A heat treatment method for improving the microstructure state and mechanical properties of a high-gamma-prime-content nickel-based cast high-temperature alloy

Abstract

The application provides a heat treatment method for improving the microstructure state and mechanical properties of a high-gamma prime content nickel-based cast high-temperature alloy, and relates to the alloy preparation technical field.The application firstly uses a hot isostatic pressing process to eliminate micro-holes and realize preliminary solid solution effect of the alloy microstructure, but due to the slow cold speed of the hot isostatic pressing process, the size of the precipitated gamma prime phase is coarse and uneven, so the high-temperature solid solution treatment with short-time holding is performed again, that is, the rapid heat treatment process, which can avoid the Kirkendall effect caused by element diffusion under long-time high-temperature treatment to form a large number of solid solution holes again, and the short-time holding can also make the gamma prime phase dissolve to a certain extent again, and then the air cooling rapid cooling can regulate the gamma prime phase morphology and realize the precipitation of the small-size gamma prime phase.The heat treatment method has low cost, is simple and reliable, and can effectively improve the microstructure compactness, fatigue and creep properties of the nickel-based cast high-temperature alloy.

Description

Technical Field

[0001] This invention relates to the field of alloy preparation technology, specifically to a heat treatment method for improving the microstructure and mechanical properties of nickel-based cast superalloys with high γ' content. Background Technology

[0002] The increased turbine inlet temperature in advanced aero-engines leads to a corresponding rise in the high-pressure compressor outlet temperature, and according to the Brayton ideal cycle, this increased outlet temperature effectively improves thermal efficiency. Currently, high-pressure compressor blades widely utilize titanium alloys and wrought superalloys, which, due to their dense structure, exhibit excellent fatigue resistance, but their operating temperature is limited to approximately 650℃, making further increases in operating temperature difficult. Cast superalloys, widely used in turbine blades, primarily employ the γ' phase, which possesses excellent high-temperature performance and exhibits good stability above 700℃, playing a crucial role in coherent strengthening and enhancing the alloy's resistance to deformation at high temperatures. However, for use in compressor blades, cast superalloys require even superior fatigue and creep properties. The non-equilibrium solidification during casting inevitably leads to microporous defects in the interdendritic region, limiting their application in high-pressure compressor blades. Therefore, it is necessary to develop a heat treatment process to eliminate micropores in cast superalloys and improve their microstructure density and mechanical properties.

[0003] Micropores are typically inherent defects in alloys, generally small in size, and can be categorized into casting pores formed during casting and solution pores formed during heat treatment. Cast high-temperature alloys solidify rapidly, and the preferentially solidifying dendrites enclose the residual liquid phase within the dendrites, preventing gas from escaping and hindering effective liquid phase feeding, thus forming micropores. Furthermore, during heat treatment, the diffusion of different elements causes the Kirkendall effect, resulting in solution pores. Micropores act as the source of microcracks during fatigue and creep, severely impacting the creep and fatigue properties of alloys.

[0004] After solution heat treatment, cast nickel-based superalloys exhibit high micropore content due to element diffusion, making it difficult to improve their mechanical properties. Hot isostatic pressing (HIP) can effectively eliminate micropores, but the cooling rate is difficult to control, and the partially precipitated γ' phase grows and coarsens during slow cooling. This results in significant variations in the size and morphology of the γ' precipitate in nickel-based cast superalloys. This is especially true for high γ' phase content nickel-based cast superalloys where γ / γ' phase interface strengthening is dominant, which severely affects the alloy's high-temperature creep and fatigue properties. Summary of the Invention

[0005] The purpose of this invention is to provide a heat treatment method for improving the microstructure and mechanical properties of nickel-based cast superalloys with high γ' content. The heat treatment method of this invention is low in cost, simple and reliable, and can effectively improve the microstructure density, fatigue and creep properties of nickel-based cast superalloys.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a heat treatment method for improving the microstructure and mechanical properties of nickel-based cast superalloys with high γ' content, comprising the following steps:

[0008] The as-cast nickel-based superalloy with high γ' content was subjected to hot isostatic pressing and rapid heat treatment in sequence.

[0009] The volume content of the γ' phase in the as-cast nickel-based cast superalloy with high γ' content is 50-80%.

[0010] The hot isostatic pressing process includes: heating from 20 to 40°C at a heating rate of 5 to 15°C / min to T. sol -30℃~T sol +20℃, the pressure medium is inert gas, the pressure of the inert gas is 140~180MPa, the heat preservation and pressure holding time is 3~10h; the cooling method is furnace cooling.

[0011] The rapid heat treatment includes: a holding temperature of T. sol -10℃~T sol +10℃, total heat preservation time ≤3h; cooling method is air cooling;

[0012] The T sol The solution heat treatment temperature for as-cast nickel-based superalloys with high γ' content.

[0013] Preferably, the as-cast nickel-based superalloy with high γ' content includes as-cast K403 equiaxed superalloy, as-cast K417G equiaxed superalloy, or as-cast IC21 single-crystal superalloy.

[0014] Preferably, the hot isostatic pressing treatment includes: heating from 30°C to T at a heating rate of 10°C / min. sol -10℃~T sol +10℃, the pressure medium is inert gas, the inert gas pressure is 160~180MPa, the heat and pressure holding time is 4~6h; the cooling method is furnace cooling.

[0015] Preferably, the solution heat treatment temperature is between the dissolution temperature of the alloy-strengthened γ' phase and the solidus temperature of the alloy.

[0016] Preferably, the solution heat treatment temperature of the as-cast K403 equiaxed cast high-temperature alloy is 1210℃; the solution heat treatment temperature of the as-cast K417G equiaxed cast high-temperature alloy is 1240℃; and the solution heat treatment temperature of the as-cast IC21 single-crystal cast high-temperature alloy is 1330℃.

[0017] Preferably, the inert gas is high-purity Ar gas.

[0018] Preferably, the rapid heat treatment includes: holding at a temperature of T. sol -10℃~T sol +10℃, total heat preservation time is 1.5~2h; cooling method is air cooling.

[0019] Preferably, the rapid heat treatment includes: first raising the furnace temperature to the holding temperature of the rapid heat treatment, and then placing the alloy sample after hot isostatic pressing into the furnace for rapid heat treatment.

[0020] This invention provides a heat treatment method to improve the microstructure and mechanical properties of nickel-based cast superalloys with high γ' content. The method first uses hot isostatic pressing (HIP) to eliminate micropores and achieve preliminary solution treatment of the alloy microstructure. However, due to the slow cooling rate of HIP, the precipitated γ' phases are large and uneven. Therefore, a short-time high-temperature solution treatment, i.e., a rapid heat treatment process, is performed. This avoids the Kirkendall effect caused by element diffusion under long-term high-temperature treatment, which would lead to the re-formation of numerous solution pores. Simultaneously, the short-time holding also allows for a certain degree of re-dissolution of the γ' phase. Rapid cooling by air can then control the morphology of the γ' phase and achieve the precipitation of smaller γ' phases. Because this technique improves the microstructure density while ensuring the uniformity of the smaller γ' precipitate size and morphology, and increases the γ / γ' phase interface content, it plays a significant role in improving the mechanical properties of nickel-based cast superalloys with high γ' phase content, which is primarily strengthened by the γ / γ' phase interface. It also provides some improvement in the mechanical properties of nickel-based cast superalloys with general γ' phase content.

[0021] The heat treatment process described in this invention, through hot isostatic pressing and rapid heat treatment, not only effectively reduces the content of micropore defects in the microstructure of nickel-based cast superalloys with high γ' content, but also ensures a small γ' precipitate size, effectively improving the fatigue and creep mechanical properties of the alloy. Attached Figure Description

[0022] Figure 1 Metallographic diagram of as-cast K403 equiaxed high-temperature alloy;

[0023] Figure 2 Low-magnification SEM microstructure of as-cast K403 equiaxed high-temperature alloy;

[0024] Figure 3 High-magnification SEM microstructure of as-cast K403 equiaxed high-temperature alloy;

[0025] Figure 4 This is a metallographic diagram of the K403 alloy after solution treatment;

[0026] Figure 5 This is a low-magnification SEM microstructure of K403 alloy after solution treatment;

[0027] Figure 6 This is a high-magnification SEM microstructure of K403 alloy after solution treatment;

[0028] Figure 7 The image shows the metallographic structure of the K403 alloy after heat treatment according to this invention.

[0029] Figure 8 This is a low-magnification SEM microstructure of the K403 alloy after heat treatment according to the present invention;

[0030] Figure 9 This is a high-magnification SEM microstructure image of the K403 alloy after heat treatment according to the present invention;

[0031] Figure 10 A statistical chart showing the porosity of K403 alloy in different states;

[0032] Figure 11 Comparison of creep test curves for K403 alloy;

[0033] Figure 12 Comparison chart of fatigue test results for K403 alloy;

[0034] Figure 13 Metallographic structure diagram of as-cast K417G equiaxed high-temperature alloy;

[0035] Figure 14 Low-magnification SEM microstructure of as-cast K417G equiaxed high-temperature alloy;

[0036] Figure 15 High-magnification SEM microstructure of as-cast K417G equiaxed high-temperature alloy;

[0037] Figure 16 This is a metallographic diagram of the K417G alloy after solution treatment.

[0038] Figure 17 This is a low-magnification SEM microstructure of the K417G alloy after solution treatment;

[0039] Figure 18 This is a high-magnification SEM microstructure of K417G alloy after solution treatment;

[0040] Figure 19 The image shows the metallographic structure of K417G alloy after heat treatment according to this invention.

[0041] Figure 20 This is a low-magnification SEM microstructure of the K417G alloy after heat treatment according to the present invention.

[0042] Figure 21 This is a high-magnification SEM microstructure image of the K417G alloy after heat treatment according to the present invention;

[0043] Figure 22 A statistical chart of the porosity of K417G alloy in different states;

[0044] Figure 23 Comparison of creep test curves for K417G alloy;

[0045] Figure 24 Comparison chart of fatigue test results for K417G alloy;

[0046] Figure 25 The image shows the metallographic structure of the as-cast IC21 single-crystal high-temperature alloy.

[0047] Figure 26 This is a low-magnification SEM microstructure of the as-cast IC21 single-crystal high-temperature alloy.

[0048] Figure 27 High-magnification SEM microstructure of as-cast IC21 single-crystal high-temperature alloy;

[0049] Figure 28 This is a metallographic diagram of the IC21 alloy after solution treatment;

[0050] Figure 29 This is a low-magnification SEM microstructure of the IC21 alloy after solution treatment;

[0051] Figure 30 This is a high-magnification SEM microstructure of the IC21 alloy after solution treatment;

[0052] Figure 31 The image shows the metallographic structure of the IC21 alloy after heat treatment according to this invention.

[0053] Figure 32 This is a low-magnification SEM microstructure of the IC21 alloy after heat treatment according to the present invention;

[0054] Figure 33 This is a high-magnification SEM microstructure image of the IC21 alloy after heat treatment according to the present invention;

[0055] Figure 34 A statistical chart of the porosity of IC21 alloy in different states;

[0056] Figure 35 Comparison of creep test curves for IC21 alloy;

[0057] Figure 36 A comparison chart of fatigue test results for IC21 alloy. Detailed Implementation

[0058] This invention provides a heat treatment method for improving the microstructure and mechanical properties of nickel-based cast superalloys with high γ' content, comprising the following steps:

[0059] The as-cast nickel-based superalloy with high γ' content was subjected to hot isostatic pressing and rapid heat treatment in sequence.

[0060] The volume content of the γ' phase in the as-cast nickel-based cast superalloy with high γ' content is 50-80%.

[0061] The hot isostatic pressing process includes: heating from 20 to 40°C at a heating rate of 5 to 15°C / min to T. sol -30℃~T sol +20℃, the pressure medium is inert gas, the pressure of the inert gas is 140~180MPa, the heat preservation and pressure holding time is 3~10h; the cooling method is furnace cooling.

[0062] The rapid heat treatment includes: a holding temperature of T. sol -10℃~T sol +10℃, total heat preservation time ≤3h; cooling method is air cooling;

[0063] The T sol The solution heat treatment temperature for as-cast nickel-based superalloys with high γ' content.

[0064] In this invention, the content of the γ' phase-forming element (Al) in the as-cast high γ' content nickel-based cast superalloy is preferably >5 wt%. Al is the main γ' phase-forming element. In specific embodiments of this invention, the as-cast high γ' content nickel-based cast superalloy includes as-cast K403 equiaxed cast superalloy, as-cast K417G equiaxed cast superalloy, or as-cast IC21 single-crystal cast superalloy.

[0065] In this invention, the hot isostatic pressing process preferably includes: heating from 30°C to T at a heating rate of 10°C / min. sol -10℃~T sol +10℃, the pressure medium is inert gas, the pressure of the inert gas is 160~180MPa, the heat preservation and pressure holding time is 4~6h; the cooling method is furnace cooling.

[0066] In this invention, the T solThe temperature for solution heat treatment of as-cast nickel-based superalloys with high γ' content is expressed in °C. In this invention, the solution heat treatment temperature is preferably between the dissolution temperature of the alloy-strengthening γ' phase and the solidus temperature of the alloy.

[0067] In a specific embodiment of the present invention, the T of the as-cast K403 equiaxed cast high-temperature alloy sol The temperature is 1210℃; the T value of the as-cast K417G equiaxed cast high-temperature alloy is... sol The temperature is 1240℃; the T value of the as-cast IC21 single-crystal cast high-temperature alloy is... sol It is 1330℃.

[0068] In this invention, the inert gas is preferably a high-purity inert gas, and more preferably high-purity Ar gas.

[0069] In this invention, the rapid heat treatment preferably includes: a holding temperature of T. sol -10℃~T sol +10℃, total heat preservation time is 1.5~2h; cooling method is air cooling.

[0070] In this invention, the furnace temperature is first raised to the holding temperature of the rapid heat treatment, and then the alloy sample after hot isostatic pressing is placed in the furnace for rapid heat treatment.

[0071] In this invention, the volume content of the γ' phase in the as-cast nickel-based high-γ' content nickel-based superalloy after hot isostatic pressing and rapid heat treatment is preferably 50-80%.

[0072] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0073] Example 1

[0074] The as-cast K403 equiaxed high-temperature alloy was subjected to hot isostatic pressing at 1230℃. Specifically, the medium was high-purity Ar gas, the temperature was increased from 30℃ to 1230℃ at a heating rate of 10℃ / min, the pressure was increased to 160MPa, and the temperature and pressure were held at 1230℃ and 160MPa for 4 hours before being cooled to room temperature. The cooling method was furnace cooling.

[0075] The alloy samples after hot isostatic pressing were subjected to rapid heat treatment, specifically: the furnace temperature was raised to 1210℃, the alloy samples were placed into the furnace at the temperature, held at the temperature for 1.5 hours, and then cooled by air cooling.

[0076] Test Example 1

[0077] The metallographic and microstructure of as-cast K403 equiaxed superalloy, such as Figures 1-3 As shown, severe dendrite segregation can be observed, with obvious dendrite morphology within the grains, and casting voids can be observed both within the grains and at the grain boundaries (see...). Figures 1-2 The area percentage of pores is 0.109%, and the γ' phase morphology of the dendrite trunks varies considerably, with an average size of 178 nm (see...). Figure 3 The γ' phase has a moderate volume content of approximately 51%.

[0078] The metallographic and microstructures of as-cast K403 equiaxed superalloy after solution heat treatment (holding temperature 1210℃, holding time 4h, air cooling) are shown in the figure. Figures 4-6 After solution heat treatment, dendrite segregation is reduced (see...). Figure 4 However, the number of pores within the tissue increased, their shape became more circular, and collapsed pore morphology appeared. The area fraction of the pores was 0.202% (see...). Figure 4 and 5 After solution treatment, the γ' phase is fine and uniform in morphology, with a basically concave cubic shape and a size of 93 nm (see...). Figure 6 ).

[0079] Metallographic observation was performed on the sample prepared by the heat treatment process provided in this invention in Example 1 (see...). Figure 7 ) and microscopic tissue observation (see Figure 8 and 9 The heat treatment process provided in this invention was applied to the metal materials, and a 760℃ rotational fatigue test (according to GB / T 4337-2015, Rotational Bending Method for Fatigue Testing of Metallic Materials) and a 760℃ / 650MPa creep test (according to GB / T 2039-2012, Uniaxial Tensile Creep Test Method for Metallic Materials) were performed. Microstructural observation results showed that the microstructure after the heat treatment process provided in this invention was relatively uniform, and the dendritic structure showed no obvious characteristics under a light microscope, indicating a good solid solution effect (see...). Figure 7 Furthermore, the hole closure was relatively complete, and the remaining unclosed hole area decreased to 0.0406% (see...). Figure 7 and 8 Simultaneously, the precipitated γ' phase is relatively fine, basically cubic, with a size of 118 nm (see...). Figure 9 ).

[0080] After the heat treatment process provided by this invention, the micropore content of the alloy structure is effectively reduced (see...). Figure 10 Furthermore, both creep life and fatigue limit are improved compared to those after solution heat treatment (see...). Figure 11 and Figure 12The creep life at 760℃ / 650MPa was increased by about 70 hours, and the fatigue limit at 760℃ was increased by about 30MPa. Figure 10 In this context, "cast state" refers to the cast K403 equiaxed cast high-temperature alloy; "solution state" refers to the sample obtained after solution heat treatment of the cast K403 equiaxed cast high-temperature alloy; and "optimized heat-treated state" refers to the sample prepared in Example 1 using the heat treatment process provided by this invention. Figures 11-12 In this context, "optimized heat treatment" refers to the sample prepared by the heat treatment process provided by the present invention in Example 1; "solution heat treatment" refers to the sample of as-cast K403 equiaxed cast high-temperature alloy after solution heat treatment.

[0081] Example 2

[0082] The as-cast K417G equiaxed high-temperature alloy was subjected to hot isostatic pressing at 1240℃. Specifically, the medium was high-purity Ar gas, the temperature was increased from 30℃ to 1240℃ at a heating rate of 10℃ / min, the pressure was increased to 160MPa, and the temperature and pressure were held at 1240℃ and 160MPa for 4 hours before being cooled to room temperature. The cooling method was furnace cooling.

[0083] The alloy samples after hot isostatic pressing were subjected to rapid heat treatment, specifically: the furnace temperature was raised to 1230℃, the alloy samples were placed into the furnace at the temperature, held at the temperature for 1.5 hours, and then cooled by air cooling.

[0084] Test Example 2

[0085] The metallographic and microstructure of as-cast K417G equiaxed superalloy are as follows: Figures 13-15 As shown, the cast dendrite morphology is obvious, with a distribution of pores of varying sizes, and the area percentage of pores is 0.149% (see...). Figure 13 and 14 Meanwhile, the γ' phase exhibits a near-cubic structure with interconnected γ' phases. The γ' phases vary in size, with an average size of 316 nm, and the volume content of the γ' phase is moderate, approximately 54% (see...). Figure 15 ).

[0086] The metallographic and microstructures of the as-cast equiaxed superalloy K417G after solution heat treatment (holding temperature 1240℃, holding time 4h, air cooling) are shown in the figure. Figures 16-18 After solution heat treatment, the dendritic structure basically disappeared, the number of pores increased significantly, and the pore area fraction increased to 0.268% (see...). Figure 16 and 17 After solution treatment, the γ' phase is cubic in shape, uniform in morphology and size distribution, and has a size of 115 nm (see...). Figure 18 ).

[0087] Metallographic observation was performed on the sample prepared by the heat treatment process provided by the present invention in Example 2 (see...). Figure 19 ) and microscopic tissue observation (see Figure 20 and 21 The heat treatment process provided by this invention was applied to the dendritic structure, and a bending fatigue test was conducted at 760℃ (according to GB / T 4337-2015, Rotary Bending Method for Fatigue Testing of Metallic Materials) and a creep test at 760℃ / 650MPa (according to GB / T 2039-2012, Uniaxial Tensile Creep Test Method for Metallic Materials). Microstructural observation results showed that the heat treatment process provided by this invention effectively reduced the dendritic structure and achieved good solid solution treatment, significantly eliminated internal pores, and completely filled the pores, reducing the pore area ratio to 0.0305% (see [reference needed]). Figure 19 and 20 The precipitated γ' phase is basically cubic in shape and relatively uniformly distributed, with a significantly reduced size of 128 nm (see...). Figure 21 ).

[0088] After the heat treatment process provided by this invention, the micropore content of the alloy structure is effectively reduced (see...). Figure 22 Furthermore, both creep life and fatigue strength are improved compared to those after solution heat treatment (see...). Figure 23 and Figure 24 The creep life at 760℃ / 650MPa was increased by about 30 hours, and the fatigue limit at 760℃ was increased by about 20MPa. Figure 22 In this context, "cast state" refers to the cast K417G equiaxed cast high-temperature alloy; "solution state" refers to the sample obtained after solution heat treatment of the cast K417G equiaxed cast high-temperature alloy; and "optimized heat-treated state" refers to the sample prepared by the heat treatment process provided by this invention in Example 2. Figures 23-24 In this context, "optimized heat treatment" refers to the sample prepared by the heat treatment process provided by the present invention in Example 2; "solution heat treatment" refers to the sample of the as-cast K417G equiaxed cast high-temperature alloy after solution heat treatment.

[0089] Example 3

[0090] The as-cast IC21 single crystal high-temperature alloy was subjected to hot isostatic pressing at 1330℃. Specifically, the medium was high-purity Ar gas, the temperature was increased from 30℃ to 1330℃ at a heating rate of 10℃ / min, the pressure was increased to 180MPa, and the temperature and pressure were held at 1330℃ and 180MPa for 4 hours before being cooled to room temperature. The cooling method was furnace cooling.

[0091] The alloy sample after hot isostatic pressing was subjected to rapid heat treatment, specifically: the furnace temperature was raised to 1325℃, the alloy sample was placed into the furnace at the temperature, held at the temperature for 2 hours, and then cooled by air cooling.

[0092] Test Example 3

[0093] The metallographic and microstructure of as-cast IC21 single-crystal high-temperature alloys are as follows: Figures 25-27 As shown, the as-cast dendrite morphology is obvious, and there are a large number of pores inside the structure, with the pore area percentage being 0.184% (see...). Figure 25 and 26 Meanwhile, the γ' phase structure exhibits significant size variations and interconnected γ' phase morphology, with an average size of 1000 nm. The average volume content of the γ' phase is relatively high, approximately 68% (see...). Figure 27 ).

[0094] The metallographic and microstructures of the as-cast IC21 single-crystal high-temperature alloy after solution heat treatment (holding temperature 1330℃, holding time 6h, air cooling) are shown in the figure. Figures 28-30 After solution heat treatment, the dendritic structure completely disappeared, but the number of pores increased significantly, and the pore area fraction increased to 0.305% (see...). Figure 28 and 29 After solution treatment, the γ' phase is embedded cubic in shape, uniformly distributed, and has a size of 450 nm (see...). Figure 30 ).

[0095] Metallographic observation was performed on the sample prepared by the heat treatment process provided by the present invention in Example 3 (see...). Figure 31 ) and microscopic tissue observation (see Figure 32 and 33 The material underwent a bending fatigue test at 800℃ (according to GB / T 4337-2015, Rotary Bending Method for Fatigue Testing of Metallic Materials) and a creep test at 800℃ / 500MPa (according to GB / T 2039-2012, Uniaxial Tensile Creep Test Method for Metallic Materials). Microstructural observation results showed that the heat treatment process provided by this invention effectively eliminated solid solution in the dendrite structure, significantly reduced internal porosity, and decreased the porosity area to 0.0258% (see...). Figure 31 and 32 The precipitated γ' phase is basically cubic in structure and relatively uniformly distributed, with a significantly reduced size of 550 nm (see...). Figure 33 ).

[0096] After the heat treatment process provided by this invention, the micropore content of the alloy structure is effectively reduced (see...). Figure 34 Furthermore, both creep life and fatigue strength are improved compared to those after solution heat treatment (see...). Figure 35 and Figure 36 The creep life at 800℃ / 500MPa was increased by about 370 hours, and the fatigue limit at 800℃ was increased by about 30MPa. Figure 34In this context, "cast state" refers to the cast IC21 single crystal cast high-temperature alloy; "solution state" refers to the sample obtained after solution heat treatment of the cast IC21 single crystal cast high-temperature alloy; and "optimized heat treatment state" refers to the sample prepared by the heat treatment process provided in this invention in Example 3. Figures 35-36 In this context, "optimized heat treatment" refers to the sample prepared by the heat treatment process provided by the present invention in Example 3; "solution heat treatment" refers to the sample of the as-cast IC21 single crystal cast high-temperature alloy after solution heat treatment.

[0097] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A heat treatment method for improving the microstructure and mechanical properties of nickel-based cast superalloys with high γ' content, comprising the following steps: The as-cast nickel-based superalloy with high γ' content was subjected to hot isostatic pressing and rapid heat treatment in sequence. The volume content of the γ' phase in the as-cast nickel-based superalloy with high γ' content is 50-80%. The hot isostatic pressing treatment is: heating from 20-40℃ to T sol -30℃ to T sol +20℃ at a heating rate of 5-15℃ / min, the pressure medium is inert gas, the pressure of the inert gas is 140-180MPa, the holding time is 3-10h, and the cooling mode is furnace cooling. The rapid heat treatment is as follows: the holding temperature is T. sol -10℃~T sol +10℃, total heat preservation time ≤3h; cooling method is air cooling; The T sol The solution heat treatment temperature for as-cast nickel-based superalloys with high γ' content; The as-cast nickel-based superalloy with high γ' content is as-cast K403 equiaxed superalloy, as-cast K417G equiaxed superalloy, or as-cast IC21 single crystal superalloy. The solution heat treatment temperature of the as-cast K403 equiaxed cast high-temperature alloy is 1210℃; the solution heat treatment temperature of the as-cast K417G equiaxed cast high-temperature alloy is 1240℃; and the solution heat treatment temperature of the as-cast IC21 single-crystal cast high-temperature alloy is 1330℃.

2. The heat treatment method according to claim 1, characterized in that, The hot isostatic pressing process includes: heating from 30°C to T at a heating rate of 10°C / min. sol -10℃~T sol +10℃, the pressure medium is inert gas, the inert gas pressure is 160~180MPa, the heat and pressure holding time is 4~6h; the cooling method is furnace cooling.

3. The heat treatment method according to claim 1, characterized in that, The solution heat treatment temperature is between the dissolution temperature of the alloy-strengthened γ' phase and the solidus temperature of the alloy.

4. The heat treatment method according to claim 1, characterized in that, The inert gas is high-purity Ar gas.

5. The heat treatment method according to claim 1, characterized in that, The rapid heat treatment includes: a holding temperature of T. sol -10℃~T sol +10℃, total heat preservation time is 1.5~2h; cooling method is air cooling.

6. The heat treatment method according to claim 1 or 5, characterized in that, The rapid heat treatment includes: first raising the furnace temperature to the holding temperature of the rapid heat treatment, and then placing the alloy sample after hot isostatic pressing into the furnace for rapid heat treatment.

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