Die for nickel-based alloy extrusion bar

Abstract

The utility model provides a nickel-based alloy bar extrusion die, which relates to the technical field of extrusion dies and comprises an extrusion die and an extrusion cylinder. The outlet side of the extrusion cylinder is fixedly connected with the inlet side of the extrusion die, and the diameter of the outlet side of the extrusion die is smaller than that of the inlet side; the inner side surface of the extrusion die comprises a flat die section, a conical die section and a sizing belt which are connected in sequence, and the conical die section is in transition connection with the flat die section and the sizing belt through an inlet rounding and an outlet rounding respectively; an included angle between the conical die section and the axis of the extrusion die outlet is a die angle, and the size of the die angle is 30-50 degrees; the radius of the inlet fillet and the radius of the outlet fillet are 50-100 mm. According to the utility model, the design of a novel die structure is adopted, so that the temperature rise in the bar can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of extrusion dies, and more specifically, to a die for extruding nickel-based alloy bars. Background Art

[0002] Due to the poor thermal conductivity of nickel-based superalloys, when using traditional extrusion dies to extrude large-section nickel-based alloy bars, the extrusion shaft does work on the blank, converting mechanical energy into heat energy, resulting in a significant increase in the temperature at the center of the extruded bar. Moreover, the cooling rate of large-section bars is relatively slow, causing obvious growth of the deformed and refined grains, which affects the uniformity of the overall structure and properties of the bars.

[0003] Nickel-based alloy bars for aerospace applications have high technical requirements for the overall grain size and grain size gradient. Currently, in domestic production of large-sized nickel-based alloy bars, forging and extrusion are generally used. Due to the complex temperature field during the extrusion process of nickel-based alloy bars, the temperature non-uniformity has a great impact on the uniformity of the overall structure of the product, increasing the difficulty of microstructure control in the extrusion production of nickel-based alloys.

[0004] After dissecting the extruded nickel-based alloy bars, it is found that there are obvious differences in the grain size between the edge of the extruded bar and the R / 2 position (R is the radius, and the R / 2 position is the position at a distance of R / 2 from the center) and the center position. The grain sizes at the R / 2 and center positions are larger. With the increase of the extrusion ratio and the cross-section of the bar, this phenomenon becomes more obvious. The grain size gradient between the R / 2 and center positions and the edge of the bar can be greater than 2 grades, which cannot meet the requirements of fine-grained bar materials for aerospace applications.

[0005] The reason is that through finite element simulation, it is found that when using traditional dies for extrusion, the temperature rise inside the bar is significantly higher than that at the edge. The large temperature rise causes obvious growth of the recrystallized small grains after deformation, which is the main reason for the larger grain size at the R / 2 and center positions of the extruded bar compared to the edge grain size. Summary of the Utility Model

[0006] The problem solved by the utility model is how to solve the problem that the temperature rise inside the bar is higher than that at the edge, resulting in a larger grain size at the R / 2 and center of the extruded bar compared to the edge grain size.

[0007] To this end, the present utility model provides a die for nickel-based alloy extrusion bars, including an extrusion die and an extrusion cylinder; the outlet side of the extrusion cylinder is fixedly connected to the inlet side of the extrusion die, and the diameter of the outlet side of the extrusion die is smaller than that of the inlet side; the inner side surface of the extrusion die includes a flat die section, a tapered die section, and a sizing band that are sequentially connected, and the tapered die section is transitionally connected to the flat die section and the sizing band through an inlet fillet and an outlet fillet respectively; the angle between the axis of the tapered die section and the outlet of the extrusion die is the die angle, and the size of the die angle is 30°-50°; the radii of the inlet fillet and the outlet fillet are 50-100 mm.

[0008] Optionally, the size of the die angle is 40°-45°.

[0009] Optionally, the radii of the inlet fillet and the outlet fillet are 80-100 mm.

[0010] Optionally, the length of the sizing band is determined by the following method: when the diameter D2 of the extrusion end ≤ 300 mm, the length of the sizing band is taken as (1 / 8 to 1 / 6)D2; when the diameter D2 of the extrusion end > 300 mm, the length of the sizing band is taken as (1 / 6 to 1 / 5)D2, where D2 is the diameter of the extrusion end of the extrusion die.

[0011] Optionally, the length of the sizing band is determined by the following method: when the extrusion ratio λ ≤ 4, when the die angle is 30-40°, the length of the flat die section is taken as (1 / 18 to 1 / 16)D1, and when the die angle is 40-50°, the length of the flat die section is taken as (1 / 16 to 1 / 14)D1; when the extrusion ratio λ > 4, the length of the flat die section is taken as (1 / 14 to 1 / 12)D1, where D1 is the diameter of the extrusion cylinder.

[0012] Optionally, the length of the flat die section is 35 mm, the length of the sizing band is 45 mm; the size of the die angle is 45°; the radii of the inlet fillet and the outlet fillet are 80 mm.

[0013] Optionally, the length of the flat die section is 60 mm, the length of the sizing band is 60 mm; the size of the die angle is 40°; the radii of the inlet fillet and the outlet fillet are 100 mm.

[0014] Optionally, the flat die section is flush with the outlet surface of the extrusion cylinder, and the sizing band is perpendicular to the outlet surface of the extrusion die.

[0015] Optionally, the diameter of the outlet of the extrusion cylinder is larger than the diameter of the inlet end of the extrusion die.

[0016] Optionally, the outlet side of the extrusion cylinder and the inlet side of the extrusion die are fixedly connected by bolts.

[0017] Compared with the prior art, the beneficial effects of a mold for nickel-based alloy extrusion bars of the present utility model are as follows: By providing a flat die section, good lubrication can be ensured throughout the extrusion process, guaranteeing the surface quality of the bars; compared with traditional extrusion dies, the size of the die angle A is reduced, thereby being able to lower the temperature rise inside the extrusion bars, avoid the growth of recrystallized small grains, and improve the uniformity of the overall grain size of the bars; moreover, the radii of the inlet fillet and the outlet fillet are increased, which can evenly distribute the molten glass lubricant on all the inner surfaces of the mold, thereby reducing the frictional resistance and decreasing the sudden change degree of the strain of the billet before and after the deformation zone, making the strain more uniform. The combined effect of the above two aspects reduces the temperature rise inside the bars. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of a mold for nickel-based alloy extrusion bars of the present utility model;

[0019] Figure 2 It is a grain morphology diagram at the R / 2 position of the tail of the extrusion bar in Embodiment 1 of the present utility model;

[0020] Figure 3 It is a grain morphology diagram at the R / 2 position of the tail of the extrusion bar in Comparative Example 1 of the present utility model;

[0021] Figure 4 It is a longitudinal section temperature field diagram of the extrusion bar in Embodiment 1 of the present utility model;

[0022] Figure 5 It is a longitudinal section temperature field diagram of the extrusion bar in Comparative Example 1 of the present utility model;

[0023] Figure 6 It is a grain morphology diagram of the center of the tail of the extrusion bar in Embodiment 2 of the present utility model;

[0024] Figure 7 It is a grain morphology diagram of the center of the tail of the extrusion bar in Comparative Example 2 of the present utility model;

[0025] Figure 8 It is a longitudinal section temperature field diagram of the extrusion bar in Embodiment 2 of the present utility model;

[0026] Figure 9 It is a longitudinal section temperature field diagram of the extrusion bar in Comparative Example 2 of the present utility model.

[0027] Description of the Reference Numerals:

[0028] 1. Extrusion die; 2. Extrusion cylinder; L1. Flat die section; L2. Sizing band; L3. Taper die section; A. Die angle; R1. Inlet fillet; R2. Outlet fillet. Detailed Embodiments

[0029] To make the above objects, features, and advantages of the present utility model more apparent and understandable, the following provides a detailed description of specific embodiments of the present utility model with reference to the accompanying drawings.

[0030] It should be noted that in the description of the present utility model, the orientation or positional relationships indicated by terms such as "upper", "lower", "left", "right", "top", "bottom", "front", "rear", "inner", and "outer" are based on the orientation or positional relationships shown in the accompanying drawings. This is only for the convenience of describing the present utility model and does not indicate or imply that the device referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present utility model.

[0031] 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, features defined with "first" and "second" may explicitly or implicitly include at least one of such features.

[0032] Moreover, although the present utility model is described with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present utility model. Many modifications can be made to the exemplary embodiments, and other embodiments can be designed as long as they do not deviate from the core concept and scope of the present utility model defined by the appended claims, that is, they belong to the protection scope of the present utility model.

[0033] A mold for nickel-based alloy extrusion bars provided by the present utility model is a brand-new design. Through finite element simulation calculations, it is found that with the design of this new mold structure, the temperature rise inside the bars can be reduced. The mold designed by the present utility model can be widely used for hot extrusion of metal materials with low heat transfer coefficients such as titanium alloys and austenitic stainless steels. The main structure of the mold for nickel-based alloy extrusion bars designed by the present invention is a flat die + a suitable extrusion angle + a large chamfer. Using this mold design can always maintain good lubrication during the extrusion process. On the premise of ensuring the extrusion ratio, the temperature rise in the central area of the extrusion bar will not be too high, thereby avoiding the growth of recrystallized small grains in this area and improving the uniformity of the cross-sectional structure of the bar.

[0034] Such as Figure 1As shown in the figure, the present utility model provides a die for nickel-based alloy extrusion bars, which includes an extrusion die 1 and an extrusion cylinder 2. The outlet side of the extrusion cylinder 2 is fixedly connected to the inlet side of the extrusion die 1. The diameter of the outlet side of the extrusion die 1 is smaller than that of the inlet side, and the diameter of the outlet side of the extrusion cylinder 2 is larger than that of the inlet side of the extrusion die 1. The inner side surface of the extrusion die 1 includes a flat die section L1, a tapered die section L3, and a sizing belt L2 that are sequentially connected. The tapered die section L3 is transitionally connected to the flat die section L1 and the sizing belt L2 through an inlet fillet R1 and an outlet fillet R2 respectively. The angle between the tapered die section L3 and the axis of the outlet of the extrusion die 1 is the die angle A. In the present utility model, the size of the die angle A is 30° - 50°. The radius range of the inlet fillet R1 and the outlet fillet R2 is 50 - 100 mm.

[0035] Specifically, the outlet side of the extrusion cylinder 2 and the inlet side of the extrusion die 1 can be fixedly connected by bolts. In this way, when the extrusion die 1 needs to be replaced, it is convenient for disassembly.

[0036] In this embodiment, as Figure 1 shown, the sizing belt L2 is a cylindrical surface with a uniform diameter, the tapered die section L3 is a conical cylindrical surface with a gradually changing diameter, and the flat die section L1 is an annular surface perpendicular to the axis of the sizing belt L2. The flat die section L1 is flush with the outlet surface of the extrusion cylinder 2, and the sizing belt L2 is perpendicular to the outlet surface of the extrusion die 1. The reduction from the inner diameter of the extrusion cylinder 2 to the outlet diameter of the extrusion die 1 is achieved through the tapered die section L3 to realize the extrusion effect. By setting the flat die section L1, a part of the annular glass lubricating pad can stay at the flat die during extrusion. As the extrusion progresses, it continuously plays a lubricating role, which can ensure good lubrication throughout the extrusion process, guarantee the surface quality of the bars, and the presence of the flat die section L1 is beneficial to reducing the die angle A. The annular glass lubricating pad is arranged on the contact surface between the extrusion die and the blank. In the hot extrusion process, the annular glass lubricating pad changes from a solid state to a sticky state and forms a complete and continuous sticky film on the surface of the blank, and deforms and flows together with the blank, thereby playing a role in lubrication, heat insulation, and reducing friction, and finally forming a protective film on the surface of the extruded product. Compared with the traditional extrusion die, the die angle A in this embodiment is smaller, which can reduce the temperature rise inside the extrusion bar, avoid the growth of recrystallized small grains, and improve the uniformity of the overall grain size of the bar. And, in this embodiment, the design of the inlet fillet and the outlet fillet is added, and the radius of the inlet fillet and the outlet fillet is set to 50 - 100 mm, which can avoid dead corners, is beneficial to the uniform distribution of the molten glass lubricant on all the inner surfaces of the die, thereby reducing the frictional resistance and reducing the sudden change degree of the strain of the blank before and after the transition surface, making the strain more uniform. The combined effect of the above two aspects reduces the temperature rise inside the bar, avoids the growth of recrystallized small grains, and improves the uniformity of the overall grain size of the bar.

[0037] Optionally, the size of the die angle is 40° - 45°.

[0038] In this alternative embodiment, compared with the die angle of 60° of the traditional extrusion die, the die angle A of this embodiment can slow down the deformation degree of the blank in the deformation zone during extrusion, thereby reducing the temperature rise inside the bar after extrusion.

[0039] Optionally, the radii of the inlet rounding and the outlet rounding are 80 - 100 mm.

[0040] In this alternative embodiment, compared with the radius range of the small rounding for conventional transition (generally 10 - 30 mm), the radius values of the two roundings in this embodiment are significantly increased to 80 - 100 mm, making the transition from the flat die section to the conical surface and the transition from the conical surface to the sizing zone smoother. First, it can make the molten glass lubricant more evenly distributed on all the inner surfaces of the die, thereby reducing the frictional resistance; second, it can more effectively reduce the sudden change degree of the strain of the blank before and after the transition surface, making the strain more uniform. The combined effect of these two aspects reduces the temperature rise inside the bar.

[0041] Optionally, the length range of the sizing zone L2 is 50 - 70 mm.

[0042] Specifically, the length of the sizing zone L2 can be determined in the following way: when the diameter D2 of the extrusion end ≤ 300 mm, the length of the sizing zone L2 takes (1 / 8 - 1 / 6)D2; when D2 > 300 mm, the length of the sizing zone L2 takes (1 / 6 - 1 / 5)D2. The extrusion end diameter refers to the diameter of the end of the sizing zone L2 far from the conical die section L3.

[0043] This alternative embodiment can ensure the accuracy and uniformity of the size and shape of the extruded bar and extend the service life of the die.

[0044] Optionally, the length range of the flat die section L1 is 30 - 50 mm.

[0045] Specifically, the length of the flat die section L1 can be selected with different values according to the extrusion ratio λ and the size of the die angle A. Generally, the larger the extrusion ratio λ and the die angle A, the larger the length of the flat die section L1. The definition of the extrusion ratio λ is: λ = (D1 / D2) 2 , where D1 is the diameter of the extrusion cylinder and D2 is the diameter of the extrusion end. For example, when the extrusion ratio λ ≤ 4, when the die angle A is 30 - 40°, the length of the flat die section L1 takes (1 / 18 - 1 / 16)D1, and when the die angle A is 40 - 50°, the length of the flat die section L1 takes (1 / 16 - 1 / 14)D1; when the extrusion ratio λ > 4, the length of the flat die section L1 takes (1 / 14 - 1 / 12)D1. For the convenience of die processing, generally, integer multiples of 1 or 5 can be taken, such as 10 mm, 20 mm, 25 mm, 35 mm, 50 mm, etc.

[0046] In this optional embodiment, the flat die section L1 can allow a portion of the annular glass lubrication pad to remain at the flat die during extrusion, and continue to play a lubricating role as the extrusion proceeds, which can not only improve the surface quality of the rod, but also reduce frictional heat and reduce the temperature rise inside the extruded rod.

[0047] Optionally, the length of the flat die section is 30 mm, the length of the sizing belt is 50 mm; the die angle is 45°; and the radius of the inlet rounding and the outlet rounding is 80 mm.

[0048] In this optional embodiment, the temperature rise at R / 2 of the extruded rod can be effectively reduced, the growth of small recrystallized grains can be prevented, a finer structure can be obtained, and the uniformity of the structure of the extruded rod can be effectively improved.

[0049] Optionally, the length of the flat die section is 50 mm, the length of the sizing belt is 70 mm; the die angle is 40°; and the radius of the inlet rounding and the outlet rounding is 100 mm.

[0050] In this optional embodiment, the temperature rise inside the second half of the extruded rod can be effectively reduced, and the growth of small recrystallized grains can be prevented, thereby obtaining a more uniform structure and effectively improving the quality of the extruded rod.

[0051] Optionally, the flat die section is flush with the outlet surface of the extrusion barrel, and the sizing belt is perpendicular to the outlet surface of the extrusion die.

[0052] In this optional embodiment, the installation of the extrusion cylinder and the extrusion die can be facilitated.

[0053] Optionally, the outlet diameter of the extrusion barrel is larger than the diameter of the extrusion end of the extrusion die 1. The diameter of the extrusion end of the extrusion die 1 refers to the diameter of the connection between the flat die section L1 and the conical die section L3.

[0054] In this optional embodiment, the difference in diameter between the two facilitates the formation of a flat mold section.

[0055] Optionally, the outlet side of the extrusion cylinder and the inlet side of the extrusion die are fixedly connected by bolts.

[0056] In this optional embodiment, the bolt connection facilitates disassembly when the extrusion die needs to be replaced.

[0057] In this embodiment, the diameter D2 of the extrusion end of the general rod, the extrusion ratio λ and the die angle A are determined, which determines the length of the tapered die section L3 and the diameter D2 of the extrusion barrel. By designing the flat die section L1, the die angle A, the inlet rounding R1 and the outlet rounding R2, the die design can always maintain good lubrication during the extrusion process, while ensuring the total deformation amount and reducing the temperature rise inside the extruded rod, thereby avoiding the growth of small recrystallized grains in this area and improving the uniformity of the cross-sectional structure of the rod.

[0058] The present utility model will be further described below in conjunction with specific embodiments.

[0059] Embodiment 1

[0060] Select an IN718 alloy blank, perform homogenization heat treatment and extrusion operation after cogging forging. The size of the blank is φ500mm×300mm, and the extrusion ratio is about 3.

[0061] The parameters of the die designed in this Embodiment 1 are as follows: the flat die section L1 = 35mm, the sizing band L2 = 45mm, the die angle A = 45°, the first fillet R1 is r80mm, and the second fillet R2 is r80mm.

[0062] The operation process of the blank is as follows:

[0063] The blank is put into the furnace in the cold state, heated to 1040°C with the furnace and held for 4h;

[0064] Wait until the temperature of the forging is overall uniform, then take it out of the furnace and roll on glass powder. After placing a glass pad at the head of the blank, put it into the extrusion cylinder to start extrusion;

[0065] After extrusion and cooling, dissect the bar and observe the grain size at the R / 2 position of the bar. This grain size is about 6.8 grades, as Figure 2 shown. The temperature field of the longitudinal section of the bar after extrusion is as Figure 4 shown, and the maximum internal temperature rise is 20°C.

[0066] Comparative Example 1

[0067] Select the same IN718 alloy blank as in Embodiment 1, perform homogenization heat treatment and extrusion operation after cogging forging. The size of the blank is φ500mm×300mm, and the extrusion ratio is about 3.

[0068] In this Comparative Example 1, a traditional die with a die angle of 60° is selected. Compared with Embodiment 1, the die does not have a flat die section, the sizing band L2 is 30mm, the inlet fillet R1 is 30mm, and the outlet fillet R2 is 30mm.

[0069] The operation process of the blank is as follows:

[0070] The blank is put into the furnace in the cold state, heated to 1040°C with the furnace and held for 4h;

[0071] Wait until the temperature of the forging is overall uniform, then take it out of the furnace and roll on glass powder. After placing a glass pad at the head of the blank, put it into the extrusion cylinder to start extrusion;

[0072] After extrusion and cooling, dissect the bar and observe the grain size at the R / 2 position of the bar. This grain size is about 4.9 grades, as Figure 3 shown. The temperature field of the longitudinal section of the bar after extrusion is as Figure 5 shown, and the maximum internal temperature rise is 30°C.

[0073] From the comparison between Example 1 and Comparative Example 1, it can be seen that when using a mold with a traditional die angle of 60°, the temperature rise at the R / 2 position of the extruded bar is significantly higher, resulting in coarser grains at the R / 2 position of the extruded bar. However, by using the mold designed by the present utility model for extrusion, the temperature rise at the R / 2 position of the extruded bar can be effectively reduced, preventing the growth of recrystallized small grains, obtaining a finer microstructure, and effectively improving the tissue uniformity of the extruded bar.

[0074] Example 2

[0075] Select an IN718Plus alloy billet, and perform extrusion operations after homogenization heat treatment and cogging forging. The billet size is φ700mm×450mm, and the extrusion ratio is about 5.

[0076] The parameters of the mold designed in this Example 2 are as follows: the flat die section L1 = 60mm, the sizing section L2 = 60mm, the die angle A = 40°, the first rounding R1 is r100mm, and the second rounding R2 is r100mm.

[0077] The operation process of the billet is as follows:

[0078] The billet is put into the furnace in a cold state and heated to 1045°C with the furnace and held for 5h;

[0079] Wait until the temperature of the forging is overall uniform, then take it out of the furnace and roll on glass powder. After placing a glass pad at the head of the billet, put it into the extrusion cylinder and start extrusion;

[0080] After extrusion and cooling, dissect the bar and observe the grain size at the center of the second half of the bar. This grain size is about 7.6 grades, as Figure 6 shown. The temperature field of the longitudinal section of the bar after extrusion is as Figure 8 shown, and the maximum internal temperature rise is 25°C.

[0081] Comparative Example 2:

[0082] Select the same IN718Plus alloy billet as in Example 1, and perform extrusion operations after homogenization heat treatment and cogging forging. The billet size is φ700mm×450mm, and the extrusion ratio is about 5.

[0083] In this Comparative Example 2, a traditional mold with a die angle of 60° is selected. The mold does not have a flat die section compared with Example 2, and the sizing section L2 is 40mm, the inlet rounding R1 is 50mm, and the outlet rounding R2 is 50mm.

[0084] The operation process of the billet is as follows:

[0085] The billet is put into the furnace in a cold state and heated to 1045°C with the furnace and held for 5h;

[0086] The temperature of the forging blank is made uniform as a whole, and then it is taken out of the furnace and roll-coated with glass powder. After placing a glass pad at the head of the blank, it is put into the extrusion cylinder to start extrusion;

[0087] After extrusion and cooling, the bar is dissected, and the grain size at the center of the second half of the bar is observed. This grain size is about grade 5.5, as Figure 7 shown. The temperature field of the longitudinal section of the bar after extrusion is as Figure 9 shown, and the maximum internal temperature rise is 35°C.

[0088] It can be seen from the comparison between Example 2 and Comparative Example 2 that when using a die with a traditional die angle of 60°, the temperature rise inside the second half of the extruded bar is significantly higher, resulting in coarser grains inside the second half of the extruded bar. However, by using the die designed by the present utility model for extrusion, the temperature rise inside the second half of the extruded bar can be effectively reduced, preventing the growth of small recrystallized grains, thereby obtaining a more uniform structure and effectively improving the quality of the extruded bar.

[0089] Although the present utility model is disclosed as above, the protection scope of the present utility model is not limited thereto. Without departing from the spirit and scope of the present utility model, those skilled in the art can make various changes and modifications, and these changes and modifications will all fall within the protection scope of the present utility model.

Claims

1. A die for extruding a nickel-based alloy bar, characterized in that: The invention comprises an extrusion die (1) and an extrusion barrel (2); the outlet side of the extrusion barrel (2) is fixedly connected to the inlet side of the extrusion die (1), and the diameter of the outlet side of the extrusion die (1) is smaller than the diameter of the inlet side; the inner side surface of the extrusion die (1) comprises a flat die section (L1), a conical die section (L3) and a sizing belt (L2) connected in sequence, and the conical die section (L3) is transitionally connected to the flat die section (L1) and the sizing belt (L2) through an inlet fillet (R1) and an outlet fillet (R2) respectively; the angle between the conical die section (L3) and the axis of the outlet of the extrusion die (1) is a die angle (A), and the size of the die angle (A) is 30°-50°; the radii of the inlet fillet (R1) and the outlet fillet (R2) are 50-100 mm; the length of the sizing belt (L2) is 50-70 mm.

2. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The mold angle (A) is 40°-45°.

3. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The radii of the inlet rounding (R1) and the outlet rounding (R2) are 80-100 mm.

4. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The length of the sizing belt (L2) is determined in the following manner: when the extrusion end diameter D2 is ≤300 mm, the length of the sizing belt (L2) is 1 / 8 to 1 / 6 of D2; when the extrusion end diameter D2 is greater than 300 mm, the length of the sizing belt (L2) is 1 / 6 to 1 / 5 of D2, wherein D2 is the extrusion end diameter of the extrusion die (1).

5. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The length of the flat die section (L1) is determined in the following manner: when the extrusion ratio λ≤4, when the die angle (A) is 30-40°, the length of the flat die section (L1) is 1 / 18-1 / 16 of D1; when the die angle (A) is 40-50°, the length of the flat die section (L1) is 1 / 16-1 / 14 of D1; when the extrusion ratio λ>4, the length of the flat die section (L1) is 1 / 14-1 / 12 of D1, wherein D1 is the diameter of the extrusion cylinder (2).

6. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The length of the flat die section (L1) is 35 mm, the length of the sizing belt (L2) is 45 mm; the size of the die angle (A) is 45°; the radii of the inlet chamfer (R1) and the outlet chamfer (R2) are 80 mm.

7. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The length of the flat die section (L1) is 60 mm, the length of the sizing belt (L2) is 60 mm; the size of the die angle (A) is 40°; the radii of the inlet chamfer (R1) and the outlet chamfer (R2) are 100 mm.

8. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The flat die section (L1) is flush with the outlet surface of the extrusion cylinder (2), and the sizing belt (L2) is perpendicular to the outlet surface of the extrusion die (1).

9. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The diameter of the outlet of the extrusion cylinder (2) is larger than the diameter of the extrusion end of the extrusion die (1).

10. The die for extruding a nickel-based alloy bar according to claim 1, characterized in that: The outlet side of the extrusion cylinder (2) and the inlet side of the extrusion die (1) are fixedly connected by bolts.

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