High-temperature titanium alloy bar and low-cost preparation method thereof

Abstract

The invention discloses a low-cost preparation method of a high-temperature titanium alloy bar, the titanium alloy comprises the following components by mass content: 8.0%-10.5% of Al, 1.0%-2.5% of Zr, 0.5%-1.0% of Nb, 0.1%-0.5% of Mo, 0.1%-0.45% of Si, 0.15%-0.25% of O, less than or equal to 0.15% of C, and the balance of Ti and inevitable impurities, the method comprises the following steps: 1, ingot casting smelting; 2, forging and coping the cast ingot; 3, performing radial forging on the bar billet; and 4, bar billet heat treatment and machining. According to the invention, the composition of titanium alloy components is designed, one-heating-number blooming forging is combined with a multi-heating-number radial forging process, and process parameters such as deformation temperature, deformation and the like and a production flow are controlled, so that the titanium alloy bar with high-strength room-temperature mechanical property and good high-temperature property is obtained; the material is suitable for high-temperature fields such as aerospace engine parts, aircraft structural parts and fasteners.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal material processing, and in particular to a high-temperature titanium alloy bar and a low-cost preparation method thereof. Background Art

[0002] High-temperature titanium alloys are widely used in high-temperature environment fields such as aerospace, energy, petrochemicals, and automobile manufacturing due to their good thermal stability and thermal strength, as well as their own advantages such as low density, good corrosion resistance, strong creep resistance, and good fracture toughness. Under the premise of meeting the same requirements, high-temperature titanium alloys can reduce weight by about 70%, work in good condition, and play an indispensable role in modern industry. In recent years, with the rapid development of various high-temperature alloy application fields, the demand for high-temperature alloys has increased, and more stringent requirements have been put forward for their performance. Near-α titanium alloys have high high-temperature strength and high-temperature stability and have become the main high-temperature titanium alloys used at this stage, such as Ti-1100 developed in the United States, IMI834 in the United Kingdom, BT36 developed in Russia, and Ti60, Ti600, TG6, Ti65, Ti750, etc. developed in my country. Although high-temperature titanium alloys can be used at a certain high temperature, as the service temperature increases, titanium alloys are more easily oxidized, and their oxide layer will significantly reduce the alloy properties. Therefore, the current conventional service temperature of high-temperature titanium alloys is difficult to break through 600℃, the room temperature strength is about 1100MPa, and the best high-temperature tensile strength at 600℃ is about 650MPa, which also makes the development of high-temperature titanium alloys face more severe challenges. Near-α titanium alloys have a high aluminum equivalent. With the increase of α stabilizing elements, especially the increase of aluminum content, the substitution solid solution strengthening effect can significantly improve the room temperature and high temperature strength and thermal strength of titanium alloys. However, when the aluminum content exceeds a certain limit, brittle Ti3Al phase is easily formed in titanium alloys. This brittle phase will significantly reduce the plasticity and toughness of the material, making it easy to form serious surface cracks during hot processing. Traditional grinding will also aggravate crack propagation, increase invisible losses, and lead to long processing cycles, reduced yields, and increased costs. To a certain extent, it limits engineering applications, which is also one of the bottlenecks restricting the development of high-temperature titanium alloys. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a low-cost preparation method for high-temperature titanium alloy bars in view of the deficiencies of the above-mentioned prior art. The method designs the composition of the titanium alloy, adopts a process of single-fire billet forging combined with multi-fire radial forging, and controls the process parameters and production flow such as deformation temperature and deformation amount during the preparation process to avoid crack propagation during the deformation process, ensure the smooth progress of the preparation process, obtain titanium alloy bars with high-strength room temperature mechanical properties and good high-temperature properties at 700°C, improve the processing yield of high-temperature titanium alloy bars, reduce production costs, and solve the problems of poor plasticity in the hot processing process of near-α titanium alloys.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a low-cost preparation method of a high-temperature titanium alloy rod, characterized in that the high-temperature titanium alloy rod is composed of the following components by mass content: Al 8.0% to 10.5%, Zr 1.0% to 2.5%, Nb 0.5% to 1.0%, Mo 0.1% to 0.5%, Si 0.1% to 0.45%, O 0.15% to 0.25%, C ≤ 0.15%, and the balance is Ti and unavoidable impurities. The method comprises the following steps:

[0005] Step 1, ingot smelting: a consumable electrode is prepared by vacuum argon arc welding, and then the consumable electrode is smelted three times in a vacuum consumable arc furnace to obtain a titanium alloy ingot, and then the ingot riser is sawed and the surface pores and surface oxide scale are removed; the phase transition point of the titanium alloy ingot is 1100°C ± 5°C;

[0006] Step 2, ingot forging: the titanium alloy ingot from which the surface pores and surface oxide scale have been removed in step 1 is heated to a high temperature and then forged in one fire to obtain a rod blank, which is then slowly cooled;

[0007] Step 3, forging the rod billet: the rod billet slowly cooled in step 2 is subjected to 3-4 rounds of radial forging, and is ground and de-scratched after each round of radial forging. After the first 2 rounds of radial forging, the billet is slowly cooled to obtain a radial forged rod billet; the diameter of the radial forged rod billet is 2mm-4mm larger than the diameter of the target product titanium alloy bar;

[0008] Step 4, heat treatment and machining of the rod blank: use an electric heating furnace to perform atmospheric annealing on the radial forging rod blank obtained in step 3, straighten the residual temperature after annealing, and turn it to the target size to obtain a high-temperature titanium alloy rod: the high-temperature titanium alloy rod has a room temperature yield strength of more than 1150MPa, a tensile strength of more than 1250MPa, an elongation of more than 8%, a cross-sectional shrinkage of more than 10%, a high-temperature tensile strength of more than 640MPa at 700°C, an elongation of more than 55%, a uniform structure, an average grain size of about 20μm, and a finished product rate of 60% to 70%.

[0009] The above-mentioned low-cost preparation method for high-temperature titanium alloy rods is characterized in that the three vacuum consumable arc furnace smeltings in step one adopt a 500kg vacuum consumable arc furnace, and the vacuum degree is less than 0.3Pa, and the stable smelting current is 7500A~12000A; the size of the titanium alloy ingot is Φ360mm×1050mm in diameter×height, and the size of the ingot after sawing the ingot riser and removing the surface pores and surface oxide scale is Φ340mm×1000mm in diameter×height, and the surface is flat and smooth, without untreated subcutaneous pores or obvious turning steps caused by sampling.

[0010] The above-mentioned low-cost preparation method of high-temperature titanium alloy bars is characterized in that the high-temperature heating system described in step 2 is: putting it in a box-type resistance furnace at 600℃~900℃ and keeping it for 60min~90min, then heating it with the furnace to 1150℃ and keeping it for 240min~360min, and the first-time blank forging process is: after high-temperature heating, directly pulling and rounding it to a rod billet with a diameter of Φ180mm~200mm out of the furnace, the single hammer pressing amount does not exceed 70mm, and it can be returned to the furnace for heating during the forging process, and the insulation time for returning to the furnace for heating is 30min~60min; the slow cooling is to use insulation cotton to wrap and cool it, or put it in a box-type resistance furnace with a temperature not exceeding 950℃ and cool it with the furnace to 300℃~400℃, then take it out of the furnace for air cooling, and then use a grinding wheel machine to grind and remove the oxide scale on the surface of the rod billet, and water cooling during grinding to avoid heating for too long in the local area causing temperature rise and secondary cracking.

[0011] The above-mentioned low-cost preparation method of high-temperature titanium alloy bars is characterized in that the process of 3 to 4 rounds of radial forging in step three is: put it into a box-type resistance furnace at 600℃ to 900℃ and keep it for 60min to 90min, then heat it with the furnace to 1000℃ to 1050℃ and keep it for 120min to 180min, and then carry out radial forging, and the deformation of each round of radial forging is 40% to 60%. After the first two rounds of radial forging are completed, it is wrapped with insulation cotton for cooling, or placed in a box-type resistance furnace with a temperature not exceeding 950℃ and cooled with the furnace to 300℃ to 400℃ before being air-cooled out of the furnace.

[0012] The above-mentioned low-cost preparation method for high-temperature titanium alloy bars is characterized in that the heating temperature of the atmospheric annealing in step 4 is 800°C to 850°C, the holding time is 90min to 120min, and the residual temperature is straightened after being taken out of the furnace.

[0013] The above-mentioned low-cost preparation method of a high-temperature titanium alloy rod is characterized in that the diameter of the high-temperature titanium alloy rod described in step 4 is Φ30mm~Φ80mm.

[0014] At the same time, the present invention also discloses a high-temperature titanium alloy bar, characterized in that it is prepared by the above method. The high-temperature titanium alloy bar of the present invention can be applied to a high-temperature environment of 700°C, and is suitable for use in aerospace engine parts, aircraft structural parts, fasteners and many other high-temperature environment fields.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The high-temperature titanium alloy in the present invention is a typical near-α titanium alloy. By increasing the Al content in its components to 8.0% to 10.5%, its room temperature and high temperature properties are significantly improved. By adding a small amount of β interstitial stabilizing element Si, the high temperature performance and oxidation resistance of the titanium alloy are greatly improved. By adding a neutral element Zr, a large amount of solid solution is formed in α titanium, which has the effect of refining the grains and effectively improving the strength and plasticity of the titanium alloy. By adding β-stabilizing elements Mo and Nb to the titanium alloy, the thermal strength and thermal stability of the titanium alloy are improved. By adding C, the elements in the matrix are uniformly diffused and the processing window of the two-phase region is widened. The strength of the titanium alloy is further improved by doping interstitial strengthening O.

[0017] 2. The present invention adopts a process of single-fire open forging combined with multi-fire radial forging. First, the titanium alloy is used for large deformation forging at a single fire by utilizing its good deformation plasticity and low resistance at the phase transformation point. Then, multi-fire radial forging is performed at the phase transformation point, so that the billet is subjected to three-dimensional compressive stress during deformation, effectively preventing further crack expansion during deformation. At the same time, slow cooling is adopted after forging and after the first two fires of radial forging to reduce the change in temperature gradient during cooling of the billet and prevent further expansion of cracks generated during processing, thereby ensuring the smooth progress of the preparation process. Under the condition that the Al content in the titanium alloy increases and its processing plasticity decreases, the yield of high-temperature titanium alloy bars is guaranteed by regulating the preparation process.

[0018] 3. The present invention adopts a staged heating process for both single-fire forging and multi-fire radial forging, which effectively avoids the adverse phenomena such as excessive temperature gradient from the surface to the core of the billet due to poor thermal conductivity of titanium alloy during high-temperature heating and heat preservation, resulting in poor organizational uniformity, and even cracking of the billet due to uneven temperature.

[0019] 4. During the first-time forging of the blank, the present invention controls the amount of single hammer pressure reduction and takes processing measures such as remelting and heating, thereby controlling the processing deformation and deformation temperature of the blank, and at the same time controlling the temperature of the grinding process, effectively avoiding the adverse effects caused by the poor processing plasticity of near-α alloys.

[0020] 5. After the rod blanks that have obtained a certain processing plasticity through forging and radial forging are subjected to atmospheric annealing, the present invention adopts conventional air cooling to ensure that the surface of the high-temperature titanium alloy rod is good and the process is simplified; at the same time, the preparation process route of the present invention is short, the product rate is high, and the production cost is effectively reduced.

[0021] 6. The room temperature yield strength of the high-temperature titanium alloy rod prepared by the present invention is above 1150MPa, the tensile strength is above 1250MPa, the elongation is above 8%, the cross-sectional shrinkage is above 10%, the high temperature tensile strength at 700°C is above 640MPa, the elongation is above 55%, the structure is uniform, the average grain size is about 20μm, the finished product rate is 60% to 70%, and the batch consistency is good.

[0022] 7. The high-temperature titanium alloy rod prepared by the present invention has higher processing plasticity during subsequent hot working deformation, and the selectable processing methods are less limited. It is expected to prepare smaller specifications of high-temperature titanium alloy rods and wires, which will further expand its application field.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a high-magnification microstructure image of the high-temperature titanium alloy rod prepared in Example 1 of the present invention.

[0025] Figure 2 This is a high-magnification microstructure image of the high-temperature titanium alloy rod prepared in Example 2 of the present invention.

[0026] Figure 3 This is a high-magnification microstructure image of the high-temperature titanium alloy rod prepared in Example 3 of the present invention.

[0027] Figure 4 This is a high-magnification microstructure image of the high-temperature titanium alloy rod prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0028] Example 1

[0029] The high temperature titanium alloy rod of the present embodiment is composed of the following components by mass content: Al 9.2%, Zr 1.1%, Nb 0.6%, Mo 0.32%, Si 0.10%, O 0.15%, C 0.12%, and the balance is Ti and unavoidable impurities. The preparation method of the high temperature titanium alloy rod comprises the following steps:

[0030] Step 1, ingot smelting: vacuum argon arc welding is used to prepare a consumable electrode, and then the consumable electrode is placed in a 500kg vacuum consumable arc furnace for three vacuum consumable arc furnace smelting, and the vacuum degree is less than 0.3Pa, and the stable smelting current is 7520A, to obtain a titanium alloy ingot with a diameter × height of Φ360mm × 1050mm, and then the ingot riser is sawed and the surface pores and surface oxide scale are removed to a diameter × height of Φ340mm × 1000mm, and the surface is flat and smooth, without untreated subcutaneous pores or obvious turning steps caused by sampling;

[0031] Step 2, ingot forging: the titanium alloy ingot after removing the surface pores and surface oxide scale in step 1 is placed in a 600°C box-type resistance furnace for insulation for 60 minutes, then heated to 1150°C with the furnace and kept for 240 minutes, then taken out of the furnace and directly pulled out and rounded to a rod billet with a diameter of Φ180mm, the single hammer pressing amount is 60mm, and during the forging process, after the rod billet is forged to a diameter of Φ220mm, it is returned to the furnace for heating, and the insulation time for returning to the furnace for heating is 30 minutes, and then placed in a box-type resistance furnace at a temperature of 950°C, cooled to 300°C with the furnace, and then taken out of the furnace for air cooling, and the surface oxide scale is removed by grinding with a grinding wheel machine; water cooling is applied during the grinding to avoid secondary cracking caused by excessive grinding time in the local area due to temperature rise;

[0032] Step 3, forging the rod billet: the rod billet with the surface oxide scale removed in step 2 is placed in a box-type resistance furnace at 600°C for 60 minutes, and then heated to 1000°C with the furnace for 120 minutes, and then forged for 4 times, with the deformation of each time being 59%, 57%, 56%, and 56% respectively. After each time of forging, grinding and scratch removal are performed. After the first two times of forging, the rod billet is wrapped with heat preservation cotton for cooling to obtain a forged rod billet with a diameter of Φ33mm;

[0033] Step 4: heat treatment and machining of the rod blank: an electric heating furnace is used to perform atmospheric annealing on the radial forging rod blank obtained in step 3, the heating temperature is 800°C, the holding time is 90 minutes, and the residual temperature is straightened after the annealing is completed and the rod is turned to a diameter of Φ30mm to obtain a high-temperature titanium alloy rod. According to statistics, the total finished product rate of the high-temperature titanium alloy rod is 62.2%.

[0034] Figure 1 The high-magnification microstructure of the high-temperature titanium alloy rod prepared in this embodiment is as follows: Figure 1 It can be seen that the microstructure of the high-temperature titanium alloy rod is a two-phase processed structure, mainly including equiaxed α phase and a small amount of β phase, and the structure is uniform and consistent.

[0035] Example 2

[0036] The high temperature titanium alloy rod of the present embodiment is composed of the following components by mass content: Al 10.1%, Zr 1.2%, Nb 0.74%, Mo 0.12%, Si 0.22%, O 0.18%, C 0.13%, and the balance is Ti and unavoidable impurities. The preparation method of the high temperature titanium alloy rod comprises the following steps:

[0037] Step 1, ingot smelting: prepare a consumable electrode by vacuum argon arc welding, and then place the consumable electrode in a 500kg vacuum consumable arc furnace for three times of vacuum consumable arc furnace smelting, and the vacuum degree is less than 0.3Pa, the stable smelting current is 9000A, and a titanium alloy ingot with a diameter × height of Φ360mm × 1050mm is obtained, and then the ingot riser is sawed and the surface pores and surface oxide scale are removed to a diameter × height of Φ340mm × 1000mm, and the surface is flat and smooth, without untreated subcutaneous pores or obvious turning steps caused by sampling;

[0038] Step 2, ingot forging: the titanium alloy ingot after removing the surface pores and surface oxide scale in step 1 is placed in a box-type resistance furnace at 780°C for 90 minutes, and then heated to 1150°C with the furnace for 300 minutes, and then taken out of the furnace and directly pulled out and rounded to a rod billet with a diameter of Φ180mm, and the single hammer pressing amount is 65mm. During the forging process, after the rod billet is forged to a diameter of Φ220mm, it is returned to the furnace for heating, and the heating time for returning to the furnace for heating is 60 minutes, and then placed in a box-type resistance furnace at a temperature of 950°C, cooled to 400°C with the furnace, and then taken out of the furnace for air cooling, and the surface oxide scale is removed by grinding with a grinding wheel machine; water cooling is applied during the grinding to avoid the local area from being ground for too long and causing the temperature to rise and cause secondary cracking;

[0039] Step 3, forging the rod billet: put the rod billet with the surface oxide scale removed in step 2 into a box-type resistance furnace at 600°C and keep it for 60 minutes, then heat it to 1030°C and keep it for 150 minutes, then perform 3 rounds of forging, the deformation of each round of forging is 56%, 50%, and 50% respectively, and perform grinding and scratch removal after each round of forging. After the first 2 rounds of forging, put it into a box-type resistance furnace at 950°C and cool it to 300°C with the furnace, then take it out of the furnace and air cool it to obtain a forged rod billet with a diameter of Φ58mm;

[0040] Step 4: heat treatment and machining of the rod blank: an electric heating furnace is used to perform atmospheric annealing on the radial forging rod blank obtained in step 3, the heating temperature is 800°C, and the holding time is 120 minutes. After annealing, the rod blank is straightened at residual temperature after being taken out of the furnace, and is turned to a diameter of Φ55mm to obtain a high-temperature titanium alloy rod. According to statistics, the total finished product rate of the high-temperature titanium alloy rod is 68.2%.

[0041] Figure 2 The high-magnification microstructure of the high-temperature titanium alloy rod prepared in this embodiment is as follows: Figure 2It can be seen that the microstructure of the high-temperature titanium alloy rod is a two-phase processed structure, mainly including equiaxed α phase and a small amount of β phase, and the structure is uniform and consistent.

[0042] Example 3

[0043] The high temperature titanium alloy rod of the present embodiment is composed of the following components by mass content: Al 10.5%, Zr 2.4%, Nb 0.86%, Mo 0.45%, Si 0.43%, O 0.24%, C 0.09%, and the balance is Ti and unavoidable impurities. The preparation method of the high temperature titanium alloy rod comprises the following steps:

[0044] Step 1, ingot smelting: vacuum argon arc welding is used to prepare a consumable electrode, and then the consumable electrode is placed in a 500kg vacuum consumable arc furnace for three times of vacuum consumable arc furnace smelting, and the vacuum degree is less than 0.3Pa, and the stable smelting current is 10000A, to obtain a titanium alloy ingot with a diameter × height of Φ360mm × 1050mm, and then the ingot riser is sawed and the surface pores and surface oxide scale are removed to a diameter × height of Φ340mm × 1000mm, and the surface is flat and smooth, without untreated subcutaneous pores or obvious turning steps caused by sampling;

[0045] Step 2, ingot forging: the titanium alloy ingot from which the surface pores and surface oxide scale have been removed in step 1 is placed in a 900°C box-type resistance furnace for 80 minutes, and then heated to 1150°C with the furnace for 350 minutes, and then taken out of the furnace and directly drawn and rounded to a rod blank with a diameter of Φ200mm, with a single hammer pressing amount of 70mm, and then wrapped with insulation cotton and cooled to room temperature, and ground with a grinder to remove the surface oxide scale; water cooling is applied during the grinding to avoid secondary cracking caused by excessive grinding time in a local area due to temperature rise;

[0046] Step 3, forging the rod billet: put the cooled rod billet in step 2 into a box-type resistance furnace at 780°C for 80 minutes, then heat it to 1050°C with the furnace and keep it for 180 minutes, then perform 3 rounds of forging, the deformation of each round of forging is 42%, 42%, and 45% respectively, and perform grinding and de-scratching after each round of forging. After the first 2 rounds of forging, wrap it with heat preservation cotton and cool it to room temperature to obtain a forged rod billet with a diameter of Φ84mm;

[0047] Step 4: heat treatment and machining of the rod blank: an electric heating furnace is used to perform atmospheric annealing on the radial forging rod blank obtained in step 3, the heating temperature is 850°C, the holding time is 100 min, after annealing, the residual temperature is straightened after being taken out of the furnace, and the rod is turned to a diameter of Φ80 mm to obtain a high-temperature titanium alloy rod. According to statistics, the total finished product rate of the high-temperature titanium alloy rod is 65.5%.

[0048] Figure 3The high-magnification microstructure of the high-temperature titanium alloy rod prepared in this embodiment is as follows: Figure 3 It can be seen that the microstructure of the high-temperature titanium alloy rod is a two-phase processed structure, mainly including equiaxed α phase and a small amount of β phase, and the structure is uniform and consistent.

[0049] Example 4

[0050] The high temperature titanium alloy rod of the present embodiment is composed of the following components by mass content: Al 8.1%, Zr 1.8%, Nb 0.97%, Mo 0.11%, Si 0.27%, O 0.20%, C 0.14%, and the balance is Ti and unavoidable impurities. The preparation method of the high temperature titanium alloy rod comprises the following steps:

[0051] Step 1, ingot smelting: prepare a consumable electrode by vacuum argon arc welding, and then place the consumable electrode in a 500kg vacuum consumable arc furnace for three times of vacuum consumable arc furnace smelting, and the vacuum degree is less than 0.3Pa, the stable smelting current is 12000A, and a titanium alloy ingot with a diameter × height of Φ360mm × 1050mm is obtained, and then the ingot riser is sawed and the surface pores and surface oxide scale are removed to a diameter × height of Φ340mm × 1000mm, and the surface is flat and smooth, without untreated subcutaneous pores or obvious turning steps caused by sampling;

[0052] Step 2, ingot forging: the titanium alloy ingot from which the surface pores and surface oxide scale have been removed in step 1 is placed in a box-type resistance furnace at 650°C for 90 minutes, and then heated to 1150°C with the furnace for 240 minutes, and then taken out of the furnace and directly drawn and rounded to a rod blank with a diameter of Φ200mm, with a single hammer pressing amount of 70mm, and then wrapped with insulation cotton and cooled to room temperature, and ground with a grinder to remove the surface oxide scale; water cooling is applied during the grinding to avoid secondary cracking caused by excessive grinding time in a local area due to temperature rise;

[0053] Step 3, forging the rod billet: put the rod billet with the surface oxide scale removed in step 2 into a 900°C box-type resistance furnace for 90 minutes, then heat it to 1050°C with the furnace and keep it for 120 minutes, then perform 4 rounds of forging, the deformation of each round of forging is 58%, 52%, and 58% respectively, and perform grinding and scratch removal after each round of forging. After the first 2 rounds of forging, put it into a 950°C box-type resistance furnace, cool it to 400°C with the furnace, and then take it out of the furnace for air cooling to obtain a forged rod billet with a diameter of Φ58mm;

[0054] Step 4: heat treatment and machining of the rod blank: an electric heating furnace is used to perform atmospheric annealing on the radial forging rod blank obtained in step 3, the heating temperature is 820°C, the holding time is 110 min, and the residual temperature is straightened after the annealing is completed and the rod blank is turned to a diameter of Φ55 mm to obtain a high-temperature titanium alloy rod. According to statistics, the total finished product rate of the high-temperature titanium alloy rod is 61%.

[0055] Figure 4 The high-magnification microstructure of the high-temperature titanium alloy rod prepared in this embodiment is as follows: Figure 4 It can be seen that the microstructure of the high-temperature titanium alloy rod is a two-phase processed structure, mainly including equiaxed α phase and a small amount of β phase, and the structure is uniform and consistent.

[0056] The mechanical properties and average grain size of the high temperature titanium alloy bars prepared in Examples 1 to 4 of the present invention were tested, and the results are shown in Table 1 below.

[0057] Table 1

[0058]

[0059] It can be seen from Table 1 that the phase transformation point of the titanium alloy ingots prepared in Examples 1 to 4 of the present invention is 1100°C ± 5°C, the room temperature yield strength of the prepared high-temperature titanium alloy bars is above 1150 MPa, the tensile strength is above 1250 MPa, the elongation is above 8%, the cross-sectional shrinkage is above 10%, the high-temperature tensile strength at 700°C is above 640 MPa, the elongation is above 55%, the structure is uniform, the average grain size is about 20 μm, and the batch consistency is good.

[0060] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A low-cost preparation method for high-temperature titanium alloy bars, characterized in that: The high temperature titanium alloy rod is composed of the following components by mass content: Al 8.0% to 10.5%, Zr 1.0% to 2.5%, Nb 0.5% to 1.0%, Mo 0.1% to 0.5%, Si 0.1% to 0.45%, O 0.15% to 0.25%, C ≤ 0.15%, and the balance is Ti and unavoidable impurities. The method comprises the following steps: Step 1, ingot smelting: a consumable electrode is prepared by vacuum argon arc welding, and then the consumable electrode is smelted three times in a vacuum consumable arc furnace to obtain a titanium alloy ingot, and then the ingot riser is sawed and the surface pores and surface oxide scale are removed; the phase transition point of the titanium alloy ingot is 1100°C ± 5°C; Step 2, ingot forging: the titanium alloy ingot from which the surface pores and surface oxide scale have been removed in step 1 is heated to a high temperature and then forged in one fire to obtain a rod blank, which is then slowly cooled; Step 3, forging the rod billet: the rod billet slowly cooled in step 2 is subjected to 3-4 rounds of radial forging, and is ground and de-scratched after each round of radial forging. After the first 2 rounds of radial forging, the billet is slowly cooled to obtain a radial forged rod billet; the diameter of the radial forged rod billet is 2mm-4mm larger than the diameter of the target product titanium alloy bar; Step 4, heat treatment and machining of the rod blank: use an electric heating furnace to perform atmospheric annealing on the radial forging rod blank obtained in step 3, straighten the residual temperature after annealing, and turn it to the target size to obtain a high-temperature titanium alloy rod; the room temperature yield strength of the high-temperature titanium alloy rod is above 1150MPa, the tensile strength is above 1250MPa, the elongation is above 8%, the cross-sectional shrinkage is above 10%, the high-temperature tensile strength at 700°C is above 640MPa, the elongation is above 55%, the structure is uniform, the average grain size is about 20μm, and the yield rate is 60% to 70%.

2. The low-cost preparation method of a high-temperature titanium alloy rod according to claim 1, characterized in that: The three vacuum consumable arc furnace smeltings described in step one adopt a 500kg vacuum consumable arc furnace, and the vacuum degree is less than 0.3Pa, and the stable smelting current is 7500A~12000A; the size of the titanium alloy ingot is Φ360mm×1050mm in diameter×height, and the size of the ingot after sawing the ingot riser and removing the surface pores and surface oxide scale is Φ340mm×1000mm in diameter×height, and the surface is flat and smooth, without untreated subcutaneous pores or obvious turning steps caused by sampling.

3. The low-cost preparation method of a high-temperature titanium alloy rod according to claim 1, characterized in that: The high temperature heating system described in step 2 is: put it into a box-type resistance furnace at 600℃~900℃ and keep it for 60min~90min, then heat it with the furnace to 1150℃ and keep it for 240min~360min. The one-time blank forging process is: after high-temperature heating, take it out of the furnace and directly pull it out and roll it to a rod billet with a diameter of Φ180mm~200mm, the single hammer pressing amount does not exceed 70mm, and it can be returned to the furnace for heating during the forging process, and the insulation time for returning to the furnace for heating is 30min~60min; the slow cooling is to use insulation cotton to wrap and cool it, or put it into a box-type resistance furnace with a temperature not exceeding 950℃ and cool it with the furnace to 300℃~400℃, then take it out of the furnace for air cooling, and then use a grinding wheel machine to grind and remove the oxide scale on the surface of the rod billet, and water cooling during grinding to avoid heating for too long in the local area and causing secondary cracking due to temperature rise.

4. The low-cost preparation method of a high-temperature titanium alloy rod according to claim 1, characterized in that: The process of 3-4 rounds of radial forging described in step 3 is: put it into a box-type resistance furnace at 600°C to 900°C and keep it for 60min to 90min, then heat it with the furnace to 1000°C to 1050°C and keep it for 120min to 180min, then carry out radial forging, and the deformation of each round of radial forging is 40% to 60%. After the first two rounds of radial forging are completed, it is cooled by wrapping with insulation cotton, or put it into a box-type resistance furnace with a temperature not exceeding 950°C and cool it with the furnace to 300°C to 400°C before taking it out of the furnace for air cooling.

5. The low-cost preparation method of a high-temperature titanium alloy rod according to claim 1, characterized in that: The heating temperature of the atmospheric annealing in step 4 is 800° C. to 850° C., the holding time is 90 min to 120 min, and the residual temperature is used for straightening after being taken out of the furnace.

6. The low-cost preparation method of a high-temperature titanium alloy rod according to claim 1, characterized in that: The diameter of the high temperature titanium alloy rod described in step 4 is Φ30mm~Φ80mm.

7. A high temperature titanium alloy bar, characterized in that: The method is prepared by any one of claims 1 to 6.

Images