Preparation method of high-uniformity TA31 titanium alloy thick plate

Abstract

The invention relates to the field of titanium and titanium alloy processing, and provides a preparation method of a high-uniformity TA31 titanium alloy thick plate, which comprises the steps of cast ingot preparation, plate blank size design, plate blank preparation, plate rolling, thermal correction and annealing, and surface treatment. Wherein the slab preparation comprises the following steps: cogging and forging: the heating temperature is 1150 DEG C, reversing upsetting and drawing are firstly carried out, and then secondary remelting and temperature compensation are carried out; intermediate forging is carried out, specifically, the heating temperature is T beta-(20-40) DEG C, reversing upsetting and drawing are carried out firstly, and then remelting and temperature supplementing are carried out twice; and forming and forging, wherein the heating temperature is T beta-(40-55) DEG C, shaping is conducted firstly, and then remelting and temperature supplementing are conducted. According to the preparation method, the high-uniformity TA31 titanium alloy thick plate with the thickness of 40-100 mm is obtained, meanwhile, the forging cost is reduced, and the production period is shortened.

Description

Technical Field

[0001] The present invention relates to the field of forging of titanium and titanium alloys, and in particular to a method for preparing a TA31 titanium alloy thick plate with high uniformity. Background Art

[0002] Titanium, with its excellent properties such as high specific strength, corrosion resistance, non-magnetic properties, and easy weldability, has been hailed as "the most promising metal material of the 21st century" and nicknamed "the marine metal." It is widely used in the marine and offshore sectors. With the introduction of the National Deep-Sea Science and Technology Strategy to 2025, titanium alloys are poised for significant new development opportunities in the marine and offshore sectors. Compared to TC4 titanium alloy, TA31 titanium alloy offers superior strength-toughness compatibility, weldability, and explosion resistance, making it a popular choice for load-bearing components such as pressure hulls, pressure piping, and fasteners.

[0003] In recent years, as marine equipment has progressed toward deeper and longer-range capabilities, the specifications and dimensions of TA31 titanium alloy base metal for structural applications have also gradually increased. This places extremely high demands on the strength, toughness, and uniformity of TA31 titanium alloy plate microstructure and performance. Especially for plates thicker than 40 mm, significant differences in stress states, heating, and cooling rates at different thicknesses and locations during the production process can easily lead to uneven alloy microstructure and performance, which is extremely detrimental to the service performance of the product. Therefore, the preparation of highly uniform TA31 titanium alloy thick plates is currently one of the key challenges in plate production.

[0004] The production process for TA31 titanium alloy thick plate primarily involves ingot melting, slab forging, plate rolling, and heat treatment. The slab, as the raw material for rolling, has a significant impact on the microstructure and performance characteristics of the resulting plate. This impact can be particularly pronounced for thicker plates, where deformation during the rolling process is relatively limited. Since the thickness of the slab is relatively large, usually more than 100mm, in order to obtain fine and uniform structure, the conventional practice is to increase the number of forging fires, which will lead to an increase in the number of grinding times between each fire, thereby significantly increasing material loss and production cycle; for example, the patent with application number CN201410142637.4 discloses a preparation method for STi80 two-phase titanium alloy slabs for ships, with fewer forging fires and insufficient deformation to obtain uniform and fine TA31 titanium alloy equiaxed structure slabs; the patent with application number CN202311397391.0 discloses a forging method for large-size Ti80 titanium alloy forging billets, with too many forging fires, resulting in too many surface grinding times in the intermediate fires, resulting in large material loss and long production cycle, and the use of water cooling for the third intermediate billet will significantly increase the difference in structure between the surface and the core and the risk of surface cracking.

[0005] While considerable research has been conducted in recent years on the rolling and heat treatment of TA31 titanium alloy plates, there are still some limitations for thicknesses above 40 mm. For example, patent application number CN201811582924.1 discloses a Ti80 medium-thick plate with high impact toughness, its preparation method, and its application, but the thickness is limited to thin plates of 10 to 24 mm and is not suitable for thick plates of 40 to 100 mm.

[0006] In summary, the preparation methods of TA31 titanium alloy plates in the prior art are unable to obtain highly uniform TA31 titanium alloy thick plates with a thickness of 40 to 100 mm while reducing forging costs and shortening production cycles.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The purpose of the present invention is to propose a method for preparing a high-uniformity TA31 titanium alloy thick plate, so as to solve the problem that the preparation methods of TA31 titanium alloy plates in the existing technology cannot achieve the goal of obtaining a high-uniformity TA31 titanium alloy thick plate with a thickness of 40 to 100 mm while reducing the forging cost and shortening the production cycle.

[0009] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0010] A method for preparing a high-uniformity TA31 titanium alloy thick plate, the preparation method comprising the following steps:

[0011] S1. Ingot preparation;

[0012] S2, slab size design;

[0013] S3. Slab preparation:

[0014] S4, plate rolling;

[0015] S5, thermal correction and annealing;

[0016] S6, surface treatment;

[0017] Wherein, step S3 includes the following steps:

[0018] S31. Open forging: Before opening the blank, the surface of the ingot is coated with anti-oxidation paint, the heating temperature is 1150℃, the time is counted after reaching the temperature, the thermal insulation coefficient is 1.2~1.5min / mm, the reverse upsetting is carried out first, and then the furnace is returned to the furnace for heating twice; the heating temperature of the first furnace is T β -(20~35)℃, the second heating temperature of the furnace is T β +(25~50)℃;

[0019] S32, intermediate forging: heating temperature T β -(20~40)℃, after reaching the temperature, the time is 0.8~1.0min / mm, first reverse upsetting and then reheating for 2 times; the heating temperature of the first reheating is T β -(20~40)℃, the second heating temperature for reheating is T β -(30~40)℃;

[0020] S33, Forming forging: Heating temperature T β -(40~55)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.8~1.0min / mm, perform shaping, and then return to the furnace for temperature replenishment, and finally prepare a TA31 titanium alloy slab with a thickness of 100~200mm.

[0021] Furthermore, in step S31, 1 to 2 reversing upsettings are performed, each upsetting deformation is 40 to 60%, and the blank is finally turned into an octagonal shape; the first reheating and heating specifically includes the following steps: the heating temperature T β -(20~35)℃, start timing after reaching temperature, keep the insulation coefficient at 0.3~0.5min / mm, perform 1~2 upsetting and drawing, each upsetting and drawing deformation is 30~40%, the blank is finally turned into an octagonal body, after forging, it is cooled to below 750℃ and then returned to the furnace for heating again; the second reheating specifically includes the following steps: the heating temperature T β +(25~50)℃, start timing after reaching temperature, thermal insulation coefficient 0.3~0.5min / mm, perform 1~2 upsetting and drawing, each upsetting and drawing deformation is 30~40%, and the blank is finally turned into an octagon.

[0022] Furthermore, in step S32, 1 to 2 reversing upsettings are performed, each upsetting deformation is 30 to 50%, and the blank is finally turned into an octagonal shape; the first reheating and heating specifically includes the following steps: the heating temperature T β -(20~40)℃, start timing after reaching temperature, keep the insulation coefficient at 0.3~0.5min / mm, perform 1~2 upsetting and drawing, each upsetting and drawing deformation is 30~40%, and the blank is finally turned into an octagonal shape; after forging, cool to below 750℃ and perform the second re-melting and heating; the second re-melting and heating specifically includes the following steps: the heating temperature T β -(30~40)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.3~0.5min / mm, and perform 1~2 upsetting and drawing, with each upsetting and drawing deformation of 30~40%, and the blank is finally turned into an octagon.

[0023] Furthermore, step S33 is specifically as follows: heating temperature T β-(40~55)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.8~1.0min / mm, and perform shaping, with a cumulative deformation of 40~60% during forming and forging; then return to the furnace for reheating, and each time the temperature of the billet is reheated, it is necessary to first reduce the temperature of the billet to below 750℃ and then return to the furnace, start timing after reaching temperature, with a thermal insulation coefficient of 0.3~0.5min / mm; and finally prepare a TA31 titanium alloy billet with a thickness of 100~200mm.

[0024] Furthermore, the blank is surface-polished between step S31 and step S32, and between step S32 and step S33.

[0025] Furthermore, step S4 is specifically as follows: the plate rolling includes one-fire rolling and two-fire rolling; before the first-fire rolling, the slab is welded and clad on the upper and lower surfaces, and then the slab is put into the furnace for heating, firstly heating to 800-850℃, with a thermal insulation coefficient of 0.4-0.8min / mm, and then continuing to heat T β -(20~35)℃, insulation coefficient 1.0~1.5min / mm; after the insulation is completed, the roller is quickly opened to the rolling mill for billet rolling, the deformation of each pass is between 10~20%, the deformation of the rolling process is 35~45%, and the final rolling temperature is ≥800℃; after the first heat rolling is completed, the width direction of the first heat plate is used as the length direction of the second heat rolling for reversing rolling; first heat the billet to 800~850℃, the insulation coefficient is 0.3~0.6min / mm, and then continue to heat T β -(40~60)℃, insulation coefficient 1.0~1.2min / mm; after the insulation is completed, the billet is taken out of the furnace and quickly driven to the rolling mill for second-fire rolling using a roller table. The deformation of each pass is between 8~12%, the deformation of the rolling process is 40~55%, and the final rolling temperature is ≥700℃.

[0026] Furthermore, step S1 includes the following steps:

[0027] S11, mixing titanium sponge, industrial-grade HZr-1 zirconium sponge, Al-Mo alloy, Al-Nb alloy, Ti-Fe alloy, aluminum beans and titanium dioxide in proportion, and pressing the mixture into an electrode block;

[0028] S12. Using non-tungsten plasma vacuum welding as the melting electrode, TA31 titanium alloy ingots are prepared after three times of vacuum consumable arc furnace melting, peeling, and cutting the riser thickness.

[0029] Furthermore, step S2 includes the following steps:

[0030] The slab thickness H is designed based on the finished plate, where the slab thickness H must meet the following requirements:

[0031] ε1=(H-h1) / H*100%,

[0032] ε2=(h1-h) / h1*100%,

[0033] In the formula, H is the thickness of the slab; h1 is the thickness after the first hot rolling, mm; h is the thickness of the finished plate, mm; ε1 is the deformation of the first hot rolling, which is controlled at 35% to 45%; ε2 is the deformation of the second hot rolling, which is controlled at 40% to 55%.

[0034] Furthermore, step S5 includes the following steps:

[0035] S51, thermal correction: the plate is heated to 800-850℃ in a heating furnace with a thermal insulation coefficient of 1.5-2.5min / mm, and mechanical hot pressing is used for correction;

[0036] S52, annealing: heating temperature T β -(10~20)℃, holding time 2.0~3.0min / mm, air cooling after taking out of the furnace.

[0037] Furthermore, step S6 specifically includes: removing surface oxidation and defects by machining or grinding and polishing to prepare a finished plate.

[0038] Compared with the prior art, the method for preparing a high-uniformity TA31 titanium alloy thick plate described in the present invention has the following beneficial effects:

[0039] First, the method for preparing a high-uniformity TA31 titanium alloy thick plate described in the present invention, step S1 significantly improves the composition uniformity, purity and comprehensive mechanical properties of the TA31 titanium alloy ingot through precise raw material ratios, innovative welding technology and multi-stage smelting treatment, while optimizing process efficiency and cost, laying a material foundation for subsequent processing. Step S2 significantly optimizes the processing efficiency, organizational uniformity and finished product quality of the TA31 titanium alloy plate through multi-fire deformation amount stage-by-stage control and scientific thickness design, while reducing process risks and costs. In the process of preparing the slab in step S3, the idea of ​​"temperature-controlled tempering" is innovatively adopted, and the principle of recrystallization and refinement of organization is fully utilized. On the basis of the "high-low-high" forging process, special deformation methods such as reversing upsetting and inverting are adopted, which not only prepares a high-uniformity equiaxed organization TA31 titanium alloy slab, but also reduces the number of surface grinding times, significantly shortens the production cycle, and reduces production costs. Step S4 weakens the anisotropy of the TA31 titanium alloy thick plate by designing and controlling "reversing rolling", "large deformation in fewer passes" and deformation in different directions. Step S5 combines the characteristics of the TA31 titanium alloy and the difficulty in controlling the shape of thick plates to design a process route of first "thermomechanical correction" and then "near phase transition point annealing". At the same time, by heating in stages and precisely controlling the holding time, it not only ensures the shape of the TA31 titanium alloy thick plate, but also improves the uniformity of the performance, and realizes the effective optimization and regulation of the performance. Step S6 systematically solves the three core problems of poor surface quality, large thickness tolerance and high cost of the TA31 titanium alloy thick plate through coordinated surface treatment of machining / polishing and precise thickness control, and at the same time achieves the preparation of TA31 titanium alloy thick plates with high surface quality, high thickness accuracy and low cost.

[0040] Second, the method for preparing a high-uniformity TA31 titanium alloy thick plate described in the present invention, steps S1 to S6 are interrelated, inseparable, and work together to prepare a high-uniformity TA31 titanium alloy thick plate with a thickness specification covering 40 to 100 mm. While ensuring high uniformity, it significantly shortens the production cycle and reduces production costs; at the same time, the mechanical properties of the high-uniformity TA31 titanium alloy thick plate in the transverse and longitudinal directions and different thickness layers of the surface and core can reach Rm≥880Mpa, Rp0.2≥780Mpa, A≥15%, impact energy KV2≥55J, and unevenness≤3mm / m.

[0041] Third, the method for preparing a high-uniformity TA31 titanium alloy thick plate described in the present invention uses conventional forging production equipment, has strong process applicability, and is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1This is a microstructure diagram of a TA31 titanium alloy slab prepared using the method for preparing a high-uniformity TA31 titanium alloy thick plate described in Example 1 of the present invention;

[0043] Figure 2 This is a microstructure diagram of a TA31 titanium alloy slab prepared using the method for preparing a high-uniformity TA31 titanium alloy thick plate described in Example 2 of the present invention;

[0044] Figure 3 This is a microstructure diagram of a TA31 titanium alloy slab prepared using the method for preparing a high-uniformity TA31 titanium alloy thick plate described in Example 3 of the present invention;

[0045] Figure 4 This is a microstructure diagram of a TA31 titanium alloy slab prepared by the method described in Comparative Example 1 of the present invention;

[0046] Figure 5 This is a microstructure diagram of a TA31 titanium alloy slab prepared by the method described in Comparative Example 2 of the present invention;

[0047] Figure 6 This is the microstructure diagram of the TA31 titanium alloy slab prepared by the method described in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0048] In order to make the technical means, objectives and effects of the present invention easier to understand, embodiments of the present invention are described in detail below with reference to specific figures.

[0049] It should be noted that all terms used in the present invention to indicate direction and position, such as "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "low", "lateral", "longitudinal", "center", etc., are only used to explain the relative position relationship and connection status between the components in a certain specific state (as shown in the accompanying drawings). They are only for the convenience of describing the present invention, and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0050] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical connections; direct connections or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0051] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0052] A method for preparing a high-uniformity TA31 titanium alloy thick plate, the preparation method comprising the following steps:

[0053] S1. Ingot preparation;

[0054] S2, slab size design;

[0055] S3. Slab preparation:

[0056] S4, plate rolling;

[0057] S5, thermal correction and annealing;

[0058] S6. Surface treatment.

[0059] Wherein, step S3 includes the following steps:

[0060] S31. Open forging: Before opening the blank, the surface of the ingot is coated with anti-oxidation paint, the heating temperature is 1150℃, the time is counted after reaching the temperature, the thermal insulation coefficient is 1.2~1.5min / mm, the reverse upsetting is carried out first, and then the furnace is returned to the furnace for heating twice; the heating temperature of the first furnace is T β -(20~35)℃, the second heating temperature of the furnace is T β +(25~50)℃;

[0061] S32, intermediate forging: heating temperature T β -(20~40)℃, after reaching the temperature, the time is 0.8~1.0min / mm, first perform 1~2 times of reversing upsetting, then perform 2 times of reheating; the heating temperature of the first reheating is T β -(20~40)℃, the second heating temperature for reheating is T β -(30~40)℃;

[0062] S33, Forming forging: Heating temperature T β-(40~55)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.8~1.0min / mm, and perform shaping, with a cumulative deformation of 40~60% during forming and forging; then return to the furnace for reheating, and each time the temperature of the billet is reheated, it is necessary to first reduce the temperature of the billet to below 750℃ and then return to the furnace, start timing after reaching temperature, with a thermal insulation coefficient of 0.3~0.5min / mm; and finally prepare a TA31 titanium alloy billet with a thickness of 100~200mm.

[0063] The step S1 of the present invention significantly improves the composition uniformity, purity and comprehensive mechanical properties of TA31 titanium alloy ingots through precise raw material ratios, innovative welding processes and multi-stage smelting treatments, while optimizing process efficiency and costs, laying a material foundation for subsequent processing. Step S2 significantly optimizes the processing efficiency, organizational uniformity and finished product quality of TA31 titanium alloy plates through multi-fire deformation control and scientific thickness design, while reducing process risks and costs. In the process of preparing the slab in step S3, according to the characteristics of TA31 titanium alloy and the principle of recrystallization structure refinement, at the phase transition point T β The above β single phase region and phase transition point T β The following (α+β) two-phase region is fully deformed, and the remelting and reheating reforging method is used to reduce the number of grinding times and greatly shorten the process flow. At the same time, special deformation methods such as reversing upsetting and inverting are used to effectively improve the uniformity of the organization and realize the preparation of uniform and fine equiaxed TA31 titanium alloy slabs; then through step S4 reversing rolling, step S5 heat treatment organization performance regulation and step S6 surface treatment, steps S1 to S6 are interrelated and inseparable, and work together to prepare a TA31 thick plate with high uniformity, whose mechanical properties of different thickness layers in the transverse and longitudinal directions and the surface core can reach Rm≥880Mpa, Rp0.2≥780Mpa, A≥15%, impact energy KV2≥55J, and unevenness ≤3mm / m. The thickness specifications can cover 40~100mm, and at the same time significantly shorten the production cycle and reduce the production cost.

[0064] Specifically, in step S31, one or two reversing upsettings are performed, each time with a deformation of 40-60%, and the blank is finally bent into an octagonal shape. After being bent into an octagonal shape, the edges and surface of the blank are more evenly stressed, further promoting uniform grain distribution and reducing the risk of cracking during subsequent forging.

[0065] The reversing upsetting and inverted octagonal process in step S31 significantly improves the uniformity and comprehensive performance of TA31 titanium alloy slabs by refining grains, eliminating defects, improving mechanical properties, and enhancing formability. It also reduces production costs and lays a solid foundation for subsequent forging and final product performance.

[0066] Specifically, in step S31, the first reheating and heating process includes the following steps: the heating temperature T β -(20~35)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.3~0.5min / mm, and perform 1~2 upsetting and drawing, with each upsetting and drawing deformation of 30~40%. The billet is finally poured into an octagonal shape, and after forging is completed, it is cooled to below 750℃ and returned to the furnace for reheating.

[0067] The first remelting and reheating process in step S31 achieves multiple goals of grain refinement, improved organizational uniformity, optimized mechanical properties and shortened production cycle through the synergistic effect of low-temperature short-time insulation, medium deformation upsetting and inversion, while taking into account low cost and environmental safety, providing reliable guarantee for the high-uniformity production of TA31 titanium alloy slabs.

[0068] Specifically, in step 3S1, the second reheating and heating process includes the following steps: the heating temperature T β +(25~50)℃, start timing after reaching temperature, thermal insulation coefficient 0.3~0.5min / mm, perform 1~2 upsetting and drawing, each upsetting and drawing deformation is 30~40%, and the blank is finally turned into an octagon.

[0069] The second remelting and reheating process in step S31 achieves multiple goals of grain refinement, improved organizational uniformity, optimized mechanical properties and shortened production cycle through the synergistic effect of high-temperature short-time insulation, medium deformation upsetting and inversion, while taking into account low cost and environmental safety, providing reliable guarantee for the high-uniformity production of TA31 titanium alloy slabs.

[0070] Specifically, in step S32, one or two reversing upsetting operations are performed, each with a deformation of 30% to 50%, and the blank is finally bent into an octagonal shape. This octagonal shape provides more uniform stress distribution on the blank's edges and surface, further promoting uniform grain distribution and reducing the risk of cracking during subsequent forging.

[0071] The reversing upsetting and inverted octagonal process in step S32 significantly improves the uniformity and comprehensive performance of TA31 titanium alloy slabs by refining grains, eliminating defects, improving mechanical properties, and enhancing formability. It also reduces production costs and lays a solid foundation for subsequent forging and final product performance.

[0072] Specifically, in step S32, the first reheating and heating process includes the following steps: the heating temperature T β -(20~40)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.3~0.5min / mm, and perform 1~2 upsetting and drawing, with each upsetting and drawing deformation of 30~40%. The billet is finally turned into an octagonal shape; after forging, it is cooled to below 750℃ and then returned to the furnace for the second reheating.

[0073] The first remelting and reheating process in step S32 achieves multiple goals of grain refinement, improved organizational uniformity, optimized mechanical properties and shortened production cycle through the synergistic effect of low-temperature short-time insulation, medium deformation upsetting and drawing, while taking into account low cost and environmental safety, providing reliable guarantee for the high-uniformity production of TA31 titanium alloy slabs.

[0074] Specifically, in step S32, the second reheating and heating process includes the following steps: the heating temperature T β -(30~40)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.3~0.5min / mm, and perform 1~2 upsetting and drawing, with each upsetting and drawing deformation of 30~40%, and the blank is finally turned into an octagon.

[0075] The second remelting and reheating process in step S32 achieves multiple goals of grain refinement, improved organizational uniformity, optimized mechanical properties and shortened production cycle through the synergistic effect of low-temperature short-time insulation, medium deformation upsetting and inversion, while taking into account low cost and environmental safety, providing reliable guarantee for the high-uniformity production of TA31 titanium alloy slabs.

[0076] Specifically, the surface of the blank is polished between step S31 and step S33. Surface polishing is a key step in ensuring product quality.

[0077] The blank is surface-grinded between step S31 and step S32, and between step S32 and step S33 to remove surface defects such as surface cracks and folds, wherein the ratio of the width to the depth of the grinding pit is ≥8:1.

[0078] By strictly controlling the width-to-depth ratio of the polished pits (≥8:1), surface defects can be effectively eliminated, organizational uniformity can be enhanced, the forging process can be optimized, and the mechanical properties of the material can be improved. At the same time, process stability and production efficiency can be improved, significantly shortening the production cycle and reducing production costs.

[0079] Specifically, step S1 includes the following steps:

[0080] S11, mixing 0# or above titanium sponge with a particle size of 3.0 to 12.7 mm, industrial-grade HZr-1 zirconium sponge with a particle size of 3.0 to 15 mm, Al-Mo alloy, Al-Nb alloy, Ti-Fe alloy, aluminum beans, and titanium dioxide according to proportion, and pressing the mixture into an electrode block;

[0081] S12. Using non-tungsten plasma vacuum welding as the melting electrode, TA31 titanium alloy ingots are prepared after three times of vacuum consumable arc furnace melting, peeling, and cutting the riser thickness.

[0082] Step S1 significantly improves the composition uniformity, purity and comprehensive mechanical properties of TA31 titanium alloy ingots through precise raw material ratios, innovative welding processes and multi-stage smelting treatments, while optimizing process efficiency and costs, laying a material foundation for subsequent processing.

[0083] Specifically, step S2 includes the following steps:

[0084] The slab thickness is designed according to the final product plate specifications, where the slab thickness H must meet the following requirements:

[0085] ε1=(H-h1) / H*100%,

[0086] ε2=(h1-h) / h1*100%,

[0087] In the formula, H is the thickness of the slab; h1 is the thickness after the first hot rolling, mm; h is the thickness of the finished plate, mm; ε1 is the deformation of the first hot rolling, which is controlled at 35% to 45%; ε2 is the deformation of the second hot rolling, which is controlled at 40% to 55%.

[0088] Step S2 significantly optimizes the processing efficiency, structural uniformity and finished product quality of TA31 titanium alloy plates through multi-fire deformation control in stages and scientific thickness design, while reducing process risks and costs.

[0089] Step S4 is specifically as follows: the plate rolling includes one-fire rolling and two-fire rolling; before the first-fire rolling, the slab is welded and clad on the upper and lower surfaces, and the cladding plate material is TA1 or TA2 pure titanium, and the cladding layer thickness is 0.7-1.3mm; then the slab is put into the furnace for heating. In order to avoid temperature difference, the temperature is first raised to 800-850℃, and the insulation coefficient is 0.4-0.8min / mm, and then the temperature is continued to rise T β -(20~35)℃, insulation coefficient 1.0~1.5min / mm. After the insulation is completed, the roller is quickly opened to the rolling mill for billet rolling. The idea of ​​"few passes and large deformation" is adopted. The deformation of each pass is between 10~20%, the deformation of the rolling process is 35~45%, and the final rolling temperature is ≥800℃; after the first heat rolling is completed, the width direction of the first heat plate is used as the length direction of the second heat rolling for reversing rolling; first heat the billet to 800~850℃, the insulation coefficient is 0.3~0.6min / mm, and then continue to heat T β -(40~60)℃, insulation coefficient 1.0~1.2min / mm; after the insulation is completed, the billet is taken out of the furnace and quickly driven to the rolling mill for second-heat rolling using a roller table, adopting the "few passes and large deformation" method, with the deformation amount of each pass being between 8% and 12%, the deformation amount of the rolling process being 40~55%, and the final rolling temperature being ≥700℃.

[0090] Step S4 achieves the preparation goals of high strength, high toughness, high uniformity and low defects of TA31 titanium alloy plates through the collaborative innovation of cladding welding-stage heating-reversing rolling, significantly improving the surface quality, structural uniformity, mechanical properties and processing efficiency of TA31 titanium alloy plates, while reducing process risks and energy consumption, and reducing process costs by more than 20%.

[0091] Specifically, in step S4, an intermediate grinding process is performed between the first and second hot rolling processes to remove surface oxidation and defects, wherein the grinding direction is parallel to the rolling direction of the next hot rolling process, that is, the grinding direction is parallel to the rolling direction of the second hot rolling process.

[0092] Specifically, step S5 includes the following steps:

[0093] S51. Thermal correction: As thick plates are difficult to correct, the plate is first heated to 800-850°C in a heating furnace with a thermal insulation coefficient of 1.5-2.5 min / mm. Mechanical hot pressing is used for correction. The unevenness after correction is ≤3 mm / m.

[0094] S52, annealing: heating temperature T β -(10~20)℃, holding time 2.0~3.0min / mm, air cooling after taking out of the furnace.

[0095] Step S5 systematically solves the three core problems of TA31 titanium alloy thick plates: poor flatness, high residual stress, and uneven structure, through the synergistic effect of thermal correction and sub-β phase annealing. At the same time, it increases production efficiency by more than 50% and reduces energy consumption by 20%.

[0096] Step S6 specifically includes: removing surface oxidation and defects by machining or grinding and polishing to prepare a finished plate with a thickness of 40 to 100 mm.

[0097] Step S6 systematically solves the three core problems of TA31 titanium alloy thick plates, namely poor surface quality, large thickness tolerance, and high cost, through coordinated surface treatment by machining / polishing and precise thickness control. At the same time, it achieves the preparation of TA31 titanium alloy thick plates with high surface quality, high thickness accuracy, and low cost.

[0098] The short process forging method of the high uniformity TA31 titanium alloy slab of the present invention is illustrated below by using specific embodiments:

[0099] Example 1

[0100] A method for preparing a high-uniformity TA31 titanium alloy thick plate comprises the following steps:

[0101] S1. Ingot preparation;

[0102] S2, slab size design;

[0103] S3. Slab preparation:

[0104] S4, plate rolling;

[0105] S5, thermal correction and annealing;

[0106] S6. Surface treatment.

[0107] Specifically, step S1 includes the following steps:

[0108] S11, mixing 0# or above titanium sponge with a particle size of 3.0 to 12.7 mm, industrial-grade HZr-1 zirconium sponge with a particle size of 3.0 to 15 mm, Al-Mo alloy, Al-Nb alloy, Ti-Fe alloy, aluminum beans, and titanium dioxide according to proportion, and pressing the mixture into an electrode block;

[0109] S12. Using non-tungsten plasma vacuum welding as the melting electrode, TA31 titanium alloy ingots are prepared after three times of vacuum consumable arc furnace melting, peeling, and cutting the riser thickness.

[0110] Specifically, step S2 includes the following steps:

[0111] The slab thickness dimensions are designed according to the final finished product plate specifications, where ε1 = 44.9%, ε2 = 54.4%, H = 165 mm, h1 = 91 mm, and h = 41 mm.

[0112] Wherein, step S3 includes the following steps:

[0113] S31. Open Forging: The measured phase transition point of the ingot is 1000°C. Before opening, the ingot surface is coated with an anti-oxidation coating. The heating temperature is 1150°C, and the time is started after reaching temperature. The thermal insulation coefficient is 1.2 min / mm. A reverse upsetting is performed first, with each upsetting deformation of 60%. The ingot is finally tilted into an octagon. After forging is completed, it is returned to the furnace for two reheating cycles. The first heating temperature is 980°C, and the time is started after reaching temperature. The thermal insulation coefficient is 0.3 min / mm. Two upsetting cycles are performed, with each upsetting deformation of 30%. The ingot is finally tilted into an octagon. After forging, it is cooled to below 750°C and returned to the furnace for another reheating cycle. The second heating temperature is 1050°C, and the time is started after reaching temperature. The thermal insulation coefficient is 0.3 min / mm. Two upsetting cycles are performed, with each upsetting deformation of 40%. The ingot is finally tilted into an octagon.

[0114] S32, Intermediate Forging: Heating temperature 980℃, timing after reaching temperature 1.0min / mm, perform two reversing upsettings, each upsetting deformation of 50%, and finally the billet is turned into an octagon. After forging, cool to below 750℃ and reheat twice. First heating temperature 970℃, timing after reaching temperature, holding coefficient 0.3min / mm, perform two upsettings, each upsetting deformation of 30%, and finally the billet is turned into an octagon. After forging, cool to below 750℃ and reheat for the second time. Second heating temperature 960℃, timing after reaching temperature, holding coefficient 0.3min / mm, perform one upsetting, each upsetting deformation of 30%, and finally the billet is turned into an octagon.

[0115] S33, forming and forging: heating temperature 960 ℃, timing after reaching temperature, thermal insulation coefficient 0.8min / mm, shaping, forming and forging cumulative deformation 60%, allowed to return to the furnace for reheating, each time the billet temperature must be lowered to below 750 ℃ ​​before returning to the furnace, timing after reaching temperature, thermal insulation coefficient 0.3min / mm, and finally prepared into 100mm thick TA31 titanium alloy slab.

[0116] Specifically, the blank is surface-polished between step S31 and step S32, and between step S32 and step S33 to remove surface defects such as surface cracks and folds, wherein the width:depth of the polished pits is ≥8:1.

[0117] Step S4 specifically involves: Plate rolling includes first-pass and second-pass rolling. Before first-pass rolling, the slab is welded and clad on the top and bottom surfaces. The cladding is made of TA1 pure titanium and has a thickness of 1.3mm. The slab is then heated in a furnace. To avoid temperature differences, the temperature is first raised to 800°C with a holding coefficient of 0.4 min / mm, and then further raised to 980°C with a holding coefficient of 1.0 min / mm. After the holding period, the roller table is quickly opened to the rolling mill for open rolling. Adopting the principle of "few passes, large deformation," the four rolling passes are 91mm long, with deformations of 12.1%, 17.2%, 14.2%, and 11.7% respectively, resulting in a total deformation of 44.9%. The final rolling temperature is 875°C. After the first-pass rolling is completed, the width of the first-pass plate is reversed, serving as the length direction for the second-pass rolling. The billet is first heated to 800°C with a holding coefficient of 0.3 min / mm, then heated to 960°C with a holding coefficient of 1.0 min / mm. After the holding period, the billet is removed from the furnace and quickly driven to the rolling mill via a roller table for secondary rolling. The "few passes, large deformation" method is adopted, with seven rolling passes totaling 41 mm. The deformation amounts of each pass are 10.0%, 10.5%, 11.0%, 10.9%, 10.4%, 10.7%, and 10.9%, respectively. The rolling process deformation amount is 54.4%, and the final rolling temperature is ≥755°C.

[0118] Specifically, in step S4, an intermediate grinding process is performed between the first and second hot rolling processes to remove surface oxidation and defects, wherein the grinding direction is parallel to the rolling direction of the next hot rolling process, that is, the grinding direction is parallel to the rolling direction of the second hot rolling process.

[0119] Specifically, step S5 includes the following steps:

[0120] S51. Thermal correction: As thick plates are difficult to correct, the plate is first heated to 800°C in a heating furnace with a thermal insulation coefficient of 1.5min / mm and corrected by mechanical hot pressing. The unevenness after correction is 3mm / m.

[0121] S52, annealing: heating temperature 980 ℃, holding time 2.0min / mm, air cooling after taking out of the furnace.

[0122] Step S6 specifically includes: removing surface oxidation and defects by machining or grinding and polishing to prepare a finished plate with a thickness of 40 mm.

[0123] Example 2

[0124] Different from Example 1, in this embodiment,

[0125] In step S2, ε1 = 40.9%, ε2 = 45.4%, H = 220 mm, h1 = 130 mm, h = 71 mm.

[0126] In step S31, the surface of the ingot is coated with anti-oxidation coating before being opened, the heating temperature is 1150°C, the time is counted after reaching the temperature, and the thermal insulation coefficient is 1.5min / mm.

[0127] In step S31, the second heating temperature for reheating is 1050°C, the time is counted after reaching the temperature, and the thermal insulation coefficient is 0.5min / mm.

[0128] In step S32, the second heating temperature for reheating is 960°C, the time is counted after reaching the temperature, and the thermal insulation coefficient is 0.5min / mm.

[0129] Step S33 is specifically as follows:

[0130] S33, forming and forging: heating temperature 960 ℃, timing after reaching temperature, thermal insulation coefficient 1.0min / mm, shaping, forming and forging cumulative deformation 60%, re-melting and reheating, each time the billet temperature must be lowered to below 750 ℃ ​​before re-melting, timing after reaching temperature, thermal insulation coefficient 0.5min / mm, and finally prepared into 160mm thick TA31 titanium alloy slab.

[0131] In step S4, the slab is welded and clad on the top and bottom surfaces before the first hot rolling. The cladding is made of TA2 pure titanium and has a thickness of 1.0 mm. The slab is then heated in a furnace. To avoid temperature differences, the temperature is initially raised to 850°C with a holding coefficient of 0.6 min / mm, followed by a further increase to 980°C with a holding coefficient of 1.2 min / mm. After the holding period, the slab is quickly moved to the rolling mill using a roller table for open rolling. Adopting the principle of "few passes, large deformation," the four rolling passes are 130 mm long, with deformations of 11.4%, 13.9%, 13.1%, and 11.0%, respectively, resulting in a total deformation of 40.9%. The final rolling temperature is 852°C. After the first hot rolling is completed, the width of the first hot slab serves as the length of the second hot rolling, and the slab is reversed. The slab is first heated to 850°C with a holding coefficient of 0.5 min / mm, followed by a further increase to 96°C with a holding coefficient of 1.2 min / mm. After the holding period, the billet is removed from the furnace and quickly transferred to the rolling mill via a roller table for secondary rolling. Using a "few passes, large deformation" approach, the rolling process is 71mm in six passes, with deformations of 10.0%, 10.3%, 11.4%, 9.1%, 8.6%, and 8.0% respectively. The rolling process deformation is 45.4%, and the final rolling temperature is ≥783°C.

[0132] Specifically, step S5 includes the following steps:

[0133] S51. Thermal correction: As thick plates are difficult to correct, the plate is first heated to 850°C in a heating furnace with a thermal insulation coefficient of 2 min / mm and corrected by mechanical hot pressing. The unevenness after correction is 3 mm / m.

[0134] S52, annealing: heating temperature 980 ℃, holding time 2.5min / mm, air cooling after taking out of the furnace.

[0135] Step S6 specifically includes: removing surface oxidation and defects by machining or grinding and polishing to prepare a finished plate with a thickness of 70 mm.

[0136] Example 3

[0137] Different from Example 1, in this embodiment,

[0138] In step S2, ε1 = 35.0%, ε2 = 40.2%, H = 260 mm, h1 = 169 mm, h = 101 mm.

[0139] In step S31, the phase transition point of the ingot is measured to be 995°C, the surface of the ingot is coated with anti-oxidation coating before being opened, the heating temperature is 1150°C, the time is counted after reaching the temperature, and the thermal insulation coefficient is 1.5min / mm.

[0140] In step S31, two reversing upsetting operations are performed, with each upsetting deformation amount being 30%.

[0141] In step S31, during the first reheating and heating process: the heating temperature of the first reheating and heating is 960°C, the time is counted after reaching the temperature, the thermal insulation coefficient is 0.5min / mm, and one upsetting is performed, and the deformation amount of each upsetting is 37%.

[0142] In step S31, during the second reheating and heating process: the heating temperature of the second reheating and heating is 1020°C, the time is counted after reaching the temperature, the thermal insulation coefficient is 0.5min / mm, and one upsetting is performed, and the deformation amount of each upsetting is 37%.

[0143] In step S32, the heating temperature is 960°C, and the time after reaching the temperature is 1.0 min / mm. First, two reversing upsettings are performed, and then two reheating and heating operations are performed.

[0144] In step S32, during the first reheating and reheating process: the heating temperature of the first reheating and reheating is 960°C, the time is counted after reaching the temperature, the thermal insulation coefficient is 0.5min / mm, and two upsettings are performed, with each upsetting deformation of 37%.

[0145] In step S32, during the second reheating and heating process: the heating temperature of the second reheating and heating is 950°C, the time is counted after reaching the temperature, the thermal insulation coefficient is 0.5min / mm, and one upsetting is performed, and the deformation amount of each upsetting is 37%.

[0146] Step S33 is specifically as follows:

[0147] S33, forming and forging: heating temperature 940 ℃, timing after reaching temperature, thermal insulation coefficient 0.8min / mm, shaping, forming and forging cumulative deformation 52%, re-melting and reheating, each time the billet temperature must be lowered to below 750 ℃ ​​before re-melting, timing after reaching temperature, thermal insulation coefficient 0.5min / mm, and finally prepared into 200mm thick TA31 titanium alloy slab.

[0148] Step S4 specifically involves: Before the first hot rolling, the slab is welded and clad on the top and bottom surfaces. The cladding is made of TA1 pure titanium and has a thickness of 0.7mm. The slab is then heated in a furnace. To avoid temperature differences, the temperature is first raised to 850°C with a holding coefficient of 0.8min / mm, and then further raised to 960°C with a holding coefficient of 1.5min / mm. After the holding period, the slab is quickly moved to the rolling mill using a roller table for open rolling. Adopting the principle of "few passes, large deformation," the three rolling passes are 169mm in length, with deformations of 11.5%, 17.4%, and 11.1% respectively, resulting in a rolling process deformation of 35.0%. The final rolling temperature is ≥882°C. After the first hot rolling is completed, the width of the first hot plate is reversed, serving as the length direction for the second hot rolling. The slab is first heated to 850°C with a holding coefficient of 0.6min / mm, and then further raised to 940°C with a holding coefficient of 1.2min / mm. After the insulation is complete, the billet is removed from the furnace and quickly transferred to the rolling mill via a roller table for secondary rolling. Adopting the "few passes, large deformation" approach, the five rolling passes are 101 mm in length, with deformations of 8.9%, 9.7%, 10.8%, 10.1%, and 9.4% respectively, resulting in a total rolling deformation of 40.2%. The final rolling temperature is ≥778°C.

[0149] Specifically, step S5 includes the following steps:

[0150] S51. Thermal correction: As thick plates are difficult to correct, the plate is first heated to 850°C in a heating furnace with a thermal insulation coefficient of 2.5min / mm and corrected by mechanical hot pressing. The unevenness after correction is 1mm / m.

[0151] S52, annealing: heating temperature 985 ℃, holding time 3.0min / mm, air cooling after taking out of the furnace.

[0152] Step S6 specifically includes: removing surface oxidation and defects by machining or grinding and polishing to prepare a finished plate with a thickness of 100 mm.

[0153] Comparative Example 1

[0154] Different from Example 1, in this comparative example,

[0155] The measured phase transition point of the ingot was 995°C. The ingot surface was coated with an anti-oxidation coating. The ingot was heated to 1150°C with a holding coefficient of 1.0 min / mm and subjected to two upsetting and drawing cycles. After air cooling to room temperature, the surface was polished. The second heating cycle was 1020°C with a holding coefficient of 0.8 min / mm, followed by intermediate surface polishing. The third heating cycle was 980°C with a holding coefficient of 0.8 min / mm, followed by forming and forging, ultimately producing a 165mm thick slab.

[0156] Comparative Example 2

[0157] Different from Example 1, in this comparative example,

[0158] The phase transformation point of TA31 titanium alloy ingot is measured to be 1002℃. The surface of the ingot is coated with anti-oxidation coating. The heating temperature of the blank is 1150℃, the thermal insulation coefficient is 0.8min / mm, and two upsettings are carried out. After air cooling to room temperature, the surface is polished. The second heating temperature is 1050℃, the thermal insulation coefficient is 0.8min / mm, and two upsettings are carried out. After air cooling to room temperature, the surface is polished. The third heating temperature is 980℃, the thermal insulation coefficient is 0.6min / mm, and two upsettings are carried out. After air cooling to room temperature, the surface is polished. The fourth heating temperature is 970℃, the thermal insulation coefficient is 0.6min / mm, and two upsettings are carried out. After air cooling to room temperature, the surface is polished. The fifth heating temperature is 960℃, the thermal insulation coefficient is 0.6min / mm, and the forming forging is prepared into a 200mm thick slab.

[0159] Comparative Example 3

[0160] Different from Example 1, in this comparative example,

[0161] Before slab opening, the ingot is coated with an anti-oxidation coating. The forging process is heated to 1150°C, followed by two upsetting passes, with a final forging temperature of 878°C. The ingot is then returned to the furnace for reheating and then forged again at 1050°C, followed by two upsetting passes, with a final forging temperature of 855°C. The intermediate forging process is heated to 980°C for the first forging pass, followed by two reversing upsetting passes, with a final forging temperature of 780°C. The ingot is then returned to the furnace for reheating and then forged again at 980°C, followed by two reversing upsetting passes, with a final forging temperature of 772°C. The forming forging process is heated to 960°C, with a final forging temperature of 757°C, resulting in a 260mm thick slab. After slab preparation, the slab undergoes a first widening and reversing rolling process to produce 90mm plate. The rolling process is heated to 980°C, with a holding coefficient of 1.3 min / mm. The deformation during the rolling process is 28% for widening and 37% for reversing. After rolling, heat treatment annealing is carried out with a heating temperature of 980°C and a holding time of 2.8 min / mm, and air cooling is performed after being taken out of the furnace.

[0162] Performance Testing

[0163] 1. The surface and core of the TA31 titanium alloy slabs prepared by the methods described in Examples 1 to 3 and Comparative Examples 1 to 3 were sampled and microstructured. Figures 1 to 6 .

[0164] Depend on Figures 1 to 6It can be seen that the TA31 titanium alloy slabs with a thickness of 100 to 200 mm prepared in Examples 1, 2, and 3 of the present invention have an ideal equiaxed structure, and the difference between the surface and core structures is small, and the structure is fine and uniform, which lays a good foundation for the preparation of plates with excellent comprehensive performance. However, due to the small number of fires below the phase transformation point and insufficient deformation, the final slab structure of Comparative Example 1 presents a typical Widmanstätten structure with a coarse structure, which is detrimental to the performance of the future plate; Comparative Example 2 uses 5 fires to prepare a near-equiaxed structure slab, which not only requires multiple surface grinding treatments in the middle and a long process flow, but also the primary α phase morphology of the surface and core is significantly different, the degree of equiaxed core is significantly higher than that of the surface, and the uniformity is poor, which may have an adverse effect on the uniformity of the future plate structure and performance. In addition, the plate finally prepared by using one fire unidirectional rolling shows obvious anisotropy. In comparison example 3, the deformation above and below the phase transformation point is not sufficient, and no reversing deformation is performed during the forging process, resulting in coarse and poorly uniform structure of the slab, which has an adverse effect on the uniformity of the future plate structure and performance. In addition, the rolling process adopts one-fire widening and reversing rolling forming, and the deformation in the original width direction is relatively small, and the degree of structure refinement is limited, resulting in obvious anisotropy and uneven performance distribution of the finished plate.

[0165] 2. The microstructure and properties of the TA31 titanium alloy slabs and plates prepared by the methods described in Examples 1 to 3 and Comparative Examples 1 to 3 were tested. The results are shown in Table 1.

[0166] Table 1 Performance comparison between comparative examples and examples

[0167]

[0168]

[0169] As can be seen from Table 1, compared with the comparative example, the TA31 thick plate prepared by the present invention has low anisotropy, high performance uniformity, good strength and toughness matching, and the mechanical properties of different thickness layers in the transverse and longitudinal directions as well as the surface and core can reach Rm≥880Mpa, Rp0.2≥780Mpa, A≥15%, impact energy KV2≥55J, and unevenness≤3mm / m, which solves the problem of uneven performance of TA31 titanium alloy thick plates.

[0170] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A method for preparing a high-uniformity TA31 titanium alloy thick plate, characterized in that: The preparation method comprises the following steps: S1. Ingot preparation; S2, slab size design; S3. Slab preparation: S4, plate rolling; S5, thermal correction and annealing; S6, surface treatment; Wherein, step S3 includes the following steps: S31. Open forging: Before opening the blank, the surface of the ingot is coated with anti-oxidation paint, the heating temperature is 1150℃, the time is counted after reaching the temperature, the thermal insulation coefficient is 1.2~1.5min / mm, the reverse upsetting is carried out first, and then the furnace is returned to the furnace for heating twice; the heating temperature of the first furnace is T β -(20~35)℃, the second heating temperature of the furnace is T β +(25~50)℃; S32, intermediate forging: heating temperature T β -(20~40)℃, after reaching the temperature, the time is 0.8~1.0min / mm, first reverse upsetting and then reheating for 2 times; the heating temperature of the first reheating is T β -(20~40)℃, the second heating temperature of the furnace is T β -(30~40)℃; S33, Forming forging: Heating temperature T β -(40~55)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.8~1.0min / mm, perform shaping, and then return to the furnace for temperature replenishment, and finally prepare a TA31 titanium alloy slab with a thickness of 100~200mm.

2. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: In step S31, 1 to 2 reversing upsettings are performed, with each upsetting deformation of 40 to 60%, and the blank is finally turned into an octagonal shape; the first reheating and heating specifically includes the following steps: the heating temperature T β -(20~35)℃, start timing after reaching temperature, keep the insulation coefficient at 0.3~0.5min / mm, perform 1~2 upsetting and drawing, each upsetting and drawing deformation is 30~40%, the blank is finally turned into an octagonal body, after forging, it is cooled to below 750℃ and then returned to the furnace for heating again; the second reheating specifically includes the following steps: the heating temperature T β +(25~50)℃, start timing after reaching temperature, thermal insulation coefficient 0.3~0.5min / mm, perform 1~2 upsetting and drawing, each upsetting and drawing deformation is 30~40%, and the blank is finally turned into an octagon.

3. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: In step S32, 1 to 2 reversing upsettings are performed, with each upsetting deformation of 30 to 50%, and the blank is finally turned into an octagonal shape; the first reheating and heating specifically includes the following steps: the heating temperature T β -(20~40)℃, start timing after reaching temperature, keep the insulation coefficient at 0.3~0.5min / mm, perform 1~2 upsetting and drawing, each upsetting and drawing deformation is 30~40%, and the blank is finally turned into an octagonal shape; after forging, cool to below 750℃ and perform the second re-melting and heating; the second re-melting and heating specifically includes the following steps: the heating temperature T β -(30~40)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.3~0.5min / mm, and perform 1~2 upsetting and drawing, with each upsetting and drawing deformation of 30~40%, and the blank is finally turned into an octagon.

4. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: Step S33 is specifically as follows: heating temperature T β -(40~55)℃, start timing after reaching temperature, with a thermal insulation coefficient of 0.8~1.0min / mm, and perform shaping, with a cumulative deformation of 40~60% during forming and forging; then return to the furnace for reheating, and each time the temperature of the billet is reheated, it is necessary to first reduce the temperature of the billet to below 750℃ and then return to the furnace, start timing after reaching temperature, with a thermal insulation coefficient of 0.3~0.5min / mm; and finally prepare a TA31 titanium alloy billet with a thickness of 100~200mm.

5. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: The surface of the blank is polished between step S31 and step S32, and between step S32 and step S33.

6. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: Step S4 is specifically as follows: the plate rolling includes one-fire rolling and two-fire rolling; before the first-fire rolling, the slab is welded and clad on the upper and lower surfaces, and then the slab is put into the furnace for heating, firstly heating to 800-850℃, with a thermal insulation coefficient of 0.4-0.8min / mm, and then continuing to heat T β -(20~35)℃, insulation coefficient 1.0~1.5min / mm; after the insulation is completed, the roller is quickly opened to the rolling mill for billet rolling, the deformation of each pass is between 10~20%, the deformation of the rolling process is 35~45%, and the final rolling temperature is ≥800℃; after the first heat rolling is completed, the width direction of the first heat plate is used as the length direction of the second heat rolling for reversing rolling; first heat the billet to 800~850℃, the insulation coefficient is 0.3~0.6min / mm, and then continue to heat T β -(40~60)℃, insulation coefficient 1.0~1.2min / mm; after the insulation is completed, the billet is taken out of the furnace and quickly driven to the rolling mill for second-fire rolling using a roller table. The deformation of each pass is between 8~12%, the deformation of the rolling process is 40~55%, and the final rolling temperature is ≥700℃.

7. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: Step S1 includes the following steps: S11, mixing titanium sponge, industrial-grade HZr-1 zirconium sponge, Al-Mo alloy, Al-Nb alloy, Ti-Fe alloy, aluminum beans and titanium dioxide in proportion, and pressing the mixture into an electrode block; S12. Using non-tungsten plasma vacuum welding as the melting electrode, TA31 titanium alloy ingots are prepared after three times of vacuum consumable arc furnace melting, peeling, and cutting the riser thickness.

8. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: Step S2 includes the following steps: The slab thickness H is designed based on the finished plate, where the slab thickness H must meet the following requirements: ε1=(H-h1) / H*100%, ε2=(h1-h) / h1*100%, In the formula, H is the thickness of the slab; h1 is the thickness after the first hot rolling, mm; h is the thickness of the finished plate, mm; ε1 is the deformation of the first hot rolling, which is controlled at 35% to 45%; ε2 is the deformation of the second hot rolling, which is controlled at 40% to 55%.

9. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: Step S5 includes the following steps: S51, thermal correction: the plate is heated to 800-850℃ in a heating furnace with a thermal insulation coefficient of 1.5-2.5min / mm, and mechanical hot pressing is used for correction; S52, annealing: heating temperature T β -(10~20)℃, holding time 2.0~3.0min / mm, air cooling after taking out of the furnace.

10. The method for preparing a high-uniformity TA31 titanium alloy thick plate according to claim 1, characterized in that: Step S6 specifically includes: removing surface oxidation and defects by machining or grinding and polishing to prepare a finished plate.

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