Forging forming method for high-temperature alloy blade of large gas turbine

Abstract

The forging forming method for the high-temperature alloy blade of the large gas turbine is suitable for controlling thermal deformation in the blade machining process and comprises the steps that S1, a high-temperature alloy blank is selected, and the blank is subjected to rough turning machining according to the design requirement of the blade so that a bar with end fillets can be formed at the two ends; s2, the bar is subjected to upset forging heating and formed at a time through an upset forging die, and an upset-forged blank is formed; s3, according to design requirements, a lower tenon and a blade body of the upset blank are subjected to turn-milling machining to the target size, a glass lubricant is sprayed, and heating is conducted; s4, a small head of the heated upset blank is flattened in a flattening cavity of a pre-forging die, then the blank is turned over by 90 degrees, a blade body is flattened in the pre-forging cavity, and a blank piece is formed; s5, oxide skin on the surface of the blank is removed, a lubricating agent is sprayed, and it is guaranteed that the surface of the blank is smooth; s6, forming leaves; and S7, the blade is subjected to deburring, heat treatment and sand blasting treatment and is detected, and the machining efficiency of the blade is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of gas turbine blade forging, and particularly relates to a forging forming method for a large gas turbine high-temperature alloy blade. BACKGROUND

[0002] A certain gas turbine blade selects GH2132 alloy material. The alloy is strengthened by aging and precipitating intermetallic compound gamma' phase (Ni3AlTi), and has good comprehensive performance after solid solution aging, such as high yield strength, good hot hardness, high creep strength and a series of advantages, and is applied to high-temperature load-bearing components. In the hot working process, the strengthening phase inhibits the migration of the grain boundary, so that the recrystallized grain size can be refined. If the processing temperature is too high, the strengthening phase will dissolve, the inhibitory effect will disappear, and the recrystallized grain will easily coarsen. Even if large plastic deformation processing is used, it is also difficult to refine the grain again, thereby greatly reducing the comprehensive performance of the alloy; if the forging temperature is too low, the η phase is easily precipitated in the grain, which can significantly reduce the impact performance, yield strength and high-temperature mechanical properties of the material. At the same time, when the forging temperature is too low, the plasticity of the alloy is reduced, and thus the deformation resistance is increased, which ultimately leads to uneven deformation and reduces the processing efficiency.

[0003] Therefore, the present application is proposed. SUMMARY

[0004] The purpose of the present application is to provide a forging forming method for a large gas turbine high-temperature alloy blade, which can improve the processing efficiency of the high-temperature alloy blade. The technical solution of the present application has many technical advantages, which are described below: A forging forming method for a large gas turbine high-temperature alloy blade, which is suitable for the forging process of a large gas turbine high-temperature alloy blade, and the method comprises the following steps: S1: selecting a high-temperature alloy blank, and rough turning the blank to form a rod material with end fillets at both ends according to the blade design requirements; S2: the rod material is heated and formed by a top forging die in one step to form a top-forged blank; S3: the lower tenon and the blade body of the top-forged blank are respectively turned and milled to the target size according to the design requirements, and a glass lubricant is sprayed and heated; S4: the heated top-forged blank is clamped in the small head of the pre-forging die cavity, then turned 90° and clamped in the blade body in the pre-forging cavity to form a rough piece; S5: removing the oxide skin on the surface of the rough piece, and spraying a lubricant to ensure the smoothness of the surface of the rough piece; S6: the forging is put into a high-temperature electric furnace, preheated at 825±10 DEG C for 70-120 min, then kept at 1050±10 DEG C for 26-60 min, the pre-forging is taken out of the electric furnace, and final forming is carried out in the final forging die cavity, the stop-forging temperature is ensured, the time from the pre-forging being taken out of the electric furnace to the stop-forging is less than or equal to 15 s, if the die forging cannot be completed within 15 s, the pre-forging needs to be reheated for 5 min and then the die forging is carried out, until the blade is formed; S7: the blade is deburred, heat treated, sand blasted, and detected.

[0005] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects: The method of the present application adopts a multi-stage forging process, different temperatures are adopted in each link, in order to ensure that the strengthening phase is dissolved in the matrix, reduce the deformation resistance, prevent the heating time from being too long, the grains from being overburned or abnormally grown, refine the grains and improve the structure, meanwhile, the uniformity of the final forging forming force and the material deformation amount can be ensured through improving the pre-forging process, and finally the forged piece with qualified shape and performance is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0006] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0007] Fig. 1 It is a schematic diagram of the top forging in the method of the present application; Fig. 2 It is a schematic diagram of the pre-forging in the method of the present application; Fig. 3 It is a schematic diagram of the final forging in the method of the present application. DETAILED DESCRIPTION

[0008] The embodiments of the present application will be described below through specific concrete examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure. Obviously, the described embodiments are only some of the embodiments of the present application, not all. The present application can also be implemented or applied through other different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0009] It is to be understood that the embodiments described herein are illustrative of only a few of the many aspects of the present application. It is to be understood that the aspects described herein can be implemented in a wide variety of forms and that any particular structure and / or function described herein is merely illustrative. An aspect described herein as being implemented in any specific form can be implemented in a different form; thus, any recitation of an aspect hereof as being implemented in a specific form is not a disclaimer of aspects that can be implemented in other forms. The applicants will elect to concentrate on their preferred or alternative aspects of the aspects described herein and / or focus on addressing particular problems and are therefore not using their best mode for the remainder. It is therefore to be understood that there is no intent to freely merge aspects of the application that are disclosed herein with any other aspects to create new aspects, but to the contrary, it is the intent of the applicants that the aspects of the application that are disclosed herein in the manner that the application can only be practiced under the claims.

[0010] It is also to be understood that the drawings provided herein are merely schematic and that the dimensions of the various components are not necessarily to scale, and that actual dimensions can depend on specific application requirements.

[0011] In addition, in the following description, specific details are provided to thoroughly understand examples. However, one of ordinary skill in the art will understand that aspects can be practiced without these specific details. In order to better understand the present application scheme, the present application is further described in detail below in conjunction with the drawings and specific embodiments. The terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can be explicitly or implicitly included one or more features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0012] GH2132 alloy material is sensitive to hot working process parameters, improper process control will produce coarse grain, mixed crystal and other phenomena, and then affect the mechanical properties such as the notched sensitivity and impact toughness of the forging. And the blade is one of the key parts on the gas turbine, the size precision, surface quality, internal organization and streamline distribution of the forging are all high, so it is particularly important to control the forging process parameters, but there is no mature large gas turbine high-temperature alloy blade hot forging process in China at present, the multi-stage forging process provided by the present application can improve the processing efficiency, such as Figs. 1 to 3 As shown in the large gas turbine high-temperature alloy blade forging forming method, it is suitable for controlling the forging process of the large gas turbine high-temperature alloy blade, and the method comprises, S1: Selecting a blank of high-temperature alloy (GH2132 high-temperature alloy), rough turning the blank according to the blade design requirements to form a bar with end fillets at both ends, for example, the length tolerance is controlled within ±1, then rough turning the blank to ensure that the size of the end fillets at both ends is R5±1; S2: Referring to Fig. 1 , the bar is heated and formed by a top forging die to form a top forging blank. The top forging heating includes selecting a high-temperature electric furnace with a temperature error of ±10℃, preheating at 825±10℃ for 60-120min, then keeping at 1050±10℃ for 22-55min, and forming by a top forging die to meet the size requirements. The time from furnace discharge to stop forging is ≤30s, which ensures uniform heating of the high-temperature alloy blank and prevents grain growth.

[0013] S3: Referring to Fig. 2 , the tenon and the blade body of the top forging blank are respectively turned and milled to the target size according to the design requirements, and are sprayed with glass lubricant and heated. The purpose is to reasonably allocate the metal volume based on the principle of constant volume. Specifically, Spraying glass lubricant and heating includes cleaning the top forging piece after turning and placing it in an oven, heating to 80-150℃ for a preset time according to the heating requirements in the glass lubricant coating process, then spraying high-temperature alloy lubricant: GDS-17, and naturally drying after spraying for ≥3h; The sprayed top forging piece is placed in a high-temperature electric furnace, preheated at 825±10℃ for 50-120min, then kept at 1050±10℃ for 22-55min. The purpose is to ensure that the strengthening phase is dissolved in the matrix and further reduce the deformation resistance, but also to prevent the alloy from overburning. Select the appropriate heating temperature; set the preheating to prevent the surface temperature of the forging piece from being too high, ensure uniform heating of the forging piece, and set the heating time range to prevent the heating time from being too long, causing grain overburning or abnormal grain growth.

[0014] S4: The heated top forging blank is clamped in the small head of the pre-forging die cavity, then turned 90° and clamped in the blade body in the pre-forging cavity to form a rough piece; S5: Removing the oxide skin on the surface of the rough piece and spraying lubricant to ensure the smoothness of the surface of the rough piece. Specifically, Manually sandblasting the rough piece to remove the surface oxide skin; Cleaning the sandblasted rough piece and placing it in an oven, heating to 80-150℃ for a period of time according to the heating requirements in the glass lubricant coating process, then spraying high-temperature alloy lubricant: GDS-17, and naturally drying after spraying for ≥3h to ensure the smoothness of the surface of the forging piece to reduce friction.

[0015] S6: The forging is put into a high-temperature electric furnace, preheated at 825±10℃ for 70-120 minutes, and then kept at 1050±10℃ for 26-60 minutes. The pre-forging is taken out of the electric furnace, see Fig. 3 The final forming (die forging) is performed in the final forging die, the stop-forging temperature is ensured, and the time from the pre-forging to the stop-forging is ≤15s. If the die forging cannot be completed within 15s, the pre-forging needs to be reheated for 5 minutes and then the die forging is performed until the blade is formed. The purpose is to more accurately allocate the volume of the blank by the pre-forging, refine the grain and improve the structure, ensure the uniformity of the final forging forming force and the material deformation amount by improving the pre-forging process, affect the final microstructure of the forging, and make the forging completely fill the cavity and have a reasonable deformation amount, refine the grain structure, and finally obtain a forging with qualified shape and performance.

[0016] S7: The blade is deburred, heat treated, sandblasted, and detected, specifically, The blade edge is removed by mechanical processing, and each side of the blade body is ≤3mm, and the rest is allowed to be ≤1.2mm; The blade is subjected to solid solution heat treatment, oil cooling is used for solid solution, and air drying or drying is used for oil removal after oil cooling. The hardness after heat treatment is ensured to be HB=277-352; The blade is manually sandblasted to remove the surface oxide scale.

[0017] Example This embodiment takes a large gas turbine blade forging as an example. The sawing bed used is a common sawing bed, the top forging equipment used is an 800T flat forging machine, the pre-forging equipment is a 1250T flat forging machine, and the final forging equipment is a 2500T electric screw press.

[0018] 1. Cutting: Select qualified GH2132 bar stock, and cut the size to φ55×312±1. Then rough turn the blank to ensure that the round corner size at both ends is R5±1.

[0019] 2. Top forging heating: To ensure uniform heating of the high-temperature alloy blank and prevent grain growth, preheat at 825±10℃ for 62-75 minutes, and then keep at 1050±10℃ for 23-43 minutes.

[0020] 3. Top forging: After the blank is heated, it is formed by a top forging die on an 800T flat forging machine. The time from the pre-forging to the stop-forging is 21s.

[0021] 4. Turning: The head part of the blank after top forging, i.e. the lower tenon forming part, and the middle rod part, i.e. the blade body forming part, are respectively turned to φ48 and φ40, and are smoothly connected with the adapter disc.

[0022] 5. Lubricant coating: clean the upset piece after machining and place it in the oven, heat to 140°C for a period of time according to the heating requirements in the glass lubricant coating process, then spray high-temperature alloy lubricant GDS-17, and naturally dry after spraying for 3h10min.

[0023] 6. Pre-upset heating: place the lubricant-coated upset piece in a high-temperature electric furnace, preheat at 825±10°C for 75-86min, then heat at 1050±10°C for 23-28min.

[0024] 7. Pre-upset: take the upset piece out of the electric furnace, clamp the small head in the clamping cavity of the pre-upset die on the 1250T flat forging machine, and deform the small head by 17%, then flip it by 90°, clamp the blade in the pre-upset cavity, and deform the blade by 35%, and the time from ejection to stop forging is 12s to ensure the stop forging temperature.

[0025] 8. Sand blasting: manually sand blast the pre-upset piece to remove the surface oxide scale.

[0026] 9. Lubricant coating: clean the sand-blasted pre-upset piece and place it in the oven, heat to 140°C for a period of time according to the heating requirements in the glass lubricant coating process, then spray high-temperature alloy lubricant GDS-17, and naturally dry after spraying for 3h10min.

[0027] 10. Final forging heating: place the lubricant-coated pre-upset piece in a high-temperature electric furnace, preheat at 825±10°C for 70-113min, then heat at 1050±10°C for 31-40min.

[0028] 11. Final forging: take the pre-upset piece out of the electric furnace, and finally shape it in the final forging die cavity on the 2500T press, with a deformation of the tenon of 24% and a deformation of the blade of 35%, and the time from ejection to stop forging is 10s to ensure the stop forging temperature.

[0029] 12. Edge cutting: remove the burrs by machining to ensure that the residual burrs are 2.5-2.6mm on each side of the blade and 1.0-1.2mm on the remaining sides.

[0030] 13. Heat treatment: perform solid solution + first aging + second aging heat treatment on the forged piece, use oil cooling for solid solution, dry or bake after oil removal, use air cooling for aging, and the hardness of the forged piece after heat treatment is HB=293-331.

[0031] 14. Sand blasting: manually sand blast the edge-cutting forged piece to remove the surface oxide scale.

[0032] 15. Final Inspection: The dimensions of the forged blade conform to the requirements of the blank drawing; the surface quality meets the requirements of complete blade shape, with no cracks, folds, or indentations on the surface; the cross-sectional light transmittance is 0.5-1.0mm; the residual burrs on each side of the blade are 2.0-2.6mm, and the rest are 0.9-1.2mm; the parting surface misalignment is 0.6-1.2mm; the distance from the blade centerline to the horizontal reference plane is 90mm, and the distance to the side reference plane is 80mm; the low-magnification structure and streamlines of the forging are normal; the grain size of the forging is grade 8; the room temperature tensile test and high-temperature creep test are both qualified.

[0033] The product provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the invention claims.

Claims

1. A forging method for large gas turbine high-temperature alloy blades, applicable to controlling the forging process of large gas turbine high-temperature alloy blades, the method comprising, S1: Select a high-temperature alloy billet and rough machine the billet according to the blade design requirements to form a bar stock with rounded ends at both ends; S2: The bar stock is heated by upsetting and formed in one step using an upsetting die to form an upsetting billet; S3: According to the design requirements, the lower tenon and blade of the forged billet are machined to the target size by turning and milling, and then coated with glass lubricant and heated. S4: After heating and forging, the billet is clamped in the pre-forging mold with the small end flattened, then rotated 90° and the blade is clamped in the pre-forging mold to form a blank; S5: Remove the oxide scale from the surface of the blank and spray lubricant to ensure that the surface of the blank is smooth; S6: The forging is placed in a high-temperature electric furnace and preheated at 825±10℃ for 70-120 minutes, then held at 1050±10℃ for 26-60 minutes. The pre-forging is then removed from the electric furnace and finally formed in the final forging die cavity. The forging stop temperature is ensured. The time from the pre-forging exits the furnace to the forging stop is ≤15 seconds. If the die forging cannot be completed within 15 seconds, it needs to be reheated in the furnace for 5 minutes before die forging is performed until the blade is formed. S7: The blades undergo deburring, heat treatment, sandblasting, and testing.

2. The forging method according to claim 1, characterized in that, The upsetting heating in S2 includes using a high-temperature electric furnace with a temperature error of ±10℃, preheating at 825±10℃ for 60~120min, then holding at 1050±10℃ for 22~55min, and using an upsetting die to form the material in one go and meet the dimensional requirements. The time from exiting the furnace to stopping the forging is ≤30s.

3. The forging method according to claim 2, characterized in that, The spraying of glass lubricant and heating in S3 include, After machining, the top forging is cleaned and placed in an oven. It is heated to 80-150℃ and held for a preset time according to the heating requirements in the glass lubricant coating process. Then, high-temperature alloy lubricant: GDS-17 is sprayed on and allowed to dry naturally for ≥3 hours. After spraying, the forged parts are placed in a high-temperature electric furnace and preheated at 825±10℃ for 50 to 120 minutes, and then held at 1050±10℃ for 22 to 55 minutes.

4. The forging method according to claim 3, characterized in that, S4 includes, The time from when the blank comes out of the furnace to when the forging stops is ≤15s.

5. The forging method according to claim 4, characterized in that, S5 includes, Manually sandblast the blank to remove the surface oxide scale; After cleaning the sandblasted blank, place it in an oven and heat it to 80-150℃ according to the heating requirements in the glass lubricant coating process. After holding it at that temperature for a period of time, spray high-temperature alloy lubricant: GDS-17. After spraying, allow it to dry naturally for ≥3 hours to ensure the surface of the forging is smooth and reduce friction.

6. The forging method according to claim 5, characterized in that, S7 includes, Remove the rough edges of the leaves by trimming, with each side of the leaf blade ≤3mm and the rest ≤1.2mm. The blades undergo solution heat treatment. Solution treatment is performed by oil cooling, and after oil cooling, the oil is removed by air drying or baking. The hardness HB is guaranteed to be 277-352 after heat treatment. The blades are manually blown to remove the surface oxide scale.

7. The forging method according to claim 6, characterized in that, The detection in S7 includes, The light transmittance of the blade cross section is ≤1.5mm, the residual burrs on each side of the blade are ≤3.0mm, and the rest are ≤1.2mm, and the parting surface misalignment is ≤1.5mm; The distance from the blade centerline to the horizontal reference plane is 90mm, and the distance to the side reference plane is 80mm; the low-magnification microstructure and streamlines of the forging are normal; the grain size of the forging is greater than grade 5; both room temperature tensile and high temperature creep tests are qualified.

Images