Preparation method of TC4 titanium alloy ring forging

Abstract

The invention relates to a preparation method of a TC4 titanium alloy ring forge piece, in particular to the field of titanium alloy ring forge pieces, which comprises the following steps: sequentially carrying out cast ingot cogging, forging, punching, chambering, rolling and annealing on a TC4 titanium alloy cast ingot to obtain the TC4 titanium alloy ring forge piece; the forging comprises first forging, second forging, third forging, fourth forging, heat treatment and upsetting treatment which are sequentially carried out; the radial growth speed of the ring is controlled to be 0.5-1 mm / s when rolling is started, and the radial growth speed of the ring is controlled to be 0.1-0.2 mm / s when the surface temperature of the blank is 750-850 DEG C. According to the preparation method provided by the invention, the preparation process is reasonably designed, so that a fine beta-phase transformation structure is obtained during rolling forming, the primary alpha-phase content is controlled to be 20-55% of a lamellar fine grain structure, the mechanical property of the obtained forge piece is improved, and the preparation method does not need equipment transformation and is suitable for large-scale production. And production and manufacturing can be completed by using existing equipment.

Description

Technical Field

[0001] The invention relates to the field of titanium alloy ring forgings, and in particular to a preparation method of a TC4 titanium alloy ring forging. Background Art

[0002] Super-large TC4 titanium alloy ring forgings are mainly used in marine equipment and aerospace fields, and are widely used in hull structural parts, offshore platform lifting devices, deep-sea pressure tanks, large pressure-bearing equipment, casings, etc.

[0003] Since TC4 titanium alloy is often used in key equipment structures and components in deep-sea engineering, it is often in a harsh environment of seawater corrosion during service. Connecting parts by welding will shorten the service life of the equipment and increase maintenance and repair costs. Therefore, some parts are designed as a whole to reduce the adverse effects of welds, including super-large TC4 titanium alloy ring forgings.

[0004] TC4 is an α+β type titanium alloy, which is widely used in the field of marine equipment due to its excellent corrosion resistance, high strength and light weight. Its smelting process and heat treatment process are relatively mature, but with the large-scale marine equipment, higher requirements are placed on the smelting and heat treatment process of large-scale raw materials. Therefore, in-depth research is needed, especially for aerospace, ship equipment, and deep-sea manned submarines, which have higher requirements on the comprehensive mechanical properties and uniformity of parts.

[0005] Although TC4 titanium alloy has good comprehensive mechanical properties, it is very difficult to produce this material in practice, especially for super-large forgings. On the one hand, the raw materials themselves have smelting difficulties and component segregation. This is because the temperature difference and cooling speed during smelting and casting lead to uneven distribution of Al and V elements in the alloy during the crystallization process. On the other hand, the ingot is prone to cracking and multiple firings during blanking, billet making and reforging. This is because the composition of the material determines that its forging temperature range is narrow, its cold work hardening tendency is obvious, and its deformation resistance is high. At the same time, the microstructure of this deformed titanium alloy needs to select a matching forging and forming process according to its different use requirements, so as to obtain a fine and uniform equiaxed structure or dual-state structure, and clear grains visible to the naked eye are not allowed.

[0006] Although the TC4 titanium alloy structure and properties can be adjusted through annealing or solution aging heat treatment, it is highly related to the material composition, organizational state and process requirements of the forging. At the same time, the performance of super-large TC4 ring forgings is unstable. This is because large-scale raw materials are prone to more serious segregation during smelting, and the control of inclusions also puts higher requirements on smelting. In the subsequent hot working process, the oxide film and α embrittlement layer are more likely to crack.

[0007] Although a lot of research has been done on the performance, structure, heat treatment, and hot processing of TC4 materials, there is little research on the production and application of ultra-large TC4 ring forgings in deep-sea engineering. At the same time, the obtained TC4 ring forgings still have problems with poor mechanical properties and structural uniformity. Summary of the invention

[0008] In view of the problems existing in the prior art, the object of the present invention is to provide a method for preparing a TC4 titanium alloy ring forging to solve the problem that the TC4 ring forging still has poor mechanical properties and organizational uniformity.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for preparing a TC4 titanium alloy ring forging, the preparation method comprising:

[0011] The TC4 titanium alloy ingot is subjected to ingot blanking, forging, punching, hole expansion, rolling and annealing in sequence to obtain a TC4 titanium alloy ring forging;

[0012] The forging includes first forging, second forging, third forging, fourth forging, heat treatment and roughening treatment performed in sequence; the preheating and heat preservation temperature of the first forging is 30-50°C higher than the β phase transformation temperature; the preheating and heat preservation temperature of the second forging is 30-50°C lower than the β phase transformation temperature; the preheating and heat preservation temperature of the third forging is 30-50°C higher than the β phase transformation temperature; the preheating and heat preservation temperature of the fourth forging is 30-50°C lower than the β phase transformation temperature;

[0013] At the beginning of the rolling, the radial growth rate of the control ring is 0.5-1 mm / s. When the surface temperature of the billet is 750-850° C., the radial growth rate of the control ring is 0.1-0.2 mm / s.

[0014] The preparation method provided by the present invention optimizes the crystal structure of the forging product by rationally designing the preparation process, so that a fine β phase transformation structure is obtained during rolling forming, and the primary α phase content is controlled within 20-55% of a lamellar fine grain structure, thereby improving the mechanical properties of the obtained forging. The preparation method does not require equipment modification and can be manufactured using existing equipment, thereby solving the problem of manufacturing super-large TC4 titanium alloy ring forgings and meeting strength requirements, with stable and reliable quality, and meeting the technical requirements of marine engineering equipment parts.

[0015] As a preferred technical solution of the present invention, the initial forging temperature of the forging blank is 120-150°C higher than the β phase transformation temperature.

[0016] Preferably, the final forging temperature of the forging blank is ≥800°C.

[0017] Preferably, the cross-sectional size of the raw material in the forging blank is ≤250 mm, and the heating includes: keeping the temperature 130-140° C. higher than the β phase transformation temperature for t=(0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material.

[0018] Preferably, if the cross-sectional size of the raw material in the forging blank is greater than 250 mm, the heating includes: keeping the temperature at 640-660°C for t=(0.3-0.45 min / mm)×T, then keeping the temperature at 130-140°C higher than the β phase transformation temperature for t=(0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material.

[0019] Preferably, the forging method includes drawing.

[0020] Preferably, the single pressing amount of the forging blank is controlled to be 30-40 mm.

[0021] Preferably, the total reduction amount of the forging process is controlled to be 90-110 mm.

[0022] As a preferred technical solution of the present invention, the first forging includes: upsetting and drawing performed sequentially at least twice.

[0023] Preferably, the preheating and holding time of the first forging is (0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material.

[0024] Preferably, the deformation amounts in the upsetting and the drawing in the first forging are independently controlled to be 40-50%.

[0025] Preferably, the upsetting ratio in the first forging is ≥1.8.

[0026] Preferably, the drawing ratio in the first forging is ≥1.8.

[0027] As a preferred technical solution of the present invention, the second forging includes: at least one sequential upsetting and drawing.

[0028] Preferably, the preheating and holding time of the second forging is (0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material.

[0029] Preferably, the deformation amounts in the upsetting and the drawing in the second forging are independently controlled to be 45-55%.

[0030] Preferably, the upsetting ratio in the second forging is ≥1.8.

[0031] Preferably, the drawing ratio in the second forging is ≥1.8.

[0032] As a preferred technical solution of the present invention, the third forging includes: upsetting and drawing performed sequentially at least twice.

[0033] Preferably, the preheating and holding time of the third forging is (0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material.

[0034] Preferably, the deformation amounts in the upsetting and the drawing in the third forging are independently controlled to be 40-50%.

[0035] Preferably, the upsetting ratio in the third forging is ≥1.8.

[0036] Preferably, the drawing ratio in the third forging is ≥1.8.

[0037] As a preferred technical solution of the present invention, the fourth forging includes: upsetting and drawing performed sequentially at least twice.

[0038] Preferably, the preheating and holding time of the fourth forging is (0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material.

[0039] Preferably, the deformation amounts in upsetting and drawing in the fourth forging are independently controlled to be 45-55%.

[0040] Preferably, the upsetting ratio in the fourth forging is ≥1.8.

[0041] Preferably, the drawing ratio in the fourth forging is ≥1.8.

[0042] As a preferred technical solution of the present invention, the total forging ratio of the first forging, the second forging, the third forging and the fourth forging is ≥12.6.

[0043] Preferably, the heat treatment includes solution-aging treatment or heat-insulating-cooling treatment.

[0044] Preferably, the heat preservation-cooling treatment comprises: heat preservation at 20-40° C. below the β-phase transition temperature for 50-80 minutes, and then cooling.

[0045] Preferably, the cooling rate of the cooling is greater than or equal to the cooling rate of air cooling.

[0046] As a preferred technical solution of the present invention, the heating temperature of the roughening treatment is 45-50° C. lower than the β phase transition temperature.

[0047] Preferably, the deformation amount is controlled to be 45-55% during the roughening process.

[0048] As a preferred technical solution of the present invention, the starting rolling temperature is 50-70°C lower than the β phase transformation temperature; and the final rolling temperature is 650-750°C.

[0049] Preferably, the rolled final billet is air-cooled to 420-460° C. and then air-cooled.

[0050] As a preferred technical solution of the present invention, the annealing temperature is 710-780°C.

[0051] Preferably, the annealing holding time is (0.6-0.8 mm / min)×fT+1.5h, where fT is the equivalent thickness of the TC4 ring forging.

[0052] Preferably, the cooling method of the annealing includes air cooling.

[0053] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0054] (1) The preparation method provided by the present invention can be easily controlled on site in the workshop by refining the key points of forging heating, billet making requirements and ring rolling control, and has reliable quality stability, thereby avoiding rework due to unqualified tissues caused by insufficient forging, improving the turnover rate of equipment, and shortening the product production cycle and manufacturing cost.

[0055] (2) The preparation method provided by the present invention adjusts the structure by controlling the rolling speed, the final rolling temperature and the cooling rate after the ring rolling. After the body is sampled, the performance is all qualified, which can effectively solve the mechanical property problem of this type of material, avoid the loss of product rework or even scrapping due to unqualified strength, and save production costs. The tensile strength of the obtained product is ≥895MPa, the yield strength is ≥825MPa, the elongation is ≥10%, the cross-sectional shrinkage is ≥25%, and the impact energy is ≥35Akv / J. Under the preferred embodiment, the tensile strength of the obtained product is ≥928MPa, the yield strength is ≥877MPa, the elongation is ≥14%, the cross-sectional shrinkage is ≥39%, and the impact energy is ≥37Akv / J.

[0056] (3) Since there is a large price gap between ingots and forged bars in the market, the price difference can generally reach RMB 100 / kg. The preparation method provided by the present invention greatly saves the procurement cost of raw materials and enhances the company's competitiveness in the market by exploring, optimizing and solidifying the ingot blanking, blank making and forging processes.

[0057] (4) The preparation method provided by the present invention is scientific and reasonable, with stable quality. It has been verified by engineering application practice that the product one-time inspection rate is increased by 100%, which is conducive to ensuring the stability of the preparation process. DETAILED DESCRIPTION

[0058] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0059] This embodiment provides a method for preparing a TC4 titanium alloy ring forging, the preparation method comprising:

[0060] The TC4 titanium alloy ingot is subjected to ingot blanking, forging, punching, hole expansion, rolling and annealing in sequence to obtain a TC4 titanium alloy ring forging;

[0061] In the present invention, the TC4 titanium alloy ingot used can be a commercially available ingot product having a composition conforming to GJB2744A-2007 and a composition deviation according to GB / T 3620.2, or a TC4 titanium alloy ingot obtained according to a preparation process known in the art.

[0062] In the present invention, TC4 titanium alloy ring forgings refer to forgings with a cross-sectional thickness ≥60mm and / or an inner diameter ≥2000mm. Based on the knowledge in the art, it is known that the larger the size of the forging, the greater the forging difficulty, that is, the scheme of the present invention does not exclude the possibility of processing small ring forgings.

[0063] Among them, the initial forging temperature of the forging blank is 120-150°C higher than the β phase transformation temperature, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C, 136°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C or 150°C, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0064] In the present invention, the β-phase transition temperature refers to the temperature at which the titanium alloy transforms from the α-phase to the β-phase. Exemplarily, it can be obtained by testing the TC4 titanium alloy used according to GB / T 23605-2020, or by other relevant testing methods disclosed in the art, thereby obtaining the solution provided by the present invention.

[0065] Among them, the final forging temperature of the forging blank is ≥800℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃ or 1000℃, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0066] Wherein, the cross-sectional size of the raw material in the forging blank is ≤250mm, and the heating includes: keeping the temperature 130-140°C higher than the β phase transformation temperature for t=(0.6-0.8min / mm)×T, where T is the equivalent thickness of the raw material.

[0067] In the present invention, the equivalent thickness T of the raw material refers to the case where the wall thicknesses of different parts of the workpiece are different. If the heating time is determined according to the wall thickness at a certain location to ensure the heat treatment quality, then the wall thickness at that location is called the effective thickness of the workpiece, such as the maximum inner diameter of the resulting ring forging product.

[0068] Among them, if the cross-sectional size of the raw material in the forging blank is ≤250mm, the heating includes: keeping the temperature at 130-140°C higher than the β phase transformation temperature, for example, it can be 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C or 140°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0069] Among them, if the cross-sectional size of the raw material in the forging blank is greater than 250mm, the heating includes: keeping the temperature at 640-660°C, keeping the temperature at t=(0.3-0.45min / mm)×T, and then keeping the temperature at 130-140°C higher than the β phase transformation temperature for t=(0.6-0.8min / mm)×T, where T is the equivalent thickness of the raw material.

[0070] Among them, if the cross-sectional size of the raw material in the forging blank is greater than 250mm, the heating includes: keeping the temperature at 640-660℃, for example, it can be 640℃, 642℃, 644℃, 646℃, 648℃, 650℃, 652℃, 654℃, 656℃, 658℃ or 660℃, etc., but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0071] Among them, the cross-sectional size of the raw material in the forging blank is greater than 250mm, and the insulation temperature during heating is 130-140°C higher than the β phase transformation temperature, for example, it can be 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C or 140°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0072] Wherein, the forging blanking method includes drawing.

[0073] Among them, the single pressing amount of the forging blank is controlled to be 30-40mm, for example, it can be 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, 36mm, 37mm, 38mm, 39mm or 40mm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0074] Among them, the total reduction amount of the forging blank is controlled to be 90-110mm, for example, it can be 90mm, 92mm, 94mm, 96mm, 98mm, 100mm, 102mm, 104mm, 106mm, 108mm or 110mm, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0075] In the present invention, the forging process is completed in one firing. If the surface of the blank is cracked after the blank is forged, the defects are removed by grinding or turning.

[0076] In the present invention, before the cold material is heated during forging, a glass protective lubricant can be applied to the surface of the blank to prevent oxygen from slowly diffusing into the matrix, forming an α hard and brittle layer, reducing the plasticity of the blank, and increasing the degree of cracking of the blank. At the same time, before the blank is transferred to the workbench, the production tooling should be preheated, and the surface where the blank contacts the tooling should be coated with thermal insulation asbestos to reduce the temperature drop of the blank when it is transferred from the forging heating furnace to the workbench, improve the plasticity of the blank, and reduce the deformation resistance of the material. The surface temperature of the tooling is controlled at 250-350℃ to reduce the temperature difference between the blank and the tooling, and reduce the degree of cracking of the blank caused by the rapid temperature drop where the blank contacts the hammer anvil.

[0077] The forging includes first forging, second forging, third forging, fourth forging, heat treatment and roughening treatment performed in sequence.

[0078] Wherein, the first forging includes: upsetting and drawing performed sequentially at least twice.

[0079] Among them, the preheating and holding temperature of the first forging is 30-50°C higher than the β phase transformation temperature, for example, it can be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0080] Among them, the preheating and holding time of the first forging is (0.6-0.8min / mm)×T, T is the equivalent thickness of the raw material, for example, it can be 0.6min / mm, 0.62min / mm, 0.64min / mm, 0.66min / mm, 0.68min / mm, 0.7min / mm, 0.72min / mm, 0.74min / mm, 0.76min / mm, 0.78min / mm or 0.8min / mm, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0081] Among them, the deformation amount in the upsetting and drawing in the first forging is independently controlled to be 40-50%, for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58% or 60%, etc., but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0082] Among them, the upsetting ratio in the first forging is ≥1.8, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0083] Among them, the drawing ratio in the first forging is ≥1.8, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0084] In the present invention, if the first forging is not completed in one firing, it is allowed to be returned to the furnace while hot, and the return and heat preservation time is selected according to (0.3-0.4min / mm)×T, where T is the equivalent thickness of the raw material.

[0085] Wherein, the second forging includes: at least one sequential upsetting and drawing.

[0086] Among them, the preheating and holding temperature of the second forging is 30-50°C lower than the β phase transformation temperature, for example, it can be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0087] Among them, the preheating and holding time of the second forging is (0.6-0.8min / mm)×T, T is the equivalent thickness of the raw material, for example, it can be 0.6min / mm, 0.62min / mm, 0.64min / mm, 0.66min / mm, 0.68min / mm, 0.7min / mm, 0.72min / mm, 0.74min / mm, 0.76min / mm, 0.78min / mm or 0.8min / mm, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0088] Among them, the deformation amounts in the upsetting and the drawing in the second forging are independently controlled to be 45-55%, for example, it can be 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54% or 55%, etc., but are not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0089] Among them, the upsetting ratio in the second forging is ≥1.8, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0090] Among them, the drawing ratio in the second forging is ≥1.8, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0091] In the present invention, if the second forging is not completed in one firing, it is allowed to be returned to the furnace while hot, and the return and heat preservation time is selected according to (0.3-0.4min / mm)×T, where T is the equivalent thickness of the raw material.

[0092] The third forging includes: upsetting and stretching performed sequentially at least twice.

[0093] Among them, the preheating and holding temperature of the third forging is 30-50°C higher than the β phase transformation temperature, for example, it can be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0094] Among them, the preheating and holding time of the third forging is (0.6-0.8min / mm)×T, T is the equivalent thickness of the raw material, for example, it can be 0.6min / mm, 0.62min / mm, 0.64min / mm, 0.66min / mm, 0.68min / mm, 0.7min / mm, 0.72min / mm, 0.74min / mm, 0.76min / mm, 0.78min / mm or 0.8min / mm, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0095] Among them, the deformation amount in the upsetting and drawing in the third forging is independently controlled to be 40-50%, for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58% or 60%, etc., but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0096] Among them, the upsetting ratio in the third forging is ≥1.8, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0097] Among them, the drawing ratio in the third forging is ≥1.8, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0098] In the present invention, if the third forging is not completed in one firing, it is allowed to be returned to the furnace while hot, and the return and heat preservation time is selected according to (0.3-0.4min / mm)×T, where T is the equivalent thickness of the raw material.

[0099] Wherein, the fourth forging includes: upsetting and drawing performed sequentially at least twice.

[0100] Among them, the preheating and holding temperature of the fourth forging is 30-50°C lower than the β phase transformation temperature, for example, it can be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0101] Among them, the preheating and holding time of the fourth forging is (0.6-0.8min / mm)×T, T is the equivalent thickness of the raw material, for example, it can be 0.6min / mm, 0.62min / mm, 0.64min / mm, 0.66min / mm, 0.68min / mm, 0.7min / mm, 0.72min / mm, 0.74min / mm, 0.76min / mm, 0.78min / mm or 0.8min / mm, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0102] Among them, the deformation amount in the upsetting and drawing in the fourth forging is independently controlled to be 45-55%, for example, it can be 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54% or 55%, etc., but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0103] Among them, the upsetting ratio in the fourth forging is ≥1.8, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0104] Among them, the drawing ratio in the fourth forging is ≥1.8, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0105] In the present invention, if the fourth forging is not completed in one firing, it is allowed to be returned to the furnace while hot, and the return and heat preservation time is selected according to (0.3-0.4min / mm)×T, where T is the equivalent thickness of the raw material.

[0106] Among them, the total forging ratio of the first forging, the second forging, the third forging and the fourth forging is ≥12.6, for example, it can be 12.6, 12.7, 12.8, 12.9, 13, 13.2, 13.4, 13.6, 13.8, 14, 14.2, 14.4, 14.6, 14.8 or 15, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0107] Wherein, the heat treatment includes solution-aging treatment or heat preservation-cooling treatment.

[0108] Wherein, the solution-aging treatment may be optionally carried out according to conventional requirements in the art, for example: the solution treatment is carried out by heating at a temperature where the β phase exists (910°C-940°C), and the heat preservation is carried out according to the heat penetration time + metallurgical transformation time, i.e., 0.6T+(60-90)min, wherein T is the effective thickness, and the aging treatment is carried out after rapid cooling (quenching) from this temperature to room temperature. The aging temperature is generally (520-550°C), and the heat preservation is carried out according to the heat penetration time + metallurgical transformation time, i.e., 0.7T+(90-120)min, and then air cooling is carried out to room temperature.

[0109] Wherein, the insulation-cooling treatment includes: insulation at 20-40°C below the β phase transition temperature for 50-80min, and then cooling. For example, it can be insulation at 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C or 40°C for 50min, 52min, 54min, 56min, 58min, 60min, 62min, 64min, 66min, 68min, 70min, 72min, 74min, 76min, 78min or 80min, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0110] Wherein, the cooling rate of the cooling is greater than or equal to the cooling rate of air cooling.

[0111] In the present invention, the blank obtained after heat treatment has a fine and uniform equiaxed structure or a dual-state structure, and no visible clear grains are allowed to appear.

[0112] The heating temperature for the roughening treatment is 45-50°C lower than the β phase transition temperature, for example, it can be 45°C, 46°C, 47°C, 48°C, 49°C or 50°C, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0113] Among them, the deformation amount in the roughening treatment is controlled to be 45-55%, for example, it can be 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54% or 55%, etc., but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0114] In the present invention, if the blank is cracked during forging, the defect needs to be removed by grinding or turning.

[0115] In the present invention, punching and expanding can be performed according to conventional design requirements in the art, and the present invention does not make any specific limitations.

[0116] Among them, the starting rolling temperature is 50-70°C lower than the β phase transformation temperature, for example, it can be 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0117] Wherein, at the beginning of the rolling, the radial growth rate of the control ring is 0.5-1 mm / s, and when the surface temperature of the billet is 750-850°C, the radial growth rate of the control ring is 0.1-0.2 mm / s.

[0118] Among them, at the beginning of rolling, the radial growth rate of the control ring is 0.5-1mm / s, for example, it can be 0.5mm / s, 0.55mm / s, 0.6mm / s, 0.65mm / s, 0.7mm / s, 0.75mm / s, 0.8mm / s, 0.85mm / s, 0.9mm / s, 0.95mm / s or 1mm / s, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0119] Among them, when the surface temperature of the billet during the rolling is 750-850℃, for example, it can be 750℃, 760℃, 780℃, 800℃, 820℃, 840℃ or 850℃, and the radial growth rate of the control ring is 0.1-0.2mm / s, for example, it can be 0.1mm / s, 0.11mm / s, 0.12mm / s, 0.13mm / s, 0.14mm / s, 0.15mm / s, 0.16mm / s, 0.17mm / s, 0.18mm / s, 0.19mm / s or 0.2mm / s, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0120] Among them, the final rolling temperature of the rolling is 650-750℃, for example, it can be 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, 710℃, 720℃, 730℃, 740℃ or 750℃, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0121] Among them, the rolled final billet is air-cooled to 420-460°C and then air-cooled. For example, it can be 420°C, 425°C, 430°C, 435°C, 440°C, 445°C, 450°C, 455°C or 460°C, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0122] In the present invention, the billet obtained by rolling can have a fine β phase transformation structure, and the content of the primary α phase is controlled to be 20-55% of a lamellar fine grain structure.

[0123] Wherein, when the final rolled billet is air-cooled, the cooling rate can be controlled to be ≥100°C / h.

[0124] Wherein, the annealing temperature is 710-780°C, for example, it can be 710°C, 715°C, 720°C, 725°C, 730°C, 735°C, 740°C, 745°C, 750°C, 755°C, 760°C, 765°C, 770°C, 775°C or 780°C, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0125] The annealing holding time is (0.6-0.8 mm / min)×fT+1.5h, where fT is the equivalent thickness of the TC4 ring forging.

[0126] In the present invention, the equivalent thickness of the TC4 ring forging refers to the case where the wall thicknesses of different parts of the workpiece are different. If the heating time is determined according to the wall thickness at a certain location to ensure the heat treatment quality, then the wall thickness at that location is called the effective thickness of the workpiece, specifically the maximum inner diameter of the obtained ring forging product.

[0127] Wherein, the cooling method of the annealing includes air cooling.

[0128] Further, in order to illustrate the preparation method of the TC4 titanium alloy ring forging provided by the present invention, the obtained TC4 titanium alloy ring forging can have good performance, and the following actual examples are used for illustration, as follows:

[0129] In the following example, the β-phase transformation temperature of the TC4 alloy ingot is 1000°C.

[0130] Example 1

[0131] This embodiment provides a method for preparing a TC4 titanium alloy ring forging, the preparation method comprising:

[0132] The TC4 titanium alloy ingot is subjected to ingot blanking, forging, punching, hole expansion, rolling and annealing in sequence to obtain a TC4 titanium alloy ring forging;

[0133] Among them, the rough turning size of the ring forging is: Φ3955mm / Φ3615mm×h450mm, the blank size after rolling is: Φ3985mm / Φ3585mm×h570mm, and the equivalent thickness is T=200mm;

[0134] The initial forging temperature of the forging blank is 1140°C, and the final forging temperature is 850°C. Since the cross-sectional size of the raw material is 820mm, the heating at this time includes: keeping the temperature at 640°C for 246min, and then keeping the temperature at 1130°C for 492min. The forging blank is drawn, the single pressing amount is controlled to be 37mm, and the total pressing amount is controlled to be 100mm.

[0135] The forging includes first forging, second forging, third forging, fourth forging, heat treatment and upsetting treatment performed in sequence; the total forging ratio of the first forging, second forging, third forging and fourth forging is 28.8;

[0136] The first forging includes: two sequential upsets and stretching, the preheating and holding temperature is 1045°C, the preheating and holding time is 615 minutes, the deformation amount is independently controlled to be 48% during the upset and the stretching, the upset ratio is 2, and the stretching ratio is 2.2;

[0137] The second forging includes: upsetting and drawing in sequence at one time, with a preheating and holding temperature of 955° C. and a preheating and holding time of 574 min; the deformation amount is independently controlled to be 50% during upsetting and drawing, the upsetting ratio is 2, and the drawing ratio is 2.2;

[0138] The third forging includes: two sequential upsets and stretching, the preheating and holding temperature is 1040°C, the preheating and holding time is 533 minutes; the amount of deformation is independently controlled to be 48% in the upset and stretching, the upset ratio is 2.2, and the stretching ratio is 1.8;

[0139] The fourth forging includes: two sequential upsets and stretching, the preheating and holding temperature is 955°C, the preheating and holding time is 533 minutes; the upset and stretching are independently controlled to have a deformation amount of 50%, an upset ratio of 1.8, and a stretching ratio of 2.3;

[0140] The heat treatment is a heat preservation-cooling treatment, including: keeping the temperature at 970°C for 60 minutes, and then cooling, and the cooling rate of the cooling is the cooling rate of air cooling, that is, air cooling;

[0141] The heating temperature of the roughening treatment is 951°C, and the deformation is controlled to be 55%;

[0142] At the beginning of the rolling, the radial growth rate of the control ring is 0.8 mm / s. When the surface temperature of the billet is 820°C, the radial growth rate of the control ring is 0.15 mm / s. The starting rolling temperature is 935°C, the final rolling temperature is 700°C, and the final rolled billet is air-cooled to 450°C and then air-cooled.

[0143] The annealing temperature is 740° C., the holding time is 4 hours, and the cooling method is air cooling.

[0144] Example 2

[0145] This embodiment provides a method for preparing a TC4 titanium alloy ring forging, the preparation method comprising:

[0146] The TC4 titanium alloy ingot is subjected to ingot blanking, forging, punching, hole expansion, rolling and annealing in sequence to obtain a TC4 titanium alloy ring forging;

[0147] Among them, the rough turning size of the ring forging is: Φ650mm / Φ480mm×h80mm, the blank size after rolling is: Φ665mm / Φ465mm*h185mm, and the equivalent thickness is T=100mm;

[0148] The initial forging temperature of the forging blank is 1130°C, and the final forging temperature is 800°C; the cross-sectional size of the raw material is 250mm, and the heating at this time includes: keeping the temperature at 1140°C for 200min; the forging blank is stretched, the single pressing amount is controlled to be 34mm, and the total pressing amount is controlled to be 102mm;

[0149] The forging includes first forging, second forging, third forging, fourth forging, heat treatment and upsetting treatment performed in sequence; the total forging ratio of the first forging, second forging, third forging and fourth forging is 26.8;

[0150] The first forging includes: two sequential upsetting and drawing, the preheating and holding temperature is 1040°C, the preheating and holding time is 175 minutes, the deformation amount is independently controlled to be 45% during upsetting and drawing, the upsetting ratio is 1.8, and the drawing ratio is 1.8;

[0151] The second forging includes: upsetting and drawing in sequence at one time, with a preheating and holding temperature of 960° C. and a preheating and holding time of 200 min; in the upsetting and drawing, the deformation amount is independently controlled to be 48%, the upsetting ratio is 1.8, and the drawing ratio is 1.8;

[0152] The third forging includes: two sequential upsets and stretching, the preheating and holding temperature is 1045°C, the preheating and holding time is 175 minutes; the amount of deformation is independently controlled to be 45%, the upset ratio is 1.8, and the stretching ratio is 2 during the upset and the stretching;

[0153] The fourth forging includes: two sequential upsets and stretching, the preheating and holding temperature is 960°C, the preheating and holding time is 175 minutes; the amount of deformation is independently controlled to be 48% during the upset and the stretching, the upset ratio is 2, and the stretching ratio is 2.2;

[0154] The heat treatment is a heat preservation-cooling treatment, including: keeping the temperature at 965°C for 70 minutes, and then cooling, and the cooling rate of the cooling is the cooling rate of air cooling, that is, air cooling;

[0155] The heating temperature of the roughening treatment is 952°C, and the deformation is controlled to be 45%;

[0156] At the beginning of the rolling, the radial growth rate of the control ring is 0.6 mm / s. When the surface temperature of the billet is 800°C, the radial growth rate of the control ring is 0.18 mm / s. The starting rolling temperature is 940°C, the final rolling temperature is 680°C, and the final rolled billet is air-cooled to 440°C and then air-cooled.

[0157] The annealing temperature is 720° C., the holding time is 160 min, and the cooling method is air cooling.

[0158] Example 3

[0159] This embodiment provides a method for preparing a TC4 titanium alloy ring forging, the preparation method comprising:

[0160] The TC4 titanium alloy ingot is subjected to ingot blanking, forging, punching, hole expansion, rolling and annealing in sequence to obtain a TC4 titanium alloy ring forging;

[0161] Among them, the rough turning size of the ring forging is: Φ3000mm / Φ2890mm×h300mm, the blank size after rolling is: Φ3025mm / Φ2865mm×420mm, and the equivalent thickness is T=80mm;

[0162] The initial forging temperature of the forging blank is 1150°C, and the final forging temperature is 880°C. Since the cross-sectional size of the raw material is 560mm, the heating at this time includes: keeping the temperature at 650°C for 168min, and then keeping the temperature at 1130°C for 336min. The forging blanking method includes drawing, the single pressing amount is controlled to be 30mm, and the total pressing amount is controlled to be 90mm.

[0163] The forging includes first forging, second forging, third forging, fourth forging, heat treatment and upsetting treatment performed in sequence; the total forging ratio of the first forging, second forging, third forging and fourth forging is 28;

[0164] The first forging includes: two sequential upsets and stretching, the preheating and holding temperature is 1030°C, the preheating and holding time is 448 minutes, the deformation amount is independently controlled to be 40% during the upset and the stretching, the upset ratio is 2, and the stretching ratio is 1.8;

[0165] The second forging includes: upsetting and drawing in sequence at one time, with a preheating and holding temperature of 950° C. and a preheating and holding time of 448 minutes; the deformation amount is independently controlled to be 45% during upsetting and drawing, the upsetting ratio is 1.8, and the drawing ratio is 1.8;

[0166] The third forging includes: two sequential upsets and stretching, the preheating and holding temperature is 1030°C, the preheating and holding time is 448 minutes; the amount of deformation is independently controlled to be 40% during the upset and the stretching, the upset ratio is 2.6, and the stretching ratio is 2;

[0167] The fourth forging includes: two sequential upsets and stretching, the preheating and holding temperature is 950°C, the preheating and holding time is 448 minutes; the amount of deformation is independently controlled to be 45% during the upset and the stretching, the upset ratio is 2, and the stretching ratio is 1.8;

[0168] The heat treatment is a heat preservation-cooling treatment, including: keeping the temperature at 980°C for 50 minutes, and then cooling, the cooling rate of the cooling is the cooling rate of air cooling, that is, air cooling;

[0169] The heating temperature of the roughening treatment is 950°C, and the deformation is controlled to be 50%;

[0170] At the beginning of the rolling, the radial growth rate of the control ring is 0.5 mm / s. When the surface temperature of the billet is 750°C, the radial growth rate of the control ring is 0.2 mm / s. The starting rolling temperature is 950°C, the final rolling temperature is 650°C, and the final rolled billet is air-cooled to 420°C and then air-cooled.

[0171] The annealing temperature is 710°C, the holding time is 154 minutes, and the cooling method includes air cooling.

[0172] Example 4

[0173] This embodiment provides a method for preparing a TC4 titanium alloy ring forging, the preparation method comprising:

[0174] The TC4 titanium alloy ingot is subjected to ingot blanking, forging, punching, hole expansion, rolling and annealing in sequence to obtain a TC4 titanium alloy ring forging;

[0175] Among them, the rough turning size of the ring forging is: Φ600mm / Φ520mm×h100mm, the blank size after rolling is: Φ620mm / Φ500mm*h122mm, and the equivalent thickness is T=60mm;

[0176] The initial forging temperature of the forging blank is 1120°C, and the final forging temperature is 850°C; the cross-sectional size of the raw material is 200mm, and the heating includes: keeping the temperature at 1130°C for 120min; the forging blank method includes drawing, the single pressing amount is controlled to be 40mm, and the total pressing amount is controlled to be 90mm;

[0177] The forging includes first forging, second forging, third forging, fourth forging, heat treatment and upsetting treatment performed in sequence; the total forging ratio of the first forging, second forging, third forging and fourth forging is 30.7;

[0178] The first forging comprises: two sequential upsetting and drawing, the preheating and holding temperature is 1050°C, the preheating and holding time is 120min, the deformation amount is independently controlled to be 50% during upsetting and drawing, the upsetting ratio is 1.9, and the drawing ratio is 2;

[0179] The second forging includes: upsetting and drawing in sequence at one time, with a preheating and holding temperature of 970°C and a preheating and holding time of 120 minutes; the deformation amount is independently controlled to be 55%, the upsetting ratio is 2, and the drawing ratio is 2.5 during the upsetting and the drawing;

[0180] The third forging includes: two sequential upsets and stretching, the preheating and holding temperature is 1050°C, the preheating and holding time is 120 minutes; the amount of deformation is independently controlled to be 50% during the upset and the stretching, the upset ratio is 2, and the stretching ratio is 2.4;

[0181] The fourth forging includes: two sequential upsets and stretching, the preheating and holding temperature is 970°C, the preheating and holding time is 120 minutes; the amount of deformation is independently controlled to be 55% in the upset and the stretching, the upset ratio is 2.2, and the stretching ratio is 2.6;

[0182] The heat treatment is a heat preservation-cooling treatment; the heat preservation-cooling treatment includes: keeping the temperature at 960° C. for 80 minutes, and then cooling, and the cooling rate is the cooling rate of air cooling, that is, air cooling;

[0183] The heating temperature of the roughening treatment is 955°C, and the deformation is controlled to be 45%;

[0184] At the beginning of the rolling, the radial growth rate of the control ring is 1 mm / s. When the surface temperature of the billet is 850°C, the radial growth rate of the control ring is 0.1 mm / s. The starting rolling temperature is 930°C, the final rolling temperature is 750°C, and the final rolled billet is air-cooled to 460°C and then air-cooled.

[0185] The annealing temperature is 780° C., the holding time is 138 min, and the cooling method is air cooling.

[0186] Example 5

[0187] The only difference from Example 1 is that the starting rolling temperature is 30°C lower than the β phase transformation temperature, namely 970°C.

[0188] Example 6

[0189] The only difference from Example 1 is that the starting rolling temperature is 90°C lower than the β phase transformation temperature, namely 930°C.

[0190] Example 7

[0191] The only difference from Example 1 is that the rolled final billet is directly air-cooled.

[0192] Example 8

[0193] The only difference from Example 1 is that the rolled final billet is air-cooled after being air-cooled to 600°C.

[0194] Comparative Example 1

[0195] The only difference from Example 1 is that the preheating and holding temperature of the first forging is 45°C lower than the β phase transformation temperature, that is, 955°C.

[0196] Comparative Example 2

[0197] The only difference from Example 1 is that the preheating and holding temperature of the second forging is 45°C higher than the β phase transformation temperature, namely 1045°C.

[0198] Comparative Example 3

[0199] The only difference from Example 1 is that the preheating and holding temperature of the third forging is 40°C lower than the β phase transformation temperature, that is, 960°C.

[0200] Comparative Example 4

[0201] The only difference from Example 1 is that the preheating and holding temperature of the fourth forging is 45°C higher than the β phase transformation temperature, that is, 1045°C.

[0202] Comparative Example 5

[0203] The only difference from Example 1 is that the radial growth rate of the ring is controlled to be 0.2 mm / s at the beginning of rolling.

[0204] Comparative Example 6

[0205] The only difference from Example 1 is that the radial growth rate of the ring is controlled to be 1.5 mm / s at the beginning of rolling.

[0206] Comparative Example 7

[0207] The only difference from Example 1 is that when the surface temperature of the blank is 700° C., the radial growth rate of the control ring is 0.15 mm / s.

[0208] Comparative Example 8

[0209] The only difference from Example 1 is that when the surface temperature of the blank is 900° C., the radial growth rate of the control ring is 0.15 mm / s.

[0210] Comparative Example 9

[0211] The only difference from Example 1 is that when the surface temperature of the blank is 820° C., the radial growth rate of the control ring is 0.05 mm / s.

[0212] Comparative Example 10

[0213] The only difference from Example 1 is that when the surface temperature of the blank is 820° C., the radial growth rate of the control ring is 0.3 mm / s.

[0214] The TC4 titanium alloy ring forgings obtained in the above embodiments and comparative examples were tested for mechanical properties according to GB / T228.1-2021 and GB / T229-2020, wherein the impact energy test was performed three times at 20°C and the average value was taken. The results are shown in Table 1 for details.

[0215] Table 1

[0216]

[0217]

[0218] As can be seen from Table 1, in Examples 1-4 of the scheme of the present invention, according to the process parameters provided by the present invention, the physical and chemical performance indicators all meet the product performance indicators, and have no obvious influence on the ingot specifications, the blanking temperature, and the annealing temperature; it can be seen from Examples 5-6 that the rolling temperature has a great influence on the final mechanical properties of the product, and a high rolling temperature will reduce the strength of the product; by comparing Example 1 with Example 7, it can be seen that the air cooling process after forging has a significant effect on the improvement of the final mechanical properties of the product, and air cooling after ring rolling can significantly improve the strength and impact value of the product; by comparing Example 1 with Example 8, the product is air-cooled during rolling, and the surface temperature of the product after air cooling has a significant influence on the final performance of the product. If the surface temperature of the product is high after the air cooling, the strength and impact work of the product will be seriously reduced.

[0219] It can be seen from Comparative Example 1 that if the ingot is basically kept below the β phase transformation point during forging, the ingot forging is not sufficient, which has a serious impact on the performance of subsequent products; it can be seen from Comparative Example 2 that the ingot is fully forged at the phase transformation point, which can ensure the final mechanical properties of the product, but compared with Example 1, the performance of the "high-low-high-low" process is better than that of the "high-high-high-low" product; it can be seen from Comparative Example 3 that the performance of the "high-low-high-low" process is better than that of the "high-high-low-low" product; it can be seen from Comparative Example 4 that the "high-low-high-low" process is better than that of the "high-high-low-low" product. The performance of the product of the "high-low" process is better than that of the "high-high-low-high" process; it can be seen from comparative examples 5 and 6 that the rolling speed has a significant effect on the mechanical properties of the product. The faster the rolling speed, the higher the product's machine temperature, and the more primary α phase content is obtained, resulting in reduced strength and failure to meet the product performance requirements; it can be seen from comparative examples 7-10 that during rolling, due to the different temperatures and radial growth rates of the rings, the products are deformed at different temperatures and the product's machine temperature is also different. From the results, the product performance is better when the surface temperature is within the range of the present invention.

[0220] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0221] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0222] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a TC4 titanium alloy ring forging, characterized in that: The preparation method comprises: The TC4 titanium alloy ingot is subjected to ingot blanking, forging, punching, hole expansion, rolling and annealing in sequence to obtain a TC4 titanium alloy ring forging; The forging includes first forging, second forging, third forging, fourth forging, heat treatment and roughening treatment performed in sequence; the preheating and heat preservation temperature of the first forging is 30-50°C higher than the β phase transformation temperature; the preheating and heat preservation temperature of the second forging is 30-50°C lower than the β phase transformation temperature; the preheating and heat preservation temperature of the third forging is 30-50°C higher than the β phase transformation temperature; the preheating and heat preservation temperature of the fourth forging is 30-50°C lower than the β phase transformation temperature; At the beginning of the rolling, the radial growth rate of the control ring is 0.5-1 mm / s. When the surface temperature of the billet is 750-850° C., the radial growth rate of the control ring is 0.1-0.2 mm / s.

2. The preparation method according to claim 1, characterized in that The initial forging temperature of the forging blank is 120-150° C. higher than the β phase transformation temperature; Preferably, the final forging temperature of the forging blank is ≥800°C; Preferably, the cross-sectional size of the raw material in the forging blank is ≤250 mm, and the heating comprises: keeping the temperature at 130-140° C. higher than the β phase transformation temperature for t=(0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material; Preferably, the cross-sectional size of the raw material in the forging blank is greater than 250 mm, and the heating comprises: holding at a temperature of 640-660° C. for t=(0.3-0.45 min / mm)×T, then holding at a temperature of 130-140° C. higher than the β phase transformation temperature for t=(0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material; Preferably, the forging method includes drawing; Preferably, the single pressing amount of the forging blank is controlled to be 30-40 mm; Preferably, the total reduction amount of the forging process is controlled to be 90-110 mm.

3. The preparation method according to claim 1 or 2, characterized in that: The first forging includes: at least two sequential upsetting and drawing operations; Preferably, the preheating and holding time of the first forging is (0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material; Preferably, the deformation amount in the upsetting and the drawing in the first forging is independently controlled to be 40-50%; Preferably, the upsetting ratio in the first forging is ≥1.8; Preferably, the drawing ratio in the first forging is ≥1.

8.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The second forging includes: at least one sequential upsetting and drawing; Preferably, the preheating and holding time of the second forging is (0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material; Preferably, the deformation amount in the upsetting and the drawing in the second forging is independently controlled to be 45-55%; Preferably, the upsetting ratio in the second forging is ≥1.8; Preferably, the drawing ratio in the second forging is ≥1.

8.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The third forging includes: upsetting and drawing performed sequentially at least twice; Preferably, the preheating and holding time of the third forging is (0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material; Preferably, the deformation amount in the upsetting and the drawing in the third forging is independently controlled to be 40-50%; Preferably, the upsetting ratio in the third forging is ≥1.8; Preferably, the drawing ratio in the third forging is ≥1.

8.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The fourth forging includes: upsetting and drawing performed sequentially at least twice; Preferably, the preheating and holding time of the fourth forging is (0.6-0.8 min / mm)×T, where T is the equivalent thickness of the raw material; Preferably, the deformation amount in the upsetting and the drawing in the fourth forging is independently controlled to be 45-55%; Preferably, the upsetting ratio in the fourth forging is ≥1.8; Preferably, the drawing ratio in the fourth forging is ≥1.

8.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The total forging ratio of the first forging, the second forging, the third forging and the fourth forging is ≥12.6; Preferably, the heat treatment includes solution-aging treatment or heat preservation-cooling treatment; Preferably, the heat preservation-cooling treatment comprises: heat preservation at 20-40° C. below the β phase transition temperature for 50-80 min, and then cooling; Preferably, the cooling rate of the cooling is greater than or equal to the cooling rate of air cooling.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The heating temperature of the roughening treatment is 45-50°C lower than the β phase transition temperature; Preferably, the deformation amount is controlled to be 45-55% during the roughening process.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The starting rolling temperature is 50-70°C lower than the β phase transformation temperature; the final rolling temperature is 650-750°C; Preferably, the rolled final billet is air-cooled to 420-460° C. and then air-cooled.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The annealing temperature is 710-780°C; Preferably, the annealing holding time is (0.6-0.8 mm / min)×fT+1.5h, where fT is the equivalent thickness of the TC4 ring forging; Preferably, the cooling method of the annealing includes air cooling.

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