Preparation method of core-shell structure FGH4097 alloy powder and preparation method of metallurgical workpiece

Abstract

The application belongs to the technical field of powder metallurgy high-temperature alloy preparation, and relates to a preparation method of FGH4097 alloy powder with a core-shell structure and a preparation method of metallurgical parts. The preparation method of the FGH4097 alloy powder comprises the following steps: after the FGH4097 bar is lifted to an initial speed, calibration is performed, then the FGH4097 bar is prepared into FGH4097 powder by using a plasma rotating electrode method, and screening is performed to obtain target powder. The preparation method of the metallurgical part comprises the following steps: the target powder is loaded into a package, after pretreatment, vacuum preheating treatment and hot isostatic pressing are sequentially performed, and after the package is removed, a part blank is obtained; then, through heat treatment and finishing, a bicrystal grain powder metallurgical part is prepared. Compared with a part prepared by a traditional process, the metallurgical part prepared by the application has higher tensile strength and high-temperature plasticity, and the synchronous improvement of strength and plasticity is realized.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy high-temperature alloy preparation technology, and relates to a method for preparing core-shell structure FGH4097 alloy powder and a method for preparing metallurgical parts. Background Technology

[0002] Powder metallurgy is a near-net-shape forming technology that uses metal powders as raw materials, and produces parts or materials through pressing, molding, and high-temperature non-melting sintering. This technology can avoid the structural defects caused by traditional casting, forging, and machining processes. FGH4097 high-temperature alloy has excellent high-temperature load-bearing performance and is widely used in critical components under harsh conditions such as turbine disks, turbine baffles, and drum shafts of aero-engines. Currently, this alloy is mainly produced by preparing high-purity alloy powders and combining them with hot isostatic pressing to achieve the integral forming of part blanks.

[0003] However, after FGH4097 high-temperature alloy powder is hot isostatic pressing (HIP) solidification, the grain size of the finished part is usually comparable to that of the original powder particles. Since HIP cannot induce significant plastic deformation, the grain size is difficult to control flexibly. Although HIP has been able to control compositional segregation in components down to the micrometer level, further precise control of grain size and distribution could potentially enable simultaneous improvement in strength and plasticity at service temperatures, resulting in more reliable high-temperature load-bearing components.

[0004] Therefore, there is an urgent need to provide a method for preparing core-shell structured FGH4097 alloy powder and a method for preparing metallurgical parts, so as to obtain a bigrain structure with fine and coarse grains, and achieve a synergistic improvement in the tensile strength and plasticity of the alloy. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art. Firstly, it proposes a method for preparing core-shell structured FGH4097 alloy powder, which yields a core-shell structured FGH4097 alloy powder raw material. Secondly, it provides a method for preparing metallurgical parts by combining the FGH4097 alloy powder raw material with specific powder metallurgy techniques to solidify the alloy powder into a shape, thereby obtaining a part with a bicrystalline structure consisting of fine and coarse grains. The metallurgical parts prepared by this invention exhibit higher tensile strength and high-temperature plasticity compared to parts prepared by traditional processes, achieving a simultaneous improvement in both strength and plasticity.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Firstly, see [the following] Figure 1 As shown, this invention provides a method for preparing core-shell structured FGH4097 alloy powder, comprising the following steps: Step 1: Place the FGH4097 rod of a specific diameter into the pre-treated rotary electrode powder making equipment. After the rotation speed is increased to the initial speed, perform the calibration operation. Step 2: After calibration, the FGH4097 rod is subjected to variable-speed layered melting. The variable-speed layered melting process adopts a plasma rotating electrode process with a rotation speed of 36,000~40,000 r / min, and the rotation speed fluctuates sinusoidally. At the same time, the variable-speed layered melting adopts a plasma gun with an inner and outer dual-nozzle structure. The inner nozzle of the plasma gun has a contraction angle of 25~35°, and the outer nozzle has a contraction angle of 110~140°. After variable-speed layered melting, FGH4097 powder is obtained, which is then sieved according to the target particle size to obtain the target powder.

[0007] Specifically, in step 1, the rotating electrode powder-making equipment is an ultra-high speed plasma rotating electrode powder-making equipment.

[0008] Specifically, in step 1, the pretreatment steps are as follows: first, start the vacuum pump group to evacuate the ultra-high speed plasma rotating electrode powder making equipment to a vacuum, and then fill the equipment with argon gas.

[0009] Specifically, during the powder-making process, the vacuum degree of the ultra-high speed plasma rotating electrode powder-making equipment is ≤1×10⁻⁶. - 3 Pa.

[0010] Specifically, in step 1, the diameter of the FGH4097 bar is preferably 55~60mm.

[0011] Specifically, in step 1, the initial speed is preferably 36000 r / min; the calibration operation is specifically: adjusting the central axis of the plasma gun flame to coincide with the central axis of the FGH4097 rod.

[0012] More specifically, during the process of the FGH4097 bar reaching the initial speed, the rotational speed increases at a rate of 3600 r / min, that is, the target rotational speed of 36000 r / min is reached after 10 minutes; at the same time, when the rotational speed of the FGH4097 bar is higher than 36000 r / min, variable speed layered melting begins.

[0013] Specifically, in step 2, the melting voltage during the variable speed layered melting process is preferably 80V, and the melting current is preferably 1200A; during the melting process, the distance between the melting end face of the FGH4097 bar and the plasma gun is preferably 40mm, and the plasma gun gas pressure is preferably 2.0~2.5bar.

[0014] Specifically, in step 2, the sieving operation is as follows: FGH4097 powder is sieved using a square hole sieve that conforms to national standards, and the particle size of the target powder (i.e., the target particle size) is preferably 53~106μm.

[0015] More specifically, the aperture of the square-hole sieve is equal to the maximum grain size of the target powder's bicrystalline structure.

[0016] Specifically, in step 2, the rotational speed fluctuates sinusoidally around 38000 r / min, with an amplitude of 1000 r / min and a period preferably of 5 min.

[0017] More specifically, the sinusoidal wave runs through the entire smelting process, and the preferred time for the variable-speed stratified smelting is 15 minutes.

[0018] Specifically, in step 2, the plasma gun includes a cathode, an anode, and a gas ring. The plasma gun is used to generate a high-temperature plasma flame. The gas ring of the plasma gun has a double-layer structure, including an inner passage and an outer passage. The inner passage is filled with neon gas, and the outer passage is filled with argon gas.

[0019] Furthermore, the flame temperature of the inner nozzle is 18000~25000K, and the flame temperature of the outer nozzle is 15000~18000K.

[0020] Secondly, see Figure 2 As shown, this invention discloses a method for preparing metallurgical parts. The raw materials used in this method are prepared from the core-shell structure FGH4097 alloy powder described in the first aspect above, and the method includes the following steps: Step 1: The target powder is loaded into a sleeve, pretreated, and then subjected to vacuum preheating and hot isostatic pressing in sequence. The sleeve is then removed to obtain a part blank. Step 2: The part blank is subjected to solution heat treatment and aging heat treatment in sequence, and then precision machining is performed to obtain a bicrystalline powder metallurgy part.

[0021] Specifically, in step 1, the vacuum level inside the enclosure is ≤1×10⁻⁶. -2 Pa.

[0022] Specifically, in step 1, the vacuum preheating treatment is carried out in a vacuum heat treatment device, and the vacuum degree of the vacuum preheating treatment is ≤1×10⁻⁶. -2 Pa.

[0023] Specifically, in step 1, the hot isostatic pressing is used to solidify the target powder into shape.

[0024] Specifically, in step 1, the material of the cover is preferably conventional carbon steel or stainless steel.

[0025] Specifically, in step 1, the removal of the casing is carried out by pickling or machining.

[0026] Specifically, in step 1, the pretreatment includes degassing of the casing, compaction, and casing welding.

[0027] Furthermore, in step 1, the temperature of the vacuum preheating treatment is 800~1000℃, and the holding time is 1~3h.

[0028] Further, in step 1, the hot isostatic pressing process includes a first stage and a second stage; the first stage specifically involves raising the furnace temperature to 900~950℃ and maintaining the pressure at 150~220MPa for 2~4 hours; the second stage specifically involves raising the furnace temperature to 1120~1150℃ and maintaining the pressure at 150~220MPa for 30~50 minutes, followed by cooling.

[0029] Specifically, before the hot isostatic pressing process, the pre-treated package containing the target powder is loaded into the furnace at room temperature.

[0030] Specifically, during the hot isostatic pressing process, the furnace temperature is raised to 900~950℃ using the maximum heating rate allowed by the equipment.

[0031] Specifically, after the first stage of hot isostatic pressing is completed, the furnace temperature is raised to 1120~1150℃ at a rate of 15℃ / min.

[0032] Furthermore, the cooling process specifically involves: first reducing the furnace temperature to 900~1000℃ at a specific rate, and then further cooling the furnace to the equipment's allowable furnace opening temperature.

[0033] Specifically, the preferred rate is 10~20℃ / min.

[0034] Furthermore, in step 2, the solution heat treatment temperature is 15~25℃ below the γ′ phase solution temperature, and the holding time is ≥1h; the aging heat treatment adopts standard aging heat treatment.

[0035] Specifically, after the solution heat treatment is completed, the solution is air-cooled to room temperature and then subjected to standard aging heat treatment.

[0036] Specifically, the standard aging heat treatment process is carried out in accordance with the general aging heat treatment provisions of the High Temperature Alloy Handbook FGH4097.

[0037] More specifically, the standard aging heat treatment is preferably performed by holding at 850°C for 32 hours, followed by air cooling to room temperature.

[0038] Thirdly, the present invention discloses the application of bicrystalline powder metallurgy parts in high-temperature load-bearing components of aero-engines, and the bicrystalline powder metallurgy parts are prepared using a metallurgical part preparation method.

[0039] Compared with the prior art, the present invention has the following beneficial effects: First, in the preparation method of core-shell structure FGH4097 alloy powder, after the rotation speed of the FGH4097 rod is increased to 36000 r / min, the central axis of the plasma gun flame is moved to coincide with the central axis of the FGH4097 rod to complete the calibration. This calibration operation can ensure the stable production of the entire FGH4097 rod during the melting process and ensure the stability of large-scale engineering production. Meanwhile, the gas ring of the plasma gun has a double-layer structure, including an inner layer passage and an outer layer passage. This double-layer structure design can control the theoretical temperature of the inner layer of the plasma flame at 18,000~25,000K and the theoretical temperature of the outer layer at 15,000~18,000K. Thus, during the melting process, the inner and outer rings of the FGH4097 bar end face exhibit layered melting—that is, the area near the center liquefies preferentially, while the area near the edge liquefies with a delay. This helps the particles that liquefy preferentially in the inner ring to wrap around the liquid film of the delayed liquefaction in the outer ring under the action of centrifugal force, forming a stepped cooling phenomenon, and finally forming a high-temperature alloy powder with a core-shell structure.

[0040] Secondly, in the preparation method of core-shell structure FGH4097 alloy powder, within 10 minutes before the start of the plasma rotating electrode melting method, the rotation speed of the FGH4097 bar is increased to the target speed of 36,000 r / min, and then the melting begins. The above operation can ensure that the entire FGH4097 bar is produced at a high speed, thereby improving the utilization rate of FGH4097 bar material in engineering applications. Meanwhile, when using the plasma rotating electrode method for melting, the total melting time is preferably 15 minutes, the rotation speed range during the melting process is 36,000~40,000 r / min, with 38,000 r / min as the fluctuation center and an amplitude of 1,000 r / min for sinusoidal fluctuation, and the melting fluctuation period is 5 minutes. The purpose is to achieve finer particle size of the target powder as the rotation speed increases, based on the production principle of the plasma rotating electrode. Therefore, this invention utilizes a variable rotation speed production process to generate more fine metal liquid films in the 38,000~40,000 r / min stage and more coarse metal liquid films in the 36,000~38,000 r / min stage. Due to the difference in supercooling, the coarse metal powder is further encapsulated within the fine metal powder.

[0041] Third, in step 1 of the metallurgical component preparation method, the carbon steel or stainless steel sheath containing the target powder is placed in a vacuum heat treatment device for vacuum preheating treatment. The vacuum degree of the vacuum heat treatment device should not exceed 1×10⁻⁶. -2 The process involves heating the powder at 800-1000℃ for 1-3 hours under vacuum to prevent oxidation of the carbon steel or stainless steel sheath and to preheat the compacted target powder at 800-1000℃. Furthermore, since a good metallurgical bond cannot be guaranteed for the core-shell structure of all target powders during powder preparation, a vacuum preheating step is included in step 1. This step further sintersulates the powder shell and core at medium temperature, resulting in a tighter metallurgical bond between them. This prevents the shell structure from peeling or severely deforming due to pressure during the first stage of hot isostatic pressing, which would affect the uniformity of subsequent recrystallization distribution.

[0042] Fourth, in step 1 of the metallurgical component preparation method, hot isostatic pressing (HIP) is implemented in two stages. In the first stage, the package containing the target powder is loaded into the furnace at room temperature. The furnace temperature is raised to 900-950℃ using the maximum allowable heating rate of the equipment. Pressure is increased simultaneously during the heating process. Once the temperature reaches the set range, the pressure is simultaneously stabilized at 150-220 MPa, and the pressure is maintained for 2-4 hours. Due to the unique characteristics of the HIP process, a driving force is applied between the powder shells with vacuum gaps, causing significant plastic deformation of the shells to fill the vacuum gaps. The powder core undergoes almost no plastic deformation, resulting in a differentiated stress distribution with high distortion energy in the shells and low distortion energy in the core. The temperature in this stage is limited to 900-950℃: temperatures above 950℃ are prone to premature dynamic recrystallization; temperatures below 900℃ increase the yield strength of the powder shells, requiring a pressure of over 300 MPa to fill the gaps, exceeding the capabilities of conventional HIP equipment. Therefore, a pressure of 150~220MPa was selected to balance material properties and equipment limits. Furthermore, this stage only focuses on the difference in distortion energy and does not pursue complete compactness of the part.

[0043] Due to the pressure limit of the equipment, the second stage maintains a constant pressure of 150-220 MPa throughout, with the temperature increased to 1120-1150℃ at a rate of 15℃ / min, and held at that temperature and pressure for 30-50 minutes. Heating reduces material flow stress, accelerates atomic diffusion, and achieves complete densification of the part blank, while simultaneously forming appropriate dynamic recrystallization in the powder shell. Furthermore, the temperature in the second stage must be controlled within 1120-1150℃; if it deviates from this range, the dynamically recrystallized grains will grow rapidly, damaging the target microstructure and properties of the part blank.

[0044] In addition, after the heat preservation is completed, the cooling rate is first controlled to be between 10~20℃ / min, and then cooled to 900~1000℃. After that, the furnace is cooled to the temperature allowed by the equipment before the part blank is taken out. Specifically, the cooling rate is controlled at this stage in order to obtain the micron-sized γ′ phase, which is in preparation for subsequent heat treatment.

[0045] Fifth, in step 2 of the metallurgical part preparation method, the solution heat treatment is carried out at 15~25℃ below the solution temperature of the γ′ phase. On the one hand, this can reduce the volume fraction of the micron-sized γ′ phase; on the other hand, it can use the micron-sized γ′ phase after hot isostatic pressing to pin the grain boundaries, thereby controlling the growth of fine dynamic recrystallized grains in the shell region and forming a γ-γ′ dual-phase structure in the shell.

[0046] In summary, the acquisition of the core-shell structure FGH4097 alloy powder and the bicrystalline powder metallurgy parts depends strictly on the key steps and process parameters provided by this invention. The absence of any key step or deviation of the process parameters will prevent the achievement of the technical effects of this invention. Attached Figure Description

[0047] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a process flow diagram for preparing the FGH4097 alloy powder raw material of the present invention; Figure 2 This is a process flow diagram of the bicrystalline powder metallurgy parts of the present invention; Figure 3 This is a schematic diagram of the double-layer gas ring structure used in the plasma gun of the present invention; Figure 4 This is a process diagram showing the rotational speed of FGH4097 bars during the plasma melting process of this invention. Figure 5 A secondary electron image of the cross-section of target powder No. 1 prepared in Example 1 of this invention; Figure 6 This is a secondary electron image of the cross-section of target powder No. 4 prepared in Comparative Example 1 of the present invention; Figure 7 This is a secondary electron micrograph of the microstructure of the No. 1 double-grain powder metallurgy part prepared in Example 1 of the present invention; Figure 8 This is a secondary electron micrograph of the microstructure of the No. 4 bicrystalline powder metallurgy part prepared in Comparative Example 1 of the present invention.

[0050] Wherein: 1 is the plasma gun cathode; 2 is a double-layer gas ring; 201 is the inner gas passage; 202 is the outer gas passage. Detailed Implementation

[0051] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0052] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Example 1

[0053] In a first aspect, this embodiment provides a method for preparing core-shell structured FGH4097 alloy powder, comprising the following steps: Step 1: Start the vacuum pump unit to evacuate the ultra-high speed plasma rotating electrode powder making equipment to a vacuum level of 1×10⁻⁶. -3 Pa, then the gas filling device is started to fill the powder making equipment with argon gas in preparation for powder preparation.

[0054] A 55mm diameter FGH4097 rod is placed in the powder-making equipment. The rotation speed of the FGH4097 rod is increased from 3600r / min to 36000r / min. Then, the central axis of the plasma gun flame is adjusted to coincide with the central axis of the FGH4097 rod.

[0055] Step 2: After calibration, see Figure 4 As shown, variable-speed layered melting begins. During the variable-speed layered melting process, the inner nozzle contraction angle of the plasma gun is 25° and the outer nozzle contraction angle is 110°. The plasma melting time is 15 minutes, and the rotation speed during the melting process is 36,000~40,000 r / min. The rotation speed fluctuates sinusoidally around 38,000 r / min with an amplitude of 1,000 r / min and a period preferably of 5 minutes, resulting in No. 1 FGH4097 powder.

[0056] Subsequently, the No. 1 FGH4097 powder was sieved using a square-hole sieve conforming to national standards to obtain the No. 1 target powder, which has a particle size of 53~106μm.

[0057] For details, see Figure 3 As shown, the plasma gun includes a plasma gun cathode 1, an anode, and a double-layer gas ring 2. The plasma gun is used to generate a high-temperature plasma flame. Neon gas is introduced into the inner gas passage 201 of the double-layer gas ring 2, and argon gas is introduced into the outer gas passage 202.

[0058] Specifically, in the process of powder preparation using the plasma rotating electrode method, the melting voltage is 80V, the melting current is 1200A, the distance between the melting end face of the FGH4097 bar and the plasma gun is 40mm, and the plasma gun gas pressure is 2.0bar.

[0059] Secondly, this embodiment provides a method for preparing metallurgical parts, wherein the raw materials used in this method are prepared by the method for preparing the core-shell structure FGH4097 alloy powder, and the method includes the following steps: Step 1: Place the No. 1 target powder in an 8×10⁻⁶ ℃ molten metal. -3 The part is loaded into a carbon steel sleeve under a vacuum of Pa, and the sleeve is degassed, vibrated and welded in sequence. Then, it is subjected to vacuum preheating and hot isostatic pressing in sequence. After the carbon steel sleeve is removed by machining, the part blank is obtained. Specifically, the vacuum degree during the preheating process is 8 × 10⁻⁶. -3 Pa, temperature is 800℃, and the holding time is 1 hour.

[0060] Specifically, the hot isostatic pressing process is as follows: the cladding is placed in a hot isostatic pressing apparatus, and after loading the furnace at room temperature, the furnace temperature is raised to 900°C at the maximum allowable heating rate of the apparatus, while the pressure is maintained at 150 MPa, and the temperature and pressure are maintained for 2 hours; subsequently, the temperature is raised to 1120°C at a rate of 15°C / min, while the pressure is maintained at 150 MPa, and the temperature and pressure are maintained for 30 minutes; after the second stage of hot isostatic pressing is completed, the temperature is cooled to 900°C at a rate of 10°C / min, and then cooled to 400°C with the furnace before being removed from the furnace.

[0061] Step 2: The part blank is subjected to solution heat treatment and standard aging heat treatment in sequence. The solution heat treatment temperature is 1170℃ and the holding time is 1h; the standard aging heat treatment temperature is 850℃ and the holding time is 32h. Then, the part blank is machined to obtain No. 1 double-grain powder metallurgy part.

[0062] Specifically, the solid solution temperature of the γ′ phase is 1190℃. Example 2

[0063] In a first aspect, this embodiment provides a method for preparing core-shell structured FGH4097 alloy powder, comprising the following steps: Step 1: Start the vacuum pump unit to evacuate the ultra-high speed plasma rotating electrode powder making equipment to a vacuum level of 8×10. -4 Pa, then the gas filling device is started to fill the powder making equipment with argon gas in preparation for powder preparation.

[0064] A 58mm diameter FGH4097 rod is placed in the powder-making equipment. The rotation speed of the FGH4097 rod is increased from 3600r / min to 36000r / min. Then, the central axis of the plasma gun flame is adjusted to coincide with the central axis of the FGH4097 rod.

[0065] Step 2: After calibration, variable speed layered melting begins. During the variable speed layered melting process, the inner nozzle contraction angle of the plasma gun is 30° and the outer nozzle contraction angle is 130°. The plasma melting time is 15 minutes, and the rotation speed during melting is 36,000~40,000 r / min. The rotation speed fluctuates sinusoidally around 38,000 r / min with an amplitude of 1,000 r / min and a period preferably of 5 minutes, to obtain No. 2 FGH4097 powder.

[0066] Subsequently, the No. 2 FGH4097 powder was sieved using a square-hole sieve conforming to national standards to obtain the No. 2 target powder, which has a particle size of 53~106μm.

[0067] Specifically, in the process of powder making using the plasma rotating electrode method, the melting voltage is 80V, the melting current is 1200A, the distance between the melting end face of the FGH4097 bar and the plasma gun is 40mm, and the plasma gun gas pressure is 2.5bar.

[0068] Secondly, this embodiment provides a method for preparing metallurgical parts, wherein the raw materials used in this method are prepared by the method for preparing the core-shell structure FGH4097 alloy powder, and the method includes the following steps: Step 1: Place the No. 2 target powder in a 5×10⁻⁶ ℃ environment. -3 The part is loaded into a carbon steel sleeve under a vacuum of Pa, and the sleeve is degassed, vibrated and welded in sequence. Then, it is subjected to vacuum preheating and hot isostatic pressing in sequence. After the carbon steel sleeve is removed by machining, the part blank is obtained. Specifically, the vacuum degree during the preheating process is 5 × 10⁻⁶. -3 Pa, temperature is 900℃, and the holding time is 2h.

[0069] Specifically, the hot isostatic pressing process is as follows: the cladding is placed in a hot isostatic pressing apparatus, and after loading the furnace at room temperature, the furnace temperature is raised to 920°C at the maximum allowable heating rate of the apparatus, and the pressure is maintained at 190 MPa for 3 hours; then, the temperature is raised to 1130°C at a rate of 15°C / min, and the pressure is maintained at 190 MPa for 40 minutes; after the second stage of hot isostatic pressing is completed, the furnace is cooled to 950°C at a rate of 10°C / min, and then cooled to 400°C before being removed from the furnace.

[0070] Step 2: The part blank is subjected to solution heat treatment and standard aging heat treatment in sequence. The solution heat treatment temperature is 1165℃ and the holding time is 1.2h; the standard aging heat treatment temperature is 850℃ and the holding time is 32h. Then, the part blank is machined to obtain No. 2 double grain powder metallurgy part.

[0071] Specifically, the solid solution temperature of the γ′ phase is 1190℃. Example 3

[0072] In a first aspect, this embodiment provides a method for preparing core-shell structured FGH4097 alloy powder, comprising the following steps: Step 1: Start the vacuum pump unit to evacuate the ultra-high speed plasma rotating electrode powder making equipment to a vacuum level of 1×10⁻⁶. -3 Pa, then the gas filling device is started to fill the powder making equipment with argon gas in preparation for powder preparation.

[0073] A 60mm diameter FGH4097 rod is placed in the powder-making equipment. The rotation speed of the FGH4097 rod is increased from 3600r / min to 36000r / min. Then, the central axis of the plasma gun flame is adjusted to coincide with the central axis of the FGH4097 rod.

[0074] Step 2: After calibration, variable speed layered melting begins. During the variable speed layered melting process, the inner nozzle contraction angle of the plasma gun is 35° and the outer nozzle contraction angle is 140°. The plasma melting time is 15 minutes, and the rotation speed during melting is 36,000~40,000 r / min. The rotation speed fluctuates sinusoidally around 38,000 r / min with an amplitude of 1,000 r / min and a period preferably of 5 minutes, to obtain No. 3 FGH4097 powder.

[0075] Subsequently, the No. 3 FGH4097 powder was sieved using a square-hole sieve conforming to national standards to obtain the No. 3 target powder, which has a particle size of 53~106μm.

[0076] Specifically, in the process of powder preparation using the plasma rotating electrode method, the melting voltage is 80V, the melting current is 1200A, the distance between the melting end face of the FGH4097 bar and the plasma gun is 40mm, and the plasma gun gas pressure is 2.0bar.

[0077] Secondly, this embodiment provides a method for preparing metallurgical parts, wherein the raw materials used in this method are prepared by the method for preparing the core-shell structure FGH4097 alloy powder, and the method includes the following steps: Step 1: The No. 3 target powder is heated in a 9×10⁻⁶ environment. -3The part is loaded into a carbon steel sleeve under a vacuum of Pa, and the sleeve is degassed, vibrated and sealed in sequence. Then, it is subjected to vacuum preheating and hot isostatic pressing. After the carbon steel sleeve is removed by pickling, the part blank is obtained. Specifically, the vacuum degree during the preheating process is 9 × 10⁻⁶. -3 Pa, temperature is 1000℃, and the holding time is 3h.

[0078] Specifically, the hot isostatic pressing process is as follows: the cladding is placed in a hot isostatic pressing apparatus, and after loading the furnace at room temperature, the furnace temperature is raised to 950°C at the maximum allowable heating rate of the apparatus, while the pressure is maintained at 220 MPa, and the temperature and pressure are maintained for 4 hours; subsequently, the temperature is raised to 1150°C at a rate of 15°C / min, while the pressure is maintained at 220 MPa, and the temperature and pressure are maintained for 50 minutes; after the second stage of hot isostatic pressing is completed, the furnace is cooled to 1000°C at a rate of 10°C / min, and then cooled to 400°C before being removed from the furnace.

[0079] Step 2: The part blank is subjected to solution heat treatment and standard aging heat treatment in sequence. The solution heat treatment temperature is 1175℃ and the holding time is 1.6h; the standard aging heat treatment temperature is 850℃ and the holding time is 32h. Then, the part blank is machined to obtain No. 3 double grain powder metallurgy part.

[0080] Specifically, the solid solution temperature of the γ′ phase is 1190℃. Comparative Example 1

[0081] In a first aspect, this embodiment provides a method for preparing core-shell structured FGH4097 alloy powder, comprising the following steps: Step 1: Start the vacuum pump unit to evacuate the ultra-high speed plasma rotating electrode powder making equipment to a vacuum level of 1×10⁻⁶. -3 Pa, then the gas filling device is started to fill the powder making equipment with argon gas in preparation for powder preparation.

[0082] Place a 60mm diameter FGH4097 rod in the powder-making equipment. After the rotation speed of the FGH4097 rod is increased to 40,000 r / min, adjust the central axis of the plasma gun flame to coincide with the central axis of the FGH4097 rod to complete the calibration.

[0083] After calibration, plasma melting was performed at a constant speed of 40,000 r / min for 15 min to obtain No. 4 FGH4097 powder.

[0084] After plasma melting is completed, the No. 4 FGH4097 powder is sieved using a square hole sieve to obtain the No. 4 target powder, which has a particle size of 53~106μm.

[0085] Specifically, in step 1, the plasma gun uses a conventional single-layer gas ring.

[0086] Secondly, this comparative example provides a method for preparing metallurgical parts, wherein the raw materials used in this method are prepared by the above-mentioned method for preparing FGH4097 alloy powder, and the method includes the following steps: Step 1: Place the No. 4 target powder in a 5×10⁻⁶ ℃ molten metallurgy furnace. -3 The carbon steel sheath is loaded under vacuum of Pa and then degassed and vibrated for sealing. It is then solidified and formed. The solidification and forming process includes only one hot isostatic pressing. Specifically, the sheath is placed in a hot isostatic pressing equipment, loaded into the furnace at room temperature, and then subjected to one hot isostatic pressing. The first hot isostatic pressing process uses the fastest heating rate within the equipment's capacity to heat to 1200°C, maintains a pressure of 180 MPa, holds the temperature and pressure for 4 hours, and then cools down to 400°C with the furnace before being removed from the furnace.

[0087] Step 2: The carbon steel sheath after consolidation is subjected to a first heat treatment at a temperature of 1200℃ for 4 hours; after air cooling to room temperature, a second heat treatment is performed at a temperature of 870℃ for 32 hours; the carbon steel sheath is then removed by machining to form a part blank, which is then precision machined to finally obtain the No. 4 metallurgical part.

[0088] The difference between Comparative Example 1 and Example 3 is that the gas ring of the plasma gun adopts a conventional single-layer gas ring, and the plasma melting process is produced at a constant speed; at the same time, Comparative Example 1 omits the preheating treatment stage before consolidation and forming, and the consolidation and forming stage only adopts a single hot isostatic pressing process.

[0089] The tensile properties of the metallurgical parts prepared in Examples 1-3 and Comparative Example 1 were tested, and the specific results are shown in Table 1: Table 1 Tensile properties of various metallurgical parts in the examples and comparative examples

[0090] As shown in Table 1, at room temperature, the bicrystalline powder metallurgy parts prepared in Examples 1-3 have better overall strength and plasticity. The yield strength and reduction of area are significantly improved compared with part No. 4 prepared in Comparative Example 1. This indicates that the bicrystalline powder metallurgy parts prepared by the process provided by the present invention can achieve a better strength and toughness match at room temperature.

[0091] At 400℃, the bicrystalline powder metallurgy parts prepared in Examples 1-3 still maintain high strength, and the increase in elongation and reduction of area is the highest in the entire temperature range. This indicates that the present invention can effectively improve the plasticity and toughness of metallurgical parts at medium temperature.

[0092] When the ambient temperature is 650℃, the yield strength of Examples 1 to 3 is still nearly 20% higher than that of Comparative Example 1, and the plasticity index (elongation and reduction of area) is also higher than that of Comparative Example 1. This shows that the synergistic effect between the processes of the present invention can significantly improve the high temperature load-bearing capacity and fracture resistance of FGH4097 alloy.

[0093] In addition, see Figure 5 As shown, the scanning electron microscope (SEM) test parameters are as follows: electron beam acceleration high voltage of 20.00 kV, imaging magnification of 750x, working distance between sample surface and objective lens of 7.9 mm, imaging signal acquisition using secondary electron detector SE2, and image scale bar of 10 μm. Under these observation conditions, it is evident that the target powder No. 1 prepared in Example 1 exhibits a core-shell structure, with differences in supercooling and microstructure between the outer and inner layers. This structure provides a basis for powder shrinkage and deformation during subsequent hot isostatic pressing (HIP) stages and inhibits the growth of fine dynamic recrystallized grains in the outer shell region during subsequent processes, thereby forming a γ-γ′ dual-phase microstructure in the outer shell. See also... Figure 6 As shown, the scanning electron microscope test parameters are as follows: electron beam acceleration high voltage is 20.00kV, imaging magnification is 800x, working distance between sample surface and objective lens is 7.9mm, imaging signal is acquired by secondary electron detector SE2, and image scale bar is 10μm. Under these observation conditions, it can be seen that the No. 4 target powder prepared in Comparative Example 1 is a common spherical powder and does not have a core-shell structure.

[0094] See Figure 7 As shown, this invention effectively achieves a fine-grained + coarse-grained structure in the FGH4097 alloy metallurgical parts, with the fine-grained region forming a γ-γ′ dual-phase structure; while Comparative Example 1 (see Comparative Example 1) Figure 8 The No. 4 metallurgical part obtained (as shown) has a common equiaxed structure with coarse grains. This difference in microstructure directly determines that the mechanical properties of the part of this invention are significantly better than those of the comparative example at both room temperature and high temperature, providing a reliable microstructure guarantee for the high-performance and stable service of alloy parts.

[0095] In summary, the acquisition of the core-shell structure FGH4097 alloy powder and the bicrystalline powder metallurgy part depends strictly on the synergistic effect of the key steps and process parameters provided by this invention. The absence of any key step or deviation of the process parameters will prevent the achievement of the technical effect of this invention. At the same time, the bicrystalline powder metallurgy part obtained by this invention meets the requirements for application in high-temperature load-bearing components of aero-engines.

[0096] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0097] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing core-shell structured FGH4097 alloy powder, characterized in that, Includes the following steps: Step 1: Place the FGH4097 rod with a diameter of 55~60mm into the pre-treated ultra-high speed plasma rotating electrode powder making equipment. After the rotation speed of the ultra-high speed plasma rotating electrode is increased to the initial speed, a calibration operation is performed. The calibration operation is specifically: adjust the central axis of the plasma gun flame to coincide with the central axis of the FGH4097 rod. Step 2: After calibration, the FGH4097 bar is subjected to variable-speed layered melting. This variable-speed layered melting process employs an ultra-high-speed plasma rotating electrode process with a rotation speed of 36,000~40,000 r / min, exhibiting sinusoidal fluctuations. Simultaneously, the variable-speed layered melting utilizes a plasma gun with an inner and outer dual-nozzle structure. The plasma gun includes a cathode, an anode, and a gas ring, and is used to generate a high-temperature plasma flame. The gas ring of the plasma gun has a double-layer structure, including an inner passage and an outer passage. The inner passage is purged with neon gas, and the outer passage with argon gas. The inner nozzle of the plasma gun has a contraction angle of 25~35° and a flame temperature of 18,000~25,000 K, while the outer nozzle has a contraction angle of 110~140° and a flame temperature of 15,000~18,000 K. During the variable-speed layered melting process, the distance between the melting end face of the FGH4097 bar and the plasma gun is 40mm, and the gas pressure of the plasma gun is 2.0~2.5bar; after variable-speed layered melting, FGH4097 powder is obtained, and then it is sieved according to the target particle size to obtain the target powder. During the powder-making process, the vacuum degree of the ultra-high speed plasma rotating electrode powder-making equipment is ≤1×10⁻⁶. -3 Pa; In step 2, the sinusoidal fluctuation of the rotational speed specifically means that the rotational speed fluctuates sinusoidally around 38000 r / min, with an amplitude of 1000 r / min and a period of 5 min.

2. A method for preparing a metallurgical component, characterized in that, The raw materials used in this method are prepared by the method for preparing core-shell structure FGH4097 alloy powder as described in claim 1, and include the following steps: Step 1: The target powder is loaded into a casing, pretreated, and then subjected to vacuum preheating and hot isostatic pressing in sequence. The casing is then removed to obtain a part blank. The vacuum preheating temperature is 800~1000℃, and the holding time is 1~3h. The hot isostatic pressing process is as follows: first, the furnace temperature is raised to 900~950℃, and the pressure is maintained at 150~220MPa for 2~4h; then, the temperature is raised to 1120~1150℃, and the pressure is maintained at 150~220MPa for 30~50min, followed by cooling. Step 2: The part blank is subjected to solution heat treatment in sequence. The solution heat treatment temperature is 15~25℃ below the solution temperature of the γ′ phase, and the holding time is ≥1h; then it is subjected to standard aging heat treatment, and then precision machining is performed to obtain the bicrystalline powder metallurgy part.

3. The method for preparing a metallurgical component according to claim 2, characterized in that, The cooling process specifically involves: first, reducing the furnace temperature to 900-1000℃ at a rate of 10-20℃ / min, and then further cooling the furnace to the allowable furnace opening temperature.

4. An application of a bicrystalline powder metallurgy part, characterized in that, The bicrystalline powder metallurgy part is used in high-temperature load-bearing components of aero-engines, and the bicrystalline powder metallurgy part is prepared by the metallurgical part preparation method as described in any one of claims 2 to 3.

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