Post-forging heat treatment method for runner bucket forging, and auxiliary tool

Abstract

Provided are a post-forging heat treatment method for a runner bucket forging, and an auxiliary tool, relating to the technical field of heat treatment of steel. When performing normalizing heat treatment on a runner bucket forging intermediate sample (1) formed by forging, and when performing a related process step in which an austenite structure is transformed into a martensite structure, the runner bucket forging intermediate sample (1) is mounted in the provided auxiliary tool, such that bottoms of two runner bucket side walls (12) of the sample are secured in corresponding retaining notches (52), and inner walls on left and right sides of an upper ring (2) are in flush contact with the runner bucket side walls (12). The auxiliary tool plays a role in inhibiting sample expansion in the process steps, thereby inhibiting outward expansion and sagging of the runner bucket side walls (12) of the runner bucket forging intermediate sample (1). During a post-forging heat treatment process, the present method inhibits outward expansion and sagging of runner bucket side walls (12) of runner bucket forging intermediate samples (1) formed by forging, and ensures that runner bucket forgings exhibit a relatively fine grain size.

Description

A method for post-forging heat treatment of water bucket forgings and auxiliary tools Technical Field

[0001] This invention relates to the field of heat treatment technology for steel, and more specifically, to a method and auxiliary tool for post-forging heat treatment of water tank forgings. Background Technology

[0002] In impulse turbine units, the runner typically consists of a hub and buckets. The hub is the central part connecting the runner to the axle, and multiple buckets are mounted on the outer circumference of the hub to receive the impact force of the water flow, converting the kinetic energy of the water flow into mechanical energy to drive the hub to rotate. As the capacity of the units continues to increase, the requirements for the strength and toughness of the runner become increasingly stringent. The runner is usually welded from hub forgings and bucket forgings.

[0003] Previously, smaller water bucket forgings could be forged together with turbine forgings into a disc shape, heat-treated, and then machined into water buckets. However, for larger water bucket forgings, such as those used in turbine forgings for 500MW to 700MW systems, the tonnage and material strength of the forgings prevented their production from being done by forging them together with the turbine and then machining them into water buckets. Instead, the water buckets had to be forged separately or cast. However, cast water buckets have poor material density and are insufficient to withstand the immense erosion in harsh environments. Forging water buckets overcomes these drawbacks. To achieve near-net-shape forging of the water bucket forging, the intermediate sample of the forged water bucket is basically consistent with the structure and dimensions of the forged water bucket. Specifically, as shown in Figures 1 to 3, the intermediate sample of the water bucket forging has a symmetrical structure, including a ridge 11 that protrudes upward in the middle and bucket sidewalls 12 symmetrically located on the left and right sides of the ridge 11. The lower side of the ridge 11 has a groove 13 corresponding to the ridge 11. The intermediate sample of the water bucket forging 1 also has a front notch 14 and a rear notch 15 at its front and rear ends, respectively, which separate the two bucket sidewalls 12 and make the front end of the bucket sidewalls 12 form a pointed tip. In order to improve the water flow effect of the water bucket forging, each bucket sidewall 12 has a certain longitudinal curvature. The intermediate sample of the forged water bucket forging 1 needs to undergo post-forging heat treatment. During the post-forging heat treatment, the bucket sidewalls 12 of the intermediate sample of the water bucket forging 1 will undergo severe outward expansion and sagging, resulting in large deformation of the water bucket forging after heat treatment, making it difficult to achieve near-net-shape forging of the water bucket forging. In addition, the water bucket forging is made of 04Cr13Ni5Mo steel, and during the production process, it is also necessary to ensure that the water bucket forging has a fine grain size. Summary of the Invention

[0004] The problem solved by this invention is at least one of the following: how to suppress the outward expansion and sagging of the bucket sidewall of the intermediate sample of the forged bucket during the post-forging heat treatment process; and how to ensure that the bucket forging made of 04Cr13Ni5Mo steel has a finer grain size.

[0005] To address the aforementioned problems, this invention provides an auxiliary tool for suppressing deformation of intermediate samples of forged water buckets during post-forging heat treatment. The intermediate sample includes a ridge protruding upwards from the center laterally and bucket sidewalls symmetrically arranged on the left and right sides of the ridge. The lower side of the ridge is recessed upwards to form a groove corresponding to the ridge. A rearwardly concave front notch is formed at the center of the front end of the intermediate sample, and a forwardly concave rear notch is formed at the center of the rear end of the intermediate sample.

[0006] The auxiliary device includes an upper ring, a lower ring, intermediate support columns, and two support frames. The upper ring and the lower ring are arranged vertically opposite each other. The lower end face of the upper ring and the upper end face of the lower ring are connected by multiple intermediate support columns to form a cylindrical support structure. The two support frames are arranged symmetrically inside the cylindrical support structure. Each support frame includes a vertical panel. The upper middle area of ​​the vertical panel forms a downwardly recessed binding notch, which is used to hold the bottom of the bucket sidewall in place. The inner wall shape on the left and right sides of the upper ring matches the longitudinal curvature of the bucket sidewall.

[0007] Compared with the prior art, when normalizing the intermediate sample of the forged water bucket, during the process steps involving the transformation of austenite to martensite, the intermediate sample of the water bucket forging is installed in the auxiliary tool provided by this invention, so that the bottom of the two bucket side walls of the sample is locked at the corresponding binding notch, and the inner walls of the left and right sides of the upper ring are in contact with the bucket side walls. The auxiliary tool can suppress the expansion of the sample in the above process steps, thereby suppressing the outward expansion and sagging of the bucket side walls of the intermediate sample of the water bucket forging.

[0008] Optionally, the support frame is fixed to the inner wall of the lower ring.

[0009] Optionally, the plurality of intermediate support columns are evenly distributed along the circumference of the cylindrical support structure.

[0010] The present invention also provides a post-forging heat treatment method for water bucket forgings, based on the auxiliary tool described above, comprising:

[0011] Step S1, Normalizing treatment: The intermediate sample of the forged water bucket is installed in the auxiliary fixture and held at 500°C to 540°C for 4 to 6 hours. It is then cooled to 100°C to 160°C at a preset cooling rate and held for 4 to 6 hours. The sample is then heated to 500°C to 550°C at a first preset heating rate. The sample is then removed from the auxiliary fixture and heated to 960°C to 1020°C at a second preset heating rate. The sample is held for 8 to 12 hours. The sample is then installed in the auxiliary fixture and air-cooled to 100°C to 160°C.

[0012] Step S2: After removing the sample obtained after normalizing from the fixture, perform tempering treatment.

[0013] Compared with the prior art, in this invention, the intermediate sample of the forged water bucket is installed in the auxiliary fixture. Then, the intermediate sample is held at 500°C to 540°C for 4 to 6 hours to ensure uniform temperature inside and outside the sample, thereby reducing sample deformation caused by thermal stress. Then, the sample is cooled to 100°C to 160°C and held for 4 to 6 hours. During this process, the austenitic structure transforms into martensite. Since the sample is installed in the auxiliary fixture at this time, the fixture can suppress sample expansion, thereby suppressing the expansion of the water bucket forging. The intermediate sample exhibits outward expansion and sagging of the bucket sidewalls. Subsequently, the sample is heated to 960°C to 1020°C and held at this temperature for a short period (8 to 12 hours) to avoid grain coarsening that can occur with prolonged holding at high temperatures. The sample is then air-cooled to 100°C to 160°C. During this cooling process, austenite transforms into martensite. Since the sample is mounted in a fixture, the fixture helps to suppress sample expansion. In summary, the method of this invention, during post-forging heat treatment, can suppress the outward expansion and sagging of the bucket sidewalls in the intermediate sample of the forged bucket and ensure that the bucket forging has a finer grain size.

[0014] Optionally, in step S1, the preset cooling rate is below 10℃ / h.

[0015] Optionally, in step S1, the first preset heating rate is 30℃ / h to 40℃ / h.

[0016] Optionally, in step S1, the second preset heating rate is 50℃ / h to 80℃ / h.

[0017] Optionally, in step S2, after removing the sample obtained after normalizing treatment from the auxiliary fixture, the tempering treatment includes: after removing the sample obtained after normalizing treatment from the auxiliary fixture, holding it at 100°C to 160°C for 4 to 6 hours, raising the temperature to 560°C to 610°C at a third preset heating rate, holding it at 10 to 15 hours, furnace cooling to 190°C to 200°C, and then removing it from the furnace for cooling.

[0018] Optionally, in step S2, the third preset heating rate is 30℃ / h to 40℃ / h.

[0019] Optionally, the intermediate sample of the water bucket forging is made of 04Cr13Ni5Mo steel. Attached Figure Description

[0020] Figure 1 is a three-dimensional structural schematic diagram of the intermediate sample of the water bucket forging in an embodiment of the present invention;

[0021] Figure 2 is a front view of the intermediate sample of the water bucket forging in an embodiment of the present invention;

[0022] Figure 3 is a top view of the intermediate sample of the water bucket forging in an embodiment of the present invention;

[0023] Figure 4 is a schematic diagram of the assistive device in an embodiment of the present invention;

[0024] Figure 5 is a schematic diagram of the structure when the intermediate sample of the water bucket forging is installed in the auxiliary fixture in an embodiment of the present invention;

[0025] Figure 6 is a front view of the intermediate sample of the water bucket forging installed in the auxiliary fixture in an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached drawings: 1. Intermediate sample of water bucket forging; 11. Ridge; 12. Bucket side wall; 13. Groove; 14. Front notch; 15. Rear notch; 2. Upper ring; 3. Lower ring; 4. Intermediate support column; 5. Support frame; 51. Vertical panel; 52. Binding notch; 53. Bottom column. Detailed Implementation

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0028] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0029] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the description below. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0030] It should be noted that in the attached diagram, the X-axis represents the vertical direction, that is, the front-to-back direction, and the positive direction of the X-axis represents the front, and the negative direction of the X-axis represents the back; the Y-axis represents the horizontal direction, that is, the left-to-right direction, and the positive direction of the Y-axis represents the right, and the negative direction of the Y-axis represents the left; the Z-axis represents the vertical direction, that is, the up-down direction, and the positive direction of the Z-axis represents the up, and the negative direction of the Z-axis represents the down.

[0031] The material of the water bucket forging is 04Cr13Ni5Mo steel. The intermediate sample of the forged water bucket needs to undergo post-forging heat treatment. The post-forging heat treatment process generally includes normalizing and tempering. During the normalizing process, the austenite structure in the sample will transform into martensite. The transformation of austenite into martensite will cause the sample to undergo a large volume expansion, resulting in severe outward expansion and sagging of the bucket sidewall of the intermediate sample of the water bucket forging. This will cause the water bucket forging to undergo large deformation after heat treatment, making it difficult to achieve near-net-shape forging of the water bucket forging.

[0032] To address the problems existing in the aforementioned related technologies, this embodiment provides an auxiliary tool for suppressing the deformation of the intermediate sample 1 of the forged water bucket during the post-forging heat treatment process. As shown in Figures 1 to 3, the intermediate sample 1 of the water bucket forging includes a ridge 11 that protrudes upward from the middle of the transverse direction and bucket sidewalls 12 symmetrically arranged on the left and right sides of the ridge 11. The lower side of the ridge 11 is recessed upward to form a groove 13 corresponding to the ridge 11. A front notch 14 that is recessed inward is formed at the middle of the front end of the intermediate sample 1 of the water bucket forging, and a rear notch 15 that is recessed inward is formed at the middle of the rear end of the intermediate sample 1 of the water bucket forging.

[0033] As shown in Figure 4, the auxiliary device includes an upper ring 2, a lower ring 3, a middle support column 4, and two support frames 5. The upper ring 2 and the lower ring 3 are arranged opposite each other vertically. The lower end face of the upper ring 2 and the upper end face of the lower ring 3 are connected by multiple middle support columns 4 to form a cylindrical support structure. The two support frames 5 are arranged symmetrically inside the cylindrical support structure. Each support frame 5 includes a vertical panel 51. The upper middle area of ​​the vertical panel 51 forms a downwardly recessed binding notch 52, which is used to hold the bottom of the bucket side wall 12. The inner wall shape on the left and right sides of the upper ring 2 matches the longitudinal curvature of the bucket side wall 12.

[0034] In use, when normalizing the intermediate sample 1 of the forged water bucket, during the relevant process steps involving the transformation of austenite to martensite, as shown in Figures 5 and 6, the intermediate sample 1 of the water bucket forging is installed in the auxiliary tool provided in the embodiment of the present invention, so that the bottom of the two bucket side walls 12 of the sample is stuck at the corresponding binding notch 52, and the inner walls on the left and right sides of the upper ring 2 are in contact with the bucket side walls 12. The auxiliary tool can suppress the expansion of the sample in the above process steps, thereby suppressing the outward expansion and sagging of the bucket side walls 12 of the intermediate sample 1 of the water bucket forging.

[0035] In some embodiments of the present invention, as shown in FIG4, the support frame 5 is fixed to the inner wall of the lower ring 3. Specifically, the support frame 5 includes a bottom column 53 and a vertical panel 51. The two ends of the bottom column 53 in the length direction are respectively connected to the inner wall of the lower ring 3, and the vertical panel 51 is fixed to the upper end surface of the bottom column 53.

[0036] In some embodiments of the present invention, as shown in FIG4, a plurality of intermediate support columns 4 are evenly distributed along the circumference of the cylindrical support structure. Specifically, six intermediate support columns 4 are evenly distributed along the circumference of the cylindrical support structure.

[0037] This invention also provides a post-forging heat treatment method for water tank forgings, based on the auxiliary tool described above, including:

[0038] Step S1, Normalizing treatment: As shown in Figures 5 and 6, the intermediate sample of the forged water bucket is installed in the auxiliary fixture and held at 500°C to 540°C for 4 to 6 hours. Then, it is cooled to 100°C to 160°C at a preset cooling rate and held for 4 to 6 hours. The sample is then heated to 500°C to 550°C at a first preset heating rate. The sample is then removed from the auxiliary fixture and heated to 960°C to 1020°C at a second preset heating rate. The sample is held for 8 to 12 hours. The sample is then installed in the auxiliary fixture and air-cooled to 100°C to 160°C.

[0039] Step S2: After removing the sample obtained after normalizing from the fixture, perform tempering treatment.

[0040] In this embodiment of the invention, as shown in Figures 5 and 6, the intermediate sample of the forged water bucket is installed in the auxiliary fixture. Then, the intermediate sample is held at 500°C to 540°C for 4 to 6 hours to ensure uniform temperature throughout the sample, thereby reducing deformation caused by thermal stress. The sample is then cooled to 100°C to 160°C and held for 4 to 6 hours. During this process, austenite transforms into martensite. Since the sample is installed in the auxiliary fixture, the fixture helps to suppress sample expansion, thus inhibiting water bucket deformation. The sidewalls of the intermediate forging sample expand and sag. Subsequently, the sample is heated to 960°C to 1020°C and held at this temperature for a short period (8 to 12 hours) to avoid grain coarsening caused by prolonged holding at high temperatures. The sample is then air-cooled to 100°C to 160°C. During this cooling process, austenite transforms into martensite. Since the sample is mounted in a fixture, the fixture helps to suppress sample expansion. In summary, the method described in this invention can suppress the expansion and sag of the sidewalls of the intermediate forging sample during post-forging heat treatment, ensuring a finer grain size in the forging.

[0041] In some embodiments of the present invention, in step S1, the preset cooling rate is below 10°C / h. In this embodiment, because the cooling rate is slow, the austenitic structure in both the internal and external regions of the sample can transform into martensite simultaneously, thereby reducing structural stress and further reducing sample deformation.

[0042] In some embodiments of the present invention, in step S1, the first preset heating rate is 30℃ / h to 40℃ / h. In this embodiment, because the heating rate is relatively slow (30℃ / h to 40℃ / h), the martensite recovers slowly, which can effectively reduce the thermal stress and structural stress of the sample, and further reduce the deformation of the sample.

[0043] In some embodiments of the present invention, in step S1, the second preset heating rate is 50°C / h to 80°C / h. In this embodiment, because the heating rate is relatively fast (50°C / h to 80°C / h), it can effectively increase the material nucleation driving force, promote grain nucleation, and thus effectively refine the grains.

[0044] In some embodiments of the present invention, step S2, after removing the sample obtained after normalizing treatment from the auxiliary fixture, includes: after removing the sample obtained after normalizing treatment from the auxiliary fixture, holding it at 100°C to 160°C for 4 to 6 hours, raising the temperature to 560°C to 610°C at a third preset heating rate, holding it at 10 to 15 hours, furnace cooling to 190°C to 200°C, and then removing it from the furnace for cooling.

[0045] In some embodiments of the present invention, in step S2, the third preset heating rate is 30°C / h to 40°C / h.

[0046] In some embodiments of the present invention, the intermediate sample of the water bucket forging is made of 04Cr13Ni5Mo steel, with the following composition: C: 0.01% to 0.04%, Si: 0 to 0.6%, Mn: 0.50% to 1.00%, Cr: 12.0% to 13.5%, Mo: 0.40% to 0.80%, Ni: 4.5% to 6.0%, V: 0 to 0.07%, Cu: 0 to 0.50%, W: 0 to 0.10%, S: 0 to 0.008%, P: 0 to 0.020%, with the balance being Fe and unavoidable impurities; wherein the sum of the mass fractions of V, Cu, and W is 0 to 0.50%.

[0047] The present invention will be further described below with reference to specific embodiments.

[0048] Example 1

[0049] A1. Normalizing Treatment: The intermediate sample of the forged water tank part is installed in the fixture provided in this embodiment of the invention and held at 520°C for 5 hours. It is then cooled to 130°C at a preset cooling rate and held for 5 hours. Next, it is heated to 525°C at a first preset heating rate. The resulting sample is removed from the fixture and then heated to 990°C at a second preset heating rate and held for 10 hours. The resulting sample is then installed in the fixture and air-cooled to 130°C. The preset cooling rate is 5°C / h. The first preset heating rate is 35℃ / h, and the second preset heating rate is 65℃ / h; by weight percentage, the composition of the intermediate sample of the water tank forging includes: C: 0.02%, Si: 0.3%, Mn: 0.70%, Cr: 12.5%, Mo: 0.60%, Ni: 5.0%, V: 0.03%, Cu: 0.20%, W: 0.05%, S: 0.004%, P: 0.010%, with the balance being Fe and unavoidable impurities.

[0050] A2. Tempering treatment: After the sample obtained after normalizing treatment is taken out from the auxiliary tool, it is heated at 130°C for 5 hours, heated to 585°C at a third preset heating rate, held for 13 hours, furnace cooled to 195°C, and then cooled to obtain the final water tank forging sample; wherein, the third preset heating rate is 35°C / h.

[0051] Upon testing, the final bucket forging sample obtained in Example 1 showed no outward expansion or sagging of the bucket sidewall.

[0052] Example 2

[0053] A1. Normalizing Treatment: The intermediate sample of the forged water tank part is installed in the fixture provided in this embodiment of the invention and held at 540°C for 4 hours. It is then cooled to 160°C at a preset cooling rate and held for 4 hours. The temperature is then increased to 550°C at a first preset heating rate. The resulting sample is removed from the fixture and then heated to 1020°C at a second preset heating rate and held for 8 hours. The resulting sample is then installed in the fixture and air-cooled to 130°C. The preset cooling rate is 5°C / h. The first preset heating rate is 40℃ / h, and the second preset heating rate is 80℃ / h; by weight percentage, the composition of the intermediate sample of the water tank forging includes: C: 0.02%, Si: 0.3%, Mn: 0.70%, Cr: 12.5%, Mo: 0.60%, Ni: 5.0%, V: 0.03%, Cu: 0.20%, W: 0.05%, S: 0.004%, P: 0.010%, with the balance being Fe and unavoidable impurities.

[0054] A2. Tempering treatment: After the sample obtained after normalizing treatment is taken out from the auxiliary tool, it is held at 160°C for 4 hours, heated to 610°C at a third preset heating rate, held for 10 hours, furnace cooled to 195°C, and then cooled to obtain the final water tank forging sample; wherein, the third preset heating rate is 40°C / h.

[0055] Upon testing, the final bucket forging sample obtained in Example 2 showed no outward expansion or sagging of the bucket sidewall.

[0056] Example 3

[0057] A1. Normalizing Treatment: The intermediate sample of the forged water tank part is installed in the fixture provided in this embodiment of the invention and held at 500°C for 6 hours. It is then cooled to 100°C at a preset cooling rate and held for 6 hours. The sample is then heated to 500°C at a first preset heating rate. The resulting sample is removed from the fixture and then heated to 960°C at a second preset heating rate and held for 12 hours. The resulting sample is then installed in the fixture and air-cooled to 130°C. The preset cooling rate is 5°C / h. The first preset heating rate is 30℃ / h, and the second preset heating rate is 50℃ / h; by weight percentage, the composition of the intermediate sample of the water tank forging includes: C: 0.02%, Si: 0.3%, Mn: 0.70%, Cr: 12.5%, Mo: 0.60%, Ni: 5.0%, V: 0.03%, Cu: 0.20%, W: 0.05%, S: 0.004%, P: 0.010%, with the balance being Fe and unavoidable impurities.

[0058] A2. Tempering treatment: After the sample obtained after normalizing treatment is taken out from the auxiliary tool, it is heated at 100°C for 6 hours, heated to 560°C at a third preset heating rate, held for 15 hours, furnace cooled to 195°C, and then cooled to obtain the final water tank forging sample; wherein, the third preset heating rate is 30°C / h.

[0059] Upon testing, the final bucket forging sample obtained in Example 3 showed no outward expansion or sagging of the bucket sidewall.

[0060] Comparative example (the auxiliary tools provided in the embodiments of the present invention were not used during the normalizing process).

[0061] The difference from Example 1 is that step A1 is as follows: the intermediate sample of the forged water bucket is held at 540°C for 4 hours, cooled to 160°C at a preset cooling rate, held for 4 hours, heated to 550°C at a first preset heating rate, then heated to 1020°C at a second preset heating rate, held for 8 hours, and then air-cooled to 130°C; wherein, the preset cooling rate is 5°C / h, the first preset heating rate is 40°C / h, and the second preset heating rate is 80°C / h; the composition of the intermediate sample of the water bucket forging, by weight percentage, includes: C: 0.02%, Si: 0.3%, Mn: 0.70%, Cr: 12.5%, Mo: 0.60%, Ni: 5.0%, V: 0.03%, Cu: 0.20%, W: 0.05%, S: 0.004%, P: 0.010%, with the balance being Fe and unavoidable impurities.

[0062] Testing revealed that the final bucket forging sample obtained in the comparative experiment exhibited severe outward expansion and sagging of the bucket sidewall.

[0063] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. An assistive device, comprising: The intermediate sample (1) of the water bucket forging is used to suppress deformation during the post-forging heat treatment process. The intermediate sample (1) of the water bucket forging includes a ridge (11) that protrudes upward in the middle of the transverse direction and bucket sidewalls (12) symmetrically arranged on the left and right sides of the ridge (11). The lower side of the ridge (11) is recessed upward to form a groove (13) corresponding to the ridge (11). The intermediate sample (1) of the water bucket forging has a front notch (14) that is recessed inward in the middle of the front end and a rear notch (15) that is recessed inward in the middle of the rear end. The auxiliary device includes an upper ring (2), a lower ring (3), a middle support column (4), and two support frames (5). The upper ring (2) and the lower ring (3) are arranged opposite each other. The lower end face of the upper ring (2) and the upper end face of the lower ring (3) are connected by multiple middle support columns (4) to form a cylindrical support structure. The two support frames (5) are arranged symmetrically inside the cylindrical support structure. The support frame (5) includes a vertical panel (51). The upper middle area of ​​the vertical panel (51) forms a downwardly recessed binding notch (52). The binding notch (52) is used to hold the bottom of the bucket side wall (12). The inner wall shape on the left and right sides of the upper ring (2) matches the longitudinal curvature of the bucket side wall (12).

2. The assistive device of claim 1, wherein, The support frame (5) is fixed on the inner wall of the lower ring (3).

3. The assistive device of claim 1, wherein, Multiple intermediate support columns (4) are evenly distributed along the circumference of the cylindrical support structure.

4. A method of post-forgmg heat treatment of a water bucket forging, characterized by, Based on the assistive device as described in any one of claims 1 to 3, comprising: Step S1, Normalizing treatment: The intermediate sample of the forged water bucket is installed in the auxiliary fixture and held at 500°C to 540°C for 4 to 6 hours. It is then cooled to 100°C to 160°C at a preset cooling rate and held for 4 to 6 hours. The sample is then heated to 500°C to 550°C at a first preset heating rate. The sample is then removed from the auxiliary fixture and heated to 960°C to 1020°C at a second preset heating rate. The sample is held for 8 to 12 hours. The sample is then installed in the auxiliary fixture and air-cooled to 100°C to 160°C. Step S2: After removing the sample obtained after normalizing from the fixture, perform tempering treatment.

5. The method of post-forgmg heat treatment of a ladle forging according to claim 4, characterized in that, In step S1, the preset cooling rate is below 10℃ / h.

6. The method of post-forgmg heat treatment of a ladle forging according to claim 4, characterized in that, In step S1, the first preset heating rate is 30℃ / h to 40℃ / h.

7. The post-forging heat treatment method for the water bucket forging according to claim 4, characterized in that, In step S1, the second preset heating rate is 50℃ / h to 80℃ / h.

8. The post-forging heat treatment method for the water bucket forging according to claim 4, characterized in that, In step S2, after the sample obtained after normalizing is removed from the auxiliary fixture, tempering is performed, which includes: after removing the sample obtained after normalizing from the auxiliary fixture, holding it at 100°C to 160°C for 4 to 6 hours, raising it to 560°C to 610°C at a third preset heating rate, holding it at 560°C to 610°C for 10 to 15 hours, furnace cooling to 190°C to 200°C, and then removing it from the furnace for cooling.

9. The post-forging heat treatment method for the water bucket forging according to claim 8, characterized in that, In step S2, the third preset heating rate is 30℃ / h to 40℃ / h.

10. The post-forging heat treatment method for the water bucket forging according to claim 4, characterized in that, The intermediate sample of the water bucket forging is made of 04Cr13Ni5Mo steel.

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