A production method for 7xxx series aluminum alloy narrow thin strip

Abstract

The present invention relates to a production method of a 7xxx series aluminum alloy narrow and thin strip, which makes full use of the characteristics of aluminum alloy rapid cooling continuous casting and continuous expansion extrusion process, and continuously expands and extrude the cast disc round rod material after homogenization treatment and uses its outlet waste heat to roll and coil it into a narrow strip, so as to replace the traditional semi-continuous ingot casting-hot rolling process to produce high-strength aluminum alloy coils and plates, so when producing large-volume heavy aluminum alloy coils and plates, it is not necessary to equip large-scale aluminum alloy semi-continuous flat ingot casting machines, ingot homogenization and heating furnaces and hot rolling mills and other equipment, and has the characteristics of low investment, short production process flow and energy saving, while improving the mechanical properties of products and product yield rate, it brings higher economic benefits to enterprises. The present invention is particularly suitable for the production of high-strength 7xxx series aluminum alloy narrow and thin strips for consumer electronic products with a thickness of less than 0.5 mm and a width of less than 300 mm.

Description

Technical Field

[0001] The invention belongs to the technical field of metal plastic processing, and in particular relates to a production method for a 7xxx series aluminum alloy narrow and thin strip. Background Art

[0002] In recent years, with the rapid development of the consumer electronics market, end consumers have not only continuously improved their functional requirements for consumer electronic products, but also their demands for the personality, texture and taste of product appearance. Simple, light, delicate, beautiful, durable and environmentally friendly have become the development trend of consumer electronic products. Aluminum alloy has the advantages of being strong and durable, easy to color, good heat dissipation, and continuously decreasing comprehensive costs. The use of appropriate processes can greatly improve the product grade, so it has been increasingly used in various consumer electronics fields such as smart phones, smart TVs, smart wearable devices, and tablet computers. 7xxx series Al-Zn-Mg-Cu alloy is a heat-treatable and strengthened aluminum alloy with excellent properties such as high specific strength, high specific stiffness, good processing performance, and high fracture toughness. It is widely used in high-tech fields such as aerospace. Because the strength of 7xxx series aluminum alloy is very strong and not easily bent by external forces, some high-end electronic brands have begun to use 7xxx series high-strength aluminum alloys for smart phones, smart TV frames, smart wearable devices, tablet computers, etc., which are 60% stronger than 6xxx series aluminum alloys. It features an ultra-thin body and an aluminum alloy shell to make it lighter and more beautiful.

[0003] At present, the traditional production process of aluminum alloy narrow coil thin strip is mainly semi-continuous ingot casting-hot rolling method, such as Figure 2 As shown in the figure, the traditional production process of large coil weight aluminum alloy sheet and strip includes: semi-continuous casting flat ingot - homogenization treatment - heating - hot rolling - cold rolling - intermediate annealing - slitting - narrow coil strip. If this process method is used to produce large coil weight (≥200Kg) aluminum alloy coil plate, it is necessary to use thick cast flat ingot, so large casting machine, homogenization and heating furnace and thermal machine are required to match it. Therefore, it leads to large investment in production equipment, large floor space, high energy consumption and other problems. At the same time, the geometric waste in the production process of slitting into narrow coil strip is also high, and the product yield is low. This process is only suitable for the production of large quantities of aluminum alloy sheet and strip, but not suitable for the production of high-strength 7xxx series aluminum alloy narrow and thin strips with a thickness of less than 0.5mm and a width of less than 300mm for consumer electronic products, taking into account both cost and economic benefits. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, combined with the process characteristics of continuous expansion extrusion deformation of aluminum alloys, the present invention proposes a production method for 7xxx series aluminum alloy narrow and thin strips, which fully utilizes the characteristics of aluminum alloy rapid cooling continuous casting and continuous expansion extrusion process, and continuously expands and extrude the cast disc round rod material after homogenization treatment and uses its outlet waste heat to roll it into coils and plates, so as to replace the traditional semi-continuous ingot casting-hot rolling process to produce high-strength aluminum alloy coils and plates, and does not require large-scale aluminum alloy semi-continuous flat ingot casting machines, ingot homogenization and heating furnaces and hot rolling mills and other equipment. It has the characteristics of low investment, short production process flow, high flexibility and energy saving, and is particularly suitable for the production of small-batch high-strength 7xxx series aluminum alloy narrow and thin strips.

[0006] (II) Technical solution

[0007] In a first aspect, the present invention provides a method for producing a 7xxx series aluminum alloy narrow and thin strip, comprising: a rapid cooling continuous casting process, a homogenization treatment process, a continuous expansion extrusion process, a residual heat rolling process, a coiling process, a cold rolling process and an intermediate annealing process;

[0008] The rapid cooling and continuous casting process comprises: rapidly cooling and continuously casting the molten aluminum alloy material into a round bar material with a diameter of 30-35 mm;

[0009] The homogenization treatment process comprises: keeping the round bar material at 460-480°C for 8-16 hours, cooling it in a furnace to 240-280°C, and then taking it out of the furnace and air cooling it;

[0010] The continuous expansion extrusion process comprises: continuously expanding and extruding into a narrow plate with a width of 40-300 mm through an expansion die cavity, and the outlet temperature of the expansion die cavity is set to 410-460° C.;

[0011] The residual heat rolling and coiling process comprises: at the outlet of the expansion die cavity, using a constant tension hot rolling mill to use the residual heat after continuous expansion extrusion to roll and deform the narrow plate, controlling the reduction rate to 20-50%, and coiling it into a narrow strip after rolling;

[0012] The cold rolling process includes: performing multiple cold rolling deformations on the narrow strip to reduce the thickness of the narrow strip, controlling the total cold rolling deformation rate to 30-60%, so that the thickness of the narrow strip reaches the thickness of the finished aluminum alloy narrow and thin strip;

[0013] After the cold rolling process, intermediate annealing treatment is carried out to produce narrow and thin strips of 7xxx series aluminum alloy.

[0014] Preferably, in the rapid cooling continuous casting process, the continuous casting temperature is controlled at 680-690°C and the casting speed is 600-750mm / min. The rapid cooling continuous casting may also include a peeling process to peel the round bar material to remove the oxide layer on the surface. After peeling, the diameter of the round bar material is 30-35mm.

[0015] Preferably, the rapid cooling continuous casting is horizontal continuous casting or upward continuous casting, and the casting cooling rate is greater than 200°C / s.

[0016] Preferably, the homogenization treatment condition is to keep the round rod material at 460-480°C for 8-16 hours, furnace cool it to 260°C, and then air cool it out of the furnace; in the continuous expansion extrusion process, the outlet temperature of the expansion mold cavity is set to 430-450°C.

[0017] Preferably, the continuous expansion extruder used in the continuous expansion extrusion process is a 600-type low-speed, high-torque aluminum alloy continuous expansion extruder, which adopts expansion die cavity extrusion and an extrusion wheel speed of 1-5 rpm.

[0018] Preferably, in the residual heat rolling process, a synchronous hot rolling mill with constant tension control is installed at the outlet of the expansion die cavity, and the synchronous hot rolling mill is used to roll and deform the narrow plate after continuous expansion and extrusion, and the reduction rate is controlled to be 30-40%, and the plate is rolled into a narrow strip after rolling.

[0019] Preferably, the total cold rolling deformation rate is controlled at 40-50% during the cold rolling process; the intermediate annealing conditions are: keeping at 360-420°C for 2h, cooling in the furnace to 260°C, and then air cooling out of the furnace.

[0020] Preferably, the cold rolling and intermediate annealing treatments of the narrow strip are repeated until the narrow strip reaches the finished thickness.

[0021] Preferably, after the intermediate annealing is completed, solid solution quenching, artificial aging and plate shape finishing treatment are also included.

[0022] Preferably, the thickness of the aluminum alloy narrow thin strip is ≤0.5mm and the width is ≤300mm. The aluminum alloy includes but is not limited to 7075, 7475, 7050, 7049, 7020, 7055 and other aluminum alloys, and a single roll of the produced aluminum alloy narrow thin strip can be ≥200Kg.

[0023] (III) Beneficial effects

[0024] (1) The present invention makes full use of the characteristics of aluminum alloy rapid cooling continuous casting and continuous expansion extrusion process, continuously expands and extrude the cast disc round rod material after homogenization treatment, and uses the residual heat at its outlet to roll and coil it into narrow strips, so as to replace the traditional semi-continuous ingot casting-hot rolling process to produce high-strength aluminum alloy coils and plates. Therefore, when producing large coil weight (≥200Kg) aluminum alloy coils and plates, there is no need to equip large aluminum alloy semi-continuous flat ingot casting machines, ingot homogenization and heating furnaces, hot rolling machines and other equipment, so that equipment investment costs, floor space and energy consumption costs can be reduced. It has the characteristics of low investment, equipment investment is less than 1 / 10 of that of traditional plate and strip production, short production process, high flexibility and energy saving, with energy saving of more than 20%.

[0025] (2) The 7xxx series aluminum alloy narrow and thin strip produced by the present invention has high mechanical properties and is particularly suitable for the production of high-strength 7xxx series aluminum alloy narrow and thin strips with a thickness of less than 0.5 mm and a width of less than 300 mm for consumer electronic products. It can reduce production costs, improve product mechanical properties, and bring higher economic benefits to enterprises. Compared with similar products, it has higher tensile strength, yield strength, elongation and hardness Hv.

[0026] (3) The production method does not include a slitting process, and except for the oxide layer peeling, almost no geometric waste is generated, and the product yield rate is high. The present invention can produce a single roll of aluminum alloy narrow and thin strips with a weight of several hundred to several thousand, and there is no upper limit in theory, and it is suitable for producing 7075, 7475, 7050, 7049, 7020, 7055 and other aluminum alloy narrow and thin strips. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of the method for producing 7xxx series aluminum alloy narrow and thin strip.

[0028] Figure 2 The figure is a flow chart of the traditional production process of aluminum alloy narrow coil thin strip, which is mainly a semi-continuous ingot casting-hot rolling method. DETAILED DESCRIPTION

[0029] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0030] like Figure 1 As shown, the present invention provides a method for producing a 7xxx series aluminum alloy narrow and thin strip, including: a rapid cooling continuous casting process, a homogenization treatment process, a continuous expansion extrusion process, a residual heat rolling process, a coiling process, a cold rolling process and an intermediate annealing process.

[0031] Specifically, the aluminum alloy molten material is firstly cast into a round bar with a diameter of 30-35mm by rapid cooling, and the round bar is kept at 460-480℃ for 8-16h and furnace cooled to 240-280℃ before being taken out of the furnace for air cooling; then, it is continuously expanded and extruded into a narrow plate with a width of 40-300mm through an expansion die cavity, and the outlet temperature of the expansion die cavity is set to 410-460℃; at the outlet of the expansion die cavity, a constant tension hot rolling mill is used to use the residual heat after continuous expansion and extrusion to roll and deform the narrow plate, and the reduction rate is controlled to be 20-50%, and after rolling, it is rolled into a narrow strip; the narrow strip is subjected to multiple cold rolling deformations to reduce the thickness of the narrow strip, and the total cold rolling deformation rate is controlled to be 30-60%, so that the thickness of the narrow strip reaches the finished thickness of the aluminum alloy narrow thin strip, and intermediate annealing is performed to obtain 7xxx series aluminum alloy narrow thin strip. Among them, cold rolling and intermediate annealing can be repeated until the narrow strip reaches the finished thickness.

[0032] Preferably, in the rapid cooling continuous casting process, the continuous casting temperature is controlled at 680-690° C., and the casting speed is 600-750 mm / min, more preferably 650-700 mm / min.

[0033] Preferably, the rapid cooling continuous casting is horizontal continuous casting or upward continuous casting, and the casting cooling rate is greater than 200°C / s.

[0034] Preferably, the homogenization treatment condition is to keep the round rod material at 460-480°C for 8-16h, furnace cool it to 260°C, and then take it out of the furnace and air cool it. Preferably, after the insulation is completed, the furnace is cooled to 260°C, and then taken out of the furnace and air cooled.

[0035] Among them, the homogenization temperature should not be too high, otherwise it will cause overburning, and it should not be lower than this range, otherwise the solid solution temperature of the strengthening phase will not be reached. Generally speaking, the homogenization time of large plate ingots needs to be more than 24 hours, but for the rod material of the rapid cooling and continuous casting of the present invention, due to the small diameter of the rod material and the high cooling rate, its structural uniformity is better, so the homogenization time is controlled within 8-16 hours, which can achieve a good homogenization effect and save energy. During the period from the end of insulation to the furnace cooling to 240-280℃, the insulation effect of the furnace body can be used to prevent the quenching effect caused by excessive cooling speed, which will reduce the extrusion processing performance of the aluminum alloy; if the furnace temperature is higher than 280℃, the quenching effect still exists, which reduces the extrusion processing performance of the aluminum alloy, and if the furnace temperature is lower than 240℃, it is not conducive to saving energy and the insulation requirements of the furnace body are too high, which will also increase costs.

[0036] Preferably, the narrow plate with a width of 40-300 mm is formed by continuously expanding the die cavity, and the outlet temperature of the expanded die cavity is set to 410-460°C, preferably 430-450°C. The setting of the outlet temperature is directly related to the continuous expansion extrusion temperature. The outlet temperature should not be set too high, otherwise cracks will be generated in the extruded plate, and too low an outlet temperature is not conducive to residual heat rolling deformation.

[0037] Preferably, the continuous expansion extruder used in the continuous expansion extrusion process is a 600-type low-speed, high-torque aluminum alloy continuous expansion extruder, which adopts expansion die cavity extrusion, and the extrusion wheel speed is 1-5rpm, preferably 1.5-3rpm.

[0038] Preferably, in the residual hot rolling process, a synchronous hot rolling mill with constant tension control is installed at the outlet of the expansion die cavity, and the synchronous hot rolling mill is used to roll and deform the narrow plate after continuous expansion and extrusion, and the reduction rate is controlled to be 20-50%, preferably 30-40%, and the narrow strip is rolled after rolling to improve the efficiency of the subsequent cold rolling process. In the residual hot rolling process, the rolling cracking phenomenon caused by excessive reduction rate should be avoided.

[0039] Preferably, the total cold rolling deformation rate is controlled to be 30-60%, preferably 40-50% in the cold rolling process. In the cold rolling process, the total deformation rate is controlled not to exceed 60% to avoid work hardening and cracks caused by excessive deformation rate.

[0040] Preferably, the intermediate annealing conditions are: 360-420℃ for 2h, furnace cooling to 240-280℃ (preferably 260℃), and then air cooling. If the intermediate annealing temperature is too high, it is easy to cause recrystallization and grain growth, which will reduce the mechanical properties. If the intermediate annealing temperature is too low, it will not achieve the effect of restoring softening, which is not conducive to repeated cold rolling. For the consideration of the furnace temperature, please refer to the furnace temperature of the above homogenization treatment.

[0041] Preferably, the cold rolling and intermediate annealing treatment of the narrow strip is repeated until the narrow strip reaches the finished thickness. The intermediate annealing occurs in the middle of the multi-pass cold rolling process, and the narrow strip is first cold rolled for multiple passes, then intermediate annealed, and then cold rolled for multiple passes until the narrow strip reaches the finished thickness.

[0042] Preferably, after the intermediate annealing is completed, solution quenching, artificial aging and plate shape finishing treatment are also included to improve the dimensional accuracy and mechanical properties of the finished aluminum alloy narrow and thin strip.

[0043] Preferably, the thickness of the aluminum alloy narrow and thin strip is ≤0.5 mm, and the width is ≤300 mm. The coil weight of the produced aluminum alloy narrow and thin strip can be ≥200 kg. The aluminum alloy includes but is not limited to 7075 aluminum alloy.

[0044] The present invention is further described below with reference to specific embodiments and comparative examples.

[0045] Example 1

[0046] This embodiment provides a method for producing a 7xxx series aluminum alloy narrow and thin coil, which is a 7075 aluminum alloy narrow and thin coil with a material of 0.48×287 mm and a coil weight of ≥200 kg, and is used for a certain brand of tablet computer. The production process of the aluminum alloy narrow and thin coil is as follows:

[0047] (1) Rapid cooling continuous casting: 99.7% aluminum ingot, zinc ingot, magnesium ingot and Al-5Mn, Al-5Cr, Al-10Cu master alloys were used. The weight ratio of each alloy was calculated according to the chemical composition range of 7075 aluminum alloy. The ingredients were mixed according to this ratio. After melting, refining, heat preservation and online filtration in a double 1000Kg gas melting furnace, samples were taken for alloy chemical composition detection, as shown in Table 1. 7075 aluminum alloy disc round rod billets with a diameter of φ 34mm and a weight of 363Kg were continuously cast by horizontal continuous casting. The continuous casting temperature was controlled at 680-690℃ and the casting speed was set to 700mm / min. At this casting speed, the cooling rate of rapid cooling continuous casting was greater than 200℃ / s.

[0048] (2) The round bar material is kept at 465°C for 10 hours, furnace cooled to 260°C, and then air cooled to make the round bar material uniform.

[0049] (3) The aluminum alloy cast disc round rod with a diameter of φ34 mm was peeled to a diameter of φ30 mm, and then extruded into 10×295 mm 7075 aluminum alloy plates using continuous expansion extrusion on a 600 type continuous expansion extruder, with an outlet temperature of about 430°C.

[0050] (4) The aluminum alloy sheet after continuous expansion and extrusion is sent to a φ450×400mm two-roll aluminum alloy irreversible hot rolling mill through a guide roller, and the residual heat at the outlet of continuous expansion and extrusion is used to roll the sheet into a 7075 aluminum alloy coil with a thickness of 6mm, with a reduction rate of 40%. After rolling, it is rolled into a narrow strip.

[0051] (5) The 7075 aluminum alloy narrow strip with a thickness of 6 mm was subjected to cold rough rolling (initial thickness 6.0 mm, thickness reduced to 4.8 mm after the first cold rolling, thickness reduced to 3.8 mm after the second cold rolling, thickness reduced to 3.0 mm after the third cold rolling, (total cold rolling reduction rate was 50%) on a φ400×420 mm two-roll aluminum alloy reversible cold rolling mill (with double coiling) according to the following cold rolling pass arrangement 6.0-4.8-3.8-3.0 (the initial thickness was 6.0 mm, thickness reduced to 4.8 mm after the first cold rolling, thickness reduced to 3.8 mm after the second cold rolling, thickness reduced to 3.0 mm after the third cold rolling, (total cold rolling reduction rate was 50%), and then intermediate annealing was carried out in a box annealing furnace. The annealing process was 415°C for 2 h, furnace cooling to 260°C and air cooling.

[0052] Then, on a φ230 / φ550×450mm four-roll aluminum alloy reversible cold rolling mill (with double coiling), the following cold rolling and intermediate annealing process is 3.0-2.2-1.7-1.4-1.2 annealing (415℃ / 2h)-1-0.8-0.65-0.55-0.48 to the finished product thickness, specifically: initial thickness 3.0mm, after the first cold rolling, the thickness is reduced to 2.2mm, the second cold rolling, the thickness is reduced to 1.7mm, the third cold rolling, the thickness is reduced to 1.4mm, the fourth cold rolling, the thickness is reduced to 1.2mm (the total cold rolling reduction is 60%). At this time, an intermediate annealing is required, that is, keeping at 415℃ for 2h to eliminate the internal stress generated during the cold deformation process and restore some of the plasticity of the material so that the subsequent cold rolling operation can be continued without breaking. Continue the fifth cold rolling, the thickness is reduced to 1.0mm, the sixth cold rolling, the thickness is reduced to 0.8mm, the seventh cold rolling, the thickness is reduced to 0.65mm, the eighth cold rolling, the thickness is reduced to 0.55mm, the ninth cold rolling, the thickness reaches the finished product thickness of 0.48mm (the total cold rolling reduction rate is 60%).

[0053] (6) T6 treatment: keep at 475℃ for 1h, water quench, and then artificial aging: keep at 120℃ for 24h.

[0054] Comparative Example 1

[0055] A 7075 aluminum alloy hot-rolled coil with a thickness of 6 mm produced by a conventional large-size semi-continuous casting flat ingot-hot rolling method was purchased from the market and cut into narrow coils with a width of 298 mm. The chemical composition of the coils is shown in Table 1. The purchased 7075 aluminum alloy hot-rolled coil with a thickness of 6 mm was cold-rolled and intermediate-annealed according to the same method and conditions as step (5) in Example 1 until a finished product thickness of 0.48 mm was obtained, and then T6 treatment (water quenching at 475°C for 1 h + artificial aging at 120°C for 24 h) was performed.

[0056] Table 1: Main chemical compositions of Example 1 and commercially available 7075 aluminum alloy (weight percentage %)

[0057]

[0058] The T6 mechanical properties of the 7075 aluminum alloy narrow thin strips of Example 1 and Comparative Example 1 are tested. The test results are shown in Table 2.

[0059] Table 2: Comparison of mechanical properties of aluminum alloy narrow thin strips in T6 state between Example 1 and Comparative Example 1

[0060] product Tensile strength / MPa Yield strength / MPa Elongation A50 / % Hv Example 1 572 503 11.6 188 Comparative Example 1 557 491 10.8 182

[0061] As can be seen from the above table, the aluminum alloy narrow thin coil produced by the method of the present invention has higher tensile strength, yield strength, elongation and hardness Hv than similar processed products. The method is very suitable for the production of high-strength 7xxx series aluminum alloy narrow thin strips with a thickness of less than 0.5 mm and a width of less than 300 mm for consumer electronic products.

[0062] Furthermore, the cost of producing a 300Kg single roll of aluminum alloy narrow thin coil is estimated. The two cost comparisons are shown in Table 3:

[0063] Table 3: Comparison of production costs of single-roll aluminum alloy narrow and thin coils

[0064] product Processing cost (yuan / roll) Example 1 6000-7200 Comparative Example 1 9000-135000

[0065] It can be seen from Table 3 that the production method of the present invention can reduce production costs, and the production method does not include a slitting process, does not generate excessive geometric waste, has a high product yield, and is more flexible in production, with order production of as little as a few hundred kilograms.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features therein may be replaced by equivalents. These modifications or replacements, or the technical features in the above embodiments may be combined in the manner described in the embodiments if they do not conflict with each other, and these modifications, replacements or combinations do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing a 7xxx series aluminum alloy narrow thin strip, characterized in that: include: Rapid cooling continuous casting process, homogenization process, continuous expansion extrusion process, residual heat rolling process, coiling process, cold rolling process and intermediate annealing process; The rapid cooling continuous casting process includes: rapidly cooling and continuously casting the molten aluminum alloy material into a round bar material with a diameter of 30-35 mm; The homogenization process includes: keeping the round bar material at 460-480℃ for 8-16h, cooling it in the furnace to 240-280℃, and then cooling it in the air; The continuous expansion extrusion process includes: continuously expanding and extruding into a narrow plate with a width of 40-300 mm through an expansion die cavity, and the outlet temperature of the expansion die cavity is set to 410-460° C.; The residual heat rolling and coiling process includes: at the outlet of the expansion die cavity, using a constant tension hot rolling mill to use the residual heat after continuous expansion extrusion to roll and deform the narrow plate, controlling the reduction rate to 30-40%, and coiling it into a narrow strip after rolling; The cold rolling process includes: performing multiple cold rolling deformations on the narrow strip to reduce the thickness of the narrow strip, controlling the total cold rolling deformation rate to 30-60%, so that the thickness of the narrow strip reaches the thickness of the finished aluminum alloy narrow and thin strip; After the cold rolling process, intermediate annealing is carried out. The conditions of intermediate annealing are: keeping at 360-420℃ for 2h, cooling in the furnace to 260℃, and then air cooling. After the intermediate annealing is completed, it also includes solid solution quenching, artificial aging and plate shape finishing treatment to obtain 7xxx series aluminum alloy narrow and thin strips.

2. The production method according to claim 1, characterized in that In the rapid cooling continuous casting process, the continuous casting temperature is controlled at 680-690° C. and the casting speed is 600-750 mm / min.

3. The production method according to claim 1, characterized in that The rapid cooling continuous casting is horizontal continuous casting or upward continuous casting, and the casting cooling speed is greater than 200°C / s.

4. The production method according to claim 1, characterized in that The homogenization treatment conditions are to keep the round rod material at 460-480°C for 8-16 hours, cool it in the furnace to 260°C, and then air-cool it; in the continuous expansion extrusion process, the outlet temperature of the expansion cavity is set to 430-450°C.

5. The production method according to claim 1, characterized in that: The continuous expansion extruder used in the continuous expansion extrusion process is a 600-type low-speed, high-torque aluminum alloy continuous expansion extruder, which adopts expansion die cavity extrusion, and the extrusion wheel speed is 1-5rpm.

6. The production method according to claim 1, characterized in that: In the residual hot rolling process, a synchronous hot rolling mill with constant tension control is installed at the outlet of the expansion die cavity. The synchronous hot rolling mill is used to roll and deform the narrow plate after continuous expansion and extrusion, and then coiled into a narrow strip after rolling.

7. The production method according to claim 1, characterized in that: In the cold rolling process, the total cold rolling deformation rate is controlled to be 40-50%.

8. The production method according to claim 1, characterized in that: The cold rolling and intermediate annealing treatments of the narrow strip are repeated until the narrow strip reaches the finished thickness.

9. The production method according to claim 1, characterized in that: The aluminum alloy narrow thin strip has a thickness of ≤0.5 mm and a width of ≤300 mm.

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