Titanium alloy with strong non-uniform deformation ability and high yield strength and its preparation method

Abstract

The present invention provides a titanium alloy with strong non-uniform deformation ability and high yield strength, and a preparation method thereof. The titanium alloy is alloyed with eutectoid β-stabilizing elements Cr and Fe, isomorphous β-stabilizing elements Mo and V, neutral element Zr, and matrix Ti. The preparation method includes: (1) melting to prepare an alloy ingot; (2) initial construction of the heterogeneous structure of the ingot; (3) large deformation processing of the ingot; (4) final regulation of the multi-heterogeneous alloy structure. By finely selecting the components of eutectoid and isomorphous β-stabilizing elements, the present invention enhances the alloy stability and introduces a high density of hard ω phase, which is beneficial to significantly improving the yield strength of the alloy; solves the mismatch problem of high plasticity and low yield strength of TRIP / TWIP type metastable β titanium alloy, and is applicable to the upgrading and potential applications of equipment components such as aviation, aerospace, 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 the 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 and 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 type β stabilizing element components, 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 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 type 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 , and 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:

[0009] (1) Melting and preparing an alloy ingot

[0010] 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 in a vacuum non-consumable melting furnace to obtain an alloy ingot with uniform composition;

[0011] (2) Initial construction of the heterogeneous structure of the ingot

[0012] Putting the alloy ingot prepared in step (1) into a vacuum heat treatment furnace, heating it to temperature T1 with the vacuum heat treatment furnace and holding for time t1, then cooling it to T2 with the vacuum heat treatment furnace at a cooling rate ν1 and holding for time t2, and then air-cooling to room temperature to obtain an alloy material with a preliminary heterogeneous structure;

[0013] (3) Large deformation processing of the ingot

[0014] (3.1) Mechanically processing the alloy material with a preliminary heterogeneous structure prepared in step (2) into a regular shape, then putting it into a heat treatment furnace at temperature T3 and holding for time t3, and then performing large deformation processing on the thickness direction of the alloy material by a rolling mill or forging machine so that the deformation amount in the thickness direction is λ1, and then air-cooling to room temperature to obtain a once-deformed alloy material; (3.2) Putting the once-deformed alloy material obtained in step (3.1) into a heat treatment furnace at temperature T4 and holding for time t4, then water-cooling to room temperature, and then performing secondary room-temperature rolling large deformation processing on the thickness direction of the alloy material so that the deformation amount in the thickness direction is λ2 to obtain a twice-deformed alloy material;

[0015] (4)Final regulation of the multi - heterogeneous alloy structure

[0016] Put the secondary - deformed alloy material obtained in step (3.2) into a heat - treatment furnace at temperature T5 for heat preservation for time t5, then water - cool it to room temperature, and subsequently perform mechanical treatment on the surface of the alloy material to obtain a high - performance titanium alloy material.

[0017] 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 uniformly mixed 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.

[0018] 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.

[0019] The preparation method of the titanium alloy with strong non - uniform deformation ability and high yield strength, wherein: in the step (2), the temperature T1 is 1000°C - 1100°C, the heat - preservation 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 heat - preservation time t2 is 10min - 60min.

[0020] The preparation method of the titanium alloy with strong non - uniform deformation ability and high yield strength, wherein: in the step (3.1), when performing large - deformation processing on the thickness direction of the alloy material by a rolling mill or a forging machine, 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 temperature T3 for heat - preservation for time t3 for treatment.

[0021] The preparation method of the titanium alloy with strong non - uniform deformation ability and high yield strength, wherein: in the step (3.1), the temperature T3 is 670°C - 750°C, the heat - preservation time t3 is 5min - 40min, and the deformation amount λ1 in the thickness direction is 60% - 70%.

[0022] The preparation method of the titanium alloy with strong non - uniform deformation ability and high yield strength, wherein: in the step (3.2), the temperature T4 is 520°C - 650°C, the heat - preservation time t4 is 10min - 60min, the deformation amount for each pass of room - temperature rolling of the alloy material is 2% - 8%, and the deformation amount λ2 in the thickness direction is 45 - 80%.

[0023] The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength, wherein: in the step (4), the temperature T5 is 620-850 °C, and the heat preservation time t5 is 2-120 min.

[0024] Adopting the above technical solution, the present invention has the following beneficial effects:

[0025] 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 plasticity 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.

[0026] When developing the 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, two different 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 excellent 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 the 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, namely Cr, Fe, Mo, V, and Zr.

[0027] When developing the 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 eutectoid elements, Fe and Cr have the highest β solid solution strengthening ability; among 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, secondarily adding isomorphous elements Mo and V, and adding 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.

[0028] When developing a titanium alloy with strong non-uniform deformation ability and high yield strength, in order to obtain a high yield strength, a heterogeneous structure strengthening and toughening strategy 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 the heterogeneous structure, the present invention can not only improve the yield strength of the alloy, but also improve the work hardening ability of the alloy 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. By finely selecting the eutectoid and isomorphous β-stabilizing element components, while enhancing the alloy stability and introducing a high density of fine and hard ω phases, it is beneficial to significantly improve the yield strength of the alloy.

[0029] When developing a preparation method for a titanium alloy with strong non-uniform deformation ability and high yield strength, in order to obtain a high yield strength, a processing flow is formulated around the construction of multiple heterogeneous structures. Before deformation processing, coarse lamellar α-phase is 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 alloy yield strength.

[0030] 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 phase 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 of step S3-2, the recovery and recrystallization of grains can be effectively controlled, resulting in the maximum deformation of the precipitated phase and grains inside, forming a perfect lamellar gradient heterogeneous structure, which can significantly increase the yield strength of the material.

[0031] Using the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength of the present invention, not only a 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 a super strong non-uniform deformation ability (ε non-u ≥10%) is obtained. Such a huge non-uniform deformation ability has not been reported in the published titanium alloy materials. Description of the Drawings

[0032] 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 following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0033] Figure 1 This is a flow chart of the preparation method of a titanium alloy with high yield strength and strong non-uniform deformation ability according to the present invention;

[0034] Figure 2 This is a tensile curve graph of the titanium alloy with high yield strength and strong non-uniform deformation ability according to the present invention;

[0035] Figure 3 This is a graph of the heterogeneous microstructure after the initial construction of the ingot heterogeneous structure involved in the titanium alloy with high yield strength and strong non-uniform deformation ability according to the present invention. Detailed implementation manners

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] The present invention will be further explained below in conjunction with specific implementation manners.

[0038] As Figure 1 shown, a titanium alloy with high yield strength and strong non-uniform deformation ability provided in this embodiment is alloyed with eutectoid β-stable elements Cr and Fe, isomorphous β-stable elements Mo and V, neutral element Zr, and matrix Ti.

[0039] 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.

[0040] The yield strength of the titanium alloy is , the uniform elongation is ε u ≥25%, the tensile strength is , the fracture elongation is 25% ≤ ε f ≤45%, and it has excellent strength-plasticity matching and comprehensive mechanical properties.

[0041] The non-uniform strain ε of the titanium alloy non-u ≥10%, showing strong non-uniform deformation ability.

[0042] As Figure 1 shown, the preparation method of the titanium alloy with high yield strength and strong non-uniform deformation ability according to the present invention mainly includes the following steps:

[0043] S01. Melting and preparing alloy ingots

[0044] Use sponge titanium, 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, proportion them according to the set mass percentages, and then mix the proportioned raw materials evenly. After that, melt them repeatedly 6 - 8 times in a vacuum non-consumable melting furnace. When the vacuum non-consumable melting furnace prepares the ingot, the vacuum degree ≤ 5x10 -3 Pa, apply a current of 200A - 500A, and the melting time for each pass is 1 min - 6 min to obtain an alloy ingot with uniform composition.

[0045] S02. Initial construction of the heterogeneous structure of the ingot

[0046] Put the alloy ingot prepared in step S01 into a vacuum heat treatment furnace, evacuate to a vacuum degree ≤ 3x10 -3 Pa, then heat it at a heating rate of 1ºC / min - 10ºC / min to a temperature T1 of 1000°C - 1100°C, and keep it warm for a time t1 of 1 - 2.5 h. Then, cool it with the furnace at a cooling rate ν1 of 5ºC / min - 10ºC / min to T2 of 720°C - 850°C, and keep it warm for a time t2 of 10 min - 60 min. Then, air-cool it to room temperature to obtain an alloy material with a preliminary heterogeneous structure.

[0047] S03. Large deformation processing of the ingot

[0048] S031. Machine the blank, i.e., the alloy material with a preliminary heterogeneous structure prepared in step S02, into a regular shape, and then put it into a heat treatment furnace at a temperature T3 of 670°C - 750°C and keep it warm for a time t3 of 5 min - 40 min. Then, 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%, the sample needs to be put back into the heat treatment furnace at temperature T3 for heat preservation treatment t3 to make the deformation amount in the thickness direction λ1 be 60% - 70%. Then, air-cool it to room temperature to obtain a once-deformed alloy material.

[0049] S032. Put the once-deformed alloy material obtained in step S031 into a heat treatment furnace at a temperature T4 of 520°C - 650°C and keep it warm for a time t4 of 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, and the deformation amount for each pass is 2% - 8% to make the deformation amount in the thickness direction λ2 be 45% - 80% to obtain a twice-deformed alloy material.

[0050] S04. Final regulation of the multi-heterogeneous alloy structure

[0051] Put the blank material obtained in step S032, i.e., the secondary deformed alloy, into a heat treatment furnace at a temperature T5 of 620°C to 850°C for a holding time t5 of 2 minutes to 120 minutes, then perform water cooling to room temperature, and subsequently perform mechanical treatment on the surface of the alloy to obtain a high-performance titanium alloy material.

[0052] Example 1:

[0053] 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 by mass percentage: 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.

[0054] In Example 1 of the present invention, the weight of the smelted ingot is 150 g.

[0055] 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:

[0056] S11. Smelt and prepare an alloy ingot

[0057] Use titanium sponge, pure chromium flakes, pure iron particles, pure molybdenum particles, pure vanadium particles, and pure zirconium flakes as raw materials for smelting and preparing the alloy ingot. Mix them according to the set mass percentage, that is, 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 proportioned raw materials evenly, repeatedly smelt them 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 minutes to obtain an alloy ingot with uniform composition.

[0058] S12. Initial construction of the heterogeneous structure of the ingot

[0059] Put the alloy ingot prepared in step S11 into a vacuum heat treatment furnace, evacuate to a vacuum degree ≤ 3x10 -3 Pa, then heat it at a heating rate of 5 °C / min to a temperature T1 of 1100°C and hold for a time t1 of 2 h, then cool it at a cooling rate ν1 of 5 °C / min with the furnace to T2 of 760°C and hold for a time t2 of 10 min, and then perform air cooling to room temperature to obtain an alloy material with a preliminary heterogeneous structure.

[0060] S13. Large deformation processing of the ingot

[0061] S131. Machine-process the preliminary heterogeneous tissue alloy material prepared in step S12 into a regular shape, then place it in a heat treatment furnace at a temperature T3 of 750 °C for a holding time t3 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 for each pass is about 10%, the sample needs to be placed back in the heat treatment furnace at 750 °C for 15 min of heat treatment. The deformation amount in the thickness direction is about 60% for λ1. Subsequently, air-cool to room temperature to obtain the primary deformed alloy material.

[0062] S132. Place the primary deformed alloy material obtained in step S131 in a heat treatment furnace at a temperature T4 of 600 °C for a holding time t4 of 10 min, then perform water cooling to room temperature. Subsequently, perform large deformation processing by room temperature rolling on the alloy material, with the deformation amount for each pass being about 5%, so that the deformation amount in the thickness direction is about 50% for λ2, to obtain the secondary deformed alloy material.

[0063] S14 Final regulation of the multi-heterogeneous alloy structure

[0064] After dividing the secondary deformed alloy in step S132, place them in heat treatment furnaces at temperatures T5 of 650 °C (1 # sample) and 700 °C (2 # sample) respectively for a holding time t5 of 60 min, then perform water cooling to room temperature. Subsequently, perform mechanical treatment on the alloy surface to obtain the high-performance titanium alloy material.

[0065] Table 1 shows the measured elemental composition mass fractions of the titanium alloy with strong non-uniform deformation ability and high yield strength prepared in Example 1 of the present invention. Among them, 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.

[0066] Figure 2 In 1 # and 2 # The curves are the tensile property curves of the titanium alloy with strong non-uniform deformation ability and high yield strength prepared in Example 1 of the present invention. Example 1 of the present invention carried out a uniaxial tensile experiment 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 1 # and 2# All the samples exhibited excellent strength-plasticity matching and had a wide range of application scenarios.

[0067] Figure 3 This is the microstructure diagram 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 of uniform size, and secondary α-phase precipitates are distributed at the grain boundaries of each grain, while there is a very small amount of secondary α-phase inside the grains. The non-uniformly distributed secondary α-phase in the grains forms a typical heterogeneous microstructure, laying an organizational foundation for finally obtaining a titanium alloy material with excellent comprehensive mechanical properties.

[0068] 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 it is a high-performance titanium alloy material with great application potential.

[0069] Example 2:

[0070] 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 inevitable impurity elements;

[0071] The weight of the melting ingot in Example 2 of the present invention is 150 g.

[0072] The preparation method of the high-yield-strength titanium alloy with strong non-uniform deformation ability in Example 2 of the present invention mainly includes the following steps:

[0073] S21 Melting and preparing alloy ingots

[0074] 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 percentage, 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. Then, 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.

[0075] S22 Initial construction of the heterogeneous structure of the ingot

[0076] Put the alloy ingot prepared in step S21 into a vacuum heat treatment furnace, evacuate to a vacuum degree ≤ 3x10 -3 Pa, then heat it at a heating rate of 6 °C / min to a temperature T1 of 1080 °C, and keep it for a holding time t1 of 2 h. After that, cool it with the furnace at a cooling rate ν1 of 5 °C / min to T2 of 740 °C, and keep it for a holding time t2 of 10 min, and then air-cool it to room temperature to obtain an alloy material with a preliminary heterogeneous structure.

[0077] S23 Large deformation processing of the ingot

[0078] S231 Mechanically process the alloy material with a preliminary heterogeneous structure prepared in step S22 into a regular shape, then put it into a heat treatment furnace at a temperature T3 of 720 °C and keep it for a holding time t3 of 10 min. Then, perform large deformation processing on the thickness direction of the cuboid-shaped alloy using a rolling mill or forging machine. After the deformation amount in the thickness direction of each pass is 10%, the sample needs to be put back into the heat treatment furnace at 720 °C for 10 min of treatment to make the deformation amount in the thickness direction λ1 approximately 65%. Then, air-cool it to room temperature to obtain a once-deformed alloy material.

[0079] S232 Put the once-deformed alloy material obtained in step S231 into a heat treatment furnace at a temperature T4 of 580 °C and keep it for a holding time t4 of 20 min. Then, water-cool it to room temperature. Subsequently, perform large deformation processing of room temperature rolling on the alloy material, and the deformation amount of each pass is approximately 3% to make the deformation amount in the thickness direction λ2 approximately 60% to obtain a twice-deformed alloy material.

[0080] S24 Final regulation of the multi-heterogeneous alloy structure

[0081] Put the twice-deformed alloy obtained in step S232 into a heat treatment furnace at a temperature T5 of 780 °C and keep it for a holding time t5 of 60 min. Then, water-cool it to room temperature. Subsequently, perform mechanical treatment on the alloy surface to obtain a high-performance titanium alloy material.

[0082] Table 1 shows the measured elemental composition mass fractions of the titanium alloy with strong non-uniform deformation ability and high yield strength prepared in Example 2 of the present invention, where 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.

[0083] Figure 2 medium 3 #The curve 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 for the 3 # samples, the non-uniform deformation strain is 18%, the yield strength is 1027 MPa, the uniform elongation is 30%, and the tensile strength is 1069 MPa, showing excellent strength and plasticity matching and having a wide range of application scenarios.

[0084] 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 high yield strength while maintaining high plasticity, and is a high-performance titanium alloy material with great application potential.

[0085] Example 3:

[0086] 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 unavoidable impurity elements;

[0087] The weight of the melting ingot in Example 3 of the present invention is 150 g.

[0088] The preparation method of the high yield strength titanium alloy with strong non-uniform deformation ability in Example 3 of the present invention mainly includes the following steps:

[0089] S31 Melting to prepare an alloy ingot

[0090] Using titanium sponge, pure chromium flakes, pure iron particles, pure molybdenum particles, pure vanadium particles and pure zirconium flakes as raw materials for melting to prepare an alloy ingot, and making a ratio according to the set mass percentage, 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. Then, 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.

[0091] S32 Initial construction of the heterogeneous structure of the ingot

[0092] Put the alloy ingot prepared in step S31 into a vacuum heat treatment furnace, evacuate to a vacuum degree ≤ 3x10-3 At a pressure of Pa, it was then heated at a heating rate of 5 °C / min to a temperature T1 of 1050 °C and held for a time t1 of 2 h. After that, it was cooled in the furnace at a cooling rate ν1 of 8 °C / min to T2 of 800 °C and held for a time t2 of 50 min, and then air-cooled to room temperature to obtain an alloy material with a preliminary heterogeneous structure.

[0093] Large deformation processing of the S33 ingot

[0094] S331 The alloy material with a preliminary heterogeneous structure prepared in step S32 was machined into a regular shape and then placed in a heat treatment furnace at a temperature T3 of 700 °C and held for a time t3 of 10 min. After that, large deformation processing was carried out on the thickness direction of the cuboid-shaped alloy using a rolling mill or forging machine. After the deformation amount in the thickness direction of each pass was about 8%, the sample needed to be put back into the heat treatment furnace at 700 °C for 10 min of treatment to make the deformation amount in the thickness direction λ1 about 60%. Subsequently, it was air-cooled to room temperature to obtain a once-deformed alloy material.

[0095] S332 The once-deformed alloy material obtained in step S331 was placed in a heat treatment furnace at a temperature T4 of 620 °C and held for a time t4 of 10 min. After that, it was water-cooled to room temperature. Subsequently, large deformation processing of room-temperature rolling was carried out on the alloy material, and the deformation amount of each pass was about 5% to make the deformation amount in the thickness direction λ2 about 60% to obtain a twice-deformed alloy material.

[0096] S34 Final regulation of the multi-heterogeneous alloy structure

[0097] The twice-deformed alloy obtained in step S332 was placed in a heat treatment furnace at a temperature T5 of 720 °C and held for a time t5 of 30 min. After that, it was water-cooled to room temperature. Subsequently, mechanical treatment was carried out on the alloy surface to obtain a high-performance titanium alloy material.

[0098] 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 the Ti element.

[0099] Figure 2 In 4 # The curve 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, 4 #The non-uniform deformation strain of the sample is 15%, the yield strength is 1038 MPa, the uniform elongation is 25%, and the tensile strength is 1089 MPa. It shows excellent strength-plasticity matching and has a wide range of application scenarios.

[0100] It can be seen from this that based on the preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength developed in Embodiment 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.

[0101] Table 1

[0102]

[0103] The concept of the present invention is reasonable. When designing the composition of the titanium alloy, it focuses on the positive feedback of alloying on the construction of multiple heterogeneous structures. Through the fine selection of the eutectoid-type and isomorphous-type β-stabilizing element components, while enhancing the alloy stability and introducing a high density of hard ω-phase, it is beneficial to significantly improve the alloy yield strength; 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 mismatch problem of 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.

[0104] 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 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; The yield strength of the alloy is 900 MPa to 1100 MPa, the uniform elongation is ≥ 25%, the tensile strength is 1000 MPa to 1250 MPa, the fracture elongation is 25% to 45%, and the non-uniform strain ε non-u ≥ 10%.

2. A preparation method of a titanium alloy with strong non-uniform deformation ability and high yield strength as described in claim 1, characterized in that, It mainly includes the following steps: (1) 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 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 alloy ingots 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. After heating to temperature T1 and holding for time t1 with the vacuum heat treatment furnace, it is cooled to T2 with the vacuum heat treatment furnace at a cooling rate of ν1 and held for time t2, and then air-cooled 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 T3 and hold for time t3. Then, use a rolling mill or forging machine to carry out large deformation processing on the thickness direction of the alloy material so that the deformation amount in the thickness direction is λ1. Subsequently, it is air-cooled 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 T4 and hold for time t4, then water-cool it to room temperature. Subsequently, carry out secondary room-temperature rolling large deformation processing on the thickness direction of the alloy material so that the deformation amount in the thickness direction is λ2 to obtain a twice-deformed alloy material; (4) Final regulation of the multi-heterogeneous alloy structure Put the twice-deformed alloy material obtained in step (3.2) into a heat treatment furnace at temperature T5 and hold for time t5, then water-cool it to room temperature. Subsequently, carry out mechanical treatment on the surface of the alloy material to obtain a high-performance titanium alloy material.

3. The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength according to claim 2, characterized in that: In the step (1), the uniformly mixed raw materials 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.

4. The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength according to claim 2, characterized in that: When heating in a vacuum heat treatment furnace in step (2), the vacuum degree ≤ 3x10 -3 Pa, and the heating rate of temperature rise is 1 ºC / min to 10 ºC / min.

5. The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength according to claim 2, characterized in that: The temperature T1 in step (2) is 1000 °C - 1100 °C, the holding time t1 is 1 h - 2.5 h, the cooling rate ν1 is 5 °C / min - 10 °C / min, the temperature T2 is 720 °C - 850 °C, and the holding time t2 is 10 min - 60 min.

6. The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength according to claim 2, wherein: When using a rolling mill or forging machine to carry out large deformation processing on the thickness direction of the alloy material in 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 the heat treatment furnace at temperature T3 and hold for time t3 for treatment.

7. The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength according to claim 2 or 6, characterized in that: The temperature T3 in step (3.1) is 670 °C - 750 °C, the holding time t3 is 5 min - 40 min, and the deformation amount λ1 in the thickness direction is 60% - 70%.

8. The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength according to claim 2, characterized in that: The temperature T4 in step (3.2) is 520 °C - 650 °C, the holding time t4 is 10 min - 60 min, the deformation amount for each pass of room-temperature rolling of the alloy material is 2% - 8%, and the deformation amount λ2 in the thickness direction is 45 - 80%.

9. The preparation method of the titanium alloy with strong non-uniform deformation ability and high yield strength according to claim 2, wherein: In the step (4), the temperature T5 is 620 to 850 °C, and the heat preservation time t5 is 2 to 120 minutes.

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