A heat treatment process for a laser selective melting alloy and components thereof

Abstract

The present application relates to a kind of laser selective melting alloy and its component heat treatment process, belong to additive manufacturing heat treatment technical field, the existing heat treatment process has been solved and makes the component deformation and cracking risk big, leading to the problem of low component qualification rate.The heat treatment process includes the following steps: step 1: the alloy sample and / or its component prepared using laser selective melting technology is stress relieved;Step 2: the alloy and / or its component after stress relief is aged treatment.The heat treatment process of the present application can increase the component qualification rate by 30%-40%.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology in additive manufacturing, and more particularly to a heat treatment process for selective laser melting of GH4099 alloy and its components. Background Technology

[0002] GH4099 alloy is an age-hardening nickel-based superalloy, with the γ′ phase (γ′-Ni3(Al,Ti)) as its main strengthening phase. Through the coupled effect of precipitation strengthening of the high-density γ′ phase and solid solution strengthening by elements such as W, Mo, and Co, GH4099 superalloy can be used stably at 800-900℃, with a maximum operating temperature exceeding 1000℃. Simultaneously, GH4099 alloy also possesses high hot strength and good weldability and cold / hot working properties. Therefore, GH4099 alloy is a key structural material for components such as combustion chambers and sections of high-speed aircraft engines, and is widely used in aerospace and other military fields.

[0003] Currently, the main processing methods for GH4099 alloy are forging and machining, but traditional methods struggle to achieve integral forming of complex structures, significantly limiting the application and development of GH4099 high-temperature alloys. Selective laser melting (SLM) is an additive manufacturing (AM) technology that uses a high-energy laser beam to selectively heat metal powder, causing it to completely melt and rapidly solidify. Compared to other AM technologies (directional energy deposition, laser stereolithography, etc.), SLM technology has significant advantages in forming accuracy, forming complexity, and component quality, making it the ideal manufacturing technology for large-size, ultra-thin, and complex GH4099 high-temperature alloy components. However, in actual production, GH4099 high-temperature components prepared by SLM often experience deformation or cracking after heat treatment. The fundamental reason is that existing heat treatment processes are not suitable for GH4099 high-temperature components manufactured by SLM.

[0004] Currently, there are few reports on heat treatment systems for SLM-GH4099 alloy and components. Existing patents include: 1) Patent application number CN202110294836.7, entitled "Heat Treatment Process for GH4099 Alloy Laser Selective Melting Forming Parts"; and 2) Patent application number CN 202111310804.8, entitled "Heat Treatment Method for GH4099 Alloy Components Formed by Laser Selective Melting Forming." The SLM-GH4099 alloy heat treatment processes involved in the above two patent documents are optimized based on existing GH4099 casting or forging heat treatment processes, and their essence has not escaped the constraints of traditional heat treatment processes.

[0005] The traditional heat treatment process for GH4099 alloy requires solution treatment first. This involves slowly heating the GH4099 alloy to 1100℃, holding it at that temperature for 1-2 hours, and then air-cooling or water-cooling it to room temperature. Solution treatment introduces three problems: 1) increased risk of deformation and cracking; 2) insufficient performance improvement; and 3) reduced efficiency. Solution treatment, involving heating, holding, and cooling processes, significantly increases time costs, leading to lower production efficiency.

[0006] Therefore, providing a heat treatment process suitable for laser selective melting of GH4099 high-temperature alloy and its components is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] Based on the above analysis, the present invention aims to provide a heat treatment process for laser selective melting alloys and their components to solve at least one of the following technical problems: (1) the solution + aging heat treatment process causes high risk of component deformation and cracking, resulting in low component qualification rate; (2) the low temperature and high temperature tensile properties of SLM-GH4099 alloy are insufficient; (3) the existing heat treatment process for SLM-GH4099 high temperature alloy components is cumbersome and has low production efficiency.

[0008] On one hand, the present invention provides a heat treatment process for laser selective melting of alloys, comprising the following steps:

[0009] Step 1: The alloy prepared using selective laser melting technology is subjected to stress relief treatment;

[0010] Step 2: Aging treatment is performed on the stress-relief alloy.

[0011] Furthermore, step 2 includes the following steps:

[0012] Step 21: Place the alloy treated in Step 1 into a vacuum furnace and evacuate it;

[0013] Step 22: Heat the vacuum furnace until it reaches the target temperature, then hold it at that temperature for the first time; after the first holding is completed, cool the vacuum furnace to a lower temperature and hold it at that temperature for the second time.

[0014] Step 23: Cooling.

[0015] Furthermore, in step 21, the vacuum degree is 5 to 10 × 10⁻⁶. -4 Torr.

[0016] Further, step 23 includes: cooling the furnace to room temperature in a vacuum furnace.

[0017] Furthermore, the alloy is GH4099 alloy.

[0018] Further, step 1 includes the following steps:

[0019] Step 11: Place the alloy and / or its components in a vacuum furnace and evacuate the vacuum.

[0020] Step 12: Heat and maintain the temperature of the vacuum furnace;

[0021] Step 13: Cooling.

[0022] Furthermore, in step 12, the vacuum furnace is heated to 500-550°C and held for 1-2 hours.

[0023] Furthermore, in step 12, the heat preservation time is 2 hours.

[0024] Furthermore, the laser selective melting alloy includes an alloy sample and an alloy component.

[0025] On the other hand, the present invention also provides a laser selective melting alloy, which is obtained by the above-mentioned heat treatment process. The laser selective melting alloy has a room temperature yield strength ≥1020MPa, tensile strength ≥1180MPa, elongation ≥20%, and a yield strength ≥220MPa, tensile strength ≥290MPa, and elongation ≥25% at 950℃.

[0026] Furthermore, the tensile fracture surface of the alloy exhibits a transgranular fracture morphology.

[0027] Furthermore, the fracture surface of the alloy contains a large number of tiny dimples.

[0028] Furthermore, the internal reinforcing phase (γ′ phase) of the alloy is smaller in size and has a higher density.

[0029] Furthermore, the grain boundaries of the alloy do not contain large, continuous carbides.

[0030] Furthermore, in step 22, the first heat preservation temperature is higher than the second heat preservation temperature. The first heat preservation temperature is 800-850℃, which is used to promote the nucleation of the γ' phase, and the first heat preservation time is 1-2 hours. The second heat preservation temperature is 700-750℃, which is used to inhibit the growth of the γ' phase to obtain a small and dense γ' phase, and the second heat preservation time is 3-4 hours.

[0031] Compared with the prior art, the present invention can achieve at least one of the following technical effects:

[0032] 1) The traditional heat treatment process for GH4099 alloy in the existing technology is solution treatment + aging treatment. Even when combined with SLM technology, solution treatment + aging treatment is still used. However, the solution treatment + aging heat treatment process increases the risk of component deformation and cracking, resulting in a low component qualification rate. This invention utilizes the unique process characteristics of SLM technology, namely, a small molten pool and a fast cooling rate. The molten pool solidifies from a liquid state to a solid state in a very short time. Because the solute elements do not have enough time to diffuse, most of the elements exist in the solid solution form inside the deposited GH4099 alloy matrix.

[0033] Based on the above findings, this invention innovatively proposes to eliminate solution treatment and directly perform aging treatment. Because solution treatment requires direct air cooling (or water cooling) from 1100℃ to room temperature, uneven cooling of the alloy and component surface and core leads to deformation and cracking. The heat treatment process of this invention, by eliminating solution treatment, significantly reduces the risk of component deformation and cracking, and improves the component yield (by 30%-40%). Furthermore, by eliminating solution treatment, the heat treatment process is simplified, improving production efficiency.

[0034] (2) In terms of mechanical properties, the GH4099 alloy of this invention, after direct aging heat treatment, exhibits significantly superior room temperature and high temperature mechanical properties compared to samples treated with existing heat treatment methods (as shown in Table 1). Specifically, the room temperature yield strength is increased by more than 30%. Figure 6 and Figure 7 As shown, the directly aged specimen exhibits transgranular fracture, while the existing solution-aged specimen exhibits intergranular fracture. This may be related to the solution treatment, which enriches the grain boundaries with a large amount of solute elements, leading to weakened grain boundary strength and intergranular fracture. This also demonstrates the superiority of direct aging.

[0035] (3) Existing aging treatments are all one-step aging treatments, while the aging treatment of this invention is a two-step aging treatment. The first step of the aging treatment is used to promote the nucleation of the γ' phase, and the second step of the aging treatment is used to inhibit the growth of the γ' phase, so as to obtain a small and dense γ' phase, thereby improving the mechanical properties of the alloy. By setting the temperature of the first step of the aging treatment to be higher than that of the second step of the aging treatment, the mechanical properties of the alloy are further improved.

[0036] (4) The alloy obtained by the heat treatment process of the present invention has a room temperature yield strength ≥1020MPa, tensile strength ≥1180MPa, elongation ≥20%, and a yield strength ≥220MPa, tensile strength ≥290MPa, and elongation ≥25% at 950℃.

[0037] Other features and advantages of the invention will be set forth in the following description, and in part will be obvious from the description or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0038] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0039] Figure 1 This is a flowchart illustrating the heat treatment process of the SLM-GH4099 alloy component of this invention.

[0040] Figure 2(a) shows the microstructure of the deposited GH4099 alloy under low magnification;

[0041] Figure 2(b) shows the substructure of grains and the morphology of nano-carbide in the deposited GH4099 alloy under high magnification.

[0042] Figure 3 The inverse pole figure (IPF) of the deposited GH4099 alloy;

[0043] Figure 4 The images shown are SEM images of the tensile fracture surface of GH4099 alloy in Example 1. Among them, (a) is the macroscopic fracture morphology at low magnification parallel to the additive direction, (b) is the macroscopic fracture morphology at low magnification perpendicular to the additive direction, (c) is the microscopic fracture morphology at high magnification parallel to the additive direction, and (d) is the microscopic fracture morphology at high magnification perpendicular to the additive direction.

[0044] Figure 5 The following are SEM images of the tensile fracture ends of the GH4099 alloy in Comparative Example 1: (a) shows the macroscopic fracture morphology at low magnification parallel to the additive direction, (b) shows the macroscopic fracture morphology at low magnification perpendicular to the additive direction, (c) shows the microscopic fracture morphology at high magnification parallel to the additive direction, and (d) shows the microscopic fracture morphology at high magnification perpendicular to the additive direction.

[0045] Figure 6 Analysis of grain boundary morphology and γ′ phase in GH4099 alloy in Example 1;

[0046] Figure 7 For the analysis of grain boundary morphology and γ′ phase of GH4099 alloy in Comparative Example 1;

[0047] Figure 8 Tensile curves of GH4099 alloy under direct aging at 950℃. Detailed Implementation

[0048] The following detailed description of a heat treatment process for laser selective melting of GH4099 high-temperature alloy components, with reference to specific embodiments, is provided. These embodiments are for comparative and illustrative purposes only, and the present invention is not limited to these embodiments.

[0049] like Figure 1 As shown, this invention provides a heat treatment process for laser selective melting alloys and their components, particularly for the heat treatment of GH4099 (SLM-GH4099) alloys and their components prepared using laser selective melting technology. The chemical composition of the GH4099 nickel-based superalloy, by mass percentage, is: C≤0.08%, Cr17.00~20.0%, W5.00~7.00%, Mo3.50~4.50%, Al1.70~2.40%, Co5.00~8.00%, Ti1.00~1.50%, Fe≤2.00%, B≤0.005%, Mg≤0.010%, Ce≤0.020%, Mn≤0.40%, Si≤0.50%, P≤0.015%, S≤0.015%, with the remainder being Ni.

[0050] The above heat treatment process includes the following steps:

[0051] Step 1: Stress relief treatment is performed on the alloy and / or its components prepared using selective laser melting technology;

[0052] Step 2: The stress-relief alloy and / or its components are subjected to aging treatment to obtain SLM-GH4099 alloy and / or its components.

[0053] The traditional heat treatment process for GH4099 alloy in existing technologies is solution treatment followed by aging treatment. Even when combined with SLM technology, solution treatment plus aging treatment is still used. However, during the solution treatment process, due to the rapid cooling rate of the air or water cooling process, the cooling rate of the GH4099 alloy or component is uneven between the surface and the core, which easily generates large internal stress, increases the risk of component deformation and cracking, and results in a low component yield.

[0054] Furthermore, the purpose of solution treatment is to redistribute solute elements, originally existing as precipitated phases, within the matrix of the GH4099 alloy, so that they can be redeprecipitated during aging treatment, thereby achieving better mechanical properties. To ensure the solute elements re-enter the matrix as much as possible, the solution treatment process must have sufficiently high temperatures and long durations. While high temperatures and long durations promote the uniform distribution of elements in the matrix, they also lead to physical processes such as recrystallization, grain growth, dislocation annihilation, and segregation of solute elements at grain boundaries in the GH4099 alloy. Therefore, regardless of whether the GH4099 alloy is cast, forged, or additively manufactured, solution treatment significantly reduces internal defects such as dislocations and vacancies. These high-density defects can promote the nucleation and growth of the γ′ phase, thereby improving the properties of the GH4099 alloy. For example, dislocations can serve as nucleation sites for the γ′ phase, lowering the nucleation barrier and promoting the dispersed precipitation of the γ′ phase; vacancies act as diffusion media for solute elements, and a high density of vacancies can promote the diffusion of solute elements, which is conducive to the precipitation and growth of the γ′ phase and shortens the heat treatment time. From this perspective, solution treatment is also not conducive to the performance optimization of the SLM-GH4099 alloy.

[0055] This invention utilizes the unique process characteristics of SLM technology, namely, a small molten pool and a fast cooling rate. The molten pool solidifies from a liquid state to a solid state in a very short time. Since the solute elements do not have enough time to diffuse, most of the elements exist in the solid solution form inside the deposited GH4099 alloy matrix.

[0056] As shown in Figures 2(a) and 2(b), the deposited GH4099 alloy exhibits a uniform microstructure with fine grains and a large number of dislocation cells; the dislocation cell walls contain a small amount of white nano-carbide. Furthermore, from... Figure 3 It can be seen that the grain morphology of the deposited GH4099 alloy is irregular. It is noteworthy that, apart from a small amount of nanoscale carbides, no other second phase exists within the deposited GH4099 alloy, further proving that the deposited GH4099 alloy is in a supersaturated state, with most solute elements existing in a solid solution state within the matrix. The main reason for this phenomenon is that SLM is a strongly non-equilibrium process, with a small molten pool and a rapid cooling rate (up to 10). 6 -10 8 The SLM-GH4099 alloy solidifies in a very short time (K / s), causing solute elements in the molten pool to freeze inside the matrix before they can diffuse and precipitate. This microstructure is the most significant difference between the SLM-GH4099 alloy and the traditional cast and forged GH4099 alloy, and it also provides the possibility for the development of new heat treatment processes.

[0057] Meanwhile, the SLM-GH4099 high-temperature alloy contains high-density dislocation cells (as shown in Figure 2). The high density of dislocations can significantly reduce the nucleation barrier of the γ′ phase and promote the precipitation and growth of the γ′ phase. At the same time, the cellular structure interface contains a large number of solute element clusters (which have been observed in the literature and are a consensus in the academic community), which can significantly shorten the element diffusion distance. These solute clusters can also serve as nucleation sites to promote the formation of high-density γ′ phase.

[0058] The direct aging heat treatment process proposed in this invention makes full use of the high-density dislocations and cellular structure inside the deposited GH4099 alloy to generate a more dispersed γ′ phase. The high-density γ′ phase will hinder the movement of dislocations and significantly improve the performance of SLM-GH4099 alloy and components.

[0059] Specifically, step 1 includes the following steps:

[0060] Step 11: Place the alloy and / or its components in a vacuum furnace and evacuate the vacuum.

[0061] Step 12: Heat and maintain the temperature of the vacuum furnace;

[0062] Step 13: Cooling.

[0063] In one embodiment, in step 11, the vacuum degree of the vacuum furnace is 5 to 10 × 10⁻⁶. -4 Torr, for example, can be 5×10 -4 Torr, 6×10 -4 Torr, 7×10 -4 Torr, 8×10 -4 Torr, 9×10 -4 Torr, 10×10 -4 Torr.

[0064] In one embodiment, in step 12, the vacuum furnace is heated to 500–550°C, for example, 500°C, 510°C, 520°C, 530°C, 540°C, or 550°C. The heating rate is 5–10°C / min, for example, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, or 10°C / min. The holding time is 1–2 hours, for example, 1 hour, 1.5 hours, or 2 hours. The furnace temperature fluctuation is controlled within ±5°C.

[0065] In one embodiment, step 13, cooling includes cooling the alloy and / or its components to room temperature in the furnace.

[0066] Specifically, step 2 includes two time-sensitive processing steps, specifically the following steps:

[0067] Step 21: Place the alloy and / or its components treated in Step 1 into a vacuum furnace and evacuate them;

[0068] Step 22: First, heat the vacuum furnace to 800-850℃ and hold it for 1-2 hours; then cool it to 700-750℃ and hold it for 3-4 hours.

[0069] Step 23: Cooling.

[0070] In one embodiment, in step 21, the vacuum degree of the vacuum furnace is 5 to 10 × 10⁻⁶. -4 Torr, for example, can be 5×10 -4 Torr, 6×10 -4 Torr, 7×10 -4 Torr, 8×10 -4 Torr, 9×10 -4 Torr, 10×10 -4 Torr.

[0071] In one embodiment, in step 22, the first insulation temperature is higher than the second insulation temperature.

[0072] Specifically, the initial holding temperature is 800-850℃, for example, 800℃, 810℃, 820℃, 830℃, 840℃, or 850℃. The heating rate is 5-10℃ / min, for example, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min. The holding time is 1-2 hours, for example, 1 hour, 1.5 hours, or 2 hours. The furnace temperature fluctuation is controlled within ±5℃.

[0073] The second heat treatment temperature is 700-750℃, for example, 700℃, 710℃, 720℃, 730℃, 740℃, or 750℃. The cooling rate is 15-20℃ / min, for example, 15℃ / min, 16℃ / min, 17℃ / min, 18℃ / min, 19℃ / min, or 20℃ / min. The heat treatment time is 3-4 hours, for example, 3 hours, 3.5 hours, or 4 hours. The furnace temperature fluctuation is controlled within ±5℃.

[0074] In one embodiment, in steps 22 and 23, cooling includes cooling the alloy and / or its components to room temperature in the furnace.

[0075] The prepared SLM-GH4099 alloy and / or its components were subjected to tensile tests at room temperature and high temperature (950°C) by wire cutting.

[0076] Example 1:

[0077] (1) Place the GH4099 laser selective melting alloy sample along with the additive substrate into a vacuum furnace, and then evacuate the furnace until the vacuum level reaches 5×10⁻⁶. -4 Torr. The vacuum furnace was then heated to 500°C at a rate of 5°C / min and held for 2 hours for stress relief. After the holding period, the furnace was cooled to room temperature.

[0078] (2) The GH4099 alloy sample undergoing stress relief treatment was removed from the vacuum furnace, and the additive substrate was removed by wire cutting. The GH4099 alloy sample was then placed in a vacuum heat treatment furnace, and the furnace was evacuated to a vacuum level of 5×10⁻⁶. -4 Torr. The vacuum furnace was then heated to 800°C at a rate of 5°C / min and held for 2 hours. After holding, it was cooled to 700°C and held for 4 hours. After holding, the furnace was cooled to room temperature.

[0079] (3) After the GH4099 alloy sample cooled, wire cutting was used to prepare tensile samples, and room temperature and high temperature tensile tests were conducted. The test results are shown in Table 1.

[0080] Example 2:

[0081] (1) Place the GH4099 laser selective melting component along with the additive substrate into a vacuum furnace, and then evacuate the furnace until the vacuum level inside the furnace reaches 10×10⁻⁶. -4 Torr. The vacuum furnace was then heated to 550°C at a rate of 5°C / min and held for 1.5 hours for stress relief. After the holding period, the furnace was cooled to room temperature.

[0082] (2) Remove the GH4099 component that has undergone stress relief treatment from the vacuum furnace, remove the additive substrate using wire cutting, place the GH4099 component in a vacuum heat treatment furnace, and then evacuate the vacuum furnace to achieve a vacuum level of 10×10⁻⁶. -4 Torr. Then, the vacuum furnace was heated to 850°C at a heating rate of 5°C / min and held at that temperature for 1 hour. After the holding period, it was cooled to 750°C and held at that temperature for 3 hours. After the holding period, it was cooled to room temperature along with the furnace.

[0083] (3) After the GH4099 component cooled down, wire cutting was used to prepare tensile samples, and room temperature and high temperature tensile tests were conducted. The test results are shown in Table 1.

[0084] Example 3:

[0085] (1) Place the GH4099 laser selective melting alloy sample along with the additive substrate into a vacuum furnace, and then evacuate the furnace until the vacuum level inside the furnace reaches 8×10⁻⁶. -4Torr. The vacuum furnace was then heated to 520°C at a rate of 8°C / min and held for 2 hours for stress relief. After the holding period, the furnace was cooled to room temperature.

[0086] (2) The GH4099 alloy sample undergoing stress relief treatment was removed from the vacuum furnace, and the additive substrate was removed by wire cutting. The GH4099 alloy sample was then placed in a vacuum heat treatment furnace, and the furnace was evacuated to a vacuum level of 8×10⁻⁶. -4 Torr. The vacuum furnace was then heated to 820°C at a rate of 8°C / min and held for 1.5 hours. After holding, it was cooled to 720°C and held for 3 hours. After holding, the furnace was cooled to room temperature.

[0087] (3) After the GH4099 alloy sample cooled, wire cutting was used to prepare tensile samples, and room temperature and high temperature tensile tests were conducted. The test results are shown in Table 1.

[0088] Example 4:

[0089] (1) Place the GH4099 laser selective melting component along with the additive substrate into a vacuum furnace, and then evacuate the furnace until the vacuum level inside the furnace reaches 6×10⁻⁶. -4 Torr. The vacuum furnace was then heated to 530°C at a rate of 6°C / min and held for 1 hour for stress relief. After the holding period, the furnace was cooled to room temperature.

[0090] (2) Remove the stress-relief GH4099 component from the vacuum furnace, remove the additive substrate using wire cutting, place the GH4099 component in a vacuum heat treatment furnace, and then evacuate the vacuum furnace to achieve a vacuum level of 7×10⁻⁶. -4 Torr. The vacuum furnace was then heated to 830°C at a rate of 6°C / min and held for 1.5 hours. After holding, it was cooled to 730°C and held for 3 hours. After holding, the furnace was cooled to room temperature.

[0091] (3) After the GH4099 component cooled down, wire cutting was used to prepare tensile samples, and room temperature and high temperature tensile tests were conducted. The test results are shown in Table 1.

[0092] Comparative Example 1:

[0093] (1) The SLM-GH4099 alloy sample, along with the additive substrate, was placed in a vacuum heat treatment furnace. Then, the furnace was evacuated to achieve a vacuum level of 5 × 10⁻⁶. -4 Torr. First, the vacuum furnace was heated to 500°C at a heating rate of 5°C / min and held for 2 hours for stress relief. After the holding period, the furnace was cooled to room temperature.

[0094] (2) Next, the vacuum furnace was heated to 1100℃ at a heating rate of 10℃ / min and held for 1 hour for solution treatment. After the holding period, the furnace was cooled to room temperature by blowing low-temperature argon gas for about 50 minutes.

[0095] (3) Then, the vacuum furnace was heated to 750℃ at a heating rate of 10℃ / min and held for 8 hours. After the holding period, the GH4099 alloy sample was cooled to room temperature with the furnace.

[0096] (4) After the GH4099 alloy sample cooled, wire cutting was used to prepare tensile samples, and room temperature and high temperature tensile tests were conducted. The test results are shown in Table 1.

[0097] Comparative Example 2:

[0098] Comparative Example 2 is basically the same as Example 4, except that the aging treatment is a one-step aging treatment. Specifically, the vacuum furnace is heated to 800°C at a heating rate of 6°C / min and held at that temperature for 8 hours. After the holding period, the furnace is cooled to room temperature.

[0099] Comparative Example 3:

[0100] Comparative Example 3 is basically the same as Example 4, except that the temperature of the first aging treatment is lower than that of the second aging treatment. Specifically, the vacuum furnace was heated to 730°C at a heating rate of 6°C / min and held for 1.5 hours. After the holding period, the temperature was increased to 830°C and held for 3 hours. After the holding period, the furnace was cooled to room temperature.

[0101] Comparative Example 4:

[0102] Comparative Example 4 is basically the same as Example 4, except that the temperature of the first aging treatment is not in the range of 800-850℃, and the temperature of the second aging treatment is not in the range of 700-750℃. Specifically, the vacuum furnace is heated to 900℃ at a heating rate of 6℃ / min and held for 1.5 hours. After the holding period, it is cooled to 800℃ and held for 3 hours. After the holding period, it is cooled to room temperature with the furnace.

[0103] Table 1. Comparison of room temperature and high temperature tensile properties of specimens from Examples 1-4 and Comparative Examples 1-4

[0104]

[0105]

[0106] As can be seen from the data in Comparative Example 1 and Examples 1-4 in Table 1, the mechanical properties of the products obtained by the heat treatment process of solution treatment followed by aging treatment are significantly worse than those of the products obtained by the heat treatment process of the present invention of direct aging treatment.

[0107] A comparison of the data from Comparative Example 2 and Example 4 shows that the mechanical properties of the alloy treated with a direct one-step aging process (Comparative Example 2) are not as good as those treated with a two-step aging process (Example 4).

[0108] A comparison of the data from Comparative Example 3 and Example 4 shows that if the temperature of the first aging treatment is lower than the temperature of the second aging treatment, the mechanical properties of the alloy are poor.

[0109] A comparison of the data from Comparative Example 4 and Example 4 shows that if the temperature of the first aging treatment is not within the range of 800-850℃, and the temperature of the second aging treatment is not within the range of 700-750℃, the mechanical properties of the alloy are poor.

[0110] In addition to tensile testing, the present invention also conducted microstructure and performance analysis on Example 1 and Comparative Example 1.

[0111] Figure 4 and Figure 5 The tensile fracture analyses are for Example 1 and Comparative Example 1, respectively. Figure 4 As shown, the GH4099 high-temperature alloy obtained in Example 1 exhibits a distinct transgranular fracture morphology, with numerous small dimples on the fracture surface. In contrast, the GH4099 high-temperature alloy obtained in Comparative Example 1 exhibits an intergranular fracture morphology, but the dimple size is significantly larger compared to Example 1.

[0112] Figure 6 and Figure 7 The analysis of grain boundaries and γ′ phases in Example 1 and Comparative Example 1 are respectively. Figure 6 and Figure 7 As shown, Example 1 and Comparative Example 1 yielded GH4099 alloy containing high-density nano-sized γ′ precipitates. However, by comparison... Figure 6 and Figure 7 It is evident that the GH4099 alloy obtained in Example 1 exhibits a smaller and denser internal strengthening phase (γ′ phase). While small and dense precipitates hinder dislocation movement, they do not pin dislocations, thus preventing dislocation pile-up and cracking. Therefore, the small and dense γ′ precipitates produced in Example 1 not only improve the mechanical properties of the GH4099 alloy but also enhance its toughness. This is the fundamental reason for its significantly increased yield strength. Furthermore, the GH4099 alloy obtained in Example 1 has relatively clean grain boundaries, lacking large-sized, continuous carbides (precipitates). This indirectly demonstrates its high grain boundary bonding strength, making it less prone to intergranular fracture, which is consistent with... Figure 4 The experimental observations were consistent. However, the GH4099 alloy obtained in Comparative Example 1 exhibited numerous large, continuous carbides at its grain boundaries. These carbides weakened the grain boundary strength, making the material prone to fracture along the grain boundaries. This phenomenon can be well explained... Figure 5Why does the alloy in (Comparative Example 1) undergo intergranular fracture?

[0113] Figure 8 This is the tensile curve of GH4099 alloy at 950℃ in Example 1. (From...) Figure 8 It can be seen that the GH4099 alloy obtained by this invention has excellent mechanical properties at 950℃, which fully meets the service requirements of high-temperature components of aircraft.

[0114] The heat treatment process of this invention is particularly suitable for processing large thin-walled components, such as compartments and end frames. This invention improves the yield of large thin-walled components (compartments, end frames, etc.) by 30%-40% through direct aging treatment of GH4099 alloy samples and / or their components, and by setting the aging treatment as a two-step process, controlling the temperature of the first aging step to be higher than that of the second aging step. Compared with one-step aging, two-step aging not only allows for better control of alloy properties but also further eliminates residual stress generated by additive manufacturing, phase transformation, and other processes, thus improving the quality of large thin-walled components.

[0115] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A heat treatment process for laser selective melting of alloys, characterized in that, Includes the following steps: Step 1: The alloy prepared using selective laser melting technology is subjected to stress relief treatment; Step 2: Directly perform aging treatment on the stress-relief alloy; The alloy is GH4099 alloy; Step 2 includes two time-sensitive processing steps, including the following steps: Step 21: Place the alloy treated in Step 1 into a vacuum furnace and evacuate it; Step 22: Heat the vacuum furnace to 800-850℃ and perform the first heat preservation for 1-2 hours; after the first heat preservation is completed, cool the vacuum furnace to 700-750℃ and perform the second heat preservation for 3-4 hours. Step 23: Cooling.

2. The heat treatment process according to claim 1, characterized in that, In step 21, the vacuum degree is 5~10×10 - 4 Torr.

3. The heat treatment process according to claim 1, characterized in that, Step 23 includes: cooling the furnace to room temperature in a vacuum furnace.

4. The heat treatment process according to claim 1, characterized in that, Step 1 includes the following steps: Step 11: Place the alloy in a vacuum furnace and evacuate it; Step 12: Heat and maintain the temperature of the vacuum furnace; Step 13: Cooling.

5. The heat treatment process according to claim 4, characterized in that, In step 12, the vacuum furnace is heated to 500~550℃ and held for 1-2 hours.

6. The heat treatment process according to claim 5, characterized in that, In step 12, the heat preservation time is 2 hours.

7. The heat treatment process according to claim 1, characterized in that, The laser selective melting alloy includes alloy samples and alloy components.

8. A laser selective melting alloy, characterized in that, The laser selective melting alloy obtained by using the heat treatment process described in any one of claims 1-7 has a room temperature yield strength ≥1020MPa, tensile strength ≥1180MPa, elongation ≥20%, and a yield strength ≥220MPa, tensile strength ≥290MPa, and elongation ≥25% at 950℃.

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