A method of making a high strength, high fatigue life alloy disk

Abstract

The application discloses a method for preparing high-strength and high-fatigue-life alloy disc pieces and belongs to the technical field of metal material forming and processing. The method comprises the following steps: step one, powder preparation; step two, hot isostatic pressing forming; step three, extrusion: preheating an extrusion rod and an extrusion cylinder, processing a hot isostatic pressing state blank with a jacket into a blank A with a shape and a specification required by extrusion, heating the blank A, then putting the blank A into the extrusion cylinder and extruding the blank A through the extrusion rod to obtain an extruded state blank; step four, forging: processing the extruded state blank into a blank B with a shape and a specification required by forging, respectively heating a die and the blank B, then putting the blank B into the die to perform forging; and step five, heat treatment. The extrusion process can eliminate original particle boundaries and dispersed inclusions and avoid the generation of large-size defects. After sub-solid solution treatment and aging treatment, the strength and fatigue life of the alloy disc pieces are greatly improved.

Description

Technical Field

[0001] This invention relates to a method for preparing high-strength, high-fatigue-life alloy discs, belonging to the field of metal material forming and processing technology. Background Technology

[0002] Nickel-based powder superalloy FGH4097 exhibits excellent mechanical properties, good oxidation resistance, and corrosion resistance at high temperatures, making it widely used in hot-end components such as turbine disks and compressor disks in aero-engines. Typically, FGH4097 alloy disks are formed by direct hot isostatic pressing of powder atomized using a plasma rotating electrode process with a particle size of 50μm–150μm. After heat treatment, the resulting disks have a grain structure of approximately grade 6, indicating relatively coarse grains. This coarse grain structure leads to both a lower strength margin and higher noise during flaw detection, resulting in larger detected defects. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides a method for preparing high-strength, high-fatigue-life alloy discs, which can prepare a uniform fine-grained structure while avoiding defects such as the original particle boundaries and inclusions of powder.

[0004] This invention is achieved through the following technical solution:

[0005] A method for preparing high-strength, high-fatigue-life alloy discs includes the following steps:

[0006] Step 1, Powder preparation: Continuously cast alloy rods, then make the alloy rods obtained from continuous casting into powder, and then sieve and electrostatically separate them to obtain the finished powder;

[0007] Step 2, Hot Isostatic Pressing: The finished powder is loaded into a sleeve and the sleeve is sealed. Then the finished powder inside the sleeve is subjected to hot isostatic pressing to sinter and densify the finished powder, resulting in a hot isostatic pressed blank.

[0008] Step 3, Extrusion: Preheat the extrusion rod and extrusion cylinder, process the hot isostatic pressed billet into billet A of the required shape and specifications for extrusion with a sleeve, heat billet A, put billet A into the extrusion cylinder, and extrude billet A through the extrusion rod. The extruded bar is then air-cooled and inspected to obtain the extruded billet.

[0009] Step 4, Forging: The extruded billet is processed into billet B of the required shape and specifications for forging. The mold and billet B are heated respectively. Then, billet B is placed into the mold for forging and the forging is air-cooled.

[0010] Step 5, Heat treatment: Heat the forging, then alternate between heat treatment and air cooling to gradually reduce the temperature of the forging.

[0011] In step one, alloy bars are continuously cast using a vacuum horizontal continuous casting machine.

[0012] In step one, the alloy rods obtained from continuous casting are first precision machined into rods with a diameter of 50mm to 80mm, a length of 500mm to 1000mm, a roundness deviation of less than 0.1mm, a straightness deviation of less than 0.1mm / m, and a roughness of less than 1.6μm. Then, the rods are made into powder by plasma rotating electrode powder making method. The rotation speed during the rod powder making process is 15000r / min to 20000r / min.

[0013] The particle size of the finished powder is -100μm, and the number of non-metallic inclusions in the finished powder is ≤10 particles / kg of powder.

[0014] In step two, before loading the finished powder into the packaging sleeve, the vacuum level of the working chamber is first evacuated to 1×10⁻⁶. -2 Within MPa, the temperature of the packaging is heated to 350℃~550℃ and kept at that temperature for 1 hour before filling the packaging with the finished powder.

[0015] In step two, the temperature for hot isostatic pressing of the finished powder inside the package is 1180℃±20℃, the pressure is 130MPa~140MPa, and the holding time is 3h~4h.

[0016] In step three, the extrusion rod and extrusion cylinder are preheated simultaneously. After the preheating temperature reaches 300℃~400℃, the holding time is not less than 2 hours. After quickly coating the extrusion cylinder with glass lubricant, the billet A is extruded after being taken out of the furnace. The extrusion rod extrudes the billet A at a speed of 40mm / s~60mm / s.

[0017] In step three, a resistance heating furnace is used to heat billet A. The allowable temperature deviation within the effective heating zone of the resistance heating furnace is ≤ ±10℃, and the allowable temperature control deviation is ≤ ±5℃.

[0018] After the billet A is loaded into the furnace at a temperature below 500°C, it is heated with the furnace to 20°C to 40°C below the solution temperature and held at that temperature for 8 to 24 hours.

[0019] In step four, the mold includes an upper mold and a lower mold. Before forging the blank B in the mold, the upper mold and the lower mold are heated to 1050°C, and glass lubricant is applied to the surface of the upper mold and the lower mold during the heating process.

[0020] In step four, the billet B is heated to 20°C to 60°C below the solution temperature using a resistance heating furnace and kept at that temperature for 3 to 5 hours. Then, it is taken out of the furnace, coated with glass lubricant, and covered with insulating cotton. It is then put back into the furnace and kept at that temperature for another 3 hours.

[0021] In step four, after placing the billet B into the lower die, the upper die presses down, causing the billet B to move at a speed of 0.01–0.05 seconds. -1 The strain rate causes deformation within the mold until the mold cavity is filled.

[0022] The method for heat-treating the forging in step five is as follows: heat the forging to 1150℃~1170℃ and hold for 4 hours, then air cool; hold the forging at 910℃ for 3 hours, then air cool; hold the forging at 760℃ for 8 hours, then air cool; hold the forging at 700℃ for 17 hours, then air cool.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. The FGH4097 master alloy bar material, which is continuously cast using a vacuum horizontal continuous casting machine, has a low level of inclusions. After further powdering, sieving and electrostatic separation processes, the number of inclusions in the finished powder is 5-10 particles / kg, and the powder has high cleanliness.

[0025] 2. After extrusion, billet A can obtain uniform equiaxed grains of grade 10 or higher; at the same time, the extrusion process can eliminate the original grain boundaries and dispersed inclusions, avoiding the generation of large-sized defects.

[0026] 3. By eliminating the initial coarse hot isostatic pressing structure through extrusion and forging processes, a uniform fine-grained structure is obtained, thereby improving the comprehensive mechanical properties of FGH4097 alloy.

[0027] 4. By forging complex-shaped discs in a single firing process and maintaining a uniform fine-grained structure, the forged FGH4097 alloy discs, after heat treatment, possess ideal microstructure and properties, and the number of defects in the alloy discs is greatly reduced.

[0028] 5. After subsolution treatment and aging treatment, the strength and fatigue life of the alloy disc are greatly improved. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the extrusion rod and extrusion cylinder of the present invention extruding the billet A1;

[0030] Figure 2 This is a schematic diagram of the structure of the mold of the present invention when forging blank B4;

[0031] Figure 3 The image shows the metallographic structure of the FGH4097 alloy disc prepared according to Embodiment 1 of the present invention.

[0032] In the diagram: 1-Blank A, 2-Extrusion rod, 3-Extrusion cylinder, 4-Blank B, 5-Upper die, 6-Lower die. Detailed Implementation

[0033] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0034] like Figures 1 to 3 As shown, the method for preparing high-strength, high-fatigue-life alloy discs according to the present invention includes the following steps:

[0035] Step 1: Powder Preparation. FGH4097 alloy bars are continuously cast, then the resulting alloy bars are powdered and sequentially sieved and electrostatically separated to obtain the finished powder. The FGH4097 master alloy bars cast using a vacuum horizontal continuous casting machine have low inclusion levels. After further powder preparation, sieving, and electrostatic separation processes, the number of inclusions in the obtained finished powder is 5–10 particles / kg, resulting in high powder cleanliness.

[0036] Step 2, Hot Isostatic Pressing: The finished powder is loaded into a sleeve and the sleeve is sealed. Then, the finished powder inside the sleeve is subjected to hot isostatic pressing to sinter and densify the finished powder, resulting in a hot isostatic pressed blank.

[0037] Step 3, Extrusion: The extrusion rod 2 and extrusion cylinder 3 are preheated. The hot isostatically pressed billet, with a sleeve, is processed into billet A1 of the required shape and specifications for extrusion. Billet A1 is then heated and placed into extrusion cylinder 3, and extruded through extrusion rod 2. The extruded bar is then air-cooled and inspected to obtain the extruded billet. After extrusion, billet A1 can obtain uniform equiaxed grains of grade 10 or higher. At the same time, the extrusion process can eliminate the original grain boundaries and dispersed inclusions, avoiding the generation of large-sized defects.

[0038] Step 4: Forging: The extruded billet is processed into billet B4 of the required shape and specifications for forging. Both the die and billet B4 are heated, and then billet B4 is placed in the die for forging. The forging is then air-cooled. The extrusion and forging processes eliminate the initially coarse hot isostatic pressing structure, obtaining a uniform fine-grained structure, thereby improving the overall mechanical properties of the FGH4097 alloy. The forged FGH4097 alloy discs, after heat treatment, possess ideal microstructure and properties, and the number of defects in the alloy discs is significantly reduced.

[0039] Step 5, Heat treatment: Heat the forging, then alternate between heat treatment and air cooling to gradually reduce the temperature of the forging.

[0040] In step one, FGH4097 alloy bars are continuously cast using a vacuum horizontal continuous casting machine.

[0041] In step one, the alloy rods obtained from continuous casting are first precision machined into rods with a diameter of 50mm to 80mm, a length of 500mm to 1000mm, a roundness deviation of less than 0.1mm, a straightness deviation of less than 0.1mm / m, and a roughness of less than 1.6μm. Then, the rods are made into powder by plasma rotating electrode powder making method. The rotation speed during the rod powder making process is 15000r / min to 20000r / min.

[0042] The particle size of the finished powder is -100μm, and the number of non-metallic inclusions in the finished powder is ≤10 particles / kg of powder.

[0043] In step two, before loading the finished powder into the packaging sleeve, the vacuum level of the working chamber is first evacuated to 1×10⁻⁶. -2 Within MPa, the temperature of the packaging is heated to 350℃~550℃ and kept at that temperature for 1 hour before filling the packaging with the finished powder.

[0044] In step two, the temperature for hot isostatic pressing of the finished powder inside the package is 1180℃±20℃, the pressure is 130MPa~140MPa, and the holding time is 3h~4h.

[0045] In step three, the extrusion rod 2 and the extrusion cylinder 3 are preheated simultaneously. After the preheating temperature reaches 300℃~400℃, the heat preservation time is not less than 2 hours. After the glass lubricant is quickly coated inside the extrusion cylinder 3, the billet A1 is extruded after being taken out of the furnace. The extrusion rod 2 extrudes the billet A1 at a speed of 40mm / s~60mm / s.

[0046] In step three, a resistance heating furnace is used to heat the billet A1. The allowable temperature deviation within the effective heating zone of the resistance heating furnace is ≤ ±10℃, and the allowable temperature control deviation is ≤ ±5℃.

[0047] After being loaded into the furnace at a temperature below 500°C, the billet A1 is heated to 20°C–40°C below the solution temperature and held at that temperature for 8–24 hours. In use, the billet A1 is heated to 20°C–40°C below the solution temperature (i.e., sub-solution), specifically to 1150°C–1160°C, to coarsen the γ' phase structure at the grain boundaries, obtaining a γ+γ' phase dual-phase structure with good thermoplasticity and improving its plastic deformation capacity.

[0048] In step four, the mold includes an upper mold 5 and a lower mold 6. Before forging the blank B4 in the mold, the upper mold 5 and the lower mold 6 are heated to 1050°C, and glass lubricant is applied to the surface of the upper mold 5 and the lower mold 6 during the heating process.

[0049] In step four, a resistance heating furnace is used to heat the billet B4 to 20°C–60°C below the solution temperature and hold it at that temperature for 3–5 hours. Then, the billet is removed from the furnace, coated with glass lubricant, and insulated with cotton. It is then placed back into the furnace and held for another 3 hours. Heating the billet B4 to 20°C–60°C below the solution temperature (i.e., sub-solution), specifically to 1130°C–1150°C, coarsens the γ' phase structure at the grain boundaries, reducing deformation resistance and improving its plastic deformation capacity.

[0050] In step four, after the billet B4 is placed into the lower mold 6, the upper mold 5 presses down, causing the billet B4 to move at a speed of 0.01 to 0.05 seconds. -1 The strain rate causes deformation within the mold until the mold cavity is filled. Complex-shaped discs are forged in a single firing process while maintaining a uniform fine-grained structure.

[0051] The heat treatment method for the forging in step five is as follows: heating the forging to 1150℃~1170℃ and holding it at that temperature for 4 hours, then air cooling; holding the forging at 910℃ for 3 hours, then air cooling; holding the forging at 760℃ for 8 hours, then air cooling; and holding the forging at 700℃ for 17 hours, then air cooling. The heat treatment method is aging treatment. After subsolution treatment + aging treatment, the strength and fatigue life of the alloy disc are greatly improved.

[0052] Example 1:

[0053] Step 1: Powder preparation:

[0054] FGH4097 alloy bars were continuously cast using a vacuum horizontal continuous casting machine. The cast alloy bars were then precision machined into bars with a diameter of 50mm-80mm, a length of 500mm-1000mm, a roundness deviation of less than 0.1mm, a straightness deviation of less than 0.1mm / m, and a roughness of less than 1.6μm. The bars were then pulverized using a plasma rotating electrode powdering method at a rotation speed of 15000r / min-20000r / min. After sieving and electrostatic separation, the finished powder was obtained with a particle size of -100μm and a non-metallic inclusion count of ≤10 particles / kg of powder. A total of 2500kg of finished powder was produced in batches.

[0055] Step 2: Hot isostatic pressing (HIP)

[0056] First, the vacuum degree of the working chamber is evacuated to within 1×10-2MPa. Then, the temperature of the cladding is heated to 350℃~550℃ and held for 1 hour. Next, the finished powder is filled into the cladding. After filling, the cladding is sealed and welded. Finally, hot isostatic pressing is performed. The temperature of the hot isostatic pressing is 1200℃, the pressure is 140MPa, and the holding time is 4 hours. The finished powder is sintered and densified through hot isostatic pressing to obtain a hot isostatic pressed billet.

[0057] Step 3, Extrusion:

[0058] The hot isostatic pressed billet is processed into a sheath. Figure 1 The blank A1 has the shape shown and the size of blank A1 is φ800×750mm. Before extrusion, blank A1 is heated to 1160℃ and held for 24h. Extrusion rod 2 and extrusion cylinder 3 are preheated to 300℃~400℃ and held for 2.5h. Glass lubricant is quickly coated on the inner surface of extrusion cylinder 3. After the holding period, blank A1 is transferred to extrusion cylinder 3. Extrusion rod 2 moves down at a speed of 40mm / s to extrude blank A1. Then, the extruded bar is air-cooled and inspected in sequence to obtain the extruded blank.

[0059] Step 4: Forging

[0060] The diameter of the extruded bar is 310mm, and it is processed into the following shape: Figure 2 The billet B4 of the shape shown is placed in a resistance heating furnace and heated to 1130℃. After holding at this temperature for 3 hours, it is removed from the furnace. Glass lubricant is applied to the surface of billet B4 and insulation cotton is attached. It is then placed back into the furnace and held at this temperature for another 3 hours. The upper mold 5 and the lower mold 6 are heated to 1050℃, and glass lubricant is applied to the surfaces of the upper mold 5 and the lower mold 6 during the heating process. After billet B4 is placed in the lower mold 6, the upper mold 5 is pressed down to deform billet B4 in the mold at a strain rate of 0.01 to 0.05 s⁻¹ until it fills the mold cavity. Then, the forging is air-cooled.

[0061] Step 5, Heat Treatment:

[0062] After forging, the disc is machined and then heat-treated. The heat treatment process is as follows: 1150℃~1170℃ for 4 hours, air-cooled; 910℃ for 3 hours, air-cooled; 760℃ for 8 hours, air-cooled; 700℃ for 17 hours, air-cooled.

[0063] Metallographic structure after heat treatment, such as Figure 3 As shown, the average grain size is approximately 16.5 μm. The tensile properties are shown in Table 1, and the fatigue properties are shown in Table 2.

[0064] Table 1 Tensile Mechanical Properties

[0065] Test temperature (°C) <![CDATA[σ b (MPa)]]> <![CDATA[σ 0.2 (MPa)]]> <![CDATA[δ5%]]> ψ% room temperature 1633 1151 24.5 30 650 1420 1100 14 16.5

[0066] Table 2 Low-cycle fatigue performance

[0067] Test temperature T (°C) σ(MPa) f(Hz) <![CDATA[N f (Week) 650 1020 1 131701

Claims

1. A method for preparing high-strength, high-fatigue-life alloy discs, characterized in that: Includes the following steps: Step 1, Powder preparation: Continuously cast alloy rods, then make the alloy rods obtained from continuous casting into powder, and then sieve and electrostatically separate them to obtain the finished powder; Step 2, Hot Isostatic Pressing: The finished powder is loaded into a sleeve and the sleeve is sealed. Then the finished powder inside the sleeve is subjected to hot isostatic pressing to sinter and densify the finished powder, resulting in a hot isostatic pressed blank. Step 3, extrusion: Preheat the extrusion rod (2) and extrusion cylinder (3), process the hot isostatic pressed billet into billet A (1) of the required shape and specifications for extrusion with a sleeve, heat the billet A (1), put the billet A (1) into the extrusion cylinder (3), and extrude the billet A (1) through the extrusion rod (2). The extruded bar is air-cooled and inspected in sequence to obtain the extruded billet; Step 4, forging: The extruded billet is processed into a billet B (4) of the required shape and specifications for forging. The mold and billet B (4) are heated respectively. Then, the billet B (4) is placed into the mold for forging and the forging is air-cooled. Step 5, Heat Treatment: Heat the forging, then alternate between heat treatment and air cooling to gradually reduce the temperature of the forging, thus obtaining the final product; In step one, alloy bars are continuously cast using a vacuum horizontal continuous casting machine. In step one, the alloy rods obtained from continuous casting are first precision machined into rods with a diameter of 50mm~80mm, a length of 500mm~1000mm, a roundness deviation of less than 0.1mm, a straightness deviation of less than 0.1mm / m, and a roughness of less than 1.6μm. Then, the rods are made into powder by plasma rotating electrode powder making method. The rotation speed during the rod powder making process is 15000r / min~20000r / min. The particle size of the finished powder is -100μm, and the number of non-metallic inclusions in the finished powder is ≤10 particles / kg powder; In step two, the temperature for hot isostatic pressing of the finished powder inside the package is 1180℃±20℃, the pressure is 130MPa~140MPa, and the holding time is 3h~4h. In step three, the billet A (1) is heated to 20°C~40°C below the solution temperature after being loaded into the furnace at a temperature below 500°C, and then kept at that temperature for 8h~24h. In step three, the extrusion rod (2) and the extrusion cylinder (3) are preheated simultaneously. After the preheating temperature reaches 300℃~400℃, the heat preservation time is not less than 2 hours. After the glass lubricant is quickly coated in the extrusion cylinder (3), the blank A (1) is extruded after being taken out of the furnace. The extrusion rod (2) extrudes the blank A (1) at a speed of 40mm / s~60mm / s. In step four, the mold includes an upper mold (5) and a lower mold (6). Before forging the blank B (4) in the mold, the upper mold (5) and the lower mold (6) are heated to 1050°C. In step four, the billet B (4) is heated to 20°C~60°C below the solution temperature and kept at that temperature for 3h~5h. In step four, after the blank B (4) is placed into the lower mold (6), the upper mold (5) presses down to make the blank B (4) move at a speed of 0.01s. -1 ~0.05s -1 The strain rate causes deformation within the mold until the mold cavity is filled; The method for heat-treating the forging in step five is as follows: heat the forging to 1150℃~1170℃ and hold for 4 hours, then air cool; hold the forging at 910℃ for 3 hours, then air cool; hold the forging at 760℃ for 8 hours, then air cool; hold the forging at 700℃ for 17 hours, then air cool.

2. The method for preparing high-strength, high-fatigue-life alloy discs as described in claim 1, characterized in that: In step two, before loading the finished powder into the packaging sleeve, the vacuum level of the working chamber is first evacuated to 1×10⁻⁶. -2 Within MPa, the temperature of the packaging is heated to 350℃~550℃ and kept at that temperature for 1 hour before filling the packaging with the finished powder.

3. The method for preparing high-strength, high-fatigue-life alloy discs as described in claim 1, characterized in that: In step three, a resistance heating furnace is used to heat the billet A (1). The temperature deviation within the effective heating zone of the resistance heating furnace is ≤ ±10℃, and the temperature control deviation is ≤ ±5℃.

4. The method for preparing high-strength, high-fatigue-life alloy discs as described in claim 1, characterized in that: In step four, glass lubricant is applied to the surfaces of the upper mold (5) and the lower mold (6) during the heating process.

5. The method for preparing high-strength, high-fatigue-life alloy discs as described in claim 1, characterized in that: In step four, the billet B (4) is heated to 20°C~60°C below the solution temperature in a resistance heating furnace and kept at that temperature for 3h~5h. Then, it is taken out of the furnace, coated with glass lubricant, and covered with insulation cotton. It is then put back into the furnace and kept at that temperature for another 3h.

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