Method for preparing a high-impact, uniformly textured tc30 alloy rod for gas cylinders and product

Abstract

Disclosed are a preparation method of a tissue-uniform high-impact TC30 alloy rod for gas cylinders and a product, which solve the technical problem that TC30 alloy rods for gas cylinders cannot simultaneously meet the design requirements of "strength-plasticity-toughness" matching, realize directional regulation of the microstructure of the TC30 alloy, and obtain TC30 alloy rods (>=Φ500 mm) that meet the design requirements of comprehensive matching of strength-plasticity-toughness. Al: 4.0%-5.0%, Mo: 2.0%-3.0%, V: 1.0%-1.5%, Fe: 0.07%-0.12%, O: 0.06%-0.12%, C not more than 0.02%, N not more than 0.02%, H not more than 0.005%, and the balance being Ti; the aluminum equivalent [Al] of the titanium alloy eq is controlled to be 5.0-7.5, the molybdenum equivalent [Mo] eq is controlled to be 2.5-4.2, the beta stability coefficient K β is controlled to be 0.28-0.42.

Description

Technical Field

[0001] This invention relates to the technical field of titanium alloy manufacturing, and more particularly to a method for preparing uniform high-impact TC30 alloy bars for gas cylinders, and products manufactured according to this method. Background Technology

[0002] Steel cylinders are widely used in marine engineering equipment due to their advantages such as low manufacturing cost and ease of forming. However, steel cylinders have disadvantages such as low specific strength and poor corrosion resistance, which not only affect their service life but also lead to high maintenance costs. They need to be inspected every 2 to 3 years to assess their reliability.

[0003] Titanium and titanium alloys are excellent structural materials with high strength, good pressure resistance, good plasticity and weldability. They also have the unique combination of corrosion resistance and non-magnetic properties, which allows them to maintain excellent performance under marine environmental conditions. They are widely used in the ocean shipping industry and have become an important structural material for marine containers. They are ideal materials for submarine pressure hulls, marine piping systems, pressure vessels and other applications.

[0004] With the upgrading of domestic naval vessels and equipment, they not only need to withstand the impact of waves and floating debris during service, but also need to possess a certain degree of explosion resistance. Therefore, higher requirements are placed on the comprehensive performance of gas cylinder materials, especially impact resistance. Large-diameter (≥Φ500mm) titanium alloy bars, as raw materials for producing high-pressure gas cylinders, require particularly high uniformity of microstructure and impact resistance. According to the design requirements of a certain project, the tensile strength of titanium alloy gas cylinder bars must be ≥800MPa, elongation after fracture ≥10%, and room temperature impact energy (KV2) ≥75J. While the tensile strength and elongation of the TC4 and Ti80 titanium alloys widely used in domestic marine engineering equipment meet the design requirements, their impact energy does not. Therefore, to achieve the design requirements, it is of great significance to prepare a titanium alloy bar with uniform microstructure and high impact resistance that meets the design specifications.

[0005] Titanium and titanium alloys have poor thermal conductivity and poor hot working plasticity, resulting in a narrow processing temperature window and high processing difficulty. To ensure the uniformity of microstructure and performance of large-diameter bars meet project design requirements, large-sized square billets are typically upset forging to ensure sufficient deformation. However, upset drawing of large-sized square billets not only places high demands on the capabilities of forging equipment but also makes it easier to generate deformation dead zones during the upset drawing process, leading to uneven microstructure. Currently, the main method for producing large-diameter bars in China is multiple upset drawing at 50-100℃ above the β transformation temperature to fully break down the β grains, followed by repeated upset drawing deformation at 30-50℃ below the β transformation temperature to achieve a uniform microstructure. Traditional methods are prone to localized coarse grains and streamlines due to severe temperature rise caused by localized deformation during repeated upset drawing, resulting in uneven microstructure.

[0006] TC30 titanium alloy (equivalent to Russian BT14) is an α+β type two-phase titanium alloy with a nominal composition of Ti-5Al-3Mo-1V. It possesses excellent comprehensive mechanical properties, good weldability and hot-working plasticity, and is commonly used to manufacture critical components such as pressure vessels, compressor discs, and fasteners, finding wide application in aerospace, marine engineering, and other fields. Under conventional annealing conditions, TC30 alloy exhibits a tensile strength of 800MPa~1000MPa, elongation after fracture ≥10%, and room temperature impact energy of 40J~60J. While its tensile strength and plasticity meet design requirements, its impact performance still falls short of those requirements. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method for preparing uniform high-impact TC30 alloy rods for gas cylinders. This method can solve the technical problem that TC30 alloy rods (≥Φ500mm) for titanium alloy gas cylinders cannot simultaneously meet the design requirements for the matching of "strength-plasticity-toughness". It achieves directional control of the microstructure of TC30 alloy, and finally obtains TC30 alloy rods (≥Φ500mm) that meet the design requirements for comprehensive matching of strength-plasticity-toughness.

[0008] The technical solution of this invention is: a method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders, wherein the chemical composition of the titanium alloy consists of the following components by mass percentage: Al: 4.0%~5.0%, Mo: 2.0%~3.0%, V: 1.0%~1.5%, Fe: 0.07%~0.12%, O: 0.06%~0.12%, C not greater than 0.02%, N not greater than 0.02%, H not greater than 0.005%, balance Ti; Aluminum equivalent [Al] of titanium alloys eq The molybdenum equivalent [Mo] should be controlled between 5.0 and 7.5. eq The β stability coefficient K is controlled within the range of 2.5 to 4.2.β The value should be controlled between 0.28 and 0.42.

[0009] This invention can solve the technical problem that TC30 alloy rods (≥Φ500mm) for titanium alloy gas cylinders cannot simultaneously meet the design requirements for the matching of "strength-plasticity-toughness", realize the directional control of the microstructure of TC30 alloy, and finally obtain TC30 alloy rods (≥Φ500mm) that meet the design requirements for comprehensive matching of strength-plasticity-toughness.

[0010] It also provides titanium alloy rods manufactured using a method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders. Attached Figure Description

[0011] Figure 1 This is a low-magnification microstructure image of a Φ500mm bar prepared according to Example 1 of the present invention.

[0012] Figure 2 This is a microstructure image of a Φ500mm bar prepared according to Example 1 of the present invention. Figure 2 a represents the microstructure of the edge of the corresponding bar. Figure 2 b represents the microstructure of the core of the corresponding bar.

[0013] Figure 3 This is a low-magnification microstructure image of a Φ600mm bar prepared in Example 2 of the present invention.

[0014] Figure 4 This is a microstructure image of a Φ600mm bar prepared in Example 2 of the present invention. Figure 4 a represents the microstructure of the edge of the corresponding bar. Figure 4 b represents the microstructure of the core of the corresponding bar.

[0015] Figure 5 This is a flowchart of the method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to the present invention. Detailed Implementation

[0016] A method for preparing uniformly structured, high-impact TC30 alloy bars for gas cylinders, wherein the chemical composition of the titanium alloy consists of the following components by mass percentage: Al: 4.0%~5.0%, Mo: 2.0%~3.0%, V: 1.0%~1.5%, Fe: 0.07%~0.12%, O: 0.06%~0.12%, C not greater than 0.02%, N not greater than 0.02%, H not greater than 0.005%, balance Ti; Aluminum equivalent [Al] of titanium alloys eq The molybdenum equivalent [Mo] should be controlled between 5.0 and 7.5. eq The β stability coefficient K is controlled within the range of 2.5 to 4.2.β The value should be controlled between 0.28 and 0.42.

[0017] This invention can solve the technical problem that TC30 alloy rods (≥Φ500mm) for titanium alloy gas cylinders cannot simultaneously meet the design requirements for the matching of "strength-plasticity-toughness", realize the directional control of the microstructure of TC30 alloy, and finally obtain TC30 alloy rods (≥Φ500mm) that meet the design requirements for comprehensive matching of strength-plasticity-toughness.

[0018] Preferably, the chemical composition of the titanium alloy consists of the following components by mass percentage: Al: 4.54%, Mo: 2.56%, V: 1.26%, Fe: 0.091%, O: 0.084%, C < 0.01%, N < 0.01%, H < 0.005%, with the balance being Ti; and the aluminum equivalent [Al] eq The molybdenum equivalent [Mo] is 6.22. eq The β stability coefficient K is 3.43. β It should be controlled at 0.36.

[0019] Alternatively, the chemical composition of the titanium alloy consists of the following components by mass percentage: Al: 4.58%, Mo: 2.61%, V: 1.23%, Fe: 0.086%, O: 0.088%, C < 0.01%, N < 0.01%, H < 0.005%, with the balance being Ti; and the aluminum equivalent [Al] eq The molybdenum equivalent [Mo] is 6.34. eq The β stability coefficient K is 3.46. β It should be controlled at 0.36.

[0020] Furthermore, such as Figure 5 As shown, the method for preparing this gas cylinder using uniformly structured, high-impact TC30 alloy rods includes the following steps: (1) Preparation of TC30 alloy ingot: Grade 0 or Grade 1 small-particle sponge titanium, Al-60Mo master alloy, Al-55V master alloy, Al-60Fe master alloy, aluminum granules and titanium dioxide are weighed according to the chemical composition ratio, and then uniformly mixed by an automatic mixing and feeding system and pressed into electrode blocks. Then, the electrodes are welded into electrodes in a vacuum plasma welding box. Finally, the obtained electrodes are subjected to three vacuum self-consuming arc melting processes to obtain Φ880mm TC30 titanium alloy ingots with chemical composition that meet the requirements of GB / T 3620.1-2016 standard and have uniform composition. (2) Forging in the open phase: The titanium alloy ingot obtained in step (1) is forged in the open phase to obtain a titanium alloy square billet. The process of forging in the open phase is as follows: the ingot is heated and held at 150℃~250℃ above the β transformation temperature. The holding time is calculated as [(0.6~0.7)×min minimum cross-sectional size of the billet]min. The holding time in the furnace is controlled at 120min~150min. The height-to-diameter ratio of the billet is controlled in the range of 1.8~2.0 during the upsetting process. The upsetting rate is controlled at 20mm / s~25mm / s. The deformation amount of each upsetting and drawing is controlled between 30%~40%. The forging is completed in two fires. After the first fire is completed, the billet is immediately returned to the furnace for the second fire heating and one upsetting and one drawing forging. After forging, it is air cooled. (3) β recrystallization homogenization heat treatment: The titanium alloy billet treated in step (2) is heated and held at 30℃~50℃ below the β transformation temperature. The holding time is calculated as [(0.7~0.8)×min minimum cross-sectional size of billet] min. After holding for a certain time, it is taken out of the furnace and subjected to one heat for two upsetting and two drawing forging. The upsetting and drawing deformation is controlled between 28% and 32%, and the upsetting rate is controlled between 10mm / s and 15mm / s. The hot material is returned to the furnace and heated and held at 45℃~55℃ above the β transformation temperature. The holding time is strictly controlled within the range of [(0.45~0.55)×min minimum cross-sectional size of billet] min. After holding for a certain time, it is taken out of the furnace and water cooled immediately. The time between taking out of the furnace and entering the water is ≤30s. (4) Two-phase region upsetting and drawing forging: The billet processed in step (3) is subjected to two upsetting and drawing forging in 1 to 2 heats. The heating temperature is 30℃ to 50℃ below the β transformation temperature. The upsetting and drawing deformation is controlled between 28% and 32% each time, and the upsetting rate is controlled between 10mm / s and 15mm / s. (5) Two-phase region furnace cooling homogenization treatment: The titanium alloy billet treated in step (4) is heated and held at 30℃~50℃ below the β transformation temperature. The holding time is calculated as [(1.0~1.2)×min minimum cross-sectional size of billet]min. After holding for the time, the power is turned off and the furnace is cooled. When the temperature drops to 60℃~80℃ below the β transformation temperature, it is immediately taken out of the furnace and air cooled. (6) Two-phase region pure drawing forging: The titanium alloy billet treated in step (5) is subjected to 2 to 3 drawing forgings and 1 forging of finished product, and the heating temperature is 30℃ to 50℃ below the β transformation temperature. The net drawing deformation is controlled at 35% to 55%, and the forging is air-cooled. (7) High-temperature annealing heat treatment in the two-phase region: First, cut off the free end of the TC30 bar obtained in step (6) and cut a 20-25 mm long sample. Then, use a Class II electric furnace to anneal the sample. The annealing regime is 20-30℃ below the β transformation temperature, and hold for 1-3 hours. After taking it out of the furnace, air cool it to room temperature. The content of primary α phase is calculated by Image Pro software. A microstructure of 5%-10% equiaxed primary α phase, 25%-40% long strip primary α phase, and 55%-65% fine and dispersed secondary α structure and β transformation structure is obtained.

[0021] Preferably, in step (1), the β transformation temperature T of the alloy ingot is determined by quenching metallography. β .

[0022] Preferably, in steps (2), (3), and (4), before each upsetting process, graphite lubricant is applied to the surfaces of the upper and lower anvils; after upsetting to half the height during the upsetting process, the billet is rotated 180° and then upsetting to the remaining half height is performed.

[0023] Alternatively, this gas cylinder can be prepared using a method for fabricating uniformly structured, high-impact TC30 alloy rods, comprising the following steps: (1) Preparation of TC30 alloy ingot: Grade 0 or 1 small-particle sponge titanium, Al-60Mo master alloy, Al-55V master alloy, Al-60Fe master alloy, aluminum granules, and titanium dioxide were weighed and uniformly mixed by an automatic mixing and feeding system and then pressed into electrode blocks. The blocks were then welded into electrodes in a vacuum plasma welding box. Finally, the electrodes were subjected to three vacuum consumable arc melting processes to obtain Φ880mm TC30 titanium alloy ingots with chemical composition that meet the requirements of GB / T 3620.1-2016 standard and have uniform composition. The β transformation temperature T of the alloy ingot was determined by the quenching metallographic method. β It is 945℃; (2) Forging in the open phase: The titanium alloy ingot obtained in step (1) is subjected to single-phase open phase forging to obtain a titanium alloy square billet. The single-phase open phase forging process is as follows: After heating and holding the prepared titanium alloy ingot at 1150℃ / 560min, it is taken out of the furnace and forged in one heat, two upsetting and two drawing to □650×1210mm ("□" is a symbol commonly used in this industry, representing that the cross-sectional shape of the billet is quadrilateral). The hot material is then returned to the furnace at 1100℃ for 120 minutes, and then forged in one pass with one upsetting and one drawing to □650×1210mm. The upsetting and drawing billet height-to-diameter ratio is 1.89, the upsetting rate is 22mm / s, and the deformation amount for each upsetting and drawing is 35%. Before each upsetting process, graphite lubricant is applied to the surfaces of the upper and lower anvils. When the height is upset to 1015mm, the billet is rotated 180° and then upset to 800mm. After forging, it is air-cooled. (3) β recrystallization homogenization heat treatment: The titanium alloy billet treated in step (2) is heated and held at 915℃ for 450 min. After holding for 450 min, it is taken out of the furnace and subjected to one heat and two upsetting and two drawing forging to □650×1190mm. The upsetting and drawing deformation is 30%, and the upsetting rate is controlled at 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1010mm, the billet is rotated 180° and then upset to 830mm. After forging, the chamfer is 150~180mm, and the hot material is immediately returned to the furnace. The holding temperature of the hot material is 990℃ and the holding time is controlled at 300~330 min. After holding for 450~330 min, it is immediately taken out of the furnace and water-cooled. The water cooling time is 23s. (4) Two-phase region upsetting and drawing forging: The billet treated in step (3) is heated and held at 915℃ for 450 min. After holding at the temperature, it is taken out of the furnace and forged in one fire with two upsetting and two drawing to □650×1190mm. The deformation amount of each upsetting and drawing is 30%, and the upsetting rate is 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1010mm during the upsetting process, the billet is rotated 180° and then upset to 830mm. After forging, it is air cooled. (5) Two-phase region furnace cooling homogenization treatment: The titanium alloy billet treated in step (4) is heated and held at 915℃ for 660min~690min. After holding for 660min, the power is turned off and the furnace is cooled. When the temperature drops to 855℃, it is immediately taken out of the furnace and air cooled. (6) Two-phase region pure drawing forging: After heating and holding the titanium alloy billet treated in step (5) at 915℃, it is subjected to 2 to 3 drawing forgings and 1 forging of finished product. The net drawing deformation is 52%, and it is air-cooled after forging. (7) High-temperature annealing heat treatment in the two-phase region: After cutting off the free end of the TC30 bar obtained in step (6), a 20-25 mm long sample is cut off. Then, the sample is annealed in a Class II electric furnace. The annealing regime is 925°C below the β transformation temperature, held for 2 hours, and then air-cooled to room temperature after being taken out of the furnace. The content of primary α phase is calculated by Image Pro software, and a microstructure of 8% equiaxed primary α phase + 27% long strip primary α phase + 65% fine and dispersed secondary α structure and β transformation structure is obtained.

[0024] Alternatively, this gas cylinder can be prepared using a method for fabricating uniformly structured, high-impact TC30 alloy rods, comprising the following steps: (1) Preparation of TC30 alloy ingot: Grade 0 or 1 small-particle sponge titanium, Al-60Mo master alloy, Al-55V master alloy, Al-60Fe master alloy, aluminum granules, and titanium dioxide were weighed, uniformly mixed by an automatic mixing and feeding system, and then pressed into electrode blocks. The blocks were then welded into electrodes in a vacuum plasma welding box. Finally, the electrodes were subjected to three vacuum consumable arc melting processes to obtain Φ880mm TC30 titanium alloy ingots with chemical composition that meet the requirements of GB / T 3620.1-2016 standard and have uniform composition. The β transformation temperature T of the alloy ingot was determined by the quenching metallographic method. β It is 950℃; (2) Billet forging: The titanium alloy ingot obtained in step (1) is subjected to single-phase zone billet forging to obtain a titanium alloy square billet. The single-phase zone billet forging process is as follows: The prepared titanium alloy ingot is heated and held at 1150℃ / 560min and then taken out of the furnace for one fire and two upsetting and two drawing forging to □680×1290mm. After forging, the hot material is returned to the furnace at 1100℃ / 150min and subjected to one fire and one upsetting and one drawing forging to □680×1290mm. The upsetting and drawing billet height-to-diameter ratio is 1.9, the upsetting rate is 20mm / s, the upsetting and drawing deformation is 35% each time, and before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1065mm, the billet is rotated 180° and then upset to 840mm. After forging, it is air cooled. (3) β recrystallization homogenization heat treatment: The titanium alloy billet treated in step (2) is heated and held at 920℃ for 450 min. After holding for 450 min, it is taken out of the furnace and subjected to one heat and two upsetting and two drawing forging to □680×1270mm. The upsetting and drawing deformation is 30%, and the upsetting rate is controlled at 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1080mm, the billet is rotated 180° and then upset to 890mm. After forging, the chamfer is 150~180mm, and the hot material is immediately returned to the furnace. The holding temperature of the hot material is 1000℃ and the holding time is controlled at 330~360min. After holding for 450 min, it is taken out of the furnace and water cooled. The water cooling time is 28s. (4) Two-phase region upsetting and drawing forging: The billet treated in step (3) is heated and held at 920℃ for 480 min. After holding at the temperature, it is taken out of the furnace and forged in two upsetting and drawing cycles to □680×1270mm. The deformation amount of each upsetting and drawing is 30%, and the upsetting rate is 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1080mm during the upsetting process, the billet is rotated 180° and then upset to 890mm. After forging, it is air-cooled. (5) Two-phase region furnace cooling homogenization treatment: The titanium alloy billet treated in step (4) is heated and held at 920°C for 690 min to 720 min. After holding for 690 min to 720 min, the power is turned off and the furnace is cooled. When the temperature drops to 870°C, it is immediately taken out of the furnace and air cooled. (6) Two-phase region pure drawing forging: After heating and holding the titanium alloy billet treated in step (5) at 920℃, it is subjected to 2 to 3 drawing forgings and 1 forging of finished product. The net drawing deformation is 36%, and it is air-cooled after forging. (7) High-temperature annealing heat treatment in the two-phase region: After cutting off the free end of the TC30 bar obtained in step (6), a 20-25 mm long sample is cut off. Then, the sample is annealed in a Class II electric furnace. The annealing regime is 920°C below the β transformation temperature, held for 2 hours, and then air-cooled to room temperature after being taken out of the furnace. The content of the primary α phase is calculated by Image Pro software, and a microstructure of 5% equiaxed primary α phase, 40% long strip primary α phase, and 55% fine and dispersed secondary α and β transformation structures is obtained.

[0025] It also provides titanium alloy rods manufactured using a method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders.

[0026] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0027] 1. This invention, through precise chemical composition design and the micro-alloying effect of Fe and O elements, combined with precise free forging and heat treatment processes, prepares large-size TC30 titanium alloy bars that meet design requirements and have a good match between high plasticity and impact toughness. The tensile strength is ≥800MPa, the elongation after fracture is ≥10%, and the room temperature impact energy (KV2) is ≥75J. This invention breaks through the inverse relationship between strength and plasticity and toughness of TC30 titanium alloy and can be widely used in the manufacture of various high-pressure gas cylinders in the marine engineering field.

[0028] 2. In the free forging process, this invention first introduces a β recrystallization homogenization heat treatment in the single-phase region. By storing appropriate distortion energy through deformation in the two-phase region, and then strictly controlling the holding temperature and time in the single-phase region, sufficient static recrystallization occurs within the material. Combined with water cooling, the β grain size is solidified, achieving uniform refinement of the β grains. Next, a furnace cooling homogenization treatment is introduced in the two-phase region. By precisely controlling the furnace cooling temperature and air cooling time, the primary α phase undergoes uniform spheroidization, while a large amount of uniformly distributed secondary α phase precipitates during the air cooling stage. Finally, by precisely controlling the pure elongation deformation in the two-phase region, some of the equiaxed spheroidized primary α phase is elongated, ultimately forming a uniformly distributed microstructure. This free forging process effectively avoids the risk of microstructure inhomogeneity caused by the uneven deformation resulting from repeated multi-heat upsetting in traditional free forging processes, and also reduces the difference between the edge and core microstructures.

[0029] 3. This invention employs a high-temperature annealing heat treatment process in the two-phase region, strictly controlling the holding temperature and holding time to dissolve some of the primary α phase and simultaneously form a supersaturated solid solution (metastable β phase) in the β matrix. Subsequently, during air cooling, some of the metastable β phase undergoes decomposition, releasing fine and dispersed secondary α structures. Ultimately, a microstructure is formed consisting of 5%~10% equiaxed primary α phase + 25%~40% elongated primary α phase + 55%~65% fine and dispersed secondary α structure and β transformation structure, breaking through the inverse relationship between strength and toughness in large-size TC30 alloy bars.

[0030] In summary, under the premise of the preferred chemical composition of TC30 alloy, this invention introduces a processing method of β recrystallization homogenization heat treatment and two-phase zone furnace cooling homogenization treatment on the basis of the traditional "high-low" free forging process route, combined with two-phase zone high-temperature heat treatment. At the same time, it scientifically matches process parameters and operation details such as deformation temperature, holding time, height-to-diameter ratio, deformation amount, cooling method, forging rate, etc., thereby obtaining a uniform microstructure of the edge and core, and achieving the goal of matching strength, plasticity and toughness.

[0031] The following details specific embodiments of the present invention. Example 1

[0032] Select an ingot with a diameter of 880 mm to prepare a bar with a diameter of 500 × L mm.

[0033] This embodiment provides a TC30 alloy rod with uniform microstructure and high impact for gas cylinders and its preparation method. The chemical composition of the obtained TC30 titanium alloy, by mass percentage, includes: Al: 4.54%, Mo: 2.56%, V: 1.26%, Fe: 0.091%, O: 0.084%, C < 0.01%, N < 0.01%, H < 0.005%, with the balance being Ti; and the aluminum equivalent [Al]eq The molybdenum equivalent [Mo] is 6.22. eq The β stability coefficient (K) is 3.43. β The value should be controlled at 0.36; the specific steps are as follows:

[0034] (1) Preparation of TC30 alloy ingot: Grade 0 or 1 small-particle sponge titanium, Al-60Mo master alloy, Al-55V master alloy, Al-60Fe master alloy, aluminum briquettes, titanium dioxide, and other raw materials were weighed and uniformly mixed using an automatic mixing and feeding system. The mixture was then pressed into electrode blocks, which were welded into electrodes in a vacuum plasma welding box. Finally, the resulting electrodes underwent three vacuum consumable arc melting processes to obtain a Φ880mm TC30 titanium alloy ingot with a chemical composition meeting the requirements of GB / T 3620.1-2016 and exhibiting uniform composition. The β-transformation temperature T of the alloy ingot was determined by quenching metallography. β It is 945℃.

[0035] (2) Billet forging: The titanium alloy ingot obtained in step (1) is subjected to single-phase zone billet forging to obtain a titanium alloy square billet. The single-phase zone billet forging process is as follows: the prepared titanium alloy ingot is heated and held at 1150℃ / 560min and then taken out of the furnace for one heat and two upsetting and two drawing forging to □650×1210mm. After forging, the hot material is returned to the furnace at 1100℃ / 120min and subjected to one heat and one upsetting and one drawing forging to □650×1210mm. The height-to-diameter ratio of the upsetting and drawing billet is 1.89, the upsetting rate is 22mm / s, the deformation amount of each upsetting and drawing is 35%, and before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1015mm, the billet is rotated 180° and then upset to 800mm. After forging, it is air-cooled.

[0036] (3) β recrystallization homogenization heat treatment: The titanium alloy billet treated in step (2) is heated and held at 915℃ for 450 min. After holding for 450 min, it is taken out of the furnace and subjected to one heat and two upsetting and two drawing forging to □650×1190mm. The upsetting and drawing deformation is 30%, and the upsetting rate is controlled at 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1010mm, the billet is rotated 180° and upsetting is continued to 830mm. After forging, the chamfer is 150~180mm, and the hot material is immediately returned to the furnace. The holding temperature for hot material returning to the furnace is 990℃, and the holding time is controlled at 300~330 min. After holding for 450 min, the billet is immediately taken out of the furnace and water-cooled. The water immersion time is 23s.

[0037] (4) Two-phase region upsetting and drawing forging: The billet treated in step (3) is heated and held at 915℃ for 450 min. After holding at that temperature, it is taken out of the furnace and forged in one heat with two upsetting and two drawing processes to □650×1190mm. The deformation amount of each upsetting and drawing process is 30%, and the upsetting rate is 12mm / s. Before each upsetting process, graphite lubricant is applied to the surfaces of the upper and lower anvils. When the height is upset to 1010mm during the upsetting process, the billet is rotated 180° and then upset to 830mm. After forging, it is air-cooled.

[0038] (5) Two-phase region furnace cooling homogenization treatment: The titanium alloy billet treated in step (4) is heated and held at 915℃ for 660min~690min. After holding for the time, the power is turned off and the furnace is cooled. When the temperature drops to 855℃, it is immediately taken out of the furnace and air cooled.

[0039] (6) Two-phase region pure drawing forging: After heating and holding the titanium alloy billet treated in step (5) at 915℃, it is subjected to 2 to 3 drawing forgings and 1 forging of finished product. The net drawing deformation is 52%, and the forging is air-cooled.

[0040] (7) High-temperature annealing heat treatment in the two-phase region: After cutting off the free end of the TC30 bar obtained in step (6), a 20 (0~+5) mm long sample was cut off. Then, the sample was annealed in a Class II electric furnace at 925℃ below the β transformation temperature for 2 hours. After annealing, the sample was air-cooled to room temperature. The content of the primary α phase was calculated by Image Pro software, and a microstructure of 8% equiaxed primary α phase, 27% elongated primary α phase, and 65% fine and dispersed secondary α and β transformation structures was obtained.

[0041] The bar sample block from Example 1 was selected for performance testing, and the results of the mechanical property testing are shown in Table 1.

[0042] Figure 1 This is a low-magnification microstructure image of a Φ500mm bar produced by forging using this process. It can be seen that there are no obvious metallurgical defects at low magnification, and the microstructure is uniform. Figure 2 For the edge of the corresponding bar ( Figure 2 a) and the heart ( Figure 2 b) shows that the microstructure of the edge and the center is uniform. Example 2

[0043] Select an ingot with a diameter of 880 mm to prepare a bar with a diameter of 600 × L mm.

[0044] This embodiment provides a TC30 alloy rod with uniform microstructure and high impact for gas cylinders and its preparation method. The chemical composition of the obtained TC30 titanium alloy, by mass percentage, includes: Al: 4.58%, Mo: 2.61%, V: 1.23%, Fe: 0.086%, O: 0.088%, C < 0.01%, N < 0.01%, H < 0.005%, with the balance being Ti; and the aluminum equivalent [Al]... eq The molybdenum equivalent [Mo] is 6.34. eq The β stability coefficient (K) is 3.46. β The value should be controlled at 0.36; the specific steps are as follows:

[0045] (1) Preparation of TC30 alloy ingot: Grade 0 or 1 small-particle sponge titanium, Al-60Mo master alloy, Al-55V master alloy, Al-60Fe master alloy, aluminum briquettes, titanium dioxide, and other raw materials were weighed and uniformly mixed using an automatic mixing and feeding system. The mixture was then pressed into electrode blocks, which were welded into electrodes in a vacuum plasma welding box. Finally, the resulting electrodes underwent three vacuum consumable arc melting processes to obtain a Φ880mm TC30 titanium alloy ingot with a chemical composition meeting the requirements of GB / T 3620.1-2016 and exhibiting uniform composition. The β-transformation temperature T of the alloy ingot was determined by quenching metallography. β It is 950℃.

[0046] (2) Billet forging: The titanium alloy ingot obtained in step (1) is subjected to single-phase zone billet forging to obtain a titanium alloy square billet. The single-phase zone billet forging process is as follows: the prepared titanium alloy ingot is heated and held at 1150℃ / 560min and then taken out of the furnace for one heat and two upsetting and two drawing forging to □680×1290mm. After forging, the hot material is returned to the furnace at 1100℃ / 150min and subjected to one heat and one upsetting and one drawing forging to □680×1290mm. The upsetting and drawing billet height-to-diameter ratio is 1.9, the upsetting rate is 20mm / s, the upsetting and drawing deformation is 35% each time, and before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1065mm, the billet is rotated 180° and then upset to 840mm. After forging, it is air-cooled.

[0047] (3) β recrystallization homogenization heat treatment: The titanium alloy billet treated in step (2) is heated and held at 920℃ for 450 min. After holding for 450 min, it is taken out of the furnace and subjected to one heat and two upsetting and two drawing forging to □680×1270mm. The upsetting and drawing deformation is 30%, and the upsetting rate is controlled at 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1080mm, the billet is rotated 180° and upsetting is continued to 890mm. After forging, the chamfer is 150~180mm, and the hot material is immediately returned to the furnace. The holding temperature for hot material returning to the furnace is 1000℃, and the holding time is controlled at 330~360min. After holding for 450 min, the billet is immediately taken out of the furnace and water-cooled. The water immersion time is 28s.

[0048] (4) Two-phase region upsetting and drawing forging: The billet treated in step (3) is heated and held at 920℃ for 480 min. After holding at that temperature, it is taken out of the furnace and forged in two upsetting and drawing cycles to □680×1270mm. The deformation amount of each upsetting and drawing is 30%, and the upsetting rate is 12mm / s. Before each upsetting process, graphite lubricant is applied to the surfaces of the upper and lower anvils. When the height is upset to 1080mm during the upsetting process, the billet is rotated 180° and upsetting is continued to 890mm. After forging, it is air-cooled.

[0049] (5) Two-phase region furnace cooling homogenization treatment: The titanium alloy billet treated in step (4) is heated and held at 920℃ for 690min~720min. After holding for the time, the power is turned off and the furnace is cooled. When the temperature drops to 870℃, it is immediately taken out of the furnace and air cooled.

[0050] (6) Two-phase region pure drawing forging: After heating and holding the titanium alloy billet treated in step (5) at 920℃, it is subjected to 2 to 3 drawing forgings and 1 forging of finished product. The net drawing deformation is 36%, and it is air-cooled after forging.

[0051] (7) High-temperature annealing heat treatment in the two-phase region: After cutting off the free end of the TC30 bar obtained in step (6), a 20 (0~+5) mm long sample was cut off. Then, the sample was annealed in a Class II electric furnace at 920℃ below the β transformation temperature for 2 hours. After annealing, the sample was air-cooled to room temperature. The content of the primary α phase was calculated by Image Pro software, and a microstructure of 5% equiaxed primary α phase, 40% elongated primary α phase, and 55% fine and dispersed secondary α and β transformation structures was obtained.

[0052] The bar specimens from Example 2 were selected for performance testing, and the results of the mechanical property testing are shown in Table 1.

[0053] Figure 3This is a low-magnification microstructure image of a Φ600mm bar produced by forging using this process. It can be seen that there are no obvious metallurgical defects at low magnification, and the microstructure is uniform. Figure 4 For the edge of the corresponding bar ( Figure 4 a) and the heart ( Figure 4 b) shows that the microstructure of the edge and the center is uniform. Comparative Example 1

[0054] TC4 titanium alloy Φ780mm ingots with an ingot β transformation temperature of 990℃ were selected to prepare Φ500mm bars.

[0055] (1) Ingot preparation: The chemical composition of each element was adjusted according to the requirements of GB / T3620.1 standard. The TC4 titanium alloy ingot with a diameter of 780mm was prepared by three-stage vacuum self-consuming electric arc furnace melting. The chemical composition met the requirements of GB / T3620.1.

[0056] (2) Forging of billet: The TC4 ingot obtained in step (1) is heated and held at 1150℃. After being taken out of the furnace and drawn into a length of □640mm, it is cut into pieces and then immediately returned to the furnace for heating at 1100℃ and subsequent two upsetting and two drawing forging to obtain a square billet of □660mm. The upsetting deformation is 35%~45%, and it is air cooled after forging.

[0057] (3) Single-phase zone upsetting and drawing forging: The TC4 square billet obtained in step (II) is heated and held at 1080℃, and forged 3 times. Each time, the deformation is 38%~45% and the forging is carried out by 2 upsetting and 2 drawing to obtain a square billet □660mm. After forging, it is air-cooled.

[0058] (4) Two-phase region upsetting and drawing forging: The TC4 square billet obtained in step (III) is first heated and held at 960℃, and then forged 3 times. Each time, the forging is carried out with 2 upsetting and 2 drawing operations with a deformation amount of 35%~40% to obtain a flat square billet □500×800×L mm; then heated and held at 955℃, and forged 2 times. Each time, the forging is carried out with 1 upsetting and 1 drawing operation with a deformation amount of 40% to obtain a square billet □660 mm. After forging, it is air-cooled.

[0059] (5) Two-phase zone drawing and forging: The TC4 square billet obtained in step (IV) is heated and held at 960℃ and forged for 3 times. First, it is drawn and forged with a deformation of 20%~30% in 2 heats to obtain ◇530×L mm; then it is rolled and drawn on a flat anvil into a black bar with a diameter of Φ515×L mm.

[0060] The bar sample block from Comparative Example 1 was selected for annealing and performance testing. The results of the mechanical property testing are shown in Table 1. Comparative Example 2

[0061] A Φ780mm Ti80 titanium alloy ingot with a β transformation temperature of 985℃ was selected to prepare Φ500mm bars.

[0062] (1) Ingot preparation: The chemical composition of each element was prepared according to the requirements of GB / T3620.1 standard. The Ti80 titanium alloy ingot with a diameter of 780mm was prepared by three-stage vacuum self-consuming electric arc furnace melting. The chemical composition met the requirements of GB / T3620.1.

[0063] (2) Forging: The Ti80 ingot obtained in step (I) is heated and held at 1150℃. After being taken out of the furnace and drawn into a length of □640mm, it is cut into pieces and then immediately returned to the furnace for heating at 1100℃ and subsequent two upsetting and two drawing forging. Two forgings are performed, and each forging is performed with a deformation of 35%~40% to obtain a square billet □640mm. After forging, it is air cooled.

[0064] (3) Single-phase region upsetting and drawing forging: The Ti80 square billet obtained in step (II) is heated and held at 1080℃, and forged twice. Each forging is carried out with a deformation of 35%~40% for 2 upsetting and 2 drawing to obtain a square billet □640mm. After forging, it is air cooled.

[0065] (4) Two-phase region upsetting and drawing forging: The Ti80 square billet obtained in step (III) is heated and held at 955℃, and forged 3 times. Each time, the deformation is 30%~35% and the billet is forged 2 times upsetting and 2 times drawing to obtain a square billet □640mm. After forging, it is air cooled.

[0066] (5) Two-phase region elongation forging: The Ti80 square billet obtained in step (IV) is heated and held at 955℃, and forged 3 times. First, it is elongated by 2 times with a deformation of 20%~30% to obtain ◇530×L mm; then it is rolled and elongated on a flat anvil into a black bar with a diameter of Φ515×L mm.

[0067] The bar sample blocks from Comparative Example 2 were selected for annealing and performance testing. The results of the mechanical property testing are shown in Table 1.

[0068] Comparing Embodiment 1, Embodiment 2, Comparative Example 1 and Comparative Example 2 of the present invention, it can be seen that the method of the present invention, under the premise of satisfying the material tensile strength ≥800MPa, elongation after fracture ≥10%, and room temperature impact energy (KV2) ≥75J, has significantly better impact toughness than Comparative Example 1 and Comparative Example 2, and has a better strength and toughness match.

[0069] Table 1

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing high-impact TC30 alloy rods with uniform microstructure for gas cylinders, characterized in that: The chemical composition of titanium alloys consists of the following components by mass percentage. composition: Al: 4.0%~5.0%, Mo: 2.0%~3.0%, V: 1.0%~1.5%, Fe: 0.07%~0.12%, O: 0.06%~0.12%, C not greater than 0.02%, N not greater than 0.02%, H not greater than 0.005%, balance Ti; Aluminum equivalent [Al] of titanium alloys eq The molybdenum equivalent [Mo] should be controlled between 5.0 and 7.

5. eq The β stability coefficient K is controlled within the range of 2.5 to 4.

2. β The value should be controlled between 0.28 and 0.

42.

2. The method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to claim 1, characterized in that: The chemical composition of the titanium alloy consists of the following components by mass percentage: Al: 4.54%, Mo: 2.56%, V: 1.26%, Fe: 0.091%, O: 0.084%, C < 0.01%, N < 0.01%, H < 0.005%, with the balance being Ti; and the aluminum equivalent [Al] eq The molybdenum equivalent [Mo] is 6.

22. eq The β stability coefficient K is 3.

43. β It should be controlled at 0.

36.

3. The method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to claim 1, characterized in that: The chemical composition of the titanium alloy consists of the following components by mass percentage: Al: 4.58%, Mo: 2.61%, V: 1.23%, Fe: 0.086%, O: 0.088%, C < 0.01%, N < 0.01%, H < 0.005%, with the balance being Ti; and the aluminum equivalent [Al] eq The molybdenum equivalent [Mo] is 6.

34. eq The β stability coefficient K is 3.

46. β It should be controlled at 0.

36.

4. The method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to claim 1, characterized in that: It includes the following steps: (1) Preparation of TC30 alloy ingot: Grade 0 or Grade 1 small-particle sponge titanium, Al-60Mo master alloy, Al-55V master alloy, Al-60Fe master alloy, aluminum granules and titanium dioxide are weighed according to the chemical composition ratio, and then uniformly mixed by an automatic mixing and feeding system and pressed into electrode blocks. Then, the electrodes are welded into electrodes in a vacuum plasma welding box. Finally, the obtained electrodes are subjected to three vacuum self-consuming arc melting processes to obtain Φ880mm TC30 titanium alloy ingots with chemical composition that meet the requirements of GB / T 3620.1-2016 standard and have uniform composition. (2) Forging in the open phase: The titanium alloy ingot obtained in step (1) is forged in the open phase to obtain a titanium alloy square billet. The process of forging in the open phase is as follows: the ingot is heated and held at 150℃~250℃ above the β transformation temperature. The holding time is calculated as [(0.6~0.7)×min minimum cross-sectional size of the billet]min. The holding time in the furnace is controlled at 120min~150min. The height-to-diameter ratio of the billet is controlled in the range of 1.8~2.0 during the upsetting process. The upsetting rate is controlled at 20mm / s~25mm / s. The deformation amount of each upsetting and drawing is controlled between 30%~40%. The forging is completed in two fires. After the first fire is completed, the billet is immediately returned to the furnace for the second fire heating and one upsetting and one drawing forging. After forging, it is air cooled. (3) β recrystallization homogenization heat treatment: The titanium alloy billet treated in step (2) is heated and held at 30℃~50℃ below the β transformation temperature. The holding time is calculated as [(0.7~0.8)×min minimum cross-sectional size of billet] min. After holding for a certain time, it is taken out of the furnace and subjected to one heat for two upsetting and two drawing forging. The upsetting and drawing deformation is controlled between 28% and 32%, and the upsetting rate is controlled between 10mm / s and 15mm / s. The hot material is returned to the furnace and heated and held at 45℃~55℃ above the β transformation temperature. The holding time is strictly controlled within the range of [(0.45~0.55)×min minimum cross-sectional size of billet] min. After holding for a certain time, it is taken out of the furnace and water cooled immediately. The time between taking out of the furnace and entering the water is ≤30s. (4) Two-phase region upsetting and drawing forging: The billet processed in step (3) is subjected to two upsetting and drawing forging in 1 to 2 heats. The heating temperature is 30℃ to 50℃ below the β transformation temperature. The upsetting and drawing deformation is controlled between 28% and 32% each time, and the upsetting rate is controlled between 10mm / s and 15mm / s. (5) Two-phase region furnace cooling homogenization treatment: The titanium alloy billet treated in step (4) is heated and held at 30℃~50℃ below the β transformation temperature. The holding time is calculated as [(1.0~1.2)×min minimum cross-sectional size of billet]min. After holding for the time, the power is turned off and the furnace is cooled. When the temperature drops to 60℃~80℃ below the β transformation temperature, it is immediately taken out of the furnace and air cooled. (6) Two-phase region pure drawing forging: The titanium alloy billet treated in step (5) is subjected to 2 to 3 drawing forgings and 1 forging of finished product, and the heating temperature is 30℃ to 50℃ below the β transformation temperature. The net drawing deformation is controlled at 35% to 55%, and the forging is air-cooled. (7) High-temperature annealing heat treatment in the two-phase region: First, cut off the free end of the TC30 bar obtained in step (6) and cut a 20-25 mm long sample. Then, use a Class II electric furnace to anneal the sample. The annealing regime is 20-30℃ below the β transformation temperature, and hold for 1-3 hours. After taking it out of the furnace, air cool it to room temperature. The content of primary α phase is calculated by Image Pro software. A microstructure of 5%-10% equiaxed primary α phase, 25%-40% long strip primary α phase, and 55%-65% fine and dispersed secondary α structure and β transformation structure is obtained.

5. The method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to claim 4, characterized in that: In step (1), the β transformation temperature T of the alloy ingot is determined by quenching metallography. β .

6. The method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to claim 5, characterized in that: In steps (2), (3), and (4), before each upsetting process, graphite lubricant is applied to the surfaces of the upper and lower anvils; after upsetting to half the height during the upsetting process, the billet is rotated 180° and then upsetting to the remaining half height is performed.

7. The method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to claim 2, characterized in that: It includes the following steps: (1) Preparation of TC30 alloy ingot: Grade 0 or 1 small-particle sponge titanium, Al-60Mo master alloy, Al-55V master alloy, Al-60Fe master alloy, aluminum granules, and titanium dioxide were weighed and uniformly mixed by an automatic mixing and feeding system and then pressed into electrode blocks. The blocks were then welded into electrodes in a vacuum plasma welding box. Finally, the electrodes were subjected to three vacuum consumable arc melting processes to obtain Φ880mm TC30 titanium alloy ingots with chemical composition that meet the requirements of GB / T 3620.1-2016 standard and have uniform composition. The β transformation temperature T of the alloy ingot was determined by the quenching metallographic method. β It is 945℃; (2) Billet forging: The titanium alloy ingot obtained in step (1) is subjected to single-phase zone billet forging to obtain a titanium alloy square billet. The single-phase zone billet forging process is as follows: The prepared titanium alloy ingot is heated and held at 1150℃ / 560min and then taken out of the furnace for one fire and two upsetting and two drawing forging to □650×1210mm. After forging, the hot material is returned to the furnace at 1100℃ / 120min and subjected to one fire and one upsetting and one drawing forging to □650×1210mm. The upsetting and drawing billet height-to-diameter ratio is 1.89, the upsetting rate is 22mm / s, the upsetting and drawing deformation is 35% each time, and before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1015mm, the billet is rotated 180° and then upset to 800mm. After forging, it is air cooled. (3) β recrystallization homogenization heat treatment: The titanium alloy billet treated in step (2) is heated and held at 915℃ for 450 min. After holding for 450 min, it is taken out of the furnace and subjected to one heat and two upsetting and two drawing forging to □650×1190mm. The upsetting and drawing deformation is 30%, and the upsetting rate is controlled at 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1010mm, the billet is rotated 180° and then upset to 830mm. After forging, the chamfer is 150~180mm, and the hot material is immediately returned to the furnace. The holding temperature of the hot material is 990℃ and the holding time is controlled at 300~330 min. After holding for 450~330 min, it is immediately taken out of the furnace and water-cooled. The water cooling time is 23s. (4) Two-phase region upsetting and drawing forging: The billet treated in step (3) is heated and held at 915℃ for 450 min. After holding at the temperature, it is taken out of the furnace and forged in one fire with two upsetting and two drawing to □650×1190mm. The deformation amount of each upsetting and drawing is 30%, and the upsetting rate is 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1010mm during the upsetting process, the billet is rotated 180° and then upset to 830mm. After forging, it is air cooled. (5) Two-phase region furnace cooling homogenization treatment: The titanium alloy billet treated in step (4) is heated and held at 915℃ for 660min~690min. After holding for 660min, the power is turned off and the furnace is cooled. When the temperature drops to 855℃, it is immediately taken out of the furnace and air cooled. (6) Two-phase region pure drawing forging: After heating and holding the titanium alloy billet treated in step (5) at 915℃, it is subjected to 2 to 3 drawing forgings and 1 forging of finished product. The net drawing deformation is 52%, and it is air-cooled after forging. (7) High-temperature annealing heat treatment in the two-phase region: After cutting off the free end of the TC30 bar obtained in step (6), a 20-25 mm long sample is cut off. Then, the sample is annealed in a Class II electric furnace. The annealing regime is 925°C below the β transformation temperature, held for 2 hours, and then air-cooled to room temperature after being taken out of the furnace. The content of primary α phase is calculated by Image Pro software, and a microstructure of 8% equiaxed primary α phase + 27% long strip primary α phase + 65% fine and dispersed secondary α structure and β transformation structure is obtained.

8. The method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to claim 3, characterized in that: It includes the following steps: (1) Preparation of TC30 alloy ingot: Grade 0 or 1 small-particle sponge titanium, Al-60Mo master alloy, Al-55V master alloy, Al-60Fe master alloy, aluminum granules, and titanium dioxide were weighed, uniformly mixed by an automatic mixing and feeding system, and then pressed into electrode blocks. The blocks were then welded into electrodes in a vacuum plasma welding box. Finally, the electrodes were subjected to three vacuum consumable arc melting processes to obtain Φ880mm TC30 titanium alloy ingots with chemical composition that meet the requirements of GB / T 3620.1-2016 standard and have uniform composition. The β transformation temperature T of the alloy ingot was determined by the quenching metallographic method. β It is 950℃; (2) Billet forging: The titanium alloy ingot obtained in step (1) is subjected to single-phase zone billet forging to obtain a titanium alloy square billet. The single-phase zone billet forging process is as follows: The prepared titanium alloy ingot is heated and held at 1150℃ / 560min and then taken out of the furnace for one fire and two upsetting and two drawing forging to □680×1290mm. After forging, the hot material is returned to the furnace at 1100℃ / 150min and subjected to one fire and one upsetting and one drawing forging to □680×1290mm. The upsetting and drawing billet height-to-diameter ratio is 1.9, the upsetting rate is 20mm / s, the upsetting and drawing deformation is 35% each time, and before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1065mm, the billet is rotated 180° and then upset to 840mm. After forging, it is air cooled. (3) β recrystallization homogenization heat treatment: The titanium alloy billet treated in step (2) is heated and held at 920℃ for 450 min. After holding for 450 min, it is taken out of the furnace and subjected to one heat and two upsetting and two drawing forging to □680×1270mm. The upsetting and drawing deformation is 30%, and the upsetting rate is controlled at 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1080mm, the billet is rotated 180° and then upset to 890mm. After forging, the chamfer is 150~180mm, and the hot material is immediately returned to the furnace. The holding temperature of the hot material is 1000℃ and the holding time is controlled at 330~360min. After holding for 450 min, it is taken out of the furnace and water cooled. The water cooling time is 28s. (4) Two-phase region upsetting and drawing forging: The billet treated in step (3) is heated and held at 920℃ for 480 min. After holding at the temperature, it is taken out of the furnace and forged in two upsetting and drawing cycles to □680×1270mm. The deformation amount of each upsetting and drawing is 30%, and the upsetting rate is 12mm / s. Before each upsetting process, graphite lubricant is applied to the surface of the upper and lower anvils. When the height is upset to 1080mm during the upsetting process, the billet is rotated 180° and then upset to 890mm. After forging, it is air-cooled. (5) Two-phase region furnace cooling homogenization treatment: The titanium alloy billet treated in step (4) is heated and held at 920°C for 690 min to 720 min. After holding for 690 min to 720 min, the power is turned off and the furnace is cooled. When the temperature drops to 870°C, it is immediately taken out of the furnace and air cooled. (6) Two-phase region pure drawing forging: After heating and holding the titanium alloy billet treated in step (5) at 920℃, it is subjected to 2 to 3 drawing forgings and 1 forging of finished product. The net drawing deformation is 36%, and it is air-cooled after forging. (7) High-temperature annealing heat treatment in the two-phase region: After cutting off the free end of the TC30 bar obtained in step (6), a 20-25 mm long sample is cut off. Then, the sample is annealed in a Class II electric furnace. The annealing regime is 920°C below the β transformation temperature, held for 2 hours, and then air-cooled to room temperature after being taken out of the furnace. The content of the primary α phase is calculated by Image Pro software, and a microstructure of 5% equiaxed primary α phase, 40% long strip primary α phase, and 55% fine and dispersed secondary α and β transformation structures is obtained.

9. Titanium alloy rods manufactured by the method for preparing uniformly structured, high-impact TC30 alloy rods for gas cylinders according to any one of claims 1-8.

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