GH738 alloy large-wall-thickness forge piece uniform-grain forging method

Abstract

The invention belongs to the technical field of forging, and relates to a forging method for a GH738 alloy large-wall-thickness forge piece with uniform grains. The method comprises the steps that blanking is conducted, a positioning table is machined on a GH738 alloy bar, and chamfering is conducted; the bar is heated in a three-step heating mode; the three steps are as follows: the preheating temperature is 800-880 DEG C, the temperature is increased to 900-980 DEG C, and finally the temperature is increased to 1060-1120 DEG C for heat preservation; after being heated, the bar is transferred to a forming die, and a bar positioning table is in contact with the forming die so as to ensure that the blank is subjected to mold filling towards the circumference during die forging; die forging is carried out on the bar through 630 KJ counter-blow hammers by using a blank die, the first five hammers are lightly hit, follow-up continuous hit and heavy hit forming are carried out, and a forge piece is obtained; and performing heat treatment on the forge piece.

Description

Technical Field

[0001] The invention belongs to the technical field of forging, and relates to a forging method for a GH738 alloy heavy-wall forging with uniform grains. Background Art

[0002] GH738 alloy is a nickel-based high-temperature alloy hardened by precipitation hardening of γ' phase. It is widely used in the production of hot end parts such as turbine casings, turbine disks and blades of aircraft engines due to its good structural stability, gas corrosion resistance and fatigue resistance under conditions below 810℃. A certain GH738 alloy thick-walled ring forging is a load-bearing component of an aircraft engine. The grain size is required to be level 3 or finer, and it should be basically uniform, and no obvious coarse and fine grain segregation is allowed. In the early trial production process, for forgings with large wall thickness and small inner holes, the process route of upsetting, punching + horse rack expansion forming was adopted, resulting in uneven deformation of the forgings and the inability to completely recrystallize the structure, resulting in mixed crystals, coarse crystals and other structural problems in the forgings, which did not meet the standard requirements of grain size level 3 or finer and basically uniform. Summary of the invention

[0003] Purpose of the invention: To provide a forging method for GH738 alloy thick-walled forgings with uniform structure, so as to deform the circumference and end surface of the forgings as a whole and obtain forgings with uniform structure and no coarse and fine grain segregation.

[0004] Technical solution:

[0005] Provided is a forging method for a GH738 alloy thick-wall forging with uniform grains, comprising:

[0006] Cut the material and add the GH738 alloy bar machine to the positioning table and chamfer;

[0007] The bar is heated by a three-step heating method; the three steps are: preheating temperature 800-880℃, heating to 900-980℃, and finally heating to 1060-1120℃ for insulation;

[0008] After heating, transfer the bar to the tire membrane, and make the bar positioning table contact the tire mold to ensure that the blank is filled in the circumference at the same time during die forging;

[0009] The rod material is forged with a 630KJ hammer using a fetal membrane, wherein the first five hammers are light strikes, and the subsequent continuous strikes and heavy strikes are used to form the forgings;

[0010] Heat treatment of forgings.

[0011] Further, the preheating coefficient is calculated as 0.7min / mm;

[0012] Heating coefficient: calculated as 0.6min / mm;

[0013] Thermal insulation coefficient: calculated as 0.6min / mm;

[0014] No extension of time is allowed after holding at the highest temperature.

[0015] Furthermore, the total number of hammer blows is 20±3, and the total hammer blow time is 40±5".

[0016] Furthermore, the deformation amount of the die forging is controlled within a range of 56% to 65%.

[0017] Furthermore, the method further comprises:

[0018] Before heating the bar, spray or brush lubricant on the bar;

[0019] After the rod is insulated, it is wrapped with high temperature cotton for 40 minutes.

[0020] Furthermore, the heat treatment system is solution treatment + secondary aging;

[0021] The solution temperature is 1030°C, holding time is 240 min, and oil cooling is used.

[0022] The primary aging temperature is: 845℃, 240min insulation, air cooling;

[0023] The secondary aging temperature is: 760℃, keeping temperature for 960min, air cooling.

[0024] Furthermore, after the forging is heat treated, the method further comprises:

[0025] The heat-treated forgings are subjected to physical and chemical tests to detect whether the grain size meets the standard requirements.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention adopts die forging, a bar machine is equipped with a positioning table and chamfered and placed in a die, a flat die hammer is used for forging, and a 630KJ counter-hammer is used for die forging until the blank fills the cavity, and the deformation is controlled at 56% to 65%, thereby increasing the deformation of the forging, deforming the circumference and end face of the forging as a whole, and obtaining a large-walled forging with uniform structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Forging diagram.

[0029] Figure 2 Add a picture for the bar feeder.

[0030] Figure 3 This is a high-magnification tissue diagram. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below through specific embodiments:

[0032] The present invention provides a forging method for a GH738 alloy thick-walled forging with uniform grains, such as Figure 1 As shown, the cavity of the forging die includes a middle positioning portion and an outer circular cavity; the method includes the following steps:

[0033] Step 1: Cut the GH738 alloy bar and add the positioning table and chamfer it. Figure 2 As shown;

[0034] Step 2: Spray or brush lubricant on the rod before heating. The rod is heated in three steps. The preheating temperature is 800-880℃, and the insulation coefficient is calculated as 0.7min / mm. It is heated to 900-980℃, and the insulation coefficient is calculated as 0.6min / mm. Finally, the temperature is raised to 1060-1120℃, and the insulation coefficient is calculated as 0.6min / mm. After the highest temperature insulation, the time is not allowed to be extended. After insulation, high-temperature cotton wrapping is used for insulation for 40mi n; Before die forging, the bar positioning table is in contact with the die to ensure that the blank is filled in the circumference at the same time during die forging; 630KJ counter-hammer die forging is used, the die preheating temperature is 250℃~350℃, the first 5 hammers are light, and the subsequent continuous and heavy hammers are formed. The number of hammer blows is 20±3, and the hammer blow time is 40±5", until the blank fills the cavity, and the deformation is controlled at 56%~65%, increasing the deformation of the forging, so that the circumference and end surface of the forging are deformed as a whole, and a forging with uniform structure is obtained.

[0035] Step 3: After forging, the forging is heat treated. The heat treatment system is solid solution + secondary aging. The solid solution temperature is: 1030℃, heat preservation for 240min, oil cooling; the primary aging temperature is: 845℃, heat preservation for 240min, air cooling; the secondary aging temperature is: 760℃, heat preservation for 960min, air cooling, and the final forging is obtained.

[0036] Step 4: Perform physical and chemical tests on the heat-treated forgings to ensure that the grain size meets the standard requirements.

[0037] Example 1

[0038] The GH738 alloy thick-wall forging of the present invention has an outer diameter of Φ332 mm, an inner diameter of Φ202 mm, a height of 46.1 mm, and a weight of 52.9 kg. The circumference and end surface of the forging have uniform structure, the grain size meets the requirements of level 3 or finer, and there is no obvious coarse and fine grain segregation.

[0039] The manufacturing steps are detailed as follows:

[0040] 1. Cutting: sawing machine, cutting size φ230×155mm;

[0041] 2. Billet machining: according to the attachment Figure 3 Machined bar stock is positioned and chamfered to facilitate die forging positioning;

[0042] 3. Die forging: Use 630KJ counter-hammer for die forging, die preheating temperature 300℃, preheating time ≥20h, spray or brush lubricant on the bar before heating, put the bar into the electric furnace for preheating at 800℃ for 100min, heat to 960℃ for 100min, and then heat to 1100℃ for 100min. After heat preservation, use high-temperature cotton bag for 40min. During die forging, make the positioning surface of the bar contact with the die for positioning, the first 5 hammers are light, and the subsequent continuous and heavy blows are formed. The number of hammer blows is 20±3, and the hammer blow time is 40±5", until the blank fills the cavity, and the deformation is controlled at 56%~65%. Increase the deformation of the forging, make the circumference and end face of the forging deform as a whole, and obtain a forging with uniform structure.

[0043] 4. After forging, the forgings are heat treated with a heat treatment system of solid solution + secondary aging. The solid solution temperature is 1030°C, holding for 240 minutes, oil cooling; the primary aging temperature is 845°C, holding for 240 minutes, air cooling; the secondary aging temperature is 760°C, holding for 960 minutes, air cooling, and the final forgings are obtained.

[0044] 5. See the attached for the grain size results of forgings. Figure 3 .

[0045] The GH738 alloy thick-walled ring forging obtained by the forging method is tested: the inner diameter and outer diameter grain sizes of the forging are uniformly graded 5, there is no obvious coarse and fine grain segregation, and the grain size index of the forging meets the forging requirements.

Claims

1. A forging method for GH738 alloy thick-walled forgings with uniform grains, characterized in that: include: Cut the material and add the GH738 alloy bar machine to the positioning table and chamfer; The bar is heated by a three-step heating method; the three steps are: preheating temperature 800-880℃, heating to 900-980℃, and finally heating to 1060-1120℃ for insulation; After heating, transfer the bar to the tire membrane, and make the bar positioning table contact the tire mold to ensure that the blank is filled in the circumference at the same time during die forging; The rod material is forged with a 630KJ hammer using a fetal membrane, wherein the first 5 hammers are light strikes, and the subsequent continuous strikes and heavy strikes are used to form the forgings; Heat treatment of forgings.

2. The forging method according to claim 1, characterized in that: Preheating coefficient: calculated as 0.7min / mm; Heating coefficient: calculated as 0.6min / mm; Thermal insulation coefficient: calculated as 0.6min / mm; No extension of time is allowed after holding at the highest temperature.

3. The forging method according to claim 1, characterized in that: The total number of hammer blows is 20±3, and the total hammer blow time is 40±5〞.

4. The forging method according to claim 2, characterized in that: The deformation of the die forging is controlled at 56% to 65%.

5. The forging method according to claim 1, characterized in that: The method further comprises: Before heating the bar, spray or brush lubricant on the bar; After the rod is insulated, it is wrapped with high-temperature cotton for 40 minutes.

6. The forging method according to claim 1, characterized in that: The heat treatment system is solid solution + secondary aging; The solution temperature is 1030°C, holding time is 240 min, and oil cooling is used. The primary aging temperature is: 845℃, 240min insulation, air cooling; The secondary aging temperature is: 760℃, insulation for 960min, air cooling.

7. The method according to claim 1, characterized in that After heat treating the forging, the method further comprises: The heat-treated forgings are subjected to physical and chemical tests to detect whether the grain size meets the standard requirements.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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