Preparation method and product of Ti6246 with high creep performance and high structural uniformity

Abstract

The present invention discloses a preparation method and product of Ti6246 with high creep performance and high microstructure uniformity, comprising: (1) raw material selection; (2) ingot preparation; (3) ingot blanking forging; (4) deformation recrystallization forging; (5) α+β phase region upsetting and drawing forging; and (6) α+β phase region temperature-controlled and time-controlled drawing forging. The ingot innovatively adds a suitable amount of trace silicon, laying a compositional foundation for producing bars with high creep performance; the α+β phase region upsetting and drawing forging maintains a suitable cumulative forging deformation, so that the microstructure does not reduce creep performance or plasticity; the α+β phase region temperature-controlled and time-controlled drawing forging stage is precisely controlled to be forged at a relatively high heating temperature, and the positive effect of the microstructure generated by the increase in heating temperature on the creep performance is engineered and utilized. At the same time, in order to prevent overheating during forging at a relatively high heating temperature, the total forging time is controlled within 12 minutes, thereby ensuring microstructure uniformity.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy material processing, and in particular to a method for preparing Ti6246 with high creep performance and high structural uniformity, and a product (titanium alloy bar with a diameter of 200mm-300mm) manufactured according to the method for preparing Ti6246 with high creep performance and high structural uniformity. Background Art

[0002] The nominal composition of Ti6246 titanium alloy is Ti-6Al-2Sn-4Zr-6Mo (Wt%), and its Chinese brand is TC19 titanium alloy. Its long-term service temperature is around 420°C. It is mainly used for medium-temperature section components of aircraft engines, such as compressor disks, fans and blades. During high-temperature use, titanium alloy is subjected to long-term internal or external mechanical loads, which may cause metal parts to creep and deform, affecting the accuracy, and ultimately causing the size and performance of the parts to fail to meet the use requirements. Therefore, solving the creep problem under long-term high-temperature service conditions is very prominent. Summary of the Invention

[0003] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to provide a preparation method of Ti6246 with high creep performance and high structural uniformity. The finished rods produced have a diameter of 200mm-300mm, excellent structural uniformity and comprehensive mechanical properties (such as high-temperature creep performance), and are suitable for industrial production.

[0004] The technical solution of the present invention is: a method for preparing Ti6246 with high creep performance and high structural uniformity, which comprises the following steps:

[0005] (1) Raw material selection: The raw materials used are titanium sponge with a particle size of 3 to 12.7 mm, Al-60Mo with a particle size of ≤0.8 mm, zirconium sponge with a particle size of 1 to 12 mm, TiO2, aluminum beans, Ti-80Sn chips, and Al-10Si chips;

[0006] (2) Ingot preparation: All raw materials are mixed according to the expected value of the ingot composition. After three vacuum consumable smelting (VAR), the pressure of the ingot during the last smelting is less than 1.33 Pa, and finally an ingot with uniform composition and meeting the requirements of GB / T3620.1, AMS4981 or GJB 2218A is produced;

[0007] (3) Ingot forging: heating temperature is 1050℃~1200℃, holding time is controlled to [(0.55~0.80)×minimum cross-sectional size of the billet]min, the ingot is subjected to 1~2 rounds of upsetting and drawing forging (the total number of upsetting and drawing is controlled to be 4~8 times), the upsetting and drawing deformation of each forging is controlled to be between 35%~45%, air cooling or hot material returning to furnace after forging (hot material returning to furnace holding time is controlled to be 90~150min), and the total forging time of each round is ≤20min;

[0008] (4) Deformation recrystallization forging: the heating temperature is 30℃~60℃ below the phase transformation point temperature, the holding time is controlled to [(0.70~1.00)×the minimum cross-sectional size of the blank]min, the blank is subjected to one fire of upsetting and drawing forging (the total number of upsetting and drawing is controlled to 4 times), the upsetting and drawing deformation of each forging is controlled to be between 20% and 30%, after forging, the hot material is returned to the furnace and heated to 50℃~80℃ above the phase transformation point temperature, the holding time is controlled to [(0.35~0.55)×the minimum cross-sectional size of the blank]min, the blank is subjected to one fire of upsetting and drawing forging (the total number of upsetting and drawing is controlled to 2 times), the upsetting and drawing deformation of each forging is controlled to be between 15% and 25%, air cooling is performed after forging, and the total upsetting and drawing forging time of each fire is ≤17min;

[0009] (5) Upsetting forging in α+β phase region: the heating temperature is 40℃~60℃ below the phase transition point temperature, the holding time is controlled to be [(0.70~1.00)×minimum cross-sectional size of the blank]min, the blank is subjected to two upsetting forgings (the total number of upsettings is controlled to be 4 times), the upsetting and drawing deformation of each forging is controlled between 30% and 40%, the upsetting is performed at a uniform speed and the upsetting rate is ≤

[0010] 10mm / s, drawing and pressing rate ≤25mm / s, air cooling after forging or hot material returning to the furnace (hot material returning to the furnace and holding time is controlled within 90-150min), total forging time per fire ≤15min;

[0011] (6) Temperature and time controlled drawing forging in the α+β phase region: the heating temperature is below the phase transition point

[0012] 25℃~35℃, the holding time is controlled as [(0.70~1.00)×minimum cross-sectional size of the blank]

[0013] min, the billet is subjected to 4 to 6 fires of drawing forging (the total number of drawing is controlled to be 4 to 6 times), and finally drawn to the finished product specification size bar, and the drawing deformation of each forging is controlled within 15%~

[0014] 30%, the drawing reduction rate is ≤25mm / s, air cooling after forging or hot material returning to the furnace, the total forging time per fire is ≤12min.

[0015] While meeting the requirements of domestic and international standards, the present invention innovatively adds an appropriate amount of trace silicon to the ingot, and utilizes the strengthening effect of silicon on creep performance in an engineered manner, laying a compositional foundation for producing bars with high creep performance; the α+β phase region upsetting and drawing forging maintains an appropriate forging ratio, so that the microstructure does not suffer from excessive spheroidization due to an excessively large forging ratio, thereby reducing creep performance, nor does it suffer from insufficient spheroidization due to an excessively small cumulative deformation, thereby reducing plastic performance; the temperature and time controlled drawing and forging stage in the α+β phase region is precisely controlled to be forged at a higher heating temperature, and the positive effect of the microstructure generated by "increase in heating temperature" on creep performance is utilized in an engineered manner. At the same time, in order to prevent overheating during forging at a higher heating temperature, the total forging time is controlled within 12 minutes, thereby ensuring the uniformity of the microstructure.

[0016] Also provided is a titanium alloy bar manufactured by a preparation method of the Ti6246 titanium alloy bar with high creep performance and high structural uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the microstructure of the Φ265mm bar (left: edge, right: core).

[0018] Figure 2 This is the microstructure of the Φ265mm bar (left: edge, right: core).

[0019] Figure 3 The figure is a flow chart of the preparation method of Ti6246 with high creep performance and high structural uniformity according to the present invention. DETAILED DESCRIPTION

[0020] like Figure 1 As shown, a method for preparing Ti6246 with high creep performance and high structural uniformity comprises the following steps:

[0021] (1) Raw material selection: The raw materials are titanium sponge with a particle size of 3 to 12.7 mm,

[0022] Al-60Mo with a particle size of ≤0.8mm, zirconium sponge with a particle size of 1 to 12mm, TiO2, aluminum beans, Ti-80Sn chips, and Al-10Si chips;

[0023] (2) Ingot preparation: All raw materials are mixed according to the expected value of the ingot composition. After three vacuum consumable smelting (VAR), the pressure of the ingot during the last smelting is less than 1.33 Pa, and finally an ingot with uniform composition and meeting the requirements of GB / T3620.1, AMS4981 or GJB 2218A is produced;

[0024] (3) Ingot forging: heating temperature is 1050℃~1200℃, keeping warm, and performing 1~2 fire upsetting and drawing forging on the ingot. The upsetting and drawing deformation of each forging is controlled within 35%~

[0025] 45%, air cooling after forging or hot material returning to the furnace, the total forging time per fire is ≤20min;

[0026] (4) Deformation recrystallization forging: The heating temperature is 30℃~60℃ below the phase transition point temperature, and the billet is kept warm. The upsetting and drawing deformation of each forging is controlled between 20% and 30%. After forging, the hot material is returned to the furnace to a temperature above the phase transition point.

[0027] Heat at 50℃~80℃, keep warm, and perform another round of upsetting and drawing forging on the blank. The upsetting and drawing deformation of each forging is controlled between 15% and 25%. Air cool after forging. The total upsetting and drawing forging time of each fire is ≤17min.

[0028] (5) Upsetting and drawing forging in α+β phase region: heating temperature is 40℃~60℃ below the phase transition point temperature, keeping warm, and performing upsetting and drawing forging for the blank twice. The upsetting and drawing deformation of each forging are controlled between 30% and 40%. The upsetting is performed at a uniform speed and the upsetting rate is ≤10mm / s, and the drawing reduction rate is ≤25mm / s. After forging, the blank is air-cooled or the hot material is returned to the furnace. The total forging time for each fire is

[0029] ≤15min;

[0030] (6) Temperature and time controlled drawing and forging in the α+β phase region: the heating temperature is 25°C below the phase transition point

[0031] ~35℃, keep warm, and carry out 4~6 rounds of drawing forging on the billet, and finally draw it to the finished bar size. The deformation of each forging is controlled between 15% and 30%, and the drawing reduction rate is ≤25mm / s. After forging, air cool or return the hot material to the furnace. The total forging time for each round is ≤12min.

[0032] While meeting the requirements of domestic and international standards, the present invention innovatively adds an appropriate amount of trace silicon to the ingot, and utilizes the strengthening effect of silicon on creep performance in an engineered manner, laying a compositional foundation for producing bars with high creep performance; the α+β phase region upsetting and drawing forging maintains an appropriate cumulative deformation, so that the structure does not suffer from excessive spheroidization due to excessive cumulative deformation, thereby reducing creep performance, nor does it suffer from insufficient spheroidization due to insufficient cumulative deformation, thereby reducing plastic performance; the α+β phase region temperature and time controlled drawing and forging stage is precisely controlled to be forged at a higher heating temperature, and the positive effect of the structure generated by "increase in heating temperature" on creep performance is utilized in an engineered manner. At the same time, in order to prevent overheating during forging at a higher heating temperature, the total forging time is controlled within 12 minutes, thereby ensuring the uniformity of the structure.

[0033] Preferably, referring to Table 1, in step (2), the target value Wt% of the ingot composition is: Al, 5.95-6.15; Zr, 4.00-4.20; Sn, 1.95-2.10; Mo, 6.15-6.30; O, 0.090-0.110; and Si, 0.035-0.070.

[0034] Table 1 Target values ​​of chemical composition of ingot

[0035]

[0036] Preferably, in the step (3), two rounds of upsetting and drawing forging are performed: first, the heating temperature is 1150°C, the holding time is controlled to be [(0.55-0.80) × the minimum cross-sectional size of the billet] min, the ingot is subjected to the first round of upsetting and drawing forging, the total cumulative number of upsetting and drawing in this round is controlled to be 4 times, the upsetting and drawing deformation of each forging is controlled to be 45%, air cooling is performed after forging, and the total forging time is 19 minutes; then, the heating temperature is 1080°C, the holding time is 390 minutes, the billet is subjected to the second round of upsetting and drawing forging, the total cumulative number of upsetting and drawing in this round is controlled to be 4 times, the upsetting and drawing deformation of each forging is controlled to be 43%, air cooling is performed after forging, and the total forging time is ≤17 minutes.

[0037] Preferably, in the step (3), the total cumulative number of upsetting times in each of the first and second upsetting forging fires is controlled to be 4 times.

[0038] Preferably, in the step (4), two rounds of upsetting and drawing forging are performed: first, the heating temperature is 40°C below the phase transformation point temperature, the holding time is controlled to be [(0.70-1.00)×the minimum cross-sectional size of the blank] min, and the blank is subjected to the third round of upsetting and drawing forging, the upsetting and drawing deformation of each forging is controlled to 25%, and the total forging time is 15 min; then, the hot material is returned to the furnace and heated to 60°C above the phase transformation point temperature, the holding time is controlled to be [(0.35-0.55)×the minimum cross-sectional size of the blank] min, and the blank is subjected to the fourth round of upsetting and drawing forging, the upsetting and drawing deformation of each forging is controlled to 20%, and air cooling is performed after forging, and the total forging time is 8 min.

[0039] Preferably, in the step (4), the total cumulative number of upsetting operations in the third upsetting forging process is controlled to be 4 times, and the total cumulative number of upsetting operations in the fourth upsetting forging process is controlled to be 2 times.

[0040] Preferably, in the step (5), two rounds of upsetting and drawing forging are performed: first, the heating temperature is 40°C below the phase transition point temperature, the holding time is controlled to be [(0.70-1.00) × the minimum cross-sectional size of the billet] min, and the billet is subjected to the fifth round of upsetting and drawing forging, the upsetting and drawing deformation of each forging is controlled to be 40%, and the total forging time is 12 min; then, the hot material is returned to the furnace at the original temperature, the holding time of the hot material is controlled to be 90-150 min, and the billet is subjected to the sixth round of upsetting and drawing forging, the upsetting and drawing deformation of each forging is controlled to be 40%, and air cooling is performed after forging, and the total forging time is 11 min.

[0041] Preferably, in the step (5), the total cumulative number of upsetting times in each of the 5th and 6th upsetting forging fires is controlled to be 2 times.

[0042] Preferably, in the step (6), 5 fires of upsetting forging are performed: first, the heating temperature is 35°C below the phase transition point temperature, the holding time is controlled to be [(0.70-1.00)×the minimum cross-sectional size of the blank] min, the blank is subjected to the 7th fire of drawing forging, the drawing deformation is controlled to be 30%, and the total forging time is 7 min; then, the original temperature hot material is returned to the furnace, the hot material is returned to the furnace and the holding time is controlled to be 90-150 min, the blank is subjected to the 8th fire of drawing forging, the drawing deformation is controlled to be 30%, air cooling is performed after forging, and the total forging time is 8 min; then, the heating temperature is 30°C below the phase transition point temperature, the holding time is controlled to be [(0.70-1.00)×the minimum cross-sectional size of the blank] m in, the billet is subjected to the 9th fire of drawing forging, the drawing deformation is controlled at 25%, and the total forging time is 8min; then, the original temperature hot material is returned to the furnace, and the hot material holding time is controlled at 90-150min. The billet is subjected to the 10th fire of drawing forging, the drawing deformation is controlled at 25%, and air cooling is performed after forging, and the total forging time is 8min; finally, the heating temperature is 25°C below the phase transformation point temperature, the holding time is controlled to [(0.70-1.00) × the minimum cross-sectional size of the billet]min, the billet is subjected to the 11th fire of rounded finished product drawing forging, the drawing deformation is controlled at 15%, the total forging time is 12min, and air cooling is performed after forging. The final specification is the finished black skin bar with a specification of Φ265mm.

[0043] Also provided is a titanium alloy bar manufactured by the preparation method of the Ti6246 with high creep performance and high structural uniformity.

[0044] The specific embodiments of the present invention are described in detail below.

[0045] Example 1

[0046] Step 1) Raw material selection

[0047] The raw materials used include sponge titanium with a particle size of 3 to 12.7 mm, Al-60Mo with a particle size of ≤0.8 mm, sponge zirconium with a particle size of 1 to 12 mm, TiO2, aluminum beans, chips of Ti-80Sn, and chips of Al-10Si.

[0048] Step 2) Ingot preparation

[0049] The raw materials were mixed according to the selected raw materials to prepare consumable electrodes. The vacuum consumable melting method was used to carry out three vacuum consumable melting processes. The pressure in the stable stage of the last melting process was not greater than 5 Pa. A Ti6246 titanium alloy ingot with a specification of Φ680 mm was obtained (the specific composition is shown in the table below, and its composition meets the requirements of GB / T3620.1 or AMS4981 or GJB 2218A standards). The β-transus temperature of the ingot was measured to be 945°C.

[0050] Table 2 Chemical composition test values ​​of ingots

[0051]

[0052] Step 3) Ingot forging

[0053] The heating temperature is 1150℃, and the temperature is kept for 480min. The ingot is subjected to the first round of upsetting and drawing forging (the total number of upsetting and drawing in this round is controlled at 4 times). The upsetting and drawing deformation of each forging is controlled at 45%. It is air-cooled after forging, and the total forging time is 19min.

[0054] The heating temperature is 1080℃, and the temperature is kept for 390min. The billet is subjected to the second upsetting forging (the total number of upsetting and drawing is controlled at 4 times). The upsetting and drawing deformation of each forging is controlled at 43%. It is air-cooled after forging, and the total forging time is ≤17min.

[0055] Step 4) Deformation Recrystallization Forging

[0056] The heating temperature is 40°C below the phase transformation point temperature, and the temperature is kept for 420 minutes. The billet is subjected to the third upsetting and drawing forging (the total number of upsetting and drawing in this fire is controlled to 4 times), the upsetting and drawing deformation of each forging is controlled at 25%, and the total forging time is 15 minutes. After forging, the hot material is returned to the furnace and heated to 60°C above the phase transformation point temperature, and the temperature is kept for 330 minutes. The billet is subjected to the fourth upsetting and drawing forging (the total number of upsetting and drawing in this fire is controlled to 2 times), the upsetting and drawing deformation of each forging is controlled at 20%, and air cooling is performed after forging. The total forging time is 8 minutes.

[0057] Step 5) Upsetting and forging in α+β phase region

[0058] The heating temperature is 40°C below the phase transition point temperature, the holding time is 420min, and the billet is subjected to the 5th upsetting and drawing forging (the total number of upsetting and drawing in this fire is controlled to be 2 times), the upsetting and drawing deformation of each forging is controlled to be 40%, the total forging time is 12min, and the original temperature hot material is returned to the furnace after forging and kept warm for 120min. The billet is subjected to the 6th upsetting and drawing forging (the total number of upsetting and drawing in this fire is controlled to be 2 times), the upsetting and drawing deformation of each forging is controlled to be 40%, the upsetting is performed at a uniform speed and the upsetting rate is 10mm / s, the drawing reduction rate is 25mm / s, and the billet is air-cooled after forging. The total forging time is 11min.

[0059] Step 6) α+β phase temperature and time controlled drawing forging

[0060] The heating temperature is 35°C below the phase transformation point temperature, the holding time is 420min, the billet is subjected to the 7th drawing forging, the drawing deformation is controlled at 30%, the total forging time is 7min, the original temperature hot material is returned to the furnace after forging, and the holding time is 90min. The billet is subjected to the 8th drawing forging, the drawing deformation is controlled at 30%, the drawing reduction rate is 25mm / s, and it is air-cooled after forging. The total forging time is 8min.

[0061] The heating temperature is 30°C below the phase transformation point temperature, the holding time is 240min, the billet is subjected to the 9th drawing forging, the drawing deformation is controlled at 25%, the drawing reduction rate is 25mm / s, the total forging time is 8min, and the original temperature hot material is returned to the furnace after forging and held for 90min. The billet is subjected to the 10th drawing forging, the drawing deformation is controlled at 25%, the drawing reduction rate is 25mm / s, and it is air-cooled after forging. The total forging time is 8min.

[0062] The heating temperature is 25℃ below the phase transition point, the holding time is 210min, and the billet is subjected to the 11th rounding finished product drawing forging. The drawing deformation is controlled at 15%, the drawing reduction rate is 25mm / s, the total forging time is 12min, and air cooling is performed after forging. The final specification is the finished black bar with a specification of Φ265mm.

[0063] The specimens were cut from the finished bar and heat treated at 895℃ / 1h, air cooling + 593℃ / 6h, and air cooling. The mechanical properties are shown in the table below. Referring to the corresponding requirements of the AMS4981 standard, it can be seen that the performance margins are sufficient (especially the high temperature creep performance).

[0064] Table 3 Mechanical properties test values ​​of bars

[0065]

[0066]

[0067] Figure 1 This is the microstructure diagram of the finished product with a specification of Φ265mm prepared by this process. It can be seen that the microstructure of the edge and the core is a uniform, slightly long short rod equiaxed structure, which has higher creep performance and sufficient plasticity margin.

[0068] Implementation Counterexample 1

[0069] Except that the Al-10Si raw material is not used in step 1 and the silicon element is not added in step 2, the rest is exactly the same as in Example 1.

[0070] The chemical composition of the produced ingot is shown in Table 4, from which it can be seen that the Si content is extremely low, and the contents of other elements are comparable to those in Example 1.

[0071] Table 4 Chemical composition test values ​​of ingots

[0072]

[0073] The specimens were cut from the finished bar and subjected to heat treatment at 895°C / 1h, air cooling + 593°C / 6h, and air cooling. The mechanical properties were tested as shown in the table below. Referring to the corresponding requirements of the AMS4981 standard, it can be seen that the creep performance is significantly worse than that of Example 1.

[0074] Table 5 Test values ​​of mechanical properties of bars

[0075]

[0076] Implementation Counterexample 2

[0077] On the basis of implementing counter-example one, except for adding two more fire deformations in step five (the total number of upsetting and drawing in the two added fires is 4 times, and the total number of upsetting and drawing in step five is 8 times), which is exactly the same as the number of fires in step five of implementing counter-example one, the rest is exactly the same as implementing counter-example one.

[0078] The specimens were cut from the finished bar and subjected to heat treatment at 895°C / 1h, air cooling + 593°C / 6h, and air cooling. The mechanical properties were tested as shown in the table below. Referring to the corresponding requirements of the AMS4981 standard, it can be seen that the creep performance is worse than that of the counter-example 2 (the chemical composition of the ingot used in this bar is exactly the same as that of the counter-example 1).

[0079] Table 6 Test values ​​of mechanical properties of bars

[0080]

[0081] Figure 2 This is the microstructure diagram of the finished rod with a specification of Φ265mm produced by this process. It can be seen that the microstructure of the edge and the core is an equiaxed structure with a high degree of spheroidization, which reduces the creep performance (even unqualified).

[0082] Implementation Counterexample 3

[0083] Based on the implementation of counter-example 2, except that the heating and holding temperature of the last fire in step 6 is lowered to 55°C below the phase transition point temperature, the rest is exactly the same as the implementation of counter-example 3.

[0084] The samples were cut from the finished bars and subjected to heat treatment at 895°C / 1h, air cooling + 593°C / 6h, and air cooling. The mechanical properties were tested as shown in the table below. Referring to the corresponding requirements of the AMS4981 standard, it can be seen that the creep performance is significantly worse than that of Example 1 (the chemical composition of the ingot used in this bar is exactly the same as that of Counterexample 2).

[0085] Table 7 Mechanical properties test values ​​of bars

[0086]

[0087] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing Ti6246 with high creep performance and high structural uniformity, characterized by: It includes the following steps: (1) Raw material selection: The raw materials used are titanium sponge with a particle size of 3~12.7mm, Al-60Mo with a particle size ≤0.8mm, zirconium sponge with a particle size of 1~12mm, TiO2, aluminum beans, Ti-80Sn chips, and Al-10Si chips; (2) Ingot preparation: All raw materials are mixed according to the expected value of the ingot composition. After three vacuum consumable smelting (VAR), the pressure of the ingot during the last smelting is less than 1.33 Pa, and finally an ingot with uniform composition and meeting the requirements of GB / T3620.1, AMS4981 or GJB2218A standards is produced; (3) Ingot forging: heating temperature is 1050℃~1200℃, keeping warm, and performing 1~2 rounds of upsetting and drawing forging on the ingot. The upsetting and drawing deformation of each forging is controlled between 35% and 45%. After forging, the ingot is air-cooled or the hot material is returned to the furnace. The total forging time for each round is ≤20min. (4) Deformation recrystallization forging: The heating temperature is 30℃~60℃ below the phase transition point temperature, and the temperature is kept warm. The billet is subjected to one round of upsetting and drawing forging. The upsetting and drawing deformation of each forging is controlled between 20% and 30%. After forging, the hot material is returned to the furnace to be heated 50℃~80℃ above the phase transition point, and the temperature is kept warm. The billet is subjected to another round of upsetting and drawing forging. The upsetting and drawing deformation of each forging is controlled between 15% and 25%. After forging, it is air-cooled. The total time of upsetting and drawing forging for each round is ≤17min. (5) Upsetting and drawing forging in α+β phase region: heating temperature is 40℃~60℃ below the phase transition point temperature, keeping warm, and performing upsetting and drawing forging on the blank for 2 times. The upsetting and drawing deformation of each forging is controlled between 30% and 40%. The upsetting is performed at a uniform speed and the upsetting rate is ≤10mm / s, and the drawing reduction rate is ≤25mm / s. After forging, the blank is air-cooled or the hot material is returned to the furnace. The total forging time for each fire is ≤15min. (6) Temperature and time controlled drawing forging in the α+β phase region: the heating temperature is 25℃~35℃ below the phase transformation point temperature, and the billet is kept warm. The billet is drawn forged for 4~6 times, and finally drawn to the finished bar size. The deformation of each forging is controlled between 15% and 30%, and the drawing reduction rate is ≤25mm / s. After forging, the billet is air-cooled or the hot material is returned to the furnace. The total forging time for each forging is ≤12min. In the step (2), the target value Wt% of the ingot composition is: Al, 5.95~6.15; Zr, 4.00~4.20; Sn, 1.95~2.10; Mo, 6.15~6.30; O, 0.090~0.110; Si, 0.035~0.070; In the step (3), two rounds of upsetting and drawing forging are performed: first, the heating temperature is 1150°C, the holding time is controlled to be [(0.55-0.80) × the minimum cross-sectional size of the billet] min, the ingot is subjected to the first round of upsetting and drawing forging, the total cumulative number of upsetting and drawing in this round is controlled to be 4 times, the upsetting and drawing deformation of each forging is controlled to be 45%, air cooling is performed after forging, and the total forging time is 19 minutes; then, the heating temperature is 1080°C, the holding time is controlled to be [(0.55-0.80) × the minimum cross-sectional size of the billet] min, the billet is subjected to the second round of upsetting and drawing forging, the total cumulative number of upsetting and drawing in this round is controlled to be 4 times, the upsetting and drawing deformation of each forging is controlled to be 43%, air cooling is performed after forging, and the total forging time is ≤17 minutes.

2. The method for preparing Ti6246 with high creep performance and high structural uniformity according to claim 1, characterized in that: In the step (4), two rounds of upsetting and drawing forging are performed: first, the heating temperature is 40°C below the phase transformation point temperature, the holding time is controlled to [(0.70-1.00) × the minimum cross-sectional size of the blank] min, the blank is subjected to the third round of upsetting and drawing forging, the upsetting and drawing deformation of each forging is controlled to 25%, and the total forging time is 15 min; then, the hot material is returned to the furnace and heated to 60°C above the phase transformation point temperature, the holding time is controlled to [(0.35-0.55) × the minimum cross-sectional size of the blank] min, the blank is subjected to the fourth round of upsetting and drawing forging, the upsetting and drawing deformation of each forging is controlled to 20%, air cooling is performed after forging, and the total forging time is 8 min.

3. The method for preparing Ti6246 with high creep performance and high structural uniformity according to claim 2, characterized in that: In the step (4), the total cumulative number of upsetting forgings in the third fire is controlled to be 4 times, and the total cumulative number of upsetting forgings in the fourth fire is controlled to be 2 times.

4. The method for preparing Ti6246 with high creep performance and high structural uniformity according to claim 3, characterized in that: In the step (5), two rounds of upsetting and drawing forging are performed: first, the heating temperature is 40°C below the phase transition point temperature, the holding time is controlled to be [(0.70-1.00) × the minimum cross-sectional size of the billet] min, the billet is subjected to the fifth round of upsetting and drawing forging, the upsetting and drawing deformation of each forging is controlled to be 40%, and the total forging time is 12 min; then, the original temperature hot material is returned to the furnace, the holding time of the hot material is controlled to be 90-150 min, the billet is subjected to the sixth round of upsetting and drawing forging, the upsetting and drawing deformation of each forging is controlled to be 40%, and air cooling is performed after forging, and the total forging time is 11 min.

5. The method for preparing Ti6246 with high creep performance and high structural uniformity according to claim 4, characterized in that: In the step (5), the total cumulative number of upsetting times in each of the 5th and 6th upsetting forging fires is controlled to be 2 times.

6. The method for preparing Ti6246 with high creep performance and high structural uniformity according to claim 5, characterized in that: In the step (6), 5 fires of drawing forging are performed: first, the heating temperature is 35°C below the phase transformation point temperature, the holding time is controlled to be [(0.70-1.00) × the minimum cross-sectional size of the billet] min, the billet is subjected to the 7th fire of drawing forging, the drawing deformation is controlled to be 30%, and the total forging time is 7 min; then, the original temperature hot material is returned to the furnace, the hot material is returned to the furnace and the holding time is controlled to be 90-150 min, the billet is subjected to the 8th fire of drawing forging, the drawing deformation is controlled to be 30%, air cooling is performed after forging, and the total forging time is 8 min; then, the heating temperature is 30°C below the phase transformation point temperature, the holding time is controlled to be [(0.70-1.00) × the minimum cross-sectional size of the billet] min , the billet is subjected to the 9th fire drawing forging, the drawing deformation is controlled at 25%, and the total forging time is 8min; then, the original temperature hot material is returned to the furnace, and the hot material is returned to the furnace for a holding time of 90~150min. The billet is subjected to the 10th fire drawing forging, the drawing deformation is controlled at 25%, and air cooling is performed after forging. The total forging time is 8min; finally, the heating temperature is 25℃ below the phase transformation point temperature, and the holding time is controlled to [(0.70~1.00)×the minimum cross-sectional size of the billet]min. The billet is subjected to the 11th fire rounding finished product drawing forging, the drawing deformation is controlled at 15%, the total forging time is 12min, and air cooling is performed after forging. The final specification is the finished black skin bar with a specification of Φ265mm.

7. Titanium alloy rod manufactured according to the preparation method of Ti6246 with high creep performance and high structural uniformity according to any one of claims 1 to 6.

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