Rolling-state tough titanium alloy and preparation method thereof

Abstract

The invention belongs to the technical field of alloys, and particularly relates to a rolled-state tough titanium alloy and a preparation method thereof.The rolled-state tough titanium alloy is obtained by smelting sponge titanium, aluminum particles and a titanium-molybdenum intermediate alloy, then heating the smelted sponge titanium, aluminum particles and the titanium-molybdenum intermediate alloy and then adopting a hot rolling mode. The rolled-state tough titanium alloy obtained through the method is fine in grain and uniform in structure, all components are evenly distributed, the technical defects of as-cast-state Ti-6Al-xMo alloy are overcome, and the mechanical property is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of alloys, in particular to a rolled strong-tough titanium alloy and a preparation method thereof. Background Art

[0002] As a new type of structural material, titanium alloy has high strength, low density and high temperature resistance, and has become an ideal material in the field of aerospace. With the development of society, titanium alloy has stood out due to its excellent corrosion resistance and good biocompatibility, and has been widely used in navigation, petrochemical, weapons and equipment, and biomedicine. Ti-Al-X ternary alloy has good welding performance and plastic deformation ability, and can maintain moderate yield strength. As an α+β type titanium alloy, Ti-6Al-4V alloy is used in many fields, and its usage accounts for more than half of the total titanium alloy. Ti-6Al-4V alloy has good mechanical properties and biocompatibility, and is used in the medical field instead of pure titanium as a human implant material. However, the V element in Ti-6Al-4V alloy will be slowly released during long-term service in the human body, and produce cytotoxic effects, causing potential harm to human health.

[0003] Mo, V, Nb and Ta are all isomorphous β-phase stabilizing elements, and the ability of Mo element to stabilize β-phase is slightly stronger than that of V element. The difference in atomic radius between Mo and Ti is large, resulting in greater lattice distortion, and its strengthening effect is better than that of other β-phase stabilizing elements. In addition, Mo element is a non-toxic element, and the cost of Mo element is much lower than that of V element. Therefore, the prior art discloses a series of cast Ti-6Al-xMo alloys with different Mo element contents prepared by using Ti-6Al as the matrix and a non-consumable vacuum arc melting furnace, wherein x is the mass percentage, and x is 0, 4, 8, 12, 16, and 20, respectively, which are specifically disclosed in "Microstructure and Mechanical Properties of Cast Ti-6Al-xMo Alloy".

[0004] Although the prior art discloses a method for preparing a cast Ti-6Al-xMo alloy, the cast Ti-6Al-xMo alloy obtained by a non-consumable vacuum arc melting furnace has defects such as coarse grains, uneven structure, and component segregation, resulting in poor plasticity and low strength of the obtained cast Ti-6Al-xMo alloy, that is, poor mechanical properties. Summary of the invention

[0005] In view of the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a rolled strong and tough titanium alloy and a preparation method thereof. The present invention obtains a rolled strong and tough titanium alloy by melting titanium sponge, aluminum particles and titanium-molybdenum master alloy, then heating, and then hot rolling. The rolled strong and tough titanium alloy obtained by the method of the present invention has fine grains, uniform structure and uniform distribution of various components, which overcomes the technical defects of the cast Ti-6Al-xMo alloy and effectively improves the mechanical properties.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A method for preparing a rolled tough titanium alloy comprises the following steps:

[0008] The titanium sponge, aluminum particles and titanium-molybdenum master alloy are mixed and smelted to obtain an alloy ingot, which is a cast Ti-6Al-xMo alloy.

[0009] The alloy ingot is heated to allow the alloy ingot to be fully heated through, so as to facilitate reaching a suitable softening and plasticizing state during the hot rolling process, and facilitate subsequent rolling deformation to obtain an intermediate.

[0010] The intermediate is subjected to 30 to 35 rolling deformation passes, and annealed for 3 to 5 minutes at the rolling temperature corresponding to the rolling deformation between each pass. The purpose of each annealing pass is to eliminate the residual stress in the alloy ingot and prevent the alloy ingot from cracking. After the rolling deformation is completed, air cooling treatment is performed, that is, natural cooling in the air to obtain a rolled strong and tough titanium alloy.

[0011] Preferably, the heating condition is: heating at 800°C to 850°C for 20min to 40min.

[0012] Preferably, the rolling temperature is 800°C to 850°C.

[0013] Preferably, the reduction amount of each rolling deformation is 0.2 mm to 0.4 mm.

[0014] Preferably, after the rolling deformation is completed, the final deformation is 70% to 80%; if the deformation is too small, the coarse cast structure cannot be fully broken, and dynamic recrystallization cannot occur to refine the grains; if the deformation is too large, more cracks will appear in the rolled tough titanium alloy, which will seriously affect the mechanical properties; the deformation of 80% has the best mechanical properties.

[0015] Preferably, in the alloy ingot, the mass percentage of aluminum is 6wt%, the mass percentage of molybdenum is 4wt% to 20wt%, the balance is titanium, and the sum of the mass percentages of titanium, aluminum and molybdenum is 100%.

[0016] Preferably, the purity of the titanium sponge, aluminum particles and the titanium-molybdenum master alloy is ≥99.9%, and the titanium-molybdenum master alloy is selected from Ti-32Mo alloy.

[0017] The invention also protects the rolled strong-tough titanium alloy prepared by the preparation method.

[0018] Preferably, the as-rolled tough titanium alloy consists of fine, equiaxed α phase and β phase.

[0019] Preferably, the tensile strength of the rolled tough titanium alloy is ≥900 MPa, and the elongation is ≥15%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention uses titanium sponge, aluminum particles and titanium-molybdenum master alloy as raw materials, first smelting to obtain cast Ti-6Al-xMo alloy, and then heating and multi-pass rolling, that is, hot rolling to obtain rolled strong and tough titanium alloy. The alloy ingot can be crushed by hot rolling to break the coarse cast structure. Hot rolling also enables the alloy ingot to undergo rolling deformation, plastic deformation and dynamic recrystallization at high temperature at the same time, achieving uniform structure and composition, reducing and eliminating casting defects, and improving mechanical properties.

[0022] Dynamic recrystallization refers to the recrystallization of metals during the process of hot working deformation. In this process, thermal deformation and recrystallization of the metal occur simultaneously. When the metal is subjected to external force, plastic deformation occurs inside the grains, resulting in increased stress inside the grains and increased distortion energy in the grains. When the temperature of the alloy rises to the recrystallization temperature, the distortion energy inside the grains is also released, providing energy for the nucleation and growth of new grains.

[0023] 2. The present invention takes Ti-6Al alloy as the matrix, combines with the traditional alloy design method, and replaces a part of Ti element with Mo element by slight adjustment of the components to obtain alloy ingot, and then performs multiple hot rolling on the alloy ingot until the final deformation of the rolling deformation is 70% to 80%, so as to obtain a rolled strong and tough titanium alloy; the preparation method of the present invention is simple and low in cost, and overcomes the technical defect of poor mechanical properties of the cast Ti-6Al-xMo alloy in the prior art only by means of rolling. The results show that the prepared rolled strong and tough titanium alloy has good comprehensive mechanical properties, with a maximum tensile strength ≥900MPa and an elongation ≥15%.

[0024] 3. The phase structure and microstructure of the cast Ti-6Al-xMo alloy in the prior art are composed of coarse β phase grains and a large amount of α′ martensite phase, and the phase structure and microstructure of the rolled strong and tough titanium alloy are equiaxed α phase and β phase matrix. Compared with the cast Ti-6Al-xMo alloy, the rolled strong and tough titanium alloy changes the structural phase and microstructure morphology, and the hot rolling method is used to break the cast Ti-6Al-xMo alloy structure and refine the grains.

[0025] 4. Compared with the cast Ti-6Al-xMo alloy, the rolled strong and tough titanium alloy can significantly reduce energy consumption and reduce costs. Hot rolling is carried out at a higher temperature, which makes it easier to deform the metal. Due to the high hot rolling temperature, the strength and hardness of the metal decrease, and the required deformation force is greatly reduced, thereby reducing the energy consumption of mechanical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 In the figure, (a) is the XRD diagram of the rolled tough titanium alloy of Examples 1 to 5 and Comparative Example 6; (b) is the XRD diagram of the cast titanium alloy of Comparative Example 1 to 5 and Comparative Example 7.

[0027] Figure 2 In the figure, (a) is the microstructure diagram of the rolled tough titanium alloy of Examples 1 to 5 and Comparative Example 6; (b) is the microstructure diagram of the cast titanium alloy of Comparative Example 1 to 5 and Comparative Example 7.

[0028] Figure 3 In the figure, (a) is a mechanical property diagram of the rolled tough titanium alloy of Examples 1 to 5 and Comparative Example 6; (b) is a mechanical property diagram of the cast titanium alloy of Comparative Example 1 to 5 and Comparative Example 7. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are conventional methods unless otherwise specified.

[0030] The present invention performs hot rolling on the cast Ti-6Al-xMo alloy in the prior art, and controls the deformation amount of each rolling deformation and the final deformation amount, so as to overcome the technical defects of the poor mechanical properties of the cast Ti-6Al-xMo alloy in the prior art. The obtained rolled strong and tough titanium alloy has fine grains, uniform structure, and uniform distribution of various components. The rolled strong and tough titanium alloy is composed of equiaxed α phase + β phase, thereby improving the strength and enhancing the mechanical properties.

[0031] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, comparative examples and accompanying drawings, as shown below:

[0032] Example 1

[0033] The method for preparing a rolled tough titanium alloy comprises the following steps:

[0034] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0035] S2. According to Ti-6Al-4Mo, titanium sponge, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 4wt%, and the balance of Ti is 90wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot.

[0036] S3. The alloy ingot is first heated in a box furnace at a holding temperature of 800°C for 30 min to obtain an intermediate; then the intermediate is subjected to 35 rolling deformations, with a deformation amount of 0.3 mm in each pass, and annealing is performed at a corresponding rolling temperature of 800°C for 5 min between each adjacent pass, that is, each rolling pass is maintained at 800°C for 5 min in a box furnace, and after the rolling deformation is completed, it is cooled to room temperature in an air environment, and the final deformation amount is 80%, thereby obtaining a rolled HR-TAM4 alloy, recorded as HR-TAM4.

[0037] Example 2

[0038] The method for preparing the rolled tough titanium alloy is the same as the preparation steps of Example 1, except that the mass fraction of Mo is replaced from 4% to 8%, and comprises the following steps:

[0039] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0040] S2. According to Ti-6Al-8Mo, titanium sponge, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 8wt%, and the balance of Ti is 86wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot.

[0041] S3. The alloy ingot is first heated in a box furnace at a holding temperature of 800°C for 30 min to obtain an intermediate; then the intermediate is subjected to 35 rolling deformations, with a deformation amount of 0.3 mm in each pass, and annealing is performed at a corresponding rolling temperature of 800°C for 5 min between each adjacent pass, that is, each rolling pass is maintained at 800°C for 5 min in a box furnace, and after the rolling deformation is completed, it is cooled to room temperature in an air environment, and the final deformation amount is 80%, thereby obtaining a rolled HR-TAM8 alloy, recorded as HR-TAM8.

[0042] Example 3

[0043] The method for preparing the rolled tough titanium alloy is the same as the preparation steps of Example 1, except that the mass fraction of Mo is replaced from 4% to 12%, and comprises the following steps:

[0044] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0045] S2. According to Ti-6Al-12Mo, titanium sponge, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 12wt%, and the balance of Ti is 82wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot.

[0046] S3. The alloy ingot is first heated in a box furnace at a holding temperature of 800°C for 30 min to obtain an intermediate; then the intermediate is subjected to 35 rolling deformations, with a deformation amount of 0.3 mm in each pass, and annealing is performed at a corresponding rolling temperature of 800°C for 5 min between each adjacent pass, that is, each rolling pass is maintained at 800°C for 5 min in a box furnace, and after the rolling deformation is completed, it is cooled to room temperature in an air environment, and the final deformation amount is 80%, thereby obtaining a rolled HR-TAM12 alloy, recorded as HR-TAM12.

[0047] Example 4

[0048] The method for preparing the rolled tough titanium alloy is the same as the preparation steps of Example 1, except that the mass fraction of Mo is replaced from 4% to 16%, and comprises the following steps:

[0049] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0050] S2. According to Ti-6Al-16Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 16wt%, and the balance of Ti is 78wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot.

[0051] S3. The alloy ingot is first heated in a box furnace at a holding temperature of 800°C for 30 min to obtain an intermediate; then the intermediate is subjected to 35 rolling deformations, with a deformation amount of 0.3 mm in each pass, and annealing is performed at a corresponding rolling temperature of 800°C for 5 min between each adjacent pass, that is, each rolling pass is maintained at 800°C for 5 min in a box furnace, and after the rolling deformation is completed, it is cooled to room temperature in an air environment, and the final deformation amount is 80%, thereby obtaining a rolled HR-TAM16 alloy, recorded as HR-TAM16.

[0052] Example 5

[0053] The method for preparing the rolled tough titanium alloy is the same as the preparation steps of Example 1, except that the mass fraction of Mo is replaced from 4% to 20%, and comprises the following steps:

[0054] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0055] S2. According to Ti-6Al-16Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 20wt%, and the balance of Ti is 74wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot.

[0056] S3. The alloy ingot is first heated in a box furnace at a holding temperature of 800°C for 30 min to obtain an intermediate; then the intermediate is subjected to 35 rolling deformations, with a deformation amount of 0.3 mm in each pass, and annealing is performed at a corresponding rolling temperature of 800°C for 5 min between each adjacent pass, that is, each rolling pass is maintained at 800°C for 5 min in a box furnace, and after the rolling deformation is completed, it is cooled to room temperature in an air environment, and the final deformation amount is 80%, thereby obtaining a rolled HR-TAM20 alloy, recorded as HR-TAM20.

[0057] Example 6

[0058] The method for preparing a rolled tough titanium alloy comprises the following steps:

[0059] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0060] S2. According to Ti-6Al-16Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 10wt%, and the balance of Ti is 84wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot.

[0061] S3. The alloy ingot is first heated in a box furnace at a holding temperature of 850°C for 20 minutes to obtain an intermediate; the intermediate is subjected to 33 rolling deformations, with a deformation amount of 0.2 mm in each pass, and annealing is performed at a corresponding rolling temperature of 850°C for 3 minutes between each adjacent pass, that is, each rolling pass is maintained at 850°C for 3 minutes in a box furnace, and after the rolling deformation is completed, it is cooled to room temperature in an air environment, and the final deformation amount is 70%, to obtain a rolled strong and tough titanium alloy.

[0062] Example 7

[0063] The method for preparing a rolled tough titanium alloy comprises the following steps:

[0064] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0065] S2. According to Ti-6Al-16Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that Al is 6wt%, Mo is 15wt%, and Ti is the balance 79wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot.

[0066] S3. The alloy ingot is first heated in a box furnace at a holding temperature of 830°C for 40 minutes to obtain an intermediate; then the intermediate is subjected to 30 rolling deformations, with a deformation amount of 0.4 mm in each pass, and annealing is performed at a corresponding rolling temperature of 830°C for 4 minutes between each adjacent pass, that is, each rolling pass is maintained at 830°C for 4 minutes in a box furnace, and after the rolling deformation is completed, it is cooled to room temperature in an air environment, and the final deformation amount is 75%, to obtain a rolled strong and tough titanium alloy.

[0067] Comparative Example 1

[0068] The method for preparing the cast titanium alloy is the same as the preparation steps of Example 1, except that the hot rolling process in step S3 is not performed to obtain TAM4, and includes the following steps:

[0069] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0070] S2. According to Ti-6Al-4Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 4wt%, and the balance of Ti is 90wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot. The alloy ingot is naturally cooled to room temperature to obtain a cast TAM4 alloy, recorded as TAM4.

[0071] Comparative Example 2

[0072] The method for preparing the cast titanium alloy is the same as the preparation steps of Example 2, except that the hot rolling process in step S3 is not performed to obtain TAM8, and includes the following steps:

[0073] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0074] S2. According to Ti-6Al-8Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 8wt%, and the balance of Ti is 86wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon gas is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process with a stirring current of 5A and a time of 1min to obtain an alloy ingot. The alloy ingot is naturally cooled to room temperature to obtain a cast TAM8 alloy, recorded as TAM8.

[0075] Comparative Example 3

[0076] The method for preparing the cast titanium alloy is the same as the preparation steps of Example 3, except that the hot rolling process in step S3 is not performed to obtain TAM12, and includes the following steps:

[0077] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0078] S2. According to Ti-6Al-12Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 12wt%, and the balance of Ti is 82wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon gas is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot. The alloy ingot is naturally cooled to room temperature to obtain a cast TAM12 alloy, recorded as TAM12.

[0079] Comparative Example 4

[0080] The method for preparing the cast titanium alloy is the same as the preparation steps of Example 4, except that the hot rolling process in step S3 is not performed to obtain TAM16, and includes the following steps:

[0081] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0082] S2. According to Ti-6Al-16Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 16wt%, and the balance of Ti is 78wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon gas is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process with a stirring current of 5A and a time of 1min to obtain an alloy ingot. The alloy ingot is naturally cooled to room temperature to obtain a cast TAM16 alloy, recorded as TAM16.

[0083] Comparative Example 5

[0084] The method for preparing the cast titanium alloy is the same as the preparation steps of Example 5, except that the hot rolling process in step S3 is not performed to obtain TAM20, and includes the following steps:

[0085] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0086] S2. According to Ti-6Al-16Mo, sponge titanium, aluminum particles and titanium-molybdenum intermediate alloy Ti-32Mo are weighed so that the mass percentage of Al is 6wt%, the mass percentage of Mo is 20wt%, and the balance of Ti is 74wt%. Then the three are mixed and smelted in a non-consumable vacuum arc melting furnace. Argon gas is introduced during the smelting process to prevent oxidation. The smelting is repeated 6 times, and electromagnetic stirring is used during the smelting process. The stirring current is 5A and the time is 1min to obtain an alloy ingot. The alloy ingot is naturally cooled to room temperature to obtain a cast TAM20 alloy, recorded as TAM20.

[0087] Comparative Example 6

[0088] The method for preparing the rolled tough titanium alloy is the same as the preparation steps of Example 1, except that the mass fraction of Mo is replaced from 4% to 0, that is, no Mo is added, to obtain HR-TAM0, comprising the following steps:

[0089] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0090] S2. Weigh titanium sponge and aluminum particles according to Ti-6Al so that the mass percentage of Al is 6wt%, the mass percentage of Ti is the remainder 94wt%, and then mix the two, and use a non-consumable vacuum arc melting furnace to melt them. During the melting process, argon gas is introduced to prevent oxidation. The melting is repeated 6 times, and electromagnetic stirring is used during the melting process. The stirring current is 5A and the time is 1 min to obtain an alloy ingot.

[0091] S3. The alloy ingot is first heated in a box furnace at a holding temperature of 800°C for 30 min to obtain an intermediate; then the intermediate is subjected to 35 rolling deformations, with a deformation amount of 0.3 mm for each pass, and annealing is performed at a corresponding rolling temperature of 800°C for 5 min between each pass, that is, each rolling pass is maintained at 800°C for 5 min in a box furnace, and after the rolling deformation is completed, it is cooled to room temperature in an air environment, and the final deformation amount is 80%, thereby obtaining a rolled HR-TAM0 alloy, recorded as HR-TAM0.

[0092] Comparative Example 7

[0093] The method for preparing the cast titanium alloy is the same as the preparation steps of Comparative Example 6, except that the hot rolling process in step S3 is not performed to obtain TAM0, and includes the following steps:

[0094] S1. Perform pickling treatment and ultrasonic cleaning treatment on titanium sponge with a purity of ≥99.9%, aluminum particles with a purity of ≥99.9%, and titanium-molybdenum intermediate alloy Ti-32Mo with a purity of ≥99.9% to obtain treated raw materials.

[0095] S2. Weigh sponge titanium and aluminum particles according to Ti-6Al so that the mass percentage of Al is 6wt%, the mass percentage of Ti is the remainder 94wt%, and then mix the two, and use a non-consumable vacuum arc melting furnace to melt them. During the melting process, argon gas is introduced to prevent oxidation. The melting is repeated 6 times, and electromagnetic stirring is used during the melting process. The stirring current is 5A and the time is 1min. An alloy ingot is obtained. The alloy ingot is naturally cooled to room temperature to obtain a cast TAM0 alloy, recorded as TAM0.

[0096] Embodiments 1 to 7 of the present invention all produce rolled strong and tough titanium alloys with high plasticity, toughness and strength. The rolled strong and tough titanium alloys of Embodiments 1 to 5 and Comparative Example 6 are taken as examples, and compared with the cast titanium alloys of Comparative Examples 1 to 5 and Comparative Example 7. The specific research methods and results are as follows:

[0097] Figure 1The results show that the as-cast TAM4 alloy, the as-cast TAM8 alloy and the as-cast TAM12 alloy are all composed of α′ phase + β phase and α″ phase + β phase, and the rolled HR-TAM4 alloy, the rolled HR-TAM8 alloy and the rolled HR-TAM12 alloy obtained after rolling are all α phase + β phase. The as-cast TAM16 alloy and the as-cast TAM20 alloy are β single-phase structures, and the rolled HR-TAM16 alloy and the rolled HR-TAM20 alloy obtained after rolling are all α phase + β phase. This indicates that the hot rolling treatment decomposes the metastable α′ phase and α″ phase in the cast titanium alloy into stable α phase + β phase.

[0098] Figure 2 The results show that the as-cast titanium alloy has a larger grain size, and the interior of the grain is a fine needle-shaped α′ martensite phase; the rolled strong titanium alloy has an equiaxed α phase and β phase distributed along the rolling direction. Compared with the as-cast titanium alloy, the rolled strong titanium alloy makes the coarse structure in the as-cast titanium alloy fully broken and refined.

[0099] Figure 3 For the mechanical properties diagram, Figure 3 The data in Table 1 are obtained as follows:

[0100] Table 1 Comparison of mechanical properties of the embodiments and comparative examples

[0101]

[0102] The results in Table 1 show that, except for the decreased strength of the rolled HR-TAM12 alloy compared to the cast TAM12 alloy, the other rolled tough titanium alloys have improved strength and plasticity compared to the cast titanium alloy. Comparative Example 3 is a cast TAM12 alloy, which has a large amount of α′ martensite phase. Although it has high strength, it has poor plasticity and cannot maintain excellent strength and plasticity at the same time. The structure of the rolled TAM12 alloy is equiaxed α phase + β phase. Although the strength is decreased compared to the cast TAM12 alloy, the plasticity is greatly improved. It has both strength and plasticity characteristics and excellent mechanical properties.

[0103] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention, and the protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing a rolled tough titanium alloy, characterized in that: The steps include: The titanium sponge, aluminum particles and titanium-molybdenum master alloy are mixed and smelted to obtain an alloy ingot; In the alloy ingot, the mass percentage of aluminum is 6wt%, the mass percentage of molybdenum is 4wt% to 20wt%, the balance is titanium, and the sum of the mass percentages of titanium, aluminum and molybdenum is 100%; heating the alloy ingot to obtain an intermediate; The intermediate is subjected to multiple rolling deformations to achieve rolling deformation, plastic deformation and dynamic recrystallization of the intermediate at high temperature at the same time, and annealing is performed at a rolling temperature corresponding to the rolling deformation between each two adjacent passes. After the rolling deformation is completed, the intermediate is cooled in air to obtain a rolled strong and tough titanium alloy; The final deformation amount after rolling deformation is 70% to 80%.

2. The method for preparing a rolled tough titanium alloy according to claim 1, characterized in that: The heating conditions are: heating at 800°C to 850°C for 20min to 40min.

3. The method for preparing a rolled tough titanium alloy according to claim 1, characterized in that: The rolling temperature is 800℃~850℃.

4. The method for preparing a rolled tough titanium alloy according to claim 1, characterized in that: Each annealing time is 3min to 5min.

5. The method for preparing a rolled tough titanium alloy according to claim 1, characterized in that: The reduction amount of each rolling deformation is 0.2mm~0.4mm.

6. The method for preparing a rolled tough titanium alloy according to claim 1, characterized in that: The rolling deformation process is 30 to 35 times.

7. The method for preparing a rolled tough titanium alloy according to claim 1, characterized in that: The purity of the titanium sponge, aluminum particles and titanium-molybdenum master alloy is all ≥99.9%, and the titanium-molybdenum master alloy is selected from Ti-32Mo alloy.

8. A rolled strong and tough titanium alloy obtained by the preparation method according to any one of claims 1 to 7.

9. The rolled tough titanium alloy according to claim 8, characterized in that: The rolled tough titanium alloy consists of equiaxed α phase and β phase.

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