Titanium alloy suitable for high temperature above 650 DEG C and preparation method thereof

Abstract

The invention relates to a titanium alloy suitable for a high temperature of more than 650 DEG C and a preparation method thereof, belongs to the technical field of titanium alloys, and solves the problems of poor structure uniformity and poor high-temperature durability of the existing titanium alloy at the high temperature of more than 650 DEG C. The alloy comprises the following components in percentage by weight: 5.5%-6.2% of Al, 3.5%-4.5% of Sn, 2.8%-4.5% of Zr, 0.25%-0.45% of Si, 0.20%-0.40% of Nb, 0.4%-0.8% of Ta, 1.0%-1.5% of W, 0.04%-0.06% of C, less than or equal to 0.05% of Fe, less than or equal to 0.10% of O and the balance of Ti and inevitable impurities. The mass ratio of Nb to Ta to W is 1: 2: 3.4-1: 2.2: 4, and the total content of Nb to Ta to W is 2-2.5%; the mass ratio of Zr to Si is greater than or equal to 10. The titanium alloy prepared through the method is good in structure uniformity and high-temperature durability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium alloy, and particularly relates to a titanium alloy suitable for high temperature above 650 DEG C and a preparation method thereof. BACKGROUND

[0002] Titanium alloy has been widely used in the fields of aviation and aerospace due to its low density, high specific strength, good corrosion resistance and high temperature performance. With the continuous development of aerospace technology, higher requirements are put forward for the high temperature performance of titanium alloy.

[0003] Titanium alloys with engineering strength above 600 DEG C are collectively referred to as high temperature resistant titanium alloys, which are mainly near-alpha type (IMI834, Ti-1100, Ti60, etc.) and emerging particle reinforced titanium matrix composites at present, and the target service temperature range is 600-750 DEG C, which is used for aero-engine compressor disc, casing and hypersonic hot end components. When the service temperature is higher than 600 DEG C, the high temperature tensile strength, creep strength and fatigue strength of these traditional high temperature titanium alloys will decrease significantly, which cannot meet the increasing demand for lightweight temperature-resistant materials in the fields of aviation and aerospace.

[0004] The existing titanium alloy material suitable for high temperature environment above 600 DEG C has the problems of strengthening and embrittlement coexisting in composition design, high Al and Si improving creep strength but inducing alpha2 and silicide brittle phase, high preparation cost, poor alloy uniformity, poor high temperature stress rupture performance, and the like. The high temperature resistant titanium alloy is in the bottleneck period of performance-process-cost triangle, and breakthrough is needed for the integrated design of composition-microstructure-surface, and the composition and preparation method of the high temperature resistant titanium alloy are continuously optimized. SUMMARY

[0005] In view of the above analysis, the present application aims to provide a titanium alloy suitable for high temperature above 650 DEG C and a preparation method thereof, at least to solve one of the following problems of the existing high temperature resistant titanium alloy: 1. the uniformity of the existing high temperature resistant titanium alloy with a service temperature above 650 DEG C is poor; 2. the high temperature stress rupture performance of the existing high temperature resistant titanium alloy with a service temperature above 650 DEG C is poor.

[0006] The purpose of the present application is mainly realized through the following technical solutions:

[0007] In one aspect, the present application provides a titanium alloy suitable for high temperature above 650 DEG C, the alloy composition is as follows in terms of percentage by weight: Al: 5.5%-6.2%, Sn: 3.5%-4.5%, Zr: 2.8%-4.5%, Si: 0.25%-0.45%, Nb: 0.20%-0.40%, Ta: 0.4%-0.8%, W: 1.0%-1.5%, C: 0.04-0.06%, Fe≤0.05%, O≤0.10%, the balance being Ti and inevitable impurities.

[0008] Wherein, the mass ratio of high-temperature alloy elements Nb:Ta:W is 1:2:3.4-1:2.2:4, and the total content is 2%-2.5%; the mass ratio of Zr:Si is≥10.

[0009] Further, the titanium alloy presents a bimodal microstructure composed of equiaxed alpha phase and lamellar alpha+beta bundles, the lamellar thickness is about 1-2 microns, the overall structure is uniform, and there is no obvious pore or crack, the volume fraction of equiaxed alpha phase is 35-50%, and the grain size is 15-20 microns.

[0010] In another aspect, the present application also provides a preparation method of a titanium alloy suitable for high temperature above 650 DEG C, for preparing the above-mentioned titanium alloy, comprising the following steps:

[0011] S1: a certain amount of pure metal and / or alloy is weighed according to the component ratio of the titanium alloy, the ingredients are mixed and pressed into an electrode, and the electrode is vacuum plasma welded into an electrode group;

[0012] S2: the titanium alloy ingot is prepared by three times of vacuum consumable arc melting, and the obtained ingot is treated in appearance or peeled after each time of vacuum consumable arc melting;

[0013] S3: the titanium alloy ingot finally obtained in step S2 is subjected to inspection and then is subjected to cogging forging to obtain a titanium alloy billet;

[0014] S4: the titanium alloy billet is subjected to hot straightening, solid solution aging heat treatment and surface treatment to obtain a titanium alloy rod product;

[0015] In step S1, the furnace chamber pressure is≤3.0 Pa before the vacuum plasma welding starts; during the welding process, argon needs to be filled in the furnace chamber to maintain the pressure in the furnace chamber at 10000-20000 Pa; the leakage rate is≤0.25 Pa / min; the welding current is 330-450 A, and the welding voltage is 40-58 V.

[0016] Further, step S2 comprises:

[0017] S21: one time of vacuum melting

[0018] The inner wall of the water-cooled copper crucible is cleaned before smelting, the welded electrode is assembled into the furnace, the vacuum degree of the furnace body before smelting is less than or equal to 0.542 Pa, and the leakage rate is less than or equal to 0.25 Pa / min; in the stable smelting stage, the smelting current is 7-13.5 kA, the voltage is 31.6-36 V, and the stirring current DC is 6-10 A, so as to obtain two-section primary ingots;

[0019] S22: primary ingot appearance treatment

[0020] S23: secondary vacuum smelting

[0021] The inner wall of the water-cooled copper crucible is cleaned before smelting, the welded electrode is assembled into the furnace, the two-section primary ingots are inverted and welded, the vacuum degree of the furnace body before smelting is less than or equal to 0.528 Pa, and the leakage rate is less than or equal to 0.25 Pa / min; in the stable smelting stage, the smelting current is 10-22 kA, the voltage is 31.8-37 V, and the stirring current AC30s is 7-14 A, so as to obtain one-section secondary ingots;

[0022] S24: secondary ingot appearance treatment

[0023] S25: tertiary vacuum smelting

[0024] The inner wall of the water-cooled copper crucible is cleaned before smelting, the welded electrode is assembled into the furnace, the vacuum degree of the furnace body before smelting is less than or equal to 0.50 Pa, and the leakage rate is less than or equal to 0.2 Pa / min; in the stable smelting stage, the smelting current is 15-24 kA, the voltage is 32-38 V, and the stirring current AC30s is 7.5-18.5 A, so as to obtain one-section tertiary ingots;

[0025] S26: skinning of the tertiary ingot.

[0026] Further, the step S3 comprises:

[0027] S31: alloy and interstitial gas element content detection is performed on the ingot obtained in the step S26, so as to ensure that the content of each element in the obtained ingot meets the design requirements, and the internal defects of the ingot and the location of the riser are detected by a non-destructive ultrasonic flaw detector;

[0028] S32: the α+β / β phase transition point of the ingot is tested, the empty furnace is heated to 820±10℃, the furnace is loaded and kept warm, the temperature is increased to 20-35℃ above the α+β / β phase transition point within a specified time, and the temperature is kept warm, and upsetting and piercing forging are performed;

[0029] S33: the ingot after the step S32 is processed, the empty furnace is heated to 820±10℃, the furnace is loaded and kept warm, the temperature is increased to 10-50℃ below the α+β / β phase transition point within a specified time, and the temperature is kept warm, and hydraulic forging is performed, so as to obtain an intermediate blank;

[0030] S34: the intermediate blank is subjected to hot working of a precision forging machine, the holding time is 20-50 DEG C below the alpha+beta / beta phase transition point temperature, the final forging temperature is controlled in the temperature range of the alpha+beta two-phase region, and the blank is air-cooled to room temperature after forging to obtain a titanium alloy bar blank.

[0031] Further, in step S32, the furnace loading holding time is 85-95 min, the specified time is 110-130 min, and the holding time at 20-35 DEG C above the alpha+beta / beta phase transition point temperature is 140-160 min.

[0032] The upsetting and drawing forging is 2-4 times, the deformation amount is 20-50% per time, the speed is kept uniform during the pressing process, the speed is 40-60 mm / s, and the pressing amount is controlled to be 80-100 mm each time.

[0033] Further, in step S33, the furnace loading holding time is 85-95 min, the specified time is 110-130 min, and the holding time at 10-60 DEG C above the alpha+beta / beta phase transition point temperature is 110-130 min.

[0034] The hydraulic forging is 4-5 times, the heating temperature is gradually reduced with the increase of the forging times, the maximum reduction per time is ≤100 DEG C, the nominal deformation amount per time is ≥40-45%, and the single anvil amount is ≥10%.

[0035] Further, in step S34, the holding time at 20-60 DEG C below the alpha+beta / beta phase transition point temperature is 90-100 min, and the deformation amount of the final forging is 10-30%.

[0036] Further, step S4 comprises:

[0037] S41: the titanium alloy bar blank is subjected to hot straightening, and the heating temperature is 800-900 DEG C;

[0038] S42: the titanium alloy bar blank subjected to the hot straightening treatment is subjected to solid solution and aging heat treatment, the blank is water-cooled after the solid solution treatment, and the blank is air-cooled after the aging treatment;

[0039] S43: the titanium alloy bar blank subjected to the solid solution and aging heat treatment is subjected to outer layer oxide removal by a lathe machine, and is subjected to mechanical polishing to obtain a titanium alloy bar product.

[0040] Further, in step S42, the solid solution temperature is 5-35 DEG C below the alpha+beta / beta phase transition point temperature, and the holding time is 2h-2.5h;

[0041] The aging temperature is 700±5 DEG C, and the holding time is 6-8h.

[0042] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0043] 1. The high-temperature titanium alloy of the present application does not contain the commonly used Mo element, effectively inhibits the brittle Ti2Mo phase generated by the reaction of beta-Ti and Mo element, significantly improves the room temperature toughness and high temperature microstructure stability of the alloy; at the same time, Al constructs the alpha phase skeleton to provide basic strength, Sn and Zr assist to strengthen the alpha phase hot strength, Nb / W and other elements control the balanced plasticity and high temperature strength of beta phase, Si and C slightly strengthen the hot strength, while limiting the brittleness, the alloy system designed in the present application optimizes multiple performances, and is suitable for extremely high temperature scenes. At the same time, the expensive Ta element is partially replaced by W element, so that the raw material cost is reduced by about 35%, and through the solid solution strengthening and dispersion distribution of the second phase particles of W, the high temperature stress rupture strength of the alloy in the range of 650-800℃ is improved by about 22%. By reasonably designing the proportion of alloy components, optimizing the proportioning of alloy elements, the comprehensive mechanical properties and use stability of the titanium alloy in high temperature environment above 650℃ are improved, which meets the demand of aerospace and other fields for light weight temperature resistant materials.

[0044] 2. The titanium alloy of the present application improves the use time of titanium alloy at high temperature by reasonably designing the proportion of alloy components, optimizing the proportioning of alloy elements and accurately controlling the preparation process parameters, and significantly enhances its high temperature resistance; the titanium alloy of the present application has a tensile strength of 600MPa or more at 650℃, a 0.2% specified plastic elongation strength of 550MPa or more at 650℃, an elongation after breaking of 42% or more at 650℃, a reduction of area of 83% or more at 650℃, a stress rupture time of 29h or more at 650℃ and 200MPa, which meets the increasing demand of aerospace and other fields for light weight temperature resistant materials.

[0045] In the present application, the above technical solutions can also be combined with each other to realize more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purpose and other advantages of the present application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0047] Figure 1 100x metallographic graph of the titanium alloy prepared for the present application embodiment 1;

[0048] Figure 2 50x metallographic graph of the titanium alloy prepared for the present application embodiment 1;

[0049] Figure 3A 20x metallograph of the titanium alloy prepared for Example 1 of the present application;

[0050] Figure 4 A stress-rupture time curve of the titanium alloy prepared for Example 1 of the present application. DETAILED DESCRIPTION

[0051] The preferred embodiments of the present application will be described in detail with reference to the drawings, in which:

[0052] The present application provides a titanium alloy suitable for high temperature above 650 DEG C, the alloy composition is as follows in percentage by weight: Al: 5.5%-6.2%, Sn: 3.5%-4.5%, Zr: 2.8%-4.5%, Si: 0.25%-0.45%, Nb: 0.20%-0.40%, Ta: 0.4%-0.8%, W: 1.0%-1.5%, C: 0.04-0.06%, Fe≤0.05%, O≤0.10%, the balance being Ti and inevitable impurities.

[0053] Wherein, the mass ratio of high-temperature alloy elements Nb:Ta:W is 1:2:3.4-1:2.2:4, and the total content is 2%-2.5%; the mass ratio of Zr:Si is≥10.

[0054] The reasons for limiting the alloy composition of the high-temperature-resistant titanium alloy and the preparation method thereof in the present application are described as follows, wherein only % is used to represent the mass percentage in the composition:

[0055] Al: alpha phase stabilizing element, which increases the beta transformation temperature, expands the alpha phase stability, and substitutes solid solution strengthening; it improves the room temperature and high temperature strength and thermal strength; the Al content in the present application is 5.5%-6.2%.

[0056] Sn: neutral element, which has little effect on the beta transformation temperature, weak room temperature strengthening effect, and can improve the thermal strength; the Sn content in the present application is 3.5%-4.5%.

[0057] Zr: neutral element, which has little effect on the beta transformation temperature, weak room temperature strengthening effect, and strong high temperature strengthening effect; the Zr content in the present application is 2.8%-4.5%.

[0058] Si: eutectoid beta stabilizing element, which reduces the beta transformation temperature, expands the beta phase region, and also causes eutectoid transformation, and can improve the thermal strength and heat resistance; the Si content in the present application is 0.25%-0.45%.

[0059] Nb: as a isomorphous β-stabilizing element, its regulation effect on β phase is that: the efficiency of reducing β transformation temperature is lower than Mo (about 12℃ per 1% Nb), but the solubility in β phase is high, which is mainly used to fine-tune the β phase stability to avoid the excessive stabilization of β phase caused by single Mo; since the solubility of Nb in α phase is extremely low (<0.5%), it mainly distributes in β phase, and the contribution to α phase strengthening is weak, which belongs to "β phase exclusive strengthening element"; in terms of plasticity and toughness optimization, the synergistic effect of Nb and Mo is obvious, which can reduce the hardness gradient of β phase, reduce the stress concentration of α / β interface, and improve the fatigue crack propagation resistance (ΔK); under the same β stabilization effect, replacing part of Mo with Nb can reduce the density of the alloy by about 0.1-0.2 g / cm 3 , which meets the weight reduction demand of aviation structural parts; in addition, a small amount of Nb can promote the continuity of Al2O3 in the surface oxide film and inhibit the porosity of the TiO2 layer, and when synergized with Si, it can reduce the oxidation weight gain rate of the alloy above 600℃ by 20%, thereby assisting in improving the oxidation resistance; if the content is too low, the improvement effect on β phase plasticity and oxidation resistance is not significant, and if the content is too high, Nb atoms have a high diffusion coefficient and are prone to segregation at high temperatures, and the production cost increases significantly (the price of Nb is about 3-5 times that of Ti); excessive Nb can reduce the β transformation temperature, delay the α phase precipitation kinetics, prolong the heat treatment cycle, and reduce the industrial production efficiency; the content of Nb in the present application is 0.2%-0.4%.

[0060] Ta: isomorphous β-stabilizing element, reduces β transformation temperature, and is infinitely soluble in β phase, expands β phase region, increases β phase stability, and a small amount of alloy addition improves oxidation resistance and corrosion resistance; the content of Ta in the present application is 0.4%-0.8%.

[0061] W: as an isomorphous β-stabilizing element, tungsten reduces β transformation temperature, is infinitely soluble in β phase, expands β phase region, and forms a β phase stabilization element system with molybdenum (Mo) and niobium (Nb); its atomic radius differs from that of titanium by about 15%, which can cause strong lattice distortion in β phase and form significant solid solution strengthening effect, thereby improving room temperature and high temperature strength; by inhibiting the grain growth of β phase at high temperature, the thermal strength and creep resistance of the alloy are effectively improved; through the dual mechanisms of solid solution strengthening and inhibition of β phase softening, tungsten significantly improves the stress rupture strength and creep resistance of the alloy in the range of 500-700℃; a small amount of tungsten can synergize with aluminum (Al) to form a dense WO3 and Al2O3 composite oxide film, thereby enhancing the surface oxidation resistance; the high density of tungsten makes its excessive addition sacrifice the lightweight advantage of the alloy, and its price is relatively high; tungsten is often used as an auxiliary strengthening element in combination with molybdenum and niobium to form a composite strengthening system, which ensures high temperature performance while avoiding the performance short board caused by excessive single element; in summary, the content of W in the present application is 1.0%-1.5%.

[0062] C: belongs to weak beta stable element, has little effect on beta transition temperature, but its main characteristic is easy to form TiC hard phase with titanium (low eutectoid reaction tendency, mainly exists in the form of dispersed precipitation); carbon can be dissolved in the interstitial space of alpha phase or beta phase lattice, hinders dislocation movement through short-range stress field, can improve the room temperature strength of the alloy, but will cause certain damage to plasticity; when the carbon content exceeds the solubility of titanium, nanoscale TiC particles will be precipitated, the matrix is strengthened through Orowan bypass mechanism, especially has a weak effect on high temperature strength, if the content of TiC exceeds 0.2%, it is easy to segregate at the grain boundary to form stress concentration source, resulting in deterioration of high temperature plasticity and fatigue performance; therefore, the carbon content needs to be strictly limited, and the C content in the application is 0.04-0.06%.

[0063] Fe is a harmful impurity element in high-temperature titanium alloy, and the Fe content in the application is controlled to be ≤0.05%.

[0064] O element exists in the form of interstitial atoms in titanium alloy, has a certain strengthening effect, but will deteriorate the plasticity, toughness and thermal stability of the alloy, and the O content in the application is ≤0.1%.

[0065] The mass ratio of high-temperature alloy elements Nb:Ta:W is 1:2.2:3.4-1:2:4, and the total content is 2%-2.5%: the three elements can form a single composite precipitated phase that is coherent with the matrix, inhibit the generation of brittle topological phase and continuous beta spot, ensure that the structure is mainly α phase with excellent high-temperature performance, thereby improving the uniformity of the alloy structure and significantly improving the anti-endurance performance above 600°C.

[0066] Zr:Si mass ratio ≥10: the strong affinity of Zr to Si can lock silicon atoms in intracrystalline nanoclusters, avoid the precipitation of grain boundary silicon-rich brittle phase, and further improve the high-temperature endurance plasticity of the alloy.

[0067] Preferably, the application provides a titanium alloy suitable for high temperature above 650°C, and the alloy composition is as follows in terms of weight percentage: Al: 5.8%-5.9%, Sn: 4.0%-4.1%, Zr: 3.8%-4.0%, Si: 0.35%-0.40%, Nb: 0.30%-0.35%, Ta: 0.6%-0.72%, W: 1.0%-1.2%, C: 0.052-0.055%, Fe: 0.021%-0.036%, O: 0.058%-0.084%, and the balance is Ti and unavoidable impurities.

[0068] Among them, the mass ratio of high-temperature alloy elements Nb:Ta:W is 1:2:3.4-1:2.2:4, and the total content is 2.1%-2.27%; the mass ratio of Zr:Si is ≥10.

[0069] The application also provides a preparation method of the titanium alloy suitable for high temperature above 650 DEG C, which is used for preparing the high-temperature-resistant titanium alloy and comprises the following steps.

[0070] S1: a certain amount of pure metal and / or alloy is weighed according to the component proportion of the titanium alloy, and is mixed and pressed into an electrode, and is vacuum plasma welded into an electrode group;

[0071] S2: the titanium alloy ingot is prepared through three times of vacuum arc remelting, and the appearance of the obtained ingot is treated or is scaled after each time of vacuum arc remelting;

[0072] S3: the titanium alloy ingot finally obtained in the step S2 is subjected to inspection and then is subjected to open-die forging to obtain a titanium alloy billet;

[0073] S4: the titanium alloy billet is subjected to hot straightening, solid solution aging heat treatment and surface treatment to obtain a titanium alloy rod product.

[0074] Specifically, in the step S1, the pure metal comprises 0-grade titanium sponge, zirconium sponge, carbon powder and pure aluminum; and the alloy comprises Sn-containing intermediate alloy, Si-containing intermediate alloy, Nb-containing intermediate alloy, Ta-containing intermediate alloy, W-containing intermediate alloy and Al-containing intermediate alloy.

[0075] Preferably, the Sn-containing intermediate alloy is Ti-80Sn, the Si-containing intermediate alloy is Al-70Si, the Nb-containing intermediate alloy is Ti-50Nb, the Ta-containing intermediate alloy is Al-70Ta, the W-containing intermediate alloy is Al-70W, and the Al-containing intermediate alloy is Al-70Si, Al-70Ta and Al-70W, and the rest is pure Al bean. The raw materials adopt 0-grade titanium sponge, alloy elements Sn, Si, Nb, Ta and W in the form of intermediate alloy, and Al is partially brought in by the above-mentioned Al-containing intermediate alloy, about 0.4-0.8%, and is partially added in the form of pure Al bean, about 5.0-5.4%, Zr and C are added in the form of zirconium sponge and carbon powder respectively, the intermediate alloy and the titanium sponge are mixed and pressed into an electrode after being weighed, and then the electrode is welded into an electrode group by using a vacuum plasma welding box. In the vacuum plasma welding box, the pressure in the furnace chamber is less than or equal to 3.0 Pa before the welding starts, the lower the pressure, the higher the vacuum degree, which can effectively reduce the interference of oxygen and other impurities on the welding process; during the welding process, argon needs to be filled in the furnace chamber to maintain the pressure in the furnace chamber at 10000-20000 Pa, which can ensure that the argon can fully protect the welding area, and at the same time, avoid the damage of the equipment or other problems caused by the too high pressure; the leakage rate is less than or equal to 0.25 Pa / min, which ensures the stability and reliability of the welding environment; the welding current is 330-450 A, and the welding voltage is 40-58 V.

[0076] It should be noted that in the present application, the high melting point metal elements (Nb, Ta, W) are added in the form of intermediate alloy, and part of the Al element is added in the form of Al-containing intermediate alloy and part is added in the form of pure Al bean. This is because the titanium alloy smelting temperature is 1600-1900℃, and the melting point of W (3422℃), Nb (2477℃) and Ta (3017℃) is much higher than that of titanium (1668℃). Direct addition of pure metal is easy to cause unmelted particles to remain (forming hard spots, segregation area, fatigue strength decrease by more than 30%) and smelting time to be prolonged (increasing titanium volatilization loss by 0.5-1% / 100℃ and equipment loss); intermediate alloy (such as Al-70Ta, Al-70W) uses eutectic effect to reduce melting point and can be completely dissolved at normal temperature; at the same time, it can inhibit volatilization loss; high melting point metals have high density, and direct addition is also easy to cause density difference and bottom segregation. By adding in the form of intermediate alloy, the components can be evenly distributed after mixing and electromagnetic stirring, and the composition can be accurately controlled. Part of the Al element is added in the form of Al-containing intermediate alloy and part is added in the form of pure Al bean, because the melting point of Al is 660℃, which can be rapidly dissolved in the titanium melt (<5min), and there is no need for intermediate alloy. The purity of pure aluminum bean is ≥99.5%, and the impurities are ≤0.3%, which avoids the gas impurities that may be introduced by Al-Ti intermediate alloy; pure aluminum bean can be accurately weighed, and Al surface oxidation forms an Al2O3 film with a volatilization rate of <1% / furnace, which can further reduce volatilization when added later; in addition, the addition of pure Al bean can reduce the viscosity and promote the discharge of gas. The price of pure Al bean is lower than that of Al-Ti intermediate alloy, which can reduce the cost of each ton of alloy by 300-500 thousand yuan, and the intermediate alloy preparation step is saved, and the production cycle is shortened by 2-3 hours / furnace. In summary, the addition of high melting point metals in the form of intermediate alloy can solve the problems of dissolution, volatilization and segregation, and the addition of Al in the form of pure Al bean can ensure the uniformity of titanium alloy composition and the stability of performance by virtue of low melting point, accurate control and low cost advantages, which meets the needs of industrial production.

[0077] Specifically, step S2 comprises:

[0078] S21: primary vacuum smelting

[0079] The inner wall of the water-cooled copper crucible is cleaned before smelting, and the welded electrode is assembled into the furnace. The vacuum degree of the furnace body before smelting is ≤0.542Pa, and the leakage rate is ≤0.25Pa / min; in the stable smelting stage, the smelting current is 7-13.5kA, the voltage is 31.6-36V, and the stirring current DC is 6-10A, to obtain two sections of primary ingots.

[0080] S22: appearance treatment of primary ingot

[0081] The ingot crown of the two sections of primary ingots obtained in step S21 is turned by a lathe to make the surface flat, and the surface foreign matter of the two sections of primary ingots is treated by an ingot cleaning machine and dried.

[0082] S23: secondary vacuum melting

[0083] The inner wall of the water-cooled copper crucible is cleaned before melting, the welded electrode is assembled into the furnace, the two sections of primary cast ingot are inverted and welded, the vacuum degree of the furnace body before melting is ≤0.528 Pa, and the leakage rate is ≤0.25 Pa / min; in the stable melting stage, the melting current is 10-22 kA, the voltage is 31.8-37 V, the stirring current AC30s is 7-14 A, and one section of secondary cast ingot is obtained.

[0084] S24: appearance treatment of the secondary cast ingot

[0085] The ingot crown of the one section of secondary cast ingot obtained in step S23 is turned by a lathe to make the surface flat, and the surface foreign matter of the one section of secondary cast ingot is treated by an ingot cleaning machine and dried.

[0086] S25: tertiary vacuum melting

[0087] The inner wall of the water-cooled copper crucible is cleaned before melting, the welded electrode is assembled into the furnace, the vacuum degree of the furnace body before melting is ≤0.50 Pa, and the leakage rate is ≤0.2 Pa / min; in the stable melting stage, the melting current is 15-24 kA, the voltage is 32-38 V, the stirring current AC30s is 7.5-18.5 A, and one section of tertiary cast ingot is obtained.

[0088] S26: skinning of the tertiary cast ingot

[0089] The skin of the one section of tertiary cast ingot obtained in step S25 is skinned by a lathe to ensure that the surface of the cast ingot is free of large-area pores and defects.

[0090] Specifically, step S3 includes the following steps:

[0091] S31: alloy and interstitial gas element content detection is performed on the cast ingot obtained in step S26 to ensure that the content of each element in the obtained cast ingot meets the design requirements; the internal defects of the cast ingot are detected and the riser position is determined by a non-destructive ultrasonic flaw detector;

[0092] S32: the α+β / β phase transition point of the cast ingot is tested, the empty furnace is heated to 820±10℃, the furnace is loaded and kept, heated to 20-35℃ above the α+β / β phase transition point temperature within a specified time, and upset forging is performed;

[0093] Specifically, the ingot is heated to 820±10℃, and then heated to 20-35℃ above the α+β / β phase transition point temperature (for example, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃ above the α+β / β phase transition point temperature) within 110-130 minutes, and then held for 140-160 minutes, and then upset forging is performed for 2-4 times, so that the deformation amount of each time is 20-50% (for example, 25%, 30%, 35%, 40%, 45% of each time), the speed is kept uniform during the pressing process, and the speed is 40-60mm / s (for example, 42mm / s, 44mm / s, 45mm / s, 46mm / s, 48mm / s, 50mm / s, 52mm / s, 54mm / s, 55mm / s, 56mm / s, 58mm / s), and the pressing amount of each time is controlled to be 80-100mm (for example, 82mm, 84mm, 85mm, 86mm, 88mm, 90mm, 92mm, 94mm, 95mm, 96mm, 98mm), so that the original cast structure of the ingot is fully broken, and uniform β grains are obtained.

[0094] S33: The ingot treated in step S32 is heated to 820±10℃, and then heated to 10-50℃ below the α+β / β phase transition point temperature within a specified time, and then held, and then hydraulic forging is performed to obtain an intermediate blank.

[0095] Specifically, the ingot treated in step S32 is heated to 820±10℃, and then heated to 10-50℃ below the α+β / β phase transition point temperature within 110-130 minutes (for example, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃ below the α+β / β phase transition point temperature), and then held for 110-130 minutes, and then hydraulic forging is performed for 4-5 times, and the heating temperature is gradually reduced with the increase of the forging times, and the maximum reduction of each time is ≤100℃ (for example, 90℃, 85℃, 80℃, 75℃, 70℃, 65℃, 60℃, 55℃, 50℃), and the nominal deformation amount of each time is ≥40-45% (for example, 41%, 41.5%, 42%, 42.5%, 43%, 43.5%, 44%, 44.5%), and the single anvil amount is ≥10% (for example, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%), and then an intermediate blank is obtained.

[0096] It should be noted that in step S33, two upsetting and two drawing are performed for each forging, and the round material is first upset (length is shortened by half), then drawn to an eight-sided material, and finally rolled into a round shape; this forging method ensures that the core is fully deformed, the head and tail of the bar blank are uniformly deformed, and a uniform cross-section is obtained.

[0097] S34: The intermediate blank is subjected to hot working of a finish forging machine, at 20-50℃ below the α+β / β phase transition point temperature, and the final forging temperature is controlled within the α+β two-phase temperature range, and after forging, air cooling to room temperature to obtain a titanium alloy bar blank.

[0098] Specifically, the intermediate blank is subjected to hot working of a finish forging machine, at 20-50℃ below the α+β / β phase transition point temperature (exemplarily, 25℃, 30℃, 35℃, 40℃, 45℃ below the α+β / β phase transition point temperature), the holding time is 90-100min, the deformation amount is 60-70% (exemplarily, the deformation amount is 62%, 64%, 65%, 66%, 68%), and the final forging temperature is controlled within the α+β two-phase temperature range to ensure that the material has sufficient plasticity to withstand deformation and good mechanical properties after cooling; at the same time, the deformation amount of the blank is controlled within 10-30% (exemplarily, the deformation amount is 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%) within the temperature range, and after forging, air cooling to room temperature to obtain a titanium alloy bar blank.

[0099] Specifically, step S4 includes:

[0100] S41: The titanium alloy bar blank is subjected to hot straightening, and the heating temperature is 800-900℃ (exemplarily, 820℃, 840℃, 850℃, 860℃, 880℃);

[0101] S42: The titanium alloy bar blank after hot straightening is subjected to solid solution and aging heat treatment, the solid solution temperature is 5-35℃ below the α+β / β phase transition point temperature (6℃, 8℃, 10℃, 12℃, 14℃, 15℃, 16℃, 18℃, 20℃, 22℃, 24℃, 25℃, 26℃, 28℃, 30℃ below the α+β / β phase transition point temperature), and the holding time is 2h-2.5h, and after discharging, water cooling, the aging temperature is 700±5℃, the holding time is 6-8h, and air cooling;

[0102] S43: The titanium alloy bar blank after solid solution and aging heat treatment is removed by lathe machine, and mechanically polished to obtain a titanium alloy bar product.

[0103] The high-temperature titanium alloy of the present application does not contain Mo element, effectively inhibits the brittle Ti2Mo phase generated by the reaction of beta-Ti and Mo element, and significantly improves the room temperature toughness and high temperature microstructure stability of the alloy; at the same time, Al constructs the alpha phase skeleton to provide basic strength, Sn and Zr assist to strengthen the alpha phase hot strength, Nb / W and other elements control the balance plasticity and high temperature strength of beta phase, Si and C slightly strengthen the hot strength, and limit the brittleness at the same time, the alloy system designed in the present application optimizes multiple performances comprehensively, and is suitable for extremely high temperature scenes. At the same time, the expensive Ta element is partially replaced by W element, so that the raw material cost is reduced, and the high temperature enduring strength of the alloy in the range of 650-800℃ is improved through the solid solution strengthening of W and the second phase particles dispersedly distributed.

[0104] The high-temperature titanium alloy prepared in the present application presents a dual-state microstructure composed of equiaxed alpha phase (volume fraction about 35-50%, grain size 15-20μm) and lamellar alpha+beta bundles, the lamellar thickness is about 1-2μm, the overall microstructure is uniform, and there is no obvious pore or crack.

[0105] The present application improves the use time of titanium alloy at high temperature and significantly enhances its high temperature resistance by reasonably designing the alloy component ratio, optimizing the proportioning of alloy elements and accurately controlling the preparation process parameters; the titanium alloy prepared by the method of the present application has a room temperature tensile strength ≥1000MPa (for example, 1082-1123MPa), a 650℃ tensile strength ≥600MPa (for example, 607-615MPa); a room temperature 0.2% specified plastic elongation strength ≥1000Mpa (for example, 1010-1062MPa), a 650℃ 0.2% specified plastic elongation strength ≥550Mpa (for example, 572-586MPa); a room temperature elongation after fracture ≥11% (for example, 11.5-15.5%), a 650℃ elongation after fracture ≥42% (for example, 42.5-48.5%); a room temperature reduction of area ≥20% (for example, 23-26%), a 650℃ reduction of area ≥83% (for example, 83-89%); a 650℃ and 240MPa, the endurance time ≥29h (for example, 29.06-31.66h).

[0106] Example 1

[0107] The present embodiment provides a titanium alloy suitable for high temperature above 650℃, the alloy components are as follows in terms of weight percentage: Al: 5.8%, Sn: 4.0%, Zr: 4.0%, Si: 0.40%, Nb: 0.3%, Ta: 0.6%, W: 1.2%, C: 0.052%, Fe: 0.021%, O: 0.058%, the balance is Ti and unavoidable impurities;

[0108] The mass ratio of Nb:Ta:W is 1:2:4, the total content is 2.1%, and the mass ratio of Zr:Si is 10.

[0109] The preparation method comprises:

[0110] S1: a certain amount of pure metal and / or alloy is weighed according to the component proportion of the titanium alloy, the ingredients are mixed and pressed into electrodes, and the electrodes are vacuum plasma welded into an electrode group;

[0111] The raw materials adopt sponge titanium of 0 level and particle size of 3-12.7 mm, alloying elements Sn, Si, Nb, Ta and W are added in the form of intermediate alloy, part of Al is brought in by the intermediate alloy, and the insufficient part is added in the form of pure Al beans, Zr and C are added in the form of sponge zirconium and carbon powder respectively, and the intermediate alloy and the sponge titanium are mixed after being weighed, and then pressed into electrodes by a press;

[0112] The intermediate alloy containing Sn is Ti-80Sn, the intermediate alloy containing Si is Al-70Si, the intermediate alloy containing Nb is Ti-50Nb, the intermediate alloy containing Ta is Al-70Ta, the alloy containing W is Al-70W, and the intermediate alloy containing Al is the above-mentioned intermediate alloy containing Al, and the insufficient part adopts pure Al beans (about 0.6% of Al is brought in by the above-mentioned intermediate alloy containing Al, and about 5.2% is added in the form of pure Al beans).

[0113] The electrodes are welded into an electrode group by using a vacuum plasma welding box, wherein, in the vacuum plasma welding box, the pressure in the furnace chamber is ≤3.0 Pa before welding starts; during the welding process, argon needs to be filled in the furnace chamber to maintain the pressure in the furnace chamber at 10000-20000 Pa; the leakage rate is ≤0.25 Pa / min; the welding current is 330-450 A, and the welding voltage is 40-58 V.

[0114] S2: titanium alloy ingots are prepared by three times of vacuum consumable arc melting, and the obtained ingots are treated in appearance or peeled after each time of vacuum consumable arc melting;

[0115] S21: one-time vacuum melting

[0116] The inner wall of the water-cooled copper crucible is cleaned before melting, the welded electrode group is assembled into the furnace, the vacuum degree of the furnace body before melting is ≤0.542 Pa, and the leakage rate is ≤0.25 Pa / min; the melting current is 7-13.5 kA, the voltage is 31.6-36 V, and the stirring current DC is 6-10 A in the stable melting stage, and two sections of one-time ingots are obtained, with a diameter of 200-250 mm and a length of 800-1000 mm.

[0117] S22: appearance treatment of one-time ingot

[0118] The ingot crown of the two sections of one-time ingots obtained in step S21 is turned by a lathe to make the surface flat, the surface foreign matter of the two sections of one-time ingots is treated by using an ingot cleaning machine, and the two sections of one-time ingots are dried.

[0119] S23: two-time vacuum melting

[0120] The inner wall of the water-cooled copper crucible is cleaned before smelting, the welded electrode is assembled into the furnace, the two sections of primary cast ingot are welded in an inverted manner, the vacuum degree of the furnace body before smelting is less than or equal to 0.5 Pa, and the leakage rate is less than or equal to 0.25 Pa / min; in the stable smelting stage, the smelting current is 10-22 kA, the voltage is 31.8-37 V, the stirring current AC30s is 5-14 A, and a section of secondary cast ingot is obtained, with a diameter of 300-320 mm and a length of 1,000-1,200 mm.

[0121] S24: Appearance treatment of the secondary cast ingot

[0122] The ingot crown of the section of secondary cast ingot obtained in step S23 is turned by a lathe to make the surface flat, the surface foreign matter of the section of secondary cast ingot is treated by an ingot cleaning machine, and the section of secondary cast ingot is dried.

[0123] S25: Third vacuum smelting

[0124] The inner wall of the water-cooled copper crucible is cleaned before smelting, the welded electrode is assembled into the furnace, the vacuum degree of the furnace body before smelting is less than or equal to 0.60 Pa, and the leakage rate is less than or equal to 0.2 Pa / min; in the stable smelting stage, the smelting current is 15-24 kA, the voltage is 32-38 V, the stirring current AC30s is 7.5-18.5 A, and a section of third cast ingot is obtained, with a diameter of 300-320 mm and a length of 1,000-1,200 mm.

[0125] S26: Skinning of the third cast ingot

[0126] The skin of the section of third cast ingot obtained in step S25 is turned by a lathe to ensure that the surface of the cast ingot is free of large-area pores and defects.

[0127] S3: The titanium alloy cast ingot finally obtained in step S2 is subjected to inspection and then is subjected to breakdown forging to obtain a titanium alloy billet;

[0128] S31: The content of alloying elements and interstitial gas elements in the cast ingot obtained in step S26 is detected, and test samples are taken by turning at positions about 250 mm away from the head and tail of the cast ingot, respectively, to ensure that the content of each element in the obtained cast ingot meets the design requirements; the internal defects of the cast ingot are detected by a non-destructive ultrasonic flaw detector, and the position of the riser is determined;

[0129] S32: The α+β / β phase transition point of the cast ingot is 1,010 ℃, the empty furnace is heated to 830 ℃, the furnace is loaded and kept for 90 min, and the temperature is raised to 20 ℃ above the α+β / β phase transition point within 125 min (i.e., the heating temperature is 1,030 ℃), and the temperature is kept for 150 min; three times of upsetting and drawing forging are performed, the deformation amount of the first time is 25%, the deformation amount of the second time is 35%, and the deformation amount of the third time is 45%; the speed is kept uniform during the pressing process, the speed is 45 mm / s, the pressing amount of each time is controlled to be 80-100 mm, and the size of the obtained billet is 1,000-1,200 mm in length and 300-320 mm in diameter.

[0130] S33: The ingot after step S32 is heated to 820°C, loaded into the furnace and kept for 85 min, heated to 40°C below the α+β / β phase transition point temperature within 125 min (i.e. the heating temperature is 970°C), kept for 125 min, forged 4 times by a hydraulic machine, and the heating temperature is gradually reduced with the increase of the forging times, and the reduction of each time is 100°C, 80°C and 60°C respectively, and the nominal deformation amount of each time is 40%, and the single-time entering anvil amount is 12%;

[0131] Each time of forging is two upsetting and two drawing, and the round bar is first upset (the length is shortened by half), then drawn to an eight-square bar, and finally rolled into a round bar, which ensures that the core is fully deformed, the head and tail of the bar are uniformly deformed, and a middle billet is obtained, and the size of the middle billet is

[0132] S34: The middle billet is hot worked by a precision forging machine, heated to 40°C below the α+β / β phase transition point temperature (i.e. the heating temperature is 970°C), kept for 95 min, and the nominal deformation amount is 65%, and the final forging temperature is 850°C, which is controlled in the temperature range of the α+β two-phase region; in the temperature range, the deformation amount of the billet is 30%, and the billet is air-cooled to room temperature after forging, to obtain a titanium alloy bar blank.

[0133] S4: After the titanium alloy bar blank is subjected to hot straightening, solid solution aging heat treatment and surface treatment, a titanium alloy bar product is obtained.

[0134] S41: The titanium alloy bar blank is subjected to hot straightening, and the heating temperature is 860°C.

[0135] S42: The titanium alloy bar blank after hot straightening is subjected to solid solution aging heat treatment, the solid solution temperature is 10°C below the α+β / β phase transition point temperature (i.e. the solid solution temperature is 1000°C), and the holding time is 2 h, and the billet is water-cooled after being discharged from the furnace, and the aging temperature is 705°C, and the holding time is 6 h, and the billet is air-cooled.

[0136] S43: The titanium alloy bar blank after solid solution aging heat treatment is subjected to outer layer oxide removal by lathe machine, and mechanical polishing, to obtain a titanium alloy bar product.

[0137] The high-temperature titanium alloy prepared in the embodiment presents a dual-state microstructure, which is composed of equiaxed α phase (volume fraction is about 42.5%, grain size is 15-20 μm) and lamellar α+β bundles, and the lamellar thickness is about 1-2 μm, and the overall structure is uniform without obvious pores or cracks.

[0138] Example 2

[0139] The embodiment provides a titanium alloy suitable for high temperature above 650 DEG C, alloy components are as follows in percentage by weight: Al: 5.9%, Sn: 4.1%, Zr: 3.8%, Si: 0.35%, Nb: 0.35%, Ta: 0.72%, W: 1.30%, C: 0.055%, Fe: 0.023%, O: 0.063%; the balance is Ti and inevitable impurities.

[0140] The mass ratio between Nb, Ta and W is 1:2.05:3.42, and the total content is 2.27%; the mass ratio between Zr and Si is 10.85.

[0141] The preparation method and process parameters are the same as those in Embodiment 1.

[0142] The high-temperature titanium alloy prepared in the embodiment presents a dual-state microstructure, which is composed of equiaxed alpha phase (volume fraction is about 37.33%, grain size is 10-20 mu m) and lamellar alpha+beta bundles, the lamellar thickness is about 1-2 mu m, and the overall structure is uniform without obvious pores or cracks.

[0143] Embodiment 3

[0144] The embodiment provides a titanium alloy suitable for high temperature above 650 DEG C, alloy components are as follows in percentage by weight: Al: 5.8%, Sn: 4.0%, Zr: 4.0%, Si: 0.4%, Nb: 0.3%, Ta: 0.6%, W: 1.20%, C: 0.052%, Fe: 0.036%, O: 0.084%; the balance is Ti and inevitable impurities.

[0145] The mass ratio between Nb, Ta and W is 1:2.:4, and the total content is 2.10%; the mass ratio between Zr and Si is 10.

[0146] The preparation method is similar to that in Embodiment 1, except that in step S42, the titanium alloy bar after the hot straightening treatment is subjected to solid solution and aging heat treatment, the solid solution temperature is 5 DEG C below the alpha+beta / beta phase transition point temperature (namely, the solid solution temperature is 1005 DEG C), the heat preservation time is 2h, the titanium alloy bar is water-cooled after being discharged, the aging temperature is 700 DEG C, the heat preservation time is 8h, and the titanium alloy bar is air-cooled.

[0147] The high-temperature titanium alloy prepared in the embodiment presents a dual-state microstructure, which is composed of equiaxed alpha phase (volume fraction is about 37.33%, grain size is 10-20 mu m) and lamellar alpha+beta bundles, the lamellar thickness is about 1-2 mu m, and the overall structure is uniform without obvious pores or cracks.

[0148] Comparative Example 1

[0149] The comparative example provides a titanium alloy suitable for high temperature above 650℃, the alloy components are as follows in percentage by weight: Al: 5.8%, Sn: 4.0%, Zr: 4.0%, Si: 0.40%, Nb: 0.7%, Ta: 0.75%, W: 0.7%, C: 0.05%, Fe: 0.032%, O: 0.091%, the balance is Ti and inevitable impurities.

[0150] The mass ratio of Nb:Ta:W is 1:1.07:1, and the total content is 2.15%, and the mass ratio of Zr:Si is 10.

[0151] The preparation method and process parameters are the same as those in Example 1.

[0152] The high-temperature titanium alloy prepared in the comparative example presents a bimodal microstructure composed of equiaxed α phase (volume fraction about 31.15%, grain size 10-20 μm) and lamellar α+β clusters, the lamellar thickness is about 1-2 μm, the overall structure is uniform, and there is no obvious pore or crack.

[0153] Comparative Example 2

[0154] The comparative example provides a titanium alloy suitable for high temperature above 650℃, the alloy components are the same as those in Example 1. The preparation method is similar to that in Example 1, except that in step S42, the titanium alloy bar after hot straightening treatment is subjected to solid solution and aging heat treatment, the solid solution temperature is 50℃ below the α+β / β phase transition point temperature (i.e. the solid solution temperature is 960℃), the holding time is 2h, the titanium alloy bar is water-cooled after being taken out of the furnace, and the aging temperature is 700℃, the holding time is 8h, and the titanium alloy bar is air-cooled.

[0155] The alloy components of the titanium alloy in the examples and comparative examples are shown in Table 1, and the mechanical properties of the titanium alloy in the examples and comparative examples are shown in Table 2.

[0156] The high-temperature titanium alloy prepared in the comparative example presents a bimodal microstructure composed of equiaxed α phase (volume fraction about 31.15%, grain size 10-20 μm) and lamellar α+β clusters, the lamellar thickness is about 1-2 μm, the overall structure is uniform, and there is no obvious pore or crack.

[0157] Table 1 Alloy components of titanium alloy in examples and comparative examples (wt.%)

[0158] Element Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Al 5.8 5.9 5.8 5.8 5.8 Sn 4.0 4.1 4.0 4.0 4.0 Zr 4.0 3.8 4.0 4.0 4.0 Si 0.40 0.35 0.40 0.4 0.40 Nb 0.30 0.35 0.30 0.7 0.30 Ta 0.60 0.72 0.60 0.75 0.60 W 1.2 1.2 1.2 0.7 1.2 C 0.052 0.055 0.052 0.05 0.052 Fe 0.021 0.023 0.036 0.032 0.021 O 0.058 0.063 0.084 0.091 0.058 Nb + Ta + W % 2.10 2.27 2.10 2.15 2.10 Nb % : Ta % : W % 1:2:4 1:2.05:3.42 1:2:4 1:1.07:1 1:2:4 Zr % : Si % : 10 10.85 10 10 10

[0159] Table 2 Properties of titanium alloy in examples and comparative examples

[0160]

[0161] In the alloy component of the comparative example 1, the content of the elements Nb and W, and the ratio of Nb, Ta and W do not meet the requirements of the present application. The alloy component of the comparative example 2 is the same as that of the example 1, but some process parameters in the preparation process do not meet the requirements of the present application. As shown in Table 2, the titanium alloy prepared by the comparative example 1 and the comparative example 2 has a lower endurance time than the example at 650℃ and 200MPa. The comprehensive mechanical properties and high-temperature endurance properties of the example are higher than those of the comparative examples.

[0162] The above description is merely preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.​

Claims

1. A titanium alloy suitable for use at high temperatures above 650°C, characterized in that, The alloy components are as follows in percentage by weight: Al: 5.5%-6.2%, Sn: 3.5%-4.5%, Zr: 2.8%-4.5%, Si: 0.25%-0.45%, Nb: 0.20%-0.40%, Ta: 0.4%-0.8%, W: 1.0%-1.5%, C: 0.04-0.06%, Fe≤0.05%, O≤0.10%, and the balance of Ti and inevitable impurities; Wherein, the mass ratio of high-temperature alloy elements Nb:Ta:W is 1:2:3.4-1:2.2:4, and the total content is 2%-2.5%; the mass ratio of Zr:Si is ≥10.

2. The titanium alloy of claim 1, wherein The titanium alloy presents a bimodal microstructure composed of equiaxed α phase and lamellar α+β bundles, the lamellar thickness is about 1-2 μm, the overall structure is uniform, and there is no obvious pore or crack, the volume fraction of equiaxed α phase is 35-50%, and the grain size is 15-20 μm.

3. A method for the production of a titanium alloy suitable for high temperatures above 650 °C, for the production of a titanium alloy according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: S1: a certain amount of pure metal and / or alloy is weighed according to the component proportion of the titanium alloy, and is mixed and pressed into an electrode, and the electrode is vacuum plasma welded into an electrode group; S2: the titanium alloy ingot is prepared by three times of vacuum consumable arc melting, and the obtained ingot is subjected to appearance treatment or skinning after each time of vacuum consumable arc melting; S3: the titanium alloy ingot finally obtained in step S2 is subjected to inspection and then is subjected to cogging forging to obtain a titanium alloy billet; S4: the titanium alloy billet is subjected to hot straightening, solid solution aging heat treatment and surface treatment to obtain a titanium alloy rod product; In step S1, the pressure in the furnace chamber before the vacuum plasma welding starts is ≤3.0 Pa; during the welding process, argon needs to be filled into the furnace chamber to maintain the pressure in the furnace chamber at 10000-20000 Pa; the leakage rate is ≤0.25 Pa / min; the welding current is 330-450 A, and the welding voltage is 40-58 V.

4. The production method according to claim 3, characterized by, Step S2 comprises: S21: first vacuum melting The inner wall of the water-cooled copper crucible is cleaned before melting, the welded electrode group is assembled into the furnace, the vacuum degree of the furnace body before melting is ≤0.542 Pa, and the leakage rate is ≤0.25 Pa / min; in the stable melting stage, the melting current is 7-13.5 kA, the voltage is 31.6-36 V, and the stirring current DC is 6-10 A, to obtain two sections of first ingots; S22: appearance treatment of the first ingot S23: second vacuum melting The inner wall of the water-cooled copper crucible is cleaned before melting, the welded electrode group is assembled into the furnace, and the two sections of first ingots are inverted and welded, the vacuum degree of the furnace body before melting is ≤0.528 Pa, and the leakage rate is ≤0.25 Pa / min; in the stable melting stage, the melting current is 10-22 kA, the voltage is 31.8-37 V, and the stirring current AC30s is 7-14 A, to obtain one section of second ingot; S24: appearance treatment of the second ingot S25: third vacuum melting The inner wall of the water-cooled copper crucible is cleaned before melting, the welded electrode group is assembled into the furnace, the vacuum degree of the furnace body before melting is ≤0.50 Pa, and the leakage rate is ≤0.2 Pa / min; in the stable melting stage, the melting current is 15-24 kA, the voltage is 32-38 V, and the stirring current AC30s is 7.5-18.5 A, to obtain one section of third ingot; S26: Three times ingot skinning.

5. The preparation method according to claim 4, characterized in that, Step S3 comprises: S31: The ingot obtained in step S26 is subjected to alloy and interstitial gas element content detection to ensure that the content of each element in the obtained ingot meets the design requirements, and the internal defects of the ingot and the location of the riser are detected by a non-destructive ultrasonic flaw detector; S32: The ingot is tested for α+β / β phase transition point, the furnace is heated to 820±10℃, the furnace is charged and kept warm, and the temperature is raised to 20-35℃ above the α+β / β phase transition point within a specified time, kept warm, upset forging is performed; S33: The ingot after step S32 is heated to 820±10℃ in an empty furnace, the furnace is charged and kept warm, the temperature is raised to 10-50℃ below the α+β / β phase transition point within a specified time, kept warm, and hydraulic forging is performed to obtain an intermediate blank; S34: The intermediate blank is subjected to hot working of a precision forging machine, kept warm at 20-50℃ below the α+β / β phase transition point, and the final forging temperature should be controlled within the temperature range of the α+β two-phase region, and air cooling is performed after forging to room temperature to obtain a titanium alloy bar blank.

6. The production method according to claim 5, wherein In step S32, the furnace keeping warm time is 85-95 min, the specified time is 110-130 min, and the keeping warm time at 20-35℃ above the α+β / β phase transition point is 140-160 min; The upset forging is 2-4 heats, and the deformation amount of each heat is 20-50%, the speed is kept uniform during the pressing process, the speed is 40-60 mm / s, and the pressing amount of each time is controlled to be 80-100 mm.

7. The preparation method according to claim 5, characterized in that, In step S33, the furnace keeping warm time is 85-95 min, the specified time is 110-130 min, and the keeping warm time at 10-60℃ above the α+β / β phase transition point is 110-130 min; The hydraulic forging is 4-5 times, the heating temperature gradually decreases with the increase of the forging times, the maximum decrease of each time is ≤100℃, the nominal deformation amount of each heat is ≥40-45%, and the single anvil amount is ≥10%.

8. The preparation method according to claim 5, characterized in that, In step S34, the keeping warm time at 20-60℃ below the α+β / β phase transition point is 90-100 min, and the deformation amount of the final forging is 10-30%.

9. The preparation method according to claim 5, characterized in that, Step S4 comprises: S41: The titanium alloy bar blank is subjected to hot straightening, and the heating temperature is 800-900℃; S42: The titanium alloy bar blank after hot straightening is subjected to solid solution and aging heat treatment, water cooling after solid solution treatment, and air cooling after aging treatment; S43: The titanium alloy bar blank after solid solution and aging heat treatment is removed from the outer layer of the oxide skin by lathe machine, and is mechanically polished to obtain a titanium alloy bar product.

10. The method of claim 9, wherein, In step S42, the solid solution temperature is 5-35℃ below the α+β / β phase transition point, and the keeping warm time is 2h-2.5h; The aging temperature is 700±5℃, and the keeping warm time is 6-8h.

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