Forging method for structure homogenization of GH141 alloy complex section forge piece

Abstract

The invention belongs to the technical field of forging, and relates to a forging method for structure homogenization of a GH141 alloy complex section forge piece. The method comprises the steps that blanking is conducted, and a GH141 alloy bar is chamfered; upsetting the GH141 alloy bar to obtain a cake blank; a pre-forging die is used for pre-forging the cake blank, under the constraint of the pre-forging die, a positioning boss is formed at the upper end of the cake blank, outer circle metal flows outwards, a convex outer circle is formed, the upper section and the lower section of the convex outer circle form slopes, the middle section naturally bulges, and a rough mold is obtained; under the constraint of the finish forging die, the positioning boss is fixed with the lower die of the finish forging die, and the convex outer circle metal flows outwards and downwards until the transition position of the section and the middle section, close to the positioning boss, of the convex outer circle is in contact with the middle of the outer wall of a cavity, used for forming the outer circle of the transition part, of the lower die; and the metal of the convex outer circle simultaneously moves up and down, upwards fills the cavity for forming the circumferential part of the large head, and downwards fills the cavity for forming the inner diameter part of the small head.

Description

Technical Field

[0001] The invention belongs to the technical field of forging, and relates to a forging method for homogenizing the structure of a GH141 alloy complex-section forging. Background Art

[0002] GH141 is a coarse-grained alloy with high Al and Ti contents. Its hot working plasticity is relatively poor. In order to obtain a relatively stable structure, the forging range is narrow and the process control is difficult. The heat treatment solution temperature is high. Under the conditions of high-temperature solution process, the grains tend to grow. It is mainly used in key components of aerospace engines. GH141 forgings are important load-bearing components of aerospace engines. During the early trial production process, it was found that the process route of using die forging and then die forging would cause uneven deformation of the forgings, large deformation areas, and the structure could not be completely recrystallized. As a result, the forgings have structural problems such as low-magnification uneven structure and coarse grains, which do not meet the standard requirements of grain size ≥ level 2 and uniformity. Forging cracks are easily generated during the forging process, which reduces the yield rate. Summary of the Invention

[0003] Purpose of the invention: The present invention proposes a forging method for homogenizing the microstructure of GH141 alloy complex forgings, which makes the overall deformation of the forgings uniform and obtains GH141 alloy complex cross-section forgings with qualified grain size (≥2, without obvious coarse and fine grain segregation).

[0004] Technical solution: Provided is a forging method for homogenizing the microstructure of a GH141 alloy complex cross-section forging. The forging is a disc-shaped structure with an annular foot, comprising a large head circumference portion, a transition portion, and a small head inner diameter portion. The large head circumference portion and the transition portion constitute the disc-shaped main structure, and the small head inner diameter portion serves as the annular foot structure. The method comprises: Cut and chamfer the GH141 alloy bar; Upsetting GH141 alloy bar to obtain cake blank; Use a pre-forging die to pre-forge the cake blank. Under the constraint of the pre-forging die, a positioning boss is formed on the upper end of the cake blank. The outer circle metal flows outward to form a convex outer circle. The upper and lower sections of the convex outer circle form inclined surfaces, and the middle section naturally bulges to obtain a rough shape. The final forging die is used to perform final forging on the rough mold that is turned upside down. Under the constraint of the final forging die, the positioning boss and the lower die of the final forging die are fixed, and the convex outer circle metal flows outward and downward until the transition position between the first and middle sections of the convex outer circle close to the positioning boss contacts the middle part of the outer wall of the cavity of the lower die used to form the outer circle of the transition part. After that, the metal of the convex outer circle moves up and down at the same time, filling the cavity used to form the large head circumference part upward and filling the cavity used to form the small head inner diameter part downward until the large head circumference part and the small head inner diameter part are formed at the same time.

[0005] Furthermore, the upsetting of the GH141 alloy bar to obtain a cake blank comprises: The bar is heated to 1050~1150℃, and is soft-wrapped with thermal insulation cotton during heating. It is upset using a 45MN fast forging machine, and thermal insulation cotton is padded on the upper and lower end surfaces of the bar. The preheating temperature of the hammer anvil is ≥150℃, and the pressing rate is 10~15mm / s.

[0006] Furthermore, the pre-forging die is used to pre-forge the cake blank, including: The cake blank is heated to 1050~1150℃, and the cavity is preheated with dummy material for 20 minutes before pre-forging. The transfer time is controlled at ≤80s. During heating, it is soft-wrapped with thermal insulation cotton. The bar material is placed in the pre-forging die and pre-forged in a 200MN hydraulic press. The upper and lower end surfaces of the die are padded with thermal insulation cotton to make the rough shape required for die forging.

[0007] Furthermore, the final forging die is used to perform final forging on the upside-down rough mold, including: The blank is heated to 1050~1150℃, and the cavity is preheated with dummy material for 20 minutes before final forging. The transfer time is controlled at ≤90s. Insulation cotton is used for soft wrapping during heating before forging. A 200MN hydraulic press is used for die forging, with a die preheating temperature of 300℃, a preheating time of ≥20 hours, a deformation rate of 4~10mm / s, and a deformation amount controlled at 35%~60%.

[0008] Furthermore, after obtaining the wild type, the method further includes: Machined burrs facilitate die forging positioning.

[0009] Furthermore, after final forging the upside-down rough mold using the final forging die, the method further includes: After forging, the forgings are heat treated.

[0010] Furthermore, the heat treatment system is annealing, solution treatment, and aging; Annealing temperature: 1080℃, hold for 60min, then air cool. Solution temperature: 1120℃, keep warm for 60min, then air cool. Aging temperature: 900℃, insulation temperature: 240℃, dispersed air cooling.

[0011] Furthermore, the smaller the volume of the large head circumference, the more inclined the corresponding upper section of the outer circle of the blank; the smaller the volume of the small head inner diameter, the more inclined the corresponding lower section of the outer circle of the blank.

[0012] Beneficial effects: The present invention adopts pre-forging to make blanks, designs a reasonable blank for die forging, first uses a flat anvil for upsetting, and then uses a pre-forging die for forging, so that the deformation distribution of the blank metal is more reasonable and raw materials are saved.

[0013] A 200MN hydraulic press is used for die forging, and the deformation is controlled at 35%~60%. The deformation of the small head inner diameter is increased, so that the large head circumference and the small head inner diameter are deformed as a whole to obtain a forging with uniform structure. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 This is the final forging drawing.

[0014] Figure 2 This is a diagram of pre-forging material.

[0015] Figure 3 It is a wild type picture.

[0016] Figure 4 This is the die forging swing diagram. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below through specific embodiments: The present invention provides a forging method for GH141 alloy complex cross-section forgings with uniform structure, such as Figure 1 As shown in the figure, the GH141 alloy forging includes the large head circumference part, the transition part, and the small head inner diameter part in sequence. The cavity of the forging die includes the disc cavity, the transition cavity and the small head inner diameter cavity (see Figure 3 ); The method comprises the following steps: Step 1: Cut and chamfer the GH141 alloy bar to ensure that the billet is in the appropriate position in the pre-forging die during billet making; Step 2: Heat the bar to 1100℃, preheat the cavity with dummy material for 20min before pre-forging (heat the dummy material to 1000-1100℃, keep warm for ≥2h), control the transfer time to ≤80s, use insulation cotton for soft wrapping during heating, and place the bar in the pre-forging die (see Figure 2 ) Use 200MN hydraulic press to pre-forge and add insulation cotton to the upper and lower end faces of the die to make the rough shape required for die forging (see Figure 3 ); Step 3: Machine the burrs to facilitate die forging positioning; Step 4: Heat the blank to 1100℃, preheat the cavity with dummy material for 20 minutes before final forging (heat the dummy material to 1000-1100℃, and keep warm for ≥2h), control the transfer time to ≤90s, use insulation cotton for soft wrapping when heating before forging, use 200MN hydraulic press for die forging, preheat the mold to 300℃, preheat time ≥20 hours, deformation rate 4~10mm / s, and control the deformation amount to 35%~60%. Increase the deformation amount of the inner diameter of the small head, so that the circumference of the large head and the inner diameter of the small head are deformed as a whole to avoid the formation of large-area deformation dead zones.

[0018] During the die forging process, as the pressure increases, the blank flows to the large end circumference, transition area, and small end inner diameter area of ​​the forging, so that the large end circumference and small end inner diameter areas are filled at the same time, avoiding the problem that the large end circumference is first deformed and filled completely, while the small end inner diameter area is difficult to fill. This eliminates some dead zones in the pre-forging shape, leaves room for deformation during the die forging process, and saves material. (See Figure 4 ) Step 5: After forging, the forgings are heat treated with annealing, solution treatment and aging. The annealing temperature is 1000°C, holding for 60 minutes, and diffuse air cooling. The solution treatment temperature is 1120°C, holding for 60 minutes, and diffuse air cooling. The aging temperature is 900°C, holding at 240°C, and diffuse air cooling to obtain the final forgings.

[0019] Example 1 The GH141 alloy integrated disk-shaft forging described in the present invention has an outer diameter of Φ753 mm at the large end circumference, an inner diameter of Φ377 at the small end inner diameter, a forging height of 244 mm, and a forging weight of 506.4 kg. The rationally designed rough shape ensures uniform microstructure at the large end circumference and the small end inner diameter of the forging, and the performance indicators meet the standard requirements for forgings.

[0020] The manufacturing steps are detailed as follows: 1. Cutting: sawing machine, cutting size φ300×960mm; 2. Blank machining: bar chamfer R15, single side machining amount ≤1.5mm; 3. Blank making: Heat the bar to 1100℃, use heat preservation cotton to soft wrap during heating, and use 45MN fast forging machine for upsetting. See the attached diagram for bar placement. Figure 3 , add insulation cotton to the upper and lower ends of the rod, the preheating temperature of the hammer anvil is ≥150℃, and the pressing rate is 10~15mm / s; 4. Pre-forging: Use 200MN hydraulic press for die forging, preheat the blank in 100~150℃ electric furnace for 10~20min, preheat the cavity with dummy material for 20min before pre-forging (heat the dummy material to 1000~1100℃, keep warm for ≥2h), heat the blank to 1100℃, use insulation cotton for soft wrapping during heating, press the attached Figure 2 Place the blank to increase the deformation of the small head inner diameter part, so that the large head circumference part and the small head inner diameter part are deformed as a whole to avoid the formation of a large area of ​​deformation dead zone; 5. Die forging: Use 200MN hydraulic press for die forging, preheat the blank in 100~150℃ electric furnace for 10~20min, preheat the cavity with dummy material for 20min before forging (heat the dummy material to 1000~1100℃, keep warm for ≥2h), heat the blank to 1100℃, use insulation cotton for soft wrapping during heating, press the attached Figure 4Place the blank to increase the deformation of the small head inner diameter part, so that the large head circumference part and the small head inner diameter part are deformed as a whole to avoid the formation of a large area of ​​deformation dead zone; 6. After forging, the forgings are heat treated with annealing, solution treatment and aging. The annealing temperature is 1080°C, holding for 60 minutes, and diffuse air cooling. The solution treatment temperature is 1120°C, holding for 60 minutes, and diffuse air cooling. The aging temperature is 900°C, holding at 240°C, and diffuse air cooling.

[0021] The GH141 alloy complex cross-section forgings obtained by this forging method were tested: the grain size of the large head circumference, small head inner diameter, and transition part of the forging was uniform at level 4.5, and the high temperature tensile strength was: σ b =988MPa,σ 0.2 =769MPa, δ5=25%, ψ=39%, and the microstructure and performance indicators of the forging meet the forging requirements.

Claims

1. A forging method for homogenizing the microstructure of a GH141 alloy complex cross-section forging, wherein the forging is a disc-shaped structure with an annular foot, comprising a large end circumferential portion, a transition portion, and a small end inner diameter portion, wherein the large end circumferential portion and the transition portion constitute the disc-shaped main structure, and the small end inner diameter portion serves as the annular foot structure, characterized in that: The method includes: Cut and chamfer the GH141 alloy bar; Upsetting GH141 alloy bar to obtain cake blank; Use a pre-forging die to pre-forge the cake blank. Under the constraint of the pre-forging die, a positioning boss is formed on the upper end of the cake blank. The outer circle metal flows outward to form a convex outer circle. The upper and lower sections of the convex outer circle form inclined surfaces, and the middle section naturally bulges to obtain a rough shape. The final forging die is used to perform final forging on the rough mold that is turned upside down. Under the constraint of the final forging die, the positioning boss and the lower die of the final forging die are fixed, and the convex outer circle metal flows outward and downward until the transition position between the first and middle sections of the convex outer circle close to the positioning boss contacts the middle part of the outer wall of the cavity of the lower die used to form the outer circle of the transition part. After that, the metal of the convex outer circle moves up and down at the same time, filling the cavity used to form the large head circumference part upward and filling the cavity used to form the small head inner diameter part downward until the large head circumference part and the small head inner diameter part are formed at the same time.

2. The method according to claim 1, characterized in that The method of upsetting the GH141 alloy bar to obtain a cake blank comprises: The bar is heated to 1050~1150℃, and is soft-wrapped with thermal insulation cotton during heating. It is upset using a 45MN fast forging machine, and thermal insulation cotton is padded on the upper and lower end surfaces of the bar. The preheating temperature of the hammer anvil is ≥150℃, and the pressing rate is 10~15mm / s.

3. The method according to claim 1, characterized in that Use a pre-forging die to pre-forge the cake, including: The cake blank is heated to 1050~1150℃, and the cavity is preheated with dummy material for 20 minutes before pre-forging. The transfer time is controlled at ≤80s. During heating, it is soft-wrapped with thermal insulation cotton. The bar material is placed in the pre-forging die and pre-forged in a 200MN hydraulic press. The upper and lower end surfaces of the die are padded with thermal insulation cotton to make the rough shape required for die forging.

4. The method according to claim 1, wherein Use the final forging die to perform final forging on the upside-down rough mold, including: The blank is heated to 1050~1150℃, and the cavity is preheated with dummy material for 20 minutes before final forging. The transfer time is controlled at ≤90s. Insulation cotton is used for soft wrapping during heating before forging. A 200MN hydraulic press is used for die forging, with a die preheating temperature of 300℃, a preheating time of ≥20 hours, a deformation rate of 4~10mm / s, and a deformation amount controlled at 35%~60%.

5. The method according to claim 1, wherein After obtaining the wild type, the method further comprises: Machined burrs facilitate die forging positioning.

6. The method according to claim 1, wherein After final forging the upside-down rough mold using a final forging die, the method further comprises: After forging, the forgings are heat treated.

7. The method according to claim 6, characterized in that The heat treatment system is annealing, solution treatment and aging; Annealing temperature: 1000℃, hold for 60min, then air cool. Solution temperature: 1120℃, keep warm for 60min, then air cool. Aging temperature: 900℃, insulation temperature: 240℃, dispersed air cooling.

8. The method according to claim 1, characterized in that The smaller the volume of the large head circumference, the more inclined the corresponding upper section of the blank outer circle is; the smaller the volume of the small head inner diameter, the more inclined the corresponding lower section of the blank outer circle is.

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