Titanium alloy based on lamellar alpha phase and nanophase precipitation and preparation method thereof

Abstract

The invention discloses a titanium alloy based on lamellar alpha phase and nanophase precipitation and a preparation method of the titanium alloy, belongs to the field of titanium alloy materials, and aims to solve the bottleneck that strength and work hardening of a high-strength titanium alloy are difficult to cooperate. The titanium alloy comprises, by weight, 2.0%-7.5% of Al, 1.0%-6.0% of V, 1%-8% of x (x is at least one eutectoid beta stable element of Fe, Mn, Cr, Ni and Cu) and the balance Ti and impurities. And the beta-phase molybdenum equivalent [Mo] eq is controlled to be 5.0-10.0. The preparation method comprises the following steps: 1) smelting an ingot for three times in a vacuum consumable electric arc furnace, and cutting a dead head after scaling and flaw detection; (2) carrying out hot rolling at 810-950 DEG C in an alpha + beta two-phase region with the accumulative deformation amount of 75-95%, and constructing a multi-scale lamellar alpha phase, and (3) carrying out solid solution for 30-120 minutes at 700-850 DEG C, rapidly cooling at 50-250 DEG C / s, and inducing the precipitation of a nano eutectoid compound. Aging treatment is not needed, the yield strength is greater than 900 MPa, the work hardening amount is greater than 150 MPa, the elongation is greater than or equal to 15%, the process is simple and easy to industrialize, and the method can be applied to the fields of aerospace, ocean engineering and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of titanium alloy materials, and particularly relates to a titanium alloy based on lamellar alpha phase and nano-phase precipitation and a preparation method thereof. BACKGROUND

[0002] Titanium alloys are widely used in aerospace, marine engineering and biomedical fields due to their high specific strength, excellent corrosion resistance and good biocompatibility. In order to meet the demand of modern high-end equipment for structural lightweight and performance improvement, the development of high-strength titanium alloys has become an important research direction.

[0003] However, the development of high-strength titanium alloys has long been restricted by the core contradiction of "difficulty in synergistic improvement of strength and work hardening ability". On the one hand, although the titanium alloy using metastable beta phase stress / strain induced martensitic transformation or deformation twinning can obtain a certain work hardening effect, its yield strength is usually difficult to exceed 800 MPa due to the low critical stress of phase transformation or twinning. On the other hand, although the high-strength titanium alloy dominated by dislocation slip deformation can achieve high yield strength brought by high dislocation density, its intracrystalline dislocation storage capacity is poor, and the strain hardening ability is insufficient, resulting in low uniform elongation and premature fracture.

[0004] At present, in order to solve the above problems, the industry mainly designs heterogeneous structures (such as lamellar structure and multi-scale grains) through severe plastic deformation combined with solid solution-aging treatment. However, these traditional methods still have limitations: either sacrificing uniform elongation (<6%) in order to obtain high yield strength (>800 MPa), or making the work hardening amount (the promotion interval from yield strength to tensile strength) too low, usually less than 50 MPa, in order to ensure a certain uniform elongation. Therefore, developing a titanium alloy and its preparation method which can simultaneously realize yield strength greater than 900 MPa, work hardening amount more than 150 MPa and elongation not less than 15%, has become a technical bottleneck that needs to be broken through in the field. SUMMARY

[0005] The purpose of the present application is to provide a titanium alloy based on lamellar alpha phase and nano-phase precipitation and a preparation method thereof. In particular, a multi-scale lamellar alpha phase structure is obtained by using a simple alpha+beta two-phase zone hot rolling process combined with a solid solution treatment process, and a nano-scale eutectoid compound is precipitated, thereby playing a significant strengthening and strain hardening role, and realizing a breakthrough combination of high yield strength, high work hardening ability and plastic deformation ability.

[0006] In order to achieve the above purpose, the present application provides the following technical solutions: A titanium alloy based on lamellar alpha phase and nanophase precipitation, the titanium alloy chemical composition is: Al: 2.0%-7.5%; V: 1.0%-6.0%; x: 1%-8%, the x is one of Fe, Mn, Cr, Ni, Cu, and when x is two or more elements, 1%-8% is the total content of these elements; the balance is Ti and unavoidable impurities; the titanium alloy beta phase molybdenum equivalent [Mo] eq Control in the range of 5.0~10.0, wherein [Mo] eq =0.67V+1.6Cr+2.5Fe+1.54Mn+1.11Ni+0.77Cu.

[0007] A preparation method of a titanium alloy based on lamellar alpha phase and nanophase precipitation, comprising the following sequential steps: S1, melting and ingot treatment: three times of melting in a vacuum consumable arc furnace to obtain an ingot, skinning treatment (remove the surface oxide layer and defect layer) is performed on the ingot and ultrasonic flaw detection is carried out, and the ingot riser is cut off; S2, hot rolling deformation: the ingot treated in step S1 is hot rolled in the alpha+beta two-phase region, the hot rolling temperature is 810℃~950℃, and the cumulative deformation is 75%~95%, to obtain an alloy billet; S3, solution treatment: the alloy billet obtained in step S2 is subjected to solution treatment, the holding temperature range is 700℃~850℃, the holding time range is 30min~120min, and then it is rapidly cooled to room temperature at a cooling rate of 50℃ / s~250℃ / s.

[0008] Further, in step S1, after obtaining the ingot, the beta transition temperature T β of the titanium alloy is measured.

[0009] Further, after step S1 and before step S2, the ingot is subjected to homogenization heat treatment, the treatment temperature is T β +(100-200)℃, and the holding time is 12h~48h.

[0010] Further, after the homogenization heat treatment and before step S2, the ingot is subjected to multi-stage forging to obtain a forged bloom; the hot rolling in step S2 is carried out on the forged bloom; the multi-stage forging is a key pretreatment step to realize the heterogeneous structure for subsequent hot rolling, and the specific parameters need to match the beta transition temperature T β of the titanium alloy.

[0011] Further, the multi-stage forging includes: the breakdown forging temperature is T β +(100-200)℃, and the single-phase zone forging temperature is T β+(100-150)℃, the forging temperature of the two-phase region is T β -80℃, finished product forging temperature is T β -100℃; after each forging pass, grinding is performed, and the deformation of each forging sequence is controlled within the range of 50% to 75%.

[0012] Furthermore, the hot rolling described in step S2 specifically involves: [the process is described in the original text, but the translation is incomplete]. β The first rolling process is carried out at -120℃, with a rolling deformation of 70% to 80%; subsequently, it is carried out at T... β The second rolling process is carried out at -150℃; the cumulative deformation during rolling is 75%~95%. After each rolling pass, the material is ground and then peeled (the oxide scale is removed) after the last rolling pass to obtain the alloy billet.

[0013] Further, after step S3, a solution treatment is performed at a temperature of 700℃~850℃ for 30min~120min, followed by rapid cooling to room temperature.

[0014] Furthermore, in step S1, when preparing the ingot, sponge titanium, Al bean, AlV master alloy, TiCu master alloy and sponge zirconium are used as raw materials, weighed and batched according to the chemical composition ratio of the alloy design, and then pressed into electrodes after mixing for vacuum consumable arc melting.

[0015] The beneficial effects of this invention are: 1. This invention achieves precise composition design and utilizes the β-phase molybdenum equivalent [Mo]. eq Controlling the concentration within the range of 5.0 to 10.0 provides a compositional basis for the precipitation of nanophases during subsequent heat treatment, which is a prerequisite for achieving high strength and high work hardening.

[0016] 2. The core of the preparation method of this invention lies in the synergistic effect of three sequential steps: First, a uniform and defect-free ingot is obtained through step S1; then, a crucial multi-scale lamellar α-phase heterostructure is constructed through step S2 (hot rolling in the α+β two-phase region at 810℃~950℃, with a cumulative deformation of 75%~95%), which forms the structural basis for obtaining high work hardening capability; finally, nanoscale co-eutectoid compounds are induced to precipitate at the heterostructure interface through step S3 (solution treatment at 700℃~850℃ followed by rapid cooling), thereby simultaneously introducing a significant precipitation strengthening effect. These three steps are interconnected and indispensable, jointly solving the problem of the mutual constraint between strength and work hardening capability.

[0017] 3. The titanium alloy prepared by the specific method of this invention achieves a breakthrough in the matching of strength, plasticity, and work hardening capacity. As shown in the examples, its yield strength can be greater than 900 MPa, while the work hardening amount (the range from yield strength to tensile strength) is consistently higher than 150 MPa, and the elongation is not less than 15%. This comprehensive performance is significantly better than that of traditional high-strength titanium alloys.

[0018] 4. The preparation process of this invention is simple and efficient. Its strengthening mechanism does not depend on the phase transformation of the metastable β phase, but rather on the composite strengthening method of "heterogeneous structure + nanophase precipitation". It has higher stability and is easy to carry out industrial production and control, providing a reliable material solution for the safe application of high-performance titanium alloys in key fields such as aerospace, marine engineering, and automotive industry. Attached Figure Description

[0019] Figure 1 The images show the microstructure of the alloy in Example 1 of this invention after solution treatment and quenching. (a) is a BSE image, showing that the alloy's microstructure has two regions: light and dark. The grains in the light region are elongated, while the grains in the dark region are lamellar. (b) PM image confirms that the elongated microstructure is the α phase and the lamellar microstructure is the β phase. (c) GB+BC image shows that the alloy's microstructure contains fully recrystallized large grains and incompletely recrystallized small grains. (d) TEM bright-field image reveals a lamellar microstructure with alternating α and β phases, and nano-Ti2Cu phase is observed at the α and β phase boundaries.

[0020] Figure 2 This is an engineering stress-strain curve of the alloy in Example 1 of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments and comparative examples. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] Example 1 1. Composition and Design: By weight percentage, the composition is: Al: 6.0%, V: 4.0%, Cu: 5.5%, with the balance being Ti and unavoidable impurities. The calculated molybdenum equivalent [Mo] of this composition is... eq =0.67×4.0 (V)+0.77×5.5 (Cu)=2.68+4.235=6.915, which falls within the range of 5.0 to 10.0.

[0023] 2. Melting and Ingot Treatment (S1): Sponge titanium, Al briquettes, AlV master alloys, and TiCu master alloys are used as raw materials, mixed in the above proportions, and pressed into electrodes. The electrodes are then melted three times in a vacuum arc remelting furnace to obtain ingots. The ingots are then peeled, ultrasonically tested, and the risers are removed. The β-transformation temperature Ta of the alloy is determined using metallographic microscopy. β =980℃.

[0024] 3. Preliminary heat treatment and deformation: The ingot is placed in a T... β The material undergoes a high-temperature homogenization treatment at +150℃ for 24 hours. This is followed by multi-stage forging: the initial forging temperature is T... β +150℃, the forging temperature in the single-phase region is T. β +120℃, the forging temperature of the two-phase region is T β -80℃, finished product forging temperature is T β -100℃; the deformation amount of each forging sequence is controlled at about 60%, and finally a forged square billet is obtained.

[0025] 4. Hot rolling deformation (S2): In T β The first rolling process is carried out at -120℃ (approximately 860℃), with a rolling deformation of 70%–80%; subsequently, it is carried out at T... β The second rolling process is carried out at -150℃ (approximately 830℃); the cumulative deformation during rolling is 95%. After each rolling pass, the material is ground and then peeled off after the last rolling pass to obtain the alloy billet.

[0026] 5. Solution treatment (S3): The alloy billet obtained in step S2 is subjected to solution treatment at a holding temperature of 740℃ for 30 minutes, followed by water quenching to room temperature.

[0027] 6. Performance Results: Room temperature tensile testing revealed that the alloy exhibited a yield strength of 950 MPa, a tensile strength of 1130 MPa, a work hardening amount of 180 MPa, and an elongation of 18.0%. The microstructure of the alloy in this embodiment after solution-quenching treatment is shown in the image. Figure 1 The engineering stress-strain curve of the alloy is shown in [reference needed]. Figure 2 .

[0028] Example 2 1. Composition and Design: By weight percentage, the composition is: Al: 5.5%, V: 3.5%, Mn: 4.8%, with the balance being Ti and unavoidable impurities. Molybdenum equivalent [Mo] eq =0.67×3.5(V)+1.54×4.8(Mn)=2.345+7.392=9.737, which falls within the range of 5.0~10.0.

[0029] 2. Melting and Ingot Treatment (S1): Using TiMn master alloy, the materials are prepared and mixed according to the above proportions, then pressed into electrodes. The electrodes are then melted three times in a vacuum arc remelting furnace to obtain ingots. The ingots are then subjected to peeling, ultrasonic testing, and riser removal, and the Tg is measured. β =970℃.

[0030] 3. Preliminary heat treatment and deformation: High-temperature homogenization and multi-stage forging are performed, with parameters the same as in Example 1, according to T β Adjustment.

[0031] 4. Hot rolling deformation (S2): In T β The first rolling process is carried out at -120℃ (approximately 850℃), with a rolling deformation of 70%–80%; subsequently, it is carried out at T... β The second rolling process is carried out at -150℃ (approximately 820℃); the cumulative deformation during rolling is 90%, and grinding is performed after each rolling pass. After the last rolling pass, the outer layer is peeled off to obtain the alloy billet.

[0032] 5. Solution treatment (S3): Perform solution treatment at 790℃ and hold for 45 minutes, then quench in water to room temperature.

[0033] 6. Performance results: Yield strength is 945MPa, tensile strength is 1113MPa, work hardening amount is 168MPa, and elongation is 18.5%.

[0034] Example 3 1. Composition and Design: By weight percentage, the composition is: Al: 2.0%, V: 4.0%, Cr: 3.0%, with the balance being Ti and unavoidable impurities. Molybdenum equivalent [Mo] eq =0.67×4.0 (V)+1.6×3.0 (Cr)=2.68+4.8=7.48, which falls within the range of 5.0~10.0.

[0035] 2. Melting and Ingot Treatment (S1): Using TiCr master alloy, T was measured. β =1010℃.

[0036] 3. Preliminary heat treatment and deformation: High-temperature homogenization and multi-stage forging are performed, with parameters the same as in Example 1, according to T β Adjustment.

[0037] 4. Hot rolling deformation (S2): In T β The first rolling process is carried out at -120℃ (approximately 890℃), with a rolling deformation of 70%–80%; subsequently, it is carried out at T... βThe second rolling process is carried out at -150℃ (approximately 860℃); the cumulative deformation during rolling is 75%. After each rolling pass, the material is ground and then peeled off after the last rolling pass to obtain the alloy billet.

[0038] 5. Solution treatment (S3): Perform solution treatment at 790℃ and hold for 60 minutes, then quench in water to room temperature.

[0039] 6. Performance results: Yield strength is 936MPa, tensile strength is 1092MPa, work hardening amount is 156MPa, and elongation is 20.5%.

[0040] Example 4 1. Composition and Design: By weight percentage, the composition is: Al: 7.5%, V: 3.5%, Ni: 4.5%, with the balance being Ti and unavoidable impurities. Molybdenum equivalent [Mo] eq =0.67×3.5(V)+1.11×4.5(Ni)=2.345+4.995=7.34, which falls within the range of 5.0~10.0.

[0041] 2. Smelting and Ingot Processing (S1): Using TiNi master alloy, T was measured. β =960℃.

[0042] 3. Preliminary heat treatment and deformation: High-temperature homogenization and multi-stage forging are performed, with parameters the same as in Example 1, according to T β Adjustment.

[0043] 4. Hot rolling deformation (S2): In T β The first rolling process is carried out at -120℃ (approximately 840℃), with a rolling deformation of 70%–80%; subsequently, it is carried out at T... β The second rolling process is carried out at -150℃ (approximately 810℃); the cumulative deformation during rolling is 85%. After each rolling pass, the material is ground and then peeled off after the last rolling pass to obtain the alloy billet.

[0044] 5. Solution treatment (S3): Perform solution treatment at 750℃ and hold for 30 minutes, then quench in water to room temperature.

[0045] 6. Performance results: Yield strength is 975MPa, tensile strength is 1145MPa, work hardening amount is 170MPa, and elongation is 17.0%.

[0046] Example 5 1. Composition and Design: By weight percentage, the composition is: Al: 4.5%, V: 4.2%, Fe: 2.6%, with the balance being Ti and unavoidable impurities. Molybdenum equivalent [Mo] eq=0.67×4.2 (V)+2.5×2.6 (Fe)=2.814+6.5=9.314, which falls within the range of 5.0~10.0.

[0047] 2. Smelting and Ingot Processing (S1): Using TiFe master alloy, T was measured. β =972℃.

[0048] 3. Preliminary heat treatment and deformation: High-temperature homogenization and multi-stage forging are performed, with parameters the same as in Example 1, according to T β Adjustment.

[0049] 4. Hot rolling deformation (S2): In T β The first rolling process is carried out at -120℃ (approximately 855℃), with a rolling deformation of 70%–80%; subsequently, it is carried out at T... β The second rolling process is carried out at -150℃ (approximately 825℃); the cumulative deformation during rolling is 88%. After each rolling pass, the material is ground and then peeled off after the last rolling pass to obtain the alloy billet.

[0050] 5. Solution treatment (S3): Perform solution treatment at 770℃ and hold for 40 minutes, then quench in water to room temperature.

[0051] 6. Performance results: Yield strength is 958 MPa, tensile strength is 1128 MPa, work hardening amount is 170 MPa, and elongation is 18.2%.

[0052] Example 6 1. Composition and Design: By weight percentage, the composition is: Al: 5.0%, V: 4.5%, Cr: 3.5%, Zr: 0.3%, with the balance being Ti and unavoidable impurities. Molybdenum equivalent [Mo] eq =0.67×4.5(V)+1.6×3.5(Cr)=3.015+5.6=8.615, which falls within the range of 5.0~10.0.

[0053] 2. Melting and Ingot Treatment (S1): Sponge titanium, Al briquettes, AlV master alloy, TiCr master alloy, and sponge zirconium are used as raw materials, mixed in the above proportions, and pressed into electrodes. The electrodes are then melted three times in a vacuum arc remelting furnace to obtain ingots. The ingots are then peeled, ultrasonically tested, and the risers are removed. The β-transformation temperature Ta of the alloy is determined using metallographic microscopy. β =995℃.

[0054] 3. Preliminary heat treatment and deformation: The ingot is placed in a T... β The material undergoes a high-temperature homogenization treatment at +150℃ for 24 hours. This is followed by multi-stage forging: the initial forging temperature is T... β +150℃, the forging temperature in the single-phase region is T.β +120℃, the forging temperature of the two-phase region is T β -80℃, finished product forging temperature is T β -100℃; the deformation amount of each forging sequence is controlled at about 60%, and finally a forged square billet is obtained.

[0055] 4. Hot rolling deformation (S2): In T β The first rolling process is carried out at -120℃ (approximately 875℃), with a rolling deformation of 70%–80%; subsequently, it is carried out at T... β The second rolling process is carried out at -150℃ (approximately 845℃); the cumulative deformation during rolling is 92%. After each rolling pass, the material is ground and then peeled off after the last rolling pass to obtain the alloy billet.

[0056] 5. Solution treatment (S3): Perform solution treatment at 780℃ and hold for 50 minutes, then quench in water to room temperature.

[0057] 6. Performance results: The room temperature tensile test showed that the alloy had a yield strength of 962 MPa, a tensile strength of 1140 MPa, a work hardening amount of 178 MPa, and an elongation of 18.8%.

[0058] Example 7 1. Composition and Design: By weight percentage, the composition is: Al: 5.0%, V: 4.0%, Fe: 2.0%, Cu: 2.0%, with the balance being Ti and unavoidable impurities. The calculated molybdenum equivalent [Mo] of this composition is... eq =0.67×4.0(V)+2.5×2.0(Fe)+0.77×2.0(Cu)=2.68+5.0+1.54=9.22, which falls within the range of 5.0 to 10.0.

[0059] 2. Melting and Ingot Processing (S1): Sponge titanium, Al briquettes, AlV master alloys, TiFe master alloys, and TiCu master alloys are used as raw materials, mixed in the above proportions, and pressed into electrodes. The electrodes are then melted three times in a vacuum arc remelting furnace to obtain ingots. The ingots are then peeled, ultrasonically tested, and the risers are removed. The β-transformation temperature Ta of the alloy is determined using metallographic microscopy. β =975℃.

[0060] 3. Preliminary heat treatment and deformation: The ingot is placed in a T... β The material undergoes a high-temperature homogenization treatment at +150℃ for 24 hours. This is followed by multi-stage forging: the initial forging temperature is T... β +150℃, the forging temperature in the single-phase region is T. β +120℃, the forging temperature of the two-phase region is T β -80℃, finished product forging temperature is T β-100℃; the deformation amount of each forging sequence is controlled at about 60%, and finally a forged square billet is obtained.

[0061] 4. Hot rolling deformation (S2): In T β The first rolling process was carried out at -120℃ (approximately 855℃), with a rolling deformation of 70%–80%; subsequently, it was subjected to T... β The second rolling process is carried out at -150℃ (approximately 825℃); the cumulative deformation during rolling is 90%; after each rolling pass, grinding is performed; and after the last rolling pass, the outer layer is peeled off to obtain the alloy billet.

[0062] 5. Solution treatment (S3): Perform solution treatment at 760℃ and hold for 40 minutes, then quench in water to room temperature.

[0063] 6. Performance results: The room temperature tensile test showed that the alloy had a yield strength of 948 MPa, a tensile strength of 1120 MPa, a work hardening amount of 172 MPa, and an elongation of 18.5%.

[0064] Example 8 1. Composition and Design: By weight percentage, the composition is: Al: 6.0%, V: 3.5%, Mn: 2.5%, Cr: 2.0%, with the balance being Ti and unavoidable impurities. The calculated molybdenum equivalent [Mo] of this composition is... eq =0.67×3.5(V)+1.54×2.5(Mn)+1.6×2.0(Cr)=2.345+3.85+3.2=9.395, which falls within the range of 5.0~10.0.

[0065] 2. Melting and Ingot Treatment (S1): Sponge titanium, Al briquettes, AlV master alloys, TiMn master alloys, and TiCr master alloys are used as raw materials, mixed in the above proportions, and pressed into electrodes. The electrodes are then melted three times in a vacuum arc remelting furnace to obtain ingots. The ingots are then peeled, ultrasonically tested, and the risers are removed. The β-transformation temperature Ta of the alloy is determined using metallographic microscopy. β =985℃.

[0066] 3. Preliminary heat treatment and deformation: The ingot is placed in a T... β The material undergoes a high-temperature homogenization treatment at +150℃ for 24 hours. This is followed by multi-stage forging: the initial forging temperature is T... β +150℃, the forging temperature in the single-phase region is T. β +120℃, the forging temperature of the two-phase region is T β -80℃, finished product forging temperature is T β -100℃; the deformation amount of each forging sequence is controlled at about 60%, and finally a forged square billet is obtained.

[0067] 4. Hot rolling deformation (S2): In T β The first rolling process was carried out at -120℃ (approximately 865℃), with a rolling deformation of 70%–80%; subsequently, it was subjected to T... β The second rolling process is carried out at -150℃ (approximately 835℃); the cumulative deformation during rolling is 88%. After each rolling pass, the material is ground and then peeled off after the last rolling pass to obtain the alloy billet.

[0068] 5. Solution treatment (S3): Perform solution treatment at 770℃ and hold for 50 minutes, then quench in water to room temperature.

[0069] 6. Performance results: The room temperature tensile test showed that the alloy had a yield strength of 955 MPa, a tensile strength of 1135 MPa, a work hardening amount of 180 MPa, and an elongation of 17.8%.

[0070] Example 9 1. Composition and Design: By weight percentage, the composition is: Al: 4.5%, V: 4.5%, Ni: 2.0%, Cu: 2.5%, with the balance being Ti and unavoidable impurities. The calculated molybdenum equivalent [Mo] of this composition is... eq =0.67×4.5(V)+1.11×2.0(Ni)+0.77×2.5(Cu)=3.015+2.22+1.925=7.16, which falls within the range of 5.0~10.0.

[0071] 2. Melting and Ingot Processing (S1): Sponge titanium, Al briquettes, AlV master alloys, TiNi master alloys, and TiCu master alloys are used as raw materials, mixed in the above proportions, and pressed into electrodes. The electrodes are then melted three times in a vacuum arc remelting furnace to obtain ingots. The ingots are then peeled, ultrasonically tested, and the risers are removed. The β-transformation temperature Ta of the alloy is determined using metallographic microscopy. β =970℃.

[0072] 3. Preliminary heat treatment and deformation: The ingot is placed in a T... β The material undergoes a high-temperature homogenization treatment at +150℃ for 24 hours. This is followed by multi-stage forging: the initial forging temperature is T... β +150℃, the forging temperature in the single-phase region is T. β +120℃, the forging temperature of the two-phase region is T β -80℃, finished product forging temperature is T β -100℃; the deformation amount of each forging sequence is controlled at about 60%, and finally a forged square billet is obtained.

[0073] 4. Hot rolling deformation (S2): In T βThe first rolling process is carried out at -120℃ (approximately 850℃), with a rolling deformation of 70%–80%; subsequently, it is carried out at T... β The second rolling process is carried out at -150℃ (approximately 820℃); the cumulative deformation during rolling is 85%. After each rolling pass, the material is ground and then peeled off after the last rolling pass to obtain the alloy billet.

[0074] 5. Solution treatment (S3): Perform solution treatment at 750℃ and hold for 45 minutes, then quench in water to room temperature.

[0075] 6. Performance results: The room temperature tensile test showed that the alloy had a yield strength of 940 MPa, a tensile strength of 1110 MPa, a work hardening amount of 170 MPa, and an elongation of 19.0%.

[0076] Comparative Example 1 1. Composition and Design: The composition is the same as in Example 1: Al: 6.0%, V: 4.0%, Cu: 5.5%, with the balance being Ti and unavoidable impurities. [Mo] eq =6.915.

[0077] 2. Process deviation: Hot rolling is carried out at 800℃ with a cumulative deformation of 60%; solution treatment is carried out at 880℃ for 60 minutes.

[0078] 3. Performance results: Yield strength is 948MPa, tensile strength is 1068MPa, work hardening amount is 120MPa (not reaching 150MPa), and elongation is 19.0%.

[0079] Comparative Example 2 1. Composition and Design: Composition: Al: 5.0%, V: 3.0%, Zr: 5.0% (using non-eutectoid β-stabilizing elements), balance Ti and unavoidable impurities.

[0080] 2. Process deviation: Hot rolling is carried out at 950℃, with a cumulative deformation of 97%, and the solution treatment step is completely omitted.

[0081] 3. Performance results: Yield strength is 925MPa, tensile strength is 1057MPa, work hardening amount is 132MPa (not reaching 150MPa), and elongation is 21.0%.

[0082] Comparative Example 3 1. Composition and Design: Composition: Al: 5.5%, V: 4.5%, Nb: 3.5% (using non-eutectoid β-stabilized elements), balance Ti and unavoidable impurities.

[0083] 2. Process deviation: Solution treatment was performed at 900℃ for 30 minutes.

[0084] 3. Performance results: Yield strength is 955MPa, tensile strength is 1055MPa, work hardening amount is 100MPa (far lower than 150MPa), and elongation is 19.5%.

[0085] Comparative Example 4 1. Composition and Design: Composition: Al: 6.0%, V: 3.5%, Mo: 2.0% (using non-eutectoid β-stabilizing elements), balance Ti and unavoidable impurities.

[0086] 2. Process deviation: Solution treatment was performed at 860℃ for 45 minutes.

[0087] 3. Performance results: Yield strength is 939 MPa, tensile strength is 1074 MPa, work hardening amount is 135 MPa (not reaching 150 MPa), and elongation is 18.5%.

[0088] Performance Testing and Results Summary The above materials were subjected to room temperature tensile tests using a Zwick Z150 tensile testing machine at a tensile rate of 0.3 mm / min. The performance results are summarized in Table 1 below: Table 1: Comparison of room temperature tensile mechanical properties between the examples and comparative examples Results Analysis All embodiments achieved the invention objective of yield strength greater than 900 MPa, work hardening amount stably exceeding 150 MPa, and elongation not less than 15%.

[0089] Comparative Example 1 demonstrates that the process parameters of hot rolling and solution treatment are crucial for the formation of a multi-scale lamellar α-phase heterostructure, which is the structural basis for achieving high work hardening capacity. Deviations in these parameters resulted in the incomplete formation of this structure, leading to a severely insufficient work hardening capacity (120 MPa).

[0090] Comparative Example 2 demonstrates that using a non-eutectoid β-stabilizing element (Zr) and omitting solution treatment fails to induce the precipitation of nanoscale eutectoid compounds during subsequent heat treatment. The lack of this precipitation strengthening and interfacial strengthening effect is the direct reason why a high work hardening amount (132 MPa) cannot be achieved.

[0091] Comparative Examples 3 and 4 together demonstrate that even if the composition contains β-stabilizing elements and a solid solution treatment is performed, the nanoscale eutectoid phase on which the present invention depends cannot be effectively precipitated under the stated process if non-eutectoid β-stabilizing elements (Nb, Mo) are used, resulting in work hardening capacity (100 MPa, 135 MPa) that is far lower than that of the present invention.

[0092] Matters not covered in this invention are common knowledge.

[0093] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A titanium alloy based on lamellar α-phase and nano-phase precipitation, characterized in that, The chemical composition of titanium alloys, by weight percentage, is: Al: 2.0%-7.5%; V: 1.0%-6.0%; x: 1%-8%, where x is one eutectoid β-stabilizing element selected from Fe, Mn, Cr, Ni, and Cu, and when x is two or more elements, 1%-8% represents the total content of these elements; the balance is Ti and unavoidable impurities; the molybdenum equivalent [Mo] of the β phase of the titanium alloy. eq The value should be controlled within the range of 5.0 to 10.0, where [Mo] eq = 0.67V+1.6Cr+2.5Fe+1.54Mn+1.11Ni+0.77Cu.

2. A method for preparing a titanium alloy based on lamellar α-phase and nano-phase precipitation as described in claim 1, characterized in that, Includes the following sequential steps: S1. Melting and Ingot Processing: The ingot is obtained by three melting processes in a vacuum arc furnace. The ingot is then peeled and subjected to ultrasonic testing. The ingot riser is removed. S2. Hot rolling deformation: The ingot processed in step S1 is hot rolled in the α+β two-phase region at a hot rolling temperature of 810℃~950℃ and a cumulative deformation of 75%~95% to obtain an alloy billet. S3. Solution treatment: The alloy billet obtained in step S2 is subjected to solution treatment. The holding temperature range is 700℃~850℃ and the holding time range is 30min~120min. Then, it is rapidly cooled to room temperature at a cooling rate of 50℃ / s~250℃ / s.

3. The method for titanium alloys based on lamellar α-phase and nano-phase precipitation as described in claim 2, characterized in that, In step S1, after obtaining the ingot, the β transformation temperature T of the titanium alloy is measured. β .

4. The method for titanium alloys based on the precipitation of lamellar α-phase and nano-phase according to claim 3, characterized in that, After step S1 and before step S2, the ingot is subjected to a homogenization heat treatment at a temperature of T. β + (100-200)℃, heat preservation time is 12h~48h.

5. The method for titanium alloys based on the precipitation of lamellar α-phase and nano-phase according to claim 4, characterized in that, After homogenization heat treatment and before step S2, the ingot is subjected to multi-stage forging to obtain a forged square billet; the hot rolling in step S2 is performed on the forged square billet.

6. The method for titanium alloys based on the precipitation of lamellar α-phase and nano-phase according to claim 5, characterized in that, The multi-stage forging process includes: a billet forging temperature of T. β +(100-200)℃, the forging temperature in the single-phase region is T β +(100-150)℃, the forging temperature of the two-phase region is T β -80℃, finished product forging temperature is T β -100℃; after each forging pass, grinding is performed, and the deformation of each forging sequence is controlled within the range of 50% to 75%.

7. The method for titanium alloys based on the precipitation of lamellar α-phase and nano-phase according to claim 2, characterized in that, The hot rolling mentioned in step S2 specifically refers to: in T β The first rolling process is carried out at -120℃, with a rolling deformation of 70% to 80%; subsequently, it is carried out at T... β The second rolling process is carried out at -150℃; the cumulative deformation during rolling is 75%~95%, and grinding is performed after each rolling pass. The last rolling pass is followed by peeling.

8. The method for titanium alloys based on the precipitation of lamellar α-phase and nano-phase according to claim 2, characterized in that, After step S3, a solution treatment is performed at a temperature of 700℃~850℃ for 30min~120min, followed by rapid cooling to room temperature.

9. The method for titanium alloys based on the precipitation of lamellar α-phase and nano-phase according to claim 2, characterized in that, In step S1, when preparing the ingot, sponge titanium, Al bean, AlV master alloy, TiCu master alloy and sponge zirconium are used as raw materials. They are weighed and batched according to the chemical composition ratio of the alloy design. After mixing, they are pressed into electrodes for vacuum consumable arc melting.

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