A rolling method of isotropic ta22 titanium alloy sheet

Abstract

The application discloses a rolling method of isotropic TA22 titanium alloy sheet, which comprises the following steps: one, first fire rolling by stage heating; two, cutting and quenching; three, second fire rolling; four, cutting; five, third fire rolling; six, cutting and external cladding with a ladle cover; seven, cladding and stacking rolling; eight, finished product heat treatment, to obtain the TA22 titanium alloy sheet. The preparation method adopts the process of one fire rolling + quenching + two fire rolling + cladding and stacking rolling + finished product heat treatment, and combines with the control of rolling direction changing and the temperature and pass deformation rate in each rolling process, so that the plate is fully and uniformly deformed; the heat treatment mode of furnace cooling + air cooling is adopted, so that the plate is fully recrystallized, the plate deformation caused by direct cooling after heat treatment of the plate is avoided, the TA22 titanium alloy sheet with fine and uniform structure, high size uniformity and high isotropy is obtained, and the TA22 titanium alloy sheet is suitable for fields of ships, machinery, chemical industry, petroleum and the like.

Description

Technical Field

[0001] This invention belongs to the field of titanium and titanium alloy sheet preparation technology, and in particular relates to a rolling method for isotropic TA22 titanium alloy thin sheet. Background Technology

[0002] The nominal composition (% by mass) of TA22 titanium alloy is Ti-3Al-1Mo-1Ni-2Zr, belonging to a low-alloyed near-α type titanium alloy. TA22 titanium alloy has moderate strength, high plasticity, good machinability and formability, excellent corrosion resistance and weldability, making it a new type of high-temperature corrosion-resistant titanium alloy.

[0003] Currently, the standard thickness of TA22 steel plates is 4mm to 30mm. The "Specification for Titanium and Titanium Alloy Plates for Ships" (GJB 944A-2018) specifies the following performance requirements for TA22 steel plates (thickness 4mm to 6mm): transverse room temperature tensile strength ≥635MPa, yield strength ≥490MPa, and elongation after fracture ≥17%. However, research on TA22 titanium alloy thin plates (thickness <4mm) is relatively limited, and production has not yet stabilized. Based on production experience with near-α type titanium alloy corrugated plates, TA22 titanium alloy thin plates are generally prepared using a hot rolling (reversed direction) + cold rolling process. Trial production results show that the plates require four hot rolling passes followed by one or two cold rolling passes, resulting in a long production process and low efficiency. Furthermore, the trial-produced plates exhibit significant differences in transverse and longitudinal properties (room temperature tensile strength difference of approximately 35MPa, yield strength difference of approximately 50MPa). Therefore, there is an urgent need for technological improvements to develop a high-efficiency, isotropic process for TA22 titanium alloy thin plates. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a rolling method for isotropic TA22 titanium alloy thin plates. This method avoids abnormal grain growth caused by prolonged high-temperature heating of the slab during the first rolling pass by using a stepped heating process. Then, through a process of one-pass rolling + quenching + two-pass rolling + cladding rolling, combined with controlled rolling direction and temperature and pass deformation rate during each rolling process, the plate is fully and uniformly deformed. Finally, a combined furnace cooling and air cooling heat treatment yields a TA22 titanium alloy thin plate with fine and uniform microstructure, high dimensional uniformity, and high isotropy. This solves the problems of long production processes, low production efficiency, and large differences in mechanical properties in existing TA22 titanium alloy thin plate production.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a rolling method for isotropic TA22 titanium alloy thin plates, characterized by comprising the following steps:

[0006] Step 1: Heat a TA22 titanium alloy slab with a thickness of 180mm~200mm, a width of 700mm~900mm, and a length of 900mm~1200mm to 780℃, and then perform the first rolling pass at 880℃~910℃ to obtain a slab with a thickness of 126mm~138mm, a width of 900mm~1200mm, and a length of 1000mm~1300mm; the first rolling pass is unidirectional rolling, the pass deformation rate is 8%~20%, and the rolling speed is 1.5m / s~3m / s;

[0007] The material is reheated online and then rolled in a second pass at 880℃~910℃ to obtain a first plate with a thickness of 20mm~25mm, a width of 1000mm~1300mm, and a length of 4500mm~5600mm. The rolling direction of the second pass is perpendicular to the rolling direction of the first pass, the deformation rate per pass is 10%~25%, and the rolling speed is 1.5m / s~3m / s.

[0008] Step 2: Cut the first plate obtained in Step 1 and quench it in the β phase region;

[0009] Step 3: The first plate after quenching in Step 2 is subjected to a second rolling at 880℃~910℃ to obtain a second plate with a thickness of 10mm~13mm, a width of 1000mm~1300mm, and a length of 2300mm~2900mm; the rolling direction of the second rolling is parallel to the rolling direction of the second rolling pass in Step 1, the deformation rate per pass is 10%~25%, and the rolling speed is 2m / s~4m / s;

[0010] Step 4: Cut the second sheet material obtained in Step 3;

[0011] Step 5: The second plate cut in Step 4 is subjected to a third rolling process at 860℃~880℃ to obtain a third plate with a thickness of 5mm~9mm, a width of 950mm~1250mm, and a length of 1700mm~1900mm; the rolling direction of the third rolling process is perpendicular to the rolling direction of the second rolling process in Step 3, the deformation rate per pass is 10%~25%, and the rolling speed is 3m / s~4m / s;

[0012] Step 6: Cut the third sheet material obtained in Step 5, take several sheets, stack them, and wrap them with a steel clasp to obtain a wrapped and rolled clasp.

[0013] Step 7: After cladding and rolling the cladding roll obtained in Step 6 at 880℃~900℃, unclad the roll to obtain a cladding and rolled sheet with a thickness of 1mm~2mm, a width of 950mm~1250mm, and a length of 3000mm; the rolling direction of the cladding and rolling is parallel to the rolling direction of the third pass in Step 5, the deformation rate per pass is 10%~20%, and the rolling speed is 2m / s~4m / s;

[0014] Step 8: The coated and rolled sheet obtained in Step 7 is subjected to finished product heat treatment at 780℃~820℃, furnace cooled to 600℃ and then air cooled to obtain TA22 titanium alloy sheet.

[0015] This invention employs a process of reversing direction after every two rolling passes. By adjusting the reversing thickness, the difference in deformation between the transverse and longitudinal directions of the sheet metal is reduced. At the same time, quenching is used to eliminate the anisotropy of the processing flow lines and the sheet metal, resulting in higher isotropy of the sheet metal. By employing a stepped heat treatment process on the TA22 titanium alloy slab, abnormal grain growth caused by prolonged high-temperature heating is avoided. The first rolling pass is performed in the upper part of the (α+β) two-phase region, with controlled deformation rate and rolling speed to achieve a uniform microstructure and fine grain size. Then, heating in the β phase region causes an α→β transformation, forming coarse β grains, followed by rapid water cooling, which causes the β grains to transform and precipitate elongated α phases. A second rolling pass is then performed in the upper part of the (α+β) two-phase region, breaking up a large number of elongated α phases, leading to spheroidization and recrystallization, thus refining the microstructure. During the third rolling pass, the direction is reversed and the temperature is controlled to ensure sufficient and uniform deformation of the plate, while controlling the thickness difference to achieve elemental homogenization. Finally, a thin TA22 titanium alloy plate with a fine, uniform microstructure and high dimensional uniformity is prepared through cladding and over-rolling.

[0016] By cutting and using cladding and rolling during the preparation process, multiple TA22 titanium alloy sheets can be produced at once, making full use of the slab.

[0017] The above-mentioned rolling method for isotropic TA22 titanium alloy thin plates is characterized in that, in step one, the specific process of the first rolling stroke is as follows: heating to 780℃ and holding for 1.5h, then heating to 880℃~910℃ and holding for 4h~5h for rolling, with a total deformation rate of 29%~31%; the specific process of the second rolling stroke is as follows: heating to 880℃~910℃ and holding for 1h~2h for rolling, followed by air cooling, with a total deformation rate of 81%~84%; the starting rolling temperature of both the first and second rolling strokes is not lower than 860℃, and the final rolling temperature is not lower than 750℃.

[0018] The rolling method of the above-mentioned isotropic TA22 titanium alloy sheet is characterized in that the quenching process in step two is as follows: after heating to 960℃~980℃ and holding for 0.5h~1h, the sheet is taken out of the furnace and immersed in a water tank within 5s of taking it out of the furnace, and the first sheet is continuously shaken. The water tank uses circulating water, and the temperature of the circulating water is not greater than 30℃.

[0019] This invention prevents the formation of an air film on the surface of the plate from isolating heat transfer and affecting the quenching effect by keeping the plate swaying in a water tank during the quenching process and controlling the use of circulating water in the tank.

[0020] The above-mentioned rolling method for isotropic TA22 titanium alloy thin plates is characterized in that the specific process of the second rolling in step three is as follows: heating to 880℃~910℃ and holding for 1h~2h for rolling, followed by air cooling, with an initial rolling temperature of not less than 820℃, a final rolling temperature of not less than 650℃, and a total deformation rate of 45%~50%.

[0021] The rolling method of the above-mentioned isotropic TA22 titanium alloy sheet is characterized in that the specific process of the third rolling in step five is as follows: heating to 860℃~880℃ and holding for 0.5h~1h for rolling, followed by air cooling, with an initial rolling temperature of not less than 800℃, a final rolling temperature of not less than 720℃, and a total deformation rate of 30%~50%.

[0022] The rolling method for an isotropic TA22 titanium alloy sheet described above is characterized in that, in step six, before the steel cladding is applied, an anti-oxidation coating is applied to the surface of the third sheet after cutting, and both ends of the cladding ladle have vent holes.

[0023] This invention provides vent holes at both ends of the cladding roll to prevent venting during the cladding roll process and thus prevent cracking during the cladding rolling process.

[0024] The above-mentioned rolling method for isotropic TA22 titanium alloy thin plates is characterized in that the specific process of the cladding and rolling in step seven is as follows: heating to 880℃~900℃ and holding for 1h~2h for rolling, followed by air cooling, with an initial rolling temperature of not less than 850℃, a final rolling temperature of not less than 650℃, and a total deformation rate of 77%~80%.

[0025] The rolling method of the above-mentioned isotropic TA22 titanium alloy sheet is characterized in that the specific process of the heat treatment of the finished product in step eight is as follows: heating to 780℃~820℃ and holding for 60min~90min, then furnace cooling for 60min to reduce the temperature to 600℃, and then air cooling after removal from the furnace.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The preparation method of the present invention can produce TA22 titanium alloy thin plates by using three-stage hot rolling + cladding rolling + finished product heat treatment. Compared with the existing technology, which uses three-stage hot rolling + one to two semi-finished product heat treatments + one to two-stage cold rolling + finished product heat treatment, the production efficiency is effectively improved. At the same time, the TA22 titanium alloy thin plates prepared by the hot rolling process of the present invention have fewer defects and a higher yield, which reduces the cost of reprocessing defects in the later stage and reduces the difficulty of the production process.

[0028] 2. By adopting a stepped heating method, this invention effectively avoids abnormal grain growth caused by prolonged high-temperature heating of the slab; at the same time, due to the relatively reduced holding time in the high-temperature stage, the surface oxidation of the slab is less, the amount of grinding after rolling is less, and the yield is higher.

[0029] 3. This invention employs a cooling method of furnace cooling to a specific temperature followed by air cooling, which allows the board to fully recrystallize, avoiding board deformation caused by direct cooling during heat treatment, and further reducing the anisotropy of the board.

[0030] 4. This invention utilizes a process of first-stage reversing rolling + quenching + second-stage rolling + third-stage reversing rolling + cladding and stacking rolling + finished product heat treatment. Combined with temperature control during rolling and furnace cooling and air cooling during finished product heat treatment, this effectively reduces the anisotropy of the sheet metal, resulting in TA22 titanium alloy thin plates with more uniform and fine microstructure, uniform thickness, and isotropy. By combining the inherent properties of near-α-type TA22 titanium alloy with the aforementioned process design, the performance during sheet metal preparation can be controlled, ensuring coordinated deformation between the sheet metal and the steel cladding. This avoids the mismatch in deformation between the sheet metal and the steel cladding during rolling due to differences in their physical properties, which could lead to wrinkled surfaces and bulging that could damage the steel cladding and force production to stop.

[0031] 5. This invention can produce TA22 titanium alloy thin plates of different thicknesses by using a TA22 titanium alloy slab and adjusting the blanking size and the rolling thickness in the middle of the plate, thereby improving the utilization efficiency of the slab.

[0032] 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

[0033] Figure 1 This is a schematic diagram of the structure of the overlay and roll-up package of the present invention.

[0034] Figure 2 This is a high-magnification microstructure (200×) of the TA22 titanium alloy thin plate prepared in Example 1 of the present invention.

[0035] Figure 3 This is a high-magnification microstructure (200×) of the TA22 titanium alloy thin plate prepared in Example 2 of the present invention.

[0036] Figure 4 This is a high-magnification microstructure (200×) of the TA22 titanium alloy thin plate prepared in Example 3 of the present invention. Detailed Implementation

[0037] Example 1

[0038] The preparation method of this embodiment includes the following steps:

[0039] Step 1: A TA22 titanium alloy slab with a thickness of 180mm, a width of 700mm, and a length of 900mm is cross-coated with multiple layers of anti-oxidation coating. It is heated to 780℃ and held for 1.5 hours, then heated to 880℃ and held for 4 hours for the first pass of the first rolling process. The first rolling process consists of 3 passes with deformation rates of 10%, 13.6%, and 10% respectively. The rolling speed is 3m / s, and the total deformation rate is 30%, resulting in a slab with a thickness of 126mm, a width of 900mm, and a length of 1000mm. The first rolling process is unidirectional rolling.

[0040] The material is reheated online and held at 880℃ for 1 hour before undergoing the second rolling pass of the first heat treatment. The second rolling pass consists of 9 passes with deformation rates of 12.7%, 21.8%, 22.1%, 20.9%, 18.9%, 18.6%, 17.1%, 17.2%, and 16.7%, respectively. The rolling speed is 3 m / s, and the total deformation rate is 84%. After air cooling, a first plate with a thickness of 20 mm, a width of 1000 mm, and a length of 4500 mm is obtained. The rolling direction of the second rolling pass is perpendicular to the rolling direction of the first rolling pass. The starting rolling temperature of both the first and second rolling passes is 870℃, and the finishing rolling temperature of both passes is 760℃.

[0041] Step 2: Cut the first plate obtained in Step 1 to obtain multiple first plates with a thickness of 20mm, a width of 1000mm, and a length of 1500mm. After holding at 960℃ for 0.5h, remove them from the furnace. The time from removing them from the furnace to immersing them in the water tank is 4s. The first plates are continuously shaken, and the water tank uses circulating water with a temperature of 26℃.

[0042] Step 3: The first plate after quenching in Step 2 is held at 880℃ for 2 hours and then subjected to a second rolling process. The second rolling process consists of 5 passes with deformation rates of 10.0%, 11.1%, 15.6%, 14.8%, and 13.0% respectively. The rolling speed is 4 m / s, and the total deformation rate is 50%. After air cooling, a second plate with a thickness of 10 mm, a width of 1000 mm, and a length of 2900 mm is obtained. The rolling direction of the second rolling process is parallel to the rolling direction of the second pass in the first rolling process in Step 1. The initial rolling temperature is 850℃, and the final rolling temperature is 720℃.

[0043] Step 4: Cut the second sheet material obtained in Step 3 to obtain multiple second sheets material with a thickness of 10mm, a width of 1000mm, and a length of 950mm.

[0044] Step 5: The second plate obtained in Step 4 is held at 860℃ for 0.5h and then rolled in a third pass. The third pass rolling consists of 4 passes with deformation rates of 10%, 16.7%, 20.0%, and 16.7% respectively. The rolling speed is 4m / s, and the total deformation rate is 50%, resulting in a third plate with a thickness of 5mm, a width of 950mm, and a length of 1800mm. The rolling direction of the third pass rolling is perpendicular to the rolling direction of the second pass rolling in Step 3. The initial rolling temperature is 820℃, and the final rolling temperature is 735℃.

[0045] Step Six: Cut the third sheet material obtained in Step Five into pieces with a thickness of 5mm, a width of 950mm, and a length of 900mm. After cross-coating the surface with an anti-oxidation coating, stack 2-4 sheets together and assemble them into a package. Weld the steel sleeve using argon arc welding to obtain the desired result. Figure 1 The steel cladding shown is a laminated steel cladding; both ends of the steel cladding have vent holes.

[0046] Step 7: The cladding and rolling ladle obtained in Step 6 is held at 880℃ for 1 hour for cladding and rolling, followed by air cooling. After unpacking, a cladding and rolling sheet with a thickness of 1mm, a width of 950mm, and a length of 3000mm is obtained. The cladding and rolling process consists of 9 passes with deformation rates of 10.0%, 11.1%, 12.5%, 19.0%, 17.6%, 17.9%, 17.4%, 15.8%, and 11.9% respectively. The rolling speed is 4m / s, the total deformation rate is 80%, the initial rolling temperature is 860℃, the final rolling temperature is 660℃, and the rolling direction is parallel to the rolling direction of the third pass in Step 5.

[0047] Step 8: The coated and rolled sheet obtained in Step 7 is heat-treated at 780℃ for 60 minutes, then furnace-cooled for 60 minutes to 600℃, and then air-cooled to obtain a TA22 titanium alloy sheet with a thickness of 1mm, a width of 950mm, and a length of 3000mm.

[0048] Microscopic analysis was performed on the TA22 titanium alloy thin plate prepared in this embodiment, such as... Figure 2 As shown, the original β grains inside the TA22 titanium alloy sheet are fully broken, and there are no continuous grain boundaries α.

[0049] Example 2

[0050] The preparation method of this embodiment includes the following steps:

[0051] Step 1: A TA22 titanium alloy slab with a thickness of 190mm, a width of 860mm, and a length of 1050mm is cross-coated with multiple layers of anti-oxidation coating. It is heated to 780℃ and held for 1.5 hours, then heated to 900℃ and held for 4.5 hours for the first pass of the first rolling process. The first rolling process consists of two passes with deformation rates of 13.7% and 17.7% respectively. The rolling speed is 2m / s, and the total deformation rate is 29.4%, resulting in a slab with a thickness of 134mm, a width of 1050mm, and a length of 1200mm. The first rolling process is unidirectional rolling.

[0052] Then, the material is reheated online and held at 900℃ for 1.5 hours for the second rolling pass of the first heat treatment. The second rolling pass consists of 8 passes with deformation rates of 20%, 24.1%, 23.2%, 22.2%, 21.4%, 19.5%, 16.1%, and 15.4% respectively. The rolling speed is 2 m / s, and the total deformation rate is 83.5%. After air cooling, a first plate with a thickness of 22 mm, a width of 1200 mm, and a length of 5360 mm is obtained. The rolling direction of the second rolling pass is perpendicular to the rolling direction of the first rolling pass. The starting rolling temperature of both the first and second rolling passes is 885℃, and the finishing rolling temperature of both passes is 785℃.

[0053] Step 2: Cut the first plate obtained in Step 1 to obtain multiple first plates with a thickness of 22mm, a width of 1200mm, and a length of 1340mm. After holding at 970℃ for 0.5h, remove them from the furnace. The time from removing them from the furnace to entering the water tank is 3.5s. The first plates are continuously shaken, and the water tank uses circulating water with a temperature of 25℃.

[0054] Step 3: The first plate after quenching in Step 2 is held at 900℃ for 1.5 hours and then subjected to a second rolling process. The second rolling process consists of 4 passes with deformation rates of 13.6%, 15.8%, 15.6%, and 14.8% respectively. The rolling speed is 3 m / s, and the total deformation rate is 45%. After air cooling, a second plate with a thickness of 12 mm, a width of 1200 mm, and a length of 2300 mm is obtained. The rolling direction of the second rolling process is parallel to the rolling direction of the second pass in the first rolling process in Step 1. The initial rolling temperature is 870℃, and the final rolling temperature is 725℃.

[0055] Step 4: Cut the second sheet material obtained in Step 3 to obtain multiple second sheets material with a thickness of 12mm, a width of 1200mm, and a length of 1150mm.

[0056] Step 5: The second plate obtained in Step 4 is held at 870℃ for 0.5h and then rolled in a third pass. The third rolling process consists of 3 passes with deformation rates of 16.7%, 20.0%, and 12.5% ​​respectively. The rolling speed is 3m / s, and the total deformation rate is 41.6%, resulting in a third plate with a thickness of 7mm, a width of 1150mm, and a length of 1850mm. The rolling direction of the third rolling process is perpendicular to the rolling direction of the second rolling process in Step 3. The initial rolling temperature is 825℃, and the final rolling temperature is 740℃.

[0057] Step Six: Cut the third sheet material obtained in Step Five into pieces with a thickness of 7mm, a width of 1150mm, and a length of 925mm. After cross-coating the surface with an anti-oxidation coating, stack 2-4 sheets together and assemble them into a package. Weld the steel sleeve using argon arc welding to obtain the desired result. Figure 1 The steel cladding shown is a laminated steel cladding; both ends of the steel cladding have vent holes.

[0058] Step 7: The cladding and rolling ladle obtained in Step 6 is held at 890℃ for 1.5h for cladding and rolling, followed by air cooling. After unpacking, a cladding and rolling sheet with a thickness of 1.5mm, a width of 1150mm, and a length of 3000mm is obtained. The cladding and rolling process consists of 8 passes, with deformation rates of 11.5%, 14.8%, 15.2%, 17.9%, 18.8%, 23.1%, 15.0%, and 14.7% respectively. The rolling speed is 3m / s, the total deformation rate is 78.5%, the initial rolling temperature is 870℃, the final rolling temperature is 680℃, and the rolling direction is parallel to the rolling direction of the third pass in Step 5.

[0059] Step 8: The coated and rolled sheet obtained in Step 7 is heat-treated at 800℃ for 75 minutes, then furnace-cooled to 600℃ for 60 minutes, and then air-cooled to obtain a TA22 titanium alloy sheet with a thickness of 1.5mm, a width of 1150mm, and a length of 3000mm.

[0060] Microscopic analysis was performed on the TA22 titanium alloy thin plate prepared in this embodiment, such as... Figure 3 As shown, the original β grains inside the TA22 titanium alloy sheet are fully broken, and there are no continuous grain boundaries α.

[0061] Example 3

[0062] The preparation method of this embodiment includes the following steps:

[0063] Step 1: A TA22 titanium alloy slab with a thickness of 200mm, a width of 900mm, and a length of 1200mm is cross-coated with multiple layers of anti-oxidation coating. It is then heated to 780℃ and held for 1.5 hours, followed by heating to 910℃ and holding for 5 hours for the first rolling pass. The first rolling pass consists of three passes with deformation rates of 9%, 13.2%, and 12.7% respectively. The rolling speed is 1.5m / s, and the total deformation rate is 31%, resulting in a slab with a thickness of 138mm, a width of 900mm, and a length of 1300mm. The first rolling pass is a unidirectional rolling process.

[0064] The material is reheated online and held at 910℃ for 1 hour before undergoing the second rolling pass of the first heat treatment. The second rolling pass consists of 7 passes with deformation rates of 18.8%, 24.1%, 23.5%, 23.1%, 22.0%, 20.5%, and 16.1% respectively. The rolling speed is 1.5 m / s, and the total deformation rate is 81.8%. After air cooling, a first plate with a thickness of 25 mm, a width of 1300 mm, and a length of 5600 mm is obtained. The rolling direction of the second rolling pass is perpendicular to the rolling direction of the first rolling pass. The starting rolling temperature of both the first and second rolling passes is 892℃, and the finishing rolling temperature of both passes is 790℃.

[0065] Step 2: Cut the first plate obtained in Step 1 to obtain multiple first plates with a thickness of 25mm, a width of 1300mm, and a length of 1400mm. After holding at 980℃ for 1 hour, remove them from the furnace. The time from removing them from the furnace to entering the water tank is 4.3 seconds. The first plates are continuously shaken, and the water tank uses circulating water with a temperature of 20℃.

[0066] Step 3: The first plate after quenching in Step 2 is held at 910℃ for 1 hour and then rolled in a second pass. The second rolling process consists of 3 passes with deformation rates of 20.0%, 20.0%, and 18.8% respectively. The rolling speed is 2m / s, and the total deformation rate is 48%. After air cooling, a second plate with a thickness of 13mm, a width of 1300mm, and a length of 2500mm is obtained. The rolling direction of the second rolling process is parallel to the rolling direction of the second pass in the first rolling process in Step 1. The initial rolling temperature is 875℃, and the final rolling temperature is 710℃.

[0067] Step 4: Cut the second sheet material obtained in Step 3 to obtain multiple second sheets material with a thickness of 13mm, a width of 1300mm, and a length of 1250mm.

[0068] Step 5: The second plate obtained in Step 4 is held at 880℃ for 1 hour and then rolled in a third pass. The third rolling is carried out in two passes with deformation rates of 15.4% and 18.2% respectively. The rolling speed is 3m / s, and the total deformation rate is 30.7%, resulting in a third plate with a thickness of 9mm, a width of 1250mm, and a length of 1700mm. The rolling direction of the third rolling is perpendicular to the rolling direction of the second rolling in Step 3. The initial rolling temperature is 835℃, and the final rolling temperature is 745℃.

[0069] Step Six: Cut the third sheet material obtained in Step Five into pieces with a thickness of 9mm, a width of 1250mm, and a length of 850mm. After cross-coating the surface with an anti-oxidation coating, stack 2-4 sheets together and assemble them into a package. Weld the steel sleeve using argon arc welding to obtain the desired result. Figure 1 The steel cladding shown is a laminated steel cladding; both ends of the steel cladding have vent holes.

[0070] Step 7: The cladding and rolling ladle obtained in Step 6 is held at 900℃ for 2 hours for cladding and rolling, followed by air cooling. After unpacking, a cladding and rolling sheet with a thickness of 2mm, a width of 1250mm, and a length of 3000mm is obtained. The cladding and rolling process consists of 7 passes with deformation rates of 12.1%, 17.6%, 19.0%, 20.6%, 22.2%, 19.0%, and 18.2% respectively. The rolling speed is 2m / s, the total deformation rate is 77.8%, the initial rolling temperature is 880℃, the final rolling temperature is 690℃, and the rolling direction is parallel to the rolling direction of the third pass in Step 5.

[0071] Step 8: The coated and rolled sheet obtained in Step 7 is heat-treated at 820℃ for 90 minutes, then furnace-cooled to 600℃ for 60 minutes, and then air-cooled to obtain a TA22 titanium alloy sheet with a thickness of 2mm, a width of 1250mm, and a length of 3000mm.

[0072] Microscopic analysis was performed on the TA22 titanium alloy thin plate prepared in this embodiment, such as... Figure 4 As shown, the original β grains inside the TA22 titanium alloy sheet are fully broken, and there are no continuous grain boundaries α.

[0073] Comparative Example 1

[0074] The preparation method of this comparative example includes the following steps:

[0075] Step 1: Cross-coat the surface of a TA22 titanium alloy slab with a thickness of 180mm, a width of 1000mm, and a length of 1200mm with multiple layers of anti-oxidation coating, and perform the first rolling at 900℃ for 1 hour to obtain a first plate with a thickness of 20mm, a width of 1000mm, and a length of 10000mm.

[0076] Step 2: Cut the first plate obtained in Step 1 to obtain multiple first plates with a thickness of 20mm, a width of 1000mm, and a length of 1700mm. After holding at 960℃ for 0.5h, remove them from the furnace. The time from removing them from the furnace to entering the water tank is 4s. The water tank uses circulating water with a temperature of 26℃.

[0077] Step 3: The first plate after quenching in Step 2 is held at 880℃ for 2 hours and then subjected to a second rolling process. After air cooling, a second plate with a thickness of 10mm, a width of 1000mm, and a length of 3200mm is obtained. The rolling direction of the second rolling process is parallel to the rolling direction of the first rolling process in Step 1. The initial rolling temperature is 850℃, and the final rolling temperature is 720℃.

[0078] Step 4: Cut the second sheet material obtained in Step 3 to obtain multiple second sheets material with a thickness of 10mm, a width of 1000mm, and a length of 1050mm.

[0079] Step 5: The second plate obtained in Step 4 is held at 860℃ for 0.5h and then rolled in a third pass. The third pass consists of 4 passes to obtain a third plate with a thickness of 3.6mm, a width of 1050mm, and a length of 2500mm. The rolling direction of the third pass is perpendicular to the rolling direction of the second pass in Step 3. The initial rolling temperature is 820℃, and the final rolling temperature is 735℃.

[0080] Step 6: The third sheet material obtained in Step 5 is subjected to semi-finished product annealing treatment at a temperature of 850℃ for 1 hour.

[0081] Step 7: Cut the third sheet material after the semi-finished product annealing treatment in Step 6. The thickness of the cut sheet material is 3.6mm, the width is 1050mm, and the length is 1200mm.

[0082] The first cold rolling process was then carried out to obtain a first cold-rolled sheet with a thickness of 2.0 mm, a width of 1050 mm, and a length of 2000 mm.

[0083] Step 8: The first cold-rolled sheet obtained in Step 7 is subjected to semi-finished product annealing treatment at a temperature of 820℃ for 1 hour.

[0084] Step 9: The first cold-rolled sheet after the semi-finished product annealing treatment in Step 8 is subjected to a second rolling cold rolling process to obtain a second cold-rolled sheet with a thickness of 1.0 mm, a width of 1050 mm, and a length of 3600 mm.

[0085] Step 10: Heat-treat the second cold-rolled sheet obtained in Step 9 at 780℃ for 60 minutes, and then air-cool it to obtain a TA22 titanium alloy sheet with a thickness of 1.0 mm, a width of 1050 mm, and a length of 3600 mm.

[0086] Comparative Example 2

[0087] The preparation method of this comparative example includes the following steps:

[0088] Step 1: Cross-coat the surface of a TA22 titanium alloy slab with a thickness of 180mm, a width of 1000mm, and a length of 1200mm with multiple layers of anti-oxidation coating, and perform the first rolling at 900℃ for 1 hour to obtain a first plate with a thickness of 20mm, a width of 1000mm, and a length of 10000mm.

[0089] Step 2: Cut the first plate obtained in Step 1 to obtain multiple first plates with a thickness of 20mm, a width of 1000mm, and a length of 1700mm. After holding at 960℃ for 0.5h, remove them from the furnace. The time from removing them from the furnace to entering the water tank is 4s. The water tank uses circulating water with a temperature of 26℃.

[0090] Step 3: The first plate after quenching in Step 2 is held at 880℃ for 2 hours and then subjected to a second rolling process. After air cooling, a second plate with a thickness of 10mm, a width of 1000mm, and a length of 3200mm is obtained. The rolling direction of the second rolling process is parallel to the rolling direction of the first rolling process in Step 1. The initial rolling temperature is 850℃, and the final rolling temperature is 720℃.

[0091] Step 4: Cut the second sheet material obtained in Step 3 to obtain multiple second sheets material with a thickness of 10mm, a width of 1000mm, and a length of 1050mm.

[0092] Step 5: The second plate obtained in Step 4 is held at 860℃ for 0.5h and then rolled in a third pass. The third pass consists of 4 passes to obtain a third plate with a thickness of 3.6mm, a width of 1050mm, and a length of 2500mm. The rolling direction of the third pass is perpendicular to the rolling direction of the second pass in Step 3. The initial rolling temperature is 820℃, and the final rolling temperature is 735℃.

[0093] Step 6: The third sheet material obtained in Step 5 is subjected to semi-finished product annealing treatment at a temperature of 850℃ for 1 hour.

[0094] Step 7: Cut the third sheet material after the semi-finished product annealing treatment in Step 6. The thickness of the cut sheet material is 3.6mm, the width is 1050mm, and the length is 1200mm.

[0095] The first cold rolling process was then carried out to obtain a first cold-rolled sheet with a thickness of 2.2 mm, a width of 1050 mm, and a length of 1800 mm.

[0096] Step 8: The first cold-rolled sheet obtained in Step 7 is subjected to semi-finished product annealing treatment at a temperature of 820℃ for 1 hour.

[0097] Step 9: Perform a second cold rolling on the first cold-rolled sheet after the semi-finished product annealing treatment in Step 8 to obtain a second cold-rolled sheet with a thickness of 1.5mm, a width of 1050mm, and a length of 2400mm.

[0098] Step 10: Heat-treat the second cold-rolled sheet obtained in Step 9 at 780℃ for 60 minutes, and then air-cool it to obtain a TA22 titanium alloy sheet with a thickness of 1.5mm, a width of 1050mm, and a length of 2400mm.

[0099] Comparative Example 3

[0100] The preparation method of this comparative example includes the following steps:

[0101] Step 1: Cross-coat the surface of a TA22 titanium alloy slab with a thickness of 180mm, a width of 1000mm, and a length of 1200mm with multiple layers of anti-oxidation coating, and perform the first rolling at 900℃ for 1 hour to obtain a first plate with a thickness of 20mm, a width of 1000mm, and a length of 10000mm.

[0102] Step 2: Cut the first plate obtained in Step 1 to obtain multiple first plates with a thickness of 20mm, a width of 1000mm, and a length of 1700mm. After holding at 960℃ for 0.5h, remove them from the furnace. The time from removing them from the furnace to entering the water tank is 4s. The water tank uses circulating water with a temperature of 26℃.

[0103] Step 3: The first plate after quenching in Step 2 is held at 880℃ for 2 hours and then rolled in a second heat. After air cooling, a second plate with a thickness of 10mm, a width of 1000mm, and a length of 3200mm is obtained. The rolling direction of the second heat rolling is parallel to the rolling direction of the first heat rolling in Step 1. The initial rolling temperature is 850℃ and the final rolling temperature is 720℃.

[0104] Step 4: Cut the second sheet material obtained in Step 3 to obtain multiple second sheets material with a thickness of 10mm, a width of 1000mm, and a length of 1050mm.

[0105] Step 5: The second plate obtained in Step 4 is held at 860℃ for 0.5h and then rolled in a third pass. The third pass consists of 4 passes to obtain a third plate with a thickness of 3.6mm, a width of 1050mm, and a length of 2500mm. The rolling direction of the third pass is perpendicular to the rolling direction of the second pass in Step 3. The initial rolling temperature is 820℃, and the final rolling temperature is 735℃.

[0106] Step 6: The third sheet material obtained in Step 5 is subjected to semi-finished product annealing treatment at a temperature of 850℃ for 1 hour.

[0107] Step 7: The third sheet material after the semi-finished product annealing treatment in Step 6 is subjected to a first cold rolling to obtain a first cold-rolled sheet material with a thickness of 2mm, a width of 1050mm, and a length of 4200mm.

[0108] Step 8: The first cold-rolled sheet obtained in Step 7 is heat-treated at 780℃ for 60 minutes, and then air-cooled to obtain a TA22 titanium alloy sheet with a thickness of 1.5mm, a width of 1050mm, and a length of 2400mm.

[0109] The performance of the TA22 titanium alloy thin plates prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the results are shown in Table 1.

[0110] Table 1 Performance data of TA22 titanium alloy sheet

[0111]

[0112] As shown in Table 1, the transverse and longitudinal properties of the TA22 titanium alloy sheets prepared in Examples 1-3 all meet the requirements of GJB 944A-2018 "Specification for Titanium and Titanium Alloy Sheets for Ships". Compared with Examples 1-3, the difference in transverse and longitudinal room temperature tensile strength and yield strength of the TA22 titanium alloy sheets in Comparative Examples 1-3 is larger. The sheets prepared by the process of three-stage hot rolling + one to two semi-finished product heat treatments + one to two-stage cold rolling + finished product heat treatment have greater anisotropy. The anisotropy of the sheets should be fully considered when using them, which will limit the subsequent processing and use of the sheets and also affect their service life. In contrast, the process of three-stage rolling + cladding rolling + finished product heat treatment of the present invention can produce isotropic TA22 titanium alloy sheets.

[0113] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A rolling method for isotropic TA22 titanium alloy thin plates, characterized in that, Includes the following steps: Step 1: Heat a TA22 titanium alloy slab with a thickness of 180mm~200mm, a width of 700mm~900mm, and a length of 900mm~1200mm to 780℃, and then perform the first rolling pass at 880℃~910℃ to obtain a slab with a thickness of 126mm~138mm, a width of 900mm~1200mm, and a length of 1000mm~1300mm. The first rolling pass is unidirectional rolling, with a pass deformation rate of 8%~20% and a rolling speed of 1.5m / s~3m / s. The specific process of the first rolling pass is as follows: heat to 780℃ and hold for 1.5h, then raise the temperature to 880℃~910℃ and hold for 4h~5h for rolling, with a total deformation rate of 29%~31%. The first rolling pass involves online reheating and a second rolling pass at 880℃~910℃ to obtain a first plate with a thickness of 20mm~25mm, a width of 1000mm~1300mm, and a length of 4500mm~5600mm. The rolling direction of the second rolling pass is perpendicular to that of the first rolling pass, with a pass deformation rate of 10%~25% and a rolling speed of 1.5m / s~3m / s. The specific process of the second rolling pass is as follows: heating to 880℃~910℃ and holding for 1h~2h for rolling, followed by air cooling, with a total deformation rate of 81%~84%. The initial rolling temperature of both the first and second rolling passes is not lower than 860℃, and the final rolling temperature is not lower than 750℃. Step 2: Cut the first plate obtained in Step 1 and quench it in the β phase region; Step 3: The first plate, after quenching in Step 2, is subjected to a second rolling process at 880℃~910℃ to obtain a second plate with a thickness of 10mm~13mm, a width of 1000mm~1300mm, and a length of 2300mm~2900mm. The rolling direction of the second rolling process is parallel to the rolling direction of the second rolling pass in Step 1. The deformation rate per pass is 10%~25%, and the rolling speed is 2m / s~4m / s. The specific process of the second rolling process is as follows: heating to 880℃~910℃ and holding for 1h~2h for rolling, followed by air cooling. The initial rolling temperature is not lower than 820℃, the final rolling temperature is not lower than 650℃, and the total deformation rate is 45%~50%. Step 4: Cut the second sheet material obtained in Step 3; Step 5: The second sheet material cut in Step 4 is subjected to a third rolling process at 860℃~880℃ to obtain a third sheet material with a thickness of 5mm~9mm, a width of 950mm~1250mm, and a length of 1700mm~1900mm. The rolling direction of the third rolling process is perpendicular to the rolling direction of the second rolling process in Step 3. The deformation rate per pass is 10%~25%, and the rolling speed is 3m / s~4m / s. The specific process of the third rolling process is as follows: heating to 860℃~880℃ and holding for 0.5h~1h for rolling, followed by air cooling. The initial rolling temperature is not lower than 800℃, the final rolling temperature is not lower than 720℃, and the total deformation rate is 30%~50%. Step 6: Cut the third sheet material obtained in Step 5, take several sheets, stack them, and wrap them with a steel clasp to obtain a wrapped and rolled clasp. Step 7: After cladding and rolling the cladding roll obtained in Step 6 at 880℃~900℃, unclad the roll to obtain a cladding and rolled sheet with a thickness of 1mm~2mm, a width of 950mm~1250mm, and a length of 3000mm; the rolling direction of the cladding and rolling is parallel to the rolling direction of the third pass in Step 5, the deformation rate per pass is 10%~20%, and the rolling speed is 2m / s~4m / s; Step 8: The coated and rolled sheet obtained in Step 7 is subjected to finished product heat treatment at 780℃~820℃, furnace cooled to 600℃ and then air cooled to obtain TA22 titanium alloy sheet.

2. The rolling method for an isotropic TA22 titanium alloy sheet according to claim 1, characterized in that, The specific quenching process described in step two is as follows: after heating to 960℃~980℃ and holding for 0.5h~1h, the plate is taken out of the furnace and immersed in a water tank within 5s of being taken out of the furnace, while the first plate is continuously shaken. The water tank uses circulating water, and the temperature of the circulating water does not exceed 30℃.

3. The rolling method for an isotropic TA22 titanium alloy sheet according to claim 1, characterized in that, In step six, before covering the steel cladding, the surface of the third plate after cutting is cross-coated with an anti-oxidation coating, and both ends of the covered and stacked cladding have vent holes.

4. The rolling method for an isotropic TA22 titanium alloy sheet according to claim 1, characterized in that, The specific process of the cladding and rolling described in step seven is as follows: heat to 880℃~900℃ and hold for 1h~2h for rolling, then air cool. The initial rolling temperature is not lower than 850℃, the final rolling temperature is not lower than 650℃, and the total deformation rate is 77%~80%.

5. The rolling method for an isotropic TA22 titanium alloy sheet according to claim 1, characterized in that, The specific process of heat treatment of the finished product in step eight is as follows: heat to 780℃~820℃ and hold for 60min~90min, then furnace cool for 60min to reduce the temperature to 600℃, and then remove from the furnace and air cool.

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