Titanium alloy shaft sleeve forge piece forming control method

Abstract

The invention belongs to the technical field of titanium alloy thermal deformation, and discloses a titanium alloy shaft sleeve forge piece forming control method which comprises the following steps: aiming at the structural characteristics of shaft sleeve parts, designing two shaft sleeve forge pieces in a bilateral symmetry manner, and forging a round bar into a step-shaped intermediate blank with a large middle size and two small ends by adopting a tool; forging forming of two pieces in one die is completed in a die forging mode, one end of the finally obtained shaft sleeve forge piece is square, the other end is round, the local size precision is high, and the room-temperature comprehensive performance is excellent. The problems that at present, domestic titanium alloy small and medium-sized die forging blanks are complex in shape design, the blanks are difficult to position and prone to deflection during die filling, local bosses are difficult to fill during die forging forming, and the material utilization rate and the production efficiency are low during single-piece forming are effectively solved. Multi-batch shaft sleeve forgings produced through the method are low in single piece cost, high in production efficiency, high in batch stability and good in repeatability.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy thermal deformation, and particularly relates to a forming control method for a titanium alloy shaft sleeve forging. Background Art

[0002] TB6 (Ti-10V-2Fe-3Al) titanium alloy boasts high specific strength, good fracture toughness, and strong stress corrosion resistance. Hot die forging or isothermal forging processes are widely used to produce titanium alloy forgings both domestically and internationally. TB6 titanium alloy is used in the production of various aircraft component forgings. However, the forming process currently presents the following challenges: Some parts (such as centerpieces, connectors, folding joints, and tail reduction platforms) are forged using isothermal forging, which results in complex intermediate blank design and difficulty in local positioning during die assembly. Furthermore, the molds are made of high-temperature alloys, resulting in relatively high mold material and cavity processing costs. The forming process is one die per piece, resulting in relatively high per-piece cost and low production efficiency. Some parts (such as external connectors, angles, and horizontal tailpieces) are forged using open die forging. This process relies on individual worker experience, resulting in poor local dimensional accuracy control and a tendency for bulging or excessively rounded corners to occur. This results in high single-piece weight, extensive machining, low material utilization, and lower microstructure and performance compared to die forgings.

[0003] The TB6 titanium alloy bushings involved in the present invention belong to the category of small and medium-sized die forgings, and cooperate with the central part, and the stress conditions are complex. Most TB6 titanium alloy bushings are left-right asymmetrical special-shaped structural parts, shaped like bone rods, with one end being square and larger in size, and the other end being cylindrical and smaller in size. There are four forks with pin holes on the four corners of the square head end, and it is hollow along the axial direction, and the overall structure is relatively complex. When the bushing is formed by the one-die-one-piece isothermal forging method, due to the small size of the bushing, it is easy to cause the isothermal forging die investment cost to be high, the single-piece production efficiency is not high, and the manufacturing cost is high. When the bushing is formed by the free forging method, it is easy to cause the single-piece dimensional accuracy to be difficult to accurately control, the feed weight is large, resulting in low material utilization, high raw material cost and processing cost, low production efficiency, and poor performance level. Therefore, it is urgent to improve the existing isothermal forging and free forging processes to improve the local dimensional accuracy and performance level of the forgings, while reducing the cost of the single forgings and improving production efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a titanium alloy shaft sleeve forging forming control method to address the current technical problems of domestic titanium alloy small and medium-sized die forgings, such as complex blank shape design, difficult blank positioning and easy deflection during die loading, difficulty filling local bosses during die forging, low efficiency and prone to uneven loading during single-piece forming. The small and medium-sized die forgings involved in the present invention typically have a length L of 380 mm to 220 mm, a width W of 280 mm to 220 mm, a height H of 280 mm to 180 mm, and a weight M of 120 kg to 30 kg.

[0005] To solve this technical problem, the technical solution of the present invention is:

[0006] A titanium alloy shaft sleeve forging forming control method, the method steps are as follows:

[0007] Step 1: Prepare ingredients:

[0008] Prepare a fixed-length or multiple-length TB6 titanium alloy bar with a diameter of (W+10) mm and a weight ≥ (2M+10) kg, and ensure that the bar undergoes high-low-high multi-fire forging in alternating single-phase and two-phase regions; where W is the width of the forging after forming, and M is the weight;

[0009] Step 2: Forging the intermediate billet:

[0010] Heat the electric furnace to (T β -25)℃~(T β -65)℃, after reaching the temperature, the TB6 titanium alloy rod is loaded, and the holding time after the furnace reaches the temperature again is calculated as (0.5~1.0)min / mm;

[0011] Step 3: Machining the intermediate blank:

[0012] The cross section of the intermediate billet at the position (L / 2+10) mm from the two end faces in the length direction is controlled as (W-55) mm × (H+3) mm, and the cross section of the middle section in the length direction of the intermediate billet is controlled as (W+5) mm × (H+5) mm; after machining, the billet weight should be ≥ (2M+5) kg; L is the length of the forging after forming;

[0013] Step 4: Die forging:

[0014] Preheat the TB6 titanium alloy intermediate billet, keep it warm, preheat the die before forging, control the pressing speed during die forging at 0.05mm / s to 6.0mm / s, the underpressure amount ≤10mm, the final forging temperature of the billet ≥600℃, and air cool after forging;

[0015] Step 5: Rough machining:

[0016] Divide the forging into two parts along the middle of the length direction and cut out test pieces for testing;

[0017] Step 6: Heat the electric furnace to (T β -25)℃~(T β -65)℃ for heat treatment.

[0018] Furthermore, the method of the present invention is to design two shaft sleeve forgings to be bilaterally symmetrical, use a flat tooling to forge a square bar into a stepped intermediate blank with a large middle and small ends, and complete the forging of two pieces in one die by die forging; the specific steps are:

[0019] Step 1: Prepare ingredients:

[0020] Prepare fixed-length or multiple-length TB6 titanium alloy bars according to the size and weight of the final forging. Among them, the multiple-length bars need to be wire-cut and divided according to (2M+10) kg per bar to ensure that the bars are forged through high-low-high multiple fires alternating between the single-phase region and the two-phase region, and the last fire must be forged in the two-phase region to ensure that the macrostructure is uniform and the macrostructure is a 30% to 70% spherical or strip-shaped primary α phase uniformly distributed on the aged β matrix. There is no continuous, straight grain boundary α phase network and continuous grain boundary α phase structure in the macrostructure, and there are no β spots, etc.; the surface roughness of the bar after forging and machining should meet the requirement of Ra≤3.2μm after peeling;

[0021] Step 2: Forging the intermediate billet:

[0022] First, the fixed-length bar in step 1 is upset, the upset reduction rate is controlled within the range of (5-15) mm / s, the upset deformation is controlled within 30-50%, and single or double bulging, cracks, folding and other defects are not allowed during the upsetting process; after upsetting, it is longitudinally stretched, the reduction rate in the stretching stage is controlled within the range of (8-15) mm / s, the single downward pressure is controlled within (40-100) mm / time, the cross section is controlled to be a (W+10) mm×(H+10) mm square, a flat tool is used to press steps at (L / 2+5) mm on each end surface in the length direction of the bar, and the cross section of the end surface is controlled to be (W-50) mm×(H+5) mm, and shaping and trimming are completed while stretching. Cracks, folding and other defects are not allowed during the stretching process, the temperature rise is strictly controlled, and the final forging temperature is ensured to be ≥650°C, and air cooling is performed after forging; this step obtains a stepped intermediate billet with a large middle and small ends. Step 3: Machining the intermediate blank:

[0023] Clean the surface of the TB6 titanium alloy intermediate blank prepared in step 2, rough-machine the surface of the intermediate blank, and the surface roughness should meet the requirement of Ra≤3.2μm. Complete the surface coloring inspection and ultrasonic testing of the intermediate blank to ensure that there are no surface and internal defects in the blank.

[0024] Step 4: Die forging:

[0025] Preheat the TB6 titanium alloy intermediate blank machined in step 3 to (100-200)°C, keep it warm for (30-60) minutes, evenly apply TB6 titanium alloy high-temperature antioxidant, and let it dry; heat it in an electric furnace to (T β -25)℃~(T β -65)℃, load the intermediate billet after it reaches the temperature, and the holding time after the furnace reaches the temperature again is calculated as (0.6~1.0)min / mm, and the longest holding time does not exceed 350min; preheat the die to (200~400)℃ before forging, spray the die surface with die lubricant before die forging, and control the billet transfer time within 120s; die forging, air cooling after forging;

[0026] Step 5: Rough machining:

[0027] The forging is divided into two parts at the positioning groove in the middle position along the length direction, and a test block with a size of (L / 2-10)mm×(W / 2-20)mm×Hmm is cut from the middle position of the middle big head end along the width direction, and a through hole for heat treatment process is machined in the middle position of the forging end face along the length direction; because it is divided into two forgings, each forging must be cut into test blocks and tested separately; the test blocks are used to test the microstructure and properties of the forgings.

[0028] Step 6: Heat treatment:

[0029] First, during the solution treatment, the electric furnace is heated, and the forgings are loaded after reaching the temperature. After the furnace temperature returns to the set temperature, it is kept warm for (220±10) minutes (including the overall heat-through time of the forgings). After the forgings are taken out of the furnace, they are cooled to room temperature using circulating water. The furnace transfer time is ≤60s and the water temperature is ≤50°C. Secondly, for the aging treatment, a two-stage electric furnace is used. The electric furnace is heated to 510-550°C, and the forgings are loaded after reaching the temperature. After the furnace temperature returns to the set temperature, it is kept warm for (580±10) minutes (including the overall heat-through time of the forgings). After taking out of the furnace, they are cooled to room temperature in air.

[0030] The bar is subjected to no less than 6 to 8 high-low-high forging cycles in step 1;

[0031] In the step 2, the number of bars per furnace is controlled at 6 to 8.

[0032] The electric furnace of step 2 is heated to (T β -35)℃~(T β -55)℃; the preferred parameters are (T β -40)℃;

[0033] The heat preservation time of the bar in step 2 is calculated as (0.6-0.8) min / mm;

[0034] The upsetting pressing rate in step 2 is controlled at (8-12) mm / s;

[0035] The drawing and pressing rate in step 2 is controlled within the range of (10-12) mm / s;

[0036] The single pressing amount of the step 2 is controlled at (60-80) mm / time.

[0037] In the second step, a plate-type tooling with a diameter of ≥L / 2mm is used to press a step at a distance of (L / 2+5)mm from each end surface of the rod in the longitudinal direction;

[0038] In the step 3, the intermediate blank is milled or lathe is used to remove all the oxide scale on the surface;

[0039] In the step 3, after the intermediate blank is rough-machined, it is divided into two in the middle of the length direction, and the weight of each blank is ensured to be ≥ (M+2) kg; in the step 4, when the intermediate blank is transferred to the mold, the two intermediate blanks are ensured to be placed in the middle of the two cavities of the mold to avoid tilting;

[0040] The electric furnace of step 4 is heated to (T β -35)℃~(T β -55)℃; the preferred parameters are (T β -40)℃;

[0041] In the step 4, the pressing speed during die forging is controlled at 1.0 mm / s to 4.0 mm / s;

[0042] The fourth step of the die forging adopts isothermal forging, the die heating temperature is the same as the billet heating temperature, the isothermal forging deformation rate is controlled at 0.5-4 mm / s, and the holding time is controlled at 3-6 min;

[0043] The die cavity used in the die forging in step 4 is processed according to the drawing of the two-piece shaft sleeve forging with bilateral symmetry.

[0044] During the heat treatment of the forgings in step 6, each forging is placed in a heat treatment frame with a placement interval of ≥40 mm;

[0045] The step six solution treatment is heated in an electric furnace to (T β -35)℃~(T β -55)℃;

[0046] The step six solution treatment is heated in an electric furnace to (T β -40)℃;

[0047] In step six, the electric furnace is heated to 520-540°C for aging treatment.

[0048] In step six, the electric furnace is heated to 530° C. for aging treatment.

[0049] In the aforementioned step 6 heat treatment, if the measured room temperature tensile strength of the forging after heat treatment is higher than the standard requirement, then a new aging treatment is performed. According to the calculation that the room temperature tensile strength decreases by 20 MPa for every 5°C increase in aging temperature, the second aging treatment temperature is increased by (2-10)°C compared to the first aging treatment temperature;

[0050] In the step six heat treatment, if the strength of the forging after heat treatment is lower than the standard requirement, a new solution treatment and aging treatment are performed. According to the calculation that the room temperature tensile strength increases by 10 MPa for every 5°C increase in the solution temperature, the second solution temperature is increased by (5-10)°C compared with the first solution temperature, and the second aging temperature is decreased by (2-10)°C compared with the first aging temperature or remains unchanged.

[0051] The beneficial effects of the present invention are:

[0052] The present invention mainly targets the structural characteristics of TB6 titanium alloy shaft sleeve forgings, designs the two shaft sleeve forgings to be bilaterally symmetrical, adopts flat tooling to forge the square bar into a stepped intermediate blank with a large middle and small ends, and completes the forging of two pieces with one die through die forging. The final shaft sleeve forging has an asymmetrical special-shaped structure with one end being square and the other end being cylindrical, and has high local dimensional accuracy and excellent comprehensive performance at room temperature.

[0053] This invention effectively addresses existing challenges in the production of small and medium-sized titanium alloy die forgings, including complex blank shape design, difficulty positioning the blank during die loading and prone to deflection, difficulty filling local bosses during die forging, low material utilization during single-piece forming, and low production efficiency. The invention enables the production of multiple batches of shaft sleeve forgings, featuring simple steps, convenient operation, low unit cost, and high production efficiency. Furthermore, it offers controllable process parameters, high batch stability, and excellent repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] To more clearly illustrate the technical solutions implemented in the present invention, the following briefly explains the drawings required for use in the examples of the present invention. It is obvious that the drawings described below are only some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0055] Figure 1 Schematic diagram of the forging forming control process of the present invention;

[0056] Figure 2 This is the dimension diagram of the intermediate billet after forging of the present invention;

[0057] Figure 3 This is the dimension diagram of the intermediate blank after machining of the present invention;

[0058] Figure 4 This is a rough processing dimension diagram of the shaft sleeve forging after isothermal forging of the present invention. DETAILED DESCRIPTION

[0059] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0060] The features of various aspects of the embodiments of the present invention will be described in detail below. In the detailed description below, many specific details are provided to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is not limited to any specific configuration and method provided below, but rather encompasses all product structures, methods, and any improvements, replacements, etc., covered without departing from the spirit of the present invention.

[0061] In the various drawings and the following description, well-known structures and techniques are not shown to avoid unnecessarily obscuring the present invention.

[0062] The following is an explanation of the preparation of TB6 titanium alloy shaft sleeve forgings with a length L of 380 mm to 220 mm, a width W of 280 mm to 220 mm, a height H of 280 mm to 180 mm, and a weight M of 120 kg to 30 kg.

[0063] Example 1:

[0064] Step 1: Prepare ingredients:

[0065] The material is prepared according to the size and weight of the final forging. The forging after forming is 300mm long, 250mm wide, 250mm high and weighs 80kg.

[0066] A TB6 titanium alloy bar with a diameter of 260 mm and a weight of 170 kg was prepared. The bar was forged nine times in alternating high-low-high temperatures in the single-phase region and the two-phase region. The last fire was forged at 760°C in the two-phase region. The low-magnification structure was uniform, and the high-magnification structure was a typical aged β matrix with 40% spherical or strip-shaped primary α phase evenly distributed. There was no continuous, flat grain boundary α phase network and coarse continuous grain boundary α phase structure in the high-magnification structure, and there were no β spots. After the bar was forged and then mechanically processed and peeled, the surface roughness Ra was 3.2 μm. The measured phase transformation point of the bar was 793°C.

[0067] Step 2: Forging the intermediate billet:

[0068] Heat the electric furnace to 763°C, and after reaching temperature, load the TB6 titanium alloy rods prepared in step 1. After the furnace reaches temperature again, the holding time is calculated as 0.55 min / mm. First, a 260mm diameter bar is upset with a reduction rate of 6mm / s and a deformation of 40%. Defects such as single or double bulging, cracks, and folds should be avoided during the upset. After upsetting, the bar is longitudinally stretched. The reduction rate during the stretching phase is controlled at 12mm / s, with a single push of 50mm per stroke. The cross-section is controlled to a square of (260±5)mm×(260±5)mm. A flat tooling is used to press steps at a distance of (L / 2+5)mm from each end of the bar in the longitudinal direction. The cross-sections of the two end faces are controlled to (200±5)mm×(255±5)mm. Shaping and trimming are performed during the stretching process. Defects such as cracks and folds should be avoided during the stretching process. The temperature rise is strictly controlled, with a final forging temperature of 660°C. The bar is then air-cooled after forging. This step produces a stepped intermediate billet with a larger center and smaller ends.

[0069] Step 3: Machining the intermediate blank:

[0070] The TB6 titanium alloy intermediate billet prepared in step 2 is milled to remove all surface oxide scales. The cross-section of the intermediate billet at a position (L / 2+10) mm away from the two end faces in the length direction is controlled to be (195±5) mm×(253±3) mm, and the cross-section of the middle section in the length direction of the intermediate billet is controlled to be (255±5) mm×(255±5) mm. The surface roughness should meet the requirement of Ra=3.2μm. After machining, the weight of the billet should be ≥165kg, and the surface coloring inspection and ultrasonic testing of the intermediate billet should be completed to ensure that the billet has no surface and internal defects.

[0071] Step 4: Die forging:

[0072] The TB6 titanium alloy intermediate billet machined in step 3 is preheated to 100°C, kept warm for 40 minutes, and then evenly coated with TB6 titanium alloy high-temperature antioxidant and dried; the electric furnace is heated to 763°C, and the intermediate billet is loaded after reaching the temperature. After the furnace is heated again, the holding time is calculated as 0.8min / mm, and the maximum holding time does not exceed 350min; the mold cavity is processed according to the drawings of the left-right symmetrical design of the two-piece shaft sleeve forgings, the mold is preheated to 300°C before forging, the mold surface is sprayed with mold lubricant before die forging, and the billet transfer time is controlled within 120S; the pressing speed during die forging is controlled at 1.0mm / s, the underpressure is 10mm, the billet final forging temperature is 650°C, and air cooling is performed after forging;

[0073] Step 5: Rough machining:

[0074] Divide the forging into two parts at the positioning groove in the middle of the length direction, and cut a test piece with the size of (L / 2-10) mm × (105±3) mm × (250±3) mm at the middle of the width direction at the middle end of the forging, and make a through hole for heat treatment in the middle of the end face of the forging along the length direction;

[0075] Step 6: Heat treatment:

[0076] First, during the solution treatment, the electric furnace is heated to 763°C. After reaching the temperature, the forgings obtained in step 4 are loaded. The forgings are placed in a heat treatment frame with a spacing of ≥40mm. After the furnace temperature returns to the set temperature, it is kept warm for (220±10) minutes (including the overall heat-through time of the forgings). After the forgings are taken out of the furnace, they are cooled to room temperature using circulating water. The furnace transfer time is ≤60s and the water temperature is ≤50°C. Secondly, for aging treatment, a two-stage electric furnace is used. The electric furnace is heated to 520°C. After reaching the temperature, the forgings are loaded. After the furnace temperature returns to the set temperature, it is kept warm for (580±10) minutes (including the overall heat-through time of the forgings). After taking out of the furnace, they are cooled to room temperature in air.

[0077] Example 2:

[0078] Step 1: Prepare ingredients:

[0079] The material is prepared according to the size and weight of the final forging. The forging after forming is 280mm long, 220mm wide, 200mm high and weighs 50kg.

[0080] TB6 titanium alloy bars with a diameter of 230 mm and a weight of 330 kg were prepared and wire-cut into pieces of 110 kg each. The bars were forged in eight alternating high-low-high fires in the single-phase and two-phase regions. The last fire was forged at 755°C in the two-phase region. The low-magnification structure was uniform, and the high-magnification structure was a typical aged β matrix with 50% spherical or strip-shaped primary α phase evenly distributed. There was no continuous, flat grain boundary α phase network and coarse continuous grain boundary α phase structure in the high-magnification structure, and there were no β spots. After forging, the bar was machined and peeled, and the surface roughness Ra was 3.2 μm. The measured phase transformation point of the bar was 790°C.

[0081] Step 2: Forging the intermediate billet:

[0082] Heat the electric furnace to 760°C, and after reaching temperature, load the TB6 titanium alloy rods prepared in step 1. After the furnace reaches temperature again, the holding time is calculated as 0.65 min / mm. First, a Ø230mm bar is upset with a reduction rate of 8mm / s and deformation of 30%. Defects such as single or double bulging, cracks, and folds should be avoided during the upset. After upsetting, the bar is longitudinally stretched. The reduction rate during the stretching phase is controlled at 10mm / s, with a single stretch of 60mm / stroke. The cross-section is controlled to a square of (230±5)mm×(210±5)mm. A flat tooling is used to press steps at a distance of (L / 2+5)mm from each end of the bar in the longitudinal direction. The cross-sections of the two end faces are controlled to (170±5)mm×(205±5)mm. Shaping and trimming are performed during the stretching process. Defects such as cracks and folds should be avoided during the stretching process. The temperature rise is strictly controlled, with a final forging temperature of 650°C. The bar is then air-cooled after forging. This step produces a stepped intermediate billet with a larger center and smaller ends.

[0083] Step 3: Machining the intermediate blank:

[0084] The TB6 titanium alloy intermediate billet prepared in step 2 is lathe- cleaned to remove all surface oxide scales. The cross-section of the intermediate billet at a distance of (L / 2+10) mm from the two end faces in the length direction is controlled to be (165±5) mm×(203±3) mm. The cross-section of the middle section of the intermediate billet in the length direction is controlled to be (225±5) mm×(205±5) mm. The surface roughness should meet the requirement of Ra=3.2 μm. The intermediate billet is divided into two in the middle of the length direction to ensure that the weight of each billet is ≥55 kg. The surface coloring inspection and ultrasonic testing of the intermediate billet are completed to ensure that the billet has no surface and internal defects.

[0085] Step 4: Die forging:

[0086] Preheat the TB6 titanium alloy intermediate billet machined in step three to 200°C, keep it warm for 50 minutes, evenly apply TB6 titanium alloy high-temperature antioxidant, and let it dry; heat the electric furnace to 760°C, load the intermediate billet after reaching the temperature, and keep the intermediate billet warm for 180 minutes, with the longest keeping time not exceeding 350 minutes; the mold cavity is processed according to the drawings of the two-piece shaft sleeve forgings with left-right symmetry, and the mold is preheated to 400°C before forging, and the mold surface is sprayed with mold lubricant before die forging. When transferring the intermediate billet to the mold, ensure that the two intermediate billets are placed in the middle of the two cavities of the mold to avoid tilting, and the billet transfer time is controlled within 120S; during die forging, the pressing speed is controlled at 3.0mm / s, the underpressure is 8mm, the final forging temperature of the billet is 620°C, and it is air-cooled after forging;

[0087] Step 5: Rough machining:

[0088] A test block with the size of (L / 2-10) mm × (90 ± 3) mm × (200 ± 3) mm is cut from the middle of the big end of the forging along the width direction, and a through hole for heat treatment is made in the middle of the end face of the forging along the length direction;

[0089] Step 6: Heat treatment:

[0090] First, during the solution treatment, the electric furnace is heated to 760°C. After reaching the temperature, the forgings obtained in step 4 are loaded. The forgings are placed in a heat treatment frame with a spacing of ≥40mm. After the furnace temperature returns to the set temperature, it is kept warm for (220±10) minutes (including the overall heat-through time of the forgings). After the forgings are taken out of the furnace, they are cooled to room temperature using circulating water. The furnace transfer time is ≤60s and the water temperature is ≤50°C. Secondly, for aging treatment, a two-stage electric furnace is used. The electric furnace is heated to 530°C. After reaching the temperature, the forgings are loaded. After the furnace temperature returns to the set temperature, it is kept warm for (580±10) minutes (including the overall heat-through time of the forgings). After taking out of the furnace, they are cooled to room temperature in air.

[0091] Example 3:

[0092] Step 1: Prepare ingredients:

[0093] The material is prepared according to the size and weight of the final forging. The forging after forming is 220mm long, 220mm wide, 180mm high and weighs 30kg.

[0094] TB6 titanium alloy bars with a diameter of 230 mm and a weight of 140 kg were prepared and wire-cut into 70 kg pieces each. The bars were forged in six alternating high-low-high fires in the single-phase and two-phase regions. The last fire was forged at 750°C in the two-phase region. The low-magnification structure was uniform, and the high-magnification structure was a typical aged β matrix with 55% spherical or strip-shaped primary α phase evenly distributed. There was no continuous, straight grain boundary α phase network and coarse continuous grain boundary α phase structure in the high-magnification structure, and there were no β spots. After forging, the surface roughness of the bar was Ra = 2.0 μm after mechanical processing and peeling. The measured phase transformation point of the bar was 800°C.

[0095] Step 2: Forging the intermediate billet:

[0096] Heat the electric furnace to 750°C, and after reaching temperature, load the TB6 titanium alloy rods prepared in step 1. After the furnace reaches temperature again, the holding time is calculated as 0.8 min / mm. First, a 230mm diameter bar is upset with a reduction rate of 12mm / s and a deformation of 45%. Defects such as single or double bulging, cracks, and folds should be avoided during the upset. After upsetting, the bar is longitudinally stretched. The reduction rate during the stretching phase is controlled at 15mm / s, with a single pushdown of 80mm / stroke. The cross-section is controlled to a square shape of (230±5)mm×(190±5)mm. A flat tooling is used to press steps at a distance of (L / 2+5)mm from each end of the bar in the longitudinal direction. The cross-sections of the two end faces are controlled to (170±5)mm×(185±5)mm. Shaping and trimming are performed during the stretching process. Defects such as cracks and folds should be avoided during the stretching process. The temperature rise is strictly controlled, with a final forging temperature of 680°C. The bar is then air-cooled after forging. This step produces a stepped intermediate billet with a larger center and smaller ends.

[0097] Step 3: Machining the intermediate blank:

[0098] The TB6 titanium alloy intermediate billet prepared in step 2 is milled to remove all surface oxide scales. The cross-section of the intermediate billet at a position (L / 2+10) mm away from the two end faces in the length direction is controlled to be (165±5) mm×(183±3) mm, and the cross-section of the middle section in the length direction of the intermediate billet is controlled to be (225±5) mm×(185±5) mm. The surface roughness should meet the requirement of Ra=2.0 μm. After machining, the billet weight should be ensured to be ≥65 kg, and the surface coloring inspection and ultrasonic testing of the intermediate billet should be completed to ensure that the billet has no surface and internal defects.

[0099] Step 4: Die forging:

[0100] Preheat the TB6 titanium alloy intermediate billet machined in step three to 150°C, keep it warm for 60 minutes, evenly apply TB6 titanium alloy high-temperature antioxidant, and let it dry; heat the electric furnace to 750°C, load the intermediate billet after it reaches temperature, and wait for the furnace to reach temperature again. The holding time is calculated as 1.0min / mm, and the longest holding time does not exceed 350min; the mold cavity is processed according to the drawings of the two-piece shaft sleeve forgings with left-right symmetry. The mold is made of heat-resistant high-temperature alloy K403. Before forging, the mold is heated to the same temperature as the billet heating temperature, that is, the mold is heated to 760°C. The mold surface is sprayed with mold lubricant before forging. The billet transfer time is controlled within 120S; the isothermal forging deformation rate is controlled at 1-2mm / s, the holding time is controlled at 5min, the underpressure is 5mm, the billet final forging temperature is 630°C, and it is air-cooled after forging;

[0101] Step 5: Rough machining:

[0102] Divide the forging into two parts at the positioning groove in the middle of the length direction, and cut a test piece with the size of (L / 2-10) mm × (90±3) mm × (180±3) mm at the middle of the width direction at the middle end of the forging, and make a through hole for heat treatment in the middle of the end face of the forging along the length direction;

[0103] Step 6: Heat treatment:

[0104] First, during the solution treatment, the electric furnace is heated to 750°C. After reaching the temperature, the forgings obtained in step 4 are loaded. The forgings are placed in a heat treatment frame with a spacing of ≥40mm. After the furnace temperature returns to the set temperature, it is kept warm for (220±10) minutes (including the overall heat-through time of the forgings). After the forgings are taken out of the furnace, they are cooled to room temperature using circulating water. The furnace transfer time is ≤60s and the water temperature is ≤50°C. Secondly, for aging treatment, a two-stage electric furnace is used. The electric furnace is heated to 540°C. After reaching the temperature, the forgings are loaded. After the furnace temperature returns to the set temperature, it is kept warm for (580±10) minutes (including the overall heat-through time of the forgings). After taking out of the furnace, they are cooled to room temperature in air.

[0105] Example 4:

[0106] Step 1: Prepare ingredients:

[0107] The material is prepared according to the size and weight of the final forging. The forging after forming is 250mm long, 230mm wide, 220mm high and weighs 50kg.

[0108] A TB6 titanium alloy bar with a diameter of 240 mm and a weight of 110 kg was prepared. The bar was forged seven times in alternating high-low-high temperatures in the single-phase region and the two-phase region. The last fire was forged at 760°C in the two-phase region. The low-magnification structure was uniform, and the high-magnification structure was a typical aged β matrix with 70% spherical or strip-shaped primary α phase evenly distributed. There was no continuous, flat grain boundary α phase network and coarse continuous grain boundary α phase structure in the high-magnification structure, and there were no β spots. After the bar was forged and then mechanically processed and peeled, the surface roughness Ra = 2.0 μm. The measured phase transformation point of the bar was 790°C.

[0109] Step 2: Forging the intermediate billet:

[0110] Heat the electric furnace to 765°C, and after reaching temperature, load the TB6 titanium alloy rods prepared in step 1. After the furnace reaches temperature again, the holding time is calculated as 1.0 min / mm. First, a 240mm diameter bar is upset with a reduction rate of 15mm / s and a deformation of 50%. Single or double bulges, cracks, or folds are not permitted during the upset. After upsetting, the bar is longitudinally stretched. The reduction rate during the stretching phase is controlled at 8mm / s, with a single push of 100mm per stroke. The cross-section is controlled to a square shape of (240±5)mm x (230±5)mm. A flat tooling is used to press steps at a distance of (L / 2+5)mm from each end of the bar in the longitudinal direction. The cross-sections of the two end faces are controlled to (180±5)mm x (225±5)mm. Shaping and trimming are performed during the stretching process. Defects such as cracks and folds should be avoided during the stretching process. The temperature rise is strictly controlled, with a final forging temperature of 680°C. The bar is then air-cooled after forging. This step produces a stepped intermediate billet with a larger center and smaller ends.

[0111] Step 3: Machining the intermediate blank:

[0112] The TB6 titanium alloy intermediate billet prepared in step 2 is milled to remove all surface oxide scales. The cross-section of the intermediate billet at the position (L / 2+10) mm away from the two end faces in the length direction is controlled to be (175±5) mm×(223±3) mm, and the cross-section of the middle section in the length direction of the intermediate billet is controlled to be (235±5) mm×(225±5) mm. The surface roughness should meet the requirement of Ra=2.0μm. After machining, the weight of the billet should be ensured to be ≥105kg, and the surface coloring inspection and ultrasonic testing of the intermediate billet should be completed to ensure that the billet has no surface and internal defects.

[0113] Step 4: Die forging:

[0114] Preheat the TB6 titanium alloy intermediate billet machined in step three to 200°C, keep it warm for 30 minutes, evenly apply TB6 titanium alloy high-temperature antioxidant, and let it dry; heat the electric furnace to 765°C, load the intermediate billet after it reaches temperature, and wait for the furnace to reach temperature again. The holding time is calculated as 0.6min / mm, and the longest holding time does not exceed 350min; the mold cavity is processed according to the drawings of the left-right symmetrical design of the two-piece shaft sleeve forgings. The mold is made of heat-resistant high-temperature alloy K403. Before forging, the mold is heated to the same temperature as the billet heating temperature, that is, the mold is heated to 765°C. The mold surface is sprayed with mold lubricant before forging. The billet transfer time is controlled within 120S; the isothermal forging deformation rate is controlled at 1.5~3mm / s, the holding time is controlled at 6min, the underpressure is 6mm, the billet final forging temperature is 600°C, and it is air-cooled after forging;

[0115] Step 5: Rough machining:

[0116] The forging is divided into two parts at the positioning groove in the middle position along the length direction, and a test piece with a size of (L / 2-10) mm × (95±3) mm × (220±3) mm is cut from the middle position of the middle big head along the width direction, and a through hole for heat treatment is made in the middle position of the end face of the forging along the length direction;

[0117] Step 6: Heat treatment:

[0118] First, during the solution treatment, the electric furnace was heated to 765°C. After reaching the set temperature, the forgings obtained in step 4 were loaded. The forgings were placed in the heat treatment frame with a spacing of ≥40mm. After the furnace temperature returned to the set temperature, they were kept at this temperature for (220±10) minutes (including the overall heat-through time of the forgings). After the forgings were removed from the furnace, they were cooled to room temperature using circulating water. The transfer time was ≤60s and the water temperature was ≤50°C. Secondly, the aging treatment was carried out in a two-stage electric furnace. The electric furnace was heated to 525°C. After reaching the set temperature, the forgings were loaded. After the furnace temperature returned to the set temperature, they were kept at this temperature for (580±10) minutes (including the overall heat-through time of the forgings). After being removed from the furnace, they were cooled to room temperature in air. The measured room temperature tensile strength of the forgings after heat treatment exceeded the upper limit of the standard requirement of 15MPa. According to the standard requirements, a second aging treatment was performed at 530°C. The measured room temperature tensile strength of the forgings after the re-aging treatment met the standard requirements.

[0119] Example 5:

[0120] Step 1: Prepare ingredients:

[0121] The material is prepared according to the size and weight of the final forging. The forging after forming is 350mm long, 250mm wide, 250mm high and weighs 90kg.

[0122] TB6 titanium alloy bars with a diameter of 260 mm and a weight of 380 kg were prepared and wire-cut into pieces weighing 190 kg each. The bars were forged seven times in alternating high-low-high heats in the single-phase and two-phase regions. The last heat was forged at 740°C in the two-phase region. The low-magnification structure was uniform, and the high-magnification structure was a typical aged β matrix with 60% spherical or strip-shaped primary α phase evenly distributed. There was no continuous, flat grain boundary α phase network and coarse continuous grain boundary α phase structure in the high-magnification structure, and there were no β spots. After forging, the bar was machined and peeled, and the surface roughness Ra was 3.2 μm. The measured phase transformation point of the bar was 805°C.

[0123] Step 2: Forging the intermediate billet:

[0124] Heat the electric furnace to 740°C, and after reaching temperature, load the TB6 titanium alloy rods prepared in step 1. After the furnace reaches temperature again, the holding time is calculated as 1.0 min / mm. First, a 260mm diameter bar is upset with a reduction rate of 10mm / s and a deformation of 35%. Defects such as single or double bulging, cracks, and folds should be avoided during the upset. After upsetting, the bar is longitudinally stretched. The reduction rate during the stretching phase is controlled at 10mm / s, with a single pushdown of 40mm / stroke. The cross-section is controlled to a square of (260±5)mm×(260±5)mm. A flat tooling is used to press steps at a distance of (L / 2+5)mm from each end of the bar in the longitudinal direction. The cross-sections of the two end faces are controlled to (200±5)mm×(255±5)mm. Shaping and trimming are performed during the stretching process. Defects such as cracks and folds should be avoided during the stretching process. The temperature rise is strictly controlled, with a final forging temperature of 660°C. The bar is then air-cooled after forging. This step produces a stepped intermediate billet with a larger center and smaller ends.

[0125] Step 3: Machining the intermediate blank:

[0126] The TB6 titanium alloy intermediate billet prepared in step 2 is lathe- cleaned to remove all surface oxide scales. The cross-section of the intermediate billet at a distance of (L / 2+10) mm from the two end faces in the length direction is controlled to be (195±5) mm×(253±3) mm. The cross-section of the middle section of the intermediate billet in the length direction is controlled to be (255±5) mm×(255±5) mm. The surface roughness should meet the requirement of Ra=3.2 μm. The intermediate billet is divided into two in the middle of the length direction to ensure that the weight of each billet is ≥95 kg. The intermediate billet surface coloring inspection and ultrasonic testing are also completed to ensure that the billet has no surface and internal defects.

[0127] Step 4: Die forging:

[0128] Preheat the TB6 titanium alloy intermediate billet machined in step three to 100°C, keep it warm for 40 minutes, evenly apply TB6 titanium alloy high-temperature antioxidant, and let it dry; heat the electric furnace to 740°C, load the intermediate billet after reaching the temperature, and keep the intermediate billet warm for 180 minutes, with the longest keeping time not exceeding 350 minutes; the mold cavity is processed according to the drawings of the two-piece shaft sleeve forgings with left-right symmetry, and the mold is made of heat-resistant high-temperature alloy K403. Before forging, the mold is heated to the same temperature as the billet heating temperature, that is, the mold is heated to 740°C, and the mold surface is sprayed with mold lubricant before forging. When transferring the intermediate billet to the mold, ensure that the two intermediate billets are placed in the middle of the two cavities of the mold to avoid tilting, and the billet transfer time is controlled within 120S; the isothermal forging deformation rate is controlled at 0.5-2.5mm / s, the holding time is controlled at 3min, the underpressure is 4mm, the final forging temperature of the billet is 600°C, and it is air-cooled after forging;

[0129] Step 5: Rough machining:

[0130] A test block with the size of (L / 2-10) mm × (105 ± 3) mm × (250 ± 3) mm is cut from the middle of the big end of the forging along the width direction, and a through hole for heat treatment is made in the middle of the end face of the forging along the length direction;

[0131] Step 6: Heat treatment:

[0132] First, during the solution treatment, the electric furnace was heated to 740°C. After reaching the set temperature, the forgings obtained in step 4 were loaded. The forgings were placed in the heat treatment frame with a spacing of ≥40mm. After the furnace temperature returned to the set temperature, they were kept at this temperature for (220±10) minutes (including the overall heat-through time of the forgings). After the forgings were removed from the furnace, they were cooled to room temperature using circulating water. The transfer time was ≤60s and the water temperature was ≤50°C. Secondly, the aging treatment was performed in a two-stage electric furnace. The electric furnace was heated to 530°C. After reaching the set temperature, the forgings were loaded. After the furnace temperature returned to the set temperature, they were kept at this temperature for (580±10) minutes (including the overall heat-through time of the forgings). After being removed from the furnace, they were air-cooled to room temperature. The measured room temperature tensile strength of the forgings after heat treatment was lower than the lower limit of the standard requirement of 20MPa. According to the standard requirements, the solution treatment and aging treatment were repeated, with the second solution treatment temperature of 750°C and the second aging temperature of 525°C. The measured room temperature tensile strength of the forgings after the reheat treatment met the standard requirements.

[0133] Example 6:

[0134] Step 1: Prepare ingredients:

[0135] The material is prepared according to the size and weight of the final forging. The forging after forming is 380mm long, 280mm wide, 280mm high and weighs 120kg.

[0136] TB6 titanium alloy bars with a diameter of 290 mm and a weight of 500 kg were prepared, and wire cutting was performed according to 250 kg per bar. The bars were forged in eight alternating high-low-high fires in the single-phase and two-phase regions. The last fire was forged at 755°C in the two-phase region. The low-magnification structure was uniform, and the high-magnification structure was 35% spherical or strip-shaped primary α phase evenly distributed on the aged β matrix. There was no continuous, flat grain boundary α phase network and coarse continuous grain boundary α phase structure in the high-magnification structure, and there were no β spots. After the bar was forged and then machined and peeled, the surface roughness Ra was 3.2 μm. The measured phase transformation point of the bar was 799°C.

[0137] Step 2: Forging the intermediate billet:

[0138] Heat the electric furnace to 755°C, and after reaching temperature, load the TB6 titanium alloy rods prepared in step 1. After the furnace reaches temperature again, the holding time is calculated as 0.7 min / mm. First, a Ø290mm bar is upset with a reduction rate of 7mm / s and a deformation of 40%. Defects such as single or double bulging, cracks, and folds should be avoided during the upset. After upsetting, the bar is longitudinally stretched. The reduction rate during the stretching phase is controlled at 9mm / s, with a single pushdown of 70mm / stroke. The cross-section is controlled to a square of (290±5)mm×(290±5)mm. A flat tooling is used to press steps at a distance of (L / 2+5)mm from each end of the bar in the longitudinal direction. The cross-sections of the two end faces are controlled to (230±5)mm×(285±5)mm. Shaping and trimming are performed during the stretching process. Defects such as cracks and folds should be avoided during the stretching process. The temperature rise is strictly controlled, with a final forging temperature of 670°C. The bar is then air-cooled after forging. This step produces a stepped intermediate billet with a larger center and smaller ends.

[0139] Step 3: Machining the intermediate blank:

[0140] The TB6 titanium alloy intermediate billet prepared in step 2 is milled to remove all surface oxide scales. The cross-section of the intermediate billet at a position (L / 2+10) mm away from the two end faces in the length direction is controlled to be (235±5) mm×(283±3) mm, and the cross-section of the middle section in the length direction of the intermediate billet is controlled to be (285±5) mm×(285±5) mm. The surface roughness should meet the requirement of Ra=3.2μm. After machining, the weight of the billet should be ≥245kg, and the surface coloring inspection and ultrasonic testing of the intermediate billet should be completed to ensure that the billet has no surface and internal defects.

[0141] Step 4: Die forging:

[0142] The TB6 titanium alloy intermediate billet machined in step 3 is preheated to 180°C, kept warm for 45 minutes, and then evenly coated with TB6 titanium alloy high-temperature antioxidant and dried; the electric furnace is heated to 755°C, and the intermediate billet is loaded after reaching the temperature. After the furnace is heated again, the holding time is calculated as 0.9 min / mm, and the maximum holding time does not exceed 350 minutes; the mold cavity is processed according to the drawings of the left-right symmetrical design of the two-piece shaft sleeve forgings, the mold is preheated to 400°C before forging, the mold surface is sprayed with mold lubricant before die forging, and the billet transfer time is controlled within 120 seconds; the pressing speed during die forging is controlled at 2.0 mm / s, the underpressure is 7 mm, the billet final forging temperature is 600°C, and air cooling is performed after forging;

[0143] Step 5: Rough machining:

[0144] The forging is divided into two parts at the positioning groove in the middle position along the length direction, and a test piece with a size of (L / 2-10) mm × (120±3) mm × (280±3) mm is cut from the middle position of the middle big head along the width direction, and a through hole for heat treatment is made in the middle position of the end face of the forging along the length direction;

[0145] Step 6: Heat treatment:

[0146] First, during the solution treatment, the electric furnace is heated to 755°C. After reaching the temperature, the forgings obtained in step 4 are loaded. The forgings are placed in the heat treatment frame with a spacing of ≥40mm. After the furnace temperature returns to the set temperature, it is kept warm for (220±10)min (including the overall heat-through time of the forgings). After the forgings are taken out of the furnace, they are cooled to room temperature using circulating water. The furnace transfer time is ≤60s and the water temperature is ≤50°C. Secondly, for aging treatment, a two-stage electric furnace is used. The electric furnace is heated to 515°C. After reaching the temperature, the forgings are loaded. After the furnace temperature returns to the set temperature, it is kept warm for (580±10)min (including the overall heat-through time of the forgings). After taking out of the furnace, they are cooled to room temperature in air.

[0147] Table 1

[0148]

[0149] Table 1 is a comparison between the method of the present invention and the existing technical path. It can be seen that the use of the one-die two-piece forging method of the present invention to form the shaft sleeve not only greatly reduces the feed weight, significantly improves the dimensional accuracy of the forging, significantly improves the production efficiency, and reduces the production cost, but also better matches the strength, plasticity, and toughness of the forging, has a higher performance level, and improves batch stability.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should all be covered by the scope of protection of the present invention.

Claims

1. A titanium alloy sleeve forging forming control method, characterized in that: The method steps are as follows: Step 1: Prepare ingredients: Prepare a fixed-length or multiple-length TB6 titanium alloy bar with a diameter of (W+10) mm and a weight ≥ (2M+10) kg, and ensure that the bar undergoes high-low-high multi-fire forging in alternating single-phase and two-phase regions; where W is the width of the forging after forming, and M is the weight; Step 2: Forging the intermediate billet: Heat the electric furnace to (T β -25)℃~(T β -65)℃, after reaching the temperature, the TB6 titanium alloy rod is loaded, and the holding time after the furnace reaches the temperature again is calculated as (0.5~1.0)min / mm; Step 3: Machining the intermediate blank: The cross section of the intermediate billet at the position (L / 2+10) mm from the two end faces in the length direction is controlled as (W-55) mm × (H+3) mm, and the cross section of the middle section in the length direction of the intermediate billet is controlled as (W+5) mm × (H+5) mm; after machining, the billet weight should be ≥ (2M+5) kg; L is the length of the forging after forming; Step 4: Die forging: Preheat the TB6 titanium alloy intermediate billet, keep it warm, preheat the die before forging, control the pressing speed during die forging at 0.05mm / s to 6.0mm / s, the underpressure amount ≤10mm, the final forging temperature of the billet ≥600℃, and air cool after forging; Step 5: Rough machining: Divide the forging into two parts along the middle of the length direction and cut out test pieces for testing; Step 6: Heat the electric furnace to (T β -25)℃~(T β -65)℃ for heat treatment.

2. The method according to claim 1, characterized in that The method is to design two shaft sleeve forgings to be bilaterally symmetrical, use a flat tooling to forge a square bar into a stepped intermediate blank with a large middle and small ends, and complete the forging of two pieces in one die by die forging. The specific steps are: Step 1: Prepare ingredients: Prepare fixed-length or multiple-length TB6 titanium alloy bars according to the size and weight of the final forging. Among them, the multiple-length bars need to be wire-cut and divided according to (2M+10) kg per bar to ensure that the bars are forged through high-low-high multiple fires alternating between the single-phase region and the two-phase region, and the last fire must be forged in the two-phase region to ensure that the macrostructure is uniform and the macrostructure is a 30% to 70% spherical or strip-shaped primary α phase uniformly distributed on the aged β matrix. There is no continuous, straight grain boundary α phase network and continuous grain boundary α phase structure in the macrostructure, and there are no β spots, etc.; the surface roughness of the bar after forging and machining should meet the requirement of Ra≤3.2μm after peeling; Step 2: Forging the intermediate billet: First, the bar of fixed length in step 1 is upset, the upset reduction rate is controlled within the range of (5-15) mm / s, and the upset deformation is controlled within the range of 30-50%; after upsetting, the bar is longitudinally stretched, the reduction rate in the stretching stage is controlled within the range of (8-15) mm / s, the single downward pressure is controlled within the range of (40-100) mm / time, the cross section is controlled as a (W+10) mm×(H+10) mm square, a flat tool is used to press a step at (L / 2+5) mm at each end surface in the length direction of the bar, and the cross section of the end surface is controlled as (W-50) mm×(H+5) mm, and shaping and trimming are completed while stretching, and the temperature rise is strictly controlled, while ensuring that the final forging temperature is ≥650°C, and air cooling is performed after forging; Step 3: Machining the intermediate blank: Rough machining of the intermediate blank surface, the surface roughness should meet the requirement of Ra ≤ 3.2μm; Step 4: Die forging: Preheat the TB6 titanium alloy intermediate blank machined in step 3 to (100-200)°C, keep it warm for (30-60) minutes, evenly apply TB6 titanium alloy high-temperature antioxidant, and let it dry; heat it in an electric furnace to (T β -25)℃~(T β -65)℃, load the intermediate billet after it reaches the temperature, and the holding time after the furnace reaches the temperature again is calculated as (0.6~1.0)min / mm, and the longest holding time does not exceed 350min; preheat the die to (200~400)℃ before forging, spray the die surface with die lubricant before die forging, and control the billet transfer time within 120s; die forging, air cooling after forging; Step 5: Rough machining: The forging is divided into two parts at the positioning groove in the middle position along the length direction, and a test piece with a size of (L / 2-10) mm × (W / 2-20) mm × H mm is cut from the middle position of the middle big head along the width direction, and a through hole for heat treatment is made in the middle position of the end face of the forging along the length direction; Step 6: Heat treatment: First, the electric furnace is heated during the solution treatment, and the forgings are loaded after reaching the temperature. After the furnace temperature returns to the set temperature, it is kept warm for (220±10) minutes. After the forgings are taken out of the furnace, they are cooled to room temperature using circulating water. The furnace transfer time is ≤60s and the water temperature is ≤50°C. Secondly, the aging treatment is carried out using a two-stage electric furnace, which is heated to 510-550°C. After reaching the temperature, the forgings are loaded, and after the furnace temperature returns to the set temperature, it is kept warm for (580±10) minutes. After taking them out of the furnace, they are cooled to room temperature in the air.

3. The method according to claim 1, wherein: The high-low-high forging process of the bar in step 1 is performed at least 6 to 8 times.

4. The method according to claim 1, wherein: In step 2, the number of bars per furnace is controlled at 6 to 8.

5. The method according to claim 1, wherein: Step 2: The electric furnace is heated to (T β -35)℃~(T β -55)℃.

6. The method according to claim 1, wherein: The heat preservation time of the bar in step 2 is calculated as (0.6-0.8) min / mm.

7. The method according to claim 2, wherein: The drawing and pressing rate in step 2 is controlled at (10-12) mm / s.

8. The method according to claim 1, wherein: The single pressing amount of the pulling in step 2 is controlled at (60-80) mm / time.

9. The method according to claim 2, wherein: Step 4: The electric furnace is heated to (T β -35)℃~(T β -55)℃.

10. The method according to claim 1, wherein: During the die forging in step 4, the pressing speed is controlled at 1.0 mm / s to 4.0 mm / s.

11. The method according to claim 1, wherein: The solution treatment furnace in step 6 is heated to (T β -35)℃~(T β -55)℃.

12. The method according to claim 1, wherein: In step six, the aging treatment electric furnace is heated to 520-540°C.

13. The method according to claim 2, wherein: In step 6, if the strength of the forging after heat treatment is lower than the standard requirement, the solution and aging treatment shall be repeated. According to the calculation that the room temperature tensile strength increases by 10 MPa for every 5°C increase in the solution temperature, the second solution temperature shall be increased by (5-10)°C compared with the first solution temperature, and the second aging temperature shall be reduced by (2-10)°C compared with the first aging temperature or remain unchanged.

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