A method of heat treatment of laser powder bed fusion Mar-M247 alloy

Abstract

The application provides a heat treatment performance optimization method for laser powder bed fusion (LPBF) forming Mar-M247 nickel-based superalloy, and belongs to the technical field of metal material heat treatment. The method aims to solve the technical problem that the existing heat treatment process has poor adaptability and limited performance improvement due to the unique non-equilibrium structure and metallurgical defects of the laser powder bed fusion formed Mar-M247 alloy. The method comprises solid solution treatment and aging treatment of the alloy workpiece; the method comprises: first, internal quality detection is performed on the workpiece; according to the detection result, if there is a defect, path one containing hot isostatic pressing is executed, and if there is no defect, path two is executed. Through the flexible process path, the internal defects can be repaired, the structure can be homogenized, and the strengthening phase can be precisely controlled, so that the high-temperature mechanical properties of the alloy are significantly improved.

Description

Technical Field

[0001] This application relates to the field of heat treatment technology for metallic materials, and in particular to a method for optimizing the heat treatment performance of Mar-M247 nickel-based superalloy formed by laser powder bed melting (LPBF). Background Technology

[0002] Mar-M247 is a precipitation-strengthened nickel-based superalloy widely used in critical hot-end components such as turbine blades for aero-engines due to its excellent high-temperature strength and creep resistance. Laser powder bed melting (LBM), as an advanced additive manufacturing technology, has made it possible to manufacture Mar-M247 alloy components with complex structures. However, the extremely high cooling rate and large temperature gradient of LBM result in Mar-M247 alloys with microstructures and defects that are drastically different from traditional castings or forgings. Specifically, LBM-formed parts commonly exhibit metallurgical defects such as hot cracks and unfused voids caused by high thermal stress; simultaneously, their microstructure displays typical non-equilibrium characteristics, such as columnar crystals growing along the build direction, severe elemental segregation, and chain-like carbides forming at grain boundaries. These defects and inhomogeneous microstructures severely impair the mechanical properties and service reliability of the components.

[0003] In existing technologies, heat treatment processes for Mar-M247 alloys are primarily designed based on their as-cast state or for repair parts damaged after service. For example, some repair processes employ a combination of hot isostatic pressing, solution treatment, and aging treatment to heal voids caused by creep damage. However, these existing processes have significant drawbacks when directly applied to Mar-M247 alloys formed by laser powder bed melting. First, the initial microstructure of the treated parts, i.e., castings or creep-damaged parts, is completely different from the non-equilibrium microstructure of laser powder bed melt-formed parts, resulting in untargeted process parameters. Second, existing processes fail to effectively address the columnar crystal texture and elemental segregation problems unique to laser powder bed melt-formed parts, leading to uneven precipitation of subsequent strengthening phases and limited strengthening effects. For example, some repair processes employ aging treatments lasting more than 8 hours, which may not be optimal for the non-equilibrium microstructure formed by laser powder bed melting and could even lead to undesirable phase coarsening. Therefore, directly applying existing heat treatment processes to Mar-M247 alloy formed by laser powder bed melting cannot synergistically eliminate its internal defects and optimize its microstructure, making it difficult to fully explore the material's performance potential. Summary of the Invention

[0004] This application aims to address the technical problem that existing heat treatment methods cannot adapt to the unique microstructure and defects of laser powder bed fused Mar-M247 alloy, resulting in its high-temperature mechanical properties failing to meet engineering application requirements. Specifically, the purpose of this application is to provide a dedicated heat treatment method that can synergistically eliminate defects such as microcracks and pores inside laser powder bed fused parts, homogenize its non-equilibrium microstructure, and precisely control the precipitation of strengthening phases, thereby significantly improving the overall mechanical properties of the alloy.

[0005] To address the aforementioned technical problems, this application provides a method for optimizing the heat treatment performance of Mar-M247 nickel-based superalloy formed by laser powder bed melting (LPBF), the method comprising the following steps: S1. Perform internal quality inspection on the workpiece of the alloy to determine whether there are microcracks or pore defects inside the workpiece. S2. Based on the detection results of step S1, select one of the following heat treatment paths to execute: Path 1: When the test results show that there are microcracks or pores inside the workpiece, the workpiece is subjected to hot isostatic pressing, solution treatment and aging treatment in sequence. Path 2: When the test results show that there are no microcracks or pores inside the workpiece, the workpiece is subjected to solution treatment and aging treatment in sequence.

[0006] Optionally, in the first path, the process parameters for the hot isostatic pressing treatment are: temperature of 1200-1260℃, pressure of 100-200MPa, and holding time of 2-6 hours.

[0007] Optionally, in the first path: the process parameters for the solution treatment are: temperature of 1240-1280℃ and holding time of 1-4 hours; the process parameters for the aging treatment are: temperature of 850-900℃ and holding time of 2-6 hours.

[0008] Optionally, in path one: The process parameters for the hot isostatic pressing treatment are: temperature 1240℃, pressure 150MPa, and holding time 4 hours. The process parameters for the solution treatment are: temperature 1260℃, holding time 2 hours; The process parameters for the aging treatment are: temperature 870℃ and holding time 2 hours.

[0009] Optionally, in the second path: the process parameters for the solution treatment are: temperature of 1240℃ and holding time of 2 hours; The process parameters for the aging treatment are: temperature of 875℃ and holding time of 20 hours.

[0010] Optionally, in the second path: the process parameters for the solution treatment are: temperature of 1220-1280℃ and holding time of 1-4 hours; The process parameters for the aging treatment are: temperature of 850-900℃ and holding time of 16-24 hours.

[0011] Optionally, the hot isostatic pressing process is performed in an inert gas atmosphere.

[0012] Optionally, the inert gas is high-purity argon.

[0013] Optionally, the heating process of the hot isostatic pressing treatment includes: In the stage where the temperature is below 500℃, the heating rate is 6℃ / min; When the temperature is above 500℃, the heating rate is 10℃ / min.

[0014] Optionally, both the cooling method after the solution treatment and the cooling method after the aging treatment are air cooling.

[0015] Compared with the prior art, this application has the following beneficial effects: This application, by incorporating a hot isostatic pressing (HIP) step, effectively closes microcracks and pores generated during laser powder bed melting, thereby increasing the material density to a high level, fundamentally eliminating defect sources, and enhancing the stability of the microstructure. Simultaneously, this application precisely controls the precipitation of the γ′ strengthening phase through a specific combination of solution and aging parameters, forming a uniformly dispersed strengthened structure. Compared to the deposited state, the high-temperature tensile strength and elongation of the alloy are significantly improved. Furthermore, the solution treatment effectively disperses the chain-like carbides distributed along grain boundaries in the laser powder bed melt microstructure, eliminating brittle fracture pathways. Subsequent aging treatment promotes the precipitation of uniform, dispersed strengthening phases, inhibiting crack initiation and propagation, thus optimizing the material's fracture mechanism.

[0016] Finally, this application provides two technical paths that can be flexibly selected based on the initial quality of the workpiece. For defective workpieces, the path including hot isostatic pressing can maximize performance; for workpieces with adequate density, the path omitting the hot isostatic pressing step can reduce production costs and improve economic efficiency while ensuring significant performance improvement. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic flowchart illustrating a method for optimizing the heat treatment performance of Mar-M247 nickel-based superalloy formed by laser powder bed melting (LPBF) according to an embodiment of this application; Figure 2 This is a schematic diagram comparing the microstructure before and after the processing of technical path one in Embodiment 1 of this application; Figure 3 This is a schematic diagram showing the microstructure before and after the treatment of technical path two in Embodiment 1 of this application. Detailed Implementation

[0019] To better understand the technical solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0020] Example 1: This embodiment provides a heat treatment method for Mar-M247 nickel-based superalloy workpieces formed using laser powder bed melting technology. A key aspect of this method is the selective use of two different process paths based on the initial internal quality state of the workpiece, in order to achieve precise control of the microstructure and optimization of mechanical properties.

[0021] Figure 1 This is a complete flowchart illustrating a heat treatment method provided in an embodiment of this application. Figure 2 This is a schematic diagram comparing the microstructure before and after the treatment of technical path one in Embodiment 1 of this application; wherein, (a) is the OM diagram of the sedimentary state; (b) and (c) are the BSE diagrams of the sedimentary state; (d) is the OM diagram of the heat-treated state; and (e) and (f) are the BSE diagrams of the heat-treated state. Figure 3 This is a schematic diagram comparing the microstructure before and after the treatment of technical path two in Embodiment 1 of this application; where (a) and (b) are BSE diagrams of the sedimentary state; and (c) and (d) are BSE diagrams of the heat-treated state.

[0022] Subsequently, in step S20, defect detection is performed on the workpiece to assess its internal density and determine whether it contains defects such as microcracks or holes that could affect the final performance. In one embodiment of this application, the detection method may employ conventional non-destructive testing techniques in the art, such as X-ray flaw detection or ultrasonic flaw detection. Based on the detection results of step S20, subsequent process flows can be divided into two different technical paths.

[0023] like Figure 1 As shown, the entire process begins in step S10, which involves obtaining the Mar-M247 nickel-based superalloy workpiece prepared by laser powder bed melting. It is understandable that, in its deposited state, this type of workpiece, due to the extremely rapid heating and cooling cycles, typically exhibits typical non-equilibrium microstructure and may contain metallurgical defects caused by thermal stress accumulation. Technical Approach 1: This approach can be used when the detection results in step S20 indicate the presence of obvious microcracks or pores inside the workpiece. For example... Figure 2 (a) shows the low-magnification metallographic structure, schematically illustrating the microstructure of such defective workpieces before processing. The structure contains discontinuous microcracks and irregularly shaped pores, typical defects of laser powder bed melting processes. Further combined with... Figure 2 (b) and Figure 2 The backscattered electron image in (c) reveals that the microstructure also exhibits coarse columnar crystals growing along the grain direction, as well as elemental segregation and inhomogeneous carbides that may be present at grain boundaries or between dendrites. These features collectively lead to poor mechanical properties of the material in the deposited state, particularly poor high-temperature plasticity and toughness.

[0024] For such workpieces, step S30, i.e., hot isostatic pressing (HIP), is performed first. The defective workpiece is placed in a HIP apparatus (e.g., a HIP furnace) and treated under a protective atmosphere to prevent oxidation at high temperatures. As an optional implementation, the protective atmosphere is preferably an inert gas, such as high-purity argon. Before heating, the furnace chamber can be evacuated and repeatedly filled with high-purity argon to ensure the oxygen content inside the furnace is reduced to an extremely low level. Subsequently, the workpiece is heated and pressurized. In this embodiment, a segmented control strategy is used during the heating process to ensure uniform temperature inside and outside the workpiece, avoiding the generation of new thermal stress. Specifically, in the stage below 500°C, the temperature is increased at a slower rate of 6°C / min; when the temperature exceeds 500°C, the temperature is increased at a faster rate of 10°C / min until the target processing temperature is reached. The core process parameters for HIP are set as follows: processing temperature 1240°C, processing pressure 150 MPa, and holding time 4 hours. The 1240℃ temperature setting is designed to induce creep and plastic deformation in the alloy material, while remaining below its solidus temperature to avoid initial melting; the 150 MPa high pressure applies uniform pressure to the workpiece from the outside. Under the combined action of high temperature and high pressure, microcracks and pores inside the workpiece undergo plastic collapse and creep closure, and are effectively healed through metallurgical bonding at the interface via atomic diffusion. Holding at this temperature for 4 hours ensures the full progress of the defect healing process. After the hot isostatic pressing treatment, the workpiece is slowly cooled to room temperature using furnace cooling; this slow cooling rate helps release any residual stress that may have been generated during the process.

[0025] After step S30, the internal defects of the workpiece have been largely eliminated, and the density has been significantly improved. However, its microstructure may still have problems such as uneven composition and unsatisfactory phase distribution, so subsequent solution treatment and aging treatment are required to further optimize the microstructure.

[0026] Accordingly, step S40, i.e., solution treatment, is performed on the workpiece after hot isostatic pressing. The workpiece is transferred into a vacuum or atmosphere-protected heat treatment furnace, heated to 1260°C, and held at this temperature for 2 hours. The purpose of this relatively high solution temperature of 1260°C is to redissolve the uneven γ′ strengthening phase that may precipitate in the deposited microstructure and during hot isostatic pressing into the γ matrix, forming a supersaturated solid solution, thus creating conditions for the uniform precipitation of the strengthening phase during subsequent aging treatment; at the same time, it promotes the diffusion of alloying elements to effectively reduce or eliminate dendritic segregation in the original deposited microstructure; and it disperses and partially dissolves carbides distributed in a chain or network at the grain boundaries, thereby improving the grain boundary structure and eliminating brittle fracture sources. Holding for 2 hours ensures that the above dissolution and diffusion processes are fully carried out. After the solution treatment holding is completed, the workpiece is removed from the furnace and rapidly cooled in air (i.e., air cooling). The faster cooling rate is designed to suppress unwanted phase precipitation during the cooling process, thereby maintaining the single-phase or near-single-phase microstructure at high temperatures to room temperature.

[0027] Subsequently, step S50, i.e., aging treatment, is performed. The workpiece, after solution treatment and air cooling, is placed back into the heat treatment furnace, heated to 870℃, and held at this temperature for 2 hours. Aging treatment is a crucial step for the precipitation of strengthening phases. 870℃ is a typical temperature for the precipitation of the γ′ strengthening phase in Mar-M247 alloy. At this temperature, solute atoms (such as Al, Ti, etc.) in the supersaturated solid solution will precipitate uniformly from the γ matrix in the form of dispersed, fine γ′ phases. The process control of holding at this temperature for 2 hours aims to obtain γ′ phases with nanoscale dimensions, cubic morphology, and coherence with the matrix. These dispersed, fine strengthening phases can effectively pin dislocation movement, thereby greatly improving the high-temperature strength and creep resistance of the alloy. After the aging treatment holding is completed, the workpiece is also cooled to room temperature using air cooling. At this point, the processing flow of technical route one is completed, and a high-performance workpiece is finally obtained in step S80.

[0028] like Figure 2 (d) shows the metallographic structure, which is a schematic diagram of the microstructure after complete processing using the above-described technical approach. Compared to the structure before processing... Figure 2 (a) In contrast, the treated tissue exhibits a completely dense matrix 4, and the original microcracks and pores have disappeared. Further, as... Figure 2 (e) and Figure 2As shown in the high-magnification backscattered electron image (f), the original columnar crystal structure is destroyed, transforming into a more uniform equiaxed crystal or recrystallized structure. Within the dense matrix 4, a large number of fine, uniform precipitates 5 (i.e., the γ′ strengthening phase) are dispersed. This dense, uniform, and effectively strengthened microstructure fundamentally improves the high-temperature mechanical properties of the workpiece. Experimental results show that the tensile strength of the workpiece treated via path one in this embodiment can be increased from approximately 392.3 MPa in the deposited state to 796 MPa at 900°C, an increase of 102.9%, while the elongation also increases from 1.3% to 4%, achieving a synergistic improvement in both strength and plasticity.

[0029] Technical Approach Two: This approach can be adopted when the inspection results of step S20 indicate that the workpiece has high internal density and no macroscopic defects such as microcracks or pores that affect its service performance. In this case, the costly hot isostatic pressing step can be omitted, and the microstructure and properties can be optimized directly through solution treatment and aging, thereby improving production efficiency and economics.

[0030] like Figure 3 (a) and Figure 3 (b) shows a backscattered electron image that schematically illustrates the microstructure of such densely packed workpieces before processing. Although there are no macroscopic defects, the microstructure is still a typical sedimentary microstructure with non-equilibrium characteristics, such as fine dendrites, elemental segregation, and non-uniform phase distribution, which also limits the full realization of material properties.

[0031] For this type of workpiece, after step S20, the process jumps directly to step S60, i.e., solution treatment. The workpiece is placed in a heat treatment furnace, heated to 1240℃, and held for 2 hours. Unlike technical route one, the solution temperature (1240℃) in this route is slightly lower. This temperature is chosen based on a comprehensive consideration of cost and effectiveness; it can still effectively dissolve most of the inhomogeneous γ′ phase in the deposited structure back into the matrix and improve elemental homogeneity, preparing for subsequent aging. After holding at this temperature for 2 hours, the workpiece is rapidly cooled to room temperature using air cooling.

[0032] Next, step S70, i.e., aging treatment, is performed. The solution-treated workpiece is placed back into the heat treatment furnace, heated to 875°C, and subjected to a long aging treatment of up to 20 hours. Unlike the short aging (870°C, 2 hours) in Technical Route 1, this route uses a different aging regime of "875°C, 20 hours". The slightly increased aging temperature (875°C) and significantly extended aging time (20 hours) aim to promote more complete precipitation and growth of the γ′ strengthening phase, forming a distribution of strengthening phase particles with specific size and volume fraction. This long aging treatment is particularly suitable for the microstructure after optimized solution treatment, maximizing the precipitation strengthening potential of the material to obtain excellent high-temperature creep resistance and creep resistance. After the aging treatment is completed, the workpiece is cooled to room temperature using air cooling. At this point, the processing flow of Technical Route 2 is completed, and a high-performance workpiece is finally obtained in step S80.

[0033] like Figure 3 (c) and Figure 3 As shown in (d), it is a schematic diagram of the microstructure after processing using technical path two. Compared with the original state... Figure 3 Compared to the deposited microstructure in (a), the treated microstructure forms a homogenized matrix 7, significantly improving the original dendritic structure and compositional inhomogeneity. Numerous fine and dispersed nanoscale γ′ reinforcing phases precipitate on the homogenized matrix. This microstructure effectively hinders dislocation movement, thereby significantly improving the mechanical properties of the material. Experimental results show that the tensile strength of the workpiece treated via path two in this embodiment can be increased to 707 MPa at 900℃, an increase of approximately 80.3% compared to the deposited state, and the elongation is also improved. This demonstrates that, provided the initial workpiece quality is good, the two-step heat treatment process provided in this application can also achieve excellent performance enhancement and has higher economic efficiency.

[0034] Example 2: This embodiment provides a variation of technical path one, aiming to illustrate that the "hot isostatic pressing + solution treatment + aging" three-step method proposed in this application has good technical effects within a relatively wide range of process parameters.

[0035] Similar to Example 1, a batch of Mar-M247 alloy workpieces with internal defects obtained by laser powder bed melting were first acquired. These workpieces also underwent hot isostatic pressing, solution treatment, and aging treatment sequentially, with the specific process parameters as follows: The process parameters for hot isostatic pressing (HIP) were adjusted to: a processing temperature of 1220°C, a processing pressure of 180 MPa, and a holding time of 3 hours. The process was also carried out under an inert gas atmosphere (such as high-purity argon), and the furnace was cooled after processing. It is understood that the combination of a processing temperature of 1220°C and a processing pressure of 180 MPa differs from the parameters in Example 1 (1240°C, 150 MPa), but it still falls within a range that effectively promotes defect healing. For example, the processing temperature can be selected within the range of 1200-1260°C, and the processing pressure can be selected within the range of 100-200 MPa; a lower temperature can be combined with a higher pressure or a longer holding time to achieve a comparable defect closure effect.

[0036] Subsequently, a solution treatment was performed, with the process parameters adjusted as follows: treatment temperature 1250℃, holding time 3 hours, and air cooling after the holding time. This solution temperature is similar to 1260℃ in Example 1, and it can also achieve the effect of homogenization of the structure, while the slightly extended holding time (3 hours) can more fully promote the diffusion of elements.

[0037] Finally, an aging treatment was performed, with the process parameters adjusted as follows: treatment temperature 880℃, holding time 4 hours, followed by air cooling. Compared with Example 1 (870℃, 2 hours), this aging regime involves a higher temperature and a longer time, which may result in a slight increase in the size of the precipitated γ′ strengthening phase, but it is still within the range of effective strengthening.

[0038] After the heat treatment process described in this embodiment, the test results of the workpiece show that internal defects such as microcracks and pores have been effectively closed, and the density of the microstructure has been significantly improved. Simultaneously, the microstructure has been homogenized, and fine, dispersed reinforcing phases have precipitated. Its high-temperature mechanical properties have also been significantly improved compared to the deposited state, demonstrating that the technical path disclosed in this application has good process robustness and applicability within a certain parameter adjustment range.

[0039] Example 3: This embodiment provides a variation of technical path two, which aims to illustrate that the "solution + aging" two-step method proposed in this application is also effective within a relatively wide range of process parameters.

[0040] First, a batch of Mar-M247 alloy workpieces with adequate internal density and no obvious macroscopic defects were obtained through laser powder bed melting. Subsequently, the workpieces underwent solution treatment and aging treatment sequentially.

[0041] In this embodiment, the process parameters for solution treatment are adjusted as follows: treatment temperature 1250℃, holding time 1.5 hours, and air cooling after holding. It can be understood that the solution temperature can be selected within a reasonable range, such as 1220-1280℃, and the holding time can also be selected within an effective range, such as 1-4 hours. Such a combination can also achieve the purpose of homogenizing the deposited structure.

[0042] Next, aging treatment is performed, with the process parameters adjusted to: treatment temperature 890℃, holding time 16 hours, followed by air cooling. The aging temperature (890℃) and holding time (16 hours) here differ from those in Path 2 of Example 1 (875℃, 20 hours), but both belong to a long-term aging regime. For example, the aging temperature can be selected within the range of 850-900℃, and the aging time can be selected within the range of 16-24 hours. A higher aging temperature (890℃) may accelerate the precipitation and coarsening kinetics of the γ′ phase, and the slightly shortened holding time (16 hours) aims to control the obtaining of a strengthening phase with a specific size distribution and volume fraction to balance high-temperature strength and durability.

[0043] After the heat treatment process described in this embodiment, the microstructure of the workpiece is also significantly optimized, resulting in a uniform matrix and a dispersed reinforcing phase structure. Its high-temperature strength and plasticity are significantly improved compared to the deposited state. This verifies that the second technical path disclosed in this application can achieve effective performance improvement under different combinations of process parameters, demonstrating the flexibility of the process.

[0044] Example 4: This embodiment provides another variation of technical path one, which focuses on exploring the effect of using higher solution temperatures on eliminating the heritability of the melt structure in laser powder bed, and matching it with the corresponding aging process.

[0045] First, a Mar-M247 alloy workpiece with internal defects was obtained by laser powder bed melting.

[0046] The first step is hot isostatic pressing (HIP). This embodiment uses the same HIP process parameters as Example 1, namely, holding at 1240°C, 150 MPa pressure, and a high-purity argon atmosphere for 4 hours, followed by furnace cooling. This step ensures complete healing of internal defects in the workpiece.

[0047] The second step is solution treatment. To more thoroughly eliminate the inherited characteristics of the deposited structure, such as more persistent elemental segregation and coarse grain boundary carbides, this embodiment employs a higher solution temperature. Specific process parameters are: treatment temperature 1275℃, holding time 1.5 hours, followed by air cooling. The 1275℃ temperature is very close to the solidus temperature of the material, maximizing the solubility and diffusion rate of the solute elements, thereby obtaining a more homogeneous solid solution matrix. Shortening the holding time to 1.5 hours is to achieve complete dissolution while avoiding abnormally coarse grains caused by excessively high temperatures and long holding times.

[0048] The third step is aging treatment. Due to the higher solution temperature, the matrix may have a higher degree of supersaturation, therefore the aging process needs to be adjusted accordingly. The aging treatment parameters in this embodiment are: treatment temperature 860℃, holding time 5 hours, followed by air cooling. Choosing a temperature slightly lower than that of Example 1 (860℃) and extending the holding time (5 hours) aims to provide more sufficient nucleation and growth time for the matrix with higher supersaturation, thereby controlling the precipitated γ′ strengthening phase to have an ideal size and distribution, and avoiding uneven precipitated phases or the appearance of other non-ideal phases due to excessive nucleation driving force.

[0049] After the heat treatment process described in this embodiment, the resulting workpiece is not only internally dense and defect-free, but its microstructure uniformity is also further improved. Metallographic observation reveals clearer and cleaner grain boundaries. The final high-temperature mechanical property test results show that the workpiece exhibits excellent strength and toughness matching, proving that the method disclosed in this application can achieve excellent performance improvement effects through synergistic adjustment of parameters over a wider range of solution treatment temperatures.

[0050] In summary, the heat treatment performance optimization method for Mar-M247 nickel-based superalloys formed by laser powder bed melting (LPBF) disclosed in this application optimizes the heat treatment performance of the alloy by selectively setting process paths that include hot isostatic pressing (HIP) and those that do not, and by optimizing and combining the process parameters of solution treatment and aging treatment steps in each path. This method can synergistically repair metallurgical defects, homogenize the microstructure, and precisely control the precipitation of strengthening phases, thereby significantly improving the high-temperature mechanical properties of the alloy material. This provides an effective technical approach to solving the problem of processing such additive manufacturing alloys in the prior art.

[0051] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for optimizing the heat treatment properties of Mar-M247 nickel-based superalloy used in laser powder bed melting forming, the method comprising the following steps: S1. Perform internal quality inspection on the workpiece of the alloy to determine whether there are microcracks or pore defects inside the workpiece. S2. Based on the detection results of step S1, select one of the following heat treatment paths to execute: Path 1: When the test results show that there are microcracks or pores inside the workpiece, the workpiece is subjected to hot isostatic pressing, solution treatment and aging treatment in sequence. Path 2: When the test result shows that there are no microcracks or pores inside the workpiece, the workpiece is subjected to solution treatment and aging treatment in sequence. In the first path: the process parameters for the solution treatment are: temperature 1240-1280℃, holding time 1-4 hours; the process parameters for the aging treatment are: temperature 850-900℃, holding time 2-6 hours. In the second path: the process parameters for the solution treatment are: temperature of 1220-1280℃, and holding time of 1-4 hours; The process parameters for the aging treatment are: temperature of 850-900℃ and holding time of 16-24 hours.

2. The method according to claim 1, characterized in that, In the first path, the process parameters for the hot isostatic pressing treatment are: temperature 1200-1260℃, pressure 100-200MPa, and holding time 2-6 hours.

3. The method according to claim 1, characterized in that, In the first path: The process parameters for the hot isostatic pressing treatment are: temperature 1240℃, pressure 150MPa, and holding time 4 hours. The process parameters for the solution treatment are: temperature 1260℃, holding time 2 hours; The process parameters for the aging treatment are: temperature 870℃ and holding time 2 hours.

4. The method according to claim 1, characterized in that, In the second path: the process parameters for the solution treatment are: temperature 1240℃, holding time 2 hours; The process parameters for the aging treatment are: temperature of 875℃ and holding time of 20 hours.

5. The method according to claim 2, characterized in that, The hot isostatic pressing process is carried out in an inert gas atmosphere.

6. The method according to claim 5, characterized in that, The inert gas is high-purity argon.

7. The method according to claim 2, characterized in that, The heating process of the hot isostatic pressing treatment includes: In the stage where the temperature is below 500℃, the heating rate is 6℃ / min; When the temperature is above 500℃, the heating rate is 10℃ / min.

8. The method according to claim 1, characterized in that, Both the cooling method after the solution treatment and the cooling method after the aging treatment are air cooling.

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