A method for preparing a GH4738 alloy ring forging with uniform grains

Abstract

The application discloses a preparation method of a GH4738 alloy ring forge piece with uniform grains, and comprises the following steps: step (1), sawing GH4738 bars and sampling to perform a gamma phase full solution temperature test; step (2), heating and heat preservation; step (3), upsetting and punching the bar blank to form a ring blank 1; step (4), heating and heat preservation; step (5), hole expanding of a mandrel and a mandrel holder to obtain a ring blank 2; step (6), heating and heat preservation; step (7), breaking to a ring blank 3; step (8), heating to a gamma phase solution temperature and heat preservation; and step (9), ring rolling of a plurality of heating and small deformation times to form a shaped ring blank 4, namely a forge piece. The method of high-temperature large deformation blanking, low-temperature small deformation pre-rolling and three times of heating at a gamma phase solution temperature and small deformation final rolling is adopted to produce the GH4738 special-shaped machine case ring forge piece, and the problems of forging cracking, non-uniform grain size, large mechanical property fluctuation, creep exceeding the standard, ultrasonic flaw detection exceeding the standard and deformation in a machining process of the GH4738 special-shaped machine case ring forge piece are solved.

Description

TECHNICAL FIELD

[0001] The application relates to a GH4738 alloy ring forging grain uniformity preparation method and belongs to the field of aviation part forging technology. BACKGROUND

[0002] GH4738 alloy is a precipitation-strengthened nickel-based high-temperature alloy, and the alloy is characterized by large deformation resistance, narrow deformation temperature range and poor plasticity compared with general alloys, and the alloy has great difficulty in forming process. Since the alloying degree of the GH4738 alloy is relatively high, the grain size and mechanical properties of the forging are very sensitive to the forging process parameters, and the grain size will directly affect the mechanical properties of the forging, and the grain size uniformity of the GH4738 alloy rectangular ring forging is difficult to control, and the special-shaped engine case ring forging has more mixed grains or coarse grains if produced according to the traditional process.

[0003] The traditional process method of the GH4738 alloy rectangular and special-shaped ring forging is high-temperature large deformation blanking + high-temperature large deformation ring rolling.

[0004] The process method has the following shortcomings:

[0005] 1. The grain size uniformity is unstable, mixed grains or coarse grains exist, and the requirement that the grain size difference is less than or equal to 2 levels is not met;

[0006] 2. The mechanical properties fluctuate greatly, and the creep exceeds the standard;

[0007] 3. The deformation exists in the machining of the part, and the part cannot be used;

[0008] 4. The water immersion method ultrasonic flaw detection exceeds the standard, and the requirement that the low wave loss is not more than 6 dB is not met;

[0009] 5. The forging cracks during forging, the size is out of tolerance or scrapped. SUMMARY

[0010] The technical problem to be solved by the application is to provide a GH4738 alloy ring forging grain uniformity preparation method to solve the problems in the prior art.

[0011] The technical scheme adopted by the application is as follows: a GH4738 alloy ring forging grain uniformity preparation method, comprising the following steps:

[0012] Step (1): sawing GH4738 bars according to certain blanking specifications, and sampling for gamma phase full solution temperature test;

[0013] Step (2): heating the sawed GH4738 bar blank to high temperature 1060-1100 DEG C by using an electric furnace, and the holding time is: effective thickness of the bar blank x 6 min / 10 mm;

[0014] Step (3): the heated and kept warm GH4738 bar blank is upset and punched to form a ring blank 1;

[0015] Step (4): the ring blank 1 is heated to low temperature 1010-1040℃ by using an electric furnace, and the holding time is: the effective thickness of the ring blank 1 x 6 min / 10 mm;

[0016] Step (5): the ring blank 1 is expanded to a ring blank 2 by using a mandrel and a mandrel expanding device through multiple times of small deformation;

[0017] Step (6): the ring blank 2 is heated to low temperature 1010-1040℃ by using an electric furnace, and the holding time is: the effective thickness of the ring blank 2 x 6 min / 10 mm;

[0018] Step (7): the ring blank 2 is shaped to a ring blank 3 by using a special-shaped blanking die and a blanking device through multiple times of small deformation;

[0019] Step (8): the ring blank 3 is heated to the γ phase dissolution temperature by using an electric furnace, and the holding time is: the effective thickness of the ring blank 3 x 6 min / 10 mm;

[0020] Step (9): the ring blank 3 is ring-rolled to a formed ring blank 4, i.e. a forged piece, by using a special-shaped ring rolling die and a ring rolling device through multiple times of small deformation.

[0021] Preferably, the GH4738 bar blank in the step (1) is made of raw materials in the following mass ratio: C 0.02-0.10%, Cr 18.0-21.0%, Co 12.0-15.0%, Mo 3.50-5.00%, Ti 2.75-3.25%, Al 1.20-1.60%, Zr 0.02-0.08%, B 0.003-0.010%, Mn ≤0.10%, Si ≤0.15%, P ≤0.015%, S ≤0.015%, Fe ≤2.0%, Cu ≤0.10%, Pb ≤0.0005%, Bi ≤0.00003%, Se ≤0.0003%, Ag ≤0.00005%, and the rest is Ni.

[0022] Preferably, the grain size level of the ring blank 4 is 3-4 levels.

[0023] Preferably, the γ phase dissolution temperature is the third γ phase dissolution temperature, and the range is 1040-1050℃.

[0024] Preferably, in the upsetting and punching process for preparing the ring blank 1 in the step (3), there are 1-2 times of heating, and the deformation amount of each time is 30-35%.

[0025] Preferably, in the mandrel expanding process for preparing the ring blank 2 in the step (5), there are 13-18 times of heating, and the deformation amount of each time is 10-12%.

[0026] Preferably, the step (7) is prepared by 3-6 times of ring blank 3 in the process of profiled membrane profile preparation, and the deformation amount of each time is 12-15%.

[0027] Preferably, the step (9) is prepared by 1-3 times of ring blank 4 in the process of profiled die ring rolling, and the deformation amount of each time is 8-10%.

[0028] The beneficial effects of the present application: compared with the prior art, the present application adopts the method of high temperature large deformation billet + low temperature small deformation pre-rolling + three times of γ phase dissolution temperature heating small deformation finish rolling to produce GH4738 profiled machine ring forgings, and the forgings are subjected to ultrasonic flaw detection, and no abnormal display is found after detection. The forgings are subjected to ultrasonic flaw detection according to the contact method of AMS-STD-2154, and are accepted according to AA level. The grain of the forgings is relatively uniform, which is 3-4 level, and no obvious fine grain zone and coarse grain zone segregation is found. The present application solves the problems of forging cracking of GH4738 profiled machine ring forgings, and solves the problems of uneven grain size of GH4738 profiled machine ring forgings, large fluctuation of mechanical properties, creep exceeding and ultrasonic flaw detection exceeding. The present application solves the problem of deformation of GH4738 profiled machine ring forgings during machining to parts. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a cross-sectional view of ring blank 3;

[0030] Figure 2 It is a cross-sectional view of ring blank 4;

[0031] Figure 3 It is a grain size photo of position 1 of the forgings;

[0032] Figure 4 It is a grain size photo of position 2 of the forgings;

[0033] Figure 5 It is a grain size photo of position 3 of the forgings;

[0034] Figure 6 It is a grain size photo of position 4 of the forgings;

[0035] Figure 7 It is a grain size photo of position 5 of the forgings;

[0036] Figure 8 It is a grain size photo of position 6 of the forgings;

[0037] Figure 9 It is a grain size photo of position 7 of the forgings;

[0038] Figure 10 It is a grain size photo of position 8 of the forgings;

[0039] Figure 11 Grain size photograph of position 9 of the forged piece. DETAILED DESCRIPTION

[0040] The application will be further described below in conjunction with the accompanying drawings and specific examples.

[0041] Example 1:

[0042] A method for preparing a GH4738 alloy ring forged piece with uniform grains, comprising the following steps:

[0043] Step (1): sawing GH4738 bars according to a certain blanking specification, and sampling for γ phase solubility temperature test;

[0044] Step (2): heating the sawed GH4738 bar blank to a high temperature of 1100℃ using an electric furnace, and the holding time is: effective thickness of the bar blank x 6 min / 10 mm;

[0045] Step (3): upsetting and punching the heated and held GH4738 bar blank to form a ring blank 1;

[0046] Step (4): heating the ring blank 1 to a low temperature of 1020℃ using an electric furnace, and the holding time is: effective thickness of the ring blank 1 x 6 min / 10 mm;

[0047] Step (5): expanding the ring blank 1 to a ring blank 2 through multiple times of small deformation using a mandrel and a mandrel expander;

[0048] Step (6): heating the ring blank 2 to a low temperature of 1020℃ using an electric furnace, and the holding time is: effective thickness of the ring blank 2 x 6 min / 10 mm;

[0049] Step (7): breaking the shape of the ring blank 2 to a ring blank 3 through multiple times of small deformation using a special-shaped blanking die and blanking equipment;

[0050] Step (8): heating the ring blank 3 to the γ phase solubility temperature using an electric furnace, and the holding time is: effective thickness of the ring blank 3 x 6 min / 10 mm;

[0051] Step (9): ring rolling the ring blank 3 to a formed ring blank 4, i.e. a forged piece, through multiple times of small deformation using a special-shaped ring rolling die and ring rolling equipment.

[0052] In step (1), the chemical composition mass (%) standard of the GH4738 bar blank raw material and the reinspection results of each element of the forged piece in this example are shown in Table 1:

[0053] Table 1: GH4738 chemical composition mass (%) standard and reinspection results of each element of the forged piece in this example

[0054]

[0055] From Table 1, it can be seen that the raw material ratio of the forging in the embodiment meets the standard requirements.

[0056] In the table, the forging heating temperature, deformation, blank size and fire times of each process are shown in Table 2:

[0057] Table 2 Forging heating temperature, deformation, blank size and fire times of each process

[0058]

[0059] Grain size and mechanical property test of the forging:

[0060] Table 3 Room temperature tensile and hardness test results

[0061]

[0062] Table 4 High temperature durability test results

[0063]

[0064] Ultrasonic flaw detection: no abnormal display was found in the detection, the forgings were subjected to ultrasonic flaw detection according to the contact method of AMS-STD-2154, and were accepted according to AA level.

[0065] Grain size: the grain of the forging is relatively uniform, the grain size level is 3-4, and no obvious fine grain zone and coarse grain zone segregation is found, see Table 5 and Figures 3-11 .

[0066] Table 5 Forging grain size test results

[0067]

[0068] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application, therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of making a GH4738 alloy ring forge piece with uniform grain structure, the method comprising: Comprising the following steps: ​ Step 1: The GH4738 bar is sawed according to a certain blanking specification, and a sample is taken for gamma phase full dissolution temperature test; Step 2: The sawed GH4738 bar blank is heated to a high temperature of 1060-1100 DEG C by an electric furnace, and the holding time is: the effective thickness of the bar blank x 6 min / 10 mm; Step 3: The GH4738 bar blank heated and held is upset and punched to form a ring blank 1, a total of 1-2 heating times, and the deformation amount of each heating time is 30-35%; Step 4: The ring blank 1 is heated to a low temperature of 1010-1040 DEG C by an electric furnace, and the holding time is: the effective thickness of the ring blank 1 x 6 min / 10 mm; Step 5: The ring blank 1 is expanded by a plurality of heating times of small deformation by a mandrel and a mandrel expansion device to form a ring blank 2, a total of 13-18 heating times, and the deformation amount of each heating time is 10-12%; Step 6: The ring blank 2 is heated to a low temperature of 1010-1040 DEG C by an electric furnace, and the holding time is: the effective thickness of the ring blank 2 x 6 min / 10 mm; Step 7: The ring blank 2 is formed into a ring blank 3 by a plurality of heating times of small deformation by a special-shaped blanking die and blanking equipment, a total of 3-6 heating times, and the deformation amount of each heating time is 12-15%; Step 8: The ring blank 3 is heated to a gamma phase dissolution temperature by an electric furnace, the gamma phase dissolution temperature is the third gamma phase dissolution temperature, the temperature is 1040-1050 DEG C, and the holding time is: the effective thickness of the ring blank 3 x 6 min / 10 mm; Step 9: The ring blank 3 is ring-rolled by a special-shaped ring rolling die and a ring rolling device to form a ring blank 4, i.e. a forged piece, a total of 1-3 heating times in the process of forming the ring blank 4 by special-shaped die ring rolling, and the deformation amount of each heating time is 8-10%, and the grain size grade of the ring blank 4 is 3-4; The GH4738 bar in the step 1 is made of raw materials in the following mass ratio: C 0.02-0.10%, Cr 18.0-21.0%, Co 12.0-15.0%, Mo 3.50-5.00%, Ti 2.75-3.25%, Al 1.20-1.60%, Zr 0.02-0.08%, B 0.003-0.010%, Mn ≤0.10%, Si ≤0.15%, P ≤0.015%, S ≤0.015%, Fe ≤2.0%, Cu ≤0.10%, Pb ≤0.0005%, Bi ≤0.00003%, Se ≤0.0003%, Ag ≤0.00005%, and the rest is Ni. ​

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