High-strength and high-toughness near-beta titanium alloy for large forgings and preparation method thereof

Abstract

The application provides a near-beta titanium alloy, which comprises the following components in percentage of raw material mass: Al: 2.5-3.5 %, V: 7-9 %, Cr: 0.8-1.8 %, Mo: 0.7-1.7 %, Fe: 0.5-1.0 %, and the balance of Ti and inevitable impurities. The new high-strength and high-toughness near-beta titanium alloy can reduce the decrease of plasticity and toughness when improving the strength index, fundamentally reduces the difficulty of alloy smelting control, has the advantages of high specific strength, good fracture toughness, good hardenability and good controllability of composition, and can be used for manufacturing large equipment in the fields of aerospace, weapons, petrochemical industry and the like.

Description

Technical Field

[0001] This invention belongs to the technical field of near-β titanium alloy preparation for large forgings, and relates to a near-β titanium alloy and its preparation method, particularly to a high-strength and high-toughness near-β titanium alloy for large forgings and its preparation method. Background Technology

[0002] Titanium and titanium alloys are widely used as load-bearing structural materials due to their high specific strength, low density, and good corrosion resistance. With the increasing demands for high strength and high fracture toughness in aerospace applications, and the growing trend towards larger and more integrated forgings, the development of high-strength and high-toughness titanium alloys with independent intellectual property rights is of great significance.

[0003] High-strength, high-toughness titanium alloys generally refer to titanium alloys with a tensile strength exceeding 1000 MPa and a fracture toughness exceeding 55 MPa·m1 / 2. Ti1023 alloy originated in the United States in the 1970s and is the most widely used high-strength, high-toughness near-β titanium alloy to date. Its emergence filled the gap in high-strength, high-fracture-toughness, and high-hardenability structural titanium alloys, and it can reduce weight by 20% when replacing TC4 titanium alloy. Ti1023 alloy was first practically applied in civilian and military aircraft such as the Boeing 757, A320, B-1B, and Mirage 2000. Its extensive use in aircraft such as the Boeing 777 passenger plane and the Super Lynx multi-purpose helicopter truly demonstrated its enormous potential in the aerospace industry. In the Boeing 777, it was used at three forging strength levels: 965 MPa, 1105 MPa, and 1190 MPa. Almost the entire main landing gear is made of Ti1023 alloy. The largest component in the landing gear is the bogie crossbeam, which is about 3 meters long and 340 mm in diameter. Its application on the Boeing 777 also includes the nose landing gear control mechanism and large flap rails. On the Super Lynx multi-purpose helicopter, it is mainly used for components such as the main rotor hub. Because the maximum takeoff weight of the helicopter increased from 3860 kg to 5585 kg, the strength of Ti6Al4V titanium alloy no longer met the requirements. Therefore, Ti1023 alloy replaced Ti6Al4V titanium alloy due to its higher strength, excellent high-cycle fatigue performance, and low stiffness.

[0004] However, Ti1023 alloy is highly sensitive to deformation rate and temperature, and due to its 2% Fe content, it is prone to β-spot formation during smelting due to compositional segregation. Furthermore, with the upgrading of equipment, greater tonnage load requirements have been introduced, leading not only to larger dimensions but also exacerbating the Fe segregation problem in this titanium alloy.

[0005] Therefore, in order to better meet design and usage requirements, how to design a high-strength and high-toughness near-β titanium alloy, whose alloy composition is no longer limited by size due to segregation, and whose comprehensive performance is superior to Ti1023 titanium alloy, in order to solve the urgent need for high-strength and high-toughness near-β titanium alloys for large load-bearing components in aerospace, has become one of the problems that many front-line researchers in the industry need to solve. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a near-β titanium alloy and its preparation method, particularly a high-strength and high-toughness near-β titanium alloy for large forgings and its preparation method. The near-β titanium alloy provided by the present invention has the advantages of high specific strength, good fracture toughness, good hardenability, and good composition controllability, and can be used to manufacture large equipment in aerospace, weaponry, petrochemical and other fields; moreover, the process is simple, highly controllable, and highly executable on site, making it more suitable for promotion and application in industrial-scale production.

[0007] This invention provides a near-β titanium alloy, which, by weight percentage of raw materials, comprises: Al: 2.5%~3.5%, V: 7%~9%, Cr: 0.8%~1.8%, Mo: 0.7%~1.7%, Fe: 0.5%~1.0%, with the balance being Ti and unavoidable impurities.

[0008] Preferably, the near-β titanium alloy is a high-strength and high-toughness near-β titanium alloy;

[0009] The tensile strength of the near-β titanium alloy is ≥1200MPa.

[0010] Preferably, the yield strength of the near-β titanium alloy is ≥1100MPa.

[0011] The elongation of the near-β titanium alloy is ≥10%.

[0012] Preferably, the reduction of area of ​​the near-β titanium alloy is ≥20%;

[0013] The fracture toughness of the near-β titanium alloy is ≥65 MPa·m1 / 2;

[0014] The near-β titanium alloy is a near-β titanium alloy used for large forgings.

[0015] This invention provides a method for preparing near-β titanium alloy as described in any of the above technical solutions, comprising the following steps:

[0016] 1) The titanium alloy raw material is melted three times by vacuum consumable arc melting to obtain an ingot;

[0017] 2) The ingots obtained in the above steps are forged to obtain bars, and then subjected to solution treatment and aging to obtain near-β titanium alloy.

[0018] Preferably, in the titanium alloy raw material, Al, V, Mo, and Fe are incorporated in the form of intermediate alloys, and Cr is incorporated in the form of pure metal.

[0019] The forging process includes high-low high-low forging.

[0020] Preferably, the forging process specifically includes nine hot forging processes;

[0021] In the forging process, the heating temperature of the first forging process is 1150℃, with two upsetting and two drawing operations, and the deformation is 35%~50%.

[0022] In the forging process, the heating temperature of the second forging process is 720~760℃, with one upsetting and one drawing, and the deformation is 35%~50%;

[0023] In the forging process, the heating temperature of the third forging process is 720~760℃, with one upsetting and one drawing, and the deformation is 35%~50%.

[0024] Preferably, in the forging process, the heating temperature of the fourth forging process is 900~930℃, with two upsetting and two drawing operations, and the deformation is 35%~50%;

[0025] In the forging process, the heating temperature of the fifth forging process is 720~750℃, with one upsetting and one drawing, and the deformation is 35%~50%;

[0026] In the forging process, the heating temperature of the sixth forging process is 720~750℃, with one upsetting and one drawing, and the deformation is 35%~50%.

[0027] Preferably, in the forging process, the heating temperature of the seventh forging process is 800~830℃, with two upsetting and two drawing operations, and the deformation is 35%~50%;

[0028] In the forging process, the heating temperature of the eighth forging process is 720~750℃, with one upsetting and one drawing, and the deformation is 35%~50%;

[0029] In the forging process, the heating temperature of the ninth forging process is 720~750℃, with one upsetting and one drawing, and the deformation is 35%~50%.

[0030] Preferably, the solution treatment temperature is 730~780℃;

[0031] The solution treatment time is 1-2 hours;

[0032] The aging treatment temperature is 520~600℃;

[0033] The time for the time-sensitive processing is 6 to 10 hours.

[0034] This invention provides a near-β titanium alloy, which, by weight percentage of raw materials, comprises: Al: 2.5%~3.5%, V: 7%~9%, Cr: 0.8%~1.8%, Mo: 0.7%~1.7%, Fe: 0.5%~1.0%, with the balance being Ti and unavoidable impurities. Compared with the prior art, this invention creatively designs a near-β titanium alloy with specific components and proportions. This is a high-strength and high-toughness near-β titanium alloy with advantages such as high specific strength, good fracture toughness, good hardenability, and good compositional controllability, and can be used to manufacture large equipment in aerospace, weaponry, petrochemical and other fields.

[0035] The high-strength and high-toughness near-β titanium alloy provided by this invention has a nominal chemical composition mainly of Ti-3Al-8V-1.5Cr-1Mo-1Fe. Compared with Ti1023 titanium alloy, this alloy reduces the amount of isomorphous β-stabilizing element V, replacing it with Mo; and reduces the amount of eutectoid β-stabilizing element Fe, replacing it with Cr. Therefore, while improving strength, the reduction in plasticity and toughness is less significant. Simultaneously, the reduction of easily segregated Fe fundamentally reduces the difficulty of alloy melting control.

[0036] This invention also provides a method for preparing high-strength and high-toughness near-β titanium alloys, employing a three-stage vacuum arc remelting process and a high-low-high-low forging process, which is beneficial for industrial production. Al, V, Mo, and Fe are incorporated as intermediate alloys, while Cr is incorporated as a pure metal. The raw materials are uniformly mixed and then prepared into electrodes, which are then melted in a vacuum arc remelting process to form forging ingots. These ingots are then forged into bars on a hydraulic press or high-speed forging mill.

[0037] Experimental results show that the high-strength and high-toughness near-β titanium alloy prepared by this invention has a room temperature tensile strength of b≥ 1200MPa, yield strength 0.2 ≥ 1100 MPa, elongation δ ≥ 10%, reduction of area ≥20%, fracture toughness K1C≥ 65 MPa·m1 / 2. Detailed Implementation

[0038] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.

[0039] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0040] There are no particular restrictions on the purity of any of the raw materials used in this invention. However, this invention preferably uses industrial-grade pure materials or materials with the purity requirements commonly used in the field of titanium alloy power generation.

[0041] All raw materials of this invention are conventional in the field, and each brand name and abbreviation is clear and distinct in its relevant application. Those skilled in the art can purchase them from the market or prepare them by conventional methods based on the brand name, abbreviation and corresponding application.

[0042] The processes used in this invention are all commonly referred to in the field. The specific steps and conventional parameters of each abbreviation are clear and well-defined in their respective fields. Those skilled in the art can implement them using conventional methods based on the abbreviations.

[0043] This invention provides a near-β titanium alloy, which, by weight percentage of raw materials, comprises: Al: 2.5%~3.5%, V: 7%~9%, Cr: 0.8%~1.8%, Mo: 0.7%~1.7%, Fe: 0.5%~1.0%, with the balance being Ti and unavoidable impurities.

[0044] In this invention, the amount of Al added is 2.5%~3.5%, or 2.7%~3.3%, or 2.9%~3.1%.

[0045] In this invention, the amount of V added is 7% to 9%, or 7.4% to 8.6%, or 7.8% to 8.2%.

[0046] In this invention, the amount of Cr added is 0.8%~1.8%, or 1.0%~1.6%, or 1.2%~1.4%.

[0047] In this invention, the amount of Mo added is 0.7% to 1.7%, or 0.9% to 1.5%, or 1.1% to 1.3%.

[0048] In this invention, the amount of Fe added is 0.5%~1.0%, or 0.6%~0.9%, or 0.7%~0.8%.

[0049] In this invention, the near-β titanium alloy is preferably a high-strength and high-toughness near-β titanium alloy.

[0050] In this invention, the tensile strength of the near-β titanium alloy is preferably ≥1200MPa, more preferably ≥1300MPa, and even more preferably ≥1400MPa.

[0051] In this invention, the yield strength of the near-β titanium alloy is preferably ≥1100MPa, more preferably ≥1200MPa, and even more preferably ≥1300MPa.

[0052] In this invention, the elongation of the near-β titanium alloy is preferably ≥10%, more preferably ≥11%, and even more preferably ≥12%.

[0053] In this invention, the reduction of area of ​​the near-β titanium alloy is preferably ≥20%, more preferably ≥22%, and even more preferably ≥25%.

[0054] In this invention, the fracture toughness of the near-β titanium alloy is preferably ≥65 MPa·m1 / 2, more preferably ≥66 MPa·m1 / 2, and even more preferably ≥67 MPa·m1 / 2.

[0055] In this invention, the near-β titanium alloy is preferably a near-β titanium alloy for large forgings. That is, this invention provides the application of near-β titanium alloys in the preparation of large forgings.

[0056] This invention provides a method for preparing near-β titanium alloy as described in any of the above technical solutions, comprising the following steps:

[0057] 1) The titanium alloy raw material is melted three times by vacuum consumable arc melting to obtain an ingot;

[0058] 2) The ingots obtained in the above steps are forged to obtain bars, and then subjected to solution treatment and aging to obtain near-β titanium alloy.

[0059] The present invention first involves melting titanium alloy raw materials three times using a vacuum consumable arc melting method to obtain ingots.

[0060] In this invention, the titanium alloy raw material preferably incorporates Al, V, Mo, and Fe in the form of intermediate alloys, and Cr in the form of pure metal.

[0061] In this invention, the forging preferably includes a high-low high-low forging process.

[0062] In this invention, the specific melting parameters in the triple vacuum consumable arc melting method can be adjusted according to the tonnage of the ingot. For example, a 3-ton ingot is used as an example:

[0063] For 3 tons per batch: the preferred smelting time is 1h~2h, current is 14000A~17000A, and voltage is 26~34V; more preferably, the smelting time is 1.2h~1.8h, current is 14500A~16500A, and voltage is 27~32V; even more preferably, the smelting time is 1.4h~1.6h, current is 15000A~16000A, and voltage is 29~32V.

[0064] 3-ton secondary melting: Preferred melting time is 3h~5h, current is 10000A~13000A, voltage is 26~34V; more preferred is melting time is 3.4h~4.6h, current is 10500A~12500A, voltage is 27~32V; even more preferred is melting time is 3.8h~4.2h, current is 11000A~12000A, voltage is 29~32V.

[0065] Three smelting cycles of 3 tons: Preferred smelting time is 6h~9h, current is 5000A~16000A, voltage is 26~34V; more preferred is smelting time is 6.5h~8.5h, current is 7000A~13000A, voltage is 27~32V; even more preferred is smelting time is 7h~8h, current is 9000A~11000A, voltage is 29~32V.

[0066] Finally, the ingots obtained from the above steps are forged to obtain bars, which are then subjected to solution treatment and aging to obtain near-β titanium alloys.

[0067] In this invention, the forging process preferably includes nine hot forging processes.

[0068] In this invention, the heating temperature of the first forging process is preferably 1150°C, with two upsetting and two drawing processes, and the deformation is preferably 35%~50%, more preferably 38%~47%, and even more preferably 41%~44%.

[0069] In this invention, the heating temperature of the second forging process is preferably 720~760℃, with one upsetting and one drawing, and the deformation is preferably 35%~50%. The heating temperature is more preferably 728~752℃, with one upsetting and one drawing, and the deformation is preferably more preferably 38%~47%. The heating temperature is more preferably 736~744℃, with one upsetting and one drawing, and the deformation is preferably more preferably 41%~44%.

[0070] In this invention, the heating temperature of the third forging process is preferably 720~760℃, with one upsetting and one drawing, and the deformation is preferably 35%~50%. The heating temperature is more preferably 728~752℃, with one upsetting and one drawing, and the deformation is preferably more preferably 38%~47%. The heating temperature is more preferably 736~744℃, with one upsetting and one drawing, and the deformation is preferably more preferably 41%~44%.

[0071] In this invention, the heating temperature of the fourth forging process is preferably 900~930℃, with two upsetting and two drawing processes, and the deformation is preferably 35%~50%. More preferably, the heating temperature is 905~925℃, with two upsetting and two drawing processes, and the deformation is preferably 38%~47%. More preferably, the heating temperature is 910~920℃, with two upsetting and two drawing processes, and the deformation is preferably 41%~44%.

[0072] In this invention, the heating temperature of the fifth forging process is preferably 720~750℃, with one upsetting and one drawing, and the deformation is preferably 35%~50%. More preferably, the heating temperature is 725~745℃, with one upsetting and one drawing, and the deformation is preferably 38%~47%. More preferably, the heating temperature is 730~740℃, with one upsetting and one drawing, and the deformation is preferably 41%~44%.

[0073] In this invention, the heating temperature of the sixth forging process is preferably 720~750℃, with one upsetting and one drawing, and the deformation is preferably 35%~50%. More preferably, the heating temperature is 725~745℃, with one upsetting and one drawing, and the deformation is preferably 38%~47%. More preferably, the heating temperature is 730~740℃, with one upsetting and one drawing, and the deformation is preferably 41%~44%.

[0074] In this invention, the heating temperature of the seventh forging process is preferably 800~830℃, with two upsetting and two drawing operations, and the deformation is preferably 35%~50%. More preferably, the heating temperature is 805~825℃, with two upsetting and two drawing operations, and the deformation is preferably 38%~47%. More preferably, the heating temperature is 810~820℃, with two upsetting and two drawing operations, and the deformation is preferably 41%~44%.

[0075] In this invention, the heating temperature of the eighth forging process is preferably 720~750℃, with one upsetting and one drawing, and the deformation is preferably 35%~50%. More preferably, the heating temperature is 725~745℃, with one upsetting and one drawing, and the deformation is preferably 38%~47%. More preferably, the heating temperature is 730~740℃, with one upsetting and one drawing, and the deformation is preferably 41%~44%.

[0076] In this invention, the heating temperature of the ninth forging process is preferably 720~750℃, with one upsetting and one drawing, and the deformation is preferably 35%~50%. More preferably, the heating temperature is 725~745℃, with one upsetting and one drawing, and the deformation is preferably 38%~47%. More preferably, the heating temperature is 730~740℃, with one upsetting and one drawing, and the deformation is preferably 41%~44%.

[0077] In this invention, the solution aging process is preferably carried out at 730℃~780℃ for 1h~2h, followed by water cooling + 520℃~600℃ for 6h~10h, and then air cooling.

[0078] In this invention, the solution treatment temperature is preferably 730~780℃, more preferably 740~770℃, and even more preferably 750~760℃.

[0079] In this invention, the solution treatment time is preferably 1-2 hours, more preferably 1.2-1.8 hours, and even more preferably 1.4-1.6 hours.

[0080] In this invention, the aging treatment temperature is preferably 520~600℃, more preferably 535~585℃, and even more preferably 550~570℃.

[0081] In this invention, the aging process is preferably 6 to 10 hours, more preferably 6.8 to 9.2 hours, and even more preferably 7.6 to 8.4 hours.

[0082] This invention aims to complete and refine the overall technical solution, and to better improve the tensile strength, yield strength, elongation, reduction of area, and fracture toughness of near-β titanium alloys. Specifically, the high-strength, high-toughness near-β titanium alloy for large forgings may include the following:

[0083] The near-β titanium alloy provided by this invention has the following weight percentage composition of each metal element: Al 2.5-3.5%, V 7-9%, Cr 0.8-1.8%, Mo 0.7-1.7%, Fe 0.5-1.0%, with the balance being Ti and unavoidable impurities.

[0084] The preparation method provided by this invention uses raw materials such as AlV, AlMo, FeV master alloy, pure Cr and sponge titanium, and mixes them according to the required weight percentages. The mixture is then melted three times in a vacuum arc furnace to obtain an ingot. The ingot is forged into a bar, and the bar is subjected to solution treatment and aging to obtain a near-β titanium alloy.

[0085] The present invention also provides the application of the near-β titanium alloy or the preparation method of the near-β titanium alloy described in any one of the above technical solutions in large forgings.

[0086] The present invention provides a high-strength, high-toughness near-β titanium alloy for large forgings and its preparation method. The near-β titanium alloy designed in this invention, with specific components and proportions, is a high-strength, high-toughness near-β titanium alloy with advantages such as high specific strength, good fracture toughness, good hardenability, and good compositional controllability. It can be used to manufacture large equipment in aerospace, weaponry, and petrochemical fields.

[0087] The high-strength and high-toughness near-β titanium alloy provided by this invention has a nominal chemical composition mainly of Ti-3Al-8V-1.5Cr-1Mo-1Fe. Compared with Ti1023 titanium alloy, this alloy reduces the amount of isomorphous β-stabilizing element V, replacing it with Mo; and reduces the amount of eutectoid β-stabilizing element Fe, replacing it with Cr. Therefore, while improving strength, the reduction in plasticity and toughness is less significant. Simultaneously, the reduction of easily segregated Fe fundamentally reduces the difficulty of alloy melting control.

[0088] This invention also provides a method for preparing high-strength and high-toughness near-β titanium alloys, employing a three-stage vacuum arc remelting process and a high-low-high-low forging process, which is beneficial for industrial production. Al, V, Mo, and Fe are incorporated as intermediate alloys, while Cr is incorporated as a pure metal. The raw materials are uniformly mixed and then prepared into electrodes, which are then melted in a vacuum arc remelting process to form forging ingots. These ingots are then forged into bars on a hydraulic press or high-speed forging mill.

[0089] Experimental results show that the high-strength and high-toughness near-β titanium alloy prepared by this invention has a room temperature tensile strength of b≥ 1200MPa, yield strength 0.2 ≥ 1100 MPa, elongation δ ≥ 10%, reduction of area ≥20%, fracture toughness K1C≥ 65 MPa·m1 / 2.

[0090] To further illustrate the present invention, the following detailed description of a near-β titanium alloy and its preparation method provided by the present invention is provided in conjunction with embodiments. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given only to further illustrate the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0091] Example 1

[0092] Using raw materials such as AlV65, AlMo60, FeV80 master alloys, pure Cr, and sponge titanium, the raw materials were formulated according to the following weight percentages: Al: 2.5%, V: 7%, Cr: 0.8%, Mo: 0.7%, Fe: 0.5%, and Ti as the balance. The materials were melted three times in a vacuum arc furnace to obtain 3-ton ingots. The ingots were forged into φ300mm bars. The bars were subjected to solution treatment and aging before performance testing. The data are shown in Tables 1 and 2.

[0093] The heating temperature of the first forging process is 1150℃, with two upsetting and two drawing operations, and the deformation is 41%.

[0094] The heating temperature of the second forging process is 760℃, with one upsetting and one drawing, and the deformation is 41%.

[0095] The heating temperature of the third forging process is 760℃, with one upsetting and one drawing, and the deformation is 41%.

[0096] The heating temperature of the fourth forging process is 930℃, with two upsetting and two drawing operations, and the deformation is 41%.

[0097] The heating temperature of the fifth forging process is 750℃, with one upsetting and one drawing, and the deformation is 41%.

[0098] The heating temperature of the sixth forging process is 750℃, with one upsetting and one drawing, and the deformation is 41%.

[0099] The heating temperature of the seventh forging process is 830℃, with two upsetting and two drawing operations, and the deformation is 41%.

[0100] The heating temperature of the eighth forging process is 750℃, with one upsetting and one drawing, and the deformation is 41%.

[0101] The heating temperature of the ninth forging process is 750℃, with one upsetting and one drawing, and the deformation is 41%.

[0102] The solution aging process was carried out at 750℃ for 1.5 hours, followed by water cooling at 560℃ for 8 hours, and then air cooling.

[0103] Table 1. Room temperature tensile properties of bars from Example 1

[0104]

[0105] Table 2. Fracture properties of bars in Example 1

[0106]

[0107] Example 2

[0108] Using raw materials such as AlV65, AlMo60, FeV80 master alloys, pure Cr, and sponge titanium, the raw materials were formulated according to the following weight percentages: Al: 3.5%, V: 9%, Cr: 1.8%, Mo: 1.7%, Fe: 1.0%, and Ti as the balance. The materials were melted three times in a vacuum arc furnace to obtain 3-ton ingots. The ingots were forged into φ300mm bars. The bars were subjected to solution treatment and aging before performance testing. The data are shown in Tables 3 and 4.

[0109] The heating temperature of the first forging process is 1150℃, with two upsetting and two drawing operations, and the deformation is 40%.

[0110] The heating temperature of the second forging process is 760℃, with one upsetting and one drawing, and the deformation is 40%.

[0111] The heating temperature of the third forging process is 760℃, with one upsetting and one drawing, and the deformation is 40%.

[0112] The heating temperature of the fourth forging process is 930℃, with two upsetting and two drawing operations, and the deformation is 42%.

[0113] The fifth forging process involves heating at 750℃, with one upsetting and one drawing, resulting in a deformation of 42%.

[0114] The heating temperature of the sixth forging process is 750℃, with one upsetting and one drawing, and the deformation is 42%.

[0115] The heating temperature of the seventh forging process is 830℃, with two upsetting and two drawing operations, and the deformation is 42%.

[0116] The heating temperature of the eighth forging process is 750℃, with one upsetting and one drawing, and the deformation is 42%.

[0117] The heating temperature of the ninth forging process is 750℃, with one upsetting and one drawing, and the deformation is 42%.

[0118] The solution aging process was carried out at 760℃ for 1.5 hours, followed by water cooling + 560℃ for 8 hours, and then air cooling.

[0119] Table 3 Room temperature tensile properties of bars from Example 2

[0120]

[0121] Table 4. Fracture properties of bars in Example 2

[0122]

[0123] Example 3

[0124] Using AlV65, AlMo60, FeV80 master alloys, pure Cr, and sponge titanium as raw materials, the raw materials were proportioned according to the following weight percentages: Al: 3%, V: 8%, Cr: 1.5%, Mo: 1.0%, Fe: 1.0%, and Ti as the balance. The mixture was then melted three times in a vacuum arc remelting furnace to obtain a 3-ton ingot. The ingot was forged into φ300mm bars. The bars were then subjected to solution treatment and aging before performance testing. The data are shown in Tables 5 and 6.

[0125] The heating temperature of the first forging process is 1150℃, with two upsetting and two drawing operations, and the deformation is 42%.

[0126] The heating temperature of the second forging process is 760℃, with one upsetting and one drawing, and the deformation is 42%.

[0127] The heating temperature of the third forging process is 760℃, with one upsetting and one drawing, and the deformation is 42%.

[0128] The heating temperature of the fourth forging process is 930℃, with two upsetting and two drawing operations, and the deformation is 42%.

[0129] The fifth forging process involves heating at 750℃, with one upsetting and one drawing, resulting in a deformation of 42%.

[0130] The heating temperature of the sixth forging process is 750℃, with one upsetting and one drawing, and the deformation is 42%.

[0131] The heating temperature of the seventh forging process is 830℃, with two upsetting and two drawing operations, and the deformation is 44%.

[0132] The heating temperature of the eighth forging process is 750℃, with one upsetting and one drawing, and the deformation is 44%.

[0133] The heating temperature of the ninth forging process is 750℃, with one upsetting and one drawing, and the deformation is 44%.

[0134] The solution aging process was carried out at 740℃ for 1-2 hours, followed by water cooling at 580℃ for 8 hours, and then air cooling.

[0135] Table 5. Room temperature tensile properties of bars from Example 3

[0136]

[0137] Table 6. Fracture properties of bars in Example 3

[0138]

[0139] The foregoing provides a detailed description of a high-strength, high-toughness near-β titanium alloy for large forgings and its preparation method. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to the invention without departing from the principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the wording of the claims, or if they include equivalent structural elements that are not substantially different from the wording of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for producing a near β titanium alloy, characterized by, Includes the following steps: 1) The titanium alloy raw material is melted three times by vacuum consumable arc melting to obtain an ingot; 2) The ingots obtained in the above steps are forged to obtain bars, and then subjected to solution treatment and aging to obtain near-β titanium alloy; The forging process specifically includes nine hot forging processes; In the forging process, the heating temperature of the first forging process is 1150℃, with two upsetting and two drawing operations, and the deformation is 35%~50%. In the forging process, the heating temperature of the second forging process is 720~760℃, with one upsetting and one drawing, and the deformation is 35%~50%; In the forging process, the heating temperature of the third forging process is 720~760℃, with one upsetting and one drawing, and the deformation is 35%~50%; In the forging process, the heating temperature of the fourth forging process is 900~930℃, with two upsetting and two drawing operations, and the deformation is 35%~50%. In the forging process, the heating temperature of the fifth forging process is 720~750℃, with one upsetting and one drawing, and the deformation is 35%~50%; In the forging process, the heating temperature of the sixth forging process is 720~750℃, with one upsetting and one drawing, and the deformation is 35%~50%; In the forging process, the heating temperature of the seventh forging process is 800~830℃, with two upsetting and two drawing operations, and the deformation is 35%~50%. In the forging process, the heating temperature of the eighth forging process is 720~750℃, with one upsetting and one drawing, and the deformation is 35%~50%; In the forging process, the heating temperature of the ninth forging process is 720~750℃, with one upsetting and one drawing, and the deformation is 35%~50%; The near-β titanium alloy, by weight percentage of raw materials, comprises: Al: 2.5%~3.5%, V: 7%~9%, Cr: 0.8%~1.8%, Mo: 0.7%~1.7%, Fe: 0.5%~1.0%, with the balance being Ti and unavoidable impurities.

2. The production method according to claim 1, characterized by, The near-β titanium alloy is a high-strength and high-toughness near-β titanium alloy; The tensile strength of the near-β titanium alloy is ≥1200MPa.

3. The preparation method according to claim 1, characterized in that, The yield strength of the near-β titanium alloy is ≥1100MPa.

4. The preparation method according to claim 1, characterized in that, The elongation of the near-β titanium alloy is ≥10%.

5. The preparation method according to claim 1, characterized in that, The near-β titanium alloy has a reduction of area of ​​≥20%.

6. The method of claim 1, wherein, The fracture toughness of the near-β titanium alloy is ≥65MPa·m1 / 2; The near-β titanium alloy is a near-β titanium alloy used for large forgings.

7. The preparation method according to claim 1, characterized in that, In the titanium alloy raw material, Al, V, Mo, and Fe are incorporated in the form of intermediate alloys, while Cr is incorporated in the form of pure metal.

8. The method of claim 1, wherein, The solution treatment temperature is 730~780℃; The solution treatment time is 1-2 hours.

9. The method of claim 1, wherein, The aging treatment temperature is 520~600℃; The time for the time-sensitive processing is 6 to 10 hours.

Images