Symmetrical cold rolling preparation method of titanium alloy sheet

Abstract

The invention relates to the technical field of titanium alloy sheet preparation, and discloses a symmetrical cold rolling preparation method of a titanium alloy sheet, which comprises the following steps: preparing a blank, and carrying out multi-heating-number hot rolling on the blank to obtain a semi-finished sheet; the semi-finished plate is symmetrically arranged on a roller in the rolling direction, reverse symmetrical tension is applied to the two ends of the semi-finished plate through a clamp, and the tension on the two sides is symmetrically and progressively decreased based on the pass interval; symmetrical cold rolling is conducted on the semi-finished plate, and the deformation rate of the cold rolling process is controlled to be 0.6-0.85 time of the limit deformation rate of the plate; and the cold-rolled plate is subjected to roller hearth furnace annealing and press-straightening treatment, and a finished titanium alloy plate is obtained. Compared with a thin plate prepared through a traditional cold rolling process, the same plate difference of finished products is reduced by 58%, the problem that the thin plate is locally thick, especially the middle is thick is solved, the thickness precision qualification rate is high, and the requirement for the high-precision titanium alloy thin plate in the civil field is met.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy plate preparation, and in particular to a symmetrical cold rolling preparation method for a titanium alloy thin plate. Background Art

[0002] Titanium alloys are widely used in aerospace, military, chemical, nuclear power, marine and other fields due to their low density, high specific strength and excellent corrosion resistance. At the same time, with the annual reduction in the cost of titanium alloy preparation, the proportion of titanium plates and strips in the civilian field has gradually increased, especially in the fields of 3C, medical, tool making and leisure materials, which have grown rapidly in recent years. The requirements for titanium alloy materials in the civilian field are also getting higher and higher. For example, titanium alloy materials such as TC4 and TA4 used in the 3C field have special requirements for strength. If the strength is too high, the tool wear will increase. If the strength is too low, it will easily cause processing deformation and produce waste. For example, the thickness accuracy of TC4 thin plates for high-end decoration requires a positive tolerance of <0.05mm, so that it can be used as embedded plates. However, due to the high strength and high resilience of titanium alloys, the conventional cold rolling method has high requirements on the rolling mill capacity. In the production process, there are often many passes and they are not fixed. There are differences in the degree of work hardening, resulting in poor appearance accuracy of the plate, local out-of-tolerance problems occur from time to time, and batch stability cannot be guaranteed, which hinders the widespread promotion and application of titanium alloys in the civilian field.

[0003] Therefore, there is a need in the prior art for improving the symmetrical cold rolling preparation method of titanium alloy thin plates. Summary of the invention

[0004] In view of this, the purpose of the embodiment of the present invention is to propose a symmetrical cold rolling preparation method for titanium alloy thin plates, which solves the problems of high batch strength and local thickness of alloy thin plates, and obtains high-precision titanium alloy thin plates that meet the needs of civilian use.

[0005] Based on the above purpose, the embodiment of the present invention provides a symmetrical cold rolling preparation method for titanium alloy thin plates, S1 preparing a blank, and performing multiple hot rolling on the blank to obtain a semi-finished plate; S2 places the semi-finished plate on the roller symmetrically along the rolling direction, and applies reverse symmetrical tension to both ends of the semi-finished plate through a clamp, and the tension on both sides decreases symmetrically based on the pass interval; S3 symmetrically cold-rolls the semi-finished plate, and the deformation rate of the cold-rolling process is controlled to be 0.6~0.85 times the limit deformation rate of the plate; S4 performs roller hearth furnace annealing and press straightening treatment on the cold rolled plate to obtain a titanium alloy finished plate.

[0006] In some embodiments, in S1, the billet includes, by mass fraction, 5.5-6.2% Al, 4.0-4.3% V, 0.03-0.07% Fe, 0.03-0.07% O, and the balance Ti.

[0007] In some embodiments, in S1, by mass fraction, the thickness of the blank is 80-100 mm, the width is 550-650 mm, the length is 600-750 mm, and the thickness of the semi-finished plate is 3.0 mm-5.0 mm.

[0008] In some embodiments, in S2, the tension on both sides is set at a pass interval. Symmetrical decreasing.

[0009] In some embodiments, the single decrement value is 0.4-0.6 KN, the initial tension on one side is 22-26 KN, and the final tension on one side is 20-22 KN.

[0010] In some embodiments, in S3, the rolling pass The calculation formula for the cumulative cold deformation is distributed incrementally:

[0011] Average deformation rate per pass Take 2~7%, The value is 0~4.

[0012] In some embodiments, in S3, the marked plate is rolled to a symmetrical position before rolling. After each rolling pass is completed, the clamped plate is moved to a symmetrical position for the next rolling pass. The odd-numbered passes are rolled forward from the initial position along the positive X-axis, and the even-numbered passes are rolled reversely from the initial position along the negative X-axis.

[0013] In some embodiments, in S4, the roller hearth furnace annealing is performed in a stacking manner, with a titanium plate larger than the bottom surface area of ​​the titanium alloy finished plate placed at the bottom, the thickness of the pad plate being greater than 10 mm, and the number of plates in a single stack being less than 10 plates / stack.

[0014] In some embodiments, in S4, the annealing temperature is 820° C. to 840° C., and the holding time is 55 min to 60 min.

[0015] In some embodiments, in S4, the press-correction temperature is 620° C. to 640° C., and the press-correction time is 4 to 5 hours.

[0016] The present invention has at least the following beneficial technical effects: (1) The present invention reduces the requirements of the thin plate precision control on the rolling mill capacity through the symmetrical cold rolling preparation method with tension, and the range of the pass reduction rate is wider, and the deformation amount and the number of passes in the rolling process are standardized, so that the strength of the plate is within a controllable range, the surface work hardening is reduced, which is beneficial to the subsequent cutting processing in the civilian field and ensures the batch stability.

[0017] (2) Compared with the thin plates prepared by the traditional cold rolling process, the finished product difference is reduced by 58%, which solves the problem of local thickening of the thin plates, especially the thickening in the middle part. The thickness accuracy pass rate is high, which meets the demand for high-precision titanium alloy thin plates in the civilian field. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of an embodiment of a symmetrical cold rolling preparation method for a titanium alloy sheet provided by the present invention; Figure 2 A three-dimensional diagram of the initial placement position of the intercooler plate provided by the present invention; Figure 3 A front view of the initial placement position of the intercooler plate provided by the present invention; Figure 4 A schematic diagram of the measurement position of the same-plate difference of the middle plate provided by the present invention.

[0020] Description of reference numerals: 1. Rolling mill support roll; 2. Rolling mill working roll; 3. Cold rolled plate; 4. Clamp for applying tension. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0022] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0023] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] like Figure 1 The symmetrical cold rolling preparation method of the titanium alloy sheet provided by the present invention comprises the following steps: S1 prepares a blank, and performs multiple hot rolling on the blank to obtain a semi-finished plate; S2 places the semi-finished plate on the roller symmetrically along the rolling direction, and applies reverse symmetrical tension to both ends of the semi-finished plate through a clamp, and the tension on both sides decreases symmetrically based on the pass interval; S3 symmetrically cold-rolls the semi-finished plate, and the deformation rate of the cold-rolling process is controlled to be 0.6~0.85 times the limit deformation rate of the plate; S4 performs roller hearth furnace annealing and press straightening treatment on the cold rolled plate to obtain a titanium alloy finished plate.

[0025] Further, in S1, the billet includes, by mass fraction, Al: 5.5-6.2%, V: 4.0-4.3%, Fe: 0.03-0.07%, O: 0.03-0.07% and the balance Ti.

[0026] Further, in S1, by mass fraction, the thickness of the blank is 80-100 mm, the width is 550-650 mm, and the length is 600-750 mm of TC4 titanium alloy, and the thickness of the semi-finished plate is 3.0 mm-5.0 mm.

[0027] Furthermore, in S2, the tension on both sides is adjusted according to the pass interval. Symmetrical decrease. In some embodiments, the single decrease value is 0.4-0.6 KN, the initial tension on one side is 22-26 KN, and the final tension on one side is 20-22 KN.

[0028] Furthermore, in S3, the rolling pass The calculation formula for the cumulative cold deformation is distributed incrementally:

[0029] Average deformation rate per pass Take 2~7%, The value is 0~4.

[0030] Furthermore, in S3, the marked plate is rolled to a symmetrical position before rolling. After each rolling pass is completed, the clamped plate is moved to a symmetrical position for the next rolling pass. The odd-numbered passes are rolled forward from the initial position along the positive X-axis, and the even-numbered passes are rolled reversely from the initial position along the negative X-axis.

[0031] Furthermore, in S4, the roller hearth furnace annealing adopts stacking type, with a titanium plate larger than the bottom surface area of ​​the titanium alloy finished plate at the bottom, the thickness of the plate>10mm, and the number of plates in a single stack <10 pieces / stack. The annealing temperature is 820℃~840℃, and the holding time is 55min~60min. The press-correction temperature is 620℃~640℃, and the press-correction time is 4~5h.

[0032] The present invention reduces the requirements of the rolling mill capacity for the precision control of thin plates through a symmetrical cold rolling preparation method with tension, and has a wider range of pass reduction rate, which standardizes the deformation amount and the number of passes in the rolling process, so that the strength of the plate is within a controllable range, reduces surface work hardening, is conducive to subsequent cutting processing in the civilian field, and ensures batch stability. In addition, compared with the thin plates prepared by the traditional cold rolling process, the finished product difference of the present invention is reduced by 58%, which solves the problem of local thickening of the thin plate, especially the thickening in the middle part, and has a high thickness precision qualification rate, which meets the demand for high-precision titanium alloy thin plates in the civilian field.

[0033] The present invention will be further explained below in conjunction with specific embodiments.

[0034] Example 1 A symmetrical cold rolling preparation method for titanium alloy thin plates, characterized in that the titanium alloy sheet in this embodiment is a TC4 titanium alloy thin plate for 3C field, and the symmetrical cold rolling preparation method with tension can reduce the requirements of the thin plate precision control on the rolling mill capacity, and the pass reduction rate range is wider, so as to obtain a high-precision cold-rolled finished thin plate with a thickness specification of 3.0 mm. The steps of the symmetrical cold rolling preparation method are as follows: S1 prepares several blanks, TC4 titanium alloy with a size of 100mm (thickness) × 550mm (width) × 650mm (length), and performs multiple hot rolling to obtain semi-finished plates. The blank composition is composed of Al: 5.5-6.2%, V: 4.0-4.3%, Fe: 0.07%, O: 0.07% and the balance Ti in terms of mass percentage; the semi-finished plate has a specification of 4.0mm (thickness) × 1020mm (width) × 1700mm (length).

[0035] S2 further places the semi-finished plate in S1 on the roller symmetrically along the rolling direction, and the clamps at both ends apply oppositely symmetrical tensions. The tensions on both sides decrease three times according to the pass interval, and each time decreases by 0.5KN. The initial tension on one side is 23.5KN, and the tension on one side in the last pass is 22KN.

[0036] S3 Further, S2 rolling process The rolling deformation is 18. The rolling direction is forward for odd-numbered passes and reverse for even-numbered passes. After each rolling pass, the clamped plate is moved to a symmetrical position for the next rolling pass.

[0037] S4 further performs roller hearth furnace annealing and bell furnace press-correction treatment on the plate obtained after cold rolling in S3 to obtain a finished TC4 plate with a thickness of 3.0 mm. The roller hearth furnace annealing adopts a stacking type, with a titanium plate larger than the bottom surface area of ​​the finished product pad at the bottom, the pad thickness is 12 mm, 7 plates / stack, annealing temperature is 820°C~840°C, holding time is 55 min, and the press-correction temperature is 640°C, time is 4~5 h.

[0038] The room temperature yield strength of the TC4 cold-rolled titanium alloy plate prepared in this embodiment is 860-872 MPa, the tensile strength is 916-924 MPa, and the elongation is 16.5-17.5%.

[0039] Three TC4 cold-rolled titanium alloy plates prepared in this example were randomly selected for plate difference measurement. The thickness of the plates at different positions was measured by an ultrasonic thickness gauge. The measurement point positions were as follows: Figure 3 The results are shown in Table 1.

[0040] The TC4 titanium alloy plate prepared in this embodiment has moderate strength, and its yield strength is reduced by 20-30 MPa compared with that in comparative example 1. Its thickness precision is reduced by 58% compared with that in comparative example 1, and the product qualification rate is high, which meets the requirements of plate users for the performance and precision of titanium alloy thin plates.

[0041] Table 1 The measurement results of the plate difference in Example 1

[0042] Example 2 A symmetrical cold rolling preparation method for titanium alloy thin plates, characterized in that the titanium alloy plate in this embodiment is a TC4 titanium alloy thin plate used in the tool making field, and the symmetrical cold rolling preparation method with tension can reduce the requirements of the thin plate precision control on the rolling mill capacity, and the pass reduction rate range is wider, and a high-precision cold-rolled finished thin plate with a thickness of 2.5 mm is obtained. The steps of the symmetrical cold rolling preparation method are as follows: S1 prepares several blanks, TC4 titanium alloy with the size of 95mm (thickness) × 530mm (width) × 620mm (length), and performs multiple hot rolling to obtain semi-finished plates. The blank composition is composed of Al: 5.5-6.2%, V: 4.0-4.3%, Fe: 0.06%, O: 0.06% and the balance Ti in terms of mass percentage; the semi-finished plate specification is 3.4mm (thickness) × 1030mm (width) × 1700mm (length).

[0043] S2 further places the semi-finished plate in S1 on the roller symmetrically along the rolling direction, and the clamps at both ends apply oppositely symmetrical tensions. The tensions on both sides decrease three times according to the pass interval, and each time decreases by 0.5 KN. The initial tension on one side is 23.0 KN, and the tension on one side in the last pass is 21.5 KN.

[0044] S3 Further, S2 rolling process is 20, the rolling deformation The rolling direction is forward for odd-numbered passes and reverse for even-numbered passes. After each rolling pass, the clamped plate is moved to a symmetrical position for the next rolling pass.

[0045] S4 further performs roller hearth furnace annealing and bell furnace press-correction treatment on the plate obtained after cold rolling in S3 to obtain a finished TC4 plate with a thickness of 2.5 mm. The roller hearth furnace annealing adopts a stacking type, with a titanium plate larger than the bottom surface area of ​​the finished product pad at the bottom, the pad thickness is 12 mm, 8 plates per stack, annealing temperature is 820°C~840°C, holding time is 55 min, and the press-correction temperature is 640°C, and the time is 4~5 h.

[0046] The room temperature yield strength of the TC4 cold-rolled titanium alloy plate prepared in this embodiment is 880-886 MPa, the tensile strength is 935-945 MPa, and the elongation is 15.5-16.0%.

[0047] Three TC4 cold-rolled titanium alloy plates prepared in this example were randomly selected for plate difference measurement. The thickness of the plates at different positions was measured by an ultrasonic thickness gauge. The measurement point positions were as follows: Figure 3 The results are shown in Table 2.

[0048] Table 2 The measurement results of the plate difference in Example 2

[0049] Example 3 A symmetrical cold rolling preparation method for titanium alloy thin plates, characterized in that the titanium alloy sheet in this embodiment is a TC4 titanium alloy thin plate for high-end decoration field, and the symmetrical cold rolling preparation method with tension can reduce the requirements of the thin plate precision control on the rolling mill capacity, and the pass reduction rate range is wider, so as to obtain a high-precision cold-rolled finished thin plate with a thickness specification of 2.0 mm. The steps of the symmetrical cold rolling preparation method are as follows: S1 prepares several blanks, TC4 titanium alloy with the size of 90mm (thickness) × 540mm (width) × 600mm (length), and performs multiple hot rolling to obtain semi-finished plates. The blank composition is composed of Al: 5.5-6.2%, V: 4.0-4.3%, Fe: 0.05%, O: 0.05% and the balance Ti in terms of mass percentage; the semi-finished plate has the specifications of 2.7mm (thickness) × 1030mm (width) × 1700mm (length).

[0050] S2 further places the semi-finished plate in S1 on the roller symmetrically along the rolling direction, and the clamps at both ends apply oppositely symmetrical tensions. The tensions on both sides decrease three times according to the pass interval, and each time decreases by 0.5 KN. The initial tension on one side is 23.0 KN, and the tension on one side in the last pass is 21.5 KN.

[0051] S3 Further, S2 rolling process is 20, the rolling deformation It is 25.9%, the reduction rate of the 1st and 2nd passes is 2%, and the average reduction rate of the remaining passes is 3%. The rolling direction is forward for odd-numbered passes and reverse for even-numbered passes. After each rolling pass is completed, the clamped plate is moved to a symmetrical position for the next rolling pass.

[0052] S4 further performs roller hearth furnace annealing and bell furnace press-correction treatment on the plate obtained after cold rolling in S3 to obtain a finished TC4 plate with a thickness of 2.0 mm. The roller hearth furnace annealing adopts a stacking type, with a titanium plate larger than the bottom surface area of ​​the finished product pad at the bottom, the pad thickness is 12 mm, 9 plates per stack, the annealing temperature is 820°C to 840°C, the holding time is 55 minutes, and the press-correction temperature is 640°C for 4 to 5 hours.

[0053] The room temperature yield strength of the TC4 cold-rolled titanium alloy plate prepared in this embodiment is 925-930 MPa, the tensile strength is 975-986 MPa, and the elongation is 15.5-16.5%.

[0054] Table 3 The measurement results of the plate difference in Example 3

[0055] Comparative Example 1 Comparative Example 1 is a conventional method for cold rolling TC4 titanium alloy thin plates, the goal is to obtain a cold-rolled TC4 titanium alloy finished product with a thickness of 3.0 mm. The specific steps are as follows: The S1 slab material is prepared from the same batch and composition as in Example 1, and is made of TC4 titanium alloy with a size of 100 mm (thickness) × 550 mm (width) × 650 mm (length). It is hot-rolled for multiple times to obtain a semi-finished plate with a thickness of 4.0 mm.

[0056] S2 further cold-rolls the plate obtained in S1, with 9 rolling passes, a rolling deformation rate of 25%, a reduction rate of 2% in the 1st and 9th passes, and an average reduction rate of 4% in the remaining passes.

[0057] S3: Further, the plate obtained after cold rolling in S3 is subjected to the same roller hearth furnace annealing and bell furnace press straightening treatment as in Example 1 to obtain a finished product TC4 cold-rolled plate with a thickness of 3.0 mm.

[0058] The room temperature yield strength of the TC4 cold-rolled titanium alloy plate prepared in this comparative example is 890-897 MPa, the tensile strength is 944-956 MPa, and the elongation is 13.5-15.0%.

[0059] Three sheets of TC4 cold-rolled titanium alloy sheets prepared in this comparative example were randomly selected for same-sheet difference measurement. The thickness of the sheets at different positions was measured by an ultrasonic thickness gauge. The results are shown in Table 4.

[0060] The thickness of the TC4 cold-rolled titanium alloy plate prepared in this comparative example 1 is thick in the middle and thin on both sides, with a thickness difference of 0.12-0.13 mm for the same plate, which cannot meet the user's requirement for high precision of the plate.

[0061] Table 4 The measurement results of the same plate difference in comparative example 1

[0062] In summary, compared with conventional cold rolling methods, the method of the present invention pays more attention to the matching of plate thickness accuracy and moderate strength. With the assistance of belt tension, the cold rolling process is standardized, so that the stability of thin plate batches is guaranteed, and the product qualification rate is effectively improved.

[0063] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0064] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0065] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0066] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A symmetrical cold rolling preparation method for titanium alloy thin plate, characterized in that: include: S1 prepares a blank, and performs multiple hot rolling on the blank to obtain a semi-finished plate; S2: placing the semi-finished plate symmetrically on the roller along the rolling direction, applying reverse symmetrical tension to both ends of the semi-finished plate through a clamp, and the tension on both sides decreases symmetrically based on the pass interval; S3 symmetrically cold-rolls the semi-finished plate, and the deformation rate of the cold-rolling process is controlled to be 0.6 to 0.85 times the limit deformation rate of the plate; S4 performs roller hearth furnace annealing and press straightening treatment on the cold rolled plate to obtain a titanium alloy finished plate.

2. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 1, characterized in that: In S1, the blank includes, by mass fraction, 5.5-6.2% Al, 4.0-4.3% V, 0.03-0.07% Fe, 0.03-0.07% O and the balance Ti.

3. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 1, characterized in that: In S1, by mass fraction, the thickness of the blank is 80-100 mm, the width is 550-650 mm, and the length is 600-750 mm, and the thickness of the semi-finished plate is 3.0 mm-5.0 mm.

4. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 1, characterized in that: In S2, the tension on both sides is adjusted according to the pass interval Symmetrical decreasing.

5. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 4, characterized in that: The single decrement value is 0.4~0.6KN, the initial tension on one side is 22~26KN, and the final tension on one side is 20~22KN.

6. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 1, characterized in that: In S3, the rolling pass The calculation formula for the cumulative cold deformation is distributed incrementally: Average deformation rate per pass Take 2~7%, The value is 0~4.

7. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 1, characterized in that: In S3, the plate is marked before rolling and rolled to a symmetrical position. After each rolling pass is completed, the plate is clamped and moved to a symmetrical position for the next rolling pass. The odd-numbered passes are rolled forward from the initial position along the positive X-axis, and the even-numbered passes are rolled reversely from the initial position along the negative X-axis.

8. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 1, characterized in that: In S4, the roller hearth furnace annealing adopts a stacking type, with a titanium plate larger than the bottom surface area of ​​the titanium alloy finished plate placed at the bottom, the thickness of the pad plate being greater than 10 mm, and the number of plates in a single stack being less than 10 plates / stack.

9. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 1, characterized in that: In S4, the annealing temperature is 820°C~840°C, and the holding time is 55min~60min.

10. The symmetrical cold rolling preparation method of titanium alloy sheet according to claim 1, characterized in that: In S4, the press-correction temperature is 620°C~640°C, and the press-correction time is 4~5h.

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