Heat treatment method for improving high-temperature durability of 3D printing GH4169 alloy and application

Abstract

The invention provides a heat treatment method for improving the high-temperature durability of a 3D printing GH4169 alloy, which comprises the following steps: printing and forming GH4169 alloy powder by adopting a selective laser melting technology, and then carrying out hot isostatic pressing treatment, solid solution heat treatment, primary aging treatment and secondary aging treatment to obtain the 3D printing GH4169 alloy for improving the high-temperature durability. The invention further provides application. The 3D printing GH4169 alloy capable of improving the high-temperature durability is used as an aerospace hot-end component under the working condition that the use temperature reaches 650 DEG C. Through the process route of'hot isostatic pressing + solid solution + dual aging ', printing state harmful phases are effectively eliminated, microscopic holes are healed, uniform and fine grain structures are obtained, and the precipitation behavior of gamma ''strengthening phases is optimized, so that the high-temperature durability of the alloy at the temperature of 650 DEG C is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a heat treatment method and its application for improving the high-temperature durability of GH4169 alloy in 3D printing. Background Technology

[0002] GH4169 possesses excellent corrosion resistance, good mechanical properties, and weldability. It is widely used in gas turbines, turbine blades, and combustion chamber components. GH4169 is a Ni-based precipitation-strengthened superalloy containing various alloying elements, exhibiting excellent comprehensive properties; its yield strength below 650℃ ranks first among wrought superalloys.

[0003] GH4169 alloy formed by selective laser melting (SLM) has the advantages of fine microstructure and high yield strength. However, its unique rapid solidification characteristics also lead to the following problems: (1) Microsegregation: The extremely fast cooling rate of the process leads to the enrichment of elements such as Nb and Mo in the interdendritic region, forming brittle Laves phase and chain carbides; (2) Residual stress and anisotropy: The high residual stress generated by the layer-by-layer solidification of the molten pool and the columnar crystal structure of epitaxial growth lead to obvious anisotropy in mechanical properties; (3) Structure defects: SLM formed GH4169 alloy contains defects such as unfused pores and microcracks.

[0004] The aforementioned problems, particularly the continuous distribution of brittle Laves phase and carbides at grain boundaries and interdendritic boundaries, become stress concentration points under high-temperature creep loads, preferentially initiating and rapidly propagating cracks, severely degrading the high-temperature creep life and reliability of the parts. The traditional solution-aging heat treatment process for GH4169 cannot adequately address these issues. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a heat treatment method and application for improving the high-temperature creep performance of GH4169 alloy in 3D printing, which addresses the shortcomings of the prior art. The method uses a process route of "hot isostatic pressing + solution treatment + double aging" to effectively eliminate harmful phases in the printing state, heal micropores, obtain uniform and fine grain structure, and optimize the precipitation behavior of γ'' strengthening phase, thereby significantly improving its high-temperature creep performance at 650℃.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a heat treatment method for improving the high-temperature creep performance of GH4169 alloy in 3D printing, the method being as follows: S1. Using laser selective melting technology, GH4169 alloy powder is printed into shape to obtain the GH4169 alloy part. S2. Hot Isostatic Pressing: The GH4169 alloy part obtained in S1 is subjected to hot isostatic pressing to obtain the hot isostatic pressed part. The process parameters for hot isostatic pressing are as follows: heating to 1100℃~1200℃ at a heating rate of 5℃ / min, maintaining constant temperature and pressure for 1h~4h under a pressure of 140MPa~180MPa, and then cooling to room temperature with the furnace. The purpose of hot isostatic pressing in this invention is to close and eliminate defects such as unfused pores and microcracks generated during the forming process under the combined action of high temperature and high pressure, thereby improving density; at the same time, this high temperature condition can complete recrystallization, break the original columnar crystal structure, obtain uniform and fine equiaxed grains, reduce anisotropy, and promote element homogenization. S3, Solution heat treatment: The hot isostatic pressing part obtained in S2 is subjected to solution heat treatment to obtain the solution-treated part; The parameters for the solution heat treatment are as follows: heating to 950℃~980℃ at a heating rate of 5℃ / min, holding at a constant temperature for 1 hour, and then cooling to room temperature with argon gas. The purpose of solution heat treatment in this invention is to further eliminate anisotropy, homogenize the elements, and eliminate residual stress based on the original hot isostatic pressing treatment. S4. First aging treatment: The solution-treated part obtained in S3 is heated to 710℃~730℃ at a heating rate of 5℃ / min, and kept at a constant temperature for 6h~8h. Then, it is cooled to 610℃~630℃ at a cooling rate of 40℃ / h~50℃ / h. The purpose of the first aging treatment in this invention is to promote the uniform precipitation of fine, dispersed γ' phase and γ'' phase nuclei within the crystal at a higher temperature. Slow cooling to the next stage temperature helps reduce internal stress. S5. Second aging treatment: The temperature is kept constant at 610℃~630℃ for 6h~8h, and then cooled to room temperature under argon atmosphere to obtain 3D printed GH4169 alloy with improved high temperature durability.

[0007] The purpose of the second aging treatment in this invention is to carry out the final aging at a relatively high temperature, so as to allow the γ'' phase to fully precipitate and grow to the optimal size to obtain peak strength; on the other hand, to promote the precipitation of granular, discontinuous δ phase at grain boundaries and phase boundaries, avoid the formation of harmful continuous films, thereby significantly strengthening grain boundaries and improving high-temperature creep resistance and durability.

[0008] Preferably, the parameters of the laser selective melting technology described in S1 are: laser power 200W~500W, scanning rate 800mm / s~1200mm / s.

[0009] Preferably, the method for printing GH4169 alloy powder in S1 is as follows: after vacuum drying, the high-temperature alloy GH4169 powder is loaded into a 3D printing equipment. Before printing, high-purity argon gas is introduced into the forming chamber of the 3D printing equipment for gas washing. The three-dimensional model to be printed is cut into slices with a layer thickness of 40µm to 60µm and imported into a powder bed laser melting forming equipment for printing.

[0010] Preferably, the process parameters for the hot isostatic pressing treatment in S2 are: maintaining constant temperature and pressure for 3 hours at a temperature of 1180℃ and a pressure of 160MPa, and then cooling to room temperature with argon gas.

[0011] Preferably, the solution heat treatment temperature in S3 is 980°C.

[0012] Preferably, the temperature of the first aging treatment in S4 is 720°C, and the constant temperature holding time is 8 hours.

[0013] Preferably, the temperature of the second aging treatment in S4 is 620°C, and the constant temperature holding time is 8 hours.

[0014] The present invention also provides the application of the 3D-printed GH4169 alloy with improved high-temperature durability obtained by the above-mentioned heat treatment method, wherein the 3D-printed GH4169 alloy with improved high-temperature durability is used as an aerospace hot-end component in operating conditions up to 650°C.

[0015] Preferably, the 3D-printed GH4169 alloy with improved high-temperature creep performance has the following high-temperature creep performance under stress conditions of 650℃ and 620MPa: creep time ≥23h and elongation rate ≥3%.

[0016] Preferably, the 3D-printed GH4169 alloy with improved high-temperature creep performance has the following high-temperature creep performance under stress conditions of 650℃ and 620MPa: creep time of 54.9h to 60.3h and elongation of 5.84% to 8.80%.

[0017] Compared with the prior art, the present invention has the following advantages: 1. The heat treatment method of the present invention effectively eliminates harmful phases in the printing state, heals microscopic pores, obtains uniform and fine grain structure, and optimizes the precipitation behavior of γ'' strengthening phase through the process route of "hot isostatic pressing + solution treatment + double aging", thereby significantly improving its high-temperature creep performance at 650℃.

[0018] 2. This invention effectively solves the high-temperature performance shortcomings of GH4169 alloy in 3D printing, providing technical support for its safe application in key hot-end components such as aero-engines, and can be used as aerospace hot-end components with operating temperatures up to 650℃.

[0019] 3. The heat treatment method of the present invention for improving the high-temperature durability of GH4169 alloy for 3D printing eliminates microsegregation, transforms or spheroidizes brittle phases, releases stress and obtains a stable and uniform distribution of strengthening phases, and eliminates defects such as pores in the microstructure, which is crucial for improving its high-temperature long-term performance.

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 The flowcharts are for the heat treatment method of the present invention for improving the high-temperature creep performance of GH4169 alloy for 3D printing and the heat treatment method of Comparative Example 1.

[0022] Figure 2 This is a printed microstructure image of the GH4169 alloy part after laser selective melting and forming in step S1 of Embodiment 1 of the present invention.

[0023] Figure 3 This is a microstructure of the 3D-printed GH4169 alloy with improved high-temperature durability after heat treatment, as described in Example 1 of this invention.

[0024] Figure 4 The high-temperature creep fracture results of the sample after solution treatment and two aging processes in Comparative Example 1 of this invention are shown in Figure b, which is a partial enlarged view of Figure a.

[0025] Figure 5 The image shows the high-temperature creep fracture results of the sample after hot isostatic pressing, solution treatment, and two aging processes in Example 1 of this invention. Figure b is a partial enlarged view of Figure a. Detailed Implementation

[0026] Example 1 The heat treatment method for improving the high-temperature creep performance of GH4169 alloy in this embodiment is illustrated in the flowcharts of the heat treatment methods in this embodiment and Comparative Example 1. Figure 1 As shown, the method is as follows: S1. Using selective laser melting (SLM) technology, GH4169 alloy powder is printed into shape to obtain the GH4169 alloy part. The GH4169 alloy part prepared in this embodiment is a standard GH4169 alloy durability test specimen. The specimen is perpendicular to the substrate direction, i.e., a vertical specimen. The parameters of the laser selective melting technology are: laser power 500W, scanning rate 800mm / s.

[0027] The method for printing GH4169 alloy powder is as follows: after vacuum drying, the high-temperature alloy GH4169 powder is loaded into a 3D printing equipment. Before printing, high-purity argon gas is introduced into the forming chamber of the 3D printing equipment for gas washing. The three-dimensional model to be printed is cut into slices with a layer thickness of 40µm and imported into a powder bed laser melting forming equipment for printing.

[0028] like Figure 2 The image shows the printed microstructure of the GH4169 alloy part after laser selective melting in this embodiment, with obvious molten pool boundaries and white Laves phase between dendrites. S2. Hot Isostatic Pressing: The GH4169 alloy part obtained in S1 is subjected to hot isostatic pressing to obtain the hot isostatic pressed part. The process parameters for the hot isostatic pressing treatment are as follows: heating to 1180℃ at a heating rate of 5℃ / min, maintaining constant temperature and pressure at 160MPa for 3 hours, and then cooling to room temperature with the furnace. The purpose of hot isostatic pressing in this embodiment is to close and eliminate defects such as unfused pores and microcracks generated during the forming process under the combined action of high temperature and high pressure, thereby improving density; at the same time, this high temperature condition can complete recrystallization, break the original columnar crystal structure, obtain uniform and fine equiaxed grains, reduce anisotropy, and promote element homogenization. S3, Solution heat treatment: The hot isostatic pressing part obtained in S2 is subjected to solution heat treatment to obtain the solution-treated part; The parameters for the solution heat treatment are: heating to 980°C at a heating rate of 5°C / min, holding at a constant temperature for 1 hour, and then cooling to room temperature with argon gas. The purpose of solution heat treatment in this embodiment is to further eliminate anisotropy, homogenize the elements, and eliminate residual stress based on the original hot isostatic pressing treatment. S4. First aging treatment: The solution-treated part obtained in S3 is heated to 720℃ at a heating rate of 5℃ / min, held at a constant temperature for 8h, and then cooled to 620℃ at a cooling rate of 40℃ / h. The purpose of the first aging treatment in this embodiment is to promote the uniform precipitation of fine, dispersed γ' phase and γ'' phase nuclei within the crystal at a higher temperature. Slow cooling to the next stage temperature helps reduce internal stress; S5. Second aging treatment: The temperature is kept constant at 620℃ for 8 hours, and then cooled to room temperature under argon atmosphere to obtain 3D printed GH4169 alloy with improved high-temperature durability.

[0029] like Figure 3 As shown, the microstructure of the 3D-printed GH4169 alloy with improved high-temperature durability obtained in this embodiment shows that the Laves phase is completely dissolved, the grains are uniform equiaxed, and there are granular precipitates at the grain boundaries.

[0030] The purpose of the second aging treatment in this embodiment is to perform the final aging at a relatively high temperature, so as to allow the γ'' phase to fully precipitate and grow to the optimal size to obtain peak intensity; on the other hand, to promote the precipitation of granular, discontinuous δ phase at grain boundaries and phase boundaries, avoid the formation of harmful continuous films, thereby significantly strengthening grain boundaries and improving high-temperature creep resistance and durability.

[0031] Comparative Example 1 The heat treatment method for improving the high-temperature creep performance of GH4169 alloy in this comparative example is the same as that in Example 1, except that the hot isostatic pressing treatment in step S2 is not performed in this comparative example.

[0032] The GH4169 alloy parts prepared in step S1 are from the same batch of samples as those in Example 1.

[0033] All specimens obtained by the heat treatment methods of Example 1 and Comparative Example 1 (i.e. conventional treatment) were subjected to high-temperature endurance tests at 650°C and 620 MPa stress (endurance test, when the time is ≥23h, 34.5MPa stress is applied every 10h until the specimen breaks).

[0034] like Figure 4 As shown, Figure b is a magnified view of a portion of Figure a. The high-temperature creep fracture morphology of the sample after solution treatment and two aging processes in Comparative Example 1 can be seen, and the dendritic growth trend in the microstructure can be observed.

[0035] like Figure 5 As shown, Figure b is a partial enlarged view of Figure a. The high-temperature long-term fracture surface of the sample after hot isostatic pressing + solution treatment + two aging processes in Example 1 consists of two parts: a creep crack initiation and propagation zone and an instantaneous fracture zone. The surface of the creep crack initiation and propagation zone is rough and has a rock candy-like morphology.

[0036] Both Example 1 and Comparative Example 1 involved testing two vertical specimens (i.e., vertical specimen-1 and vertical specimen-2). The test results are shown in Table 1. Table 1. High-temperature durability test results of the vertical specimens of Example 1 and Comparative Example 1 As shown in Table 1, the creep rupture time and creep elongation of the samples obtained by the heat treatment method of Example 1 of this invention are significantly improved compared with those of Comparative Example 1. Metallographic and fracture analysis show that the microstructure is uniform, the grain boundary strengthening effect is significant, and the resistance to crack initiation is greatly improved. This invention effectively solves the shortcomings of the high-temperature performance of GH4169 alloy in 3D printing, and provides technical guarantee for its safe application in key hot-end components such as aero-engines.

[0037] Example 2 The heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in this embodiment is as follows: S1. Using laser selective melting technology, GH4169 alloy powder is printed into shape to obtain the GH4169 alloy part, which is the GH4169 alloy standard durable test specimen. The specimen is perpendicular to the substrate direction, i.e., the vertical specimen. The parameters of the laser selective melting technology are: laser power 200W, scanning rate 1200mm / s.

[0038] The method for printing GH4169 alloy powder is as follows: after vacuum drying, the high-temperature alloy GH4169 powder is loaded into a 3D printing equipment. Before forming, high-purity argon gas is introduced into the forming chamber of the 3D printing equipment for gas washing. The three-dimensional model to be printed is cut into slices with a layer thickness of 60µm and imported into a powder bed laser melting forming equipment for printing. S2. Hot Isostatic Pressing: The GH4169 alloy part obtained in S1 is subjected to hot isostatic pressing to obtain the hot isostatic pressed part. The process parameters for the hot isostatic pressing treatment are as follows: heating to 1100℃ at a heating rate of 5℃ / min, maintaining constant temperature and pressure at 180MPa for 4 hours, and then cooling to room temperature with the furnace. S3, Solution heat treatment: The hot isostatic pressing part obtained in S2 is subjected to solution heat treatment to obtain the solution-treated part; The parameters for the solution heat treatment are: heating to 950°C at a heating rate of 5°C / min, holding at a constant temperature for 1 hour, and then cooling to room temperature with argon gas. S4. First aging treatment: The solution-treated part obtained in S3 is heated to 730℃ at a heating rate of 5℃ / min, held at a constant temperature for 6h, and then cooled to 610℃ at a cooling rate of 40℃ / h. S5. Second aging treatment: The temperature is kept constant at 610℃ for 6 hours, and then cooled to room temperature under argon atmosphere to obtain 3D printed GH4169 alloy with improved high-temperature durability.

[0039] High-temperature creep rupture tests were conducted according to the method of Example 1, testing two vertical specimens (i.e., vertical specimen-1 and vertical specimen-2) of 3D-printed GH4169 alloy with improved high-temperature creep rupture performance obtained by the heat treatment method of this example: The high-temperature creep performance of vertical specimen-1 under stress conditions of 650℃ and 620MPa is as follows: creep time is 50.1h and elongation is 3.25%.

[0040] The high-temperature creep performance of vertical specimen-2 under stress conditions of 650℃ and 620MPa is as follows: creep time is 45.6h and elongation is 4.32%.

[0041] Example 3 The heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in this embodiment is as follows: S1. Using laser selective melting technology, GH4169 alloy powder is printed into shape to obtain the GH4169 alloy part, which is the GH4169 alloy standard durable test specimen. The specimen is perpendicular to the substrate direction, i.e., the vertical specimen. The parameters of the laser selective melting technology are the same as in Example 1; The method for printing GH4169 alloy powder is the same as in Example 1; S2. Hot Isostatic Pressing: The GH4169 alloy part obtained in S1 is subjected to hot isostatic pressing to obtain the hot isostatic pressed part. The process parameters for the hot isostatic pressing treatment are as follows: the temperature and pressure are kept constant for 1 hour at 1200℃ and 140MPa, and then the furnace is cooled to room temperature. S3, Solution heat treatment: The hot isostatic pressing part obtained in S2 is subjected to solution heat treatment to obtain the solution-treated part; The parameters for the solution heat treatment are: heating to 960°C at a heating rate of 5°C / min, holding at a constant temperature for 1 hour, and cooling to room temperature with argon gas; S4. First aging treatment: The solution-treated part obtained in S3 is heated to 710℃ at a heating rate of 5℃ / min, held at a constant temperature for 7h, and then cooled to 630℃ at a cooling rate of 50℃ / h. S5. Second aging treatment: The temperature is kept constant at 630℃ for 7 hours, and then cooled to room temperature under argon atmosphere to obtain 3D printed GH4169 alloy with improved high-temperature durability.

[0042] High-temperature creep rupture tests were conducted according to the method of Example 1, testing two vertical specimens (i.e., vertical specimen-1 and vertical specimen-2) of 3D-printed GH4169 alloy with improved high-temperature creep rupture performance obtained by the heat treatment method of this example: The high-temperature creep performance of vertical specimen-1 under stress conditions of 650℃ and 620MPa is as follows: creep time is 51.2h and elongation is 3.68%.

[0043] The high-temperature creep performance of vertical specimen-2 under stress conditions of 650℃ and 620MPa is as follows: creep time is 53.7h and elongation is 4.21%.

[0044] In summary, the heat treatment method of the present invention, through the process route of "hot isostatic pressing + solution treatment + double aging", effectively eliminates harmful phases in the printing state, heals microscopic pores, obtains uniform and fine grain structure, and optimizes the precipitation behavior of γ'' strengthening phase, thereby significantly improving its high-temperature creep performance at 650℃.

[0045] This invention effectively addresses the shortcomings of GH4169 alloy in high-temperature performance during 3D printing, providing technical assurance for its safe application in critical hot-end components such as aero-engines. It can be used as aerospace hot-end components operating at temperatures up to 650℃. The heat treatment method of this invention for improving the high-temperature durability of GH4169 alloy eliminates microscopic segregation, transforms or spheroidizes brittle phases, releases stress, and obtains a stable and uniform distribution of strengthening phases. It also eliminates defects such as porosity within the microstructure, which is crucial for improving its long-term high-temperature performance.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in 3D printing, characterized in that, The method is as follows: S1. Using laser selective melting technology, GH4169 alloy powder is printed into shape to obtain the GH4169 alloy part. S2. Hot Isostatic Pressing: The GH4169 alloy part obtained in S1 is subjected to hot isostatic pressing to obtain the hot isostatic pressed part. The process parameters for hot isostatic pressing are as follows: heating to 1100℃~1200℃ at a heating rate of 5℃ / min, maintaining constant temperature and pressure for 1h~4h under a pressure of 140MPa~180MPa, and then cooling to room temperature with the furnace. S3, Solution heat treatment: The hot isostatic pressing part obtained in S2 is subjected to solution heat treatment to obtain the solution-treated part; The parameters for the solution heat treatment are as follows: heating to 950℃~980℃ at a heating rate of 5℃ / min, holding at a constant temperature for 1 hour, and then cooling to room temperature with argon gas. S4. First aging treatment: The solution-treated part obtained in S3 is heated to 710℃~730℃ at a heating rate of 5℃ / min, and kept at a constant temperature for 6h~8h. Then, it is cooled to 610℃~630℃ at a cooling rate of 40℃ / h~50℃ / h. S5. Second aging treatment: The temperature is kept constant at 610℃~630℃ for 6h~8h, and then cooled to room temperature under argon atmosphere to obtain 3D printed GH4169 alloy with improved high temperature durability.

2. The heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in 3D printing according to claim 1, characterized in that, The parameters of the laser selective melting technology described in S1 are: laser power 200W~500W, scanning rate 800mm / s~1200mm / s.

3. The heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in 3D printing according to claim 1, characterized in that, The method for printing GH4169 alloy powder described in S1 is as follows: After vacuum drying, the high-temperature alloy GH4169 powder is loaded into a 3D printing equipment. Before printing, high-purity argon gas is introduced into the forming chamber of the 3D printing equipment for gas washing. The three-dimensional model to be printed is cut into slices with a layer thickness of 40µm to 60µm and imported into a powder bed laser melting forming equipment for printing.

4. The heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in 3D printing according to claim 1, characterized in that, The process parameters for the hot isostatic pressing (HIP) treatment described in S2 are as follows: the temperature and pressure are kept constant for 3 hours at 1180℃ and 160MPa, and then cooled to room temperature with argon gas.

5. The heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in 3D printing according to claim 1, characterized in that, The solution heat treatment temperature described in S3 is 980℃.

6. The heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in 3D printing according to claim 1, characterized in that, The temperature for the first aging treatment described in S4 is 720℃, and the holding time is 8 hours.

7. The heat treatment method for improving the high-temperature creep resistance of GH4169 alloy in 3D printing according to claim 1, characterized in that, The second aging treatment described in S4 is performed at a temperature of 620°C for 8 hours.

8. An application of a 3D-printed GH4169 alloy with improved high-temperature creep resistance obtained by the heat treatment method according to any one of claims 1-7, characterized in that, The 3D-printed GH4169 alloy, which enhances high-temperature durability, is used as aerospace hot-end components operating at temperatures up to 650°C.

9. The application according to claim 7, characterized in that, The 3D-printed GH4169 alloy with improved high-temperature creep resistance exhibits the following high-temperature creep resistance under stress conditions of 650℃ and 620MPa: creep time ≥23h and elongation exceeding 3%.

10. The application according to claim 9, characterized in that, The 3D-printed GH4169 alloy with improved high-temperature creep resistance exhibits the following high-temperature creep resistance under stress conditions of 650℃ and 620MPa: creep time of 54.9h to 60.3h and elongation of 5.84% to 8.80%.

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