Titanium alloy bars and their preparation method

Abstract

The present invention relates to the technical field of titanium alloy material processing, and discloses a titanium alloy bar and a preparation method thereof. The preparation method comprises the following steps: S1. Mix metal raw materials and then melt them to obtain a titanium alloy ingot with an aluminum content of 6.7 - 7.1 wt% and an oxygen content of 0.12 - 0.15 wt%. The metal raw materials contain titanium and aluminum. S2. Perform at least three upsetting and drawing operations and at least one rolling operation on the titanium alloy ingot. The titanium alloy bar has high elastic modulus and strength both at room temperature and at a temperature of 300°C.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy material processing, and particularly relates to a titanium alloy bar and a preparation method thereof. Background Art

[0002] TA15 titanium alloy has a nominal composition of Ti-6Al-2Zr-1Mo-1V and is a near-α type titanium alloy with a high aluminum equivalent, which can be used for a long time at 450-500°C. With the change of the service conditions of the material, higher requirements are put forward for the room temperature and 300°C high temperature strength and elastic modulus of the material, and it is required to meet that at room temperature, the room temperature elastic modulus ≥ 109 GPa, the tensile strength ≥ 930 MPa, the yield strength ≥ 855 MPa, and the elongation ≥ 10%; at 300°C, the elastic modulus ≥ 100 GPa, the tensile strength ≥ 750 MPa, the yield strength ≥ 550 MPa, and the elongation ≥ 15%. The existing conventional process takes the ingot of TA15 that meets GB / T3620.1-2016 "Titanium and Titanium Alloy Grades and Chemical Compositions" and conducts multi-pass upsetting and drawing in the single-phase region and two-phase region, and then forms it through forming equipment such as a quick forging machine and a precision forging machine. The TA15 bars prepared by the above method often cannot meet the technical index requirements in terms of elastic modulus and strength. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problem that the elastic modulus and strength of TA15 bars cannot meet the technical index requirements in the prior art, and to provide a titanium alloy bar and a preparation method thereof, and the titanium alloy bar has high elastic modulus and strength at both room temperature and 300°C.

[0004] To achieve the above purpose, the first aspect of the present invention provides a preparation method of a titanium alloy bar, including the following steps:

[0005] S1. Mix the metal raw materials and then melt them to obtain a titanium alloy ingot with an aluminum content of 6.7-7.1 wt% and an oxygen content of 0.12-0.15 wt%; the metal raw materials contain titanium and aluminum;

[0006] S2. Perform at least three upsetting and drawing operations and at least one rolling operation on the titanium alloy ingot.

[0007] Preferably, in the step S1, the metal raw materials further contain zirconium, molybdenum, and vanadium.

[0008] Preferably, in the titanium alloy ingot, the content of zirconium is 2-2.5 wt%, the content of molybdenum is 1.5-2 wt%, the content of vanadium is 2-2.5 wt%, and the balance is titanium.

[0009] Preferably, in the titanium alloy ingot, the mass ratio of aluminum to oxygen is 1:0.016-0.023.

[0010] Preferably, the conditions for smelting include at least: the smelting current is 12 - 32 KA, the smelting voltage is 28 - 43 V, the arc stabilizing current is 10 - 30 A, and the commutation frequency is 10 - 20 seconds / time.

[0011] Preferably, the upsetting and drawing includes the first upsetting and drawing, the second upsetting and drawing, and the third upsetting and drawing;

[0012] The process of the first upsetting and drawing includes upsetting and then diagonal drawing. The conditions for the first upsetting and drawing include at least: the temperature is 1000 - 1200 °C;

[0013] The second upsetting and drawing is upsetting. The conditions for the second upsetting and drawing include at least: the temperature is T β - 70 to T β - 50 °C;

[0014] The process of the third upsetting and drawing includes upsetting and then drawing. The conditions for the third upsetting and drawing include at least: the temperature is T β - 70 to T β - 50 °C;

[0015] wherein, T β is the phase transition temperature of the titanium alloy ingot.

[0016] Further preferably, in the first upsetting and drawing, the number of times of diagonal drawing is 2 - 3 times, and the single deformation amount is 19 - 36%; and / or

[0017] The conditions for the second upsetting and drawing further include: the upsetting ratio is 2.5 - 3.5; and / or

[0018] The number of times of the third upsetting and drawing is 2 - 4 times, and the single deformation amount is 30 - 50%.

[0019] More preferably, the method further includes: after the second upsetting and drawing, heating up to T β + 20 to T β + 50 °C and then holding for 120 - 240 min.

[0020] Preferably, the conditions for rolling include at least: the temperature is T β - 90 to T β - 50 °C, and the total deformation amount of rolling is 50 - 75%.

[0021] The second aspect of the present invention provides a titanium alloy bar prepared by the above preparation method.

[0022] Through the above technical solution, the preparation method of the titanium alloy bar provided by the present invention obtains a titanium alloy ingot with an aluminum content of 6.7-7.1 wt% and an oxygen content of 0.12-0.15 wt% by melting metal raw materials, and performs at least three upsetting-drawing and at least one rolling on it, so that the obtained titanium alloy bar has a relatively high elastic modulus, tensile strength and yield strength. Description of the Drawings

[0023] Figure 1 It is the EBSD diagram of the bar prepared in Example 1. Among them, from left to right are the crystal plane distribution diagrams of the bar head tissues {0001}, {10-10}, and {11-22};

[0024] Figure 2 It is the EBSD diagram of the bar prepared in Example 2. Among them, from left to right are the crystal plane distribution diagrams of the bar head tissues {0001}, {10-10}, and {11-22};

[0025] Figure 3 It is the EBSD diagram of the bar prepared in Example 3. Among them, from left to right are the crystal plane distribution diagrams of the bar head tissues {0001}, {10-10}, and {11-22}. Detailed Embodiments

[0026] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0027] As described above, the present invention provides a preparation method of a titanium alloy bar, including the following steps:

[0028] S1. Mix the metal raw materials and then melt them to obtain a titanium alloy ingot with an aluminum content of 6.7-7.1 wt% and an oxygen content of 0.12-0.15 wt%; the metal raw materials contain titanium and aluminum;

[0029] S2. Perform at least three upsetting-drawing and at least one rolling on the titanium alloy ingot.

[0030] According to the present invention, the metal raw materials can be any raw materials containing titanium and aluminum. Exemplarily, the metal raw materials providing titanium elements can be at least one of titanium metal, titanium sponge and titanium dioxide; the metal raw materials providing aluminum raw materials can be selected from at least one of aluminum metal, aluminum molybdenum and aluminum vanadium. Preferably, the metal raw materials providing titanium elements are titanium sponge and / or titanium dioxide; the aluminum metal is aluminum beans.

[0031] According to the present invention, the aluminum and oxygen contents in the titanium alloy ingot are detected in accordance with GB / T 4698.

[0032] During the research process, the inventors found that by first mixing metal raw materials and then melting them to obtain a titanium alloy ingot with an aluminum content of 6.7 - 7.1 wt% and an oxygen content of 0.12 - 0.15 wt%, and then performing at least three upsetting and drawing operations and at least one rolling operation on the titanium alloy ingot, the aluminum and oxygen elements with the above contents are respectively dissolved in the α lattice as substitutional and interstitial elements, which can effectively enhance the atomic binding force, thereby improving the strength and elastic modulus of the material, and further improving the elastic modulus, tensile strength and yield strength of the prepared titanium alloy bar.

[0033] In addition, the present invention can use conventional raw materials for melting and the deformation method is simple. Without introducing additional production costs, the improvement of the strength and elastic modulus of the bar is achieved.

[0034] According to the present invention, in the titanium alloy ingot, the aluminum content can be 6.7 wt%, 6.8 wt%, 6.9 wt%, 7.0 wt%, 7.1 wt%, or any value within the range formed by these values; the oxygen content can be 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, or any value within the range formed by these values.

[0035] Preferably, in the step S1, the metal raw materials further contain zirconium, molybdenum and vanadium. It has been found that when the metal raw materials also contain zirconium, molybdenum and vanadium at the same time, the elastic modulus, tensile strength and yield strength of the bar can be further improved.

[0036] According to the present invention, by way of example, the metal raw material providing zirconium element can be sponge zirconium; the metal raw material providing molybdenum element can be aluminum molybdenum; the metal raw material providing vanadium element can be aluminum vanadium.

[0037] Preferably, in the titanium alloy ingot, the content of zirconium is 2-2.5 wt%, which can be 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, or any value within the range formed by these values; the content of molybdenum is 1.5-2 wt%, which can be 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, or any value within the range formed by these values; the content of vanadium is 2-2.5 wt%, which can be 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, or any value within the range formed by these values. Controlling the contents of zirconium element, molybdenum element and vanadium element in the titanium alloy ingot within the above ranges can further improve the elastic modulus, tensile strength and yield strength of the obtained titanium alloy bars.

[0038] According to the present invention, the contents of zirconium, molybdenum and vanadium in the titanium alloy ingot are detected in accordance with GB / T4698.

[0039] Preferably, in the titanium alloy ingot, the mass ratio of aluminum to oxygen is 1:0.016-0.023, which can be 1:0.016, 1:0.017, 1:0.018, 1:0.019, 1:0.02, 1:0.021, 1:0.022, 1:0.023, or any value within the range formed by these ratios. It is found that controlling the mass ratio of aluminum to oxygen within the above ranges can further improve the elastic modulus, tensile strength and yield strength of the obtained titanium alloy bars.

[0040] Preferably, the melting conditions include at least: the melting current is 12-32 KA, which can be 12 KA, 16 KA, 20 KA, 24 KA, 28 KA, 32 KA, or any value within the range formed by these values; the melting voltage is 28-43 V, the arc stabilizing current is 10-30 A, and the commutation frequency is 10-20 times / second. Under the above conditions, the contents of aluminum element and oxygen element in the titanium alloy ingot can be better controlled, and further, the elastic modulus, tensile strength and yield strength of the obtained titanium alloy bars can be improved.

[0041] Preferably, the method further includes: after mixing, pressing the metal raw materials into blocks.

[0042] In order to achieve a better melting effect, preferably, the melting is repeated 2-4 times.

[0043] Preferably, the upsetting and drawing process includes the first upsetting and drawing, the second upsetting and drawing, and the third upsetting and drawing; the process of the first upsetting and drawing includes upsetting followed by diagonal drawing, and the conditions of the first upsetting and drawing include at least: the temperature is 1000 - 1200 °C, which can be 1000 °C, 1020 °C, 1040 °C, 1060 °C, 1080 °C, 1100 °C, 1120 °C, 1140 °C, 1160 °C, 1180 °C, 1200 °C, or any value within the range formed by these temperatures; the second upsetting and drawing is upsetting, and the conditions of the second upsetting and drawing include at least: the temperature is T β - 70 to T β - 50 °C, which can be T β - 70 °C, T β - 66 °C, T β - 62 °C, T β - 58 °C, T β - 54 °C, T β - 50 °C, or any value within the range formed by these temperatures; the process of the third upsetting and drawing includes upsetting followed by drawing, and the conditions of the third upsetting and drawing include at least: the temperature is T β - 70 to T β - 50 °C, which can be T β - 70 °C, T β - 66 °C, T β - 62 °C, T β - 58 °C, T β - 54 °C, T β - 50 °C, or any value within the range formed by these temperatures. Diagonal drawing in the first upsetting and drawing can quickly break β grains and destroy the orientation relationship inside the α clusters formed during the high - temperature cooling stage, providing nucleation sites for the nucleation of the high - temperature β phase and subsequent upsetting and drawing at the phase transformation point, further refining and homogenizing β grains, so that the prepared titanium alloy bars have higher elastic modulus, tensile strength, and yield strength.

[0044] Wherein, T β is the phase transformation temperature of the titanium alloy ingot.

[0045] Preferably, in the first upsetting and drawing, the number of diagonal drawing times is 2 - 3 times, and the single - pass deformation amount is 19 - 36%, which can be 19%, 22%, 25%, 28%, 31%, 34%, 36%, or any value within the range formed by these values. It is found that controlling the diagonal drawing in the first upsetting and drawing within the above range can further improve the elastic modulus, tensile strength, and yield strength of the prepared titanium alloy bars.

[0046] Preferably, the conditions for the second upsetting and drawing also include: the upsetting ratio is 2.5 - 3.5, which can be 2.5, 2.7, 2.9, 3.1, 3.3, 3.5, or any value within the range formed by these values. Controlling the upsetting ratio of the second upsetting and drawing to 2.5 - 3.5 can further improve the elastic modulus, tensile strength, and yield strength of the prepared titanium alloy bar.

[0047] Preferably, the number of times of the second upsetting and drawing is two. The directions of the two upsetting and drawing are different.

[0048] Preferably, the number of times of the third upsetting and drawing is 2 - 4 times, and the single deformation amount is 30 - 50%, which can be 30%, 34%, 38%, 42%, 46%, 50%, or any value within the range formed by these values. Under the above conditions, the elastic modulus, tensile strength, and yield strength of the prepared titanium alloy bar can be further improved.

[0049] Preferably, the method further includes: after the second upsetting and drawing, heating to T β +20 to T β +50 °C and then holding for 120 - 240 min. The above steps can further improve the elastic modulus, tensile strength, and yield strength of the prepared titanium alloy bar.

[0050] Preferably, the conditions for the rolling at least include: the temperature is T β -90 to T β -50 °C, and the total deformation amount of the rolling is 50 - 75%. It can further improve the elastic modulus, tensile strength, and yield strength of the prepared titanium alloy bar.

[0051] Preferably, the method further includes: before upsetting and drawing, cutting off the riser and the ingot bottom of the titanium alloy ingot, so that the obtained bar is more uniform.

[0052] Preferably, the method further includes annealing the bar obtained by rolling. In order to further improve the elastic modulus, tensile strength, and yield strength of the bar. Preferably, the annealing temperature is 650 - 750 °C.

[0053] In addition, the present invention also provides a titanium alloy bar prepared by the above preparation method. This titanium alloy bar has a high elastic modulus, tensile strength, and yield strength.

[0054] Preferably, the elastic modulus of the titanium alloy bar at 25 °C is 106 - 130 GPa, the tensile strength is 980 - 1070 MPa, and the yield strength is 910 - 960 MPa; the elastic modulus of the titanium alloy bar at 300 °C is 100 - 118 GPa, the tensile strength is 760 - 840 MPa, and the yield strength is 610 - 660 MPa.

[0055] According to the present invention, the elastic modulus is tested in accordance with the standard of GB / T 22315, and the tensile strength and yield strength are tested in accordance with GB / T 228.1.

[0056] Preferably, the diameter of the titanium alloy bar is 80 - 120 mm.

[0057] According to a particularly preferred embodiment of the present invention, a method for preparing a titanium alloy bar is provided, including the following steps:

[0058] S1. Mix sponge titanium, aluminum beans, titanium dioxide, sponge zirconium, aluminum molybdenum, and aluminum vanadium and press them into an electrode block, then melt them 3 times under the melting conditions of a stable-stage melting current of 12 - 32 KA, a melting voltage of 28 - 43 V, an arc-stabilizing current of 10 - 30 A, and a commutation frequency of 10 - 20 seconds / time to obtain a titanium alloy ingot with an aluminum content of 6.7 - 7.1 wt%, an oxygen content of 0.12 - 0.15 wt%, a zirconium content of 2 - 2.5 wt%, a molybdenum content of 1.5 - 2 wt%, a vanadium content of 2 - 2.5 wt%, and the balance being titanium; in the titanium alloy ingot, the mass ratio of aluminum to oxygen is 1:0.016 - 0.023.

[0059] S2. Cut off the riser and the bottom of the ingot of the titanium alloy ingot obtained in step S1, then perform upsetting (upsetting ratio of 1.7 - 1.8) at 1150 °C and then perform diagonal drawing three times to obtain a first billet, with the single-pass deformation amount of diagonal drawing being 19 - 36%.

[0060] S3. Upset the first billet obtained in step S2 at a temperature of T β -70 to T β -50 °C with an upsetting ratio of 2.5 - 3.5, then heat up to T β +20 to T β +50 °C, hold for heat preservation in the furnace for 120 - 240 min, then cool it with water after taking it out of the furnace by performing side upsetting and drawing at a temperature of T β -70 to T β -50 °C with an upsetting and drawing ratio of 2.5 - 3.5 to obtain a second billet.

[0061] S4. Perform upsetting and drawing deformation with an upsetting ratio of 1.6 - 1.8 on the second billet obtained in step S3 at a temperature of T β -70 to T β -50 °C, repeat the upsetting and drawing 2 - 4 times and then directly perform drawing, with the single-pass deformation amount during the drawing process controlled to be 30 - 50% to obtain a third billet.

[0062] S5. Perform upsetting and drawing on the third billet obtained in step S4 at a temperature of T β -90 to T βRolling deformation is carried out at -50°C to obtain TA15 titanium alloy bars with a diameter of 80 - 120 mm, and the deformation amount during the rolling process is controlled to be 50 - 75%.

[0063] Through the above preparation method, a titanium alloy ingot with an aluminum content of 6.7 - 7.1 wt% and an oxygen content of 0.12 - 0.15 wt% is obtained by melting metal raw materials, and it is subjected to at least three upsetting and drawing operations and at least one rolling operation, so that the obtained titanium alloy bars have high elastic modulus, tensile strength and yield strength. Further controlling the zirconium content, molybdenum content, vanadium content in the titanium alloy ingot, as well as the mass ratio of oxygen to titanium, can further improve the elastic modulus, tensile strength and yield strength of the prepared titanium alloy bars.

[0064] By adopting axial diagonal drawing and elongation at the billet opening stage of the ingot to rapidly break β grains, and then destroying the orientation relationship inside the α cluster formed during the high-temperature cooling stage through the second upsetting and drawing with a large upset ratio, nucleation points are provided for the nucleation of the high-temperature β phase and the third upsetting and drawing is carried out at the phase transformation point to further refine and homogenize β grains. Finally, at the phase transformation point, a water-cooling method is adopted for the final heat treatment to precipitate α lamellae with a relatively thin thickness and relatively random orientation, providing a good original structure for the subsequent uniform and fine equiaxed α phase, thereby further improving the elastic modulus, tensile strength and yield strength of the prepared titanium alloy bars.

[0065] Since continuous grain boundary α phase that seriously damages plasticity will precipitate when titanium alloy cools from β→α + β, multiple heat treatments of deformation are often required to fully break the grain boundary α phase. However, during the multiple heat treatment heating processes, the α phase will be spheroidized and grow under the influence of the thermal driving force, reducing the strength of the material. At the same time, too large a deformation amount will cause the material to undergo α→β dynamic phase transformation during the deformation process and β→α reverse transformation during the subsequent cooling or furnace return heat preservation process, increasing the α phase grain size. In the present invention, the second upsetting and drawing and the method of furnace return forging are adopted to shorten the high-temperature heating duration to reduce the size of the α phase, and finally, on the basis of fully broken grain boundaries, α phase with fine size is obtained, thereby further improving the tensile strength and yield strength of the prepared titanium alloy bars.

[0066] The present invention adopts a high-speed deformation method of rolling deformation, and controls the temperature and deformation amount simultaneously to obtain a texture orientation with a smaller included angle between the c-axis and the loading direction, thereby further improving the elastic modulus of the bars.

[0067] In addition, the bar preparation process of low-temperature finite deformation + low-temperature rolling adopted by the present invention has a simple process flow and can significantly reduce the production cost compared with the conventional process of refining grains through multiple heat treatments of upsetting and drawing.

[0068] The present invention will be described in detail below by way of examples. In the following examples, aluminum molybdenum is a commercially available product with the grade of AlMo65, the aluminum content is 34.94 wt%, and the molybdenum content is 64.89 wt%; aluminum vanadium is a commercially available product with the grade of AlV55, the aluminum content is 41.14 wt%, and the vanadium content is 58.53 wt%.

[0069] Example 1

[0070] S1. Mix 224 kg of sponge titanium, 10.1 kg of aluminum beans, 0.78 kg of titanium dioxide, 6.48 kg of sponge zirconium, 7.89 kg of aluminum molybdenum and 10.95 kg of aluminum vanadium, press them into electrode blocks, and then melt them 3 times under the melting conditions of a stable-stage melting current of 20 KA, a melting voltage of 35 V, an arc-stabilizing current of 20 A, and a commutation frequency of 15 seconds / time, to obtain a titanium alloy ingot with an aluminum content of 6.7 wt%, an oxygen content of 0.15 wt%, a zirconium content of 2.45 wt%, a molybdenum content of 1.98 wt%, and a vanadium content of 2.48 wt%.

[0071] S2. Cut off the riser and the bottom of the ingot obtained in step S1, and then perform one-time upsetting at 1150 °C and three-time diagonal drawing to obtain the first blank.

[0072] S3. Upset the first blank obtained in step S2 at the phase transition point T β -70 °C (T β = 1010 °C) with a upset ratio of 3.5, then heat it up to T β +50 °C, hold it in the furnace for 240 min, and after taking it out of the furnace, perform lateral upsetting and drawing at the phase transition point T β -70 °C with a upset ratio of 3.5, and then water-cool it.

[0073] S4. Perform one upsetting and drawing on the second blank obtained in step S3 at the phase transition point T β -70 °C, then return it to the furnace for another upsetting and drawing, and then directly draw it. The single-pass deformation amount during the drawing process is controlled to be 50% to obtain the third blank.

[0074] S5. Perform rolling deformation on the third blank obtained in step S4 at the phase transition point T β -50 °C to obtain a TA15 titanium alloy bar with a diameter of 100 mm. The deformation amount during the rolling process is controlled to be 75%.

[0075] Example 2

[0076] S1. Mix 223 kg of titanium sponge, 12.3 kg of aluminum beans, 0.6 kg of titanium dioxide, 5.43 kg of zirconium sponge, 6.21 kg of aluminum molybdenum, and 9.27 kg of aluminum vanadium, press them into electrode blocks, and then melt them 4 times under the melting conditions of a stable-stage melting current of 12 KA, a melting voltage of 28 V, a stabilizing arc current of 10 A, and a commutation frequency of 20 seconds per time to obtain a titanium alloy ingot with an aluminum content of 7.1 wt%, an oxygen content of 0.12 wt%, a zirconium content of 2.05 wt%, a molybdenum content of 1.56 wt%, and a vanadium content of 2.03 wt%.

[0077] S2. After cutting off the riser and the bottom of the ingot obtained in step S1, perform one upsetting at 1150 °C and then three diagonal elongations to obtain the first billet.

[0078] S3. Upset the first billet obtained in step S2 at the phase transition point T β -60 °C (T β = 998 °C) with a upset ratio of 3, then heat it up to T β +40 °C, hold it in the furnace for 150 min, cool it in water after taking it out of the furnace, and perform commutation upsetting and drawing at the phase transition point T β -60 °C with a upset ratio of 3.

[0079] S4. Perform one upsetting and drawing on the second billet obtained in step S3 at the phase transition point T β -50 °C, then put it back into the furnace for another upsetting and drawing, and then directly elongate it. Control the single-pass deformation amount during the elongation process to be 30% to obtain the third billet.

[0080] S5. Perform one rolling deformation on the third billet obtained in step S4 at the phase transition point T β -75 °C to obtain a TA15 titanium alloy bar with a diameter of 120 mm. Control the deformation amount during the rolling process to be 60%.

[0081] Example 3

[0082] S1. Mix 224 kg of titanium sponge, 11 kg of aluminum beans, 0.66 kg of titanium dioxide, 6 kg of zirconium sponge, 6.42 kg of aluminum molybdenum, and 10.56 kg of aluminum vanadium, press them into electrode blocks, and then melt them 2 times under the melting conditions of a stable-stage melting current of 32 KA, a melting voltage of 43 V, a stabilizing arc current of 30 A, and a commutation frequency of 10 seconds per time to obtain a titanium alloy ingot with an aluminum content of 6.9 wt%, an oxygen content of 0.13 wt%, a zirconium content of 2.27 wt%, a molybdenum content of 1.67 wt%, and a vanadium content of 2.23 wt%.

[0083] S2. After cutting off the riser and the bottom of the ingot obtained in step S1, perform one upsetting at 1150 °C and then two diagonal elongations to obtain the first billet.

[0084] S3. Upset the first blank obtained in step S2 at the phase transition point T β -50 °C (T β = 1005 °C) with an upset ratio of 2.5, then heat it up to T β +20 °C, keep it in the furnace for heat preservation for 120 min. After taking it out of the furnace, perform lateral upsetting and drawing at the phase transition point T β -50 °C with an upset ratio of 2.5, and then water-cool.

[0085] S4. Perform one upsetting and drawing on the second blank obtained in step S3 at the phase transition point T β -60 °C, then put it back into the furnace and perform another upsetting and drawing, and then directly elongate it. The single deformation amount during the elongation process is controlled at 44% to obtain the third blank.

[0086] S5. Perform a rolling deformation on the third blank obtained in step S4 at the phase transition point T β -90 °C to obtain a TA15 titanium alloy bar with a diameter of 100 mm. The deformation amount during the rolling process is controlled at 50%.

[0087] Example 4

[0088] Prepare the titanium alloy bar according to the method of Example 1. The difference is that in step S1, adjust the addition amounts of the raw materials of titanium sponge, aluminum beans, titanium dioxide, zirconium sponge, aluminum molybdenum, and aluminum vanadium to obtain a titanium alloy ingot with an aluminum content of 6.7 wt%, an oxygen content of 0.12 wt%, a zirconium content of 2.45 wt%, a molybdenum content of 1.98 wt%, and a vanadium content of 2.48 wt%.

[0089] Example 5

[0090] Prepare the titanium alloy bar according to the method of Example 2. The difference is that in step S1, adjust the addition amounts of the raw materials of titanium sponge, aluminum beans, titanium dioxide, zirconium sponge, aluminum molybdenum, and aluminum vanadium to obtain a titanium alloy ingot with an aluminum content of 7.1 wt%, an oxygen content of 0.15 wt%, a zirconium content of 2.05 wt%, a molybdenum content of 1.56 wt%, and a vanadium content of 2.03 wt%.

[0091] Example 6

[0092] Prepare the titanium alloy bar according to the method of Example 1. The difference is that in step S1, adjust the addition amounts of the raw materials of titanium sponge, aluminum beans, titanium dioxide, zirconium sponge, aluminum molybdenum, and aluminum vanadium to obtain a titanium alloy ingot with an aluminum content of 6.7 wt%, an oxygen content of 0.15 wt%, a zirconium content of 1.93 wt%, a molybdenum content of 1.44 wt%, and a vanadium content of 1.89 wt%.

[0093] Example 7

[0094] The titanium alloy bars were prepared according to the method of Example 2, except that in step S1, the addition amounts of raw materials of titanium sponge, aluminum beans, titanium dioxide, zirconium sponge, aluminum molybdenum and aluminum vanadium were adjusted to obtain a titanium alloy ingot with an aluminum content of 7.1 wt%, an oxygen content of 0.12 wt%, a zirconium content of 2.55 wt%, a molybdenum content of 2.12 wt% and a vanadium content of 2.14 wt%.

[0095] Example 8

[0096] The titanium alloy bars were prepared according to the method of Example 1, except that in step S3, the upset ratio was 4.

[0097] Example 9

[0098] The titanium alloy bars were prepared according to the method of Example 3, except that in step S3, the upset ratio was 2.

[0099] Example 10

[0100] The titanium alloy bars were prepared according to the method of Example 1, except that in step S3, the temperature was T β +70 °C (T β = 1010 °C).

[0101] Example 11

[0102] The titanium alloy bars were prepared according to the method of Example 1, except that in step S4, the temperature was T β +70 °C (T β = 1010 °C).

[0103] Example 12

[0104] The titanium alloy bars were prepared according to the method of Example 1, except that step S3 included: upsetting the first billet obtained in step S2 at a temperature of the phase transformation point T β -70 °C (T β = 1010 °C) with an upset ratio of 3.5, and then performing side upsetting and drawing at a temperature of the phase transformation point T β -70 °C with an upset ratio of 3.5 and then water cooling.

[0105] Comparative Example 1

[0106] The titanium alloy bars were prepared according to the method of Example 1, except that in step S1, the addition amounts of raw materials of titanium sponge, aluminum beans, titanium dioxide, zirconium sponge, aluminum molybdenum and aluminum vanadium were adjusted to obtain a titanium alloy ingot with an aluminum content of 6.5 wt%, an oxygen content of 0.15 wt%, a zirconium content of 2.45 wt%, a molybdenum content of 1.98 wt% and a vanadium content of 2.48 wt%.

[0107] Comparative Example 2

[0108] The titanium alloy bars were prepared according to the method of Example 1, except that in step S1, the addition amounts of raw materials of titanium sponge, aluminum beans, titanium dioxide, zirconium sponge, aluminum molybdenum and aluminum vanadium were adjusted to obtain a titanium alloy ingot with an aluminum content of 6.7 wt%, an oxygen content of 0.17 wt%, a zirconium content of 2.45 wt%, a molybdenum content of 1.98 wt%, and a vanadium content of 2.48 wt%.

[0109] Comparative Example 3

[0110] The titanium alloy bars were prepared according to the method of Example 2, except that in step S1, the addition amounts of raw materials of titanium sponge, aluminum beans, titanium dioxide, zirconium sponge, aluminum molybdenum and aluminum vanadium were adjusted to obtain a titanium alloy ingot with an aluminum content of 7.3 wt%, an oxygen content of 0.12 wt%, a zirconium content of 2.05 wt%, a molybdenum content of 1.56 wt%, and a vanadium content of 2.03 wt%.

[0111] Comparative Example 4

[0112] The titanium alloy bars were prepared according to the method of Example 2, except that in step S1, the addition amounts of raw materials of titanium sponge, aluminum beans, titanium dioxide, zirconium sponge, aluminum molybdenum and aluminum vanadium were adjusted to obtain a titanium alloy ingot with an aluminum content of 7.1 wt%, an oxygen content of 0.1 wt%, a zirconium content of 2.05 wt%, a molybdenum content of 1.56 wt%, and a vanadium content of 2.03 wt%.

[0113] Test Example 1

[0114] The mechanical properties of the prepared titanium alloy bars were tested after annealing at 700 °C. The mechanical properties are shown in Table 1-2 and Figures 1-3 , and the mechanical properties at room temperature (25 °C) are shown in Table 1, and the mechanical properties at 300 °C are shown in Table 2. The mechanical properties of the titanium alloy bars prepared in Example 1 are shown in Figure 1 , the mechanical properties of the titanium alloy bars prepared in Example 2 are shown in Figure 2 , and the mechanical properties of the titanium alloy bars prepared in Example 3 are shown in Figure 3 . It can be seen from Figures 1-2 that the material has formed obvious {0001} / / rolling direction texture characteristics. The texture strength of the bars in Example 1 is 5.21, the structure strength of the bars in Example 2 is 7.30, and the structure strength of the bars in Example 3 is 7.87. This kind of texture characteristic can ensure that the material has better elastic modulus when bearing loads.

[0115] Table 1

[0116]

[0117] Table 2

[0118]

[0119] As can be seen from the results in Table 1 and Table 2, the tensile strength, yield strength and elastic modulus of the examples are all higher than those of the comparative examples, indicating that the titanium alloy bars prepared by the method provided by the present invention have high elastic modulus and strength both at room temperature and at 300 °C.

[0120] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A preparation method of a titanium alloy bar, characterized in that, It includes the following steps: S1. Mix the metal raw materials and then melt them to obtain a titanium alloy ingot with an aluminum content of 6.7 - 7.1 wt%, an oxygen content of 0.12 - 0.15 wt%, a zirconium content of 2 - 2.5 wt%, a molybdenum content of 1.5 - 2 wt%, a vanadium content of 2 - 2.5 wt%, and the balance being titanium; the metal raw materials contain titanium, aluminum, zirconium, molybdenum, and vanadium; S2. Perform at least three upsetting and drawing operations and at least one rolling operation on the titanium alloy ingot; The upsetting and drawing operations include the first upsetting and drawing, the second upsetting and drawing, and the third upsetting and drawing; The process of the first upsetting and drawing includes: upsetting the titanium alloy ingot and then performing diagonal drawing to obtain a first blank, and the conditions of the first upsetting and drawing at least include: the temperature is 1000 - 1200 °C; The process of the second upsetting and drawing includes: subjecting the first blank to upsetting at a temperature of T β -70 to T β -50 °C and a upsetting ratio of 2.5 - 3.5, then heating it to T β +20 to T β +50 °C, holding it in the furnace for heat preservation for 120 - 240 min, and after taking it out of the furnace, subjecting it to side upsetting and drawing at a temperature of T β -70 to T β -50 °C and a upsetting ratio of 2.5 - 3.5 to obtain a second blank; The process of the third upsetting and drawing includes: upsetting and drawing the second blank under the condition that the temperature is T β -70 to T β -50 °C, repeating upsetting and then directly drawing to obtain the third blank; The rolling process includes: subjecting the third blank to rolling deformation at a temperature of T β -90 to T β -50°C, and controlling the deformation amount during the rolling process to be 50-75%; Among them, T β is the phase transition temperature of the titanium alloy ingot.

2. The preparation method according to claim 1, characterized in that, In the titanium alloy ingot, the mass ratio of aluminum to oxygen is 1:0.016 - 0.

023.

3. The preparation method according to claim 1, characterized in that, The conditions of the melting at least include: the melting current is 12 - 32 KA, the melting voltage is 28 - 43 V, the arc stabilizing current is 10 - 30 A, and the commutation frequency is 10 - 20 seconds / time.

4. The preparation method according to claim 1, characterized in that, In the first upsetting and drawing, the number of diagonal drawing operations is 2 - 3 times, and the single deformation amount is 19 - 36%; and / or In the process of the third upsetting and drawing, the number of upsetting and drawing repetitions is 2 - 4 times, and the single deformation amount during the drawing process is 30 - 50%.

5. A titanium alloy bar prepared by the preparation method according to any one of claims 1 to 4.

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