Forging method for homogenizing the microstructure of GH4169 alloy disc shaft integral forging

Abstract

This invention belongs to the field of forging technology and relates to a forging method for achieving uniform microstructure in GH4169 alloy disc-shaft integral forgings. The method includes: preparing a billet, which is a truncated cone with a variable cross-section, wider at the top and narrower at the bottom; using a punch to upset the center of the larger end of the truncated cone to form a concave platform, while the non-concave area at the larger end forms an arc surface due to metal flow; machining a bevel on the arc surface as a positioning surface to obtain a rough shape; flipping the rough shape 180° and placing it in the lower mold cavity, with the positioning surface of the rough shape fitting against the bevel of the transition cavity, at which point the concave platform of the rough shape faces downwards towards the rod cavity; die forging: with pressure, the metal of the smaller cross-section of the truncated cone flows towards the disc cavity, while the metal of the larger cross-section flows towards the transition cavity, and the metal of the concave platform flows towards the rod cavity, ultimately forming the forging.

Description

Technical Field

[0001] This invention belongs to the field of forging technology and relates to a forging method for achieving uniform microstructure in GH4169 alloy disc-shaft integral forgings. Background Technology

[0002] GH4169 alloy is an iron-nickel-chromium based wrought superalloy. Its microstructure consists of a γ matrix, δ phase, carbides, and γ''(Ni3Nb) and γ''(Ni3(Al,Ti)) as strengthening phases. It is mainly used in key components of aerospace engines. A certain GH4169 disc-shaft integrated forging is an important load-bearing component of an aero-engine, requiring a high-strength process. During early trial production, it was found that the process route of forging the rod part using a die and then die-forging the disc part resulted in uneven deformation of the forging, the appearance of small deformation zones, and incomplete recrystallization of the microstructure. This led to microstructural problems such as inhomogeneity at low magnification and coarse grains, failing to meet the standard requirement of a grain size ≥8. This invention proposes a forging method to achieve uniform microstructure in GH4169 alloy disc-shaft integrated forgings. This method deforms the disc and rod parts as a whole, increasing the deformation amount of the rod part, resulting in a GH4169 alloy disc-shaft integrated forging with qualified grain size (≥8 grade) and uniform microstructure. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a forging method for homogenizing the microstructure of GH4169 alloy disc shaft integral forgings, so as to obtain disc shaft forgings with uniform microstructure and good performance margin.

[0004] Technical solution:

[0005] A forging method for achieving homogeneous microstructure in an integral forging of a GH4169 alloy disc shaft, wherein the GH4169 alloy disc shaft sequentially comprises a disc portion, a transition portion, and a rod portion, and the forging die cavity includes a disc cavity, a transition cavity, and a rod portion cavity; the method includes:

[0006] The blank is made into a truncated cone with a variable cross-section, the truncated cone being larger at the top and smaller at the bottom;

[0007] A concave platform is formed by upsetting the center of the large end of the truncated cone using a punch, while the non-concave area at the large end forms an arc surface due to metal flow.

[0008] A bevel is machined onto the arc surface as a positioning surface to obtain the rough shape;

[0009] Flip the rough shape 180° and place it in the lower model cavity. The positioning surface of the rough shape fits into the inclined surface of the transition cavity. At this time, the concave platform of the rough shape faces downward and is directly opposite the rod cavity.

[0010] Die forging: With pressure, the small-section metal of the cone flows to the disc cavity, while the large-section metal flows to the transition cavity, and the concave metal flows to the rod cavity, finally forming the forging.

[0011] Making blanks includes:

[0012] The bar stock is heated to 1010℃ and then placed in a mold to form a truncated cone with a variable cross-section.

[0013] When heating, use insulating cotton to cover the material.

[0014] The mold is formed using a flat anvil upsetting method.

[0015] Forging, including:

[0016] The 200MN hydraulic press is used for die forging. The die preheating temperature is 300℃ and the preheating time is ≥20h. The billet is heated to 1000℃. During heating, insulation cotton is used for soft wrapping. During die forging, the billet is flipped so that the large cross section of the billet contacts the die for positioning. The deformation rate is 3~5mm / s and the deformation amount is controlled at 40%~58%.

[0017] After die forging, the method further includes:

[0018] After forging, the forging is subjected to heat treatment. The heat treatment regime is solution treatment and aging. The solution treatment temperature is 975℃, held for 60 min, and then air-cooled. The aging temperature is 720℃, held for 480 min, and then furnace-cooled to 620℃ at a cooling rate of (50±10)℃ / h, held for 480 min, and then air-cooled to obtain the final forging.

[0019] The ratio of the sum of the heights of the disc and the transition section to the height of the rod is 1:1 to 1.5:1.

[0020] The depth of the concave platform is set between 20-25mm; the diameter of the concave platform is 1 / 3 to 1 / 2 of the diameter of the large end face of the truncated cone.

[0021] The diameter of the large end face of the truncated cone is between the maximum and minimum diameters of the transition section.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention uses a die for blank preparation, which provides a reasonable rough shape for die forging. First, a flat anvil is used for upsetting, and then a punch is used for upsetting. The punch presses a pit in the center of the rough shape, which makes the metal distribution of the rough shape more reasonable, increases the deformation during the blank preparation process, and saves raw materials.

[0024] During die forging, the billet is flipped so that the larger side of the billet contacts the die for positioning. A 200MN hydraulic press is used for die forging, and the deformation is controlled between 40% and 58%. This increases the deformation of the rod, causing the disc and rod to deform as a whole, resulting in a uniformly structured disc-shaft integral forging. Attached Figure Description

[0025] Figure 1 This is the final forging drawing.

[0026] Figure 2 Forging pattern of tire mold.

[0027] Figure 3 Add a diagram to the undeveloped machine.

[0028] Figure 4 This is a diagram of a die forging material. Detailed Implementation

[0029] The present invention will be further described in detail below through specific embodiments:

[0030] This invention provides a forging method for producing a GH4169 alloy disc-shaft integral forging with uniform microstructure, such as... Figure 1 As shown, the GH4169 alloy disc shaft sequentially includes a disc section, a transition section, and a rod section, as follows: Figure 3 As shown, the cavity of the forging die includes a disc cavity, a transition cavity, and a rod cavity; the method includes the following steps:

[0031] Step 1: Cut the GH4169 alloy bar and position it with a beveled surface. The beveled surface of the bar should contact the die to ensure that the bar is in the appropriate position in the die during billet making.

[0032] Step 2: Heat the bar stock to 1005℃~1015℃, using insulating cotton for soft wrapping during heating. Place the bar stock in the die and upset it using a 16MN free forging press. Add insulating cotton to the upper and lower ends of the bar stock. When upseting, first use a flat anvil for upseting, then use a punch for upseting (see...). Figure 2 ), to make the rough shape required for die forging;

[0033] Step 3: Machining the rough shape and positioning table (see...) Figure 3 This facilitates positioning during die forging.

[0034] Step 4: Heat the billet to 1000℃~1010℃. During heating, use insulating cotton for a soft wrapping. During die forging, flip the billet so that its positioning surface contacts the die for positioning (see...). Figure 4 The die is forged using a 200MN hydraulic press with a preheating temperature of 250℃~350℃, a deformation rate of 3~5mm / s, and a deformation amount controlled at 40%~58%. This increases the deformation amount of the rod, allowing the disc and rod to deform as a whole, thus avoiding the formation of large-area deformation dead zones.

[0035] During the die forging process, as the pressure increases, the billet flows towards the disc, transition section, and rod section of the forging, ensuring that the disc and rod sections are filled simultaneously. This avoids the problem of the disc section deforming and filling completely first, while the rod section has difficulty filling. The recessed platform eliminates some dead zones in the die forging blank, leaves deformation space during the die forging process, and also saves material.

[0036] Step 5: After forging, the forging is subjected to heat treatment. The heat treatment regime is solution treatment and aging. The solution treatment temperature is 975℃, held for 60 min, and then air-cooled. The aging temperature is 720℃, held for 480 min, and then furnace-cooled to 620℃ at a cooling rate of (50±10)℃ / h, held for 480 min, and then air-cooled to obtain the final forging.

[0037] Example 1

[0038] The present invention discloses a GH4169 alloy disc-shaft integral forging. The outer diameter of the disc is Φ409mm, the diameter of the rod is Φ160mm, the height of the forging is 157mm, and the weight of the forging is 91Kg. The well-designed rough shape makes the structure of the disc and rod of the forging uniform, and the performance indicators meet the standard requirements for forgings.

[0039] The manufacturing process is detailed below:

[0040] 1. Cutting: Sawing machine, cutting size φ220×291mm;

[0041] 2. Billet machining: Bar stock with R10 chamfer and machined bevel for positioning;

[0042] 3. Billet Preparation: The bar stock is heated to 1010℃, and a soft insulation cotton sleeve is used during heating. The bar stock is then placed in a die and upset using a 16MN free forging press. See the diagram for bar stock placement. Figure 2 Insulating cotton is added to the upper and lower ends of the bar stock. When upsetting, a flat anvil is used first, and then a punch is used to upset the rough shape required for die forging.

[0043] 4. Machined rough shape: according to the attached... Figure 3 Machining of rough shape and positioning table facilitates positioning during die forging;

[0044] 5. Die forging: A 200MN hydraulic press is used for die forging. The die preheating temperature is 300℃, and the preheating time is ≥20h. The billet is heated to 1000℃. During heating, it needs to be softly wrapped with insulation cotton. During die forging, the billet is flipped so that the positioning surface of the billet contacts the die for positioning. (See attached...) Figure 4 Place the blank, with a deformation rate of 3-5 mm / s and a deformation amount controlled at 40%-58%. Increase the deformation amount of the rod to deform the disc and rod as a whole, avoiding the generation of large-area deformation dead zones.

[0045] 6. After forging, the forging is subjected to heat treatment. The heat treatment regime is solution treatment and aging. The solution treatment temperature is 975℃, held for 60 min, and then air-cooled. The aging temperature is 720℃, held for 480 min, and then furnace-cooled to 620℃ at a cooling rate of (50±10)℃ / h, held for 480 min, and then air-cooled to obtain the final forging.

[0046] The GH4169 alloy disc-shaft integral forging obtained by this forging method was tested and found to have: uniform grain size (grade 10) in both the disc and shaft sections; and room temperature tensile strength: σ b =1463MPa, σ 0.2 =1165MPa, δ5=19.5%, ψ=32%, the microstructure and performance indicators of the forging meet the requirements of high-strength forging.

Claims

1. A forging method for achieving uniform microstructure in a GH4169 alloy disc-shaft integral forging, wherein the GH4169 alloy disc-shaft sequentially comprises a disc portion, a transition portion, and a rod portion, characterized in that... The cavity of the forging die includes a disc cavity, a transition cavity, and a rod cavity; the method includes: The blank is made into a truncated cone with a variable cross-section, the truncated cone being larger at the top and smaller at the bottom; A concave platform is formed by upsetting the center of the large end of the truncated cone using a punch, while the non-concave area at the large end forms an arc surface due to metal flow. A bevel is machined onto the arc surface as a positioning surface to obtain the rough shape; The rough die is flipped 180° and placed in the lower mold cavity. The positioning surface of the rough die fits against the inclined surface of the transition cavity. At this time, the concave platform of the rough die faces downward and directly faces the rod cavity. The concave platform eliminates part of the dead zone in the die forging process and leaves deformation space during the die forging process. Die forging: With pressure, the small-section metal of the truncated cone flows to the disc cavity, while the large-section metal flows to the transition cavity, and the concave metal flows to the rod cavity, finally forming the forging; Forging, including: The 200MN hydraulic press is used for die forging. The die preheating temperature is 300℃ and the preheating time is ≥20h. The billet is heated to 1000℃. During heating, insulation cotton is used for soft wrapping. During die forging, the billet is flipped so that the large section of the billet contacts the die for positioning. The deformation rate is 3~5mm / s and the deformation amount is controlled at 40%~58%. The ratio of the sum of the heights of the disc and the transition section to the height of the rod is 1:1 to 1.5:

1.

2. The method according to claim 1, characterized in that, Making blanks includes: The bar stock is heated to 1010℃ and then placed in a mold to form a truncated cone with a variable cross-section. When heating, use insulating cotton to cover the material.

3. The method according to claim 2, characterized in that, The mold is formed using a flat anvil upsetting method.

4. The method according to claim 1, characterized in that, After die forging, the method further includes: After forging, the forging is subjected to heat treatment. The heat treatment regime is solution treatment and aging. The solution treatment temperature is 975℃, held for 60 min, and then air-cooled. The aging temperature is 720℃, held for 480 min, and then furnace-cooled to 620℃ at a cooling rate of (50±10)℃ / h, held for 480 min, and then air-cooled to obtain the final forging.

5. The method according to claim 1, characterized in that, The depth of the concave platform is set between 20-25mm; the diameter of the concave platform is 1 / 3 to 1 / 2 of the diameter of the large end face of the truncated cone.

6. The method according to claim 1, characterized in that, The diameter of the large end face of the truncated cone is between the maximum and minimum diameters of the transition section.

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