A forging method for high-uniform β-state titanium alloy step forgings

Abstract

The present invention discloses a forging method for highly uniform β-titanium alloy step forgings, comprising blanking forging, first static recrystallization homogenization forging, second static recrystallization homogenization forging, step forging two-phase region drawing blank forging, and finished product forging. The method produces forgings with a uniform lamellar structure, high fracture toughness, and improved service life for shaft forgings.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy material processing, in particular to a forging method for a high-uniform beta-state titanium alloy stage forging. Background Art

[0002] Titanium alloys can achieve different microstructures depending on their processing techniques. For example, forging and heat treating below the phase transition point yields an equiaxed structure, which exhibits excellent room temperature properties but poor high-temperature durability and creep resistance. Forging and heat treating in the upper half of the phase transition point yields a duplex structure, which exhibits excellent room temperature properties but a rapid crack growth rate. Deforming near the phase transition point, or heating in the β phase and then forging in the duplex phase, yields a basketweave structure, which exhibits poor plasticity. Forging in the upper half of the β phase or quasi-β heat treatment yields a lamellar structure, which exhibits high fracture toughness and a low fatigue crack growth rate. To meet the requirements for high uniformity, large size, and long-life surfaces for load-bearing components in new-generation aircraft, current aircraft materials primarily utilize high damage tolerance technology. The lamellar structure of titanium alloy can meet the damage tolerance design requirements of the new generation of aircraft, but the uniformity of the lamellar structure plays a vital role in the performance and service life of the final forging. If there is partial structural unevenness in the forging, cracks may initiate there, greatly reducing the service life of the forging.

[0003] Most titanium alloy step forgings in the prior art have equiaxed structures and cannot meet current usage requirements. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a forging method for highly uniform β-state titanium alloy step forgings.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A forging method for a high-uniform β-state titanium alloy step forging, characterized by comprising the following steps:

[0007] Step 1: Forging

[0008] The titanium alloy ingot is heated to 1050-1150°C, and the billet is subjected to one-time upsetting forging using a fast forging machine to obtain an intermediate forging billet with an octagonal or quadrilateral cross section, which is then air-cooled after forging;

[0009] Step 2: First static recrystallization homogenization forging

[0010] The blank obtained in step 1 is heated to 50-80° C. below the β phase transformation point temperature, and a reversing upsetting and drawing forging is performed on the blank using a fast forging machine, wherein the drawing process is a drawing method of directional homogenization deformation; when the blank temperature is lower than 650° C. during the forging process, the blank is returned to the furnace for reheating at 50-80° C. below the β phase transformation point temperature, and the holding time is 30-60 min; after forging, the blank is returned to the furnace for recrystallization and homogenization, and the returning temperature is 80-120° C. above the β phase transformation point temperature, and after heating, upsetting and drawing forging is performed, and air cooling is performed after forging, and the cross-section of the blank after homogenization is octagonal or quadrilateral;

[0011] Step 3: Second static recrystallization homogenization forging

[0012] The blank obtained in step 2 is heated to 30-50° C. below the β phase transformation point temperature, and a fast forging machine is used to perform a reversing upsetting and drawing forging on the blank, and a directional homogenization deformation drawing method is performed during the drawing process; when the blank temperature is lower than 650° C. during the forging process, the blank is returned to the furnace for heating at 30-50° C. below the β phase transformation point temperature, and the holding time is 30-60 min; after forging, the blank is returned to the furnace for recrystallization and homogenization, and the return temperature is 50-80° C. above the β phase transformation point temperature. After heating, step drawing is performed, and air cooling is performed after forging. After homogenization, each step cross-section of the drawn forging blank is an octagon;

[0013] Step 4: Step forging two-phase zone drawing and billet forging

[0014] The intermediate billet obtained in step 3 is heated to 30-80°C below the β phase transformation point temperature, with a heating coefficient of 0.55-0.80 min / mm, and subjected to multi-fire drawing forging in the two-phase region, with a single-fire deformation of 20-40%, to obtain an intermediate billet for step forgings, which is air-cooled after forging, and the last fire drawing is performed by rolling drawing;

[0015] Step 5: Finished Forging

[0016] The intermediate billet obtained in step 4 is heated to 20-50°C above the β phase transformation point temperature. This heating is performed in a step-by-step heating manner. After heating is completed, the billet is forged into a finished product using a precision forging machine. The precision forging machine is forged for multiple passes to form a stepped forging product. The final forging temperature is 120°C higher than the β phase transformation point temperature.

[0017] Furthermore, in the above step 1, the heating coefficient of the blank forging is 0.50-0.80 min / mm, and the deformation amount of each upsetting and drawing is 30-50%.

[0018] Furthermore, the specific process of the above step 2 is as follows:

[0019] Carry out in two batches,

[0020] The first fire is 2 upsetting and 2 drawing, with a heating coefficient of 0.55-0.80min / mm, a single upsetting deformation of 20-45%, and radial drawing after the two upsettings, so that the metal on the end surface of the material is distributed around the billet. At the same time, the drawing process first draws along the large surface of the billet, then rotates the billet 45° to deform on the edge surface of the billet, and then rotates 45° to deform on the large surface. The above forging method is repeated until the target size is reached. The use of the above-mentioned directional uniform deformation drawing method can eliminate the deformation dead zone in the drawing process and achieve the effect of uniform drawing. The cross-section of the billet after forging is octagonal or quadrilateral, and it is returned to the furnace after forging.

[0021] The second fire is 1 upsetting and 1 drawing, the heating coefficient is 0.30-0.55min / mm, the single upsetting deformation is 20-45%, and the billet is air-cooled after forging. The cross-section of the billet is still octagonal or quadrilateral. At this time, the metal on the end face of the material is distributed around the billet.

[0022] Furthermore, the specific process of step 3 is as follows:

[0023] Carry out in two batches,

[0024] The first fire is 2 upsetting and 2 drawing, with a heating coefficient of 0.55-0.80min / mm, a single upsetting deformation of 20-45%, and the two upsettings respectively adopt the deformation methods of straight upsetting and straight drawing and side upsetting and axial drawing. After the second upsetting, the drawing is done along the radial direction of the ingot to transform the original end metal of the material to the original end. The drawing process also adopts the drawing method of directional homogenization deformation. The cross section after forging is octagonal or quadrilateral, and the forging is returned to the furnace.

[0025] The second fire is for drawing forging, with a heating coefficient of 0.30-0.55 min / mm, and step forging is performed to forge to two or more steps, with a drawing deformation of 10-50%, and air cooling after forging.

[0026] The specific process of step 4 above is:

[0027] The two-phase zone is drawn and forged with 1-5 fires. The drawing method adopts drawing forging, and the deformation of a single fire is 20-40%. When making the billet, the large and small steps are interchanged. The original large step adopts a large deformation and is forged to the small step of the finished step forging with a drawing deformation of 35-85%. The small step adopts a small deformation and is forged to the large step of the finished step forging with a drawing deformation of 10-65%. Air cooling is performed after forging.

[0028] The specific process of step 5 above is:

[0029] The heating is carried out in a step-by-step heating manner, that is, the temperature is kept at 100-150°C below the β phase transformation point temperature, the holding time after reaching the temperature is the holding coefficient of 0.55-0.85min / mm, and the temperature is raised to 70-100°C below the β phase transformation point temperature after completion of the heating, the holding time after reaching the temperature is the holding coefficient of 0.35-0.55min / mm, and the temperature is raised to 40-70°C below the β phase transformation point temperature after completion of the heating, the holding time after reaching the temperature is the holding coefficient of 0.20-0.35min / mm, and the temperature is raised to 10-40°C below the β phase transformation point temperature after completion of the heating, the holding time after reaching the temperature is the holding coefficient of 0.10-0.20min / mm, and the temperature is heated to 20-50°C above the β phase transformation point temperature after completion of the heating, the holding time after reaching the temperature is the holding coefficient of 0.30-0.55 min / mm, after heating is completed, the billet is forged into finished product by a precision forging machine, the frequency of large-step forging of forgings is 150-600 times / min, the total forging deformation is 40-80%, the total number of passes is 3-5 times, of which the deformation of a single pass is 5-30%, and the deformation of the last pass is ≤10%; the frequency of small-step forging of forgings is 50-450 times / min, the total forging deformation is 10-60%, the total number of passes is 2-4 passes, of which the deformation of a single pass is 5-20%, and the deformation of the last pass is ≤5%, the forging method is reciprocating forging, the billet pulling rate is ≤8m / min, and the final forging temperature is ≥120℃ below the β phase transformation point temperature.

[0030] Conventional step forging methods forge large steps from an initial large step to a final large step, and then from an initial small step to a final small step. This forging method results in significantly greater cumulative deformation for the small steps than for the large steps, leading to significant differences in microstructure and performance between the small and large steps. Furthermore, forgings with large cumulative deformation for the small steps may exhibit fine-grained bright bands at low magnification, while forgings with small deformation for the large steps may exhibit uneven microstructure at low magnification. The present invention, however, employs a forging method that interchanges large and small steps during production, using large deformation for the large steps and small deformation for the small steps. This achieves uniform microstructure and performance, while also resolving low-magnification anomalies in forgings caused by deformation mismatch. Furthermore, the present invention employs two static recrystallization forgings to achieve grain refinement. Specifically, reversing forging is performed below the first phase transition point, converting the end metal to the surface. At the second phase transition point, the original end metal is returned to its original position. A uniform deformation stretching method is employed during elongation. Combining these two uniform deformation methods allows the original billet to achieve uniform deformation, resulting in more uniform recrystallized grains. In addition, the present invention starts heating at an initial heating temperature of 100-150°C below the β phase transformation point temperature during the final β forging, and adopts a 5-step heating method during the heating process, which can greatly reduce the residence time of the billet in the β phase region, avoid the organizational difference caused by the temperature difference between the inside and outside of the billet during heating in the single-phase region, and the temperature field of the billet of the present invention will be heated more uniformly; the finished product is forged using a precision forging machine, and the total deformation, single-pass deformation, forging frequency, and final forging temperature of each step forging are designed according to the step morphology and organizational evolution law, to ensure that the deformation state of the forging process remains consistent during the forging process of each step, and obtain a uniform lamellar structure.

[0031] The beneficial effects of the present invention are as follows:

[0032] By adopting the method of the present invention, the forgings produced are of uniform lamellar structure, the forgings can obtain higher fracture toughness, and the service life of the shaft forgings can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The microstructures at various positions of the Ti-1300 alloy step forging according to the first embodiment of the present invention are shown in FIG. 1 , where a represents a large step microstructure and b represents a small step microstructure.

[0034] Figure 2 The microstructures at various positions of the Ti-1050 alloy step forging according to the second embodiment of the present invention are shown in FIG. 1 , where a represents a large-step microstructure and b represents a small-step microstructure. DETAILED DESCRIPTION

[0035] The present invention will be further described with reference to the accompanying drawings and specific embodiments. The following are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any identical or similar solutions that do not depart from the initial concept of the present invention should fall within the scope of protection of the present invention. Hereinafter, "◇" represents the height of a blank with an octagonal cross section, and "Φ" represents the diameter of a blank with a circular cross section.

[0036] Example 1 (Preparation of Ti-1300 Alloy Step Forgings)

[0037] The raw material in this example is Ti-1300 Φ680mm alloy ingot, the ingot β phase transition temperature is 820℃, and the specific forging process is as follows:

[0038] ① Open forging: heat the ingot to 1150℃ with a holding coefficient of 0.65min / mm. After the holding period, the ingot is forged on a high-speed forging machine with two upsetting and two drawing processes. The first drawing process is diagonal drawing, and the second drawing process is used to forge the billet into a ◇550mm square billet. Air cooling is performed after forging.

[0039] ② The first static recrystallization homogenization forging, the blank material is heated to 760 ℃, the heating coefficient is 0.7min / mm, and after the end of the heat preservation, 2 upsetting and 2 drawing forging is carried out on the fast forging machine. This process adopts reversing upsetting and drawing, and the metal of the material end face is distributed around the blank. The two upsettings adopt the deformation methods of straight upsetting and straight drawing, and side upsetting and axial drawing respectively. After the second upsetting, the drawing is extended along the radial direction of the ingot, and the original end metal of the material is changed to the original end. When drawing, the large surface of the blank is deformed first, and then rotated 45° on the edge of the blank. Deform, then rotate 45° to deform on the large surface, and repeat the above forging process (when drawing, first deform the large surface of the billet, then rotate 45° to deform on the edge of the billet, and then rotate 45° to deform on the large surface), rotate 24 times in total, forging to ◇550mm square billet, immediately return to 910℃ heating furnace after forging, insulation coefficient 0.50min / mm, after insulation is completed, carry out 1 upsetting and 1 drawing, forging to ◇550mm square billet, drawing along the radial direction, the metal of the material end face is still distributed around the billet, and air cooling after forging;

[0040] ③ The second static recrystallization homogenization forging, the material is heated to 780 ℃, the heating coefficient is 0.7min / mm, and after the end of the heat preservation, it is forged on the fast forging machine with 2 upsetting and 2 drawing. This process adopts reversing upsetting and drawing. The two upsettings adopt the deformation mode of straight upsetting and straight drawing and side upsetting and axial drawing respectively. After the second upsetting, the drawing is done along the radial direction of the ingot, and the original end metal of the material is transformed to the original end. When drawing, the large surface of the billet is deformed first, and then the billet edge is deformed by rotating 45°. Then rotate 45° to deform the large surface, and repeat the above forging process (when stretching, first deform the large surface of the billet, then rotate 45° to deform on the edge of the billet, and then rotate 45° to deform on the large surface), rotate 24 times in total, and forge to a square billet of ◇550mm. After forging is completed, immediately return to the 880℃ heating furnace with a thermal insulation coefficient of 0.55min / mm. After the thermal insulation is completed, step forging is carried out, with the first step forging to ◇500mm and the second step forging to ◇440mm;

[0041] ④ Two-phase zone billet forging, heating the material to 780℃, with a holding coefficient of 0.7min / mm. After the holding is completed, the step forging is carried out on a fast forging machine. The first step is forged to Φ250mm, and the second step is forged to Φ380mm. Air cooling is performed after forging;

[0042] ⑤ Forging of finished products, heat the material to 720℃, with a thermal insulation coefficient of 0.60min / mm. After the insulation is completed, heat it to 750℃, with a thermal insulation coefficient of 0.45min / mm. After the insulation is completed, heat it to 780℃, with a thermal insulation coefficient of 0.30min / mm. After the insulation is completed, heat it to 810℃, with a thermal insulation coefficient of 0.20min / mm. After the insulation is completed, heat the finished product to a thermal insulation temperature of 850℃, with a thermal insulation coefficient of 0.40min / mm. After the insulation is completed, forge the finished product on a precision forging machine. The first-level small step is forged to Φ200mm, with a forging frequency of 100 times / min, and the forging is completed in 2 passes. The second-level large step is forged to Φ260mm, with a forging frequency of 180 times / min, and the forging is completed in 4 passes. The pulling rate during forging is 5mm / min, and air cooling is performed after forging.

[0043] The microstructure of each position of the step forging prepared in this embodiment is as follows Figure 1 As shown, the large and small step structures of the forgings are uniform lamellar structures. The comparison of fracture toughness under different organizational states is shown in Table 1:

[0044] .

[0045] Example 2 (Preparation of Ti-1050 Alloy Step Forgings)

[0046] The raw material in this example is Ti-1050 Φ780mm alloy ingot, the ingot β phase transition temperature is 950℃, and the specific forging process is as follows:

[0047] ① Open forging: heat the ingot to 1150℃ with a holding coefficient of 0.7min / mm. After the holding period, perform 2 upsetting and 3 drawing forging on a fast forging machine. The first and second drawing processes are performed diagonally. The third drawing process is performed to forge the billet into a ◇350mm square billet. Air cool the billet after forging.

[0048] ② The first static recrystallization homogenization forging, the blank material is heated to 900 ℃, the heating coefficient is 0.65min / mm, and after the end of the heat preservation, 2 upsetting and 2 drawing forging is carried out on the fast forging machine. This process adopts reversing upsetting and drawing, and the metal of the material end face is distributed around the blank. The two upsettings adopt the deformation methods of straight upsetting and straight drawing, and side upsetting and axial drawing respectively. After the second upsetting, the drawing is extended along the radial direction of the ingot, and the original end metal of the material is changed to the original end. When drawing, the large surface of the blank is deformed first, and then rotated 45° on the edge of the blank. Deform, then rotate 45° to deform on the large surface, and repeat the above forging process (when stretching, first deform on the large surface of the billet, then rotate 45° to deform on the edge of the billet, and then rotate 45° to deform on the large surface), rotate 16 times in total, forge to ◇350mm square billet, and immediately return to the 1050℃ heating furnace after forging, with a heat preservation coefficient of 0.50min / mm. After the heat preservation is completed, perform one upsetting and one drawing, forging to ◇350mm square billet, and stretch along the radial direction during stretching, with the metal on the end surface of the material still distributed around the billet, and air cool after forging;

[0049] ③ The second static recrystallization homogenization forging, the material is heated to 920 ℃, the heating coefficient is 0.65min / mm, and after the end of the heat preservation, it is forged on the fast forging machine with 2 upsetting and 2 drawing. This process adopts reversing upsetting and drawing, and the original end metal of the material is transformed to the original end. The two upsettings adopt the deformation methods of straight upsetting and straight drawing and side upsetting and axial drawing respectively. After the second upsetting, the drawing is stretched along the radial direction of the ingot, and the original end metal of the material is transformed to the original end. When stretching, the large surface of the billet is deformed first, and then rotated 45 degrees. Deform the billet on the edge, then rotate 45° to deform on the large surface, and repeat the above forging process (when stretching, first deform the billet on the large surface, then rotate 45° to deform on the billet edge, and then rotate 45° to deform on the large surface), rotate 16 times in total, and forge to ◇350mm square billet. After forging is completed, immediately return to the 1000℃ heating furnace with a thermal insulation coefficient of 0.55min / mm. After the thermal insulation is completed, step forging is carried out, with the first step forging to ◇310mm and the second step forging to ◇280mm;

[0050] ④ Two-phase zone billet forging, heating the material to 915℃, with a holding coefficient of 0.65min / mm. After the holding is completed, the step forging is carried out on a fast forging machine. The first step is forged to Φ200mm, and the second step is forged to Φ255mm. Air cooling is performed after forging;

[0051] ⑤ Forging of finished products, heat the material to 850℃, with a thermal insulation coefficient of 0.55min / mm. After the insulation is completed, heat it to 880℃, with a thermal insulation coefficient of 0.40min / mm. After the insulation is completed, heat it to 910℃, with a thermal insulation coefficient of 0.25min / mm. After the insulation is completed, heat it to 940℃, with a thermal insulation coefficient of 0.15min / mm. After the insulation is completed, heat the finished product to a thermal insulation temperature of 980℃, with a thermal insulation coefficient of 0.35min / mm. After the insulation is completed, forge the finished product on a precision forging machine. The first level of small step forging is to Φ150mm, the forging frequency is 400 times / min, and the forging is completed in 3 passes. The second level of step forging is to Φ180mm, the forging frequency is 300 times / min, and the forging is completed in 3 passes. The pulling rate during forging is 3mm / min, and air cooling is performed after forging.

[0052] The microstructure of each position of the step forging prepared in this embodiment is as follows Figure 2 As shown, the large and small step structures of the forgings are uniform lamellar structures. The comparison of fracture toughness under different organizational states is shown in Table 2:

[0053] .

Claims

1. A forging method for a high-uniform β-state titanium alloy step forging, characterized in that: The steps include: Step 1: Forging The titanium alloy ingot is heated to 1050-1150°C, and the billet is subjected to one-time upsetting forging using a fast forging machine to obtain an intermediate forging billet with an octagonal or quadrilateral cross section, which is then air-cooled after forging; Step 2: First static recrystallization homogenization forging The blank obtained in step 1 is heated to 50-80° C. below the β phase transformation point temperature, and a reversing upsetting and drawing forging is performed on the blank using a fast forging machine, wherein the drawing process is a drawing method of directional homogenization deformation; when the blank temperature is lower than 650° C. during the forging process, the blank is returned to the furnace for reheating at 50-80° C. below the β phase transformation point temperature, and the holding time is 30-60 min; after forging, the blank is returned to the furnace for recrystallization and homogenization, and the returning temperature is 80-120° C. above the β phase transformation point temperature, and after heating, upsetting and drawing forging is performed, and air cooling is performed after forging, and the cross-section of the blank after homogenization is octagonal or quadrilateral; Step 3: Second static recrystallization homogenization forging The blank obtained in step 2 is heated to 30-50° C. below the β phase transformation point temperature, and a fast forging machine is used to perform a reversing upsetting and drawing forging on the blank, and a directional homogenization deformation drawing method is performed during the drawing process; when the blank temperature is lower than 650° C. during the forging process, the blank is returned to the furnace for heating at 30-50° C. below the β phase transformation point temperature, and the holding time is 30-60 min; after forging, the blank is returned to the furnace for recrystallization and homogenization, and the return temperature is 50-80° C. above the β phase transformation point temperature. After heating, step drawing is performed, and air cooling is performed after forging. After homogenization, each step cross-section of the drawn forging blank is an octagon; Step 4: Step forging two-phase zone drawing and billet forging The intermediate billet obtained in step 3 is heated to 30-80°C below the β phase transformation point temperature, with a heating coefficient of 0.55-0.80 min / mm, and subjected to multi-fire drawing forging in the two-phase region, with a single-fire deformation of 20-40%, to obtain an intermediate billet for step forgings, which is air-cooled after forging, and the last fire drawing is performed by rolling drawing; Step 5: Finished Forging The intermediate billet obtained in step 4 is heated to 20-50°C above the β phase transformation point temperature. This heating is performed in a step-by-step heating manner. After heating is completed, the billet is forged into a finished product using a precision forging machine. The precision forging machine is forged for multiple passes to form a stepped forging product. The final forging temperature is 120°C higher than the β phase transformation point temperature.

2. The forging method of a high-uniform β-state titanium alloy step forging according to claim 1, characterized in that: In the above step 1, the heating coefficient of the blank forging is 0.50-0.80 min / mm, and the deformation amount of each upsetting and drawing is 30-50%.

3. The forging method of a high-uniform β-state titanium alloy step forging according to claim 1, characterized in that: The specific process of step 2 above is: Carry out in two batches, The first fire is 2 upsetting and 2 drawing, with a heating coefficient of 0.55-0.80min / mm, a single upsetting deformation of 20-45%, and radial drawing after the two upsettings, so that the metal on the end surface of the material is distributed around the billet. At the same time, the drawing process first draws along the large surface of the billet, then rotates the billet 45° to deform on the edge surface of the billet, and then rotates 45° to deform on the large surface. The above forging method is repeated until the target size is reached. The use of the above-mentioned directional uniform deformation drawing method can eliminate the deformation dead zone in the drawing process and achieve the effect of uniform drawing. The cross-section of the billet after forging is octagonal or quadrilateral, and it is returned to the furnace after forging. The second fire is 1 upsetting and 1 drawing, the heating coefficient is 0.30-0.55min / mm, the single upsetting deformation is 20-45%, and the billet is air-cooled after forging. The cross-section of the billet is still octagonal or quadrilateral. At this time, the metal on the end face of the material is distributed around the billet.

4. The forging method of a high-uniform β-state titanium alloy step forging according to claim 1, characterized in that: The specific process of step 3 above is: Carry out in two batches, The first fire is 2 upsetting and 2 drawing, with a heating coefficient of 0.55-0.80min / mm, a single upsetting deformation of 20-45%, and the two upsettings respectively adopt the deformation methods of straight upsetting and straight drawing and side upsetting and axial drawing. After the second upsetting, the drawing is done along the radial direction of the ingot to transform the original end metal of the material to the original end. The drawing process also adopts the drawing method of directional homogenization deformation. The cross section after forging is octagonal or quadrilateral, and the forging is returned to the furnace. The second fire is for drawing forging, with a heating coefficient of 0.30-0.55 min / mm, and step forging is performed to forge to two or more steps, with a drawing deformation of 10-50%, and air cooling after forging.

5. The forging method of a high-uniform β-state titanium alloy step forging according to claim 1, characterized in that: The specific process of step 4 is as follows: The two-phase zone is used for 1-5 fire drawing and forging. The drawing method is drawing forging, and the deformation of a single fire is 20-40%. When making the billet, the large and small steps are interchanged. The original large step adopts a large deformation and is forged to the small step of the finished step forging. The drawing deformation is 35~85%; the small step adopts a small deformation and is forged to the large step of the finished step forging. The drawing deformation is 10~65%, and air cooling is performed after forging.

6. The forging method of a high-uniform β-state titanium alloy step forging according to claim 1, characterized in that: The specific process of step 5 above is: The heating is carried out in a step-by-step heating manner, that is, the temperature is kept at 100-150°C below the β phase transformation point temperature, the holding time after reaching the temperature is the holding coefficient of 0.55-0.85min / mm, and the temperature is raised to 70-100°C below the β phase transformation point temperature after completion of the heating, the holding time after reaching the temperature is the holding coefficient of 0.35-0.55min / mm, and the temperature is raised to 40-70°C below the β phase transformation point temperature after completion of the heating, the holding time after reaching the temperature is the holding coefficient of 0.20-0.35min / mm, and the temperature is raised to 10-40°C below the β phase transformation point temperature after completion of the heating, the holding time after reaching the temperature is the holding coefficient of 0.10-0.20min / mm, and the temperature is heated to 20-50°C above the β phase transformation point temperature after completion of the heating, the holding time after reaching the temperature is the holding coefficient of 0.30-0.55 min / mm, after heating is completed, the billet is forged into finished product by a precision forging machine, the frequency of large-step forging of forgings is 150-600 times / min, the total forging deformation is 40-80%, the total number of passes is 3-5 times, of which the deformation of a single pass is 5-30%, and the deformation of the last pass is ≤10%; the frequency of small-step forging of forgings is 50-450 times / min, the total forging deformation is 10-60%, the total number of passes is 2-4 passes, of which the deformation of a single pass is 5-20%, and the deformation of the last pass is ≤5%, the forging method is reciprocating forging, the billet pulling rate is ≤8m / min, and the final forging temperature is ≥120℃ below the β phase transformation point temperature.

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