Preparation method of heterostructure high-performance metastable beta titanium alloy capable of inducing deformation mechanism in multilevel and sequential mode

Abstract

The invention discloses a preparation method of a heterostructure high-performance metastable beta titanium alloy capable of inducing a deformation mechanism in a multilevel and sequential mode, and belongs to the technical field of metal materials. The method comprises the following steps: firstly, carrying out hot rolling in a beta single-phase region to prepare a blank and crushing coarse grains; substructures such as twin crystals and martensite are introduced through cold rolling; and through short-time annealing in a beta single-phase region, a multi-stage heterogeneous lamellar structure composed of thick equiaxed crystal grains, deformation recovery crystal grains and fine recrystallized crystal grains in an alternating manner is successfully constructed. The characteristic that twin crystals and martensite induce different stresses under different grain sizes is utilized, during deformation, thick equiaxed grains firstly start a deformation mechanism, and then fine recrystallized grains are activated; and in the later period of plastic deformation, the interior of the primary deformation strip further triggers a secondary deformation mechanism. The unique behavior of'grading-time sequence 'activation of a multi-deformation mechanism along with the increase of the dependent variable enables the metastable beta titanium alloy to keep excellent plasticity, and meanwhile, the work hardening rate is remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal materials, and particularly relates to a preparation method of a high-performance metastable beta titanium alloy with a heterogeneous structure capable of inducing a multistage and time sequence deformation mechanism. BACKGROUND

[0002] The metastable beta titanium alloy can obtain an extremely high work hardening rate (θ>2000 MPa) by triggering a transformation induced plasticity (TRIP) and / or a twinning induced plasticity (TWIP) mechanism, while maintaining good ductility. However, such an alloy usually exhibits a low yield strength (200-300 MPa). In addition, since the beta phase has a high stacking fault energy, dynamic recovery is prone to occur during hot deformation, and it is difficult to recrystallize, resulting in a deformation structure mainly composed of coarse elongated or equiaxed beta grains, which cannot effectively improve the strength. Even after cold deformation and recrystallization annealing, it is often difficult to form a complete recrystallized structure, thereby affecting the balance between strength and plasticity.

[0003] In order to improve the performance of the metastable beta titanium alloy, a method of aging treatment after hot deformation is usually adopted to improve the yield strength by precipitating a second phase such as omega or alpha in the beta matrix. However, although the introduction of such a brittle second phase can significantly improve the yield strength, it inevitably reduces the work hardening rate, resulting in a sharp decrease in ductility and a significant increase in Young's modulus, which is not conducive to the optimization of the comprehensive mechanical properties of the alloy. SUMMARY

[0004] In view of the problem that the plasticity and work hardening performance of the metastable beta titanium alloy significantly decrease during the process of improving the strength, the application provides a preparation method of a high-performance metastable beta titanium alloy with a heterogeneous structure capable of inducing a multistage and time sequence deformation mechanism. The method successfully constructs a heterogeneous lamellar heterogeneous structure with multistage grains by implementing hot rolling, cold rolling and annealing processes on the metastable beta titanium alloy. The structure can induce multiple deformation mechanisms in a multistage and time sequence manner, effectively breaking through the inverted relationship between the increase in strength and the decrease in plasticity and work hardening rate in traditional strengthening, while maintaining excellent plasticity, significantly improving the yield strength of the alloy and simultaneously increasing the work hardening rate.

[0005] To achieve the above-mentioned purpose, the application provides the following technical scheme:

[0006] A preparation method of a high-performance metastable beta titanium alloy with a heterogeneous structure capable of inducing a multistage and time sequence deformation mechanism, comprising the following steps:

[0007] (1) uniformly treating the metastable beta titanium alloy in a beta single-phase region, and then cooling it to room temperature in the furnace;

[0008] (2) heating and hot rolling the metastable beta titanium alloy obtained in step (1) in a beta phase region, holding and water cooling after hot rolling;

[0009] (3) cold rolling deformation on the plate obtained in step (2) to obtain a plate containing martensite and twin substructure;

[0010] (4) short-time annealing the plate containing martensite and twin substructure obtained in step (3) in a beta single-phase region to form a multi-level grain heterogeneous lamellar heterostructure, i.e. a high-performance metastable beta titanium alloy.

[0011] The present application successfully designs a heterogeneous lamellar heterostructure with multi-level grain size by simple processes such as hot rolling, cold rolling and heat treatment. The organization is composed of a recrystallized layer composed of coarse recrystallized grains, and a composite structure layer composed of deformed recovery grains and fine recrystallized grains. This lamellar heterostructure based on grain size gradient utilizes the strain gradient generated by the inhomogeneity of soft domains (large grains) and hard domains (small grains) during deformation to provide significant heterogeneous deformation-induced (HDI) strengthening and additional strain hardening capacity for the alloy. The synergistic effect of fine grains and heterogeneous structure greatly improves the yield strength of the alloy. At the same time, the difference in grain size affects the induced stress of the deformation strip, resulting in a unique time sequence feature of TWIP and TRIP effect, i.e. preferentially starting in large grains and then appearing in small grains. With the increase of tensile deformation, finer secondary deformation strips will be formed in the primary deformation twins of the metastable beta titanium alloy after plastic deformation. These secondary strips act as barriers to hinder dislocation slip in the primary {332}<112> twin, thereby strengthening the primary twin; the strengthened twin further hinders dislocation slip. The formation of secondary strips provides additional work hardening for the alloy.

[0012] The core of the present application: the heterogeneous lamellar structure based on multi-level grain size construction can induce TWIP / TRIP effect and secondary deformation band mechanism in a multi-level and time sequence during plastic deformation. The coupling of these deformation mechanisms in a multi-level time sequence enables the alloy to provide extremely high work hardening rate in a very wide plastic deformation range while significantly improving the yield strength, thereby maintaining excellent plasticity and achieving a good match between strength and plasticity. This solves the problem of difficult to balance plasticity when improving the strength of metastable beta titanium alloy. Unlike the second phase strengthening introduced in the comparative patent (CN 202110345276.3), the present application only realizes strengthening by regulating the microstructure of a single beta phase. The specific process key lies in: making full use of the uneven distribution of cold rolling deformation, combining with short-time annealing, and fully utilizing the characteristics of twin grain boundaries to promote recrystallization, and finally forming a lamellar heterogeneous structure distributed along the rolling direction. This structure contains three types of characteristic grains: a large number of fine recrystallized grains, coarse equiaxed recrystallized grains grown during annealing, and deformation recovery grains. This new heterogeneous structure significantly improves the strength while effectively improving the work hardening rate and plasticity of the alloy through multiple deformation mechanisms activated in a multi-level time sequence.

[0013] Further, the temperature of the homogenization treatment in step (1) is 1000℃, and the holding time is 1h.

[0014] Further, the specific process of heating in step (2) is: heating the metastable beta titanium alloy to 850℃ and holding for 30min for blooming.

[0015] Further, the specific process of hot rolling in step (2) is: hot rolling the alloy after heating treatment in a two-roller mill with a pass deformation of 15%, and reheating and holding for 5min after each hot rolling pass; after rolling to a plate thickness of 10mm, the temperature is lowered to 800℃ for further hot rolling, and the total deformation of hot rolling is 82% until the plate thickness is 3mm; then water cooling after holding at 800℃ for 5min.

[0016] Further, in the cold rolling deformation process in step (3), the cold rolling pass amount is 0.05mm, and the plate is rolled from 3mm to 1mm, and the total cold rolling deformation is 60%.

[0017] Further, the temperature of the short-time annealing in step (4) is 770-780℃, and the holding time is 5min.

[0018] The present application also provides a high-performance metastable beta titanium alloy prepared by the above preparation method, which has a multi-level grain heterogeneous lamellar heterogeneous structure composed of coarse equiaxed grains, deformation recovery grains and fine recrystallized grains.

[0019] Further, the average size of the coarse equiaxed grains is 31-48 mu m; the average size of the deformed recovery grains is 29-33 mu m; and the average size of the fine recrystallized grains is 3-3.5 mu m.

[0020] Compared with the prior art, the present application has the following advantages and technical effects:

[0021] 1. The present application utilizes the uneven distribution of the cold rolling deformation, and successfully prepares a novel three-level grain inhomogeneous sheet layer heterogeneous structure composed of fine recrystallized grains, deformed recovery grains and coarse equiaxed recrystallized grains, and distributed along the rolling direction through subsequent short-time annealing.

[0022] 2. During the annealing process, the present application utilizes the deformation bands (twin boundaries, etc.) generated by cold deformation to introduce a large number of fine recrystallized grains with an average size of about 3 mu m, providing fine-grain strengthening. At the same time, by utilizing the characteristics that the soft domains (large grains) and the hard domains (small grains) in the heterogeneous structure deform asynchronously, a significant strain gradient is generated at the domain interface, inducing the accumulation of geometrically necessary dislocations (GNDs), and producing HDI strengthening. The synergistic coupling effect of the above-mentioned fine-grain strengthening and HDI strengthening together realizes a substantial increase in the strength of the alloy.

[0023] 3. The present application does not introduce a second phase, maintaining the inherent metastable characteristics of the beta phase. By utilizing the grain size gradient factor in the heterogeneous structure, the TWIP and / or TRIP effects are induced in a hierarchical and time-sequential manner during deformation. In the later stage of deformation, the secondary deformation band mechanism is further triggered. These multi-level time-sequential activated deformation mechanisms continuously provide the alloy with extremely high work hardening capacity, thereby significantly improving the yield strength of the alloy without sacrificing the plasticity.

[0024] 4. The present application has a simple process and short flow. A three-level grain inhomogeneous sheet layer heterogeneous structure is designed, which hierarchically and time-sequentially induces deformation mechanisms as the tensile deformation increases. This heterogeneous structure can significantly improve the yield strength and work hardening rate of the alloy without sacrificing the plasticity. This method is an excellent solution to improve the performance of metastable beta titanium alloys. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which form a part of the present application, are used to provide a further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explanations rather than limiting the present application. In the drawings:

[0026] Figure 1 is a diagram of the plate after hot rolling in Example 1;

[0027] Figure 2 is a diagram of the plate after cold rolling in Example 1;

[0028] Figure 3Optical micrograph of the microstructure of the alloy produced in Example 1 after cold rolling;

[0029] Figure 4 IPF map of the microstructure of the heterogeneous metastable beta titanium alloy produced in Example 1 ;

[0030] Figure 5 IPF map of the deformation bands induced by the grain size effect at 2% and 4% strain of the alloy produced in Example 1 ;

[0031] Figure 6 Transmission image of the secondary twins induced within the primary twins at the later stage of plastic straining of the alloy produced in Example 1 ;

[0032] Figure 7 IPF map of the microstructure of the heterogeneous metastable beta titanium alloy produced in Example 2;

[0033] Figure 8 IPF map of the deformation bands induced by the grain size effect at 2% and 4% strain of the alloy produced in Example 2;

[0034] Figure 9 Transmission image of the secondary twins induced within the primary twins at the later stage of plastic straining of the alloy produced in Example 2;

[0035] Figure 10 IPF map of the microstructure of the homogeneous equiaxed single beta phase metastable beta titanium alloy produced in Comparative Example 1 ;

[0036] Figure 11 Mechanical property test results of the alloys produced in Example 1, Example 2, and Comparative Example 1 ;

[0037] Figure 12 Work hardening rate property test results of the alloys produced in Example 1, Example 2, and Comparative Example 1. DETAILED DESCRIPTION

[0038] Various illustrative embodiments of the present application are now described in detail below. The described embodiments are not intended to limit the scope of the application, but instead are presented as a series of examples, wherein those skilled in the art can recognize equivalents within the spirit of the application.

[0039] It should be understood that the terms used herein are for the purpose of describing particular embodiments and are not intended to limit the application. Additionally, for a range of values, it is intended that every intervening value between the upper and lower limit, as well as any other stated or intervening values in that stated range, is encompassed. Any smaller ranges between an stated value or intervening value in a stated range and any other stated or intervening value in that stated range are also encompassed. The upper and lower limits of these smaller ranges can independently be included or excluded in the range, and the endpoints are included in the ranges.

[0040] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this application pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All publications mentioned in this specification are herein incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference is not an admission that it is prior art with respect to the present application.

[0041] Many modifications and variations of this application specification of the specific embodiments of the application can be practiced in accordance with the principles of the application, and such variations can become apparent to those skilled in the art once informed by the general nature of the application when the application specification is read with the attendant knowledge of technologies relating to the application. Additional implementations of the present application will be apparent to those skilled in the art from a consideration of the specification or practice of the application. The specification and examples given are exemplary only.

[0042] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean including, but not limited to.

[0043] The embodiment of the present application provides a preparation method of a high-performance metastable β titanium alloy with a heterogeneous structure of a multi-stage and time sequence induced deformation mechanism, comprising the following steps:

[0044] (1) homogenization treatment: the metastable β titanium alloy is homogenized at 1000℃ (β single-phase region) for 1h, and then cooled to room temperature in the furnace;

[0045] (2) hot rolling and rolling: ① the alloy plate with a thickness of 15mm after homogenization treatment is placed in a muffle furnace, heated to 850℃ (β phase region) for 30min for breakdown; ② then hot rolling is carried out on a two-roller rolling mill: the deformation amount of each pass is 15%, after each pass rolling, the furnace is returned (850℃) and kept for 5min, when the thickness is reduced to 10mm, the temperature is reduced to 800℃ (β phase region) for continuous rolling, and the total hot rolling deformation is 82% (the final plate thickness is 3mm); ③ the hot-rolled plate is placed in the furnace at 800℃ for 5min and then water-cooled;

[0046] (3) Cold rolling deformation and microstructure characteristics: The water-cooled plate obtained in step (2) is cold-rolled on a two-roller mill: the pass reduction is 0.05 mm, and the total cold rolling deformation is 60% (the final plate thickness is 1 mm). The plate after cold rolling has good mechanical properties. Since the critical shear stress for inducing martensite in the metastable β titanium alloy is smaller than the critical shear stress for inducing twinning, martensite is preferentially induced in the grains with small cold deformation; with the increase of the cold deformation, twinning appears in the grains. Therefore, the cold rolling microstructure is composed of elongated β grains and the induced martensite and twinning inside, showing a hierarchical induction feature: the grains with small deformation mainly have martensite, and the grains with large deformation mainly have twinning;

[0047] (4) Short-time annealing and formation of heterogeneous structure:

[0048] S1, annealing process and micro mechanism: The cold-rolled plate obtained in step (3) is short-time annealed in the β single-phase region, and the uneven distribution of cold rolling deformation and the difference in the induced substructure are utilized:

[0049] Grains inducing martensite: small cold deformation → low stored energy → mainly recovery during annealing → formation of coarse recovery grains;

[0050] Grains inducing twinning: large cold deformation → high stored energy, and the twinning boundary provides nucleation sites for recrystallization → recrystallization during annealing → formation of a large number of fine recrystallized grains;

[0051] The present application is to utilize the different evolution behaviors of the martensite and twinning substructures formed in cold rolling during annealing to induce the formation of a three-level grain heterogeneous lamellar heterogeneous structure composed of coarse recovery grains, coarse recrystallized grains and fine recrystallized grains.

[0052] S2, specific process parameters and performance results:

[0053] Scheme A (low lamellar density): The cold-rolled plate is placed in a muffle furnace at 780℃ (β phase region) for 5 min, and a three-level grain heterogeneous lamellar heterogeneous structure with low lamellar density (fine recrystallized grain size 3.42 μm, deformed recovery grain size 32.78 μm, coarse recrystallized size 48.04 μm) can be obtained. The performance index is significantly improved, the tensile strength is 1053.6 MPa, the yield strength is 764.77 MPa, and the elongation is 36.28%.

[0054] Scheme B (high sheet density): the cold-rolled sheet is put into a muffle furnace, heated to 770℃ (beta phase zone), and kept for 5 min, so that a high sheet density three-level grain heterogeneous sheet heterostructure organization (fine recrystallized grain size 3.41 μm, deformed recovery grain size 29.79 μm, coarse recrystallized size 31.38 μm) is obtained, and the performance index is significantly improved, the tensile strength is 1081 MPa, the yield strength is 906 MPa, and the elongation is 29.65%.

[0055] In the present application, "room temperature" refers to 25±2℃ unless otherwise specified.

[0056] In the present application, all raw materials are purchased from the market.

[0057] The technical solutions of the present application are further illustrated by the following examples.

[0058] Example 1

[0059] A preparation method of a high-performance metastable beta titanium alloy with a multi-level and time sequence induced deformation mechanism heterostructure, the steps are as follows:

[0060] (1) The metastable beta titanium alloy is homogenized at 1000℃ (beta single phase zone) for 1h, and then cooled to room temperature in the furnace;

[0061] (2) The 15mm-thick alloy sheet after homogenization is placed in a muffle furnace, heated to 850℃ (beta phase zone) and kept for 30 min for blooming; then hot rolling is carried out on a two-roller mill with a deformation amount of 15% per pass, and the sheet is reheated (850℃) and kept for 5 min after each pass, and then rolled to a thickness of 10mm, and then the temperature is reduced to 800℃ (beta phase zone) for further rolling, and the total hot rolling deformation is 82%, until the sheet thickness is reduced to 3mm, and then the hot-rolled sheet is placed in the furnace at 800℃ for 5 min and then water-cooled (as shown in Figure 1 );

[0062] (3) The water-cooled sheet obtained in step (2) is cold-rolled on a two-roller mill with a pass reduction of 0.05mm, and the total cold rolling deformation is 60%, and the sheet is rolled to 1mm (as shown in Figure 2 , and the microstructure of the alloy after cold rolling is as shown in Figure 3 );

[0063] (4) The cold-rolled sheet obtained in step (3) is placed in a muffle furnace and kept at 780℃ (beta phase zone) for 5 min, so that a metastable beta titanium alloy with a three-level grain heterogeneous sheet heterostructure organization is obtained, and the IPF microstructure is as shown in Figure 4 .

[0064] From Figure 4It can be seen from the figure that there are a large number of fine recrystallized grains (average size of about 3.42 μm), retained deformed recovered grains (average size of 32.78 μm) and coarse equiaxed grains (average size of 48.04 μm) distributed in the form of lamellar in the microstructure of the alloy.

[0065] Figure 5 The IPF figures of the deformation bands induced by the hierarchical time sequence due to the grain size at strains of 2% and 4% for the alloy prepared in Example 1 can be seen from the figures. It can be seen that at a strain of 2%, the deformation bands only appear in the coarse recrystallized lamellar in the microstructure of the alloy, and at a strain of 4%, high-density deformation bands are induced in the fine equiaxed grains.

[0066] Figure 6 The transmission figure of the secondary twinning induced in the primary twinning in the later stage of plastic strain of the alloy prepared in Example 1 (the transmission experiment is performed on the tensile sample after the sample is broken, the secondary twinning appears in the primary twinning, which is a complementary mechanism of the primary deformation mechanism, i.e. the later stage of plastic deformation, and is observed in the tensile broken sample by default) can be seen from the figure. Figure 6 It can be seen from the figure that in the later stage of deformation, the secondary twinning is induced in the primary twinning, and a large number of dislocations are accumulated on the primary twinning boundary.

[0067] Example 2

[0068] A preparation method of a high-performance metastable β titanium alloy with a heterogeneous structure capable of inducing deformation mechanisms in multiple levels and time sequences, steps are as follows:

[0069] (1) homogenize the metastable β titanium alloy at 1000 ℃ (β single-phase region) for 1 h, and then cool to room temperature in the furnace;

[0070] (2) place the alloy plate with a thickness of 15 mm after the homogenization treatment in a muffle furnace, heat to 850 ℃ (β phase region) and keep for 30 min for blooming; then perform hot rolling on a two-roller rolling mill with a deformation amount of 15% per pass, reheat (850 ℃) and keep for 5 min after each pass, continue to roll until the thickness is 10 mm, then reduce the temperature to 800 ℃ (β phase region) and continue to roll, the total hot rolling deformation is 82%, until the thickness of the plate is 3 mm, finally, water cool the hot rolled plate after keeping at 800 ℃ for 5 min in the furnace;

[0071] (3) cold roll the water-cooled plate obtained in step (2) on a two-roller rolling mill with a pass reduction of 0.05 mm, and the total cold rolling deformation is 60%, and the plate is rolled to 1 mm;

[0072] (4) place the cold-rolled plate obtained in step (3) in a muffle furnace, keep at 770 ℃ (β phase region) for 5 min, and obtain a metastable β titanium alloy with a non-homogeneous lamellar heterogeneous structure with three levels of grains, and the microstructure IPF figure is as follows:Figure 7 As shown.

[0073] from Figure 7 As can be seen, the microstructure contains a large number of fine recrystallized grains (average size of about 3.41 μm), retained deformation recovery grains (average size of 29.79 μm), and coarse equiaxed grains (average size of 31.38 μm) distributed in a lamellar pattern.

[0074] Figure 8 The IPF diagrams of the alloy prepared in Example 2, showing the graded deformation bands induced by grain size factors at strains of 2% and 4%, show that at strain of 2%, the deformation bands only appear in the coarse recrystallized lamellar layers. When the deformation increases to 4%, fine equiaxed crystals also induce high-density deformation bands.

[0075] Figure 9 The image shows the transmission spectrum of the alloy prepared in Example 2 during the later stage of plastic strain, where secondary twins are induced within primary twins. Figure 9 As can be seen from the data, as the deformation increases, secondary martensite is induced within the primary twins in this alloy.

[0076] Comparative Example 1

[0077] A method for preparing a uniform equiaxed single-β phase metastable β titanium alloy, comprising the following steps:

[0078] (1) The metastable β titanium alloy was homogenized by holding it at 1000℃ (β single phase region) for 1h, and then cooled to room temperature in the furnace.

[0079] (2) The alloy plate with a thickness of 15 mm after homogenization is placed in a muffle furnace and heated to 850℃ (β phase region) and held for 30 min to open the billet; then it is hot rolled on a two-roll mill with a deformation of 15% per pass. After each pass, it is returned to the furnace (850℃) and held for 5 min. After rolling to a thickness of 10 mm, the temperature is reduced to 800℃ (β phase region) and rolling is continued. The total hot rolling deformation is 82% until the plate thickness becomes 3 mm. Finally, the hot-rolled plate is placed in the furnace and held at 800℃ for 5 min before water cooling.

[0080] (3) The water-cooled sheet obtained in step (2) is cold-rolled on a two-roll mill. The reduction in each pass is 0.05 mm, and the total cold-rolling deformation is 60%. The sheet is rolled to 1 mm.

[0081] (4) The cold-rolled sheet obtained in step (3) is placed in a muffle furnace and held at 800℃ (β phase region) for 10 min to obtain a uniform equiaxed single β phase metastable β titanium alloy. The IPF microstructure is shown in the figure. Figure 10 As shown.

[0082] from Figure 10As can be seen, the microstructure after hot rolling is equiaxed, with a grain size of 70 μm.

[0083] The room temperature tensile properties of the alloys prepared in Examples 1, 2, and 1 are tested, and the results are as follows: Figure 11 As shown, the work hardening rate of the alloy was tested, and the results are as follows. Figure 12 As shown.

[0084] from Figure 11 As can be seen, the heterostructure metastable β-titanium alloy prepared in Example 1 has a yield strength of 764.77 MPa, a tensile strength of 1053.6 MPa, and an elongation at break of 36.28%; the heterostructure metastable β-titanium alloy prepared in Example 2 has a yield strength of 906 MPa, a tensile strength of 1081 MPa, and an elongation at break of 29.65%; and the homogeneous equiaxed single-β phase metastable β-titanium alloy prepared in Comparative Example 1 has a yield strength of 520.93 MPa, a tensile strength of 749.99 MPa, and an elongation at break of 34.83%.

[0085] from Figure 12 As can be seen, the work hardening rate of the heterostructure metastable β titanium alloy prepared in Example 1 is significantly increased to 1800 MPa compared to 1250 MPa of the equiaxed structure (Comparative Example 1); the work hardening rate of the heterostructure metastable β titanium alloy prepared in Example 2 is increased to 1500 MPa compared to 1250 MPa of the equiaxed structure (Comparative Example 1).

[0086] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a high-performance metastable β titanium alloy with a heterogeneous structure capable of inducing deformation in a multi-stage and time sequence, characterized in that, The method comprises the following steps: (1) homogenizing the metastable β titanium alloy in the β single-phase region, and then cooling to room temperature in the furnace; (2) heating and hot-rolling the metastable β titanium alloy obtained in step (1) in the β phase region, and then heat preservation and water cooling after hot rolling; (3) cold rolling the plate obtained in step (2) to obtain a plate containing martensite and twin substructure; (4) short-time annealing the plate containing martensite and twin substructure obtained in step (3) in the β single-phase region to form a high-performance metastable β titanium alloy with a multi-level grain non-homogeneous lamellar heterogeneous structure.

2. The method of claim 1, wherein the method is characterized by: The homogenization treatment in step (1) is carried out at a temperature of 1000℃ for 1h.

3. The method of claim 1, wherein the method is characterized by: The heating in step (2) is carried out by heating the metastable β titanium alloy to 850℃ and heat preservation for 30min.

4. The method of claim 1, wherein the method is characterized by: The hot rolling in step (2) is carried out by hot rolling the alloy after heat treatment in a two-roller mill with a deformation amount of 15% per pass, and reheating and heat preservation for 5min after each hot rolling pass; the temperature is lowered to 800℃ for further hot rolling after the plate thickness is reduced to 10mm, and the total deformation amount of hot rolling is 82% until the plate thickness is 3mm; then water cooling after heat preservation at 800℃ for 5min.

5. The method of claim 1, wherein the method is characterized by: The cold rolling deformation in step (3) is carried out by cold rolling the plate from 3mm to 1mm with a total deformation amount of 60%.

6. The method of claim 1, wherein the method is characterized by: The short-time annealing in step (4) is carried out at a temperature of 770-780℃ for 5min.

7. A high performance metastable β titanium alloy produced by the method of any one of claims 1 to 6, characterized in that, The high-performance metastable β titanium alloy has a multi-level grain non-homogeneous lamellar heterogeneous structure, which is composed of coarse equiaxed grains, deformed recovery grains and fine recrystallized grains.

8. The high-performance metastable beta titanium alloy of claim 7, wherein, The average size of the coarse equiaxed grains is 31-48μm; the average size of the deformed recovery grains is 29-33μm; and the average size of the fine recrystallized grains is 3-3.5μm.

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