A large-size tc4 titanium alloy beta phase region hot deformation method based on temperature-strain field synergistic regulation

Abstract

The application discloses a large-size TC4 titanium alloy beta phase region hot deformation method based on temperature-strain field cooperative regulation, and the method comprises the following steps: firstly, a large-size TC4 titanium alloy round ingot is heated to a beta phase region temperature interval and kept warm; secondly, axial upsetting hot deformation is carried out to obtain a blank; thirdly, the blank is heated and kept warm; fourthly, the blank after the heating and keeping warm is once axially elongated after being rotated by 45 degrees along the original ingot axial direction; fifthly, the blank is twice axially elongated after being rotated by 90 degrees along the original ingot axial direction; and sixthly, the blank is thrice axially elongated after being rotated by 90 degrees along the original ingot axial direction to obtain a TC4 titanium alloy square blank. The application actively regulates the energy accumulation and recrystallization driving force of different regions by designing a multi-directional strain path and a thermal force coupling process window, guides the gradient ordered evolution of the regional recrystallization, and significantly improves the structure uniformity and process controllability of the large-size titanium alloy blank, and is suitable for the field of super-large titanium alloy forgings for aviation, aerospace and ships.

Description

Technical Field

[0001] This invention belongs to the field of hot working technology of metal materials, and specifically relates to a hot deformation method for the β phase region of large-size TC4 titanium alloy based on temperature-strain field synergistic control. Background Technology

[0002] TC4 titanium alloy (Ti-6Al-4V) is widely used in aerospace, shipbuilding, and other fields due to its high specific strength, excellent corrosion resistance, and good high-temperature performance. It is the most widely used α+β type titanium alloy. To obtain a high-performance equiaxed microstructure, a multi-stage thermomechanical processing route of "β phase region billet preparation + (α+β) phase region reforging" is usually adopted. First, the ingot is hot-deformed above the β transformation temperature (about 1000~1200℃). The hot deformation of the β phase region aims to refine the original coarse as-cast β grains, providing uniform initial conditions for subsequent microstructure transformation. Then, the billet is deformed in the α+β two-phase region, causing the α lamellars to spheroidize, ultimately obtaining a high-performance TC4 alloy with a uniform equiaxed microstructure. Since the β grain size determines the α lamellar size, it is easier to obtain a qualified equiaxed microstructure when the original β grains are uniform and fine. Therefore, refining the β grains through hot deformation is crucial for the processing of titanium alloys.

[0003] In actual production, during the hot deformation of the β-phase region of large-size titanium alloy ingots and billets, heat loss from the surface of the ingot and billet is greater than the temperature loss at the center due to heat conduction and radiation. Simultaneously, the deformation heat effect causes the temperature at the center of the ingot to rise, resulting in a temperature gradient across the entire ingot and billet cross-section. Furthermore, during the forging upsetting process, three deformation zones exist within the billet: the main deformation zone at the core, the difficult-to-deform zone at the ends, and the intermediate secondary deformation zone (located between the main deformation zone and the difficult-to-deform zone, serving as a transition area between the two). This results in a gradient distribution of equivalent strain values ​​on the cross-section and longitudinal section of the ingot. This temperature-strain gradient distribution leads to regional differences in the dynamic recovery (DRV) and dynamic recrystallization (DRX) behaviors of the alloy billet, ultimately causing a regionalized recrystallization gradient in the microstructure of the alloy billet. The physical essence of this regionalization lies in the fact that in the high-temperature, high-strain core region, the dislocation multiplication rate far exceeds the annihilation rate, leading to rapid energy accumulation and providing ample thermodynamic and kinetic driving force for dynamic recrystallization (DRX). In contrast, in the low-temperature, low-strain end / edge regions, dislocation slip and climb are restricted, with dynamic recovery (DRV) primarily occurring. Energy storage levels are low, making it difficult to reach the critical nucleation work for recrystallization. This significant difference in energy storage distribution directly affects the consistency of subsequent tissue evolution and the stability of mechanical properties.

[0004] Existing technologies mostly focus on optimizing parameters (such as heating temperature and reduction) of the billet as a single homogeneous material, lacking a systematic control over the deformation of large-scale TC4 titanium alloy regions under the coupled effect of temperature and strain fields. This makes it difficult to achieve overall microstructure homogenization and precise performance control of large titanium alloy components. Therefore, there is an urgent need for a novel hot deformation method for the β-phase region of titanium alloys that can actively control the temperature and strain field distribution and guide the orderly evolution of the regional recrystallization gradient. Summary of the Invention

[0005] The technical problem this invention aims to solve is to address the shortcomings of the prior art by providing a hot deformation method for the β-phase region of large-size TC4 titanium alloy based on temperature-strain field synergistic control. This method employs β-phase region forging and axial diagonal elongation, and actively controls the energy accumulation and recrystallization driving force in different regions by designing multi-directional strain paths and thermo-mechanical coupling process windows. This achieves a shift from "passively accepting gradients" to "actively guiding gradient evolution," significantly improving the microstructure uniformity and process controllability of large-size titanium alloy billets, and solving problems such as excessive radial gradient and uneven recrystallization in existing large-size titanium alloy billets.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for hot deformation of large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control, characterized in that the method includes the following steps: Step 1, β-phase region heating: Heat the large-size TC4 titanium alloy round ingot to the β-phase region temperature range and hold it at that temperature to ensure that the ingot is heated sufficiently; Step 2, Axial upsetting of titanium alloy ingot: The large-sized TC4 titanium alloy round ingot, which was heated and held at the temperature in Step 1, is subjected to axial upsetting hot deformation to obtain the billet; Step 3, Reheating and Holding: Heat the billet obtained in Step 2 to the β phase temperature range and hold it there; Step 4, One-time axial diagonal elongation: After heating and holding the billet in Step 3, rotate the billet 45° along the original ingot axis and perform one-time axial diagonal elongation to obtain a forging billet. Step 5, Secondary Axial Diagonal Lengthening: The primary forging billet obtained in Step 4 is rotated 90° along the original ingot axis and then subjected to secondary axial diagonal lengthening to obtain the secondary forging billet. Step 6, Three-stage axial diagonal elongation: The secondary forging billet obtained in Step 5 is rotated 90° along the original ingot axis and then subjected to three-stage axial diagonal elongation to obtain the TC4 titanium alloy forging billet. The length ratio of the height direction to the side length direction of the TC4 titanium alloy forging billet is 1.5~2.0.

[0007] In the hot deformation of large-size titanium alloy billets, physical boundary conditions determine the intrinsic gradient non-uniformity of the temperature and strain fields. This invention does not attempt to eliminate the gradient, but rather takes the opposite approach, actively designing and utilizing the temperature-strain coupling field to guide the energy storage level and regional recrystallization behavior in different regions, ultimately achieving "overall homogeneity" of the microstructure through the "gradient evolution" of the microstructure. Specifically, this invention first employs a large-deformation axial upsetting hot deformation method in the β-phase region forging. This not only improves the fragmentation degree of the original coarse structure in the main deformation zone of the billet core, but also allows sufficient deformation distortion energy to accumulate in the main deformation zone of the billet core, providing a driving force for the recrystallization process of β grains in this region, preferentially driving the recrystallization of β grains in this region. Subsequently, a three-stage axial diagonal elongation method with smaller deformation amounts is used to effectively control the equivalent strain in the main deformation zone of the billet core, avoiding excessive accumulation of deformation distortion energy that would lead to rapid growth of β recrystallized grains. At the same time, it improves the strain and temperature field distribution in the secondary deformation zone on the side of the billet and the dead deformation zone at the end. The equivalent strain in the secondary deformation zone is significantly improved. Meanwhile, titanium alloy has poor thermal conductivity, and although there is a certain temperature gradient in the secondary deformation zone, it still remains above 1000℃. Therefore, the secondary deformation zone has accumulated sufficient deformation distortion energy to drive the recrystallization of β grains. The equivalent strain in the difficult-to-deform region is also significantly improved, thereby achieving overall homogenization of the microstructure of the TC4 titanium alloy forging billet.

[0008] The above-mentioned method for hot deformation of large-scale TC4 titanium alloy β-phase region based on temperature-strain field synergistic control is characterized in that the diameter of the large-scale TC4 titanium alloy circular ingot in step one is 720mm~1020mm and the single weight is 2000kg~10000kg.

[0009] The aforementioned method for hot deformation of the β-phase region of large-size TC4 titanium alloy based on temperature-strain field synergistic control is characterized in that the heating and holding temperature in step one is 1050℃~1170℃, and the time is the minimum cross-sectional size of the large-size TC4 titanium alloy circular ingot multiplied by the heating coefficient, wherein the unit of time is min, the minimum cross-sectional size is mm, and the heating coefficient is 0.8~1.5. By controlling the heating and holding temperature and time, sufficient heating of the ingot is ensured.

[0010] The above-mentioned method for hot deformation of large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control is characterized in that the deformation amount of axial upsetting hot deformation in step two is 30%~60%, and the strain rate is 20mm / s~60mm / s.

[0011] The above-mentioned method for hot deformation of large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control is characterized in that the heating and holding temperature in step three is 1050℃~1170℃ and the time is 120min~600min.

[0012] The above-mentioned hot deformation method for large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control is characterized in that the deformation amount of the first axial elongation in step four is 10%~20%, and the strain rate is 20mm / s~60mm / s.

[0013] The above-mentioned method for hot deformation of large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control is characterized in that the deformation amount of secondary axial elongation in step five is 10%~30%, and the strain rate is 20mm / s~60mm / s.

[0014] The above-mentioned hot deformation method for large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control is characterized in that the deformation amount of the three axial elongations in step six is ​​5%~15%, and the strain rate is 20mm / s~60mm / s.

[0015] This invention is based on temperature-strain field coordinated control. By controlling the deformation amount of the first, second and third axial elongation, the forging blank at different positions during the axial elongation deformation process reaches the critical strain, achieving uniform deformation and ensuring dynamic recrystallization of β grains in the corresponding region within a controllable temperature range.

[0016] The above-mentioned method for hot deformation of large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control is characterized in that the TC4 titanium alloy square forging billet in step six is ​​subjected to repeated β-phase region heating, axial upsetting, reheating and holding in the furnace, and three axial diagonal elongation processes in steps one to six until the target size is achieved.

[0017] Compared with the prior art, the present invention has the following advantages: 1. This invention first uses axial upsetting in the β phase region forging to ensure dynamic recrystallization of β grains in the main deformation zone of the billet core, achieving rapid refinement and homogenization. Then, it combines this with axial diagonal elongation to avoid high temperature rise and high strain in the main deformation zone of the billet core, thus preventing the rapid growth of dynamically recrystallized β grains. On the other hand, by increasing the diversity of strain paths, it effectively expands the range of high strain zone, improves the internal temperature field distribution of the billet, promotes dislocation multiplication and grain boundary migration, and makes the energy storage distribution more uniform, achieving a more uniform dynamic recrystallized structure and significantly improving the microstructure uniformity of large-size titanium alloys.

[0018] 2. The hot deformation method of the present invention can achieve efficient crushing and uniform refinement of β grains in the β phase region of ultra-large TC4 titanium alloy with a single weight of 2000kg~10000kg on a high-speed forging machine. The average size of the β grains can reach 1mm. At the same time, it optimizes the total number of forging passes in the β phase region from 3~5 passes in the traditional titanium alloy billet forging to 1~2 passes, which significantly reduces processing costs and improves processing efficiency.

[0019] 3. The hot deformation method based on temperature-strain field synergistic control of the present invention is applicable to the control of microstructure uniformity in the β phase region of titanium alloy ingots and billets with diameter ≥800mm and weight ≥5T during hot deformation, and is applicable to the control of microstructure uniformity in the preparation of ultra-large titanium alloy forgings for aviation, aerospace and shipbuilding.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a low-magnification microstructure diagram of the overall cross-section of the TC4 titanium alloy octagonal forging blank prepared in Example 1 of the present invention.

[0022] Figure 2 High-magnification microstructure images of different locations on the cross-section of the TC4 titanium alloy octagonal forging billet prepared in Example 1 of this invention.

[0023] Figure 3 This is a low-magnification microstructure diagram of the overall cross-section of the TC4 titanium alloy octagonal forging blank prepared in Example 2 of the present invention.

[0024] Figure 4 High-magnification microstructure images of different locations on the cross-section of the TC4 titanium alloy octagonal forging billet prepared in Example 2 of this invention. Detailed Implementation

[0025] Example 1 This embodiment includes the following steps: Step 1: Heating in the β-phase region: Place the TC4 titanium alloy circular ingot in a resistance furnace and heat it to 1150℃ for 580 minutes; the TC4 titanium alloy circular ingot has a diameter of 720mm, a single weight of 2100kg, and a β-transformation temperature T. β It is 998℃; Step 2, Axial upsetting of titanium alloy ingot: The TC4 titanium alloy round ingot heated and held in Step 1 is subjected to axial upsetting hot deformation. The upsetting ratio is 2.5, the strain rate is 60mm / s, and the deformation is 60%, resulting in a square billet with a side length of 1005mm. Step 3, Reheating and Holding: Heat the square billet obtained in Step 2 to 1150℃ and hold for 120 minutes; Step 4: Axial diagonal elongation: The square billet after heating and heat preservation in Step 3 is rotated 45° along the original ingot axis and then axially elongated once. The deformation path is diagonal, the deformation amount is 20%, and the strain rate is 60 mm / s, to obtain a forging billet. Step 5, Secondary Axial Diagonal Elongation: The primary forging billet obtained in Step 4 is rotated 90° along the original ingot axis and then subjected to secondary axial elongation. The deformation path is diagonal, the deformation amount is 10%, and the strain rate is 60 mm / s, to obtain the secondary forging billet. Step Six: Three-stage axial diagonal elongation: The secondary forging billet obtained in Step Five is rotated 90° along the original ingot axis and then subjected to three-stage axial elongation. The deformation path is diagonal, the deformation amount is 5%, and the strain rate is 60 mm / s. Finally, an octagonal forging billet of TC4 titanium alloy is obtained, and the length ratio of the height direction to the side length direction of the TC4 titanium alloy octagonal forging billet is 1.5. After forging, air cooling is adopted.

[0026] Figure 1 This is a low-magnification microstructure image of the overall cross-section of the TC4 titanium alloy octagonal forging billet prepared in this embodiment. Figure 1 It can be seen that the β grains in different regions of the cross-section of the octagonal forged billet of TC4 titanium alloy have all achieved equiaxed structure, the as-cast structure has been completely broken, and no obvious coarse columnar crystals were found.

[0027] Figure 2 These are high-magnification microstructure images of different locations on the cross-section of the TC4 titanium alloy octagonal forging billet prepared in this embodiment. Figure 2 The caliber bar is 500 μm, from Figure 2 It can be seen that the cross-sectional microstructure of the TC4 titanium alloy octagonal forging billet is equiaxed β-grain microstructure from the edge to the center of the billet, with the β-grain size ranging from 1 mm to 2 mm.

[0028] Combination Figure 1 and Figure 2 It can be seen that the microstructure of the TC4 titanium alloy forging billet (weight < 5t) after the first forging in the β phase region of this embodiment is basically the same in different regions such as the edge and the core. This indicates that the forging method of the present invention significantly improves the microstructure uniformity and process controllability of large-size titanium alloy forging billets through the coordinated control of temperature and strain field.

[0029] Example 2 This embodiment includes the following steps: Step 1: Heating in the β-phase region: Place the TC4 titanium alloy circular ingot in a resistance furnace and heat it to 1150℃ for 980 min; the diameter of the TC4 titanium alloy circular ingot is 896 mm, the weight is 5110 kg, and the β-transformation temperature T β It is 990℃; Step 2, Axial upsetting of titanium alloy ingot: The TC4 titanium alloy round ingot heated and held in Step 1 is subjected to axial upsetting hot deformation. The upsetting ratio is 1.43, the strain rate is 40mm / s, and the deformation is 30%, resulting in a square billet with a side length of 1040mm. Step 3, Reheating and Holding: Heat the square billet obtained in Step 2 to 1150℃ and hold for 180 minutes; Step 4: Axial diagonal elongation: The square billet after heating and heat preservation in Step 3 is rotated 45° along the original ingot axis and then axially elongated once. The deformation path is diagonal, the deformation amount is 16%, and the strain rate is 40 mm / s, to obtain a forging billet. Step 5, Secondary Axial Diagonal Elongation: The primary forging billet obtained in Step 4 is rotated 90° along the original ingot axis and then subjected to secondary axial elongation. The deformation path is diagonal, the deformation amount is 22%, and the strain rate is 40 mm / s, to obtain the secondary forging billet. Step 6, Three-stage axial diagonal elongation: The secondary forging billet obtained in step 5 is rotated 90° along the original ingot axis and then subjected to three-stage axial elongation. The deformation path is diagonal, the deformation amount is 12%, and the strain rate is 40 mm / s, to obtain the intermediate body of TC4 titanium alloy octagonal forging billet. The intermediate octagonal forging billet of TC4 titanium alloy is subjected to two-fire forging, that is, repeating the β phase region heating, axial upsetting, furnace heating and holding, and three axial elongation processes in steps one to six. The temperature of β phase region heating in step one is 1050℃, and the deformation amount of the second axial elongation in step five is 30%, until the target size is reached. The final TC4 titanium alloy octagonal forging billet has a length ratio of 2.0 in the height direction to the side length direction. After forging, it is air-cooled.

[0030] Figure 3 This is a low-magnification microstructure image of the overall cross-section of the TC4 titanium alloy octagonal forging billet prepared in this embodiment. Figure 3 It can be seen that the β grains in different regions of the cross-section of the octagonal forged billet of TC4 titanium alloy have all achieved equiaxed structure, the as-cast structure has been completely broken, and no obvious coarse columnar crystals were found.

[0031] Figure 4 These are high-magnification microstructure images of different locations on the cross-section of the TC4 titanium alloy octagonal forging billet prepared in this embodiment. Figure 4 The caliber bar is 500 μm, from Figure 4 It can be seen that the cross-sectional microstructure of the TC4 titanium alloy octagonal forging billet is equiaxed β-grain microstructure from the edge to the center of the billet, with the β-grain size ranging from 1 mm to 2 mm.

[0032] Combination Figure 3 and Figure 4 It can be seen that the microstructure of the TC4 titanium alloy forging billet (weight > 5t) after two heat treatments in the β phase region of this embodiment is basically the same in different regions such as the edge and the core. This indicates that the forging method of the present invention significantly improves the microstructure uniformity and process controllability of large-size TC4 titanium alloy forging billets through the coordinated control of temperature and strain fields.

[0033] Example 3 This embodiment includes the following steps: Step 1: Heating in the β-phase region: Place the TC4 titanium alloy circular ingot in a resistance furnace and heat it to 1170℃ for 1530 min; the diameter of the TC4 titanium alloy circular ingot is 1020 mm, the weight is 10300 kg, and the β-transformation temperature T β It is 995℃; Step 2, Axial upsetting of titanium alloy ingot: The TC4 titanium alloy round ingot heated and held in Step 1 is subjected to axial upsetting hot deformation. The upsetting ratio is 2.0, the strain rate is 20mm / s, and the deformation is 50%, resulting in a square billet with a side length of 1278mm. Step 3, Reheating and Holding: Heat the square billet obtained in Step 2 to 1170℃ and hold for 120 minutes; Step 4, One-time axial diagonal elongation: After heating and holding the square billet in Step 3, rotate it 45° along the original ingot axis and then perform one-time axial elongation. The deformation path is diagonal, the deformation amount is 10%, and the strain rate is 20mm / s to obtain a forging billet. Step 5, Secondary Axial Diagonal Elongation: The primary forging billet obtained in Step 4 is rotated 90° along the original ingot axis and then subjected to secondary axial elongation. The deformation path is diagonal, the deformation amount is 15%, and the strain rate is 20 mm / s, to obtain the secondary forging billet. Step 6: Three-stage axial diagonal elongation: The secondary forging billet obtained in Step 5 is rotated 90° along the original ingot axis and then subjected to three-stage axial elongation. The deformation path is diagonal, the deformation amount is 15%, and the strain rate is 20 mm / s. Finally, an octagonal forging billet of TC4 titanium alloy is obtained, and the length ratio of the height direction to the side length direction of the TC4 titanium alloy octagonal forging billet is 1.7. After forging, air cooling is adopted.

[0034] The method in this embodiment can prepare billets for ultra-large TC4 titanium alloy plates, rings, forgings, etc., weighing more than 10 tons.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for hot deformation of large-scale TC4 titanium alloy β-phase region based on temperature-strain field synergistic control, characterized in that, The method includes the following steps: Step 1, β-phase region heating: Heat the large-size TC4 titanium alloy round ingot to the β-phase region temperature range and hold it at that temperature to ensure that the ingot is heated sufficiently; Step 2, Axial upsetting of titanium alloy ingot: The large-sized TC4 titanium alloy round ingot, which was heated and kept at a certain temperature in Step 1, is subjected to axial upsetting hot deformation to obtain the billet; Step 3, Reheating and Holding: Heat the billet obtained in Step 2 to the β phase temperature range and hold it there; Step 4, One-time axial diagonal elongation: After heating and holding the billet in Step 3, rotate the billet 45° along the original ingot axis and perform one-time axial diagonal elongation to obtain a forging billet. Step 5, Secondary Axial Diagonal Lengthening: The primary forging billet obtained in Step 4 is rotated 90° along the original ingot axis and then subjected to secondary axial diagonal lengthening to obtain the secondary forging billet. Step 6, Three-stage axial diagonal elongation: The secondary forging billet obtained in Step 5 is rotated 90° along the original ingot axis and then subjected to three-stage axial diagonal elongation to obtain the TC4 titanium alloy forging billet. The length ratio of the height direction to the side length direction of the TC4 titanium alloy forging billet is 1.5~2.

0.

2. The method for hot deformation of large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control as described in claim 1, characterized in that, The large-size TC4 titanium alloy round ingot mentioned in step one has a diameter of 720mm~1020mm and a single weight of 2000kg~10000kg.

3. The method for hot deformation of large-scale TC4 titanium alloy β-phase region based on temperature-strain field synergistic control according to claim 1, characterized in that, The heating and holding temperature in step one is 1050℃~1170℃, and the time is the minimum cross-sectional size of the large-size TC4 titanium alloy round ingot × the heating coefficient. The unit of time is min, the minimum cross-sectional size is mm, and the heating coefficient is 0.8~1.

5.

4. The method for hot deformation of large-scale TC4 titanium alloy β-phase region based on temperature-strain field synergistic control according to claim 1, characterized in that, The deformation amount of the axial upsetting hot deformation in step two is 30%~60%, and the strain rate is 20mm / s~60mm / s.

5. The method for hot deformation of large-scale TC4 titanium alloy β-phase region based on temperature-strain field synergistic control according to claim 1, characterized in that, The heating and heat preservation temperature in step three is 1050℃~1170℃, and the time is 120min~600min.

6. The method for hot deformation of large-scale TC4 titanium alloy β-phase region based on temperature-strain field synergistic control according to claim 1, characterized in that, The deformation amount of the axial elongation in step four is 10%~20%, and the strain rate is 20mm / s~60mm / s.

7. The method for hot deformation of large-scale TC4 titanium alloy β-phase region based on temperature-strain field synergistic control according to claim 1, characterized in that, The deformation amount of the secondary axial elongation in step five is 10%~30%, and the strain rate is 20mm / s~60mm / s.

8. The method for hot deformation of large-scale TC4 titanium alloy β-phase region based on temperature-strain field synergistic control according to claim 1, characterized in that, The deformation amount of the three axial elongations in step six is ​​5%~15%, and the strain rate is 20mm / s~60mm / s.

9. The method for hot deformation of large-size TC4 titanium alloy β-phase region based on temperature-strain field synergistic control according to claim 1, characterized in that, Repeat the β-phase region heating, axial upsetting, reheating and holding in the furnace, and three axial diagonal elongation processes in steps one through six for the TC4 titanium alloy square forging billet in step six until the target size is achieved.

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