Heat treatment method of nickel-based superalloy

Abstract

The invention discloses a heat treatment method of a nickel-based superalloy, and belongs to the technical field of heat treatment of metal materials. According to the heat treatment method, superhigh-temperature solution treatment and stabilizing treatment are introduced, so that precise regulation and control on the microstructure of the nickel-based high-temperature alloy are realized, and the high-temperature strength, creep resistance and long-term structure stability of the nickel-based high-temperature alloy are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of heat treatment technology for metallic materials, and specifically relates to a heat treatment method for nickel-based high-temperature alloys. Background Technology

[0002] Nickel-based superalloys are key materials for manufacturing hot-end components (such as turbine blades and turbine disks) in high-end equipment like aero-engines and gas turbines. The excellent high-temperature performance of nickel-based superalloys mainly relies on the precipitation strengthening of the γ' phase (Ni3(Al, Ti)). The mechanical properties of nickel-based superalloys directly depend on the size, morphology, and distribution of the γ' phase, as well as the content of harmful phases (such as topologically close-packed phases and eutectic phases) in the γ matrix.

[0003] Currently, conventional heat treatment for such alloys often employs a two-step method of "solution treatment + aging treatment," for example, solution treatment at around 1100 °C followed by aging treatment at around 845 °C. However, the aforementioned conventional two-step heat treatment process of "solution treatment + aging treatment" has the following inherent limitations: Incomplete elimination of harmful phases: The solution temperature of 1100 ℃ is insufficient to completely dissolve the coarse and stable γ / γ' eutectic phases in the as-cast or forged structure of the alloy. These residual blocky eutectic phases not only fail to provide strengthening effects, but also become the source of crack initiation and propagation, severely deteriorating the alloy's creep strength and creep life.

[0004] Insufficient control over the morphology and distribution of the γ' phase: At the conventional solution temperature of 1100 °C, the alloying elements do not dissolve sufficiently, resulting in γ' phases that precipitate during subsequent aging being mostly spherical, making it difficult to achieve the ideal cubic shape of the γ' phase, and the spherical γ' phases also have poor size uniformity. Studies have confirmed that regularly arranged cubic γ' phases can more effectively hinder dislocation movement, thus providing a stronger strengthening effect than spherical γ' phases.

[0005] Poor thermal stability of the microstructure: During long-term high-temperature service, the γ' phase of the alloy microstructure obtained by the conventional two-step heat treatment process of "solution treatment + aging treatment" is prone to coarsening and morphological degradation (such as a decrease in cubicity) during the long-term high-temperature service process, which leads to accelerated performance degradation. Summary of the Invention

[0006] This invention is based on the inventors' discovery and understanding of the following facts and problems: Although there are methods in related technologies to improve the microstructure of nickel-based superalloys by increasing the solution temperature, simply increasing the solution temperature may lead to new problems such as abnormal grain growth and initial melting. Furthermore, simply adding processing steps, if the temperature is not properly selected, cannot synergistically solve the dual challenges of eutectic phase dissolution and γ' phase cubication. Therefore, there is an urgent need to develop an innovative heat treatment method for nickel-based superalloys that can synergistically and thoroughly eliminate harmful phases and guide the formation and stabilization of the γ' phase in an optimal cubic morphology, thereby breaking through the performance bottlenecks of existing nickel-based superalloys.

[0007] The purpose of this invention is to overcome the shortcomings of the conventional two-step heat treatment process of "solution treatment + aging treatment" and to provide a multi-stage, synergistic heat treatment method for nickel-based superalloys. This heat treatment method, through a specific temperature sequence design, aims to: maximize the dissolution of harmful eutectic phases through ultra-high temperature solution treatment; and create optimal conditions for the uniform nucleation and regular growth of the γ' phase through stabilization treatment, enabling it to form a well-developed cubic morphology after aging treatment, ultimately achieving a significant improvement in the high-temperature strength and creep life of the nickel-based superalloy.

[0008] This invention provides a heat treatment method for nickel-based superalloys, the heat treatment method comprising the following steps: Step 1. The nickel-based superalloy is subjected to ultra-high temperature solution treatment, followed by cooling; wherein the holding temperature of the ultra-high temperature solution treatment is 1180 ~ 1210 ℃, and the holding time of the ultra-high temperature solution treatment is 1 ~ 4 hours; Step 2. The nickel-based superalloy obtained after step 1 is subjected to medium-temperature solution treatment, followed by cooling; wherein the holding temperature of the medium-temperature solution treatment is 1090~1110 ℃, and the holding time of the medium-temperature solution treatment is 1~4 hours; Step 3. The nickel-based superalloy obtained after step 2 is subjected to stabilization treatment, followed by cooling; wherein the holding temperature of the stabilization treatment is 950 ~ 990 ℃, and the holding time of the stabilization treatment is 2 ~ 8 hours; Step 4. The nickel-based superalloy treated in Step 3 is subjected to aging treatment, and then cooled to room temperature; wherein the holding temperature of the aging treatment is 835 ~ 855 ℃, and the holding time of the aging treatment is 8 ~ 24 hours.

[0009] Compared with the conventional two-step heat treatment process of "solution treatment + aging treatment" and other existing improved processes, the heat treatment method of the present invention has the following advantages and technical effects: 1. Ultimate optimization of microstructure: Nearly complete elimination of eutectic phase: Ultra-high temperature solution treatment at 1180~1210 ℃ can almost completely dissolve harmful eutectic phase. The amount of harmful eutectic phase residue in the alloy obtained after heat treatment by the method of this invention is reduced by more than 90% compared with the alloy treated by the conventional two-step heat treatment process of "solution treatment + aging treatment", resulting in an extremely pure γ matrix.

[0010] 2. Perfect cubic transformation of the γ' phase: The key step of "stabilization treatment" at 950 ~ 990 ℃ ensures that the γ' phase nucleates at a high density and forms a cubic morphology with uniform size and regular arrangement after aging treatment, forming a coherent strain field with the γ matrix and maximizing the strengthening effect.

[0011] 3. High organizational stability: After undergoing a multi-stage heat treatment process involving "ultra-high temperature solution treatment + medium temperature solution treatment + stabilization treatment + aging treatment", the alloy microstructure of nickel-based superalloys is in a more stable state. Under long-term high-temperature exposure, the resistance to coarsening and morphological stability of the γ' phase are significantly enhanced.

[0012] 3. Significantly improved tensile properties: Significantly improved high-temperature strength: After being treated by the heat treatment method of the present invention, the yield strength and tensile strength of nickel-based superalloys in the temperature range of 750~850 ℃ are increased by 5%~20% compared with the alloys treated by the conventional two-step heat treatment process of "solution treatment + aging treatment".

[0013] 4. Creep life is significantly extended: After being treated by the heat treatment method of this invention, the clean grain boundaries and regular cubic γ' phase of the nickel-based superalloy greatly hinder dislocation movement and crack propagation, thus extending the creep fracture life of the alloy under typical service conditions by 100% to 300% or even more than that of alloys treated by the conventional two-step heat treatment process of "solution treatment + aging treatment".

[0014] 5. The process is controllable and has good reproducibility: The multi-stage temperature sequence design is scientific, with each step having a clear purpose, forming a synergistic overall process that avoids the risks of single high-temperature treatments, has good microstructure reproducibility, and is suitable for industrial production and quality control.

[0015] Optionally, in step 1, the holding temperature of the ultra-high temperature solution treatment is 1185 ~ 1195 ℃, and the holding time of the ultra-high temperature solution treatment is 2 ~ 4 hours.

[0016] Optionally, in step 1, the cooling method is to first quench the air at a rate of 50~80 ℃ / min or force-cool it to below 540 ℃, and then air-cool it to room temperature.

[0017] Optionally, in step 2, the holding temperature of the medium-temperature solution treatment is 1095 ~ 1105 ℃, and the holding time of the medium-temperature solution treatment is 2 ~ 4 hours.

[0018] Optionally, in step 2, the cooling method is to first quench the air at a rate of 50~80 ℃ / min or force-cool it to below 540 ℃, and then air-cool it to room temperature.

[0019] Optionally, in step 3, the holding temperature for the stabilization treatment is 960~970 ℃, and the holding time for the stabilization treatment is 6~8 hours.

[0020] Optionally, in step 3, the cooling method is to first quench the air or force-cool it to below 540°C at a rate of 50~80°C / min, and then air-cool it to room temperature.

[0021] Optionally, in step 4, the holding temperature of the aging treatment is 840~850 ℃, and the holding time of the aging treatment is 20~24 hours. Attached Figure Description

[0022] Figure 1 is a metallographic image of the nickel-based superalloy obtained by the heat treatment method of Example 1.

[0023] Figure 2 is a metallographic image of the nickel-based superalloy obtained by the heat treatment method of Comparative Example 1.

[0024] Figure 3 is a SEM image of the nickel-based superalloy obtained by the heat treatment method of Example 1.

[0025] Figure 4 is a SEM image of the nickel-based superalloy obtained by the heat treatment method of Comparative Example 1. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] This invention provides a heat treatment method for nickel-based superalloys, the heat treatment method comprising the following steps: Step 1. The nickel-based superalloy is subjected to ultra-high temperature solution treatment, followed by cooling; wherein the holding temperature of the ultra-high temperature solution treatment is 1180~1210 ℃, for example 1180 ℃, 1185 ℃, 1190 ℃, 1195 ℃, 1200 ℃, 1205 ℃, 1210 ℃, etc., and the holding time of the ultra-high temperature solution treatment is 1~4 hours, for example 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc. Step 2. The nickel-based superalloy obtained after Step 1 is subjected to a medium-temperature solution treatment, followed by cooling; wherein the holding temperature of the medium-temperature solution treatment is 1090 ~ 1110 ℃, for example 1090 ℃, 1095 ℃, 1100 ℃, 1105 ℃, 1110 ℃, etc., and the holding time of the medium-temperature solution treatment is 1 ~ 4 hours, for example 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc. Step 3. The nickel-based superalloy obtained after step 2 is subjected to stabilization treatment, followed by cooling; wherein the holding temperature of the stabilization treatment is 950~990 ℃, for example 950 ℃, 955 ℃, 960 ℃, 965 ℃, 970 ℃, 975 ℃, 980 ℃, 985 ℃, 990 ℃, etc., and the holding time of the stabilization treatment is 2~8 hours, for example 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc. Step 4. The nickel-based superalloy treated in Step 3 is subjected to aging treatment, and then cooled to room temperature; wherein the holding temperature of the aging treatment is 835 ~ 855 ℃, for example 835 ℃, 840 ℃, 845 ℃, 850 ℃, 855 ℃, etc., and the holding time of the aging treatment is 8 ~ 24 hours, for example 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, etc.

[0028] Working Mechanism: First, ultra-high temperature treatment is one of the key innovations of the heat treatment method in this embodiment of the invention. The core of ultra-high temperature solution treatment is to use extremely high temperatures to dissolve the coarse, stable γ / γ' eutectic phase and other harmful precipitates (such as topologically close-packed phases) in the alloy back into the γ matrix to the maximum extent, obtaining a highly homogeneous supersaturated solid solution. This lays a pure matrix foundation for subsequent microstructure optimization. Second, medium-temperature solution treatment serves as a buffer between ultra-high temperature solution treatment and subsequent stabilization treatment. Its purpose is to adjust the supersaturation of the γ matrix, prevent excessive internal stress or unnecessary phase transformation caused by direct cooling from ultra-high temperature, and control the grain size to avoid excessive growth. Subsequently, the stabilization treatment is one of the key innovations of the heat treatment method in this embodiment of the invention. At this temperature, the γ' phase will begin to nucleate uniformly and diffusely from the supersaturated matrix. By holding at this subsolid temperature for a long time, a high-density, fine γ' phase "nucleus" distribution can be formed. This "pre-precipitation" process provides a crucial nucleation basis and microstructure preparation for the growth of the γ' phase into a regular cubic morphology in the next aging treatment. Finally, the aging treatment, based on the "nucleus" formed by the stabilization treatment, will further increase the γ' phase. Due to the aforementioned precisely controlled temperature process, the γ' phase tends to grow along the low-energy state... <100> Preferred crystal orientation growth ultimately forms a cubic morphology with uniform size and regular arrangement. This step enables the γ' phase to reach the final required size and volume fraction, achieving the best strengthening effect.

[0029] Compared with the conventional two-step heat treatment process of "solution treatment + aging treatment" and other existing improved processes, the heat treatment method of this invention, through the synergistic effect of a four-step process of "ultra-high temperature solution treatment + medium temperature solution treatment + stabilization treatment + aging treatment", brings the following significant beneficial effects: 1. Ultimate optimization of microstructure: Nearly complete elimination of eutectic phase: Ultra-high temperature solution treatment at 1180~1210 ℃ can almost completely dissolve harmful eutectic phase. The amount of harmful eutectic phase residue in the alloy obtained after heat treatment by the method of this invention is reduced by more than 90% compared with the alloy treated by the conventional two-step heat treatment process of "solution treatment + aging treatment", resulting in an extremely pure γ matrix.

[0030] 2. Perfect cubic transformation of the γ' phase: The key step of "stabilization treatment" at 950 ~ 990 ℃ ensures that the γ' phase nucleates at a high density and forms a cubic morphology with uniform size and regular arrangement after aging treatment, forming a coherent strain field with the γ matrix and maximizing the strengthening effect.

[0031] 3. High organizational stability: After undergoing a multi-stage heat treatment process involving "ultra-high temperature solution treatment + medium temperature solution treatment + stabilization treatment + aging treatment", the alloy microstructure of nickel-based superalloys is in a more stable state. Under long-term high-temperature exposure, the resistance to coarsening and morphological stability of the γ' phase are significantly enhanced.

[0032] 3. Significantly improved tensile properties: Significantly improved high-temperature strength: After being treated by the heat treatment method of the present invention, the yield strength and tensile strength of nickel-based superalloys in the temperature range of 750~850℃ are increased by 5%~20% compared with alloys treated by the conventional two-step heat treatment process of "solution treatment + aging treatment".

[0033] 4. Creep life is significantly extended: After being treated by the heat treatment method of this invention, the clean grain boundaries and regular cubic γ' phase of the nickel-based superalloy greatly hinder dislocation movement and crack propagation, thus extending the creep fracture life of the alloy under typical service conditions by 100% to 300% or even more than that of alloys treated by the conventional two-step heat treatment process of "solution treatment + aging treatment".

[0034] 5. The process is controllable and has good reproducibility: The multi-stage temperature sequence design is scientific, with each step having a clear purpose, forming a synergistic overall process that avoids the risks of single high-temperature treatments, has good microstructure reproducibility, and is suitable for industrial production and quality control.

[0035] Optionally, in step 1, the holding temperature for the ultra-high temperature solution treatment is 1185℃ ~ 1195℃, and the holding time is 2 ~ 4 hours. When the holding temperature or holding time is too low, it is not conducive to reducing the amount of harmful eutectic phase residue in the γ matrix. When the holding temperature or holding time is too high, it is not conducive to the formation of fine γ' phase.

[0036] Optionally, in step 1, the cooling method is to first quench the air at a rate of 50~80℃ / min or force-cool it to below 540℃, such as 540℃, 520℃, 500℃, 450℃, 400℃, 350℃, 300℃, etc., and then air-cool it to room temperature. Rapidly cooling to below 540℃ first and then air-cooling to room temperature is to precipitate the γ' phase and inhibit its growth.

[0037] Optionally, in step 2, the holding temperature for the intermediate-temperature solution treatment is 1095℃ ~ 1105℃, and the holding time is 2 ~ 4 hours. If the holding temperature is too low or the holding time is too short, it is not conducive to preventing excessive internal stress or unnecessary phase transformation in the alloy due to direct cooling from ultra-high temperatures, and it is also not conducive to avoiding appropriate grain size growth. If the holding temperature is too high or the holding time is too long, it is not conducive to the formation of uniform γ' phase precipitation.

[0038] Optionally, in step 2, the cooling method is to first quench the air at a rate of 50~80 ℃ / min or force-cool it to below 540 ℃, such as 540 ℃, 520 ℃, 500 ℃, 450 ℃, 400 ℃, 350 ℃, 300 ℃, etc., and then air-cool it to room temperature. Rapidly cooling to below 540 ℃ first and then air-cooling to room temperature is to achieve complete γ' phase transformation.

[0039] Optionally, in step 3, the holding temperature for the stabilization treatment is 960~970℃, and the holding time for the stabilization treatment is 6~8 hours. If the holding temperature for the stabilization treatment is too low or the holding time is too short, it is not conducive to the perfect cubic formation of the γ' phase, thus hindering the improvement of the strengthening effect. If the holding temperature for the stabilization treatment is too high or the holding time is too long, it is not conducive to cost reduction and efficiency improvement.

[0040] Optionally, in step 3, the cooling method is to first quench the air at a rate of 50~80 ℃ / min or force-cool it to below 540 ℃, such as 540 ℃, 520 ℃, 500 ℃, 450 ℃, 400 ℃, 350 ℃, 300 ℃, etc., and then air-cool it to room temperature. Rapidly cooling to below 540 ℃ first and then air-cooling to room temperature is to achieve complete γ' phase transformation.

[0041] Optionally, in step 4, the holding temperature for the aging treatment is 840~850℃, and the holding time for the aging treatment is 20~24 hours. If the holding temperature for the aging treatment is too low or the holding time is too short, it is not conducive to the γ' phase reaching the final required size and volume fraction, thus hindering the improvement of the strengthening effect. If the holding temperature for the aging treatment is too high or the holding time is too long, it is not conducive to cost reduction and efficiency improvement.

[0042] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0043] Example 1 The nickel-based superalloy workpiece was heated to 1200 °C at a heating rate of 10 °C / min, held for 2 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 1095 °C at a heating rate of 10 °C / min, held for 4 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 950 °C at a heating rate of 10 °C / min, held for 6 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. Finally, the workpiece was heated to 835 °C at a heating rate of 10 °C / min, held for 24 hours, and then air-quenched to 540 °C at an average rate of 50 °C / min, followed by air cooling to room temperature.

[0044] Example 2 The nickel-based superalloy workpiece was heated to 1190 °C at a heating rate of 10 °C / min, held for 2 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 1100 °C at a heating rate of 10 °C / min, held for 4 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 965 °C at a heating rate of 10 °C / min, held for 6 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. Finally, the workpiece was heated to 845 °C at a heating rate of 10 °C / min, held for 24 hours, and then air-quenched to 540 °C at an average rate of 50 °C / min, followed by air cooling to room temperature.

[0045] Example 3 The nickel-based superalloy workpiece was heated to 1210 °C at a heating rate of 5 °C / min, held for 2 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 1100 °C at a heating rate of 10 °C / min, held for 4 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 990 °C at a heating rate of 10 °C / min, held for 6 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. Finally, the workpiece was heated to 855 °C at a heating rate of 10 °C / min, held for 24 hours, and then air-quenched to 540 °C at an average rate of 50 °C / min, followed by air cooling to room temperature.

[0046] Example 4 The nickel-based superalloy workpiece was heated to 1200 °C at a heating rate of 5 °C / min, held for 4 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 1095 °C at a heating rate of 5 °C / min, held for 2 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 980 °C at a heating rate of 5 °C / min, held for 3 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. Finally, the workpiece was heated to 850 °C at a heating rate of 5 °C / min, held for 8 hours, and then air-quenched to 540 °C at an average rate of 50 °C / min, followed by air cooling to room temperature.

[0047] Example 5 The nickel-based superalloy workpiece was heated to 1200 °C at a heating rate of 10 °C / min, held for 4 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 1095 °C at a heating rate of 10 °C / min, held for 4 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. The workpiece was then heated to 980 °C at a heating rate of 10 °C / min, held for 8 hours, and then air-quenched to 540 °C at an average rate of 80 °C / min, followed by air cooling to room temperature. Finally, the workpiece was heated to 850 °C at a heating rate of 10 °C / min, held for 15 hours, and then air-quenched to 540 °C at an average rate of 50 °C / min, followed by air cooling to room temperature.

[0048] Comparative Example 1 The nickel-based superalloy workpiece was heated to 1100℃ at a heating rate of 10℃ / min, held for 2 hours, and then air-quenched to 540℃ at an average rate of 80℃ / min, followed by air cooling to room temperature; then the workpiece was heated to 850℃ at a heating rate of 10℃ / min, held for 24 hours, and then air-quenched to 540℃ at an average rate of 50℃ / min, followed by air cooling to room temperature.

[0049] Performance testing 1. The metallographic structure of the nickel-based superalloys obtained by the heat treatment methods of the above embodiments and comparative examples was tested. The γ / γ' eutectic phase content is shown in Table 1. Figure 1 is a metallographic image of the nickel-based superalloy obtained by the heat treatment method of Example 1, and Figure 2 is a metallographic image of the nickel-based superalloy obtained by the heat treatment method of Comparative Example 1.

[0050] 2. The morphology of the nickel-based superalloys obtained by the heat treatment methods of the above embodiments and comparative examples was tested. The morphology and size of the γ' phase are shown in Table 1. Figure 3 This is a SEM image of the nickel-based superalloy obtained by the heat treatment method in Example 1. Figure 4This is a SEM image of the nickel-based superalloy obtained by the heat treatment method in Comparative Example 1.

[0051] Performance test results analysis Table 1. γ / γ' eutectic phase content, γ' phase morphology, and γ' phase size of nickel-based superalloys obtained by the heat treatment methods of the above embodiments and comparative examples.

[0052] Figure 1 This is a metallographic image of the nickel-based superalloy obtained by the heat treatment method of Example 1. Figure 2 This is a metallographic image of the nickel-based superalloy obtained by the heat treatment method in Comparative Example 1. (The image is obtained through...) Figure 1 and Figure 2 The comparison shows that the γ / γ' eutectic phase content in Example 1 is significantly lower than that in Comparative Example 1.

[0053] Figure 3 This is a SEM image of the nickel-based superalloy obtained by the heat treatment method in Example 1. Figure 4 This is a SEM image of the nickel-based superalloy obtained by the heat treatment method in Comparative Example 1. (The image is obtained through...) Figure 3 and Figure 4 The comparison shows that the morphology and size of the γ' phase are different between the two. Compared with Comparative Example 1, the size of the γ' phase in Example 1 is significantly reduced and the cubic morphology is clearer.

[0054] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A heat treatment method for nickel-based superalloys, characterized in that, The heat treatment method includes the following steps: Step 1. The nickel-based superalloy is subjected to ultra-high temperature solution treatment, followed by gas quenching; wherein the holding temperature of the ultra-high temperature solution treatment is 1180~1210 ℃, and the holding time of the ultra-high temperature solution treatment is 1~4 hours; Step 2. The nickel-based superalloy obtained after step 1 is subjected to medium-temperature solution treatment, followed by cooling; wherein the holding temperature of the medium-temperature solution treatment is 1090~1110 ℃, and the holding time of the medium-temperature solution treatment is 1~4 hours; Step 3. The nickel-based superalloy obtained after step 2 is subjected to stabilization treatment, followed by cooling; wherein the holding temperature of the stabilization treatment is 950 ~ 990 ℃, and the holding time of the stabilization treatment is 2 ~ 8 hours; Step 4. The nickel-based superalloy treated in Step 3 is subjected to aging treatment, followed by cooling; wherein the holding temperature of the aging treatment is 835 ~ 855 ℃, and the holding time of the aging treatment is 8 ~ 24 hours.

2. The heat treatment method according to claim 1, characterized in that, In step 1, the holding temperature of the ultra-high temperature solution treatment is 1185 ~ 1195 ℃, and / or the holding time of the ultra-high temperature solution treatment is 2 ~ 4 hours.

3. The heat treatment method according to claim 1, characterized in that, In step 1, the cooling method is to first quench the air at a rate of 50~80℃ / minute or force-cool it to below 540℃, and then air cool it to room temperature.

4. The heat treatment method according to claim 1, characterized in that, In step 2, the holding temperature of the medium-temperature solution treatment is 1095 ~ 1105 ℃, and / or the holding time of the medium-temperature solution treatment is 2 ~ 4 hours.

5. The heat treatment method according to claim 1, characterized in that, In step 2, the cooling method is to first quench the air or force-cool it to below 540°C at a rate of 50~80°C / minute, and then air cool it to room temperature.

6. The heat treatment method according to claim 1, characterized in that, In step 3, the holding temperature for the stabilization treatment is 960~970 ℃, and / or the holding time for the stabilization treatment is 6~8 hours.

7. The heat treatment method according to claim 1, characterized in that, In step 3, the cooling method is to first quench the air or force-cool it to below 540°C at a rate of 50~80°C / minute, and then air-cool it to room temperature.

8. The heat treatment method according to claim 1, characterized in that, In step 4, the holding temperature for the aging treatment is 840~850℃, and / or the holding time for the aging treatment is 20~24 hours.

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