Titanium alloy with high non-uniform deformability and high yield strength and preparation method thereof

Abstract

The invention provides a titanium alloy with strong non-uniform deformability and high yield strength and a preparation method thereof. The titanium alloy is formed by alloying eutectoid beta stable elements Cr and Fe, isomorphic beta stable elements Mo and V, a neutral element Zr and a matrix Ti. The preparation method comprises the following steps: (1) smelting to prepare an alloy ingot; (2) primary construction of a heterogeneous structure of the cast ingot; (3) performing large deformation processing on the cast ingot; and (4) final regulation and control of multiple heterogeneous alloy structures. Through fine matching and selection of eutectoid and isomorphic beta stable element components, the stability of the alloy is enhanced, and a high-density hard omega phase is introduced, so that the yield strength of the alloy is remarkably improved; the problem of mismatching of high plasticity and low yield strength of the TRIP / TWIP type metastable beta titanium alloy is solved, and the TRIP / TWIP type metastable beta titanium alloy is suitable for upgrading and potential application of equipment parts such as aviation, spaceflight and armored weapons.

Description

Technical Field

[0001] The present invention relates to the technical field of advanced metal materials, and particularly relates to a titanium alloy with strong non-uniform deformation ability and high yield strength and a preparation method thereof. Background Art

[0002] High-strength and tough titanium alloys have characteristics such as high specific strength, strong corrosion resistance, and stable mechanical properties at medium and low temperatures, and are widely used in many fields such as aviation, aerospace, and ships. However, the strengthening methods of traditional high-strength and tough titanium alloys usually regulate the precipitation behavior of α-phase in the alloy, and use the α / β phase interface to hinder the movement of dislocations to achieve the purpose of strengthening, resulting in prominent problems such as insufficient strength-plasticity matching, poor work hardening, and low strength-plasticity product, which greatly limits its application prospects in the field of high-end equipment manufacturing.

[0003] Research shows that high-strength and tough metastable β titanium alloys with TRIP / TWIP effects (Transformation Induced Plasticity / Twin Induced Plasticity) developed based on the DX-Vα molecular orbital theory introduce stress-induced phase transformation or deformation twins during the alloy deformation process, which can significantly improve the uniform plastic deformation ability and work hardening rate of the alloy, thereby improving the strength-plasticity matching relationship of the titanium alloy. However, currently, the TRIP / TWIP type metastable β titanium alloys developed based on the DX-Vα molecular orbital theory can usually obtain an elongation of up to 20-35%, but their yield strength is only 300-750 MPa. Thus, how to obtain a high yield strength (1000 MPa) while maintaining ultra-high plasticity (≥30%) has become a research and development technical bottleneck for TRIP / TWIP type metastable β titanium alloys. Summary of the Invention

[0004] Aiming at the technical problems existing in the above background art, the present invention proposes a titanium alloy with strong non-uniform deformation ability and high yield strength and a preparation method thereof. Its concept is reasonable. When designing the composition of the titanium alloy, the positive feedback of alloying on the construction of multiple heterogeneous structures is emphasized. Through the fine selection of eutectoid-type and isomorphous β-stabilizing element components, while enhancing the alloy stability and introducing high-density hard ω-phase, it is beneficial to significantly improve the yield strength of the alloy; in the alloy preparation and processing technology, a processing flow is formulated around the construction of multiple heterogeneous structures, and through the method of enhancing and plasticizing multiple heterogeneous structures, the problem of mismatch between high plasticity and low yield strength of TRIP / TWIP type metastable β titanium alloys is solved, and it is applicable to the upgrading and potential applications of equipment components such as aviation, aerospace, and armored weapons.

[0005] To solve the above technical problems, a titanium alloy with strong non-uniform deformation ability and high yield strength provided by the present invention is characterized in that the titanium alloy is alloyed and composed of eutectoid-type β-stabilizing elements Cr and Fe, isomorphous β-stabilizing elements Mo and V, neutral element Zr, and matrix Ti.

[0006] The titanium alloy with strong non-uniform deformation ability and high yield strength, wherein the titanium alloy is composed of the following elements in mass percentages: Cr is 3.2 - 4.8%, Fe is 1.0 - 1.8%, Mo is 2.2 - 3.2%, V is 0.4 - 0.8%, Zr is 0.6 - 1.3%, and the balance is Ti and inevitable impurity elements.

[0007] The titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: the yield strength of the alloy is , the uniform elongation is ε u ≥25%, the tensile strength is , the fracture elongation is 25% ≤ ε f ≤45%, and the non-uniform strain ε non-u ≥10%.

[0008] A preparation method of a titanium alloy with strong non-uniform deformation ability and high yield strength mainly includes the following steps: (1) Melting to prepare an alloy ingot Using titanium sponge, pure chromium flakes, pure iron particles, pure molybdenum particles, pure vanadium particles, and pure zirconium flakes as raw materials and proportioning them according to the set mass percentages. Then, after mixing the proportioned raw materials evenly, they are repeatedly melted by a vacuum non-consumable melting furnace to obtain an alloy ingot with uniform composition; (2) Initial construction of the heterogeneous structure of the ingot Put the alloy ingot prepared in step (1) into a vacuum heat treatment furnace, heat it to temperature T 1 and keep it warm for time t 1 After that, cool it to T 1 with the cooling rate ν 2 and keep it warm for time t 2 , and then air-cool it to room temperature to obtain an alloy material with a preliminary heterogeneous structure; (3) Large deformation processing of the ingot (3.1) Mechanically process the alloy material with a preliminary heterogeneous structure prepared in step (2) into a regular shape, then put it into a heat treatment furnace at temperature T 3 and keep it warm for time t 3 After that, use a rolling mill or forging machine to perform large deformation processing on the thickness direction of the alloy material so that the deformation amount in the thickness direction is λ 1 , and then air-cool it to room temperature to obtain a once-deformed alloy material; (3.2) Put the once-deformed alloy material obtained in step (3.1) into a heat treatment furnace at temperature T 4 and keep it warm for time t 4After that, it is water-cooled to room temperature, and then the alloy material is subjected to secondary room-temperature rolling large-deformation processing in the thickness direction so that the deformation amount in the thickness direction is λ 2 , and a secondary deformed alloy material is obtained; (4)Final regulation of the multi-heterogeneous alloy structure The secondary deformed alloy material obtained in step (3.2) is placed in a heat treatment furnace at a temperature of T 5 for a holding time of t 5 After that, it is water-cooled to room temperature, and then the surface of the alloy material is mechanically treated to obtain a high-performance titanium alloy material.

[0009] In the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: in the step (1), the raw materials after being mixed evenly are repeatedly melted 6-8 times by a vacuum non-consumable melting furnace, and the vacuum degree of the vacuum non-consumable melting furnace during melting is ≤ 5x10 -3 Pa, the applied current is 200A - 500A, and the melting time for each time is 1min - 6min.

[0010] In the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: in the step (2), the vacuum degree during heating by the vacuum heat treatment furnace is ≤ 3x10 -3 Pa, and the heating rate of temperature rise is 1 ºC / min - 10ºC / min.

[0011] In the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: the temperature T 1 in the step (2) is 1000°C - 1100°C, the holding time t 1 is 1h - 2.5h, the cooling rate ν 1 is 5ºC / min - 10ºC / min, the temperature T 2 is 720°C - 850°C, and the holding time t 2 is 10min - 60min.

[0012] In the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: when the alloy material is subjected to large-deformation processing in the thickness direction by a rolling mill or a forging machine in the step (3.1), the deformation amount in the thickness direction for each pass is 5% - 10%, and it is necessary to put the processed sample back into a heat treatment furnace at a temperature of T 3 for a holding time of t 3 for treatment.

[0013] In the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: the temperature T 3 in the step (3.1) is 670°C - 750°C, and the holding time t 3is 5 min to 40 min, and the deformation amount λ in the thickness direction 1 is 60% to 70%.

[0014] The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: the temperature T in the step (3.2) 4 is 520 °C to 650 °C, and the heat preservation time t 4 is 10 min to 60 min. The deformation amount of each pass of room temperature rolling of the alloy material is 2% to 8%, and the deformation amount λ in the thickness direction 2 is 45 to 80%.

[0015] The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: the temperature T in the step (4) 5 is 620 to 850 °C, and the heat preservation time t 5 is 2 to 120 min.

[0016] Adopting the above technical solution, the present invention has the following beneficial effects: The titanium alloy with strong non-uniform deformation ability and high yield strength and its preparation method of the present invention are reasonably conceived. When designing the composition of the titanium alloy, the positive feedback of alloying on the construction of multiple heterogeneous structures is emphasized. Through the fine selection of the composition of eutectoid-type and isomorphous-type β-stabilizing elements, while enhancing the alloy stability and introducing high-density hard ω phase, it is beneficial to significantly improve the yield strength of the alloy; in the alloy preparation method, a processing flow is formulated around the construction of multiple heterogeneous structures, and through the method of enhancing and plasticizing with multiple heterogeneous structures, the problem of mismatch between high plasticity and low yield strength of TRIP / TWIP-type metastable β titanium alloy is solved, and it is applicable to the upgrading and potential application of equipment components such as aviation, aerospace, and armored weapons.

[0017] When the present invention develops a titanium alloy with strong non-uniform deformation ability and high yield strength, in order to obtain high yield strength, the composition design principle of multi-element composite alloying is introduced. First, when selecting β-stabilizing elements, eutectoid-type and isomorphous-type β-stabilizing elements are added in combination. Secondly, when selecting eutectoid-type or isomorphous-type β-stabilizing elements, the same two types of alloying elements are also added in combination. The establishment of this multi-element composite alloying principle is closely related to the mature Ti-12Mo alloy, which has extraordinary plasticity (>35%) but low yield strength (~450 MPa). One of the key factors leading to the strength-plasticity mismatch of this alloy is that the alloy is alloyed with a single isomorphous Mo element. Based on this, it is confirmed that the multi-element composite alloying element group consists of eutectoid-type β-stabilizing elements Cr and Fe, isomorphous-type β-stabilizing elements Mo and V, and neutral element Zr to regulate the stability of the alloy, that is, the composition of the titanium alloy of the present invention is composed of five alloying elements including Cr, Fe, Mo, V, and Zr.

[0018] When developing a titanium alloy with strong non-uniform deformation ability and high yield strength, in order to obtain high yield strength, according to the Mo equivalent empirical formula and the DX-Vα molecular orbital theory, among the eutectoid elements, Fe and Cr have the highest β solid solution strengthening ability; while among the isomorphous elements, Mo and V have the highest β solid solution strengthening ability. Based on this, it is confirmed to select the principle of mainly adding eutectoid elements Cr and Fe, secondly adding isomorphous elements Mo and V, and a small amount of neutral element Zr to regulate the stability of the alloy, laying a foundation for maximizing the solid solution strengthening ability of the β matrix.

[0019] When developing a titanium alloy with strong non-uniform deformation ability and high yield strength, in order to obtain high yield strength, a strategy of strengthening tough heterogeneous structures is introduced. Research shows that the single β-phase Ti-3Al-5Mo-7V-3Cr alloy has a relatively high yield strength (750 MPa), but its elongation is relatively low. Through the regulation of heterogeneous structures in this invention, not only can the yield strength of the alloy be improved, but also the work hardening ability of the alloy can be enhanced through back stress hardening, thereby improving the elongation of the alloy. Based on this, when designing the composition of the titanium alloy, the positive feedback of multi-element composite alloying on the construction of multiple heterogeneous structures is emphasized. Through the fine selection of eutectoid and isomorphous β-stabilizing element compositions, while enhancing the stability of the alloy and introducing a high density of fine and hard ω phases, it is beneficial to significantly improve the yield strength of the alloy.

[0020] When developing a preparation method for a titanium alloy with strong non-uniform deformation ability and high yield strength, in order to obtain high yield strength, a processing flow is formulated around the construction of multiple heterogeneous structures. Before deformation processing, coarse lamellar α phases are introduced; after deformation processing, through the regulation of the annealing process, relatively small α-phase particles are introduced, thereby obtaining a multiple heterogeneous microstructure, laying a foundation for obtaining a high yield strength of the alloy.

[0021] When developing a preparation method for a titanium alloy with strong non-uniform deformation ability and high yield strength, in order to finely regulate the spatial distribution and morphology of the precipitated phases and grains, a two-step deformation processing method is adopted in the large deformation processing of the ingot in step S3. In the room temperature deformation processing in step S3-2, the recovery and recrystallization of grains can be effectively controlled, resulting in the maximum deformation of the precipitated phases and grains inside, forming a perfect lamellar gradient heterogeneous structure, which can significantly increase the yield strength of the material.

[0022] By using the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength of the present invention, not only high yield strength and tensile strength as well as excellent uniform elongation (ε u ≥25%) and fracture elongation (25%≤ε f ≤45%) are obtained, but also super strong non-uniform deformation ability (εnon-u ≥ 10%), such a large non-uniform deformation ability has not been reported in the published titanium alloy materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a flowchart of the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength of the present invention; Figure 2 It is a tensile curve diagram of the titanium alloy with strong non-uniform deformation ability and high yield strength of the present invention; Figure 3 It is a diagram of the heterogeneous microstructure after the initial construction of the ingot heterogeneous structure involved in the titanium alloy with strong non-uniform deformation ability and high yield strength of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] The following further explains the present invention in conjunction with specific embodiments.

[0027] As Figure 1 shown, a titanium alloy with strong non-uniform deformation ability and high yield strength provided in this embodiment is alloyed with eutectoid β-stabilizing elements Cr and Fe, isomorphous β-stabilizing elements Mo and V, neutral element Zr, and matrix Ti.

[0028] Among them, the titanium alloy is composed of the following elements by mass percentage: Cr is 3.2 - 4.8%, Fe is 1.0 - 1.8%, Mo is 2.2 - 3.2%, V is 0.4 - 0.8%, Zr is 0.6 - 1.3%, and the balance is Ti and inevitable impurity elements.

[0029] The yield strength of the titanium alloy is , the uniform elongation is ε u ≥ 25%, the tensile strength is , and the fracture elongation is 25% ≤ ε f≤45%, with excellent strength-plasticity matching and comprehensive mechanical properties.

[0030] The non-uniform strain ε of the titanium alloy non-u ≥10%, showing strong non-uniform deformation ability.

[0031] Such as Figure 1 As shown, the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength of the present invention mainly includes the following steps: S01. Melting and preparing alloy ingots Using titanium sponge, pure chromium sheets, pure iron particles, pure molybdenum particles, pure vanadium particles and pure zirconium sheets as raw materials for melting and preparing alloy ingots, proportioning according to the set mass percentage, and then mixing the proportioned raw materials evenly. After that, it is repeatedly melted 6-8 times by a vacuum non-consumable melting furnace. When the vacuum non-consumable melting furnace prepares the ingot, the vacuum degree ≤ 5x10 -3 Pa, the applied current is 200A~500A, and the melting time for each pass is 1 min~6min, obtaining an alloy ingot with uniform composition.

[0032] S02. Initial construction of the heterogeneous structure of the ingot Put the alloy ingot prepared in step S01 into a vacuum heat treatment furnace, evacuate to a vacuum degree ≤ 3x10 -3 Pa, and then heat it at a heating rate of 1ºC / min~10ºC / min to a temperature T 1 of 1000°C~1100°C, and keep it warm for a time t 1 of 1~2.5h, and then cool it at a cooling rate ν 1 of 5ºC / min~10ºC / min with the furnace to T 2 of 720°C~850°C, and keep it warm for a time t 2 of 10 min~60min, and then air-cool it to room temperature to obtain an alloy material with a preliminary heterogeneous structure.

[0033] S03. Large deformation processing of the ingot S031. Machine the blank prepared in step S02, that is, the alloy material with a preliminary heterogeneous structure, into a regular shape, and then put it into a heat treatment furnace at a temperature T 3 of 670°C~750°C and keep it warm for a time t 3 of 5min~40min. After that, use a rolling mill or forging machine to perform large deformation processing on the thickness direction of the alloy material. After the deformation amount in the thickness direction for each pass is 5%~10%, it is necessary to put the sample back into the heat treatment furnace at a temperature of T 3 for heat preservation t 3 treatment to make the deformation amount in the thickness direction be λ 1It is 60% - 70%, and then it is air-cooled to room temperature to obtain a primary deformed alloy material.

[0034] S032. Put the primary deformed alloy material obtained in step S031 into a heat treatment furnace at a temperature of T 4 which is 520°C - 650°C and keep it for a holding time t 4 which is 10 min - 60 min, then water-cool it to room temperature. Subsequently, perform secondary room-temperature rolling large deformation processing on the thickness direction of the alloy material, with the deformation amount per pass being 2% - 8%, so that the deformation amount in the thickness direction is λ 2 which is 45% - 80% to obtain a secondary deformed alloy material.

[0035] S04. Final regulation of the multi-heterogeneous alloy structure Put the blank, i.e., the secondary deformed alloy obtained in step S032, into a heat treatment furnace at a temperature of T 5 which is 620°C - 850°C and keep it for a holding time t 5 which is 2 min - 120 min, then water-cool it to room temperature. Subsequently, perform mechanical treatment on the alloy surface to obtain a high-performance titanium alloy material.

[0036] Example 1:

[0037] In Example 1 of the present invention, the titanium alloy with strong non-uniform deformation ability and high yield strength mainly consists of the following elements in mass percentages: Cr is 4.5%, Fe is 1.0%, Mo is 2.2%, V is 0.6%, Zr is 0.85%, and the balance is Ti and inevitable impurity elements.

[0038] In Example 1 of the present invention, the weight of the melting ingot is 150 g.

[0039] The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength in Example 1 of the present invention mainly includes the following steps: S11. Melting and preparing an alloy ingot Use titanium sponge, pure chromium flakes, pure iron particles, pure molybdenum particles, pure vanadium particles, and pure zirconium flakes as raw materials for melting and preparing the alloy ingot. Mix them according to the set mass percentages, i.e., 136.3 g of titanium sponge, 6.8 g of pure chromium flakes, 1.5 g of pure iron particles, 3.3 g of pure molybdenum particles, 0.9 g of pure vanadium particles, and 1.3 g of pure zirconium flakes. Then, after mixing the raw materials evenly, melt them repeatedly 8 times through a vacuum non-consumable melting furnace. When the vacuum non-consumable melting furnace prepares the ingot, the vacuum degree is 6x10 - 4 Pa, the applied current is 200 A - 500 A, and the melting time per pass is about 2 min to obtain an alloy ingot with uniform composition.

[0040] S12. Initial construction of the heterogeneous structure of the ingot Put the alloy ingot prepared in step S11 into a vacuum heat treatment furnace, evacuate to a vacuum degree ≤ 3x10 -3 Pa, and then heat it at a heating rate of 5 °C / min to a temperature T 1 of 1100 °C, and keep it for a holding time t 1 of 2 h. After that, cool it at a cooling rate ν 1 of 5 °C / min to T 2 of 760 °C, and keep it for a holding time t 2 of 10 min, and then air-cool it to room temperature to obtain an alloy material with a preliminary heterogeneous structure.

[0041] S13. Large deformation processing of the ingot S131. Machine the alloy material with a preliminary heterogeneous structure prepared in step S12 into a regular shape, and then put it into a heat treatment furnace at a temperature T 3 of 750 °C for a holding time t 3 of 15 min. After that, use a rolling mill or forging machine to perform large deformation processing on the thickness direction of the cuboid-shaped alloy. After the deformation amount in the thickness direction of each pass is about 10%, the sample needs to be put back into the heat treatment furnace at a temperature of 750 °C for 15 min of treatment. The deformation amount in its thickness direction is λ 1 of about 60%. Then air-cool it to room temperature to obtain a once-deformed alloy material.

[0042] S132. Put the once-deformed alloy material obtained in step S131 into a heat treatment furnace at a temperature T 4 of 600 °C for a holding time t 4 of 10 min. After that, water-cool it to room temperature, and then perform large deformation processing of room temperature rolling on the alloy material. The deformation amount of each pass is about 5%, so that the deformation amount in the thickness direction is λ 2 of about 50% to obtain a twice-deformed alloy material.

[0043] S14. Final regulation of the multi-heterogeneous alloy structure After dividing the twice-deformed alloy in step S132, put them into heat treatment furnaces at temperatures T 5 of 650 °C (1 # sample) and 700 °C (2 # sample) for a holding time t 5 both of 60 min. After that, water-cool it to room temperature, and then perform mechanical treatment on the alloy surface to obtain a high-performance titanium alloy material.

[0044] Table 1 shows the measured mass fractions of elemental components of the high-yield-strength titanium alloy with strong non-uniform deformation ability prepared in Example 1 of the present invention, where Cr is 4.62%, Fe is 1.01%, Mo is 2.31%, V is 0.62%, Zr is 0.86%, O is 0.077, N is 0.019%, H is 0.0047, and the rest is Ti element.

[0045] Figure 2 In 1 # and 2 # The curves are the tensile property curves of the high-yield-strength titanium alloy with strong non-uniform deformation ability prepared in Example 1 of the present invention. In Example 1 of the present invention, a uniaxial tensile experiment was carried out under room temperature conditions on a standard testing machine (Instron 8801). The test results show that under the preparation conditions of Example 1 of the present invention, for the 1 # sample, the non-uniform deformation strain is 17%, the yield strength is 1087 MPa, the uniform elongation is 27%, and the tensile strength is 1179 MPa; for the 2 # sample, the non-uniform deformation strain is 15%, the yield strength is 977 MPa, the uniform elongation is 33%, and the tensile strength is 1089 MPa. For the 1 # and 2 # samples, both show excellent strength and plasticity matching and have a wide range of application scenarios.

[0046] Figure 3 This is the micrograph of the titanium alloy after the initial construction of the heterogeneous structure of the S12 ingot in Example 1 of the present invention. As can be seen from the figure, the matrix structure is composed of grains with uniform sizes, and secondary α phases are precipitated at the grain boundaries of each grain, while there are very few secondary α phases inside the grains. The non-uniformly distributed secondary α phases in the grains form a typical heterogeneous microstructure, laying an organizational foundation for finally obtaining a titanium alloy material with excellent comprehensive mechanical properties.

[0047] It can be seen from this that based on the preparation method of the high-yield-strength titanium alloy with strong non-uniform deformation ability developed in Example 1 of the present invention, this high-performance titanium alloy material can have high yield strength while maintaining high plasticity, and is a high-performance titanium alloy material with great application potential.

[0048] Example 2:

[0049] The nominal composition of the high-yield-strength titanium alloy with strong non-uniform deformation ability in Example 2 of the present invention mainly consists of the following elements by mass percentage: Cr is 4.0%, Fe is 1.3%, Mo is 2.5%, V is 0.6%, Zr is 0.85%, and the balance is Ti and unavoidable impurity elements; The weight of the melting ingot in Example 2 of the present invention is 150 g.

[0050] The preparation method of a high-yield-strength titanium alloy with strong non-uniform deformation ability according to Embodiment 2 of the present invention mainly includes the following steps: S21 Melting and preparing an alloy ingot Using titanium sponge, pure chromium flakes, pure iron particles, pure molybdenum particles, pure vanadium particles, and pure zirconium flakes as raw materials for melting and preparing the alloy ingot, and proportioning them according to the set mass percentages, that is, 136.1 g of titanium sponge, 6 g of pure chromium flakes, 2 g of pure iron particles, 3.8 g of pure molybdenum particles, 0.9 g of pure vanadium particles, and 1.3 g of pure zirconium flakes. Subsequently, after mixing the proportioned raw materials evenly, they are repeatedly melted 8 times in a vacuum non-consumable melting furnace. When the vacuum non-consumable melting furnace prepares the ingot, the vacuum degree is 6x10 -4 Pa, the applied current is 200 A to 500 A, and the melting time for each pass is about 2 min, obtaining an alloy ingot with uniform composition.

[0051] S22 Initial construction of the heterogeneous structure of the ingot Put the alloy ingot prepared in step S21 into a vacuum heat treatment furnace, evacuate to a vacuum degree ≤ 3x10 -3 Pa, and then heat it at a heating rate of 6 °C / min to a temperature T 1 of 1080 °C, and keep it warm for a time t 1 of 2 h. After that, cool it at a cooling rate ν 1 of 5 °C / min furnace-cooled to T 2 of 740 °C, and keep it warm for a time t 2 of 10 min, and then air-cool it to room temperature to obtain an alloy material with a preliminary heterogeneous structure.

[0052] S23 Large deformation processing of the ingot S231 Mechanically process the alloy material with the preliminary heterogeneous structure prepared in step S22 into a regular shape, and then put it into a heat treatment furnace at a temperature T 3 of 720 °C and keep it warm for a time t 3 of 10 min. After that, use a rolling mill or forging machine to perform large deformation processing on the thickness direction of the cuboid-shaped alloy. After the deformation amount in the thickness direction for each pass is 10%, the sample needs to be put back into the heat treatment furnace at a temperature of 720 °C and kept warm for 10 min to make the deformation amount in the thickness direction λ 1 about 65%, and then air-cool it to room temperature to obtain a once-deformed alloy material.

[0053] S232 Put the once-deformed alloy material obtained in step S231 into a heat treatment furnace at a temperature T 4 of 580 °C and keep it warm for a time t 4After 20 min, water cooling is carried out to room temperature, and then large deformation processing of room temperature rolling is carried out on the alloy material. The deformation amount of each pass is about 3%, and the deformation amount in the thickness direction is λ 2 which is about 60% to obtain a secondary deformed alloy material.

[0054] Final regulation of the S24 multi-heterogeneous alloy structure Put the secondary deformed alloy obtained in step S232 into a heat treatment furnace at a temperature of T 5 which is 780 °C and keep it for a heat preservation time t 5 which is 60 min, then water cooling is carried out to room temperature, and then mechanical treatment is carried out on the alloy surface to obtain a high-performance titanium alloy material.

[0055] Table 1 shows the measured elemental composition mass fractions of the high-yield-strength titanium alloy with strong non-uniform deformation ability prepared in Example 2 of the present invention. Among them, Cr is 3.85%, Fe is 1.17%, Mo is 2.46%, V is 0.65%, Zr is 0.89%, O is 0.081, N is 0.022%, H is 0.0052, and the rest is Ti element.

[0056] Figure 2 in 3 # The curve in 3 is the tensile property curve of the high-yield-strength titanium alloy with strong non-uniform deformation ability prepared in Example 2 of the present invention. In Example 2 of the present invention, a uniaxial tensile experiment was carried out under room temperature conditions on a standard testing machine (Instron 8801). The test results show that under the preparation conditions of Example 2 of the present invention, the 3 # sample has a non-uniform deformation strain of 18%, a yield strength of 1027 MPa, a uniform elongation of 30%, and a tensile strength of 1069 MPa, showing an excellent strength-plasticity matching and having a wide range of application scenarios.

[0057] It can be seen from this that based on the preparation method of the high-yield-strength titanium alloy with strong non-uniform deformation ability developed in Example 2 of the present invention, this high-performance titanium alloy material can have a high yield strength while maintaining high plasticity, and is a high-performance titanium alloy material with great application potential.

[0058] Example 3:

[0059] The nominal composition of the high-yield-strength titanium alloy with strong non-uniform deformation ability in Example 3 of the present invention mainly consists of the following elements by mass percentage: Cr is 3.5%, Fe is 1.6%, Mo is 3.0%, V is 0.6%, Zr is 0.85%, and the balance is Ti and inevitable impurity elements; The weight of the melting ingot in Example 3 of the present invention is 150 g.

[0060] The preparation method of the high-yield-strength titanium alloy with strong non-uniform deformation ability in Embodiment 3 of the present invention mainly includes the following steps: S31 Melting and preparing alloy ingots Using titanium sponge, pure chromium flakes, pure iron particles, pure molybdenum particles, pure vanadium particles and pure zirconium flakes as raw materials for melting and preparing alloy ingots, and proportioning them according to the set mass percentages, that is, 135.7 g of titanium sponge, 5.3 g of pure chromium flakes, 2.4 g of pure iron particles, 4.5 g of pure molybdenum particles, 0.9 g of pure vanadium particles and 1.3 g of pure zirconium flakes. Subsequently, after mixing the proportioned raw materials evenly, they are repeatedly melted 8 times in a vacuum non-consumable melting furnace. When the vacuum non-consumable melting furnace prepares the ingot, the vacuum degree is 6x10 - 4 Pa, the applied current is 200 A - 500 A, and the melting time for each pass is about 2 min, to obtain an alloy ingot with uniform composition.

[0061] S32 Primary construction of the heterogeneous structure of the ingot Put the alloy ingot prepared in step S31 into a vacuum heat treatment furnace, evacuate to a vacuum degree ≤ 3x10 -3 Pa, and then heat it at a heating rate of 5 °C / min to a temperature T 1 of 1050 °C, and keep it warm for a time t 1 of 2 h. After that, cool it at a cooling rate ν 1 of 8 °C / min with the furnace to T 2 of 800 °C, and keep it warm for a time t 2 of 50 min, and then air-cool it to room temperature to obtain an alloy material with a preliminary heterogeneous structure.

[0062] S33 Large deformation processing of the ingot S331 Mechanically process the alloy material with the preliminary heterogeneous structure prepared in step S32 into a regular shape, and then put it into a heat treatment furnace at a temperature T 3 of 700 °C and keep it warm for a time t 3 of 10 min. After that, use a rolling mill or forging machine to perform large deformation processing on the thickness direction of the cuboid-shaped alloy. After the deformation amount in the thickness direction for each pass is about 8%, the sample needs to be put back into the heat treatment furnace at a temperature of 700 °C and kept warm for 10 min to make the deformation amount in the thickness direction be λ 1 about 60%, and then air-cool it to room temperature to obtain a once-deformed alloy material.

[0063] S332 Put the once-deformed alloy material obtained in step S331 into a heat treatment furnace at a temperature T 4 of 620 °C and keep it warm for a time t 4After 10 min, water cooling is carried out to room temperature. Subsequently, large deformation processing of room temperature rolling is carried out on the alloy material, and the deformation amount per pass is about 5%, so that the deformation amount in the thickness direction is λ 2 which is about 60% to obtain a secondary deformed alloy material.

[0064] Final regulation of the S34 multi-heterogeneous alloy structure Put the secondary deformed alloy obtained in step S332 into a heat treatment furnace at a temperature of T 5 which is 720 °C and keep it for a time t 5 which is 30 min. Then water cooling is carried out to room temperature. Subsequently, mechanical treatment is carried out on the alloy surface to obtain a high-performance titanium alloy material.

[0065] Table 1 shows the measured elemental composition mass fractions of the high-yield-strength titanium alloy with strong non-uniform deformation ability prepared in Example 3 of the present invention. Among them, Cr is 3.36%, Fe is 1.66%, Mo is 2.87%, V is 0.63%, Zr is 0.82%, O is 0.068, N is 0.018%, H is 0.0042, and the rest is Ti element.

[0066] Figure 2 in 4 # The curve in 4 is the tensile property curve of the high-yield-strength titanium alloy with strong non-uniform deformation ability prepared in Example 3 of the present invention. In Example 3 of the present invention, a uniaxial tensile experiment was carried out under room temperature conditions on a standard testing machine (Instron 8801). The test results show that under the preparation conditions of Example 3 of the present invention, the 4 # sample has a non-uniform deformation strain of 15%, a yield strength of 1038 MPa, a uniform elongation of 25%, and a tensile strength of 1089 MPa, showing excellent strength and plasticity matching and having a wide range of application scenarios.

[0067] It can be seen from this that based on the preparation method of the high-yield-strength titanium alloy with strong non-uniform deformation ability developed in Example 3 of the present invention, this high-performance titanium alloy material can have high yield strength while maintaining high plasticity, and is a high-performance titanium alloy material with great application potential.

[0068] Table 1

[0069] The inventive concept is reasonable. When designing the composition of titanium alloys, emphasis is placed on considering the positive feedback of alloying on the construction of multiple heterogeneous microstructures. Through the fine selection of the compositions of eutectoid-type and isomorphous β-stabilizing elements, while enhancing the alloy stability and introducing a high density of hard ω-phase, it is beneficial to significantly improve the yield strength of the alloy. In the alloy preparation and processing technology, a processing flow is formulated around the construction of multiple heterogeneous microstructures, and through the method of enhancing plasticity with multiple heterogeneous microstructures, the problem of the mismatch between high plasticity and low yield strength of TRIP / TWIP-type metastable β-titanium alloys is solved, which is applicable to the upgrading and potential applications of equipment components such as aviation, aerospace, and armored weapons.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A titanium alloy with strong non-uniform deformation ability and high yield strength, characterized in that The titanium alloy is composed of alloying eutectoid β-stabilizing elements Cr and Fe, isomorphous β-stabilizing elements Mo and V, neutral element Zr and matrix Ti.

2. The titanium alloy with strong non-uniform deformation ability and high yield strength as claimed in claim 1, characterized in that: The titanium alloy is composed of the following elements in mass percentage: 3.2-4.8% Cr, 1.0-1.8% Fe, 2.2-3.2% Mo, 0.4-0.8% V, 0.6-1.3% Zr, and the remainder is Ti and unavoidable impurity elements.

3. The titanium alloy with strong non-uniform deformation ability and high yield strength as claimed in claim 1, characterized in that: The yield strength of the alloy is , the uniform elongation is ε u ≥25%, tensile strength , elongation at break is 25%≤ε f ≤45%, non-uniform strain ε non-u ≥10%.

4. A method for preparing a titanium alloy having strong non-uniform deformation ability and high yield strength as claimed in any one of claims 1 to 3, characterized in that: The main steps include: (1) Melting and preparing alloy ingots Sponge titanium, pure chromium flakes, pure iron particles, pure molybdenum particles, pure vanadium particles and pure zirconium flakes are used as raw materials and are proportioned according to a set mass percentage. Subsequently, the proportioned raw materials are evenly mixed and repeatedly smelted in a vacuum non-consumable smelting furnace to obtain an alloy ingot with uniform composition. (2) Initial construction of ingot heterogeneous structure The alloy ingot prepared in step (1) is placed in a vacuum heat treatment furnace, heated to a temperature T1 and kept at a temperature of t1 in the vacuum heat treatment furnace, then cooled to a temperature T2 at a cooling rate v1 and kept at a temperature of t2 in the vacuum heat treatment furnace, and then air-cooled to room temperature to obtain an alloy material with a preliminary heterogeneous structure; (3) Large deformation processing of ingots (3.1) machining the alloy material with a preliminary heterogeneous structure prepared in step (2) into a regular shape, then placing it in a heat treatment furnace at a temperature of T3 for a holding time of t3, and then using a rolling mill or a forging machine to perform a large deformation process on the thickness direction of the alloy material so that the deformation amount in the thickness direction is λ1, and then air cooling it to room temperature to obtain a primary deformed alloy material; (3.2) placing the primary deformed alloy material obtained in step (3.1) in a heat treatment furnace at a temperature of T4 for a holding time of t4, cooling it to room temperature with water, and then performing secondary room temperature rolling large deformation processing in the thickness direction of the alloy material, so that the deformation amount in the thickness direction is λ2, thereby obtaining a secondary deformed alloy material; (4) Final control of multiple heterogeneous alloy structures The secondary deformed alloy material obtained in step (3.2) is placed in a heat treatment furnace at a temperature of T5 for a holding time of t5, and then water-cooled to room temperature. The surface of the alloy material is then mechanically treated to obtain a high-performance titanium alloy material.

5. The method for preparing a titanium alloy having strong non-uniform deformation capability and high yield strength as claimed in claim 4, characterized in that: In the step (1), the raw materials after uniform mixing are repeatedly melted 6-8 times in a vacuum non-consumable melting furnace, and the vacuum degree of the vacuum non-consumable melting furnace during melting is ≤5x10 -3 Pa, the applied current is 200A~500A, and the melting time each time is 1min~6min.

6. The method for preparing a titanium alloy having strong non-uniform deformation capability and high yield strength as claimed in claim 4, characterized in that: The vacuum degree of the vacuum heat treatment furnace used in step (2) is ≤3x10 -3 Pa, the heating rate is 1 ºC / min~10ºC / min.

7. The method for preparing a titanium alloy having strong non-uniform deformation capability and high yield strength as claimed in claim 4, characterized in that: The temperature T1 in step (2) is 1000°C~1100°C, the holding time t1 is 1h~2.5h, the cooling rate ν1 is 5ºC / min~10ºC / min, the temperature T2 is 720°C~850°C, and the holding time t2 is 10min~60min.

8. The method for preparing a titanium alloy having strong non-uniform deformation capability and high yield strength as claimed in claim 4, characterized in that: When a rolling mill or a forging machine is used to perform large deformation processing on the alloy material in the thickness direction in the step (3.1), the deformation amount in the thickness direction of each pass is 5% to 10%, and the processed sample needs to be put back into a heat treatment furnace at a temperature of T3 for a holding time of t3.

9. The method for preparing a titanium alloy having strong non-uniform deformation ability and high yield strength as claimed in claim 4 or 8, characterized in that: The temperature T3 in the step (3.1) is 670°C to 750°C, the holding time t3 is 5min to 40min, and the deformation λ1 in the thickness direction is 60% to 70%.

10. The method for preparing a titanium alloy having strong non-uniform deformation capability and high yield strength as claimed in claim 4, characterized in that: In the step (3.2), the temperature T4 is 520°C to 650°C, the holding time t4 is 10min to 60min, the deformation of the alloy material in each room temperature rolling is 2% to 8%, and the deformation λ2 in the thickness direction is 45% to 80%.

11. The method for preparing a titanium alloy having strong non-uniform deformation capability and high yield strength as claimed in claim 4, characterized in that: In step (4), the temperature T5 is 620-850°C, and the insulation time t5 is 2-120 min.

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