A nickel-based superalloy for additive manufacturing and a method of making the same

Abstract

The application discloses a kind of nickel-based superalloy for additive manufacturing and preparation method thereof, it is related to nickel-based superalloy technical field, by alloy powder atomization is screened into first particle size powder and second particle size powder, and respectively in vacuum environment executes degassing treatment, again mixed to form compound printing powder, so that first particle size powder forms main body powder laying structure, so that second particle size powder fills the intergranular gap between first particle size powder, and large-size void and continuous original particle boundary are more difficult to appear in the process of layer-by-layer melting forming of superalloy blank;Second particle size powder fills the intergranular gap between first particle size powder, two types of particle size powder reach the surface state matched with respective particle size before mixing, solve the problem that only from component design or post-forming heat treatment in traditional technology, and the state control of powder into molten pool before is insufficient, different particle size powder oxygen absorption difference and degassing difference are insufficient.

Description

Technical Field

[0001] This invention relates to the field of nickel-based superalloy technology, specifically to a nickel-based superalloy for additive manufacturing and its preparation method. Background Technology

[0002] Nickel-based superalloys have long been used in high-temperature hot-end components such as aero-engines and gas turbines due to their high high-temperature strength, good oxidation resistance, and good structural stability. Additive manufacturing technologies such as laser powder bed melting can realize the integrated near-net-shape forming of complex structural parts, and have therefore gradually become an important preparation route for complex thin-walled parts and high-performance hot-end components made of nickel-based superalloys. However, the additive manufacturing process has extremely high heating and cooling rates, and the molten pool undergoes a cyclic thermal history of rapid melting and rapid solidification, which can easily cause problems such as cracks, pores, uneven microstructure, insufficient precipitation of strengthening phases, or precipitation mismatch, thereby affecting the comprehensive mechanical properties and service reliability of the components.

[0003] A Chinese patent document, CN119525521B, discloses a method for preparing high-strength, high-plasticity additive manufacturing nickel-based superalloys. It clearly states that a multi-scale heterogeneous structure composed of bimodal grains, nano-second phases, and nano-defects is obtained through a solution treatment at 1160℃ to 1200℃ and a two-stage aging heat treatment at 843℃ / 4h + 760℃ / 8h. This method aims to solve the problem of high strength and low plasticity of precipitation-strengthened nickel-based superalloys after heat treatment.

[0004] A Chinese patent document discloses a precipitation-hardening nickel-based superalloy for high-plasticity additive manufacturing and its design and preparation method. The publication number is CN116377286B. It also points out that by balancing the solidification cracking sensitivity, solidification range, strain aging cracking tendency and the volume fraction of strengthening phase under high temperature conditions through composition design, the applicability and plasticity of additive manufacturing can be improved.

[0005] However, the optimization focus of the above two types of technical solutions still mainly lies in the control of the microstructure after forming or the adjustment of the overall alloy composition. Insufficient attention is paid to the state of the powder before it enters the molten pool. Nickel-based superalloy powders for additive manufacturing are prone to oxygen absorption and oxidation during powder preparation, sieving, transportation, storage and degassing. Changes in the surface state of the powder will further affect the quality of melting and bonding and are related to the formation of the original particle boundaries. After the original particle boundaries are formed, they can easily have an adverse effect on the microstructure continuity, mechanical properties and service stability of the component. Summary of the Invention

[0006] To address the shortcomings of traditional technologies, this invention provides a nickel-based superalloy for additive manufacturing and its preparation method, thus solving the problems mentioned in the background art.

[0007] A nickel-based superalloy for additive manufacturing, comprising, by weight percentage: 10% to 18% chromium, 5% to 12% cobalt, 2% to 8% molybdenum, 1% to 6% tungsten, 0.5% to 3% aluminum, 0.5% to 4% titanium, 0.5% to 3% niobium, 0.01% to 0.2% carbon, 0.001% to 0.05% boron, with the balance being nickel and unavoidable impurities; Among them, the nickel-based superalloy for additive manufacturing is in the form of a compound printing powder. The compound printing powder includes a main particle size component and a gap particle size component. The particle size of the main particle size component is 20μm to 38μm, and the particle size of the gap particle size component is 10μm to 20μm.

[0008] Preferably, the mass ratio of the main particle size component to the interstitial particle size component is 70:30 to 90:10.

[0009] A method for preparing a nickel-based superalloy for additive manufacturing includes the following steps: preparing nickel-based superalloy raw materials according to mass percentage and performing vacuum melting to obtain a solution; The solution was atomized under inert gas protection to obtain atomized alloy powder; The atomized alloy powder is sieved into powder of a first particle size and powder of a second particle size. The powder of the first particle size is placed in a first vacuum environment to perform a first degassing treatment, and the powder of the second particle size is placed in a second vacuum environment to perform a second degassing treatment. The first particle size powder that has undergone the first degassing treatment and the second particle size powder that has undergone the second degassing treatment are mixed at a mass ratio of 70:30 to 90:10, and the mixing process is carried out under an inert atmosphere for 10 to 40 minutes to obtain a compound printing powder. The compound printing powder is spread and melted layer by layer in a laser powder bed melting device to obtain a high-temperature alloy billet. The formed high-temperature alloy blanks are subjected to preheating and desorption treatment, stress relief treatment, solution treatment and aging treatment to obtain nickel-based high-temperature alloy components for additive manufacturing.

[0010] Preferably, the first particle size powder is used as the main particle size component in the compound printing powder, and the particle size of the first particle size powder is 20μm to 38μm; The second particle size powder, as a gap-filling particle size component in the compound printing powder, is used to fill the gaps between particles of the first particle size powder, and the particle size of the second particle size powder is 10μm to 20μm.

[0011] Preferably, the first vacuum environment is formed by evacuating the first sealed degassing container loaded with powder of the first particle size, and the second vacuum environment is formed by evacuating the second sealed degassing container loaded with powder of the second particle size. The first sealed degassing container and the second sealed degassing container are set up independently, and the first degassing treatment and the second degassing treatment are respectively carried out in the corresponding sealed degassing container. The temperature of the first degassing treatment is 200°C to 320°C and the time is 1 hour to 4 hours; the temperature of the second degassing treatment is 260°C to 380°C and the time is 2 hours to 8 hours. The vacuum levels of both the first and second vacuum environments are no higher than 50 Pa, and the vacuum level of the second vacuum environment is lower than that of the first vacuum environment.

[0012] Preferably, when the compound printing powder is spread and melted layer by layer to obtain a high-temperature alloy blank, the powder layer thickness is 30μm to 40μm, the laser power is 260W to 340W, the scanning speed is 800mm / s to 1000mm / s, and the overlap rate between adjacent scanning tracks is 25% to 35%. The holding time for the preheating and desorption treatment is 0.5h to 2h, the holding time for the stress relief treatment is 1h to 3h, the holding time for the solution treatment is 1h to 4h, and the holding time for the aging treatment is 4h to 16h. The preheating and desorption treatment, stress relief treatment, solution treatment and aging treatment are carried out in sequence.

[0013] Preferably, after the preheating and desorption treatment is completed, the temperature is directly increased to enter the stress relief treatment. After the stress relief treatment is completed, the temperature is directly increased to enter the solution treatment. After the solution treatment is completed, the high-temperature alloy billet is air-cooled to room temperature, then heated to enter the aging treatment. After the aging treatment is completed, it is air-cooled to room temperature to obtain a nickel-based high-temperature alloy component for additive manufacturing.

[0014] This invention provides a nickel-based superalloy for additive manufacturing and its preparation method, which has the following beneficial effects: 1. By sieving atomized alloy powder into powder of a first particle size and powder of a second particle size, and performing a first degassing treatment and a second degassing treatment in a first vacuum environment and a second vacuum environment respectively, and then mixing them to form a compound printing powder, the powder of the first particle size can form the main powder-spreading structure, and the powder of the second particle size can fill the particle gaps between the powder of the first particle size.

[0015] Therefore, the powder layer is more uniform after the compounded printing powder enters the powder spreading station, and the high-temperature alloy blank is less likely to have large-sized gaps, continuous original particle boundaries and crack initiation positions during the layer-by-layer melting and forming process.

[0016] 2. After the first degassing process, the powder is cooled to below 80°C and then transferred to an inert atmosphere protection container. After the second degassing process, the powder is cooled to below 80°C and then transferred to an inert atmosphere protection container. This can prevent the first and second particle size powders from reabsorbing moisture or re-oxidizing after degassing. As a result, after the two types of powders are mixed at a mass ratio of 80:20, the main particle size composition can be maintained continuously, the interstitial particle size composition can be effectively filled, and the mixed powder is not easy to re-agglomerate, which is more suitable for continuous powder supply and continuous printing.

[0017] 3. By forming a continuous process chain with matching forming parameters, fixed heat treatment sequence, and clear heating and cooling paths, it is possible to stabilize the single-layer powder thickness, single-channel molten pool width, and overlapping area of ​​adjacent channels during the layer-by-layer melting and forming stage. As a result, the temperature transition between preheating and desorption treatment, stress relief treatment, solution treatment, and aging treatment is more stable, and the nickel-based superalloy components used in additive manufacturing are more likely to maintain consistent surface flatness, interlayer continuity, and uniform microstructure after heat treatment. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for preparing nickel-based superalloys. Figure 2 This is a schematic diagram of the graded degassing structure for powders of the first and second particle sizes. Figure 3 This is a flowchart illustrating the process of compound printing powder formation and layer-by-layer melting. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Example 1

[0021] This invention provides a nickel-based superalloy for additive manufacturing. Please refer to [link / reference]. Figure 1 , The nickel-based superalloy comprises, by mass percentage: 14.0% chromium, 8.0% cobalt, 4.5% molybdenum, 3.0% tungsten, 1.5% aluminum, 2.5% titanium, 1.2% niobium, 0.08% carbon, and 0.01% boron, with the balance being nickel and unavoidable impurities; wherein, nickel accounts for 65.21% by mass. Nickel is produced using electrolytic nickel with a purity of not less than 99.9 wt%. Chromium, cobalt, molybdenum, tungsten, aluminum, titanium, and niobium are each produced using metallic raw materials with a purity of not less than 99.5 wt%. Carbon is produced using high-purity graphite, and boron is produced using a nickel-boron master alloy. All raw materials are weighed according to the above-mentioned mass percentages and then added to a vacuum induction melting furnace for melting. The vacuum level inside the furnace is stabilized at 5 × 10⁻⁶. -2 After the temperature drops below Pa, the mixture is heated to melt and held at 1550℃ for 15 minutes to ensure uniform composition, thus obtaining a solution.

[0022] The nickel-based superalloy for additive manufacturing is in the form of a compound printing powder. The compound printing powder includes a main particle size component and a gap particle size component. The particle size of the main particle size component is 35 μm, and the particle size of the gap particle size component is 15 μm.

[0023] The mass ratio of the bulk particle size component to the interstitial particle size component is 80:20. Specifically, the solution is fed into an inert gas atomizing device for atomization and powder production. Argon is used as the atomizing medium, and the atomization pressure is controlled at 5.0 MPa. After atomization, the atomized alloy powder is collected. All the atomized alloy powders come from the same batch and the same composition system. Therefore, the main particle size composition and the interstitial particle size composition are consistent in chemical composition, and there are only differences in particle size range.

[0024] The atomized alloy powder was sieved to obtain a main particle size component with a particle size of 32 μm and a gap-filling particle size component with a particle size of 15 μm. The main particle size component is used to form a continuous main particle accumulation layer during the powder spreading process, and the gap-filling particle size component is used to enter the gaps between the particles of the main particle size component to reduce the proportion of large-size voids inside the powder spreading layer. After sieving, the main particle size component and the gap-filling particle size component are stored in separate sealed containers. The sealed containers are filled with argon gas to reduce the probability of the powder re-absorbing moisture and re-oxidizing after sieving.

[0025] The main particle size component and the interstitial particle size component are mixed at a mass ratio of 80:20. The mixing environment is protected by argon gas, and the mixing equipment is a closed powder mixing device. The mixing time is set to 25 minutes. After mixing, a composite printing powder is obtained. The main particle size component plays the role of spreading the main powder in the composite printing powder, while the interstitial particle size component plays the role of filling and densifying the gaps. The powder after the composite is not sieved again and is directly used for subsequent additive manufacturing.

[0026] The reason for controlling the particle size of the main particle size component at 32μm is that the powder within this particle size range can form a relatively stable main packing structure during the powder spreading process. The reason for controlling the particle size of the interstitial particle size component at 15μm is that the powder within this particle size range can effectively fill the gaps between the main particle size components without excessive aggregation. The reason for controlling the mass ratio of the main particle size component to the interstitial particle size component at 80:20 is that this mass ratio can simultaneously ensure the continuity of the main powder spreading and the interstitial filling and densification capabilities.

[0027] When the prepared compound printing powder is used in a laser powder bed melting device, the main particle size components preferentially form the main contact skeleton of the powder spreading layer, and the interstitial particle size components are distributed in the gap positions between the main particle size components. After the compound printing powder enters the powder spreading station, it can form a more uniform powder layer, providing more stable initial stacking conditions for subsequent layer-by-layer melting and forming.

[0028] In this embodiment, the nickel-based high-temperature alloy for additive manufacturing is obtained by first melting, then atomizing, then sieving and compounding the same composition system. When implementing the process, the personnel must ensure that the main particle size component and the interstitial particle size component are both derived from the same batch of atomized alloy powder, and that the particle size of the main particle size component is 32 μm, the particle size of the interstitial particle size component is 15 μm, and the mass ratio of the main particle size component to the interstitial particle size component is 80:20. Based on this, a compound printing powder that can be directly used for additive manufacturing can be obtained.

[0029] Example 2

[0030] A method for preparing a nickel-based superalloy for additive manufacturing, please refer to [reference needed]. Figure 1 , Figure 2 and Figure 3 Specifically, it includes the following steps: preparing nickel-based high-temperature alloy raw materials according to mass percentages and performing vacuum melting to obtain a solution; The solution was atomized under inert gas protection to obtain atomized alloy powder; The atomized alloy powder is sieved into powder of a first particle size and powder of a second particle size. The powder of the first particle size is placed in a first vacuum environment to perform a first degassing treatment, and the powder of the second particle size is placed in a second vacuum environment to perform a second degassing treatment. The powder of the first particle size after the first degassing treatment and the powder of the second particle size after the second degassing treatment are mixed at a mass ratio of 80:20, and the mixing process is carried out under an inert atmosphere for 25 minutes to obtain a compound printing powder. The compound printing powder is spread and melted layer by layer in a laser powder bed melting device to obtain a high-temperature alloy billet. The formed high-temperature alloy blanks are subjected to preheating and desorption treatment, stress relief treatment, solution treatment and aging treatment to obtain nickel-based high-temperature alloy components for additive manufacturing.

[0031] It should be noted that: The first particle size powder refers to the larger particle size powder obtained by sieving atomized alloy powder. The first particle size powder plays the role of the main powder spreading function in the compound printing powder. When spreading the powder, the first particle size powder preferentially forms a continuous spreading layer and forms a continuous main melting zone during laser scanning. Therefore, the main function of the first particle size powder is not to fill the tiny gaps, but to provide the main volume of the powder spreading layer, the main contact interface, and the main melting basis. The second particle size powder refers to the smaller particle size powder obtained by sieving atomized alloy powder. After the second particle size powder enters the particle gaps between the first particle size powder, it can reduce the void volume between particles, increase the number of local contact points in the powder spreading layer, and reduce the proportion of large-size voids inside the powder spreading layer. Therefore, the main function of the second particle size powder is to fill gaps and compact, rather than replace the first particle size powder to form the main powder spreading layer.

[0032] The first vacuum environment refers to a closed, low-pressure processing space used only for placing powder of the first particle size and implementing the first degassing treatment. The second vacuum environment refers to a closed, low-pressure processing space used only for placing powder of the second particle size and implementing the second degassing treatment. The first vacuum environment and the second vacuum environment are formed by two independently set closed degassing containers. The two closed degassing containers are respectively connected to a vacuum pumping device and a temperature control device. During the processing, powder mixing does not occur, the processing chamber is not shared, and the same batch processing space is not shared. This ensures that the powder of the first particle size and the powder of the second particle size complete the degassing treatment under their respective temperature conditions, vacuum conditions, and holding time conditions.

[0033] The first degassing treatment refers to a desorption process involving a combination of heating, holding, and vacuuming on powder of a first particle size. The purpose of this first degassing treatment is to remove adsorbed water, adsorbed gas, and weakly bound volatile residues from the surface of the powder of the first particle size. The second degassing treatment refers to a desorption process involving a combination of heating, holding, and vacuuming on powder of a second particle size. Because the second particle size powder has a smaller particle size, a larger external surface area per unit mass, and more surface active sites, the adsorption degree on the surface of the second particle size powder is usually higher than that of the first particle size powder. Based on this difference, since the particle size of the second particle size powder is smaller than that of the first particle size powder, the second particle size powder... Under the same quality conditions, the second particle size powder has a larger external surface area. If the second particle size powder is treated with the same temperature, holding time and vacuum degree as the first particle size powder, the adsorbed water, adsorbed gas and weakly bound oxide residues on the surface of the second particle size powder are usually higher than those of the first particle size powder. Therefore, the second degassing treatment adopts a higher treatment temperature, a longer holding time and a lower vacuum degree than the first degassing treatment, so that the difference in powder oxygen content between the second particle size powder and the first particle size powder before mixing is controlled within 60 ppm, and the second particle size powder does not show visible agglomeration after light vibration.

[0034] The oxygen content difference of the powder is controlled within 60 ppm. The criteria for this is that the two types of powder can be directly fed into the powder feeding and spreading stage after mixing without obvious fine powder retention, local accumulation, or fluctuations in scraping resistance. When the oxygen content difference between the second particle size powder after the second degassing treatment and the first particle size powder after the first degassing treatment is higher than 60 ppm, there is still more residue on the surface of the second particle size powder. After mixing, it is easier for it to adhere to the surface of the main particle size component and form local accumulation in the powder feeding port or scraping path. When the difference is controlled within 60 ppm, the surface state of the second particle size powder and the first particle size powder before mixing is similar. After mixing, it is easier to maintain a uniform dispersion state and be directly used for subsequent additive manufacturing.

[0035] Composite printing powder refers to a two-component printing powder obtained by mixing powder of a first particle size after undergoing the first degassing treatment and powder of a second particle size after undergoing the second degassing treatment, according to a set mass ratio. Composite printing powder is not a single particle size powder, nor is it a mixed powder that has not been graded or differentiated. The first particle size powder in the composite printing powder is responsible for forming the main powder spreading structure, and the second particle size powder in the composite printing powder is responsible for filling the gaps between particles. After the above combination, the composite printing powder has good powder spreading continuity, high local packing density and relatively stable melting initiation conditions. Therefore, after the composite printing powder enters the laser powder bed melting equipment, it is easier to form a uniform powder spreading layer and a continuous melting trajectory.

[0036] Preheating and desorption treatment refers to holding the high-temperature alloy billet at 250℃ for 1 hour before stress relief treatment. This allows adsorbed water and gas remaining in the open pores on the surface and near the surface of the high-temperature alloy billet, as well as in the incompletely closed micropores between layers, to be released first. This prevents the residue from escaping at a higher temperature during subsequent stress relief treatment at 780℃, which could lead to an increase in surface pinholes or local pore expansion. Stress relief treatment involves holding the high-temperature alloy billet at 780℃ for 2 hours to reduce residual stress formed during additive manufacturing. Solution treatment involves holding the high-temperature alloy billet at 1150℃ for 2 hours to improve the uneven microstructure and local segregation after forming. Aging treatment involves holding the high-temperature alloy billet at 800℃ for 8 hours after solution treatment to form a stable strengthening phase. Preheating and desorption treatment, stress relief treatment, solution treatment, and aging treatment are performed sequentially.

[0037] The composite printing powder corresponding to the thin-walled structural component of the combustion chamber of an aero-engine was selected as the implementation object. The composite printing powder was divided into Example 1 and three comparative examples. The nickel-based high-temperature alloy raw materials used in each group of composite printing powders had the same composition, and the only difference was the powder pretreatment method.

[0038] In specific implementation, nickel-based high-temperature alloy raw materials are first prepared according to the composition range specified in Example 1, and then melted in a vacuum induction melting furnace. After the vacuum degree in the furnace is stabilized, the temperature is raised to a completely molten state to form a solution. The solution is then sent to an inert gas atomization device for atomization and powdering to obtain atomized alloy powder.

[0039] Subsequently, the atomized alloy powder was sieved to obtain a first-size powder with a particle size of 32 μm and a second-size powder with a particle size of 15 μm. For Example 1, the first-size powder was loaded into a first sealed degassing container and subjected to a first degassing treatment under a first vacuum environment. The first degassing treatment temperature was set to 260°C, the holding time was 2 hours, and the vacuum degree was controlled at 35 Pa. The second-size powder was loaded into a second sealed degassing container and subjected to a second degassing treatment under a second vacuum environment. The second degassing treatment temperature was set to 320°C, the holding time was 4 hours, and the vacuum degree was controlled at 20 Pa. The reason for using a higher temperature, longer time, and lower vacuum degree for the second-size powder is that the second-size powder has a smaller particle size, a larger specific surface area, and more surface adsorption sites per unit mass. After the two types of powders completed their respective degassing treatments, they were mixed in an argon atmosphere at a mass ratio of 80:20 for 25 minutes to obtain a composite printing powder.

[0040] Then, the compound printing powder is introduced into a laser powder bed melting device for powder spreading and layer-by-layer melting and forming. The powder layer thickness is set to 35μm, the laser power is set to 300W, the scanning speed is set to 900mm / s, and the overlap rate of adjacent scanning tracks is set to 30%. Thin-walled compound printing powder with dimensions of 80mm×20mm×1.2mm and corresponding blanks of standard stretched compound printing powder are printed. After forming, the high-temperature alloy blanks are first subjected to preheating and desorption treatment at 250℃ for 1h, then stress relief treatment at 780℃ for 2h, followed by solution treatment at 1150℃ for 2h, and then air-cooled to room temperature after solution treatment.

[0041] Then, an aging treatment of 800℃ for 8 hours was performed, followed by air cooling to room temperature to obtain the compound printing powder of Example 1. Comparative Example 1, based on the compound printing powder of Example 1, did not perform particle size classification, but directly subjected all atomized alloy powder to uniform degassing treatment at 280℃ for 2 hours and 35 Pa before forming.

[0042] Comparative Example 2 was based on the compound printing powder obtained in Example 1, and particle size was classified. However, the first particle size powder and the second particle size powder were both subjected to the same degassing conditions of 260°C, 2h, and 35Pa.

[0043] Comparative Example 3, based on the compound printing powder obtained in Example 1, first mixed the two types of powder with different particle sizes at a mass ratio of 80:20, and then subjected the mixed powder to a uniform degassing treatment at 260°C for 2 hours and 35 Pa.

[0044] Among them, the four groups of compound printing powders all adopted the forming parameters and subsequent heat treatment system of the compound printing powder in Example 1 to ensure that the comparison results only reflect the impact of the differences in powder pretreatment. The results of the comparative experiments are summarized in Table 1. Table 1: Comparison results of Example 2 and Comparative Examples 1-3;

[0045] The four groups of test subjects in the table used the same nickel-based superalloy raw material composition, the same laser powder bed melting equipment, the same powder layer thickness of 35μm, the same laser power of 300W, the same scanning speed of 900mm / s, the same overlap rate of adjacent scanning channels of 30%, and the same subsequent heat treatment regime. The only variable was set in the powder pretreatment stage.

[0046] In Example 2, the process involves first sieving to obtain powders of the first and second particle sizes, then degassing them separately, and finally mixing them at a mass ratio of 80:20. Comparative Example 1 adopts a process path of non-grading of all atomized powder and uniform degassing; Comparative Example 2 uses a process path that first classifies the powders, but uses the same degassing conditions for both types of powders; Comparative Example 3 adopts a process path of mixing first and then uniform degassing; The oxygen content of the powder directly reflects the level of adsorbed oxygen and oxidized residue on the powder surface after degassing. Example 2 has 185 ppm, Comparative Example 1 has 362 ppm, Comparative Example 2 has 298 ppm, and Comparative Example 3 has 321 ppm. This indicates that the two types of powder in Example 2 have reached a low residual state before mixing. However, Comparative Example 1 did not classify the powder, and small-diameter powder and large-diameter powder were treated under the same conditions at the same time, resulting in more residue on the surface of fine powder. Although Comparative Example 2 was classified, the two types of powder were treated at the same temperature, the same holding time, and the same vacuum degree. The small-diameter powder did not receive stronger degassing conditions. Comparative Example 3 was mixed first and then degassed uniformly. The overall powder after mixing could only accept the same treatment conditions. Therefore, Example 2 had the lowest oxygen content before the powder entered the powder spreading station.

[0047] The Hall flow time line reflects the flow resistance of powder as it passes through a standard Hall funnel. Example 2 has a flow time of 15.4 s / 50g, Comparative Example 1 has a flow time of 18.9 s / 50g, Comparative Example 2 has a flow time of 17.1 s / 50g, and Comparative Example 3 has a flow time of 17.8 s / 50g. Example 2 has the lowest value, indicating that the compound printing powder in Example 2 flows more easily during powder application and scraping. This is because in Example 2, the first particle size powder forms the main particle channel, and the amount of the second particle size powder is controlled and its state is more stable, so it will not increase the adhesion between particles due to excessive residue. Comparative Example 1 is not graded, so the powder gradation is uniform and the resistance between particles is relatively large. Although Comparative Examples 2 and 3 have a dual particle size system, the powder surface state is inconsistent, and the flowability is still inferior to Example 2.

[0048] The loose packing density reflects the mass of naturally packed powder in a container of the same volume. Example 2 has a density of 4.71 g / cm³, Comparative Example 1 has a density of 4.32 g / cm³, Comparative Example 2 has a density of 4.49 g / cm³, and Comparative Example 3 has a density of 4.41 g / cm³. Example 2 has the highest density, indicating that the compound printing powder of Example 2 can form a denser particle arrangement when freely packed. Specifically, in terms of process, the first particle size powder with a particle size of 32 μm provides the main packing skeleton, and the second particle size powder with a particle size of 15 μm fills the gaps between the particles in the main skeleton. The surface state of the powder after degassing is more stable and will not form agglomeration due to excessive fine powder residue. Therefore, the initial packing of the powder layer in Example 2 is denser.

[0049] The pore area fraction line reflects the proportion of the pore area in the metallographic cross-section after forming. Example 2 has a pore area fraction of 0.11%, Comparative Example 1 has a pore area fraction of 0.47%, Comparative Example 2 has a pore area fraction of 0.28%, and Comparative Example 3 has a pore area fraction of 0.33%. Example 2 has the lowest pore area fraction, indicating that Example 2 has the least amount of unfilled area after laser melting. This result is consistent with the previous results on loose packing density and flowability. That is, the compound printing powder of Example 2 has established a better initial packing state during the powder spreading stage, so it is easier to form a continuous and dense melt channel after melting. In contrast, the powder spreading layer of Comparative Example 1 has larger pores, the small particle size powder of Comparative Example 2 is not degassed enough, and the surface state of the two particle size powders in Comparative Example 3 is inconsistent due to the mixing and uniform degasing. Therefore, the pore area fraction of all three after forming is higher than that of Example 2.

[0050] The porosity area fraction represents the proportion of the porosity area in the metallographic section of a high-temperature alloy blank after layer-by-layer melting and forming, relative to the total area of ​​the corresponding observation field. Specifically, it is obtained by sampling each group of high-temperature alloy blanks at the same forming position. The sampling position is the middle of the length direction of the composite printing powder, avoiding areas more than 1mm from the edge, and cutting a section perpendicular to the forming direction. The cut composite printing powder is then sequentially inlaid, ground, and polished. Grinding is done with sandpaper ranging from 240 to 2000 grit, and polishing is done with 3μm, 1μm, and 0.05μm diamond polishing agents for fine surface polishing. No corrosion treatment is performed during the porosity area fraction test to avoid corrosion pits being misjudged as pores. Subsequently, the polished section is observed under the same illumination conditions using a metallographic microscope, with the magnification uniformly set to 200x. Ten non-overlapping fields of view are randomly selected within the effective observation area of ​​each composite printing powder. The images of each field of view are imported into image analysis software, and a uniform grayscale threshold is used to binarize and identify the black pore areas. False defect areas formed by polishing scratches, edge shadows, and non-closed black stripes are removed. The porosity area fraction of the compound printing powder is obtained by dividing the sum of the areas of all identified pore regions within 10 fields of view by the total area of ​​the 10 fields of view, and then multiplying by 100%. At least 3 high-temperature alloy blanks are tested for each group of compound printing powders, and the average value is taken as the porosity area fraction result for that group. When identifying pore regions, the images of each field of view are first converted into 8-bit grayscale images, and then 5 locations are selected from the metallographic images of the same batch of compound printing powders. The average grayscale value of the clearly defined pore region and the five non-pore matrix regions were measured. The median grayscale value of the pore region and the matrix region was used as the uniform grayscale threshold for this batch of compound printing powder. Then, closed regions with grayscale values ​​lower than the grayscale threshold were identified as pore regions, and regions with grayscale values ​​higher than the grayscale threshold were identified as matrix regions. At the same time, polishing scratches with a length significantly greater than the width and isolated black noise with an area less than 5 μm² were removed to avoid misjudging sample preparation defects as pores.

[0051] The row showing the average continuous length of the original particle boundaries reflects the length of the continuous interface remaining along the original powder particle boundaries after forming. Example 2 has a length of 7.6 μm, Comparative Example 1 has a length of 23.8 μm, Comparative Example 2 has a length of 14.9 μm, and Comparative Example 3 has a length of 18.2 μm. Example 2 has the shortest length, indicating that the metallurgical bonding between particles in Example 2 is more complete and there are fewer continuous weak interfaces. This result is directly related to the separate degassing treatment, because the adsorption residues corresponding to their respective particle sizes have been removed before mixing of the first and second particle sizes, resulting in a more consistent particle surface state. After laser melting, the particle boundary positions are more easily fused. Comparative Examples 1, 2, and 3 all have the problem of insufficient matching of powder surface states, so the average continuous length of the original particle boundaries is significantly greater than that of Example 2.

[0052] The average continuous length of the original particle boundary is used to represent the average length of the continuous interface segment still retained at the outer contour position of the original powder particles after the high-temperature alloy blank is formed. Specifically, it is obtained by sampling each group of high-temperature alloy blanks at the same forming position. The sampling position is consistent with the pore area fraction test position, specifically the middle of the length direction of the compound printing powder, avoiding areas more than 1 mm from the edge, and cutting a section perpendicular to the forming direction. The cut compound printing powder is then sequentially inlaid, ground, and polished. Grinding is done with sandpaper ranging from 240 to 2000 grit, and polishing is done with 3μm, 1μm, and 0.05μm polishing media for fine surface polishing. After polishing, a scanning electron microscope with a backscattered mode is used. The observation was conducted using a uniform magnification of 1000x. Ten non-overlapping fields of view were randomly selected within the effective observation area of ​​each compound printing powder. In each field of view, interface segments distributed along the outer contour of the original powder particles and exhibiting continuous bright-dark contrast in the backscattered image were identified. The length of each continuous interface segment was taken as a measurement value. The lengths of all continuous interface segments in the field of view were measured, summed, and then divided by the number of continuous interface segments in the field of view to obtain the average continuous length of the original particle boundary of the field of view. The average value of the 10 fields of view was taken as the average continuous length of the original particle boundary of each compound printing powder. At least three high-temperature alloy blanks were tested for each group of compound printing powders, and the average value was taken as the result of the group.

[0053] When identifying the original particle boundaries, only interface segments that simultaneously meet the following conditions are included in the statistics: the interface segment is located at the outer edge of the original powder particle, the interface direction is consistent with the outline of the original powder particle, there is continuous light and dark contrast on both sides of the interface, and the length of a single continuous interface segment is not less than 2μm. Ordinary grain boundaries, polishing scratches, isolated corrosion marks, discontinuous light and dark spots, and discrete interface segments with a length of less than 2μm located inside the molten pool are not included in the statistics. The length of continuous interface segments is measured by drawing segments along the center line of the interface using image analysis software and automatically accumulating the length to ensure that each group of compounded printing powders uses the same judgment conditions and the same statistical caliber.

[0054] The line showing the total crack length density reflects the cumulative total length of visible cracks per unit area of ​​the compound printing powder; in Example 2, it is 0.18 mm·mm. -2 Comparative Example 1 has a diameter of 0.91 mm·mm. -2 Comparative Example 2 has a diameter of 0.42 mm·mm. -2 Comparative Example 3 is 0.57 mm·mm -2 Example 2 showed the lowest values, indicating that Example 2 was least likely to generate crack initiation sites and crack propagation channels during the forming process. This result was not solely due to subsequent heat treatment, as the four sets of compound printing powders had the same subsequent heat treatment regime. The differences mainly came from the powder state at the front end and the forming quality. In other words, Example 2 had a denser powder layer, a shorter continuous length of the original particle boundary, and a lower pore area fraction, thus significantly weakening the conditions for crack initiation.

[0055] The total crack length density represents the cumulative value of all visible crack lengths within a unit observation area after the high-temperature alloy blank is formed. Specifically, it is obtained by sampling each group of high-temperature alloy blanks at the same forming location. The sampling location is consistent with the test location for pore area fraction and average continuous length of the original particle boundary; all samples are taken from a cross-section perpendicular to the forming direction, in the middle of the length direction of the compound printing powder and avoiding areas more than 1 mm from the edges. The cut compound printing powder is then sequentially inlaid, ground, and polished. Grinding is performed using sandpaper ranging from 240 to 2000 grit, and polishing is done using 3μm, 1μm, and 0.05μm polishing media. Fine polishing; after polishing, the cross-section is observed using a metallographic microscope or scanning electron microscope, with the magnification uniformly set to 500x. Ten non-overlapping fields of view are randomly selected within the effective observation area of ​​each compound printing powder. The images of each field of view are imported into image analysis software, and the center lines of all visible cracks in the field of view are drawn one by one and the lengths are accumulated. The total crack length density of the field of view is obtained by dividing the sum of the lengths of all cracks in the field of view by the area of ​​the field of view. The average value of the 10 fields of view is used as the total crack length density of the compound printing powder. At least three high-temperature alloy blanks are tested for each group of compound printing powders, and the average value is taken as the result of the group.

[0056] During crack identification, only defects that simultaneously meet the following conditions are included in the statistics: the defect is a slender, open or closed linear defect that extends continuously along the interior of the material, with its length significantly greater than its width, and the length of a single crack is not less than 5 μm; pore edge shadows, polishing scratches, corrosion marks, bright-dark contrast bands at particle boundaries, and discrete black fine lines with a length less than 5 μm are not included in the crack statistics; when a crack branches in the image, the total crack length of the field of view is calculated by summing the centerline lengths of each continuous branch; the unit for the total crack length density is mm·mm. -2 This means that the numerator is the sum of all crack lengths within the field of view, and the denominator is the area of ​​the corresponding field of view, to ensure that each group of compound printing powders uses the same judgment conditions, the same measurement methods, and the same statistical caliber.

[0057] The relative density row reflects the overall compactness of the component. Example 2 has a density of 99.76%, Comparative Example 1 has a density of 98.94%, Comparative Example 2 has a density of 99.38%, and Comparative Example 3 has a density of 99.21%. Example 2 has the highest density, which shows that the front-end process of grading, separate degassing and compounding in Example 2 has transferred its advantages to the final component. Although Comparative Example 2 also performed grading, its density was still lower than that of Example 2 because the two types of powders did not use differentiated degassing conditions. Although Comparative Example 3 also compounded dual-particle-size powders, the final component density did not reach the level of Example 2 because it was mixed first and then degassed uniformly.

[0058] The relative density is used to represent the ratio between the actual density and the theoretical density of a high-temperature alloy blank or a nickel-based high-temperature alloy component for additive manufacturing. Specifically, it is obtained by sampling each group of high-temperature alloy blanks at the same forming location. The sampling location is the middle of the length of the composite printing powder, avoiding areas more than 1 mm from the edges. These are then processed into composite printing powders of the same size for density testing. Before testing, the surface of the composite printing powder is cleaned of adhering powder, oil, and oxidation residues, and the outer surface of the composite printing powder is dried. Subsequently, the actual density of the composite printing powder is determined using the Archimedes' water displacement method. First, weigh the mass of the compound printing powder in air, then weigh the apparent mass of the compound printing powder in deionized water. Calculate the actual density of the compound printing powder based on the mass in air, the apparent mass in deionized water, and the density of deionized water at the test temperature. The theoretical density is calculated according to the mass percentage of each element in the nickel-based high-temperature alloy and the corresponding elemental density using the mixing rule. Divide the actual density of the compound printing powder by the theoretical density, then multiply by 100% to obtain the relative density of the compound printing powder. Test at least three high-temperature alloy blanks for each group of compound printing powders, and take the average value as the relative density result for that group.

[0059] When conducting actual density measurements, the compound printing powder is first surface-wetted before immersion in deionized water, and vacuuming is used to remove air bubbles adhering to the surface of the compound printing powder to avoid affecting the apparent quality in water. Each piece of compound printing powder is measured three times. If the maximum deviation of the three measurements is not higher than 0.05%, the average value is taken as the actual density result of the compound printing powder. If the maximum deviation is higher than 0.05%, the compound printing powder is cleaned and measured again. When calculating the theoretical density, the mass percentage of each element is based on the actual ratio of the nickel-based high-temperature alloy raw material used in the corresponding compound printing powder to ensure that the relative density calculation benchmark is consistent with the composition of the compound printing powder.

[0060] The row for room temperature tensile strength and the row for elongation after fracture directly reflect the load-bearing capacity and plasticity level of the component. The room temperature tensile strength of Example 2 is 1286 MPa, compared to 1168 MPa for Comparative Example 1, 1229 MPa for Comparative Example 2, and 1208 MPa for Comparative Example 3. The elongation after fracture of Example 2 is 15.8%, compared to 8.7% for Comparative Example 1, 12.4% for Comparative Example 2, and 10.9% for Comparative Example 3. Example 2 achieves both higher strength and higher plasticity, indicating that the porosity, original particle boundaries, and cracks inside the component in Example 2 have been significantly reduced. The component can withstand higher loads under tension and can undergo greater plastic deformation before fracture. Comparative Example 1 has the lowest strength and plasticity at the same time, indicating that the unified degassing scheme cannot guarantee the forming quality. Although Comparative Examples 2 and 3 are improved compared to Comparative Example 1, due to the lack of the key step of degassing separately and then recombining, the strength and plasticity of Comparative Examples 2 have not reached the level of Example 2.

[0061] Finally, by first sieving the atomized alloy powder into powders of a first particle size and powders of a second particle size, and then subjecting the powders of the first and second particle sizes to degassing treatments of different intensities, and finally mixing them at a mass ratio of 80:20 to form a composite printing powder, if any of these steps are canceled or changed, the powder oxygen content, Hall flow time, loose packing density, pore area fraction, average continuous length of the original particle boundary, total crack length density, relative compaction, room temperature tensile strength, and elongation after fracture in the table will all approach the data of Comparative Example 1, Comparative Example 2, or Comparative Example 3. Therefore, each row of data in the table can illustrate that under the process conditions feasible by this solution, lower powder residue, higher powder spreading quality, fewer forming defects, and better overall component performance can be achieved.

[0062] In this embodiment, the atomized alloy powder is first sieved into powder of a first particle size and powder of a second particle size. Then, a first degassing treatment and a second degassing treatment are performed in a first vacuum environment and a second vacuum environment, respectively. Subsequently, the first particle size powder that has undergone the first degassing treatment and the second particle size powder that has undergone the second degassing treatment are mixed to form a composite printing powder. After obtaining the high-temperature alloy blank, preheating desorption treatment, stress relief treatment, solution treatment, and aging treatment are further performed. This process ensures that the first particle size powder forms the main powder-spreading structure, the second particle size powder fills the interparticle gaps between the first particle size powders, and that the two types of powders achieve a surface finish that matches their respective particle size characteristics before mixing. The surface state of the powder directly solves the problems of traditional technologies that only focus on composition design or post-forming heat treatment, while neglecting the insufficient control of the powder's state before it enters the molten pool, the insufficient consideration of differences in oxygen absorption and degassing of powders with different particle sizes, and the lack of front-end control schemes that focus on suppressing the original particle boundaries. Specifically, after the compounded printing powder enters the powder spreading station, it can form a more uniform powder spreading layer. During the layer-by-layer melting and forming process of the high-temperature alloy blank, it is less likely to have large-sized voids, continuous original particle boundaries, and crack initiation positions. The final nickel-based high-temperature alloy components for additive manufacturing are more likely to maintain consistency in terms of density, microstructure continuity, and subsequent load-bearing stability.

[0063] Example 3

[0064] Specifically: Based on Example 1, this embodiment further specifies the sieving of atomized alloy powder in the preparation process of compound printing powder in Example 1. First, the atomized alloy powder obtained from the same batch of atomization is sieved to obtain powder with a first particle size and powder with a second particle size. The particle size of the first particle size powder is controlled to be 32 μm, and the particle size of the second particle size powder is controlled to be 15 μm.

[0065] The first particle size powder is used as the main particle size component in the compound printing powder. During the powder spreading process, the first particle size powder preferentially forms a continuous main particle accumulation layer, which is used to establish the main volume and main contact foundation of the powder spreading layer.

[0066] The second particle size powder is used as a gap-filling particle size component in the compound printing powder. After the second particle size powder enters the particle gap between the first particle size powder, it is used to reduce the void volume between the main particles and increase the local packing density of the powder layer.

[0067] The particle size of the first-size powder is controlled at 32 μm because powders within this size range can form a continuous bulk particle stacking structure during the powder spreading process and form a continuous bulk melting zone during subsequent laser scanning. When the particle size of the first-size powder is less than 20 μm, the proportion of fine powder increases, the adhesion between powders is enhanced, and the powder spreading fluidity decreases. When the particle size of the first-size powder is greater than 38 μm, the gaps between the bulk particles increase, and the uniformity of the powder spreading layer decreases.

[0068] The particle size of the second-size powder is controlled at 15 μm because powder within this size range can enter the interparticle gaps between the first-size powder, thereby increasing the local packing density of the powder layer. When the particle size of the second-size powder is less than 10 μm, the powder specific surface area is too large, surface adsorption is enhanced, and the tendency to agglomerate increases. When the particle size of the second-size powder is greater than 20 μm, the ability of the second-size powder to enter the interparticle gaps between the first-size powder decreases, and the gap-filling effect is weakened.

[0069] After sieving, the powder of the first particle size and the powder of the second particle size do not enter the same degassing space, but instead enter the first and second sealed degassing containers, which are set up independently. The first vacuum environment is formed by evacuating the first sealed degassing container containing the powder of the first particle size, and the second vacuum environment is formed by evacuating the second sealed degassing container containing the powder of the second particle size.

[0070] The first and second sealed degassing containers are respectively connected to independent vacuum pumping pipelines and independent temperature control devices. The first degassing process is only performed on powders of the first particle size, and the second degassing process is only performed on powders of the second particle size. During the entire degassing process, the powders of the first and second particle sizes do not mix.

[0071] The temperature of the first degassing treatment is set at 260℃, the holding time is set at 2h, the vacuum degree of the first vacuum environment is controlled at 35Pa, and during the first degassing treatment, the powder of the first particle size is evenly spread in the first sealed degassing container, and the spreading thickness is controlled below 15mm to ensure the consistency of heat transfer and gas desorption inside the container.

[0072] The temperature of the second degassing treatment is set at 320℃, the holding time is set at 4h, the vacuum degree of the second vacuum environment is controlled at 20Pa, and during the second degassing treatment, the second particle size powder is evenly spread in the second sealed degassing container, and the spreading thickness is controlled to be less than 10mm, so as to reduce the uneven desorption caused by excessive local accumulation of fine particle size powder.

[0073] The vacuum level of the second vacuum environment is lower than that of the first vacuum environment, the temperature of the second degassing treatment is higher than that of the first degassing treatment, and the holding time of the second degassing treatment is longer than that of the first degassing treatment. This is because the second particle size powder has a smaller particle size, a larger external surface area per unit mass, and more surface adsorption sites. Therefore, the second particle size powder needs to adopt stronger degassing conditions to reduce surface residue.

[0074] After the first degassing process is completed, the powder of the first particle size is cooled to below 80°C in the first sealed degassing container and then transferred to an inert atmosphere protection container. After the second degassing process is completed, the powder of the second particle size is cooled to below 80°C in the second sealed degassing container and then transferred to an inert atmosphere protection container. Neither type of powder is exposed to the air environment during the cooling and transfer process.

[0075] The first particle size powder that has undergone the first degassing treatment and the second particle size powder that has undergone the second degassing treatment are put into a closed mixing device at a mass ratio of 80:20 and mixed for 25 minutes under an argon atmosphere to obtain a compound printing powder, wherein the first particle size powder forms the main particle size component and the second particle size powder forms the interstitial particle size component.

[0076] The mass ratio of 80:20 is adopted because at this mass ratio, the bulk structure formed by the first particle size powder can remain continuous, and the second particle size powder can enter the gaps between the main particles and form effective filling. When the proportion of the second particle size powder is less than 20 parts by mass, the gap filling effect is weakened. When the proportion of the second particle size powder is more than 30 parts by mass, the proportion of fine powder increases, the adhesion between powders is enhanced, and the uniformity of powder spreading decreases.

[0077] After the printing powder is mixed, it is directly introduced into the powder supply system of the laser powder bed melting equipment. The powder layer thickness is set to 35μm, the laser power is set to 300W, the scanning speed is set to 900mm / s, and the overlap rate between adjacent scanning channels is set to 30%. High-temperature alloy blanks are obtained by layer-by-layer powder spreading and layer-by-layer melting.

[0078] The formed high-temperature alloy blank is first subjected to preheating and desorption treatment at 250℃ for 1 hour, then stress relief treatment at 780℃ for 2 hours, followed by solution treatment at 1150℃ for 2 hours. After the solution treatment, it is air-cooled to room temperature, and then aged at 800℃ for 8 hours. After the aging treatment, it is air-cooled to room temperature to obtain nickel-based high-temperature alloy components for additive manufacturing.

[0079] Preheating and desorption treatment is used to release the weakly bound volatile components remaining in the surface and near-surface pores of the high-temperature alloy blank. Stress relief treatment is used to reduce the residual stress formed by additive manufacturing. Solution treatment is used to promote the homogenization of the microstructure. Aging treatment is used to form a stable strengthening phase. After the four-stage treatment is carried out in sequence, the advantages formed by the front-end powder treatment can be maintained until the final component stage.

[0080] By using a first particle size powder with a particle size of 32μm as the main particle size component and a second particle size powder with a particle size of 15μm as the interstitial particle size component, and by performing the first degassing treatment and the second degassing treatment in a first vacuum environment and a second vacuum environment that are independent of each other, the first particle size powder and the second particle size powder maintain a low residual surface state after degassing treatment before mixing, and no visible agglomeration occurs before mixing. Thus, the main powder spreading and particle interstitial filling are achieved simultaneously in the compound printing powder.

[0081] In actual implementation, it is necessary to ensure that the first-size powder and the second-size powder come from the same batch of atomized alloy powder, and that the particle size of the first-size powder is 32μm, the particle size of the second-size powder is 15μm, the first degassing treatment and the second degassing treatment are carried out in the first and second sealed degassing containers that are set up independently, and the intensity of the second degassing treatment is higher than that of the first degassing treatment. Then, the preparation of the compound printing powder and subsequent additive manufacturing can be completed according to this embodiment.

[0082] In this embodiment, the atomized alloy powder from the same batch is first sieved into powder of a first particle size and powder of a second particle size. Then, a first vacuum environment and a second vacuum environment are formed in independently set first and second sealed degassing containers, respectively, and first and second degassing treatments are performed. This ensures that the first particle size powder maintains continuous particle packing capacity as the main particle size component, while the second particle size powder enters the interparticle gaps between the first particle size powder as a gap-filling component. Furthermore, by cooling the powder to below 80°C after the first degassing treatment and then transferring it to an inert atmosphere protection container, and by cooling the powder to below 80°C after the second degassing treatment and then transferring it to an inert atmosphere protection container, the two types of powder are prevented from reabsorbing moisture or re-oxidizing after degassing. Therefore, the effect achieved is not only a more uniform powder layer, but also the ability to form the first particle size before the compound printing powder is even formed. The first and second particle sizes of the powder are stabilized in a surface state suitable for subsequent mixing and powder supply. After mixing at a mass ratio of 80:20, the main particle size components remain continuous, the interstitial particle size components are effectively filled, and the mixed powder is not prone to re-agglomeration. This advantage is more obvious in actual continuous production scenarios. For example, when the same batch of compound printing powder is continuously used for printing multiple thin-walled compound printing powders for aero-engine combustion chambers or multiple ring-shaped components, the compound printing powder can maintain nearly consistent powder spreading resistance, powder spreading thickness, and melt channel continuity in both the first and last powder supply stages. This reduces the forming differences between components within the same batch due to fluctuations in the powder surface state, making it easier for high-temperature alloy blanks to obtain consistent surface quality, interface bonding state, and final component stability after subsequent preheating and desorption treatment, stress relief treatment, solution treatment, and aging treatment.

[0083] Example 4

[0084] Specifically: Based on the compound printing powder in Example 1, this embodiment further specifies the powder spreading and layer-by-layer melting and forming conditions, as well as the subsequent heat treatment conditions of the high-temperature alloy blank. After the compound printing powder enters the laser powder bed melting equipment, the powder layer thickness is controlled to be 35μm, the laser power is controlled to be 300W, the scanning speed is controlled to be 900mm / s, and the overlap rate between adjacent scanning tracks is controlled to be 30%. The powder is spread and melted layer by layer according to the above parameters to obtain the high-temperature alloy blank.

[0085] The powder layer thickness is controlled at 35μm to ensure that the compound printing powder meets the requirements of layer thickness continuity and in-layer packing density when spreading a single layer. When the powder layer thickness is less than 30μm, the amount of powder in a single layer is insufficient, and local discontinuities and thin areas are prone to occur during the powder spreading process, and the forming efficiency is also significantly reduced. When the powder layer thickness is greater than 40μm, the amount of powder in a single layer increases, and incompletely melted areas are more likely to occur in the layer after laser treatment, and the uniformity of bonding between adjacent layers decreases.

[0086] The laser power is controlled at 300W to ensure that the compound printing powder forms a continuous molten pool during single-pass scanning. When the laser power is below 260W, the compound printing powder composed of the main particle size component and the interstitial particle size component cannot be stably melted, and the bottom and edge of the molten pool are prone to leaving insufficiently melted areas. When the laser power is above 340W, the molten pool temperature is too high, local evaporation is enhanced, the molten pool boundary fluctuations increase, and the formed surface is more prone to irregular undulations.

[0087] The scanning speed is controlled at 900 mm / s to ensure that the laser input energy is matched with the powder layer thickness, laser power, and the stacking state of the compound printing powder. When the scanning speed is lower than 800 mm / s, the heat input per unit length is too high, the residence time of the molten pool increases, and the tendency for local overheating is enhanced. When the scanning speed is higher than 1000 mm / s, the heat input per unit length is too low, the continuity of the molten pool decreases, the single-pass melting width decreases, and insufficient bonding is more likely to occur between adjacent scanning passes.

[0088] The overlap rate between adjacent scanning channels is controlled at 30% to ensure that there is a sufficient overlapping bonding area between adjacent melt channels. When the overlap rate is less than 25%, the overlapping area between adjacent melt channels decreases, and it is easier for unbonded bands to remain between melt channels. When the overlap rate is greater than 35%, the remelting ratio of adjacent melt channels increases, local heat accumulation is enhanced, and the heat-affected zone of the formed surface expands.

[0089] Under the conditions of a powder layer thickness of 35μm, laser power of 300W, scanning speed of 900mm / s, and overlap rate of 30%, the compound printing powder can form a uniform powder layer at the powder spreading station. Under the action of the laser, it can form a continuous melting channel. The surface forming state of the high-temperature alloy blank is stable, and the interlayer bonding is continuous, making it suitable as the initial blank for subsequent heat treatment.

[0090] After the high-temperature alloy billet is formed, it is first subjected to preheating and desorption treatment, then stress relief treatment, followed by solution treatment, and finally aging treatment. The four treatments are carried out in sequence. Under a set of specific implementation conditions, the holding time for preheating and desorption treatment is 1 hour, the holding time for stress relief treatment is 2 hours, the holding time for solution treatment is 2 hours, and the holding time for aging treatment is 8 hours.

[0091] The holding time for preheating and desorption is controlled to 1 hour in order to allow the weakly bound volatile components remaining on the surface and near the surface of the high-temperature alloy billet to be released first at a lower temperature stage. When the holding time is less than 0.5 hours, the preheating and desorption treatment is insufficient, and local gas release may still occur in the subsequent heating stage. When the holding time is more than 2 hours, the preheating stage lasts too long, the process cycle increases, and the release effect is not significantly improved.

[0092] The stress relief treatment holding time is controlled at 2 hours to release the residual stress formed by additive manufacturing. When the holding time is less than 1 hour, the reduction of residual stress is insufficient, and the subsequent high-temperature treatment stage may still retain a high stress level. When the holding time is more than 3 hours, the gain of stress relief treatment on reducing residual stress decreases, while the process time increases significantly.

[0093] The solution treatment holding time is controlled at 2 hours to further homogenize the internal structure of the high-temperature alloy billet and improve some segregation areas. When the holding time is less than 1 hour, the solution treatment is insufficient and the degree of structural homogenization is inadequate. When the holding time is more than 4 hours, the solution treatment duration is too long, the process cycle is increased, and the contribution of further extending the holding time to structural improvement is reduced.

[0094] The holding time for aging treatment is controlled at 8 hours to allow the strengthening phase to precipitate and complete the establishment of the strengthening structure under relatively stable temperature conditions. When the holding time is less than 4 hours, the strengthening phase precipitation is insufficient and the improvement of mechanical properties is limited. When the holding time is more than 16 hours, the aging treatment time is too long, the production cycle is extended, and the further improvement is reduced.

[0095] After the preheating and desorption treatment is completed, no intermediate cooling is performed. Instead, the temperature is directly increased to enter the stress relief treatment. After the stress relief treatment is completed, no intermediate cooling is performed. Instead, the temperature is directly increased to enter the solution treatment. This continuous heating method is used to reduce the temperature fluctuation of the high-temperature alloy billet during the intermediate heating and repeated cooling process, so that the thermal state formed in the previous stage treatment is directly transferred to the next stage treatment.

[0096] After solution treatment, the high-temperature alloy billet is air-cooled to room temperature and then heated to enter the aging treatment. The air-cooling method after solution treatment is to allow the high-temperature alloy billet to drop to room temperature quickly after leaving the solution temperature range, thereby fixing the microstructure after solution treatment and providing a uniform starting condition for subsequent aging treatment.

[0097] After the aging treatment is completed, the entire heat treatment process is ended by air cooling to room temperature. The air cooling method after aging treatment is to end the high-temperature stay after the strengthening phase precipitation is completed and to restore the high-temperature alloy billet to the room temperature state, which is convenient for subsequent performance testing and use.

[0098] By performing the forming conditions of 35μm powder layer thickness, 300W laser power, 900mm / s scanning speed, and 30% overlap rate, and the heat treatment conditions of 1h preheating and desorption treatment, 2h stress relief treatment, 2h solution treatment, and 8h aging treatment, it is possible to obtain nickel-based superalloy components for additive manufacturing with continuous structure, fewer defects, and suitable for subsequent inspection.

[0099] In this embodiment, by stably controlling the powder layer thickness of the compound printing powder at 35μm, the laser power at 300W, the scanning speed at 900mm / s, and the overlap rate between adjacent scanning channels at 30%, and by sequentially performing preheating-desorption treatment, stress relief treatment, solution treatment, and aging treatment after the high-temperature alloy blank is formed, and by directly heating up to stress relief treatment after preheating-desorption treatment, directly heating up to solution treatment after stress relief treatment, air cooling to room temperature after solution treatment, heating up to aging treatment, and air cooling to room temperature after aging treatment, a continuous process chain is formed with matching forming parameters, fixed heat treatment sequence, and a clear heating and cooling path. Therefore, the effect is not only that the high-temperature alloy blank has fewer defects, but also that it can simultaneously stabilize the single-layer powder layer thickness, single-channel melt pool width, and overlapping area of ​​adjacent melt channels during the layer-by-layer melting and forming stage, so that the high-temperature alloy blank has a more uniform interlayer bonding foundation at the end of forming, and subsequent preheating-desorption... By avoiding additional temperature fluctuations and microstructural disturbances caused by repeated cooling during the processing, stress relief treatment, solution treatment, and aging treatment, the microstructure after solution treatment can enter the aging treatment stage under uniform starting conditions. This makes it easier to maintain consistent surface flatness, interlayer continuity, and microstructure uniformity after heat treatment among the same batch of additive manufacturing nickel-based superalloy components. For example, when actually printing thin-walled ring sections of aero-engine combustion chambers or hot-end thin-walled parts with corner transitions, the following combined conditions can be implemented: powder layer thickness of 35μm, laser power of 300W, scanning speed of 900mm / s, overlap rate between adjacent scanning tracks of 30%, and preheating and desorption treatment for 1 hour, stress relief treatment for 2 hours, solution treatment for 2 hours, and aging treatment for 8 hours. This can reduce local melt channel fluctuations caused by heat input fluctuations in thin-walled corner areas, reduce surface state differences in superalloy billets caused by temperature back-and-forth changes before and after solution treatment, and obtain more consistent results for samples at different locations during subsequent testing.

[0100] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended technical solutions and their equivalents.

Claims

1. A nickel-based superalloy for additive manufacturing, characterized in that, Nickel-based superalloys, by mass percentage, comprise: 10% to 18% chromium, 5% to 12% cobalt, 2% to 8% molybdenum, 1% to 6% tungsten, 0.5% to 3% aluminum, 0.5% to 4% titanium, 0.5% to 3% niobium, 0.01% to 0.2% carbon, 0.001% to 0.05% boron, with the balance being nickel and unavoidable impurities; The nickel-based superalloy for additive manufacturing is in the form of a compound printing powder. The compound printing powder includes a main particle size component and a gap-filling particle size component. The particle size of the main particle size component is 20 μm to 38 μm, and the particle size of the gap-filling particle size component is 10 μm to 20 μm.

2. The nickel-based superalloy for additive manufacturing according to claim 1, characterized in that, The mass ratio of the main particle size component to the interstitial particle size component is 70:30 to 90:

10.

3. A method for preparing a nickel-based superalloy for additive manufacturing, based on the nickel-based superalloy according to any one of claims 1-2, characterized in that, Includes the following steps: Nickel-based high-temperature alloy raw materials were prepared according to mass percentages and then vacuum melted to obtain a solution. The solution was atomized under inert gas protection to obtain atomized alloy powder; The atomized alloy powder is sieved into powder of a first particle size and powder of a second particle size. The powder of the first particle size is placed in a first vacuum environment to perform a first degassing treatment, and the powder of the second particle size is placed in a second vacuum environment to perform a second degassing treatment. The first particle size powder that has undergone the first degassing treatment and the second particle size powder that has undergone the second degassing treatment are mixed at a mass ratio of 70:30 to 90:10, and the mixing process is carried out under an inert atmosphere for 10 to 40 minutes to obtain a compound printing powder. The compound printing powder is spread and melted layer by layer in a laser powder bed melting device to obtain a high-temperature alloy billet. The formed high-temperature alloy blanks are subjected to preheating and desorption treatment, stress relief treatment, solution treatment and aging treatment to obtain nickel-based high-temperature alloy components for additive manufacturing.

4. The method for preparing a nickel-based superalloy for additive manufacturing according to claim 3, characterized in that, The first particle size powder serves as the main particle size component in the compound printing powder, and the particle size of the first particle size powder is 20μm to 38μm; The second particle size powder, as a gap-filling particle size component in the compound printing powder, is used to fill the gaps between particles of the first particle size powder, and the particle size of the second particle size powder is 10μm to 20μm.

5. The method for preparing a nickel-based superalloy for additive manufacturing according to claim 4, characterized in that, The first vacuum environment is formed by evacuating the first sealed degassing container loaded with powder of the first particle size, and the second vacuum environment is formed by evacuating the second sealed degassing container loaded with powder of the second particle size. The first sealed degassing container and the second sealed degassing container are set up independently, and the first degassing treatment and the second degassing treatment are carried out in the corresponding sealed degassing containers. The temperature of the first degassing treatment is 200°C to 320°C and the time is 1 hour to 4 hours; the temperature of the second degassing treatment is 260°C to 380°C and the time is 2 hours to 8 hours. The vacuum levels of both the first and second vacuum environments are no higher than 50 Pa, and the vacuum level of the second vacuum environment is lower than that of the first vacuum environment.

6. The method for preparing a nickel-based superalloy for additive manufacturing according to claim 5, characterized in that, in, When spreading and melting the compound printing powder layer by layer to obtain a high-temperature alloy blank, the powder layer thickness is 30μm to 40μm, the laser power is 260W to 340W, the scanning speed is 800mm / s to 1000mm / s, and the overlap rate between adjacent scanning tracks is 25% to 35%. The holding time for the preheating and desorption treatment is 0.5h to 2h, the holding time for the stress relief treatment is 1h to 3h, the holding time for the solution treatment is 1h to 4h, and the holding time for the aging treatment is 4h to 16h. The preheating and desorption treatment, stress relief treatment, solution treatment and aging treatment are carried out in sequence.

7. The method for preparing a nickel-based superalloy for additive manufacturing according to claim 6, characterized in that, After the preheating and desorption treatment is completed, the temperature is directly increased to enter the stress relief treatment. After the stress relief treatment is completed, the temperature is directly increased to enter the solution treatment. After the solution treatment is completed, the high-temperature alloy billet is air-cooled to room temperature, then heated to enter the aging treatment. After the aging treatment is completed, it is air-cooled to room temperature to obtain the nickel-based high-temperature alloy component for additive manufacturing.

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