A heat treatment process to improve the comprehensive mechanical properties of GH4169 alloy

Abstract

This invention provides a heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy, belonging to the technical field of high-temperature alloy heat treatment. The heat treatment process includes: S1, solution treatment: GH4169 forgings are solution treated to obtain solution-treated GH4169 forgings; S2, controlled cooling after solution treatment: the solution-treated GH4169 forgings from S1 are cooled at a specific rate to a stable microstructure temperature and held at that temperature, then removed and air-cooled to room temperature, resulting in GH4169 forgings with a precipitate distribution that tends towards a stable state; S3, low-temperature aging treatment: the GH4169 forgings from S2 with a precipitate distribution that tends towards a stable state are subjected to low-temperature aging treatment, then removed and air-cooled to room temperature, resulting in GH4169 forgings with high comprehensive mechanical properties. This invention's method is simple, easy to operate, environmentally friendly, low-cost, and highly efficient, facilitating large-scale industrial production and application.

Description

Technical Field

[0001] This invention relates to the technical field of high-temperature alloy heat treatment, specifically to a heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy. Background Technology

[0002] GH4169 alloy is a classic precipitation-strengthened nickel-based superalloy, which mainly relies on the main strengthening phase γ′′ and the auxiliary strengthening phase γ′. The alloy has excellent microstructure stability and mechanical properties below 650℃, and it is still the most widely used nickel-based superalloy material in aero-engines.

[0003] As a long-established high-temperature alloy, GH4169 is still the subject of much research to optimize its microstructure and properties, and its mechanical properties are constantly being improved. However, it has technical defects such as the inability to synergistically improve strength and plasticity, and the conflict between preparation cost and product quality.

[0004] For example, studies have shown that increasing the aging temperature to 900℃ can improve the plasticity of GH4169 by 80%, but reduce the yield strength by 34% (Influence of high temperature aging on the properties of GH4169 nickel-based superalloy [J]. Journal of Materials Research, 2026, 40(02): 143-151.).

[0005] Studies have shown that shortening the aging process from two stages to a single stage of aging at 720℃×16h can simplify the process, but the yield strength is 100MPa lower than that of two-stage aging (Influence of aging process on the microstructure and mechanical properties of Inconel 718 alloy [J]. Journal of Electron Microscopy, 2023, 42(05):565-573.).

[0006] Studies have shown that raising the solution temperature to above 1000℃ promotes the dissolution of more δ phases, thereby increasing the content of the strengthening phase γ′′ / γ′. However, the effect of increasing the solution temperature leading to increased grain size and reduced strength is greater than the strengthening effect brought about by the increase of the strengthening phase (Influence of solution temperature on the microstructure and mechanical properties of GH4169 high-temperature alloy [J]. Foundry Technology, 2025, 46(08): 809-815.).

[0007] At the patent technology level, existing technologies have also proposed many research innovations.

[0008] For example, Chinese patent CN117488226A discloses a method to increase the cooling rate after solution treatment to suppress the precipitation of the δ phase, thereby increasing the precipitation of the γ′′ / γ′ phase in the subsequent aging stage. However, the amount of δ phase precipitation in the original air cooling stage is extremely small, or even negligible, so the improvement effect of this method is very limited.

[0009] Chinese patent CN110747417A discloses increasing the temperature and extending the aging time to promote an increase in precipitation. However, increasing the aging temperature will accelerate the coarsening of the γ′′ / γ′ phase. For the standard aging process, which has already reached the precipitation equilibrium of the γ′′ / γ′ phase, extending the aging time will not have a significant effect in practice.

[0010] Chinese patent CN111270178A discloses a method of increasing the aging temperature to shorten the aging time in order to improve production efficiency, but this does not improve the alloy properties and increases the risk of severe coarsening of the γ′′ / γ′ phase.

[0011] Chinese patent CN112795857A discloses a method to improve strength by promoting grain refinement through cold rolling, but it is limited to plates and cannot be applied to high-temperature alloys in all states.

[0012] Chinese patent CN115786831A discloses an aging treatment before solution treatment to stabilize the microstructure of forgings, but this method has virtually no effect on the regulation of the γ′′ / γ′ phase.

[0013] In addition, there are existing technologies for improving the mechanical properties of GH4169 alloy by targeting its composition. For example, Chinese patent CN119753544A sets different solution temperatures to dissolve the δ phase and increase the γ′′ / γ′ phase content for GH4169 forgings produced domestically and internationally, based on the different Nb contents. Another Chinese patent CN117778815A proposes controlling the Nb, Ti, Al, and Co elemental compositions to improve the creep performance of GH4169 alloy. Yet another Chinese patent CN120666205A proposes adding rare earth oxides to improve the mechanical properties of GH4169 alloy. However, these technologies all have some issues with product quality, product performance, and cost control, making it difficult to effectively obtain high-strength and ductile products and efficient, low-cost preparation methods.

[0014] As can be seen from the above literature and patent research, due to the mature heat treatment process of GH4169 alloy, the optimization of heat treatment for GH4169 can only be limited to improving a single aspect such as strength or plasticity, or the performance improvement is small.

[0015] Therefore, how to fully utilize and improve the heat treatment process of GH4169 to simultaneously enhance both strength and plasticity is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0016] To address the technical problems in existing technologies where improving the strength and ductility of GH4169 alloys through alloy composition design and / or preparation method modifications fails to achieve a synergistic improvement, resulting in a conflict between preparation costs and product quality, limited synergistic improvement, and a mismatch between the achieved performance and production costs and efficiency, this invention provides a heat treatment process for improving the comprehensive mechanical properties of GH4169 alloys. The technical solution is as follows:

[0017] A heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy, comprising the following preparation steps:

[0018] S1. Solution treatment: The GH4169 forging is subjected to solution treatment to obtain the solution-treated GH4169 forging.

[0019] S2. Controlled cooling treatment after solution treatment: The solution-treated GH4169 forging in S1 is cooled to the microstructure stability temperature at a specific rate, and then taken out and air-cooled to room temperature to obtain a GH4169 forging with a precipitate distribution that tends to be stable.

[0020] S3. Low-temperature aging treatment: The GH4169 forging with the precipitate distribution of S2 tending to be in a stable state is subjected to low-temperature aging treatment, and then taken out and air-cooled to room temperature to obtain the GH4169 forging finished product with high comprehensive mechanical properties.

[0021] Optionally, the GH4169 forging in S1 is obtained by: obtaining an ingot through three-stage smelting, homogenizing heat treatment, forging a blank, forging ratio ≥3, and finally hot forging.

[0022] Optionally, the triple smelting process is vacuum induction melting (VIM) + electroslag remelting (ESR) + vacuum arc remelting (VAR).

[0023] Optionally, in S1, the solution treatment involves heating the GH4169 forging in the furnace at 220-320℃ / h to 700-800℃ and holding it for 10-30 min; then heating it again at 150-250℃ / h to the solution temperature of 980±10℃ and holding it for 60±10 min.

[0024] Optionally, during the S1 solution treatment, the strengthening phase γ′′ / γ′ phase completely dissolves, leaving 7.2±0.5% undissolved δ phase inside the alloy. This portion of δ phase can prevent the alloy from exhibiting notch sensitivity and improve its high-temperature creep resistance.

[0025] Optionally, the cooling rate of the solution-treated GH4169 forging in S2 is 8-12℃ / min, the microstructure stabilization temperature is 400-450℃, the holding temperature is 10-20min, and then it is taken out and air-cooled to room temperature.

[0026] Optionally, during the cooling to the microstructure stabilization temperature in S2, the γ′′ / γ′ phase inside the alloy will precipitate, which can effectively control the quantity and size of the γ′′ / γ′ phase precipitates, so that a large number of fine-sized γ′′ / γ′ phases are precipitated, with a content of 40%-47% (area fraction) and an average size of 18.0-20.0 nm.

[0027] Optionally, the S3 low-temperature aging treatment involves heating the GH4169 alloy in the furnace at 220-320℃ / h to 500-550℃ and holding for 10-30 min; then heating at 150-220℃ / h to the aging temperature of 620±10℃, with an aging time of 6-10 h.

[0028] Optionally, the GH4169 forgings with high comprehensive mechanical properties in S3 have a γ′′ / γ′ phase content of 61% (area fraction) and an average size of 21.3-22.7 nm.

[0029] Optionally, compared with the GH4169 forgings of S1, the S3 high comprehensive mechanical properties GH4169 forgings improve the room temperature and 540℃ high temperature yield strength by 4.5%-7.1% and 4.6%-6.2%, respectively; improve the room temperature and high temperature tensile strength by 2.1%-5.0% and 3.2%-6.0%, respectively; improve the room temperature and high temperature elongation by 24.0%-25.8% and 25.0%-27.6%, respectively; and improve the room temperature and high temperature reduction of area by 14.8%-22.2% and 12.9%-16.1%, respectively.

[0030] Optionally, the room temperature properties of GH4169 forgings with high comprehensive mechanical properties in S3 are as follows: yield strength 1167-1204 MPa, tensile strength 1375-1414 MPa, yield ratio 0.843-0.851, elongation after fracture 20.2%-20.8%, and reduction of area 31%-33%; the high temperature properties at 540℃ are as follows: yield strength 966-989 MPa, tensile strength 1157-1188 MPa, yield ratio 0.832-0.837, elongation after fracture 26.1%-27.4%, and reduction of area 35%-36%.

[0031] Technical principle of the invention:

[0032] This invention involves solution treatment and heat preservation of GH4169 alloy; followed by cooling the alloy at a specified rate to its microstructure stabilization temperature, during which a large number of fine γ′′ / γ′ phases precipitate; then performing a low-temperature aging treatment, where the γ′′ / γ′ phases maintain their fine size and additionally precipitate even finer γ′′ / γ′ phases, ultimately improving both the alloy's strength and plasticity. This invention promotes the pre-precipitation of fine-sized γ′′ / γ′ phases by controlling the cooling rate of the workpiece after solution treatment, fully utilizing the previously overlooked value of cooling processes. By matching this with a low-temperature aging regime, the size of the strengthening phases in the alloy is maintained at a finer level than in standard heat treatment processes, further enhancing the overall mechanical properties of the alloy. This method is simple and easy to operate, further raising the upper limit of the mechanical properties of the classic GH4169 high-temperature alloy. It is environmentally friendly, low-cost, has a short process, and is highly efficient.

[0033] The above technical solution has at least the following advantages compared with the existing technology:

[0034] The above-mentioned solution proposes a heat treatment process to improve the comprehensive mechanical properties of GH4169 alloy. This process can solve the technical problems in the prior art, such as the inability to synergistically improve the strength and plasticity of GH4169 through alloy composition design and / or preparation method improvement, the conflict between preparation cost and product quality, the small synergistic improvement, and the mismatch between the obtained performance and production cost and production efficiency.

[0035] The solution treatment of this invention involves heating the GH4169 forging in the furnace at 220-320℃ / h to 700-800℃ and holding for 10-30 min; then heating again at 150-250℃ / h to the solution temperature of 980±10℃ and holding for 60±10 min. During this period, all the strengthening phases γ′′ / γ′ dissolve, leaving approximately 7.2% undissolved δ phase inside the alloy. This portion of δ phase can prevent the alloy from exhibiting notch sensitivity and improve its high-temperature creep resistance.

[0036] This invention employs controlled cooling, specifically cooling to 400-500℃ at a rate of 8-12℃ / min. During this process, the γ′′ / γ′ phase precipitates within the alloy. Controlling the cooling rate during this phase is crucial. Excessive cooling leads to insufficient or no precipitation of the γ′′ / γ′ phase, resulting in an alloy matrix with insufficient γ′′ / γ′ phase precipitation even after the subsequent low-temperature aging process in step three. Conversely, excessive cooling leads to excessive γ′′ / γ′ phase precipitation and significant coarsening, resulting in an irreversible strengthening effect regardless of subsequent aging. Experimental verification shows that cooling at the rate specified in step two ensures the precipitation of a large amount of fine-sized γ′′ / γ′ phase, with a content of 40-47% (area fraction) and an average size of 18.0-20.0 nm.

[0037] This invention employs low-temperature aging treatment, omitting the standard 720℃ high-temperature aging process. This effectively avoids the significant coarsening of the γ′′ / γ′ phase precipitated during the cooling rate of 8-12℃ / min after solution treatment at 720℃. Instead, only a 620℃ low-temperature aging treatment is performed. The already precipitated γ′′ / γ′ phase exhibits minimal coarsening under low-temperature aging, and even finer γ′′ / γ′ phases can be precipitated, thereby enhancing the strengthening effect. Simultaneously, the original two-stage aging process is shortened, achieving cost reduction and efficiency improvement.

[0038] In summary, compared with traditional methods for improving the comprehensive mechanical properties of GH4169 alloy, the method of the present invention, through solution treatment + controlled cooling + low-temperature aging treatment, can synergistically improve the room temperature strength and plasticity of the alloy, thereby further enhancing the comprehensive mechanical properties of the alloy. The method is simple in process, easy to operate, environmentally friendly, low in cost, and highly efficient, which is conducive to large-scale industrial production and application. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a microstructure diagram of the γ′′ / γ′ phase distribution in the alloy obtained after a heat treatment process to improve the comprehensive mechanical properties of GH4169 alloy according to Embodiment 1 of the present invention.

[0041] Figure 2 This is a microstructure diagram of the γ′′ / γ′ phase distribution in the alloy obtained after a heat treatment process to improve the comprehensive mechanical properties of GH4169 alloy according to Embodiment 2 of the present invention.

[0042] Figure 3 This is a microstructure diagram of the γ′′ / γ′ phase distribution in the alloy obtained after a heat treatment process to improve the comprehensive mechanical properties of GH4169 alloy according to Embodiment 3 of the present invention.

[0043] Figure 4 This is a microstructure diagram of the γ′′ / γ′ phase distribution in the alloy obtained by the heat treatment process of Comparative Example 1 of this invention. Detailed Implementation

[0044] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0045] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0046] In the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, their intended meanings are consistent.

[0047] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0048] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0049] A heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy, comprising the following preparation steps:

[0050] S1. Solution treatment: The GH4169 forging is subjected to solution treatment to obtain the solution-treated GH4169 forging.

[0051] S2. Controlled cooling treatment after solution treatment: The solution-treated GH4169 forging in S1 is cooled to the microstructure stability temperature at a specific rate and held at that temperature. Then it is taken out and air-cooled to room temperature to obtain a GH4169 forging with a precipitate distribution that tends to be stable.

[0052] S3. Low-temperature aging treatment: The GH4169 forging with the precipitate distribution of S2 tending to be in a stable state is subjected to low-temperature aging treatment, and then taken out and air-cooled to room temperature to obtain the GH4169 forging finished product with high comprehensive mechanical properties.

[0053] Specifically, the GH4169 forgings in S1 are obtained by three-stage smelting to obtain ingots, followed by homogenization heat treatment and forging blanks with a forging ratio ≥3, and finally hot forging.

[0054] Specifically, the triple smelting process consists of vacuum induction melting (VIM) + electroslag remelting (ESR) + vacuum arc remelting (VAR).

[0055] Specifically, in S1, the solution treatment of GH4169 forgings is carried out by heating the furnace at 220-320℃ / h to 700-800℃ and holding for 10-30min; then the temperature is further increased at 150-250℃ / h to the solution temperature of 980±10℃ and held for 60±10min.

[0056] In particular, during the S1 solution treatment, the strengthening phase γ′′ / γ′ phase completely dissolves, leaving 7.2±0.5% undissolved δ phase inside the alloy. This portion of δ phase can prevent the alloy from exhibiting notch sensitivity and improve its high-temperature creep resistance.

[0057] Specifically, the cooling rate of the solution-treated GH4169 forging in S2 is 8-12℃ / min, the microstructure stabilization temperature is 400-450℃, the holding time is 10-20min, and then it is taken out and air-cooled to room temperature.

[0058] In particular, during the cooling to the microstructure stabilization temperature in S2, the γ′′ / γ′ phase inside the alloy will precipitate. The quantity and size of the γ′′ / γ′ phase precipitates can be effectively controlled to ensure that a large number of fine-sized γ′′ / γ′ phases are precipitated, with a content of 40-47% (area fraction) and an average size of 18.0-20.0 nm.

[0059] Specifically, the S3 low-temperature aging treatment involves heating the GH4169 alloy in the furnace at 220-320℃ / h to 500-550℃ and holding it for 10-30 minutes; then heating it at 150-220℃ / h to the aging temperature of 620±10℃, aging for 6-10 hours, and finally air-cooling it to room temperature.

[0060] Specifically, the GH4169 forgings with high comprehensive mechanical properties in S3 have a γ′′ / γ′ phase content of 61% (area fraction) and an average size of 21.3-22.7 nm.

[0061] Specifically, compared to the GH4169 forgings in S1, the S3 high-comprehensive mechanical properties of the finished GH4169 forgings show improvements in room temperature and 540℃ high-temperature yield strength of 4.5%-7.1% and 4.6%-6.2%, respectively; room temperature and high-temperature tensile strength of 2.1%-5.0% and 3.2%-6.0%, respectively; room temperature and high-temperature elongation of 24.0%-25.8% and 25.0%-27.6%, respectively; and room temperature and high-temperature reduction of area of ​​14.8%-22.2% and 12.9%-16.1%, respectively.

[0062] Specifically, the room temperature properties of GH4169 forgings with high comprehensive mechanical properties in S3 are as follows: yield strength 1167-1204 MPa, tensile strength 1375-1414 MPa, yield-to-tensile ratio 0.843-0.851, elongation after fracture 20.2%-20.8%, and reduction of area 31%-33%; the high temperature properties at 540℃ are as follows: yield strength 966-989 MPa, tensile strength 1157-1188 MPa, yield-to-tensile ratio 0.832-0.837, elongation after fracture 26.1%-27.4%, and reduction of area 35%-36%.

[0063] Example 1

[0064] This embodiment describes a heat treatment process for improving the overall mechanical properties of GH4169 alloy. The heat treatment process for improving the overall mechanical properties of GH4169 alloy includes the following preparation steps:

[0065] S1. Solution treatment: The GH4169 forgings are obtained by three-stage smelting to obtain ingots, followed by homogenization heat treatment and forging blanks with a forging ratio of 3, and finally hot forging. The GH4169 forgings are subjected to solution treatment. The GH4169 forgings are heated to 750℃ in the furnace at 250℃ / h and held for 20min. Then, the temperature is raised to the solution temperature of 980℃ at 200℃ / h and held for 60min to obtain the solution-treated GH4169 forgings.

[0066] During the solution treatment, the strengthening phase γ′′ / γ′ phase completely dissolves, leaving about 7.2% undissolved δ phase inside the alloy. This part of the δ phase can prevent the alloy from being notch sensitive and improve its high-temperature creep resistance.

[0067] S2. Controlled cooling treatment after solution treatment: The solution-treated GH4169 forging in S1 is cooled to the microstructure stability temperature of 450℃ at a rate of 10℃ / min and held for 15min. Then it is taken out and air-cooled to room temperature to obtain a GH4169 forging with a precipitate distribution that tends to be stable.

[0068] During the cooling process to the microstructure stabilization temperature, the γ′′ / γ′ phase inside the alloy will precipitate. The quantity and size of the γ′′ / γ′ phase precipitates can be controlled, resulting in the precipitation of a large number of fine-sized γ′′ / γ′ phases with a content of 45% (area fraction) and an average size of 19.0 nm.

[0069] S3. Low-temperature aging treatment: The GH4169 forgings in S2 with the precipitate distribution tending to be stable are subjected to low-temperature aging treatment. The workpiece is heated to 520℃ in the furnace at 250℃ / h and held for 20min; then heated to the low-temperature aging treatment temperature of 620℃ at 180℃ / h and aged for 8h; then taken out and air-cooled to room temperature to obtain the GH4169 forging finished product with high comprehensive mechanical properties.

[0070] like Figure 1 As shown, the GH4169 forging with high comprehensive mechanical properties prepared in this embodiment has a γ′′ / γ′ phase content of 61% (area fraction) and an average size of 22.1 nm.

[0071] The room temperature properties of the GH4169 forging with high comprehensive mechanical properties prepared in this embodiment are as follows: yield strength 1175 MPa, tensile strength 1394 MPa, yield-to-tensile ratio 0.843, elongation after fracture 20.2%, reduction of area 31%, and strength-ductility product 28.159 GPa; the high temperature properties at 540℃ are as follows: yield strength 974 MPa, tensile strength 1164 MPa, yield-to-tensile ratio 0.837, elongation after fracture 26.1%, reduction of area 35%, and strength-ductility product 30.380 GPa.

[0072] Example 2

[0073] This embodiment describes a heat treatment process for improving the overall mechanical properties of GH4169 alloy. The heat treatment process for improving the overall mechanical properties of GH4169 alloy includes the following preparation steps:

[0074] S1. Solution treatment: The GH4169 forgings are obtained by three-stage smelting to obtain ingots, homogenizing them, forging them into billets with a forging ratio of 3, and finally hot forging them into shape. The GH4169 forgings are subjected to solution treatment. The GH4169 forgings are heated to 800℃ in the furnace at 220℃ / h and held for 10min. Then, the temperature is raised to the solution temperature of 980℃ at 150℃ / h and held for 60min to obtain the solution-treated GH4169 forgings.

[0075] During the solution treatment, the strengthening phase γ′′ / γ′ phase completely dissolves, leaving about 7.2% undissolved δ phase inside the alloy. This part of the δ phase can prevent the alloy from being notch sensitive and improve its high-temperature creep resistance.

[0076] S2. Controlled cooling treatment after solution treatment: The solution-treated GH4169 forging in S1 is cooled to the microstructure stability temperature of 450℃ at a rate of 8℃ / min and held for 10min. Then it is taken out and air-cooled to room temperature to obtain a GH4169 forging with a precipitate distribution that tends to be stable.

[0077] During the cooling process to the microstructure stabilization temperature, the γ′′ / γ′ phase inside the alloy will precipitate. The quantity and size of the γ′′ / γ′ phase precipitates can be controlled, resulting in the precipitation of a large number of fine-sized γ′′ / γ′ phases with a content of 40% (area fraction) and an average size of 18.0 nm.

[0078] S3. Low-temperature aging treatment: The GH4169 forgings in S2 with the precipitate distribution tending to be stable are subjected to low-temperature aging treatment. The workpiece is heated to 500℃ in the furnace at 220℃ / h and held for 10min; then heated to the low-temperature aging treatment temperature of 620℃ at 150℃ / h and aged for 6h; then taken out and air-cooled to room temperature to obtain the GH4169 forging finished product with high comprehensive mechanical properties.

[0079] like Figure 2 As shown, the GH4169 forging with high comprehensive mechanical properties prepared in this embodiment has a γ′′ / γ′ phase content of 61% (area fraction) and an average size of 22.7 nm.

[0080] The room temperature properties of the GH4169 forging with high comprehensive mechanical properties prepared in this embodiment are as follows: yield strength 1167 MPa, tensile strength 1375 MPa, yield-to-tensile ratio 0.849, elongation after fracture 20.3%, reduction of area 31%, and strength-ductility product 27.913 GPa; the high temperature properties at 540℃ are as follows: yield strength 966 MPa, tensile strength 1157 MPa, yield-to-tensile ratio 0.835, elongation after fracture 26.5%, reduction of area 36%, and strength-ductility product 30.661 GPa.

[0081] Example 3

[0082] This embodiment describes a heat treatment process for improving the overall mechanical properties of GH4169 alloy. The heat treatment process for improving the overall mechanical properties of GH4169 alloy includes the following preparation steps:

[0083] S1. Solution treatment: The GH4169 forgings are obtained by three-stage smelting to obtain ingots, homogenizing them, forging them into billets with a forging ratio of 3, and finally hot forging them into shape. The GH4169 forgings are subjected to solution treatment. The GH4169 forgings are heated to 700℃ in the furnace at 320℃ / h and held for 20min. Then, the temperature is raised to the solution temperature of 980℃ at 250℃ / h and held for 60min to obtain the solution-treated GH4169 forgings.

[0084] During the solution treatment, the strengthening phase γ′′ / γ′ phase completely dissolves, leaving about 7.2% undissolved δ phase inside the alloy. This part of the δ phase can prevent the alloy from being notch sensitive and improve its high-temperature creep resistance.

[0085] S2. Controlled cooling treatment after solution treatment: The solution-treated GH4169 forging in S1 is cooled to the microstructure stability temperature of 400℃ at a rate of 12℃ / min and held for 20min. Then it is taken out and air-cooled to room temperature to obtain a GH4169 forging with the precipitate distribution tending to be stable.

[0086] During the cooling process to the microstructure stabilization temperature, the γ′′ / γ′ phase inside the alloy will precipitate. The quantity and size of the γ′′ / γ′ phase precipitates can be controlled to ensure that a large number of fine-sized γ′′ / γ′ phases are precipitated, with a content of 47% (area fraction) and an average size of 20.0 nm.

[0087] S3. Low-temperature aging treatment: The GH4169 forgings with the precipitate distribution of S2 tending to be stable are subjected to low-temperature aging treatment. The workpiece is heated to 550℃ in the furnace at 320℃ / h and held for 30min; then heated to the low-temperature aging treatment temperature of 620℃ at 220℃ / h and aged for 10h; then taken out and air-cooled to room temperature to obtain the GH4169 forging finished product with high comprehensive mechanical properties.

[0088] like Figure 3 As shown, the GH4169 forging with high comprehensive mechanical properties prepared in this embodiment has a γ′′ / γ′ phase content of 61% (area fraction) and an average size of 21.3 nm.

[0089] The room temperature properties of the GH4169 forging with high comprehensive mechanical properties prepared in this embodiment are as follows: yield strength 1204 MPa, tensile strength 1414 MPa, yield-to-tensile ratio 0.851, elongation after fracture 20.8%, reduction of area 33%, and strength-ductility product 29.411 GPa; the high temperature properties at 540℃ are as follows: yield strength 989 MPa, tensile strength 1188 MPa, yield-to-tensile ratio 0.832, elongation after fracture 27.4%, reduction of area 36%, and strength-ductility product 32.551 GPa.

[0090] Comparative Example 1

[0091] This comparative example describes a heat treatment process for a GH4169 alloy, which includes the following preparation steps:

[0092] S1. Solution treatment: The GH4169 forgings are obtained by three-stage smelting to obtain ingots, homogenizing them, forging them into billets with a forging ratio of 3, and finally hot forging them into shape. The GH4169 forgings are subjected to solution treatment. The GH4169 forgings are heated to 750℃ in the furnace at 250℃ / h and held for 20min. Then, the temperature is raised to the solution temperature of 980℃ at 200℃ / h and held for 60min to obtain the solution-treated GH4169 forgings.

[0093] During the solution treatment, the strengthening phase γ′′ / γ′ phase completely dissolves, leaving about 7.2% undissolved δ phase inside the alloy. This part of the δ phase can prevent the alloy from being notch sensitive and improve its high-temperature creep resistance.

[0094] S2, Air Cooling: Take out the solution-treated GH4169 forging from S1 and air cool it to room temperature to obtain a cooled GH4169 forging;

[0095] S3, Standard Two-Stage Aging Treatment: The cooled GH4169 forging from S2 undergoes a standard two-stage aging treatment. The workpiece is heated in the furnace at 250℃ / h to 600℃ and held for 20 minutes; then heated at 180℃ / h to a high-temperature aging temperature of 720℃ and aged for 8 hours; after that, the workpiece is furnace cooled in the furnace at 55℃ / h to a room temperature aging temperature of 620℃ and held for 8 hours, and finally air-cooled to room temperature to obtain the finished GH4169 forging.

[0096] like Figure 4 As shown, the GH4169 forging product prepared in this comparative example has a γ′′ / γ′ phase content of 61% (area fraction) and an average size of 25.2 nm.

[0097] The room temperature properties of the GH4169 forgings prepared in this comparative example are as follows: yield strength 1124 MPa, tensile strength 1347 MPa, yield-to-tensile ratio 0.834, elongation after fracture 18.4%, reduction of area 27%, and strength-ductility product 24.785 GPa; the high temperature properties at 540℃ are as follows: yield strength 931 MPa, tensile strength 1121 MPa, yield-to-tensile ratio 0.831, elongation after fracture 24.7%, reduction of area 31%, and strength-ductility product 27.689 GPa.

[0098] The above-mentioned solution proposes a heat treatment process to improve the comprehensive mechanical properties of GH4169 alloy. This process can solve the technical problems in the prior art, such as the inability to synergistically improve the strength and plasticity of GH4169 through alloy composition design and / or preparation method improvement, the conflict between preparation cost and product quality, the small synergistic improvement, and the mismatch between the obtained performance and production cost and production efficiency.

[0099] The solution treatment of this invention involves heating the GH4169 forging in the furnace at 220-320℃ / h to 700-800℃ and holding for 10-30 min; then heating again at 150-250℃ / h to the solution temperature of 980±10℃ and holding for 60±10 min. During this period, all the strengthening phases γ′′ / γ′ dissolve, leaving approximately 7.2% undissolved δ phase inside the alloy. This portion of δ phase can prevent the alloy from exhibiting notch sensitivity and improve its high-temperature creep resistance.

[0100] This invention employs controlled cooling, specifically cooling to 400-500℃ at a rate of 8-12℃ / min. During this process, the γ′′ / γ′ phase precipitates within the alloy. Controlling the cooling rate during this phase is crucial. Excessive cooling leads to insufficient or no precipitation of the γ′′ / γ′ phase, resulting in an alloy matrix with insufficient γ′′ / γ′ phase precipitation even after the subsequent low-temperature aging process in step three. Conversely, excessive cooling leads to excessive γ′′ / γ′ phase precipitation and significant coarsening, resulting in an irreversible strengthening effect regardless of subsequent aging. Experimental verification shows that cooling at the rate specified in step two ensures the precipitation of a large amount of fine-sized γ′′ / γ′ phase, with a content of 40-47% (area fraction) and an average size of 18.0-20.0 nm.

[0101] This invention employs low-temperature aging treatment, omitting the standard 720℃ high-temperature aging process. This effectively avoids the significant coarsening of the γ′′ / γ′ phase precipitated during the cooling rate of 8-12℃ / min after solution treatment at 720℃. Instead, only a 620℃ low-temperature aging treatment is performed. The already precipitated γ′′ / γ′ phase exhibits minimal coarsening under low-temperature aging, and even finer γ′′ / γ′ phases can be precipitated, thereby enhancing the strengthening effect. Simultaneously, the original two-stage aging process is shortened, achieving cost reduction and efficiency improvement.

[0102] In summary, compared with traditional methods for improving the comprehensive mechanical properties of GH4169 alloy, the method of the present invention, through solution treatment + controlled cooling + low-temperature aging treatment, can synergistically improve the room temperature strength and plasticity of the alloy, thereby further enhancing the comprehensive mechanical properties of the alloy. The method is simple in process, easy to operate, environmentally friendly, low in cost, and highly efficient, which is conducive to large-scale industrial production and application.

[0103] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0104] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0105] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy, characterized in that, The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy includes the following preparation steps: S1. Solution treatment: The GH4169 forging is solution treated to obtain the GH4169 forging in a solution-treated state; S2. Controlled cooling treatment after solution treatment: The solution-treated GH4169 forging in S1 is cooled to the microstructure stability temperature at a specific rate and held at that temperature. Then it is taken out and air-cooled to room temperature to obtain a GH4169 forging with a precipitate distribution that tends to be stable. S3. Low-temperature aging treatment: The GH4169 forging with the precipitate distribution of S2 tending to be stable is subjected to low-temperature aging treatment, and then taken out and air-cooled to room temperature to obtain the GH4169 forging finished product with high comprehensive mechanical properties.

2. The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy according to claim 1, characterized in that, The GH4169 forgings in S1 are obtained by: obtaining ingots through three-stage smelting, homogenizing heat treatment, forging blanks, forging ratio ≥3, and finally hot forging.

3. The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy according to claim 1, characterized in that, In S1, the solution treatment of GH4169 forgings is carried out by heating the furnace at 220-320℃ / h to 700-800℃ and holding for 10-30min; then the temperature is further increased at 150-250℃ / h to the solution temperature of 980±10℃ and held for 60±10min.

4. The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy according to claim 1, characterized in that, During the S1 solution treatment, the strengthening phase γ′′ / γ′ phase completely dissolves. At this time, 7.2±0.5% of the undissolved δ phase remains inside the alloy. This part of the δ phase can avoid the alloy from notch sensitivity and improve the high-temperature creep performance.

5. The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy according to claim 1, characterized in that, The cooling rate of the solution-treated GH4169 forging in S2 is 8-12℃ / min, the microstructure stabilization temperature is 400-450℃, the holding temperature is 10-20min, and then it is taken out and air-cooled to room temperature.

6. The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy according to claim 1, characterized in that, During the cooling process to the microstructure stabilization temperature in S2, the γ′′ / γ′ phase inside the alloy will precipitate. The quantity and size of the γ′′ / γ′ phase precipitates can be effectively controlled to ensure that a large number of fine-sized γ′′ / γ′ phases are precipitated, with a content of 40%-47% (area fraction) and an average size of 18.0-20.0 nm.

7. The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy according to claim 1, characterized in that, The S3 low-temperature aging treatment involves heating the GH4169 alloy in the furnace at 220-320℃ / h to 500-550℃ and holding for 10-30 min; then heating at 150-220℃ / h to the aging temperature of 620±10℃ and aging for 6-10 h.

8. The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy according to claim 1, characterized in that, The GH4169 forgings with high comprehensive mechanical properties in S3 have a γ′′ / γ′ phase content of 61% (area fraction) and an average size of 21.3-22.7 nm.

9. The heat treatment process for improving the comprehensive mechanical properties of GH4169 alloy according to claim 1, characterized in that, Compared to the S1 GH4169 forgings, the S3 high-comprehensive mechanical properties GH4169 forgings show improvements in room temperature and high temperature yield strength of 4.5%-7.1% and 4.6%-6.2%, respectively; room temperature and high temperature tensile strength of 2.1%-5.0% and 3.2%-6.0%, respectively; room temperature and high temperature elongation of 24.0%-25.8% and 25.0%-27.6%, respectively; and room temperature and high temperature reduction of area of ​​14.8%-22.2% and 12.9%-16.1%, respectively.

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