A rolling method of TA21 titanium alloy sheet
By employing a multi-stage two-phase region reversing cross-rolling and quenching process, the problems of edge cracking and uneven properties in the preparation of TA21 titanium alloy thin plates were solved, and the production of TA21 titanium alloy thin plates with fine and uniform microstructure and excellent mechanical properties was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WESTERN TITANIUM TECH
- Filing Date
- 2024-11-11
- Publication Date
- 2026-07-31
AI Technical Summary
Existing technologies often result in edge cracks, poor quality at the beginning and end of the sheet, and unsatisfactory mechanical properties when preparing TA21 titanium alloy thin plates, leading to a complicated production process and uneven performance.
The method of multi-fire two-phase region reversing cross rolling combined with quenching treatment is adopted. The coarse β phase is formed by quenching and holding above the β phase transformation point, and the long strip α phase is precipitated by rapid water cooling to form a needle-like Widmanstätten structure. Then, the structure is refined by one-fire reversing large deformation rolling and cold rolling in the two-phase region.
It effectively solved the edge cracking problem, improved the microstructure uniformity and mechanical properties of the thin plate, reduced the amount of surface treatment, improved production efficiency, and met the quality requirements of TA21 titanium alloy thin plate.
Smart Images
Figure CN119187222B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of titanium and titanium alloy thin plate preparation technology, specifically relating to a rolling method for TA21 titanium alloy thin plate. Background Technology
[0002] TA21 titanium alloy is a low-alloyed Ti-Al-Mn near-α type titanium alloy with a nominal composition (mass fraction, %) of Ti-1Al-1Mn. This alloy has a long-term operating temperature of 300℃ and is used to manufacture cold-formed and welded parts with complex shapes and low strength requirements, such as tubular parts. TA21 titanium alloy is characterized by low strength, high process plasticity, good weldability, and thermal stability. Domestic research on the rolling of TA21 titanium alloy thin plates is limited; relevant literature recommends a two-phase region hot working + two-phase region heat treatment process. According to traditional processes, near-α type titanium alloys are generally prepared by a two-phase region multi-stage reversing hot rolling + cold rolling method when producing thin plates. Near-α type titanium alloys prepared in this way are prone to edge cracking and poor quality at the beginning and end of the thin plate during reversing rolling, significantly increasing the workload of surface treatment, cutting, and other processes, making the process complex. Furthermore, due to the increased surface treatment workload, if the process control is not appropriate, the produced titanium alloy thin plates will have significant differences in quality between plates, resulting in variations in mechanical properties. Therefore, technological improvements are urgently needed. Summary of the Invention
[0003] The technical problem to be solved by this invention is to provide a rolling method for TA21 titanium alloy thin plates, addressing the shortcomings of the prior art. This method involves two rolling passes in the two-phase region of the TA21 titanium alloy slab, combined with quenching and heat treatment to form coarse β grains. Rapid water cooling causes elongated α phases to precipitate from the coarse β phases, forming acicular Widmanstätten structures. Then, a single-pass reversing large deformation rolling and cold rolling are performed in the two-phase region to significantly break down and refine the microstructure, causing the acicular Widmanstätten structures to spheroidize, resulting in a fine and uniform TA21 titanium alloy thin plate. This solves the problems of high workload, poor quality, and unsatisfactory mechanical properties associated with traditional processes for producing titanium alloy thin plates.
[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a rolling method for TA21 titanium alloy thin plates, characterized in that the method includes the following steps:
[0005] Step 1: Apply an anti-oxidation coating to the surface of the TA21 titanium alloy slab; the thickness of the TA21 titanium alloy slab is 140mm to 180mm, the width is 800mm to 1100mm, and the length is 800mm to 1400mm.
[0006] Step 2: The TA21 titanium alloy slab processed in Step 1 is subjected to a first rolling process at a temperature of 880℃~900℃ to obtain a first rolled slab. The first rolling process is unidirectional rolling, with a pass deformation rate of 8%~25%, 6~8 passes, and a rolling speed of 3m / s~4m / s. The thickness of the first rolled slab is 20mm~30mm, and the width is 800mm~1100mm.
[0007] Step 3: Cut the first rolled slab obtained in Step 2 to obtain multiple first intermediate slabs; the thickness of the first intermediate slab is 20mm to 30mm, the width is 800mm to 1100mm, and the length is 1000mm to 1600mm.
[0008] Step 4: The first intermediate slab obtained in Step 3 is subjected to a second rolling process at a temperature of 850℃~880℃, and then returned to the furnace for reheating to obtain a second rolled slab. The deformation rate of the second rolling pass is 10%~25%, the number of passes is 4~6, the rolling speed is 3m / s~4m / s, and the rolling direction of the second rolling is parallel to the rolling direction of the first rolling in Step 2. The thickness of the second rolled slab is 10mm~15mm, and the width is 800mm~1100mm.
[0009] Step 5: Cut the second rolled slab obtained in Step 4 to obtain multiple second intermediate slabs; the thickness of the second intermediate slab is 10mm to 15mm, the width is 800mm to 1100mm, and the length is 1000mm to 1300mm.
[0010] Step 6: Quench the second intermediate slab obtained in Step 5;
[0011] Step 7: The second intermediate slab, after being quenched in Step 6, is subjected to a third rolling process at a temperature of 800℃~830℃ to obtain a third rolled slab. The deformation rate of the third rolling pass is 10%~25%, the rolling speed is 3m / s~4m / s, and the rolling direction of the third rolling is perpendicular to the rolling direction of the second rolling in Step 4. The thickness of the third rolled slab is 3.6mm~4mm, and the width is 1000mm~1300mm.
[0012] Step 8: Cut the third rolled slab obtained in Step 7 to obtain multiple third intermediate slabs; the thickness of the third intermediate slab is 3.6mm to 4mm, the width is 1000mm to 1300mm, and the length is 1000mm to 1500mm.
[0013] Step 9: The third intermediate slab obtained in Step 8 is subjected to semi-finished product annealing at a temperature of 700℃~750℃.
[0014] Step 10: The third intermediate slab after the semi-finished product annealing treatment in Step 9 is cold-rolled to obtain a TA21 titanium alloy cold-rolled sheet; the deformation rate of the cold rolling pass is 5% to 20%, and the rolling direction of the cold rolling is the same as that of the third heat rolling in Step 7; the thickness of the TA21 titanium alloy cold-rolled sheet is 1.2mm to 2.0mm, the width is 1000mm to 1300mm, and the length is 2800mm to 3200mm;
[0015] Step 11: The TA21 titanium alloy cold-rolled sheet obtained in Step 10 is subjected to finished product annealing treatment, and then air-cooled to room temperature to obtain a titanium alloy sheet; the thickness of the TA21 titanium alloy sheet is 1.2mm to 2.0mm, the width is 1000mm to 1300mm, and the length is 2800mm to 3200mm.
[0016] This invention involves sequentially subjecting a TA21 titanium alloy slab to a first rolling process, cutting process, a second rolling process, cutting process, quenching process, a third rolling process, cutting process, semi-finished product annealing process, cold rolling process, and finished product annealing process to obtain a TA21 titanium alloy thin plate. In this process, the TA21 titanium alloy slab is first rolled in the two-phase region in the first two heats, with precise control over the deformation rate and rolling speed of the first two heats. Combined with quenching and holding above the β phase transformation point, a coarse β phase is formed at this temperature. Then, rapid water cooling is achieved through quenching, causing elongated α phases to precipitate from the coarse β phase, forming a acicular Widmanstätten structure. In addition, the quenching process eliminates or weakens the texture of the sheet, reduces the anisotropy of the sheet, and improves the edge cracking problem after rolling. Afterward, a single heat reversing large deformation rolling and cold rolling are performed in the two-phase region to break down and refine the structure, causing the acicular Widmanstätten structure to spheroidize. Finally, the finished product is annealed to obtain a TA21 titanium alloy thin sheet with a fine and uniform structure.
[0017] Furthermore, the rolling method of the present invention reduces the risk of surface defects such as edge cracks in medium and thick plates and poor quality at the beginning and end of thin plates when titanium alloys are rolled directly without quenching treatment, and reduces the workload of surface treatment and cutting processes; at the same time, a single TA21 titanium alloy slab can be used to produce TA21 titanium alloy thin plates of various specifications, which greatly improves production efficiency.
[0018] In summary, this invention utilizes the characteristics of TA21 titanium alloy as a near-α alloy, which has low strength and high plasticity, and employs a multi-stage two-phase region reversing cross rolling + quenching + cold rolling method to prepare TA21 titanium alloy thin plates with uniform and fine equiaxed α grains in the metallographic structure and mechanical properties that meet the requirements.
[0019] The above-mentioned rolling method for TA21 titanium alloy sheet is characterized in that, in step one, the TA21 titanium alloy slab is cross-coated with TB920 anti-oxidation coating, and the direction of the last coating of TB920 anti-oxidation coating is the same as the direction of the first rolling in step two.
[0020] The above-mentioned rolling method for TA21 titanium alloy thin plates is characterized in that the specific process of the first rolling in step two is as follows: holding at 880℃~900℃ for 3h~6h, the initial rolling temperature of the first rolling is not lower than 860℃, the final rolling temperature is not lower than 650℃, and the total deformation rate of the first rolling is 60%~90%. By controlling the final rolling temperature and the total deformation rate of the first rolling, the surface cracks of the first rolled slab are effectively reduced, and its surface quality is improved.
[0021] The above-mentioned rolling method for TA21 titanium alloy thin plates is characterized in that the specific process of the second rolling in step four is as follows: holding at 850℃~880℃ for 1h~2h, the initial rolling temperature of the second rolling is not lower than 800℃, the final rolling temperature is not lower than 550℃, and the total deformation rate of the second rolling is 50%~70%. By controlling the temperature and total deformation rate of the second rolling, the surface quality and performance of the second rolled slab are improved.
[0022] The above-mentioned rolling method for TA21 titanium alloy thin plates is characterized in that the quenching process in step six is as follows: holding at 940℃~980℃ for 0.5h~1h, the time from the second intermediate slab exiting the furnace to immersion in water does not exceed 10s, and the water temperature does not exceed 30℃. By controlling the holding temperature, immersion time, and water temperature of the quenching process, coarse β phase is first formed, and elongated α phase is precipitated from the coarse β phase through rapid water cooling, forming a acicular Widmanstätten structure; in addition, the quenching process eliminates or weakens the texture of the plate, reduces the anisotropy of the plate, and improves the edge cracking problem of the plate after rolling.
[0023] The above-mentioned rolling method for TA21 titanium alloy thin plate is characterized in that the specific process of the third rolling in step seven is as follows: holding at 800℃~830℃ for 1h~2h, the third rolling is a reversing rolling, the initial rolling temperature of the third rolling is not lower than 750℃, the final rolling temperature is not lower than 450℃, and the total deformation rate of the third rolling is 50%~70%.
[0024] The above-mentioned rolling method for TA21 titanium alloy thin plates is characterized in that the specific process of the semi-finished product annealing treatment in step nine is as follows: holding at 700℃~750℃ for 0.5h~1h. By controlling the temperature and time of the semi-finished product annealing treatment, the work hardening effect is effectively reduced, deformed grains are transformed into equiaxed grains through recrystallization, the plasticity of the third intermediate slab is improved, the deformation resistance of the third intermediate slab during cold rolling is reduced, and cold rolling is facilitated.
[0025] The rolling method for TA21 titanium alloy thin plate described above is characterized in that the specific process of the finished product annealing treatment in step eleven is: holding at 600℃~650℃ for 0.5h~1h.
[0026] Compared with the prior art, the present invention has the following advantages:
[0027] 1. This invention involves rolling the TA21 titanium alloy slab in the two-phase region twice, then quenching and holding it above the β phase transformation point to form a coarse β phase. Through rapid water cooling quenching, elongated α phases precipitate from the coarse β phase, forming a needle-like Widmanstätten structure. Then, a single-pass reversal large deformation rolling and cold rolling are performed in the two-phase region to break up and refine the structure, causing the needle-like Widmanstätten structure to spheroidize, resulting in a TA21 titanium alloy thin plate with a fine and uniform structure.
[0028] 2. This invention employs multi-stage two-phase region reversing cross rolling combined with quenching treatment, and precisely controls the deformation rate and rolling speed of each rolling stage. Furthermore, after the intermediate rolling stage (i.e., the second rolling stage), intermediate slabs of different widths are obtained through cutting for subsequent rolling. This effectively eliminates and weakens the plate texture, reduces the anisotropy of the plate, and reduces the significant cracking phenomenon of titanium alloy plates caused by traditional processes. At the same time, it reduces the amount of subsequent grinding, saves costs, and lowers the difficulty of the production process.
[0029] 3. The rolling method of the present invention, while ensuring the production of TA21 titanium alloy thin plates, can produce TA21 titanium alloy thin plates of various specifications using a single TA21 titanium alloy slab, thereby making full use of the slab and greatly improving production efficiency.
[0030] 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
[0031] Figure 1 Metallographic image (500×) of the TA21 titanium alloy sheet prepared in Example 1 of this invention.
[0032] Figure 2 Metallographic image (500×) of the TA21 titanium alloy sheet prepared in Example 2 of this invention.
[0033] Figure 3 Metallographic image (500×) of the TA21 titanium alloy sheet prepared in Example 3 of this invention. Detailed Implementation
[0034] Example 1
[0035] This embodiment includes the following steps:
[0036] Step 1: Cross-coating the TA21 titanium alloy slab with TB920 anti-oxidation coating, and the direction of the last TB920 anti-oxidation coating is the same as the direction of the first rolling in Step 2; the TA21 titanium alloy slab has a thickness of 140mm, a width of 800mm, and a length of 800mm.
[0037] Step 2: After holding the TA21 titanium alloy slab processed in Step 1 at 800℃ for 3 hours, perform the first rolling to obtain the first rolled slab. The first rolling is unidirectional rolling, and the deformation rates of each pass in the first rolling are 12.1%, 17.9%, 24.8%, 25.0%, 24.6%, 23.3%, 22.7%, and 22.6%, respectively. There are 8 passes and the rolling speed is 3 m / s. The thickness of the first rolled slab is 20 mm, the width is 800 mm, the initial rolling temperature of the first rolling is 867℃, the final rolling temperature is 700℃, and the total deformation rate of the first rolling is 85%.
[0038] Step 3: Cut the first rolled slab obtained in Step 2 to obtain multiple first intermediate slabs; the thickness of the first intermediate slab is 20mm, the width is 800mm, and the length is 1050mm.
[0039] Step 4: The first intermediate slab obtained in Step 3 is held at 850℃ for 2 hours and then subjected to a second rolling process, followed by online reheating in the furnace to obtain the second rolled slab. The deformation rates of the passes in the second rolling process are 15%, 17.6%, 17.9%, and 13% respectively, with 4 passes and a rolling speed of 3 m / s. The rolling direction of the second rolling process is parallel to that of the first rolling process in Step 2. The initial rolling temperature of the second rolling process is 830℃, the final rolling temperature is 600℃, and the total deformation rate of the second rolling process is 50%. The thickness of the second rolled slab is 10 mm, and the width is 800 mm.
[0040] Step 5: Cut the second rolled slab obtained in Step 4 to obtain multiple second intermediate slabs; the thickness of the second intermediate slab is 10mm, the width is 800mm, and the length is 1000mm.
[0041] Step 6: Quench the second intermediate slab obtained in Step 5; the specific process of the quenching treatment is as follows: keep it at 940℃ for 0.5h, the time from the second intermediate slab being taken out of the furnace to being put into the water does not exceed 10s, and the water temperature does not exceed 30℃.
[0042] Step 7: The second intermediate slab, after being quenched in Step 6, is held at 800℃ for 1 hour and then subjected to a third rolling process to obtain the third rolled slab. The deformation rates of the passes in the third rolling process are 16.7%, 20%, 23.8%, and 23% respectively, the rolling speed is 3 m / s, and the rolling direction of the third rolling process is perpendicular to the rolling direction of the second rolling process in Step 4. The initial rolling temperature of the third rolling process is 760℃, the final rolling temperature is 500℃, and the total deformation rate of the third rolling process is 64%. The thickness of the third rolled slab is 3.6 mm, and the width is 1000 mm.
[0043] Step 8: Cut the third rolled slab obtained in Step 7 to obtain multiple third intermediate slabs; the thickness of the third intermediate slab is 3.6 mm, the width is 1000 mm, and the length is 1050 mm.
[0044] Step 9: The third intermediate slab obtained in Step 8 is subjected to semi-finished product annealing treatment by holding it at 700℃ for 0.5h.
[0045] Step 10: The third intermediate slab after the semi-finished product annealing treatment in Step 9 is cold-rolled to obtain a TA21 titanium alloy cold-rolled sheet; the deformation rates of the cold rolling passes are 11.1%, 12.5%, 14.3%, 16.7%, 15.0%, 14.7%, 10.3%, and 7.7% respectively, and the rolling direction of the cold rolling is the same as that of the third heat rolling in Step 7; the thickness of the TA21 titanium alloy cold-rolled sheet is 1.2 mm, the width is 1000 mm, and the length is 3000 mm;
[0046] Step 11: After straightening the TA21 titanium alloy cold-rolled sheet obtained in Step 10, perform finished product annealing treatment by holding it at 600℃ for 1 hour, and then air-cool it to room temperature to obtain a titanium alloy sheet; the TA21 titanium alloy sheet has a thickness of 1.2mm, a width of 1000mm, and a length of 3000mm.
[0047] Figure 1 Metallographic image (500×) of the TA21 titanium alloy sheet prepared in this embodiment. Figure 1 It can be seen that the metallographic structure of the TA21 titanium alloy sheet is a uniform and fine structure, with no needle-like structures present.
[0048] Testing revealed that the TA21 titanium alloy sheet prepared in this embodiment exhibits a room temperature tensile strength of 550 MPa–560 MPa, a yield strength of 510 MPa–520 MPa, and an elongation after fracture of 30%–40%. It meets the bending requirements of 2T at 100°. The low-magnification microstructure shows no metallic or non-metallic inclusions or other visually visible defects, while the high-magnification microstructure shows no needle-like structures. This meets the requirements of the company's "Technical Specifications for TA21 Titanium Alloy Sheets for Aerospace Use".
[0049] In summary, the microstructure of the TA21 titanium alloy prepared in this embodiment meets the microstructure requirements of TA21 single-phase titanium alloy, and it has excellent mechanical properties.
[0050] Example 2
[0051] This embodiment includes the following steps:
[0052] Step 1: Apply a cross-coating anti-oxidation coating to the TA21 titanium alloy slab; the TA21 titanium alloy slab has a thickness of 160mm, a width of 1000mm, and a length of 1100mm.
[0053] Step 2: After the TA21 titanium alloy slab processed in Step 1 is held at 880℃ for 4 hours, it is subjected to the first rolling process to obtain the first rolled slab. The first rolling process is unidirectional rolling, and the deformation rates of each pass in the first rolling process are 15.0%, 20.0%, 24.8%, 24.4%, 25.0%, 23.4%, and 23.1%, respectively. The number of passes is 7, and the rolling speed is 3 m / s. The thickness of the first rolled slab is 25 mm, the width is 1000 mm, the initial rolling temperature of the first rolling process is 865℃, the final rolling temperature is 660℃, and the total deformation rate of the first rolling process is 84%.
[0054] Step 3: Cut the first rolled slab obtained in Step 2 to obtain multiple first intermediate slabs; the thickness of the first intermediate slab is 25mm, the width is 1000mm, and the length is 1300mm.
[0055] Step 4: The first intermediate slab obtained in Step 3 is held at 860℃ for 1 hour and then subjected to a second rolling process, followed by online reheating in the furnace to obtain the second rolled slab. The deformation rates of the passes in the second rolling process are 12.0%, 13.6%, 13.2%, 15.2%, and 14.3% respectively, with 5 passes and a rolling speed of 4 m / s. The rolling direction of the second rolling process is parallel to that of the first rolling process in Step 2. The initial rolling temperature of the second rolling process is 840℃, the final rolling temperature is 620℃, and the total deformation rate of the second rolling process is 52%. The thickness of the second rolled slab is 12 mm, and the width is 1000 mm.
[0056] Step 5: Cut the second rolled slab obtained in Step 4 to obtain multiple second intermediate slabs; the thickness of the second intermediate slab is 12mm, the width is 1000mm, and the length is 1200mm.
[0057] Step 6: Quench the second intermediate slab obtained in Step 5; the specific process of the quenching treatment is as follows: keep it at 960℃ for 1 hour, the time from the second intermediate slab being taken out of the furnace to being put into the water does not exceed 10 seconds, and the water temperature does not exceed 30℃.
[0058] Step 7: After the second intermediate slab, which has undergone quenching treatment in Step 6, is held at 810℃ for 1.5 hours and then subjected to a third rolling process to obtain the third rolled slab. The deformation rates of the passes in the third rolling process are 16.7%, 20%, 23.8%, 23%, and 19.1% respectively, the rolling speed is 3 m / s, and the rolling direction of the third rolling process is perpendicular to the rolling direction of the second rolling process in Step 4. The initial rolling temperature of the third rolling process is 760℃, the final rolling temperature is 510℃, and the total deformation rate of the third rolling process is 68%. The thickness of the third rolled slab is 3.8 mm, and the width is 1200 mm.
[0059] Step 8: Cut the third rolled slab obtained in Step 7 to obtain multiple third intermediate slabs; the thickness of the third intermediate slab is 3.8 mm, the width is 1200 mm, and the length is 1400 mm.
[0060] Step 9: The third intermediate slab obtained in Step 8 is subjected to semi-finished product annealing treatment by holding it at 720℃ for 1 hour.
[0061] Step 10: The third intermediate slab after the semi-finished product annealing treatment in Step 9 is cold-rolled to obtain a TA21 titanium alloy cold-rolled sheet; the deformation rates of the cold rolling passes are 13.2%, 15.2%, 14.3%, 12.5%, 11.9%, 10.8%, and 9.1% respectively, and the rolling direction of the cold rolling is the same as that of the third heat rolling in Step 7; the thickness of the TA21 titanium alloy cold-rolled sheet is 1.2 mm, the width is 1200 mm, and the length is 3200 mm;
[0062] Step 11: After straightening the TA21 titanium alloy cold-rolled sheet obtained in Step 10, perform finished product annealing treatment by holding it at 620℃ for 1 hour, and then air-cool it to room temperature to obtain a titanium alloy sheet; the TA21 titanium alloy sheet has a thickness of 1.5mm, a width of 1200mm, and a length of 3200mm.
[0063] Figure 2 Metallographic image (500×) of the TA21 titanium alloy sheet prepared in this embodiment. Figure 2It can be seen that the metallographic structure of the TA21 titanium alloy sheet is a uniform and fine structure, with no needle-like structures present.
[0064] Testing revealed that the TA21 titanium alloy sheet prepared in this embodiment exhibits a room temperature tensile strength of 540 MPa–550 MPa, a yield strength of 500 MPa–510 MPa, and an elongation after fracture of 32%–40%. It meets the bending requirements of 2T and 90°. The low-magnification microstructure shows no metallic or non-metallic inclusions or other visually visible defects, while the high-magnification microstructure shows no needle-like structures. This meets the requirements of the company's "Technical Specifications for TA21 Titanium Alloy Sheets for Aerospace Use".
[0065] In summary, the microstructure of the TA21 titanium alloy prepared in this embodiment meets the microstructure requirements of TA21 single-phase titanium alloy, and it has excellent mechanical properties.
[0066] Example 3
[0067] This embodiment includes the following steps:
[0068] Step 1: Apply a cross-coating anti-oxidation coating to the TA21 titanium alloy slab; the TA21 titanium alloy slab has a thickness of 180mm, a width of 1100mm, and a length of 1400mm.
[0069] Step 2: After the TA21 titanium alloy slab processed in Step 1 is held at 900℃ for 5 hours, it is then subjected to the first rolling process to obtain the first rolled slab. The first rolling process is unidirectional rolling, and the deformation rates of each pass in the first rolling process are 13.6%, 17.1%, 22.4%, 22.1%, 19.7%, 19.3%, 19.6%, and 18.9% respectively. There are 8 passes and the rolling speed is 4 m / s. The thickness of the first rolled slab is 30 mm, the width is 1100 mm, the initial rolling temperature of the first rolling process is 875℃, the final rolling temperature is 670℃, and the total deformation rate of the first rolling process is 83%.
[0070] Step 3: Cut the first rolled slab obtained in Step 2 to obtain multiple first intermediate slabs; the thickness of the first intermediate slab is 30mm, the width is 1100mm, and the length is 1600mm.
[0071] Step 4: The first intermediate slab obtained in Step 3 is held at 880℃ for 1 hour and then subjected to a second rolling process, followed by online reheating in the furnace to obtain the second rolled slab. The deformation rates of the passes in the second rolling process are 10%, 11.1%, 12.5%, 11.4%, 10.2%, and 10.2% respectively, with 6 passes and a rolling speed of 4 m / s. The rolling direction of the second rolling process is parallel to that of the first rolling process in Step 2. The initial rolling temperature of the second rolling process is 860℃, the final rolling temperature is 630℃, and the total deformation rate of the second rolling process is 50%. The thickness of the second rolled slab is 15 mm, and the width is 1100 mm.
[0072] Step 5: Cut the second rolled slab obtained in Step 4 to obtain multiple second intermediate slabs; the thickness of the second intermediate slab is 15mm, the width is 1100mm, and the length is 1300mm.
[0073] Step 6: Quench the second intermediate slab obtained in Step 5; the specific process of the quenching treatment is as follows: keep it at 980℃ for 0.5h, the time from the second intermediate slab being taken out of the furnace to being put into the water does not exceed 10s, and the water temperature does not exceed 30℃.
[0074] Step 7: After the second intermediate slab, which has undergone quenching treatment in Step 6, is held at 830℃ for 2 hours and then subjected to a third rolling process to obtain the third rolled slab. The deformation rates of the passes in the third rolling process are 13.3%, 15.4%, 18.2%, 18.9%, 20.5%, 19.0%, and 14.9% respectively, with a rolling speed of 4 m / s. The rolling direction of the third rolling process is perpendicular to the rolling direction of the second rolling process in Step 4. The initial rolling temperature of the third rolling process is 780℃, the final rolling temperature is 520℃, and the total deformation rate of the third rolling process is 73%. The thickness of the third rolled slab is 4 mm, and the width is 1300 mm.
[0075] Step 8: Cut the third rolled slab obtained in Step 7 to obtain multiple third intermediate slabs; the thickness of the third intermediate slab is 4.0 mm, the width is 1300 mm, and the length is 1500 mm.
[0076] Step 9: The third intermediate slab obtained in Step 8 is subjected to semi-finished product annealing treatment by holding it at a temperature of 750℃ for 1 hour.
[0077] Step 10: The third intermediate slab after the semi-finished product annealing treatment in Step 9 is cold-rolled to obtain a TA21 titanium alloy cold-rolled sheet; the deformation rates of the cold rolling passes are 10.0%, 11.1%, 12.5%, 12.5%, 10.2%, and 9.1% respectively, and the rolling direction of the cold rolling is the same as that of the third heat rolling in Step 7; the thickness of the TA21 titanium alloy cold-rolled sheet is 2.0 mm, the width is 1300 mm, and the length is 2800 mm;
[0078] Step 11: The TA21 titanium alloy cold-rolled sheet obtained in Step 10 is subjected to finished product annealing treatment at 650℃ for 0.5h, and then air-cooled to room temperature to obtain a titanium alloy sheet; the TA21 titanium alloy sheet has a thickness of 2.0mm, a width of 1300mm, and a length of 2800mm.
[0079] Figure 3 Metallographic image (500×) of the TA21 titanium alloy sheet prepared in this embodiment. Figure 3 It can be seen that the metallographic structure of the TA21 titanium alloy sheet is a uniform and fine structure, with no needle-like structures present.
[0080] Testing revealed that the TA21 titanium alloy sheet prepared in this embodiment exhibits a room temperature tensile strength of 535 MPa–545 MPa, a yield strength of 502 MPa–513 MPa, and an elongation after fracture of 34%–42%. It meets the bending requirements of 2T at 80°. The low-magnification microstructure shows no metallic or non-metallic inclusions or other visually visible defects, while the high-magnification microstructure shows no needle-like structures. This meets the requirements of the company's "Technical Specifications for TA21 Titanium Alloy Sheets for Aerospace Use".
[0081] In summary, the microstructure of the TA21 titanium alloy prepared in this embodiment meets the microstructure requirements of TA21 single-phase titanium alloy, and it has excellent mechanical properties.
[0082] 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 rolling method of a TA21 titanium alloy sheet, characterized by, The method includes the following steps: Step 1: Apply an anti-oxidation coating to the surface of the TA21 titanium alloy slab; the thickness of the TA21 titanium alloy slab is 140mm~180mm, the width is 800mm~1100mm, and the length is 800mm~1400mm. Step 2: The TA21 titanium alloy slab processed in Step 1 is subjected to a first rolling process at a temperature of 880℃~900℃ to obtain a first rolled slab. The first rolling process is unidirectional rolling, with a pass deformation rate of 8%~25%, 6~8 passes, and a rolling speed of 3m / s~4m / s. The total deformation rate of the first rolling process is 60%~90%. The thickness of the first rolled slab is 20mm~30mm, and the width is 800mm~1100mm. Step 3: Cut the first rolled slab obtained in Step 2 to obtain multiple first intermediate slabs; the thickness of the first intermediate slab is 20mm~30mm, the width is 800mm~1100mm, and the length is 1000mm~1600mm. Step 4: The first intermediate slab obtained in Step 3 is subjected to a second rolling process at a temperature of 850℃~880℃, and then returned to the furnace for reheating to obtain a second rolled slab. The deformation rate of the second rolling process is 10%~25%, the number of passes is 4~6, the rolling speed is 3m / s~4m / s, and the rolling direction of the second rolling process is parallel to the rolling direction of the first rolling process in Step 2. The total deformation rate of the second rolling process is 50%~70%. The thickness of the second rolled slab is 10mm~15mm, and the width is 800mm~1100mm. Step 5: Cut the second rolled slab obtained in Step 4 to obtain multiple second intermediate slabs; the thickness of the second intermediate slab is 10mm~15mm, the width is 800mm~1100mm, and the length is 1000mm~1300mm. Step 6: Quench the second intermediate slab obtained in Step 5; the specific process of the quenching treatment is as follows: keep it at 940℃~980℃ for 0.5h~1h, the time from the second intermediate slab being taken out of the furnace to being put into the water does not exceed 10s, and the water temperature does not exceed 30℃. Step 7: The second intermediate slab, after quenching in Step 6, is subjected to a third rolling process at a temperature of 800℃~830℃ to obtain a third rolled slab. The deformation rate of the third rolling pass is 10%~25%, the rolling speed is 3m / s~4m / s, and the rolling direction of the third rolling is perpendicular to the rolling direction of the second rolling in Step 4. The initial rolling temperature of the third rolling is not lower than 750℃, the final rolling temperature is not lower than 450℃, and the total deformation rate of the third rolling is 50%~70%. The thickness of the third rolled slab is 3.6mm~4mm, and the width is 1000mm~1300mm. Step 8: Cut the third rolled slab obtained in Step 7 to obtain multiple third intermediate slabs; the thickness of the third intermediate slab is 3.6mm~4mm, the width is 1000mm~1300mm, and the length is 1000mm~1500mm. Step 9: The third intermediate slab obtained in Step 8 is subjected to semi-finished product annealing at a temperature of 700℃~750℃. Step 10: The third intermediate slab after the semi-finished product annealing treatment in Step 9 is cold-rolled to obtain a TA21 titanium alloy cold-rolled sheet; the deformation rate of the cold rolling pass is 5%~20%, and the rolling direction of the cold rolling is the same as that of the third heat rolling in Step 7; the thickness of the TA21 titanium alloy cold-rolled sheet is 1.2mm~2.0mm, the width is 1000mm~1300mm, and the length is 2800mm~3200mm; Step 11: The TA21 titanium alloy cold-rolled sheet obtained in Step 10 is subjected to finished product annealing treatment, and then air-cooled to room temperature to obtain a titanium alloy sheet; the thickness of the TA21 titanium alloy sheet is 1.2mm~2.0mm, the width is 1000mm~1300mm, and the length is 2800mm~3200mm.
2. The method of claim 1, wherein the TA21 titanium alloy sheet is rolled at a temperature of 950°C or higher. In step one, the TA21 titanium alloy slab is cross-coated with TB920 anti-oxidation coating, and the direction of the last TB920 anti-oxidation coating is the same as the direction of the first rolling in step two.
3. The rolling method for TA21 titanium alloy thin plate according to claim 1, characterized in that, The specific process of the first rolling in step two is as follows: hold at 880℃~900℃ for 3h~6h, the initial rolling temperature of the first rolling is not lower than 860℃, and the final rolling temperature is not lower than 650℃.
4. The rolling method for TA21 titanium alloy thin plate according to claim 1, characterized in that, The specific process of the second rolling in step four is as follows: hold at 850℃~880℃ for 1h~2h, the initial rolling temperature of the second rolling is not lower than 800℃, and the final rolling temperature is not lower than 550℃.
5. The rolling method for TA21 titanium alloy thin plate according to claim 1, characterized in that, The specific process of the third rolling in step seven is as follows: hold at 800℃~830℃ for 1h~2h, and the third rolling is a reversing rolling.
6. The rolling method for TA21 titanium alloy thin plate according to claim 1, characterized in that, The specific process of the semi-finished product annealing treatment in step nine is as follows: heat treatment at 700℃~750℃ for 0.5h~1h.
7. The rolling method for TA21 titanium alloy thin plate according to claim 1, characterized in that, The specific process of the finished product annealing treatment described in step eleven is as follows: heat at 600℃~650℃ for 0.5h~1h.