A plastic processing technology for realizing grain refinement and homogenization of titanium alloy forging blanks

Abstract

The present invention relates to the technical field of titanium alloy plastic processing, and specifically discloses a plastic processing process for realizing grain refinement and homogenization of titanium alloy forging blanks. Specifically, the TC18 titanium alloy ingot is subjected to the first-pass cogging forging at 1150-1250 °C, and then the forging blank is heated to (30-50) °C below the β transformation temperature for one-pass forging. Then the blank is heated to (300-400) °C below the β transformation temperature for one-pass cold deformation, and then the blank is heated to (30-50) °C above the β transformation temperature for recrystallization refinement and homogenization treatment. The present invention can achieve the purpose of significantly refining grains with fewer passes, and the grain refinement effect is better than that of traditional multi-pass repeated upsetting and drawing forging.

Description

Technical Field

[0001] The present invention relates to the field of titanium alloy plastic processing, and particularly to a plastic processing process for rapidly realizing grain refinement and homogenization of large-sized forging blanks of TC18 titanium alloy. Background Art

[0002] TC18 titanium alloy is a typical high-strength and tough near-β titanium alloy. Due to its excellent strength-plasticity-toughness matching, it is widely used in manufacturing large load-bearing components such as aircraft landing gears, frames, and beams, and has broad application prospects. At present, the main melting method for high-end titanium alloy ingots for aviation in China is vacuum consumable arc melting (VAR melting). During the melting process of this method, the liquid molten pool maintains a short time, and the molten pool stirring is insufficient, resulting in a typical fine grain, columnar grain, and equiaxed grain zone from the outside to the inside of the titanium alloy ingot. Among them, the grain size of the columnar grains usually reaches dozens or even hundreds of millimeters, and has obvious directionality. If this original coarse and non-uniform as-cast structure cannot be effectively improved, it is extremely easy to be inherited to the final forging, resulting in local coarse structure in the forging, laying a quality hidden danger for the service of the forging. Therefore, it is necessary to use forging to crush and refine the as-cast grains.

[0003] The phase transformation temperature of TC18 titanium alloy is relatively low, and the forging process has characteristics such as a narrow forging process window, large deformation resistance, and extreme sensitivity to deformation parameters. In order to crush the as-cast grains of β-type titanium alloy, the traditional method is usually to perform multi-pass repeated upsetting and drawing forging on the ingot at high temperature. Since each forging pass is carried out above the recrystallization temperature, while the material undergoes work hardening during the hot deformation process, recovery and recrystallization will occur. The lattice distortion formed during the deformation process is difficult to be preserved to room temperature, the recrystallization nucleation rate is low, and the grain growth rate is fast. The recrystallization refinement and homogenization effects are limited. Therefore, multi-pass repeated upsetting and drawing are usually also required, but it is easy to cause a long production cycle and high costs. Moreover, when the grains are refined to a certain extent, it is difficult to further refine them by increasing the number of upsetting and drawing forging passes. The non-uniformity of deformation also determines that the uniformity of crushing and refining grains by simply deforming is relatively poor, and there are limitations in both grain refinement and homogenization effects.

[0004] Cold deformation can increase the dislocation density in titanium alloys, thereby affecting the heat treatment structure and properties of titanium alloys. The patent application with the publication number CN201810521142 and the title "A heat treatment method for improving the strength and plasticity of TC4 titanium alloy" discloses a heat treatment method for TC4 titanium alloy. The purpose of this method is to use the thermomechanical treatment method of cold deformation + aging to refine the secondary α phase precipitated during aging, thereby improving the strength and plasticity of the alloy. However, the specific process parameters of its cold deformation are not applicable to the recrystallization refinement and homogenization of β grains. Moreover, TC4 is an (α + β) type titanium alloy with a relatively high phase transformation temperature (about 1000 °C), and the temperature required for obvious recrystallization of the alloy is also relatively high. The grain growth rate is relatively fast under high-temperature conditions. Therefore, for (α + β) type and α type titanium alloys with relatively high phase transformation temperatures, it is difficult to significantly refine β grains through recrystallization. The patent application with the publication number CN202011229602.6 and the title "A processing method for improving the strength and plasticity of copper-containing titanium alloy" discloses a processing method for improving the strength and plasticity of copper-containing titanium alloy. The purpose of this method is to use the method of cold deformation + medium and low-temperature annealing to refine the submicron or nanoscale copper-containing precipitates precipitated during aging, thereby improving the strength and plasticity of the alloy. The specific temperature of its cold deformation is carried out below 400 °C. This temperature is suitable for copper-containing titanium alloys with good plastic processing performance. However, for thick-section β type alloys with extremely high deformation resistance, it is difficult to undergo plastic deformation under this temperature condition.

[0005] Aiming at the plastic processing characteristics of TC18 titanium alloy, seeking a more concise and efficient plastic processing process to quickly realize the refinement and homogenization of the coarse columnar grains of TC18 titanium alloy is of great significance for the further popularization and application of this titanium alloy material. Summary of the Invention

[0006] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a plastic processing process for quickly realizing the grain refinement and homogenization of large-sized forgings of TC18 titanium alloy. Through a small number of heating passes, the rapid refinement and homogenization of the grains of large-sized titanium alloy ingots can be completed. Not only the number of forging passes is greatly reduced compared with the traditional process, but also the degree of grain refinement and homogenization is significantly higher than that of the existing technologies.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is: a plastic processing process for realizing grain refinement and homogenization of titanium alloy forgings, characterized in that the TC18 titanium alloy ingot is subjected to the first-pass blooming forging at 1150 - 1250 °C, and then the forging blank is heated to (30 - 50) °C below the β transformation temperature for 1 pass of forging, and then the blank is heated to (300 - 400) °C below the β transformation temperature for 1 pass of cold deformation, and then the blank is heated to T β +(30 - 50) °C for recrystallization refinement and homogenization treatment.

[0008] After cogging forging, the forged blank is heated to (30 - 50)°C below the β transformation temperature for one-pass forging. The purpose is to appropriately break the primary α phase, increase the process plasticity of the blank, and accumulate partial deformation energy storage. Then, the blank is heated to Tβ - (300 - 400)°C for one-pass cold deformation to form a large number of deformation defects inside the blank, providing a large number of nucleation points for the subsequent recrystallization refinement. The inventor found through a large number of experiments that when the cold deformation temperature is relatively low (especially at room temperature), the deformation resistance of cold deformation is extremely large, the deformation is difficult to carry out and is extremely prone to cracking. However, if the cold deformation temperature is too high or the forging ratio is too large, it is extremely easy to raise the local temperature above the recrystallization temperature, exacerbating the non-uniformity of the subsequent recrystallized structure.

[0009] Furthermore, the plastic processing process for realizing the grain refinement and homogenization of the titanium alloy forged blank is specifically realized through the following steps:

[0010] Step 1): Heat the titanium alloy ingot to 1150 - 1250°C for one-pass forging. The cumulative forging ratio for this pass is controlled between 3 and 6, and the cylindrical ingot is forged into a forged blank with a square cross-section.

[0011] Step 2): Heat the forged blank obtained in Step 1 to T β - (30 - 50)°C for one-pass forging. The cumulative forging ratio for this pass is controlled between 1.5 and 2.5.

[0012] Step 3): Heat the forged blank obtained in Step 2 to T β - (300 - 400)°C, and perform one-pass cold deformation along the thickness direction of the cross-section of the forged blank. The cold deformation forging ratio is controlled between 1.1 and 1.3. After the cold deformation is completed, the minimum cross-sectional size of the blank does not exceed 450 mm.

[0013] Step 4): Heat the forged blank obtained in Step 3 to T β + (30 - 50)°C for heat preservation. The recrystallization heat preservation time is calculated according to t = k·h, where k is the recrystallization heat preservation coefficient, the k value is controlled between 1.0 and 1.5 min / mm, and h is the minimum cross-sectional size of the blank. After the heat preservation is completed, take it out of the furnace and perform one-pass sizing forging. The forging ratio is controlled between 1.1 and 1.3. After forging, air-cool it to room temperature, and the full refinement and homogenization of the ingot are completed.

[0014] Furthermore, the heating in the above Step 1) to Step 4) all adopts charging the furnace when reaching the temperature. Start timing when the charging is completed and the furnace temperature resumes to the set temperature ±10°C.

[0015] Furthermore, the heating heat preservation coefficient in the above Step 1) is controlled to be 0.60 - 0.80, the forging time does not exceed 15 min, and after forging, chamfer it and air-cool it to room temperature.

[0016] Further, the heating and heat preservation coefficient in the above step 2) is controlled to be 0.65 - 0.85, the forging time does not exceed 10 min, and after forging, it is cooled to room temperature by circulating water, where the water temperature at the outlet does not exceed 50°C.

[0017] Further, in the above step 3), the cold deformation adopts any one of the conventional plastic processing methods such as cold forging and cold rolling, and after the cold deformation is completed, it is air-cooled to room temperature.

[0018] The working principle of the present invention is as follows:

[0019] The process of grain refinement is the process of alloy recrystallization. The recrystallized grain size is affected by the nucleation rate and the grain growth rate. Generally, the higher the nucleation rate or the slower the grain growth rate, the smaller the recrystallized grains. On the premise that the alloy composition is determined, the recrystallization nucleation rate is mainly related to the stored distortion energy of the pre-deformation before recrystallization. The more metastable phases preserved by the pre-deformation, the greater the distortion energy, and the more nucleation points provided for the recrystallization process, and the higher the nucleation rate. The grain growth rate is mainly affected by the recrystallization temperature and time. The higher the recrystallization heating temperature, the faster the grain growth rate, and the larger the recrystallized grain size.

[0020] Conventional forging processes usually choose to heat and deform above the recrystallization temperature. While deformation produces work hardening, it is accompanied by recovery and recrystallization, resulting in a significant reduction or even disappearance of crystal defects such as vacancies and dislocations generated during the deformation process. There are very few crystal defects that can be retained to room temperature after cooling, resulting in a relatively low recrystallization nucleation rate. Cold deformation below the recrystallization temperature can significantly increase the distortion energy, and the crystal defects formed below the recrystallization temperature will not disappear due to recovery and recrystallization. A large number of preserved defects can provide a large number of nucleation points for subsequent recrystallization nucleation, thus increasing the recrystallization nucleation rate. However, for β-type thick-section titanium alloys, the deformation resistance during cold deformation at room temperature is extremely large, the deformation is difficult to carry out, and it is extremely easy to crack. If the cold deformation temperature is too high or the forging ratio is too large, it is very easy to make the local temperature rise above the recrystallization temperature, exacerbating the subsequent non-uniformity of recrystallization. This application aims at the characteristics of TC18 titanium alloy, and through a large number of experiments, explores a cold deformation processing window suitable for this type of alloy to significantly increase the recrystallization nucleation rate, thus quickly realizing the grain refinement of TC18 titanium alloy.

[0021] In addition to exploring the cold deformation window suitable for TC18 titanium alloy to increase the recrystallization nucleation rate, the present application also strictly controls the recrystallization process window. The recrystallization process parameters have an important influence on the size and uniformity of the β grains after recrystallization. Billets with different cross-sectional thicknesses need to match different recrystallization temperatures and times. If the recrystallization temperature is too high or the time is too long, the grains will coarsen and even undergo secondary recrystallization growth. If the recrystallization temperature is too low or the time is too short, the recrystallization will be too long and insufficient, and the purpose of grain refinement and homogenization will not be achieved. For TC18 titanium alloy, its phase transition temperature is relatively low (not exceeding 900°C), and the recrystallization temperature is also correspondingly low. In view of the recrystallization characteristics of TC18 titanium alloy, the present application has found through a large number of experiments that controlling the recrystallization temperature of this type of titanium alloy at T β + (30~50) ℃ for insulation, the grains will not grow significantly after complete recrystallization, so this application controls the recrystallization temperature at T β + (30~50) ℃ range, through a large number of experiments to find out the time required for billets with different cross-sectional thicknesses to complete full recrystallization, to ensure that the grains at different cross-sectional depths of the billet are fully recrystallized, and at the same time strictly control the billet cross-sectional thickness during recrystallization homogenization, to minimize the difference in recrystallization holding time at different parts caused by the cross-sectional thickness, so as to achieve the purpose of achieving grain refinement while ensuring grain homogenization at different parts of the billet.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention significantly improves the recrystallization nucleus rate by selecting a suitable cold deformation processing window for one-time cold deformation before recrystallization homogenization, thereby achieving the purpose of significant grain refinement with fewer fires, and the grain refinement effect is better than that of traditional multi-fire repeated upsetting and forging;

[0024] 2. Aiming at the low recrystallization temperature of TC18 titanium alloy, the present invention strictly controls the recrystallization homogenization temperature and appropriately prolongs the holding time under the recrystallization temperature to ensure that the material undergoes complete recrystallization under the temperature without obvious grain growth. At the same time, a flat square is used for recrystallization homogenization to further reduce the recrystallization holding time of different parts of the blank, thereby greatly improving the grain uniformity of different parts of the blank;

[0025] 3. The present invention achieves grain refinement quickly by significantly improving the recrystallization nucleation rate through cold deformation, avoiding the traditional method of using a large number of upsetting and forging methods for grain refinement, greatly reducing the number of forging fires, reducing the forging production cost, and because of the shortened production cycle, the process controllability is further enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is the macrostructure diagram of the TC18 titanium alloy ingot;

[0027] Figure 2 It is the macro grain diagram corresponding to Scheme 1 mentioned in the present invention;

[0028] Figure 3 It is the macro grain diagram corresponding to Scheme 2 mentioned in the present invention;

[0029] Figure 4 It is the macro grain diagram corresponding to Scheme 3 (i.e., Example 1 of the present application) mentioned in the present invention. Specific embodiments

[0030] The present invention will be elaborated in detail below in combination with embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention. Any identical or similar schemes without departing from the concept of the present invention shall fall within the protection scope of the present invention. And for the parts not described in detail in the text, they are carried out in the conventional manner in the art. And in the following text: "Φ" refers to the diameter of the blank with a circular cross-section; T β is the phase transformation point temperature.

[0031] Material: TC18, phase transformation point: 865 °C, the ingot specification is Φ680×1400 mm, the ingot is obtained by 3 times of vacuum consumable arc melting, the transverse grain size of the ingot reaches 15 - 20 mm, and the macrostructure is as Figure 1 shown.

[0032] The plastic processing process for realizing grain refinement and homogenization of the titanium alloy forging blank in the present invention is specifically realized through the following steps:

[0033] Step 1): Heat the titanium alloy ingot to 1150 - 1250 °C, load it into the furnace when reaching the temperature, start timing when the furnace temperature resumes to the set temperature ±10 °C, control the holding coefficient to be 0.60 - 0.80, after the holding is completed, take it out of the furnace for one-pass forging, the cumulative forging ratio of this pass is controlled between 3 - 6, forge the cylindrical ingot into a forging blank with a square cross-section, the forging time does not exceed 15 min, chamfer after forging and air-cool to room temperature.

[0034] Step 2): Heat the forging blank obtained in Step 1 to T β -(30 - 50) °C, load it into the furnace when reaching the temperature, start timing when the furnace temperature resumes to the set temperature ±10 °C, the holding coefficient is 0.65 - 0.85, after the holding is completed, take it out of the furnace for one-pass forging, the cumulative forging ratio of this pass is controlled between 1.5 - 2.5, the forging time does not exceed 10 min, cool it to room temperature by circulating water after forging, and the water temperature at the outlet does not exceed 50 °C;

[0035] The inventor found that forging the forging billet once at a temperature 30 - 50°C below the β transformation temperature before cold deformation and controlling a reasonable forging ratio can appropriately break the primary α phase, increase the process plasticity of the billet, and accumulate partial deformation energy storage.

[0036] Step 3): Heat the forging billet obtained in Step 2 to T β -(300 - 400)°C, charge into the furnace when reaching the temperature, fully heat-insulate and then take out of the furnace, and perform one-pass cold deformation along the thickness direction of the cross-section of the forging billet. The cold deformation specifically adopts any one of the conventional plastic processing methods such as cold forging and cold rolling. The cold deformation forging ratio is controlled between 1.1 and 1.3. After the cold deformation, the billet is a flat square with a minimum cross-sectional size not exceeding 450 mm, and air-cool after forging.

[0037] The inventor found that for β-type thick-section titanium alloys, when the cold deformation temperature is relatively low, the deformation resistance is extremely large, the deformation is very difficult to carry out, and it is very easy to crack. However, if the cold deformation temperature is designed too high or the forging ratio is designed too large, it is extremely easy to make the local temperature rise above the recrystallization temperature, exacerbating the unevenness of subsequent recrystallization. Through a large number of experiments, the present application has found that when the cold deformation temperature is controlled within the range of 300 - 400°C below the β transformation temperature and the forging ratio is effectively controlled between 1.1 and 1.3, the recrystallization nucleation rate can be significantly increased.

[0038] Step 4): Heat the forging billet obtained in Step 3 to T β +(30 - 50)°C for heat insulation. The recrystallization heat-insulation time is calculated according to t = k·h, where k is the recrystallization heat-insulation coefficient, the k value is controlled between 1.0 - 1.5 min / mm, and h is the minimum cross-sectional size of the billet. After the heat insulation ends, take out of the furnace and perform one-pass sizing forging. The forging ratio is controlled between 1.1 and 1.3, and air-cool to room temperature after forging, that is, the full refinement and homogenization of the ingot are completed.

[0039] The recrystallization process parameters have important influences on both the β grain size and uniformity after recrystallization. The recrystallization temperature of TC18 is relatively low. If the lower recrystallization temperature is controlled or the recrystallization time is too short, or the recrystallization is too long and insufficient, the purpose of grain refinement and homogenization cannot be achieved. Through a large number of experiments, the inventor has found that when the recrystallization temperature of β-type titanium alloys is controlled at T β +(30 - 50)°C for heat insulation, and the recrystallization time required for billets with different cross-sectional thicknesses is controlled, and the cross-sectional thickness of the billet during recrystallization homogenization is strictly controlled (not exceeding 450 mm), the grain refinement can be effectively achieved while ensuring the grain uniformity of different parts of the billet.

[0040] The following is a comparison between the processing technology of the present invention and the processing technology in the prior art:

[0041] I. The short-process bloom forging method in the prior art (abbreviated as Scheme 1)

[0042] The as-cast bloom forging process is rapidly completed through 4 hot plastic working processes, which are specifically implemented through the following steps:

[0043] Step 1: Heat a TC18 titanium alloy ingot with a specification of Φ680×1400mm to 1150°C for the first hot upsetting and drawing forging. The forging ratio of this heat is 6.5, and it is air-cooled after forging.

[0044] Step 2: Use an electric furnace to heat the billet obtained in Step 1 to 1050°C for the second hot upsetting and drawing forging. The forging ratio of this heat is 6.0, and it is air-cooled after forging.

[0045] Step 3: Use an electric furnace to heat the billet obtained in Step 2 to 830°C for the third hot upsetting and drawing forging. The forging ratio of this heat is 1.6, and it is water-cooled after forging.

[0046] Step 4: Heat the forged billet obtained in Step 3 to 960°C for holding and recrystallization treatment. The holding coefficient is controlled at 0.7. After the holding is completed, take it out of the furnace for one hot sizing forging. The forging ratio is 1.2, and it is air-cooled to room temperature after forging.

[0047] II. Conventional bloom forging method in the prior art (abbreviated as Solution 2)

[0048] The refinement and homogenization of the as-cast crystal are completed through 8 hot forging processes, which are specifically implemented through the following steps:

[0049] Step 1: Heat a TC18 titanium alloy ingot with a specification of Φ680×1400mm to 1150°C for the first hot upsetting and drawing forging. The forging ratio of this heat is 9.2, and it is air-cooled after forging.

[0050] Step 2: Use an electric furnace to heat the billet obtained in Step 1 to 1100°C - 950°C for the second to fifth hot upsetting and drawing forging. The forging ratio of each heat is controlled in the range of 9.5 - 10.5, and each is air-cooled after forging.

[0051] Step 3: Use an electric furnace to heat the billet obtained in Step 2 to 830°C for the sixth hot upsetting and drawing forging. The forging ratio of this heat is 1.7, and it is air-cooled after forging.

[0052] Step 4: Use an electric furnace to heat the billet obtained in Step 3 to 1000°C - 950°C, and use a 45MN quick forging machine for the seventh to eighth hot upsetting and drawing forging. The forging ratio of each heat is controlled in the range of 5.0 - 7.5, and it is air-cooled after forging to complete the refinement and homogenization of the as-cast crystal.

[0053] III. Forging method of Embodiment 1 of the present application (abbreviated as Solution 3)

[0054] The refinement and homogenization of the as-cast grains are rapidly realized through 4 hot plastic working processes. Specifically, it includes the following steps:

[0055] Step 1: Heat a TC18 titanium alloy ingot with a specification of Φ680×1400mm to 1200°C, load it into the furnace when reaching the temperature, start timing after the furnace temperature resumes to 1200±10°C, with a soaking factor of 0.75. After soaking, take it out of the furnace for the first forging pass. The forging ratio of this pass is 5.2, the forging time is less than 15 min. Chamfer the forging after forging and air-cool it to room temperature;

[0056] Step 2: Heat the blank obtained in Step 1 to 830°C, load it into the furnace when reaching the temperature, start timing after the furnace temperature resumes to 830±10°C, with a soaking factor of 0.7. After soaking, take it out of the furnace for the second forging pass. The forging ratio of this pass is 1.7, the forging time is less than 10 min. Cool it to room temperature by circulating water after forging, and the outlet water temperature does not exceed 50°C;

[0057] Step 3: Heat the blank obtained in Step 2 to 550°C, load it into the furnace when reaching the temperature, and after sufficient soaking, take it out of the furnace for the third cold deformation pass. The cold deformation forging ratio is 1.2, forge the blank into a flat square with a cross-section of 400mm, and air-cool it after forging;

[0058] Step 4: Heat the forged blank obtained in Step 3 to 910°C for soaking, control the soaking factor at 1.2. After soaking, take it out of the furnace for one forging pass for sizing. The forging ratio is 1.1, and air-cool it to room temperature after forging, then the full refinement and homogenization of the ingot can be completed.

[0059] Macrographs of the same TC18 titanium alloy ingot after cogging forging completed by three different schemes are as Figure 2 、 3 、shown in Figure 4. Among them Figure 2 is the macroscopical macrostructure obtained after forging a TC18 ingot by 4 forging passes according to the conventional short process, Figure 3 is the macroscopical macrostructure obtained after forging a TC18 ingot by 8 forging passes according to the traditional process, Figure 4 is the macroscopical macrostructure after 4 plastic working passes according to the technology of Example 1 of the present application. From the comparison between Figure 2 and Figure 4 , it can be known that under the condition of the same number of forging passes, for the forged blank obtained by the existing short process, the average grain size of the core part is 3 - 5mm, and that of the edge part reaches 4 - 8mm. The grain size is coarse, and the grain size gradually increases from the core part to the edge part, with relatively poor overall uniformity. While for the β forged blank obtained according to Example 1 of the present application, the β grain size of different parts is 1 - 2mm, and the degree of grain refinement and homogenization is significantly better than that of the traditional short process. From the comparison between Figure 3 and Figure 4By comparison, it can be seen that the macrostructure low-magnification central grains after forging by the traditional process are significantly coarser than those at the edge, and there are obvious deformation streamlines, and the tissue uniformity is relatively poor. While implementing according to the first embodiment of the present application, on the premise that the number of heats is reduced by half, the degree of grain refinement is basically the same as that of the traditional process, but the degree of grain refinement in the center is better than that of the traditional process, and the grain uniformity in different parts is significantly better than that of the traditional process.

Claims

1. A plastic processing process for realizing grain refinement and homogenization of titanium alloy forging blanks, characterized in that, It is specifically achieved through the following steps: Step 1): Heat the TC18 titanium alloy ingot to 1150 - 1250 °C for one-pass forging, and control the cumulative forging ratio of this pass between 3 and 6. Forge the cylindrical ingot into a forging blank with a square cross-section; Step 2): Heat the forging blank obtained in Step 1 to Tβ - (30 - 50) °C for one-pass forging, and control the cumulative forging ratio of this pass between 1.5 and 2.5; Step 3): Heat the forging blank obtained in Step 2 to Tβ - (300 - 400) °C, and perform one-pass cold deformation along the thickness direction of the forging blank cross-section. Control the cold deformation forging ratio between 1.1 and 1.

3. After cold deformation, the minimum cross-section of the blank does not exceed 450 mm; Step 4): Heat the forging blank obtained in Step 3 to Tβ + (30 - 50) °C for heat preservation. The recrystallization heat preservation time is calculated according to t = k·h, where k is the recrystallization heat preservation coefficient, and the k value is controlled between 1.0 and 1.5 min / mm, and h is the minimum cross-section size of the blank. After heat preservation, take it out of the furnace for one-pass sizing forging, control the forging ratio between 1.1 and 1.3, and air cool to room temperature after forging, that is, complete the full refinement and homogenization of the ingot.

2. The plastic processing process for realizing grain refinement and homogenization of titanium alloy forging blanks according to claim 1, characterized in that, For the heating in the above Step 1) to Step 4), the furnace is charged when the temperature reaches the set value. Timing starts when the charging is completed and the furnace temperature resumes to within ±10 °C of the set temperature.

3. The plastic processing technology for realizing grain refinement and homogenization of titanium alloy forging blanks according to claim 1, characterized in that, The heating heat preservation coefficient in the above Step 1) is controlled to be 0.60 - 0.80, the forging time does not exceed 15 min, chamfer the forging after forging and air cool to room temperature.

4. The plastic processing process for realizing grain refinement and homogenization of titanium alloy forging blanks according to claim 1, characterized in that, The heating heat preservation coefficient in the above Step 2) is controlled to be 0.65 - 0.85, the forging time does not exceed 10 min, and cool to room temperature by circulating water after forging, where the outlet water temperature does not exceed 50 °C.

5. The plastic processing technology for realizing grain refinement and homogenization of titanium alloy forging blanks according to claim 1, characterized in that, For the cold deformation in the above Step 3), any one of cold forging and cold rolling can be used, and air cool to room temperature after cold deformation.

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