A heat treatment method for reducing the recrystallization tendency of a single crystal cast of a high-temperature alloy
By eliminating the alkaline boiling and descaling process, the castings with shells are directly heat-treated and the shells are manually removed, which solves the problem of recrystallization of single-crystal turbine blades during heat treatment, improves the yield and service performance, and reduces production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- RED SILVER METAL CO LTD
- Filing Date
- 2026-06-10
- Publication Date
- 2026-07-31
AI Technical Summary
In the existing technology for casting single-crystal turbine blades, the alkaline boiling and descaling process before heat treatment causes recrystallization due to the collision, squeezing, and bumping of the castings during transportation, resulting in grain defects and affecting service performance.
A heat treatment method with low recrystallization tendency for high-temperature alloy single crystal castings is adopted, which eliminates the alkaline boiling and desquamation process. The castings with shells are directly heat treated, and the shells are manually removed after heat treatment to avoid recrystallization.
It effectively reduces recrystallization, improves the yield of castings, enhances the service performance and safety of blades, and reduces production costs and cycle time.
Smart Images
Figure CN122484658A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-temperature alloy investment casting technology, specifically relating to a heat treatment method for high-temperature alloy single crystal castings with low recrystallization tendency. Background Technology
[0002] Blades are crucial components of aero-engines, and single-crystal blades for aero-engines are generally manufactured using investment casting. The process begins with the structural design of the mold assembly, followed by pressing and assembling of wax molds. After degreasing, the wax mold assembly undergoes coating, sanding, dewaxing, and firing to prepare the mold shell. Finally, the refined alloy liquid is poured into the mold shell in a vacuum directional solidification furnace, completing the casting process. However, due to the poor collapsibility of the mold shell, it cannot be completely removed during the shell removal process. Therefore, the current production process for single-crystal blades typically involves: after casting, the blade undergoes an alkaline boiling and shell removal process; only after the residual shell is completely removed is heat treatment performed. However, the collisions and compression caused by the dense arrangement of the castings during alkaline boiling and shell removal, as well as the handling and impacts during transport before heat treatment, generate minute plastic strains sufficient to induce recrystallization in the single-crystal turbine blades during heat treatment. This recrystallization inevitably leads to a significant reduction in the service performance of the single-crystal alloy turbine blades, especially their high-temperature performance. Therefore, reducing recrystallization behavior during the heat treatment of cast single-crystal turbine blades by adopting appropriate process methods is an important step in improving the yield of single-crystal alloy turbine blades for aero-engines.
[0003] Therefore, there is an urgent need for a simple and effective process to reduce the recrystallization defects that are easily generated during the preparation of cast turbine blades. This would not only help improve the yield of castings, but also help improve the service performance and safety of turbine blades. Summary of the Invention
[0004] The technical problem this invention aims to solve is to address the shortcomings of the prior art by providing a heat treatment method for high-temperature alloy single-crystal castings with low recrystallization tendency. This method eliminates the need for alkaline boiling and descrambling after casting, directly subjecting the shelled castings to heat treatment. After heat treatment, the shell is manually removed from the casting assembly, reducing recrystallization. This method is applicable to all single-crystal blades, is simple to process, highly operable, and effectively improves the casting yield.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a heat treatment method for high-temperature alloy single crystal castings with low recrystallization tendency, comprising the following steps: S1. Inject wax into the product mold, and after the mold material cools, a wax mold of the product to be cast is obtained; weld the wax mold to the gating system to obtain a wax mold assembly. S2. After cleaning the surface oil film of the wax mold obtained in S1, it is repeatedly immersed in refractory coating and sanded. After drying and hardening, it forms a shell. The shell is then dewaxed and fired. S3. Pour the high-temperature alloy liquid into the shell obtained in S2. After cooling and solidification, perform slight shell cleaning on the casting assembly, and then directly heat treat the casting with shell. S4. After the heat treatment of the castings is completed, the castings are sandblasted to remove the residual shell.
[0006] Preferably, the dewaxing method in S2 is as follows: the shell is dewaxed by steam pressure using a dewaxing kettle, with the pouring cup of the shell placed downwards, the dewaxing temperature is 180℃~200℃, the dewaxing time is 13min~15min, and the pressure is 7.9bar~8.5bar.
[0007] Preferably, the calcination temperature in S2 is 940℃~960℃, and the calcination time is 4h~6h.
[0008] Preferably, the high-temperature alloy liquid poured in S3 is a nickel-based high-temperature alloy liquid.
[0009] Preferably, the nickel-based superalloy liquid is composed of the following raw materials in the indicated mass fractions: C: 0.04%~0.06%, Cr: 6.75%~7.25%, Co: 7.00%~8.00%, W: 4.75%~5.25%, Mo: 1.30%~1.70%, Al: 6.0%~6.40%, Re: 2.75%~3.25%, Hf: 0.12%~0.18%, B: 0.003%~0.005%, with the balance being Ni.
[0010] Preferably, the pouring temperature in S3 is 1500℃~1520℃.
[0011] Preferably, the heat treatment process in S3 is as follows: first, the casting with shell is subjected to solution treatment, and then the casting after solution treatment is subjected to two aging treatments; The solution treatment involves a heating rate of 10℃ / min, followed by a rapid increase to 850℃±10℃ over 90 minutes at maximum power, followed by a holding time of 30 minutes and a partial pressure of 100Pa±10Pa. Then, the temperature is increased to 1200℃±10℃ over 30 minutes at maximum power. Next, the temperature is slowly increased to 1280℃±10℃ over 90 minutes and held for 120 minutes±10 minutes. Then, the temperature is slowly increased to 1290℃±10℃ over 10 minutes and held for 60 minutes±10 minutes. Finally, the temperature is slowly increased to 1300℃±10℃ over 10 minutes and held for 120 minutes±10 minutes. After the holding time, the temperature is cooled by argon gas, first decreasing to below 1093℃ over 4 minutes, then cooling to 650℃±28℃ over 60 minutes, and finally cooling to below 100℃ at any rate. In the two aging treatments, the first aging treatment involved a heating rate of 10℃ / min, with the temperature increased to 850℃±10℃ over 90 minutes at maximum power, held for 30 minutes, and the partial pressure reduced to 100Pa±10Pa. Then, the temperature was increased to 1100℃±10℃ over 30 minutes at maximum power. Next, the temperature was slowly increased to 1120℃±10℃ over 20 minutes and held for 240 minutes±10 minutes. After the holding period, the temperature was cooled with argon gas, dropping below 1080℃ within 1 minute, and then cooled to 65℃ over 60 minutes. The first aging process involves heating to 0℃±28℃ and then cooling at any rate to below 100℃. The second aging process is as follows: Heat to 850℃±10℃ at maximum power within 90 minutes, hold for 30 minutes, and reduce the partial pressure to 100Pa±10Pa; then heat to 1060℃±10℃ at maximum power within 30 minutes; then slowly heat to 1080℃±10℃ for 20 minutes, hold for 240 minutes±10 minutes; after holding, purge with argon gas and cool to 650℃±28℃ within 6 minutes, then cool to room temperature at any rate. If the temperature does not reach 650℃±28℃ within 6 minutes after holding, it is permissible to heat again to 1080℃±10℃, hold for 15-20 minutes, and then cool again to meet the requirement of cooling to 650℃±28℃ within 6 minutes.
[0012] Preferably, the material used for sandblasting and shell cleaning in S4 is 180# corundum sand.
[0013] Compared with the prior art, the present invention has the following significant technical effects: 1. This invention provides a heat treatment method for high-temperature alloy single-crystal castings with low recrystallization tendency. This method eliminates the alkaline boiling and shell removal process after casting is completed and directly heat-treats the castings with shells. This effectively avoids the mutual collision and squeezing caused by the dense placement of castings during alkaline boiling and shell removal, as well as the grain defects caused by the handling of castings during the transfer process before heat treatment. This reduces the occurrence of recrystallization in the castings. After heat treatment, the castings are manually cleaned, which effectively improves the yield of the castings.
[0014] 2. The heat treatment method for high-temperature alloy single crystal castings with low recrystallization tendency of the present invention is applicable to all single crystal blades. The process is simple, highly operable, and can reduce production cycle and cost. It not only helps to improve the qualification rate of castings, but also helps to improve the service performance and service safety of blades.
[0015] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the heat treatment of the shell casting in Embodiment 1 of the present invention; Figure 2 This is a microstructure diagram of the shell casting after heat treatment in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram showing the placement of castings in Comparative Example 1 of the present invention after alkaline boiling and descaling. Figure 4 This is a schematic diagram of surface recrystallization after heat treatment of the alkaline boiling and descaling casting in Comparative Example 1 of the present invention. Figure 5 This is a schematic diagram of surface recrystallization after heat treatment of the alkaline boiling and descaling casting in Comparative Example 2 of the present invention. Detailed Implementation
[0017] Example 1
[0018] This embodiment describes a heat treatment method for high-temperature alloy single-crystal castings with low recrystallization tendency, wherein the high-temperature alloy single-crystal casting is a single-crystal turbine alloy blade. The method includes the following steps: S1. Inject wax into the product mold. After the mold material cools, visually inspect the wax model. If the surface has a high degree of smoothness and there are no defects such as air bubbles or oil marks, the product wax model to be cast is obtained. Weld the wax model to the gating system to obtain the wax model module.
[0019] S2. After cleaning the surface oil film of the wax mold obtained in S1, repeatedly immerse it in refractory coating and sprinkle it with sand. After drying and hardening, a shell is formed. The shell is then dewaxed and fired. The dewaxing method is as follows: the shell is dewaxed under steam pressure using a dewaxing kettle. The pouring cup of the shell is placed downwards and stably on the dewaxing cart. When the indicated pressure reaches 8.2 bar, the loading cart is gently pushed into the dewaxing kettle, the door is closed and locked, and the air inlet valve is immediately opened. The dewaxing temperature is 190℃ and the dewaxing time is 15 minutes. After the program is completed, the hollow shell is removed. The shell is fired at 950℃ for 4 hours.
[0020] S3. Pour nickel-based superalloy liquid into the shell obtained in S2 at 1520℃. After the alloy liquid cools and solidifies, perform slight shell cleaning on the casting assembly, and then directly heat treat the casting with shell; the heat treatment diagram of the casting with shell is shown below. Figure 1 As shown; The nickel-based superalloy liquid is composed of the following raw materials in the indicated mass fractions: C: 0.04%~0.06%, Cr: 6.75%~7.25%, Co: 7.00%~8.00%, W: 4.75%~5.25%, Mo: 1.30%~1.70%, Al: 6.0%~6.40%, Re: 2.75%~3.25%, Hf: 0.12%~0.18%, B: 0.003%~0.005%, with the balance being Ni; The heat treatment process is as follows: First, the casting with shell is subjected to solution treatment, with a heating rate of 10℃ / min, and the temperature is raised to 850℃ within 90 minutes at maximum power, held for 30 minutes, and the partial pressure is reduced to 100Pa; then the temperature is raised to 1200℃ within 30 minutes at maximum power; then the temperature is slowly raised to 1280℃ within 90 minutes and held for 120 minutes; then the temperature is slowly raised to 1290℃ within 10 minutes and held for 60 minutes; then the temperature is slowly raised to 1300℃ within 10 minutes and held for 120 minutes; after the holding period, argon gas is used for cooling, and the temperature is reduced to 900℃ within 4 minutes, then cooled to 650℃ within 60 minutes, and finally cooled to room temperature at 10℃ / min. The solution-treated castings were then subjected to two aging treatments. The first aging treatment involved a heating rate of 10℃ / min, with the temperature increased to 850℃ at maximum power within 90 minutes, held for 30 minutes, and the partial pressure reduced to 100Pa. Then, the temperature was increased to 1100℃ at maximum power within 30 minutes. Next, the temperature was slowly increased to 1120℃ over 20 minutes and held for 240 minutes. After the holding period, argon gas was used for cooling, reducing the temperature to 1000℃ within 1 minute, then to 650℃ over 60 minutes, and finally to room temperature at a rate of 10℃ / min. The second aging treatment involved increasing the temperature to 850℃ at maximum power within 90 minutes, holding for 30 minutes, and the partial pressure reduced to 100Pa. Then, the temperature was increased to 1060℃ at maximum power within 30 minutes. Next, the temperature was slowly increased to 1080℃ over 20 minutes and held for 240 minutes. After the holding period, argon gas was used for cooling, reducing the temperature to 650℃ over 6 minutes, and finally to room temperature at a rate of 10℃ / min.
[0021] S4. After heat treatment, perform manual shell removal by tapping the pouring cup and gating area to remove most of the shell. Do not tap the casting body. Then use 180# corundum sand to blow away the residual shell that is difficult to remove at the root of the casting. During the shell blowing process, do not blow sand on a certain part of the casting for a long time to avoid dimensional deformation of the casting.
[0022] The castings underwent low-magnification etching treatment, and defects were observed and statistically analyzed. Results showed no recrystallization caused by impact, resulting in a 100% pass rate. The castings were also dissected; the post-dissection microstructure is shown below. Figure 2 The castings after heat treatment with shell have a uniform microstructure and no component segregation. Their microstructure is basically consistent with that of conventionally heat-treated castings, which meets the requirements.
[0023] Comparative Example 1 Using the same single-crystal turbine alloy blades as in Example 1, the method includes the following steps: S1. Inject wax into the product mold. After the mold material cools, visually inspect the wax model. If the surface has a high degree of smoothness and there are no defects such as air bubbles or oil marks, the product wax model to be cast is obtained. Weld the wax model to the gating system to obtain the wax model module.
[0024] S2. After cleaning the surface oil film of the wax mold obtained in S1, repeatedly immerse it in refractory coating and sprinkle it with sand. After drying and hardening, a shell is formed. The shell is then dewaxed and fired. The dewaxing method is as follows: the shell is dewaxed under steam pressure using a dewaxing kettle. The pouring cup of the shell is placed face down and stably on the dewaxing cart. When the indicated pressure reaches 8.2 bar, the loading cart is gently pushed into the dewaxing kettle, the door is closed and locked, and the air inlet valve is immediately opened. The dewaxing temperature is 190℃ and the dewaxing time is 15 minutes. After the program is completed, the hollow shell is removed. The shell is fired at 950℃ for 4 hours.
[0025] S3. Pour nickel-based superalloy liquid into the shell obtained in S2 at 1520℃. After the alloy liquid cools and solidifies, perform a slight shell removal on the casting assembly, followed by an alkaline boiling shell removal process. The castings are arranged as follows: Figure 3 After the alkaline boiling is completed, the castings are cut into groups, and individual castings without residual shells on their surfaces are heat treated. The nickel-based superalloy liquid is composed of the following raw materials in the indicated mass fractions: C: 0.04%~0.06%, Cr: 6.75%~7.25%, Co: 7.00%~8.00%, W: 4.75%~5.25%, Mo: 1.30%~1.70%, Al: 6.0%~6.40%, Re: 2.75%~3.25%, Hf: 0.12%~0.18%, B: 0.003%~0.005%, with the balance being Ni; The heat treatment process is as follows: First, the casting with shell is subjected to solution treatment, with a heating rate of 10℃ / min, and the temperature is raised to 850℃ within 90 minutes at maximum power, held for 30 minutes, and the partial pressure is reduced to 100Pa; then the temperature is raised to 1200℃ within 30 minutes at maximum power; then the temperature is slowly raised to 1280℃ within 90 minutes and held for 120 minutes; then the temperature is slowly raised to 1290℃ within 10 minutes and held for 60 minutes; then the temperature is slowly raised to 1300℃ within 10 minutes and held for 120 minutes; after the holding period, argon gas is used for cooling, and the temperature is reduced to 900℃ within 4 minutes, then cooled to 650℃ within 60 minutes, and finally cooled to room temperature at 10℃ / min. The solution-treated castings were then subjected to two aging treatments. The first aging treatment involved a heating rate of 10℃ / min, with the temperature increased to 850℃ at maximum power within 90 minutes, held for 30 minutes, and the partial pressure reduced to 100Pa. Then, the temperature was increased to 1100℃ at maximum power within 30 minutes. Next, the temperature was slowly increased to 1120℃ over 20 minutes and held for 240 minutes. After the holding period, argon gas was used for cooling, reducing the temperature to 1000℃ within 1 minute, then to 650℃ over 60 minutes, and finally to room temperature at a rate of 10℃ / min. The second aging treatment involved increasing the temperature to 850℃ at maximum power within 90 minutes, holding for 30 minutes, and the partial pressure reduced to 100Pa. Then, the temperature was increased to 1060℃ at maximum power within 30 minutes. Next, the temperature was slowly increased to 1080℃ over 20 minutes and held for 240 minutes. After the holding period, argon gas was used for cooling, reducing the temperature to 650℃ over 6 minutes, and finally to room temperature at a rate of 10℃ / min.
[0026] After heat treatment, the castings underwent low-magnification etching to observe defects and compile a defect statistics report. The results showed that recrystallization caused by impacts was observed on the flanges and blade surfaces of the castings after alkaline boiling and descaling. Figure 4 The pass rate was 50%.
[0027] Comparative Example 2 Using the same single-crystal turbine alloy blades as in Example 1, the method includes the following steps: S1. Inject wax into the product mold. After the mold material cools, visually inspect the wax model. If the surface has a high degree of smoothness and there are no defects such as air bubbles or oil marks, the product wax model to be cast is obtained. Weld the wax model to the gating system to obtain the wax model module.
[0028] S2. After cleaning the surface oil film of the wax mold obtained in S1, repeatedly immerse it in refractory coating and sprinkle it with sand. After drying and hardening, a shell is formed. The shell is then dewaxed and fired. The dewaxing method is as follows: the shell is dewaxed under steam pressure using a dewaxing kettle. The pouring cup of the shell is placed face down and stably on the dewaxing cart. When the indicated pressure reaches 8.2 bar, the loading cart is gently pushed into the dewaxing kettle, the door is closed and locked, and the air inlet valve is immediately opened. The dewaxing temperature is 190℃ and the dewaxing time is 15 minutes. After the program is completed, the hollow shell is removed. The shell is fired at 950℃ for 4 hours.
[0029] S3. Pour nickel-based high-temperature alloy liquid into the shell obtained in S2 at 1520℃. After the alloy liquid cools and solidifies, perform slight shell removal on the casting group, followed by alkaline boiling to remove the shell. After alkaline boiling, cut the casting group and heat treat the individual castings without residual shell on the surface. The nickel-based superalloy liquid is composed of the following raw materials in the indicated mass fractions: C: 0.04%~0.06%, Cr: 6.75%~7.25%, Co: 7.00%~8.00%, W: 4.75%~5.25%, Mo: 1.30%~1.70%, Al: 6.0%~6.40%, Re: 2.75%~3.25%, Hf: 0.12%~0.18%, B: 0.003%~0.005%, with the balance being Ni; The heat treatment process is referenced in CN107243601A, specifically as follows: 1300℃ / 3h, AC. (air cooling to room temperature) + 1080℃ / 5h, AC. (air cooling to room temperature) + 870℃ / 16h, AC. (air cooling to room temperature).
[0030] After heat treatment, the castings underwent low-magnification etching to observe defects and compile a defect statistics report. The results showed that recrystallization caused by impacts was observed on the flanges and blade surfaces of the castings after alkaline boiling and descaling. Figure 5 The pass rate was 60%.
[0031] Example 2
[0032] This embodiment describes a heat treatment method for high-temperature alloy single-crystal castings with low recrystallization tendency, wherein the high-temperature alloy single-crystal casting is a single-crystal turbine alloy blade. The method includes the following steps: S1. Inject wax into the product mold. After the mold material cools, visually inspect the wax model. If the surface has a high degree of smoothness and there are no defects such as air bubbles or oil marks, the product wax model to be cast is obtained. Weld the wax model to the gating system to obtain the wax model module.
[0033] S2. After cleaning the surface oil film of the wax mold obtained in S1, repeatedly immerse it in refractory coating and sprinkle it with sand. After drying and hardening, a shell is formed. The shell is then dewaxed and fired. The dewaxing method is as follows: the shell is dewaxed under steam pressure using a dewaxing kettle. The pouring cup of the shell is placed face down and placed stably on the dewaxing cart. When the indicated pressure reaches 8.5 bar, the loading cart is gently pushed into the dewaxing kettle, the door is closed and locked, and the air inlet valve is immediately opened. The dewaxing temperature is 180℃ and the dewaxing time is 13 minutes. After the program is completed, the hollow shell is taken out. The shell is fired at 960℃ for 5 hours.
[0034] S3. Pour nickel-based high-temperature alloy liquid into the shell obtained in S2 at 1500℃. After the alloy liquid cools and solidifies, perform slight shell cleaning on the casting assembly, and then directly heat treat the casting with shell. The nickel-based superalloy liquid is composed of the following raw materials in the indicated mass fractions: C: 0.04%~0.06%, Cr: 6.75%~7.25%, Co: 7.00%~8.00%, W: 4.75%~5.25%, Mo: 1.30%~1.70%, Al: 6.0%~6.40%, Re: 2.75%~3.25%, Hf: 0.12%~0.18%, B: 0.003%~0.005%, with the balance being Ni; The heat treatment process is as follows: First, the casting with shell is subjected to solution treatment, with a heating rate of 10℃ / min, and the temperature is raised to 840℃ within 90 minutes at maximum power, held for 30 minutes until the partial pressure reaches 90Pa; then the temperature is raised to 1190℃ within 30 minutes at maximum power; then the temperature is slowly raised to 1270℃ within 90 minutes and held for 130 minutes; then the temperature is slowly raised to 1280℃ within 10 minutes and held for 70 minutes; then the temperature is slowly raised to 1290℃ within 10 minutes and held for 130 minutes; after the holding period, argon gas is used for cooling, and the temperature is lowered to 800℃ within 4 minutes, then cooled to 650℃ within 60 minutes, and finally cooled to room temperature at 10℃ / min. The solution-treated castings were then subjected to two aging treatments. The first aging treatment involved a heating rate of 10℃ / min, with the temperature increased to 840℃ within 90 minutes at maximum power, held for 30 minutes, and the partial pressure reduced to 90 Pa. Then, the temperature was increased to 1090℃ within 30 minutes at maximum power. The temperature was then slowly increased to 1110℃ within 20 minutes and held for 250 minutes. After the holding period, argon gas was used for cooling, reducing the temperature to 800℃ within 1 minute, then to 640℃ within 60 minutes, and finally to room temperature at a rate of 10℃ / min. The second aging treatment involved increasing the temperature to 840℃ within 90 minutes at maximum power, holding for 30 minutes, and the partial pressure reduced to 90 Pa. Then, the temperature was increased to 1050℃ within 30 minutes at maximum power. The temperature was then slowly increased to 1070℃ within 20 minutes and held for 250 minutes. After the holding period, argon gas was used for cooling, reducing the temperature to 640℃ within 6 minutes, and finally to room temperature at a rate of 10℃ / min.
[0035] S4. After heat treatment, perform manual shell removal by tapping the pouring cup and gating area to remove most of the shell. Do not tap the casting body. Then use 180# corundum sand to blow away the residual shell that is difficult to remove at the root of the casting. During the shell blowing process, do not blow sand on a certain part of the casting for a long time to avoid dimensional deformation of the casting.
[0036] The castings were subjected to low-magnification etching treatment. The defects in the castings were observed and statistically analyzed. No recrystallization caused by impact was found, and the pass rate was 90%.
[0037] Example 3
[0038] This embodiment describes a heat treatment method for high-temperature alloy single-crystal castings with low recrystallization tendency, wherein the high-temperature alloy single-crystal casting is a single-crystal turbine alloy blade. The method includes the following steps: S1. Inject wax into the product mold. After the mold material cools, visually inspect the wax model. If the surface has a high degree of smoothness and there are no defects such as air bubbles or oil marks, the product wax model to be cast is obtained. Weld the wax model to the gating system to obtain the wax model module.
[0039] S2. After cleaning the surface oil film of the wax mold obtained in S1, repeatedly immerse it in refractory coating and sprinkle it with sand. After drying and hardening, a shell is formed. The shell is then dewaxed and fired. The dewaxing method is as follows: the shell is dewaxed under steam pressure using a dewaxing kettle. The pouring cup of the shell is placed face down and placed stably on the dewaxing cart. When the indicated pressure reaches 7.9 bar, the loading cart is gently pushed into the dewaxing kettle, the door is closed and locked, and the air inlet valve is immediately opened. The dewaxing temperature is 200℃ and the dewaxing time is 14 minutes. After the program is completed, the hollow shell is taken out. The shell is fired at 940℃ for 6 hours.
[0040] S3. Pour nickel-based high-temperature alloy liquid into the shell obtained in S2 at 1510℃. After the alloy liquid cools and solidifies, perform slight shell cleaning on the casting assembly, and then directly heat treat the casting with shell. The nickel-based superalloy liquid is composed of the following raw materials in the indicated mass fractions: C: 0.04%~0.06%, Cr: 6.75%~7.25%, Co: 7.00%~8.00%, W: 4.75%~5.25%, Mo: 1.30%~1.70%, Al: 6.0%~6.40%, Re: 2.75%~3.25%, Hf: 0.12%~0.18%, B: 0.003%~0.005%, with the balance being Ni; The heat treatment process is as follows: First, the casting with shell is subjected to solution treatment, with a heating rate of 10℃ / min, and the temperature is raised to 860℃ within 90 minutes at maximum power, held for 30 minutes until the partial pressure reaches 110Pa; then, the temperature is raised to 1210℃ within 30 minutes at maximum power; then, the temperature is slowly raised to 1290℃ within 90 minutes and held for 110 minutes; then, the temperature is slowly raised to 1300℃ within 10 minutes and held for 50 minutes; then, the temperature is slowly raised to 1310℃ within 10 minutes and held for 110 minutes; after the holding period, argon gas is used for cooling, reducing the temperature to 1000℃ within 4 minutes, then to 670℃ within 60 minutes, and finally cooling to room temperature at 10℃ / min; then, the casting after solution treatment is subjected to two aging treatments. The heating rate for the first aging treatment is 10℃ / min, and the partial pressure is raised to 110Pa within 30 minutes at maximum power. The first aging process involved heating the temperature to 860°C at maximum power for 90 minutes, holding it for 30 minutes, and reducing the partial pressure to 110 Pa. Then, the temperature was increased to 1110°C at maximum power for 30 minutes. The temperature was then slowly increased to 1130°C over 20 minutes and held for 230 minutes. After holding, the temperature was cooled with argon gas, decreasing to 900°C within 1 minute, then to 670°C within 60 minutes, and finally cooled to room temperature at a rate of 10°C / min. The second aging process involved heating the temperature to 860°C at maximum power for 90 minutes, holding it for 30 minutes, and reducing the partial pressure to 110 Pa. Then, the temperature was increased to 1070°C at maximum power for 30 minutes. The temperature was then slowly increased to 1090°C over 20 minutes and held for 250 minutes. After holding, the temperature was cooled with argon gas, decreasing to 670°C within 6 minutes, and finally cooled to room temperature at a rate of 10°C / min.
[0041] S4. After heat treatment, perform manual shell removal by tapping the pouring cup and gating area to remove most of the shell. Do not tap the casting body. Then use 180# corundum sand to blow away the residual shell that is difficult to remove at the root of the casting. During the shell blowing process, do not blow sand on a certain part of the casting for a long time to avoid dimensional deformation of the casting.
[0042] The castings were subjected to low-magnification etching treatment. The defects in the castings were observed and statistically analyzed. No recrystallization caused by impact was found, and the pass rate was 90%.
[0043] This invention provides a heat treatment method for high-temperature alloy single-crystal castings with low recrystallization tendency. This method eliminates the need for alkaline boiling and descraping after casting, allowing direct heat treatment of the castings with their shells intact. This effectively avoids collisions and compression caused by the dense arrangement of castings during alkaline boiling and descraping, as well as grain defects caused by handling during transport before heat treatment. This reduces recrystallization. After heat treatment, the castings are manually descrambled. This method is applicable to all single-crystal blades, is simple, highly operable, reduces production time and costs, and effectively improves the yield of castings.
[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.
Claims
1. A heat treatment method for high-temperature alloy single-crystal castings with low recrystallization tendency, characterized in that, Includes the following steps: S1. Inject wax into the product mold, and after the mold material cools, a wax mold of the product to be cast is obtained; weld the wax mold to the gating system to obtain a wax mold assembly. S2. After cleaning the surface oil film of the wax mold obtained in S1, it is repeatedly immersed in refractory coating and sanded. After drying and hardening, it forms a shell. The shell is then dewaxed and fired. S3. Pour the high-temperature alloy liquid into the shell obtained in S2. After cooling and solidification, perform slight shell cleaning on the casting assembly, and then directly heat treat the casting with shell. S4. After the heat treatment of the castings is completed, the castings are sandblasted to remove the residual shell.
2. The method according to claim 1, characterized in that, The dewaxing method described in S2 is as follows: the shell is dewaxed by steam pressure using a dewaxing kettle, with the pouring cup of the shell placed downwards, the dewaxing temperature is 180℃~200℃, the dewaxing time is 13min~15min, and the pressure is 7.9bar~8.5bar.
3. The method according to claim 1, characterized in that, The roasting temperature described in S2 is 940℃~960℃, and the roasting time is 4h~6h.
4. The method according to claim 1, characterized in that, The high-temperature alloy liquid described in S3 is a nickel-based high-temperature alloy liquid.
5. The method according to claim 4, characterized in that, The nickel-based superalloy liquid is composed of the following raw materials in the indicated mass fractions: C: 0.04%~0.06%, Cr: 6.75%~7.25%, Co: 7.00%~8.00%, W: 4.75%~5.25%, Mo: 1.30%~1.70%, Al: 6.0%~6.40%, Re: 2.75%~3.25%, Hf: 0.12%~0.18%, B: 0.003%~0.005%, with the balance being Ni.
6. The method according to claim 1, characterized in that, The pouring temperature described in S3 is 1500℃~1520℃.
7. The method according to claim 1, characterized in that, The heat treatment process described in S3 is as follows: first, the casting with shell is subjected to solution treatment, and then the casting after solution treatment is subjected to two aging treatments. The solution treatment involves a heating rate of 10℃ / min, followed by heating to 850℃±10℃ within 90 min, holding for 30 min, and reducing the partial pressure to 100Pa±10Pa; then heating to 1200℃±10℃ within 30 min; then heating to 1280℃±10℃ within 90 min, holding for 120min±10 min; then heating to 1290℃±10℃ within 10 min, holding for 60min±10 min; then heating to 1300℃±10℃ within 10 min, holding for 120min±10 min; after holding, argon gas is used for cooling, reducing the temperature to below 1093℃ within 4 min, then cooling to 650℃±28℃ within 60 min, and finally cooling to below 100℃ at any rate. In the two aging treatments, the first aging treatment involved a heating rate of 10℃ / min, reaching 850℃±10℃ within 90 min, holding for 30 min, and reducing the partial pressure to 100Pa±10Pa; then, the temperature was increased to 1100℃±10℃ within 30 min; followed by a further increase to 1120℃±10℃ within 20 min, holding for 240min±10 min; after the holding period, argon gas was used for cooling, reducing the temperature to below 1080℃ within 1 min, and then cooling to 650℃ within 60 min. The first aging process involves heating to 850℃±10℃ within 90 minutes, holding for 30 minutes, and reducing the partial pressure to 100Pa±10Pa. Then, the temperature is increased to 1060℃±10℃ within 30 minutes. Next, the temperature is increased to 1080℃±10℃ within 20 minutes and held for 240 minutes±10 minutes. After the holding period, the temperature is purged with argon gas and cooled to 650℃±28℃ within 6 minutes. Finally, the temperature is cooled to room temperature at an arbitrary rate.
8. The method according to claim 1, characterized in that, The material used for sandblasting and shell cleaning in S4 is 180# corundum sand.