Manufacturing process of high plasticity high strength GH3230 forgings, prepared forgings and application thereof

Abstract

This invention provides a manufacturing process for high-plasticity and high-strength GH3230 forgings, the resulting forgings, and their applications. The process includes the following steps: pre-deforming the GH3230 forging billet at 1100℃-1180℃; finalizing the pre-deformed billet at 1100℃-1150℃; and performing a three-stage solution heat treatment on the forging, including holding at 1100℃-1175℃ for 30-120 minutes, raising the temperature to 1200℃ and holding for 30-120 minutes, and then raising the temperature to 1230℃ and holding for 10-60 minutes. This invention achieves coordinated control of grain size and carbide morphology through a step-by-step deformation design involving pre-deformation and final forming, combined with a three-stage solution heat treatment. The forging grain size is better than grade 3 and consists of uniform equiaxed grains, with carbides distributed in a granular dispersed manner, eliminating grain boundary network carbides. The three-stage stepped heating combined with a controlled heating rate effectively inhibits abnormal grain growth while fully dissolving carbides, solving the grain coarsening problem caused by traditional rapid heating.

Description

Technical Field

[0001] This invention relates to, and particularly to, a manufacturing process for a high-plasticity, high-strength GH3230 forging, the resulting forging, and its applications. Background Technology

[0002] GH3230 alloy is a nickel-based superalloy widely used in high-temperature components of gas turbines, such as turbine disks and turbine blades. These alloys need to possess both high-temperature strength and good plastic deformation capacity to meet the requirements of gas turbines operating in harsh environments.

[0003] Currently, GH3230 forgings are typically manufactured using conventional hot working and heat treatment processes. In terms of hot working, forging is generally performed using single or multiple deformation methods. Regarding heat treatment, traditional GH3230 alloy forging heat treatment processes mainly include solution treatment at a single temperature. This method is simple and easy to implement, but it is difficult to simultaneously achieve both strength and plasticity of the material. For example, Chinese patent CN110484841B discloses a heat treatment method for GH4780 alloy forgings. This method, through solution heat treatment within a temperature range of 1020-1170℃, can effectively eliminate alloy element segregation, break up columnar crystals, promote dynamic recrystallization, thereby refining the grains and improving the strength and plasticity of the alloy forgings. However, this method is only applicable to GH4780 alloy and uses a single temperature range for solution treatment, making it difficult to meet the synergistic requirements of high plasticity and high strength for GH3230 alloy.

[0004] The existing technology has the following main shortcomings: First, the control of forging deformation amount and deformation temperature is not precise enough, resulting in uneven grain size of forgings and easy occurrence of mixed grain structure; Second, the solution heat treatment system is not reasonable enough, making it difficult to fully dissolve the grain boundary network carbides, or the grains grow abnormally during the heating process; Third, some processes add aging treatment after solution treatment, which can slightly improve the strength, but leads to a significant decrease in plasticity, making it difficult to achieve both high strength (tensile strength ≥800MPa) and high plasticity (elongation ≥50%).

[0005] Therefore, it is urgent to develop a new manufacturing process for GH3230 forgings to solve the above-mentioned technical problems. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a manufacturing process for high-plasticity, high-strength GH3230 forgings, which solves the problems of high plasticity and high strength, as well as uneven microstructure, in existing GH3230 free forging parts for medium-gas turbines. Furthermore, this invention will also provide high-plasticity, high-strength GH3230 forgings produced by this manufacturing process; in addition, this invention will also provide applications of this high-plasticity, high-strength GH3230 forging.

[0007] To achieve the above and other related objectives, the present invention provides the following technical solutions: In a first aspect, the present invention provides a manufacturing process for a high-plasticity, high-strength GH3230 forging, comprising the following steps: (1) Pre-deformation: The GH3230 forging billet is preheated at 1100℃-1180℃ and subjected to one or more high-temperature plastic deformations, with a total deformation of 20%-50%; (2) Final forming: The pre-deformed billet is preheated at 1100℃-1150℃ and subjected to 15%-25% high-temperature plastic deformation along the streamline direction of the final forging to obtain the forging; (3) Heat treatment: The forgings obtained in step (2) are subjected to a three-stage solution heat treatment, wherein the three-stage solution heat treatment includes: First stage: Keep warm at 1100℃-1175℃ for 30-120 minutes; Second stage: Heat to 1200℃ and hold for 30-120 minutes; Third stage: Heat to 1230℃ and hold for 10-60 minutes; After the heat preservation is completed, quickly cool to room temperature.

[0008] In step (1), the pre-deformation temperature is preferably 1120℃-1160℃. This temperature range can ensure that the alloy has good hot working plasticity while avoiding excessive grain growth.

[0009] In step (2), the final forming temperature is preferably 1120℃~1140℃. Performing 15%~25% critical deformation within this temperature range allows for the formation of a uniform equiaxed grain structure through deformation-induced grain boundary migration during subsequent solution heat treatment.

[0010] In step (2), the high-temperature plastic deformation occurs once during the final molding process, which helps to maintain the accumulation of deformation energy and provide sufficient driving force for recrystallization in subsequent heat treatment.

[0011] In step (3), the heating rate in the second stage is 100℃±50℃ / h, and the heating rate in the third stage is 50℃±20℃ / h.

[0012] The three-stage solution heat treatment of this invention has the following characteristics: The first stage is held at 1100℃-1175℃, which can eliminate forging work hardening and initially dissolve fine carbides within the grains; the second stage is heated to 1200℃ at a controlled rate of 100℃±50℃ / h. This slow heating process makes the internal temperature field of the forging tend to be uniform, avoiding thermal stress concentration. At the same time, the heating process itself constitutes a homogenization process, and the next stage can be entered without long-term holding; the third stage is heated to 1230℃ at a more moderate rate of 50℃±20℃ / h and held. This temperature can fully dissolve the grain boundary network carbides, and the controlled heating rate can prevent abnormal grain growth at high temperatures.

[0013] In step (3), the rapid cooling method is at least one of air cooling, forced air cooling, or oil cooling.

[0014] Preferably, the cooling method is oil cooling, or the forging is first air-cooled to below 1000°C and then subjected to forced air cooling. This cooling method can ensure a sufficient cooling rate to suppress carbide precipitation along the grain, and can also effectively reduce the risk of cracking of the forging due to excessive thermal stress.

[0015] In step (3), the manufacturing process does not involve aging treatment after heat treatment.

[0016] Secondly, the present invention provides a high-plasticity, high-strength GH3230 forging, which is prepared by the above-mentioned manufacturing process. The forging has uniform equiaxed grains with a grain size better than grade 3, and the carbide size is 10-20 μm, which is dispersed in a granular manner.

[0017] Furthermore, the forging has a room temperature elongation of ≥50%, a tensile strength of ≥800MPa, a yield strength of ≥330MPa, and no grain boundary network precipitation of carbides.

[0018] Thirdly, the present invention provides the application of the above-mentioned high-plasticity and high-strength GH3230 forgings in gas turbine components.

[0019] As described above, the manufacturing process of the high-plasticity, high-strength GH3230 forgings of the present invention, the resulting forgings, and their applications have the following beneficial effects: 1. Through the step-by-step deformation design of pre-deformation and final forming, combined with three-stage solution heat treatment, the grain size and carbide morphology are coordinated and controlled. The grain size of the forging is better than level 3 and is uniform equiaxed. The carbides are dispersed in a granular manner, eliminating the network carbides at grain boundaries.

[0020] 2. A three-stage stepped heating solution process is adopted, combined with a controlled heating rate, which effectively inhibits abnormal grain growth while fully dissolving carbides, thus solving the grain coarsening problem caused by traditional rapid heating.

[0021] 3. Using oil cooling or segmented cooling instead of water cooling significantly reduces the risk of forging cracking while ensuring the suppression of carbide precipitation, resulting in higher process safety.

[0022] 4. The aging treatment step in the traditional process is omitted, which allows the forging to retain the high plasticity of the solution-treated state. It successfully achieves a synergistic improvement in tensile strength ≥800MPa and elongation ≥50%, meeting the requirement that the room temperature tensile elongation must reach more than 40%, exceeding the requirements of American standard AMS5891, while also meeting the strength requirements at room temperature. Attached Figure Description

[0023] Figure 1 The microstructure of the forging obtained in Embodiment 1 of the present invention is shown. Figure 1 .

[0024] Figure 2 The microstructure of the forging obtained in Embodiment 1 of the present invention is shown. Figure 2 . Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. It should be noted that, unless otherwise specified, the following embodiments and features described herein can be combined with each other.

[0026] This invention provides a manufacturing process for high-plasticity, high-strength GH3230 forgings, comprising the following steps: (1) Pre-deformation: The GH3230 forging billet is preheated at 1100℃-1180℃ and subjected to one or more high-temperature plastic deformations, with a total deformation of 20%-50%. In this step, the pre-deformation temperature is preferably 1120℃-1160℃. This temperature range can ensure that the alloy has good hot working plasticity while avoiding excessive grain growth. The pre-deformation process can be completed by various forging methods such as free forging and die forging. By reasonably controlling the deformation amount and deformation temperature, a good microstructure foundation is laid for subsequent processes.

[0027] (2) Final forming: The pre-deformed billet is preheated at 1100℃-1150℃ and subjected to 15%-25% high-temperature plastic deformation along the streamline direction of the final forging to obtain the forging. In this step, the preferred temperature for final forming is 1120℃-1140℃. Performing 15%-25% critical deformation within this temperature range allows for deformation-induced grain boundary migration to obtain a uniform equiaxed grain structure during subsequent solution heat treatment. During the final forming process, the high-temperature plastic deformation occurs only once, which helps to maintain the accumulation of deformation energy and provides sufficient driving force for recrystallization in subsequent heat treatment.

[0028] (3) Heat treatment: The forgings obtained in step (2) are subjected to a three-stage solution heat treatment, which includes: First stage: Heat the forging to 1100℃-1175℃ and hold for 30-120 minutes. This stage can eliminate forging work hardening and initially dissolve fine carbides within the grains.

[0029] The second stage involves raising the temperature to 1200℃ at a controlled heating rate of 100℃±50℃ / h and holding it at that temperature for 30-120 minutes. This slow heating process helps to homogenize the internal temperature field of the forging, avoiding thermal stress concentration. At the same time, the heating process itself constitutes a homogenization process, which is beneficial for the further dissolution of carbides.

[0030] The third stage involves raising the temperature to 1230℃ at a controlled heating rate of 50℃±20℃ / h and holding it at that temperature for 10-60 minutes. This temperature allows for the complete dissolution of the grain boundary network carbides, while the controlled heating rate prevents abnormal grain growth at high temperatures.

[0031] After the heat treatment is completed, the forging is rapidly cooled to room temperature. Rapid cooling can be achieved using at least one of air cooling, forced air cooling, or oil cooling. Preferably, oil cooling is used, or the forging is first air-cooled to below 1000°C before forced air cooling. This cooling method ensures a sufficient cooling rate to suppress carbide precipitation along the grain and effectively reduces the risk of cracking caused by excessive thermal stress.

[0032] To prevent the precipitation of harmful continuous network M6C or M23C6 carbides in the sensitization temperature range of 900℃-700℃, the cooling rate should be no less than 30℃ / s; preferably, the cooling rate range is 50℃ / s-150℃ / s; more preferably, the cooling rate is 90℃ / s-120℃ / s.

[0033] This manufacturing process does not perform aging treatment after step (3). This is because GH3230 is a solid solution strengthened alloy, and its standard service state is the solid solution state. If aging treatment is added after solid solution treatment, although the strength can be slightly improved, it will lead to a sharp decrease in plasticity, making it difficult to achieve the target of elongation ≥50%. By omitting the aging treatment, the inherent high plasticity characteristics of the solid solution state are preserved.

[0034] The GH3230 forgings prepared by the above process exhibit excellent comprehensive properties, with a room temperature elongation ≥50%, tensile strength ≥800MPa, yield strength ≥330MPa, grain size better than grade 3, and no grain boundary network precipitation of carbides. The grains of the forgings are uniform equiaxed crystals, and the carbide size is 10-20μm, with a granular and dispersed distribution. This microstructure is key to achieving both high plasticity and high strength.

[0035] This high-plasticity, high-strength GH3230 forging can be applied to components for gas turbines. GH3230 alloy, as a nickel-based high-temperature alloy, possesses excellent high-temperature strength, oxidation resistance, and hot corrosion resistance, making it particularly suitable for manufacturing critical gas turbine components such as turbine disks, blades, guide vanes, and combustion chamber parts. The high-plasticity, high-strength GH3230 forging provided in this embodiment, due to its excellent room-temperature elongation and strength, can significantly improve the reliability and service life of gas turbine components, and is especially suitable for critical parts operating in complex environments with significant stress variations.

[0036] In practical applications of gas turbine components, the high-plasticity, high-strength GH3230 forging can withstand complex working conditions such as high temperature, high pressure, and high-speed rotation, exhibiting excellent fatigue resistance and fracture toughness. Due to its uniform equiaxed grain structure and dispersed carbides, the forging has good microstructural stability during high-temperature service and can maintain excellent mechanical properties over a long period of time.

[0037] Example 1 This embodiment provides a high-plasticity, high-strength GH3230 forging, the manufacturing process of which includes the following steps: (1) Pre-deformation: The forging billet is preheated at 1140℃ and subjected to a high-temperature plastic deformation, with a deformation amount of 35%; (2) Final forming: The pre-deformed billet is preheated at 1130℃ and subjected to a 20% high-temperature plastic deformation along the flow line direction of the final forging to obtain the forging; (3) Heat treatment: The forgings undergo a three-stage solution treatment, including: First stage: Hold at 1150℃ for 60 minutes; Second stage: Increase the temperature to 1200℃ at a rate of 100℃ / h, and hold for 60 minutes after reaching the temperature; Third stage: Increase the temperature to 1230℃ at a rate of 50℃ / h, and hold for 30 minutes; After holding, cool to room temperature with oil.

[0038] According to the test results, the GH3230 forging prepared in this embodiment has a room temperature tensile strength of 825 MPa, a yield strength of 376 MPa, an elongation after fracture of 53%, and a reduction of area of ​​50%.

[0039] Figures 1 to 2 The image shows the microstructure of the forging in this embodiment. It reveals a uniform equiaxed grain structure with a grain size of 4 to 5. Carbides are dispersed in a granular manner, without any grain boundary network carbides. This image demonstrates that the high-temperature solution treatment at 1230℃ fully dissolved the original grain boundary network phase, and that the subsequent cooling process successfully suppressed secondary intergranular precipitation during cooling.

[0040] Example 2 This embodiment provides a high-plasticity, high-strength GH3230 forging, the manufacturing process of which includes the following steps: (1) Pre-deformation: The forging billet is preheated at 1160℃ and subjected to two high-temperature plastic deformations, with a total deformation of 45%; (2) Final forming: The pre-deformed billet is preheated at 1120℃ and subjected to a 15% high-temperature plastic deformation along the flow line direction of the final forging to obtain the forging; (3) Heat treatment: The forgings undergo a three-stage solution treatment, including: First stage: Hold at 1120℃ for 90 minutes; Second stage: Increase the temperature to 1200℃ at a rate of 80℃ / h, and hold for 45 minutes after reaching the temperature; Third stage: Increase the temperature to 1230℃ at a rate of 60℃ / h, and hold for 20 minutes; After the holding period, first air cool to 980℃, and then use strong air cooling to bring the temperature to room temperature.

[0041] Testing revealed that the GH3230 forging prepared in this embodiment exhibited the following characteristics: room temperature tensile strength of 830 MPa, yield strength of 388 MPa, elongation after fracture of 54%, and reduction of area of ​​55%. The grain size reached grade 5, the microstructure consisted of uniform equiaxed crystals, and the carbide size was 10–18 μm, exhibiting a granular, dispersed distribution without grain boundary network carbides.

[0042] Example 3 This embodiment provides a high-plasticity, high-strength GH3230 forging, the manufacturing process of which includes the following steps: (1) Pre-deformation: The forging billet is preheated at 1120℃ and subjected to three high-temperature plastic deformations, with a deformation amount of 25%; (2) Final forming: The pre-deformed billet is preheated at 1140℃ and subjected to a 25% high-temperature plastic deformation along the flow line direction of the final forging to obtain the forging; (3) Heat treatment: The forgings undergo a three-stage solution treatment, including: First stage: Hold at 1170℃ for 40 minutes; Second stage: Increase the temperature to 1200℃ at a rate of 120℃ / h, and hold for 90 minutes after reaching the temperature; Third stage: Increase the temperature to 1230℃ at a rate of 40℃ / h, and hold for 45 minutes; After holding, cool to room temperature with oil.

[0043] Testing revealed that the GH3230 forging prepared in this embodiment had a room temperature tensile strength of 828 MPa, a yield strength of 375 MPa, an elongation after fracture of 55%, a reduction of area of ​​50%, a grain size of grade 4, a microstructure of uniform equiaxed crystals, and carbide sizes of 10~16 μm, which were dispersed in a granular manner without grain boundary network carbides.

[0044] Performance testing The forging samples from Examples 1 and 2 were tested according to ASTM E8 / E8M-24 standard, and the test results are shown in Table 1. (In the table, the forging sample with a diameter of 6.01 mm is from Example 1, and the forging sample with a diameter of 6.02 mm is from Example 2.) Table 1. Performance test results of forgings in Examples 1 and 2

[0045] Results Analysis: Both samples achieved tensile strengths exceeding 825 MPa and elongation after fracture exceeding 53%, simultaneously achieving high strength and high plasticity, overcoming the bottleneck of decreased plasticity accompanying strength improvement in traditional processes. Furthermore, the two sets of data showed extremely small dispersion (tensile strength difference of only 5 MPa, elongation difference of only 1%), indicating that the manufacturing process of this invention has a wide parameter window, good repeatability, and is suitable for industrial-scale mass production. Both samples fractured at the midpoint of the gauge length, indicating uniform material structure, absence of local defects, and deformation behavior consistent with uniform plastic deformation characteristics.

[0046] In summary, this invention pre-deforms the GH3230 forging billet at 1100℃-1180℃; then finalizes the pre-deformed billet at 1100℃-1150℃; and performs a three-stage solution heat treatment on the forging, including holding at 1100℃-1175℃ for 30-120 min, raising the temperature to 1200℃ and holding for 30-120 min, and then raising the temperature to 1230℃ and holding for 10-60 min. Through the step-by-step deformation design of pre-deformation and final shaping, combined with the three-stage solution heat treatment, this invention achieves synergistic control of grain size and carbide morphology. The forging has a grain size better than grade 3 and is uniformly equiaxed, with carbides dispersed in a granular manner, eliminating grain boundary network carbides. The three-stage stepped heating, combined with a controlled heating rate, effectively inhibits abnormal grain growth while fully dissolving carbides, solving the grain coarsening problem caused by traditional rapid heating. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0047] It should be noted that the embodiments described above are only some, not all, embodiments of the present invention, and are used only to illustrate the present invention, and should not be considered as limiting the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0048] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A manufacturing process for high-plasticity, high-strength GH3230 forgings, characterized in that, Includes the following steps: (1) Pre-deformation: The GH3230 forging billet is preheated at 1100℃-1180℃ and subjected to one or more high-temperature plastic deformations, with a total deformation of 20%-50%; (2) Final forming: The pre-deformed billet is preheated at 1100℃-1150℃ and subjected to 15%-25% high-temperature plastic deformation along the streamline direction of the final forging to obtain the forging; (3) Heat treatment: The forgings obtained in step (2) are subjected to a three-stage solution heat treatment, wherein the three-stage solution heat treatment includes: First stage: Keep warm at 1100℃-1175℃ for 30-120 minutes; Second stage: Heat to 1200℃ and hold for 30-120 minutes; Third stage: Heat to 1230℃ and hold for 10-60 minutes; After the heat preservation is completed, quickly cool to room temperature.

2. The manufacturing process of the high-plasticity, high-strength GH3230 forging according to claim 1, characterized in that, In the three-stage solution heat treatment in step (3), the heating rate in the second stage is 100℃±50℃ / h, and the heating rate in the third stage is 50℃±20℃ / h.

3. The manufacturing process of the high-plasticity, high-strength GH3230 forging according to claim 1, characterized in that, In step (3), the rapid cooling method is at least one of air cooling, forced air cooling, or oil cooling.

4. The manufacturing process of the high-plasticity, high-strength GH3230 forging according to claim 3, characterized in that, In step (3), the cooling method is oil cooling, or the forging is first air-cooled to below 1000°C and then subjected to forced air cooling.

5. The manufacturing process of the high-plasticity, high-strength GH3230 forging according to claim 1, characterized in that, In step (1), the pre-deformation temperature is preferably 1120℃-1160℃.

6. The manufacturing process of the high-plasticity, high-strength GH3230 forging according to claim 1, characterized in that, In step (2), the final forming temperature is preferably 1120℃-1140℃.

7. A high-plasticity, high-strength GH3230 forging, characterized in that, It is prepared by the manufacturing process described in any one of claims 1 to 6.

8. The high-plasticity, high-strength GH3230 forging according to claim 7, characterized in that, The high-plasticity, high-strength GH3230 forging has uniform equiaxed grains with a grain size better than grade 3, and the carbide size is 10-20μm, which is dispersed in a granular manner.

9. The high-plasticity, high-strength GH3230 forging according to claim 7, characterized in that, The high-plasticity, high-strength GH3230 forging has a room temperature elongation of ≥50%, a tensile strength of ≥800MPa, a yield strength of ≥330MPa, and no grain boundary network precipitation of carbides.

10. The application of the high-plasticity, high-strength GH3230 forgings according to any one of claims 7-9 in gas turbine components.

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