A method for manufacturing a TC8-1 titanium alloy disc forging

Abstract

The present application relates to a kind of preparation methods of TC8-1 titanium alloy disc forgings, belong to titanium alloy forging technical field, at least solve the uniformity of the organization of disc forging prepared by existing method and batch consistency is insufficient;Small specification disc forging forming difficulty is big;One of the problems of unreasonable heat treatment process and strength toughness matching.It includes using TC8-1 titanium alloy bar as raw material, according to its height-diameter ratio, selects blanking mode, obtains disc forging blank;According to the thickness of disc forging blank, select disc forging forming mode, obtain disc forging blank after forging;Disc forging blank is subjected to double isothermal annealing treatment, and titanium alloy disc forging is obtained;Double isothermal annealing treatment includes heating disc forging blank to the first heavy annealing temperature and holding, converter to the second heavy annealing temperature and holding, fan cooling is used in converter process, and converter time is ≤10min.The TC8-1 titanium alloy disc forging prepared by the present application has high uniformity of organization and batch consistency.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy forging technology, and in particular to a method for preparing TC8-1 titanium alloy disc forgings. Background Technology

[0002] TC8-1 titanium alloy is a high-performance martensitic two-phase titanium alloy belonging to the Ti-Al-Mo-Sn-Zr-Si alloy system. Its nominal composition is Ti-6.3Al-1Sn-1Zr-3.3Mo-0.18Si. It exhibits high strength, good plasticity, and toughness at both room and high temperatures. TC8-1 titanium alloy can withstand long-term service temperatures up to 500℃ and possesses excellent thermal stability, hot workability, and damage tolerance. It is widely used both domestically and internationally in forgings such as multi-stage compressor disks and integral bladed disks for aero-engines.

[0003] The existing methods for preparing TC8-1 titanium alloy disc forgings lack a fully integrated design for the entire process. There is a lack of unified and matched control over the heat treatment temperature, deformation temperature, and bar forging temperature of the forgings, resulting in insufficient uniformity of microstructure and batch consistency of the forgings. For small-sized forgings, the problems of easy sticking to the die and large tonnage in the die forging method are not considered, which makes it difficult to form small-sized forgings. The thermal stability of the engine during long-term use is not taken into account, resulting in an unreasonable match between heat treatment process and strength and toughness in the preparation of titanium alloy disc forgings. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a method for preparing TC8-1 titanium alloy disc forgings, at least to solve one of the following problems existing in the preparation methods of TC8-1 titanium alloy disc forgings: 1. The microstructure uniformity and batch consistency of disc forgings prepared by existing TC8-1 titanium alloy disc forging preparation methods are insufficient; 2. Existing TC8-1 titanium alloy disc forging preparation methods are difficult to form small-sized disc forgings; 3. Existing TC8-1 titanium alloy disc forging preparation methods have unreasonable heat treatment processes and strength-toughness matching.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] This invention provides a method for preparing TC8-1 titanium alloy disc forgings, comprising the following steps:

[0007] S1: Using TC8-1 titanium alloy bars as raw materials, the billet preparation method is selected according to the height-to-diameter ratio of TC8-1 titanium alloy bars, and the disc forging billet is obtained after billet preparation.

[0008] S2: Select the forging method of the disc forging according to the thickness of the disc forging blank, and obtain the disc forging blank after forging;

[0009] S3: The disc forging blank is subjected to double isothermal annealing heat treatment to obtain TC8-1 titanium alloy disc forging;

[0010] In step S3, the double isothermal annealing heat treatment includes heating the disc forging blank to the first annealing holding temperature T1 and holding it there, then converting it to the second annealing holding temperature T2 and holding it there. During the converter process, a fan is used for cooling, and the converter time is ≤10min.

[0011] Further, in step S1, the height-to-diameter ratio of the TC8-1 titanium alloy bar is ≤3, and the blank is prepared by machining.

[0012] The height-to-diameter ratio of the TC8-1 titanium alloy bar is >3. The TC8-1 titanium alloy bar is heated to Tβ-80℃ to the forging temperature T. 模锻 Interval billet preparation;

[0013] The T β -80℃ refers to the β-phase transformation point T of TC8-1 titanium alloy bars. β below 80℃.

[0014] Furthermore, in step S2, the thickness of the disc forging blank is >35mm, and isothermal die forging is selected;

[0015] The thickness of the disc forging blank is ≤35mm, and axial closed rolling forging is selected.

[0016] Furthermore, during the isothermal forging process, the forging temperature T is... 模锻 The mold temperature is 950–960℃, and the deformation speed is 0.3–0.8 mm / s.

[0017] Furthermore, during the isothermal forging process, the following conditions must also be met:

[0018] Forging temperature T 模锻 ≥TC8-1 titanium alloy bar raw material final forging temperature, die forging temperature T 模锻 ≤ First annealing holding temperature T1.

[0019] Furthermore, during the axial closed-circuit rolling forging, the forging heating temperature is 950–960°C.

[0020] Furthermore, during the axial closed rolling forging process, the upper die feed rate is 3-5 mm / r per revolution, the upper die feed speed is 2-4 mm / s, and the upper die tilt angle is 6-10°.

[0021] Furthermore, in step S3, the first annealing holding temperature T1 satisfies: T 模锻 <T1<T β -30℃;

[0022] Where T1 is the first annealing holding temperature;

[0023] T 模锻 Forging temperature;

[0024] T β -30℃ refers to the β-phase transformation point T of TC8-1 titanium alloy bars. β below 30℃.

[0025] Furthermore, in step S3, the first annealing holding time is 1 to 4 hours.

[0026] Furthermore, the second annealing holding temperature T2 is 570-600℃, and the holding time is 1-2 hours.

[0027] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0028] 1. The forging method of the TC8-1 titanium alloy disc forging of the present invention achieves coordinated matching control of the forging temperature, forging temperature and annealing heat treatment temperature of the TC8-1 titanium alloy bar raw material by setting the final forging temperature of the TC8-1 titanium alloy bar raw material ≤ the die forging temperature and the first-stage annealing holding temperature ≥ the die forging temperature. Through the coordinated control of the forging temperature, forging temperature and annealing heat treatment temperature of the TC8-1 titanium alloy bar raw material, the uniformity of microstructure and batch consistency of forgings of the same drawing number are improved.

[0029] 2. In view of the characteristics of TC8-1 disc forgings, which have many types and large variations in structural dimensions, this invention selects isothermal die forging for forging when the thickness of the disc forging blank is >35mm; and selects axial closed rolling forging for forging when the thickness of the disc forging blank is ≤35mm. This achieves stable forming of TC8-1 disc forgings and avoids the problems of thin-section thick forgings sticking to the die and inadequate dimensional accuracy control that may occur when using isothermal forging process for thin titanium alloy disc forging blanks with small thickness.

[0030] 3. This invention uses isothermal annealing heat treatment on the disc forging blank and fan cooling during the converter process to ensure the strength of the disc forging while improving its thermal stability and impact performance. The TC8-1 titanium alloy disc forging prepared by this invention has high microstructure uniformity, and the rating range is ≤1 according to the rating requirements of GJB 2218A-2008.

[0031] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0032] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0033] Figure 1a The shape of the forging blank in Embodiment 1 of the present invention;

[0034] Figure 1b The shape of the disc forging blank is shown in Embodiment 1 of the present invention;

[0035] Figure 2 The shape of the forging blank in Embodiment 2 of the present invention;

[0036] Figure 3 The shape of the forging blank in Embodiment 3 of the present invention;

[0037] Figure 4a The shape of the disc forging blank is shown in Embodiment 2 of the present invention;

[0038] Figure 4b The shape of the disc forging blank in Embodiment 3 of the present invention;

[0039] Figure 5a The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in Embodiment 1 of the present invention;

[0040] Figure 5b The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in Embodiment 2 of the present invention;

[0041] Figure 5c The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in Example 3 of the present invention;

[0042] Figure 5d The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in Example 4 of this invention;

[0043] Figure 5e The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in Example 5 of the present invention;

[0044] Figure 6 The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in Comparative Example 1 of this invention is shown. Detailed Implementation

[0045] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0046] This invention provides a method for preparing TC8-1 titanium alloy disc forgings, comprising the following steps:

[0047] S1: Using TC8-1 titanium alloy bars as raw materials, the billet preparation method is selected according to the height-to-diameter ratio of TC8-1 titanium alloy bars, and the disc forging billet is obtained after billet preparation.

[0048] TC8-1 titanium alloy bar heated to T β -80℃ (i.e., the β phase transition point T) β (below 80℃) ~ forging temperature (T) 模锻 The blanking process is completed by either interval blanking or direct machining to obtain the disc forging blank;

[0049] It should be noted that when the height-to-diameter ratio of the TC8-1 titanium alloy bar is ≤3, the bar length is relatively short compared to its diameter, making it easier to control dimensional accuracy during machining. Therefore, direct machining is used to complete the blanking process. When the height-to-diameter ratio of the TC8-1 titanium alloy bar is >3, the bar with a large height-to-diameter ratio is more prone to problems such as folding, tilting, and unstable bending during forging. Heating can reduce the material's deformation resistance and improve its plasticity, thus making it easier to achieve blanking. Therefore, heating the TC8-1 titanium alloy bar to T... β -80℃ (i.e., the β phase transition point T) β (below 80℃) ~ forging temperature (T) 模锻 For the blanking process, the holding time is calculated based on the thickness of the bar section and determined according to 0.6 to 0.8 min / mm.

[0050] S2: Select the forging method of the disc forging according to the thickness of the disc forging blank, and obtain the disc forging blank after forging;

[0051] The preparation method for forging the disc forging is determined based on the thickness of the disc forging blank: if the thickness of the disc forging blank is >35mm, isothermal die forging is selected; if the thickness of the disc forging blank is ≤35mm, axial closed rolling is selected.

[0052] Specifically, in isothermal forging, the forging temperature (T) 模锻 The mold temperature is 950-960℃ to reduce temperature difference and thermal stress; the deformation speed is 0.3-0.8mm / s. Within this deformation speed range, the flow and deformation of the blank are uniform. If the deformation speed is lower than 0.3mm / s, the blank deformation is more uniform, reducing internal defects, but production efficiency will decrease. If the deformation speed is higher than 0.8mm / s, production efficiency can be improved. However, excessively fast deformation can easily cause internal defects, requiring more precise control to avoid defects, resulting in high cost and energy consumption. This invention controls the deformation speed at 0.3-0.8mm / s.

[0053] At the same time, when using isothermal forging, the forging temperature (T) must also be met. 模锻 )≥TC8-1 titanium alloy bar raw material final forging temperature, die forging temperature (T) 模锻 )≤ the first-stage annealing temperature (T1) in the subsequent annealing steps.

[0054] Specifically, when using axial closed-circuit rolling forging, the forging heating temperature (i.e., the die forging temperature (T-die forging)) is 950–960℃, the upper die feed per revolution is 3–5 mm / r, the upper die feed speed is 2–4 mm / s, and the upper die inclination angle is 6–10°. It should be noted that when the thickness of the titanium alloy disc forging blank is small, due to the low dimensional accuracy, it is prone to problems such as large under-pressure, large forming tonnage, and film adhesion, affecting the forging quality and making small-size forming difficult. Axial closed-circuit rolling forging has high material utilization, high dimensional accuracy, and high surface quality of formed forgings; however, its intense deformation easily leads to problems such as stress concentration, uneven deformation, and poor metal flow. The titanium alloy disc forging billet of this invention is produced by axial closed-circuit rolling forging. The forging heating temperature is set at 945–965°C, which is within the β-phase region of the titanium alloy. At this temperature, the grain structure of the titanium alloy is relatively stable and it has high deformation capacity, effectively reducing stress concentration and crack initiation during forging. Simultaneously, it ensures that the titanium alloy billet maintains good fluidity and uniform deformation capacity during forging, avoiding uneven local deformation or excessively high deformation resistance caused by excessively low temperatures. The upper die feed rate is 3–5 mm / r, ensuring sufficient deformation without causing excessively vigorous metal flow, thus effectively controlling the stability of the deformation process. The upper die feed speed is 2-4 mm / s, which allows the metal to flow more evenly during deformation, avoiding severe local deformation and stress concentration caused by excessive speed. The upper die tilt angle is 6-10°. The design of the upper die tilt angle can change the flow direction and deformation path of the metal. An appropriate tilt angle can guide the metal to flow more evenly and reduce local stress concentration. This invention sets the upper die tilt angle to 6-10° to guide the metal flow direction, making the deformation process more even and avoiding uneven metal flow and stress concentration caused by vertical downward pressure. It also reduces the risk of severe deformation and cracking caused by uneven metal flow, thus effectively overcoming the defect of severe deformation. By rationally controlling process parameters such as heating temperature, feed per revolution of the upper die, feed speed of the upper die, and tilt angle of the upper die, the titanium alloy billet can achieve more uniform deformation during axial closed rolling forging. This avoids problems such as stress concentration, crack initiation, and uneven metal flow caused by severe deformation. Through the synergistic effect of these parameters, the forging process is more stable, significantly improving the forming quality of the forgings. It also avoids the problems of thin-section forgings sticking to the die and inadequate dimensional accuracy control that may occur when using isothermal forging processes for thin titanium alloy disc forging billets with small thicknesses.

[0055] S3: The disc forging blank is subjected to double isothermal annealing heat treatment to obtain TC8-1 titanium alloy disc forging;

[0056] The disc forging blank obtained in step S2 is subjected to isothermal annealing heat treatment, which includes heating the disc forging blank to the first annealing holding temperature (T1) and holding it there, and then converting it to the second annealing holding temperature (T2) and holding it there.

[0057] Specifically, the first annealing holding temperature T1 satisfies: T 模锻 <T1<T β -30℃, holding time 1~4h, converter time ≤10min, supplemented by fan cooling; the second annealing holding temperature T2 meets: 570-600℃, holding time 1~2h, and air cooling to room temperature after holding.

[0058] It should be noted that during the first annealing and heat treatment process, the holding temperature T1 meets the requirements of T... 模锻 <T1<T β -30℃ avoids overheating and grain coarsening, allowing for partial phase transformation and stress release without grain coarsening. Partial phase transformation softens the material, facilitating subsequent processing, while preserving its microstructure and strength. During the converter process, the material undergoes temperature changes; controlling the converter time to ≤10min reduces temperature gradients caused by rapid temperature changes, preventing new thermal stresses and ensuring the stability of the material's microstructure and properties. Fan cooling is used during the converter interval; rapid cooling helps refine the grains, which improves the material's strength and toughness, as well as its thermal stability and impact resistance. The second annealing heat treatment, with a holding temperature T2 of 570-600℃ and a holding time of 1-2 hours, results in a more reasonable distribution of the α and β phases, optimizing the phase structure. This further releases residual stress within the material, while also making the microstructure more uniform and stable. After the second annealing, air cooling is used, which allows the internal stress of the material to gradually balance during the cooling process, reducing defects such as cracks and microstructural changes caused by excessively rapid cooling, and ensuring the stability and consistency of the material's performance.

[0059] The forging method of the TC8-1 titanium alloy disc forging of the present invention involves setting the final forging temperature of the TC8-1 titanium alloy bar stock to be ≤ the die forging temperature (T). 模锻 The first-stage annealing holding temperature T1 ≥ the forging temperature (T) 模锻This technology achieves coordinated control of the forging temperature, die forging temperature, and annealing heat treatment temperature of TC8-1 titanium alloy bars. By coordinating these temperatures, the consistency of microstructure between batches of forgings with the same drawing number is improved. By increasing the first-stage annealing holding temperature T1, a good recrystallized microstructure can be obtained, improving the microstructure consistency of forgings with different drawing numbers. Through isothermal annealing heat treatment, fan cooling is used during the converter process, ensuring the strength of the disc forgings while improving thermal stability and impact performance.

[0060] The microstructure of the TC8-1 titanium alloy disc forging prepared by this invention is a uniform bimodal structure, mainly consisting of equiaxed primary α phases distributed on a matrix of β-transformation structure (fine lamellar α phase).

[0061] The TC8-1 titanium alloy disc forgings prepared by this invention exhibit high microstructure uniformity, with a rating range ≤1 according to the rating requirements of GJB 2218A-2008. Before heat exposure, the TC8-1 titanium alloy disc forgings prepared by this invention have a tensile strength ≥1010 MPa (e.g., 1012-1021 MPa) and a specified non-proportional elongation strength R. p0.2 ≥905MPa (e.g., 909-915MPa), elongation after fracture ≥17% (e.g., 17.3-19.6%), reduction of area ≥51% (e.g., 51.2-56.4%); after heat exposure at 500℃ for 100h, tensile strength ≥1020MPa (e.g., 1020-1027MPa), specified non-proportional elongation strength R p0.2 ≥910MPa (e.g., 910-919MPa), elongation after fracture ≥17% (e.g., 17.4-19%), reduction of area ≥43% (e.g., 43-52.6%); the absolute value of the difference in tensile strength between TC8-1 titanium alloy disc forgings before and after heat exposure ≤7MPa (e.g., 2-7MPa), and the specified non-proportional elongation strength R p0.2 The absolute value of the difference in elongation after fracture is ≤10MPa (e.g., 0-10MPa), the absolute value of the difference in elongation after fracture is ≤0.6% (e.g., 0.1-0.6%), and the absolute value of the difference in reduction of area is ≤14% (e.g., 1.4-13.1%). The room temperature impact mechanical properties KU2 of the TC8-1 titanium alloy disc forgings prepared by this invention are ≥50J (e.g., 54.9-63.3J), and the room temperature impact bending toughness K... CT ≥40J / cm 2 (e.g., 44-48 J / cm) 2 ).

[0062] Example 1

[0063] The TC8-1 titanium alloy disc forging to be prepared in this embodiment has dimensions of Ф360×110mm, and includes the following steps:

[0064] S1: Using TC8-1 titanium alloy bars as raw material, the billet preparation method is selected based on the height-to-diameter ratio of the TC8-1 titanium alloy bars, and the resulting disc forging billet is obtained after billet preparation.

[0065] The TC8-1 titanium alloy bar has dimensions of Ф180×280mm and a β phase transformation temperature T. β The forging temperature is 1000℃ (T). 模锻 The final forging temperature for TC8-1 titanium alloy bars is 940℃, while the final forging temperature is 950℃.

[0066] Because the TC8-1 titanium alloy bar used has a height-to-diameter ratio of 1.56 (i.e., 280mm / 180mm), direct machining was used to cut the material and create positioning recesses to obtain the disc forging blank, such as... Figure 1a As shown.

[0067] S2: Select the forging method for the disc forging based on the thickness of the disc forging blank, and obtain the disc forging blank after forging:

[0068] Because the thickness of the disc forging blank is 84mm, which is greater than 35mm, isothermal die forging is selected; among which, the die forging temperature (T) 模锻 The mold temperature is 950℃, which meets the forging temperature T. 模锻 (950℃)≥TC8-1 titanium alloy bar raw material final forging temperature 940℃, die forging temperature T 模锻 (950℃)≤ the first-stage annealing temperature T1 (960℃) in the subsequent annealing steps;

[0069] The deformation rate is 0.5 mm / s, and the forging process yields a disc forging blank, such as... Figure 1b As shown.

[0070] S3: The disc forging blank is subjected to double isothermal annealing heat treatment to obtain TC8-1 titanium alloy disc forging:

[0071] Isothermal annealing heat treatment includes heating the disc forging blank to the first annealing holding temperature (T1) and holding it in a converter to the second annealing holding temperature (T2).

[0072] The first annealing holding temperature T1 is 960℃, which satisfies: T 模锻 (950℃)<T1(960℃)<T β -30℃ (970℃), holding time 3h, converter time 8min, supplemented by fan cooling; second annealing holding temperature T2 is 590℃, holding time 2h, after holding to air cooling to room temperature, to obtain TC8-1 titanium alloy disc forging. Figure 5aThe microstructure of the core and edge of the TC8-1 titanium alloy disc forging in this embodiment is a uniform bimodal structure, with a rating range ≤1 according to the rating requirements of GJB 2218A-2008.

[0073] Example 2

[0074] The TC8-1 titanium alloy disc forging to be prepared in this embodiment has dimensions of Ф400×70mm, and includes the following steps:

[0075] S1: Using TC8-1 titanium alloy bars as raw material, the billet preparation method is selected based on the height-to-diameter ratio of the TC8-1 titanium alloy bars, and the resulting disc forging billet is obtained after billet preparation.

[0076] The TC8-1 titanium alloy bar has dimensions of Ф180×300mm and a β phase transformation temperature T. β The forging temperature is 1000℃ (T). 模锻 The final forging temperature for TC8-1 titanium alloy bars is 940℃, while the final forging temperature is 950℃.

[0077] Because the TC8-1 titanium alloy bar used has a height-to-diameter ratio of 1.67 (i.e., 300mm / 180mm), direct machining was used to cut the material and create positioning recesses to obtain the disc forging blank, such as... Figure 2 As shown.

[0078] S2: Select the forging method for the disc forging based on the thickness of the disc forging blank, and obtain the disc forging blank after forging:

[0079] Because the thickness of the disc forging blank is 62mm, which is greater than 35mm, isothermal die forging is selected; among which, the die forging temperature (T) 模锻 The mold temperature is 950℃, which meets the forging temperature T. 模锻 (950℃)≥TC8-1 titanium alloy bar raw material final forging temperature 940℃, die forging temperature T 模锻 (950℃)≤ the first-stage annealing temperature T1 (960℃) in the subsequent annealing steps;

[0080] The deformation rate is 0.6 mm / s, and the forging process yields a disc forging blank, such as... Figure 4a As shown.

[0081] S3: The disc forging blank is subjected to double isothermal annealing heat treatment to obtain TC8-1 titanium alloy disc forging:

[0082] Isothermal annealing heat treatment includes heating the disc forging blank to the first annealing holding temperature (T1) and holding it in a converter to the second annealing holding temperature (T2).

[0083] The first annealing holding temperature T1 is 960℃, which satisfies: T模锻 (950℃)<T1(960℃)<T β -30℃ (970℃), holding time 2h, converter time 6min, supplemented by fan cooling; the second annealing holding temperature T2 is 580℃, holding time 1.5h, after holding, air cooling to room temperature, to obtain TC8-1 titanium alloy disc forging. Figure 5b The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in this embodiment is a uniform bimodal structure, with a rating range ≤1 according to the rating requirements of GJB 2218A-2008.

[0084] Example 3

[0085] The TC8-1 titanium alloy disc forging to be prepared in this embodiment has dimensions of Ф400×70mm, and includes the following steps:

[0086] S1: Using TC8-1 titanium alloy bars as raw material, the billet preparation method is selected based on the height-to-diameter ratio of the TC8-1 titanium alloy bars, and the resulting disc forging billet is obtained after billet preparation.

[0087] The TC8-1 titanium alloy bar has dimensions of Ф260×150mm and a β phase transformation temperature T. β The forging temperature is 1005℃ (T). 模锻 The final forging temperature for TC8-1 titanium alloy bars is 945℃, while the final forging temperature is 950℃.

[0088] Because the TC8-1 titanium alloy bar used has a height-to-diameter ratio of 0.58 (i.e., 150mm / 260mm), direct machining is used to cut the material and create positioning recesses to obtain the disc forging blank, such as... Figure 3 As shown.

[0089] S2: Select the forging method for the disc forging based on the thickness of the disc forging blank, and obtain the disc forging blank after forging:

[0090] Because the thickness of the disc forging blank is 65mm, which is greater than 35mm, isothermal die forging is selected; among which, the die forging temperature (T) 模锻 The mold temperature is 950℃, which meets the forging temperature T. 模锻 (950℃)≥TC8-1 titanium alloy bar raw material final forging temperature 945℃, die forging temperature T 模锻 (950℃)≤ the first-stage annealing temperature T1 (960℃) in the subsequent annealing steps;

[0091] The deformation rate is 0.4 mm / s, and the forging process yields a disc forging blank, such as... Figure 4b As shown.

[0092] S3: The disc forging blank is subjected to double isothermal annealing heat treatment to obtain TC8-1 titanium alloy disc forging:

[0093] Isothermal annealing heat treatment includes heating the disc forging blank to the first annealing holding temperature (T1) and holding it in a converter to the second annealing holding temperature (T2).

[0094] The first annealing holding temperature T1 is 960℃, which satisfies: T 模锻 (950℃)<T1(960℃)<T β -30℃ (975℃), holding time 2h, converter time 6min, supplemented by fan cooling; second annealing holding temperature T2 is 580℃, holding time 1.5h, after holding to room temperature by air cooling, to obtain TC8-1 titanium alloy disc forging. Figure 5c The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in this embodiment is a uniform bimodal structure, with a rating range ≤1 according to the rating requirements of GJB 2218A-2008.

[0095] Example 4

[0096] The TC8-1 titanium alloy disc forging to be prepared in this embodiment has dimensions of Ф350×34mm, and includes the following steps:

[0097] S1: Using TC8-1 titanium alloy bars as raw material, the billet preparation method is selected based on the height-to-diameter ratio of the TC8-1 titanium alloy bars, and the resulting disc forging billet is obtained after billet preparation.

[0098] The TC8-1 titanium alloy bar has dimensions of Ф260×80mm and a β phase transformation temperature T. β The final forging temperature for TC8-1 titanium alloy bars is 945℃, with a maximum temperature of 1005℃.

[0099] Because the height-to-diameter ratio of the TC8-1 titanium alloy bar used is 0.31 (i.e., 80mm / 260mm), direct machining is used to cut the material and create a positioning recess to obtain the disc forging blank.

[0100] S2: Select the forging method for the disc forging based on the thickness of the disc forging blank, and obtain the disc forging blank after forging:

[0101] Since the thickness of the disc forging blank is 34mm, which is less than 35mm, the axial closed rolling method is selected for forging. The forging heating temperature is 955℃, the upper die feed rate is 4mm / r per revolution, the upper die feed speed is 3mm / s, and the upper die inclination angle is 8°. After forging, a disc forging blank is obtained.

[0102] S3: The disc forging blank is subjected to double isothermal annealing heat treatment to obtain TC8-1 titanium alloy disc forging:

[0103] Isothermal annealing heat treatment includes heating the disc forging blank to the first annealing holding temperature (T1) and holding it in a converter to the second annealing holding temperature (T2).

[0104] The first annealing holding temperature T1 is 965℃, satisfying: T 模锻 (i.e., the forging heating temperature during axial closed-circuit forging is 955℃) < T1 (965℃) < T β -30℃ (975℃), holding time 1.5h, converter time 4min, supplemented by fan cooling; second annealing holding temperature T2 is 570℃, holding time 1h, after holding to air cooling to room temperature, to obtain TC8-1 titanium alloy disc forging. Figure 5d The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in this embodiment is a uniform bimodal structure, with a rating range ≤1 according to the rating requirements of GJB 2218A-2008.

[0105] Example 5

[0106] The TC8-1 titanium alloy disc forging to be prepared in this embodiment has dimensions of Ф400×25mm, and includes the following steps:

[0107] S1: Using TC8-1 titanium alloy bars as raw material, the billet preparation method is selected based on the height-to-diameter ratio of the TC8-1 titanium alloy bars, and the resulting disc forging billet is obtained after billet preparation.

[0108] The TC8-1 titanium alloy bar has dimensions of Ф260×80mm and a β phase transformation temperature T. β The final forging temperature for TC8-1 titanium alloy bars is 945℃, with a maximum temperature of 1005℃.

[0109] Because the height-to-diameter ratio of the TC8-1 titanium alloy bar used is 0.31 (i.e., 80mm / 260mm), direct machining is used to cut the material and create a positioning recess to obtain the disc forging blank.

[0110] S2: Select the forging method for the disc forging based on the thickness of the disc forging blank, and obtain the disc forging blank after forging:

[0111] Since the thickness of the disc forging blank is 25mm, which is less than 35mm, the axial closed rolling method is selected for forging. The forging heating temperature is 958℃, the upper die feed rate is 5mm / r per revolution, the upper die feed speed is 4mm / s, and the upper die inclination angle is 6°. After forging, a disc forging blank is obtained.

[0112] S3: The disc forging blank is subjected to double isothermal annealing heat treatment to obtain TC8-1 titanium alloy disc forging:

[0113] Isothermal annealing heat treatment includes heating the disc forging blank to the first annealing holding temperature (T1) and holding it in a converter to the second annealing holding temperature (T2).

[0114] The first annealing holding temperature T1 is 965℃, satisfying: T 模锻 (i.e., the forging heating temperature during axial closed-circuit forging is 958℃) < T1 (965℃) < T β -30℃ (975℃), holding time 1.5h, converter time 4min, supplemented by fan cooling; second annealing holding temperature T2 is 570℃, holding time 1h, after holding to air cooling to room temperature, to obtain TC8-1 titanium alloy disc forging. Figure 5e The microstructure of the core and edge of the TC8-1 titanium alloy disc forging in this embodiment is a uniform bimodal structure, with a rating range ≤1 according to the rating requirements of GJB 2218A-2008.

[0115] Comparative Example 1

[0116] The TC8-1 titanium alloy disc forging prepared in this comparative example has dimensions of Ф400×70mm. The TC8-1 titanium alloy bar material and preparation process used are similar to those in Example 2, except that in step S3, the first annealing holding temperature T1 is 930℃, which is lower than the die forging temperature T. 模 Forging does not satisfy: T forging (950℃) < T1 < T β -30℃ (970℃).

[0117] Figure 6 The microstructure of the core and edge of the TC8-1 titanium alloy disc forging is shown in the figure. As can be seen from the figure, a three-phase mixed structure appears in the microstructure, with equiaxed α phase, coarse lamellar α phase formed by post-forging cooling, and fine lamellar α phase formed by isothermal annealing cooling. It is extremely difficult to control the microstructure uniformity of the forging, and the microstructure uniformity is poor. According to the rating requirements of GJB 2218A-2008, the rating range is >1.

[0118] Comparative Example 2

[0119] The TC8-1 titanium alloy disc forgings prepared in this comparative example have dimensions of Ф400×70mm.

[0120] The TC8-1 titanium alloy bar raw material and preparation process used are similar to those in Example 2, except that:

[0121] S3: The disc forging blank undergoes double annealing heat treatment to obtain the TC8-1 titanium alloy disc forging.

[0122] The first annealing holding temperature T1 is 960℃, which satisfies: T 模锻 (950℃)<T1(960℃)<Tβ -30℃ (970℃), holding time 1.5h, air cooling; second annealing holding temperature T2 is 580℃, holding time 1h, after holding to room temperature, to obtain TC8-1 titanium alloy disc forging.

[0123] As can be seen from Table 1, although the TC8-1 titanium alloy disc forging prepared in this comparative example has better forging strength than that in Example 2, its room temperature tensile plasticity (elongation and reduction of area) decreased significantly after being exposed at 500℃ for 100h, indicating poor thermal stability.

[0124] Comparative Example 3

[0125] The TC8-1 titanium alloy disc forgings prepared in this comparative example have dimensions of Ф400×70mm.

[0126] The TC8-1 titanium alloy bar raw material and preparation process used are similar to those in Example 2, except that:

[0127] S3: The disc forging blank undergoes double annealing heat treatment to obtain the TC8-1 titanium alloy disc forging.

[0128] The first annealing holding temperature T1 is 960℃, which satisfies: T 模锻 (950℃)<T1(960℃)<T β -30℃ (970℃), holding time 2h, water cooling; second annealing holding temperature T2 is 535℃, holding time 1h, after holding, air cooling to room temperature, to obtain TC8-1 titanium alloy disc forging.

[0129] As can be seen from Table 1, although the TC8-1 titanium alloy disc forging prepared in this comparative example has better forging strength than that of Example 2, its room temperature tensile plasticity (elongation and reduction of area) decreased significantly after being exposed at 500℃ for 100h, indicating poor thermal stability.

[0130] Comparative Example 4

[0131] The TC8-1 titanium alloy disc forging to be prepared in this comparative example has dimensions of Ф400×25mm.

[0132] The TC8-1 titanium alloy bar raw material and preparation process used are similar to those in Example 5, except that in step S2, because the thickness of the disc forging billet is 25mm, which is less than 35mm, axial closed rolling forging is not used; instead, isothermal die forging is employed. The forging temperature (T...) 模 The forging temperature and die temperature are 950℃, satisfying the requirement that the forging temperature Tforging(950℃)≥TC. The final forging temperature of the 8-1 titanium alloy bar raw material is 945℃, and the forging temperature Tforging... 模锻 (950℃)≤ the first-stage annealing temperature T1 (965℃) in the subsequent annealing steps.

[0133] In the preparation process of this comparative example, the forging continuously stuck to the die, making it difficult for the robot to assist in removing the forging from the die. The clamping process easily caused deformation of the thin forging. In addition, due to the prolonged cooling of the forging in the die, the microstructure of the forging was poor, with a dual-state microstructure consisting of coarse and fine lamellar α phases. The TC8-1 titanium alloy disc forging prepared in this comparative example had a rating range >1 according to the rating requirements of GJB2218A-2008.

[0134] Comparative Example 5

[0135] The TC8-1 titanium alloy disc forging to be prepared in this comparative example has dimensions of Ф400×25mm.

[0136] The TC8-1 titanium alloy bar material and preparation process used are similar to those in Example 5, except that in step S2, since the thickness of the disc forging blank is 25mm, which is less than 35mm, an axial closed rolling method is selected for forging; the forging heating temperature is 958℃, the upper die feed per revolution is 6mm / r, the upper die feed speed is 5mm / s, the upper die inclination angle is 5°, and a disc forging blank is obtained after forging.

[0137] In the axial closed-circuit rolling forging process of the TC8-1 titanium alloy disc forging in this comparative example, the feed per revolution of the upper die and the feed speed of the upper die are relatively large, exceeding the range required by this invention; the inclination angle of the upper die is relatively small, lower than the requirements of this invention. As a result, the disc forging billet undergoes severe deformation, stress concentration, and uneven metal flow during the forging process. The final TC8-1 titanium alloy disc forging has poor microstructure uniformity, with some areas exhibiting a bimodal structure and the severely deformed areas exhibiting a trimodal mixed structure. According to the rating requirements of GJB2218A-2008, the rating range is >1.

[0138] The TC8-1 titanium alloy disc forgings prepared in the examples and comparative examples were heat-exposed at 500℃ for 100 h. The mechanical properties of the TC8-1 titanium alloy disc forgings in the examples and comparative examples after heat exposure at room temperature and 500℃ for 100 h are shown in Table 1. As can be seen from the table, the room temperature tensile properties of the TC8-1 titanium alloy disc forgings in the examples did not change significantly before and after heat exposure, exhibiting high thermal stability (room temperature tensile properties after 500℃ heat exposure for 100 h) and impact properties. The thermal stability of the comparative examples decreased compared to the corresponding examples.

[0139] Table 1. Mechanical properties of TC8-1 titanium alloy disc forgings before and after heat exposure in the examples and comparative examples.

[0140]

[0141] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a TC8-1 titanium alloy disc forging, characterized in that, Includes the following steps: S1: Using TC8-1 titanium alloy bars as raw materials, the billet preparation method is selected according to the height-to-diameter ratio of TC8-1 titanium alloy bars, and the disc forging billet is obtained after billet preparation. S2: Select the forging method of the disc forging according to the thickness of the disc forging blank, and obtain the disc forging blank after forging; S3: The disc forging blank is subjected to double isothermal annealing heat treatment to obtain TC8-1 titanium alloy disc forging; In step S3, the double isothermal annealing heat treatment includes heating the disc forging blank to the first annealing holding temperature. T 1. Hold the furnace to the second annealing holding temperature. T 2. Keep warm and cool with a fan during the converter process; converter time ≤ 10 min. In step S2, the thickness of the disc forging blank is >35mm, and isothermal die forging is selected; The thickness of the disc forging blank is ≤35mm, and axial closed rolling forging is selected; During the axial closed rolling forging process, the upper die feed rate is 3-5 mm / r per revolution, the upper die feed speed is 2-4 mm / s, and the upper die tilt angle is 6-10°.

2. The preparation method according to claim 1, characterized in that, In step S1, the height-to-diameter ratio of the TC8-1 titanium alloy bar is ≤3, and the billet is prepared by machining. The aspect ratio of the TC8-1 titanium alloy bar is >3, and the TC8-1 titanium alloy bar is heated to... Tβ 80℃~Forging temperature T 模锻 Interval billet preparation; The Tβ 80℃ refers to the β-phase transformation point T of TC8-1 titanium alloy bars. β below 80℃.

3. The preparation method according to claim 1, characterized in that, During the isothermal forging process, the forging temperature is... T 模锻 The mold temperature is 950–960℃, and the deformation speed is 0.3–0.8 mm / s.

4. The preparation method according to claim 3, characterized in that, When forging using the isothermal die forging method, the following must also be met: Forging temperature T 模锻 ≥TC8-1 titanium alloy bar raw material final forging temperature, die forging temperature T 模锻 ≤ First annealing holding temperature T 1.

5. The preparation method according to claim 1, characterized in that, During the axial closed-circuit rolling forging, the forging heating temperature is 950–960℃.

6. The preparation method according to claim 1, characterized in that, In step S3, the first annealing holding temperature T 1 satisfies: T 模锻 < T 1 < T β 30℃; in, T 1 represents the first annealing and holding temperature; T 模锻 Forging temperature; Tβ 30℃ refers to the β-phase transformation point T of TC8-1 titanium alloy bars. β below 30℃.

7. The preparation method according to claim 6, characterized in that, In step S3, the first annealing holding time is 1 to 4 hours.

8. The preparation method according to claim 7, characterized in that, In step S3, the second annealing holding temperature T2 is 570-600℃, and the holding time is 1-2 hours.

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