A light high-strength corrosion-resistant titanium alloy material and a preparation method and application thereof

Abstract

The application relates to the technical field of alloy materials, and discloses a light high-strength corrosion-resistant titanium alloy material as well as a preparation method and application thereof.The light high-strength corrosion-resistant titanium alloy material is composed of the following elements in percentage by mass: Al 3%-5%, V 2%-4%, Cr 1%-3%, Mo 2%-3%, Zr 1.5%-2.5%, Fe 0.5%-1.5%, O 0.06%-0.10%, C 0.01%-0.05%, N 0.01%-0.02%, H<=0.003%, and Ti balance.The light high-strength corrosion-resistant titanium alloy material provided by the application has a solid solution state yield strength of 940 MPa, an aging state yield strength of 1335 MPa, and a fracture elongation of 27.2%, and has good mechanical properties; the light high-strength corrosion-resistant titanium alloy material provided by the application has a pitting potential of 1.05 V in a 3.5% NaCl solution and a corrosion rate of 0.007 g / (m 2 ·h) in a 10% HCl solution, and has good corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, and more specifically, to a lightweight, high-strength, corrosion-resistant titanium alloy material, its preparation method, and its application. Background Technology

[0002] Titanium alloys, due to their low density, high specific strength, and excellent corrosion resistance, have become ideal lightweight materials for manufacturing downhole equipment in oil and gas wells. The development of deep and deep-water oil and gas wells places stringent requirements on titanium alloys used in downhole equipment, demanding a synergistic match of high strength, high toughness, and high corrosion resistance, and requiring compatibility with H2S and Cl... - Extreme service conditions involving highly corrosive media and high stress.

[0003] Existing titanium alloys for oil and gas wells are mostly designed based on traditional systems such as Ti-542, which have many technical bottlenecks: 1) The composition ratio design is simple, and the multi-element alloying elements are not introduced in a targeted manner to strengthen the structure. Furthermore, the control of interstitial impurities is not precise enough, which makes it easy to precipitate brittle Ti3Al phase and ω phase. This makes it difficult to balance solid solution strengthening and plasticity and toughness, and it is impossible to achieve both lightweight and high strength. 2) The preparation process has shortcomings. Traditional processes often use direct electrode pressing, conventional unidirectional VAR melting, unidirectional forging and single heat treatment process. Raw materials are prone to stratification and interstitial inclusions. The density and composition uniformity of the ingot are poor. After forging, the alloy grains are coarse and the anisotropy is significant. Heat treatment cannot accurately control the morphology and distribution of precipitated phases, making it difficult to achieve efficient improvement of mechanical properties. 3) The overall performance is difficult to meet the requirements of the working conditions. Existing titanium alloys either have insufficient yield strength or low elongation at break. In corrosive media such as 3.5% NaCl and HCl, the pitting potential is low and the corrosion rate is high. The synergy between corrosion resistance and mechanical properties is poor, and they cannot be adapted to the extreme operating environment of deep water oil and gas wells.

[0004] Meanwhile, the existing titanium alloy preparation process has not formed a closed-loop control of the entire process, the connection between each process is poor, and the composition design and process control are disconnected, which further leads to poor uniformity of alloy structure and large performance fluctuations, becoming the core problem restricting the large-scale application of titanium alloys in the field of oil and gas well downhole equipment.

[0005] Therefore, developing a titanium alloy material with a reasonable composition design, innovative preparation process, and the combination of lightweight, high strength, high toughness, and excellent corrosion resistance, along with its supporting preparation method, has become an urgent need for the lightweight upgrading of oil and gas well equipment and the development of deep oil and gas resources. Summary of the Invention

[0006] The purpose of this invention is to provide a lightweight, high-strength, corrosion-resistant titanium alloy material, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention: A lightweight, high-strength, corrosion-resistant titanium alloy material, composed of the following elements by mass percentage: Al 3%~5%, V 2%~4%, Cr 1%~3%, Mo 2%~3%, Zr 1.5%~2.5%, Fe 0.5%~1.5%, O0.06%~0.10%, C 0.01%~0.05%, N 0.01%~0.02%, H≤0.003%, Ti balance.

[0008] The second technical solution of this invention: The above-mentioned method for preparing a lightweight, high-strength, corrosion-resistant titanium alloy material includes the following steps: 1) Weigh the high-purity metal or master alloy according to the element mass percentage: 2) Mix the high-purity metals and intermediate alloys weighed in step 1), pre-melt them under vacuum at low temperature, and cold isostatically press them to obtain the electrode blank precursor. 3) Perform staged VAR melting and annealing on the electrode blank precursor obtained in step 2) to obtain VAR melting ingot; 4) Perform triaxial isothermal forging on the VAR melting ingot obtained in step 3) to obtain an isothermal forging ingot; 5) The isothermal forging ingot obtained in step 4) is subjected to solution treatment and aging treatment to obtain the lightweight, high-strength, corrosion-resistant titanium alloy material.

[0009] Further, in step 2), the vacuum cryogenic pre-melting specifically involves controlling the vacuum level to 5 × 10⁻⁶ under inert gas protection. -3 Pa, stirring speed of 30-50 r / min, and stirring at 200-300℃ for 1.5-2.5 h.

[0010] Further, in step 2), the cold isostatic pressing specifically involves holding the pressure at a molding pressure of 150-200 MPa for 10-20 minutes.

[0011] Further, in step 3), the staged VAR melting specifically refers to: Flow stabilization melting stage: control the vacuum level at 5×10 -3 Pa, current 3000-4000A, melting 60-90min; Solidification stage: Control the cooling rate at 10℃ / min, and rapidly cool to 300~400℃; Flow stabilization refining stage: First, control the vacuum level to 5×10. -3 The melting process is carried out at a pressure of Pa and a current of 3500–3800 A for 30–50 minutes, followed by controlling the vacuum level at 3 × 10⁻⁶. -3Pa, current 4200-4500A, melting for 40-60 minutes.

[0012] Further, in step 3), the annealing process specifically involves controlling the temperature at 850–950°C and annealing for 4–6 hours.

[0013] Further, in step 4), the triaxial isothermal forging specifically involves controlling the forging temperature to be in the α+β two-phase region, the forging rate to be 0.5~1.5mm / s, alternating deformation in three loading directions, a single-pass deformation amount of 30%~40%, and a total deformation amount ≥85%.

[0014] Further, in step 5), the solution treatment specifically involves: holding at 860–890°C for 1.5–2.5 hours, then using oil quenching and air cooling combined for rapid cooling, controlling the cooling rate at 10–20°C / s, cooling to 750–780°C, holding at that temperature for 1–2 hours, and finally using air cooling to cool to room temperature.

[0015] Further, in step 5), the aging treatment specifically involves: holding at 450–480°C for 4–6 hours, then holding at 520–550°C for 2–3 hours, and then cooling in the furnace to room temperature.

[0016] The third technical solution of this invention: The above-mentioned lightweight, high-strength, corrosion-resistant titanium alloy material is used in the manufacture of downhole equipment for oil and gas wells.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a lightweight, high-strength, corrosion-resistant titanium alloy material with a solid solution yield strength of up to 940 MPa, an aged yield strength of up to 1335 MPa, and an elongation at break of up to 27.2%, exhibiting excellent mechanical properties. The lightweight, high-strength, and corrosion-resistant titanium alloy material provided by this invention exhibits a pitting potential of up to 1.05V in 3.5% NaCl solution and a corrosion rate of 0.007g / (m²) in 10% HCl solution. 2 ·h), has good corrosion resistance.

[0018] This invention overcomes the technical bottleneck of the difficulty in synergistically achieving high strength, high toughness, and high corrosion resistance in traditional titanium alloys through component design and process innovation. Simultaneously, it achieves a lightweight design, making it suitable for the extreme corrosion and high stress conditions encountered in oil and gas wells. The specific principles and design concepts are as follows: The present invention provides a lightweight, high-strength, corrosion-resistant titanium alloy material with Ti-542 as the matrix and microalloying design. It introduces Cr and Mo dual β phase stabilizing elements and combines them with Zr and Fe for synergistic strengthening. It precisely controls the content of interstitial impurities such as O, C, N, and H, and suppresses the excessive precipitation of brittle Ti3Al phase and ω phase from the composition level. It achieves solid solution strengthening while taking into account the balance of plasticity and toughness, and also achieves lightweight composition design. The present invention provides a method for preparing lightweight, high-strength, and corrosion-resistant titanium alloy materials. This method abandons the traditional direct electrode pressing process and adds low-temperature vacuum pre-fusion and cold isostatic pressing processes. By vacuum stirring to remove impurities and activating the metal interface, the problems of raw material gaps and segregation are effectively eliminated, and a high-purity and dense electrode blank precursor is prepared, which provides a good foundation for subsequent smelting and forging processes. The present invention provides a method for preparing a lightweight, high-strength, corrosion-resistant titanium alloy material by adopting a staged VAR melting process, gradient control of vacuum degree, current and refining time, and through step-by-step operation of steady flow melting to form billets, controlled-speed solidification and homogenization, and gradient refining and purification, effectively eliminating defects such as ingot segregation, inclusions and microporosity, improving ingot purity and density, and ensuring ingot composition uniformity. The present invention provides a method for preparing lightweight, high-strength, and corrosion-resistant titanium alloy materials that breaks through the limitations of traditional unidirectional forging. It adopts a triaxial alternating isothermal precision forging process, and induces dynamic recrystallization of the alloy through triaxial orthogonal variable loading and large deformation forging, thereby achieving ultra-fine grains, significantly reducing the anisotropy of the alloy, and improving the density of the microstructure.

[0019] The present invention provides a method for preparing lightweight, high-strength, and corrosion-resistant titanium alloy materials that abandons the single heat treatment process and adopts a graded control mode of composite rapid cooling solution treatment and gradient aging. The composite rapid cooling of solution treatment and step-by-step heat preservation achieve solution phase locking. Then, the morphology, size and distribution of α precipitates are finely controlled by graded aging to induce the controllable precipitation of nanoscale dispersed strengthening phases, thereby achieving the dual effects of solution strengthening and nanoscale dispersed strengthening, and further improving the yield strength and ductility of the alloy. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0021] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] In the following examples and comparative examples, the high-purity metals and intermediate alloys are commercially available or pre-cast alloys, and are not specifically limited, as long as they can achieve the mass percentages defined in this invention.

[0026] The following embodiments illustrate a method for preparing a lightweight, high-strength, corrosion-resistant titanium alloy material, comprising the following steps: 1) Weigh out the high-purity metal or master alloy according to the following mass percentages: Al 3%~5%, V 2%~4%, Cr 1%~3%, Mo 2%~3%, Zr 1.5%~2.5%, Fe 0.5%~1.5%, O0.06%~0.10%, C 0.01%~0.05%, N 0.01%~0.02%, H≤0.003%, Ti balance; 2) Mix the high-purity metals and intermediate alloys weighed in step 1), pre-melt them under vacuum at low temperature, and cold isostatically press them to obtain the electrode blank precursor. Specifically, the vacuum cryogenic pre-melting involves controlling the vacuum level to 5 × 10⁻⁶ under inert gas protection. -3 Pa, stirring speed of 30-50 r / min, and stirring at 200-300℃ for 1.5-2.5 h; Specifically, the cold isostatic pressing process involves holding the pressure at 150–200 MPa for 10–20 minutes. 3) Perform staged VAR melting and annealing on the electrode blank precursor obtained in step 2) to obtain VAR melting ingot; Specifically, the staged VAR melting process is as follows: Flow stabilization melting stage: control the vacuum level at 5×10 -3 Pa, current 3000-4000A, melting 60-90min; Solidification stage: Control the cooling rate at 10℃ / min, and rapidly cool to 300~400℃; Flow stabilization refining stage: First, control the vacuum level to 5×10. -3 The melting process is carried out at a pressure of Pa and a current of 3500–3800 A for 30–50 minutes, followed by controlling the vacuum level at 3 × 10⁻⁶. -3 Pa, current 4200~4500A, melting 40~60min; Specifically, the annealing process involves controlling the temperature at 850–950°C and annealing for 4–6 hours. 4) Perform triaxial isothermal forging on the VAR melting ingot obtained in step 3) to obtain an isothermal forging ingot; Specifically, the triaxial isothermal forging involves controlling the forging temperature in the α+β two-phase region (780~850℃), the forging rate at 0.5~1.5mm / s, alternating deformation in three loading directions, a single-pass deformation amount of 30%~40%, and a total deformation amount ≥85%. 5) The isothermal forging ingot obtained in step 4) is subjected to solution treatment and aging treatment to obtain the lightweight, high-strength, corrosion-resistant titanium alloy material. The solution treatment specifically involves: holding the solution at 860–890°C for 1.5–2.5 hours, followed by rapid cooling using a combination of oil quenching and air cooling at a rate of 10–20°C / s to 750–780°C, holding the solution at 860–890°C for 1–2 hours, and finally air cooling to room temperature. The aging process specifically involves holding the furnace at 450–480°C for 4–6 hours, then holding it at 520–550°C for 2–3 hours, followed by furnace cooling to room temperature.

[0027] Example 1 A lightweight, high-strength, corrosion-resistant titanium alloy material 1) Weigh out the high-purity metal or master alloy according to the following mass percentages: Al 4%, V 3%, Cr 2%, Mo 2.5%, Zr 2%, Fe 1%, O 0.08%, C 0.03%, N 0.015%, H 0.001%, Ti balance; 2) Mix the high-purity metals and intermediate alloys weighed in step 1), pre-melt them under vacuum at low temperature, and cold isostatically press them to obtain the electrode blank precursor. Specifically, the vacuum cryogenic pre-melting involves controlling the vacuum level to 5 × 10⁻⁶ under inert gas protection. -3Pa, stirring speed 40 r / min, kept at 250℃ for 2 h; Specifically, the cold isostatic pressing process involves holding the pressure at 180 MPa for 15 minutes. 3) Perform staged VAR melting and annealing on the electrode blank precursor obtained in step 2) to obtain VAR melting ingot; Specifically, the staged VAR melting process is as follows: Flow stabilization melting stage: control the vacuum level at 5×10 -3 Pa, current 3500A, melting for 75 minutes; Solidification stage: Control the cooling rate at 10℃ / min, and rapidly cool to 350℃; Flow stabilization refining stage: First, control the vacuum level to 5×10. -3 The melting process was carried out at a pressure of Pa and a current of 3700 A for 40 minutes, followed by vacuum control at 3 × 10⁻⁶. -3 Pa, current 4300A, melting for 50 minutes; Specifically, the annealing process involves controlling the temperature at 900℃ and annealing for 5 hours. 4) Perform triaxial isothermal forging on the VAR melting ingot obtained in step 3) to obtain an isothermal forging ingot; Specifically, the triaxial isothermal forging involves controlling the forging temperature at 800℃ and the forging rate at 1mm / s, alternating deformation in three loading directions, with a single-pass deformation amount of 35% and a total deformation amount of 90%. 5) The isothermal forging ingot obtained in step 4) is subjected to solution treatment and aging treatment to obtain the lightweight, high-strength, corrosion-resistant titanium alloy material. The solution treatment specifically involves: holding at 870℃ for 2 hours, then using oil quenching + air cooling composite rapid cooling at a controlled cooling rate of 15℃ / s to cool to 760℃, holding at that temperature for 1.5 hours, and finally using air cooling to cool to room temperature. The aging process specifically involves holding the furnace at 460°C for 5 hours, then holding it at 530°C for 2.5 hours, and finally cooling it to room temperature.

[0028] Example 2 A lightweight, high-strength, corrosion-resistant titanium alloy material 1) Weigh out the high-purity metal or master alloy according to the following mass percentages: Al 3%, V 2%, Cr 1%, Mo 2%, Zr 1.5%, Fe 0.5%, O 0.06%, C 0.01%, N 0.01%, H 0.003%, Ti balance; 2) Mix the high-purity metals and intermediate alloys weighed in step 1), pre-melt them under vacuum at low temperature, and cold isostatically press them to obtain the electrode blank precursor. Specifically, the vacuum cryogenic pre-melting involves controlling the vacuum level to 5 × 10⁻⁶ under inert gas protection. -3 Pa, stirring speed of 30 r / min, and kept at 200℃ for 1.5 h; Specifically, the cold isostatic pressing process involves holding the pressure at 150 MPa for 10 minutes. 3) Perform staged VAR melting and annealing on the electrode blank precursor obtained in step 2) to obtain VAR melting ingot; Specifically, the staged VAR melting process is as follows: Flow stabilization melting stage: control the vacuum level at 5×10 -3 Pa, current 3000A, melting for 60 minutes; Solidification stage: Control the cooling rate at 10℃ / min, and rapidly cool to 300℃; Flow stabilization refining stage: First, control the vacuum level to 5×10. -3 The melting process was carried out at a pressure of Pa and a current of 3500A for 30 minutes, followed by a vacuum control of 3×10⁻⁶. -3 Pa, current 4200A, melting for 40 minutes; Specifically, the annealing process involves controlling the temperature at 850°C and annealing for 4 hours. 4) Perform triaxial isothermal forging on the VAR melting ingot obtained in step 3) to obtain an isothermal forging ingot; Specifically, the triaxial isothermal forging involves controlling the forging temperature at 780℃ and the forging rate at 0.5mm / s, alternating deformation in three loading directions, with a single-pass deformation of 30% and a total deformation of 90%. 5) The isothermal forging ingot obtained in step 4) is subjected to solution treatment and aging treatment to obtain the lightweight, high-strength, corrosion-resistant titanium alloy material. Specifically, the solution treatment involves holding the solution at 860°C for 1.5 hours, followed by rapid cooling using a combination of oil quenching and air cooling at a controlled cooling rate of 10°C / s, cooling the solution to 750°C, holding the solution at 860°C for 1 hour, and finally cooling the solution to room temperature using air cooling. The aging process specifically involves holding the furnace at 450°C for 4 hours, then holding it at 520°C for 2 hours, and finally cooling it to room temperature.

[0029] Example 3 A lightweight, high-strength, corrosion-resistant titanium alloy material 1) Weigh out the high-purity metal or master alloy according to the following mass percentages: Al 5%, V 4%, Cr 3%, Mo 3%, Zr 2.5%, Fe 1.5%, O 0.10%, C 0.05%, N 0.02%, H 0.002%, Ti balance; 2) Mix the high-purity metals and intermediate alloys weighed in step 1), pre-melt them under vacuum at low temperature, and cold isostatically press them to obtain the electrode blank precursor. Specifically, the vacuum cryogenic pre-melting involves controlling the vacuum level to 5 × 10⁻⁶ under inert gas protection. -3 Pa, stirring speed of 50 r / min, and kept at 300℃ for 2.5 h; Specifically, the cold isostatic pressing process involves holding the pressure at 200 MPa for 20 minutes. 3) Perform staged VAR melting and annealing on the electrode blank precursor obtained in step 2) to obtain VAR melting ingot; Specifically, the staged VAR melting process is as follows: Flow stabilization melting stage: control the vacuum level at 5×10 -3 Pa, current 4000A, melting for 90 minutes; Solidification stage: Control the cooling rate at 10℃ / min, and rapidly cool to 400℃; Flow stabilization refining stage: First, control the vacuum level to 5×10. -3 The melting process was carried out at a pressure of Pa and a current of 3800 A for 50 minutes, followed by vacuum control at 3 × 10⁻⁶. -3 Pa, current 4500A, melting for 60 minutes; Specifically, the annealing process involves controlling the temperature at 950°C and annealing for 6 hours. 4) Perform triaxial isothermal forging on the VAR melting ingot obtained in step 3) to obtain an isothermal forging ingot; Specifically, the triaxial isothermal forging involves controlling the forging temperature at 850℃ and the forging rate at 1.5mm / s, alternating deformation in three loading directions, with a single-pass deformation of 40% and a total deformation of 95%. 5) The isothermal forging ingot obtained in step 4) is subjected to solution treatment and aging treatment to obtain the lightweight, high-strength, corrosion-resistant titanium alloy material. Specifically, the solution treatment involves holding the solution at 890°C for 2.5 hours, followed by rapid cooling using a combination of oil quenching and air cooling at a controlled cooling rate of 20°C / s, cooling the solution to 780°C, holding the solution at 890°C for 2 hours, and finally cooling the solution to room temperature using air cooling. The aging process specifically involves holding the furnace at 480°C for 6 hours, then holding it at 550°C for 3 hours, followed by furnace cooling to room temperature.

[0030] Comparative Example 1 A titanium alloy material Same as Example 1, except that step 1) is: Weigh out the high-purity metal or master alloy according to the following mass percentages: Sn 6%, V 3%, Cr 2%, Mo 2.5%, Fe 1%, O 0.08%, C 0.03%, N 0.015%, H 0.001%, Ti balance.

[0031] Comparative Example 2 A titanium alloy material Same as Example 1, except that step 1) is: Weigh out the high-purity metal or master alloy according to the following mass percentages: Al 4%, V 5%, Cr 0.5%, Mo 1.5%, Zr 2%, Fe 1%, O 0.08%, C 0.03%, N 0.015%, H 0.001%, Ti balance.

[0032] Comparative Example 3 A titanium alloy material Same as Example 1, except that step 1) is: Weigh out the high-purity metal or master alloy according to the following mass percentages: Al 4%, V 3%, Cr 2%, Mo 2.5%, Zr 2%, Fe 1%, O 0.15%, C 0.08%, N 0.015%, H 0.001%, Ti balance.

[0033] Comparative Example 4 A titanium alloy material Same as Example 1, except that step 3) is: The electrode blank precursor obtained in step 2) is subjected to VAR melting and annealing to obtain VAR melting ingot; Specifically, the VAR melting process involves controlling the vacuum level to 5×10⁻⁶. -3 Pa, current 3800A, melting for 150min; Specifically, the annealing process involves controlling the temperature at 900℃ and annealing for 5 hours.

[0034] Comparative Example 5 A titanium alloy material Same as Example 1, except that step 3) is: The electrode blank precursor obtained in step 2) is subjected to staged VAR melting to obtain VAR melting ingot; Specifically, the staged VAR melting process is as follows: Flow stabilization melting stage: control the vacuum level at 5×10 -3 Pa, current 3500A, melting for 75 minutes; Solidification stage: Control the cooling rate at 10℃ / min, and rapidly cool to 350℃; Flow stabilization refining stage: First, control the vacuum level to 5×10. -3 The melting process was carried out at a pressure of Pa and a current of 3700 A for 40 minutes, followed by vacuum control at 3 × 10⁻⁶. -3 Pa, current 4300A, melting for 50 minutes.

[0035] Comparative Example 6 A titanium alloy material Same as Example 1, except that step 4) is: The VAR melting ingot obtained in step 3) is subjected to unidirectional isothermal forging to obtain an isothermal forging ingot; Specifically, the unidirectional isothermal forging involves controlling the forging temperature to 800℃, the forging rate to 1mm / s, unidirectional forging, and a total deformation of 90%.

[0036] Comparative Example 7 A titanium alloy material Same as Example 1, except that step 5) is: The isothermal forging ingot obtained in step 4) is subjected to solution treatment and aging treatment to obtain the lightweight, high-strength, corrosion-resistant titanium alloy material. Specifically, the solution treatment involves holding the solution at 870°C for 2 hours, followed by rapid cooling using a combination of oil quenching and air cooling at a rate of 15°C / s to cool it to room temperature. The aging process specifically involves holding the furnace at 460°C for 5 hours, then holding it at 530°C for 2.5 hours, and finally cooling it to room temperature.

[0037] Effect verification I. Mechanical property testing The mechanical properties of the titanium alloy materials prepared in Examples 1-3 and Comparative Examples 1-7 were tested, and the results are shown in Table 1. Table 1 Mechanical property test results

[0038] As shown in Table 1, the lightweight, high-strength, corrosion-resistant titanium alloy material provided by this invention has a solution-treated yield strength of up to 940 MPa, an aged yield strength of up to 1335 MPa, and an elongation at break of up to 27.2%, exhibiting excellent mechanical properties.

[0039] II. Corrosion Resistance Testing The corrosion resistance of the titanium alloy materials prepared in Examples 1-3 and Comparative Examples 1-7 was tested, and the results are shown in Table 2. Table 2 Corrosion Resistance Test Results

[0040] As shown in Table 2, the lightweight, high-strength, and corrosion-resistant titanium alloy material provided by this invention has a pitting potential of up to 1.05V in 3.5% NaCl solution and a corrosion rate of 0.007g / (m²) in 10% HCl solution. 2 ·h), has good corrosion resistance.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A lightweight, high-strength, corrosion-resistant titanium alloy material, characterized in that, It consists of the following elements by mass percentage: Al 3%~5%, V 2%~4%, Cr 1%~3%, Mo 2%~3%, Zr 1.5%~2.5%, Fe 0.5%~1.5%, O0.06%~0.10%, C 0.01%~0.05%, N 0.01%~0.02%, H≤0.003%, Ti balance.

2. A method for preparing a lightweight, high-strength, corrosion-resistant titanium alloy material as described in claim 1, characterized in that, Includes the following steps: 1) Weigh the high-purity metal or master alloy according to the element mass percentage: 2) Mix the high-purity metals and intermediate alloys weighed in step 1), pre-melt them under vacuum at low temperature, and cold isostatically press them to obtain the electrode blank precursor. 3) Perform staged VAR melting and annealing on the electrode blank precursor obtained in step 2) to obtain VAR melting ingot; 4) Perform triaxial isothermal forging on the VAR melting ingot obtained in step 3) to obtain an isothermal forging ingot; 5) The isothermal forging ingot obtained in step 4) is subjected to solution treatment and aging treatment to obtain the lightweight, high-strength, corrosion-resistant titanium alloy material.

3. The method for preparing lightweight, high-strength, corrosion-resistant titanium alloy material according to claim 2, characterized in that, In step 2), the vacuum cryogenic pre-melting specifically involves controlling the vacuum level to 5 × 10⁻⁶ under inert gas protection. -3 Pa, stirring speed of 30-50 r / min, and stirring at 200-300℃ for 1.5-2.5 h.

4. The method for preparing lightweight, high-strength, corrosion-resistant titanium alloy material according to claim 2, characterized in that, In step 2), the cold isostatic pressing specifically involves holding the pressure at 150-200 MPa for 10-20 minutes.

5. The method for preparing lightweight, high-strength, corrosion-resistant titanium alloy material according to claim 2, characterized in that, In step 3), the staged VAR melting specifically refers to: Flow stabilization melting stage: control the vacuum level at 5×10 -3 Pa, current 3000-4000A, melting 60-90min; Solidification stage: Control the cooling rate at 10℃ / min, and rapidly cool to 300~400℃; Flow stabilization refining stage: First, control the vacuum level to 5×10. -3 The melting process is carried out at a pressure of Pa and a current of 3500–3800 A for 30–50 minutes, followed by controlling the vacuum level at 3 × 10⁻⁶. -3 Pa, current 4200-4500A, melting for 40-60 minutes.

6. The method for preparing lightweight, high-strength, corrosion-resistant titanium alloy material according to claim 2, characterized in that, In step 3), the annealing process specifically involves controlling the temperature at 850–950°C and annealing for 4–6 hours.

7. The method for preparing lightweight, high-strength, corrosion-resistant titanium alloy material according to claim 2, characterized in that, In step 4), the three-dimensional isothermal forging specifically involves controlling the forging temperature to be in the α+β two-phase region, the forging rate to be 0.5~1.5mm / s, alternating deformation in three loading directions, a single-pass deformation amount of 30%~40%, and a total deformation amount ≥85%.

8. The method for preparing lightweight, high-strength, corrosion-resistant titanium alloy material according to claim 2, characterized in that, In step 5), the solution treatment specifically involves: holding at 860–890°C for 1.5–2.5 hours, followed by rapid cooling using a combination of oil quenching and air cooling, with a cooling rate controlled at 10–20°C / s, cooling to 750–780°C, holding at that temperature for 1–2 hours, and finally air cooling to room temperature.

9. The method for preparing lightweight, high-strength, corrosion-resistant titanium alloy material according to claim 2, characterized in that, In step 5), the aging treatment specifically involves: holding at 450–480°C for 4–6 hours, then holding at 520–550°C for 2–3 hours, and then cooling in the furnace to room temperature.

10. The application of the lightweight, high-strength, corrosion-resistant titanium alloy material as described in claim 1 in the manufacture of downhole equipment for oil and gas wells.

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