High plasticity low interstitial titanium alloy and method for producing a bar therefrom

Abstract

The application belongs to the technical field of titanium alloy material and bar processing, and particularly relates to a high plasticity and toughness low-interstitial titanium alloy and a bar preparation method thereof. The raw materials are mixed, pressed and assembled and welded into a consumable electrode, and the bar is obtained through smelting, forging and heat treatment. Through the synergistic process control of component optimization and preparation, the content of interstitial elements in the alloy is reduced, the impact energy of the prepared high plasticity and toughness low-interstitial titanium alloy bar is greater than or equal to 60 J, the fracture toughness is greater than or equal to 115 MPa.m 1 / 2 , the dynamic rheological stress is greater than or equal to 1580 MPa, the dynamic plastic strain is greater than or equal to 0.33, and the dynamic impact absorption energy is greater than or equal to 520 J / cm 3 under the condition of 10 ‑1 s 3 grade strain rate, the tensile strength at 500 DEG C is greater than or equal to 850 MPa, the dynamic rheological stress is greater than or equal to 1260 MPa, the dynamic plastic strain is greater than or equal to 0.46, and the dynamic impact absorption energy is greater than or equal to 579 J / cm 3 under the condition of 10 ‑1 s 3 grade strain rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium alloy materials and bar processing, and particularly relates to a high plasticity and toughness low-gap titanium alloy and a bar preparation method thereof. BACKGROUND

[0002] Titanium alloy has become a key material for lightening and high performance of modern weapon equipment due to its small density, high specific strength and excellent comprehensive performance. The missile warhead is the core damage unit of the missile, and the titanium alloy material can significantly improve the charge ratio and damage power of the warhead.

[0003] The warhead shell material needs to have the ability to resist projectile deformation, high plasticity strain to absorb impact energy and high toughness to prevent brittle fracture in microseconds during penetration. In the case of instantaneous overload, the warhead shell needs to suppress strength attenuation and adiabatic shear instability. Therefore, the design of the warhead shell material needs to consider not only dynamic rheological stress and dynamic plastic strain, but also fracture toughness, impact toughness and high temperature stability, so as to improve the penetration ability of the missile warhead.

[0004] The specific strength (strength / density) of early titanium alloy (such as TC4) is improved by 50% compared with steel material, which is significantly lightened, and the theoretical charge coefficient can be improved to 35%. However, it is prone to adiabatic shear failure at high strain rate, and the dynamic strength is insufficient, so the target test is prone to fracture, which is difficult to meet the development needs of missiles. The existing TA15 and other warhead titanium alloys only consider the room temperature dynamic performance in the design, and do not pay attention to the high temperature dynamic performance. The high temperature dynamic performance is poor, and the plasticity and toughness are insufficient, which leads to brittle fracture during penetration, and seriously restricts the upgrading and replacement needs of new equipment.

[0005] Meanwhile, there are technical problems of difficulty in controlling alloy composition and uniformity of ingot composition in the preparation process of high plasticity and toughness titanium alloy. During the mixing process, the powder alloy is easy to be contaminated on the inner wall or lost in the form of dust, which affects the accuracy of the ingot composition and the uneven distribution of the powder intermediate alloy in the consumable electrode. In the welding process, if the length of the weld is long, stress concentration and weld cracking are prone to occur at the splicing joint, and in the subsequent melting process, the phenomenon of dropping pieces or blocks is prone to occur at the weld position, thereby affecting the composition uniformity of the material.

[0006] Therefore, it is urgent to develop a high plasticity and toughness titanium alloy material with innovative composition and an optimized preparation process to meet the needs of the new generation of missile warheads. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art and provide a high plasticity and toughness low-gap titanium alloy and a bar preparation method thereof.

[0008] To achieve the above object, the present application provides the following technical solutions.

[0009] In one aspect, the present application provides a high plasticity and toughness low-interstitial titanium alloy, which is composed of the following components in mass percentage: Al: 5.5-7.0%, Mo: 1.5-2.4%, V: 2.1-3.0%, Zr: 2.1-3.0%, Sn≤2%, Si≤0.02%, O≤0.075%, C≤0.01%, N<0.003%, H≤0.005%, and the balance being Ti, wherein the sum of the mass percentages of the above components is 100%.

[0010] In another aspect, the present application provides a method for preparing a high plasticity and toughness low-interstitial titanium alloy rod, which comprises the following steps:

[0011] Step 1: aluminum-molybdenum alloy powder, aluminum-vanadium alloy powder, titanium sponge, zirconium sponge, high-purity aluminum, and tin-titanium alloy are weighed as raw materials according to the mass percentage, and the aluminum-molybdenum alloy powder and the aluminum-vanadium alloy powder are mixed uniformly in a closed mixing bin, then wrapped with a customized high-purity aluminum foil to form N alloy packages, and then the titanium sponge, the zirconium sponge, the high-purity aluminum, the tin-titanium alloy, and the alloy packages are placed in a drying oven for drying for 1-4 hours; wherein N is an integer greater than zero.

[0012] It should be noted that the titanium sponge is a 0-grade titanium sponge with a purity of ≥99.65%, and the purity of the high-purity aluminum, the zirconium sponge, the aluminum-molybdenum alloy powder, the aluminum-vanadium alloy powder, and the tin-titanium alloy is all ≥99.9%; the high-purity aluminum is selected as an aluminum bean, and the tin-titanium alloy is selected as a tin-titanium alloy particle with a particle size of 5-15 mm; the particle size of the aluminum-molybdenum alloy powder is 0.5-2 mm, and the particle size of the aluminum-vanadium alloy powder is 0.5-2 mm.

[0013] Low-interstitial control principle: common impurity elements such as O, N, C, H, and Si in titanium alloy will form interstitial / substitutional solid solution with titanium, which can improve the strength of titanium, but will cause a serious decrease in the plasticity and toughness of the titanium alloy, and will accelerate the fatigue crack propagation rate, and will make the thermal stability, creep resistance, and notch sensitivity worse. Especially, the strong solid solution element O significantly affects the initiation and propagation of cracks. Therefore, the present application specially controls the interstitial elements, adopts a low-interstitial composition design to improve the plasticity and toughness of the alloy. The purpose of using high-purity Al with a purity of >99.9% (the traditional Al purity is 99.5%) and 0-grade titanium sponge in the present application is to purify the ingot, thereby improving the plasticity and toughness of the alloy.

[0014] In addition, in step 1, the mixed powder of the aluminum-molybdenum alloy powder and the aluminum-vanadium alloy powder is coated with a customized high-purity aluminum foil, which can avoid the loss of the interstitial alloy in the mixing and pressing process.

[0015] Step 2, first divide the sponge titanium into at least five parts, mix the first part of the sponge titanium with the sponge zirconium uniformly to form the first mixture, mix the second part of the sponge titanium with high-purity aluminum and N alloy packages uniformly to form the second mixture, mix the third part of the sponge titanium with a tin-titanium alloy uniformly to form the third mixture, then combine the remaining parts of the sponge titanium with the first mixture, the second mixture and the third mixture in a mixed material manner to obtain a pre-pressed material, and finally press the pre-pressed material into a consumable electrode block and place it in a drying box for drying;

[0016] By dividing the sponge titanium into five parts and mixing them with sponge zirconium, high-purity aluminum, tin-titanium alloy and alloy packages, the uniformity of the distribution of various raw materials in the consumable electrode block can be improved through mixed material, so that the ingot composition accuracy is higher and the ingot composition uniformity is higher.

[0017] Step 3, first assemble the consumable electrode block into an unwelded consumable electrode on the fastening material rack, then extrude all the consumable electrode blocks through the clamping devices at both ends of the material rack until the gap between the consumable electrode blocks is ≤2.5mm to ensure that the consumable electrode blocks are tightly assembled and reduce the middle weld of the consumable electrode; before welding, vacuumize to a vacuum degree below 1.5Pa, load a single consumable electrode into a plasma welding box and vacuumize, then fill argon into the plasma welding box; adjust the plasma welding gun to be located at an arc striking position, start welding along the transverse joint gap of the consumable electrode, and stop welding 40-60mm before the cross joint gap position; then complete the welding of the "L-shaped" weld along the longitudinal direction and stop welding, then move the plasma welding gun to the center of the transverse weld 40-60mm away from the longitudinal weld to perform transverse welding, thus completing the breakpoint welding of one cross joint gap; complete the welding of all cross joint gaps on one side of the single consumable electrode in the same way, cool for 1h, rotate the material rack, complete the welding of all cross joint gaps on the other side, cool for more than 1.5h under the protection of argon in the plasma welding box, and finally obtain the consumable electrode; the total cooling time is more than 2.5h, clean the spatters and weld beads on the consumable electrode in time after taking out from the welding box, then place the consumable electrode into a drying box for drying;

[0018] It should be further pointed out that, since the assembly length of the consumable electrode is generally long during the welding process of the consumable electrode, the clamp and the material rack will have certain deformation behavior, and the clamping force and the deformation force will be converted into internal stress after the assembled consumable electrode is welded, since the gap element content is reduced by increasing the clamping force and the deformation force in the present application, the internal stress is increased, and the traditional "cross-shaped" welding method is easy to cause cracking of the weld, therefore the "L-shaped" welding method is selected, so that the transverse through cracks can be eliminated and the dropping or chipping phenomenon at the weld position during the melting process can be prevented.

[0019] Step 4, welding the dried consumable electrode with the same brand auxiliary electrode in a vacuum consumable arc furnace to obtain a primary consumable electrode, and after completely removing the spatter and welding tumor generated by the welding, performing first-time smelting on the primary consumable electrode, and obtaining a primary ingot after first-time cooling in the furnace; after peeling the two primary ingots, performing in-furnace welding in a vacuum furnace, performing second-time smelting, and obtaining a secondary ingot after second-time cooling in the furnace, and after peeling the secondary ingot, performing third-time smelting, and obtaining a finished ingot after third-time cooling in the furnace;

[0020] It should be noted that the vacuum degree during smelting is required to be ≤1 Pa, the smelting current is 10-30 kA, the smelting voltage is 20-45 V, the leakage rate is ≤0.8 Pa / min, the optimized vacuum arc furnace smelting parameters guarantee the uniformity and compactness of the alloy composition, and the control of the vacuum degree is conducive to the control of the O element and the prevention of O increase; the peeling depth of the primary ingot and the secondary ingot is 4-12 mm; the temperature after the first-time cooling in the furnace, the second-time cooling in the furnace and the third-time cooling in the furnace is all lower than 300℃.

[0021] The content of impurity elements in the surface layer of the ingot is extremely high, therefore, peeling the primary ingot and the secondary ingot can effectively reduce the content of impurity elements, so as to achieve the purpose of purifying the ingot.

[0022] Step 5, peeling the finished ingot first, coating an anti-oxidation layer, and then performing forging to obtain a bar blank; the purpose of coating the anti-oxidation layer during the forging process is to prevent the surface of the finished ingot from absorbing H or other harmful elements that are not conducive to plasticity and toughness during the forging process;

[0023] Step 5.1, peeling the finished ingot first, coating an anti-oxidation layer, and then placing it in a heating furnace above the phase transition point at 100-240℃ for 5-7h, and then performing 1-2 times of upsetting and drawing, with the total forging ratio of each time being 2.0-4.5, hot material is returned to the furnace after forging, and is placed in a heating furnace above the phase transition point at 50-120℃ for 2-3h, and then performing 1-2 times of upsetting and drawing, with the total forging ratio of each time being 2.0-4.5, and the forged material is air-cooled after forging to obtain a first forged blank;

[0024] Step 5.2, placing the first forged blank in a heating furnace below the phase transition point at 20-80℃ for 5-6h, and then performing 1-2 times of upsetting and drawing, with the total forging ratio of each time being controlled between 1.3 and 3, hot material is returned to the furnace after forging, and is placed in a heating furnace above the phase transition point at 50-120℃ for 3-4h, and then performing 4-7 times of upsetting and drawing, with the total forging ratio of each time being 2.0-4.5, and the forged material is air-cooled after forging to obtain a second forged blank;

[0025] Step 5.3, the second forging blank is placed into a heating furnace below the phase transition point for 6-8 hours, and then 4-7 times of finished product forging is performed, the total forging ratio of each time is controlled to be 1.1-1.5, and after the forging, air cooling is performed, so as to obtain a rod blank.

[0026] Step 6, the rod blank is coated with an oxidation-resistant coating, and then heated to 700-800 DEG C at a heating rate of 4-5 DEG C / min, and then heat treated for 1-2 hours, and then slowly furnace-cooled to obtain a high plasticity and toughness low-interstitial titanium alloy rod.

[0027] In another aspect, the application provides a high plasticity and toughness low-interstitial titanium alloy, or a high plasticity and toughness low-interstitial titanium alloy prepared by the preparation method as described above, which is detected to have an impact energy of greater than or equal to 60 J, a fracture toughness of greater than or equal to 115 MPa.m 1 / 2 , a tensile strength at 500 DEG C of greater than or equal to 850 MPa;

[0028] Under the conditions of room temperature, 10 3 s -1 , the dynamic rheological stress is greater than or equal to 1580 MPa, the dynamic plastic strain is greater than or equal to 0.33, and the dynamic impact absorption energy is greater than or equal to 520 J / cm 3 .

[0029] Under the conditions of 500 DEG C, 10 3 s -1 , the dynamic rheological stress is greater than or equal to 1260 MPa, the dynamic plastic strain is greater than or equal to 0.46, and the dynamic impact absorption energy is greater than or equal to 579 J / cm 3 .

[0030] Compared with the prior art, the technical scheme provided by the application has the following beneficial effects:

[0031] 1) The application significantly improves the fracture toughness, impact toughness and dynamic performance of the material by component design and low-interstitial control.

[0032] 2) The intermediate alloy powder is wrapped, decomposed and mixed, and the welding process is optimized, so that the loss rate of the intermediate alloy powder is effectively reduced, the composition of the ingot is more stable, and the composition uniformity is higher.

[0033] 3) The application controls the content of O, C, N and other interstitial elements in the material to a very low level through the synergistic process quality control of raw material selection, smelting, forging and heat treatment, reduces the adverse effects of these interstitial elements on the thermal stability and plasticity of the titanium alloy, and improves the deformation coordination ability of the titanium alloy, so that the plasticity and toughness of the material are improved under the condition of ensuring the strength.

[0034] 4) The designed forging and heat treatment process can obtain high equiaxed structure with high alpha phase content, and high plasticity and toughness low interstitial titanium alloy rod with excellent performance, impact energy ≥ 60J, fracture toughness ≥ 115MPa·m 1 / 2 , tensile strength ≥ 850MPa at 500℃; under the condition of room temperature, 10 3 s -1 , dynamic rheological stress ≥ 1580MPa, dynamic plastic strain ≥ 0.33, dynamic impact absorption energy ≥ 520J / cm 3 under the condition of 10 3 s -1 grade strain rate, dynamic rheological stress ≥ 1260MPa, dynamic plastic strain ≥ 0.46, dynamic impact absorption energy ≥ 579J / cm 3 . BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings incorporated in and forming a part of the specification, illustrate the embodiments of the present application and, together with the description, serve to explain the principles of the application.

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0037] Figure 1 The flow chart of the preparation method of the present application is shown in the figure.

[0038] Figure 2 The microstructure of the titanium alloy rod A1 prepared in Example 1 is shown in the figure. DETAILED DESCRIPTION

[0039] Hereinafter, the exemplary embodiments will be described in detail with reference to the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. Rather, they are merely examples consistent with some aspects of the present application, as detailed in the appended claims.

[0040] In order to enable those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the accompanying drawings and examples.

[0041] In order to prove the effect of the rod preparation method of the present application, the following examples and comparative examples are provided for verification.

[0042] The element composition of the five examples and two comparative examples provided by the present application is shown in Table 1.

[0043] Table 1 Comparison of components of Examples 1-5 and Comparative Examples 1-2 of the present application

[0044] Ingredients Al％ Mo % V％ Zr％ Sn % Si % O％ C％ N％ H％ Example 1 6.8 1.8 3.0 2.3 1.5 0.007 0.046 0.010 ＜0.003 0.0023 Example 2 6.3 1.5 2.2 2.1 1.5 0.005 0.051 0.004 ＜0.003 0.0035 Example 3 7.0 2.4 2.1 2.3 1.6 0.009 0.075 0.006 ＜0.003 0.0050 Example 4 5.5 1.7 2.4 3.0 2.0 0.020 0.051 0.007 ＜0.003 0.0012 Example 5 6.1 2.3 2.1 2.6 1.6 0.012 0.065 0.005 ＜0.003 0.0024 Comparative Example 1 7.5 2.6 3.4 3.6 3.0 0.020 0.074 0.004 ＜0.003 0.0034 Comparative Example 2 4.8 2.2 2.5 2.4 1.3 0.011 0.085 0.005 ＜0.003 0.0041

[0045] Example 1

[0046] Referring to Figure 1 The embodiment provides a high-plasticity and high-toughness low-interstitial titanium alloy rod preparation method, and specifically comprises the following steps:

[0047] Step 1: taking 0-grade sponge titanium with a purity of greater than or equal to 99.65%, aluminum-molybdenum alloy powder, sponge zirconium, aluminum-vanadium alloy powder, tin-titanium alloy and high-purity aluminum with a purity of greater than or equal to 99.9% as raw materials, the raw materials are weighed according to mass percentage, the aluminum-molybdenum alloy powder and the aluminum-vanadium alloy powder are uniformly mixed in a closed mixing bin, then the N alloy packages are wrapped with customized high-purity aluminum foil, and finally the sponge titanium, the sponge zirconium, the high-purity aluminum, the tin-titanium alloy and the alloy packages are placed in a drying box and dried for 1-4 hours; wherein N is an integer greater than zero.

[0048] Step 2: the sponge titanium is first divided into at least five parts, the first part of the sponge titanium is uniformly mixed with the sponge zirconium to form a first mixture, the second part of the sponge titanium is uniformly mixed with the high-purity aluminum and the N alloy packages to form a second mixture, the third part of the sponge titanium is uniformly mixed with the tin-titanium alloy to form a third mixture, then the remaining parts of the sponge titanium are combined with the first mixture, the second mixture and the third mixture in a mixed manner to obtain a pre-pressed material, and finally the pre-pressed material is pressed into a consumable electrode block and placed in a drying box for drying.

[0049] Step 3, first, the consumable electrode blocks are assembled into an unwelded consumable electrode on the fastening rack, and then all the consumable electrode blocks are extruded through the clamping devices at both ends of the rack until the gap between the consumable electrode blocks is ≤2.5 mm, so as to ensure that the consumable electrode blocks are tightly assembled and the middle weld of the consumable electrode is reduced; before welding, vacuumizing to a vacuum degree below 1.5 Pa, loading the single consumable electrode into the plasma welding box and vacuumizing, and then filling argon into the plasma welding box; adjusting the plasma welding gun to be located at the arc striking position, starting welding along the transverse joint gap of the consumable electrode, and stopping the arc 40-60 mm before the cross joint gap position; then, completing the welding of the "L-shaped" weld along the longitudinal direction and stopping the arc, then moving the plasma welding gun to the center of the transverse weld 40-60 mm away from the longitudinal weld to perform transverse welding, thus completing the breakpoint welding of one cross joint gap; using the same method to complete the welding of all the cross joint gaps on one side of the single consumable electrode, after cooling for 1 h, rotating the rack to complete the welding of all the cross joint gaps on the other side; cooling for more than 1.5 h under the protection of argon in the plasma welding box and discharging from the furnace to finally obtain the consumable electrode, the total cooling time is more than 2.5 h, and the spatters and welds on the consumable electrode are cleaned in time after discharging from the welding box, then the consumable electrode is placed into a drying box for drying;

[0050] Step 4, the consumable electrode is vacuum consumable arc melted into 2 finished ingots for three times, and the specific melting process is as follows: welding the dried consumable electrode with the auxiliary electrode of the same grade in the vacuum consumable arc furnace to obtain a primary consumable electrode, and after completely removing the spatters and welds generated during welding, the primary consumable electrode is subjected to first melting, and the primary ingot is obtained after first in-furnace cooling; after peeling the two primary ingots, in-furnace welding is performed in the vacuum furnace for second melting, and the secondary ingot is obtained after second in-furnace cooling; after peeling the secondary ingot, third melting is performed, and the finished ingot is obtained after third in-furnace cooling; the vacuum degree is ≤0.90 Pa, the melting current is 15-22 kA, the melting voltage is 20-35 V, and the leakage rate is ≤0.5 Pa / min, and the ingot discharge temperature after the first in-furnace cooling, the second in-furnace cooling and the third in-furnace cooling is lower than 270℃;

[0051] In step 4, the first finished ingot is subjected to peeling treatment during melting;

[0052] The second finished ingot is not subjected to peeling treatment during melting;

[0053] The two finished ingots are respectively subjected to peeling, flaw detection and sprue sawing, and then the two finished ingots are respectively sampled for chemical composition detection, and the detection results are shown in Table 2;

[0054] Table 2 Chemical composition detection results of finished ingots (wt.%)

[0055]

[0056] Step 5, the two finished ingots are peeled and coated with an oxidation-resistant layer, and then forged to obtain two billets, specifically:

[0057] Step 5.1, the finished ingot is first peeled, then coated with an oxidation-resistant coating, then placed in a heating furnace above the phase transition point at 160-220°C for 5h, and then subjected to 2 times of upsetting and drawing, with a total forging ratio of 2.0-3.0 each time, and then hot material is returned to the furnace after forging, placed in a heating furnace above the phase transition point at 90-120°C for 3h, and then subjected to 2 times of upsetting and drawing, with a total forging ratio of 2.0-3.5 each time, and then air-cooled after forging to obtain a first forged billet;

[0058] Step 5.2, the first forged billet is placed in a heating furnace below the phase transition point at 50°C for 5h, and then subjected to 1 time of upsetting and drawing, with a total forging ratio of about 2.4 each time, and then hot material is returned to the furnace after forging, placed in a heating furnace above the phase transition point at 80-120°C for 4h, and then subjected to 6 times of upsetting and drawing, with a total forging ratio of 2.0-3.5 each time, and then air-cooled after forging to obtain a second forged billet;

[0059] Step 5.3, the second forged billet is placed in a heating furnace below the phase transition point at 30-80°C for 8h, and then subjected to 5 times of finished forging, with a total forging ratio of 1.2-1.5 each time, and then air-cooled after forging to obtain a billet.

[0060] Step 6, the billet is first coated with an oxidation-resistant coating, and then heat-treated at a heating rate of 5°C / min to 700°C for 2h, and then slowly furnace-cooled to obtain a finished titanium alloy rod A1 (peeled from the first ingot and the second ingot) and a finished titanium alloy rod A2 (not peeled from the first ingot and the second ingot) with high plasticity and toughness and low interstitial gaps after machining.

[0061] Referring to Figure 2 , it can be seen from the figure that the microstructure of the finished rod A1 is uniform.

[0062] Example 2

[0063] Referring to Figure 1 , the present embodiment provides a method for preparing a titanium alloy rod with high plasticity and toughness and low interstitial gaps, specifically including the following steps:

[0064] Step 1, taking the grade 0 sponge titanium with purity ≥ 99.65%, the aluminum molybdenum alloy powder, the sponge zirconium, the aluminum vanadium alloy powder, the tin titanium alloy, and the high-purity aluminum with purity ≥ 99.9% as raw materials, taking the raw materials according to the mass percentage, mixing the aluminum molybdenum alloy powder and the aluminum vanadium alloy powder uniformly in a closed mixing bin, then wrapping the alloy package with a customized high-purity aluminum foil, and then putting the sponge titanium, the sponge zirconium, the high-purity aluminum, the tin titanium alloy, and the alloy package into a drying box and drying for 4h; wherein N is an integer greater than zero;

[0065] Step 2, first dividing the sponge titanium into at least five parts, mixing the first part of the sponge titanium with the sponge zirconium uniformly to form a first mixture, mixing the second part of the sponge titanium with the high-purity aluminum and the N alloy packages uniformly to form a second mixture, mixing the third part of the sponge titanium with the tin titanium alloy uniformly to form a third mixture, then combining the remaining parts of the sponge titanium with the first mixture, the second mixture, and the third mixture in a mixed manner to obtain a pre-pressed material, and finally pressing the pre-pressed material into a consumable electrode block and placing it in a drying box for drying;

[0066] Step 3, first assembling the consumable electrode block into an unwelded consumable electrode on a fastening material rack, then extruding all the consumable electrode blocks through the clamping devices at both ends of the material rack until the gap between the consumable electrode blocks is ≤ 2.5mm to ensure that the consumable electrode blocks are tightly assembled and reduce the middle weld of the consumable electrode; before welding, vacuumizing to a vacuum degree below 1.5Pa, placing a single consumable electrode into a plasma welding box and vacuumizing, then filling argon into the plasma welding box; adjusting the plasma welding gun to be located at an arc striking position, starting to weld along the transverse joint gap of the consumable electrode, and stopping the arc at 40-60mm before the cross joint gap position; then completing the welding of the "L-shaped" weld along the longitudinal direction and stopping the arc, then moving the plasma welding gun to the center of the transverse weld 40-60mm away from the longitudinal weld to perform transverse welding, thus completing the breakpoint welding of one cross joint gap; using the same method to complete the welding of all cross joint gaps on one side of the single consumable electrode, cooling for 1h, rotating the material rack, and completing the welding of all cross joint gaps on the other side; cooling for 1.5h or more under the protection of argon in the plasma welding box and discharging the final consumable electrode, the total cooling time being 2.5h or more; cleaning the spatters and welds on the consumable electrode in time after discharging from the welding box, then placing the consumable electrode into a drying box for drying;

[0067] Step 4, welding the dried consumable electrode with the same grade auxiliary electrode in a vacuum consumable arc furnace to obtain a primary consumable electrode, and after completely removing the spatter and welding tumor generated by the welding, performing first-time smelting on the primary consumable electrode, and obtaining a primary ingot after first-time furnace cooling; after peeling the two primary ingots, performing in-furnace welding in a vacuum furnace, performing second-time smelting, and obtaining a secondary ingot after second-time furnace cooling; after peeling the secondary ingot, performing third-time smelting, and obtaining a finished ingot after third-time furnace cooling; the vacuum degree is ≤0.92 Pa, the smelting current is 10-20 kA, the smelting voltage is 25-42 V, the leakage rate is ≤0.6 Pa / min, and the ingot out-of-furnace temperature after the first-time furnace cooling, the second-time furnace cooling and the third-time furnace cooling is lower than 300℃;

[0068] Peeling, flaw detection and sprue sawing are performed on the finished ingot, and then chemical component detection is performed on the finished ingot sample, and the detection results are shown in Table 3;

[0069] Table 3: Chemical component detection results of the finished ingot (wt. %)

[0070]

[0071] Step 5, after peeling and coating an anti-oxidation layer, the finished ingot is forged to obtain a bar blank, specifically:

[0072] Step 5.1, first, peeling the finished ingot, coating an anti-oxidation layer, then placing it in a heating furnace above the phase transition point at 100-180℃ for 5h, and then performing 2 times of upsetting and drawing, with a total forging ratio of 2.6-3.8 for each time, hot material is returned to the furnace after forging, and is placed in a heating furnace above the phase transition point at 85-110℃ for 3h, and then performing 2 times of upsetting and drawing, with a total forging ratio of 2.0-3.8 for each time, and air cooling after forging to obtain a first forged blank;

[0073] Step 5.2, placing the first forged blank in a heating furnace below the phase transition point at 65℃ for 6h, and performing 1 time of upsetting and drawing, with a total forging ratio of about 1.3 for each time, hot material is returned to the furnace after forging, and is placed in a heating furnace above the phase transition point at 70-120℃ for 3h, and then performing 5 times of upsetting and drawing, with a total forging ratio of 3.0-4.5 for each time, and air cooling after forging to obtain a second forged blank;

[0074] Step 5.3, placing the second forged blank in a heating furnace below the phase transition point at 40-100℃ for 6h, and performing 6 times of finished forging, with a total forging ratio of 1.1-1.4 for each time, and air cooling after forging to obtain a bar blank.

[0075] Step 6, the rod blank is coated with an oxidation-resistant coating, and then heat treated at a heating rate of 4℃ / min to 700℃ for 2h, and then slowly furnace-cooled to obtain a finished rod B of the high plasticity and toughness low-interstitial titanium alloy.

[0076] Example 3

[0077] Referring to Figure 1 As shown in the figure, the embodiment provides a method for preparing a high plasticity and toughness low-interstitial titanium alloy rod, which specifically comprises the following steps:

[0078] Step 1, using titanium sponge with a purity of ≥99.65%, aluminum-molybdenum alloy powder, sponge zirconium, aluminum-vanadium alloy powder, tin-titanium alloy, and high-purity aluminum with a purity of ≥99.9% as raw materials, the raw materials are weighed according to the mass percentage, and the aluminum-molybdenum alloy powder and the aluminum-vanadium alloy powder are mixed uniformly in a closed mixing bin, then wrapped with a customized high-purity aluminum foil into N alloy packages, and then the titanium sponge, the sponge zirconium, the high-purity aluminum, the tin-titanium alloy, and the alloy packages are placed in a drying oven for drying for 1-4h; wherein N is an integer greater than zero.

[0079] Step 2, the titanium sponge is first divided into at least five parts, the first part of the titanium sponge is mixed uniformly with the sponge zirconium to form a first mixture, the second part of the titanium sponge is mixed uniformly with the high-purity aluminum and the N alloy packages to form a second mixture, the third part of the titanium sponge is mixed uniformly with the tin-titanium alloy to form a third mixture, then the remaining parts of the titanium sponge are combined with the first mixture, the second mixture, and the third mixture in a mixed manner to obtain a pre-pressed material, and finally the pre-pressed material is pressed into a consumable electrode block and placed in a drying oven for drying.

[0080] Step 3, first, the consumable electrode blocks are assembled into an unwelded consumable electrode on the fastening rack, then all the consumable electrode blocks are extruded through the clamping devices at both ends of the rack until the gap between the consumable electrode blocks is ≤2.5mm, so as to ensure that the consumable electrode blocks are tightly assembled and the middle weld of the consumable electrode is reduced; before welding, vacuumize to a vacuum degree below 1.5Pa, put the single consumable electrode into the plasma welding box and vacuumize, then fill argon into the plasma welding box; adjust the plasma welding gun to be at the arc striking position, start welding along the transverse joint gap of the consumable electrode, and stop welding 40-60mm before the cross joint gap position; then complete the welding of the "L-shaped" weld along the longitudinal direction and stop welding, then move the plasma welding gun to the center of the transverse weld 40-60mm away from the longitudinal weld to perform transverse welding, thus completing the breakpoint welding of one cross joint gap; complete the welding of all the cross joint gaps on one side of the single consumable electrode in the same way, cool for 1h, rotate the rack, and complete the welding of all the cross joint gaps on the other side; cool for 1.5h or above under the protection of argon in the plasma welding box and take out the furnace to obtain the consumable electrode, the total cooling time is 2.5h or above, clean the spatters and weld beads on the consumable electrode in time after taking out the welding box, then put the consumable electrode into the drying box for drying;

[0081] Step 4, weld the dried consumable electrode with the auxiliary electrode of the same grade in the vacuum consumable arc furnace to obtain a primary consumable electrode, remove the spatters and weld beads generated during welding, and perform first melting on the primary consumable electrode, obtain a primary ingot after first cooling in the furnace; perform in-furnace welding on the two primary ingots after skinning, perform second melting, and obtain a secondary ingot after second cooling in the furnace; perform third melting on the secondary ingot after skinning, and obtain a finished ingot after third cooling in the furnace; the vacuum degree is ≤1Pa, the melting current is 18-30kA, the melting voltage is 25-40V, and the leakage rate is ≤0.8Pa / min; the finished ingot after first cooling in the furnace, second cooling in the furnace and third cooling in the furnace is taken out of the furnace at a temperature below 300℃;

[0082] Skin the finished ingot, perform flaw detection and saw cutting of the riser, then sample the finished ingot for chemical composition detection, and the detection results are shown in Table 4;

[0083] Table 4: Chemical composition detection results of the finished ingot (wt. %)

[0084]

[0085] Step 5, skin the finished ingot, coat an anti-oxidation layer, and then perform forging to obtain a bar blank, specifically:

[0086] Step 5.1, first, the finished ingot is peeled, then the anti-oxidation coating is coated, then it is placed in a heating furnace above the phase transition point at 180℃ for 5h, then it is forged for 1 fire, the total forging ratio of each fire is 4.5, after forging, the hot material is returned to the furnace, it is placed in a heating furnace above the phase transition point at 80-100℃ for 2h, then it is forged for 2 fires, the total forging ratio of each fire is 2.0-3.5, after forging, it is air-cooled, to obtain a first forged blank;

[0087] Step 5.2, the first forged blank is placed in a heating furnace below the phase transition point at 80℃ for 6h, it is forged for 1 fire, the total forging ratio is controlled at 2.5, after forging, the hot material is returned to the furnace, it is placed in a heating furnace above the phase transition point at 50-90℃ for 3h, it is forged for 5 fires, the total forging ratio of each fire is 3.0-4.2, after forging, it is air-cooled, to obtain a second forged blank;

[0088] Step 5.3, the second forged blank is placed in a heating furnace below the phase transition point at 50-120℃ for 6h, it is finished forging for 4 fires, the total forging ratio of each fire is controlled at 1.3-1.5, after forging, it is air-cooled, to obtain a rod blank.

[0089] Step 6, first, the rod blank is coated with an anti-oxidation coating, then it is heated at a heating rate to 750℃ for 1h for heat treatment, and then it is slowly furnace-cooled to obtain a high-plasticity and high-toughness low-interstitial titanium alloy finished rod C.

[0090] Example 4

[0091] Referring to Figure 1 The embodiment provides a high-plasticity and high-toughness low-interstitial titanium alloy rod preparation method, and specifically comprises the following steps:

[0092] Step 1, 0-grade sponge titanium with a purity of ≥99.65%, aluminum-molybdenum alloy powder, sponge zirconium, aluminum-vanadium alloy powder, tin-titanium alloy and high-purity aluminum with a purity of ≥99.9% are used as raw materials, the raw materials are weighed according to mass percentage, the aluminum-molybdenum alloy powder and the aluminum-vanadium alloy powder are uniformly mixed in a closed mixing bin, then wrapped with customized high-purity aluminum foil into N alloy packages, and then the sponge titanium, the sponge zirconium, the high-purity aluminum, the tin-titanium alloy and the alloy packages are placed in a drying box for drying for 4h; wherein N is an integer greater than zero.

[0093] Step 2, first, the sponge titanium is evenly divided into at least five parts, the first part of the sponge titanium is uniformly mixed with the sponge zirconium to form a first mixture, the second part of the sponge titanium is uniformly mixed with the high-purity aluminum and the N alloy packages to form a second mixture, the third part of the sponge titanium is uniformly mixed with the tin-titanium alloy to form a third mixture, then the remaining parts of the sponge titanium are combined with the first mixture, the second mixture and the third mixture in a mixed manner to obtain a pre-pressed material, and finally the pre-pressed material is pressed into a consumable electrode block and placed in a drying box for drying.

[0094] Step 3, first, the consumable electrode blocks are assembled into an unwelded consumable electrode on the fastening rack, then all the consumable electrode blocks are extruded through the clamping devices at both ends of the rack until the gap between the consumable electrode blocks is ≤2.5mm, to ensure that the consumable electrode blocks are tightly assembled and to reduce the weld in the middle of the consumable electrode; before welding, vacuumize to a vacuum degree below 1.5Pa, put the single consumable electrode into the plasma welding box and vacuumize, then fill argon into the plasma welding box; adjust the plasma welding gun to be at the arc striking position, start welding along the transverse joint gap of the consumable electrode, and stop the arc 40-60mm before the cross joint gap position; then complete the welding of the "L-shaped" weld along the longitudinal direction and stop the arc, then move the plasma welding gun to the center of the transverse weld 40-60mm away from the longitudinal weld to weld transversely, thus completing the breakpoint welding of one cross joint gap; weld all the cross joint gaps on one side of the single consumable electrode in the same way, cool for 1h, rotate the rack, and weld all the cross joint gaps on the other side; cool for 1.5h or above under the protection of argon in the plasma welding box and take out the furnace to obtain the consumable electrode, the total cooling time is 2.5h or above, clean the spatters and weld bumps on the consumable electrode in time after taking out the welding box, then put the consumable electrode into the drying box for drying;

[0095] Step 4, weld the dried consumable electrode with the auxiliary electrode of the same grade in the vacuum consumable arc furnace to obtain a primary consumable electrode, remove the spatters and weld bumps generated during welding, and then perform the first melting of the primary consumable electrode, obtain a primary ingot after the first in-furnace cooling; skin the two primary ingots and perform in-furnace welding in the vacuum furnace, perform the second melting, and obtain a secondary ingot after the second in-furnace cooling; skin the secondary ingot, perform the third melting, and obtain a finished ingot after the third in-furnace cooling; the vacuum degree is ≤0.93Pa, the melting current is 10-20kA, the melting voltage is 25-40V, and the leakage rate is ≤0.6Pa / min; the temperature of the ingot after the first in-furnace cooling, the second in-furnace cooling and the third in-furnace cooling is lower than 300℃;

[0096] Skin the finished ingot, perform flaw detection and saw cutting of the riser, then sample the finished ingot for chemical composition detection, and the detection results are shown in Table 5;

[0097] Table 5: Chemical composition detection results of the finished ingot (wt. %)

[0098]

[0099] Step 5, skin the finished ingot, coat an anti-oxidation layer, and then perform forging to obtain a bar blank, specifically:

[0100] Step 5.1, first, the finished ingot is peeled, then the anti-oxidation coating is coated, then it is placed in a heating furnace above the phase transition point at 240 DEG C for 5.5 h, then it is subjected to 1 fire upsetting, the total forging ratio of each fire is 4.5, after forging, the hot material is returned to the furnace, it is placed in a heating furnace above the phase transition point at 50 DEG C for 3 h, then it is subjected to 1 fire upsetting, the total forging ratio of each fire is 4.5, after forging, it is air-cooled, to obtain a first forging blank;

[0101] Step 5.2, the first forging blank is placed in a heating furnace below the phase transition point at 20 DEG C for 6 h, it is subjected to 1 fire upsetting, the total forging ratio of each fire is controlled between 3, after forging, the hot material is returned to the furnace, it is placed in a heating furnace above the phase transition point at 80-120 DEG C for 3 h, it is subjected to 7 fires upsetting, the total forging ratio of each fire is 2.0-3.0, after forging, it is air-cooled, to obtain a second forging blank;

[0102] Step 5.3, the second forging blank is placed in a heating furnace below the phase transition point at 20-40 DEG C for 6-7 h, it is subjected to 7 fires finished forging, the total forging ratio of each fire is controlled at 1.1-1.5, after forging, it is air-cooled, to obtain a rod blank.

[0103] Step 6, first, the rod blank is coated with an anti-oxidation coating, then it is subjected to heat treatment at a heating rate of 4.5 DEG C / min, heated to 760 DEG C for 2 h, slowly furnace-cooled, to obtain a finished rod D of high plasticity and toughness low interstitial titanium alloy.

[0104] Example 5

[0105] Referring to Figure 1 The embodiment provides a high plasticity and toughness low interstitial titanium alloy rod preparation method, and specifically comprises the following steps:

[0106] Step 1, 0-grade sponge titanium with a purity of greater than or equal to 99.65%, aluminum molybdenum alloy powder, sponge zirconium, aluminum vanadium alloy powder, tin titanium alloy and high-purity aluminum with a purity of greater than or equal to 99.9% are used as raw materials, the raw materials are weighed according to mass percentage, the aluminum molybdenum alloy powder and the aluminum vanadium alloy powder are uniformly mixed in a closed mixing bin, then wrapped into N alloy packages by using a customized high-purity aluminum foil, and then the sponge titanium, the sponge zirconium, the high-purity aluminum, the tin titanium alloy and the alloy packages are placed in a drying box and dried for 4 h; wherein N is an integer greater than zero.

[0107] Step 2, first, the sponge titanium is evenly divided into at least five parts, the first part of the sponge titanium is uniformly mixed with the sponge zirconium to form a first mixture, the second part of the sponge titanium is uniformly mixed with the high-purity aluminum and the N alloy packages to form a second mixture, the third part of the sponge titanium is uniformly mixed with the tin titanium alloy to form a third mixture, then the remaining parts of the sponge titanium are combined with the first mixture, the second mixture and the third mixture in a mixed manner to obtain a pre-pressed material, and finally the pre-pressed material is pressed into a consumable electrode block and placed in a drying box for drying.

[0108] Step 3, first, the consumable electrode blocks are assembled into an unwelded consumable electrode on the fastening rack, and then all the consumable electrode blocks are extruded through the clamping devices at both ends of the rack until the gap between the consumable electrode blocks is ≤2.5 mm, so as to ensure that the consumable electrode blocks are tightly assembled and the middle weld of the consumable electrode is reduced; before welding, vacuumize to a vacuum degree below 1.5 Pa, load the single consumable electrode into the plasma welding box and vacuumize, and then fill argon into the plasma welding box; adjust the plasma welding gun to be located at the arc striking position, start welding along the transverse joint gap of the consumable electrode, and stop the arc 40-60 mm before the cross joint gap position; then complete the welding of the "L-shaped" weld along the longitudinal direction and stop the arc, then move the plasma welding gun to the center of the transverse weld 40-60 mm away from the longitudinal weld to perform transverse welding, thus completing the breakpoint welding of one cross joint gap; weld all the cross joint gaps on one side of the single consumable electrode by the same method, cool for 1 h, rotate the rack, and complete the welding of all the cross joint gaps on the other side; cool for 1.5 h or more under the protection of argon in the plasma welding box, and take out the final consumable electrode; the total cooling time is 2.5 h or more; clean the spatters and weld bumps on the consumable electrode in time after taking out the consumable electrode from the welding box, and then place the consumable electrode in a drying box for drying;

[0109] Step 4, weld the dried consumable electrode with the auxiliary electrode of the same grade in the vacuum consumable arc furnace to obtain a primary consumable electrode, remove the spatters and weld bumps generated during welding, and then perform first melting on the primary consumable electrode, and obtain a primary ingot after first cooling in the furnace; skin the two primary ingots, weld them in the vacuum furnace, perform second melting, and obtain a secondary ingot after first cooling in the furnace; skin the secondary ingot, perform third melting, and obtain a finished ingot after third cooling in the furnace; the vacuum degree is ≤0.95 Pa, the melting current is 10-25 kA, the melting voltage is 28-45 V, the outgassing rate is ≤0.7 Pa / min, and the temperature of the ingot after first cooling in the furnace, second cooling in the furnace and third cooling in the furnace is lower than 290℃;

[0110] Skin the finished ingot, perform flaw detection and saw cutting of the riser, then sample the finished ingot for chemical composition detection, and the detection results are shown in Table 6;

[0111] Table 6 Chemical composition detection results of the finished ingot (wt. %)

[0112]

[0113] Step 5, skin the finished ingot, coat an anti-oxidation layer, and then perform forging to obtain a bar blank, specifically as follows:

[0114] Step 5.1, first, the finished ingot is peeled, then the coating of the antioxidant coating is coated, then it is placed in a heating furnace above the phase transition point of 130-140℃ for 6.5h, then it is subjected to 2 times of upsetting and drawing, the total forging ratio of each fire is 2.0-3.5, after forging, the hot material is returned to the furnace, it is placed in a heating furnace above the phase transition point of 100℃ for 2h, then it is subjected to 1 time of upsetting and drawing, the total forging ratio of each fire is 4.2, after forging, it is air-cooled, to obtain a first forging blank;

[0115] Step 5.2, the first forging blank is placed in a heating furnace below the phase transition point of 80℃ for 5h, it is subjected to 1 time of upsetting and drawing, the total forging ratio of each fire is controlled to be about 3, after forging, the hot material is returned to the furnace, it is placed in a heating furnace above the phase transition point of 50-80℃ for 3-4h, it is subjected to 4 times of upsetting and drawing, the total forging ratio of each fire is 3.5-4.5, after forging, it is air-cooled, to obtain a second forging blank;

[0116] Step 5.3, the second forging blank is placed in a heating furnace below the phase transition point of 60-120℃ for 6-8h, it is subjected to 7 times of finished product forging, the total forging ratio of each fire is controlled to be 1.1-1.5, after forging, it is air-cooled, to obtain a rod blank.

[0117] Step 6, first, the rod blank is coated with an antioxidant coating, then it is subjected to heat treatment at a heating rate of 5℃ / min, heated to 800℃ for 1h, slowly furnace-cooled, to obtain a high plasticity and toughness low-interstitial titanium alloy rod, slowly furnace-cooled, to obtain a finished product rod E of the high plasticity and toughness low-interstitial titanium alloy.

[0118] Comparative Example 1

[0119] Referring to Figure 1 The present comparative example provides a preparation method of a titanium alloy rod, specifically comprising the following steps:

[0120] Step 1, taking 0-grade sponge titanium with a purity of ≥99.65%, aluminum-molybdenum alloy powder, sponge zirconium, aluminum-vanadium alloy powder, tin-titanium alloy, high-purity aluminum with a purity of ≥99.9% as raw materials, the raw materials are weighed according to the mass percentage, the aluminum-molybdenum alloy powder and the aluminum-vanadium alloy powder are mixed uniformly in a closed mixing bin, then wrapped into N alloy packages using a customized high-purity aluminum foil, and then the sponge titanium, the sponge zirconium, the high-purity aluminum, the tin-titanium alloy and the alloy packages are placed in a drying box for drying for 4h; wherein N is an integer greater than zero;

[0121] Step 2, first divide the sponge titanium into at least five parts, mix the first part of the sponge titanium with the sponge zirconium uniformly to form the first mixture, mix the second part of the sponge titanium with high-purity aluminum and N alloy packages uniformly to form the second mixture, mix the third part of the sponge titanium with a tin-titanium alloy uniformly to form the third mixture, then combine the remaining parts of the sponge titanium with the first mixture, the second mixture and the third mixture in a mixed material manner to obtain a pre-pressed material, and finally press the pre-pressed material into a consumable electrode block and place it in a drying box for drying;

[0122] Step 3, first assemble the consumable electrode block into an unwelded consumable electrode on the fastening material rack, then extrude all the consumable electrode blocks through the clamping devices at both ends of the material rack until the gap between the consumable electrode blocks is ≤2.5mm to ensure that the consumable electrode blocks are tightly assembled and reduce the middle weld of the consumable electrode; before welding, vacuumize to a vacuum degree below 1.5Pa, load a single consumable electrode into a plasma welding box and vacuumize, then fill argon into the plasma welding box; adjust the plasma welding gun to be located at an arc striking position, start welding along the transverse joint gap of the consumable electrode, and stop welding 40-60mm before the cross joint gap position to perform arc collection; then complete the welding of the "L-shaped" weld along the longitudinal direction and stop the arc, then move the plasma welding gun to the center of the transverse weld 40-60mm away from the longitudinal weld to perform transverse welding, thus completing the breakpoint welding of one cross joint gap; complete the welding of all cross joint gaps on one side of the single consumable electrode in the same way, cool for 1h, rotate the material rack, complete the welding of all cross joint gaps on the other side, cool for 1.5h or more under the protection of argon in the plasma welding box, and finally obtain the consumable electrode; the total cooling time is 2.5h or more, clean the spatters and weld beads on the consumable electrode in time after taking out from the welding box, then place the consumable electrode into a drying box for drying;

[0123] Step 4, weld the dried consumable electrode with the same grade auxiliary electrode in a vacuum consumable electrode arc furnace to obtain a primary consumable electrode, completely remove the spatters and weld beads generated during welding, and then perform first smelting on the primary consumable electrode, obtain a primary ingot after first in-furnace cooling; after peeling the two primary ingots, perform in-furnace welding in a vacuum furnace, perform second smelting, and obtain a secondary ingot after second in-furnace cooling; after peeling the secondary ingot, perform third smelting, and obtain a finished ingot after third in-furnace cooling; the vacuum degree is ≤1Pa, the smelting current is 20-30kA, the smelting voltage is 20-35V, the leakage rate is ≤0.8Pa / min, and the temperature of the ingot after the first in-furnace cooling, the second in-furnace cooling and the third in-furnace cooling is lower than 300℃;

[0124] Peel the finished ingot, perform flaw detection and saw cutting of the riser, then sample the finished ingot for chemical composition detection, and the detection results are shown in Table 7;

[0125] Table 7 Chemical composition detection results of finished ingot (wt. %)

[0126]

[0127] Step 5, forging the finished ingot to obtain a rod blank, specifically:

[0128] Step 5.1, first peeling the finished ingot, then coating an oxidation-resistant coating, then placing it in a heating furnace above the phase transition point for 120°C for 7h, then performing 1 fire upsetting and drawing, with a total forging ratio of 4.2 per fire, and then hot material is returned to the furnace after forging, placed in a heating furnace above the phase transition point for 80°C for 3h, then performing 1 fire upsetting and drawing, with a total forging ratio of 4.5 per fire, and then air cooling after forging to obtain a first forging blank;

[0129] Step 5.2, placing the first forging blank in a heating furnace below the phase transition point for 40°C for 5h, performing 1 fire upsetting and drawing, with a total forging ratio controlled at about 3 per fire, and then hot material is returned to the furnace after forging, placed in a heating furnace above the phase transition point for 50-80°C for 3-4h, performing 4 fire upsetting and drawing, with a total forging ratio of 3.5-4.5 per fire, and then air cooling after forging to obtain a second forging blank;

[0130] Step 5.3, placing the second forging blank in a heating furnace below the phase transition point for 80-120°C for 6-8h, performing 5 fire finished forging, with a total forging ratio controlled at 1.1-1.4 per fire, and then air cooling after forging to obtain a rod blank.

[0131] Step 6, first coating an oxidation-resistant coating on the rod blank, and then heating at a rate of 4°C / min to 750°C for 2h for heat treatment, and then slowly furnace cooling to obtain finished rod F.

[0132] Comparative Example 2

[0133] Referring to Figure 1 The present comparative example provides a preparation method of a titanium alloy rod, specifically including the following steps:

[0134] Step 1, taking 0-grade sponge titanium with a purity of ≥99.65%, aluminum molybdenum alloy powder, sponge zirconium, aluminum vanadium alloy powder, tin titanium alloy, and high-purity aluminum with a purity of ≥99.9% as raw materials, weighing the raw materials according to the mass percentage, and then mixing the aluminum molybdenum alloy powder and the aluminum vanadium alloy powder uniformly in a closed mixing bin, wrapping them into N alloy packages with a customized high-purity aluminum foil, and then placing the sponge titanium, sponge zirconium, high-purity aluminum, tin titanium alloy, and alloy packages into a drying box for drying for 4h; wherein N is an integer greater than zero;

[0135] Step 2, first divide the sponge titanium into at least five parts, mix the first part of the sponge titanium with the sponge zirconium uniformly to form the first mixture, mix the second part of the sponge titanium with high-purity aluminum and N alloy packages uniformly to form the second mixture, mix the third part of the sponge titanium with a tin-titanium alloy uniformly to form the third mixture, then combine the remaining parts of the sponge titanium with the first mixture, the second mixture and the third mixture in a mixed material manner to obtain a pre-pressed material, and finally press the pre-pressed material into a consumable electrode block and place it in a drying box for drying;

[0136] Step 3, first assemble the consumable electrode block into an unwelded consumable electrode on the fastening material rack, then extrude all the consumable electrode blocks through the clamping devices at both ends of the material rack until the gap between the consumable electrode blocks is ≤2.5mm to ensure that the consumable electrode blocks are tightly assembled and reduce the middle weld of the consumable electrode; before welding, vacuumize to a vacuum degree below 1.5Pa, load a single consumable electrode into a plasma welding box and vacuumize, then fill argon into the plasma welding box; adjust the plasma welding gun to be located at an arc striking position, start welding along the transverse joint gap of the consumable electrode, and stop welding 40-60mm before the cross joint gap position to perform arc collection; then complete the welding of the "L-shaped" weld along the longitudinal direction and stop the arc, then move the plasma welding gun to the center of the transverse weld 40-60mm away from the longitudinal weld to perform transverse welding, thus completing the breakpoint welding of one cross joint gap; complete the welding of all cross joint gaps on one side of the single consumable electrode in the same way, cool for 1h, rotate the material rack, and complete the welding of all cross joint gaps on the other side; cool for 1.5h or more under the protection of argon in the plasma welding box and discharge to obtain the consumable electrode, the total cooling time is 2.5h or more, clean the spatters and weld beads on the consumable electrode in time after discharging from the welding box, then place the consumable electrode in a drying box for drying;

[0137] Step 4, weld the dried consumable electrode with the same grade auxiliary electrode in a vacuum consumable arc furnace to obtain a primary consumable electrode, remove the spatters and weld beads generated during welding, and perform first melting on the primary consumable electrode, then obtain a primary ingot after first in-furnace cooling; skin the two primary ingots and perform in-furnace welding in a vacuum furnace, then perform second melting, and obtain a secondary ingot after second in-furnace cooling; skin the secondary ingot, perform third melting, and obtain a finished ingot after third in-furnace cooling; the vacuum degree is ≤1Pa, the melting current is 15-25kA, the melting voltage is 30-45V, the leakage rate is ≤0.6Pa / min, and the discharge temperature of the ingot after the first in-furnace cooling, the second in-furnace cooling and the third in-furnace cooling is lower than 280℃;

[0138] Skin the finished ingot, perform flaw detection and saw cutting of the sprue, then sample the finished ingot for chemical composition detection, and the detection results are shown in Table 8;

[0139] Table 8: Chemical composition of the finished ingot (wt. %)

[0140]

[0141] Step 5: forging the finished ingot to obtain a rod blank, specifically:

[0142] Step 5.1: first, the finished ingot is scaled, then an oxidation-resistant coating is applied, and then it is placed in a heating furnace above the phase transition point at 150℃ for 5h, followed by 1 fire upsetting and drawing, with a total forging ratio of 4.5 per fire, and after forging, the hot material is returned to the furnace, placed in a heating furnace above the phase transition point at 80℃ for 3h, and then 1 fire upsetting and drawing is performed, with a total forging ratio of 3.5 per fire, and after forging, the material is air-cooled to obtain a first forged blank;

[0143] Step 5.2: the first forged blank is placed in a heating furnace below the phase transition point at 80℃ for 5h, and 1 fire upsetting and drawing is performed, with a total forging ratio controlled between 3 per fire, and after forging, the hot material is returned to the furnace, placed in a heating furnace above the phase transition point at 70-100℃ for 4h, and 7 fire upsetting and drawing is performed, with a total forging ratio of 2.0-3.5 per fire, and after forging, the material is air-cooled to obtain a second forged blank;

[0144] Step 5.3: the second forged blank is placed in a heating furnace below the phase transition point at 20-100℃ for 6-8h, and 4 fire final forging is performed, with a total forging ratio controlled at 1.3-1.5 per fire, and after forging, the material is air-cooled to obtain a rod blank.

[0145] Step 6: first, the rod blank is coated with an oxidation-resistant coating, and then heat treatment is performed at a heating rate of 4℃ / min, heating to 750℃ for 2h, and then slowly furnace cooling to obtain a finished rod G.

[0146] To further verify the effectiveness of the technical solutions provided by the present application, the following performance tests were conducted on the finished rod A1, finished rod A2, finished rod B, finished rod C, finished rod D, finished rod E, finished rod F, and finished rod G:

[0147] (1) performance tests for fracture toughness, impact energy, and 500℃ tensile strength were conducted;

[0148] (2) dynamic performance tests were conducted at room temperature, 10 3 s -1 level strain rate conditions;

[0149] (3) dynamic performance tests were conducted at 500℃, 10 3 s -1 level strain rate conditions;

[0150] The performance test results are shown in Table 9:

[0151] From the above, it can be seen that the present application can effectively control the interstitial elements in the titanium alloy to a very low level by the synergistic control of the preparation of alloy package, drying of raw materials, step-by-step mixing and pressing of consumable electrode block, welding process parameter control, melting process parameter control, and drying treatment. Further, the composition of the ingot obtained in the above examples and comparative examples is relatively uniform and the alloy element composition is accurately controlled, indicating that the alloy package measures can effectively solve the loss problem of the powder-shaped intermediate alloy. After increasing the fastening force in the welding process, the "L-type" welding method is used, and the welds are not cracked, so the measures taken to reduce the content of interstitial elements and the "L-type" welding method are feasible and meet the requirements.

[0152] From the analysis of Table 2, it can be seen that the content of interstitial elements O, C, and N in the finished ingot can be effectively reduced after peeling of the primary ingot and the secondary ingot.

[0153] Table 9 Performance comparison of examples 1-5 and comparative examples 1-2 of the present application

[0154]

[0155] From the analysis of Table 9, it can be seen that the alloy composition of the finished rod prepared in examples 1-5 is compared with the alloy composition of the finished rod in comparative examples 1 and 2 which is not within the scope of the alloy composition claimed in the present application: ① significantly improves the plasticity and toughness of the alloy under the premise of ensuring strength; ② under the condition of room temperature and 500℃, 10 3 s -1 grade strain rate, ensures a certain dynamic plastic strain and dynamic impact absorption energy while ensuring a certain dynamic plastic strain and dynamic impact absorption energy; it is indicated that within the composition range of the titanium alloy in the present application, the finished rod manufactured by the preparation method of the present application significantly improves the plasticity and toughness of the titanium alloy under the premise of ensuring a certain strength, and meets the application requirements of the new generation of missile warhead shells in high-speed penetration scenarios.

[0156] It should be noted that the antioxidant coating in the present application is an aluminum coating; the depth during peeling in the examples and comparative examples is 4-12mm, and the three times of melting represent the first melting, the second melting, and the third melting.

[0157] The above description is only a specific implementation of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application.

[0158] It should be understood that the application is not limited to what has been described hereinabove and that various modifications and changes can be made without departing from the scope of the application. The scope of the application is limited only by the claims that follow.

Claims

1. A method of producing a high ductility, low interstitial titanium alloy bar, the high ductility, low interstitial titanium alloy bar being produced from the following components in mass percent Composition: Al: 5.5~7.0%, Mo: 1.5~2.4%, V: 2.1~3.0%, Zr: 2.1~3.0%, Sn≤2%, Si≤0.02%, O≤0.075%, C≤0.01%, N<0.003%, H≤0.005%, the balance being Ti, the sum of the above components being 100% by mass, characterized in that it comprises the following steps: Step 1, first calculate and weigh the aluminum-molybdenum alloy powder, aluminum-vanadium alloy powder, titanium sponge, zirconium sponge, high-purity aluminum, tin-titanium alloy as raw materials, and mix the aluminum-molybdenum alloy powder and aluminum-vanadium alloy powder uniformly, then wrap them with aluminum foil into N alloy packages, and then dry the titanium sponge, zirconium sponge, high-purity aluminum, tin-titanium alloy and alloy packages; Step 2, first divide the titanium sponge into at least five parts, mix the first part of the titanium sponge with the zirconium sponge uniformly to form the first mixture, mix the second part of the titanium sponge with the high-purity aluminum and N alloy packages uniformly to form the second mixture, mix the third part of the titanium sponge with the tin-titanium alloy uniformly to form the third mixture, then combine the remaining parts of the titanium sponge with the first mixture, the second mixture and the third mixture in a mixed manner to obtain a pre-pressed material, and finally press the pre-pressed material into a consumable electrode block and dry it; Step 3, first assemble the dried consumable electrode block into an unwelded consumable electrode, control the gap between the consumable electrode blocks to ≤2.5mm, then weld to form a consumable electrode, and dry after surface pretreatment; Step 4, under vacuum conditions, weld the dried consumable electrode with the same grade auxiliary electrode to obtain a primary consumable electrode, and after surface pretreatment, carry out three times of melting to obtain a finished ingot; Step 5, first peel the finished ingot, coat an antioxidant layer, and then perform forging to obtain a rod blank; Step 6, first coat the rod blank with an antioxidant coating, and then perform heat treatment to obtain a high-plasticity and high-toughness low-gap titanium alloy rod.

2. The method of claim 1, wherein the high plasticity low interstitial titanium alloy bar is produced by the steps of: providing a titanium alloy ingot; hot working the titanium alloy ingot to produce a titanium alloy bar; and cold working the titanium alloy bar to produce a high plasticity low interstitial titanium alloy bar. In step 1, the titanium sponge has a purity of ≥99.65%, the high-purity aluminum has a purity of ≥99.9%, the zirconium sponge has a purity of ≥99.9%, and the aluminum-molybdenum alloy powder, aluminum-vanadium alloy powder and tin-titanium alloy all have a purity of ≥99.9%.

3. The method of claim 1, wherein the high plasticity low interstitial titanium alloy bar is produced by the steps of: providing a titanium alloy ingot; hot working the titanium alloy ingot to produce a titanium alloy bar; and cold working the titanium alloy bar to produce a high plasticity low interstitial titanium alloy bar. In step 3, first assemble the consumable electrode blocks on a fastening rack to form an unwelded consumable electrode, then extrude all the consumable electrode blocks through the clamping devices at both ends of the rack until the gap between the consumable electrode blocks is ≤2.5mm, then weld the consumable electrode by using the "L-type" welding method in the plasma welding box, clean the splashes and welds, and then dry them in a drying box; before assembling and welding the consumable electrode blocks, the flash of the consumable electrode blocks needs to be removed and the HTi particles need to be cleaned; the vacuum degree during welding is controlled to be below 1.5Pa, and the cooling time is ≥2.5h.

4. The method of claim 1, wherein the high plasticity low interstitial titanium alloy bar is produced by the steps of: providing a titanium alloy ingot; hot working the titanium alloy ingot to produce a titanium alloy bar; and cold working the titanium alloy bar to produce a high plasticity low interstitial titanium alloy bar. In step 4, the three times of melting are as follows: first time of melting is performed on the first consumable electrode, and the first ingot is obtained after first time of cooling; after the two first ingots are scaled, in-vacuum furnace welding is performed in a vacuum furnace, second time of melting is performed, and the second ingot is obtained after second time of cooling; after the second ingot is scaled, third time of melting is performed, and the finished product ingot is obtained after third time of cooling; during the melting process, the vacuum degree is required to be less than or equal to 1 Pa, the melting current is 10-30 kA, and the melting voltage is 20-45 V; the scaling depth of the first ingot and the second ingot is 4-12 mm.

5. The method for preparing high-ductility, low-gap titanium alloy rods according to claim 1, characterized in that, Step 5 specifically comprises: Step 5.1, first, the finished product ingot is scaled, then an oxidation-resistant coating is coated, then the finished product ingot is placed in a heating furnace above the phase transition point for 5-7 h at a temperature of 100-240 DEG C, and then 1-2 times of upsetting and drawing are performed, the total forging ratio of each time of upsetting and drawing is 2.0-4.5, the hot material is returned to the furnace after forging, the hot material is placed in a heating furnace above the phase transition point for 2-3 h at a temperature of 50-120 DEG C, and then 1-2 times of upsetting and drawing are performed, the total forging ratio of each time of upsetting and drawing is 2.0-4.5, and the second forging blank is obtained after air cooling; Step 5.2, the first forging blank is placed in a heating furnace below the phase transition point for 5-6 h at a temperature of 20-80 DEG C, 1-2 times of upsetting and drawing are performed, the total forging ratio of each time of upsetting and drawing is controlled to be between 1.3 and 3, the hot material is returned to the furnace after forging, the hot material is placed in a heating furnace above the phase transition point for 3-4 h at a temperature of 50-120 DEG C, 4-7 times of upsetting and drawing are performed, the total forging ratio of each time of upsetting and drawing is 2.0-4.5, and the second forging blank is obtained after air cooling; Step 5.3, the second forging blank is placed in a heating furnace below the phase transition point for 6-8 h at a temperature of 20-120 DEG C, 4-7 times of finished product forging are performed, the total forging ratio of each time of finished product forging is controlled to be between 1.1 and 1.5, and the bar blank is obtained after air cooling.

6. The method for preparing high-ductility, low-gap titanium alloy rods according to claim 1, characterized in that, In step 6, the parameters of the heat treatment are as follows: the temperature is 700-800 DEG C, and the holding time is 1-2 h.

7. The method for preparing high-ductility, low-gap titanium alloy rods according to claim 1, characterized in that, In steps 5 and 6, the oxidation-resistant coating is an aluminum coating.

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