloy liquid to the casting temperature. The casting temperature of the master alloy liquid is the holding temperature of the large-module nickel-based single-crystal blade ceramic shell.

[0038] Step 5: Pour the master alloy liquid into the ceramic shell of the large module nickel-based single crystal blade. After standing for a certain period of time, pull the ceramic shell of the large module nickel-based single crystal blade downwards at a certain pulling speed. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to be flush with the lower surface of the baffle below the heater, stop pulling and let it stand for a certain period of time. At this time, record the temperature values ​​measured by each thermocouple. Keep the heater temperature and pulling speed constant, and continue to pull the ceramic shell of the large module nickel-based single crystal blade downwards. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to a certain distance from the lower surface of the baffle below the heater, stop pulling and let it stand for a certain period of time. At this time, record the temperature values ​​measured by each thermocouple.

[0039] Step 6: Adjust the heater temperature and pulling rate according to the temperature values ​​measured by each thermocouple, and calculate the adjusted heater temperature, the temperature parameters of the nickel-based single crystal blade, the adjusted pulling rate of the nickel-based single crystal blade, and the adjusted pulling rate of the ceramic shell of the large module nickel-based single crystal blade.

[0040] Step 7: Re-prepare the ceramic shell of the large module nickel-based single crystal blade according to the operations of Step 1 to Step 3, but no longer embed ceramic tubes on the nickel-based single crystal blade wax model; heat the re-prepare ceramic shell of the large module nickel-based single crystal blade and the master alloy ingot according to the operation of Step 4, at which time the heater temperature is the original heater temperature;

[0041] Step 8: Pour the master alloy liquid into the newly prepared large-module nickel-based single-crystal blade ceramic shell. After standing for a certain period of time, pull the large-module nickel-based single-crystal blade ceramic shell downwards at the original pulling rate. When the upper surface of the edge plate of the bottommost nickel-based single-crystal blade is pulled to be flush with the lower surface of the baffle below the heater, change the original heater temperature to the adjusted heater temperature and the original pulling rate to the adjusted pulling rate. Continue to pull at a uniform speed with the adjusted heater temperature and the adjusted pulling rate. When the upper surface of the edge plate of the bottommost nickel-based single-crystal blade is pulled to a certain distance from the lower surface of the baffle below the heater, change the adjusted heater temperature to the original heater temperature and the adjusted pulling rate to the original pulling rate. The heater temperature adjustment process and pulling rate adjustment process of the other layers of the large-module nickel-based single-crystal blade ceramic shell are the same as those of the bottommost layer until the pulling is completed. Take out the large-module nickel-based single-crystal blade ceramic shell, knock off the shell, and you will get the large-module nickel-based single-crystal blade.

[0042] In step one, the nickel-based single-crystal blade wax model 3 consists of a blade body 301, a rim plate 302, and a tenon 303. The transition connection between the blade body 301 and the rim plate 302 is the transition part 304, and the specific structure is as follows: Figure 2 As shown; the longitudinally arranged nickel-based single crystal blade wax mold has three layers, and the radially arranged nickel-based single crystal blade wax mold has three layers; three ceramic tubes are embedded on the nickel-based single crystal blade wax mold, and the three ceramic tubes are equally spaced at the transition part between the blade body and the edge plate of the nickel-based single crystal blade, and the ceramic tubes form a 45° angle with the upper surface of the edge plate of the nickel-based single crystal blade.

[0043] In step two, the shell is coated with alternating layers of corundum powder slurry and corundum sand, and the sealing layer is coated with corundum powder slurry, for a total of 7.5 layers.

[0044] In step four, the vacuum degree in the vacuum induction melting furnace is 5 Pa, and the heater temperature is 1530℃.

[0045] In step five, the master alloy liquid is poured into the ceramic shell of the large module nickel-based single crystal blade. After standing for 1.5 minutes, the large module nickel-based single crystal blade ceramic shell is pulled downwards at a pulling speed of 3.5 mm / s. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to be flush with the lower surface of the baffle below the heater, the pulling is stopped and the shell is left to stand for 10-15 seconds. At this time, the temperature values ​​measured by each thermocouple are recorded. If the nickel-based single crystal blades are numbered 1#, 2#, ... n# from the inner layer to the outer layer, then the temperature value measured by each thermocouple is T. 1a T 1b T 1c T 2a T 2b T 2c......T na T nb T nc .

[0046] Maintaining the heater temperature at 1530℃ and the pulling speed at 3.5mm / s, continue pulling down the ceramic shell of the large module nickel-based single-crystal blades. When the upper surface of the edge plate of the lowest nickel-based single-crystal blade is pulled down to 7mm from the lower surface of the baffle below the heater, stop pulling and let it stand for 12s. Record the temperature values ​​measured by each thermocouple at this time as T. 1a '、T 1b '、T 1c '、T 2a '、T 2b '、T 2c '.......T na '、T nb '、T nc '.

[0047] In step six, the adjusted heater temperature is In the formula: T1 is the original heater temperature, °C; T2 is the adjusted heater temperature, °C.

[0048] The temperature parameters of nickel-based single crystal blades are Where: M i Let be the temperature parameter of the i-th nickel-based single crystal blade, also known as the intermediate parameter, in °C.

[0049] The adjusted pulling rate of the nickel-based single crystal blade is V i2 =V1*(T ia '-T ic ') / M i In the formula: V1 is the original pulling speed, mm / s; V i2 M represents the adjusted pulling rate of the i-th nickel-based single crystal blade, in mm / s; i Let be the temperature parameter of the i-th nickel-based single crystal blade, also known as the intermediate parameter, in °C.

[0050] The adjusted pulling rate of the large module nickel-based single crystal blade ceramic shell is: Where: V2 is the adjusted pulling speed, mm / s; V i2 is the adjusted pulling speed of the i-th nickel-based single crystal blade, in mm / s; n is a natural number.

[0051] In step eight, the master alloy liquid is poured into the newly prepared large module nickel-based single crystal blade ceramic shell and left to stand for 1.5 minutes. When the upper surface of the edge plate of the lowest nickel-based single crystal blade is pulled to 7 mm from the lower surface of the baffle below the heater, the adjusted heater temperature is changed back to the original heater temperature, and the adjusted pulling rate is adjusted back to the original pulling rate.

[0052] In this embodiment, the microscopic morphology photograph of the flange transition area is as follows: Figure 3 As shown, (a) is a photograph of the eutectic morphology of the transition area before the directional solidification parameters are adjusted, and (b) is a photograph of the eutectic morphology of the transition area after the directional solidification parameters are adjusted; photographs of defects at the transition area of ​​the flange plate are shown below. Figure 4 As shown in the figure, (a) is a photograph of the transition area with impurities before the adjustment of the directional solidification parameters, and (b) is a photograph of the transition area without impurities after the adjustment of the directional solidification parameters. It can be seen from the figure that after the adjustment of the process parameters of directional solidification, the eutectic at the edge plate transition area of ​​the cast nickel-based single crystal blade is significantly reduced, and there are no impurity defects.

[0053] In this embodiment, the pressing of the nickel-based single-crystal blade wax mold, the preparation of the nickel-based single-crystal blade ceramic shell (including slurry preparation, drying process, dewaxing process, calcination process, etc.), the melting and refining of the master alloy ingot, and the directional solidification process can all be carried out using traditional techniques, and no special requirements are placed on the process parameters. The casting temperature, shell temperature, and other parameters of the alloy are selected according to the solidus and liquidus temperatures of the nickel-based single-crystal alloy used.

[0054] The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades in this embodiment is applicable to the directional solidification process of nickel-based single-crystal superalloy blades prepared using the large-module method. By measuring the temperature field distribution along the chord length at the edge transition area of ​​each single-crystal blade in the large module through directional solidification experiments, the temperature field change of the blade edge when pulled to the vicinity of the single-crystal furnace baffle is obtained, and the pulling rate and heater temperature at this location are then adjusted. This method allows for detailed control of the directional solidification process of large-module single-crystal blades, reducing the probability of defects such as impurities and small-angle grain boundaries caused by temperature inhomogeneity at the edge transition area, improving the casting yield and stability of large-module single-crystal blades, enhancing the uniformity and consistency of the microstructure, and ultimately reducing the manufacturing cost of single-crystal blades. This embodiment uses the pre-embedded thermocouple method to measure the temperature field distribution during the directional solidification process of large-module single-crystal alloy blades, and adjusts the pulling rate and heater temperature accordingly to improve the temperature field uniformity of the single-crystal alloy prepared by the large module and suppress defect generation.

[0055] Example 2:

[0056] Another preferred embodiment of the method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to the present invention has the same process flow, technical principle, and beneficial effects as Embodiment 1, except that:

[0057] In step two, the shell is coated with alternating layers of corundum powder slurry and corundum sand, and the sealing layer is coated with corundum powder slurry, for a total of 6.5 layers.

[0058] In step four, the vacuum degree in the vacuum induction melting furnace is 4 Pa, and the heater temperature is 1520℃.

[0059] In step five, the master alloy liquid is poured into the ceramic shell of the large module nickel-based single crystal blade. After standing for 1 minute, the ceramic shell of the large module nickel-based single crystal blade is pulled downward at a pulling speed of 2.5 mm / s. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to be flush with the lower surface of the baffle below the heater, the pulling is stopped and it is left to stand for 10 seconds. Keeping the heater temperature at 1520℃ and the pulling speed at 2.5 mm / s, the ceramic shell of the large module nickel-based single crystal blade is pulled downward. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to 5 mm from the lower surface of the baffle below the heater, the pulling is stopped and it is left to stand for 10 seconds.

[0060] In step eight, the master alloy liquid is poured into the newly prepared large module nickel-based single crystal blade ceramic shell and left to stand for 1 minute. When the upper surface of the edge plate of the lowest nickel-based single crystal blade is pulled to 5 mm from the lower surface of the baffle below the heater, the adjusted heater temperature is changed back to the original heater temperature, and the adjusted pulling rate is adjusted back to the original pulling rate.

[0061] Example 3:

[0062] Another preferred embodiment of the method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to the present invention has the same process flow, technical principle, and beneficial effects as Embodiment 1, except that:

[0063] In step two, the shell is coated with corundum powder slurry and corundum sand alternately, and the sealing layer is coated with corundum powder slurry, for a total of 8.5 layers.

[0064] In step four, the vacuum degree in the vacuum induction melting furnace is 6 Pa, and the heater temperature is 1540℃.

[0065] In step five, the master alloy liquid is poured into the ceramic shell of the large module nickel-based single crystal blade. After standing for 1 minute, the ceramic shell of the large module nickel-based single crystal blade is pulled downward at a pulling speed of 5 mm / s. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to be flush with the lower surface of the baffle below the heater, the pulling is stopped and it is left to stand for 15 seconds. Keeping the heater temperature at 1540℃ and the pulling speed at 5 mm / s, the ceramic shell of the large module nickel-based single crystal blade is pulled downward. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to 8 mm from the lower surface of the baffle below the heater, the pulling is stopped and it is left to stand for 15 seconds.

[0066] In step eight, the master alloy liquid is poured into the newly prepared large module nickel-based single crystal blade ceramic shell and left to stand for 2 minutes. When the upper surface of the edge plate of the lowest nickel-based single crystal blade is pulled to 8 mm from the lower surface of the baffle below the heater, the adjusted heater temperature is changed back to the original heater temperature, and the adjusted pulling rate is adjusted back to the original pulling rate.

[0067] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant progress of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive experimentation. For each parameter and the combinations thereof, the inventors have recorded a large amount of experimental data; however, due to space limitations, the specific experimental data is not disclosed here.

[0068] Those skilled in the art will readily understand that the method for adjusting the directional solidification parameters of the large-module nickel-based single-crystal blades of the present invention includes any combination of the inventive content and specific embodiments described in the above specification and the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for adjusting the directional solidification parameters of a large-module nickel-based single-crystal blade, characterized in that: The adjustment method includes the following steps in sequence: Step 1: Press several nickel-based single crystal blade wax molds according to the design requirements, and assemble the pouring cup, runner, nickel-based single crystal blade wax mold, seed crystal and base plate from top to bottom to form a nickel-based single crystal blade wax mold module. This wax mold module consists of several layers of longitudinally arranged nickel-based single crystal blade wax molds and several layers of radially arranged nickel-based single crystal blade wax molds, which is the large module nickel-based single crystal blade wax mold module. In the large module nickel-based single crystal blade wax mold module, ceramic tubes are embedded in the nickel-based single crystal blade wax molds located on the same radius in the bottom layer; Step 2: Seal the opening of the ceramic tube with a rubber stopper, then coat the outer surface of the large module nickel-based single crystal blade wax mold with several layers of shell and one layer of sealing slurry. After each layer is coated, dry it, then dewax and fire the shell to obtain the ceramic shell of the large module nickel-based single crystal blade. Step 3: Remove the rubber stopper from the opening of the ceramic tube, then insert the thermocouple into the opening of the ceramic tube, and seal the opening of the ceramic tube with refractory slurry to fix the thermocouple in the ceramic tube. Step 4: Place the large-module nickel-based single-crystal blade ceramic shell and the master alloy ingot into the heater and crucible of the vacuum induction melting furnace, respectively. Evacuate the vacuum induction melting furnace to a certain vacuum level. Heat the heater to the holding temperature of the large-module nickel-based single-crystal blade ceramic shell. Heat the crucible to make the master alloy ingot go through the melting, smelting and refining process in sequence. Then cool the master alloy liquid to the casting temperature. The casting temperature of the master alloy liquid is the holding temperature of the large-module nickel-based single-crystal blade ceramic shell. Step 5: Pour the master alloy liquid into the ceramic shell of the large module nickel-based single crystal blade. After standing for a certain period of time, pull the ceramic shell of the large module nickel-based single crystal blade downwards at a certain pulling speed. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to be flush with the lower surface of the baffle below the heater, stop pulling and let it stand for a certain period of time. At this time, record the temperature values ​​measured by each thermocouple. Keep the heater temperature and pulling speed constant, and continue to pull the ceramic shell of the large module nickel-based single crystal blade downwards. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to a certain distance from the lower surface of the baffle below the heater, stop pulling and let it stand for a certain period of time. At this time, record the temperature values ​​measured by each thermocouple. Step 6: Adjust the heater temperature and pulling rate according to the temperature values ​​measured by each thermocouple, and calculate the adjusted heater temperature, the temperature parameters of the nickel-based single crystal blade, the adjusted pulling rate of the nickel-based single crystal blade, and the adjusted pulling rate of the ceramic shell of the large module nickel-based single crystal blade. Step 7: Re-prepare the ceramic shell of the large module nickel-based single crystal blade according to the operations of Step 1 to Step 3, but no longer embed ceramic tubes on the nickel-based single crystal blade wax model; heat the re-prepare ceramic shell of the large module nickel-based single crystal blade and the master alloy ingot according to the operation of Step 4, at which time the heater temperature is the original heater temperature; Step 8: Pour the master alloy liquid into the newly prepared large-module nickel-based single-crystal blade ceramic shell. After standing for a certain period of time, pull the large-module nickel-based single-crystal blade ceramic shell downwards at the original pulling rate. When the upper surface of the edge plate of the bottommost nickel-based single-crystal blade is pulled to be flush with the lower surface of the baffle below the heater, change the original heater temperature to the adjusted heater temperature and the original pulling rate to the adjusted pulling rate. Continue to pull at the adjusted heater temperature and the adjusted pulling rate at a uniform speed. When the upper surface of the edge plate of the bottommost nickel-based single-crystal blade is pulled to a certain distance from the lower surface of the baffle below the heater, change the adjusted heater temperature to the original heater temperature and the adjusted pulling rate to the original pulling rate. The heater temperature adjustment process and pulling rate adjustment process of the other layers of the large-module nickel-based single-crystal blade ceramic shell are the same as those of the bottommost layer, until the pulling is completed. Take out the large-module nickel-based single-crystal blade ceramic shell, knock off the shell, and you will get the large-module nickel-based single-crystal blade.

2. The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to claim 1, characterized in that: In step one, there are at least two layers of longitudinally arranged nickel-based single crystal blade wax molds and at least two layers of radially arranged nickel-based single crystal blade wax molds; three ceramic tubes are embedded on the nickel-based single crystal blade wax molds, and the three ceramic tubes are equally spaced at the transition part between the blade body and the edge plate of the nickel-based single crystal blade, with the ceramic tubes forming a 45° angle with the upper surface of the edge plate of the nickel-based single crystal blade.

3. The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to claim 2, characterized in that: In step two, the shell is coated with corundum powder slurry and corundum sand alternately, and the sealing layer is coated with corundum powder slurry, with a total of 6.5-8.5 layers.

4. The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to claim 3, characterized in that: In step four, the vacuum degree in the vacuum induction melting furnace is 4-6 Pa, and the heater temperature is 1520-1540℃.

5. The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to claim 4, characterized in that: In step five, the master alloy liquid is poured into the ceramic shell of the large module nickel-based single crystal blade. After standing for 1-2 minutes, the large module nickel-based single crystal blade ceramic shell is pulled downwards at a pulling speed of 2.5-5 mm / s. When the upper surface of the edge plate of the bottommost nickel-based single crystal blade is pulled to be flush with the lower surface of the baffle below the heater, the pulling is stopped and the shell is left to stand for 10-15 seconds. At this time, the temperature values ​​measured by each thermocouple are recorded. If the nickel-based single crystal blades are numbered 1#, 2#, ... n# from the inner layer to the outer layer, then the temperature value measured by each thermocouple is T. 1a T 1b T 1c T 2a T 2b T 2c ......T na T nb T nc .

6. The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to claim 5, characterized in that: In step five, maintain the heater temperature at 1520-1540℃ and the pulling speed at 2.5-5mm / s, and continue pulling down the ceramic shell of the large module nickel-based single crystal blades. When the upper surface of the edge plate of the lowest nickel-based single crystal blade is pulled down to 5-8mm from the lower surface of the baffle below the heater, stop pulling and let it stand for 10-15s. At this time, record the temperature values ​​measured by each thermocouple as T. 1a '、T 1b '、T 1c '、T 2a '、T 2b '、T 2c '.......T na '、T nb '、T nc '.

7. The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to claim 6, characterized in that: In step six, the adjusted heater temperature is In the formula: T1 is the original heater temperature, °C; T2 is the adjusted heater temperature, °C; The temperature parameters of the nickel-based single crystal blade are Where: M i Let be the temperature parameter of the i-th nickel-based single crystal blade, also known as the intermediate parameter, in °C; The adjusted pulling rate of the nickel-based single crystal blade is V i2 =V1*(T ia '-T ic ') / M i In the formula: V1 is the original pulling speed, mm / s; V i2 M represents the adjusted pulling rate of the i-th nickel-based single crystal blade, in mm / s; i Let be the temperature parameter of the i-th nickel-based single crystal blade, also known as the intermediate parameter, in °C; The adjusted pulling rate of the large module nickel-based single crystal blade ceramic shell is: Where: V2 is the adjusted pulling speed, mm / s; V i2 is the adjusted pulling speed of the i-th nickel-based single crystal blade, in mm / s; n is a natural number.

8. The method for adjusting the directional solidification parameters of large-module nickel-based single-crystal blades according to claim 7, characterized in that: In step eight, the master alloy liquid is poured into the newly prepared large module nickel-based single crystal blade ceramic shell and left to stand for 1-2 minutes. When the upper surface of the edge plate of the lowest nickel-based single crystal blade is pulled to 5-8 mm from the lower surface of the baffle below the heater, the adjusted heater temperature is changed back to the original heater temperature, and the adjusted pulling rate is adjusted back to the original pulling rate.

Images