Alpha + beta double-phase titanium alloy plate strip and forming method thereof

Abstract

The invention relates to the technical field of titanium alloys. Specifically, the invention relates to a forming method of an alpha + beta double-phase titanium alloy plate strip. The forming method comprises the steps that the alpha + beta double-phase titanium alloy plate strip is kept at the annealing treatment temperature T DEG C for t seconds, and the annealing treatment temperature T DEG C ranges from the recrystallization spheroidization temperature Tr DEG C of the alpha + beta double-phase titanium alloy to the alpha-to-beta phase transition temperature T beta-trans DEG C of the alpha + beta double-phase titanium alloy. The numerical values of the annealing treatment time t seconds and the annealing treatment temperature T DEG C meet the following relational expression: 15 < = 100t / (T beta-trans-T) < = 400. By means of the forming method, the annealed-state alpha + beta double-phase titanium alloy plate strip can be formed, the unevenness of the alpha + beta double-phase titanium alloy plate strip can be well controlled while rapid structure spheroidizing of the alpha + beta double-phase titanium alloy plate strip is achieved, and the ideal mechanical property of the alpha + beta double-phase titanium alloy plate strip is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloys. Specifically, the present invention relates to a method for producing α+β dual-phase titanium alloy plate and strip materials, and the present invention also relates to the annealed α+β dual-phase titanium alloy plate and strip materials obtained by the production method. Background Art

[0002] In the conventional cold rolling process of α+β dual-phase titanium alloys (the deformation temperature is generally below 120°C), the maximum rolling deformation is usually less than about 25%. A larger deformation (for example, a deformation of more than about 30%) may cause tissue damage to the titanium alloy strip after rolling, a significant reduction in plasticity after annealing heat treatment (for example, below about 10%), and it cannot be improved by heat treatment methods, making it very difficult to meet the minimum requirements of the standard.

[0003] The conventional process for preparing α+β dual-phase titanium alloy plate and strip materials usually includes recrystallization annealing at a temperature in the range of about 760 to about 900°C, and the annealing time is generally in the range of about 1 to 2 hours to achieve the recrystallization spheroidization of the α phase and the control of the grain sizes of the α and β phases. Long-time annealing is usually suitable for production in a bell-type annealing furnace or a vacuum annealing furnace. However, during the production process in a bell-type annealing furnace or a vacuum annealing furnace, due to the large temperature difference between the inside and outside of the titanium plate and strip during the heating and cooling processes, serious creep of the titanium alloy plate and strip materials will occur during the annealing process, resulting in serious transverse C-shaped warping, making it very difficult to straighten the titanium alloy plate and strip materials, and it is difficult to ensure the flatness. Summary of the Invention

[0004] Object of the Invention

[0005] In view of the problems existing in the prior art described in the above background art section, the purpose of the present invention is to provide a method for producing α+β dual-phase titanium alloy plate and strip materials and the annealed α+β dual-phase titanium alloy plate and strip materials obtained by the production method.

[0006] Embodiment

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] Solution 1: A method for producing α+β dual-phase titanium alloy plate and strip materials, wherein the production method includes annealing the α+β dual-phase titanium alloy plate and strip materials, and the annealing treatment includes maintaining an annealing treatment time of t seconds at an annealing treatment temperature of T°C, where

[0009] the annealing treatment temperature T°C is within the range from the recrystallization spheroidization temperature T r °C of the α+β dual-phase titanium alloy to the α→β phase transformation temperature T β-trans °C of the α+β dual-phase titanium alloy;

[0010] The values ​​of the annealing time t seconds and the annealing temperature T°C meet the following relationship: 15≤100t / (T β-trans -T)≤400.

[0011] Solution 2: According to the material forming method described in the above-mentioned solution 1, the α+β dual-phase titanium alloy sheet and strip comprises, based on the total weight of the α+β dual-phase titanium alloy sheet and strip,

[0012] about 3.0 to about 6.5 mass % of elemental Al,

[0013] about 0.01 to about 0.15 mass % of elemental Fe,

[0014] about ≤ 5.2 mass %, preferably about 3.3 mass % to about 5.2 mass % of the element V, about ≤ 6.0 mass % of the element Mo,

[0015] About ≤ 2.5 mass% of elemental Sn,

[0016] about ≤ 4.0 mass% of element Zr,

[0017] about ≤ 0.5 mass% elemental Si,

[0018] about 0.05 to about 0.20 mass % of elemental O,

[0019] and the balance of elemental titanium and unavoidable impurities.

[0020] Scheme 3: The material forming method according to the above scheme 1 or 2, wherein the recrystallization spheroidization temperature T of the α+β dual-phase titanium alloy is r ℃ is in the range of about 680℃ to about 920℃.

[0021] Scheme 4: A material forming method according to any one of schemes 1 to 3 above, wherein the α→β phase transformation temperature T of the α+β dual-phase titanium alloy is β-trans ℃ is in the range of about 930 to about 1020℃.

[0022] Solution 5: The method for forming a material according to any one of the above solutions 1 to 4, wherein the annealing treatment time t is controlled within the range of about 10 to about 600 seconds while satisfying the relationship.

[0023] Option 6: A material forming method according to any one of the above options 1 to 5, wherein the method further includes cooling the α+β duplex titanium alloy plate and strip from T℃ to a temperature range below about 100℃ after maintaining the annealing temperature T℃ for t seconds, wherein the cooling is preferably carried out by air cooling or cooling in an inert atmosphere.

[0024] Option 7: A material forming method according to any one of the above-mentioned Options 1 to 6, wherein during the process of maintaining the α+β duplex titanium alloy sheet and strip at an annealing temperature T°C for t seconds, a unit tension of about 5 to about 30 MPa is also given to the α+β duplex titanium alloy sheet and strip.

[0025] Solution 8: The material forming method according to any one of claims 1 to 7, wherein the α+β dual-phase titanium alloy sheet and strip is obtained by a process comprising the following steps:

[0026] Step 1: subjecting an α+β dual-phase titanium alloy billet to rolling at a temperature of about 300 to about 760° C. to obtain a rolled α+β dual-phase titanium alloy plate, wherein a rolling deformation amount of the α+β dual-phase titanium alloy billet to form the rolled α+β dual-phase titanium alloy plate is in the range of about 30% to about 60%,

[0027] Step 2: Cool the rolled α+β duplex titanium alloy plate from step 1 to a temperature range below about 100°C to obtain the α+β duplex titanium alloy plate strip, wherein the cooling is preferably performed by air cooling or cooling in an inert atmosphere.

[0028] Option 9: A material forming method according to any one of options 1 to 8 above, wherein the thickness of the α+β dual-phase titanium alloy sheet and strip is in the range of about 0.1 to about 4 mm.

[0029] Scheme 10: An annealed α+β dual-phase titanium alloy sheet and strip obtained by the material forming method according to any one of Schemes 1 to 9 above, wherein the annealed α+β dual-phase titanium alloy sheet and strip obtained has one or more of the following properties:

[0030] The unevenness of the plate and strip is about ≤2mm / m;

[0031] The average grain size is about ≤5 μm;

[0032] The tensile strength is about >980MPa;

[0033] A yield strength of about >840 MPa; and

[0034] The elongation after break is about >11%.

[0035] Technical Effect

[0036] The method for forming an annealed α+β dual-phase titanium alloy sheet and strip of the present invention can achieve rapid structural spheroidization of the α+β dual-phase titanium alloy sheet and strip while also achieving good control of its unevenness and achieving ideal mechanical properties. Specifically, the obtained annealed α+β dual-phase titanium alloy sheet and strip has one or more of the following properties:

[0037] The flatness of the sheet and strip is about ≤ 2 mm / m;

[0038] The average grain size is about ≤ 5 μm;

[0039] The tensile strength is about > 980 MPa;

[0040] The yield strength is about > 840 MPa; and

[0041] The elongation after fracture is about > 11%. Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings required for the specific embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0043] Figure 1 (a) is a micrograph of the cooled rolled TC4 titanium alloy sheet obtained in step 2 of Example 1 of the present invention;

[0044] Figure 1 (b) is a spheroidized micrograph of the annealed α + β duplex TC4 titanium alloy sheet and strip obtained in step 3 of Example 1 of the present invention. Detailed Description of the Embodiments

[0045] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. The process parameters not specified in the following embodiments are usually in accordance with conventional conditions.

[0046] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. The term "about" used in the present invention means that the modified number can fluctuate within the range of ±20%, ±15%, ±10%, ±5% or ±2% of the number. For numerical ranges, the endpoints of each range, between the endpoints of each range and the individual point values covered therein, and between the individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0047] According to a first aspect of the present invention, there is provided a method for producing an α+β dual-phase titanium alloy sheet and strip.

[0048] In the method for producing the sheet and strip according to the first aspect of the present invention, the α+β dual-phase titanium alloy sheet and strip preferably contains, based on the total weight of the α+β dual-phase titanium alloy sheet and strip,

[0049] about 3.0 to about 6.5% by mass (such as about 4.0% by mass, 5.0% by mass or about 6.0% by mass) of elemental aluminum (Al),

[0050] about 0.01 to about 0.15% by mass (such as about 0.05% by mass or about 0.10% by mass) of elemental iron (Fe),

[0051] not more than about 5.2% by mass (such as about 1.0% by mass, about 2.0% by mass, about 3.0% by mass, about 4.0% by mass or about 5.0% by mass, preferably about 3.3% by mass to about 5.2% by mass) of elemental vanadium (V)

[0052] not more than about 6.0% by mass (such as about 1.0% by mass, about 2.0% by mass, about 3.0% by mass, about 4.0% by mass or about 5.0% by mass) of elemental molybdenum (Mo),

[0053] not more than about 2.5% by mass (such as about 0.5% by mass, about 1.0% by mass, about 1.5% by mass or about 2.0% by mass) of elemental tin (Sn),

[0054] not more than about 4.0% by mass (such as about 1.0% by mass, about 2.0% by mass or about 3.0% by mass) of elemental zirconium (Zr),

[0055] not more than about 0.5% by mass (such as about 0.1% by mass, about 0.2% by mass, about 0.3% by mass or about 0.4% by mass) of elemental silicon (Si),

[0056] about 0.05 to about 0.20% by mass (such as about 0.10% by mass or about 0.15% by mass) of elemental oxygen (O),

[0057] and the balance of elemental titanium (Ti) and inevitable impurities.

[0058] In the α+β dual-phase titanium alloy sheet and strip, the Ti element, as the matrix element, becomes the basis of the titanium alloy sheet and strip of the present invention due to its low density, high strength and good corrosion resistance.

[0059] In the α+β dual-phase titanium alloy strip, adding a specific content of Fe element helps to improve the hot working performance and heat treatment control ability of the titanium alloy strip. Here, the content requirement of Fe element is preferably in the range of about 0.01 to 0.15 mass%, too little Fe element (such as less than about 0.01 mass%) may lead to a decrease in the strength and workability of the titanium alloy strip; however, too much Fe element (such as greater than about 0.15 mass%) may lead to a decrease in the plasticity and impact toughness of the titanium alloy strip.

[0060] In the α+β dual-phase titanium alloy strip, adding a specific content of Al element can promote the formation of the α phase (close-packed hexagonal structure) of the α+β dual-phase titanium alloy strip, and enhance the strength, thermal stability and creep resistance of the titanium alloy strip. Here, the content requirement of Al element is preferably in the range of about 3.0 to 6.5 mass%, too little Al element (such as less than about 3.0 mass%) may lead to a decrease in the strength and corrosion resistance of the titanium alloy strip; however, too much Al element (such as greater than about 6.5 mass%) may lead to a decrease in the plasticity and toughness of the titanium alloy strip.

[0061] In the α+β dual-phase titanium alloy strip, adding a specific content of V element mainly acts on the β phase (body-centered cubic structure), thereby improving the plasticity and processing performance of the titanium alloy strip. Here, the content requirement of V element does not exceed about 5.2 mass%, too much V element (such as greater than about 5.2 mass%) may lead to a decrease in the plasticity and high-temperature stability of the titanium alloy strip; however, further preferably, the content of V element is preferably not less than about 3.3 mass%, too little V element (such as less than about 3.3 mass%) may lead to a decrease in the strength and high-temperature performance of the titanium alloy strip.

[0062] In the α+β dual-phase titanium alloy strip, adding a specific content of Al and V generally enables the titanium alloy strip with the α+β dual-phase structure of the present invention to have good toughness while maintaining high strength, and is an ideal choice for many high-end application fields.

[0063] In the α+β dual-phase titanium alloy strip, adding a specific content of Mo element can improve the high-temperature strength and creep resistance of the titanium alloy strip. Here, the content requirement of Mo element is preferably not more than 6.0 mass%, too much Mo element (such as greater than about 6.0 mass%) may lead to a decrease in the plasticity and weldability of the titanium alloy strip.

[0064] In the α+β dual-phase titanium alloy strip, adding a specific content of Sn element can increase the high-temperature strength and creep properties of the titanium alloy strip. Here, the content requirement of Sn element is preferably not more than 2.5% by mass. Excessive Sn element (such as greater than about 2.5% by mass) may cause the plasticity of the titanium alloy strip to decrease and increase its tendency to appear thermal cracks.

[0065] In the α+β dual-phase titanium alloy strip, adding a specific content of Zr element can improve the strength and toughness of the titanium alloy strip. Here, the content requirement of Zr element is preferably not more than 4.0% by mass. Excessive Zr element (such as greater than about 4.0% by mass) may cause the titanium alloy strip to easily contain impurities and form inclusions, leading to high-temperature brittleness under certain conditions.

[0066] In the α+β dual-phase titanium alloy strip, adding a specific content of Si element can improve the thermal stability and creep resistance of the titanium alloy strip. Here, the content requirement of Si element is preferably not more than 0.5% by mass. Excessive Si element (such as greater than about 0.5% by mass) may cause coarse precipitates to form in the titanium alloy strip, reducing the ductility and workability of the strip.

[0067] In the α+β dual-phase titanium alloy strip, O element generally exists as an impurity element, but it has a certain strengthening effect on the strength of the titanium alloy. Therefore, in the α+β dual-phase titanium alloy strip of the present invention, the content requirement of O element is preferably in the range of about 0.05 to about 0.20% by mass. Too little O element (such as less than about 0.05% by mass) may cause the alloy thermal stability of the titanium alloy strip to decrease and the strength to drop; however, too much O element (such as greater than about 0.20% by mass) may cause the plasticity of the titanium alloy strip to significantly decrease and be prone to low-temperature brittleness.

[0068] In some preferred embodiments, the recrystallization globularization temperature T r °C of the α+β dual-phase titanium alloy is in the range of about 680 °C to about 920 °C, such as about 700 °C, about 725 °C, about 750 °C, about 775 °C, about 800 °C, about 825 °C, about 850 °C, about 875 °C or about 900 °C. Here, the recrystallization globularization temperature T r °C should not be too high or too low. For example, it should not be higher than about 920 °C, otherwise it will cause the strength of the titanium alloy strip to drop excessively; nor should it be lower than about 680 °C, otherwise it may affect the plasticity and workability of the titanium alloy strip after annealing.

[0069] In some other preferred embodiments, the α→β phase transformation temperature T of the α+β dual-phase titanium alloy β-trans℃ is in the range of about 930 to about 1020 ℃, for example, about 945 ℃, about 960 ℃, about 975 ℃, about 990 ℃ or about 1050 ℃. Here, firstly, the phase transition temperature is determined according to the selected alloy composition, and secondly, the titanium alloy whose phase transition temperature is not in this temperature range may not achieve the effect of the present invention by using the present annealing process.

[0070] In the material forming method of the first aspect of the present invention, the material forming method comprises annealing the α+β dual-phase titanium alloy sheet and strip, wherein the annealing comprises maintaining the α+β dual-phase titanium alloy sheet and strip at an annealing temperature T°C for t seconds, wherein

[0071] The annealing temperature T°C is within the recrystallization spheroidization temperature T of the α+β dual-phase titanium alloy. r ℃ to the α→β phase transformation temperature T of the α+β dual-phase titanium alloy β-trans ℃ range, and

[0072] The annealing time t seconds and the annealing temperature T°C are in accordance with the following relationship: 100t / (T β-trans -T) is in the range of about 15 to about 400, for example, about 25, about 50,

[0073] About 75, about 100, about 150, about 200, about 250, about 300 or about 350.

[0074] The above relationship is obtained by the inventors of the present invention through statistical analysis based on the rapid annealing test results of the α+β dual-phase titanium alloy sheet and strip involved in the present invention.

[0075] Here, the annealing temperature T°C should not be higher than the phase transformation temperature, otherwise it may cause the titanium alloy sheet and strip to have a coarse structure, and the strength and plasticity after annealing will be reduced; the annealing temperature T°C should not be lower than the recrystallization spheroidization temperature T of the α+β dual-phase titanium alloy. r ℃, otherwise it may cause uneven structure of titanium alloy plate and strip.

[0076] In some further preferred embodiments, the annealing time t is further controlled within the range of about 10 to about 600 seconds while satisfying the relationship, for example, about 15 seconds, about 60 seconds, about 100 seconds, about 200 seconds, about 300 seconds, about 400 seconds or about 500 seconds. The annealing time herein should not be too long, for example, should not exceed about 600 seconds. Too long annealing time not only affects production efficiency, but also is not conducive to the control of fine structures, and the superplastic processing performance of some materials cannot be achieved. It should not be too short, for example, should not be less than about 10 seconds, otherwise the desired spheroidization effect may not be achieved.

[0077] In a further preferred embodiment of the material forming method of the first aspect of the present invention, the material forming treatment further includes cooling the α+β dual-phase titanium alloy sheet and strip from T℃ to a temperature range below about 100℃, such as cooling to about 75℃, about 50℃ or about 25℃ after maintaining the annealing treatment temperature T℃ for t seconds, wherein the cooling is preferably carried out by air cooling or cooling in an inert atmosphere. Here, the annealing cooling temperature should not be too high, for example, it should not be higher than about 100℃, otherwise it will cause the titanium alloy sheet and strip to absorb oxygen and become dark or yellow in color, affecting the appearance and corrosion resistance of the material.

[0078] In a further preferred embodiment of the material forming method of the first aspect of the present invention, in the process of maintaining the α+β duplex titanium alloy sheet and strip at the annealing temperature T℃ for t seconds, it is also preferred to apply tension to the α+β duplex titanium alloy sheet and strip, and the magnitude of the tension is in the range of about 5 to about 30MPa unit tension, such as about 8MPa, about 12MPa, about 17MPa, about 20MPa or about 25MPa. Here, the tension is given to control the plate shape and unevenness of the annealed material. The magnitude of the tension is mainly indirectly controlled by the coiler speed and the pressure detected by the tension meter. In addition, the applied tension is preferably not higher than about 30MPa unit tension, otherwise it may cause the titanium alloy sheet and strip to be overstretched and produce plastic deformation; it is also not suitable to be lower than about 5MPa unit tension, otherwise it may be impossible to control the plate shape of the titanium alloy sheet and strip, and wrinkles may easily appear.

[0079] In some preferred embodiments of the material forming method according to the first aspect of the present invention, the α+β dual-phase titanium alloy sheet and strip can be obtained by a process including the following steps 1 and 2.

[0080] The step 1 includes subjecting the α+β dual-phase titanium alloy billet to rolling at a temperature of about 300 to about 760°C (e.g., about 400°C, about 500°C, about 600°C, or about 700°C) to obtain a rolled α+β dual-phase titanium alloy plate, wherein the rolling deformation of the rolled α+β dual-phase titanium alloy plate formed by rolling the α+β dual-phase titanium alloy billet is in the range of about 30% to about 60% (e.g., about 40% or about 50%). Here, the set temperature is determined based on the processing plasticity and high-temperature oxidation properties of the material. Increasing the temperature will produce oxidation, but it is beneficial to rolling deformation and the plasticity of the material after processing. The two are in a contradictory relationship. Therefore, the inventors of the present invention select the rolling temperature in the range of about 300 to about 760°C based on the balance between material processing and oxidation properties.

[0081] The step 2 includes cooling the rolled α+β dual-phase titanium alloy plate from the step 1 to a temperature range of about 100°C or less (e.g., cooling to about 75°C, about 50°C, or about 25°C) to obtain the α+β dual-phase titanium alloy plate strip, wherein the cooling is preferably performed by air cooling or cooling in an inert atmosphere. The temperature reached by the cooling should not be higher than about 100°C, in order to prevent excessive martensitic structure from being generated by rapid cooling, and to prevent coarse structure caused by low cooling rate.

[0082] It is precisely because of the warm processing in the above-mentioned rolling process and the greater deformation caused by the warm processing that the recrystallization and spheroidization in a short time in the subsequent process can be better promoted.

[0083] In the material forming method of the first aspect of the present invention, there is no particular limitation on the thickness of the α+β duplex titanium alloy plate and strip. However, in some exemplary embodiments of the present invention, the thickness can be controlled within the range of about 0.1 to about 4 mm, for example, about 0.4 mm, about 1 mm, about 2 mm or about 3 mm.

[0084] According to a second aspect of the present invention, the present invention provides an annealed α+β dual-phase titanium alloy sheet and strip obtained by the material forming method as described in the first aspect of the present invention. The microstructure of the annealed α+β dual-phase titanium alloy sheet and strip in the present invention belongs to any one of a dual-state structure, a Widmanstatten structure, an equiaxed structure, and a basket structure.

[0085] The annealed α+β dual-phase titanium alloy sheet and strip according to the second aspect of the present invention has one or more of the following properties:

[0086] The unevenness of the plate strip is about ≤2 mm / m, preferably about ≤1 mm / m;

[0087] The average grain size is about ≤5 μm;

[0088] The tensile strength is about >980MPa;

[0089] A yield strength of about >840 MPa; and

[0090] The elongation after break is about >11%.

[0091] The present invention is further described in detail below with reference to specific embodiments and comparative examples.

[0092] The α+β dual-phase TC4 alloy blanks used in the following examples and comparative examples have the following dimensions: a width of about 1000 mm, a thickness of about 2 mm, and a recrystallization spheroidization temperature of T r In the range of about 770 to about 820°C; α→β phase transition temperature T β-transis about 990 °C. The elemental weight percentage content of the α+β duplex TC4 titanium alloy blank falls within the elemental content range disclosed in the Summary of the Invention section of the present invention.

[0093] Examples and Comparative Examples

[0094] Examples 1 to 4: Preparation of annealed α+β duplex TC4 titanium alloy sheet and strip

[0095] The annealed α+β duplex TC4 titanium alloy sheet and strip are obtained from the α+β duplex TC4 titanium alloy blank through the following steps:

[0096] Step 1: Subject the α+β duplex TC4 titanium alloy blank to rolling at the rolling temperature shown in Table 1 to obtain a rolled α+β duplex TC4 titanium alloy sheet, wherein the rolling deformation amount of the α+β duplex TC4 titanium alloy blank caused by the rolling is also shown in Table 1.

[0097] Step 2: Cool the rolled α+β duplex titanium alloy sheet from Step 1 to below about 100 °C to obtain a cooled rolled α+β duplex TC4 titanium alloy sheet, wherein the cooling method is air cooling.

[0098] Step 3: Subject the α+β duplex TC4 titanium alloy sheet rolled in Step 1 to annealing for an annealing time t at the annealing temperature T shown in Table 1 to obtain an annealed α+β duplex TC4 titanium alloy sheet. During the annealing process, a certain tension is applied to the α+β duplex titanium alloy sheet. After the annealing treatment, air-cool the annealed α+β duplex TC4 titanium alloy sheet to below about 100 °C to obtain the annealed α+β duplex TC4 titanium alloy sheet and strip.

[0099] Comparative Example 1:

[0100] An annealed α+β duplex TC4 titanium alloy sheet and strip are obtained from the α+β duplex TC4 titanium alloy blank by a process similar to that of Example 1, except for using the process parameters shown in Table 1.

[0101] Table 1

[0102]

[0103] The rolled α+β duplex TC4 titanium alloy sheets obtained from Step 2 and the annealed α+β duplex TC4 titanium alloy sheets and strips obtained from Step 3 in Examples 1 to 4 and Comparative Example 1 above are respectively subjected to performance tests and photographed for microstructures (see the microstructure photograph of the titanium alloy sheet in Example 1 Figure 1 ).

[0104] Among them, the tensile strength, yield strength and elongation are measured according to Chinese national standard GB / T 228.1-2021; the average grain size is measured according to Chinese national standard GB / T 6394-2017; the surface roughness is measured according to Chinese national standard GB / T 38982-2020.

[0105] The test results are shown in Table 2.

[0106] Table 2

[0107]

[0108] It can be seen from the data in Table 1 and Table 2 above:

[0109] Examples 1 to 3 use the same rolled plate, only annealed at different temperatures subsequently. As the annealing temperature increases, the average grain size in the titanium alloy gradually increases, the tensile and yield strengths of the annealed titanium alloy gradually increase, and the elongation decreases.

[0110] Examples 4 and 5 use the same cold-rolled plate, only annealed for different times subsequently. Comparative Example 2 and Examples 1 to 3 also use the same rolled plate, only annealed for different times subsequently, resulting in different calculation results of the relational formula.

[0111] The titanium alloy strip obtained from Examples 1 to 5 of the present invention has better comprehensive properties (tensile strength is about >980 MPa, yield strength is about >840 MPa, and elongation after fracture is about >11%). The process parameters used can control grain growth (not exceeding about 5 μm), improve the comprehensive mechanical properties of the material, and at the same time the surface roughness is about ≤2 mm / m; while in Comparative Example 1, the grains grow excessively after annealing (exceeding about 5 μm), resulting in a decrease in strength, a reduction in plasticity, and the surface roughness not meeting the requirements, indicating that the heat treatment process of Comparative Example 1 cannot achieve the technical effects to be achieved by the present invention. The individual properties of the titanium alloy strip obtained from Comparative Example 2 and Comparative Example 3 may be able to meet the requirements in the present invention, but the overall comprehensive properties cannot meet the requirements.

[0112] From the tissue Figure 1 photographs in the specification appendix, it can also be seen that after annealing, the titanium alloy strip of the present invention undergoes complete recrystallization, and the structure in the rolled state becomes the structure in the annealed state (i.e., fine equiaxed grains).

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions claimed by the present invention.

Claims

1. A method for producing α+β dual-phase titanium alloy sheet and strip, characterized in that: The material forming method comprises annealing the α+β dual-phase titanium alloy plate and strip, wherein the annealing comprises maintaining the annealing temperature T°C for t seconds, wherein: The annealing temperature T°C is within the recrystallization spheroidization temperature T of the α+β dual-phase titanium alloy. r ℃ to the α→β phase transformation temperature T of the α+β dual-phase titanium alloy β-trans ℃ range; and The values ​​of the annealing time t seconds and the annealing temperature T°C meet the following relationship: 15≤100t / (T β-trans -T)≤400.

2. The method for forming timber according to claim 1, characterized in that: The α+β duplex titanium alloy plate and strip comprises, based on the total weight of the α+β duplex titanium alloy plate and strip, 3.0 to 6.5 mass % of elemental Al, 0.01 to 0.15 mass % of elemental Fe, ≤5.2 mass %, preferably 3.3 to 5.2 mass % of element V, ≤ 6.0 mass% of elemental Mo, ≤2.5 mass% of element Sn, ≤ 4.0 mass% of element Zr, ≤ 0.5 mass% elemental Si, 0.05 to 0.20 mass% of element O, and the balance of elemental titanium and unavoidable impurities.

3. The method for forming timber according to claim 1, characterized in that: The recrystallization spheroidization temperature T of the α+β dual-phase titanium alloy r ℃ is in the range of 680℃ to 920℃.

4. The method for forming timber according to claim 1, characterized in that: The α→β phase transition temperature T of the α+β dual-phase titanium alloy β-trans In the range of 930 to 1020°C.

5. The method for forming timber according to claim 1, characterized in that: The annealing treatment time t is further controlled within the range of 10 to 600 seconds while satisfying the relationship.

6. The method for forming timber according to claim 1, characterized in that: The method also includes cooling the α+β dual-phase titanium alloy plate and strip from T°C to a temperature range below 100°C after maintaining the annealing temperature T°C for t seconds, wherein the cooling is preferably carried out by air cooling or cooling in an inert atmosphere.

7. The method for forming timber according to claim 1, characterized in that: In the process of maintaining the α+β duplex titanium alloy sheet and strip at the annealing temperature T°C for t seconds, a unit tension of 5 to 30 MPa is also applied to the α+β duplex titanium alloy sheet and strip.

8. The method for forming timber according to any one of claims 1 to 7, characterized in that: The α+β dual-phase titanium alloy sheet and strip is obtained by a process comprising the following steps: Step 1: subjecting the α+β dual-phase titanium alloy billet to rolling at a temperature of 300 to 760° C. to obtain a rolled α+β dual-phase titanium alloy plate, wherein the rolling deformation amount of the rolled α+β dual-phase titanium alloy plate formed by rolling the α+β dual-phase titanium alloy billet is in the range of 30% to 60%, Step 2: Cool the rolled α+β duplex titanium alloy plate from step 1 to a temperature range below 100°C to obtain the α+β duplex titanium alloy plate strip, wherein the cooling is preferably performed by air cooling or cooling in an inert atmosphere.

9. The method for forming timber according to any one of claims 1 to 7, characterized in that: The thickness of the α+β dual-phase titanium alloy plate and strip is in the range of 0.1 to 4 mm.

10. The annealed α+β dual-phase titanium alloy sheet and strip obtained by the material forming method according to any one of claims 1 to 9, characterized in that: The obtained annealed α+β dual-phase titanium alloy sheet and strip has one or more of the following properties: The unevenness of the plate and strip is ≤2mm / m; The average grain size is ≤5μm; Tensile strength >980MPa; Yield strength >840MPa; and The elongation after break is >11%.

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