Extra-large-sized Ti80 titanium alloy forging billets with high impact toughness above 9 tons and manufacturing method

Abstract

The present invention discloses a super-large-sized Ti80 titanium alloy forging blank with high impact toughness above 9 tons and a manufacturing method, including the following steps: S1) using a Ti80 titanium alloy ingot with a diameter of Φ960 - 1060 mm and a weight of 9 - 17 tons; S2) cogging forging, the ingot is upset and drawn in the β phase region for 2 - 5 heats, and the upset and draw deformation amount for each heat is 30 - 55%; S3) intermediate forging, the billet is upset and drawn in the β phase region for 3 - 4 heats, the upset and draw deformation amount for each heat is 30 - 55%, and it is air-cooled after upset and draw; S4) finish forging, drawing is carried out for 3 - 5 heats at 30 - 60 °C below the phase transformation point, the deformation amount for each heat is 10 - 30%, and the total deformation amount ≥ 50%. The obtained forging blank has a thickness of 200 - 500 mm, a width of 1000 - 2500 mm, and a length of 2000 - 4000 mm. After annealing, the tensile strength at each position of the forging blank ≥ 840 MPa, the yield strength ≥ 740 MPa, the elongation rate ≥ 10%, and the impact energy > 60 J. The obtained forging blank has a uniform structure, the material does not crack during the forging process, and the finished product rate and the impact toughness after annealing are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy hot processing, and particularly relates to a super-large-sized Ti80 titanium alloy forging billet with a weight of more than 9 tons and high impact toughness and a manufacturing method thereof. Background Art

[0002] Ti80 titanium alloy is a 780 MPa-class marine near-α titanium alloy with excellent strength, toughness and weldability, and its nominal composition is Ti-6Al-2Zr-1Mo-3Nb. The impact toughness KV2, fracture toughness K IC and stress corrosion fracture toughness K ISCC , welding performance and other indexes of this alloy are superior to those of TC4 ELI alloy, and it is suitable for making pressure-resistant shells of deep submersibles, ship hull structural parts, etc.

[0003] With the rapid development of fields such as ships and ocean engineering, the demand for large-sized and single-heavy Ti80 forgings and plates is increasing day by day, and correspondingly, high-quality forging billets with large sizes and single weights are required. At present, the single weight of the commonly used Ti80 alloy forging billets is generally less than 2 tons. For super-large-sized Ti80 titanium alloy forging billets with a finished product single weight exceeding 8 tons, the engineering preparation technology thereof is not yet mature.

[0004] First of all, compared with materials such as steel, titanium alloy has low thermal conductivity, high temperature sensitivity and a narrow hot processing window. Especially when the billet size increases, it is difficult to ensure the deformation effect of the forging billet and the uniformity of the internal temperature distribution, and problems such as poor forging penetration in the core of the material and non-uniformity of the structure in different parts of the material caused by multi-pass forging are likely to occur, which directly affects the structure uniformity of the subsequent rolled plate.

[0005] Secondly, Ti80 titanium alloy belongs to a near-α titanium alloy, and cracks are likely to occur during the forging process, and it is difficult to control the defects of the forging billet.

[0006] Thirdly, the deformation resistance of Ti80 titanium alloy is relatively large. If the forging process design is unreasonable, the forging pressure will increase sharply, resulting in being unable to forge or requiring a forging equipment of more than 10,000 tons, which limits the preparation of the billet.

[0007] In addition, components used in fields such as ships and ocean engineering are subject to the scouring and impact of sea waves and floating objects during service, and very high requirements are put forward for the impact toughness of the material. From the forging billet to the forging and rolled plate, their structures and impact toughness have a certain heredity. If the impact toughness of the forging billet is poor, the risk that the impact toughness of the forging or rolled plate does not meet the requirements is very high.

[0008] Chinese Patent 202311397391.0 discloses a forging method for large-sized Ti80 titanium alloy forging blanks, including cogging forging, intermediate forging and finish forging. Among them, during the intermediate blank forging process, the blank is forged and drawn below the phase transformation point. For ingots below 8 tons (a 7-ton ingot is used in the embodiment), but for ingots above 9 tons, the pressure during upsetting in the two-phase region can reach more than 8,000 tons, and conventional forging equipment cannot meet the requirements. After intermediate blank forging, water quenching is used. For titanium alloys such as TC4, there are no major problems, but for Ti80 titanium alloy with a large cracking tendency, there are problems such as water quenching cracking, difficult subsequent surface machining, and large material loss.

[0009] Chinese Patent CN111906225 discloses a forging method for super-large-sized Ti80 titanium alloy forging blanks, which also includes cogging forging, intermediate forging and finish forging. During the intermediate forging process, forging is carried out 6 to 9 times in the single-phase region first, and then 3 to 5 times in the two-phase region. The intermediate forging adopts the "high-low" forging process, and there are many forging passes, which easily cause uneven material organization, poor forging penetration in the core of the material, low material yield and high cost.

[0010] Chinese Patent 202311199508.4 discloses a forging method for titanium alloy blanks for ships with low anisotropy. A forging method combining various deformation methods such as "high-low-high-low" cyclic deformation, reverse upsetting and drawing, diagonal drawing and flattening is adopted to reduce the anisotropy of the titanium alloy plates prepared from the forging blanks. The "high-low-high-low" cyclic deformation method is applicable to ingots below 8 tons, but for larger blanks, there are also problems such as inability to upset in the two-phase region ("low"). In addition, the above process uses a large amount of reverse upsetting and drawing, resulting in problems such as material cracking and low yield.

[0011] Chinese Patent CN111230012B discloses a forging method for Ti80 titanium alloy. Deformation is carried out in sequence from above the phase transformation point to below the phase transformation point, ensuring sufficient deformation per forging pass. The obtained bars have uniform organization in each part, the primary α phase is equiaxed, and its content is between 60% and 80%. The impact toughness after annealing is ≥35J / cm 2 This patent only targets bars, and the obtained impact toughness is not high.

[0012] Chinese Patent CN113755709B discloses a preparation method for Ti80 titanium alloy bars with high impact toughness. By controlling the oxygen content and the content of other impurity elements of the bars, and combining high-temperature forging and high-temperature annealing in the two-phase region, the phase ratio and phase morphology are regulated, and the impact toughness of the bars is improved without reducing the strength of the Ti80 alloy. This patent also only targets bars, and its effectiveness for large forging blanks remains to be verified.

[0013] In summary, at present, there are still many problems in the manufacture of Ti80 titanium alloy forging blanks with high impact toughness in the super-large specifications above 9 tons (9 - 17 tons), with thickness of 200 - 500 mm, width of 1000 - 2500 mm, and length of 2000 - 4000 mm, making it difficult to meet the requirements of the ship and ocean engineering fields. Summary of the Invention

[0014] The purpose of the present invention is to provide a method for manufacturing a super-large specification Ti80 titanium alloy forging blank with high impact toughness above 9 tons, to improve the microstructure uniformity and impact toughness of the forging blank above 9 tons, prevent material cracking during the forging process, and increase the finished product rate; the obtained titanium alloy forging blank has a uniform equiaxed microstructure, the primary α-phase content is 70 - 90%, the short side size is 12 - 20 μm, the aspect ratio is less than 1.5, and after annealing, the tensile strength at each position of the titanium alloy forging blank is ≥840 MPa, the yield strength is ≥740 MPa, the elongation is ≥10%, and the impact energy is >60 J.

[0015] To achieve the above purpose, the technical solution of the present invention is as follows:

[0016] A method for manufacturing a super-large specification Ti80 titanium alloy forging blank with high impact toughness above 9 tons, comprising the following steps:

[0017] S1) Titanium alloy ingot

[0018] The diameter of the Ti80 titanium alloy ingot is Φ960 - 1060 mm, and the weight is 9 - 17 tons;

[0019] S2) Initial forging

[0020] The Ti80 titanium alloy ingot is subjected to upsetting and drawing for 2 - 5 heating passes, the upsetting and drawing holding temperature is 1050 - 1180 °C, the upsetting and drawing method is flat anvil upsetting plus transverse drawing, the upsetting and drawing deformation amount for each heating pass is 30 - 55%, and after the last heating pass of upsetting and drawing, it is air-cooled to obtain the first forging blank;

[0021] S3) Intermediate forging

[0022] The obtained first forging blank is subjected to upsetting and drawing for 3 - 4 heating passes at 20 - 50 °C above the phase transformation point, the upsetting and drawing method is flat anvil upsetting plus transverse drawing, the upsetting and drawing deformation amount for each heating pass is 30 - 55%, and after the last heating pass of upsetting and drawing, it is air-cooled to obtain the second forging blank;

[0023] S4) Final forging

[0024] The second forging blank is longitudinally drawn for 3 - 5 heating passes at 30 - 60 °C below the phase transformation point, the deformation amount for each heating pass is 10 - 30%, the total deformation amount ≥50%, and it is air-cooled to obtain the forging blank.

[0025] Preferably, in step S1), the Ti80 titanium alloy ingot is obtained by at least three times of vacuum consumable melting.

[0026] Preferably, the mass percentages of the components in the Ti80 titanium alloy ingot are as follows: 6.0% ≤ Al ≤ 6.3%, 2.8% ≤ Nb ≤ 3.2%, 1.9% ≤ Zr ≤ 2.1%, 1.0% ≤ Mo ≤ 1.5%, 0 < Si ≤ 0.03%, 0 < Fe ≤ 0.25%, 0 < C ≤ 0.10%, 0 < N ≤ 0.05%, 0 < H ≤ 0.010%, 0.06 ≤ O ≤ 0.10%, and the balance is Ti and unavoidable impurities.

[0027] Preferably, in step S2), the forging process adopts temperature reduction upsetting and drawing. The holding temperature for the first upsetting and drawing is 1150 - 1180 °C. After each upsetting and drawing, the ingot is returned to the furnace, and the holding temperature is 20 - 50 °C lower than that of the previous upsetting and drawing; the holding time t = (0.15 - 0.5) × H, where t is in minutes and H is the thickness of the forging blank in millimeters.

[0028] Preferably, in step S2), the first forging blank is an octagonal blank.

[0029] Preferably, in step S3), after each upsetting and drawing, the cross-section of the forging blank is flat and rectangular, and the ratio of the long side to the short side is 1.2 - 1.8.

[0030] Preferably, in step S3), the holding temperature after each upsetting and drawing is the same, and the holding time t = (0.15 - 0.5) × H, where t is in minutes and H is the thickness of the forging blank in millimeters.

[0031] Preferably, in steps S2) and S3), during each upsetting and drawing process, the upsetting speed is 30 - 40 mm / s, and the upsetting process pauses 2 - 3 times, with each pause time being 3 - 8 seconds.

[0032] Preferably, in step 3), the air cooling time ≥ 1 h.

[0033] Preferably, in step 4), the deformation amount for each heat is 10 - 30%. During the longitudinal drawing process for each heat, the deformation amount for the first pass is 1.5 - 4%, the deformation amount for the last pass is 0.5 - 2%, the deformation amount for the remaining passes is 5 - 15%, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the drawing down pressure speed is 50 - 70 mm / s.

[0034] The titanium alloy forging blank obtained by the present invention has a thickness of 200 - 500 mm, a width of 1000 - 2500 mm, and a length of 2000 - 4000 mm;

[0035] The microstructure of the titanium alloy forging billet is a uniform equiaxed structure, with the primary α-phase content being 70-90%, the short side dimension being 12-20 μm, and the aspect ratio being less than 1.5;

[0036] After annealing, the tensile strength of each position of the titanium alloy forging billet is ≥840 MPa, the yield strength is ≥740 MPa, the elongation is ≥10%, and the impact energy is >60 J.

[0037] In the manufacturing method of the present invention:

[0038] The present invention selects a Ti80 titanium alloy ingot with a diameter of Φ960-1060 mm (weight 9-17 tons) to meet the requirements of the ship and ocean engineering fields for large-size and single-large-weight Ti80 forging billets. The mass percentages of each component in the titanium alloy ingot are: 6.0% ≤ Al ≤ 6.3%, 2.8% ≤ Nb ≤ 3.2%, 1.9% ≤ Zr ≤ 2.1%, 1.0% ≤ Mo ≤ 1.5%, 0 < Si ≤ 0.03%, 0 < Fe ≤ 0.25%, 0 < C ≤ 0.10%, 0 < N ≤ 0.05%, 0 < H ≤ 0.010%, 0.06 ≤ O ≤ 0.10%, and the balance is Ti and unavoidable impurities. On the one hand, the contents of Al, Nb, Zr, and Mo are preferably selected to ensure strength, and on the other hand, the O content is appropriately reduced to improve impact toughness, but too low is not conducive to strength, so the lower limit of the O content is selected at 0.06%.

[0039] The titanium alloy ingot is obtained through at least three times of vacuum consumable melting to ensure the composition uniformity.

[0040] The design idea of the cogging forging in step S2):

[0041] The Ti80 titanium alloy ingot is subjected to upsetting and drawing for 2-5 heating times, the upsetting and drawing holding temperature is 1050-1180 °C, the upsetting and drawing method is flat anvil upsetting plus transverse drawing, the upsetting and drawing deformation amount per heating time is controlled at 30-55%, and after the last heating time of upsetting and drawing, it is air-cooled to obtain the first forging billet.

[0042] (1) Upsetting and drawing holding temperature: For large-size titanium alloy ingots, the melting and solidification time is long, and its as-cast structure is extremely coarse, with the grain width reaching several centimeters. When heated and forged at 1050-1180 °C, the material is in the β single-phase region. On the one hand, the β grains grow continuously, and on the other hand, the β grains are elongated along the direction of metal flow after being deformed, and dynamic recrystallization occurs under certain conditions.

[0043] (2) Deformation amount: Controlling the deformation amount of each upsetting and drawing at 30-55% can achieve the purpose of crushing and refining the as-cast structure of the ingot. If the deformation amount is less than 30%, the recrystallization occurs incompletely; if the deformation amount is greater than 55%, the deformation amount is too large, and folding is prone to occur during the upsetting process of the billet, and surface cracking is prone to occur during subsequent drawing.

[0044] (3) Deformation method: The upsetting and drawing method is flat anvil upsetting plus transverse drawing to improve the tissue uniformity. After upsetting, a deformation dead zone is formed at the place where the blank contacts the upper and lower anvils. The schematic diagram of the blank shape and strain distribution obtained by longitudinal drawing in the traditional process is as Figure 1 shown. A sunken deformation dead zone is likely to appear at the end, and a folded hole is formed subsequently and is not easy to eliminate. The schematic diagram of the blank shape and strain distribution obtained by transverse drawing in the present invention is as Figure 2 shown, which is conducive to the material at the end of the blank bulging outwards, and the deformed tissue is more uniform.

[0045] Furthermore, cooling forging is adopted between each heat treatment. The upsetting and drawing holding temperature of the first heat treatment is controlled at 1150 - 1180 °C. After each heat treatment of upsetting and drawing, it is returned to the furnace, and the holding temperature is 20 - 50 °C lower than that of the previous heat treatment; the deformation amount of each heat treatment is 30 - 55%, and the holding time t = (0.15 - 0.5) × H, where t is in minutes and H is the thickness of the forging blank in mm. Only the coefficient is substituted for calculation in this formula without substituting the unit. In the cogging forging, cooling upsetting and drawing is adopted, and the temperature drop range of each heat treatment of upsetting and drawing is 20 - 50 °C. On the one hand, it can, to a certain extent, inhibit the excessive growth of the recrystallized grains formed during the forging process of the previous heat treatment, and on the other hand, it also ensures the smooth progress of recrystallization during the forging process of this heat treatment. The upsetting and drawing holding time is based on being burned through. If the time is too long, the grains will grow, affecting the final structure.

[0046] Design idea of the intermediate forging in step S3):

[0047] The first forging blank obtained is upset and drawn 3 - 4 times at 20 - 50 °C above the phase transformation point. The upsetting and drawing method is flat anvil upsetting plus transverse drawing. The upsetting and drawing deformation amount of each heat treatment is controlled at 30 - 55%. After the last heat treatment of upsetting and drawing, it is air-cooled to obtain the second forging blank.

[0048] (1) Upsetting and drawing temperature: The purpose of upsetting and drawing the blank multiple times in the single-phase region is to further refine the β grains and improve the tissue uniformity of the blank. In order to prevent the growth of recrystallized β grains, the forging temperature is selected at 20 - 50 °C above the phase transformation point.

[0049] (2) Deformation amount: In the selection of the upsetting and drawing deformation amount, on the one hand, a larger deformation amount is considered to increase the strain energy and promote the recrystallization of the material to refine the grains, and on the other hand, surface defects are considered to be avoided. Therefore, the upsetting and drawing deformation amount of each heat treatment is controlled at 30 - 55%.

[0050] (3) Deformation method: To improve the forging penetration of the billet, the upsetting and drawing forging method still selects flat anvil upsetting plus transverse drawing, but the cross-section of the billet is selected as a flat rectangle, and the ratio of its long side to short side is selected to be 1.2 - 1.8. On the one hand, this cross-section selection is beneficial to saving forging time and preventing the temperature in some areas from dropping below the phase transformation point during forging, which may cause non-uniform structure and surface cracking; on the other hand, during the upsetting and flattening processes, the reduction amount during drawing can be increased. The large reduction amount makes the internal deformation of the billet sufficient and increases the forging penetration; finally, the thickness of the thin cross-section becomes smaller, the reheating time is shortened, and excessive grain growth is avoided.

[0051] (4) Cooling method: Air cooling is adopted after forging in the single-phase region. Accelerating the cooling rate will be beneficial to inhibiting the growth of recrystallized β grains, and at the same time increasing the nucleation points during the β→α transformation and inhibiting the growth of α lamellae, obtaining thinner grain boundary α and α lamellae structures in the grains, providing a lamellar structure that is easy to break for subsequent deformation in the two-phase region. Common cooling methods include air cooling, air blast cooling, and water cooling. Water cooling will increase the risk of surface cracking. Therefore, air blast cooling is adopted after forging in the single-phase region. To ensure the effect of air blast cooling, it is preferred that the air blast cooling time ≥ 1 h.

[0052] Design idea of finished product forging in step S4):

[0053] The obtained second forging billet is longitudinally drawn 3 - 5 times at 30 - 60 °C below the phase transformation point, with the deformation amount per pass being 10 - 30%, and the total deformation amount ≥ 50%, and the forging billet is obtained by air cooling.

[0054] (1) Drawing temperature: The drawing is selected to be carried out at 30 - 60 °C below the phase transformation point. If the temperature is too low, the deformation resistance is large and the material is prone to cracking; if the temperature is too high, the α lamella content is small and the crushing effect is not good.

[0055] (2) Deformation amount: On the premise of ensuring the deformation requirements of the foregoing steps, a total deformation amount ≥ 50% in the finished product forging stage can achieve sufficient crushing of the lamellar structure. Design 3 - 5 times of longitudinal drawing, and control the deformation amount per pass to be 10 - 30% to ensure the surface quality and the forging penetration of the core of the intermediate billet and the finished product thickness slab during the deformation process.

[0056] Furthermore, during the longitudinal drawing process for each heat, the deformation amount in the first pass is 1.5 - 4%, the deformation amount in the last pass is 0.5 - 2%, the deformation amount in the remaining passes is 5 - 15%, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the drawing-down speed is 50 - 70 mm / s. The billet structure cooled from the single-phase region during the intermediate forging in step S3) is lamellar Widmanstätten structure with poor plasticity. The deformation amount in the first pass is 1.5 - 4%. A small reduction is used in the first pass, and the deformation is mainly concentrated on the surface to break the lamella on the surface layer and improve the surface plasticity. Then, the reduction is increased, and the deformation amount in each pass is controlled at 5 - 15% to ensure the forging penetration of the billet core. The deformation amount in the last pass is controlled at 0.5 - 2% to ensure the flatness and surface quality of the billet surface. The selection of the feeding amount is to ensure the forging penetration of the core. For the selection of the drawing-down speed, if the speed is too high, there is a possibility of temperature rise in the core. Once it exceeds the phase transformation point, the forging blank is scrapped. If the speed is too low, the billet is prone to cooling during the drawing process, the deformation resistance increases, and the forging pressure increases sharply, resulting in inability to forge or requiring a forging equipment of more than 10,000 tons, which limits the preparation of the billet. On the other hand, the low-temperature forging billet is prone to cracking.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] In the prior art for the forging process of Ti80 titanium alloy, during the intermediate forging process, the forging heating temperature is alternately above and below the phase transformation point. For the forging of large-sized ingots, this method will cause uneven material structure and poor forging penetration in the core.

[0059] Through the method of cogging forging plus intermediate forging plus finish forging, and combining the control of the deformation method, cooling method, deformation amount per heat and total deformation amount during the forging process, the present invention enables the structure of the extra-large-sized Ti80 titanium alloy above 9 tons to be fully broken and refined during the forging process, improves the uniformity of the billet structure, so that the structures of the surface layer and the core of the titanium alloy are uniform and fine, and improves the toughness of the core of the extra-large-sized Ti80 titanium alloy after annealing.

[0060] During the cogging forging process of the present invention, by controlling the upsetting and drawing method as flat anvil upsetting plus transverse drawing and adopting a large deformation amount, the deformation amount per heat is 30 - 55%, the structure is fully broken and refined, and the structure becomes more uniform.

[0061] During the intermediate forging process, the forging heating temperature is controlled in the high-temperature region 20 - 50°C above the phase transformation point, and the deformation amount is increased. The upsetting and drawing deformation amount per heat is controlled at 30 - 55%. After 3 - 4 heats of upsetting and drawing, combined with the deformation methods of upsetting / flat-square upsetting plus transverse drawing to fully break the forged structure, refine the β grains and improve the uniformity of the billet structure. And after upsetting and drawing, sufficient air cooling is carried out to refine the precipitated lamellar structure and improve the lamellar structure breaking effect during the finish forging deformation in the two-phase region subsequently.

[0062] During the finished product forging process, the forging temperature is controlled in the two-phase region, the deformation method is longitudinal drawing out, the deformation amount per heating is controlled at 10-30%, and the total deformation amount is ≥50% to fully break the lamellae and improve the uniformity of the forging blank structure.

[0063] For Ti80 titanium alloy, the size and structure uniformity of the primary α-phase of the forging blank will be inherited to the rolled state and even the heat-treated state, ultimately affecting the impact toughness of the finished product. Therefore, controlling the size and distribution of the primary α-phase of the forging blank is the key to obtaining high impact toughness in the forged state and finished product. During impact, the crack nucleation position is mainly concentrated near the primary a-phase boundary. The larger the size and the more uneven the distribution of the primary a-phase, the easier it is for pores to initiate and the lower the impact toughness of the material. Through the control of the deformation method, deformation amount and cooling method in the ingot forging, intermediate forging and finished product forging, the present invention realizes the manufacture of Ti80 titanium alloy forging blanks with a super-large specification of more than 9 tons. The obtained forging blank has a uniform microstructure and a fine primary α-phase with a short side size of 12-20 μm and an aspect ratio of less than 1.5, improving the impact toughness after annealing of the forging blank.

[0064] The forging blank obtained by using a Ti80 titanium alloy ingot with a super-large specification of more than 9 tons has a thickness of 200-500 mm, a width of 1000-2500 mm, and a length of 2000-4000 mm. After annealing, the tensile strength at each position of the titanium alloy forging blank is ≥840 MPa, the yield strength is ≥740 MPa, the elongation is ≥10%, and the impact energy is >60 J.

[0065] In the present invention, the cumulative total number of upsetting and drawing operations in the ingot forging plus intermediate forging is controlled within 5-9 times, and there is no need for reverse upsetting and drawing, avoiding material cracking, making the process control easier and the finished product rate higher. Moreover, the upsetting and drawing temperature before finished product forging is relatively high, avoiding the dependence on large-tonnage equipment in the traditional process for forging the core of super-large specification ingots to be fully penetrated at low temperature. Brief Description of the Drawings

[0066] Figure 1 It is a schematic diagram of the blank shape and strain distribution after longitudinal drawing out deformation;

[0067] Figure 2 It is a schematic diagram of the blank shape and strain distribution after transverse drawing out deformation;

[0068] Figure 3 It is the appearance morphology of a Ti80 titanium alloy forging blank with a thickness of 450 mm prepared in Example 1 of the present invention;

[0069] Figure 4 It is the microstructure of a Ti80 titanium alloy forging blank with a thickness of 450 mm prepared in Example 1 of the present invention;

[0070] Figure 5Appearance morphology of the Ti80 titanium alloy forging blank with a thickness of 400 mm prepared in Example 2 of the present invention;

[0071] Figure 6 Microstructure of the Ti80 titanium alloy forging blank with a thickness of 400 mm prepared in Example 2 of the present invention;

[0072] Figure 7 Microstructure of the Ti80 titanium alloy forging blank with a thickness of 300 mm prepared in Example 3 of the present invention;

[0073] Figure 8 Microstructure of the Ti80 titanium alloy forging blank with a thickness of 300 mm prepared in the comparative example. Detailed implementation manners

[0074] The present invention will be further described below in conjunction with examples and drawings.

[0075] The compositions of the Ti80 titanium alloy used in the examples and comparative examples of the present invention are shown in Table 1. Tables 2, 3, and 4 are the specific control parameters of the processes in the examples and comparative examples of the present invention. Table 5 is the properties of the titanium alloys obtained in the examples and comparative examples of the present invention.

[0076] Example 1

[0077] A manufacturing method for a Ti80 titanium alloy forging blank with specifications of 450×2000×2500 includes the following steps:

[0078] S1) Prepare a titanium alloy ingot

[0079] The diameter of the Ti80 titanium alloy ingot is Φ1060 mm, the weight is 13 tons, and the phase transformation point T β is 990 °C;

[0080] S2) Perform cogging forging

[0081] The Ti80 titanium alloy ingot obtained in step S1) is subjected to upsetting and drawing for 3 heats;

[0082] The first heat of upsetting and drawing: The upsetting and drawing holding temperature is 1180 °C, and after reaching the temperature, the holding time is 15 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 55%. After upsetting, the billet is longitudinally drawn to an octagon of 1200;

[0083] The second heat of upsetting and drawing: The upsetting and drawing holding temperature is 1130 °C, and after reaching the temperature, hold for 3.5 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 55%. After upsetting, the billet is longitudinally drawn to an octagon of 1200;

[0084] The 3rd upsetting and drawing: The upsetting and drawing holding temperature is 1080 °C. After reaching the temperature, hold for 4.0 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 55%. After upsetting, longitudinally draw the billet to an octagon with a side length of 1200;

[0085] Air-cool the billet to room temperature after forging to obtain the first forged billet;

[0086] S3) Intermediate forging

[0087] Perform 4 upsetting and drawing operations on the obtained first forged billet;

[0088] The 1st upsetting and drawing: The upsetting and drawing temperature is 1020 °C, the holding time is 16 h, the upsetting deformation amount is 45%. After upsetting, longitudinally draw the billet to obtain a billet with a cross-sectional size of 1000×1200 mm;

[0089] The 2nd upsetting and drawing: After the 1st forging, return the billet to the furnace, the holding temperature is 1020 °C, hold for 3 hours, use a flat anvil to perform one upsetting deformation with a deformation amount of 35%. After upsetting, longitudinally draw the billet to a billet with a cross-sectional size of 1000×1200 mm;

[0090] The 3rd upsetting and drawing: After the 2nd forging, return the billet to the furnace, the holding temperature is 1020 °C, hold for 3 hours, use a flat anvil to perform one upsetting deformation with a deformation amount of 35%. After upsetting, longitudinally draw the billet to a billet with a cross-sectional size of 1000×1200 mm;

[0091] The 4th upsetting and drawing: After the 2nd forging, return the billet to the furnace, the holding temperature is 1020 °C, hold for 3 hours, use a flat anvil to perform one upsetting deformation with a deformation amount of 35%. After upsetting, longitudinally draw the billet to a billet with a cross-sectional size of 1000×1200 mm;

[0092] After forging, air-cool the billet for 3 h to obtain the second forged billet;

[0093] S4) Finish forging

[0094] Perform 3 longitudinal drawing operations on the obtained second forged billet;

[0095] The 1st drawing: The drawing temperature is 960 °C. When drawing and forming, the deformation amount of the 1st pass is 1.5%, the deformation amounts of the 2nd and 3rd passes are 12 - 13%, and the deformation amount of the last pass is 0.7%. After the 1st drawing, the thickness of the slab is 750 mm. The feeding amount during the drawing process is 1 / 3 - 1 / 2 of the anvil width, and the drawing downward pressure speed is 50 - 70 mm / s;

[0096] The second forging pass of drawing out: The forging temperature of drawing out is 950°C. When forming by drawing out, the deformation rate of the first pass is 3.3%, the deformation rates of the second and third passes are 11 - 14%, the deformation rate of the last pass is 1%. After the second forging pass of drawing out, the thickness of the slab is 550 mm. The feeding amount during the drawing out process is 1 / 3 - 1 / 2 of the anvil width, and the pressing down speed of drawing out is 50 - 70 mm / s;

[0097] The third forging pass of drawing out: The forging temperature of drawing out is 950°C. When forming by drawing out, the deformation rate of the first pass is 1.8%, the deformation rate of the second pass is 9.3%, the deformation rate of the third pass is 5.1%, the deformation rate of the last pass is 1.1%. After the third forging pass of drawing out, the thickness of the slab is 460 mm. The feeding amount during the drawing out process is 1 / 3 - 1 / 2 of the anvil width, and the pressing down speed of drawing out is 50 - 70 mm / s;

[0098] After longitudinal drawing out, the blank is air-cooled. After sizing and facing, the specifications of the forged blank are 450×2000×2500 mm.

[0099] Figure 3 This is the appearance morphology diagram of the Ti80 titanium alloy forged blank prepared in Example 1 of the present invention. Figure 4 This is the microstructural picture of the surface layer and the position at 1 / 2 thickness of the Ti80 titanium alloy forged blank prepared in Example 1 of the present invention. It can be seen from the figure that the obtained forged blank structure is a uniform equiaxed structure, composed of a β matrix and ellipsoidal primary α phases. The content of the primary α phases is 70%, and the grain size is 12 - 20 μm.

[0100] Example 2

[0101] A manufacturing method for a Ti80 titanium alloy forged blank with specifications of 400×1850×2650 includes the following steps:

[0102] S1) Prepare a titanium alloy ingot

[0103] The diameter of the Ti80 titanium alloy ingot is Φ1060 mm, the weight is 11 tons, and the phase transformation point T β is 987°C;

[0104] S2) Perform cogging forging

[0105] Subject the Ti80 titanium alloy ingot obtained in step S1) to cogging forging through 4 forging passes of upsetting and drawing out;

[0106] The first forging pass of upsetting and drawing out: The holding temperature for upsetting and drawing out is 1160°C. After reaching the temperature, hold for 15 h. Perform one upsetting deformation using a flat anvil, with a deformation rate of 55%. After upsetting, perform transverse drawing out on the blank until it reaches an octagonal shape of 1100;

[0107] The second forging pass of upsetting and drawing out: The holding temperature for upsetting and drawing out is 1130°C. After reaching the temperature, hold for 3.0 h. Perform one upsetting deformation using a flat anvil, with a deformation rate of 50%. After upsetting, perform transverse drawing out on the blank until it reaches an octagonal shape of 1100;

[0108] The 3rd upsetting and drawing: The upsetting and drawing holding temperature is 1080 °C. After reaching the temperature, hold for 3.0 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 50%. After upsetting, longitudinally draw the billet to an 1100 octagon;

[0109] The 4th upsetting and drawing: The upsetting and drawing holding temperature is 1050 °C. After reaching the temperature, hold for 4.0 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 35%. After upsetting, longitudinally draw the billet to an 1100 octagon;

[0110] Air-cool the billet to room temperature after forging to obtain the first forged billet;

[0111] S3) Intermediate forging

[0112] Perform 3 upsetting and drawing operations on the obtained first forged billet;

[0113] The 1st upsetting and drawing: The upsetting and drawing temperature is 1030 °C, the holding time is 12 h, the upsetting deformation amount is 42%. After upsetting, longitudinally draw the billet to obtain a billet with a cross-sectional size of 950×1100 mm;

[0114] The 2nd upsetting and drawing: After forging in the 1st fire, return to the furnace, the holding temperature is 1030 °C, hold for 3.5 hours, use a flat anvil to perform one upsetting deformation with a deformation amount of 33%. After upsetting, longitudinally draw the billet to a billet with a cross-sectional size of 950×1100 mm;

[0115] The 3rd upsetting and drawing: After forging in the 2nd fire, return to the furnace, the holding temperature is 1030 °C, hold for 3.5 hours, use a flat anvil to perform one upsetting deformation with a deformation amount of 33%. After upsetting, longitudinally draw the billet to a billet with a cross-sectional size of 950×1200 mm;

[0116] After forging, air-cool the billet for 4 h to obtain the second forged billet;

[0117] S4) Finished forging

[0118] Perform 4 longitudinal drawing operations on the obtained second forged billet;

[0119] The 1st drawing: The drawing temperature is 950 °C. When drawing and forming, the deformation amount of the 1st pass is 1.6%, the deformation amounts of the 2nd and 3rd passes are 7 - 7.5%, and the deformation amount of the last pass is 0.6%. After the 1st drawing, the thickness of the slab is 800 mm. The feeding amount during the drawing process is 1 / 3 - 1 / 2 of the anvil width, and the drawing downward pressure speed is 50 - 70 mm / s;

[0120] The second forging pass of stretching: The stretching temperature is 950 °C. During stretching and forming, the deformation amount of the first pass is 2.7%, the deformation amounts of the second and third passes are 11 - 14%, the deformation amount of the last pass is 1%. After the second forging pass of stretching, the thickness of the slab is 550 mm. During the stretching process, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the downward pressing speed of stretching is 50 - 70 mm / s;

[0121] The third forging pass of stretching: The stretching temperature is 940 °C. During stretching and forming, the deformation amount of the first pass is 1.8%, the deformation amount of the second pass is 9.3%, the deformation amount of the third pass is 7.1%, the deformation amount of the last pass is 1.1%. After the third forging pass of stretching, the thickness of the slab is 450 mm. During the stretching process, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the downward pressing speed of stretching is 50 - 70 mm / s;

[0122] The fourth forging pass of stretching: The stretching temperature is 940 °C. During stretching and forming, the deformation amount of the first pass is 2.2%, the deformation amount of the second pass is 11.4%, the deformation amount of the third pass is 6.4%, the deformation amount of the last pass is 1.4%. After the fourth forging pass of stretching, the thickness of the slab is 410 mm. During the stretching process, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the downward pressing speed of stretching is 50 - 70 mm / s;

[0123] After longitudinal stretching, the blank is air-cooled. After sizing and facing, the dimensions of the forging blank are 400×1950×2650 mm.

[0124] Figure 5 This is the appearance morphology diagram of the Ti80 titanium alloy forging blank prepared in Example 2 of the present invention. Figure 6 This is the microstructural picture of the surface layer and the 1 / 2 thickness position of the Ti80 titanium alloy forging blank prepared in Example 2 of the present invention. The structure is a uniform equiaxed structure, composed of a β matrix and ellipsoidal primary α phases. The content of the primary α phases is as high as 90%, and the grain size is 12 - 20 μm.

[0125] Example 3

[0126] A manufacturing method for a Ti80 titanium alloy forging blank with dimensions of 300×1800×3300 includes the following steps:

[0127] S1) Prepare a titanium alloy ingot

[0128] The diameter of the Ti80 titanium alloy ingot is Φ960 mm, and the weight is 9.7 tons. The phase transformation point T β is 991 °C;

[0129] S2) Perform cogging forging

[0130] Subject the Ti80 titanium alloy ingot obtained in step S1) to cogging forging through two forging passes of upsetting and stretching;

[0131] The first forging: The forging and upsetting holding temperature is 1150 °C. After reaching the temperature, hold for 10 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 35%. After upsetting, longitudinally elongate the blank to an octagon with a side length of 1000;

[0132] The second forging: The forging and upsetting holding temperature is 1130 °C. After reaching the temperature, hold for 2.5 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 35%. After upsetting, longitudinally elongate the blank to an octagon with a side length of 1000;

[0133] After forging, air cool to room temperature to obtain the first forging blank;

[0134] S3) Intermediate forging

[0135] The obtained first forging blank is subjected to 3 times of forging and upsetting;

[0136] The first forging: The forging temperature is 1020 °C, the holding time is 12 h, the upsetting deformation amount is 40%. After upsetting, longitudinally elongate the blank to obtain a blank with a cross-sectional size of 800×1200 mm;

[0137] The second forging: After the first forging, return to the furnace. The holding temperature is 1020 °C, hold for 2.5 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 40%. After upsetting, longitudinally elongate the blank to a blank with a cross-sectional size of 800×1200 mm;

[0138] The third forging: After the second forging, return to the furnace. The holding temperature is 1020 °C, hold for 2.5 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 40%. After upsetting, longitudinally elongate the blank to a blank with a cross-sectional size of 800×1200 mm;

[0139] After forging, air cool the blank with a cooling time of 2.5 h to obtain the second forging blank;

[0140] S4) Finish forging

[0141] The obtained second forging blank is subjected to 3 times of longitudinal elongation;

[0142] The first elongation: The elongation temperature is 950 °C. When elongating and forming, the deformation amount of the first pass is 1.9%, the deformation amounts of the second and third passes are 12 - 14%, the deformation amount of the last pass is 1.7%. After the first elongation, the thickness of the slab is 580 mm. The feeding amount during elongation is 1 / 3 - 1 / 2 of the anvil width, and the downward pressing speed during elongation is 50 - 70 mm / s;

[0143] The second forging reduction: The forging temperature is 940°C. During forging forming, the reduction of the first pass is 1.7%, the reduction of the second and third passes is 12 - 15%, the reduction of the last pass is 1.2%. After the second forging reduction, the slab thickness is 420 mm. The feeding amount during forging reduction is 1 / 3 - 1 / 2 of the anvil width, and the downward pressing speed of forging reduction is 50 - 70 mm / s;

[0144] The third forging reduction: The forging temperature is 940°C. During forging forming, the reduction of the first pass is 2.4%, the reduction of the second and third passes is 11 - 13%, the reduction of the last pass is 1.6%. After the third forging reduction, the slab thickness is 315 mm. The feeding amount during forging reduction is 1 / 3 - 1 / 2 of the anvil width, and the downward pressing speed of forging reduction is 50 - 70 mm / s;

[0145] After longitudinal forging reduction, the blank is air-cooled. After sizing and facing, the dimensions of the forged blank are 300×1800×3300 mm.

[0146] Figure 7 This is the microstructural picture of the surface layer and the position at 1 / 2 thickness of the Ti80 titanium alloy forged blank prepared in Example 3 of the present invention. The structure is a uniform equiaxed structure, composed of a β matrix and ellipsoidal primary α phases. The content of the primary α phase is as high as 80%, and the grain size is 12 - 20 μm.

[0147] Example 4

[0148] The manufacturing method of a Ti80 titanium alloy forged blank with dimensions of 500×2200×2500 includes the following steps:

[0149] S1) Prepare a titanium alloy ingot

[0150] The diameter of the Ti80 titanium alloy ingot is Φ1060 mm, and the weight is 15 tons. The phase transformation point T β is 990°C;

[0151] S2) Perform cogging forging

[0152] Subject the Ti80 titanium alloy ingot obtained in step S1) to cogging forging through 5 passes of upsetting and reducing;

[0153] The first pass of upsetting and reducing: The holding temperature for upsetting and reducing is 1180°C. After reaching the temperature, hold for 15 h. Use a flat anvil to perform one upsetting deformation with a reduction of 45%. After upsetting, perform transverse forging reduction on the blank until it reaches an octagonal shape with a side length of 1200;

[0154] The second pass of upsetting and reducing: The holding temperature for upsetting and reducing is 1150°C. After reaching the temperature, hold for 4 h. Use a flat anvil to perform one upsetting deformation with a reduction of 45%. After upsetting, perform transverse forging reduction on the blank until it reaches an octagonal shape with a side length of 1200;

[0155] The 3rd upsetting and drawing: The upsetting and drawing holding temperature is 1130 °C. After reaching the temperature, hold for 4 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 45%. After upsetting, longitudinally draw the billet to an octagon with a size of 1200;

[0156] The 4th upsetting and drawing: The upsetting and drawing holding temperature is 1100 °C. After reaching the temperature, hold for 4 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 40%. After upsetting, longitudinally draw the billet to an octagon with a size of 1200;

[0157] The 5th upsetting and drawing: The upsetting and drawing holding temperature is 1080 °C. After reaching the temperature, hold for 4 h. Use a flat anvil to perform one upsetting deformation with a deformation amount of 30%. After upsetting, longitudinally draw the billet to an octagon with a size of 1200;

[0158] After forging, air-cool to room temperature to obtain the first forging blank;

[0159] S3) Intermediate forging

[0160] The obtained first forging blank is subjected to 4 upsetting and drawing operations;

[0161] The 1st upsetting and drawing: The upsetting and drawing temperature is 1030 °C, the holding time is 15 h, the upsetting deformation amount is 55%. After upsetting, longitudinally draw the billet to obtain a billet with a cross-sectional size of 1000×1200 mm;

[0162] The 2nd upsetting and drawing: After forging in the 1st fire, return to the furnace, the holding temperature is 1030 °C, hold for 3.5 hours. Use a flat anvil to perform one upsetting deformation with a deformation amount of 45%. After upsetting, longitudinally draw the billet to a billet with a cross-sectional size of 1000×1200 mm;

[0163] The 3rd upsetting and drawing: After forging in the 2nd fire, return to the furnace, the holding temperature is 1030 °C, hold for 3.5 hours. Use a flat anvil to perform one upsetting deformation with a deformation amount of 40%. After upsetting, longitudinally draw the billet to a billet with a cross-sectional size of 1000×1200 mm;

[0164] The 4th upsetting and drawing: After forging in the 2nd fire, return to the furnace, the holding temperature is 1030 °C, hold for 3.5 hours. Use a flat anvil to perform one upsetting deformation with a deformation amount of 35%. After upsetting, longitudinally draw the billet to a billet with a cross-sectional size of 1000×1200 mm;

[0165] After forging, air-cool the billet for 3 h to obtain the second forging blank;

[0166] S4) Finished forging

[0167] The obtained second forging blank is subjected to 3 longitudinal drawing operations;

[0168] The first forging pass of drawing out: The forging temperature of drawing out is 950°C. When forming by drawing out, the deformation amount of the first pass is 1.5%, that of the second and third passes is 10 - 12%, and that of the last pass is 1.3%. After the first forging pass of drawing out, the thickness of the slab is 800 mm. During the drawing out process, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the pressing down speed of drawing out is 50 - 70 mm / s;

[0169] The second forging pass of drawing out: The forging temperature of drawing out is 950°C. When forming by drawing out, the deformation amount of the first pass is 1.3%, that of the second and third passes is 8 - 11%, and that of the last pass is 0.8%. After the second forging pass of drawing out, the thickness of the slab is 600 mm. During the drawing out process, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the pressing down speed of drawing out is 50 - 70 mm / s;

[0170] The third forging pass of drawing out: The forging temperature of drawing out is 940°C. When forming by drawing out, the deformation amount of the first pass is 1.7%, that of the second and third passes is 7 - 8.5, and that of the last pass is 1%. After the third forging pass of drawing out, the thickness of the slab is 510 mm. During the drawing out process, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the pressing down speed of drawing out is 50 - 70 mm / s.

[0171] After longitudinal drawing out, the blank is air - cooled. After sizing and facing, the specifications of the forging blank are 500×2200×2500 mm. The microstructure of the surface layer and the position at 1 / 2 thickness of the forging blank is a uniform equiaxed structure, which consists of a β matrix and ellipsoidal primary α - phase. The content of the primary α - phase is as high as 75%, and the grain size is 12 - 20 μm.

[0172] Example 5

[0173] A manufacturing method for a Ti80 titanium alloy forging blank with specifications of 200×1900×4000 includes the following steps:

[0174] S1) Prepare a titanium alloy ingot

[0175] The diameter of the Ti80 titanium alloy ingot is Φ960 mm, the weight is 9 tons, and the phase transformation point T β is 990°C;

[0176] S2) Open - die forging

[0177] The Ti80 titanium alloy ingot obtained in step S1) is subjected to upset - drawing in 3 forging passes;

[0178] The first forging pass of upset - drawing: The holding temperature for upset - drawing is 1180°C. After reaching the temperature, hold for 12 h. Carry out one upsetting deformation with a flat anvil, and the deformation amount is 45%. After upsetting, draw out the blank transversely to 1000 octagon;

[0179] The second upsetting and drawing: The upsetting and drawing holding temperature is 1150°C. After reaching the temperature, hold for 4 hours. Use a flat anvil to perform one upsetting deformation with a deformation amount of 45%. After upsetting, draw the billet horizontally to a 1000-octagon;

[0180] The third upsetting and drawing: The upsetting and drawing holding temperature is 1130°C. After reaching the temperature, hold for 4 hours. Use a flat anvil to perform one upsetting deformation with a deformation amount of 40%. After upsetting, draw the billet horizontally to a 1000-octagon;

[0181] Air cool the forging to room temperature to obtain the first forging blank;

[0182] S3) Intermediate forging

[0183] Perform 3 upsetting and drawing operations on the obtained first forging blank;

[0184] The first upsetting and drawing: The upsetting and drawing temperature is 1030°C, the holding time is 14 hours, the upsetting deformation amount is 35%. After upsetting, draw the billet horizontally to obtain a billet with a cross-sectional size of 800×1400 mm;

[0185] The second upsetting and drawing: After the first forging, return to the furnace, the holding temperature is 1030°C, hold for 3.5 hours. Use a flat anvil to perform one upsetting deformation with a deformation amount of 35%. After upsetting, draw the billet horizontally to a billet with a cross-sectional size of 800×1400 mm;

[0186] The third upsetting and drawing: After the second forging, return to the furnace, the holding temperature is 1030°C, hold for 3.5 hours. Use a flat anvil to perform one upsetting deformation with a deformation amount of 30%. After upsetting, draw the billet horizontally to a billet with a cross-sectional size of 800×1400 mm;

[0187] After forging, air cool the billet for 3 hours to obtain the second forging blank;

[0188] S4) Finish forging

[0189] Perform 5 longitudinal drawing operations on the obtained second forging blank;

[0190] The first drawing: The drawing temperature is 950°C. When drawing and forming, the deformation amount of the first pass is 1.9%, the deformation amount of the second and third passes is 12 - 14%, the deformation amount of the last pass is 1.7%. After the first drawing, the thickness of the slab is 600 mm. The feeding amount during the drawing process is 1 / 3 - 1 / 2 of the anvil width, and the drawing downward pressure speed is 50 - 70 mm / s;

[0191] The second forging pass of stretching: The stretching temperature is 950 °C. During the stretching forming process, the deformation amount of the first pass is 1.7%, the deformation amounts of the second and third passes are 11-15%, the deformation amount of the last pass is 1.1%. After the second forging pass of stretching, the slab thickness is 450 mm. The feeding amount during the stretching process is 1 / 3-1 / 2 of the anvil width, and the downward pressing speed of stretching is 50-70 mm / s;

[0192] The third forging pass of stretching: The stretching temperature is 940 °C. During the stretching forming process, the deformation amount of the first pass is 2.2%, the deformation amounts of the second and third passes are 10-12%, the deformation amount of the last pass is 1.4%. After the third forging pass of stretching, the slab thickness is 350 mm. The feeding amount during the stretching process is 1 / 3-1 / 2 of the anvil width, and the downward pressing speed of stretching is 50-70 mm / s;

[0193] The fourth forging pass of stretching: The stretching temperature is 940 °C. During the stretching forming process, the deformation amount of the first pass is 1.4%, the deformation amounts of the second to third passes are 6-10%, the deformation amount of the last pass is 1.9%. After the fourth forging pass of stretching, the slab thickness is 265 mm. The feeding amount during the stretching process is 1 / 3-1 / 2 of the anvil width, and the downward pressing speed of stretching is 50-70 mm / s;

[0194] The fifth forging pass of stretching: The stretching temperature is 940 °C. During the stretching forming process, the deformation amount of the first pass is 1.9%, the deformation amounts of the second and third passes are 9-12%, the deformation amount of the last pass is 1.4%. After the fourth forging pass of stretching, the slab thickness is 207 mm. The feeding amount during the stretching process is 1 / 3-1 / 2 of the anvil width, and the downward pressing speed of stretching is 50-70 mm / s.

[0195] After longitudinal stretching, the billet is air-cooled. After sizing and facing, the dimensions of the forged billet are 200×1900×40000 mm. The microstructure on the surface layer and at the 1 / 2 thickness position of the forged billet is a uniform equiaxed structure, composed of a β matrix and ellipsoidal primary α phase. The content of the primary α phase is as high as 70%, and the grain size is 12-20 μm.

[0196] Comparative Example 1

[0197] A method for manufacturing a Ti80 titanium alloy forged billet with dimensions of 400×1850×2650 includes the following steps:

[0198] S1) Prepare a titanium alloy ingot

[0199] The diameter of the Ti80 titanium alloy ingot is Φ1060 mm, the weight is 12 tons, and the phase transformation point T β is 989 °C;

[0200] S2) Open-die forging

[0201] The Ti80 titanium alloy ingot obtained in step S1) is subjected to 4 forging passes of upsetting and stretching, and the process parameters are the same as those in Example 2;

[0202] The first forging blank is obtained by air cooling the forging to room temperature;

[0203] S3) Intermediate forging

[0204] The obtained first forging blank is subjected to upsetting and drawing for 4 heating passes, with the process parameters the same as those in Example 2. The difference is that the forging blank is air cooled to room temperature to obtain the second forging blank with a cross-sectional size of 650×1800 mm;

[0205] S4) Finish forging

[0206] The second forging blank is longitudinally drawn for 2 heating passes, with the process parameters the same as those in Example 3;

[0207] The first drawing pass: The drawing temperature is 950 °C. When forming by drawing, the deformation amount of the first pass is 1.5%, the deformation amounts of the second and third passes are 9 - 11%, and the deformation amount of the last pass is 1.2%. After the first drawing pass, the thickness of the slab is 500 mm. The feeding amount during the drawing process is 1 / 3 - 1 / 2 of the anvil width, and the drawing downward pressure speed is 50 - 70 mm / s;

[0208] The second drawing pass: The drawing temperature is 950 °C. When forming by drawing, the deformation amount of the first pass is 1%, the deformation amounts of the second and third passes are 8 - 11%, and the deformation amount of the last pass is 1.2%. After the second drawing pass, the thickness of the slab is 410 mm. The feeding amount during the drawing process is 1 / 3 - 1 / 2 of the anvil width, and the drawing downward pressure speed is 50 - 70 mm / s.

[0209] After sizing and milling the surface of the forging blank, the specifications are 400×1850×2650 mm. Figure 8 For the forging blank prepared in the comparative example, the lamellar structures at the surface layer and the 1 / 2 thickness position have not been completely broken, especially the structure at the 1 / 2 thickness position is extremely uneven.

[0210] Comparative example 2

[0211] A manufacturing method for a Ti80 titanium alloy forging blank with specifications of 300×1800×3300, comprising the following steps:

[0212] S1) Prepare a titanium alloy ingot

[0213] The diameter of the Ti80 titanium alloy ingot is Φ960 mm and the weight is 9.5 tons. The phase transformation point T β is 989 °C;

[0214] S2) Blooming forging

[0215] The Ti80 titanium alloy ingot obtained in step S1) is subjected to upsetting and drawing for 2 heating passes;

[0216] The 1st forging upsetting and drawing: The heating temperature is 1150 °C, and after reaching the temperature, it is held for 10 h. A flat anvil is used for one upsetting deformation with a deformation amount of 35%. After upsetting, the billet is longitudinally drawn to an octagon with a side length of 1000;

[0217] The 2nd forging upsetting and drawing: The heating temperature is 1130 °C, and after reaching the temperature, it is held for 2.5 h. A flat anvil is used for one upsetting deformation with a deformation amount of 35%. After upsetting, the billet is longitudinally drawn to an octagon with a side length of 1000;

[0218] After forging, it is air-cooled to room temperature to obtain the first forging blank;

[0219] S3) Intermediate forging

[0220] The obtained first forging blank is subjected to 2 times of upsetting and drawing;

[0221] The 1st forging upsetting and drawing: The heating temperature is 1020 °C, the holding time is 12 h, the upsetting deformation amount is 45%, and after upsetting, the billet is longitudinally drawn to obtain a billet with a cross-sectional size of 800×1200 mm;

[0222] The 2nd forging upsetting and drawing: After the first forging, it is reheated. The heating temperature is 1020 °C, and it is held for 2.5 hours. A flat anvil is used for one upsetting deformation with a deformation amount of 35%. After upsetting, the billet is longitudinally drawn to obtain a billet with a cross-sectional size of 800×1200 mm;

[0223] After forging, the billet is air-cooled for 2.5 h to obtain the second forging blank;

[0224] S4) Finish forging

[0225] The obtained second forging blank is subjected to 3 times of longitudinal drawing with the same process parameters as in Example 3;

[0226] After the forging blank is shaped and milled, its specifications are 300×1800×3300 mm. The microstructure analysis of the forging blank shows that the lamellae on the surface and at the 1 / 2 thickness are not completely broken, especially the microstructure at the 1 / 2 thickness is extremely uneven.

[0227] In Comparative Example 1, after intermediate forging, air cooling is used instead of air blast cooling. The reduction in drawing during finish forging is small, and the lamellar structure in the two-phase region cannot be fully broken; the properties of the forging blank obtained in Comparative Example 1 are uneven, and the strength and impact properties at the core position of the forging blank do not meet the requirements.

[0228] In Comparative Example 2, only 4 times of upsetting and drawing are carried out during the ingot forging and intermediate forging processes. The number of forging times is small, the total deformation amount is small, the as-forged structure cannot be fully broken, the β grains cannot be refined, and the uniformity of the billet structure cannot be improved. The strength and impact properties at the surface and core positions of the forging blank obtained in Comparative Example 2 do not meet the standard requirements.

[0229] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

[0230]

[0231]

[0232]

[0233]

[0234]

Claims

1. A manufacturing method of a super-large-sized Ti80 titanium alloy forging blank with a high impact toughness of over 9 tons, characterized in that, It includes the following steps: S1) Titanium alloy ingot The diameter of the Ti80 titanium alloy ingot is Φ960 - 1060 mm, and the weight is 9 - 17 tons; S2) Blooming forging The Ti80 titanium alloy ingot is subjected to upsetting and drawing for 2 - 5 heats. The upsetting and drawing heat preservation temperature is 1050 - 1180 °C. The upsetting and drawing method is flat anvil upsetting plus transverse drawing. The deformation amount per heat of upsetting and drawing is 30 - 55%. After the last heat of upsetting and drawing, it is air - cooled to obtain the first forging blank; S3) Intermediate forging The obtained first forging blank is upset and drawn for 3 - 4 heats at 20 - 50 °C above the phase transformation point. The upsetting and drawing method is flat anvil upsetting plus transverse drawing. The deformation amount per heat of upsetting and drawing is 30 - 55%. After the last heat of upsetting and drawing, it is air - cooled to obtain the second forging blank; S4) Finish forging The second forging blank is longitudinally drawn for 3 - 5 heats at 30 - 60 °C below the phase transformation point. The deformation amount per heat is 10 - 30%, and the total deformation amount ≥50%. It is air - cooled to obtain the titanium alloy forging blank; The thickness of the titanium alloy forging blank is 200 - 500 mm, the width is 1000 - 2500 mm, and the length is 2000 - 4000 mm; The microstructure of the titanium alloy forging blank is a uniform equiaxed structure, the content of primary α phase is 70 - 90%, and the short - side size is 12 - 20 μm.

2. The manufacturing method of a super-large-sized Ti80 titanium alloy forging blank with high impact toughness above 9 tons as described in claim 1, characterized in that, In step S1), the Ti80 titanium alloy ingot is obtained by at least three times of vacuum consumable melting.

3. The manufacturing method of the extra-large-sized Ti80 titanium alloy forging billet with high impact toughness and above 9 tons as described in claim 1 or 2, characterized in that, The mass percentages of each component in the Ti80 titanium alloy ingot are as follows: Al 6.0 - 6.3%, Nb 2.8 - 3.2%, Zr 1.9% - 2.1%, Mo 1.0% - 1.5%, 0 < Si ≤ 0.03%, 0 < Fe ≤ 0.25%, 0 < C ≤ 0.10%, 0 < N ≤ 0.05%, 0 < H ≤ 0.010%, O 0.06 - 0.10%, and the balance is Ti and unavoidable impurities.

4. The manufacturing method of the super-large-sized Ti80 titanium alloy forging billet with high impact toughness above 9 tons as claimed in claim 1, characterized in that, In step S2), the forging process uses temperature - decreasing upsetting and drawing. The heat preservation temperature for the first heat of upsetting and drawing is 1150 - 1180 °C. After each heat of upsetting and drawing, it is reheated for heat preservation, and the heat preservation temperature is 20 - 50 °C lower than the heat preservation temperature of the previous heat; the heat preservation time t=(0.15 - 0.5)×H, where t is in units of min and H is the thickness of the forging blank in units of mm.

5. The manufacturing method of the super-large-sized Ti80 titanium alloy forging billet with high impact toughness above 9 tons as described in claim 1 or 4, characterized in that, In step S2), the first forging blank is an octagonal blank.

6. The manufacturing method of the super-large-sized Ti80 titanium alloy forging billet with high impact toughness above 9 tons as described in claim 1, characterized in that, In step S3), the cross - section of the forging blank after each heat of upsetting and drawing is flat - square, and the ratio of its long side to short side is 1.2 - 1.

8.

7. The manufacturing method of the super-large-sized Ti80 titanium alloy forging blank with high impact toughness above 9 tons as described in claim 1, wherein In step S3), the heat preservation temperature after each heat of upsetting and drawing is the same, and the heat preservation time t=(0.15 - 0.5)×H, where t is in units of min and H is the thickness of the forging blank in units of mm.

8. The manufacturing method of a super-large-sized Ti80 titanium alloy forging blank with a weight of over 9 tons and high impact toughness as described in claim 1 or 4 or 6 or 7, characterized in that, In steps S2) and S3), during each heat of upsetting and drawing, the upsetting speed is 30 - 40 mm / s, and the upsetting process pauses 2 - 3 times, and each pause time is 3 - 8 seconds.

9. The manufacturing method of a super-large-sized Ti80 titanium alloy forging blank with a high impact toughness of over 9 tons as described in claim 1 or 6 or 7, characterized in that, In step 3), the air - cooling time ≥1 h.

10. The manufacturing method of the extra-large-sized Ti80 titanium alloy forging billet with high impact toughness above 9 tons as described in claim 1, characterized in that, In step 4), during each heat of longitudinal drawing, the deformation amount of the first pass is 1.5 - 4%, the deformation amount of the last pass is 0.5 - 2%, the deformation amount of the remaining passes is 5 - 15%, the feeding amount is 1 / 3 - 1 / 2 of the anvil width, and the drawing - down speed is 50 - 70 mm / s.

11. A Ti80 titanium alloy forging blank with extra-large specifications and high impact toughness manufactured by the method described in any one of claims 1 to 10, characterized in that after annealing, the tensile strength at each position of the titanium alloy forging blank is ≥840 MPa, the yield strength is ≥740 MPa, the elongation is ≥10%, and the impact energy is >60 J.

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