Mo-containing high-strength and high-plasticity Ti-6Al-4V alloy and preparation method thereof

Abstract

The invention belongs to the field of titanium alloy material preparation and processing, and particularly relates to a Mo-containing high-strength and high-plasticity Ti-6Al-4V alloy and a preparation method thereof, and the Mo-containing high-strength and high-plasticity Ti-6Al-4V alloy comprises the following chemical components in percentage by weight: 1.0-3.5% of Mo, 5.50-6.75% of Al, 3.5-4.5% of V, less than or equal to 0.3% of Fe, less than or equal to 0.2% of O, and the balance of Ti and inevitable impurities. According to the technical scheme disclosed by the invention, the Ti-6Al-4V alloy with high strength and high plasticity is obtained by adding the alloy element Mo and adopting a hot rolling annealing process. The process is simple, convenient to operate and easy to popularize and apply in actual production; according to the Mo-containing high-strength and high-plasticity Ti-6Al-V alloy, alpha-phase and beta transformation structures are obtained through annealing treatment, the structures are uniform, the yield strength of the prepared Mo-containing high-strength and high-plasticity Ti-6Al-V alloy is larger than or equal to 997.5 MPa, the tensile strength is larger than or equal to 1092.4 MPa, and the ductility is larger than or

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy material preparation and processing technology, specifically relating to a high-strength and high-plasticity Ti-6Al-4V alloy containing Mo and its preparation method. Background Technology

[0002] Titanium and titanium alloys, due to their excellent comprehensive properties such as high strength, low density, and good corrosion resistance, have been widely used in aerospace, medical and chemical industries, military defense, and marine engineering. With the development of science and technology, titanium alloys have become the preferred material in many fields, leading to increasing demand and more stringent requirements in engineering design. Developing titanium alloy materials with even better comprehensive properties has become an important direction for titanium alloy research and development.

[0003] Titanium-aluminum-vanadium alloys are currently the most widely used type of titanium alloy, with Ti-6Al-4V (TC4) being a typical grade. Conventional Ti-6Al-4V has a room temperature tensile strength of approximately 900-1000 MPa and an elongation of approximately 10-12%. Some demanding applications, such as aerospace structural components, require titanium alloys to withstand higher loads, demanding both high strength and good ductility. The overall performance of conventional Ti-6Al-4V needs further improvement to adapt to more stringent applications. Developing high-strength, high-ductility Ti-6Al-4V alloys to meet the demands of various fields for high-performance titanium alloys and continuously expand the application range of titanium alloys is of great significance.

[0004] CN106399886A discloses a TC4 fine-grained titanium alloy thin plate and its preparation method. The TC4 alloy has a good elongation after fracture of 15~19% and a tensile strength of 1020~1050MPa. However, its hot working process is complicated, involving slab cladding treatment, stacking and rolling, etc., resulting in general production efficiency and high production cost.

[0005] CN117403100A discloses a high-performance, short-process TC4 titanium alloy thin strip and its preparation method. This method involves online warm rolling under hydraulic tension, resulting in TC4 titanium alloy thin strips with tensile strengths of 1241 MPa to 1406 MPa and total elongation of 5.0% to 9.2%. While exhibiting high strength, the elongation is relatively low, and the rolling process is complex. This invention aims to provide a Mo-containing high-strength, high-ductility Ti-6Al-4V alloy that, while maintaining a simple and easy hot-working process, achieves a 10-15% increase in room temperature tensile strength and a 10% increase in elongation, solving the problem of the difficulty in achieving both high strength and high ductility in traditional Ti-6Al-4V alloys. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a high-strength and high-plasticity Ti-6Al-4V alloy containing Mo and its preparation method. By adding alloying elements and hot rolling annealing process, the Ti-6Al-4V alloy can achieve both high strength and high plasticity. The process is simple and easy to operate.

[0007] According to one aspect of the present invention, a high-strength and high-plasticity Ti-6Al-4V alloy containing Mo is provided, comprising the following chemical composition by weight percentage: Mo 1.0%~3.5%, Al 5.50%~6.75%, V 3.5%~4.5%, Fe≤0.3%, O≤0.2%, with the remainder being Ti and unavoidable impurities.

[0008] The rationale for the alloy design of this invention is as follows:

[0009] Mo: A strong β-stabilizing element, it forms strong lattice distortion in the β phase, greatly increasing the strength of the β phase. It is also effectively dissolved in the α phase, thus playing a strengthening role.

[0010] Al: A strong α-stabilizing element, it strengthens titanium alloys by forming substituted solid solutions. Appropriate amounts of Al can improve the room temperature and high temperature strength properties of titanium alloys. At low Al content, the α-phase stability is insufficient, leading to decreased room temperature strength. At high Al content, brittle Ti3Al phases easily precipitate, causing alloy embrittlement.

[0011] V: A weakly β-stabilizing element, it can be infinitely dissolved in the β-phase region, strengthening the β-phase while retaining its toughness. It can effectively suppress the precipitation of the brittle Ti3Al phase caused by Al. When the V content is low, the β-phase is insufficient, resulting in poor hot workability. When the V content is high, the room temperature strength decreases, and the microstructure is prone to segregation.

[0012] Fe: Usually a residual impurity element, and its content is required to be no higher than 0.3 wt%.

[0013] O: Interstitial element, a key indicator for quality control of titanium alloys, with a required content not exceeding 0.2wt%.

[0014] Based on the above technical solution, the microstructure of the Ti-6Al-4V alloy is composed of α phase and β transformation structure and the structure is relatively uniform. The α phase accounts for 22.7%~35.2% and the β transformation structure accounts for 64.8%~77.3%, based on a total surface area ratio of 100%.

[0015] Based on the above technical solution, the Ti-6Al-4V alloy has a yield strength ≥997.5MPa, a tensile strength ≥1092.4MPa, and an elongation ≥13.3%.

[0016] According to another aspect of the present invention, a method for preparing a Mo-containing high-strength and high-plasticity Ti-6Al-4V alloy is also provided, comprising the following steps: vacuum melting - hot rolling - annealing; Vacuum melting: vacuum degree is 0.05~0.10MPa, melting arc current is 400~450A, melting time is 4~6min, ingot melting is 3~5 times / ingot, and square ingots are obtained by copper mold suction casting; Hot rolling: The heating temperature is 930~980℃, the holding time is 0.5~2.0h, and the alloy is rolled immediately after being taken out of the furnace after reaching the temperature to obtain the hot-rolled alloy; Annealing: The hot-rolled alloy is annealed at a temperature of 780~830℃ for 20~60min and then cooled to room temperature by natural cooling to obtain Ti-6Al-4V alloy.

[0017] Based on the above technical solution, the composition of the alloy raw material is as follows: sponge titanium, vanadium-aluminum alloy, titanium-molybdenum alloy, and aluminum briquettes.

[0018] Based on the above technical solution, the vacuum melting specifically involves: loading the alloy raw material into a vacuum non-consumable arc furnace, and evacuating the furnace to a vacuum degree of 1.0 × 10⁻⁶. -3 After Pa, the vacuum gauge is turned off and argon gas is introduced until the vacuum level inside the furnace is 0.05 MPa, and then the melting process begins.

[0019] Based on the above technical solution, the hot rolling specifically involves: loading the obtained square ingot into an electric resistance furnace for heating, and the alloy deformation after hot rolling is 80%~90%.

[0020] Beneficial effects This invention obtains a high-strength and high-ductility Ti-6Al-4V alloy by adding alloying elements and hot rolling annealing. The process is simple and easy to operate, and can be readily promoted and applied in actual production. Annealing treatment yields α-phase and β-transformation microstructures with uniform structure. The prepared Mo-containing high-strength and high-ductility Ti-6Al-4V alloy has a yield strength ≥997.5 MPa, tensile strength ≥1092.4 MPa, and elongation ≥13.3%. A Ti-6Al-4V alloy with good overall performance can achieve a yield strength of 1107.6 MPa, a tensile strength of 1182.4 MPa, and an elongation of 15.3%. Compared to the standard Ti-6Al-4V alloy, the Mo-containing Ti-6Al-4V alloy can achieve a 10%~15% increase in room temperature tensile strength and a 10% increase in elongation, which can expand the application scenarios of Ti-6Al-4V alloy to a certain extent. Attached Figure Description

[0021] Figure 1 This is a SEM image of the Ti-6Al-4V alloy prepared in Example 2 of this invention; Figure 2 This is a graph showing the relationship between standard load and nominal strain of the alloys described in Examples 1-3 and the comparative examples of the present invention. Detailed Implementation

[0022] To make the objectives and technical solutions of this invention clearer, the following embodiments are provided for further explanation. However, the scope of protection of this invention is not limited to these embodiments; the embodiments are merely for illustrative purposes. Those skilled in the art should understand that any changes or equivalent substitutions that do not depart from the concept of this invention are included within the scope of protection of this invention.

[0023] Unless otherwise specified, all reagents and raw materials used in this invention are obtained through purchase.

[0024] The present invention provides a high-strength and high-plasticity Ti-6Al-4V alloy containing Mo in the specific embodiments section, which includes the following chemical composition by weight percentage: Mo 1.0%~3.5%, Al 5.50%~6.75%, V 3.5%~4.5%, Fe≤0.3%, O≤0.2%, and the remainder being Ti and unavoidable impurities; The microstructure of the Ti-6Al-4V alloy consists of α phase and β transformation structure and the structure is relatively uniform. The α phase accounts for 22.7%~35.2% and the β transformation structure accounts for 64.8%~77.3%, based on a total area ratio of 100%.

[0025] Based on the above technical solution, the Ti-6Al-4V alloy has a yield strength ≥997.5MPa, a tensile strength ≥1092.4MPa, and an elongation ≥13.3%.

[0026] The present invention also provides a method for preparing a Mo-containing high-strength and high-plasticity Ti-6Al-4V alloy in the specific embodiments section, comprising the following steps: vacuum melting - hot rolling - annealing; Vacuum melting: The alloy raw materials are loaded into a vacuum non-consumable arc furnace. During the melting process, the furnace is evacuated and filled with argon gas. The vacuum degree is 0.05~0.10MPa, the melting arc current is 400~450A, the melting time is 4~6min, and the ingot is melted 3~5 times / ingot. Square ingots are obtained by copper mold suction casting. Hot rolling: The obtained square ingot is placed into an electric resistance furnace and heated to a temperature of 930~980℃ for 0.5~2.0h. After reaching the desired temperature, it is immediately rolled after being removed from the furnace, with a hot rolling deformation of 80%~90%. Annealing: The annealing temperature is 780~830℃, the holding time is 20~60min, and the temperature is cooled to room temperature by natural cooling to obtain Ti-6Al-4V alloy.

[0027] Based on the above technical solution, the alloy raw materials include sponge titanium, vanadium-aluminum alloy, titanium-molybdenum alloy, and aluminum briquettes. Specifically, the sponge titanium is grade 0 sponge titanium (Ti≥99.7wt%), the vanadium-aluminum alloy is Al-55V, the titanium-molybdenum alloy is Ti-15Mo, and the aluminum briquettes are high-purity aluminum briquettes (Al≥99.9wt%).

[0028] Examples and Comparative Examples The chemical composition and content of the Ti-6Al-4V alloys in Examples 1-3 and the comparative examples of this invention are shown in Table 1. Vacuum melting parameters are shown in Table 2, and hot rolling and annealing parameters are shown in Table 3. The mechanical properties of the Ti-6Al-4V alloys are shown in Table 4. Specifically, the yield strength of Example 2 is 16.4% higher than that of the comparative example, the tensile strength is 12.2% higher, and the elongation is 22.4% higher. The SEM image of the Ti-6Al-4V alloy prepared in Example 2 is shown in Table 4. Figure 1 The α phase accounts for 29.1%, and the β transformation structure accounts for 70.9%; the relationship between standard strain and standard strain in Examples 1-3 and the comparative example is shown in the figure. Figure 2 .

[0029] Table 1 shows the chemical composition (wt%) of the examples and comparative examples.

[0030] Table 2 shows the smelting process parameters for the examples and comparative examples.

[0031] Table 3 shows the rolling and annealing process parameters for the examples and comparative examples.

[0032] Table 4 shows the room temperature mechanical properties of the examples and comparative examples.

[0033] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A high-strength, high-ductility Ti-6Al-4V alloy containing Mo, characterized in that, Based on a weight percentage of 100%, it includes the following chemical composition: Mo 1.0%~3.5%, Al 5.50%~6.75%, V 3.5%~4.5%, Fe≤0.3%, O≤0.2%, with the remainder being Ti and unavoidable impurities.

2. The Mo-containing high-strength, high-plasticity Ti-6Al-4V alloy according to claim 1, characterized in that, The microstructure of the Ti-6Al-4V alloy consists of α phase and β transformation structure and the structure is relatively uniform. The α phase accounts for 22.7%~35.2% and the β transformation structure accounts for 64.8%~77.3%, based on a total area ratio of 100%.

3. The Mo-containing high-strength, high-plasticity Ti-6Al-4V alloy according to claim 1, characterized in that, The Ti-6Al-4V alloy has a yield strength ≥997.5MPa, a tensile strength ≥1092.4MPa, and an elongation ≥13.3%.

4. The method for preparing the Mo-containing high-strength and high-ductility Ti-6Al-4V alloy according to any one of claims 1 to 3, characterized in that, The process includes the following steps: vacuum melting, hot rolling, and annealing. Vacuum melting: vacuum degree is 0.05~0.10MPa, melting arc current is 400~450A, melting time is 4~6min, ingot melting is 3~5 times / ingot, and square ingots are obtained by copper mold suction casting; Hot rolling: The heating temperature is 930~980℃, the holding time is 0.5~2.0h, and the alloy is rolled immediately after being taken out of the furnace after reaching the temperature to obtain the hot-rolled alloy; Annealing: The hot-rolled alloy is annealed at a temperature of 780~830℃ for 20~60min and then cooled to room temperature by natural cooling to obtain Ti-6Al-4V alloy.

5. The preparation method according to claim 4, characterized in that, The composition of the alloy raw material is as follows: by weight percentage (100%), Mo 1.0%~3.5%, Al 5.50%~6.75%, V 3.5%~4.5%, Fe≤0.3%, O≤0.2%, and the remainder is Ti or unavoidable impurities.

6. The preparation method according to claim 4, characterized in that, The vacuum melting process specifically involves: loading the alloy raw material into a vacuum non-consumable arc furnace, and evacuating the furnace to a vacuum level of 1.0 × 10⁻⁶. -3 After Pa, the vacuum gauge is turned off and argon gas is introduced until the vacuum level inside the furnace is 0.05 MPa, and then the melting process begins.

7. The preparation method according to claim 4, characterized in that, The hot rolling process specifically involves placing the obtained square ingot into an electric resistance furnace for heating, and the alloy deformation after hot rolling is 80%~90%.

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