Forging state ti-al alloy sheet pack rolling method based on superposition structure design
By using a cladding structure design and a forged TiAl alloy cladding rolling method, the problems of casting defects and uneven deformation in the preparation of TiAl alloy thin plates were solved, and efficient and stable production of TiAl alloy thin plates was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNIV OF SCI & TECH BEIJING
- Filing Date
- 2023-05-16
- Publication Date
- 2026-06-12
AI Technical Summary
Existing technologies are difficult to stably produce TiAl alloy thin plates with a thickness of less than 1 mm, and there are problems such as casting defects, uneven deformation and low production efficiency.
A forged TiAl alloy sheet cladding rolling method based on a stacked structure design is adopted. The TiAl alloy forging disc and Ti2AlNb alloy are stacked together after isothermal forging, combined with a heat-resistant glass coating and composite isolation material, and then cladding rolling and stress-relief annealing are performed.
The preparation of TiAl alloy thin plates without casting defects has been achieved, improving deformation uniformity and production efficiency, and enabling the stable preparation of TiAl alloy thin plates with a thickness of less than 1 mm.
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Figure CN116603860B_ABST
Abstract
Description
Technical Field
[0001] This invention pertains to the rolling technology of TiAl alloy thin plates, and specifically relates to a method for preparing TiAl alloy thin plates with a thickness of less than 1 mm. Background Technology
[0002] TiAl-based alloys possess excellent properties such as low density, good high-temperature strength, superior creep resistance, and oxidation resistance, making them promising candidates for high-temperature structural applications in the aerospace and automotive industries. However, defects in TiAl alloys, such as a narrow hot working window, susceptibility to cracking during deformation, and poor room-temperature plasticity, limit their sheet metal forming capabilities. This is especially true when preparing thin sheets, where large reduction deformations and high temperature drop rates further complicate the process.
[0003] Currently, the main method for preparing TiAl alloy plates is cladding hot rolling technology. Its advantages are primarily twofold: first, the cladding structure isolates the TiAl alloy from air, preventing oxidation and providing insulation, reducing temperature drop and heat dissipation from contact with the rolls; second, the cladding structure allows for uniform deformation of the TiAl alloy. However, when the plate thickness is less than 2 mm, the cladding effect has limited improvement. In many studies on TiAl alloy cladding rolling processes, to reduce costs and simplify the process, cast TiAl alloy is directly selected. However, the thickness of the rolled plate is difficult to exceed 1 mm. This is because cast alloys have casting defects such as shrinkage porosity and cracks, and the inhomogeneous structure of the cast alloy makes it sensitive to stress changes, making it difficult to roll thin plates.
[0004] TiAl alloy cladding hot rolling technology generally uses single-plate rolling, but it also has many limitations: in order to ensure the insulation performance of the cladding, the thickness of the cladding material needs to be increased, which increases the cost; single-plate rolling can only roll one TiAl alloy plate at a time, which is inefficient and cannot be carried out on a large scale; at the same time, the deformation coordination between the stainless steel cladding material and the TiAl alloy plate is poor and the difference in thermal expansion coefficient is too large, which makes it easy to crack when the TiAl alloy plate is rolled thin.
[0005] In a published patent (publication number CN 112916644 A), the inventors proposed using cladding and stacking rolling to prepare multiple TiAl alloy plates, thereby reducing the cost of TiAl alloy plate preparation and improving the efficiency and quality of plate preparation. However, when large deformations are performed, the stress conditions of the core TiAl alloy plate and the edge TiAl alloy plate differ significantly, leading to uneven deformation. This patent uses metal foil as the isolation layer material, which can easily lead to metallurgical bonding during the heat preservation process, hindering the separation of the plates after rolling.
[0006] In a published patent (publication number CN 105081323 A), the inventors proposed using spark plasma sintering to prepare TiAl alloy slabs. These slabs exhibit high density, fine microstructure, uniform composition, and excellent performance, which is beneficial for rolling TiAl / Ti alloy layered composite plates at relatively low temperatures and high strain rates. However, spark plasma sintering technology suffers from drawbacks such as high energy consumption, high equipment investment, and poor controllability during the sintering process. Furthermore, due to equipment limitations, it is impossible to prepare large-sized TiAl alloy slabs.
[0007] The literature "Research Status of TiAl Alloy Plate Rolling. Acta Metallurgica Sinica, 2022, 58(08):965-978" points out that large-size high-performance TiAl alloy plates or foils are important lightweight high-temperature structural materials in the aerospace field. The size of high-performance TiAl alloy plates produced domestically still lags significantly behind that of foreign counterparts, and there is still a considerable gap before they can be applied in engineering. Currently, there are no reports of mass production of TiAl alloy thin plates with a thickness of less than 1 mm in China. Plansee, an Austrian company, can reliably supply ultra-thin TiAl alloy plates using a cladding hot rolling process, but the technical details of this process are kept confidential.
[0008] Therefore, developing a simple and stable method for preparing TiAl alloy thin plates is of great significance for the widespread application of TiAl-based alloys in the aerospace field. Summary of the Invention
[0009] The purpose of this invention is to provide a method for rolling forged TiAl alloy thin plates based on a stacked structure design. The method uses isothermal forged TiAl alloy forging discs as rolling plates, which solves the problem of the difficulty in preparing TiAl alloy thin plates with a thickness of less than 1 mm. The process is simple and can be stably prepared.
[0010] The present invention adopts the following technical solution:
[0011] A method for cladding rolling of forged TiAl alloy thin plates based on a stacked structure design, comprising the following steps:
[0012] Step 1, Preparation of forged TiAl alloy slab: TiAl alloy ingots are obtained by vacuum arc melting, TiAl alloy slabs are obtained by isothermal forging, N plate-shaped blanks are obtained by electrical discharge wire cutting, rounded corners with a radius of 3-8mm are made, and the surface of the blanks is polished by a grinding machine.
[0013] Step 2, Ti2AlNb alloy slab preparation: Ti2AlNb alloy ingots are obtained by vacuum arc melting, homogenization treatment and hot isostatic pressing treatment are performed, N+1 slab blanks are obtained by wire EDM, the corners are rounded with a radius of 3-8mm, and the surface of the blanks is polished by a grinding machine.
[0014] Step 3, Preparation of the cladding blank for the stacked structure design: The surfaces of N forged TiAl alloy plates are uniformly coated with a heat-resistant glass coating. Then, 1-Ti2AlNb alloy, 2-forged TiAl alloy, 3-Ti2AlNb alloy, 4-forged TiAl alloy, 5-Ti2AlNb alloy...2N-forged TiAl alloy, 2N+1-Ti2AlNb alloy (N is the number of forged TiAl alloys in the stacked structure, 1≤N≤4) are stacked and placed in the groove of the cladding. A composite isolation material is added between the TiAl alloy and the Ti2AlNb alloy, and then they are welded together to obtain the cladding TiAl alloy blank with the stacked structure design.
[0015] Step 4, Encasing Rolling: The casing billet with the overlapping structure design obtained in Step 3 is placed in a high-temperature furnace and heated to 1050℃~1350℃, held for 0.5~5h, and then casing rolling is performed. Each pass is held in the furnace for 5~30min. After the rolling process is completed, it is placed in a vacuum furnace for stress-relief annealing.
[0016] Step 5, Machining of the rolled slab: The cladding on the rolled TiAl alloy slab obtained in Step 4 is removed by wire cutting. The Ti2AlNb alloy plate and the TiAl alloy sheet are automatically separated. The heat-resistant glass coating on the surface of the TiAl sheet is removed by grinding to obtain a TiAl alloy sheet with a thickness of less than 1 mm.
[0017] Furthermore, the TiAl alloy described in step 1, by atomic percentage, comprises Al: 40%–45%, V: 6%–9%, Y: 0%–1%, with the balance being Ti.
[0018] Further, the TiAl alloy described in step 1, by atomic percentage, has Al: 40%–45%, Nb: 5%–10%, Y: 0%–1%, B: 0%–1%, C: 0%–1%, and the balance is Ti.
[0019] Further, the TiAl alloy described in step 1, by atomic percentage, comprises: Al: 40%–48%, Nb: 2%–8%, Cr: 0%–8%, Mn: 0%–8%, V: 0%–8%, Mo: 0%–8%, Y: 0%–1%, B: 0%–1%, C: 0%–1%, with the balance being Ti.
[0020] Furthermore, in step 1, the isothermal forging is carried out at a forging temperature of 1200℃~1300℃, with a total deformation of 70%~80% and a deformation rate of 0.001~0.1s. -1 .
[0021] Furthermore, the Ti2AlNb alloy described in step 2, by atomic percentage, comprises Al: 23%–26%, Nb: 18%–20%, Mo: 0.5%–2%, with the balance being Ti.
[0022] Furthermore, the thickness of the TiAl plate obtained by wire cutting in step 1 is 2mm to 10mm.
[0023] Furthermore, the thickness of the Ti2AlNb plate blank obtained by wire cutting in step 2 is 2mm to 15mm.
[0024] Furthermore, the composite insulating material described in step 3 has a thickness of 2mm to 4mm and includes high-temperature resistant insulation cotton, micron-sized ceramic powder, and micron-sized graphite powder.
[0025] Further, the rolling process described in step 4 involves a pass deformation of 10%–30% and a rolling speed of 50 mm / s–150 mm / s. When the pass deformation is 20%–30%, the rolling speed is 100 mm / s–150 mm / s; when the pass deformation is 10%–20%, the rolling speed is 50 mm / s–100 mm / s. After rolling, the material is placed in a vacuum furnace and held at 700℃–1000℃ for 1 hour–6 hours, then cooled in the furnace for stress-relief annealing.
[0026] The present invention has the following beneficial effects:
[0027] (1) The present invention uses forged TiAl alloy for thin plate rolling, which ensures that the alloy has no casting defects before rolling, has fine grain size and good high temperature plasticity, and is easy to roll into thin TiAl alloy plates.
[0028] (2) Compared with the traditional TiAl alloy cladding rolling, the present invention adopts a stacked structure design, using Ti2AlNb alloy as a transition layer between TiAl alloy and cladding metal, which greatly reduces the deformation incoordination between TiAl alloy and cladding metal and increases the heat capacity, which is beneficial to improving the forming quality of TiAl alloy thin plate; at the same time, high-quality Ti2AlNb alloy thin plate will also be obtained as a by-product of TiAl alloy thin plate, thus improving production efficiency.
[0029] (3) The present invention provides a method for rolling a forged TiAl alloy thin plate with a cladding structure based on a stacked structure design. The cladding preparation process is easy to operate and the rolling process is controllable, and it can successfully prepare TiAl alloy thin plates with a thickness of less than 1 mm.
[0030] (4) The composite insulating material used in this invention comprises a layer of high-temperature resistant insulation cotton, a layer of micron-sized ceramic powder, and a layer of micron-sized graphite powder. The high-temperature resistant insulation cotton provides insulation, while the micron-sized ceramic powder provides insulation, effectively preventing the metallurgical bonding between the TiAl alloy and the Ti2AlNb alloy; at the same time, the micron-sized graphite powder provides lubrication, which is beneficial for coordinating deformation. Attached Figure Description
[0031] Figure 1 The image shows the microstructure of the TiAl alloy sheet prepared in Example 1.
[0032] Figure 2 The image shows the microstructure of the TiAl alloy sheet prepared in Example 2.
[0033] Figure 3 The image shows the microstructure of the TiAl alloy sheet prepared in Example 3.
[0034] Figure 4 The image shows the microstructure of the TiAl alloy sheet prepared in Example 4. Detailed Implementation
[0035] To describe in detail the technical features and process scheme of the present invention, further explanation is provided below in conjunction with specific embodiments.
[0036] Example 1
[0037] Preparation of forged TiAl alloy slabs: TiAl alloy ingots were obtained by vacuum arc melting with a composition of Ti-43Al-7.5V-0.12Y. The ingots were then isothermally forged at 1300℃, achieving a deformation rate of 0.1 s⁻¹ with a deformation rate of 80%. -1 TiAl alloy forging discs were obtained, and a 5mm thick TiAl alloy square blank was obtained by wire electrical discharge machining. The corners were rounded with a radius of 5mm, and the surface of the blank was polished by a grinding machine.
[0038] Preparation of Ti2AlNb alloy slabs: Ti2AlNb alloy ingots were obtained by vacuum arc melting with the alloy composition Ti-25Al-19Nb-0.5Mo. Homogenization and hot isostatic pressing were performed. Two 8mm square billets were obtained by wire EDM, with 5mm radius rounded corners, and the surface of the billets was polished by a grinding machine.
[0039] Preparation of the cladding blank with the stacked structure design: The cladding material is stainless steel. The surface of the forged TiAl alloy plate is uniformly coated with a heat-resistant glass coating. Then, the bottom Ti2AlNb alloy plate, the forged TiAl alloy plate and the upper Ti2AlNb alloy plate are placed in the groove of the cladding in sequence. A 3mm thick composite isolation material is added between the alloy plate layers. Finally, they are welded together to obtain the cladding TiAl alloy blank with the stacked structure design.
[0040] Encasing rolling: The obtained clad TiAl alloy billet with the cladding structure design is placed in a high-temperature furnace and heated to 1200℃, held for 3 hours; the deformation amount of the first two passes is 30%, and the rolling speed is 140 mm / s; the deformation amount of the third, fourth, fifth and sixth passes is 25%, and the rolling speed is 115 mm / s; the deformation amount of the seventh, eighth and ninth passes is 15%, and the rolling speed is 55 mm / s. Each pass is held in the furnace for 10 minutes; after rolling, it is immediately placed in a vacuum furnace and held at 900℃ for 2 hours for stress relief annealing, and then cooled in the furnace.
[0041] Machining of the rolled slab: The cladding on the TiAl alloy billet was removed by wire cutting. Since the Ti2AlNb alloy was not bonded to the TiAl alloy, it detached automatically. The heat-resistant glass coating on the surface of the TiAl alloy sheet was then removed by grinding, yielding a 0.85mm thick TiAl alloy sheet with good surface quality. Its internal microstructure consists of fine equiaxed γ and β phases, free of microscopic defects. Figure 1 As shown.
[0042] Example 2
[0043] Preparation of forged TiAl alloy slabs: TiAl alloy ingots were obtained by vacuum arc melting with the alloy composition Ti-45Al-4Nb-1.5Mo-0.2Y. The ingots were then isothermally forged at 1200℃, achieving a deformation rate of 0.01 s⁻¹ with a deformation amount of 70%. -1 TiAl alloy forging discs were obtained, and two 4mm thick TiAl alloy square blanks were obtained by wire electrical discharge machining. The corners were rounded with a radius of 4mm, and the surface of the blanks was polished by a grinding machine.
[0044] Preparation of Ti2AlNb alloy slabs: Ti2AlNb alloy ingots were obtained by vacuum arc melting with Ti-26Al-19Nb-1Mo alloy composition. Homogenization and hot isostatic pressing were performed. Three 6mm square billets were obtained by wire EDM, with 4mm radius rounded corners, and the surface of the billets was polished by a grinding machine.
[0045] Preparation of the cladding blank with the stacked structure design: The cladding material is stainless steel. The surface of the forged TiAl alloy plate is uniformly coated with a heat-resistant glass coating. Then, Ti2AlNb alloy plates, forged TiAl alloy plates, Ti2AlNb alloy plates, forged TiAl alloy plates, and Ti2AlNb alloy plates are placed in the groove of the cladding in sequence. A 2mm thick composite isolation material is added between the alloy plate layers. Finally, they are welded together to obtain the cladding TiAl alloy blank with the stacked structure design.
[0046] Encasing Rolling: The obtained clad TiAl alloy billet with the cladding structure design is placed in a high-temperature furnace and heated to 1250℃, held for 2 hours; the deformation amount of the first three passes is 30%, and the rolling speed is 150 mm / s; the deformation amount of the fourth, fifth, and sixth passes is 25%, and the rolling speed is 115 mm / s; the deformation amount of the seventh and eighth passes is 15%, and the rolling speed is 75 mm / s; the deformation amount of the ninth, tenth, and eleventh passes is 10%, and the rolling speed is 55 mm / s. Each pass is held in the furnace for 15 minutes; after rolling, it is immediately placed in a vacuum furnace and held at 1000℃ for 1 hour for stress relief annealing, and then cooled in the furnace.
[0047] Machining of the rolled slab: The cladding on the TiAl alloy billet was removed by wire cutting. Since the Ti2AlNb alloy was not bonded to the TiAl alloy, it detached automatically. The heat-resistant glass coating on the surface of the TiAl alloy sheet was removed by grinding, yielding two 0.92mm thick TiAl alloy sheets with good surface quality. Their internal microstructure consists of fine (α2 + γ) lamellae, streamlined β phase, and fine equiaxed γ phase, with no microscopic defects. Figure 2 As shown.
[0048] Example 3
[0049] Preparation of forged TiAl alloy slabs: TiAl alloy ingots were obtained by vacuum arc melting with the alloy composition of Ti-44Al-9Nb-0.2B-0.2Y. TiAl alloy forging slabs were obtained by isothermal forging at 1200℃ with a deformation of 70% and a deformation rate of 0.01s-1. Three 3mm thick TiAl alloy square billets were obtained by wire EDM, with rounded corners of 3mm radius, and the surface of the billets was polished by a grinding machine.
[0050] Preparation of Ti2AlNb alloy slabs: Ti2AlNb alloy ingots were obtained by vacuum arc melting with Ti-26Al-19Nb-1Mo alloy composition. Homogenization and hot isostatic pressing were performed. Four 5mm square billets were obtained by wire EDM, with rounded corners of 3mm radius, and the surface of the billets was polished by a grinding machine.
[0051] Preparation of the cladding blank with the stacked structure design: The cladding material is stainless steel. The surface of the forged TiAl alloy plate is uniformly coated with a heat-resistant glass coating. Then, Ti2AlNb alloy plates, forged TiAl alloy plates, Ti2AlNb alloy plates, forged TiAl alloy plates, Ti2AlNb alloy plates, forged TiAl alloy plates, Ti2AlNb alloy plates, and Ti2AlNb alloy plates are placed in the groove of the cladding in sequence. A 2mm thick composite isolation material is added between the alloy plate layers. Finally, they are welded together to obtain the cladding TiAl alloy blank with the stacked structure design.
[0052] Encasing Rolling: The obtained clad TiAl alloy billet with the cladding structure design is placed in a high-temperature furnace and heated to 1300℃, held for 2 hours; the deformation amount of the first three passes is 30%, and the rolling speed is 145 mm / s; the deformation amount of the fourth, fifth, sixth and seventh passes is 25%, and the rolling speed is 115 mm / s; the deformation amount of the eighth and ninth passes is 20%, and the rolling speed is 100 mm / s; the deformation amount of the tenth, eleventh and twelfth passes is 15%, and the rolling speed is 75 mm / s; the deformation amount of the thirteenth and fourteenth passes is 10%, and the rolling speed is 50 mm / s. Each pass is held in the furnace for 20 minutes; after rolling, it is immediately placed in a vacuum furnace and held at 700℃ for 3 hours for stress relief annealing, and then cooled in the furnace.
[0053] Machining of the rolled slab: The cladding on the TiAl alloy billet was removed by wire cutting. Since the Ti2AlNb alloy was not bonded to the TiAl alloy, it detached automatically. The heat-resistant glass coating on the surface of the TiAl alloy sheet was removed by grinding, yielding three 0.81mm thick TiAl alloy sheets with good surface quality. Their internal microstructure is a fine and uniform bimodal structure, composed of dynamically recrystallized γ grains and fine (α2+γ) lamellae, without microscopic defects. Figure 3 As shown.
[0054] Example 4
[0055] The difference from Example 1 is that the thickness of the forged TiAl alloy in this example is 8 mm, the thickness of the Ti2AlNb alloy is 10 mm, the rolling temperature is 1250℃, the tenth and eleventh passes are added, the deformation per pass is 10%, and the rolling speed is 50 mm / s. All other process steps and parameters are the same as in Example 1. This example prepared a 0.96 mm thick TiAl alloy sheet with good surface quality and no cracks. Its internal microstructure consists of fine equiaxed γ and β phases, without microscopic defects. Figure 4 As shown.
[0056] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the basic principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for cladding rolling of forged TiAl alloy thin plates based on a stacked structure design, characterized in that, The method includes the following steps: Step 1, Preparation of Forged TiAl Alloy Slab: TiAl alloy ingots are obtained by vacuum arc melting, and TiAl alloy slabs are obtained by isothermal forging. The isothermal forging temperature is 1200 ℃~1300 ℃, the total deformation is 70%~80%, and the deformation rate is 0.001~0.1s. -1 N plate-shaped blanks are obtained by wire electrical discharge machining, rounded with a radius of 3~8mm, and the surface of the blanks is polished by a grinding machine. Step 2, Ti2AlNb alloy slab preparation: Ti2AlNb alloy ingots are obtained by vacuum arc melting, homogenization and hot isostatic pressing are performed, N+1 slab blanks are obtained by wire EDM, the corners are rounded with a radius of 3~8mm, and the surface of the blanks is polished by a grinding machine. Step 3, Preparation of the cladding blank with the stacked structure design: N forged TiAl alloy plates are uniformly coated with a heat-resistant glass coating. Then, 1-Ti2AlNb alloy, 2-forged TiAl alloy, 3-Ti2AlNb alloy, 4-forged TiAl alloy, 5-Ti2AlNb alloy...2N-forged TiAl alloy, 2N+1-Ti2AlNb alloy are stacked in sequence and placed in the groove of the cladding. A composite isolation material with a thickness of 2 mm to 4 mm is added between the TiAl alloy and the Ti2AlNb alloy. Then, they are welded together to obtain the cladding TiAl alloy blank with the stacked structure design. N represents the number of forged TiAl alloys in the stacked structure, where 1 ≤ N ≤ 4; Step 4, Encasing Rolling: The casing billet with the overlapping structure design obtained in Step 3 is placed in a high-temperature furnace and heated to 1050 ℃~1350 ℃, held for 0.5~5 h, and then casing rolling is performed. The deformation per pass is 10%~30%, and the rolling speed is 50 mm / s~150 mm / s; when the deformation per pass is 20%~30%, the rolling speed is 100 mm / s~150 mm / s; when the deformation per pass is 10%~20%, the rolling speed is 50 mm / s~100 mm / s. Each pass is held in the furnace for 5~30 min. After the rolling process is completed, it is placed in a vacuum furnace for stress-relief annealing. Step 5, Machining of the rolled slab: The cladding on the rolled TiAl alloy slab obtained in Step 4 is removed by wire cutting. The Ti2AlNb alloy plate and the TiAl alloy sheet are automatically separated. The heat-resistant glass coating on the surface of the TiAl sheet is removed by grinding to obtain a TiAl alloy sheet with a thickness of less than 1 mm.
2. The rolling method according to claim 1, characterized in that, The TiAl alloy described in step 1 has the following atomic percentages: Al: 40%~45%, V: 6%~9%, Y: 0%~1%, with the balance being Ti.
3. The rolling method according to claim 1, characterized in that, The TiAl alloy described in step 1, by atomic percentage, has Al: 40%~45%, Nb: 5%~10%, Y: 0%~1%, B: 0%~1%, C: 0%~1%, and the balance is Ti.
4. The rolling method according to claim 1, characterized in that, The TiAl alloy described in step 1, by atomic percentage, has Al: 40%~48%, Nb: 2%~8%, Cr: 0%~8%, Mn: 0%~8%, V: 0%~8%, Mo: 0%~8%, Y: 0%~1%, B: 0%~1%, C: 0%~1%, with the balance being Ti.
5. The rolling method according to claim 1, characterized in that, The Ti2AlNb alloy described in step 2, by atomic percentage, has Al: 23%~26%, Nb: 18%~20%, Mo: 0.5%~2%, and the balance is Ti.
6. The rolling method according to claim 1, characterized in that, The thickness of the TiAl plate obtained by wire cutting in step 1 is 2mm~10mm.
7. The rolling method according to claim 1, characterized in that, The thickness of the Ti2AlNb plate blank obtained by wire cutting in step 2 is 2mm~15mm.
8. The rolling method according to claim 1, characterized in that, The composite insulation material mentioned in step 3 includes high-temperature resistant insulation cotton, micron-sized ceramic powder, and micron-sized graphite powder.
9. The rolling method according to claim 1, characterized in that, The stress-relief annealing described in step 4 is performed by holding at 700 ℃~1000 ℃ for 1 h~6 h, followed by furnace cooling.