Rolling method of TA21 titanium alloy sheet

Abstract

The invention discloses a method for rolling a TA21 titanium alloy sheet. The method comprises the following steps: 1, coating the surface of a TA21 titanium alloy plate blank with an anti-oxidation coating; 2, rolling for the first heating number; 3, cutting treatment; 4, rolling for the second heating number; and 5, cutting. 6, quenching treatment; 7, rolling for the third heating number; 8, cutting treatment; 9, annealing the semi-finished product; 10, cold rolling; and 11, annealing a finished product. According to the method, first two-heating-number rolling is carried out in a two-phase region, coarse beta grains are formed in combination with quenching and heat preservation, a long-strip-shaped alpha phase is separated out from a coarse beta phase through rapid water cooling to form a needle-shaped widmannstatten structure, then one-heating-number reversing large-deformation rolling and cold rolling are carried out in the two-phase region, a large number of structures are crushed and refined, the needle-shaped widmannstatten structure is spheroidized, and the needle-shaped widmannstatten structure is obtained. The TA21 titanium alloy thin plate with fine and uniform tissue is obtained, the plate blank is fully utilized, and the production efficiency is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium and titanium alloy thin plate preparation, and specifically relates to a rolling method for a TA21 titanium alloy thin plate. Background Art

[0002] TA21 titanium alloy is a low-alloyed Ti-Al-Mn near-α-type titanium alloy, and its nominal composition (mass fraction, %) is Ti-1Al-1Mn. The alloy has a long-term working temperature of 300°C and is used to manufacture cold-formed and welded parts of pipes with complex shapes and low strength requirements. The characteristics of TA21 titanium alloy are low strength, high process plasticity, good welding performance and thermal stability. There are few studies on the rolling of TA21 titanium alloy sheets in China, and the relevant literature recommends hot working in the two-phase zone + heat treatment in the two-phase zone. According to the traditional process, when preparing thin plates, the near-α-type titanium alloy generally adopts the method of multi-fire reversing hot rolling + cold rolling in the two-phase zone. The near-α-type titanium alloy prepared in this way is prone to edge cracking and poor quality of the head and tail of the thin plate during reversing rolling, which seriously increases the workload of surface treatment, cutting and other processes, and the process is complicated. In addition, due to the increase in the amount of surface treatment mentioned above, if the process control is not appropriate, the titanium alloy thin plates produced will have large differences in the same plate, and the mechanical properties will be different. Therefore, technical improvements are urgently needed. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a rolling method for TA21 titanium alloy thin plates in view of the deficiencies of the above-mentioned prior art. The method performs the first two rounds of rolling in the two-phase region of the TA21 titanium alloy slab, combines quenching and heat preservation to form coarse β grains, and uses rapid water cooling to precipitate long strips of α phase in the coarse β phase to form a needle-like Widmanstatten structure, and then performs one round of reversing large deformation rolling and cold rolling in the two-phase region to crush and refine the structure in large quantities, so that the needle-like Widmanstatten structure is spheroidized, and a TA21 titanium alloy thin plate with fine and uniform structure is obtained, which solves the problem of large workload, poor quality and poor mechanical properties in the production of titanium alloy thin plates by traditional processes.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a rolling method of TA21 titanium alloy sheet, characterized in that the method comprises the following steps:

[0005] Step 1: coating the surface of a TA21 titanium alloy slab with an anti-oxidation coating; the TA21 titanium alloy slab has a thickness of 140 mm to 180 mm, a width of 800 mm to 1100 mm, and a length of 800 mm to 1400 mm;

[0006] Step 2, the TA21 titanium alloy slab treated in step 1 is subjected to a first heat rolling at a temperature of 880°C to 900°C to obtain a first rolled slab; the first heat rolling is unidirectional rolling, the pass deformation rate of the first heat rolling is 8% to 25%, the number of passes is 6 to 8, and the rolling rate is 3m / s to 4m / s; the thickness of the first rolled slab is 20mm to 30mm, and the width is 800mm to 1100mm;

[0007] Step 3: cutting the first rolled slab obtained in step 2 to obtain a plurality of first intermediate slabs; the first intermediate slabs have a thickness of 20 mm to 30 mm, a width of 800 mm to 1100 mm, and a length of 1000 mm to 1600 mm;

[0008] Step 4, the first intermediate slab obtained in step 3 is subjected to a second rolling at a temperature of 850°C to 880°C, and is returned to the furnace online for temperature compensation to obtain a second rolled slab; the deformation rate of the second rolling is 10% to 25%, the number of passes is 4 to 6, the rolling rate is 3m / s to 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 to 15mm, and the width is 800mm to 1100mm;

[0009] Step 5: cutting the second rolled slab obtained in step 4 to obtain a plurality of second intermediate slabs; the second intermediate slabs have a thickness of 10 mm to 15 mm, a width of 800 mm to 1100 mm, and a length of 1000 mm to 1300 mm;

[0010] Step 6: quenching the second intermediate slab obtained in step 5;

[0011] Step 7, the second intermediate slab after quenching in step 6 is subjected to a third heat rolling at a temperature of 800°C to 830°C to obtain a third rolled slab; the pass deformation rate of the third heat rolling is 10% to 25%, the rolling rate is 3m / s to 4m / s, and the rolling direction of the third heat rolling is perpendicular to the rolling direction of the second heat rolling in step 4, and the thickness of the third rolled slab is 3.6mm to 4mm, and the width is 1000mm to 1300mm;

[0012] Step 8: Cut the third rolled slab obtained in step 7 to obtain a plurality of third intermediate slabs; the third intermediate slabs have a thickness of 3.6 mm to 4 mm, a width of 1000 mm to 1300 mm, and a length of 1000 mm to 1500 mm;

[0013] Step nine, subjecting the third intermediate slab obtained in step eight to semi-finished product annealing treatment at a temperature of 700° C. to 750° C.;

[0014] Step 10, cold rolling the third intermediate slab after the semi-finished product annealing treatment in step 9 to obtain a TA21 titanium alloy cold-rolled plate; the pass deformation rate of the cold rolling is 5% to 20%, and the rolling direction of the cold rolling is the same as the rolling direction of the third fire rolling in step 7; the TA21 titanium alloy cold-rolled plate has a thickness of 1.2 mm to 2.0 mm, a width of 1000 mm to 1300 mm, and a length of 2800 mm to 3200 mm;

[0015] Step 11: subject the TA21 titanium alloy cold-rolled sheet obtained in step 10 to finished product annealing treatment, and then air-cool it to room temperature to obtain a titanium alloy thin plate; the TA21 titanium alloy thin plate has a thickness of 1.2 mm to 2.0 mm, a width of 1000 mm to 1300 mm, and a length of 2800 mm to 3200 mm.

[0016] The present invention sequentially performs first-time rolling, cutting, second-time rolling, cutting, quenching, third-time rolling, cutting, semi-finished product annealing, cold rolling and finished product annealing on a TA21 titanium alloy slab to obtain a TA21 titanium alloy thin plate. In this process, the TA21 titanium alloy slab is firstly rolled in the two-phase region for the first two heats, and the deformation rate and rolling rate of the first two heats are precisely controlled, combined with quenching and heat preservation above the β phase transformation point, so that a coarse β phase is formed at this temperature, and then rapid water cooling is achieved through quenching treatment, so that long strips of α phase are precipitated in the coarse β phase to form a needle-like Widmanstatten structure; in addition, the quenching treatment is used to eliminate or weaken the plate texture, reduce the anisotropy of the plate, and improve the edge cracking problem of the plate after rolling; then, a heat reversing large deformation rolling and cold rolling are carried out in the two-phase region to crush and refine the structure in large quantities, so that the needle-like Widmanstatten structure is spheroidized; and then the finished product is annealed to obtain a TA21 titanium alloy sheet with fine and uniform structure.

[0017] In addition, 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 head and tail of thin plates when the titanium alloy is directly reversed and rolled without quenching, thereby reducing the workload of processes such as surface treatment and cutting; at the same time, a piece of TA21 titanium alloy slab can be used to produce TA21 titanium alloy thin plates of various specifications, greatly improving production efficiency.

[0018] In summary, the present invention utilizes the low strength and high plasticity of TA21 titanium alloy as a near-α alloy, and adopts the method of multi-fire two-phase zone reversing cross rolling + quenching + cold rolling to prepare TA21 titanium alloy thin plate with uniform and fine equiaxed α grains in the metallographic structure and mechanical properties that meet the requirements.

[0019] The above-mentioned method for rolling TA21 titanium alloy thin plate is characterized in that in step one, the surface of the TA21 titanium alloy slab is cross-coated with a TB920 anti-oxidation coating, and the direction of the last coating of the TB920 anti-oxidation coating is the direction of the first fire rolling in step two.

[0020] The above-mentioned rolling method of a TA21 titanium alloy sheet is characterized in that the specific process of the first rolling in step 2 is: keeping at 880°C to 900°C for 3h to 6h, the starting rolling temperature of the first rolling is not less than 860°C, the final rolling temperature is not less than 650°C, and the total deformation rate of the first rolling is 60% to 90%. By controlling the final rolling temperature and 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 of a TA21 titanium alloy sheet is characterized in that the specific process of the second rolling in step 4 is: keeping at 850°C to 880°C for 1h to 2h, the starting rolling temperature of the second rolling is not less than 800°C, the final rolling temperature is not less than 550°C, and the total deformation rate of the second rolling is 50% to 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 method for rolling a TA21 titanium alloy sheet is characterized in that the specific process of the quenching treatment in step six is: heat preservation at 940℃~980℃ for 0.5h~1h, the time from the second intermediate slab being taken out of the furnace to entering the water is not more than 10s, and the water temperature is not more than 30℃. By controlling the heat preservation temperature, water entry time and water temperature of the quenching treatment, it is ensured that a coarse β phase is formed first, and through rapid water cooling, a long strip of α phase is precipitated in the coarse β phase to form a needle-shaped Widmanstatten structure; in addition, the quenching treatment eliminates or weakens the plate texture, reduces the anisotropy of the plate, and improves the problem of edge cracking of the plate after rolling.

[0023] The above-mentioned method for rolling TA21 titanium alloy thin plate is characterized in that the specific process of the third rolling in step seven is: keeping warm at 800℃~830℃ for 1h~2h, the third rolling is reversing rolling, the starting 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 method for rolling a TA21 titanium alloy sheet is characterized in that the specific process of the semi-finished product annealing treatment in step nine is: keeping the temperature 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, the deformed grains are transformed into equiaxed grains through recrystallization, the plasticity of the third intermediate slab is improved, and the deformation resistance of the third intermediate slab during cold rolling is reduced, which is convenient for cold rolling.

[0025] The above-mentioned method for rolling TA21 titanium alloy thin plate is characterized in that the specific process of the finished product annealing treatment in step eleven is: keeping warm at 600°C to 650°C for 0.5h to 1h.

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

[0027] 1. The present invention performs the first two hot rollings in the two-phase region of the TA21 titanium alloy slab, and then performs quenching and heat preservation above the β phase transformation point to form a coarse β phase, and uses a rapid water cooling quenching treatment to precipitate a long strip of α phase in the coarse β phase to form a needle-like Widmanstatten structure, and then performs a hot reversing large deformation rolling and cold rolling in the two-phase region to crush and refine the structure in large quantities, so that the needle-like Widmanstatten structure is spheroidized, and a TA21 titanium alloy sheet with a fine and uniform structure is obtained.

[0028] 2. The present invention adopts multi-fire two-phase zone reversing cross rolling combined with quenching treatment, and accurately controls the rolling deformation rate and rolling rate of each fire, and after the intermediate fire rolling, i.e. the second fire rolling, the intermediate slabs of different widths are obtained by cutting for subsequent rolling, which effectively eliminates and weakens the plate texture, reduces the anisotropy of the plate, and reduces the obvious cracking of the titanium alloy plate caused by traditional production processes. At the same time, it reduces the amount of later grinding, saves costs, and reduces the difficulty in the production process.

[0029] 3. Under the premise of ensuring the acquisition of TA21 titanium alloy thin plates, the rolling method of the present invention can produce TA21 titanium alloy thin plates of various specifications using one TA21 titanium alloy slab, thereby fully utilizing the slab and greatly improving production efficiency.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the metallographic structure diagram (500×) of the TA21 titanium alloy sheet prepared in Example 1 of the present invention.

[0032] Figure 2 This is the metallographic structure diagram (500×) of the TA21 titanium alloy sheet prepared in Example 2 of the present invention.

[0033] Figure 3 This is the metallographic structure diagram (500×) of the TA21 titanium alloy sheet prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0034] Example 1

[0035] This embodiment includes the following steps:

[0036] Step 1: Cross-coating the TA21 titanium alloy slab with a TB920 anti-oxidation coating, and the direction of the last coating of the TB920 anti-oxidation coating is the direction of the first hot rolling in step 2; the TA21 titanium alloy slab has a thickness of 140 mm, a width of 800 mm, and a length of 800 mm;

[0037] Step 2, the TA21 titanium alloy slab treated in step 1 is kept at a temperature of 800°C for 3h and then subjected to the first fire rolling to obtain a first rolled slab; the first fire rolling is unidirectional rolling, and the pass deformation rates of the first fire rolling are 12.1%, 17.9%, 24.8%, 25.0%, 24.6%, 23.3%, 22.7%, and 22.6% respectively, the number of passes is 8, and the rolling rate is 3m / s; the thickness of the first rolled slab is 20mm, the width is 800mm, the start rolling temperature of the first fire rolling is 867°C, the final rolling temperature is 700°C, and the total deformation rate of the first fire rolling is 85%;

[0038] Step 3: cutting the first rolled slab obtained in step 2 to obtain a plurality of first intermediate slabs; the first intermediate slabs have a thickness of 20 mm, a width of 800 mm, and a length of 1050 mm;

[0039] Step 4: The first intermediate slab obtained in step 3 is kept at a temperature of 850°C for 2h and then subjected to a second heat rolling, and the slab is returned to the furnace for online temperature compensation to obtain a second rolled slab; the deformation rates of the second heat rolling are 15%, 17.6%, 17.9%, and 13% respectively, the number of passes is 4, the rolling rate is 3m / s, and the rolling direction of the second heat rolling is parallel to the rolling direction of the first heat rolling in step 2, the starting rolling temperature of the second heat rolling is 830°C, the final rolling temperature is 600°C, and the total deformation rate of the second heat rolling is 50%; the thickness of the second rolled slab is 10mm and the width is 800mm;

[0040] Step 5: cutting the second rolled slab obtained in step 4 to obtain a plurality of second intermediate slabs; the second intermediate slabs have a thickness of 10 mm, a width of 800 mm, and a length of 1000 mm;

[0041] Step 6: quench the second intermediate slab obtained in step 5; the specific process of the quenching treatment is: keep the temperature at 940°C for 0.5h, the time from the second intermediate slab being taken out of the furnace to entering the water is not more than 10s, and the water temperature is not more than 30°C;

[0042] Step 7, the second intermediate slab after quenching treatment in step 6 is kept at a temperature of 800°C for 1h and then subjected to a third rolling to obtain a third rolled slab; the pass deformation rates of the third rolling are 16.7%, 20%, 23.8%, and 23% respectively, the rolling rate is 3m / s, and the rolling direction of the third rolling is perpendicular to the rolling direction of the second rolling in step 4, the starting rolling temperature of the third rolling is 760°C, the final rolling temperature is 500°C, and the total deformation rate of the third rolling is 64%; the thickness of the third rolled slab is 3.6mm and the width is 1000mm;

[0043] Step 8: Cut the third rolled slab obtained in step 7 to obtain a plurality of third intermediate slabs; the third intermediate slabs have a thickness of 3.6 mm, a width of 1000 mm, and a length of 1050 mm;

[0044] Step 9: subjecting the third intermediate slab obtained in step 8 to semi-finished product annealing treatment by keeping the temperature at 700° C. for 0.5 h;

[0045] Step 10, cold rolling the third intermediate slab after the semi-finished product annealing treatment in step 9 to obtain a TA21 titanium alloy cold-rolled plate; 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 the rolling direction of the third hot rolling in step 7; the TA21 titanium alloy cold-rolled plate has a thickness of 1.2 mm, a width of 1000 mm, and a length of 3000 mm;

[0046] Step 11. Straighten the TA21 titanium alloy cold-rolled sheet obtained in step 10, keep it at 600°C for 1h for finished product annealing, and then air-cool it to room temperature to obtain a titanium alloy thin plate; the TA21 titanium alloy thin plate has a thickness of 1.2mm, a width of 1000mm, and a length of 3000mm.

[0047] Figure 1 The metallographic structure diagram (500×) of the TA21 titanium alloy sheet prepared in this embodiment is shown in FIG. Figure 1 It can be seen that the metallographic structure of the TA21 titanium alloy sheet is a uniform and fine structure without the presence of needle-like structure.

[0048] After testing, the room temperature tensile strength of the TA21 titanium alloy sheet prepared in this embodiment is 550MPa-560MPa, the yield strength is 510MPa-520MPa, the elongation after fracture is 30%-40%, the bending meets 2T, 100°, the low-magnification structure has no metal and non-metal inclusions and other visually visible defects, and the high-magnification structure has no needle-like structure. It meets the requirements of the enterprise's "Technical Conditions for TA21 Titanium Alloy Sheets for Aviation Use".

[0049] In summary, the metallographic structure of the TA21 titanium alloy prepared in this embodiment meets the structural requirements of the TA21 single-phase titanium alloy and has excellent mechanical properties.

[0050] Example 2

[0051] This embodiment includes the following steps:

[0052] Step 1: Cross-coating the TA21 titanium alloy slab with an anti-oxidation coating; the TA21 titanium alloy slab has a thickness of 160 mm, a width of 1000 mm, and a length of 1100 mm;

[0053] Step 2, the TA21 titanium alloy slab treated in step 1 is kept at a temperature of 880°C for 4 hours and then subjected to the first fire rolling to obtain a first rolled slab; the first fire rolling is unidirectional rolling, and the pass deformation rates of the first fire rolling 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 rate is 3m / s; the thickness of the first rolled slab is 25mm, the width is 1000mm, the start rolling temperature of the first fire rolling is 865°C, the final rolling temperature is 660°C, and the total deformation rate of the first fire rolling is 84%;

[0054] Step 3: cutting the first rolled slab obtained in step 2 to obtain a plurality of first intermediate slabs; the first intermediate slabs have a thickness of 25 mm, a width of 1000 mm, and a length of 1300 mm;

[0055] Step 4: The first intermediate slab obtained in step 3 is kept at a temperature of 860°C for 1h and then subjected to a second heat rolling, and the slab is returned to the furnace online for temperature compensation to obtain a second rolled slab; the deformation rates of the second heat rolling are 12.0%, 13.6%, 13.2%, 15.2%, and 14.3% respectively, the number of passes is 5, the rolling rate is 4m / s, and the rolling direction of the second heat rolling is parallel to the rolling direction of the first heat rolling in step 2, the starting rolling temperature of the second heat rolling is 840°C, the final rolling temperature is 620°C, and the total deformation rate of the second heat rolling is 52%; the thickness of the second rolled slab is 12mm and the width is 1000mm;

[0056] Step 5: cutting the second rolled slab obtained in step 4 to obtain a plurality of second intermediate slabs; the second intermediate slabs have a thickness of 12 mm, a width of 1000 mm, and a length of 1200 mm;

[0057] Step 6: quench the second intermediate slab obtained in step 5; the specific process of the quenching treatment is: keep the temperature at 960°C for 1 hour, the time from the second intermediate slab being taken out of the furnace to entering the water is not more than 10 seconds, and the water temperature is not more than 30°C;

[0058] Step seven, the second intermediate slab after quenching treatment in step six is ​​kept at a temperature of 810°C for 1.5h and then subjected to a third fire rolling to obtain a third rolled slab; the pass deformation rates of the third fire rolling are 16.7%, 20%, 23.8%, 23%, and 19.1% respectively, the rolling rate is 3m / s, and the rolling direction of the third fire rolling is perpendicular to the rolling direction of the second fire rolling in step four, the starting rolling temperature of the third fire rolling is 760°C, the final rolling temperature is 510°C, and the total deformation rate of the third fire rolling is 68%; the thickness of the third rolled slab is 3.8mm and the width is 1200mm;

[0059] Step 8: Cut the third rolled slab obtained in step 7 to obtain a plurality of third intermediate slabs; the third intermediate slabs have a thickness of 3.8 mm, a width of 1200 mm, and a length of 1400 mm;

[0060] Step 9: The third intermediate slab obtained in step 8 is kept at 720° C. for 1 hour to perform semi-finished product annealing treatment;

[0061] Step 10, cold rolling the third intermediate slab after the semi-finished product annealing treatment in step 9 to obtain a TA21 titanium alloy cold-rolled plate; 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 the rolling direction of the third hot rolling in step 7; the TA21 titanium alloy cold-rolled plate has a thickness of 1.2 mm, a width of 1200 mm, and a length of 3200 mm;

[0062] Step 11. Straighten the TA21 titanium alloy cold-rolled sheet obtained in step 10, keep it at 620°C for 1 hour for finished product annealing, and then air-cool it to room temperature to obtain a titanium alloy thin plate; the TA21 titanium alloy thin plate has a thickness of 1.5 mm, a width of 1200 mm, and a length of 3200 mm.

[0063] Figure 2 The metallographic structure diagram (500×) of the TA21 titanium alloy sheet prepared in this embodiment is shown in FIG. Figure 2It can be seen that the metallographic structure of the TA21 titanium alloy sheet is a uniform and fine structure without the presence of needle-like structure.

[0064] After testing, the room temperature tensile strength of the TA21 titanium alloy sheet prepared in this embodiment is 540MPa-550MPa, the yield strength is 500MPa-510MPa, the elongation after fracture is 32%-40%, the bending meets 2T, 90°, the low-magnification structure has no metal and non-metal inclusions and other visually visible defects, and the high-magnification structure has no needle-like structure. It meets the requirements of the enterprise's "Technical Conditions for TA21 Titanium Alloy Sheets for Aviation Use".

[0065] In summary, the metallographic structure of the TA21 titanium alloy prepared in this embodiment meets the structural requirements of the TA21 single-phase titanium alloy and has excellent mechanical properties.

[0066] Example 3

[0067] This embodiment includes the following steps:

[0068] Step 1: Cross-coating the TA21 titanium alloy slab with an anti-oxidation coating; the TA21 titanium alloy slab has a thickness of 180 mm, a width of 1100 mm, and a length of 1400 mm;

[0069] Step 2, the TA21 titanium alloy slab treated in step 1 is kept at a temperature of 900°C for 5h and then subjected to the first fire rolling to obtain a first rolled slab; the first fire rolling is unidirectional rolling, and the pass deformation rates of the first fire rolling are 13.6%, 17.1%, 22.4%, 22.1%, 19.7%, 19.3%, 19.6%, and 18.9% respectively, the number of passes is 8, and the rolling rate is 4m / s; the thickness of the first rolled slab is 30mm, the width is 1100mm, the start rolling temperature of the first fire rolling is 875°C, the final rolling temperature is 670°C, and the total deformation rate of the first fire rolling is 83%;

[0070] Step 3: cutting the first rolled slab obtained in step 2 to obtain a plurality of first intermediate slabs; the first intermediate slabs have a thickness of 30 mm, a width of 1100 mm, and a length of 1600 mm;

[0071] Step 4, the first intermediate slab obtained in step 3 is kept at a temperature of 880°C for 1h and then subjected to a second heat rolling, and the slab is returned to the furnace online for temperature compensation to obtain a second rolled slab; the deformation rates of the second heat rolling are 10%, 11.1%, 12.5%, 11.4%, 10.2%, and 10.2% respectively, the number of passes is 6, the rolling rate is 4m / s, and the rolling direction of the second heat rolling is parallel to the rolling direction of the first heat rolling in step 2, the starting rolling temperature of the second heat rolling is 860°C, the final rolling temperature is 630°C, and the total deformation rate of the second heat rolling is 50%; the thickness of the second rolled slab is 15mm and the width is 1100mm;

[0072] Step 5: cutting the second rolled slab obtained in step 4 to obtain a plurality of second intermediate slabs; the second intermediate slabs have a thickness of 15 mm, a width of 1100 mm, and a length of 1300 mm;

[0073] Step 6: quench the second intermediate slab obtained in step 5; the specific process of the quenching treatment is: keep the temperature at 980°C for 0.5h, the time from the second intermediate slab being taken out of the furnace to entering the water is not more than 10s, and the water temperature is not more than 30°C;

[0074] Step seven, the second intermediate slab after quenching treatment in step six is ​​kept at a temperature of 830°C for 2h and then subjected to a third rolling to obtain a third rolled slab; the pass deformation rates of the third rolling are 13.3%, 15.4%, 18.2%, 18.9%, 20.5%, 19.0%, and 14.9% respectively, the rolling rate is 4m / s, and the rolling direction of the third rolling is perpendicular to the rolling direction of the second rolling in step four, the starting rolling temperature of the third rolling is 780°C, the final rolling temperature is 520°C, and the total deformation rate of the third rolling is 73%; the thickness of the third rolled slab is 4mm and the width is 1300mm;

[0075] Step 8: Cut the third rolled slab obtained in step 7 to obtain a plurality of third intermediate slabs; the third intermediate slabs have a thickness of 4.0 mm, a width of 1300 mm, and a length of 1500 mm;

[0076] Step 9: The third intermediate slab obtained in step 8 is subjected to semi-finished product annealing treatment by keeping the temperature at 750° C. for 1 hour;

[0077] Step 10, cold rolling the third intermediate slab after the semi-finished product annealing treatment in step 9 to obtain a TA21 titanium alloy cold-rolled plate; 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 the rolling direction of the third hot rolling in step 7; the TA21 titanium alloy cold-rolled plate has a thickness of 2.0 mm, a width of 1300 mm, and a length of 2800 mm;

[0078] Step 11: subject the TA21 titanium alloy cold-rolled sheet obtained in step 10 to finished product annealing treatment at 650°C for 0.5h, and then air-cool it to room temperature to obtain a titanium alloy thin plate; the TA21 titanium alloy thin plate has a thickness of 2.0mm, a width of 1300mm, and a length of 2800mm.

[0079] Figure 3 The metallographic structure diagram (500×) of the TA21 titanium alloy sheet prepared in this embodiment is shown in FIG. Figure 3 It can be seen that the metallographic structure of the TA21 titanium alloy sheet is a uniform and fine structure without the presence of needle-like structure.

[0080] After testing, the room temperature tensile strength of the TA21 titanium alloy sheet prepared in this embodiment is 535MPa-545MPa, the yield strength is 502MPa-513MPa, the elongation after fracture is 34%-42%, the bending meets 2T, 80°, the low-magnification structure has no metal and non-metal inclusions and other visually visible defects, and the high-magnification structure has no needle-like structure. It meets the requirements of the enterprise's "Technical Conditions for TA21 Titanium Alloy Sheets for Aviation Use".

[0081] In summary, the metallographic structure of the TA21 titanium alloy prepared in this embodiment meets the structural requirements of the TA21 single-phase titanium alloy and has excellent mechanical properties.

[0082] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for rolling a TA21 titanium alloy sheet, characterized in that: The method comprises the following steps: Step 1: coating the surface of a TA21 titanium alloy slab with an anti-oxidation coating; the TA21 titanium alloy slab has a thickness of 140 mm to 180 mm, a width of 800 mm to 1100 mm, and a length of 800 mm to 1400 mm; Step 2, the TA21 titanium alloy slab treated in step 1 is subjected to a first heat rolling at a temperature of 880°C to 900°C to obtain a first rolled slab; the first heat rolling is unidirectional rolling, the pass deformation rate of the first heat rolling is 8% to 25%, the number of passes is 6 to 8, and the rolling rate is 3m / s to 4m / s; the thickness of the first rolled slab is 20mm to 30mm, and the width is 800mm to 1100mm; Step 3: cutting the first rolled slab obtained in step 2 to obtain a plurality of first intermediate slabs; the first intermediate slabs have a thickness of 20 mm to 30 mm, a width of 800 mm to 1100 mm, and a length of 1000 mm to 1600 mm; Step 4, the first intermediate slab obtained in step 3 is subjected to a second rolling at a temperature of 850°C to 880°C, and is returned to the furnace online for temperature compensation to obtain a second rolled slab; the deformation rate of the second rolling is 10% to 25%, the number of passes is 4 to 6, the rolling rate is 3m / s to 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 to 15mm, and the width is 800mm to 1100mm; Step 5: cutting the second rolled slab obtained in step 4 to obtain a plurality of second intermediate slabs; the second intermediate slabs have a thickness of 10 mm to 15 mm, a width of 800 mm to 1100 mm, and a length of 1000 mm to 1300 mm; Step 6: quenching the second intermediate slab obtained in step 5; Step 7, the second intermediate slab after quenching in step 6 is subjected to a third heat rolling at a temperature of 800°C to 830°C to obtain a third rolled slab; the pass deformation rate of the third heat rolling is 10% to 25%, the rolling rate is 3m / s to 4m / s, and the rolling direction of the third heat rolling is perpendicular to the rolling direction of the second heat rolling in step 4, and the thickness of the third rolled slab is 3.6mm to 4mm, and the width is 1000mm to 1300mm; Step 8: Cut the third rolled slab obtained in step 7 to obtain a plurality of third intermediate slabs; the third intermediate slabs have a thickness of 3.6 mm to 4 mm, a width of 1000 mm to 1300 mm, and a length of 1000 mm to 1500 mm; Step nine, subjecting the third intermediate slab obtained in step eight to semi-finished product annealing treatment at a temperature of 700° C. to 750° C.; Step 10, cold rolling the third intermediate slab after the semi-finished product annealing treatment in step 9 to obtain a TA21 titanium alloy cold-rolled plate; the pass deformation rate of the cold rolling is 5% to 20%, and the rolling direction of the cold rolling is the same as the rolling direction of the third fire rolling in step 7; the TA21 titanium alloy cold-rolled plate has a thickness of 1.2 mm to 2.0 mm, a width of 1000 mm to 1300 mm, and a length of 2800 mm to 3200 mm; Step 11: subject the TA21 titanium alloy cold-rolled sheet obtained in step 10 to finished product annealing treatment, and then air-cool it to room temperature to obtain a titanium alloy thin plate; the TA21 titanium alloy thin plate has a thickness of 1.2 mm to 2.0 mm, a width of 1000 mm to 1300 mm, and a length of 2800 mm to 3200 mm.

2. The method for rolling a TA21 titanium alloy sheet according to claim 1, characterized in that: In step one, the surface of the TA21 titanium alloy slab is cross-coated with a TB920 anti-oxidation coating, and the direction of the last coating of the TB920 anti-oxidation coating is the direction of the first fire rolling in step two.

3. The method for rolling a TA21 titanium alloy sheet according to claim 1, characterized in that: The specific process of the first rolling in step 2 is: keeping warm at 880℃~900℃ for 3h~6h, the starting temperature of the first rolling is not less than 860℃, the final rolling temperature is not less than 650℃, and the total deformation rate of the first rolling is 60%~90%.

4. The method for rolling a TA21 titanium alloy sheet according to claim 1, characterized in that: The specific process of the second rolling in step 4 is: keeping warm at 850℃~880℃ for 1h~2h, the starting temperature of the second rolling is not less than 800℃, the final rolling temperature is not less than 550℃, and the total deformation rate of the second rolling is 50%~70%.

5. The method for rolling a TA21 titanium alloy sheet according to claim 1, characterized in that: The specific process of the quenching treatment in step six is: keep warm at 940℃~980℃ for 0.5h~1h, the time from the second intermediate slab being taken out of the furnace to entering the water is not more than 10s, and the water temperature is not more than 30℃.

6. The method for rolling a TA21 titanium alloy sheet according to claim 1, characterized in that: The specific process of the third rolling in step seven is: keeping warm at 800℃~830℃ for 1h~2h, the third rolling is reversing rolling, the starting rolling temperature of the third rolling is not less than 750℃, the final rolling temperature is not less than 450℃, and the total deformation rate of the third rolling is 50%~70%.

7. The method for rolling a TA21 titanium alloy sheet according to claim 1, characterized in that: The specific process of the semi-finished product annealing treatment in step nine is: keeping warm at 700° C. to 750° C. for 0.5 h to 1 h.

8. The method for rolling a TA21 titanium alloy sheet according to claim 1, characterized in that: The specific process of the finished product annealing treatment in step 11 is: keeping warm at 600° C. to 650° C. for 0.5 h to 1 h.

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