Heat treatment process for improving strength of additive manufacturing nickel base alloy FGH4098

Abstract

The invention discloses a heat treatment process for improving the strength of an additive manufacturing nickel-based alloy FGH4098, and belongs to the technical field of metal additive manufacturing and heat treatment. Comprising the following steps: forming an FGH4098 alloy blank by adopting a selective laser melting (LPBF) technology; performing high-vacuum packaging treatment on the cleaned sample to construct a clean independent microenvironment; and then direct aging heat treatment at the temperature of about 760 DEG C is carried out. According to the method, a traditional high-temperature solid solution step is abandoned, and a micron-sized fine grain structure and a high-density dislocation network which are unique to a printing state are completely reserved; meanwhile, oxygen erosion in the heat treatment process is effectively isolated through vacuum packaging, oxidative depletion of key strengthening elements (Al and Ti) is prevented, and it is ensured that phases are fully dispersed and separated out in the pure environment. According to the invention, the problems of grain coarsening and softening caused by high-temperature solid solution and easy oxidative deformation in conventional aging in the prior art are solved, the tensile strength, hardness and dimensional stability of the alloy are remarkably improved, and short-process precision manufacturing of high-performance components is realized.

Description

Technical Field

[0001] This invention relates to the fields of metal additive manufacturing and heat treatment technology, specifically a heat treatment process for improving the strength of additively manufactured nickel-based alloy FGH4098. Background Technology

[0002] FGH4098 alloy, as an advanced powder metallurgy nickel-based superalloy, is widely used in the manufacture of hot-end core components such as turbine disks for aerospace engines due to its excellent high-temperature strength, creep resistance, and good oxidation and corrosion resistance. With the continuous development of manufacturing technology, laser selective melting (LPBF) additive manufacturing technology, due to its extremely high design freedom and near-net-shape forming capability, has gradually become an important means of preparing complex FGH4098 structural parts. The LPBF process, based on a layer-by-layer melting and solidification process with extremely high cooling rates, results in an alloy that naturally possesses micron-level ultrafine grains and a high-density dislocation network structure. This unique non-equilibrium microstructure contains enormous potential for strengthening and toughening.

[0003] However, current heat treatment procedures for additive manufacturing FGH4098 alloys mostly follow the traditional solution treatment + aging standard heat treatment system used for powder metallurgy or forged alloys. This traditional process typically includes a high-temperature solution treatment step above 1090℃, the core purpose of which is to eliminate processing stress and homogenize the microstructure through sufficient atomic diffusion. But for additive manufacturing alloys, this high-temperature treatment is a double-edged sword: while high-temperature solution treatment eliminates stress, it also causes the unique metastable fine-grained structure of LPBF to recrystallize and grow significantly. The high-density dislocation strengthening structure also recovers and is largely annihilated, causing the material to not only lose its original excellent fine-grain strengthening and dislocation strengthening advantages, but also often resulting in a significant decrease in strength due to the sharp coarsening of grains.

[0004] To avoid the microstructure coarsening problem caused by high-temperature solution treatment, some studies have attempted to adopt direct aging processes, which skip the solution treatment step and proceed directly with heat treatment. However, existing direct aging processes face severe environmental control challenges during implementation. Because the FGH4098 alloy contains a high proportion of active strengthening elements such as aluminum (Al) and titanium (Ti), it is extremely sensitive to the oxygen content in the heat treatment atmosphere. In conventional industrial vacuum heat treatment furnaces, even with a certain vacuum level maintained, the trace amounts of residual oxygen or leaked gas in the furnace during the aging holding process, which lasts for several to tens of hours, are still sufficient to react with the surface of the high-temperature sample, leading to the formation of oxide scale or even a depleted layer of alloying elements. This destruction of surface integrity not only reduces the fatigue life of the component but also hinders the uniform precipitation of strengthening phases on the surface. Furthermore, the lack of effective physical isolation in direct heating methods makes it susceptible to the effects of airflow disturbances or uneven radiation within the furnace, causing uncontrollable thermal deformation of precision and complex components during the release of residual stress. Therefore, developing a novel heat treatment process that can fully preserve the fine-grained structure of the printed state while providing an extremely pure thermal environment to ensure surface integrity and enhance phase filling analysis has become a key technical bottleneck in fully realizing the performance potential of additive manufacturing FGH4098 alloy. Summary of the Invention

[0005] This invention mainly addresses the technical problems of existing additive manufacturing of FGH4098 alloy, which result in the disappearance of fine grain and dislocation structure and a decrease in strength due to traditional high-temperature solution heat treatment, while direct aging process is prone to deformation and cracking due to residual stress and insufficient precipitation of strengthening phase.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098, the process comprising the following steps: Step S1: Provide nickel-based alloy FGH4098 pre-alloyed powder; Step S2: The pre-alloyed powder is formed into an alloy billet using laser selective melting (LPBF) technology; Step S3: Separate the alloy billet from the forming substrate and perform surface cleaning to obtain the sample to be processed; Step S4: Vacuum seal the sample to be processed; Step S5, perform direct aging heat treatment on the vacuum-sealed sample: vacuum seal the sample in a quartz tube, heat it to the aging temperature and hold it at that temperature, then cool it to room temperature; Step S5 is performed directly after step S4 is completed, without undergoing high-temperature solution treatment.

[0007] Further, in step S1, the chemical composition of the nickel-based alloy FGH4098 pre-alloyed powder, by mass percentage, includes: Cr: 12.5–13.5%, Co: 18.0–21.0%, Mo: 3.5–4.5%, W: 3.5–4.5%, Ti: 3.4–4.0%, Al: 3.2–3.8%, Nb: 0.5–1.0%, C: 0.02–0.06%, B: 0.01–0.03%, Zr: 0.03–0.06%, with the balance being Ni. The particle size distribution of the pre-alloyed powder ranges from 15 to 45 μm, and the Hall flow rate is 14–16 s / 50 g.

[0008] Furthermore, the specific process conditions for step S2 include: preheating the substrate to 80°C before molding; and conducting the molding process under a high-purity argon atmosphere with an oxygen content of less than 100 ppm. The laser scanning parameters used are: laser power P = 188 W; scanning speed v = 1700 mm / s; powder layer thickness t = 30 μm; scanning spacing h = 30 μm; and a strip scanning strategy with 90° interlayer rotation.

[0009] Further, step S3 specifically includes: after the substrate has cooled to room temperature, separating the alloy billet using a wire cutting process; ultrasonically cleaning the separated sample with acetone and anhydrous ethanol for 10-15 minutes, and then drying it.

[0010] Further, the specific operation of step S4 is as follows: placing the sample to be treated in a quartz glass tube and evacuating the vacuum until the pressure is below 510. -3 After Pa, seal the seal and then proceed to step S5.

[0011] Further, the specific process parameters for step S5 are as follows: the heating rate is controlled at 5-10℃ / min; the aging temperature is 7605℃; and the holding time is 80.5 hours. After the holding time is completed, argon gas is introduced for protection, and the furnace is cooled with the furnace or air-cooled with a fan to below 100℃ before being removed from the furnace.

[0012] This invention provides a heat treatment process to improve the strength of additively manufactured nickel-based alloy FGH4098. It has the following beneficial effects: 1. This invention employs a direct aging process, which fully preserves the micron-sized cellular crystals and high-density dislocation network formed during laser selective melting, avoiding the microstructure recovery and recrystallization softening caused by traditional solid solution treatment. Direct aging achieves high dislocation density and promotes the precipitation of strengthening phases, resulting in high strength. This process route realizes multiple synergistic effects of grain refinement strengthening, dislocation strengthening, and precipitation strengthening, enabling the final alloy to achieve a significant improvement in tensile strength and microhardness without sacrificing plasticity, fully exploring the strengthening and toughening potential of FGH4098 alloy in the non-equilibrium state of additive manufacturing.

[0013] 2. This invention successfully solves the risk of macroscopic deformation or cracking caused by uneven release of residual stress in conventional direct aging processes through a non-thermal activated stress control mechanism. This allows the alloy to maintain excellent dimensional accuracy and structural integrity without undergoing high-temperature creep relaxation, making it particularly suitable for the manufacture of complex thin-walled components.

[0014] 3. This invention eliminates the solution treatment and high-temperature aging processes exceeding 1000 degrees Celsius required in traditional standard heat treatment, strictly limiting the maximum temperature of the entire heat treatment process to below the material's recrystallization temperature. This technical feature ensures that the rapid solidification and ultrafine grain structure unique to additively manufactured FGH4098 alloy does not undergo thermal coarsening, allowing the final product to fully inherit the excellent grain boundary strengthening effect of the printed state. This effectively overcomes the technical challenge of existing heat treatment processes often leading to a decline in material fatigue performance and local mechanical consistency due to abnormal grain growth.

[0015] 4. This invention significantly simplifies the post-processing chain of FGH4098 alloy, transforming it from the traditional, cumbersome multi-stage, high-temperature, long-duration heating to a single-stage aging process. This not only drastically reduces the maximum processing temperature but also effectively shortens the total process time. This short-process, low-energy-consumption design significantly reduces production costs and electricity consumption while substantially improving production turnover efficiency, providing a highly competitive technological path for the green, low-cost, and rapid mass production of high-performance nickel-based superalloy components in the aerospace field. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a schematic diagram illustrating the dimensional differences in the metallographic structure of the present invention; Figure 3 This is a schematic diagram of the fracture characteristics of the present invention. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example This embodiment provides a heat treatment process to improve the strength of additive manufacturing nickel-based alloy FGH4098, which is prepared using optimized parameters. The specific steps are as follows: Step S1: Preparation of raw material powder FGH4098 pre-alloyed powder was prepared by gas atomization, with a particle size distribution of 15–45 μm and a Hall flow rate of 15 s / 50 g. The chemical composition of the batch powder, by mass percentage, was: Cr: 13.0%, Co: 19.5%, Mo: 4.0%, W: 4.0%, Ti: 3.7%, Al: 3.5%, Nb: 0.75%, C: 0.04%, B: 0.02%, Zr: 0.045%, with the balance being Ni.

[0019] Step S2: Laser Selective Blowing (LPBF) Forming. The substrate is preheated to 80°C, and the forming chamber is filled with high-purity argon gas, with the oxygen content controlled at approximately 80 ppm. The following laser scanning parameters are used for printing: laser power P = 188W, scanning speed v = 1700mm / s, powder layer thickness t = 30μm, and scanning spacing h = 30μm. The scanning strategy adopts a strip scanning mode with 90° interlayer rotation.

[0020] Step S3: Sample separation and cleaning After the substrate has cooled to room temperature naturally, the alloy billet is separated from the substrate using wire cutting. It is then ultrasonically cleaned for 12 minutes with a mixture of acetone and anhydrous ethanol, and dried for later use.

[0021] Step S4: Vacuum Pretreatment The cleaned and dried sample to be treated was placed in a quartz glass tube, and a vacuum pump was connected to evacuate the air until the pressure inside the tube dropped to 310. -3 At Pa, the quartz tube is melt-sealed using an oxyhydrogen flame to complete the vacuum sealing of the sample.

[0022] Step S5: Direct aging heat treatment The vacuum-sealed sample was placed in a tube furnace and heated to 760°C at a rate of 10°C / min, and held at that temperature for 8 hours. It was then removed from the furnace and air-cooled to room temperature to complete the heat treatment.

[0023] Comparative Example Comparative Example 1 Compared with Example 1, the difference is that the aging temperature in step S5 exceeds the upper limit of the scope protected by this invention. The aging temperature of the vacuum-sealed sample was increased from 760°C to 845°C, while the holding time remained unchanged at 8 hours. All other process steps and parameters were the same.

[0024] Comparative Example 2 Compared to Example 1, the difference lies in extending the aging time in step S5. The aging time of the vacuum-sealed sample was extended from 8 hours to 16 hours, while the remaining process steps and parameters remained the same.

[0025] Comparative Example 3 Compared to Example 1, the difference lies in the addition of an aging treatment between steps S4 and S5. Specifically, the vacuum-sealed sample is first heated to 845°C and held at that temperature for 4 hours, then removed from the furnace and air-cooled to room temperature. Afterward, the sample undergoes the aging treatment at 760°C as described in step S5. All other process steps and parameters remain the same.

[0026] Comparative Example 4 Compared to Example 1, the difference lies in the addition of a standard high-temperature solution treatment between steps S4 and S5. Specifically, the vacuum-sealed sample is heated to 1090°C and held at that temperature for 1 hour, then removed and air-cooled to room temperature. Afterward, the sample undergoes the 760°C aging treatment of step S5, with all other process steps and parameters remaining the same.

[0027] Comparative Example 5 Compared to Example 1, the difference lies in the addition of a standard high-temperature solution treatment between steps S4 and S5. Specifically, the vacuum-sealed sample is first heated to 1130°C and held for 1 hour, then removed and air-cooled to room temperature. Next, the sample is heated to 845°C and held for 4 hours, then removed and air-cooled to room temperature. Afterward, the sample undergoes the 760°C aging treatment of step S5; all other process steps and parameters remain the same.

[0028] Test Example 1: Room Temperature Tensile Properties Test 1. Experimental Instructions and Procedures This experiment was conducted in accordance with the national standard GB / T228.1-2010 "Metallic materials, tensile testing—Part 1: Test at room temperature". The test aimed to evaluate the influence of different heat treatment processes on the macroscopic mechanical properties of FGH4098 alloy.

[0029] The specific operating steps are as follows: First, the heat-treated block specimens of Example 1 and Comparative Examples 1 to 5 were machined into standard tensile specimens by wire electrical discharge machining (WEDM) and CNC turning. The specimens were plate-shaped, 50 mm long, 10 mm wide, with a gauge length of 15 mm, a width of 4 mm, and a thickness of 1 mm. The coolant flow rate was strictly controlled during machining to prevent the processing heat from affecting the specimen microstructure.

[0030] Secondly, before testing, the surface of the gauge section of the specimen was lightly sanded with fine sandpaper to remove machining marks and oxide layers until the surface roughness Ra was less than 1.6 μm. The diameter of each gauge section of the specimen was measured and recorded using a high-precision vernier caliper, and the average value was taken from three different cross-sections to calculate the original cross-sectional area.

[0031] Finally, the specimen was mounted on an electronic universal testing machine equipped with an electronic extensometer. Uniaxial tensile loading was performed at room temperature (252℃). The test was conducted in displacement control mode, with a constant loading rate of 1.0 mm / min. The computer system automatically collected load-displacement data until the specimen fractured. The tensile strength (Rm), specified plastic extension strength (Rp0.2), and elongation after fracture (A) were calculated based on the collected data.

[0032] Reference Figure 3 Figure a shows the fracture morphology of Example 1, which exhibits typical brittle fracture characteristics and obvious cleavage steps can be observed. In contrast, Figure b (Comparative Example 4) shows ductile fracture with a large number of dimples distributed on the fracture surface.

[0033] 2. Experimental Data Table 1. Room temperature tensile properties of FGH4098 alloy samples under different heat treatment processes. ; As can be seen from the data in Table 1, Example 1, which uses the vacuum encapsulation + direct aging process of the present invention, obtained the best comprehensive mechanical properties. Its tensile strength reached 1610 MPa and its yield strength reached 1425.28 MPa, which is significantly better than Comparative Example 4 and Comparative Example 5, which use traditional standard heat treatment (solution + aging).

[0034] First, abandoning high-temperature solution treatment is key to improving strength. Comparing the data of Example 1 with Comparative Example 4 (solution at 1090℃) and Comparative Example 5 (solution at 1130℃), it can be found that although the elongation of the sample treated with high-temperature solution treatment is higher, its yield strength drops significantly (only about 1058~1155 MPa). This is because although high-temperature solution treatment eliminates stress, it also causes the micron-sized cellular structure unique to laser selective melting (LPBF) to recrystallize and grow significantly, while also causing a large number of high-density dislocation networks originally present in the printed state to be annihilated. In contrast, Example 1 of this invention uses a direct aging process, which completely preserves the fine-grained structure and dislocation structure of the non-equilibrium state in additive manufacturing. Through the synergistic effect of fine-grain strengthening and dislocation strengthening, extremely high matrix strength is maintained.

[0035] Secondly, the choice of low-temperature aging is crucial for maintaining metastable structures.

[0036] Comparing the data from Example 1 (aging at 760℃) and Comparative Example 1 (aging at 845℃), it can be seen that when the direct aging temperature is increased to 845℃, the tensile strength of the alloy decreases from 1610 MPa to 1400.29 MPa. This indicates that excessively high aging temperatures accelerate the coarsening of the strengthening phase and may induce localized softening of the microstructure, weakening the precipitation strengthening effect. This invention strictly controls the aging temperature around 760℃, ensuring sufficient driving force for phase dispersion and precipitation while avoiding over-aging of the microstructure due to excessively high temperatures, thus achieving optimal strength matching.

[0037] Finally, vacuum packaging technology ensures high performance.

[0038] The superior performance of Example 1 compared to conventional processes is also attributed to its unique vacuum encapsulation pretreatment. Compared to direct heating in a conventional vacuum furnace, pre-sealing the sample in a high-vacuum microenvironment within a quartz tube maximizes the protection against oxidation and erosion of the sample surface by residual oxygen during heating, preventing the depletion of active strengthening elements such as Al and Ti in the alloy. This stringent protection mechanism ensures the purity and surface integrity of the precipitation reaction during aging, allowing residual stress within the material to be gently released in a pure thermal environment while the strengthening phase precipitates uniformly to the greatest extent possible. In contrast, comparative examples (such as Comparative Example 2) without optimized encapsulation or with inappropriate parameter control exhibit significantly lower strength (1477.92 MPa) than Example 1, further validating the significant advantages of the specific process route of this invention (vacuum encapsulation + direct aging at 760℃) in unlocking the strengthening and toughening potential of the FGH4098 alloy.

[0039] Test Example 2: Vickers Hardness Test 1. Experimental Instructions and Procedures This experiment was conducted in accordance with the national standard GB / T4340.1-2009 "Metallic materials - Vickers hardness test - Part 1: Test method". The test aims to evaluate the differences in the micro-strengthening effect and local deformation resistance of the alloy matrix by measuring microhardness.

[0040] The specific operating steps are as follows: First, small sample pieces measuring 10mm x 10mm x 5mm were cut from the center of each heat-treated sample. These pieces were then mounted using a metallographic mounting machine with thermosetting resin to ensure the flatness of the test surface. Subsequently, the samples were progressively ground on an automatic polishing machine using 240#, 600#, 1000#, and 2000# wet sandpaper. Finally, 1.0m diamond polishing paste was applied to a velvet polishing cloth for polishing until the sample surface achieved a mirror-like finish, and no obvious scratches were observed under an optical microscope.

[0041] Next, the prepared metallographic sample was placed on the stage of the micro Vickers hardness tester. A diamond square pyramid indenter was selected, and the test force was set to 500 gf (4.90 N), with a holding time of 15 seconds. To avoid mutual interference between work-hardened areas, the distance between the centers of adjacent indentations was strictly controlled to be more than three times the length of the indentation diagonal, and the distance between the indentation and the edge of the sample was not less than 2.5 mm.

[0042] Finally, multiple points were randomly selected on the surface of each sample for testing in non-overlapping areas. The lengths of the two diagonals of the indentation were measured through a microscope eyepiece, and the Vickers hardness value (HV) was automatically calculated by the equipment according to the formula. To cover local inhomogeneities of the material, at least 7 valid points were tested for each sample, all data were recorded, and the arithmetic mean was taken as the final result after discarding the maximum and minimum values.

[0043] like Figure 2 As shown in (a) and (d), (a) is the metallographic structure of Example 1, (b) is Comparative Example 1, (c) is Comparative Example 4, and (d) is Comparative Example 5. A comparison reveals that the grain size and morphology of Example 1 and Comparative Example 1 are not significantly different; however, the grain coarsening characteristics are more pronounced in Comparative Examples 4 and 5, exhibiting obvious grain growth.

[0044] 2. Experimental Data Table 2. Original and average data of microVickers hardness tests on FGH4098 alloy samples processed using different techniques. ; 3. Analysis of Experimental Results The test results in Table 2 clearly reveal the decisive influence of different heat treatment strategies on the microhardness of the material. The average hardness of Example 1 reached 574.4 HV, which is significantly higher than that of Comparative Example 4 (467.79 HV) after conventional high-temperature solution treatment.

[0045] This significant difference in hardness directly verifies the core advantages of the vacuum packaging + direct aging process of this invention: First, abandoning high-temperature solid solution treatment is the key to maintaining high hardness.

[0046] As can be seen from the data in Comparative Example 4, once a high-temperature solution treatment step (usually above 1000℃) is introduced, the hardness of the material drops sharply to around 460 HV. This is because the high temperature causes the micron-sized cellular crystals unique to laser selective melting (LPBF) to recrystallize and grow, while the high-density dislocation network accumulated inside the printed state recovers and annihilates, leading to softening of the matrix. In contrast, Example 1 uses a direct aging process, which completely preserves the fine-grained structure and dislocation network of the printed state. The matrix itself is in a hard state, and the phase strengthening precipitated during aging further enhances the hardness, thus achieving a hardness level far higher than that of traditional processes.

[0047] Second, vacuum encapsulation ensures the complete extraction of the enhanced phase.

[0048] Comparing Example 1 (574.4 HV) with Comparative Example 2 (561 HV) and Comparative Example 5 (565.37 HV), it can be seen that Example 1 exhibits superior hardness. This is attributed to the quartz tube vacuum encapsulation technology used in this invention, which creates an extremely high vacuum (510 HV) within a tiny, sealed space. -3 The environment (Pa) effectively isolates the sample surface from oxygen corrosion during heating, prevents the oxidation and depletion of key strengthening elements such as Al and Ti in the alloy, and ensures that the strengthening phase can be fully and uniformly dispersed and precipitated during the subsequent aging process at 760℃.

[0049] Third, the rationality of low-temperature aging parameters.

[0050] Data shows that controlling the aging temperature at 760℃ is the optimal window for maintaining high hardness. At this temperature, the precipitation kinetics of the strengthening phase are moderate, avoiding both insufficient precipitation at low temperatures and over-aging coarsening caused by high temperatures (such as Comparative Example 4). Although Comparative Example 3 achieved a hardness of 605.7 HV (presumably corresponding to a high alloy content composition system), Example 1 still maintained an extremely high hardness value under standard composition, and the data at each test point (556~586 HV) showed small fluctuations, proving that the process not only ensures performance improvement but also has good microstructure uniformity and process stability.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098, characterized in that, The process includes the following steps: Step S1: Provide nickel-based alloy FGH4098 pre-alloyed powder; Step S2: The pre-alloyed powder is formed into an alloy billet using laser selective melting (LPBF) technology; Step S3: Separate the alloy billet from the forming substrate and perform surface cleaning to obtain the sample to be processed; Step S4: Vacuum seal the sample to be processed; Step S5, perform direct aging heat treatment on the sample: place the sample in a vacuum environment, heat it to the aging temperature and hold it at that temperature, and then cool it to room temperature; Step S5 is performed directly after step S4 is completed, without undergoing high-temperature solution treatment.

2. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 1, characterized in that, In step S1, the chemical composition of the nickel-based alloy FGH4098 pre-alloyed powder, by mass percentage, includes: Cr: 12.5–13.5%, Co: 18.0–21.0%, Mo: 3.5–4.5%, W: 3.5–4.5%, Ti: 3.4–4.0%, Al: 3.2–3.8%, Nb: 0.5–1.0%, C: 0.02–0.06%, B: 0.01–0.03%, Zr: 0.03–0.06%, with the balance being Ni.

3. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 1, characterized in that, In step S1, the particle size distribution of the pre-alloyed powder ranges from 15 to 45 μm, and the Hall flow rate is 14 to 16 s / 50 g.

4. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 1, characterized in that, The specific process conditions for step S2 include: Preheat the substrate to 80-100°C before molding; The molding process is carried out under the protection of a high-purity argon atmosphere with an oxygen content of less than 100 ppm.

5. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 4, characterized in that, The laser scanning parameters used in step S2 are as follows: The laser power P is 188W; The scanning speed v is 1700 mm / s; the powder layer thickness t is 30 μm. The scanning interval h is 30m; The scanning strategy employs a strip scanning mode with 90° interlayer rotation.

6. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 1, characterized in that, Step S3 specifically includes: After the substrate cools to room temperature, the alloy billet is separated using a wire cutting process; The separated sample was ultrasonically cleaned with acetone and anhydrous ethanol for 10–15 minutes, and then dried.

7. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 1, characterized in that, In step S4, the specific operation of vacuum sealing is as follows: the sample to be processed is placed in a quartz glass tube, and a vacuum is drawn until the pressure is below 510. -3 After Pa, seal it.

8. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 1, characterized in that, In step S5, the heating rate is controlled at 5-10℃ / min.

9. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 1, characterized in that, In step S5, the aging temperature is 7605℃ and the holding time is 80.5 hours.

10. The heat treatment process for improving the strength of additive manufacturing nickel-based alloy FGH4098 according to claim 9, characterized in that, The cooling method in step S5 is as follows: After the heat preservation period, remove the product from the oven and air cool it.

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