A method of forming a titanium alloy forging

Abstract

The present application relates to a kind of forming method of titanium alloy forge piece, by using the bar of small height-diameter ratio, the flatness of C type streamline waist produced after pressing is poor, and it is more advantageous to the chaotic streamline distribution. Then in the two fire times of mandrel expanding, deliberately control the deformation amount of anvil under pressure, and turn over flat end face, deliberately break the streamline distribution. In the pre-rolling process, the end pressure is not given by taper roller, but by small press, and the height is spun to break the streamline distribution, and the special edge corner shape is presented, to ensure the uniformity of organization. The forming method of the present application can effectively solve the problems of uneven organization of thick-walled titanium alloy ring blank and excessive bottom damage of flaw detection, and improve the qualified rate of titanium alloy ultrasonic flaw detection.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy forging technology, and in particular to a method for forming titanium alloy forgings. Background Technology

[0002] Titanium alloys are favored by aerospace, marine engineering and other fields due to their high specific strength, good plasticity and toughness, excellent corrosion resistance and high temperature stability.

[0003] Different billet preparation methods for titanium alloy forgings affect the microstructure of the ring billet and the properties of the forging. Currently, the main method for preparing titanium alloy forgings is free forging followed by pre-rolling. First, the billet is upset to the required height for the ring billet. Then, a punch and die of appropriate size are selected for punching. Whether to perform forward or reverse punching is determined based on the actual situation. After punching, the ring billet undergoes rounding and shaping. Next, the number of reaming passes is selected based on the product's wall thickness and inner hole size. Finally, the required forging dimensions are obtained through final rolling.

[0004] However, the strain and streamlines during the forging process of rings with different wall thicknesses often differ, especially between thick-walled and thin-walled forgings. Thin-walled parts exhibit relatively uniform strain, resulting in a more uniform microstructure and better anisotropy in grain orientation. In contrast, thick-walled parts are difficult to forge through to the core, creating a small strain zone. This leads to material flow concentrating on the surface layer, resulting in strong isotropy in the surface grains. During product flaw detection, this can easily cause sidewall effects, significantly increasing the probability of exceeding bottom loss standards.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention discloses a forming method for titanium alloy forgings, which solves the problem that billet forming methods where the billet height is similar to the final forging height are difficult to forge through the core of thick-walled parts, resulting in excessive bottom damage during the flaw detection stage.

[0007] The technical solution adopted in this invention is as follows: A method for forming a titanium alloy forging, the method comprising the following steps: Cutting: Select bars with a height-to-diameter ratio of 0.7 to 1.1; Upsetting and punching: The billet is heated, the press presses down the bar, the punch is selected according to the product size, and the press presses the punch into the billet to punch holes; Bracket reaming: After the first reaming of the bracket, it is kept warm in the furnace, and then the bracket is reamed again by free forging in the second reaming, and the end face is treated. Pre-rolling: Heating the ring billet, rolling it into a ring using a ring mill, and then flattening the end face; Final rolling: Heating the ring billet and rolling it into a ring using a ring mill.

[0008] The further technical solution is as follows: in the upsetting and punching steps, the heating temperature is 35℃~55℃ below the β phase transformation point of TC4 titanium alloy, the holding time is 280~370min, the final forging temperature is ≥850℃, and the forging is followed by air cooling with a transfer time ≤45s. After pressing, the billet height exceeds the final forging height by 35~45mm, and the forging deformation is 50%~80%.

[0009] In traditional forming methods, after upsetting and pressing large aspect ratio bars, the streamlines along the axial direction of the ring billet have a high degree of verticality. Subsequent steps lack sufficient reduction in height to further decrease this verticality. Microscopically, this manifests as a sidewall interface in the vertical direction. When this interface is parallel to the acoustic waves used in flaw detection, it causes a significant reduction in the bottom echo. Using bars with a smaller aspect ratio results in poor straightness of the waist of the C-shaped streamlines after pressing, which is more favorable for a more chaotic streamline distribution.

[0010] In this application, the forging temperature is relatively low throughout the preforming stage to suppress the formation of continuous β phase at grain boundaries, solve the sidewall scattering problem, and maintain the mechanical properties as required. In traditional forming methods, titanium alloys are usually rolled into rings with equal height or small reduction, so the billet height is generally equivalent to the final forging height. Moreover, current titanium alloy forgings, whether in the free forging reaming or ring rolling reaming stages, require end-face treatment. Free forging reaming is often done by a press, while the ring rolling stage is usually completed by the tapered rolls of a ring rolling mill. The height change in this stage is similar to that of high-temperature alloys, often not exceeding 5mm. From both forming and performance perspectives, the height of the ring billet of conventional products can never exceed the final forging height by 35~45mm. This height is considered to be due to excessive reduction during forging, making it impossible to reasonably distribute the height reduction. Before final rolling, large rounded corners will be generated at the edges of the ring billet, which is not conducive to product shaping. A single final rolling is insufficient to eliminate the large rounded corners, and subsequent processing may result in insufficient allowance. In this application, however, it is possible to ensure that the ring billet has sufficient reduction before final rolling by exceeding the final forging height by 35~45mm, and to obtain the shape of the waist bulge by operating the flat end face of the press.

[0011] The further technical solution is as follows: in the reaming step, the heating temperature of each forging is 35℃~55℃ below the β phase transformation point of TC4 titanium alloy, the holding time is 150~240min, the final forging temperature is ≥850℃, the air cooling is performed after forging, the transfer time is ≤45s, the deformation of the reaming step is 10%~20% per forging, the flat end face reduction is ≥12mm, and the hammer anvil needs to be turned flat, and the length of the hammer anvil is greater than the outer diameter of the ring billet.

[0012] The further technical solution is as follows: In the pre-rolling step, the heating temperature is 35℃~55℃ below the β phase transformation point of TC4 titanium alloy, the holding time is 130~220min, the final forging temperature is ≥800℃, and the forging is followed by air cooling with a transfer time ≤60s; the tapered rolls of the ring mill are not allowed to press down, the ring deformation is 20%~35%, and the ring speed increase is ≤4mm / s. A small hammer anvil press is used for spinning, with the length of the small hammer anvil being less than the outer diameter of the ring billet, until an outward bulge appears at the waist. The radial bulge dimension of the ring billet needs to exceed the minimum radial dimension of the ring billet by 10mm, the flat end face reduction is ≥12mm, and it needs to be flipped flat with a flat end face deformation of 5%~10%.

[0013] To ensure consistent product dimensions, ring forming is ultimately the preferred method. However, ring forming introduces noticeable straight-line flow lines. Therefore, to disrupt the flow lines in each forging step, a press must be used for free forging during pre-rolling to maintain the degree of flow line disorder and ensure the irregular distribution of flow lines after final rolling. During pre-rolling, the tapered rolls do not apply downward pressure; instead, a small press flips and spins the ring blank to flatten the height, ensuring a collapsed corner effect at the ring blank's corners. A height reduction of ≥12mm is used to disrupt the flow line distribution. Conventional flat-end faces, due to their minimal flattening height and the anvil length exceeding the ring blank's outer diameter (i.e., the overall anvil pressure height), do not exhibit outward bulging. During the flattening process, the forging temperature near the ring blank's outer diameter is lower, allowing for the acquisition of more α-phase and resulting in higher mechanical properties in the forging, avoiding abnormal properties caused by inconsistent grain orientation.

[0014] The further technical solution is that, in the final rolling step, the heating temperature is 35℃~55℃ below the β phase transformation point of TC4 titanium alloy, the holding time is 105~195min, the final forging temperature is ≥850℃, the air cooling is performed after forging, and the transfer time is ≤45s; the tapered roll reduction of the ring mill is ≥12mm, and the forging deformation is 20%~35%.

[0015] A further technical solution is that, after the final rolling step, the following step is also included: Solution treatment: The heating temperature is 40°C below the β phase transformation point of TC4 titanium alloy, the holding time is 120~140 min, and then water-cooled to room temperature; Aging: Heating temperature is 690~710℃, heat penetration time is 90~110min, holding time is 120min, and air cooling is performed after forging.

[0016] A further technical solution is that, after the time-sensitive step, the following step is also included: Ultrasonic testing: Each piece shall be subjected to water immersion ultrasonic testing, and the acceptance shall be based on A1 level, with the bottom echo loss not exceeding 50%.

[0017] A further technical solution is that the weight percentage of each chemical element in the forging is as follows: Al: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; other elements: individual ≤0.1%, total ≤0.4%; balance is Ti.

[0018] The beneficial effects of the embodiments of the present invention are as follows: (I) The forming method of titanium alloy forgings in this embodiment of the invention utilizes bars with a small height-to-diameter ratio. The resulting C-shaped streamlines have poor straightness at the waist, which is advantageous for preventing chaotic streamline distribution. Then, during the two-stage reaming process, the deformation under pressure from the hammer anvil is deliberately controlled, and the end face is flipped flat to intentionally disrupt the streamline distribution. In the pre-rolling process, the tapered rolls do not apply end pressure; instead, a small press flips and spins the billet to flatten the height, further disrupting the streamline distribution and creating a unique edge corner shape, ensuring uniformity of the microstructure. The forming method of this invention can effectively solve the problems of uneven microstructure and excessive bottom loss during ultrasonic testing of thick-walled titanium alloy ring billets, improving the pass rate of ultrasonic testing of titanium alloys.

[0019] (ii) Furthermore, after pressing, the height of the billet exceeds the final forging height by 35~45mm, ensuring that the ring billet has sufficient reduction before final rolling. The waist bulge shape is obtained by flattening the end face of the press. From the perspective of microstructure, the two end faces are flat and the forging temperature is lower than the β phase transformation temperature, resulting in more α phase, which is beneficial to improving the mechanical properties of the forging. Attached Figure Description

[0020] Figure 1 This is a flowchart of the forming method for the titanium alloy forging of the present invention.

[0021] Figure 2 This is a schematic diagram of the blanking step in the forming method of titanium alloy forgings according to the present invention.

[0022] Figure 3 This is a schematic diagram of the upsetting and punching steps in the forming method of the titanium alloy forging of the present invention.

[0023] Figure 4 This is a schematic diagram of the frame reaming step in the forming method of the titanium alloy forging of the present invention.

[0024] Figure 5 This is a schematic diagram of the flat end face in the pre-rolling step of the titanium alloy forging forming method of the present invention.

[0025] Figure 6 This is a schematic diagram of the pre-rolling step of the titanium alloy forging forming method of the present invention, showing the flipping and flattening of the end face.

[0026] Figure 7 A comparison diagram of process parameters for producing ring forgings using the conventional forming method and the forming method of the first embodiment.

[0027] Figure 8 Ultrasonic flaw detection waveforms for titanium alloy forgings produced using traditional forming methods.

[0028] Figure 9 The ultrasonic flaw detection waveform of the titanium alloy forging produced by the forming method of the present invention is shown. Detailed Implementation

[0029] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0030] First embodiment: This embodiment discloses a method for forming titanium alloy forgings.

[0031] like Figure 1 As shown, the forming method of titanium alloy forgings includes the following steps: Step S1, material preparation: Select a bar with a height-to-diameter ratio of 1.02.

[0032] like Figure 2 As shown, specifically, TC4 alloy material is selected for the bar stock. The weight percentage of each chemical element in the forging is as follows: Al: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; other elements: individual ≤0.1%, total ≤0.4%; balance is Ti.

[0033] Step S2, upsetting and punching: Heat the billet, press down the bar, select the punch according to the product size, and press the punch into the billet to punch holes.

[0034] like Figure 3 As shown, specifically in the upsetting and punching steps, the heating temperature is 45°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 325 min, the final forging temperature is ≥850°C, and after forging, it is air-cooled with a transfer time ≤45 s. After pressing, the billet height exceeds the final forging height by 35~45 mm, and the forging deformation is 58%.

[0035] Step S3, reaming the shank: After the first reaming of the shank, it is kept warm in the furnace, and then the shank is reamed by free forging in the second reaming, and the end face is treated.

[0036] like Figure 4As shown, specifically, in the forging process, the heating temperature for each pass is 45°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 195 min, the final forging temperature is ≥850°C, air cooling is performed after forging, and the transfer time is ≤45 s. The deformation amount of the forging process in the first pass is 17%, and the deformation amount in the second pass is 16%. The flat end face reduction is ≥12 mm, and the hammer anvil needs to be turned flat, with the length of the hammer anvil greater than the outer diameter of the ring billet.

[0037] Step S4, pre-rolling: heat the ring billet, roll it into a ring using a ring mill, and then flatten the end face.

[0038] like Figure 5 and Figure 6 As shown, specifically, in the pre-rolling step, the heating temperature is 45℃ below the β-phase transformation point of TC4 titanium alloy, the holding time is 175min, the final forging temperature is ≥800℃, and after forging, air cooling is performed with a transfer time ≤60s. The tapered rolls of the ring mill are not allowed to press down, and the ring deformation is 23%. A small hammer anvil press is used for spinning, with the length of the small hammer anvil being less than the outer diameter of the ring billet, until an outward bulge appears at the waist. The radial bulge dimension of the ring billet needs to exceed the minimum radial dimension of the ring billet by 10mm. The flat end face reduction is ≥12mm, and the ring needs to be flipped flat, with a flat end face deformation of 6.7%.

[0039] Step S5, final rolling: heat the ring billet and roll it into a ring using a ring mill.

[0040] Specifically, in the final rolling step, the heating temperature is 45°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 150 min, the final forging temperature is ≥850°C, and the forging is followed by air cooling with a transfer time ≤45 s. The tapered roll reduction of the ring mill is ≥12 mm, and the forging deformation is 24%.

[0041] Step S6, solution treatment: The heating temperature is 40°C below the β phase transformation point of TC4 titanium alloy, the holding time is 120 min, and then water-cooled to room temperature.

[0042] Step S7, aging: heating temperature is 700℃, heat penetration time is 90min, holding time is 120min, and air cooling is performed after forging.

[0043] Step S8, Ultrasonic testing: Perform water immersion ultrasonic testing on each piece, and accept it according to A1 level, with the bottom echo loss not exceeding 50%.

[0044] Second embodiment: This embodiment discloses a method for forming titanium alloy forgings.

[0045] like Figure 1 As shown, the forming method of titanium alloy forgings includes the following steps: Step S1, material preparation: Select a bar with a height-to-diameter ratio of 0.71.

[0046] like Figure 2As shown, specifically, TC4 alloy material is selected for the bar stock. The weight percentage of each chemical element in the forging is as follows: Al: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; other elements: individual ≤0.1%, total ≤0.4%; balance is Ti.

[0047] Step S2, upsetting and punching: Heat the billet, press down the bar, select the punch according to the product size, and press the punch into the billet to punch holes.

[0048] like Figure 3 As shown, specifically, in the upsetting and punching steps, the heating temperature is 35°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 280 min, the final forging temperature is ≥850°C, and after forging, it is air-cooled with a transfer time ≤45 s. After pressing, the billet height exceeds the final forging height by 35~45 mm, and the forging deformation is 50%.

[0049] Step S3, reaming the shank: After the first reaming of the shank, it is kept warm in the furnace, and then the shank is reamed by free forging in the second reaming, and the end face is treated.

[0050] like Figure 4 As shown, specifically, in the forging process of the reaming block, the heating temperature for each forging is 35°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 150 min, the final forging temperature is ≥850°C, air cooling is performed after forging, the transfer time is ≤45 s, and the deformation of the reaming block is 10% per forging. The flat end face reduction is ≥12 mm, and the hammer anvil needs to be turned flat, with the length of the hammer anvil greater than the outer diameter of the ring billet.

[0051] Step S4, pre-rolling: heat the ring billet, roll it into a ring using a ring mill, and then flatten the end face.

[0052] like Figure 5 and Figure 6 As shown, specifically, in the pre-rolling step, the heating temperature is 35℃ below the β-phase transformation point of TC4 titanium alloy, the holding time is 130min, the final forging temperature is ≥800℃, and after forging, air cooling is performed with a transfer time ≤60s. The tapered rolls of the ring mill are not allowed to be pressed down, and the ring deformation is 20%. A small hammer anvil press is used for spinning, with the length of the small hammer anvil being less than the outer diameter of the ring billet, until an outward bulge appears at the waist. The radial bulge dimension of the ring billet needs to exceed the minimum radial dimension of the ring billet by 10mm, the flat end face reduction is ≥12mm, and it needs to be flipped flat, with a flat end face deformation of 5%.

[0053] Step S5, final rolling: heat the ring billet and roll it into a ring using a ring mill.

[0054] Specifically, in the final rolling step, the heating temperature is 35°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 105 min, the final forging temperature is ≥850°C, and the forging is followed by air cooling with a transfer time ≤45 s. The tapered roll reduction of the ring mill is ≥12 mm, and the forging deformation is 20%.

[0055] Step S6, solution treatment: The heating temperature is 40°C below the β phase transformation point of TC4 titanium alloy, the holding time is 130 min, and then water-cooled to room temperature.

[0056] Step S7, aging: heating temperature is 690℃, heat penetration time is 110min, holding time is 120min, and air cooling is performed after forging.

[0057] Step S8, Ultrasonic testing: Perform water immersion ultrasonic testing on each piece, and accept it according to A1 level, with the bottom echo loss not exceeding 50%.

[0058] Third embodiment: This embodiment discloses a method for forming titanium alloy forgings.

[0059] like Figure 1 As shown, the forming method of titanium alloy forgings includes the following steps: Step S1, material preparation: Select a bar with a height-to-diameter ratio of 1.1.

[0060] like Figure 2 As shown, specifically, TC4 alloy material is selected for the bar stock. The weight percentage of each chemical element in the forging is as follows: Al: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; other elements: individual ≤0.1%, total ≤0.4%; balance is Ti.

[0061] Step S2, upsetting and punching: Heat the billet, press down the bar, select the punch according to the product size, and press the punch into the billet to punch holes.

[0062] like Figure 3 As shown, specifically, in the upsetting and punching steps, the heating temperature is 55°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 370 min, the final forging temperature is ≥850°C, and after forging, it is air-cooled with a transfer time ≤45 s. After pressing, the billet height exceeds the final forging height by 35~45 mm, and the forging deformation is 80%.

[0063] Step S3, reaming the shank: After the first reaming of the shank, it is kept warm in the furnace, and then the shank is reamed by free forging in the second reaming, and the end face is treated.

[0064] like Figure 4As shown, specifically, in the forging process of the reaming block, the heating temperature for each forging is 55°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 240 min, the final forging temperature is ≥850°C, air cooling is performed after forging, the transfer time is ≤45 s, and the deformation of the reaming block per forging is 20%. The flat end face reduction is ≥12 mm, and the hammer anvil needs to be turned flat, with the length of the hammer anvil greater than the outer diameter of the ring billet.

[0065] Step S4, pre-rolling: heat the ring billet, roll it into a ring using a ring mill, and then flatten the end face.

[0066] like Figure 5 and Figure 6 As shown, specifically, in the pre-rolling step, the heating temperature is 55℃ below the β-phase transformation point of TC4 titanium alloy, the holding time is 220min, the final forging temperature is ≥800℃, and after forging, air cooling is performed with a transfer time ≤60s. The tapered rolls of the ring mill are not allowed to press down, and the ring deformation is 35%. A small hammer anvil press is used for spinning, with the length of the small hammer anvil being less than the outer diameter of the ring billet, until an outward bulge appears at the waist. The radial bulge dimension of the ring billet needs to exceed the minimum radial dimension of the ring billet by 10mm. The flat end face reduction is ≥12mm, and the ring needs to be flipped flat, with a flat end face deformation of 10%.

[0067] Step S5, final rolling: heat the ring billet and roll it into a ring using a ring mill.

[0068] Specifically, in the final rolling step, the heating temperature is 55°C below the β-phase transformation point of TC4 titanium alloy, the holding time is 195 min, the final forging temperature is ≥850°C, and the forging is followed by air cooling with a transfer time ≤45 s. The tapered roll reduction of the ring mill is ≥12 mm, and the forging deformation is 35%.

[0069] Step S6, solution treatment: The heating temperature is 40°C below the β phase transformation point of TC4 titanium alloy, the holding time is 140 min, and then water-cooled to room temperature.

[0070] Step S7, aging: heating temperature is 710℃, heat penetration time is 100min, holding time is 120min, and air cooling is performed after forging.

[0071] Step S8, Ultrasonic testing: Perform water immersion ultrasonic testing on each piece, and accept it according to A1 level, with the bottom echo loss not exceeding 50%.

[0072] Experimental example: Ring forgings were produced using both the conventional forming method and the forming method of the first embodiment, with the process parameters compared as follows: Figure 7 As shown, the diameter and height are in mm.

[0073] Process inspection results as follows Figure 8 and Figure 9 As shown. Figure 8 and Figure 9This is a C-scan image used in water immersion testing to assess bottom echo loss and determine tissue homogeneity. The horizontal axis represents 0~360°, i.e., one circumference of the ultrasonic probe along the ring, and the vertical axis represents the wall thickness direction of the ring. The shades of color on the right side of the image indicate the level of bottom echo loss; areas above green meet standard requirements, while blue areas below green indicate excessive bottom echo loss and severe tissue inhomogeneity.

[0074] Figure 8 A blue ring appears around 25mm along the wall thickness direction, indicating tissue abnormalities and significant bottom echo loss, demonstrating the adverse effects of the sidewall effect. Figure 9 The overall color is uniform, meaning the texture is uniform, which meets the standard requirements.

[0075] Meanwhile, performance tests were conducted on ring forgings produced using both the conventional forming method and the forming method of the first embodiment. The ring forgings produced using the forming method of the first embodiment showed a 20% increase in primary α phase, a 15-30 MPa increase in tensile strength, a 2-4% increase in elongation, and a 10-20 MPa increase in fracture toughness. .

[0076] Among them, primary α phase: tested according to GB / T 5168, using a stereomicroscope. Tensile strength: GB / T 228.1 and GB / T 228.2, using a fully automated extensometer. Elongation: tested according to GB / T 228.1 and GB / T 228.2, using a fully automated extensometer. Fracture toughness: tested according to GB 229, using an impact testing machine.

[0077] In the embodiments of this invention, by using bars with a small height-to-diameter ratio, the resulting C-shaped streamlines after pressing have poor straightness at the waist, which is beneficial for the chaotic distribution of streamlines. Then, during the two-stage reaming process, the deformation amount under pressure from the hammer anvil is deliberately controlled, and the end face is flipped flat to intentionally disrupt the streamline distribution. In the pre-rolling process, the tapered rolls do not apply end pressure; instead, a small press flips and spins the rolls to flatten the height, further disrupting the streamline distribution and creating a unique edge corner shape, ensuring the uniformity of the microstructure. The forming method of this invention can effectively solve the problems of uneven microstructure and excessive bottom loss during ultrasonic testing of thick-walled titanium alloy ring billets, improving the pass rate of ultrasonic testing of titanium alloys.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for forming titanium alloy forgings, characterized in that, The forming method of the titanium alloy forging includes the following steps: Blanking: Select bars with a height-to-diameter ratio of 0.7 to 1.1 as billets; Upsetting and punching: The billet is heated, and a press is used to press it down. A punch is selected based on the product dimensions, and the press presses the punch into the billet to punch holes. In the upsetting and punching process, the heating temperature is 35℃~55℃ below the β-phase transformation point of TC4 titanium alloy, the holding time is 280~370min, the final forging temperature is ≥850℃, and air cooling is performed after forging with a transfer time ≤45s. After pressing, the billet height exceeds the final forging height by 35~45mm, and the forging deformation is 50%~80%. Forging with a forging frame: After the first forging with a forging frame, the forging frame is returned to the furnace for heat preservation, and then the forging frame is forged again for free forging with a forging frame, and the end face is treated. In the forging frame forging step, the heating temperature of each forging frame is 35℃~55℃ below the β phase transformation point of TC4 titanium alloy, the heat preservation time is 150~240min, the final forging temperature is ≥850℃, the forging frame is air-cooled, the transfer time is ≤45s, the deformation of each forging frame forging frame is 10%~20%, the end face reduction is ≥12mm, and the hammer anvil needs to be turned flat, and the length of the hammer anvil is greater than the outer diameter of the ring billet. Pre-rolling: Heat the ring billet, roll it into a ring using a ring mill, and then flatten the end face; in the pre-rolling step, the heating temperature is 35℃~55℃ below the β phase transformation point of TC4 titanium alloy, the holding time is 130~220min, the final forging temperature is ≥800℃, and the ring is air-cooled after forging with a transfer time ≤60s; the tapered rolls of the ring mill are not allowed to press down, and the ring deformation is 20%~35%; spin forming is performed using a small hammer anvil press, the length of the small hammer anvil is less than the outer diameter of the ring billet, until an outward bulge appears at the waist, the radial bulge dimension of the ring billet needs to exceed the minimum radial dimension of the ring billet by 10mm, the flattening amount of the end face is ≥12mm, and it needs to be flipped flat, with a flattening amount of 5%~10%; Final rolling: Heating the ring billet and rolling it into a ring using a ring mill.

2. The forming method for titanium alloy forgings according to claim 1, characterized in that: In the final rolling step, the heating temperature is 35℃~55℃ below the β phase transformation point of TC4 titanium alloy, the holding time is 105~195min, the final forging temperature is ≥850℃, the forging is air-cooled, and the transfer time is ≤45s; the tapered roll reduction of the ring mill is ≥12mm, and the forging deformation is 20%~35%.

3. The forming method for titanium alloy forgings according to claim 1, characterized in that: Following the final rolling step, the following step is also included: Solution treatment: The heating temperature is 40°C below the β phase transformation point of TC4 titanium alloy, the holding time is 120~140 min, and then water-cooled to room temperature; Aging: Heating temperature is 690~710℃, heat penetration time is 90~110min, holding time is 120min, and air cooling is performed after forging.

4. The forming method of titanium alloy forgings according to claim 3, characterized in that: Following the timeliness step, the following step is also included: Ultrasonic testing: Each piece shall be subjected to water immersion ultrasonic testing, and the acceptance shall be based on A1 level, with the bottom echo loss not exceeding 50%.

5. The forming method for titanium alloy forgings according to claim 1, characterized in that, The weight percentages of each chemical element in the forging are as follows: Al: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C：≤0.08%； N ：≤0.05%； H: ≤0.015%; O: ≤0.2%; other elements: individual ≤0.1%, total ≤0.4%; balance is Ti.

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