A method for preparing high-elongation cast-rolled 3003 aluminum alloy strip

Abstract

The present invention discloses a method for preparing a high-elongation cast-rolled 3003 aluminum alloy plate and strip. The method comprises alloy blending, producing a cast-rolled billet, high-temperature pre-annealing the cast-rolled billet, a first recrystallization annealing, a second recrystallization annealing, and finished product annealing to obtain a 3003 aluminum alloy plate and strip having a thickness of 0.20-0.30 mm and an elongation of ≥35%. The method is a process improvement based on a conventional cast-rolling method. The finished 3003 aluminum alloy plate and strip is produced by shortening the length of the cast-rolling zone, reducing the cast-rolling speed, and increasing the cast-rolling plate thickness. The cast-rolled billet is subjected to a high-temperature preheating annealing treatment, and the first two cold rolling passes are subjected to a first recrystallization annealing and a second recrystallization annealing treatment, respectively. Finally, the cold rolling process produces a 3003 aluminum alloy plate and strip that meets the requirements for pipeline materials. This method simplifies the production process, saves energy, and reduces costs, broadens the range of target products of existing cast-rolling equipment, and improves production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy production, and in particular to a method for preparing a high-elongation cast-rolled 3003 aluminum alloy plate and strip. Background Art

[0002] Aluminum is a silvery-white metal with a melting point of 660°C and a density of 2.7 g / cm 3 , has good corrosion resistance, electrical conductivity and thermal conductivity, high specific strength, good ductility and plasticity, and is easy to process and form. However, due to the low strength of pure aluminum, it is necessary to add alloying elements to strengthen it and make it into aluminum alloy products before it can be used in aerospace, transportation, construction, packaging and other fields. 3003 aluminum alloy is an Al-Mn series aluminum alloy with good rust resistance, formability, weldability and corrosion resistance. Because its mechanical properties are significantly better than conventional 1 series alloy aluminum products, it is often used to make parts used in humid environments, such as tanks for transporting liquid products, various pressure vessels and pipelines.

[0003] 3003 aluminum alloy strips with a thickness of 0.20-0.30mm are mainly used to make pipe products with large deformation, and their elongation is required to be ≥35%. At present, the production of 3003 aluminum alloy strips with a thickness of 0.20-0.30mm usually adopts conventional casting and rolling method (casting-cold rolling) or hot rolling method (ingot-hot rolling-cold rolling). Among them, conventional casting and rolling is a metal casting and rolling method in which liquid aluminum is continuously passed through rotating rollers (crystallizer) to form a blank and then rolled into a strip. Hot rolling is a metal processing process in which the metal blank is heated to a high temperature and then rolled. The two methods will encounter the following problems during the production process: (1) The elongation of 3003 aluminum alloy strips produced by conventional casting and rolling is It is only 20%, which cannot meet the requirement of ≥35% elongation of pipe plate; (2) When the conventional casting and rolling method is used, the cooling speed is faster than that of the traditional deep-well casting method. Most manganese atoms do not have time to diffuse, resulting in a highly supersaturated aluminum matrix. The aluminum matrix will precipitate in large quantities during the recrystallization annealing process after cold rolling, resulting in coarse and uneven recrystallization structure; (3) When the hot rolling method is used, it is necessary to carry out smelting, deep-well casting of flat ingots, flat ingot washing, homogenization annealing, hot rolling, cold rolling, annealing and other processes, which has the disadvantages of many production processes, long process cycle and high production cost. Compared with the hot rolling method, the conventional casting and rolling method consumes less energy and can save about 40% of energy. It has the advantages of small equipment investment, short production cycle, and is conducive to recycling waste and low transportation costs. It can partially or completely eliminate the hot rolling process with large investment and heavy equipment, thereby simplifying the production process and reducing costs. Summary of the Invention

[0004] The present invention provides a method for preparing a high-elongation cast-rolled 3003 aluminum alloy plate and strip, the purpose of which is to improve the conventional casting and rolling method, simplify the process, reduce costs, and prepare a 3003 aluminum alloy plate and strip for pipes with a thickness of 0.20-0.30 mm and an elongation of 35% or more.

[0005] To achieve its purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing a high-elongation cast-rolled 3003 aluminum alloy strip comprises the following steps:

[0007] S1: Alloy preparation: smelting aluminum ingots to obtain aluminum liquid, adding a master alloy and stirring when the aluminum liquid temperature reaches 730-760°C, and degassing and refining to obtain a 3003 aluminum alloy melt; the master alloy composition is as follows: Si≤0.20%, Fe:0.40-0.60%, Cu:0.12-0.15%, Mn:1.00-1.20%, and the remainder is Al;

[0008] S2: producing a cast billet; the 3003 aluminum alloy melt obtained in step S1 is cast and rolled to obtain a cast billet having a thickness of 10-12 mm; the casting zone has a length of 40-50 mm and a strip casting speed of 500-700 mm / min;

[0009] S3: High-temperature pre-annealing of the cast-rolled billet; the cast-rolled billet obtained in step S2 is fed into an annealing furnace for pre-annealing. After the temperature of the cast-rolled billet reaches 570-600°C, it is kept at this temperature for 5-7 hours and then removed from the furnace to obtain a pre-annealed cast-rolled billet; S4: First recrystallization annealing; the pre-annealed cast-rolled billet obtained in step S3 is cold-rolled from 10-12 mm to 7-8 mm to obtain a primary cold-rolled coil. The primary cold-rolled coil is unrolled and fed into an annealing furnace for a first recrystallization annealing. After the temperature of the primary cold-rolled coil reaches 550-580°C, it is kept at this temperature for 4-6 hours and then removed from the furnace to obtain a cold-rolled coil after the first recrystallization annealing;

[0010] S5: Second recrystallization annealing: The cold-rolled coil obtained in step S4 with a thickness of 7-8 mm after the first recrystallization annealing is subjected to a second cold rolling to a thickness of 3.5-4.5 mm to obtain a second cold-rolled coil. The second cold-rolled coil is unrolled and sent to an annealing furnace for a second recrystallization annealing. After the temperature of the second cold-rolled coil reaches 500-530°C, it is kept at this temperature for 4-6 hours and then taken out of the furnace to obtain a cold-rolled coil after the second recrystallization annealing.

[0011] S6: Finished product annealing; the cold-rolled coil obtained in step S5 after the second recrystallization annealing is subjected to several cold rolling passes to 0.20-0.30 mm to obtain a finished cold-rolled coil. The finished cold-rolled coil is unloaded and sent to an annealing furnace for finished product annealing. After the finished cold-rolled coil temperature reaches 350-400°C, it is kept warm for 3-5 hours and then taken out of the furnace. After cooling, a 3003 aluminum alloy sheet with a thickness of 0.20-0.30 mm and an elongation of ≥35% is obtained.

[0012] Furthermore, a smelting furnace is used for smelting the aluminum ingot in step S1.

[0013] Furthermore, the time for degassing and refining in step S1 is 30-40 minutes.

[0014] Furthermore, in step S2, a casting and rolling mill is used for casting and rolling the 3003 aluminum alloy melt.

[0015] Furthermore, the gap between the casting rolls of the casting mill is 10-11 mm, the roughness of the casting rolls is 1.03 μm, and the crown is 0.62.

[0016] Furthermore, the furnace gas temperature of the annealing furnace in steps S3, S4, S5 and S6 is 490-620°C.

[0017] Furthermore, a cold rolling mill is used in the cold rolling of steps S4, S5 and S6.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This method makes process improvements based on the conventional casting and rolling method. Specifically, the length of the casting and rolling zone is shortened from 55-65 mm to 40-50 mm, the casting and rolling speed is reduced from 800-900 mm / min to 500-700 mm / min, the thickness of the cast and rolled plate is increased from 6-7 mm to 10-12 mm, the casting and rolling cooling rate is reduced, and the casting and rolling billet is combined with high-temperature pre-annealing treatment. The first and second recrystallization annealing treatments are respectively performed in the two passes before cold rolling. Finally, the 3003 aluminum alloy plate and strip with a target thickness of 0.20-0.30 mm and an elongation of 35% are obtained by cold rolling. This method solves the limitation problem that only the hot rolling method (ingot casting-hot rolling-cold rolling) can produce 3003 aluminum alloy plates and strips that meet the requirements. Compared with the hot rolling method, the method achieves the goals of simplifying the production process, saving energy, and reducing costs, broadens the range of target products of existing casting and rolling equipment, and improves production efficiency.

[0020] 2. This method reduces manganese supersaturation by shortening the casting zone (the area where the aluminum melt is poured to the rolling centerline), reducing casting and cooling speeds, and then subjecting the cast-rolled billet to high-temperature pre-annealing to promote the precipitation of manganese atoms from the supersaturated solid solution, thereby reducing manganese precipitation during the subsequent recrystallization annealing process and solving the problem of coarse and uneven recrystallized structure. After cold rolling, the cast-rolled billet undergoes multiple recrystallization anneals for refinement, improving the elongation of 3003 aluminum alloy sheet and strip products. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a physical picture of the finished product of 3003 aluminum alloy plate and strip in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with embodiment:

[0023] In the following embodiments of the present invention, the smelting furnace is a 25t smelting furnace, the casting and rolling mill is a 1900mm inclined casting and rolling mill, the annealing furnace is a 40t high-temperature annealing furnace, and the cold rolling mill is an 1850mm cold rolling mill.

[0024] Example 1

[0025] The present invention provides a method for preparing a high-elongation cast-rolled 3003 aluminum alloy plate and strip, comprising the following steps:

[0026] S1: Alloy preparation: an aluminum ingot is placed in a smelting furnace to obtain molten aluminum. When the temperature of the molten aluminum reaches 750°C, a master alloy is added and electromagnetic stirring is performed for 30 minutes. After the master alloy is completely melted and uniformly dissolved in the molten aluminum, degassing and refining is performed for 30 minutes to obtain a 3003 aluminum alloy melt. The master alloy composition, by weight percentage, is Si: 0.12%, Fe: 0.56%, Cu: 0.14%, Mn: 1.15%, and the remainder is Al.

[0027] S2: producing a cast billet; the 3003 aluminum alloy melt obtained in step S1 was fed into a casting mill for casting to obtain a cast billet having a thickness of 12 mm; the casting roll gap of the casting mill was 10.8 mm, and when the casting nozzle was installed, the casting zone length was 43 mm, the casting strip speed was 580 mm / min, the casting roll roughness was 1.03 μm, and the convexity was 0.62;

[0028] S3: high temperature pre-annealing of the cast-rolled billet; the 12 mm cast-rolled billet obtained in step S2 is fed into an annealing furnace with a furnace gas temperature of 620°C for pre-annealing. After the temperature of the cast-rolled billet reaches 590°C, it is kept warm for 6 hours and then taken out of the furnace to obtain a pre-annealed cast-rolled billet;

[0029] S4: First recrystallization annealing; the pre-annealed cast-rolled billet obtained in step S3 is cold-rolled from 12 mm to 8 mm to obtain a primary cold-rolled coil. The primary cold-rolled coil is then unloaded and sent to an annealing furnace at a furnace gas temperature of 620°C for a first recrystallization annealing. After the temperature of the primary cold-rolled coil reaches 560°C, it is kept at this temperature for 5 hours and then removed from the furnace to obtain a cold-rolled coil with a thickness of 8 mm after the first recrystallization annealing.

[0030] S5: Second recrystallization annealing: The cold-rolled coil obtained in step S4 with a thickness of 8 mm after the first recrystallization annealing is subjected to a second cold rolling to 4.5 mm to obtain a second cold-rolled coil. The second cold-rolled coil is then unrolled and sent to an annealing furnace with a furnace gas temperature of 590°C for a second recrystallization annealing. After the temperature of the second cold-rolled coil reaches 530°C, it is kept at this temperature for 5 hours and then removed from the furnace to obtain a second recrystallization annealed cold-rolled coil with a thickness of 4.5 mm.

[0031] S6: Finished product annealing; The cold rolled coil with a thickness of 4.5 mm obtained in step S5 after the second recrystallization annealing is subjected to multiple cold rolling as shown in Table 1 to obtain a finished cold rolled coil of 0.30 mm. The finished cold rolled coil is then unloaded and sent to an annealing furnace with a furnace gas temperature of 490 ° C for finished product annealing. After the finished cold rolled coil temperature reaches 390 ° C, it is kept warm for 5 hours and taken out of the furnace after cooling to obtain the finished product. Figure 1 As shown, the finished product of 3003 aluminum alloy strip with a thickness of 0.30 mm;

[0032] S7: The finished 3003 aluminum alloy strip with a thickness of 0.30 mm obtained in step S6 was sampled and subjected to a tensile test. The test results are shown in Table 2.

[0033] Example 2

[0034] The present invention provides a method for preparing a high-elongation cast-rolled 3003 aluminum alloy plate and strip, comprising the following steps:

[0035] S1: Alloy preparation: an aluminum ingot is placed in a smelting furnace to obtain aluminum liquid. When the aluminum liquid temperature reaches 730°C, a master alloy is added and electromagnetic stirring is performed for 30 minutes. After the master alloy is completely melted and uniformly dissolved in the aluminum liquid, degassing and refining is performed for 36 minutes to obtain a 3003 aluminum alloy melt. The master alloy composition, by weight percentage, is Si: 0.20%, Fe: 0.40%, Cu: 0.12%, Mn: 1.20%, and the remainder is Al.

[0036] S2: producing a cast billet; the 3003 aluminum alloy melt obtained in step S1 was fed into a casting mill for casting and rolling to obtain a cast billet having a thickness of 11.4 mm; the casting roll gap of the casting mill was 10.2 mm, and when the casting nozzle was installed, the casting zone length was 40 mm, the casting strip speed was 500 mm / min, the casting roll roughness was 1.03 μm, and the convexity was 0.62;

[0037] S3: high temperature pre-annealing of the cast-rolled billet; the 11.4 mm cast-rolled billet obtained in step S2 is fed into an annealing furnace with a furnace gas temperature of 620°C for pre-annealing. After the cast-rolled billet temperature reaches 570°C, it is kept warm for 5 hours and then taken out of the furnace to obtain a pre-annealed cast-rolled billet;

[0038] S4: First recrystallization annealing; the pre-annealed cast-rolled billet obtained in step S3 is cold-rolled from 11.4 mm to 7.5 mm to obtain a first cold-rolled coil. The first cold-rolled coil is then unloaded and sent to an annealing furnace at a furnace gas temperature of 620°C for a first recrystallization annealing. After the temperature of the first cold-rolled coil reaches 550°C, it is kept at this temperature for 4 hours and then removed from the furnace to obtain a first recrystallization annealed cold-rolled coil with a thickness of 7.5 mm.

[0039] S5: Second recrystallization annealing: The cold-rolled coil obtained in step S4 with a thickness of 7.5 mm after the first recrystallization annealing is subjected to a second cold rolling to 4.0 mm to obtain a second cold-rolled coil. The second cold-rolled coil is then unrolled and sent to an annealing furnace with a furnace gas temperature of 590°C for a second recrystallization annealing. After the temperature of the second cold-rolled coil reaches 500°C, it is kept at this temperature for 4 hours and then removed from the furnace to obtain a second recrystallization annealed cold-rolled coil with a thickness of 4.0 mm.

[0040] S6: Finished product annealing; the cold-rolled coil with a thickness of 4.0 mm obtained in step S5 after the second recrystallization annealing is subjected to multiple cold rolling passes as shown in Table 1 to obtain a finished cold-rolled coil with a thickness of 0.25 mm. The finished cold-rolled coil is then unloaded and sent to an annealing furnace with a furnace gas temperature of 490°C for finished product annealing. After the finished cold-rolled coil temperature reaches 350°C, it is kept at this temperature for 3 hours and then removed from the furnace. After cooling, a finished 3003 aluminum alloy strip with a thickness of 0.25 mm is obtained.

[0041] S7: The finished 3003 aluminum alloy strip with a thickness of 0.25 mm obtained in step S6 was sampled and subjected to a tensile test. The test results are shown in Table 2.

[0042] Example 3

[0043] The present invention provides a method for preparing a high-elongation cast-rolled 3003 aluminum alloy plate and strip, comprising the following steps:

[0044] S1: Alloy preparation: an aluminum ingot is placed in a smelting furnace to obtain aluminum liquid. When the aluminum liquid temperature reaches 730°C, a master alloy is added and electromagnetic stirring is performed for 30 minutes. After the master alloy is completely melted and uniformly dissolved in the aluminum liquid, degassing and refining is performed for 40 minutes to obtain a 3003 aluminum alloy melt. The master alloy composition, by weight percentage, is Si: 0.13%, Fe: 0.60%, Cu: 0.15%, Mn: 1.00%, and the remainder is Al.

[0045] S2: producing a cast billet; the 3003 aluminum alloy melt obtained in step S1 was fed into a casting mill for casting to obtain a cast billet having a thickness of 10 mm; the casting roll gap of the casting mill was 11 mm, and when the casting nozzle was installed, the casting zone length was 50 mm, the casting strip speed was 700 mm / min, the casting roll roughness was 1.03 μm, and the convexity was 0.62;

[0046] S3: high temperature pre-annealing of the cast-rolled billet; the 10 mm cast-rolled billet obtained in step S2 is fed into an annealing furnace with a furnace gas temperature of 620°C for pre-annealing. After the cast-rolled billet temperature reaches 600°C, it is kept warm for 7 hours and then taken out of the furnace to obtain a pre-annealed cast-rolled billet;

[0047] S4: First recrystallization annealing; the pre-annealed cast-rolled billet obtained in step S3 is cold-rolled from 10 mm to 7.0 mm to obtain a primary cold-rolled coil. The primary cold-rolled coil is then unrolled and sent to an annealing furnace at a furnace gas temperature of 620°C for a first recrystallization annealing. After the temperature of the primary cold-rolled coil reaches 580°C, it is kept at this temperature for 6 hours and then removed from the furnace to obtain a cold-rolled coil with a thickness of 7.0 mm after the first recrystallization annealing.

[0048] S5: Second recrystallization annealing: The cold-rolled coil obtained in step S4 with a thickness of 7.0 mm after the first recrystallization annealing is subjected to a second cold rolling to 3.5 mm to obtain a second cold-rolled coil. The second cold-rolled coil is then unrolled and sent to an annealing furnace with a furnace gas temperature of 590°C for a second recrystallization annealing. After the temperature of the second cold-rolled coil reaches 520°C, it is kept at this temperature for 6 hours and then removed from the furnace to obtain a second recrystallization annealed cold-rolled coil with a thickness of 3.5 mm.

[0049] S6: Finished product annealing; the cold-rolled coil with a thickness of 3.5 mm obtained in step S5 after the second recrystallization annealing is subjected to multiple cold rolling passes as shown in Table 1 to obtain a finished cold-rolled coil with a thickness of 0.20 mm. The finished cold-rolled coil is then unloaded and sent to an annealing furnace with a furnace gas temperature of 490°C for finished product annealing. After the finished cold-rolled coil temperature reaches 400°C, it is kept at this temperature for 3 hours and then removed from the furnace. After cooling, a finished 3003 aluminum alloy strip with a thickness of 0.20 mm is obtained.

[0050] S7: The finished 3003 aluminum alloy strip with a thickness of 0.20 mm obtained in step S6 was sampled and subjected to a tensile test. The test results are shown in Table 2.

[0051] The thickness and processing rate of the multi-pass cold rolling in Examples 1-3 are shown in Table 1, and the tensile strength and elongation test results of the finished aluminum alloy strips are shown in Table 2:

[0052] Table 1 Thickness and processing rate of multi-pass cold rolling

[0053]

[0054] Table 2 Tensile strength and elongation of aluminum alloy strips

[0055]

[0056] From the analysis of Table 1-2, it can be seen that the present invention produces 3003 aluminum alloy plate and strip finished products by shortening the length of the casting and rolling zone, reducing the casting and rolling speed, and increasing the thickness of the cast and rolled plate. Combined with the high-temperature preheating annealing treatment of the cast and rolled billet, the first recrystallization annealing and the second recrystallization annealing are performed respectively in the first two passes of cold rolling. Finally, the 3003 aluminum alloy plate and strip finished products with a target thickness of 0.20-0.30 mm and an elongation of ≥35% are obtained by cold rolling, which meets the material requirements for pipelines.

Claims

1. A method for preparing high elongation cast-rolled 3003 aluminum alloy strip, characterized in that: The following steps are involved: S1: Alloy preparation: smelting aluminum ingots to obtain aluminum liquid, adding a master alloy and stirring when the aluminum liquid temperature reaches 730-760°C, and degassing and refining to obtain a 3003 aluminum alloy melt; the master alloy composition is as follows: Si≤0.20%, Fe:0.40-0.60%, Cu:0.12-0.15%, Mn:1.00-1.20%, and the remainder is Al; S2: producing a cast billet; the 3003 aluminum alloy melt obtained in step S1 is cast and rolled to obtain a cast billet having a thickness of 10-12 mm; the casting zone has a length of 40-50 mm and a strip casting speed of 500-700 mm / min; S3: high temperature pre-annealing of the cast-rolled billet; the cast-rolled billet obtained in step S2 is sent to an annealing furnace for pre-annealing. After the temperature of the cast-rolled billet reaches 570-600°C, it is kept at this temperature for 5-7 hours and then taken out of the furnace to obtain a pre-annealed cast-rolled billet; S4: First recrystallization annealing; cold rolling the pre-annealed cast-rolled billet obtained in step S3 from 10-12 mm to 7-8 mm to obtain a primary cold-rolled coil, unrolling the primary cold-rolled coil and sending it to an annealing furnace for the first recrystallization annealing. After the primary cold-rolled coil temperature reaches 550-580°C, it is kept at this temperature for 4-6 hours and then removed from the furnace to obtain a cold-rolled coil after the first recrystallization annealing; S5: Second recrystallization annealing: The cold-rolled coil obtained in step S4 with a thickness of 7-8 mm after the first recrystallization annealing is subjected to a second cold rolling to a thickness of 3.5-4.5 mm to obtain a second cold-rolled coil. The second cold-rolled coil is unrolled and sent to an annealing furnace for a second recrystallization annealing. After the temperature of the second cold-rolled coil reaches 500-530°C, it is kept at this temperature for 4-6 hours and then taken out of the furnace to obtain a cold-rolled coil after the second recrystallization annealing. S6: Finished product annealing; the cold-rolled coil obtained in step S5 after the second recrystallization annealing is subjected to several cold rolling passes to 0.20-0.30 mm to obtain a finished cold-rolled coil. The finished cold-rolled coil is unloaded and sent to an annealing furnace for finished product annealing. After the finished cold-rolled coil temperature reaches 350-400°C, it is kept warm for 3-5 hours and then taken out of the furnace. After cooling, a 3003 aluminum alloy sheet with a thickness of 0.20-0.30 mm and an elongation of ≥35% is obtained.

2. The method for preparing a high elongation cast-rolled 3003 aluminum alloy strip according to claim 1, wherein: In step S1, a smelting furnace is used for smelting the aluminum ingot.

3. The method for preparing a high-elongation cast-rolled 3003 aluminum alloy strip according to claim 2, wherein: The time for degassing and refining in step S1 is 30-40 minutes.

4. The method for preparing a high-elongation cast-rolled 3003 aluminum alloy strip according to claim 3, wherein: In step S2, a casting and rolling mill is used for casting and rolling the 3003 aluminum alloy melt.

5. The method for preparing a high elongation cast-rolled 3003 aluminum alloy strip according to claim 4, wherein: The casting roll gap of the casting rolling mill is 10-11 mm, the casting roll roughness is 1.03 μm, and the crown is 0.

62.

6. The method for preparing a high elongation cast-rolled 3003 aluminum alloy strip according to claim 5, wherein: The furnace gas temperature of the annealing furnace in steps S3, S4, S5 and S6 is 490-620°C.

7. The method for preparing a high elongation cast-rolled 3003 aluminum alloy strip according to claim 6, wherein: The cold rolling in steps S4, S5 and S6 is performed using a cold rolling mill.

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