A forging method for improving the properties of TC16 titanium alloy

Abstract

The present invention relates to the field of metallurgical technology, and particularly relates to a forging and forming method for improving the performance of TC16 titanium alloy, including an ingot blooming process, a forging process, and a forming process. The temperature of ingot blooming forging is reduced from 1150 - 1160 °C to 1060 - 1075 °C, and the reduction amount of the cross-sectional diameter is reduced from 190 - 200 mm per heat to 90 - 100 mm per heat; the temperature of forging is reduced from 1000 - 1015 °C to 950 - 965 °C, and the reduction amount of the cross-sectional diameter is reduced from 70 - 80 mm per heat to 50 - 60 mm per heat; the temperature of forming forging is reduced from β - 30 °C to β - 45 °C, and the reduction amount of the cross-sectional diameter is reduced from 50 - 60 mm per heat to 30 - 35 mm per heat; chamfering is carried out during the forging process of the titanium alloy blank. This method solves the problems of the existing forging methods, such as long forging cycle, many heats, and uneven deformation.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and particularly relates to a forging and forming method for improving the performance of TC16 titanium alloy. Background Art

[0002] TC16 titanium alloy is a type of titanium alloy material designed and developed on the basis of BT16 titanium alloy, with high strength, high plasticity, fatigue resistance, good weldability and hardenability. It is widely used in fields such as aviation, aerospace, chemical industry, metallurgy, shipbuilding, national defense, medical treatment, oil field and automobile, and is one of the most ideal materials for manufacturing fasteners. TC16 titanium alloy is a martensitic α+β two-phase titanium alloy with a nominal composition of Ti-3Al-5Mo-4.5V. Its composition contains α-stabilizing element Al and isomorphous β-stabilizing elements Mo and V; the chemical composition includes Ti, Al, Mo, V, Fe, Si, Zr, O, N, H.

[0003] TC16 titanium alloy can be not only hot forged but also cold forged. TC16 titanium alloy is usually strengthened by cold working. Conventional cold working methods mainly involve melting, forging, upsetting, and drawing on a hammer to form the required bars. However, this method has defects such as long cycle, many heating times, and uneven deformation, and the required related properties are difficult to meet the requirements of the forgings for the required products. In addition, before the finished cold working, it is also necessary to use forging equipment to perform homogenizing forging on the blank to meet the requirements of the products. In order to perform homogenizing forming on the blank, a certain heat treatment method is usually required to optimize the mechanical properties and microstructure of TC16 titanium alloy bars. After the TC16 titanium alloy is heat treated, the microstructure of the titanium alloy wire undergoes a large deformation. Usually, the microstructure of the bar becomes smaller, making this type of alloy have high plasticity and relatively low strength.

[0004] Currently, for the forging and forming method, the general method is to use the forging improvement method to complete the forging production of the uniformity of titanium alloy. For the forging improvement method, the method of "upsetting-drawing" is usually used to complete the uniform refinement of the titanium alloy structure. However, such a forging method is likely to result in a long forging cycle and many heating times. For example, usually at least 5 heating times of forging improvement are required, and it is also prone to problems such as uneven deformation. Eventually, the physical and chemical results of the forgings cannot meet the required requirements, resulting in a high rejection rate.

[0005] Based on this, the present invention improves the existing forging method to match the corresponding forging temperature, and can uniformly refine the titanium alloy structure while reducing the forging heating times to meet the processing requirements. Summary of the Invention

[0006] In order to solve the problems that the existing forging methods are prone to cause long forging cycles, multiple heating times, and uneven deformation, the purpose of the present invention is to provide a forging and forming method for improving the properties of TC16 titanium alloy.

[0007] To achieve the above object, the technical solution of the present invention is as follows.

[0008] A forging and forming method for improving the properties of TC16 titanium alloy, characterized by comprising:

[0009] The blanking process, in which the titanium alloy blank is subjected to blanking forging for n1 heating times, and as the number of blanking forging heating times increases, the temperature of the blanking forging decreases from 1150 - 1160 °C to 1060 - 1075 °C, and the reduction amount of the cross-sectional diameter decreases from 190 - 200 mm / heating time to 90 - 100 mm / heating time;

[0010] The forging modification process, in which the titanium alloy blank is subjected to forging modification for n2 heating times, and as the number of forging modification heating times increases, the temperature of the forging modification decreases from 1000 - 1015 °C to 950 - 965 °C, and the reduction amount of the cross-sectional diameter decreases from 70 - 80 mm / heating time to 50 - 60 mm / heating time;

[0011] The forming process, in which the titanium alloy blank is subjected to forming forging for n3 heating times, and as the number of forming forging heating times increases, the temperature of the forming forging decreases from β - 30 °C to β - 45 °C, and the reduction amount of the cross-sectional diameter decreases from 50 - 60 mm / heating time to 30 - 35 mm / heating time;

[0012] n1 = 3 - 5, n2 = 3 - 5, n3 = 3 - 5, and β is the phase transformation point temperature of the titanium alloy blank;

[0013] As the number of forging heating times increases, chamfering is carried out during the forging process of the titanium alloy blank.

[0014] In some preferred embodiments, as the number of forging heating times increases, the cross-sectional size of the titanium alloy blank decreases in sequence.

[0015] In some preferred embodiments, as the number of forging heating times increases, the cross-sectional shape of the titanium alloy blank changes in accordance with square, hexagonal, and octagonal shapes;

[0016] And the cross-sectional shape of the n3 - th forming forging is square.

[0017] In some preferred embodiments, when n1 = 2, n2 = 2, and n3 = 4, as the number of forging heating times increases, the cross-sectional shape of the titanium alloy blank is square, hexagonal, octagonal, hexagonal, square, hexagonal, square, square.

[0018] In some preferred embodiments, the temperature of the blanking forging decreases at a rate of 85 - 100 °C / heating time;

[0019] The temperature of forging reduction decreases at a rate of 50 - 65 °C per heat treatment;

[0020] The temperature of forming forging decreases at a rate of 5 - 10 °C per heat treatment.

[0021] In some preferred embodiments, the titanium alloy blank is a TC16 titanium alloy blank; the phase transformation point temperature of the titanium alloy blank is β = 835 - 885 °C.

[0022] In some preferred embodiments, with the increase in the number of cogging forging heat treatments, the deformation amount of cogging forging decreases from 60 - 55% to 55 - 50%;

[0023] With the increase in the number of forging reduction heat treatments, the deformation amount of forging reduction decreases from 50 - 45% to 45 - 40%;

[0024] With the increase in the number of forming forging heat treatments, the deformation amount of forming forging increases from 45 - 50% to 60 - 65%.

[0025] In some preferred embodiments, with the increase in the number of cogging forging heat treatments, the hammering speed of cogging forging decreases from 55 - 50 mm / s to 50 - 45 mm / s;

[0026] With the increase in the number of forging reduction heat treatments, the hammering speed of forging reduction decreases from 45 - 40 mm / s to 40 - 35 mm / s;

[0027] With the increase in the number of forming forging heat treatments, the hammering speed of forming forging increases from 35 - 40 mm / s to 50 - 55 mm / s.

[0028] In some preferred embodiments, after the forming process, there is also a heat treatment regime, and the heat treatment regime is at least one of annealing heat treatment, stress relief annealing, solution heat treatment, and aging heat treatment.

[0029] In some preferred embodiments, the annealing heat treatment is carried out at 770 - 779 °C for 15 - 25 h, and then cooled to 530 - 580 °C and then taken out of the furnace for air cooling;

[0030] The stress relief annealing treatment is carried out at 530 - 670 °C for 0.5 - 4.5 h, and then taken out of the furnace for air cooling;

[0031] The solution heat treatment is carried out at 770 - 850 °C for 1.5 - 2.5 h, and then taken out of the furnace for water quenching;

[0032] The aging heat treatment is carried out at 450 °C - 600 °C for 5.5 - 11.5 h, and then taken out of the furnace for air cooling.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention uses a matching forging temperature under different forging processes to enable the materials used for forging to meet the required forging requirements. While shortening the forging cycle and reducing the heat treatment production cost, it improves the deformation uniformity and reduces the difficulty of production operations.

[0035] 2. The present invention uses different heating temperatures to match different forging methods, and the diameter of the blank is generally forged by the method of decreasing cross-section. This is mainly because when controlling the forging temperature, in the case where the internal grain refinement of the forging is not fully improved during high-temperature deformation, producing according to the decreasing heating temperature method will ultimately result in local coarse grains or uneven organization, leading to out-of-spec mechanical property indicators, unqualified physical and chemical results, scrapping, long production cycles, high energy consumption, and other defects.

[0036] 3. In order to improve production efficiency and reduce waste products, the present invention effectively improves the conventional forging method by optimizing the production process of forging temperature and forging technical conditions. The present invention mainly uses the method of decreasing cross-section and the method of changing cross-section shape, that is, the "square - hexagon - octagon" method, to effectively improve the original grain structure during blooming, improve the qualified rate of forging production and the qualified rate of related required properties, and at the same time can well control the mutual matching relationship of the deformation technical parameters during forging of forgings.

[0037] 4. By comprehensively considering the heating temperature required for the forging of bars and the matching process of forging methods, and simultaneously considering factors such as the amount of deformation and the hammering frequency, the present invention can improve the tissue uniformity of Ti-3Al-5Mo-4.5V titanium alloy bars by uniformly forging the blank. Description of the Drawings

[0038] Figure 1 It is a macrostructure diagram of the cross-section of the 1 / 2 section of the test sample for Example 1. Among them, (A) is the macrostructure diagram of the positive cross-section of the 1 / 2 section of the test sample for Example 1; (B) is the macrostructure diagram of the reverse cross-section of the 1 / 2 section of the test sample for Example 1.

[0039] Figure 2 It is a macrostructure diagram of the cross-section of the 1 / 4 section of the test sample for Example 1. Among them, (A) is the macrostructure diagram of the positive cross-section of the 1 / 4 section of the test sample for Example 1; (B) is the macrostructure diagram of the reverse cross-section of the 1 / 4 section of the test sample for Example 1.

[0040] Figure 3 It is a high-magnification microstructure diagram of the front cross-section of the titanium alloy bar for Example 1.

[0041] Figure 4 It is a high-magnification microstructure diagram of the front cross-section of the titanium alloy bar for Comparative Example 1. Detailed Embodiments

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0044] TC16 titanium alloy can not only be hot forged, but also cold forged. TC16 titanium alloy is usually strengthened by cold working. Conventional cold working methods mainly include melting, forging, and drawing on a hammer to form the required bars. However, this method has defects such as long cycle, many heating times, and uneven deformation, and its required related properties are difficult to meet the requirements of the forgings for the materials. In addition, before the finished cold working, it is also necessary to use forging equipment to perform homogenization forging on the blank to meet the requirements of the product. In order to perform homogenization forming on the blank, a certain heat treatment method is usually required to optimize the mechanical properties and microstructure of the TC16 titanium alloy bar. After the TC16 titanium alloy is heat treated, the microstructure of the titanium alloy wire undergoes a large deformation. Usually, the microstructure of the bar becomes smaller, making this type of alloy have high plasticity and relatively low strength.

[0045] Currently, for the forging and forming method, generally the remelting method is used to complete the remelting production of the titanium alloy uniformity. For the remelting method, usually the "upsetting-drawing" method is used to complete the uniform refinement of the titanium alloy structure. However, such a forging method is likely to result in a long forging cycle and many heating times. For example, usually at least 5 heating times of remelting forging are required, and it is also prone to problems such as uneven deformation. Eventually, the physical and chemical results of the forgings cannot meet the required requirements, resulting in a high rejection rate.

[0046] In order to solve the above problems, the present invention adopts a new matching method for the forging heating temperature and forging method to complete the hammer forging of Ti-3Al-5Mo-4.5V titanium alloy. Under the condition of reducing the forging heating times, it can make the titanium alloy structure uniformly refined, and finally meet the required related performance requirements. The required internal structure is: the requirement of martensitic α+β two-phase structure.

[0047] First, the forging method of Ti-3Al-5Mo-4.5V titanium alloy on the hammer is as follows: different drawing methods are adopted at different temperatures to complete. The commonly used forging methods at present are: ingot forging, remelting forging, and forming forging; and the forging method of "upsetting + drawing" is adopted during the forging process, which easily leads to a long forging cycle and many heating times. Based on this, for Ti-3Al-5Mo-4.5V titanium alloy materials, in order to meet the requirements of this material, different temperatures need to be adopted under different forging methods to complete the corresponding forging processes.

[0048] The original blank usually uses smelted ingots as Ingots with a diameter: From the perspective of energy utilization rate and economic practicality, the most direct method is Forging ingots with a diameter into the required blank specifications. Usually, the blank specifications required for cold processing of Ti-3Al-5Mo-4.5V titanium alloy parts are That is to say, before cold processing, it is necessary to Ingots with a diameter are processed into blanks required for cold processing of TC16 titanium alloy parts of.

[0049] Therefore, higher requirements are put forward for forging. In order to shorten the cycle, reduce the number of hot processing heating times, improve the deformation uniformity, and reduce the production operation difficulty, this scheme proposes a hot forming production scheme, specifically: different forging methods are adopted at different temperatures to complete.

[0050] For Ti-3Al-5Mo-4.5V titanium alloy forgings produced by forging equipment, different forging methods are matched with different heating temperatures, and the overall cross-section reduction method is adopted for forging the blank diameter; that is, the diameter gradually becomes smaller; the length becomes larger. Different forging methods are adopted for forging methods at different heating temperatures to complete the production of the blank before cold processing.

[0051] A method for cogging forging of Ti-3Al-5Mo-4.5V titanium alloy billets using the cross-section decreasing method. This is mainly because when controlling the forging temperature, in the case where the internal structure grain refinement of the forgings is not fully improved during high-temperature deformation, production is carried out in the way of decreasing heating temperature. Eventually, there are local coarse grains or uneven structures, resulting in out-of-tolerance mechanical property indicators, unqualified physical and chemical results, scrapping, long production cycles, high energy consumption and other defects. In order to improve production efficiency and reduce waste products, the present invention fully utilizes the optimized production process of forging temperature and forging technical conditions to effectively improve the conventional forging method. By using the cross-section decreasing method and the way of changing cross-section shapes, that is, the "square - hexagon - octagon" method, it can effectively improve the original grain structure during cogging, improve the qualified rate of forging production and related required performance qualified rate, and at the same time can well control the mutual matching relationship of deformation technical parameters during forging of forgings.

[0052] In summary, by comprehensively considering the heating temperature required for red forging of bars and the matching process of forging methods, and at the same time comprehensively considering factors such as the deformation amount and the hammering frequency, the present invention can improve the tissue uniformity of Ti-3Al-5Mo-4.5V titanium alloy bars by evenly forging the billets using a 5000T press forging equipment.

[0053] The forging forming method for improving the performance of TC16 titanium alloy is specifically described as follows.

[0054] A forging forming method for improving the performance of TC16 titanium alloy, characterized by including:

[0055] Cogging process: cogging forge the titanium alloy billet for n1 heats. As the number of cogging forging heats increases, the forging temperature decreases from 1150 - 1160 °C to 1060 - 1075 °C, and the reduction amount of the cross-section diameter decreases from 190 - 200 mm / heat to 90 - 100 mm / heat;

[0056] Red forging process: red forge the titanium alloy billet for n2 heats. As the number of red forging heats increases, the forging temperature decreases from 1000 - 1015 °C to 950 - 965 °C, and the reduction amount of the cross-section diameter decreases from 70 - 80 mm / heat to 50 - 60 mm / heat;

[0057] Forming process: form forge the titanium alloy billet for n3 heats. As the number of form forging heats increases, the forging temperature decreases from β - 30 °C to β - 45 °C, and the reduction amount of the cross-section diameter decreases from 50 - 60 mm / heat to 30 - 35 mm / heat;

[0058] n1 = 3 - 5, n2 = 3 - 5, n3 = 3 - 5, and β is the phase transformation point temperature of the titanium alloy billet;

[0059] As the number of forging heats increases, chamfering is performed during the forging process of the titanium alloy billet.

[0060] In a preferred embodiment, in the cogging process, the cogging forging in two heats is the first-heat cogging forging and the second-heat cogging forging respectively;

[0061] The first-heat cogging forging is preheated by heating with the furnace from ≤800°C to 830 - 850°C, then heated to 1150 - 1160°C, and then the first-heat cogging forging is performed;

[0062] The second-heat cogging forging is preheated by heating with the furnace from ≤800°C to 800 - 830°C, then heated to 1060 - 1075°C, and then the second-heat cogging forging is performed;

[0063] In the secondary forging process, the secondary forging in two heats is the first-heat secondary forging and the second-heat secondary forging respectively;

[0064] The first-heat secondary forging is preheated by heating with the furnace from ≤800°C to 800°C, then heated to 1000 - 1015°C, and then the first-heat secondary forging is performed;

[0065] The second-heat secondary forging is preheated by heating with the furnace from ≤800°C to 950 - 965°C, and then the second-heat secondary forging is performed;

[0066] The shaping process includes shaping forging in four heats, and the shaping forging in four heats is the first-heat shaping forging, the second-heat shaping forging, the third-heat shaping forging, and the fourth-heat shaping forging respectively;

[0067] The first-heat shaping forging is preheated by heating with the furnace from ≤800°C to β - 30°C, and then the first-heat shaping forging is performed;

[0068] The second-heat shaping forging is preheated by heating with the furnace from ≤800°C to β - 35°C, and then the second-heat shaping forging is performed;

[0069] The third-heat shaping forging is preheated by heating with the furnace from ≤800°C to β - 40°C, and then the third-heat shaping forging is performed;

[0070] The fourth-heat shaping forging is preheated by heating with the furnace from ≤800°C to β - 45°C, and then the fourth-heat shaping forging is performed.

[0071] In some preferred embodiments, as the number of forging heats increases, the cross-sectional dimensions of the titanium alloy billet decrease sequentially.

[0072] In a preferred embodiment, as the forging process progresses, the reduction amount of the cross-sectional dimension of the titanium alloy ingot gradually decreases to

[0073] In some preferred embodiments, as the number of forging heats increases, the cross-sectional shape of the titanium alloy billet changes in the order of square, hexagonal, and octagonal;

[0074] And the cross-sectional shape formed by forging at the n3rd heat is square.

[0075] In some preferred embodiments, when n1 = 2, n2 = 2, and n3 = 4, as the number of forging heats increases, the cross-sectional shape of the titanium alloy billet is square, hexagonal, octagonal, hexagonal, square, hexagonal, square, square.

[0076] In a preferred embodiment, the cross-sectional shape of the titanium alloy billet in the cogging process is square and hexagonal; the cross-sectional shape of the titanium alloy billet in the secondary forging process is octagonal and hexagonal; the cross-sectional shape of the titanium alloy billet in the forming process is square, hexagonal, square, square.

[0077] In some preferred embodiments, the temperature of cogging forging decreases at a rate of 85 - 100 °C per heat;

[0078] The temperature of secondary forging decreases at a rate of 50 - 65 °C per heat;

[0079] The temperature of forming forging decreases at a rate of 5 - 10 °C per heat.

[0080] In some preferred embodiments, the titanium alloy billet is a TC16 titanium alloy billet; the phase transformation point temperature of the titanium alloy billet is β = 835 - 885 °C.

[0081] In some preferred embodiments, as the number of cogging forging heats increases, the deformation amount of cogging forging decreases from 60 - 55% to 55 - 50%;

[0082] As the number of secondary forging heats increases, the deformation amount of secondary forging decreases from 50 - 45% to 45 - 40%;

[0083] As the number of forming forging heats increases, the deformation amount of forming forging increases from 45 - 50% to 60 - 65%.

[0084] In some preferred embodiments, as the number of cogging forging heats increases, the hammering speed of cogging forging decreases from 55 - 50 mm / s to 50 - 45 mm / s;

[0085] As the number of secondary forging heats increases, the hammering speed of secondary forging decreases from 45 - 40 mm / s to 40 - 35 mm / s;

[0086] As the number of forming forging heats increases, the hammering speed of forming forging increases from 35 - 40 mm / s to 50 - 55 mm / s.

[0087] In a preferred embodiment, the technical method of bloom forging is as follows:

[0088] The method of the first-pass bloom forging is axial flattening, forging into a square and then axially drawing out into a square; chamfering once, forging deformation amount 60 - 55%, forging hammering speed 55 - 50 mm / s;

[0089] The method of the second-pass bloom forging is axial drawing out, axially drawing out the square into a hexagon after chamfering the square, chamfering once, forging deformation amount 55 - 50%, forging hammering speed 50 - 45 mm / s.

[0090] In a preferred embodiment, the technical method of remelting forging is as follows:

[0091] The method of the first-pass remelting forging is axial drawing out, axially drawing out the hexagon into an octagon after chamfering the hexagon, chamfering once, forging deformation amount 50 - 45%, forging hammering speed 45 - 40 mm / s;

[0092] The method of the second-pass remelting forging is axial drawing out, axially drawing out the octagon into a hexagon after chamfering the octagon, chamfering once, forging deformation amount 45 - 40%, forging hammering speed 40 - 35 mm / s.

[0093] In a preferred embodiment, the technical method of shaping forging is as follows:

[0094] The method of the first-pass shaping forging is axial drawing out, axially drawing out the hexagon into a square after chamfering the hexagon, chamfering once, forging deformation amount 45 - 50%, forging hammering speed 35 - 40 mm / s;

[0095] The method of the second-pass shaping forging is axial drawing out, axially drawing out the square into a hexagon after chamfering the square, chamfering once, forging deformation amount 50 - 55%, forging hammering speed 40 - 45 mm / s;

[0096] The method of the third-pass shaping forging is axial drawing out, axially drawing out the hexagon into a square after chamfering the hexagon, chamfering once, forging deformation amount 55 - 60%, forging hammering speed 45 - 50 mm / s;

[0097] The method of the fourth-pass shaping forging is axial drawing out, axially drawing out the square into a square after chamfering the square, chamfering once, forging deformation amount 60 - 65%; forging hammering speed 50 - 55 mm / s.

[0098] In some preferred embodiments, after the shaping process, a heat treatment system is further included, and the heat treatment system is at least one of annealing heat treatment, stress relief annealing, solution heat treatment, and aging heat treatment.

[0099] In some preferred embodiments, the annealing heat treatment is carried out at 770 - 779 °C for 15 - 25 h, and then cooled to 530 - 580 °C and then taken out of the furnace for air cooling;

[0100] The stress relief annealing treatment is carried out at 530 - 670 °C for 0.5 - 4.5 h, and then taken out of the furnace for air cooling;

[0101] The solution heat treatment is carried out at 770 - 850 °C for 1.5 - 2.5 h, and then taken out of the furnace for water quenching;

[0102] The aging heat treatment is carried out at 450 °C - 600 °C for 5.5 - 11.5 h, and then taken out of the furnace for air cooling.

[0103] According to the characteristics of the production equipment, the present invention combines the technical method of "square - hexagon - octagon" for the change of the cross - section shape required for production with the heating parameters to solve the problems of uneven final macrostructure and unqualified flaw detection of the forging billet caused by uneven high - temperature deformation of the forging billet.

[0104] The optimization of the forging method of the present invention adopts the method of changing the cross - section form of "square - hexagon - octagon" to effectively improve the original grain structure with high - temperature residual undeformed in the bloom, and improve the re - forging qualification rate of forging production and the qualification rate of the required internal structure.

[0105] The present invention can well control the mutual matching relationship between the deformation method, heating temperature and deformation amount technical parameters during forging of forgings. By comprehensively considering the process of cross - section reduction required for re - forging of the bar, and at the same time comprehensively considering factors such as the deformation amount and key technical points of the forging process: to improve the final physical and chemical requirements of the bar.

[0106] In summary, the present invention optimizes the forging process of the bar using a 5000T press equipment, adopts the method of changing the cross - section form of "square - hexagon - octagon" to effectively improve the original grain structure with high - temperature residual undeformed in the bloom, and improve the re - forging qualification rate of forging production and the qualification rate of the required internal structure. At the same time, it can well control the mutual matching relationship between the deformation amount and parameters during forging of forgings. By comprehensively considering factors such as the heating temperature, heating times, and key technical points of the production process required for re - forging of the bar, it improves the final physical and chemical requirements of the bar. As a result, the forging qualification rate is improved, the waste loss is reduced, energy is saved, and the economic benefit is improved at the same time. Specific embodiments

[0108] For a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the implementable scope of the present invention.

[0109] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0110] Unless otherwise specified, the methods described in the following embodiments are all conventional methods; the reagents and materials, unless otherwise specified, can all be purchased on the market.

[0111] TC16 titanium alloy, with a nominal composition of Ti-3Al-5Mo-4.5V.

[0112] The technical solutions of the present invention will be further described in detail through the following embodiments:

[0113] Production details: Material Ti-3Al-5Mo-4.5V titanium alloy; blank specification, Φ690×900; weight: 1682.7 kg; standard: AMS54928; name: Ti-3Al-5Mo-4.5V titanium alloy - Φ10 - titanium bar; bar specification: Φ100×2000; phase transformation point: β = 880 °C.

[0114] Example 1

[0115] A forging method for improving the properties of TC16 titanium alloy, comprising the following steps:

[0116] Step 1. Ingot forging:

[0117] The first heat: Put the billet into the furnace at ≤800 °C, heat it up to 850 °C with the furnace, and hold for 120 min; then heat it up to 1150 °C with the furnace and hold for 415 min. Then carry out the first heat ingot forging. The specific forging method is: Upset the billet from Φ690×900 to ~□695×700±15 and then draw it out. After forging the square axially and then drawing it out to forge a square to ~ square □490×1395±15; Chamfer once during the forging process, the forging deformation amount is 60%, and the forging hammering speed is 55 mm / s.

[0118] The second heating: The forged billet obtained from the first heating is charged into the furnace at a temperature ≤800°C, heated to 830°C with the furnace, held for 120 min, then further heated to 1060°C with the furnace and held for 295 min. Then, the second heating for blooming forging is carried out. The specific forging method is as follows: The forged billet is axially forged from a square □490×1395±15 to a square, elongated, and forged into a hexagon to ~ hexagon □400×2090±15: cut the stock into equal parts once, and the single piece is a hexagon □400×1040±15. Chamfer once during the forging process; the forging deformation is 55%; the forging hammering speed is 50 mm / s.

[0119] Step 2. Reducing forging:

[0120] The first heating: The forged billet obtained from the second heating for blooming forging is charged into the furnace at a temperature ≤800°C, heated to 800°C with the furnace, held for 120 min, then further heated to 1000°C with the furnace and held for 240 min. Then, the first heating for reducing forging is carried out. The specific forging method is as follows: The forged billet is axially forged from a hexagon □400×1040±15 to a square, elongated, and forged into an octagon to ~ octagon □330×1560±15; chamfer once during the forging process. The forging deformation is 50%, and the forging hammering speed is 45 mm / s.

[0121] The second heating: The forged billet obtained from the first heating for reducing forging is charged into the furnace at a temperature ≤800°C and then heated to 950°C with the furnace and held for 200 min. Then, the second heating for reducing forging is carried out. The specific forging method is as follows: The forged billet is axially forged from an octagon □330×1560±15 to a square, elongated, and forged into a hexagon to ~ hexagon □280×2185±15; chamfer once during the forging process. The forging deformation is 45%, and the forging hammering speed is 40 mm / s. Divide the hexagon □280×2185±15 into 2 pieces with a chopping knife in the middle, and the single-piece size is hexagon □280×1080±15.

[0122] Step 3. Shaping forging

[0123] The first heating: The forged billet obtained from the second heating for reducing forging is charged into the furnace at a temperature ≤800°C, heated to β - 30°C below the phase transformation point, i.e., 850°C ± 10°C, and held for 170 min. Then, the first heating for shaping forging is carried out. The specific forging method is as follows: The forged billet is axially elongated and chamfered to a square from a hexagon □280×1080±15 to ~ square □

[0124] 230×1560±15, chamfer once during the forging process. The forging deformation is 45%, and the forging hammering speed is 35 mm / s.

[0125] The second heating: The forging blank obtained by the first heating forming forging is put into the furnace at ≤800°C, and heated in the furnace to β-35°C below the phase transformation point, that is, 845°C ± 10°C, and held for 140 minutes. Then, the second heating forming forging is carried out. The specific forging method is as follows: The forging blank is axially drawn out from the square □230×1560±15, and after chamfering the square, it is axially drawn out into a hexagon ~ hexagon □185×2340±15; chamfering is carried out once during the forging process; the forging deformation amount is 50%, and the forging hammering speed is 40 mm / s. In the middle, the hexagon □185×2340±15 is evenly divided into 2 pieces with a chopping knife, and the single-piece size is hexagon □185×1160±15.

[0126] The third heating: The forging blank obtained by the second heating forming forging is put into the furnace at ≤800°C, and heated in the furnace to β-40°C below the phase transformation point, that is, 840°C ± 10°C, and held for 110 minutes. Then, the third heating forming forging is carried out. The specific forging method is as follows: The forging blank is axially drawn out from the hexagon □185×1160±15, and after chamfering the hexagon, it is axially drawn out into a square ~ square □150×1790±15, and chamfering is carried out once during the forging process. The forging deformation amount is 55%, and the forging hammering speed is 45 mm / s.

[0127] The fourth heating: The forging blank obtained by the third heating forming forging is put into the furnace at ≤800°C, and heated in the furnace to β-45°C below the phase transformation point, that is, 835°C ± 10°C, and held for 90 minutes. Then, the fourth heating forming forging is carried out. The specific forging method is as follows: The forging blank is axially drawn out from the square □150×1790±15, and after chamfering the square, it is axially drawn out into a square ~ square □115×2860±15; chamfering is carried out once during the forging process; the forging deformation amount is 60%, and the forging hammering speed is 50 mm / s.

[0128] After the hot material is returned to the furnace, it is rounded with a special swage and then axially drawn out to Φ100+2 / -1×4576±15 (allowing 1 return to the furnace to complete).

[0129] Step four: The heat treatment system adopts annealing heat treatment. The specific operation is: Insulate at 770°C for 1.5 h; then cool at a speed of 1.5°C / min. After cooling to 530°C, take it out of the furnace and air-cool.

[0130] Step five: Machining: Machine the outer circle and both end faces; the surface roughness Ra is 3.2.

[0131] Comparative example 1

[0132] A forging and forming method of TC16 titanium alloy includes the following steps:

[0133] Step one: Ingot forging:

[0134] Put the billet into a resistance furnace at 1150°C and keep it warm for 415 min. Then, perform the first-pass blooming forging of three upsetting and three drawing operations. The process is to first upset, then draw into a hexagonal shape and roll it round, and then repeat the upsetting and drawing operations 2 times. After forging, air-cool it. The forging deformation amount is 60%.

[0135] Subsequently, keep it warm at 1060°C for 295 min, and then perform the second-pass blooming forging of three upsetting and three drawing operations. The process is to first upset, then draw into a hexagonal shape and roll it round, and then repeat the upsetting and drawing operations 2 times. After forging, air-cool it to obtain a titanium alloy forging billet. The forging deformation amount is 55%.

[0136] Step Two: Reducing forging:

[0137] Perform five-pass reducing forging on the titanium alloy forging billet obtained in Step One:

[0138] The first pass: Keep it warm at 1000°C for 240 min, take it out and perform the first-pass reducing forging of one upsetting and one drawing. The process is to first upset, then turn it over 180 degrees and upset again, then draw into a hexagonal shape along the axial direction and roll it round, and then air-cool it.

[0139] The second pass: Keep it warm at 950°C for 200 min, take it out and perform the second-pass reducing forging of two upsetting and two drawing. The process is to first upset, then turn it over 180 degrees and upset again, then draw into a hexagonal shape along the axial direction and roll it round, repeat the upsetting and drawing operations once, and then air-cool it.

[0140] The third pass: Keep it warm at 930°C for 170 min, take it out and perform the third-pass reducing forging of one upsetting and one drawing. The process is to first upset, then turn it over 180 degrees and upset again, then draw into a hexagonal shape along the axial direction, and then return it to the furnace.

[0141] The fourth pass: Keep it warm at 910°C for 150 min, take it out and perform the fourth-pass reducing forging of one upsetting and one drawing. The process is to first upset, then turn it over 180 degrees and upset again, then draw into a hexagonal shape along the axial direction, and then return it to the furnace.

[0142] The fifth pass: Keep it warm at 900°C for 120 min, take it out and perform the fifth-pass reducing forging of drawing out. The process is to draw the billet into a hexagonal shape along the axial direction and roll it round.

[0143] In Step Three, the heat treatment system adopts annealing heat treatment. The specific operation is: Keep it warm at 770°C for 1.5 h; then cool it at a rate of 1.5°C / min. After cooling to 530°C, take it out of the furnace and air-cool it.

[0144] Step Four: Machining: Machine the outer circle and both end faces; the surface roughness Ra is 3.2.

[0145] Perform performance tests on the titanium alloy bars prepared in the above embodiments.

[0146] The inspection methods are carried out in accordance with GB / T 2039-2012, GB / T 228.1-2021, GB / T 228.2-2015, GB / T 229-2020, GB / T 23605-2020, GB / T 4698.15-2011, GB / T 5168-2020.

[0147] Test 1: Impact test:

[0148] Taking the titanium alloy bar prepared in Example 1 as the sample to be tested, the sample to be tested is cut once, and impact tests are carried out on the two cut samples. The test temperature is 23 °C, and the results are shown in Table 1.

[0149] Table 1 Impact resistance test results

[0150]

[0151] Note: T1 represents the front cross-section of the sample to be tested in Example 1; T2 represents the reverse cross-section of the sample to be tested in Example 1.

[0152] From Figure 1 the results, it can be seen that the titanium alloy bar prepared in Example 1 of the present invention has good impact resistance. Thus, it can be seen that by using the mutual matching relationship between the forging temperature and the deformation technical parameters during forging in Example 1 of the present invention, and adopting the method of decreasing cross-section and the way of changing cross-section shape, that is, the method of "square - hexagon - octagon", the original grain structure during blooming can be effectively improved, thereby effectively improving the impact resistance of the forgings.

[0153] Test 2: Macrostructure inspection:

[0154] Taking the titanium alloy bar prepared in Example 1 as the sample to be tested, the 1 / 2 section of the sample to be tested is cut, and the two cut surfaces are denoted as A positive and A negative; the 1 / 4 section of the sample to be tested is cut, and the two cut surfaces are denoted as B positive and B negative.

[0155] Macrostructure inspections are carried out on the 4 cut surfaces respectively. The macrostructure diagrams are shown in Figure 1 and Figure 2 .

[0156] Figure 1 It is the macrostructure diagram of the 1 / 2 section cross-section of the sample to be tested in Example 1. Among them, (A) is the macrostructure diagram of the A positive cross-section of the 1 / 2 section of the sample to be tested in Example 1; (B) is the macrostructure diagram of the A negative cross-section of the 1 / 2 section of the sample to be tested in Example 1.

[0157] Figure 2It is the macrostructure diagram of a 1 / 4-section of the sample to be tested in Example 1. Among them, (A) is the macrostructure diagram of the positive section B of the 1 / 4-section of the sample to be tested in Example 1; (B) is the macrostructure diagram of the reverse section B of the 1 / 4-section of the sample to be tested in Example 1.

[0158] From Figure 1 and Figure 2 of the macrostructure inspection results, it can be seen that there are no delamination, cracks, pores, segregation, metal and non-metal inclusions, and other metallurgical defects visible to the naked eye in the macro inspection of the cross-sections of the 1 / 2-section and 1 / 4-section of the sample to be tested in Example 1, and there are no obvious and clearly visible grains to the naked eye, meeting the standard requirements. This further verifies that in the embodiments of the present invention, by using the mutual matching relationship between the forging temperature and the deformation technical parameters during forging, and adopting the method of decreasing the cross-section and the way of changing the cross-section shape, that is, the "quadrilateral - hexagon - octagon" method, the original grain structure during blooming can be effectively improved.

[0159] Test 3: Microstructure inspection

[0160] The titanium alloy bars prepared in Example 1 and Comparative Example 1 were sectioned, and the cross-sections were inspected for microstructure. The inspection results are shown in Figure 3 and Figure 4 .

[0161] Figure 3 It is the microstructure diagram of the cross-section of the titanium alloy bar in Example 1.

[0162] Figure 4 It is the microstructure diagram of the cross-section of the titanium alloy bar in Comparative Example 1.

[0163] From Figure 3 and Figure 4 of the microstructure inspection results, it can be seen that the microstructure of the cross-section of the titanium alloy bar in Example 1 is a uniform structure processed in the α + β two-phase region. All β grains are fully fragmented, there is no continuous grain boundary α, the length of the lamellar primary α phase is very short, and these ultrafine lamellar structures have plasticity equivalent to or even better than that of the equiaxed structure, meeting the standard requirements.

[0164] Compared with the microstructure of the titanium alloy bar in Comparative Example 1, the microstructure of Example 1 is more uniform. This is mainly because the internal structure determines the flaw detection result. The more uniform the structure, the more the flaw detection result exceeds the standard. Different structures will obtain different flaw detection results. Therefore, compared with the relatively poor structure in Comparative Example 1, the better microstructure in Example 1 is more uniform and finer, and its flaw detection result is better than that of the forgings represented by the relatively poor microstructure.

[0165] Test 4: Mechanical property test

[0166] The room-temperature mechanical properties of the titanium alloy bars prepared in Example 1 and Comparative Example 1 were tested, and the results are shown in Table 2.

[0167] Table 2 Test Results of Room-Temperature Mechanical Properties of TC16 Titanium Alloy Bars

[0168] <![CDATA[Tensile strength R m / MPa]]> Elongation A / % Example 1 910.2 21.4 Comparative Example 1 830 12 Standard 815～930 ≥14

[0169] Note: The temperature at room temperature is 23 °C.

[0170] It can be seen from the results in Table 2 that the tensile strength and elongation of the TC16 titanium alloy bars prepared in Example 1 are significantly higher than the standard requirements, while the elongation of Comparative Example 1 is relatively low. It is speculated that this may be due to the fact that when producing in the order of decreasing heating temperature without fully improving the grain refinement of the internal structure of the forgings under the condition that the high-temperature deformation is not fully improved, there are finally local coarse grains or uneven structures, resulting in relatively low mechanical property indexes.

[0171] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A forging method for improving the properties of TC16 titanium alloy, characterized in that, Including: The cogging process, in which the titanium alloy billet is cogging forged for n1 heats, and as the number of cogging forging heats increases, the cogging forging temperature decreases from 1150 - 1160 °C to 1060 - 1075 °C, and the reduction in cross-sectional diameter decreases from 190 - 200 mm / heatt to 90 - 100 mm / heatt; The forging modification process, in which the titanium alloy billet is forging modified for n2 heats, and as the number of forging modification heats increases, the forging modification temperature decreases from 1000 - 1015 °C to 950 - 965 °C, and the reduction in cross-sectional diameter decreases from 70 - 80 mm / heatt to 50 - 60 mm / heatt; The forming process, in which the titanium alloy billet is forming forged for n3 heats, and as the number of forming forging heats increases, the forming forging temperature decreases from β - 30 °C to β - 45 °C, and the reduction in cross-sectional diameter decreases from 50 - 60 mm / heatt to 30 - 35 mm / heatt; n1 = 2, n2 = 2, n3 = 3 - 5, where β is the phase transformation point temperature of the titanium alloy billet; As the number of forging heats increases, chamfering is carried out during the forging process of the titanium alloy billet.

2. The forging method for improving the properties of TC16 titanium alloy according to claim 1, characterized in that, As the number of forging heats increases, the cross-sectional size of the titanium alloy billet decreases in sequence.

3. The forging method for improving the properties of TC16 titanium alloy according to claim 1, characterized in that, As the number of forging heats increases, the cross-sectional shape of the titanium alloy billet changes in the order of square, hexagonal, and octagonal; And the cross-sectional shape of the n3rd heat forming forging is square.

4. The forging method for improving the properties of TC16 titanium alloy according to claim 3, characterized in that When n1 = 2, n2 = 2, n3 = 4, as the number of forging heats increases, the cross-sectional shape of the titanium alloy billet is square, hexagonal, octagonal, hexagonal, square, hexagonal, square, square.

5. The forging method for improving the properties of TC16 titanium alloy according to claim 1, characterized in that, The temperature of the cogging forging decreases at a rate of 85 - 100 °C / heatt; The temperature of the forging modification decreases at a rate of 50 - 65 °C / heatt; The temperature of the forming forging decreases at a rate of 5 - 10 °C / heatt.

6. The forging method for improving the properties of TC16 titanium alloy according to claim 1, characterized in that, The said titanium alloy billet is a TC16 titanium alloy billet; the phase transformation point temperature of the titanium alloy billet is β = 835 - 885 °C.

7. The forging method for improving the properties of TC16 titanium alloy according to claim 1, characterized in that As the number of cogging forging heats increases, the deformation amount of the cogging forging decreases from 60 - 55% to 55 - 50%; As the number of forging modification heats increases, the deformation amount of the forging modification decreases from 50 - 45% to 45 - 40%; As the number of forming forging heats increases, the deformation amount of the forming forging increases from 45 - 50% to 60 - 65%.

8. The forging method for improving the properties of TC16 titanium alloy according to claim 1, characterized in that, As the number of cogging forging heats increases, the hammering speed of the cogging forging decreases from 55 - 50 mm / s to 50 - 45 mm / s; As the number of forging modification heats increases, the hammering speed of the forging modification decreases from 45 - 40 mm / s to 40 - 35 mm / s; As the number of forming forging heats increases, the hammering speed of the forming forging increases from 35 - 40 mm / s to 50 - 55 mm / s.

9. The forging method for improving the properties of TC16 titanium alloy according to claim 1, characterized in that, After the forming process, there is also a heat treatment system, and the said heat treatment system is at least one of annealing heat treatment, solution heat treatment, and aging heat treatment.

10. The forging method for improving the properties of TC16 titanium alloy according to claim 9, characterized in that, The said annealing heat treatment is carried out at 770 - 779 °C for 15 - 25 h, and then cooled to 530 - 580 °C and then taken out of the furnace and air-cooled; The said solution heat treatment is carried out at 770 - 850 °C for 1.5 - 2.5 h, and then taken out of the furnace and water-quenched; The aging heat treatment is carried out at 450°C to 600°C for 5.5 to 11.5 hours, and then taken out of the furnace and air-cooled.

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