Special-shaped forming process for forged piece of turbine case of gas turbine

Abstract

The invention relates to a special-shaped forming process for a forged piece of a turbine case of a gas turbine. The special-shaped forming process comprises the following steps: S1, preparing raw materials; step S2, blanking is carried out; s3, forging and heating; s4, forging, wherein the forging comprises the following steps: (1) upsetting and punching; (2) chambering; (3) pre-rolling for the first time; (4) pre-rolling for the second time; (5) pre-rolling for the third time; and S5, preforming, which comprises the following steps: (1) heating before forging; (2) a first punch is installed on a press, the first punch is pressed downwards, and the blank deforms in an inner hole of the forming die; (3) a third working step: a second punch is adopted, the second punch is pressed downwards, and the blank deforms in the inner hole of the forming die; fourthly, a third punch is adopted, the third punch is pressed downwards, and the blank deforms in an inner hole of the forming die; the method has the beneficial effects that the alloy can be subjected to strong plastic deformation, formation and rearrangement of grain boundaries and sub-grain boundaries are caused, a fine metallographic structure is formed, and the comprehensive mechanical property of the forge piece is strengthened.

Description

Technical Field

[0001] The invention relates to the field of turbine part forming, and in particular to a special-shaped forming process for a gas turbine turbine casing forging. Background Art

[0002] GH99 high-temperature alloy is an important metal material, widely used in aviation, aerospace, energy and other fields. It is favored for its excellent high-temperature performance, good mechanical properties and stable chemical properties. In the aviation field, it is mainly used to manufacture high-temperature parts such as engine blades, combustion chambers, turbine disks, etc. In the aerospace field, it can be used to manufacture rocket engines, satellite structural parts, etc. In the energy field, it can be used to manufacture key components of gas turbines, nuclear reactors and other equipment.

[0003] At present, the gas turbine casing of the turbine casing works at high temperature and requires sufficient creep resistance and overload tolerance during the entire service life when the rotor blade breaks. In the working state, the gas turbine casing mainly bears gas load and mass inertia force, and secondly bears thermal load and some stresses. Among them, the gas load and mass inertia force act on the casing in the form of axial force, lateral force or lateral force, bending moment, torque, etc. The thermal load is caused by temperature and temperature difference, and the stress is caused by the change of material strength caused by thermal load. Therefore, in addition to meeting the supporting function, the structural design of the casing also requires the design scheme to ensure the strength and stability requirements. The casing is a typical thin-walled part. In view of the above working conditions, its strength requirements are very high, but the current GH99 high-temperature alloy forgings cannot meet the increasingly stringent performance requirements.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention discloses a special-shaped forming process for a gas turbine turbine casing forging.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A gas turbine turbine casing forging special-shaped forming process, characterized by comprising the following steps:

[0008] Step S1, raw material preparation;

[0009] Step S2, blanking;

[0010] Step S3, forging heating: heating the blank to 950±10°C and keeping the temperature, and then heating to 1080±10°C and keeping the temperature;

[0011] Step S4, forging, includes the following steps:

[0012] (1) Upsetting and punching: The blank is upset, spun and punched in sequence, and the forging process is repeated 1 to 2 times;

[0013] (2) Hole expansion: the blank is heated to 1080±10℃ and kept warm, then the blank is expanded and forged for 1 to 2 times;

[0014] (3) First pre-rolling: the billet is heated to 1080±10℃ and kept warm, then the billet is rolled into a ring and forged once;

[0015] (4) Second pre-rolling: the billet is heated to 1080±10℃ and kept warm, then the billet is ring rolled and forged once;

[0016] (5) Third pre-rolling: the billet is heated to 950±10℃ and kept warm, then heated to 1080±10℃ and kept warm, then the billet is ring rolled and forged once;

[0017] Step S5, preforming, includes the following steps:

[0018] Prepare the fetal membrane, punch one, punch two, and punch three;

[0019] (1) Heating before forging: Heat the billet to 1080±10℃ and keep warm;

[0020] (2) Step 2: The fetal membrane is mounted on the lower anvil circular table, the blank is transferred into the fetal membrane, the punch is mounted on the press, the punch is pressed down, and the blank is deformed in the inner hole of the fetal membrane;

[0021] (3) Step 3: Use punch 2, punch 2 presses down, and the blank is deformed in the inner hole of the fetal membrane;

[0022] (4) Step 4: Use punch 3 to press down, and the blank is deformed in the inner hole of the fetal membrane;

[0023] Step S6, ring rolling, includes the following steps:

[0024] (1) Heating before forging: Heat the billet to 1080±10℃ and keep warm;

[0025] (2) The blank is transferred to the ring rolling machine and formed in two steps;

[0026] Step S7, heat treatment, including the following steps

[0027] (1) Solution treatment: Heat the forging to 1120±10℃ and keep it warm;

[0028] (2) Aging: Heat the forging to 900±10℃ and keep it warm.

[0029] Furthermore, in step S3, the insulation time ranges from 60 to 180 min in the 950±10°C stage, and from 210 to 300 min in the 1080±10°C stage.

[0030] Furthermore, in the first pre-rolling of step S4, the holding time ranges from 105 to 195 minutes, and the final forging temperature is ≥950°C.

[0031] Furthermore, in the second pre-rolling of step S4, the holding time ranges from 85 to 175 minutes, and the final forging temperature is ≥950°C.

[0032] Furthermore, in the third pre-rolling of step S4, the holding time at 950±10°C is in the range of 60 to 120 min; the holding time at 1080±10°C is in the range of 70 to 160 min; and the final forging temperature is 950°C.

[0033] Further, in step S5, the fetal membrane is arranged in a ring shape, an inner wall of the fetal membrane is provided with a sloped surface one, and the inner wall of the fetal membrane is provided with a step surface, and the step surface is located above the sloped surface one.

[0034] Furthermore, a second bevel is provided on the side of the punch one, a third bevel is provided on the side of the punch two, and a fourth bevel is provided on the side of the punch three, and the slopes of the second bevel, the third bevel and the fourth bevel increase in sequence.

[0035] Furthermore, in step (1) of step S5, the heat preservation time ranges from 60 to 150 minutes.

[0036] Furthermore, in step (1) of step S6, the holding time ranges from 60 to 150 minutes; and in step (2) of step S6, the final forging temperature of the billet is ≥ 950°C.

[0037] Furthermore, in step (1) of step S7, the heat preservation time ranges from 30 to 90 minutes; and in step (2) of step S7, the heat preservation time ranges from 240 to 250 minutes.

[0038] The beneficial effects of the present invention are as follows:

[0039] 1. The punch diaphragm is used to forge the blank to the blank shape and size requirements before ring rolling. The angle of the punch diaphragm is in line with the inner and outer diameters of the forging. Compared with the traditional rectangular rolling and subsequent machining method, there is no need to cut the blank in subsequent machining. On the one hand, the generation of waste is greatly reduced. On the other hand, during the forging deformation process, the alloy will be subjected to strong plastic deformation, resulting in the formation and rearrangement of grain boundaries and subgrain boundaries, forming a fine metallographic structure and strengthening the comprehensive mechanical properties of the forging.

[0040] 2. Before the forging is preformed, during the heating process to 1080±10℃, the elements in the alloy will gradually dissolve into the matrix to form a uniform solid solution phase. Ensuring the holding time will help the elements to fully diffuse and homogenize, and avoid excessive grain growth due to excessive holding time.

[0041] 3. Heat the alloy to a high temperature single-phase zone and maintain it at a constant temperature. Within this temperature range, the γ′ strengthening phase (such as Ni3(Al,Ti)) and most of the carbides in the alloy will dissolve in the matrix to form a uniform supersaturated solid solution, which helps to eliminate the internal stress and structural inhomogeneity generated by the alloy during casting or processing. The diffusion rate of elements in the alloy is accelerated, which is conducive to the full dissolution of the strengthening phase and carbides, helps to eliminate the component segregation and structural inhomogeneity in the alloy, makes the alloy's structure more uniform, and helps to improve the alloy's mechanical properties and corrosion resistance.

[0042] 4. At the aging temperature, Al and Ti elements will precipitate from the matrix to form fine γ' phase. These precipitated phases are evenly distributed in the matrix, which plays a role in dispersion strengthening of the alloy. The solid solution elements in the alloy, such as Co, Mo, W, etc., will also be redistributed, further optimizing the organizational structure of the alloy, helping to eliminate the organizational inhomogeneity of the alloy during the processing process, and making the organization of the alloy more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the steps of the special-shaped forming process for gas turbine turbine casing forgings.

[0044] Figure 2 Schematic diagram of the structure of the forging after pre-rolling.

[0045] Figure 3 Schematic diagram of the forming of the forging in preforming (1).

[0046] Figure 4 Schematic diagram of the forming of the forging in preforming (2).

[0047] Figure 5 Schematic diagram of the forming of the forging in preforming (3).

[0048] Figure 6 Schematic diagram of the forging forming after ring rolling.

[0049] Figure 7 Schematic diagram of forging sampling.

[0050] Figure 8 Schematic diagram of the organizational changes during the preforming process of forgings.

[0051] Fig. 9 Schematic diagram of the change of punch pressure.

[0052] Fig.10 Schematic diagram of cross-section filling of formed forgings.

[0053] Fig.11 This is a diagram showing the change in roller force during the rolling process.

[0054] Fig.12 Schematic diagram of forging structure.

[0055] In the figure: 1. fetal membrane; 2. punch one; 3. punch two; 4. punch three. DETAILED DESCRIPTION

[0056] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0057] Example:

[0058] Step S1, raw material preparation: specifically, alloy GH99 is used, and the smelting method of alloy GH99 is: vacuum induction melting and electroslag remelting.

[0059] Step S2, blanking. Blank size: φ250(+3 / -2)mm*507(+5 / 0)mm, blank weight: 211(+3 / 0)mm.

[0060] Step S3: Forging heating:

[0061] Before the billet is loaded into the furnace, the surface is brushed with an insulation layer. The billet temperature is ≤850℃. First, the billet is heated to 950±10℃ for insulation, and the insulation time ranges from 60 to 180 minutes. Then the temperature is raised to 1080±10℃ for insulation, and the insulation time ranges from 210 to 300 minutes.

[0062] Step S4, forging, includes the following steps:

[0063] (1) Upsetting and punching:

[0064] First, preheat the tooling, the tooling temperature range is 250 ~ 350 ℃.

[0065] The blank is upset to a height of 260mm, then spun to a height of 220mm, and finally punched with an inner hole diameter of φ140mm. The final forging temperature of the blank is ≥950℃, and the forging times are 1 to 2 times.

[0066] (2) Hole expansion:

[0067] Preheat the expansion tooling in advance, the tooling preheating temperature range is 250 ~ 350 ℃.

[0068] The forging temperature entering the furnace is ≤850℃, heated to 1080±10℃, and the holding time ranges from 100min to 190min.

[0069] After the forging is heated, the forging hole is expanded to Φ430±10mm×Φ220±10mm×220±3mm. The final forging temperature is guaranteed to be ≥950℃. The pressing amount is controlled, and the pressing amount per hammer is ≤50mm. The forging is controlled to be 1 to 2 times.

[0070] (3) First pre-rolling:

[0071] Before the forgings are loaded into the furnace, they are coated with protective agent on their surface and then wrapped before being put into the furnace for heating.

[0072] Preheat the tooling mold, the tooling mold temperature range is 250 ~ 350 ℃.

[0073] The billet is heated to 1080±10℃ and kept warm for 105~195min. Then the forging is transferred to the forging machine and the transfer time is controlled within 90s.

[0074] The blank is rolled into a ring, the pre-rolled size of the forging is: Φ495±5mm×Φ330±5mm×220±3mm, and the forging fire is 1 time. The final forging temperature is ≥950℃.

[0075] (4) Second pre-rolling:

[0076] Before the forgings are loaded into the furnace, they are coated with protective agent on their surface and then wrapped before being put into the furnace for heating.

[0077] Preheat the tooling mold, the tooling mold temperature range is 250 ~ 350 ℃.

[0078] The billet is heated to 1080±10℃ and kept warm for 85 to 175min. The forging is then transferred to the forging machine and the transfer time is controlled within 90s.

[0079] The blank is rolled into a ring, the pre-rolled size of the forging is: Φ590±5mm×Φ460±5mm×220±3mm, and the forging fire is 1 time. The final forging temperature is ≥950℃.

[0080] (5) The third pre-rolling:

[0081] Before the forgings are loaded into the furnace, they are coated with protective agent on their surface and then wrapped before being put into the furnace for heating.

[0082] Preheat the tooling mold, the tooling mold temperature range is 250 ~ 350 ℃.

[0083] The billet is heated to 950±10℃ and kept warm for 60 to 120 minutes, and then the forging is heated to 1080±10℃ and kept warm for 70 to 160 minutes. The forging is then transferred to the forging machine, and the transfer time is controlled within 90 seconds.

[0084] Billet rolled ring, forging pre-rolled size: Φ725±5mm×Φ600±5mm×210±5mm, forging cross-section shape as Figure 2 shown.

[0085] Step S5, preforming, includes the following steps:

[0086] Prepare fetal membrane 1, punch one 2, punch two 3 and punch three 4.

[0087] (1) Heating before forging: Heat the billet to 1080±10℃ and keep it warm for 60 to 150 minutes.

[0088] (2) Step 2: Figure 3 As shown, the fetal membrane 1 is installed on the lower anvil circular table, the blank is transferred into the fetal membrane, the punch 2 is installed on the press, the punch 2 is pressed down, and the blank is deformed in the inner hole of the fetal membrane 1.

[0089] (3) Step 3: Figure 4 As shown, the punch 2 3 is replaced on the press, and the punch 2 3 is pressed down, and the blank is deformed in the inner hole of the fetal membrane 1.

[0090] (4) Step 4: Figure 5 As shown, the punch 3 4 is replaced on the press, and the punch 3 4 is pressed down, and the blank is deformed in the inner hole of the tire membrane 1. And the side slopes of the punch 1 2, the punch 2 3 and the punch 3 4 are gradually increased, and a plurality of different steps are formed on the inner wall of the inner hole of the forging according to the shape of the side of the punch.

[0091] Step S6, ring rolling, includes the following steps:

[0092] (1) Heating before forging:

[0093] Coating package: Before loading into the furnace, apply protective agent on the surface of the blank, apply it twice, and then put it into the furnace for heating.

[0094] The blank is heated to 1080±10℃ and kept warm for 60 to 150 minutes.

[0095] (2) The blank is transferred to the ring rolling machine and formed in two steps to ensure that the final forging temperature of the blank is ≥950℃.

[0096] Preheat the mold before forging, the mold temperature range is 250~350℃.

[0097] In the first fire, the outer diameter of the forging is rolled to Φ950mm, and in the second fire, the forging is rolled to the target size.

[0098] After the final ring rolling, the preformed shape of the forging is as follows Figure 6 shown.

[0099] Step S7, heat treatment, includes the following steps:

[0100] (1) Solid solution:

[0101] The forging temperature entering the furnace is ≤750℃, the forging is heated to 1120±10℃, the holding time ranges from 30 to 120min, and finally the forging is air-cooled.

[0102] (2) Time limit:

[0103] The forging temperature entering the furnace is ≤750℃, the forging is heated to 900±10℃, the holding time ranges from 240 to 250min, and finally the forging is air-cooled.

[0104] Finally, the forgings are sampled and the sampling position is as follows: Figure 7 shown.

[0105] Forging preform support simulation test:

[0106] Forging deformation process Figure 8 As shown, during the deformation process, the forging is fully deformed and there is no excessive stress concentration at the bending deformation.

[0107] Punch forming force curve Fig. 9 As shown, the forming force of each punch varies evenly.

[0108] Formed ring cross section simulates filling effect:

[0109] like Fig.10 As shown, the forging fully fills the space between the punches of the fetal membrane.

[0110] like Fig.11 As shown in the figure, the stress of each roller during the rolling process did not fluctuate greatly.

[0111] From the examples, the chemical composition and mechanical properties of the samples were tested. Details are shown in Table 1

[0112]

[0113] Table 1

[0114] Test result analysis:

[0115] 1. The chemical composition of the sample meets the design requirements.

[0116] 2. At room temperature, the tensile strength and yield strength of the sample exceed the standard, the elongation exceeds the standard by nearly twice, and it has a good cross-sectional shrinkage rate.

[0117] 3. At high temperature (800℃), the tensile strength of the sample exceeds the standard by nearly 100 MPa, the elongation exceeds nearly 2 times, and it has a good cross-sectional shrinkage rate.

[0118] 4. Under high temperature conditions of 800℃, the forging did not break within 50 hours, and the maximum heating time was 159 hours.

[0119] In summary, the forging specimens have excellent room temperature mechanical properties and high temperature mechanical properties, which indirectly proves that the forging microstructure is uniformly distributed.

[0120] Forging structure inspection:

[0121] Forging structure Fig.12 As shown, there is no coarse-grained or mixed-grained structure in the forging, and no defects such as cracks are found.

[0122] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A process for forming a gas turbine casing forging with a special shape, characterized in that: The following steps are involved: Step S1, raw material preparation; Step S2, blanking; Step S3, forging heating: heating the blank to 950±10°C and keeping the temperature, and then heating to 1080±10°C and keeping the temperature; Step S4, forging, includes the following steps: (1) Upsetting and punching: The blank is upset, spun and punched in sequence, and the forging process is repeated 1 to 2 times; (2) Hole expansion: the blank is heated to 1080±10℃ and kept warm, then the blank is expanded and forged for 1 to 2 times; (3) First pre-rolling: the billet is heated to 1080±10℃ and kept warm, then the billet is rolled into a ring and forged once; (4) Second pre-rolling: the billet is heated to 1080±10℃ and kept warm, then the billet is ring rolled and forged once; (5) Third pre-rolling: the billet is heated to 950±10℃ and kept warm, then heated to 1080±10℃ and kept warm, then the billet is ring rolled and forged once; Step S5, preforming, includes the following steps: Prepare the fetal membrane, punch one, punch two, and punch three; (1) Heating before forging: Heat the billet to 1080±10℃ and keep warm; (2) Step 2: The fetal membrane is mounted on the lower anvil circular table, the blank is transferred into the fetal membrane, the punch is mounted on the press, the punch is pressed down, and the blank is deformed in the inner hole of the fetal membrane; (3) Step 3: Use punch 2, punch 2 presses down, and the blank is deformed in the inner hole of the fetal membrane; (4) Step 4: Use punch 3 to press down, and the blank is deformed in the inner hole of the fetal membrane; Step S6, ring rolling, includes the following steps: (1) Heating before forging: Heat the billet to 1080±10℃ and keep warm; (2) The blank is transferred to the ring rolling machine and formed in two steps; Step S7, heat treatment, including the following steps (1) Solution treatment: Heat the forging to 1120±10℃ and keep it warm; (2) Aging: Heat the forging to 900±10℃ and keep it warm.

2. A gas turbine turbine casing forging special-shaped forming process according to claim 1, characterized in that: In step S3, the insulation time ranges from 60 to 180 min at the 950±10°C stage, and from 210 to 300 min at the 1080±10°C stage.

3. A gas turbine turbine casing forging special-shaped forming process according to claim 1, characterized in that: In the first pre-rolling of step S4, the holding time ranges from 105 to 195 minutes, and the final forging temperature is ≥950°C.

4. A gas turbine turbine casing forging special-shaped forming process according to claim 1, characterized in that: In the second pre-rolling of step S4, the holding time ranges from 85 to 175 minutes, and the final forging temperature is ≥950°C.

5. The process for forming a gas turbine casing forging according to claim 1, characterized in that: In the third pre-rolling of step S4, the holding time ranges from 60 to 120 minutes at the 950±10°C stage; the holding time ranges from 70 to 160 minutes at the 1080±10°C stage; and the final forging temperature is 950°C.

6. A gas turbine turbine casing forging special-shaped forming process according to claim 1, characterized in that: In step S5, the fetal membrane is arranged in a ring shape, an inner wall of the fetal membrane is provided with a sloped surface one, and the inner wall of the fetal membrane is provided with a step surface, and the step surface is located above the sloped surface one.

7. A gas turbine turbine casing forging special-shaped forming process according to claim 6, characterized in that: The side surface of the punch one is provided with a second bevel, the side surface of the punch two is provided with a third bevel, and the side surface of the punch three is provided with a fourth bevel, and the slopes of the second bevel, the third bevel and the fourth bevel increase in sequence.

8. The process for forming a gas turbine casing forging according to claim 1, characterized in that: In step (1) of step S5, the holding time ranges from 60 to 150 minutes.

9. A gas turbine turbine casing forging special-shaped forming process according to claim 1, characterized in that: In step (1) of step S6, the holding time ranges from 60 to 150 minutes; in step (2) of step S6, the final forging temperature of the billet is ≥ 950°C.

10. A process for forming a gas turbine casing forging with a special shape according to claim 1, characterized in that: In step (1) of step S7, the holding time ranges from 30 to 90 minutes; in step (2) of step S7, the holding time ranges from 240 to 250 minutes.

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