A method for preparing a dual-phase titanium alloy slab

Abstract

The invention relates to a preparation method of a dual-phase titanium alloy slab, comprising the following steps: ingot casting to obtain a first billet; performing 2-3 fire forging on the first billet above the phase transformation point of the titanium alloy to obtain a second billet; performing 2-4 fire forging on the second billet below the phase transformation point to obtain a third billet; performing 2-3 fire forging on the third billet below the phase transformation point to obtain a fourth billet; performing forming forging on the fourth billet below the phase transformation point to obtain a primary slab; performing heat treatment on the primary slab below the phase transformation point to obtain a secondary slab; and milling the secondary slab to obtain a target slab. The invention adopts a process mode combining multiple-pass repeated upsetting forging and heating treatment, so that the final slab obtained has a relatively uniform structure and fine grains. The ultrasonic flaw detection result of a plate rolled from the slab prepared by the invention can meet the requirements of AA grade in GB / T5193-2007.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy processing, and in particular to a method for preparing a dual-phase titanium alloy slab. Background Art

[0002] Titanium alloys are widely used in the aviation industry due to their excellent thermal strength and high specific strength. With the development of the aviation industry, there is an urgent need for titanium alloy medium and thick plates with high flaw detection levels. When preparing titanium alloy plates, the raw materials are first melted into ingots, then the ingots are forged into slabs, and finally the slabs are rolled to obtain plates.

[0003] The uniformity of the plate structure directly affects the flaw detection level of the plate, but the plate rolling process no longer plays a decisive role in adjusting the structure of the plate. In order to ensure the uniformity of the rolled plate structure, it is mainly necessary to improve the uniformity of the slab during the preparation process of the slab.

[0004] For dual-phase titanium alloys, the deformation in one direction is relatively large during rolling, and the original primary α phase in the alloy structure is elongated along the deformation direction to become a long strip of α phase. This long strip of α phase is directly reflected in the high noise level of the plate during the flaw detection process. However, due to the influence of the rolling processing method, it is difficult to change the problem of large deformation in one direction. Therefore, in the process of preparing slabs, it is necessary to refine the grains as much as possible and reduce the size of the primary α phase. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a method for preparing a dual-phase titanium alloy slab. The slab prepared by the method is rolled into a plate with uniform structure and an ultrasonic flaw detection level that meets standard requirements.

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

[0007] The present invention provides a method for preparing a dual-phase titanium alloy slab, comprising the following steps:

[0008] S1, ingot casting is opened to obtain the first billet;

[0009] S2, reforging the first billet 2-3 times above the phase transformation point of the titanium alloy to obtain a second billet;

[0010] S3, forging the second blank for 2 to 4 times below the phase transformation point to obtain a third blank;

[0011] S4, performing 2-3 fire forging on the third blank below the phase transformation point to obtain a fourth blank;

[0012] S5, forming and forging the fourth blank below the phase transformation point to obtain a primary slab;

[0013] S6, heat treating the primary slab below the phase transition point to obtain a secondary slab;

[0014] S7. Milling the secondary slab to obtain a target slab.

[0015] Preferably, in S1, the ingot is first heated to 800-900°C, kept warm for 60-120 min, and then heated to 100-200°C above the phase change point and kept warm. The holding time is calculated as 0.4-0.7 min / mm. The blanking is carried out according to the process flow of ingot drawing → upsetting → drawing → upsetting → drawing → air cooling.

[0016] Preferably, in S2, the process of each fire-forging is: first keep warm at 700-800°C for 60-120min, then heat up to 20°C-100°C above the phase change point and keep warm, the holding time is calculated as 0.4min / mm-0.7min / mm, and the forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0017] Preferably, in S3, the process of each fire-forging is: heating to 10°C to 30°C below the phase change point and keeping warm, the holding time is calculated according to 0.4min / mm to 0.7min / mm, and the forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0018] Preferably, in S4, the process of reforging after each fire is: heating to 30°C to 50°C below the phase change point and keeping warm, the holding time is calculated according to 0.4min / mm to 0.7min / mm, and reforging is performed according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0019] Preferably, in S5, the process of forming and forging the fourth blank comprises the following sub-steps:

[0020] S501, heating the fourth blank to 40°C to 50°C below the phase transformation point and keeping the temperature for a time calculated according to 0.4 min / mm to 0.7 min / mm, stretching the blank in the axial direction, and air cooling the blank after forging;

[0021] S502, heating the workpiece obtained in S501 to 40°C to 50°C below the phase transition point and maintaining the temperature for a time calculated according to 0.4 min / mm to 0.7 min / mm, forging the workpiece, and air cooling the workpiece after forging to obtain a primary slab;

[0022] Preferably, in S6, the heat treatment process is: heating to 20°C to 30°C below the phase transition point and keeping warm for a time calculated at 1.2 min / mm to 1.5 min / mm, and then air cooling.

[0023] Preferably, the height-to-diameter ratio during each upsetting process is 1:1.2 to 1:0.8, and the height-to-diameter ratio during each drawing process is 1.5:1 to 2.5:1.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The conventional process adopts only forging to prepare slabs. Due to the large difference between the thickness of the slab and the thickness of the billet, the slab is stretched in a single direction during the final fire forming. For the dual-phase titanium alloy, its grain direction is transiently elongated in the same direction, and is further elongated in the subsequent rolling process, thereby affecting the ultrasonic flaw detection level of the plate. The present invention adopts a process combining multi-pass repeated upsetting forging and heating treatment, which is different from the conventional process of preparing slabs by only forging. The original grains of the ingot are refined by multiple-pass repeated upsetting. After the forming is completed, the problem of excessive grain length in a single direction during the forming process is eliminated by heat treatment. The final slab structure is relatively uniform and the grains are fine. The ultrasonic flaw detection result of the plate rolled by the slab prepared by the present invention can meet the AA grade requirement in GB / T5193-2007. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a microstructure diagram of a plate rolled from the slab prepared in Example 1;

[0027] Figure 2 is a microstructure diagram of a plate rolled from the slab prepared in Example 2; DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] This embodiment provides a method for preparing a dual-phase titanium alloy slab, which is characterized by comprising the following steps:

[0031] S1. The ingot is first heated to 800°C, kept warm for 60 minutes, and then heated to 100°C above the phase change point and kept warm. The holding time is calculated as 0.4min / mm. The ingot is opened according to the process flow of ingot drawing → upsetting → drawing → upsetting → drawing → air cooling to obtain the first billet;

[0032] S2, performing two-time reforging on the first billet above the phase transformation point of the titanium alloy to obtain a second billet;

[0033] The process of the first fire-forging is: first keep the temperature at 700℃ for 60min, then heat it to 20℃ above the phase change point and keep it, the holding time is calculated as 0.4min / mm, and the forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling;

[0034] The process of the second fire-forging is: first keep the temperature at 750℃ for 100min, then heat it to 50℃ above the phase change point and keep it, the holding time is calculated as 0.6min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling;

[0035] S3, performing two-time forging on the second billet below the phase transformation point to obtain a third billet;

[0036] The process of the first fire-forging is: heating to 10℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.4min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0037] The process of the second fire forging is: heating to 15℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.5min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0038] S4, the third billet is subjected to two fire forgings below the phase transformation point to obtain a fourth billet; the process of the first fire forging is: heating to 30°C below the phase transformation point and keeping the temperature, the holding time is calculated according to 0.4min / mm, and the forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling;

[0039] The process of the second fire forging is: heating to 40℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.5min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0040] S5. Forming and forging the fourth blank below the phase transformation point to obtain a primary slab. The specific process of forming and forging is as follows:

[0041] S501, heating the fourth blank to 40°C below the phase transition point and keeping the temperature for a holding time of 0.4 min / mm, stretching the blank in the axial direction, and air cooling the blank after forging. In this embodiment, the size of the workpiece obtained in this step is 200 mm×600 mm×1100 mm;

[0042] S502, heating the workpiece obtained in S501 to 40°C below the phase transition point and keeping the temperature for a time calculated as 0.4 min / mm, forging the workpiece, and air cooling after forging to obtain a primary slab; in this embodiment, the size of the primary slab is 200 mm×600 mm×1100 mm;

[0043] S6. Heat-treating the primary slab below the phase transition point to obtain a secondary slab; the heat treatment process is: heating to 20°C below the phase transition point and keeping the temperature for a time calculated according to 1.2 min / mm to 1.5 min / mm, and then air cooling;

[0044] S7. Milling the secondary slab to obtain a target slab. In this embodiment, the size of the target slab is 100 mm×1000 mm×1000 mm.

[0045] Example 2

[0046] This embodiment provides a method for preparing a dual-phase titanium alloy slab, which is characterized by comprising the following steps:

[0047] S1. The ingot is first heated to 850°C, kept warm for 90 minutes, and then heated to 130°C above the phase change point and kept warm. The holding time is calculated as 0.5min / mm. The ingot is opened according to the process flow of ingot drawing → upsetting → drawing → upsetting → drawing → air cooling to obtain the first billet;

[0048] S2, performing three-times forging on the first billet above the phase transformation point of the titanium alloy to obtain a second billet;

[0049] The process of the first fire-forging is: first keep the temperature at 750℃ for 80min, then heat it to 100℃ above the phase change point and keep it. The holding time is calculated as 0.7min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0050] The process of the second fire forging is: first keep the temperature at 800℃ for 120min, then heat it to 100℃ above the phase change point and keep it, the holding time is calculated as 0.6min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling;

[0051] The process of the third fire forging is: first keep the temperature at 780℃ for 100min, then heat it to 80℃ above the phase change point and keep it, the holding time is calculated as 0.7min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling;

[0052] S3, performing two-time forging on the second billet below the phase transformation point to obtain a third billet;

[0053] The process of the first fire-forging is: heating to 30℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.7min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0054] The process of the second fire forging is: heating to 20℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.6min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0055] S4, the third billet is subjected to two fire forgings below the phase transformation point to obtain a fourth billet; the process of the first fire forging is: heating to 50°C below the phase transformation point and keeping the temperature, the holding time is calculated according to 0.7min / mm, and the forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling;

[0056] The process of the second fire forging is: heating to 40℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.5min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0057] S5. Forming and forging the fourth blank below the phase transformation point to obtain a primary slab. The specific process of forming and forging is as follows:

[0058] S501, heating the fourth blank to 50°C below the phase transition point and keeping the temperature for a holding time of 0.6 min / mm, stretching the blank in the axial direction, and air cooling the blank after forging. The workpiece size obtained in this step is 240 mm×600 mm×1100 mm;

[0059] S502, heating the workpiece obtained in S501 to 50°C below the phase transition point and keeping the temperature for a time calculated as 0.5 min / mm, forging the workpiece, and air cooling after forging to obtain a primary slab; in this embodiment, the size of the primary slab is 130 mm×1100 mm×1100 mm;

[0060] S6. Heat-treating the primary slab below the phase transition point to obtain a secondary slab; the heat treatment process is: heating to 30°C below the phase transition point and keeping the temperature for a time calculated at 1.5 min / mm, and then air cooling;

[0061] S7. Milling the secondary slab to obtain a target slab. In this embodiment, the size of the target slab is 100 mm×1000 mm×1000 mm.

[0062] Example 3

[0063] This embodiment provides a method for preparing a dual-phase titanium alloy slab, which is characterized by comprising the following steps:

[0064] S1. The ingot is first heated to 900°C, kept warm for 120 minutes, and then heated to 200°C above the phase change point and kept warm. The holding time is calculated according to 0.7min / mm. The ingot is opened according to the process flow of ingot drawing → upsetting → drawing → upsetting → drawing → air cooling to obtain the first billet;

[0065] S2, performing two-time reforging on the first billet above the phase transformation point of the titanium alloy to obtain a second billet;

[0066] The process of the first fire-forging is: first keep the temperature at 800℃ for 120min, then heat it to 80℃ above the phase change point and keep it. The holding time is calculated as 0.6min / mm, and the forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0067] The process of the second fire forging is: first keep the temperature at 730℃ for 100min, then heat it to 50℃ above the phase change point and keep it, the holding time is calculated as 0.4min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling;

[0068] S3, performing three-times forging on the second billet below the phase transformation point to obtain a third billet;

[0069] The process of the first fire-forging is: heating to 30℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.7min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0070] The process of the second fire forging is: heating to 20℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.5min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0071] The process of the third fire forging is: heating to 15℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.6min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0072] S4, the third billet is subjected to three-times forging below the phase transformation point to obtain a fourth billet; the process of the first forging is: heating to 35°C below the phase transformation point and keeping the temperature, the holding time is calculated according to 0.4min / mm, and the forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling;

[0073] The process of the second fire forging is: heating to 45℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.5min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0074] The process of the third fire forging is: heating to 40℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.7min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0075] S5. Forming and forging the fourth blank below the phase transformation point to obtain a primary slab. The specific process of forming and forging is as follows:

[0076] S501, heating the fourth blank to 45°C below the phase transition point and keeping the temperature for a holding time of 0.7 min / mm, stretching the blank in the axial direction, and air cooling the blank after forging. The workpiece size obtained in this step is: 260 mm × 700 mm × 1200 mm;

[0077] S502, heating the workpiece obtained in S501 to 46°C below the phase transition point and keeping the temperature for a time calculated as 0.7 min / mm, forging the workpiece, and air cooling after forging to obtain a primary slab; in this embodiment, the size of the primary slab is 150 mm×1200 mm×1200 mm;

[0078] S6, heat treating the primary slab below the phase transition point to obtain a secondary slab;

[0079] The heat treatment process is: heating to 25℃ below the phase change point and keeping the temperature for 1.3min / mm, and then air cooling;

[0080] S7. Milling the secondary slab to obtain a target slab. In this embodiment, the size of the target slab is 120 mm×1100 mm×1100 mm.

[0081] Example 4

[0082] This embodiment provides a method for preparing a dual-phase titanium alloy slab, which is characterized by comprising the following steps:

[0083] S1. The ingot is first heated to 870°C, kept warm for 110 minutes, and then heated to 180°C above the phase change point and kept warm. The holding time is calculated according to 0.6min / mm. The ingot is opened according to the process flow of ingot drawing → upsetting → drawing → upsetting → drawing → air cooling to obtain the first billet;

[0084] S2, performing two-time reforging on the first billet above the phase transformation point of the titanium alloy to obtain a second billet;

[0085] The process of the first fire-forging is: first keep the temperature at 760℃ for 100min, then heat it to 70℃ above the phase change point and keep it, the holding time is calculated as 0.5min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling;

[0086] The process of the second fire forging is: first keep the temperature at 710℃ for 70min, then heat it to 70℃ above the phase change point and keep it, the holding time is calculated as 0.4min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling;

[0087] S3, performing four-times forging on the second blank below the phase transformation point to obtain a third blank;

[0088] The process of the first fire-forging is: heating to 30℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.7min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0089] The process of the second fire forging is: heating to 28℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.4min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0090] The process of the third fire forging is: heating to 13℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.5min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0091] The process of the fourth fire-forging is: heating to 18°C ​​below the phase change point and keeping the temperature, the holding time is calculated as 0.6min / mm, and the forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling;

[0092] S4, performing two-time forging on the third blank below the phase transformation point to obtain a fourth blank;

[0093] The process of the first fire-forging is: heating to 33℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.4min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0094] The process of the second fire forging is: heating to 40℃ below the phase change point and keeping the temperature. The holding time is calculated as 0.7min / mm. The forging is carried out according to the process flow of upsetting → drawing → upsetting → drawing → air cooling.

[0095] S5. Forming and forging the fourth blank below the phase transformation point to obtain a primary slab. The specific process of forming and forging is as follows:

[0096] S501, heating the fourth blank to the phase transition point and keeping it at 43°C for a holding time of 0.5 min / mm, stretching it in the axial direction, and air cooling it after forging. The workpiece size obtained in this step is: 260 mm × 700 mm × 1200 mm;

[0097] S502, heating the workpiece obtained in S501 to 44°C below the phase transition point and keeping the temperature for a holding time of 0.7 min / mm, forging the workpiece, and air cooling the workpiece after forging to obtain a primary slab; in this embodiment, the size of the primary slab is 150 mm×1200 mm×1200 mm;

[0098] S6, heat treating the primary slab below the phase transition point to obtain a secondary slab;

[0099] The heat treatment process is as follows: heating to 24°C below the phase transition point, keeping the temperature for a time of 1.4 min / mm, and then air cooling;

[0100] S7. Milling the secondary slab to obtain a target slab. In this embodiment, the size of the target slab is 120 mm×1100 mm×1100 mm.

[0101] In the above embodiments, the height-to-diameter ratio is controlled within the range of 1:1.2 to 1:0.8 during each upsetting, and the height-to-diameter ratio is controlled within the range of 1.5:1 to 2.5:1 during each drawing.

[0102] In order to better explain the beneficial effects of the present invention, the slabs prepared in Examples 1 to 4 were respectively rolled into 30 mm thick plates. With reference to GB / T5193-2007, ultrasonic flaw detection tests were performed on the plates prepared from the slabs of each embodiment. The plates rolled from the slabs of Examples 1 to 4 all met the AA grade requirements. Figure 1 and Figure 2 It can also be seen that the internal structure of the board prepared by the present invention is relatively uniform.

[0103] The specific embodiments of the present invention enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0104] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a dual-phase titanium alloy slab, characterized in that: The following steps are involved: S1, ingot casting is opened to obtain the first billet; S2, reforging the first billet 2-3 times above the phase transformation point of the titanium alloy to obtain a second billet; S3, forging the second blank for 2 to 4 times below the phase transformation point to obtain a third blank; S4, performing 2-3 fire forging on the third blank below the phase transformation point to obtain a fourth blank; S5, forming and forging the fourth blank below the phase transformation point to obtain a primary slab; S6, heat treating the primary slab below the phase transition point to obtain a secondary slab; S7. Milling the secondary slab to obtain a target slab.

2. The method for preparing a dual-phase titanium alloy slab according to claim 1, characterized in that: In S1, the ingot is first heated to 800-900°C, kept warm for 60-120min, and then heated to 100-200°C above the phase change point and kept warm. The holding time is calculated according to 0.4-0.7min / mm. The ingot is opened according to the process flow of ingot drawing → upsetting → drawing → upsetting → drawing → air cooling.

3. The method for preparing a dual-phase titanium alloy slab according to claim 1, characterized in that: In S2, the process of each fire-to-forging is: first keep warm at 700-800℃ for 60-120min, then heat up to 20℃-100℃ above the phase change point and keep warm. The holding time is calculated as 0.4min / mm-0.7min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling.

4. The method for preparing a dual-phase titanium alloy slab according to claim 1, characterized in that: In S3, the process of each fire-to-forging is: heating to 10℃~30℃ below the phase change point and keeping warm, the holding time is calculated as 0.4min / mm~0.7min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling.

5. The method for preparing a dual-phase titanium alloy slab according to claim 1, characterized in that: In S4, the process of each fire-forging is: heating to 30℃~50℃ below the phase change point and keeping warm, the holding time is calculated as 0.4min / mm~0.7min / mm, and the forging is carried out according to the process flow of upsetting→drawing→upsetting→drawing→air cooling.

6. The method for preparing a dual-phase titanium alloy slab according to claim 1, characterized in that: In S5, the process of forming and forging the fourth blank includes the following sub-steps: S501, heating the fourth blank to 40°C to 50°C below the phase transformation point and keeping the temperature for a time calculated according to 0.4 min / mm to 0.7 min / mm, stretching the blank in the axial direction, and air cooling the blank after forging; S502, heating the workpiece obtained in S501 to 40°C to 50°C below the phase transformation point and keeping the temperature therefor for a time calculated as 0.4 min / mm to 0.7 min / mm, forging the workpiece, and air cooling the workpiece after forging to obtain a primary slab.

7. The method for preparing a dual-phase titanium alloy slab according to claim 1, characterized in that: In S6, the heat treatment process is: heating to 20°C to 30°C below the phase transition point and keeping warm for a time calculated at 1.2 min / mm to 1.5 min / mm, followed by air cooling.

8. The method for preparing a dual-phase titanium alloy slab according to any one of claims 3 to 5, characterized in that: The height-to-diameter ratio during each upsetting process is 1:1.2 to 1:0.8, and the height-to-diameter ratio during each drawing process is 1.5:1 to 2.5:1.

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