Forming method of IN617 alloy cylindrical forge piece

Abstract

The invention provides a forming method of an IN617 alloy cylindrical forge piece, and relates to the technical field of forging, according to the method, after an IN617 nickel base alloy cast ingot is subjected to homogenization heat treatment, one-heating-number free forging upsetting, one-heating-number drawing-out, closed upsetting, punching, saddle chambering and core rod drawing-out are conducted, and the IN617 alloy cylindrical forge piece is obtained; by strictly controlling technological parameters in the forge piece forming process, the material utilization rate and the production efficiency can be improved, meanwhile, cracking of the end face of the barrel of the IN617 alloy barrel-shaped forge piece is reduced, and the grain size of the forge piece is further refined.

Description

Technical Field

[0001] The present invention relates to the field of forging technology, and more specifically, to a forming method for an IN617 alloy cylindrical forging. Background Art

[0002] IN617 is a solution-strengthened nickel-based superalloy, with main strengthening elements such as chromium, molybdenum, and cobalt, and has excellent high-temperature strength, oxidation resistance, and corrosion resistance. IN617 alloy can be applied in multiple fields such as thermal power, nuclear power, aviation industry, and petrochemical industry. Due to the large deformation resistance of IN617 nickel-based alloy, narrow forging temperature range, and difficulty in recrystallization, and for the IN617 alloy cylindrical forging, due to its large surface area, rapid temperature drop after being taken out of the furnace, easy cracking of the cylinder end face, and often mixed grains in the structure after forging, the forging of IN617 alloy cylindrical forgings is difficult and the technology is not yet mature. Summary of the Invention

[0003] The problem solved by the present invention is: how to reduce the risk of cracking of the cylinder end face of the IN617 alloy cylindrical forging and further refine the grain size of the forging while improving material utilization rate and production efficiency.

[0004] To solve the above problems, the present invention provides a forming method for an IN617 alloy cylindrical forging, including:

[0005] Step S1: After homogenizing heat treatment of an IN617 nickel-based alloy ingot, heat it to the initial forging temperature, and perform one-pass free forging upsetting and one-pass drawing to obtain a first intermediate blank;

[0006] Step S2: Heat the first intermediate blank to the upsetting temperature and perform closed-die upsetting to obtain a second intermediate blank;

[0007] Step S3: Heat the second intermediate blank to the punching temperature and perform punching to obtain a third intermediate blank; wherein, the inner diameter of the third intermediate blank is d, the diameter of the second intermediate blank is D, and the ratio of d to D is 1 / 4 to 1 / 2;

[0008] Step S4: Heat the third intermediate blank to the expanding temperature and perform mandrel expanding to obtain a fourth intermediate blank; wherein, the expanding temperature is 1140°C to 1180°C, and during the mandrel expanding process, the expanding deformation amount per pass is not higher than 60%;

[0009] Step S5: Heat the fourth intermediate blank to the flattening temperature and perform flattening of the end face to obtain a fifth intermediate blank;

[0010] Step S6: Heat the fifth intermediate blank to the first drawing temperature and perform at least one-pass mandrel drawing to obtain a sixth intermediate blank. Wherein, the first drawing temperature is 1100°C to 1140°C, and during the at least one-pass mandrel drawing process, the mandrel drawing deformation amount for each pass is 30% to 50%.

[0011] Step S7: Heat the sixth intermediate blank to the second drawing temperature and perform the last-pass mandrel drawing and annealing treatment to obtain an IN617 alloy cylindrical forging. Wherein, the second drawing temperature is 1060°C to 1100°C, and the mandrel drawing deformation amount for the last pass is 20% to 40%.

[0012] Optionally, in step S1, the temperature of the homogenization heat treatment is 1180°C to 1220°C, and the time is 48h to 96h.

[0013] Optionally, in step S1, the starting forging temperature is 1140°C to 1200°C.

[0014] Optionally, in step S1, the deformation amounts of the one-pass open-die forging upsetting and the one-pass drawing are both 40% to 60%.

[0015] Optionally, in step S2, the upsetting temperature is 1160°C to 1200°C.

[0016] Optionally, in step S2, the height of the second intermediate blank is H, and the ratio of H to D is 1 / 4 to 2 / 3.

[0017] Optionally, in step S3, the punching temperature is 1160°C to 1200°C.

[0018] Optionally, in step S5, the flattening temperature is 1140°C to 1180°C.

[0019] Optionally, in step S5, the deformation amount of the flattened end face is not higher than 6%.

[0020] Optionally, in step S7, the temperature of the annealing treatment is 800°C to 900°C, and the time is 4h to 8h.

[0021] Compared with the related technologies, after homogenizing heat treatment of an IN617 nickel-based alloy ingot, the present invention first performs upsetting of the ingot by one-pass free forging and drawing out by one-pass to obtain a first intermediate blank; then, the first intermediate blank is upset by using a closed-die upsetting method to obtain a second intermediate blank. Since the pressure required for closed-die upsetting is relatively large and the blank is in a triaxial compressive stress state during the upsetting process, the risk of cracking is small; subsequently, the second intermediate blank is heated to the punching temperature and then punched. During this process, by controlling the ratio of the inner diameter d of the third intermediate blank to the diameter D of the second intermediate blank to be 1 / 4 to 1 / 2, not only can the situation of poor flatness of the inner surface of the punching and an increase in the number of passes for subsequent reaming and mandrel drawing be avoided, which is beneficial to improving production efficiency, but also the situation of an increase in the volume of the blank being punched off can be avoided, which is beneficial to improving material utilization rate; then, the third intermediate blank is heated to the reaming temperature for mandrel reaming. During this process, by controlling the reaming temperature to be 1140°C to 1180°C, the need for increasing the number of passes due to too low forging temperature can be avoided, which is beneficial to improving production efficiency, and at the same time, the situation of excessive growth of forged grains due to too high forging temperature can be avoided, which is beneficial to obtaining forgings with smaller grain sizes; at the same time, the reaming deformation amount per pass during the mandrel reaming process is controlled to be not higher than 60%, so as to avoid the situation of end face cracking due to too large deformation amount per pass; in addition, during the process of performing at least one-pass mandrel drawing on the fifth intermediate blank and the last-pass mandrel drawing on the sixth intermediate blank, by forging with step-by-step cooling and ensuring a certain deformation amount, the internal structure of the blank is fully recrystallized and the recrystallized grains do not grow during the heating of the next pass, so as to ensure the overall structural uniformity of the forging, and at the same time, avoid the situation of easy cracking of the blank end face due to too large deformation amount. In addition, by controlling the second drawing temperature to be 1060°C to 1100°C, the forging temperature during this process is below the grain growth inflection temperature, which can avoid the growth of grains. At the same time, the mandrel drawing deformation amount of the last pass is controlled to be 20% to 40%, so that the structure undergoes dynamic recrystallization, thereby avoiding abnormal grain growth. In summary, by using the method of the present invention, while improving material utilization rate and production efficiency, the cracking of the cylinder end face of the IN617 alloy cylindrical forging can be reduced and the grain size of the forging can be further refined. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a process schematic diagram of the forming method of the IN617 alloy cylindrical forging in the embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of mandrel reaming of the third intermediate blank in the embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of mandrel drawing of the fourth intermediate blank in the embodiment of the present invention;

[0025] Figure 4 It is the metallographic structure picture of the IN617 alloy cylindrical forging obtained in Example 1;

[0026] Figure 5 It is the metallographic structure picture of the IN617 alloy cylindrical forging obtained in Example 2;

[0027] Figure 6 It is the end face picture of the IN617 alloy cylindrical forging obtained in Comparative Example 3;

[0028] Figure 7 It is the metallographic structure picture of the IN617 alloy cylindrical forging obtained in Comparative Example 3;

[0029] Figure 8 It is the metallographic structure picture of the IN617 alloy cylindrical forging obtained in Comparative Example 4.

[0030] Explanation of reference numerals:

[0031] 1. Upper anvil; 2. Third intermediate billet; 3. Mandrel bar; 4. Core rod; 5. Fourth intermediate billet. Detailed implementation manners

[0032] To make the above objects, features and advantages of the present invention more obvious and understandable, the following combines the accompanying drawings to make a detailed description of the specific embodiments of the present invention. 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 described herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the present invention in the specification are only for the purpose of describing specific implementation manners and are not intended to limit the present invention.

[0034] As used herein, the term "comprising" and its variations are open-ended, i.e., "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"; the term "optionally" means "optional embodiment". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or primary-secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "a plurality of" means two or more.

[0035] Regarding the problems existing in the above-related technologies, such as Figure 1 As shown, this embodiment provides a forming method for an IN617 alloy cylindrical forging, including:

[0036] Step S1: After homogenizing and heat-treating an IN617 nickel-based alloy ingot, heat it to the initial forging temperature, and perform one-pass free forging upsetting and one-pass drawing to obtain a first intermediate blank.

[0037] Step S2: Heat the first intermediate blank to the upsetting temperature and perform closed-die upsetting to obtain a second intermediate blank.

[0038] Step S3: Heat the second intermediate blank to the punching temperature and perform punching to obtain a third intermediate blank; wherein, the inner diameter of the third intermediate blank is d, the diameter of the second intermediate blank is D, and the ratio of d to D is 1 / 4 to 1 / 2.

[0039] Step S4: Heat the third intermediate blank to the expanding temperature and perform mandrel expanding to obtain a fourth intermediate blank; wherein, the expanding temperature is 1140°C to 1180°C, and during the mandrel expanding process, the expanding deformation amount per pass is not higher than 60%. Figure 2 A schematic diagram for performing mandrel expanding on the third intermediate blank 2, as Figure 2 As shown, use the upper anvil 1 and the mandrel 3 to perform mandrel expanding on the third intermediate blank 2.

[0040] Step S5: Heat the fourth intermediate blank to the flattening temperature and perform end face flattening to obtain a fifth intermediate blank.

[0041] Mandrel drawing out: Step S6: Heat the fifth intermediate blank to the first drawing out temperature, and perform mandrel drawing out for at least one heat to obtain a sixth intermediate blank. Among them, the first drawing out temperature is 1100°C to 1140°C, and during the at least one heat of mandrel drawing out, the deformation amount of mandrel drawing out for each heat is 30% to 50%. Step S7: Heat the sixth intermediate blank to the second drawing out temperature, and perform the last heat of mandrel drawing out and annealing treatment to obtain an IN617 alloy cylindrical forging. Among them, the second drawing out temperature is 1060°C to 1100°C, and the deformation amount of mandrel drawing out for the last heat is 20% to 40%. Figure 3 Schematic diagram for mandrel drawing out of the fourth intermediate blank 5, as Figure 3 shown, use the upper anvil 1 and the mandrel 4 to perform mandrel drawing out on the fourth intermediate blank 5.

[0042] After homogenizing heat treatment of the IN617 nickel-based alloy ingot in the embodiments of the present invention, first, the ingot is upset by one-pass free forging and elongated by one-pass to obtain a first intermediate blank; then the first intermediate blank is upset by a closed-die upsetting method to obtain a second intermediate blank. Since the pressure required for closed-die upsetting is relatively large and the blank is in a triaxial compressive stress state during upsetting, the cracking risk is relatively small; subsequently, the second intermediate blank is heated to the punching temperature and then punched. During this process, by controlling the ratio of the inner diameter d of the third intermediate blank to the diameter D of the second intermediate blank to be 1 / 4 to 1 / 2, it can not only avoid the situation that the flatness of the inner surface of the punched hole becomes poor due to too small a ratio of d to D and increase the number of heating passes for subsequent reaming and mandrel drawing, which is beneficial to improving production efficiency, but also avoid the situation that the volume of the punched blank increases due to too large a ratio of d to D, which is beneficial to improving material utilization rate; then, the third intermediate blank is heated to the reaming temperature and reamed with a mandrel. During this process, by controlling the reaming temperature to be 1140°C to 1180°C, it can avoid increasing the number of heating passes due to too low forging temperature, which is beneficial to improving production efficiency, and at the same time can avoid the excessive growth of forged grains due to too high forging temperature, which is beneficial to obtaining forgings with smaller grain sizes; at the same time, the reaming deformation amount per heating pass during mandrel reaming is controlled to be not higher than 60%, so as to avoid the situation of end face cracking due to too large a deformation amount per heating pass; in addition, during the process of at least one-pass mandrel drawing of the fifth intermediate blank and the last-pass mandrel drawing of the sixth intermediate blank, by gradually reducing the temperature for forging in each heating pass and ensuring a certain deformation amount, the internal structure of the blank is fully recrystallized and it is ensured that the recrystallized grains do not grow during the heating of the next heating pass, so as to ensure the overall structural uniformity of the forging and at the same time avoid the situation that the end face of the blank is prone to cracking due to too large a deformation amount. In addition, by controlling the second drawing temperature to be 1060°C to 1100°C, the forging temperature during this process is below the grain growth inflection temperature, which can avoid the growth of grains, and at the same time control the mandrel drawing deformation amount of the last heating pass to be 20% to 40%, so that the structure undergoes dynamic recrystallization, thereby avoiding abnormal grain growth. In summary, by adopting the method of the embodiments of the present invention, it is possible to improve the material utilization rate and production efficiency while reducing the cracking of the cylinder end face of the IN617 alloy cylindrical forging and further refining the grain size of the forging.

[0043] In some embodiments of the present invention, in the step S1, the temperature of the homogenizing heat treatment is 1180°C to 1220°C, and the time is 48h to 96h.

[0044] In some embodiments of the present invention, in step S1, the initial forging temperature is 1140°C to 1200°C; the deformation amounts of both the first-pass free forging upsetting and the first-pass drawing are 40% to 60%. In this embodiment, the initial forging temperature is set relatively high and the deformation amounts of the first-pass free forging upsetting and the first-pass drawing are set relatively large, so that the blank can be forged through; however, when the deformation amount of the first-pass free forging upsetting exceeds 60%, cracks are likely to appear at the bulging part of the blank, and the blank will become unstable during the subsequent first-pass drawing.

[0045] In some embodiments of the present invention, in step S2, the upsetting temperature is 1160°C to 1200°C; the height of the second intermediate blank is H, and the ratio of H to D is 1 / 4 to 2 / 3. After the first-pass free forging upsetting, the blank is in a bulging shape, and after the closed-die upsetting, the blank is close to a cylinder. After punching, the cross-section of the annular blank is rectangular. Subsequently, when performing mandrel expanding, the deformation amounts at all parts in the axial direction of the blank are the same, which can ensure the uniformity of the axial structure of the final forging. Since the pressure required for closed-die upsetting is relatively large and the blank is in a triaxial compressive stress state, the risk of cracking is small, so the heating temperature can be appropriately increased. If the height-to-diameter ratio (the ratio of H to D) of the second intermediate blank obtained after closed-die upsetting is too large, the blank cannot fit well with the upsetting cylinder and the function of closed-die upsetting cannot be achieved. If the height-to-diameter ratio is too small, it will result in too much pressure required for upsetting and increase the requirement for the equipment tonnage.

[0046] In some embodiments of the present invention, in step S3, the punching temperature is 1160°C to 1200°C. Punching is to punch a hole in the center of a solid blank, and the material undergoes shear deformation. Therefore, in this embodiment, the punching temperature is set relatively high to enable the metal to deform in a temperature range with high plasticity and low strength.

[0047] In some embodiments of the present invention, in step S5, the flattening temperature is 1140°C to 1180°C; the deformation amount of flattening the end face is not higher than 6%. Flattening the end face is to flatten the end faces at both axial ends of the cylindrical fourth intermediate blank. Generally, the deformation amount ≤ 6%, and the purpose is to make the end faces neater.

[0048] In some embodiments of the present invention, in step S7, the temperature of the annealing treatment is 800°C to 900°C, and the time is 4h to 8h. In this embodiment, by controlling the annealing temperature and time, the internal stress of the forging can be better removed.

[0049] The present invention will be further described below in conjunction with specific embodiments. It should be noted that Figure 4 and Figure 5 the scales in both

[0050] Example 1

[0051] A1. After homogenizing and heat-treating the IN617 nickel-based alloy ingot, it is heated to the initial forging temperature, and one-pass free forging upsetting and one-pass drawing are carried out to obtain the first intermediate blank; wherein, the temperature of the homogenizing heat treatment is 1180 °C, the time is 48 h, and the initial forging temperature is 1140 °C; the deformation amounts of the one-pass free forging upsetting and the one-pass drawing are both 40%.

[0052] A2. Heat the first intermediate blank to the upsetting temperature and perform closed-die upsetting to obtain the second intermediate blank; wherein, the upsetting temperature is 1160 °C, and the ratio of the height H to the diameter D of the second intermediate blank is 1 / 4.

[0053] A3. Heat the second intermediate blank to the punching temperature and perform punching to obtain the third intermediate blank; wherein, the punching temperature is 1160 °C, and the inner diameter of the third intermediate blank is d, and the ratio of d to D is 1 / 2.

[0054] A4. Heat the third intermediate blank to the reaming temperature and perform one-pass mandrel reaming to obtain the fourth intermediate blank; wherein, the reaming temperature is 1140 °C, and the deformation amount of the one-pass mandrel reaming is 40%.

[0055] A5. Heat the fourth intermediate blank to the flattening temperature and perform end face flattening to obtain the fifth intermediate blank; wherein, the flattening temperature is 1140 °C, and the deformation amount of the end face flattening is 4%.

[0056] A6. Mandrel drawing:

[0057] A61. Heat the fifth intermediate blank to the first drawing temperature and perform one-pass mandrel drawing to obtain the sixth intermediate blank; wherein, the first drawing temperature is 1100 °C, and during the one-pass mandrel drawing process, the mandrel drawing deformation amount is 30%.

[0058] A62. Heat the sixth intermediate blank to the second drawing temperature and perform the last-pass mandrel drawing and annealing treatment to obtain the IN617 alloy tubular forging; wherein, the second drawing temperature is 1060 °C, the deformation amount of the last-pass mandrel drawing is 20%; the temperature of the annealing treatment is 800 °C, and the time is 4 h.

[0059] For the IN617 alloy tubular forging obtained in Example 1, there are no cracks on both end faces. Observe the metallographic structure of the IN617 alloy tubular forging obtained in Example 1, and the results are shown in Figure 4 , from Figure 4 it can be seen that the metallographic structure of the forging is uniform and fine, and the average grain size reaches grade 7.

[0060] Example 2

[0061] A1. After homogenizing heat treatment of the IN617 nickel-based alloy ingot, it is heated to the initial forging temperature, and one-pass free forging upsetting and one-pass drawing are carried out to obtain the first intermediate blank. Among them, the temperature of the homogenizing heat treatment is 1220 °C, the time is 96 h, and the initial forging temperature is 1200 °C; the deformation amounts of both the one-pass free forging upsetting and the one-pass drawing are 60%.

[0062] A2. The first intermediate blank is heated to the upsetting temperature, and closed die upsetting is carried out to obtain the second intermediate blank. Among them, the upsetting temperature is 1200 °C, and the ratio of the height H to the diameter D of the second intermediate blank is 2 / 3.

[0063] A3. The second intermediate blank is heated to the punching temperature, and punching is carried out to obtain the third intermediate blank. Among them, the punching temperature is 1200 °C, and the inner diameter of the third intermediate blank is d, and the ratio of d to D is 1 / 4.

[0064] A4. The third intermediate blank is heated to the reaming temperature, and one-pass mandrel reaming is carried out to obtain the fourth intermediate blank. Among them, the reaming temperature is 1180 °C, and the deformation amount of the one-pass mandrel reaming is 60%.

[0065] A5. The fourth intermediate blank is heated to the flattening temperature, and the end face is flattened to obtain the fifth intermediate blank. Among them, the flattening temperature is 1180 °C, and the deformation amount of flattening the end face is 6%.

[0066] A6. Mandrel drawing:

[0067] A61. The fifth intermediate blank is heated to the first drawing temperature, and two-pass mandrel drawing is carried out to obtain the sixth intermediate blank. Among them, the first drawing temperature is 1140 °C, and during the two-pass mandrel drawing process, the deformation amount of each pass of mandrel drawing is 50%.

[0068] A62. The sixth intermediate blank is heated to the second drawing temperature, and the last pass of mandrel drawing and annealing treatment are carried out to obtain the IN617 alloy tubular forging. Among them, the second drawing temperature is 1100 °C, the deformation amount of the last pass of mandrel drawing is 40%; the temperature of the annealing treatment is 900 °C, and the time is 8 h.

[0069] For the IN617 alloy tubular forging obtained in Example 2, there are no cracks on both end faces. The metallographic structure of the IN617 alloy tubular forging obtained in Example 2 is observed, and the results are shown in Figure 5 , from Figure 5 it can be seen that the metallographic structure of the forging is uniform and fine, and the average grain size reaches grade 6.

[0070] Comparative Example 1

[0071] The difference from Example 1 is that in step A2: the first intermediate blank is heated to the upsetting temperature and upset freely. During free upsetting, since the blank is in a drum shape and the deformation amount is large, cracking occurs at the maximum bulge of the drum shape. After defect cleaning treatment, it is reheated in the furnace to the upsetting temperature again, taken out of the furnace for sizing, and the second intermediate blank is obtained; wherein, the upsetting temperature is 1160°C, and the ratio of the height H to the diameter D of the second intermediate blank is 1 / 4.

[0072] Compared with Example 1, in step A2 of Comparative Example 1, the closed-die upsetting method is not adopted but free upsetting is used. Since a specific height-to-diameter ratio is required, the deformation amount is large. The deformation amount at the maximum bulge of the free upsetting drum exceeds the deformation limit of the material, resulting in cracking. Therefore, a defect cleaning step is added. To achieve the purpose that the cross-section of the blank is close to a rectangle after closed-die upsetting, in Comparative Example 1, sizing is carried out in an additional heating cycle after defect cleaning. It can be seen that compared with Example 1, Comparative Example 1 reduces the material utilization rate and the total production cost increases by about 8%.

[0073] Comparative Example 2

[0074] The difference from Example 1 is that

[0075] In step A3: the second intermediate blank is heated to the punching temperature and punched to obtain the third intermediate blank; wherein, the punching temperature is 1160°C, the inner diameter of the third intermediate blank is d, and the ratio of d to D is 1 / 5.

[0076] A4. The third intermediate blank is heated to the reaming temperature, and the first-pass mandrel reaming is carried out. It is reheated in the furnace to the reaming temperature, and the second-pass mandrel reaming is carried out to obtain the fourth intermediate blank; wherein, the reaming temperature is 1140°C, the deformation amount of the first-pass mandrel reaming is 40%, and the deformation amount of the second-pass mandrel reaming is 40%.

[0077] Compared with Example 1, in Comparative Example 2, the punching diameter is smaller. When the deformation amount of the first-pass mandrel reaming reaches 40% which is the same as that in Example 1, the inner hole diameter of the blank is still small at this time and does not reach the final reaming size requirement. However, the blank temperature is too low to meet the requirement of continuous deformation at this time, so it is reheated in the furnace to 1140°C again and the second-pass mandrel reaming is carried out, increasing the cost of one reaming process and reducing the production efficiency. In addition, the smaller punching diameter makes the height-width ratio of the deformed cross-section during reaming larger, and instability is likely to occur.

[0078] Comparative Example 3

[0079] The difference from Example 2 is that

[0080] Step A4 is: heating the third intermediate blank to the reaming temperature and performing one-pass mandrel reaming to obtain a fourth intermediate blank; wherein, the reaming temperature is 1200°C, and the deformation amount of the one-pass mandrel reaming is 70%.

[0081] Step A6 is: mandrel drawing:

[0082] A61. Heating the fifth intermediate blank to the first drawing temperature and performing two-pass mandrel drawing to obtain a sixth intermediate blank; wherein, the first drawing temperature is 1140°C, and during the two-pass mandrel drawing, the deformation amount of each pass of mandrel drawing is 50%. Through experiments, it is found that cracks appear on the end face during the second-pass mandrel drawing, and defect cleaning treatment is performed.

[0083] A62. Heating the sixth intermediate blank to the second drawing temperature and performing the last-pass mandrel drawing and annealing treatment to obtain an IN617 alloy cylindrical forging; wherein, the second drawing temperature is 1100°C, the deformation amount of the last-pass mandrel drawing is 40%; the annealing temperature is 900°C, and the time is 8 h; through experiments, it is found that cracks appear on the end face again during the last-pass mandrel drawing, and defect cleaning treatment is performed again.

[0084] Compared with Example 2, in Comparative Example 3, both the reaming temperature and the reaming deformation amount are increased, resulting in overheating of the material before mandrel drawing, leading to widening of the grain boundaries. Moreover, the drawing deformation amount is also relatively large, resulting in cracking of the end face twice during mandrel drawing. Therefore, defect cleaning treatment is carried out, but cracks can still be observed on the final IN617 alloy cylindrical forging. Samples are taken from the cylindrical forging for end face and metallographic structure analysis, and the results are shown in Figure 6 and Figure 7 as shown. It can be seen from Figure 6 that the cracks appearing in the forging are hot cracks. It can be seen from Figure 7 that there are mixed grains in the metallographic structure of the forging, and the grain size is relatively large.

[0085] Comparative Example 4

[0086] The difference from Example 2 is that

[0087] Step A6 is: mandrel drawing:

[0088] A61. Heating the fifth intermediate blank to the first drawing temperature and performing two-pass mandrel drawing to obtain a sixth intermediate blank; wherein, the first drawing temperature is 1080°C, and during the two-pass mandrel drawing, the deformation amount of each pass of mandrel drawing is 20%.

[0089] A62. Heat the sixth intermediate blank to the second drawing temperature, perform the last-pass mandrel drawing and annealing treatment to obtain an IN617 alloy cylindrical forging; wherein, the second drawing temperature is 1040 °C, the deformation amount of the last-pass mandrel drawing is 10%; the temperature of the annealing treatment is 900 °C, and the time is 8 h.

[0090] Different from Example 2, in Comparative Example 4, the heating temperature of the mandrel drawing is lower and the deformation amount is smaller. Due to the lower heating temperature, the temperature drop of the cylindrical blank is larger during the furnace discharging, transfer and drawing processes. There are folding injuries on both end faces of the forged IN617 alloy cylindrical forging, resulting in a relatively tight machining allowance in the subsequent process. Take samples from the end face of the forging for metallographic analysis, as Figure 8 shown, it can be seen that there are obvious mixed grains in the forging structure and the grain size is relatively large.

[0091] Although the present invention is disclosed as above, the protection scope of the present invention 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 these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A forming method for an IN617 alloy cylindrical forging, characterized in that Including: Step S1: After homogenizing and heat-treating an IN617 nickel-based alloy ingot, heat it to the initial forging temperature, perform one-pass free forging upsetting and one-pass drawing to obtain a first intermediate blank. Step S2: Heat the first intermediate blank to the upsetting temperature and perform closed-die upsetting to obtain a second intermediate blank. Step S3: Heat the second intermediate blank to the punching temperature and perform punching to obtain a third intermediate blank. Wherein, the inner diameter of the third intermediate blank is d, the diameter of the second intermediate blank is D, and the ratio of d to D is 1 / 4 to 1 / 2. Step S4: Heat the third intermediate blank to the expanding temperature and perform mandrel expanding to obtain a fourth intermediate blank. Wherein, the expanding temperature is 1140°C to 1180°C, and during the mandrel expanding process, the expanding deformation per pass is not higher than 60%. Step S5: Heat the fourth intermediate blank to the flattening temperature and perform end-face flattening to obtain a fifth intermediate blank. Step S6: Heat the fifth intermediate blank to the first drawing temperature and perform at least one-pass mandrel drawing to obtain a sixth intermediate blank. Wherein, the first drawing temperature is 1100°C to 1140°C, and during the at least one-pass mandrel drawing process, the mandrel drawing deformation per pass is 30% to 50%. Step S7: Heat the sixth intermediate blank to the second drawing temperature and perform the last-pass mandrel drawing and annealing treatment to obtain an IN617 alloy cylindrical forging. Wherein, the second drawing temperature is 1060°C to 1100°C, and the mandrel drawing deformation of the last pass is 20% to 40%.

2. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that, In step S1, the temperature of the homogenizing heat treatment is 1180°C to 1220°C, and the time is 48h to 96h.

3. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that, In step S1, the initial forging temperature is 1140°C to 1200°C.

4. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that, In step S1, the deformation amounts of the one-pass free forging upsetting and the one-pass drawing are both 40% to 60%.

5. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that, In step S2, the upsetting temperature is 1160°C to 1200°C.

6. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that, In step S2, the height of the second intermediate blank is H, and the ratio of H to D is 1 / 4 to 2 / 3.

7. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that, In step S3, the punching temperature is 1160°C to 1200°C.

8. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that, In step S5, the flattening temperature is 1140°C to 1180°C.

9. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that, In step S5, the deformation amount of the end-face flattening is not higher than 6%.

10. The forming method of the IN617 alloy cylindrical forging according to claim 1, characterized in that In step S7, the temperature of the annealing treatment is 800°C to 900°C, and the time is 4h to 8h.

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